JPH08257340A - Heat recovery in pressure swing type method for adsorption - Google Patents

Abstract

PURPOSE: To increase energy efficiency of a PSA system by collecting waste heat generated in the PSA system and preheating with this waste heat a supply gas mixture passing to a compressor. CONSTITUTION: Product oxygen from the PSA system is passed through a pipe 1 to a product oxygen compressor 2 and compressed to the desirable level. After passing this compressed oxygen from a pipe 3 to a product heat exchanger 4, the oxygen is supplied from a pipe 5. In the product heat exchange 4 the product oxygen and a cooling fluid are cooled by heat exchanging, the cooling fluid is heated and passed into a heat exchanger 8 for preheating supply air from a pipe 7. Here a supply gas mixture is pre-heated by using the waste heat, while the cooling fluid is cooled again and recycled to the product heat exchanger 4. Consequently the supply gas mixture can reach at a higher temperature than a heated temperature under an environmental condition at lower temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure swing adsorption method for gas separation, and more particularly to recovery and utilization of waste heat in the pressure swing adsorption method.

[0002]

The pressure swing adsorption (abbreviated as "PSA") method is the preferred method for separating and purifying gases, such as in the process of producing oxygen or nitrogen gas by air separation. In general, the PSA method (1) selectively adsorbs easily adsorbed components in a feed gas mixture at an overpressure, that is, at a high pressure (above atmospheric pressure) (referred to as “adsorption high pressure”), and removes components that are difficult to be adsorbed. Includes operations of discharging, (2) desorbing components that are easily adsorbed under reduced pressure (vacuum) desorption pressure, that is, desorption low pressure (low pressure for desorption), and (3) repressurizing from desorption low pressure to adsorption high pressure. . These operations, and variants thereof, comprise a PSA consisting of one or more adsorbent beds containing adsorbents that selectively adsorb easily adsorbed components in the feed gas mixture and can be separated from less adsorbed components.
(Pressure swing adsorption) system. PSA
Each operation of the process is carried out within each adsorption bed (also referred to simply as "bed") on a cycle basis (in a cyclical manner) that correlates with the performance of the operating order of the other beds in the system. PS
Although various kinds of adsorbents suitable for use in the method A are commercially available, a convenient adsorbent is a zeolite capable of selectively adsorbing nitrogen from supply air (raw material air). It is a zeolite-based molecular sieve material such as 5A or 13X.

In operation of the PSA system, heat is released during adsorption and absorbed by the adsorbent during desorption. Therefore, the temperature of the adsorption bed rises during the adsorption operation,
It decreases during the desorption operation. For example, in a typical PSA process for producing oxygen and / or nitrogen from air,
Since the forward (forward) flow rate of the gas during the adsorption operation exceeds the backward (forward) flow rate of the gas during the desorption operation, there is a net forward flow of heat, which causes PS
It tends to lower the average temperature of the adsorption beds used in the A system.

Prepared by the PSA process, especially by the ion exchange of modern high performance adsorbents (adsorbents with strong adsorbents for easily adsorbed components in the feed gas, eg LiX, CaX, or sodium type zeolites). The PSA process using other zeolites) is very sensitive to the temperature of the adsorbent. Reduced pressure or vacuum (lower than atmospheric pressure)
Vacuum pressure swing adsorption (“VP
The PSA process, including the process referred to as "SA" for short), is believed to operate most advantageously when the temperature in the adsorbent bed is at a certain temperature. The data obtained by the field tests show that if this optimum temperature in the adsorption bed is not controlled, performance fluctuations (performance deterioration) of 10% or more can occur. It is important to note that VPSA systems that use high performance adsorbents use a lower pressure ratio (higher adsorption to desorption lower pressure) compared to conventional PSA systems. As a result, the amount of heat due to the heat of compression generated by the supply air delivery machine or compressor is relatively low. This heat defines the temperature of the supply air and thus the temperature of the adsorbent. Thus, the feed air and adsorbent temperatures are primarily a function of ambient conditions. Since a high performance adsorbent may require a certain temperature to achieve its desired performance, an efficient method of adding heat to the adsorbent in addition to the heat supplied by the feed air compressor. Often it is important to find out.

