JP2019196873A - Recovery method of waste heat of air separation equipment and recovery system of waste heat of air separation equipment - Google Patents

Abstract

To provide a recovery method of waste heat of air separation equipment in which steam generated in air separation equipment separating oxygen and nitrogen from raw material air is recovered and thermal energy of the recovered steam is utilized, and a recovery system of waste heat of air separation equipment.SOLUTION: The recovery method of waste heat of air separation equipment is provided that includes; an MS adsorption step of supplying raw material air compressed by an air compressor to an adsorption tower removing impurity in air passing therethrough and cleaning the air; and a rectification step of rectifying and separating nitrogen and oxygen from the raw material air cleaned in the MS adsorption step. The recovery method of waste heat of air separation equipment further includes: a heat exchange step of supplying a part of nitrogen gas discharged from the air separation equipment to a heat exchanger disposed in a discharge route and performing heat exchange; a regenerated gas supply step of generating regenerated gas by heating nitrogen gas in the heat exchanger and flowing the generated regenerated gas in a regenerated gas supply route thereby supplying the regenerated gas to the adsorption tower; and drain supply step of flowing steam drain generated by the generation of regenerated gas in drain supply route provided on the discharge side of the heat exchanger and supplying the steam drain to the other equipment. The recovery method of waste heat of air separation equipment recovers the generated steam drain and uses as a heat source.SELECTED DRAWING: Figure 1

Description

  The present invention recovers waste steam discharged from an air separation facility that separates oxygen and nitrogen from raw air, and uses the heat energy of the waste heat recovery method of the air separation facility and the waste heat recovery system of the air separation facility About.

  A large amount of oxygen is consumed in facilities such as blast furnaces and converters in steelworks. In a place where a large amount of oxygen is required in this way, generally, an oxygen production facility is installed in an ironworks, and oxygen generated by the oxygen production facility is supplied to facilities such as a blast furnace.

  As one of the oxygen production facilities, there is one that produces oxygen using a cryogenic separation type air separation facility that separates air using a difference in boiling points. For example, Patent Document 1 discloses a compressor that compresses raw material air, an air-cooled or water-cooled after cooler that cools the raw material air that has been compressed and heated by the compressor, and the raw material air that is cooled by the after cooler. An adsorber that adsorbs and removes moisture and carbon dioxide that are impurities contained therein (hereinafter also referred to as pretreatment equipment), an air-cooled or water-cooled cooler that cools the raw air purified by the adsorber, and And an air liquefaction separation apparatus having an air separation part for performing cryogenic liquefaction separation of the raw material air cooled by the cooler.

JP 2003-56981 A

  The technique of Patent Document 1 described above is a regeneration in which heated regeneration gas (heated gas) is introduced into moisture and carbon dioxide impurities adsorbed and removed by the pretreatment facility of the air liquefaction separation apparatus, and the pretreatment facility is heated and regenerated. Process. However, the waste steam generated when the heating gas required in the regeneration process is obtained is only released into the air and is not effectively used, so that there is a problem that the energy efficiency is poor.

In recent years, further energy saving and CO ₂ emission reduction are required from the viewpoint of preventing global warming. In facilities such as steelworks, it is also required to develop new technologies for recovering thermal energy such as waste steam generated in the facility and reusing it as an energy source for the steel manufacturing process.

  In view of the problem, the present invention recovers waste steam generated in an air separation facility that separates oxygen and nitrogen from raw air, and uses the heat energy of the waste heat recovery method of the air separation facility and waste heat of the air separation facility. The purpose is to provide a collection system.

  As a result of intensive studies, the present inventors recovered waste steam generated when heating a part of the nitrogen gas discharged from the air separation facility, and supplied the thermal energy to other facilities. We found that we could achieve the purpose.

