Patent Application
20050183642
John N. Basic, Sr., in his U.S. Pat. Nos. 4,438,705, 4,475,469, 4,516,510, 4,706,578, 5,007,353, 5,209,169, and 5,413,715, (all of which are incorporated here as well as Mr. Basic's U.S. provisional patent application Ser. No. 60/353,850, filed Jan. 31, 2002) has significantly advanced the science of refuse incineration and showed how to appropriately control the “three T's” of combustion, viz., time, temperature, and turbulence. In the first and third of these patents, Mr. Basic has disclosed methods and equipment for incinerating that have achieved significant improvements in the efficiency for different types of refuse with the optional recovery of heat for further economic use. These two references establish three zones of combustion, make temperature measurements at significant locations, and alter the conditions of combustion to achieve the desired efficiency and environmental acceptability. Further, the patents accomplish their objectives while using bulk refuse, which simply means that it requires no processing before its introduction into the main combustion chamber. The system displays such versatility that it can adjust to remarkably different types and heat capacities of refuse and yet achieve environmentally sound incineration.
The principles related in these patents have such wide applicability that they do not even require refuse or even hydrocarbon liquids as a fuel. The discoveries find use in effectuating the combustion of hydrocarbon-containing fumes emanating from a generalized, undefined source. The patents specifically cover the use of the system for such fumes and without a main incinerator chamber.
Where a main chamber finds use, however, the patents show improvements for this component of an incinerator system as well. These improvements include, first, a stepped hearth floor with the individual steps extending laterally in the direction that the refuse moves through the chamber and air nozzles located in the vertical faces, or risers, of the steps. As a separate consideration, the incinerator combustion chamber receives an approximately stoichiometric amount of oxygen for the chamber's burning contents, and the chamber's floor and volume bear general respective relationships to the heat content of the burning refuse. Separately, the air moving through the combustion chamber has an upper limit to its volume to avoid lifting unburned particles of refuse. Alternately, various dimensions of the chamber's wall bear specific relationships to each other for improved incineration.
In the second and fourth patents listed above, Mr. Basic showed how to convey material sitting on a floor, most likely a hearth floor in a main incinerator chamber. The patents disclose nonsinusoidal motion of the hearth or floor that actually pulses the material forward. The motion of the floor actually resembles the activity of shoveling snow or other material. In addition to imparting a general progression of the material, especially burning refuse, the pulsing motion accelerates and decelerates and thus also jostles the mass of refuse vigorously to increase the burning rate and effectiveness.
The first four patents of Mr. Basic discussed above established an entirely new regiment for the incineration of refuse. They gave the essential conditions for the incineration of the waste themselves and showed how to move bulk refuse through the main combustion chamber to facilitate the process. With these parameters established, Mr. Basic then set to work to refine and improve the system that he had developed. In the process, he increased the sophistication of his incinerator system by an order of magnitude and its ability to reliably handle different types of refuse from those even contemplated previously. The issuance of the last three patents above justly rewarded his subsequent efforts.
In the earliest of these, Mr. Basic sets forth various incinerator improvements. Amongst these is the concept of splitting the reburn tunnel into two parallel reburn sections, each capable of performing the same functions on fumes emanating from a source such as the main combustion chamber. The control provided by two smaller reburn sections dramatically increases the control over the three T's of combustion.
As a separate aspect, the patent places an “excitor” in the reburn tunnel. The excitor actually reduces the cross-sectional area in the center of the tunnel where the mass flow of the flue gas is located and forces the flume gasses to pass around it. The shortened distance between the gas molecules and a wall, be it the outer or excitor wall, and the concomitant reradiation of heat give dramatically improved control over the three T's. The excitor may, in addition, provide nozzles introducing air to the tunnel for temperature and time control as well as assuring sufficient oxygen for complete combustion. Other aspects of the excitor include providing the air through the excitor's supports in the reburn tunnel and assuring that the excitor exterior has a low thermal conductivity to retain the generated heat. Additionally, the patent has shown that placing a damper at the outlet of the reburn tunnel gives even further control over the time of the combustion.
The next patent, U.S. Pat. No. 5,209,169, covers an entirely new feature placed into the combustion chamber having a hearth floor. Specifically, the combustion chamber may include a grate located adjacent to the inlet door and above the hearth. This grate will hold waste having either a high moisture or a high B.T.U. content. In the former case, the material dries while on the grate. In the latter, some of the volatile hydrocarbons burn or are driven off to prevent overheating and possible slagging on the hearth floor. In either case, the fixed hydrocarbon refuse falls through the grate to undergo thorough combustion on the hearth below. The refuse may do so while it still contains over half of its combustible hydrocarbons. Alternately, the grate may have openings of a particular size to accomplish the stated objectives. Moving the grate can jostle its contents to permit the desired burning and encourage dried or partially burned refuse to fall through to the hearth underneath.
A fluid passing through the grate, such as air or steam, may serve to cool the supporting metal structure of the grate, and a refractory may serve to further protect it. When the grate has air passing through it, the gas may then directly enter the combustion chamber to enhance the combustion efficiency. Thus, the air passing through the grate may actually possess two separate and distinct purposes. First, it cools the internal structure of the grate to prevent destruction by the combustion within the main chamber. Second, it may provide oxygen to the combustion fire itself.
The latest patent U.S. Pat. No. 5,413,715 listed above relates to a scoop for taking ashes out of a pool of water after the incinerator dumps them there. The scoop travels along a track, and when it reaches the bottom, its blade rotates and closes so that it can grab the ashes. After travelling upward on the track, the scoop opens, and the ashes drop out into a receptacle of some sort, like a tote bin or truck.
As seen from the above, the art and science of refuse incineration has advanced significantly under Mr. Basic's creativity and tutelage. As the recent history of incineration given above shows, each step forward opens new vistas for further improvements. A number of such advances are set forth below.
The above discussion of Mr. Basic's U.S. Pat. No. 5,209,169 indicated that a grate may sit above a hearth floor and hold refuse for drying and vaporizing volatile hydrocarbons. Passing air through the grate serves to maintain its temperature below a point where it may suffer harm or even destruction. This air may also provide oxygen-containing gas to the combustion fire.
However, subsequent work has shown the difficulty of controlling the two functions of the air in the grate to achieve maximum efficiency and cleanliness in the burning of refuse or any hydrocarbon stream. Thus, as discussed in Mr. Basic's patents U.S. Pat. Nos. 4,438,705 and 4,516,510, the main combustion chamber should generally receive stoichiomentric amounts of oxygen for the material undergoing burning there. This includes the underfire, overfire, and grate air. The portion specifically permitted for the grate may not suffice to adequately cool it to prevent harming it; alternately, adequately cooling through the grate may require an amount of air passing through it that would prove more than the optimal.
Furthermore, introducing air to both cool the grate and provide combustion air through its jets may overachieve its objective and decrease the temperature of the environs of the grate area to an unacceptably low point. This can happen even when the oxygen-containing air picks up some heat by passing through plenums surrounding various incinerator components. Also, the drying of wet refuse on the grate may actually require more heat than oxygen. This can prove particularly difficult to control.
A further and serious problem involving the use of the combustion air to control the temperature in the grate results from any possible disruption of the air supply itself. The deleterious disruption in the air supply to the grate may occur as a result of the failure of the blower fan supplying the air. As a further possibility, the installation may experience an electrical failure which, again, stops the supply of cooling air to the grate. Or, the operator, during shut-down, may simply turn off the air blower before the grate has a chance to adequately cool.
In any event, the loss of cooling air to the grate may result in its destruction. The grate sits in the extreme heat conditions of the incinerator chamber. It typically uses steel as its structural material, with a possible coating of refractory. At about 700 to 900 degrees Fahrenheit, steel loses 90 percent of its strength. Thus, the unexpected loss of adequate cooling air for whatever reason will likely lead to the severe misshapening and destruction of the grate itself.
On the other hand and as suggested above, providing adequate air to prevent heat damage to the grate may actually introduce excessive air into the refuse sitting on the grate. As indicated previously and in Mr. Basic's patents discussed above, placing the refuse on the grate may serve two purposes. First, it allows moisture in the refuse to vaporize from the refuse. Only when the refuse moisture content falls to around 50 percent can it actually ignite. Excessive air and its concomitant cooling effect upon the refuse may actually interfere with the removal of moisture from the material.