Since the temperature of the feed air depends on changes in ambient temperature, the heat of compression of the feed air alone may not always be sufficient to achieve the desired adsorbent bed temperature level.
Adequate adsorbent temperature levels are provided under warm ambient conditions because the heat of compression from the feed air delivery machine generates sufficient heat to heat the adsorbent sufficiently above the ambient temperature to the desired level. Is naturally obtained. However, if the heat of compression is not sufficient to meet such a thermogenic purpose, then the adsorbent, or temperature-supplied air or other supply should be used to raise the adsorbent temperature and optimize system performance. Other means for heating the gas must be provided. In that case, care should be taken not to associate warm and cold ambient temperature conditions with a particular temperature. For the purposes of the present invention, warm conditions exist when the heat of compression from the feed air produces sufficient heat to obtain the optimum adsorbent bed temperature, and system performance is optimized to obtain the optimum process temperature. Cold conditions may be considered to be present if VPSA or some other means of applying heat to the PSA system is required.

Attempts have been made in the prior art to provide heat to adsorbent beds operating at suboptimal temperatures.
Although compression heat from the supply air is desirable as a heat source for that purpose, a satisfactory means for increasing the compression heat has not yet been found. It has been proposed to place a convection heat exchanger at the inlet of the adsorption bed. The convection heat exchanger also serves to distribute the heat flow generated. It has also been proposed to use a hot process gas to transfer heat directly to the adsorption bed.

[0007]

However, there remains a need in the art for improved means for controlling the temperature of adsorbents for the purpose of enhancing the process performance of PSA or VPSA. It is therefore the object of the present invention to provide an improved means for controlling the temperature of the adsorbent.

It is an object of the present invention to provide an improved method and system for controlling the temperature of adsorbents in the process of air or other gas separation by the PSA / VPSA method. Another object of the present invention is to provide an improved method and system for increasing the energy efficiency of PSA / VPSA systems operating at desired adsorbent temperature conditions.

[0009]

The present invention is a PSA or V
The above problem is solved by utilizing the low-grade waste heat generated in the PSA system itself in order to enhance the performance of the PSA system. Such waste heat, if not in accordance with the present invention, is lost without being utilized for the purposes of the air or other gas separation process contemplated, but by utilizing it in accordance with the teachings of the present invention. The energy efficiency of the system and thus the overall performance of the system can be improved.

The present invention achieves the above objectives by recovering and utilizing the waste heat lost in the prior art in the air or other gas separation process by the PSA or VPSA process. Feed air (feed air) or other feed gas (feed gas) is delivered to the adsorption bed of the PSA or VPSA system by a feed blower, but according to the present invention, the feed air or feed gas fed to the feed blower. Use the waste heat described above to preheat. The recovery and utilization of this waste heat can increase the energy efficiency of the air or other gas separation process. In addition, by increasing the temperature of the feed air or other feed gas sent to the feed blower, the PSA
/ The compressed feed gas passed to the VPSA system can be at a temperature higher than that obtained by simply compressing the feed gas under ambient temperature conditions, thereby obtaining the desired bed temperature. . Thus, when the present invention is carried out under low ambient temperature conditions, it provides an advantageous means for obtaining the desired bed temperature. Thus, the present invention provides that whenever the heat of compression generated during the operation of compressing the feed gas to reach the desired adsorption high pressure level is not sufficient to obtain the desired temperature conditions for optimal operation of the PSA / VPSA system. It makes it possible to obtain the desired temperature conditions in a convenient and efficient manner.

[0011]

EXAMPLES In the embodiment of the invention illustrated in FIG. 1 of the accompanying drawings, the product oxygen from the PSA or VPSA system (simply “product”, “oxygen”, “product gas”, “oxygen gas”). Or “gas”) is sent through conduit 1 to the product oxygen compressor 2 and compressed to the desired level. This compressed oxygen is sent to the product heat exchanger 4 via conduit 3 from which the product oxygen is recovered via conduit 5 for delivery to the customer or desired department of use. In the heat exchanger 4, in order to recover the product oxygen, the heat of compression thereof,
It is cooled by heat exchange with a cooling fluid (preferably water) sent through conduit 6. On the other hand, the cooling fluid, after being heated in the heat exchanger 4, is sent from there through the conduit 7 to the supply air preheating heat exchanger (also simply referred to as “preheater”) 8. The cooling fluid is then cooled in the heat exchanger 8 and then recirculated from there through the conduit 9 to the product heat exchanger 4. Optionally, the fluid flow through conduit 9 may be passed to another heat exchanger or cooling tower prior to being recycled to product heat exchanger 4. Supply air (raw material air)
Is preheated by passing through the conduit 10 to the preheating heat exchanger 8 and then through the conduit 11 to supply air blower (compressor)
It is sent to 12 to be compressed to the desired adsorption operating level and then to a working PSA or VPSA system for air separation and product oxygen recovery through conduit 13.