This invention is made | formed based on the above-mentioned knowledge, and makes the following a summary.
[1] An MS adsorption process for supplying raw air compressed by an air compressor to an adsorption tower that removes impurities in the passing air and cleaning the adsorption tower;
A rectification step of rectifying and separating nitrogen and oxygen from the raw material air cleaned in the MS adsorption step, and a waste heat recovery method for an air separation facility,
A part of nitrogen gas discharged from the air separation facility is supplied to a heat exchanger disposed in the discharge path, and a heat exchange step of performing heat exchange;
A regeneration gas supply step of heating the nitrogen gas in the heat exchanger to generate a regeneration gas, flowing the generated regeneration gas through a regeneration gas supply path, and supplying the regeneration gas to the adsorption tower;
A drain supply step of supplying the steam drain generated by the generation of the regeneration gas to the drain supply path provided on the outlet side of the heat exchanger and supplying it to other equipment,
A method for recovering waste heat from an air separation facility, wherein the generated steam drain is recovered and used as a heat source.
[2] The waste heat recovery method for an air separation facility according to [1], wherein a mechanical pump driven by steam is disposed in the drain supply path to recover the steam drain.
[3] The waste heat of the air separation facility according to [1] or [2], wherein the other facility is a liquid vaporizing and feeding facility that heats liquid supplied from a tank with the vapor drain. Collection method.
[4] An MS adsorber that has an adsorption tower that removes impurities in the passing air, and that supplies raw air compressed by an air compressor to the adsorption tower for cleaning.
A rectifying tower for rectifying and separating nitrogen and oxygen from raw air cleaned by the MS adsorber, and a waste heat recovery system for an air separation facility comprising:
A heat exchanger disposed in a discharge path for supplying a part of the nitrogen gas discharged from the air separation facility;
A regeneration gas supply path for supplying regeneration gas generated by heating in the heat exchanger to the adsorption tower;
On the outlet side of the heat exchanger, a drain supply path for supplying steam drain generated by the generation of the regeneration gas to other equipment, and
A waste heat recovery system for an air separation facility, wherein the generated steam drain is recovered and used as a heat source.
[5] The waste heat recovery system for an air separation facility according to [4], wherein a mechanical pump driven by steam is disposed in the drain supply path.
[6] The waste heat of the air separation facility according to [4] or [5], wherein the other facility is a liquid vaporizing and feeding facility that heats the liquid supplied from a tank with the vapor drain. Collection system.

  According to the present invention, the waste steam discharged into the air by the equipment used in the steel manufacturing process can be efficiently recovered and its thermal energy can be used effectively, so that energy efficiency is improved.

FIG. 1 is a configuration diagram illustrating a waste heat recovery system for an air separation facility according to an embodiment of the present invention. FIG. 2 is a flowchart for explaining a waste heat recovery method for an air separation facility according to an embodiment of the present invention.

  Hereinafter, the present invention will be described in detail. Note that the present invention is not limited to this embodiment.

  First, a waste heat recovery system for an air separation facility according to the present invention will be described with reference to FIG. In FIG. 1, the block diagram of the waste heat recovery system (henceforth a waste heat recovery system) of the air separation equipment in one Embodiment of this invention is shown. Here, as an example, a case will be described in which the waste heat recovery system of the present invention is applied to an oxygen production facility that produces oxygen to be supplied to facilities such as a blast furnace and a converter in an ironworks. In FIG. 1, as the “other equipment 5”, for example, a liquid vaporizing and feeding equipment is shown. The liquid vaporization / feeding equipment is equipment for exchanging heat of stored liquid oxygen and feeding it as gaseous oxygen.

  The present invention includes an MS adsorber having an adsorption tower that removes impurities in air passing therethrough, and supplying raw air compressed by an air compressor to the adsorption tower for cleaning, and a raw material cleaned by the MS adsorber A waste heat recovery system for an air separation facility comprising: a rectifying column for rectifying and separating nitrogen and oxygen from air. In the waste heat recovery system of the present invention, the heat exchanger disposed in the discharge path for supplying a part of the nitrogen gas discharged from the air separation facility, and the regeneration gas generated by heating with the heat exchanger, By providing a regeneration gas supply path for supplying to the adsorption tower and a drain supply path for supplying steam drain generated by the generation of the regeneration gas to other equipment on the outlet side of the heat exchanger, the generated steam drain can be reduced. It is collected and used as a heat source.

  As shown in FIG. 1, the air separation facility 1 includes an air compressor 10, an MS adsorber 11, a rectification column 12, and a control device (not shown). In addition, as a waste heat recovery system for the air separation facility 1, the heat exchanger 2 and the regeneration gas supply path 3 that generate regeneration gas used for the regeneration process of the MS adsorber 11 and the generated steam drain are supplied to other facilities. A drain supply path 4 is provided.

  In the air compressor 10, the air taken in through the filter is compressed, then cooled by a cooler (not shown) such as an aftercooler, and supplied to the MS adsorber 11 as raw air.

  In the MS adsorber 11, the compressed raw material air supplied from the air compressor 10 is supplied to the adsorption tower and cleaned. In the adsorption tower, impurities such as water and hydrocarbons, carbon dioxide and the like in the raw material air passing through are adsorbed and removed by an adsorbent. The purified raw material air is cooled to the vicinity of the dew point with a heat exchanger (not shown) provided on the outlet side of the MS adsorber 11 and then supplied to the rectification column 12.