Further, placing refuse upon the grate may serve to drive off volatile hydrocarbons contained in it. This keeps the volatile HC's from falling onto the hearth floor below where they can flash into a “bloom” of fire, create localized overheating, and result in slagging due to the excessive heat. However, providing a large amount of air through the grate, possibly considered necessary to cool it, may allow the volatile HC's to actually burn on or near the grate itself. This can actually cause slagging on the grate due to the heat generated by the blooming fire of the volatilizing HC's. Controlling the cooling and the amount of air supplied to the volatilizing HC's also constitutes a very tricky and not always soluble task.
Divorcing the control of the air-grate's temperature from the air introduced into the incinerator chamber through the grate portends significant improvements in the system's operation and reliability. It will provide closer control of the conditions of incineration and the factors that could lead to the air-grate's destruction.
Generally, an incinerator system for bulk refuse and hydrocarbon-containing liquids may include a substantially enclosed chamber and a fire-resistant floor means within the chamber for holding and burning material on it. An inlet opening to the chamber allows for the introduction of solid bulk refuse and an outlet opening permits the egress of the gaseous products of combustion from the chamber.
A grate means having openings through it and located within the chamber, adjacent to the inlet opening and above the floor, holds refuse newly introduced through the inlet opening above the floor for a limited period of time. It then allows the refuse to drop through to the floor while burning. An oxygenating means couples to the grate means and introduces an oxygen-containing gas into the chamber through the grate means.
A significant improvement to the system includes regulating means coupled to the grate means. The regulating means controls the temperature of the grate means separate from the oxygenating means, the oxygen-containing gas, and the gaseous products of combustion.
In particular, an improved incinerator system may comprise temperature-controlling means, coupled to the grate means. The temperature-controlling means passes a fluid, other than the oxygen-containing gas and of a temperature within a predetermined range, through the grate means and separate from the oxygen-containing gas. As a specific choice, the fluid may take the form of a two-phase fluid of a temperature within a predetermined range. Because of its known characteristics, the steam-water combination represents a good selection for the two-phase system, although others may find use in particular circumstances. The steam-water two-phase flow in particular will continue to circulate without the need of electrical power. Thus, a loss of electricity will not destroy the steam-water combination's ability to protect the grate structure.
Since the fluid passes through the grate means separate from the oxygenating-containing gas, it may beneficially circulate through a closed system. This permits the treatment of the fluid for its temperature-controlling or other purposes and its subsequent return to the grate means.
In one particular situation, the incinerator system may include a boiler coupled to the outlet opening. The boiler captures heat contained in the gaseous products of combustion passing through the outlet opening and transfers it to a separate fluid. Usually, this fluid takes the form of two-phase steam. A significant improvement results when the temperature-controlling means couples to the boiler and the grate means and passes the two-phase fluid between the boiler and the grate means while still keeping it separate from the oxygen-containing gas. This accomplishes two separate though interrelated purposes. First, it permits the cooling fluid to rid itself of excess heat that it may have acquired during its passage through the grate means. Second, it permits the capture of the heat acquired by the fluid for economically beneficial use elsewhere.
Regardless of which of the specific features discussed above find use in a particular incinerator system, the temperature-controlling fluid, when used, passes through the grate means separate from the oxygenating-containing gas. An advanced structure for accomplishing the passage of the fluid without mixing with the oxygen-containing gas assumes the form of a “membrane tube wall”. The membrane tube wall constitutes part of the grate means and is formed into a conduit from relatively thin sections, or plates, of substantially heat conducting material. The wall then has at least two spaced-apart, substantially fluid-tight tubules formed from substantially heat conducting material and in thermal contact with the thin plate, or fin, sections of metal. As discussed below, the temperature-controlling fluid passes through the tubules and effects a substantial degree of control over their temperature. This controlled temperature then passes to the other parts of the wall because of its construction from a substantially-heat conducting material.
In the typical construction, the thin sections and the tubules are welded to each other to form an integral whole. Moreover, two of the tubules are in fluid-tight, fluid communication with each other. In fact, the wall will typically have an even number of tubules. This allows for their connections to each other in units of two tubules each. In each pair, one tubule takes the fluid entering the grate means. The fluid then passes from the first tubule to the second in the pair from which it ultimately leaves the grate means.
A particularly useful form of the membrane tube wall has the shape of a conduit. To achieve this, the membrane tube wall may curve around into a circular cross section to form an enclosed cylindrical tube. The tubules run parallel to the axis of the tube. The oxygen-containing gas then passes through the tube wall's interior and exits through openings, for example nozzles, through the tube. The control of the tube's temperature permits the use of very hot oxygen-containing gasses. As discussed below, such gasses may be or include flue gasses from the incinerator chamber which will still have a content of some oxygen. To take advantage of the closed cylinder-shaped membrane tube wall, the grate means may take the form of a plurality of grate arms, with each of the arms comprising an enclosed membrane tube wall in the form of a conduit. As stated above, the oxygenating means introduces the oxygen-containing gas through a plenum formed from the membrane tube wall.
The temperature controlling feature of the grate means obviates the necessity for materials that can themselves withstand the heat generated by the combustion. It also dispenses with heat-protective materials that themselves have difficulty living in the combustion temperatures. As a consequence, materials such as steel that lose their strength at such high temperatures may find use even without additional protection, such as refractory coatings, from the temperatures encountered. Accordingly, the grate means may comprises at least one passageway through which the oxygen-containing gas passes prior to being introduced into the chamber. The passageway may then have a composition of steel, and at least a portion of the steel passageway is directly exposed to the combustion occurring within the chamber. The remainder of the passageway may still have a refractory or other coating to protect it from abrasion damage from the refuse or other material placed upon it or contacting it in other fashions.
The flue gas from an incinerator represents a source of heat. However, the products of combusting refuse often contain one or more severely corrosive components, especially chlorine at higher temperatures or hydrochloric acid at lower temperatures. Either of these could well have a destructive effect upon metal components of the blower used to handle the movement of the flue gas. This would appear to limit the flue gas' potential for subsequent use as a heat source in the incinerator itself and especially in the grate means.
However, the flue gas may have several properties that make it particularly desirable for use as part or all of the oxygen-containing gas passing through the grate means into the combustion chamber and specifically into the refuse on the grate means itself. First, the flue gas has a substantial moisture content as a result of the combustion process. The water molecules impart a high specific heat to the gas. This, in turn, allows the flue gas to impart more heat rapidly to the refuse sitting on the grate means.
Further, the flue gas, because it has already experienced use in combustion, has a lower oxygen content than, for example, air. As a result, it has less ability to support combustion in the refuse sitting on the grate. This proves particularly beneficial where the refuse contains substantial amounts of volatile hydrocarbons. The low oxygen content of the flue gas limits the burning of the volatilizing HC's. As a result, they may well not bloom into flame on the grate means which would cause extreme localized overheating, slagging, and possibly some damage to the grate itself. However, the use of flue gas for air-grate purposes has not proved generally feasible in the past.
In general, to use the flue gas, an improved incinerator system will have the oxygenating means for the grate means coupled to the outlet opening of the substantially enclosed combustion chamber. The oxygenating means then introduces at least a portion of the gaseous products of combustion that it had obtained from the outlet opening back into the chamber through the grate means as all or at least a part of the oxygen-containing gas.
The oxygenating means may go further to assist the combustion process occurring upon the grate means. To do so, the oxygenating means will also establish the temperature of the oxygen-containing flue gas to within a predetermined range prior to the oxygen-containing flue gas entering the grate means. When the refuse contains chlorine, often from the commonly used polyvinylchlorides (“PVC's”), the temperature typically will range about 350 to 800 degrees and more desirably 400 to 750 degrees F. Below this range, hydrochloric acid could damage parts of the blower used to move the flue gas. Using acid-resistant blower parts may permit the use of temperatures below this range. Above the upper end, chlorine gas, for example, can attack the blower.
One convenient way that the oxygenating means establishes the temperature of the oxygen-containing flue gas is to combine with the gaseous products of combustion a separate oxygen-containing gas having a temperature lower than the gaseous products of combustion taken from the chamber's outlet opening. Naturally, air represents a convenient low-temperature gas. Combining the appropriate amount of it with the flue gas will bring it into the desired temperature range where it sill support combustion without damaging the system.