In the embodiment of FIG. 1, of the waste heat recovered in the preheating heat exchanger 8 using the bypass control means for use in preheating the feed air to the PSA or VPSA system. The amount can be conveniently controlled.
To this end, a bypass conduit 1 having a bypass control valve 15 for bypassing a portion of the heated cooling fluid that is sent through conduit 7 to preheating heat exchanger 8.
4 can be used. Under relatively warm ambient conditions, the amount of preheating of the feed air through the conduit 10 in the preheating heat exchanger 8 may be small and may be passed through the preheating heat exchanger 8 to slightly preheat it. Once done, and then compressed by the feed air blower 12, the feed air is sent through conduit 13 at a temperature desired to obtain the desired temperature conditions in the downstream PSA or VPSA system.
Also, as a modified embodiment of the present invention, compression of the supply air alone without the need to extend and heat the supply air by recovery and utilization of waste heat is sufficient to obtain the desired temperature conditions during the PSA or VPSA air separation process. Under such warm ambient temperature conditions, all or part of the compressed product oxygen through conduit 3 may be bypassed by heat exchanger 4.

In the implementation of the embodiment shown in FIG.
A product aftercooler (aftercooler) as a heat carrier for heating the feed air (or other feed gas) by a heat exchanger, such as the preheating heat exchanger 8 described above, before sending it to the feed air blower 12. ), An intercooler or other heat exchanger connected to the product compressor,
It will be apparent to those skilled in the art that the product booster compressor, or the hot chilled fluid exiting the decompression vacuum blower (vacuum pump) oil cooler unit can be used. This heat exchange of the feed air prior to feeding it to the feed air blower 12 allows a maximum temperature difference to be established between the feed air and the hot water or other heated cooling fluid, which Allows the most efficient heat transfer between the feed air (or other feed gas) and the cooling fluid to be achieved. Although there may be certain conditions in which sufficient adsorbent temperature is obtained by heat exchange with the compressed feed air alone, the amount of heat obtained by compression of the feed air alone is in accordance with the present invention. This is less than when the supply air is heated on the upstream side of the supply air blower 12 by the waste heat.

As is clear from the above description, it is necessary to first determine whether or not there is a need to apply the present invention. For this purpose, first the feed (feed air or other feed gas) temperature required to obtain the desired bed temperature is measured. For example, the average supply pressure of a certain VPSA system (the average pressure of the supply air supplied to the system) is 5 ps.
ig (0.35 Kg / cm ² ), the temperature rise due to the heat of compression when the feed air is compressed to its pressure level is about 50 ° F. (27.8 ° C.). The value of this temperature rise can be found by consulting with the blower manufacturer as in the case of this example of the present invention, or the efficiency of the supply air blower and its motor can be inferred, so The amount of energy transfer into the air can be easily calculated. By knowing the value of this temperature rise, it is possible to know whether or not heat must be added to the feed air in order to bring the inlet temperature (introduction temperature) of the feed air to the adsorption bed of the PSA / VPSA system to the desired adsorption temperature. be able to. For example, assuming that the optimum feed air temperature for a particular air separation process is 100 ° F (37.8 ° C), the feed air blower and PSA or VPSA system may have an ambient temperature below 50 ° F (10 ° C). Exposure to the desired optimum supply air temperature (100
To obtain ° F (37.8 ° C), it is necessary to add heat to the feed air. By calculating the mass flow rate of the feed air, the amount of additional heat needed to obtain the desired adsorption temperature can be easily determined. The present invention is shown in FIG.
To optimize the energy efficiency of the PSA / VPSA process for air or other gas separation and its process performance by effectively utilizing the waste heat that would otherwise be lost, as in the example shown in FIG. Thereby increasing the overall technical and economic suitability of using the desired PSA technology in an actual commercial gas separation process.

In the embodiment of the invention illustrated in FIG. 2, a vacuum blower (vacuum) as a waste heat recovery source for preheating feed air or other feed gas prior to compression to the desired adsorption high pressure level. Use warm drain water from the pump) effluent separator. This water contains the seal water for the vacuum blower and the water separated from the desorbed components in the air or gas separation step, and can be collected in a separate drain water collection container.

