JPS62114627A - Apparatus for absorbing and separating gas - Google Patents

Abstract

PURPOSE:To obtain high gas selectivity, by a method wherein specific gas is absorbed through the gas-liquid contact with an absorbing liquid and the amount of the absorbing liquid is increased in an absorbing tower to remove stock gas and pressure reducing operation is performed in the absorbing tower to separate the specific gas. CONSTITUTION:Stock gas is sent to an absorbing/desorbing tower 1 to absorb and separate CO in the stock gas and the treated gas is taken out from an exhaust gas line 4. Thereafter, a new absorbing liquid is supplied to the absorbing/desorbing tower 1 from an absorbing liquid tank 11 and the stock gas stagnated in the space above the absorbing liquid in the tower 1 is discarded through the exhaust gas line 4. Simultaneously with this operation, a valve 5 is closed and a part of the absorbing liquid in the absorbing/desorbing tower 1 is returned to the absorbing liquid tank 11 using a pump 14 to return the level of the absorbing liquid in the absorbing/desorbing tower 1 to the initial state. Subsequently, the valve 5 is opened and, at the same time, the absorbing/ desorbing tower 1 is evacuated by a pressure reducing pump 6. By this method, CO separated from the absorbing liquid is stored in a storage tank 8 through a product gas line 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a gas absorption and separation device, and particularly relates to a gas absorption separation device that uses an absorbing liquid to perform 1. It relates to a device that absorbs a certain amount of gas and separates and recovers a specific gas from the absorbed liquid.

[Background of the invention]

Various technologies have been implemented to absorb and layer 11□S, CO2, CO, etc. from various processes, but most of them employ a system in which the absorbing liquid is circulated between an absorption tower and a desorption tower. are doing. In addition, the main methods for desorbing a specific gas from an absorption liquid that has absorbed a specific gas are a method in which the absorbed gas is extracted by heating the absorption liquid, and a method in which the absorbed gas is extracted from the absorption liquid by reducing the pressure. ing.

Furthermore, in recent years, the PSA method (Pressure swing Ab) using a solid adsorbent has been developed as a small gas absorption separation device.
There is a device that employs s-orpLion).

The above-mentioned apparatus will be explained using a CO absorption liquid separation process as an example. Figure 4 shows an absorption tower system using a CO absorption liquid. The raw material gases containing CO include blast furnace gas, converter gas, FCC regeneration tower outlet gas, process gas, etc., which are byproduct gases of steel mills, and these gases contain 20% to 70% CO.
Contains CO. This CO gas is separated and concentrated and used as a chemical raw material and fuel. The absorption liquid contains CuCf.
MgC/z/water system, CuCj! - hmpa/mlumi/toluene, where hmpa is tris(dimethylamino)phosphine oxyto), AI C13/toluene, etc. have been proposed.

In FIG. 4, the raw material gas containing CO is supplied to the raw material supply pipe 3.
1 and sent to the absorption tower 32. The absorption tower 32 is formed of a packed tower, a perforated plate tower, etc., and is a system in which the absorption liquid and the raw material gas containing CO are in countercurrent contact. CO in the raw material gas is absorbed into the absorption liquid through countercurrent contact with the absorption liquid.

The raw material gas from which CO has been separated is discharged from the exhaust gas line 33 to the outside of the system. The absorption tower 32 is operated at room temperature and at 1 to 5 atm. The absorbing liquid that has absorbed CO is heat exchanged! ! !
It is heated by the heater 34, and then the heater 35 is heated by the heater 35.
The temperature is raised to about ~+20'C. In this state, the absorption liquid is sent to the desorption column 36, where CO in the absorption liquid is separated. The separated Co is recovered via a product CO line 37.

The desorption tower 36 consists of a packed tower and a perforated plate tower, and the CO
The separated absorption liquid passes through a heat exchanger 34 and is cooled, then passes through a cooler 38 and is cooled to 30 to 50°C, and is returned to the absorption tower 32 again. The desorption tower 36 is provided with a steam heater 39 at the bottom of the tower to keep the entire inside of the tower at a high temperature to efficiently desorb CO.

