Patent Application
20140203459
This invention relates to steam dispersion humidification and in particular relates to a steam dispersion system, apparatus and method of humidifying air having a combined open and closed loop system. More specifically the invention relates to a steam dispersion system having steam dispersion pipes, a source of steam at a pressure higher than atmospheric and a steam header having one end communicating with the source of steam and another end supplying humidification steam to the steam dispersion pipes.
Most modern commercial and industrial buildings are equipped with steam humidifiers mounted within the heating and air conditioning systems. Steam from the steam boiler, district steam system or steam generating humidifier is introduced into a ducted air stream and distributed throughout the building. Generally speaking, it is not advisable to allow humidification steam to condense into water in a duct system as such damp areas can become breeding grounds for algae, bacteria and organic contamination.
There have been a variety of steam humidification systems, apparatus and methods that have heretofore been developed in order to control condensate. For example, US Publication US2009/0121367 relates to a steam dispersion apparatus having a steam chamber communicating in an open-loop arrangement with a first steam source for supplying steam to the steam chamber, which steam chamber includes a steam dispersion location at which steam exits therefrom at atmospheric pressure. The heat exchanger communicates in a closed loop arrangement with a second steam source for supplying steam to the heat exchanger at a pressure higher than atmospheric pressure to convert condensate formed by the steamer chamber back to steam when the condensate contacts the heat exchanger.
Another arrangement is illustrated in U.S. Pat. No. 5,516,466 which relates to a steam humidification system comprising a manifold for receiving steam and at least one steam dispersion tube extending from the manifold for receiving steam. U.S. Pat. No. 6,065,740 shows a steam distribution device for a steam humidification system comprising a horizontally mounted steam dispersion element for receiving steam from the source of steam and for dispersing a portion of the steam into an air stream.
Moreover, U.S. Pat. No. 6,227,526 illustrates a steam dispersion device for a steam humidification system which includes a source of steam, a horizontally mounted steam dispersion element for receiving steam from the source of steam and for dispensing a portion of the steam into an air stream, a horizontally mounted jacket partially surrounding the steam dispersion element and unconnected to the source of steam for maintaining the temperature of the steam dispersion element at or about the temperature of the steam.
U.S. Pat. No. 4,913,856 relates to a humidifier system where atomized water is caused to be rapidly evaporated as a result of being strategically located in the path of high velocity turbulent air created by converging deflector vein sets. Yet another arrangement is shown in U.S. Pat. No. 5,543,090 which relates to apparatus for introducing steam into an air stream in an HVAC system which includes a supply header-steamed dispersing structure and structure reflecting condensate from the steam dispersing structure.
Moreover, U.S. Pat. No. 6,065,740 relates to a steam distribution device for a steam humidification system. U.S. Pat. No. 6,227,526 relates to a steam distribution device for a steam humidification system which includes a source of steam, a horizontally mounted source of steam dispersion element for receiving steam from the source of steam and for dispersing a portion of the steam into an airstream.
U.S. Pat. No. 6,488,219 shows a steam humidifier with pressure variable aperture. Also, U.S. Pat. No. 6,631,856 illustrates a humidifier for providing moisture to an airstream which comprises a pipe having a first end for connecting to a source of steam end a closed second end; first and second slots disposed opposite each other and longitudinally along a major portion of the length of the pipe; and a plurality of members sandwiched within the first and second slots, the members being disposed toward the interior of the pipe to guide condensate into the interior of the pipe. Also U.S. Pat. No. 7,980,535 teaches a demand activated steam dispersion system.
Moreover, there are various prior art devices and methods which illustrate a variety of steam distributors or pipe. For example, U.S. Pat. No. 4,265,840 teaches a vapour distributor pipe for an air humidifier.
Furthermore, U.S. Pat. No. 5,126,080 relates to apparatus for introducing steam into an air stream in a heating, ventilating and air conditioning system which includes a supply header, steam distributing structure and structure for collecting condensate from the steam distributing structure. This patent also illustrates a variety of distributor pipes. Also, U.S. Pat. No. 5,372,753 illustrates an apparatus for introducing steam into an air stream in an HVAC humidification system which illustrates distribution pipes disposed in a vertical orientation.
The prior art also discloses a variety of different apparatus and methods for insulating the distribution apparatus in an effort to minimize condensate. For example, U.S. Pat. No. 7,744,068 teaches a distribution system which includes insulation where the insulation covers at least a portion of the steam dispersion tubes, the insulation defining an opening aligned with the opening of the steam dispersion tube where the insulation meets 25-50 flame/smoke indices for UL 273/ASTME-84 and has a thennal conductivity less than about 035 Watts/n-K (2.4 in/hr/st2deg Fl. The insulation includes polyvinylidene flouride.