  In the example shown in FIG. 1, two adsorption towers 11a and 11b are arranged and used by alternately switching them. Specifically, while performing the above-described adsorption removal of impurities using one adsorption tower (for example, the adsorption tower 11a in FIG. 1), the other adsorption tower (for example, the adsorption tower 11b in FIG. 1) is used. Reproduce. In this regeneration process, a regeneration gas to be described later is supplied to the target adsorption tower to regenerate the used adsorbent. By using the adsorption towers 11a and 11b by alternately switching in this way, the raw material air can be continuously cleaned. Note that three or more adsorption towers may be used by switching.

  In the rectifying column 12, the washed raw air supplied from the MS adsorber 11 is further cooled (deeply cooled), and rectified and separated into nitrogen, oxygen, and argon using the difference in liquefaction temperature. Oxygen (product oxygen) and nitrogen (product nitrogen) separated in the rectification column 12 are used at the factory of the user, for example, in the case of oxygen, blast furnaces and converters, etc. Supplied to the factory.

  In the example shown in FIG. 1, the rectifying column 12 includes an upper column 12a, a lower column 12b, and a main condenser 12c.

  The raw material air cooled to the vicinity of the dew point after the above-described cleaning is introduced into the bottom of the lower tower 12b. The lower tower 12b rectifies the introduced raw material air and separates it into nitrogen gas and liquefied air rich in oxygen (hereinafter referred to as oxygen-enriched liquefied air). Nitrogen gas is stored at the top of the lower tower 12b, and oxygen-enriched liquefied air is stored at the bottom of the lower tower 12b. The nitrogen gas is condensed in the main condenser 12c to become liquefied nitrogen, and a part of the liquefied nitrogen is introduced as a reflux liquid to the upper stage of the upper tower 12a through a pipe or the like (not shown). Part of the oxygen-enriched liquefied air at the bottom of the lower tower 12b is introduced into the middle stage of the upper tower 12a through a piping tower (not shown) in a gas-liquid mixed state.

  In the upper column 12a, the liquefied nitrogen and the oxygen-enriched liquefied air that has been introduced are rectified by the lowering and rising, and oxygen and nitrogen are separated. Nitrogen gas (product nitrogen) accumulates in the upper part of the upper tower 12a, and oxygen gas (product oxygen) accumulates in the lower part of the upper tower 12a. Nitrogen gas is sent to a heat exchanger through a nitrogen extraction pipe (not shown) provided in the upper part of the upper tower 12a, and the temperature is raised to room temperature. The oxygen gas is sent to a heat exchanger through an oxygen extraction pipe (not shown) provided at the lower part of the upper tower 12a, and the temperature is raised to room temperature. The product nitrogen and product oxygen after this heat exchange are supplied to the use factories in the steelworks through the product gas feed paths.

  In addition, the purity of the nitrogen gas which accumulates in the upper tower 12a is so high that it approaches the upper part of the upper tower 12a. Therefore, in the present invention, a discharge path 13 for extracting and discharging nitrogen having lower purity than product nitrogen (waste nitrogen) is provided below the nitrogen extraction pipe of the upper tower 12a, and the extracted waste nitrogen is supplied through the discharge path 13 Thus, it is used for the regeneration process of the MS adsorber 11.

  In the heat exchanger 2, regeneration gas used for regeneration of the MS adsorber 11 is generated. The heat exchanger 2 is disposed in the discharge path 13. Part of the nitrogen gas discharged from the air separation facility 1, that is, the waste nitrogen extracted from the upper tower 12a of the rectifying column 12, is supplied to the heat exchanger 2 through the discharge path 13, and heated to generate regenerated gas. Become. The generated regeneration gas is supplied to an adsorption tower that performs a regeneration process via the regeneration gas supply path 3 to remove carbon dioxide and moisture adsorbed on the used adsorbent.

  In the example shown in FIG. 1, regeneration gas is supplied to the adsorption tower 11b through the regeneration gas supply path 3, and regeneration is performed to remove carbon dioxide and moisture adsorbed on the used adsorbent. Note that the regeneration gas supply path 3 may be alternately switched at the timing of alternately switching the adsorption towers 11a and 11b to supply and stop the regeneration gas.

  In the drain supply path 4, the steam drain generated by the generation of the regeneration gas is recovered, and the steam drain is allowed to flow through the path to be supplied to other equipment. The drain supply path 4 is provided on the outlet side of the heat exchanger 2 where the steam drain (waste steam) is discarded. In order to efficiently recover the steam drain, it is preferable to dispose a mechanical pump 4 a driven by steam in the drain supply path 4. Instead of the mechanical pump, for example, transportation using only piping can also be used.

  In the example shown in FIG. 1, the steam drain is collected by the mechanical pump 4 a and supplied to the hot water tank of the liquid vaporizing and feeding equipment 5 through the drain supply path 4. Thereby, it becomes possible to reuse the vapor drain as a heat source of the liquid vaporizing and feeding equipment 2.

  The waste heat recovery system of the present invention may be provided with a control device (not shown). The control device is constituted by a computer including, for example, a CPU and a memory, and can control each device and device. For example, the original heat source supply amount to the hot water tank may be controlled by monitoring the waste heat recovery amount.

  Next, the waste heat recovery method for the air separation facility of the present invention will be described with reference to FIG. FIG. 2 shows a flow chart of a waste heat recovery method (hereinafter referred to as a waste heat recovery method) for an air separation facility according to an embodiment of the present invention. The waste heat recovery method of the present invention can be suitably used for, for example, the waste heat recovery system having the configuration shown in FIG. Below, the case where the waste heat recovery method of this invention is applied to the waste heat recovery system of FIG. 1 is demonstrated.

  The waste heat recovery method of the present invention controls the air compressor 10, the MS adsorber 11, the rectifying column 12, the heat exchanger 2, the regeneration gas supply path 3, the drain supply path 4, and an on-off valve and equipment not shown. Executed by the processing device. In addition, since description of each apparatus etc. is the same as that of the above-mentioned, it abbreviate | omits.

  As shown in FIG. 2, first, in the MS adsorption process, after the air taken in through the filter is compressed by the air compressor 10, the compressed raw material air is supplied to the adsorption towers 11 a and 11 b of the MS adsorber 11. Clean (step s1). In the adsorption towers 11a and 11b, impurities in the passing air are removed. As described above, the two adsorption towers 11a and 11b are alternately used. In the MS adsorption step, the raw material air cleaned by the MS adsorber 11 is cooled to the vicinity of the dew point by a heat exchanger (not shown), and then supplied to the rectification column 12.

  Next, in the rectification step, after the purified raw material air supplied to the rectification column 12 is further cooled (deep cooling), nitrogen and oxygen are rectified using the difference in liquefaction temperature and separated (step) s2). In the rectification process, oxygen (product oxygen) and nitrogen (product nitrogen) separated in the rectification column 12 are sent to each product gas supply path and supplied to the factory of use.

  Next, in the heat exchange process, a part of the nitrogen gas discharged from the air separation facility 1 is extracted and supplied to the heat exchanger 2 arranged in the discharge path 13 to perform heat exchange (step s3). The extracted nitrogen gas (waste nitrogen gas) is heated by the heat exchanger 2 to generate a regeneration gas. The regeneration gas is supplied to the regeneration gas supply path 3.

  Thereafter, in the regeneration gas supply step, the supplied regeneration gas flows through the regeneration gas supply path 3 and is supplied to the adsorption tower (step s4). The adsorption tower that performs the regeneration treatment removes carbon dioxide and moisture adsorbed on the used adsorbent by the regeneration gas. In the example shown in FIG. 1, the adsorption tower 11b performs a regeneration process.

  Next, in the drain supply process, the steam drain (waste steam) generated by the generation of the regeneration gas in step s3 flows through the drain supply path 4 and is supplied to the other equipment 5 (here, liquid vaporizing and feeding equipment). (Step s5). The drain supply path 4 is provided on the outlet side of the heat exchanger 2 where the steam drain is discarded. In addition, in order to collect | recover vapor | steam drains efficiently, you may provide the above-mentioned mechanical pump 4a.

  As described above, the heat source supply amount and the like can be controlled by a control device (not shown). For example, when controlling the heat source supply amount, it may be performed after step s5.

  Each process described above is repeated while the air separation facility is in operation. By effectively recovering the steam drain generated by the operation of the air separation facility, it can be used as a heat source. That is, according to the present invention, by using waste heat energy, the amount of steam used is reduced, so that energy efficiency can be improved.

  Hereinafter, the present invention will be described based on examples. The present invention is not limited to the following examples.

  In the liquid vaporization / feeding facility 2 in the ironworks, steam is supplied to the hot water tank and heated, and the liquefied gas is vaporized through the hot water and supplied to the use factory. The steam supplied at this time is generally generated using a boiler.