In the embodiment of FIG. 2, the easily adsorbed components desorbed from the adsorbent are sent to the decompression blower (vacuum pump) 23 through the conduit 21 together with the decompression blower sealing water from the conduit 22. The effluent of the vacuum blower is desorbed at low pressure (vacuum) through conduit 24 to a conventional effluent separator 25.
From which the susceptible components in the feed gas mixture to be separated are extracted via conduit 26. In the air separation step for producing oxygen as a component that is difficult to be adsorbed in the supply air, the desorbed component that is easily adsorbed is nitrogen, and nitrogen is usually discharged as waste.

The warm drain water from the effluent separator 25 is collected in a drain water collection vessel 28 via conduit 27.
For purposes of the heat recovery of the present invention, this warm drain water is pumped by a sump pump 30 through conduit 29 to a preheat heat exchanger (also referred to simply as "preheater") 31. The drain water cooled by releasing heat in the preheating heat exchanger 31 is discharged through the conduit 32. The feed air or other feed gas to be separated by the PSA process is fed via the conduit 33 to the preheating heat exchanger 3
1 and then preheated in the preheating heat exchanger 31 and then sent to a feed blower (compressor) 35 through a conduit 34 for compression and PSA at a desired adsorption high pressure through a conduit 36.
/ VPSA system.

According to the present invention, the calorific value of the warm drain water is lost as low-grade waste heat of the PSA step. However, in the practice of the present invention, the compression heat of the feed gas alone is desirable because of low ambient temperature conditions. If no temperature level is available,
Such waste heat can be advantageously and efficiently utilized so that the desired PSA temperature conditions can be obtained.

The heat useful for the purposes of the present invention can also be collected in various ways from radiant heat sources. For example, convection and radiant waste heat sources recoverable from various process equipment such as process blowers and drive motors therefor, product compressors, closed loop cooling system equipment, process piping, various auxiliary equipment for fluid introduction and discharge, etc. Will be provided.

As shown in FIG. 3, PSA / VPSA
Enclosures to seal some or all of the equipment of the PSA / VPSA system to capture the radiant waste heat for advantageous use to preheat incoming feed air or other feed gas for the system, or An enclosure housing (also simply referred to as an "enclosure") can be used. The enclosure can be an insulated enclosure. The heat trapped within the enclosure is conveniently used to heat the incoming supply air or gas. By placing the inlet filter in the enclosure, the heat radiated and trapped from the enclosed (enclosed) part of the overall system is transferred directly to the feed gas (air) and then the feed gas (air). ) Is sent to the feed gas (air) blower (compressor). That is, in the embodiment of FIG. 3, the enclosure 43 is used to enclose all of the components of the VPSA air separation system and the feed air is fed through the conduit 41 to the inlet filter 4 located in the enclosure 43.
Send to 2. The feed air is sent from the inlet filter 42 through a conduit 44 to a feed air blower (compressor) 45, from which the compressed adsorbed high pressure feed air is fed to the valve 4.
7 through a conduit 46 with a first adsorbent bed (adsorbent bed or layer, also referred to simply as "bed") 48, or valve 47a.
Two-bed VPSA system shown (through two-bed VPSA system with two adsorption beds) through conduit 46a
To the second adsorption bed 48a. A feed unloader conduit 49 having an unloader valve 50 is branched from conduit 46 so that the feed air stream can be split or bypassed for discharge as needed.

A component which is difficult to be adsorbed in the supply air (oxygen when a conventional zeolitic molecular sieve is used to selectively absorb nitrogen from the supply air)
During the adsorption product recovery operation of the VPSA process, from the bed 48 to the valve 5
1 through conduit 67 and from floor 48a to valve 51.
Collect through conduit 68 with a. In the illustrated embodiment, oxygen is delivered from conduit 67 or 68 to product oxygen reservoir 54 through conduit 52 with valve 53. Product oxygen is delivered from this product oxygen storage vessel 54 through a conduit 55 having a product oxygen blower unit 56 from enclosure 43 to the product oxygen customer or product oxygen use department of the VPSA system.

As is well known in this type of VPSA system, depending on the particular operating procedure used in any VPSA air separation process performed in that VPSA system, product oxygen is adsorbed to one of the adsorption beds 48, 48a. Conduit 6 from the top of the bed or product outlet to the other bed
7, 68, or a portion of the product oxygen from the product oxygen reservoir 54 may be returned via conduit 52 to one or the other adsorbent bed.