On the other hand, if the refuse has no chlorine, the temperature limits due to the chlorine and acid gas corrosion discussed above lack relevance especially on high-temperature blowers used to convey the flue gasses. The flue-gas temperature then need only remain below the temperature design limit of the blower, typically 2000 degrees F. for high-temperature parts.
However, if the refuse, and thus the gaseous products of combustion, contain chlorine, the flue gas could well attack the components of the blower used to move the flue gas into the grate system. Typically the conduits may have protective coatings of refractory, and the grate means will benefit from protective temperature control. To avoid damaging or even destroying the unprotected blower components, one of two solutions present themselves. Either keep these components out of contact with the chlorine-containing flue gas or only allow such contact after the gas has fallen into the harmless temperature range.
To achieve the former, the oxygenating means includes a conduit in fluid communication with the outlet opening and the grate means. A blower means, coupled to this conduit, introduces air from outside the chamber under pressure into the conduit to make a mixture of the products of combustion and the air. The blower accomplishes this task while remaining entirely out of contact with the gaseous products of combustion and the resulting mixture of flue gases and air. The oxygenating means then introduces at least a portion of this mixture of the products of combustion and air into the chamber through the grate means as at least a part of the oxygen-containing gas.
Alternately, to reduce the gas' temperature to the desired range before it contacts the components, the oxygenating means includes a conduit in fluid communication with the outlet opening and the grate means. An inlet means couples to this conduit between the outlet opening and the grate means and provides a pathway for the introduction of air into the gaseous products of combustion. A blower means couples to the conduit between the inlet means and the grate means. The blower means draws air under a partial negative pressure from the inlet means and places it into the gaseous products of combustion to form a mixture of the air and the gaseous products of combustion prior to the products of combustion reaching the blower means. Since the mixture is created before the gasses reach the blower means, the blower means only sees gasses within the desired temperature range. The blower means then introduces the mixture of air and the gaseous products of combustion under pressure through the conduit and into the combustion chamber through the grate means as at least a part of the oxygen-containing gas.
The system described in Mr. Basic's patents has significantly altered the manner of incinerating bulk refuse. The improvements have advanced the manner and apparatus for accomplishing this task. Refuse for incineration need no longer undergo prior treatment such as shredding or comminutization before it meets the fire. However, the question arises as to the effect that prior shredding or just small-sized particles may have on the system described in the patents. Not surprisingly, small particles may readily fall through the grate and not remain upon it for a sufficiently long period of time to accomplish the dual objectives stated above. For such material, the dryer grate serves very little purpose since the particulate or shredded material does not dwell upon it long enough to dry and force the vaporization of the volatile hydrocarbons. However, adding a second grate below the first may retard the passage of the particulate matter long enough to accomplish the two objectives of drying and driving off volatile HC's.
In general terms, an improved incinerator system especially useful for particulate or shredded material has a is a first grate means and generally defines a first upper geometric surface. This is typically the only grate means in the incinerator chambers discussed above. For the present development of two grate means, a second grate means, with openings therethrough, is located within the combustion chamber and generally defines a second geometric upper surface, with the second upper surface generally lying below the first upper surface and below the first grate means. To improve the versatility of the system the second grate means may be removable from the combustion chamber.
Naturally, the improvements discussed above where the oxygenating means passes an oxygen-containing gas through the first grate means will also be realized where the oxygenating means also passes the oxygen-containing gas through the second grate means. Of course, all of the temperature-controlling features can apply to the second grate means as well as the first. Thus, the temperature-controlling means of the prior discussion can couple to both the first and second grate means and pass a first and second fluid, respectively, other than the oxygen-containing gas and of a temperature within a predetermined range, through the first and second grate means and separate from the oxygen-containing gas. Usually, the temperature-controlling fluids for the two grate means will be the same, typically two-phase water-steam under pressure.
In particular, the first and second grate means may each have openings through it and comprises, respectively, a first and second plurality of elongated arms attached to the chamber with the first grate means near and extending away from the inlet opening. The first and second plurality of elongated arms lie generally parallel to each other. The tops of the first and second plurality of arms generally define, respectively, a first and a second upper surface with the second upper surface generally lying below the first upper surface. To keep shredded and particulate matter on the two grate means for a longer period of time, the arms of the first plurality lie generally parallel to but staggered from the horizontal location of the arms of the second plurality. Accordingly, the small pieces of material may rapidly pass through the first grate means. But, they fall onto the second grate means and undergo further reaction there.
Not unexpectedly, the oxygenating means may pass an oxygen-containing gas through the second grate means as well as the first and for the same reasons. Similarly, a temperature-controlling means may couple to both the first and second grate means. As expected, it passes a first and second fluid, respectively, (usually the same) other than the oxygen-containing gas and of a temperature within a predetermined range, through the first and second grate means and separate from the oxygen-containing gas. This serves to control the temperatures of both grate means and prevent damage to either.
To permit the incinerator to handle the normal, bulk material, the second plurality of arms may permit its removal from the chamber. Closing off any openings that passed oxygen-containing gas or temperature-controlling fluid to this second grate means changes the incinerator to the usual structure described above.
As a further structural feature, one end of each of the arms of the first and second plurality of arms attaches to and cantilevers from the chamber. This allows for the expansion of the grate means under the influence of the heat in the incinerator. Connecting the ends of the arms to the sidewalls could result in damaging either or both since they heat, expand, cool and shrink at different rates. Further, cantilevered arms allow metal objects, such as tire wires or even bicycles to slide off the end without holding up the remainder of the burning refuse.
As discussed above, the refuse, upon its entry into the incinerator chamber, enters the inlet opening and sits upon the grate means for a period of time. During this time, its water content should fall below 50 percent, and its volatile HC's should enter the gas phase. Placing an excessively large pile of refuse, specifically an excessively tall stack of material, may well limit if not defeat many of the beneficial purposes of the grate means discussed above and in Mr. Basic's patents. Avoiding the height of the pile of refuse above the grate means will lead to a more efficient treatment of the material. Accordingly, an improved Incinerator system results with the use of a loader means coupled to the chamber in proximity to the inlet opening. Naturally, the loader means first must move refuse into the chamber through the inlet opening and onto the grate means. As its secondary objective and to help the grate means and its air to perform their functions, the loader means might also limit the height of the refuse above the top of the grate means. The loader means thus can aid in preventing an excessively thick layer of refuse upon the grate means.
The various developments discussed above can find use in systems other than refuse incinerators. In particular, each feature will benefit a system that can burn any type of material. Such a system comprises a chamber with a fire-resistant floor means within the chamber, for holding burning material on it. A grate means having openings through it is located within the chamber. It holds the material above the floor means for a limited period of time and then allows it to drop through to the floor means. As for a refuse incinerator system, an oxygenating means couples to the grate means and introduces an oxygen-containing gas into the chamber through the grate means. Each of the improvements enumerated above for a refuse incinerator system also finds use for this type of system that more generally burns other materials.
As indicated in Mr. Basic's patents above, controlling the temperature of the incinerating process constitutes an important objective in burning refuse and hydrocarbon-containing liquids. One incinerator system for carrying such burning includes a substantially enclosed chamber. This enclosure then has a fire-resistant floor means within the chamber for holding and burning material on it, an inlet opening for the introduction of solid bulk refuse, and an outlet opening for the egress of the gaseous products of combustion from the chamber. A grate means having openings through it sits within the chamber and adjacent to the inlet opening and above the floor means. The grate means holds refuse newly introduced through the inlet opening above the floor means for a limited period of time and then allows the refuse to drop through to the floor means while burning. A significant step forward in regulating the temperature of the system involves controlling the temperature of the grate means, but doing so independently of the temperatures of both the oxygen-containing gas introduced through the grate means and, if present, the gaseous products of combustion. This method of independently controlling the temperature of the grate means permits the separate optimization of the temperatures of the grate means, the oxygen-containing gas introduced through the grate means, and, where appropriate, the gaseous products of combustion.
One convenient method of separately controlling the temperature of the oxygen-containing gas through the grate means involves passing a fluid other than the oxygen-containing gas and of a temperature within a predetermined range, through the grate means. Keeping this fluid separate from the oxygen-containing gas allows the former to control the temperature of the latter without mixing with it. This, in turn, permits the use of two entirely separate fluids for the different purposes.