  As an example of the present invention, the waste heat recovery system and method of the present invention were applied to an oxygen production factory having the above-described configuration, and operations were performed with four facilities. The heat source of the steam drain recovered from the air separation facility 1 was supplied to the hot water tank of the liquid vaporizing and feeding facility 5 via the drain supply path 4. That is, in order to heat the hot water tank, steam drain (waste steam) supplied from the air separation facility 1 was used in addition to the steam generated by the normally supplied boiler. Table 1 shows the amount of steam drain in each facility (Units A to D) used at this time.

  The temperature conditions in the operation are: the temperature of the vapor drain to be recovered is 60 to 100 ° C., the temperature of the liquefied gas supplied to the liquid vaporizing and feeding equipment 5 is about −200 ° C., the temperature in the hot water tank is 60 ° C., and the liquid The temperature of the product gas supplied from the vaporizing and feeding facility 5 to the user factory was about 10 to 25 ° C.

  On the other hand, as a conventional example, operation was performed using conventional equipment that does not have the waste heat recovery system having the above-described configuration. For the heating of the hot water tank of the liquid vaporizing and feeding equipment 5, only the steam generated by the normally supplied boiler was used. The other conditions were the same as in the example of the present invention. Table 1 shows the amount of steam drain in the conventional equipment (No. X machine) used at this time.

  From Table 1, the amount of waste steam used was zero in the case of the conventional example, whereas in the case of the present invention example, A No .: 1.3 t / h, B No .: 1.5 t / h, C No .: 1.5 t / h, D No .: 1.5 t / h. According to the present invention, the average amount of steam used in the liquid vaporizer is reduced by 0.04 t / h, so that the energy efficiency is increased by 5% compared to the conventional example. Thereby, it turned out that waste steam drain 1.0t / h or more can be used effectively. In addition, a cost reduction effect of about 8 million yen was obtained by reducing the amount of steam used.

DESCRIPTION OF SYMBOLS 1 Air separation equipment 10 Air compressor 11 MS adsorber 11a, 11b Adsorption tower 12 Rectifying tower 12a Upper tower 12b Lower tower 12c Main condenser 13 Discharge path 2 Heat exchanger 3 Regeneration gas supply path 4 Drain supply path 5 Other Facility

Claims (6)

An MS adsorption process for supplying raw material air compressed by an air compressor to an adsorption tower that removes impurities in the air passing therethrough and cleaning the adsorption tower;
A rectification step of rectifying and separating nitrogen and oxygen from the raw material air cleaned in the MS adsorption step, and a waste heat recovery method for an air separation facility,
A part of nitrogen gas discharged from the air separation facility is supplied to a heat exchanger disposed in the discharge path, and a heat exchange step of performing heat exchange;
A regeneration gas supply step of heating the nitrogen gas in the heat exchanger to generate a regeneration gas, flowing the generated regeneration gas through a regeneration gas supply path, and supplying the regeneration gas to the adsorption tower;
A drain supply step of supplying the steam drain generated by the generation of the regeneration gas to the drain supply path provided on the outlet side of the heat exchanger and supplying it to other equipment,
A method for recovering waste heat from an air separation facility, wherein the generated steam drain is recovered and used as a heat source.   The waste heat recovery method for an air separation facility according to claim 1, wherein a mechanical pump driven by steam is disposed in the drain supply path to recover the steam drain.   The waste heat recovery method for an air separation facility according to claim 1 or 2, wherein the other facility is a liquid vaporizing and feeding facility for heating a liquid supplied from a tank with the vapor drain. An MS adsorber having an adsorption tower for removing impurities in the passing air, and supplying raw air compressed by an air compressor to the adsorption tower for cleaning;
A rectifying tower for rectifying and separating nitrogen and oxygen from raw air cleaned by the MS adsorber, and a waste heat recovery system for an air separation facility comprising:
A heat exchanger disposed in a discharge path for supplying a part of the nitrogen gas discharged from the air separation facility;
A regeneration gas supply path for supplying regeneration gas generated by heating in the heat exchanger to the adsorption tower;
On the outlet side of the heat exchanger, a drain supply path for supplying steam drain generated by the generation of the regeneration gas to other equipment, and
A waste heat recovery system for an air separation facility, wherein the generated steam drain is recovered and used as a heat source. The waste heat recovery system for an air separation facility according to claim 4, wherein a mechanical pump driven by steam is disposed in the drain supply path.   The waste heat recovery system for an air separation facility according to claim 4 or 5, wherein the other facility is a liquid vaporizing and feeding facility for heating the liquid supplied from the tank with the vapor drain.

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