As shown in the figure, the gas in the supply air,
For example, the nitrogen component that is easily adsorbed can be sucked from the bottom end of the adsorption bed 48 to the decompression blower (vacuum pump) 59 through the conduit 57 having the valve 58 after being desorbed from the adsorbent in the adsorption bed. Similarly, the nitrogen component which is easily adsorbed can also be sucked from the bottom end of the adsorption bed 48a to the decompression blower 59 through the conduit 57a having the valve 58a. The effluent from the vacuum blower 59 is discharged through a conduit 60 to an effluent separator 61 from which it is either disposed of through a conduit 62 or discharged for desired use. On the other hand, drain water from effluent separator 61 is separately extracted through conduit 63 for collection in drain water collection container 64.

The use of enclosure 43 also allows the use of other methods for heat recovery. For example, the heat exchanger unit 65 can be combined with the drain water collecting container 64 described above. As in the illustrated embodiment, the heat exchanger unit 65 can be a fan and finned heat exchanger unit such that heat is radiated from the unit through the entire interior of the enclosure 43, Thereby, heat can be drawn from inside the enclosure 43 by the supply air blower 45 through the inlet filter 42. The drain water is expediently passed through the heat exchanger unit 65 to release its heat to the enclosure 43, after which the conduit 6 is expediently
It can be discharged to the drain or a desired use department through 6.

Those skilled in the art will appreciate that PSA / VP
If the heat required to bring the SA adsorption bed to the desired optimum temperature is relatively small, for example PSA /
It is also within the scope of the invention to utilize heat radiated from only a portion of the PSA / VPSA system by machining only a portion of the VPSA system rather than the front. Recovering heat from the warm drain water discharged from the effluent separator 62 is a convenient and desirable method of waste heat recovery. Enclosure, preferably an adiabatic enclosure 43
Arranging the drain water collecting container 64 therein is a preferable means for recovering waste heat for preheating the supply air (gas) fed to the supply air (gas) blower. In that case, the fanned, finned heat exchanger unit 65 or other heat exchangers described above may or may not be used to facilitate and increase the recovery of heat from the warm drain water.

It will be apparent to those skilled in the art that various changes and modifications can be made in the details of the invention without departing from the scope of the invention as set forth in the claims of this application. Therefore, the present invention is directed to the particular PS used.
It is not limited to A or VPSA processes, but can be applied to air separation as well as other gas separations and is limited to the particular operating conditions used, such as the particular adsorption high pressure and desorption low pressure. Not something. Further, the waste heat captured and utilized in the practice of the present invention is one or a combination of the lower waste heat described above and other lower waste heat generated in a portion of the overall adsorption system. May be. "Low-grade waste heat" here means
Heat generated in the PSA / VPSA system,
Lost in the prior art, any heat source that can be efficiently captured and available to preheat the feed gas before passing it to the feed gas compressor (blower).

A variety of waste heat sources may be used in the practice of the present invention. For example, PS that obtains oxygen as a product
In the A / VPSA system, the waste stream is a nitrogen-rich stream that cannot be safely discharged into the enclosed building. According to the present invention, the waste heat present in the waste nitrogen-rich stream is appropriately heat-exchanged. Can be used to heat certain liquids through which the heated liquids can serve as a heat source for preheating the feed air to be separated. Alternatively, the waste heat can be recovered from the off-line release stream of oxygen that is removed at PSA / VPSA process start-up or during product quality fluctuations. However,
As shown in the embodiment of FIG. 3, the flow of supply air may be discharged directly into the enclosed building. This is because the feed air is not harmful and some heat is generated by the compression of the air during the idling operation of the feed air compressor (blower) that occurs during the treatment cycle of the PSA / VPSA process.

[0028]

In the practice of the present invention, the waste heat recovered and utilized to preheat the feed gas (air) is
Normally, the temperature of the feed gas is at least 10 ° F (5.6 ° C).
C), typically below 80 ° F (44.8 ° C), most commonly about 20-50 ° F (11.2-27.8 °).
It is regulated to raise only C). When the ambient temperature conditions are, for example, 0 ° F (-17.8 ° C), waste heat may be utilized to raise the temperature of the feed gas to about 70 ° F (39.2 ° C). Would be desirable. Alternatively, when the ambient temperature condition is 30 ° F (-1.1 ° C), the temperature of the feed gas is about 40-60 ° F (22.4).
It would be desirable to recover waste heat to raise by ~ 33.6 ° C). In any case, utilizing the lower waste heat generated in the PSA / VPSA system itself to raise the inlet (introduced) gas temperature without external heating means that more of the feed gas is compressed, etc. It was found to surprisingly improve the overall performance of the PSA / VPSA, even if the work is spent.