Moreover, U.S. Pat. No. 8,092,729 relates to a method of attaching insulation to a steam dispersion tube where the insulation includes polyvinylidine flouride.
These and other prior art systems, apparatus and method relating to humidification dispersion systems present relatively complicated structures. Moreover, the dispersion pipes and insulation methods and systems present relatively complicated structures.
Accordingly, it is an object of this invention to provide an improved steam dispersion system, apparatus and insulation as compared to the prior art.
It is an aspect of this invention to provide a steam dispersion system comprising steam dispersion apparatus, a source of steam at a pressure higher than atmospheric, a steam header communicating with the source of steam and operable in a closed and open loop for supplying humidification steam to the steam dispersion apparatus configured to provide humidification steam to the air in the open loop, and inhibiting the fonnation of condensate in the steam dispersion system in the closed loop. The steam in the heat exchanger is at a pressure higher than atmosphic, while the pressure in the dispersion apparatus is at atmospheric pressure.
It is another aspect of this invention to provide steam distribution apparatus comprising a heat exchanger header defining a chamber, a steam distribution apparatus communicating with the heat exchanger chamber, a source of steam at a pressure higher than atmospheric, a heat exchanger having one end communicating with the source of steam at a pressure higher than atmospheric, and another end of the heat exchanger for communicating with the chamber and steam dispersion apparatus at atmospheric pressure; a control valve for operating the heat exchanger header in an open-loop for supplying humidification steam to the steam distribution apparatus at atmospheric pressure; an isolating valve operating in a first preheat stage to preheat the heat exchanger, heat exchanger header.
It is a further aspect of this invention to provide a method of humidifying air using steam comprising supplying a source of steam at a pressure above atmospheric pressure to a heat exchanger disposed within a header defining a chamber wherein the chamber communicates with steam distribution pipes communicating with the air at atmospheric pressure; isolation valve for supplying the steam to the heat exchanger at a pressure above atmospheric to heat the chamber in a closed-loop, and a controller valve supplying steam to the chamber and distribution pipes to supply humidification steam to the air.
Still another aspect of the invention relates to a steam dispersion system comprising: steam dispersion apparatus; a source of steam at a pressure higher than atmospheric; a heat exchanger communicating with the source of steam and operable in a closed and open loop; an isolating valve to pre-heat the heat exchanger in a pre-heat closed loop cycle and act as a re-evaporator of condensate in a humidification cycle (when the steam control valve is in the humidification cycle); a steam control valve to operate the steam dispersion system in an open-loop having a pre-heat cycle so as to inhibit condensate formation followed by a control cycle to provide controlled humidification.
Yet another aspect of the invention relates to a nozzle for steam dispersion tubes, the nozzle comprising a body extending longitudinally about a generally cylindrical axis; a hole through the body whereby the hole has an axis disposed at an acute angle relative to the cylindrical axis to assist in discharging any condensate by gravity.
Another aspect of the invention provides insulation for a steam dispersion tube having an outer wall with a plurality of aligned nozzles, said insulation disposed about said outer wall where the cross section of said insulation in the vicinity of the nozzles is less than the cross section of the insulation remote from said nozzles.
These and other objects and features of the invention will now be described in relation to the following drawings.
a, 2b, and 2c, are side views, elevational view, and exploded view respectively of the steam dispersion system shown in
a and 3b are actuated steam control valve operating sequence charts in a pre-heat stage and a controlled stage respectively.
a, 5b, 5c are elevational, front elevational and exploded views of the embodiment shown in
a, 8b, 8c are schematic side elevational views, another side elevational view, and a exploded view, respectively, of another embodiment of the invention where the distribution tubes are in a horizontal orientation.
Like parts are given like numbers throughout the drawings and description herein. In the drawings, embodiments of the invention are illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, and are not intended as a definition of the limits of the invention.
In particular, the steam distribution apparatus 4 includes a steam header 6, a heat exchanger 8 and the piped assembly apparatus as shown in the drawings. The steam header 6 can comprise of a variety of materials including sheet metal, steel, iron, cast iron, copper or the like. The steam header 6 can be made from two or more pieces so as to permit the insertion of the heat exchanger 8 within a steam header chamber 11. The heat exchanger 8 as disclosed in
The steam distribution apparatus 4 also includes a steam source 50 with a primary steam supply line 9 that communicates with the primary steam inlet 32 that will communicate with the heat exchange chamber 10 so as to heat up the heat exchanger 8 and header 6. Thereafter steam will exit the steam outlet 34 toward a steam separator 26. The steam separator 26 separates the steam 25 into two paths namely S1 and S2. The steam S1 communicates with the steam supply pipe 10 that feeds the steam injector 40 disposed in the header 6 as shown in
The steam distribution apparatus to be described herein has been designed so as to minimize the presence of condensate and thereby provide a more efficient steam distribution system 2 and apparatus 4.