A very useful material for passing through the grate means for controlling its temperature takes the form of a two-phase fluid of a temperature within a predetermined range. The water-steam combination readily accomplishers this task, especially since its temperature under various pressure has long been established. Regardless of the fluid employed, the fact that it is passed separately through the grate means permits its facile handling in another manner. Specifically, the fluid may be retained in a closed system and treated elsewhere. Accordingly, after the fluid has passed through the grate means, it then passes along a closed system and back through the grate means. Two particular advantages of the water-steam system results from the fact that it needs no outside source of power to assure its circulation. Thus, even with an electrical failure, the water-steam mixture will continue to circulate to provide its temperature protecting function. Further, the continued circulation of this two-phase system avoids localized hot spots that could otherwise develop and effect harm in various locations of the system.
The gaseous products of combustion contain heat that can find economic use elsewhere. To obtain this heat in a useful form, the combustion gasses typically pass through a heat exchanger, usually a boiler. The method of recovery involves transferring the heat in the gaseous products of combustion to a two-phase fluid such as water-steam. The fluid, after receiving the heat from the combustion gasses, may then find use in controlling the temperature in the grate means. To accomplish this objective, the two-phase fluid is then passed through the grate means separate from the oxygen-containing gas.
Passing the fluid through the grate means and separate from the oxygen-containing means has the purpose, of course, of allowing heat transfer between the two fluids without intermixing their contents. To accomplish this, the oxygen-containing gas may be introduced into the combustion chamber through a conduit formed in a membrane tube wall from sections of relatively thin, substantially heat conducting material. The membrane tube wall should constitute at least part of the grate means and have at least two spaced-apart, substantially fluid-tight tubules formed from substantially heat-conducting material and in thermal contact with the sections through which the oxygen-containing gas passes. The fluid other than the oxygen-containing gas passes through the substantially fluid-tight tubules to control the temperature of the grate means.
Controlling the temperature of the grate means also results in guarding it from heat destruction. This provides considerable leeway in the selection of the materials for the grate means and in the maimer of protecting them or even dispensing with the need to protect such materials. In particular, the grate means may comprise at least one passageway having a composition of steel through which the oxygen-containing gas passes prior to being introduced into the combustion chamber. The steel has the benefits of strength (below specific temperatures) and economy. As a result of controlling the temperature, refuse may undergo combustion in the chamber. At least a portion of the steel passageway may be directly exposed to this combustion occurring within the chamber without any harmful effect of the heat upon the steel.
The methods given above have the primary purposes of incinerating bulk refuse. They may also properly incinerate particulate and shredded matter without alteration or addition. However, this may not always prove to be the case. In some instances, the particulate matter may fall through the grate means too fast to adequately remove its contained water or volatile hydrocarbons. When this occurs, the process may be able to properly handle the matter by passing it through first one grate means and then a second. Thus, the process will make use of first and second grate means each having openings through them. The first grate means has a general location within the chamber adjacent to the inlet opening and above the floor means. The first and second grate means generally define, respectively, first and second geometric upper surfaces. The second upper surface of the second grate means generally lies below the first upper surface and thus below the first grate means. The process for assisting combustion within an incinerator system of this sort generally involves passing an oxygenating-containing gas through the first grate means and into the chamber. Refuse is introduced through the inlet opening and placed upon the first upper surface from where it is allowed to drop through the first grate means. The refuse is then placed upon the second upper surface and then allowed to drop through the second grate means as well. Lastly, the refuse is then placed upon the floor means while burning. The time involved in the refuse sitting on and passing through the two grate means may accomplish its incineration in the controlled manner discussed above.
In particular, the first and second grate means may generally comprise, respectively, first and second pluralities of elongated arms attached to the chamber with the first plurality extending away from the inlet opening. The second plurality of elongated arms lies generally parallel to the first plurality. The tops of the first and second pluralities of arms generally define, respectively, first and second upper surfaces. The second upper surface generally lies below the first upper surface with the arms of the first plurality lying generally parallel to but staggered from the horizontal location of the arms of the second plurality. In this type of incinerator, the process will include passing an oxygen-containing gas through the first grate means and into the chamber accompanied by placing refuse newly introduced through the inlet opening and upon the first upper surface. The refuse is then allowed to drop through the first plurality of arms and is then placed upon the second upper surface. From there, it is allowed to drop through the second plurality of arms and is then placed upon the floor means while still burning.
Since the oxygen-containing gas does not bear the burden of controlling the temperature of the grate, gasses other than air may more readily find use in this process. In particular, for the reasons alluded to above, the flue gasses hold significant potential for advancing the incinerating methods. To take advantage of the flue gas' characteristics, at least a portion of the gaseous products of combustion from the chamber's outlet opening may be introducing into the chamber through the grate means as at least a part of the oxygen-containing gas. Although resulting from the burning process, the flue gas still contains an amount, albeit lower than air, of oxygen.
However, having a separate fluid used for temperature-controlling purposes does not necessarily mean that no reason exists for also controlling the temperature of the flue gasses when they find use as the oxygen-containing gas. Further, properly controlling the temperature of the flue gasses prior to introducing them into the grate means may, in appropriate circumstances, obviate the necessity of using a separate, temperature-controlling fluid altogether. In any event, the use of temperature-controlled gasses involves first introducing at least a portion of the gaseous products of combustion into the chamber through the grate means as at least a part of the oxygen-containing gas. The temperature of the oxygen-containing gas may be established to within a predetermined range prior to the oxygen-containing gas entering the grate means.
Using the flue gasses as part of the oxygen-containing gas introduced through the grate means suggests taking care to protect components that may prove susceptible to attack by the gasses themselves. Particularly is this the case where the refuse undergoing combustion, and thus the flue gasses as well, contain chlorine. In this case, any component with steel, especially a blower, exposed to the gasses may suffer unacceptable harm if exposed to the flue gasses outside the temperature range of 350 to 800 degrees F., or more particularly and safely, 400 to 750 degrees F. One method of preventing such harm is to keep the blower and other steel components out of contact with the flue gasses. To do this, for example, the blower may sit outside of the gas stream and introduce air under sufficient pressure to create a Venturi, or vectored, effect and force the air and the flue gasses into the grate means. Stated more generally, this process involves first introducing air from outside the chamber under pressure into the gaseous products of combustion through the use of blower means to form a mixture of air and such products. At least a portion of the mixture of air and the gaseous products of combustion is introduced into the chamber through the grate means as at least a part of the oxygen-containing gas. The blower means is, of course, kept out of contact with the gaseous products of combustion and the mixture.
Alternately, the blower may suck air into the flue gasses and reduce their temperature to an acceptable level before the latter can reach the blower itself. Taking advantage of this concept involves introducing under a partial negative pressure, provided by a blower means, air from outside of the chamber into the gaseous products of combustion. A mixture of the air and the gaseous products of combustion is formed prior to the products of combustion reaching the blower means. Finally, the mixture of air and the gaseous products of combustion is introduced under positive pressure into the grate means and into the chamber through the grate means as at least a part of the oxygen-containing gas.
Naturally, even with using the flue gasses as part of the oxygen-containing gas and even controlling the temperature of the latter as indicated above, the temperature of the grate means may still need or desire additional temperature control. This process involves introducing the gaseous products of combustion from the outlet opening of the chamber into the chamber through the grate means as at least part of the oxygen-containing gas. As with the temperature control set forth previously, a fluid, other than the oxygen-containing gas and of a temperature within a predetermined range, is passed through the grate means and separate from the oxygen-containing (flue) gas.
The oxygen-containing gas from the grate means has the functions described with regards to the refuse sitting there. Allowing the oxygen-containing gas to pass through the mass of refuse will allow it to accomplish its objective. An excessively large and tall mass may prevent the gas from penetrating it and prevent or minimize the desirable functions of the gas. A method to avoid this first involves moving refuse into the chamber through the inlet opening onto the grate means. The height of the refuse above the top of the grate means may then be limited to permit the gas to penetrate the mass of material.
The foregoing description of the various methods has centered upon an incinerator burning refuse. Clearly, the methods will have equal applicability to any similar system burning nonrefuse material. Such a system will include a chamber, a fire-resistant floor means within the chamber for holding material on it. Again, a grate means having openings through it will have a location within the chamber and the material above the floor means for a limited period of time. The grate means will then allow the material to drop through to the floor means. This generalized system for burning or even drying material can take advantage of all the methods described above and below for refuse incinerators.
The structures and methods described above can also serve to merely dry refuse or other material for any purposes and not just in aid of incinerating the material. In this case, the gas introduced through the grate means need not contain oxygen since it may not even support combustion. Or, although combustion may take place in the dried material, the gas from the grate means may supply none of the requisite oxygen. Furthermore, the drying may also benefit from the use of the generally hot gaseous products of combustion even though no burning takes place in the drying chamber. In this case, the drying may utilize the gaseous products of combustion taking place elsewhere for other purposes, for example for power generation from fossil fuels. The exhaust gasses from such a generator could well find use for this drying purpose.
A drying chamber for this purpose will have a grate means. A gas then passes through the grate means and into the drying material. The material to be dried sits upon the grate means. Under these conditions, all of the structures and methods described above will find use, individually or in combination to benefit the drying equipment and methods. Alternatively or in addition, the same components and methods may serve, under the proper conditions, to force volatile hydrocarbons from the material.
While the refuse burns, it naturally releases heat energy. Part of this energy enters the water wall 78 to heat the fluid contained in it. The heated fluid from the membrane-tube water wall 78 may then travel along the conduit 88 to the boiler 79. Steam removed from the top of the boiler 79 may find constructive use elsewhere either in the incinerator 75 or elsewhere as in electrical generation or for heating.
The refuse, after completing its burning, falls from the second pulsed hearth 77 into the ash pit 89 which contains water. The scoop 90, pulled by the cable 91 attached to the motor 92, travels along the track 93. It then dumps the ashes into the hopper 94, and from there it falls into the bin 95.
The gaseous products of combustion pass from the main incinerator chamber 84 into the passageway 102. There, they join gasses from the raw refuse in the hopper 82, which under the action of the blower 103 travel along the conduit 104. This removes and will serve to destroy the foul aroma of the raw refuse.
The gasses from the passageway 102 then enter the first reburn stage 108. There, with the controlled assistance of the auxiliary fuel burner 109, if necessary, and the air fan 110, they continue to burn at an elevated temperature to destroy combustible moieties in the gas stream. As the incineration of the gaseous products of combustion proceeds, the gasses pass to the second reburn section 111 where they continue to burn. While doing so, they receive controlled amounts of additional air from the blower 112.
After the second reburn stage 111, the gasses could, if a problem existed in the system, escape through the safety relief stack 117. In normal operation, however, the damper 118 keeps the stack 117 closed, and the gasses travel to stage 4 of the system 121. There they receive the addition of cooled gasses from the conduit 122. The cooling of the combustion gas stream thus effected lowers its temperature below the point where various ingredients in the gasses, such as zinc oxide, can exist in the vapor state. These components thus precipitate out in the cooling process and, accordingly, do not condense on the tubes of the boiler convection 79 when the combustion stream enters it. As the somewhat cooled gasses travel through the boiler 79, the give up additional heat for further useful purposes. As discussed in the first Basic patent U.S. Pat. No. 4,438,705 listed above, the first and second reburn stages 108 and 111 intervene between the water wall 78 and the boiler 79. This permits sufficient heat to remain in the gasses in the two reburn stages 108 and 111 to achieve full burning of the combustible elements of the gas stream.
After exiting the boiler 79, the gas stream enters the economizer 123. There, it preheats feed water that will find use in the boiler system of the water wall 78 and the boiler 79. Accordingly, the economizer saves further heat energy from the combustion process and feeds it back into the water that will pass through the system. This saved heat adds to the steam and electrical generation of the incinerator system 75.
From the economizer 123, some of the gas travels along the conduit 124 under the action of the blower 125. This gas, of course has given up much of its heat content in the boiler 179 and the economizer 123 and thus has a lower temperature then when it entered these latter components. Thus, after traveling along the conduit 122, it enters the stage 4 area 121 and lowers the temperature of the gas stream passing from the second reburn tunnel 111 as discussed above.
The remainder of the gas stream from the economizer 123 passes along the conduit 132 to the heat exchanger 133. The blower 134 passes outside air through the exchanger 133 to further cool the gas stream. At this point, the gasses have given up a substantial portion of their heat in the boiler 79 and in the economizer 123. However, the temperature of the gas stream may still remain above the vaporization temperature, or the dew point, of acids contained in it. The heat exchanger 133 reduces the temperature to a point, generally below about 250° F. where the acids in the gas stream actually condense into the liquid state. This allows their neutralization by combining with a base and their removal in subsequent treatment, as discussed immediately below.
The exhaust gasses then receive dry lime and activated carbon along the conduit 135 to neutralize the condensed acids and remove pollutants, respectively. The gas stream with these added materials then enters the baghouse filter and dry acid gas scrubber 138 which separates the gas from the particulate matter. The solid matter falls into the bin 141 where it awaits removal.
The cleaned gas from the baghouse 138 travels along the conduit 142. At this point, with actual refuse in an operating incinerator, no gas enters the exit conduit 142 from the conduit 143 because the motor 144 has closed the damper 145 to direct the combustion gasses into the baghouse 138.
The gasses in the conduit 142 are pulled by the induced-draft fan 148, and they escape into the atmosphere through the main exhaust stack 149. The continuous emissions monitor system 150 permits the evaluation of the discharge gasses for various combustion products possibly contained in the gasses exiting the stack 149. These could include the particulates, the carbon compounds, the nitrous oxides, the sulfur emissions, as well as others. The exact task of the monitor system 150 depends upon the particular case involved including such factors as the refuse undergoing incineration, the siting of the incinerator, and others.
During the startup operations, the incinerator 75 uses a fuel such as natural gas, propane, butane, or oil in its burners 85 and 109 to heat it to its operating temperature where it can start receiving actual refuse. During this warming time, the exhaust gas stream contains virtually no components that the baghouse 138 need remove. Under these limited conditions, the damper 145 may fully open and allow exhaust gasses to bypass the baghouse 138 and pass through the conduit 143 directly to the conduit 142 and the exhaust stack 149. However, when the incinerator 75 has reached its operating temperature, the damper 145 closes, and the exhaust gas stream enters the baghouse 138 as described above.
The inlet opening 164 allows for the entry of the bulk refuse 168 into the interior 169 of the combustion chamber 155. The inlet door 170 sits in its upward, or open, configuration in the figures to permit the entry of the refuse 168. To close, the door 170 would rotate in a counterclockwise direction about the arc 171 shown in dashed lines to block the opening 164.
The refuse 168 starts its journey into the incinerator chamber 155 by being placed into the hopper 175. To permit this, the plug loader 176 would have to move to the left of the hopper 175 and provide a space within the hopper 175 for the material. With the refuse in the hopper 176, the plug loader would then move to the right under the force of a motor. Eventually, the loader 176 would reach the position shown in
With the refuse 168 in the towering pile shown in
In
The movement of the plug loader 176 into the chamber 155 has a beneficial effect in addition to spreading out the refuse 168 on the grate 181. Often bulk refuse contains various substantial pieces of metal or wire. This may include tire bindings, bicycles, and the like. These could simple sit on the grate and 181 and block passage of refuse on in into the chamber. As the loader 176 moves into the chamber, it pushes this noncombustible metal debris along the grate 181. Moving the loader sufficiently far into the chamber that its front end 179 reaches the end of the grate 181 will force these metal pieces to fall off the grate and onto the floor 156. Eventually, the floors 156 to 158 will move the metal refuse to the pit 163. As seen from this, though, moving the loader 176 into the chamber 155 serves the purpose of cleaning the grate 181 of accumulated, most likely noncombustible, debris. Clearly, it could do the same for very large hunks of combustible material such as logs and the like which will not likely fall through the openings in the grate itself.
As suggested by the above, the depth to which the loader 176 moves into the incinerator chamber 155 varies for different circumstances. To push material off of the grate 181, the loader may travel far enough for its front end 179 to reach or almost reach the end of the grate 181. For a large amount of material, the loader 176 may extend almost as far as seen in
Clearly, as the loader 176 enters the chamber 155, it experiences the heat generated by the combustion occurring there. Accordingly, it should typically have some protection from the high temperatures found there. This protection may take one or more forms. Thus, the loader may first have a refractory covering. Further, air may circulate within the loader itself to effectuate its cooling. Whatever cooling finds use, it should desirably have the ability to protect the loader if it should happen to become stuck inside of the chamber 155.