As mentioned above, to recover waste heat from various heat sources in the PSA / VPSA system and to preheat the feed gas (air) sent to the feed gas (air) blower. Utilization significantly enhances process performance and energy efficiency compared to methods of adding external energy into the system. The present invention also provides the advantage of not requiring complicated adsorbent bed geometries, modification of process operations, reduction of mass flow within the system, etc. to increase heat transfer of the adsorbent.

The following points should be pointed out in order to specifically explain the economic advantage of the waste heat recovery of the present invention as compared with the method of adding external energy into the system. When the temperature of the ambient air is 10 ° F (-12.2 ° C), the discharge temperature of the normal supply air blower of the VPSA (the temperature of the supply air discharged from the blower) is about 60 ° F (15.6). ° C). That is, the supply air is 50 ° F (27.8 ° C) above ambient temperature as a result of being compressed by the supply air blower.
It is heated and discharged. Unlike the present invention, if 10
To obtain the desired feed air temperature of 0 ° F (37.8 ° C), if heat is added to the compressed feed air discharged from the blower, rather than to the inlet (introduction) air to the feed air blower, The associated operating costs and modification device costs are doubled.

Waste heat recovery has not been considered in previous attempts to improve the performance of PSA systems. This is because the PSA system is a system with high capital intensity (initial manufacturing cost), and it has always been a goal to reduce the capital cost (system manufacturing cost) in order to reduce the total cost of the system. . Certainly, some additional capital expenditure (increased equipment cost) is inevitable to recover waste heat. for that reason,
Conventionally, the modification of the device for waste heat recovery has been overlooked, and the technical idea of capturing and utilizing the lower waste heat for preheating before compressing the feed gas has not been conceived. However, the benefits of avoiding the above-mentioned 10% reduction in PSA performance have been found to outweigh the additional capital outlay for waste heat recovery. Furthermore, the present invention enables such benefits to be realized by efficiently capturing and utilizing low-grade waste heat, which has a lower heat transfer capacity than other heat sources. Preheating the cold inlet supply air with waste heat that would otherwise be discarded (according to the invention) to maximize the amount of heat exchange and sucking the enclosure into the inlet supply air Can be used as a heat sink, which provides a highly desirable advantage in heat utilization, resulting in increased energy efficiency and surprisingly enhanced PSA / VPSA performance.

As will be apparent to those skilled in the art, the optimal PSA
Any combination of the various waste heat recovery techniques disclosed herein may be used to provide the desired preheat to the feed gas (air) such that the temperature conditions desired to achieve performance are set in the adsorption bed. Can be used. If more than one waste heat recovery source is used in the practice of the invention, a combination of those waste heat recovery sources is set up to provide the required amount of heat for feed gas (air) preheating. Or
It can be controlled to be released.

In the above description, the present invention has been described especially as applied to a PSA air separation process for producing oxygen, but nitrogen is used as the adsorbable component in the feed gas mixture from helium or hydrogen. The process of separating,
Either nitrogen or oxygen can be applied to various other gas separation processes such as a process of separating nitrogen from air as a component which is easily adsorbed in the supply air.

The present invention provides a highly advantageous means of capturing and utilizing waste heat generated within the PSA system. The convenient recovery and efficient use of waste heat according to the present invention, which does not require the addition of heat from outside the system, enhances the energy efficiency of the PSA process and at the same time improves the overall performance of the PSA system. Let

[Brief description of drawings]

FIG. 1 is an embodiment of the invention in which waste heat recovered from a product compressor or blower of a PSA or VPSA system is utilized to preheat the feed air delivered to the feed air blower. 2 is a flowchart of.

FIG. 2 uses the waste heat present in drain water produced by separating the effluent from a vacuum blower of a PSA or VPSA system to preheat the feed air sent to the feed air blower. 6 is a flowchart of another embodiment of the present invention.

FIG. 3 illustrates an adiabatic enclosure for recovering waste heat from all or a portion of a PSA or VPSA system for use in preheating feed air to a feed air blower of the PSA or VPSA system. 4 is a flow chart of another embodiment of the present invention adapted for use.