In the embodiment shown in
The control steam supply pipe 10 (see port 43) coming from the actuated steam control valve 18 will be connected to the steam injector 40 placed above the heat exchanger 8 so that any residual condensate in that pipe will fall on the upper part of the heat exchanger 8.
In particular part of the steam injector 40 can also extend into the steam header 6 and will include exit steam holes 16 pointing downwards toward the heat exchanger 8 in such a manner so as to have any residual condensate after the actuated steam control valve 18 fall on the upper part of the heat exchanger 8.
The heat exchanger 8 has in one embodiment a construction comprised of an inlet primary steam supply pipe 9 which communicates with the isolation valve 20 directly into the heat exchanger 8 by connecting the primary steam inlet 32.
As best illustrated in
The controller 60 can comprise of a variety of devices including computers, micro processors, or the like. In one embodiment, the controller 60 can be wired to the various steam distribution apparatus 4 as described in this application or it can communicate wirelessly with the steam distribution apparatus 4 both in sending and receiving signals therefrom.
In one embodiment of the invention, the temperature range of the distribution apparatus 4 can be pre-programmed in the controller 60.
The controller 60 reads the temperature at the upstream temperature sensor 22 and compares it to a pre-determined range of operational temperatures. The temperature range can be derived from the system's steam pressure.
The isolating valve 20 can be programmed to fully open only if the temperature at sensor 22 falls within the pre-determined temperature range. The steam from source 50 will then heat up the heat exchanger 8 and the steam separator 26 and the temperature sensor 24 downstream of the heat exchanger 8. When the temperature at the temperature sensor 24 is within a pre-determined selected temperature range, the actuated steam control valve 18 opens at a controlled opening speed and to a pre-determined or selected pre-heat partial opening of the valve 18.
The actuated steam control valve 18 will remain in this position for a pre-determined heating delay, or cycle. Accordingly, the slower opening of the actuated steam control valve 18, the partial opening of the actuated steam control valve 18 and the delay period are forced or controlled by the controller 60 in order to ensure controlled pre-heat of the atmospheric section of the apparatus to be described herein and thus preclude sudden formation of condensate and the resulting ejection of that condensate through the steam distribution tubes 12 into the air ducts.
After the controlled pre-heat cycle of the atmospheric section of the apparatus 4 the actuated steam control valve 18 will then assume its normal control function responding to the actual humidification demand from a humidistat (not shown) by means of the controller 60.
If at any time the temperature read by temperature sensor 24 downstream of the heat exchanger 8 and or at the upstream temperature sensor 22 drops under the selected preset required temperature range, the actuated steam control valve 18 will close at maximum speed, leaving the isolation valve 20 open so as to raise the temperature.
When the humidity demand is satisfied, the actuated steam control valve 18 will close and after a pre-determined delay, the isolating valve 20 will also close. This will allow substantially all the condensate to be re-evaporated by the heat exchanger 8.
The temperature range of operation is selectively preset in the controller 60 by means of the steam supply pressure in accordance with thermodynamic laws where the steam temperature can be determined by a person skilled in the art.
The low temperature and high temperature of the temperature range may be selectively set in the controller 60 according to these thermodynamic laws; as well as taking into account cumulative errors including errors in sensor readings. For example, the following illustrates one particular setting, although other settings can be selected.
Sensor error has been included above since the sensor in one embodiment can be a brass thermo where the read temperature differs from about 5 degrees celsius from the real temperature value.
By using the temperature read at the temperature sensor upstream of the isolating valve 20, the steady state temperature can in one embodiment be determined and recorded in the controller. In this case, the temperature must remain constant with +/−0.5 degrees centigrade for 20 seconds in one of the embodiments of the invention. The recorded temperature will then be the steam temperature (from thermodynamic laws)−sensor error.