The three grate arms 193 to 195, described extensively below, extend through the plenum 186 and to the outside 201 of the incinerator chamber. The ends 203 of the grate arms that protrude from the chamber permit the passage of the oxygen-containing gas and the cooling fluid into the arms themselves.
FIGS. 6 to 8 give a more realistic view of an incinerator chamber in the general area 206 of its inlet opening or throat 207 but without the loader. Again refuse enters the opening 207 in the wall 208 and sits or, more accurately, moves along upon the shelf 209. It can then come to rest on the two identical grate arms 213 and 214. The shelf 209 forms the top of the plenum 215 whose side 216 permits the entry of cooling air.
The incinerator also includes the two side walls 217 and 218. Each includes the membrane-tube wall, 219 and 220, respectively, to permit heat recovery and removal from the incinerator chamber as seen in Mr. Basic's patents listed above. Additionally, the walls 219 and 218 include the sloping side shelves 223 and 224, respectively. The shelves cause the refuse to slide from the side walls 217 to 218 so that it will come to the grate arms 213 and 214.
The structure of the grate arm 214 appears in the cross-sectional view of
This important structure of the grate arm 214 (and the arm 213) achieves two purposes. First, the hollow interior 249 permits the passage of the oxygen-containing gas used in the processes occurring in the refuse on top of the arm 214. The oxygen-containing gas escapes the arm 214 through the openings, or nozzles or jets, 251 and 252 placed in the metal fins 241 and 244, respectively. The oxygen-containing gas can take various alternatives of which air represents the most common and expedient. Flue gas, as discussed both above and below, portends significant benefits as the oxygen-containing gas. First, it has a significant amount of heat that can find use in drying the refuse, if needed. Also, its heat can assist in driving off the volatile hydrocarbons. Its water content has a high specific heat which causes it to provide more heat to the refuse on the grate arms. Further, its relatively low oxygen content will allow the volatile HC's to leave the grate arm before blooming into fire. This helps prevent localized excessive hot spots on the grate arms and the resultant slagging.
Using air as the oxygen-containing gas brings a gas of very low temperature into the combustion chamber. It could well benefit from heating to help it achieve its purposes. On the other hand, using flue gasses for the same purposes introduces a potentially very hot gas into the air-grate arms 213 and 214. These excessively high temperatures can cause the steel in the grate arms to lose most of its strength. In fact, at temperatures around 800 to 950 degrees F., the different alloys of steel can lose 90 percent of their strength. Introducing flue gas at temperatures that can approach 2000 degrees F. clearly portend the air-grate arms losing structural integrity. Additionally, the arms 213 and 214, of course, sit in the combustion chamber where the temperature, due to the incineration occurring there, can well reach 1200 to 1400 degrees F. and can even go as high as 2000 to 2400 degrees F. Clearly, these, temperatures have the capability of robbing the arms of all of their strength. As a result, the gases entering the interior conduit 249 may well benefit from controlling their temperature. Even more importantly, the steel structure of the arms 213 and 214 can benefit from controlling their temperature.
To control the temperature of the arms 213 and 214 and possibly the gas traveling along their interiors, a fluid having a generally known temperature passes through the tubules 231 to 236. Clearly, since the tubules 231 to 236 have a composition of a heat conducting material such as steel, the fluid's temperature will pass to the tubules' metal.
However, the benefit of the temperature-controlling fluid passes further than the tubules 231 to 236 themselves. The tubules 231 to 236 have a heat-conducting connection to the metal fins 241 to 246. Welding or other integral connections will work well for this purpose. Accordingly, the temperature of the tubules 231 to 236 will pass from the tubules and onto the fins 241 to 246. In other words, excess heat from the fins 241 to 246 will pass to the tubules 231 to 236 from where the fluid inside will carry it off to another location. Naturally, the width of the fins 241 to 246 should not exceed that beyond which their heat can pass in a timely fashion to the tubules 231 to 236 with their fluid.
Two-phase steam represents a desirable fluid to pass through the tubules 231 to 236. At a known pressure, it will maintain a known temperature. Furthermore, heating it anywhere will induce circulation of the fluid, thus avoiding the build-up of temperature at a location that could cause a hot-spot with concomitant localized structural deterioration or destruction of the arm 213 or 214. Other potential fluids can include oil and water, either most likely under forced circulation. The two-phase steam may move through the tubules under its own impetus or under forced circulation. Furthermore, saturated steam at 40 bars of pressure, has a temperature of about 500 degrees F. Any steam system that will maintain the temperature of the grate arms below the temperature at which they will start to suffer damage will clearly suffice.
The oxygen-containing gas enters the arms' interiors 249 outside of the combustion chamber. It then travels inside the chamber and exits the arms 213 and 214 through the nozzles 251 and 252 to enter the combustion chamber. Naturally, it can then enter refuse sitting upon the grate arms to dry it and drive off its volatile HC's. (
FIGS. 6 to 8 show the steel components of the arms 213 and 214 completely unprotected from heat. The fluid in the tubules 231 to 236 (as well as the end connections 255 to 257) adequately cools the arms 213 and 214 so that the high temperatures generally encountered in the combustion chamber do not have a deleterious effect upon them. Stated otherwise, the steel components of the arms 213 and 214, because of the fluid in the tubule components 231 to 236 and 255 to 257, remain at a sufficiently low temperature that they require no heat protection such as that offered by a refractory coating.
The oxygen-containing gas, such as air, can fail to appear in the interiors 249 of the arms 213 and 214. This can result from such simple causes as the failure of electricity for the blower pushing the oxygen-containing gas. Or, the blower itself may fail. However, the loss of the oxygen-containing gas in the arm interiors 249 will not result in the loss of structural integrity in steel of the arms 213 and 214. The fluid in the tubules 231 to 236 and 255 to 257 will still protect the grate arms 213 and 214 from the high heat encountered in the combustion chamber. Further, the temperature-controlling fluid avoids the need for the air or other oxygen-containing gas to cool the grate arms 213 and 214. In fact, to support combustion, air introduced into the grate arm interiors 249 may undergo substantial heating to high temperatures prior to reaching the arms. The fluid in the tubules 231 to 236 and 255 to 257 will protect the grate from the hot air as well as from the heat in the combustion chamber itself.
Removing all or part of the refractory coating on the steel grate arms 213 and 214 thus becomes feasible due to the temperature-controlling effect of the fluid in the tubules 231 to 236 and 255 to 257. Dispensing of any amount of refractory has several potential benefits. This results from the necessity of supporting the weight of any refractory used or, alternately, the benefit of not having to carry the weight of refractory not used. Since the arms 213 and 214 use no refractory (and other structures described below have only partial refractory coverings) these structures may support other weight that can benefit the process. This allows grate arms of greater length with the same supporting structure. Or, the grate arms can receive and support greater loads of refuse. Or, without the necessity for the same amount of refractory, a lighter supporting structure may suffice where heavier supports were required in the past.
However, a refractory coating may serve to protect a dryer grate from other dangers. This could include abrasion damage from contact with the refuse, especially sharp, hard, or scraping matter contained in it. Accordingly, FIGS. 9 to 11 show a grate arm generally at 261 largely surrounded by a refractory coating. In particular, the grate arm 261 includes the six fluid tubules 265 to 270, with the tubules 265 and 266 interconnecting through the end connector 275, the tubules 267 and 270 connecting through the end tubule 276, and the tubules 268 and 268 similarly interconnected at their ends. The fins 279 weld to the tubules 265 to 270 to make a membrane tube wall conduit with the interior 280 as discussed previously. The interior 280 provides a channel for the passage of the oxygen-containing gas which enters the combustion chamber through the jets 283. The sections 286 of refractory or ceramic material or even metal adhere to the fins 279 to provide abrasion resistance. In the case of metal sections 286, the fluid in the tubules 265 to 270 also provide them protection against heat damage.
As seen in FIGS. 9 to 11, the arm 261 has the refractory sections 286 almost completely encircling it. Only the outside portions of the tubules 265 to 270 show through the refractory. In FIGS. 6 to 8, in comparison, the arms 213 and 214 carried no refractory over the metal of the tubules or the interconnecting fins. The figures that follow show other arrangements of refractory. In some cases, all of the metal of the arm has a refractory covering. In others, only the top portions of the arms have the covering which serves the purpose specifically of protecting them from abrasion damage as the refuse sits and moves upon them.