[Explanation of symbols]

 2: Product oxygen compressor 4: Product heat exchanger 8: Heat exchanger for supply air preheating (preheater) 12: Supply air blower (compressor) 14: Bypass conduit 15: Bypass control valve 23: Decompression Pump (vacuum pump) 25: Effluent separator 28: Drain water collecting container 31: Heat exchanger for supply air preheating (preheater) 35: Supply air blower (compressor) 42: Inlet filter 43: Enclosure 45: Supply air blower (compressor) 48: first adsorption bed 48a: second adsorption bed 59: decompression pump (vacuum pump) 61: discharge separator 64: drain water collection container 65: heat exchanger unit

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Frederick Wells Levit, Sandriji Drive, Amast, NY, USA 114 (72) Inventor Herbert Raymond Schaub, East Amast, NY, USA Sunburst Circle 185 (72) ) Inventor James Smolarek 6730 Libra Road, Boston, NY, USA

Claims (20)

[Claims] 1. An at least one adsorbent having an adsorbent capable of selectively adsorbing the easily adsorbed component in a feed gas mixture containing an easily adsorbed component and an easily adsorbed component.
A pressure swing adsorption method for separating the easily adsorbed component from the feed gas mixture in a pressure swing adsorption system with two adsorption beds, which is carried out on a cycle basis in each adsorption bed, (1) An operation of introducing a feed gas mixture into the feed end of the adsorption bed at an adsorption high pressure and extracting the component that is difficult to be adsorbed from the opposite end of the adsorption bed, and (2) a component that is easily adsorbed from the feed end of the adsorption bed. The operation of reducing the pressure of the adsorption bed to a desorption low pressure by discharging, (3) the adsorption of the feed gas mixture by the feed gas compressor before passing the feed gas mixture to the adsorption bed in the operation (1). Repressurizing the adsorption bed to the adsorption high pressure by compressing it to a high pressure and heating the feed gas mixture by the heat of compression generated by compression in a feed gas compressor; In the pressure swing adsorption method including: (a) capturing the waste heat generated in the entire pressure swing adsorption system or a part thereof, and (b) sending it to the feed gas compressor by utilizing the captured waste heat. Preheat the feed gas mixture, pressurize the feed gas mixture preheated with the waste heat with the feed gas compressor, and heat with the heat of compression, and then adsorb the feed gas mixture with adsorption high pressure Sent to the bed, thereby increasing the energy efficiency of the pressure swing adsorption method, and by recovering the waste heat,
Allowing the feed gas mixture to reach a temperature above the temperature at which it is heated only by compression of the feed gas mixture under cold ambient temperature conditions, thereby enhancing the performance of the pressure swing adsorption process. Characteristic pressure swing adsorption method. 2. The less adsorbed component extracted from the opposite end of the adsorption bed is compressed to a higher pressure level prior to recovery from the pressure swing adsorption system,
(a) an operation of passing the compressed hard-to-adsorb component to a heat exchanger to transfer the compression heat generated by the compression of the hard-to-adsorb component to a cooling fluid; and (b) supplying the feed gas mixture. A preheater of a cooling fluid heated by heat exchange with the less adsorbed component in the heat exchanger to transfer the heat of compression of the less adsorbed component to the feed gas mixture before passing through the gas compressor. The pressure swing adsorption method according to claim 1, further comprising: 3. An operation of bypassing a portion of the heated cooling fluid by bypassing the preheater so as to regulate the amount of heat transferred from the heated cooling fluid to the feed gas mixture. The pressure swing adsorption method according to claim 2, wherein the adsorption method includes the pressure swing adsorption method. 4. The pressure swing adsorption method according to claim 2, wherein the desorption low pressure is a pressure lower than atmospheric pressure. 5. The hot adsorbent component is aspirated through a process blower to separate warm drain water from the adsorbable component, and the feed gas mixture from the hot drain water is passed through the feed gas compressor. 5. The pressure swing adsorption process of claim 4, wherein the warm drain water is passed to a preheater to transfer waste heat to the feed gas mixture. 6. To capture the heat generated from the components of the pressure swing adsorption system for use in preheating the feed gas mixture prior to passing the feed gas mixture to the feed gas compressor. The pressure swing adsorption method according to claim 1, wherein all or a part of the pressure swing adsorption system is arranged in an enclosure. 7. The component which is easily adsorbed is sucked through a process blower at a desorption and low pressure lower than atmospheric pressure to separate warm drain water from the component which is difficult to be adsorbed, and the warm drain water is disposed in the enclosure. 7. The pressure swing adsorption of claim 6, wherein waste heat radiated from the warm drain water is used to heat the feed gas mixture that is passed to a water collection vessel and sent to the feed gas compressor. Method. 