FIG. 5 shows a PSA type gas absorption and separation device.

In FIG. 5, an absorption-desorption column 41 is filled with particles such as molecular sieve. The raw material gas containing co is sent to the absorption desorption tower 41 through the raw material supply pipe 42. In the absorption-desorption column 41, CO in the raw material gas is selectively absorbed, and the raw material gas from which CO has been separated is discharged from the system through an exhaust gas line 43. When the particles have sufficiently absorbed CO in the gas absorption desorption column 41, the valve 44 is closed, the valve 45 is simultaneously opened, and the pressure is reduced by the pressure reduction pump 46, thereby separating the CO adsorbed on the particles. In this system, product C015
Since the concentration is low, the raw material gas containing CO is further supplied to the second stage absorption/desorption tower 47, the valve 48 is opened in the same way as the first stage absorption/desorption tower 41, and the exhaust gas is discharged from the exhaust gas line 49. In addition, CO is separated and the product c'o is stored in a storage tank 52 via a valve 50 and a pressure reducing pump 51. Usually, a 5- to IO-stage absorption/desorption tower is installed to recover product CO.

The gas absorption separation device using the above-mentioned absorption liquid requires equipment of at least two towers, one for absorbing CO and the other for desorbing CO. Moreover, since CO is recovered by thermal desorption, a large amount of steam is required to heat the absorption liquid itself in addition to the heat required to separate CO, and at least heat exchange R''A l group, heating In addition, in the heat exchanger 34, the temperature of the absorption liquid coming out of the absorption tower 32 is 30 to 40°C, while the temperature of the absorption liquid coming out of the desorption tower 36 is Since the temperature difference is small at 80 to 120°C, a wide heat transfer surface is required to increase the efficiency of heat exchange.Furthermore, since the absorption liquid circulates between the absorption tower 32 and the desorption tower 3G, Two pumps are required.As described above, in the conventional CO absorption and separation apparatus that uses an absorption liquid, the equipment becomes large due to the complicated structure of equipment including the above-mentioned heat exchanger. Furthermore, highly corrosive liquid is often used as the absorbing liquid, and therefore, it is necessary to use inexpensive materials such as 'Fl-based materials for equipment that comes into contact with the absorbing liquid.

On the other hand, in the gas absorption M device using the PSA method, since the selectivity of the adsorbent itself to CO is low, there is the problem of absorbing Co, , and N2 in the raw material gas at the same time as CO, and because a packed bed of particles is used, there is a problem between particles. There is a problem in that it is not possible to purge the raw material gas that remains in the space (approximately 70%). Therefore, for COt adsorption in particles,
Separation and removal of COx is performed at the front stage of the CO absorption and separation device. Also, the adsorption of N in particles and the spaces between particles? Currently, the purging of the gas in the a-distillate is handled by repeating the gas absorption and vacuum desorption operation 5 to 10 times, increasing the CO concentration in the product CO gas to over 90%. [Object of the Invention] An object of the present invention is to solve the problems of the prior art described above,
An object of the present invention is to provide a gas absorption and separation device capable of absorbing and separating a specific gas contained in raw F4 gas with simple equipment and high gas selectivity.

[Summary of the invention]

In short, the present invention increases the amount of absorption liquid in the absorption tower before separating the specific gas absorbed by the absorption tower by decompression operation,
The absorption tower absorbs the specific gas and desorbs the specific gas by substantially eliminating the space in the absorption tower where the raw material gas stays, and by reducing the pressure inside the absorption tower and separating the specific gas from CO. It is designed to function as an absorption-desorption tower.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail based on the drawings. FIG. 1 is a schematic diagram showing an embodiment of a gas absorption and separation device according to the present invention. This gas absorption and separation apparatus is mainly composed of two absorption and desorption towers 1, a storage tank 8, and an absorption liquid tank 11. A raw material gas supply pipe 2 is provided near the bottom of the absorption-desorption column 1, and an exhaust gas line 4 with a valve 3 interposed therein is provided at the top of the absorption-desorption column 1. Further, the top of the absorption-desorption column 1 is connected to a storage tank 8 via a product gas line 7 in which a valve 5 and a pressure reducing pump 6 are installed. This storage tank 8 is connected to a recycle gas discharger 10 disposed near the base of the absorption-desorption tower 1 via a recycle line 9 in which a pump is provided. The base of the absorption-desorption column 1 and the absorption liquid pump 11 are connected by an absorption liquid supply line 13 in which a pump 12 is installed, and this absorption liquid supply line 13 is connected to a bypass line 15 in which a pump 14 is installed. is provided.

