Patent Application
20110290632
Not Applicable
Not Applicable
Not Applicable
The present invention relates to methods and apparati such as a pyrolytic kiln for treating coal and biomass by pyrolysis or similar thermal methods that remove much of the water content at the front end of the kiln where the coal and/or biomass is loaded into the kiln while reclaiming useful hydrocarbons and char at the far end of the kiln. The system described increases the capture of the useful caloric components of the coal and biomass that result from the pyrolysis process.
As fossil fuels become increasingly depleted and there is an ever increasing worldwide concern to minimize air pollution, methods to provide clean coal and biomas are receiving rising emphasis. Global warming has become a major issue which relates to find ways to decrease gases that absorb reradiated energy (infrared) from the earth's surface. These gases are principally carbon dioxide, methane and water vapor. More importantly there is a continuing drive to improve the air quality of the earth's atmosphere. To achieve this from the burning of fossil fuels such as coal, biomas, fuel oil and natural gas requires means for removing pollutants such as mercury, selenium, sulfur and sulfur dioxide. One of the chief ways of achieving these goals is to use pyrolytic methods to remove these pollutants while attempting to recapture them and bring them to a stage where they can be utilized in a variety of useful applications. The re-capturing of potential pollutants and reprocessing them makes it possible to use what is initially a pollutant into a saleable item that, in many cases can be utilized in a non-polluting or less polluting manner. This form of waste management is becoming recognized world wide as a necessary and achievable goal. Waste management, as opposed to mere recycling, has become increasingly important since standard recycling methods for the waste products found in coal and biomass are no longer adequate to contain the massive volume produced nor economically prudent.
While some of the waste products from the burning of fossil fuels and biomass can be recovered or recycled, most are disposed of in landfill. This type of disposal is wasteful and in itself potentially polluting, clearly not an environmentally friendly or economical way to proceed. Various government agencies have now put laws into effect that make certain forms of this type of disposal illegal which can result in substantial fines.
There are a large number of patents that that make use of pyrolysis and depolymerization techniques to utilize waste products that are emitted from the treatment of coal and biomasses. As an example, U.S. Pat. No. 5,269,947 describes depolymerization means for converting organic materials such as coal, biomass and inorganic materials into reusable combustible oils and gases. U.S. Pat. No. 5,711,769 consists of a continuous pyrolyzing process for treating coal to form stable coal char by passivating the coal, rehydrating and cooling the product thereby preventing spontaneous ignition. The process pyrolyzes the coal which vaporizes and has means to remove low temperature volatiles. The process also includes capturing the high temperature volatiles and the resulting coal char for useful purposes.
The invention is one relating to pyrolysis of carbonaceous matter such as coal and biomass. The unique feature of this invention is that it incorporates two airlocks, one at each end of the pyrolytic kiln. In addition there are two fans to draw off volatiles. The low temperature volatiles are drawn off by the first fan located at or near the proximal end of the kiln where the temperature is on the order of 100 C. These gases contain mostly water vapor and other low temperature volatiles. The importance of this fan, and a major novel feature of the present invention, is to withdraw from the pyrolysis kiln the water vapor at an early stage of the pyrolysis process. A second fan, located at or near the proximal end of the kiln, draws off the useful hydrocarbons together with additional contaminant gases to be processed. The remaining solid char is removed from the kiln at the proximal end of the kiln and serves as useful combustible material together with the hydrocarbon volatiles that are separated from the high temperature contaminant volatiles. In some greater detail, we describe a system for pyrolyzing carbonaceuous material to capture and isolate selected gases upon the pyrolyzing the material in a kiln consisting of an inner core and an outer shell each with an inner and outer surface. Both kiln and core have a proximal and distal end. Also, there is a first airlock affixed to the proximal end of the inner core by a first rotating seal and a second airlock attached to the distal end of the inner core with this airlock also attached to the inner core and a second rotating seal. Each end of the core has respectively a first fan connected to tubulation emanating from the proximal end of the inner core and a second fan connected to tubulation emanating from the distal end of the inner core. A helical steel rail is rigidly affixed along the inner surface the inner core while, heating coils fixedly attached to the inner surface of the kiln shell. There is also a first condenser/separator connected to a water cleanup station positioned near the proximal end of said inner core and a second condenser/separator station, positioned near the distal end of said inner core. A gear wheel surrounds the proximal circumferential end of the inner core. There also exists a means for rotation of the core along with a first tabulation connected between said first fan and first condense/separator unit; as well as a second tubulation connected between said the second fan and second condenser separator unit. The entire kiln is supported on mounts to elevate the system above ground level.
The inner core is mounted concentrically on slip rings within said outer shell, while the annular space between the shell and core contains one or more thermal sensors. Rotations of the two aforementioned fans rotate in a manner that provides airflow in opposite directions. The core, prior to loading with coal and or biomass (carbonaceous material) has an internal volume that is open, that is, similar to a hollow tube or duct except for the presence of the aforementioned helical rail. However, it is also possible to run the pyrolyzation with the installation of one or more circular baffles internally mounted within the core volume which enhances the efficiency of the oppositely directed airflows, however such baffles are optional. With the use of a baffle, at least one steel baffle stem, minimum length of 4 inches and a diameter 2-4 inches, has one end of the stem affixed to the baffle, the opposite end affixed to the steel rail of the kiln. Additional steel baffle stems can be used with one end of a stem affixed to the baffle, the opposite end affixed to the inner surface of the inner kiln core. The baffle has a thickness in the range of 0.25-5 inches.
The carbonaceous material external to the kiln is loaded into the inner core through the first airlock by means of a belt, one end of the belt positioned near the bottom of an external carbonaceous material mound and the other end positioned by or near the first airlock. The heating coils positioned on the inner surface of the outer shell provide means for transferring heat to said carbonaceous material in the kiln core, the heat being crucial for operating the pyrolysis. The carbonaceous material to be pyrolyzed can consist of coal, biomass or a combination of the two.
During the pyrolysis process, a motor with a second gear is engaged with the first gear attached to the circumference of the proximal end of the kiln core to cause rotation of the kiln core. Due to rotation of the inner kiln core, lateral movement of carbonaceous material from proximal to distal end of the inner core occurs in combination with the action of the helical rail within the inner kiln core.
Typically, the length of the kiln is in the range of 10 feet to 200 feet, while the diameter of the kiln shell is less than 18 feet but more than 1 foot. The radius of the core is at least 10% less than that of the kiln shell. The heating coils are programmed to provide a temperature of approximately 100 C at the proximal end of the kiln core and approximately 500 C at its distal end. The heating of the carbonaceous material, coal and/or biomass near the proximal end of the core partially gasifies and those gases are drawn off by the first fan through the first tubulation and first rotating seal into a first condenser/separator. Heating of said carbonaceous material (coal and or/biomass near the distal end of the core gasifies the carbonaceous material at the much higher temperature, i.e. ˜500 C, and these gases are drawn off by the second fan through tubulation and a second rotating seal into second said condenser separator. These gases are rich in useful hydrocarbons and therefore have high caloric value. These desirable caloric rich gases also contain some water vapor and hydrogen and other impurities which has not been drawn off at the proximal end, but contain mostly hydrocarbons and some traces of high temperature volatiles contaminants which are separated at the second separator and clean up station.
A control unit is part of the pyrolysis system and has means for controlling and regulating the temperature of the a pyrolyzing system by way of signals transmitted to the unit from the thermal sensors mounted within said pyrolyzing system, that is in the space between the kiln shell and the kiln core. This unit also regulates the rotational speed of the first and second fans mounted respectively at the proximal and distal ends of the kiln core. In addition, the control unit also has the means to regulate the rotation speed of the kiln core.
Since not all of the carbonaceous material is gasified in the pyrolysis process, there remains some solid material, i.e. char which can be released at the distal end of the kiln through the second airlock at the distal end and collected in a char receptacle from the core by way of the second airlock.
a is a detail of a motor and gear structure to implement rotation of the inner core carrying the material to be processed by way of heat from the heating coils mounted on the inner surface of the kiln shell. Rotation of the inner core occurs when the gear surrounding the inner core is engaged with the gear driven by the motor which in turn causes the carbonaceous material to move from the proximal to the distal end.
Generally in the pyrolysis of coal and/or biomass, it is useful to eliminate as much water as possible during the pyrolytic process.
As shown in the figure, a portion of carbonaceous coal and/or biomass 1000 from coal or biomass heap 100 is fed through an airlock 102 located at the proximal end of the inner kiln core 104 and dropped into inner kiln core 104 by means of the moving belt 101. Airlock 102 consists of an outer casing containing a finned wheel 1021 that rotates when a fin is loaded with coal or biomass 100. The fins 1021 of airlock 102 act to allow only a minimum of air to enter inner kiln core 104 during the loading of coal or biomass 1000 from coal pile 100 by way of belt 101. Heater coils 1020 bring the coal or biomass 100 inside kiln 104 to an increasing temperature as kiln 104 rotates within the outer shell 103, thereby moving coal 1000 from the proximal to the distal end of kiln core 104 by means of a helical steel rail 105 rigidly attached to the inner wall of kiln core 104. Kiln 104 can be heated to a uniform temperature along its entire length or to a specified temperature gradient, starting with a lower temperature ˜100-225 C at the proximal end and ˜500 C at the distal end. Typically the coal 1000 will be heated from the lower temperature ˜100-225 C as it enters kiln core 104 to a temperature ˜500 C as it travels through kiln 104 where the heat is supplied by the heat coils 1020. Thermocouples 118 spaced along the length of outer kiln shell 103 and located in the space between kiln shell 103 and kiln core 104 relay temperatures within the outer kiln shell 103 to control unit 124,
Near the distal end of kiln core 104, the hydrocarbon gases are driven by a second fan 111 with fan blades 1111 through tubulation 1011, which directs the hydrocarbon gases to a second condenser separator 112. From there fan 111 directs the gases from separator 112 to the hot gas clean up system 113.
A second airlock 114 mounted near the distal end of kiln core 104 receives heated coal or biomass 1000 which remains in the solid state while traversing the length of kiln core 104 from the proximal to the distal end. At the distal end of 104 airlock 114 directs coal or biomass 1000 by way of fin 1141 into chute 1115 and into vessel 115. This discharged coal 116 is in the form of char, useful as a caloric fuel. Kiln shell 103 is mounted on legs 106.
The temperature of coils 1020 is controlled by the master control unit 124 shown in