8. The pressure swing adsorption process of claim 7, wherein the feed gas mixture is drawn through an inlet filter located within the enclosure. 9. The pressure swing adsorption method according to claim 7, wherein the supply gas mixture is air. 10. The pressure swing adsorption method according to claim 9, wherein the supply air is discharged from the compressor into the enclosure during an idle operation period of an operation cycle of the pressure swing adsorption method. 11. The warm drain water is passed through a heat exchanger located within the enclosure to facilitate recovery of waste heat from the warm drain water into the atmosphere within the enclosure. The pressure swing adsorption method according to claim 7. 12. At least one adsorption bed having an adsorbent capable of selectively adsorbing the easily adsorbed components in a feed gas mixture containing components that are easily adsorbed and components that are not easily adsorbed. A pressure swing adsorption system for separating the easily adsorbed components from the feed gas mixture, wherein in each adsorption bed, (1) introducing the feed gas mixture at the adsorption high pressure to the feed end of the adsorption bed, An operation of extracting the component that is difficult to be adsorbed from the opposite end of the adsorption bed, and (2) an operation of reducing the pressure of the adsorption bed to a desorption low pressure by discharging a component that is easily adsorbed from the supply end of the adsorption bed And (3)
In the operation (1), the adsorbent bed is compressed by compressing the feed gas mixture to the adsorbed high pressure by a feed gas compressor forming a part of the pressure swing adsorption system before the adsorbent bed is passed through the adsorbent bed. In a pressure swing type adsorption system adapted to carry out the operation of repressurizing the pressure swing type to the adsorption high pressure on a cycle basis, (a) for trapping waste heat generated in the entire pressure swing type adsorption system or a part thereof. Mechanical means,
(b) including means for utilizing the captured waste heat to preheat the feed gas mixture sent to the feed gas compressor, whereby the feed gas mixture sent to the feed gas compressor. Efficiently utilize the waste heat generated in the pressure swing adsorption system to preheat the
Accordingly, the pressure swing adsorption system is characterized by enhancing the energy efficiency and the overall performance of the pressure swing adsorption system. 13. (a) a compression means for increasing the pressure level of the less adsorbed component before recovering the less adsorbed component from the pressure swing adsorption system;
(b) a heat exchanger for transferring the compression heat generated by the compression of the component that is difficult to be adsorbed in the compression means to the cooling fluid from the compression means, and (c) the feed gas mixture to the feed gas compressor. 13. The pressure swing adsorption system of claim 12 including a preheater for transferring the heat of compression from the cooling fluid to the feed gas mixture prior to passage. 14. A control for diverting a portion of the cooling fluid to the preheater to regulate the amount of heat transferred from the cooling fluid to the feed gas mixture in the preheater. 14. The pressure swing adsorption system of claim 13, including means. 15. The pressure swing adsorption system is adapted to operate at desorption low pressures below atmospheric pressure,
(a) a process blower for sucking the easily adsorbed component from the adsorbent bed, (b) a separator for separating the easily adsorbed component from warm drain water carried by it, (c) 13. The pressure swing adsorption system of claim 12, including a preheater for transferring waste heat from the warm drain water upstream of the feed gas compressor to the feed gas mixture. 16. An enclosure is provided that encloses all or part of the pressure swing adsorption system, and heat generated from the components of the pressure swing adsorption system is transferred to the feed gas mixture upstream of the feed gas compressor. 13. The pressure swing adsorption system of claim 12, wherein all or a portion of the pressure swing adsorption system is positioned within the enclosure for capture for use in preheating. 17. The pressure swing adsorption system is adapted to operate at desorption low pressures below atmospheric pressure,
(a) a process blower for sucking the easily adsorbed component from the adsorbent bed, (b) a separator for separating the easily adsorbed component from warm drain water carried by it, (c) Characterized in that it comprises a drain water collecting vessel arranged in the enclosure for using the recovered waste heat from the warm drain water for heating the feed gas mixture fed to the feed gas compressor. The pressure swing adsorption system according to claim 16. 18. The pressure swing adsorption system of claim 17, wherein an inlet filter for the feed gas mixture is located within the enclosure. 19. The pressure swing adsorption system of claim 16 including discharge means for discharging the feed gas mixture into the enclosure during idle operation of the feed gas compressor. 20. (a) a heat exchanger disposed within the enclosure to facilitate recovery of waste heat from the warm drain water into the atmosphere within the enclosure; and (b) the warm heat. 18. The pressure swing adsorption system of claim 17, including a conduit for passing drain water through the heat exchanger.