In the gas absorption separation apparatus having such a configuration, the raw material gas is sent from the raw material gas supply pipe 2 to the absorption desorption column 1 . The exhaust gas from which CO has been absorbed and separated is taken out from the exhaust gas line 4. Thereafter, the pump 12 is operated to supply new absorption liquid from the absorption liquid tank 11 into the absorption-desorption tower I, and the raw material gas staying in the space above the absorption liquid in the absorption-desorption tower I is disposed of through the exhaust gas line 4. . At the same time as this operation, the valve 5 is closed, and a part of the absorption liquid in the absorption-desorption tower 1 is returned to the absorption liquid tank 11 using the pump 14, so that the liquid level of the absorption liquid in the absorption-desorption tower 1 is brought to the initial state. Return to

Next, the valve 5 is opened, and at the same time, the pressure inside the absorption/desorption tower I is reduced by the pressure reducing pump 6 to 0.5 to 0.05 at from normal pressure.
Maintain m. The CO separated from the absorption liquid by this pressure reduction operation is stored in a storage tank 8 via a product gas line 7. In addition, a part of the product gas (CO) in the storage tank 8 passes through a recycling line 9 to a tacycle gas discharger 10.
As a result, the CO released into the absorbent agitates the absorbent and increases the monthly rate of CO from the absorbent.

After CO has been sufficiently separated from the absorption liquid, valve 5 is closed again and the absorption/desorption column is opened! Raw material gas is introduced into the chamber. Such operations can be carried out in some absorption-desorption columns. Therefore, there is no need for complicated heat exchangers and accessory equipment such as heaters.

Furthermore, by raising and lowering the liquid level of the absorption liquid in the absorption-desorption column 1, the raw material gas in the column can be almost completely separated, so that CO of high 4 degrees Celsius can be obtained.

Furthermore, a highly corrosive liquid is generally used as the CO absorption liquid, but in the apparatus shown in Figure 1, the only parts that come into contact with the absorption liquid are the absorption desorption column 1, the absorption liquid tank 11, and the line connecting these devices. Yes, and has a simple structure. Therefore, it is possible to reduce the number of parts using materials such as resin coating and Ti in consideration of corrosion resistance.

FIG. 2 is a schematic diagram showing another embodiment of the gas absorption and separation apparatus according to the present invention.

In FIG. 2, the bottom of the absorption-desorption column 1 and an absorption liquid tank 21 are connected by an absorption liquid supply inlet 22. The top of the absorption liquid tank 21 is a hydraulic tank 23 and a hydraulic pump 2.
It is connected to an oil tank 25 via 4. The space of the hydraulic tank 23 is filled with an inert gas such as N2 or argon. In FIG. 2, the components other than those described above are substantially the same as those shown in FIG. 1, so they are designated by the same reference numerals and detailed explanations will be omitted.

With such a configuration, the gas absorption amount A [at position a,
The raw material gas is sent from the raw material gas supply pipe 2 to the absorption-desorption tower 1. The exhaust gas from which CO has been separated is taken out from the exhaust gas line 4. Thereafter, the hydraulic pump 24 is operated to supply oil in the oil tank 25 to the hydraulic tank 23. Hydraulic tank 2
3, the inert gas such as N2 argon sealed in the space of the hydraulic tank 23 is pressurized, and this pressure causes the absorption liquid in the absorption liquid tank 21 to be absorbed through the absorption liquid supply line 22. is introduced into the desorption column 1.

By this operation, raw gas remaining on the absorption liquid in the absorption-desorption tower 1 is disposed of through the exhaust gas line 4.

At the same time as this operation, the valve 5 is closed, the hydraulic pump 24 is operated, the oil in the hydraulic tank 23 is returned to the oil tank 25, the pressure due to the inert gas in the absorption liquid tank 21 is reduced, and the pressure in the absorption-desorption column 1 is reduced. Return the absorption liquid level to the initial)υ[ state.

Next, as in the case of FIG. 1, the valve 5 is opened, and at the same time the pressure inside the absorption-desorption column 1 is reduced by the pressure reducing pump 6, from normal pressure to 0.
5 to 0.05 atm, and while separating CO from the absorption liquid, part of the product gas (CO) is released into the absorption liquid outside the J cycle gas release emitter. Repeat these operations.

In the embodiment shown in FIG. 2, like the device in FIG.
The O absorption and desorption operation can be performed in one part, and complicated heat exchangers and heater tower accessories are not required. Furthermore, since the absorption liquid in the absorption/desorption tower 1 is raised and lowered by the pressure of the inert gas sealed in the hydraulic tank 23, pumps, valves, etc. that come into direct contact with the absorption liquid can be omitted.

In the embodiments shown in FIGS. 1 and 2, CO is absorbed and separated in a batch manner, but in order to continuously take out the produced gas, the absorption membrane i! It is also possible to install the III tower in multiple stages.

FIG. 3 is a graph showing the relationship between raw material gas pressure and CO absorption in various absorption liquids. From Figure 3, CuC1-MBCAz/HCI is used as the absorption liquid! System, Cu CI!
-hmpa/l-luene system, CuC7! /I
It can be seen that CO can be separated from the absorption liquid by reducing the pressure in both cases of the cρ3/toluene system. Therefore, the absorption liquid exemplified above can be applied to the gas absorption separation device according to the present invention. Note that the present invention can be applied as long as a specific gas can be absorbed into an absorption liquid from the gas to be treated and the specific gas can be separated by reducing the pressure.

〔Effect of the invention〕

As described above, according to the present invention, a specific gas can be separated from a raw material gas by raising and lowering the level of the absorption liquid in the absorption-desorption tower. For this reason, a highly concentrated specific gas can be obtained in one step, and the specific gas can be absorbed and separated using only the column.

Further, there is no need for accessory equipment such as a heat exchanger or a heater tower, and it is possible to omit or reduce equipment such as a pump and a valve tower that come into contact with the corrosive crystalline absorption liquid.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the gas absorption separation device according to the present invention, FIG. 2 is a schematic configuration diagram showing another embodiment of the gas absorption separation device according to the present invention, and FIG. 3 1 is a graph showing the relationship between raw material gas pressure and CO absorption amount in various types of absorption liquids, and FIGS. 4 and 5 are schematic configuration diagrams showing conventional gas absorption and separation apparatuses using absorption liquids. ■・・・Absorption-desorption tower, 6・・・Reducing pump, 7・・・Product gas line, 8・・・Storage tank, 9・・・・・・Recycling line 11.21...Absorption? Leather tank, 23・
...Hydraulic tank, 24...Hydraulic pump 2
5...Oil tank.

Claims (2)

[Claims] (1) In a gas absorption/separation device that causes a specific gas in the source gas to be absorbed by the absorption liquid through gas-liquid contact between the source gas and the absorption liquid, and separates the specific gas from the absorption liquid using a pressure difference, the source gas is introduced. , an absorption tower that absorbs a specific gas in the raw material gas through gas-liquid contact with the absorption liquid staying in the tower, and an absorption tower in which the amount of absorption liquid in this absorption tower is made larger than the amount of absorption liquid during the absorption operation of the specific gas. It is characterized by comprising means for removing the raw material gas remaining in a space within the absorption tower, and means for reducing the pressure in the absorption tower after removing the raw material gas and separating a specific gas from the absorption liquid. Gas absorption absorption separation equipment. (2) A patent characterized in that the means for removing the raw material gas is configured to pressurize the absorption liquid stored in the absorption liquid tank connected to the absorption tower using an inert gas whose pressure is adjusted by hydraulic pressure. A gas absorption and separation device according to claim (1).