An alternative end connection between the two tubules 295 and 296 appears in
A complete, three-arm, air-grate system appears generally at 311 in FIGS. 14 to 18. The actual components for introducing the temperature-controlling fluid receive discussion below with regards to FIGS. 29 to 40. The dryer grate 311 includes the three cantilevered arms 313 to 315. These arms appear almost identical to the arms 213, 214, and 261 of the prior figures. However, the arms 313 to 315 have the refractory sections 318 which completely encase all of the steel of their tubules 319 and 320. Anchors, such as the bolts 323, keep the refractory sections 318 in place. The refractory end caps 324 protect the ends of the tubules 319 and 320.
The tubules 319 and 320, on their respective ways into and out of the incinerator chamber, pass through the plenum 331 seen in
As discussed below, oxygen-containing gas enters the interiors 345 of the membrane tube wall conduits of the arms 313 to 315, seen in
The air-grate system generally at 351 of FIGS. 19 to 21 appears very similar to that of the prior five figures. It has the three arms 353 to 355 with each including the inlet tubules 357 and the outlet tubules 358. Both sets of tubules 357 and 358 pass through the plenum 361 which has the refractory covering 362. The inlet tubules connect to the lower header 365 where the temperature-controlling fluid arrives through the coupling 366. Similarly, the outlet tubules 358 pass through the plenum 361 and connect to the outlet header 367 which attaches to its coupling 368.
The differences between the grate system 351 of these figures and the system 311 of FIGS. 14 to 18 appear most clearly in
The air-grate arm seen generally at 381 appears virtually identical to the arms 353 to 355 in
The grate arm generally at 389 in
However, the structure of the arm 389 displays substantial differences from those in the prior figures. As
Further, as seen in the figure, the Y-anchors 406 hold the refractory 401 in place on the top 402 of the arm 389. The use of the alloy Y-anchors 406 indicates that the refractory 401 was cast in place on the top 402 of the arm 389. Further, this occurred after the attachment of the anchors 406 to the fins 393. Typically, and as seen in the figure, the refractory 401, when cast, extends across the entire width of the arm 389. However, to simplify the process, the refractory 401 may be cast in sections along the length of the arm. This makes construction noticeably simpler and may allow for expansion and contraction of the components.
As clearly suggested by
Further, other coverings may serve the same abrasion protection as the refractory 402 in
The grate arm 413 in
FIGS. 25 to 28 show the use of a plenum to introduce the oxygen-containing gas into the membrane-tube-wall conduits for passage into the combustion chamber. The discussion below with regards to FIGS. 36 to 40 illustrates the direct entry of the gas into the interiors of the membrane tube wall conduits.
The air-grate system generally at 427 in
The dryer-grate system 427 has the oxygen plenum 444 to the left in
When the plenum 444 reaches the back plate 455 seen in
The conduit 475 takes gasses from the third stage 468 and provides it to the blower 476 where it can combine with air from the air conduit 477. Suitable controls allow proportioning the gasses used from all air, or all combustion gas, or any desired combination of the two. The blower 476 then impels the desired oxygen-containing gas along the conduit 478 into the grate 461 for use in the drying, volatilizing, and combustion processes as discussed above.
Returning briefly to
FIGS. 31 to 33 show the incinerator generally at 487 which takes flue gas from the end 488 of the reburn tunnels 489. (This corresponds to the first location 481 at the end of the reburn tunnel 111 in
After the damper 493, the flue gas enters the conduit 494. There, it meets and mixes with air sucked in through the inlet 497. However, after entering the inlet, the air must pass its own damper 498. The air damper 498, like the flue-gas damper 493, may be controlled from the fully open to the fully closed position as well as intermediate configurations. The air and flue gas, to the extent that their respective dampers 498 and 493 admit them, then pass through the remainder of the conduit 494 to the blower 501 operated by the motor 502. The blower 501 then puts the gas passing through it into the conduit 505 for introduction into the incineration chamber 506 by way of the dryer grate 507, as discussed below.
The two dampers 493 and 498 serve several purposes. First, their relative settings, or openings, determine the relative amounts of air and flue gas passing through the blower 501 and then fed into the grate 507. For example, opening the air damper 498 further relative to the flue-gas damper 493 will increase the proportion of air relative to the flue gas in the gas stream passing to the blower 501 and then to the dryer grate 507. Equivalently, closing the flue-gas damper 493 relative to the air damper 498 will achieve the same result of increasing the proportion of air in the subsequent gas stream.
Altering the relative proportions of air to flue gas in the gas stream has several effects. First, it will determine the temperature of the gas stream in the conduit 494, the blower 501, the conduit 505 and the dryer grate 507. Increasing the fraction of the low-temperature air decreases the temperature of the gas stream passing through these components. Clearly, the converse holds true as well; increasing the fraction of flue gas increases the temperature.
The control of temperature has particular importance for the blower 501 if the refuse burning in the in the chamber 506 has chlorine. In this instance, the flue gases will have corrosive chlorine gas at temperatures above about 800 to 850 degrees F. and can damage the blower 501. Below about 350 degrees F., the flue gas will have hydrochloric acid that can also attack the blower 501. To provide some safety margin, the gas entering the blower 501 should typically have its temperature in the range of 400 to 700 or 750 degrees F. As can be seen from the figures, the blower 501 provides the important function of creating an induced draft that pulls in the flue gas and the air through their respective inlets 492 and 497 and feeds the resulting gas mixture into the conduit 505 and then the dryer grate 507. Its destruction would have a deleterious effect upon the operation of the dryer grate and perhaps the entire incinerator. Combining the cold air with the hot flue gas prior to either reaching the blower 501 permits the control of the temperature so that it falls in the range given above where the gas should not damage it.
Unlike the other components that the gas stream contacts, the blower 501 does not carry a refractory covering. Accordingly, protecting it from chlorine attack involves controlling the temperature of the gas stream passing through it. As clearly seen from
The gas stream, as discussed above, passes through the center of the membrane tube wall forming the conduits passing through the grate arms as discussed with reference to the prior drawings. While there, it clearly contacts the steel that composes the membrane tube wall itself. However, the fluid passing through the tubules in the membrane tube wall controls the temperature of the gas stream and keeps it out of the realm where the gas could damage the membrane tube wall itself.
The two dampers 493 and 498 also permit the control of the total amount of air-flue gas mixture fed into the grate 507 without changing the relative proportions of the two gasses constituting the mixture. Accordingly, opening both dampers 493 and 498 (by the appropriate amounts) will increase the total amount of gas introduced into the incinerator chamber through the direr grate without changing the relative proportions of the two components in the mixture. Thus, the final mixture will remain at the desired temperature where it avoids damaging the blower 501. Yet, its total volume entering the chamber 506 can increase when necessary for greater amounts of refuse on the grate or where that refuse has excessive amount of moisture that must dry before it will support incineration.
In any event, gas from the conduit 505 passes through the right-angle conduit 509 and into the coupling 510. The coupling 510 takes the gas stream from the conduit 509 with a circular cross section and passes it horizontally to the conduit 511 with a rectangular cross section, as seen in
FIGS. 34 to 41 show an incinerator system that also accomplishes the same objectives of taking flue gas, combining it with air, and introducing it through the dryer grate into the incinerator chamber while keeping it separate from the temperature-controlling fluid. However, it uses several different components to accomplish the same results.
In the incinerator system shown generally at 541 in the figures, refuse enters the main incinerator chamber 542 through the opening 543. As before, the loader 546 (in
As seen in
In any event, any gas that enters the housing 559 may depart through the exit opening 570. As discussed below, the gas departing the damper housing 559 will reenter the combustion chamber through the dryer grate.
The damper housing has the main portion 571 and the upper portion 572. The flanges 573 hold the two portions 571 and 572 together. Removal of the upper housing portion 572 allows access to the interior of the damper housing 559. It also permits placement of the damper 560 within the housing 559. The upper and lower housing portions 571 and 572 both have the steel housing 579 and the refractory covering 580. The refractory 580 protects the steel 579 from corrosion and heat damage because of the flue gasses passing through the housing 559. Similarly, the conduits 554 and 556 have the refractory covering 581 for the same reason. Further, the damper conduit 556 has the refractory seat 584 against which the damper 565 seats when closed as seen in
The structure of the damper 565 itself appears in
The ends 595 and 596 extend beyond their respective sides of the damper housing 559. This serves two purposes. First, the ends 595 and 596 sit in cut out portions of the housing wall and support the damper 565 in the housing 559. The support form the tube ends 595 and 596, as implied above, allows the rotation of the damper 565 between its closed and various open configurations.
Further, the hollow tube 589 permits the flow of air through the interior of the damper 565 to help protect it from the heat it sees in the flue gasses. Specifically, air under pressure may enter the opening 601 in the end 595 of the hollow tube 589. There, it travels along until it meets the cutout 602 in the tube 589. This allows air from the tube 589 to enter the hollow interior of the damper 565. The air then travels along its circuitous route in the damper 565 as directed by the baffles 603. The air may then depart the damper through the cutout 606 and travel through the hollow tube 589 and exit through the end 596. In other words, the baffles 603 prevent the passage of the air from the inlet cutout 602 directly to the outlet cutout 606.
Additionally, the tube 589 has the disc 607 blocking the direct passage air from the inlet end 595 to the outlet end 596. Rather, it forces the air to pass through the inlet opening 602 and then through the interior of the damper 565 as described above. Placing the disc 607 in the interior of the tube 589 typically involves cutting the tube into two pieces. The disc 607 is then welded in place followed by welding the two tube sections back together to form the tube 589.
To aid in its positioning, the damper 565 includes the counterweight 611 welded to the arm 612 which is affixed to the sleeve 613. In turn, the bolts 618 keep the sleeve 613 and thus the counterweight 611 in place on the tube 589.
The damper 565, because of the refractory 588 in addition to its steel structure 587, has a very substantial weight. When the damper 565 occupies any position other than closed in
As the flue gas leaves the damper housing 559 through the exit 570, it enters the air mixing section 617. The mixing section 617 receives air under pressure from the blower 618 powered by the motor 619. Specifically, the blower places air under pressure into the plenum 620 that lies on the inside surface of the mixer 617. The air in the plenum 620 then passes through the jets 621 in the interior wall 622. The air from the jets 622 then combines with the flue gas in the interior 623 of the mixer 617.
The blower 618 provides a substantial force to the air streaming through the jets 621 into the flue gas in the interior 623 of the mixer 617. This accomplishes two tasks. First, it assures proper mixing of the air with the flue gas. Second, the jets 621, as seen in the figure, point in the direction that the gasses should flow, or toward the mixer outlet 626. As a result, the air moving forcefully through the jets 621 creates a Venturi-like vectored effect to pull the gasses from the damper into the mixer 617 and push them out of the mixer 617 through its outlet 623. Stated in other words, the mixer section 617, with the aid of the blower 618, creates an induced draft for the flue gas from the reburn section 551. It also impels the gas out of its exit 626 and into the connecting conduit 630.
Significantly, however, the blower 618 never makes contact with the flue gasses passing through the mixer section 617. As seen in
As discussed with reference to the structure of
Second, the total amount of the gas mixture admitted to the dryer grate must also submit to control. This permits the system to adjust the amount of gas dependent upon the amount of refuse introduced into the incinerator as well as the nature of that refuse.
The present structure of FIGS. 34 to 41 permits control over the same two variables. Opening and closing the damper 565 provides the first control of the amount of flue gas permitted to pass to the dryer grate. The force of the blower 618 controls the amount of air introduced into the mixture and the amount of mixture introduced into the channel 630 that will pass to the dryer grate as discussed below. Balancing the two variables of the opening of the damper 565 and the speed and thus force the blower 618 of will permit the selection of the amount and nature of the gas introduced into and through the dryer grate.
As seen in
The modified structure seen in
Returning to
Another source of gas for the bypass conduit 635 appears at the opening 641 to the conduit section 642 which feeds directly into the bypass conduit 635. The opening 641, however, supplies only air to the conduit 635. The amount of air reaching the bypass conduit from the opening 641 falls under the control of the air damper 643. The air damper 643 thus determines the relative amounts of flue gas and air in the bypass conduit 635 reaching the blower 618. The blower 618, in turn, forces this mixture into the plenum 622 and through the jets 621 into the interior 623 of the mixer 617. There, it combines with flue gas drawn directly from the outlet 570 of the damper housing 559. Thus the mixer interior 623 combines flue gas from the damper outlet 570 with the air-flue gas mixture (as determined by the air damper 643) from the bypass conduit 635. This again compares with the mixer 617 of
The structure of
However, two limitations apply to passing flue gas through the blower 618. First, if the flue gas (and thus the burning refuse) has no chlorine, the gas' temperature must remain below about 2000 degrees F. Temperatures above this will cause destruction of most every metal that can find use in the blower. Second, in the presence of chlorine, the temperature in the blower should generally not exceed about 750 degrees F. to avoid corrosive damage to the blower's components. Clearly, having the control damper 643 admit air into the bypass conduit 635 will reduce the temperature of the gas there to a point where it will not adversely affect the blower 618. The refractory linings 636 and 649 protect the conduit 635 and the mixer 617, respectively.
On the other hand, closing the damper 565 from the reburn tunnel 551 and opening the air damper 643 results in the blower 618 supplying pure air to the dryer grate. This situation may prove beneficial where the refuse has very little moisture. In conclusion, the adjustment of the two dampers 595 and 643 and the blower 618 permit the delivery to the dryer grate of the desired amounts of oxygen-containing gas where that gas has the desired ratio of flue gas to air.
In
The refuse on the grate arms 654 dries and loses its volatile HC's. Eventually, it drops through the grate arms 654 and falls onto the first hearth 657, the second hearth 658, and the succeeding hearths.
The air-grate system 661 includes the upper layer 662 of the grate arms 663 to 665 and the lower layer 668 of the grate arms 669 and 670. Each of the grate arms 663 to 665, 669, and 670 sit in and attach to an incinerator chamber and may have the structure of any of the grates previously shown and described. Thus, they may pass an oxygen-containing gas down their interiors and out into the combustion chamber through jets. Further, a temperature-controlling fluid may generally keep the grate arms at a desired temperature. The use of the previously elucidated structure of a membrane-tube wall for the grate arms in both layers 662 and 668 will again serve well in this role. The arms may have a refractory covering that is complete or partial. Or, they may have none. They may also cantilever from the chamber wall.
Moreover, grate structures different from those shown above may well suffice for this multi-layered purpose, especially those shown in Mr. Basic's prior patents previously listed. Thus the grate structure may not take the form of arms, have an oxygen-containing gas passing through, or have a cooling fluid inside. However, the grate arms described here would appear to have especial benefit for this application as for the others related previously.
In
The choice of specific structural parameters may help insure a sufficient residence time for the particulate matter 675 to permit the desired drying and volatilization. Initially, the lower layer 668 of grate arms 669 and 670 should typically have a staggered configuration relative to the grate arms 663 to 665 of the first layer 662. In other words, the lower grate arm 669 should lie under the space 676 between the upper arms 663 and 664. This will cause material falling through the space 676 to rest upon the lower arm 669. Similarly, the lower arm 670 underlies the space 677 between the upper arms 664 and 665.
Adjusting the widths of the arms 663 to 665, 669, and 667 relative to the size of the small pieces of matter 675 and relative to the spaces 676 and 677 may also permit control of the amount of time until matter falls through the two layers. A good starting point will have the width of the arms 669 and 670 in the lower layer 668 about equaling the spaces 676 and 677 between the arms 663 to 665 of the upper layer 662. Further, using flat top surfaces on the grate arms 663 to 665, 669 and 670 may also retard the progress of the particles of matter 675 through the grate structure and allow drying and volatilization of HC's.
The plural layers 662 and 668 of grate arms may prove undesirable for normal, bulk refuse. To permit an incinerator outfitted with the grate-arm structure 661 of
Removing the grate arms 669 and 670, for example, will allow the use of the combustion chamber with the remaining three arms 663 to 665 of the upper layer to operate in the normal fashion for bulk refuse or large-particle material. In this configuration, the connections for the oxygen-containing gas and the temperature-controlling fluid in the lower arms 669 and 670 should be covered to prevent their escape into the combustion chamber.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/US03/18701 | Jun 2003 | WO | international |
The present application claims the priority of the PCT application PCT/03/18701 filed on Jun. 12, 2003, which, in turn, claimed the priority of the filing of the U.S. provisional patent application 60/391,052 filed on Jun. 24, 2002, of which the present application also claims the priority.