The sequence described above automates the humidifier temperature range operation for any steam supply. The humidifier will properly work even if the steam pressure is unknown by the user and the manufacturer. In other words, the system described herein is self-adjusting to the temperature range.
a illustrates one embodiment of an actuated steam control valve opening sequence. In particular
The actuated steam control valve 18 opens at a pre-set opening speed POS until the pre-heating valve position PVP has been reached. This represents the first pre-heating time frame 100 to 102 and the slope 99 in
The pre-heating stage 100 to 104 inhibits the fonnation of condensate “spitting” within the system.
b is a representation of the controlled humidification stage which occurs after the preheat stage 104.
After the pre-heat stages 100 and 104 the controller 60 switches from pre-heat operation to control operation based on the humidification demand from the humidistat sensor and sends the proportional demand signal to the control actuated valve 18. The actual humidity in the duct work or in the space to be humidified is read by the humidistat sensor, that communicates with the controller 60. If the humidification demand is lower than the humidity reading by the humidistat sensor, the actuated control valve 18 will close to the proportional position as might be represented by the line 104 to 105. The slope 107 represents the speed of closure of the valve 18.
In one embodiment of the invention normal control speed has a faster closing than opening speed.
If the humidity demand is higher than the humidistat reading the controller 60 will further open the control valve 18 to the proportional position as might be represented by the line 104 to 103. The valve 18 will open at a pre-determined speed as represented by the slope of line 104 to 103. Line 103 to 105 represents closing of the steam control valve 18; and as previously stated occurs at a faster speed than opening. Thus the slope 109 is steeper.
It is possible that the humidity demand is the same as the humidistat reading in which event the steam control valve 18 will remain in its last position.
Once there is steam demand the following steps are implemented:
The controller 60 communicates with inputs from upstream temperature sensor 22, downstream sensor 24, and humidistat. Controller 60 controls or sends an output to steam control valve 18 and isolating valve 20. Communication between controller 60 and the various devices is either by direct wire connection (not shown) or by wireless means in a manner known to persons skilled in the art.
It will be appreciated by a person skilled in the art the vertically orientated distribution tubes 12 are disposed within a duct of an HVAC system. Accordingly, the distribution tubes will be disposed in a generally atmospheric pressure duct system. The steam from the source 50 is typically at a 3-15 psi pressure at 105-121 degrees centigrade respectively. However, the system can operate above 15 psi and the temperature of the steam can also be at other operating temperatures if operated with the invention as described.
Accordingly, the system 2 as described herein warms up the steam distribution apparatus 4 so as to substantially eliminate the condensate. Generally speaking the condensate if injected into the duct work within a HVAC system promotes the breeding of bacteria and viruses or the like which is an undesirable condition.
Furthermore, the actuated steam control valve 18 is moved (ie opened) to the pre-heating valve position PVP so as to wann up the distribution pipes 12 prior to nonnal modulating or control operation of the humidifier output. At nonnal control operation the output is proportional to the signal sent to control valve 18 from controller 60.
Furthermore, another embodiment of a horizontally disposed steam header 6 is illustrated in
The steam header 6 includes a portion of the primary steam supply line 9 inside the steam header 6 which loops around to communicate with an internal end 3 of the heat exchanger 8. This heat exchanger 8 also includes an exterior steam outlet 34.
Furthermore, the header 6 also includes angled surfaces 30 as previously described so as to force any condensate in closer proximity to the heat exchanger 8 by gravity.
Furthermore, the top ends of the vertical steam distribution tubes 12 include a V-shaped channel 13 so as to fasten the ends of the vertical distribution tubes 12 by means of fasteners 15 and rigidify the apparatus.
Furthermore,
The operation of the embodiment shown in
The steam distribution apparatus as illustrated in
a, 8b, and 8c illustrate another embodiment of the invention whereby the steam header 6 is disposed in a vertical position and the horizontal steam distribution tubes 19 are disposed in a generally horizontal disposition relative to the steam header 6. More particularly, the horizontal steam distribution tubes 19 are disposed at an acute angle a such that any condensate within the tube 19 will float downwardly toward the frustoconical collectors 23 as best illustrated in
The frustoconical collectors 23 are fastened to the outside surface of the heat exchanger 8 by press fit, soldering, welding, fasteners or the like. The heat from the outside of the heat exchanger 6 will re-vapourize any condensate 29. A plurality of frustoconical collectors 23 are disposed along the outside surface of the heat exchanger 8 as illustrated in
Furthermore,
Moreover,
Furthermore,
Moreover,
The invention described herein has a number of advantages:
The material used for the insulation is silicone foam rated UL723 and also UL94 VI. The foam reduces at maximum the heat transfer increasing the efficiency of the humidifier. The steam distribution system 2 and steam distribution apparatus 4 described herein includes the following advantages:
