JPS6272510A - Device for separating and concentrating carbon monoxide - Google Patents

Abstract

PURPOSE:To efficiently separate and concentrate CO for a long period by combining an adsorption tower and a desorption tower respectively used for absorbing and desorbing CO with an liq. absorbent line and an adsorption unit for removing H3PO4 and obtaining the specified function. CONSTITUTION:A liq. absorbent contg. CuCl, tris(dimethylamino)phosphine oxide (hmpa) and toluene is brought into countercurrent contact with raw gas in the absorption tower 1 and the CO in the raw gas is adsorbed. The liq. absorbent after absorbing CO is sent to a heat exchange 3 from a rich liq. line 2 and heated therein to a temp. close to the temp. at which CO is desorbed. The liq. absorbent heated in the heat exchanger 3 is introduced into a stripper 4 and then passed through a condenser 14 and the product is obtained. The liq. absorbent from a control valve 8 is introduced into the adsorption unit 9A, wherein weakly acidic H3PO4 in the liq. absorbent generated by the hydrolysis of the hmpa reacts with NaOH constituting the bed of the adsorption unit 9A, and the H3PO4 in the liq. absorbent is removed as Na3PO4.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a carbon monoxide (hereinafter referred to as CO) separation and concentration device, and particularly relates to a carbon monoxide (hereinafter referred to as CO) separation and concentration device, and in particular, to a device for separating and concentrating carbon monoxide (hereinafter referred to as CO), and in particular, to a device for separating and concentrating carbon monoxide (hereinafter referred to as CO), and in particular for cuprous chloride (hereinafter referred to as CuC1), tris(dimethylamino)phosphine. The present invention relates to a CO separation/concentration device suitable for stabilizing the absorption liquid when circulating the absorption liquid in a process using an absorption liquid containing oxides.

[Background of the invention]

A conventional CO separation/store system using an absorption liquid containing CuC1, tris(dimethylamino)phosphine oxide (hereinafter referred to as hmpa), and toluene as a solvent is shown in FIG. In FIG. 2, a raw material gas containing CO comes into countercurrent contact with an absorption liquid in an absorption tower I, and CO in the raw material gas is selectively absorbed. The absorption liquid that has absorbed CO is sent from the rich liquid line 2 to the heat exchanger 3, where it is heated to a temperature close to the temperature at which CO can be dissipated from the absorption liquid. The absorption liquid heated by the heat exchanger 3 is transferred to a desorption column (stripper) 4
where it dissipates CO. The bottom liquid of the stripper 4 is heated by the repoiler 5, and the toluene vapor generated at this time acts as a CO stripping agent.
Helps dissipate CO.

The absorption/desorption mechanism of the above-mentioned absorption liquid is
hmp a +CO,1 CuCn ・ hmp a -co-・・-(tl
It is indicated by.

Therefore, in order to obtain stable CO absorption performance, operating conditions that match the above-mentioned reaction of equation +11 are required.

When the absorption liquid is recycled under high temperature and acidic conditions, hmp a becomes 2(2)((CH3)2N)3P.
O+3HzO→3 (C)is)zN H+ H:lP
Os... Hydrolyzes as shown in (2) to produce dimethylamine and H3P Oa.

The dimethylamine produced in this reaction has C, uC7! as a monodentate ligand, as shown in 2(3). and ammine complexes, reducing CO absorption performance.

CuCff-hmpa+ (CH*)zNIl-CuC
12. (CHz)zNll+hmp a-・----
(3) On the other hand, Hs P Oa reacts with CuC/-hmpa as shown in equation (4) to produce poorly soluble cuprous phosphate, which increases the concentration of the CuC1'·hmpa complex that has CO absorption ability. decrease.

CuC1・hmpa+H3PO4→ Cu C1' HzP Oa ↓+h m pa
+ H' = - (41 Furthermore, although dimethylamine itself exhibits strong basicity, it becomes neutral due to the ammine complex produced by the reaction with CuCe. Moreover, H, PO, and H' as shown in formula (4) As a whole, h
As the hydrolysis of mpa progresses, the pH decreases and h
Accelerates hydrolysis of mpa.

Therefore, if the pH of the absorption liquid is in an acidic state of 5 or less, the stripper 4, the reboiler 5, the line connecting the stripper 4 and the reboiler 5, etc.
decomposition progresses. Dimethylamine and 11°PO produced by the hydrolysis of hmpa reduce the CO absorption performance as described above, and further lower the pH of the absorption liquid, so they accelerate the hydrolysis of hmpa on the downstream side of the stripper 4. let For this reason, CO
In separation/concentration equipment, it has been difficult to stabilize the absorption liquid and efficiently separate and concentrate CO over a long period of time.

[Purpose of the invention]

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to
In a CO separation and 4-condensation device that circulates and uses an absorption liquid containing uC1 and tris(dimethylamino)phosphine oxide, the CO absorption performance of the absorption liquid is stabilized and CO can be efficiently separated and 4-condensed over a long period of time. Our objective is to provide a CO separation/concentration device.

[Summary of the Invention] In short, the present invention provides CuCl! and tris(dimethylamino)phosphine oxide.
O absorption performance decreases over time due to hmpa in the absorption liquid.
Focusing on the fact that 83PO4 is generated during the hydrolysis of CO and that this H3PO4 is easily generated in high-temperature atmospheres such as strippers, the absorption liquid is Hs P inside
This is to remove Oa by adsorption and stabilize the absorption liquid.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 2 is a system configuration diagram showing an embodiment of the present invention. This CO separation/concentration apparatus is equipped with an absorption tower 1, a stripper 4, and a reboiler 5. A heat exchanger 3 is installed in the middle of a rich liquid line from the absorption tower 1, and this rich liquid line 2 is connected to a stripper 4. Connected to the top of 4. A line is provided for introducing the bottom liquid into the reboiler 5 from the lower side of the column of the stripper 4, and this line is again connected to the lower side of the column of the stripper 4.

The heat exchanger 3 is installed in the lean liquid line 6 from the bottom of the stripper 4, and the absorption liquid cooler 7 is installed downstream of the lean liquid from the heat exchanger 3. is connected to the top of the absorption tower 1 via a heat exchanger 3 and an absorption liquid cooler 7.

The lean liquid line 6 includes a bypass line 8 branched near the stripper 4, and adsorption units 9A and 9B are installed in parallel to the bypass line 8. A head made of a solid basic compound such as NaOH is formed in each of the adsorption units 9A and 9B. Further, a control valve 10 is installed upstream of the bypass line 8 from the adsorption units 9A and 9B, and a pH detector 12 is installed downstream of the lean liquid line 6 from the confluence 11 of the lean liquid line 6 and the bypass line 8. is set up.

A condenser 14 is installed in the middle of the gas line 13 from the top of the stripper 4, and a drain separator 16 is installed in the middle of the drain line 15 from the condenser 14, and the toluene recovered by the drain separator 16 is transferred to the downstream side of the stripper 4. There is a line for introduction.

Next, the operation of the CO separation/concentration device configured as described above will be explained.

The absorption liquid containing CuC1, tris(dimethylamino)phosphine oxide, and toluene comes into countercurrent contact with the raw material gas in the absorption tower 1, and absorbs C0 in the raw material gas. The absorption liquid that has absorbed CO is sent from the rich liquid line 2 to the heat exchanger 3, where it is heated to a temperature close to the point at which CO is released. 4 will be introduced.

Here, when the atmosphere in the stripper 4, the repoiler 5, and the line connecting them is acidic and under high temperature conditions, 83PO4 is generated according to the above equation (2). This Hs
The absorption liquid containing P 2 Oa flows from the bottom of the stripper 4 through the lean liquid line 6, the control valve 8, and the bypass line 8 to the adsorption unit. The adsorption unit has two towers, and the upstream and downstream valves of one adsorption unit 9A are open, and the upstream and downstream valves of the other adsorption unit 9B are closed. . The absorption liquid from the control valve 8 is introduced into the adsorption unit 9A,
Here, weakly acidic H3P0. reacts with NaO+ (which forms the bed of the adsorption unit 9A) as shown in formula (5)%, and H3P04 in the absorption liquid becomes Na3
It is removed as Po.

The absorption liquid that has passed through the adsorption unit) 9A is introduced into the lean liquid line 6 again through the confluence point 11.
During the process, the pH value of the absorption liquid is continuously detected by the pH detector 12. If there are many stars of H3PO4 produced by the decomposition of hmp a in the absorbing liquid, the pH value of the absorbing liquid will decrease, and the CO absorption performance of the absorbing liquid will decrease. p of absorption liquid
Since the stabilization region as an H value is about 5 to 6, the pH value of the absorption liquid in this stabilization region is set as the set value, and the deviation value between this set value and the pif detection value of the absorption liquid by the pH detector 12. The opening degree of the control valve 10 is adjusted based on. In this way, H and P, which are factors that reduce the CO absorption performance of the absorbent due to the decomposition of hmpa in the absorbent,
After O, is adsorbed and removed by the adsorption unit 9A, the absorption liquid passes through the heat exchanger 3 and the absorption liquid cooler 7 and is introduced into the absorption tower 1 in a state where the CO absorption performance is increased. Note that the adsorption unit 9A has a function as a filter for adsorbing and removing precipitates in the absorption liquid in addition to adsorption and removal of HtPO4 from the absorption liquid.

When the adsorption and removal functions of I(ff P 04 and precipitate in the absorption liquid by the adsorption unit 9A deteriorate, the valves on the upstream and downstream sides of the adsorption unit 9A are closed, respectively, and the adsorption unit The valves on the upstream side and the downstream side of 9B are opened, respectively, and the absorption liquid from the stripper 4 is introduced into the adsorption unit 9B.In this way, the adsorption unit 9
The absorption liquid from the stripper 4 is alternately introduced into A and 9B, so that H and pOa can be adsorbed and removed, and precipitates in the absorption liquid can be adsorbed and removed continuously.

In the present invention, the adsorption units may be installed in parallel in three or more stages, and if the heat of neutralization reaction of H 3 P Oa is large, this heat of neutralization reaction can be recovered by the absorption liquid introduced into the stripper 4. I can do it.

The bed formed in the adsorption unit is limited to NaOH, as long as it is a solid basic compound that forms a reaction product that is not dissolved in the absorption liquid by reaction with H, PO, etc.

Further, the absorption liquid used in the apparatus of the present invention is an absorption liquid containing cuprous chloride and hmpa, but an aromatic hydrocarbon is used as a solvent, and as an aromatic hydrocarbon, a substance specified by the law, especially CO gas, is used as a solvent. Toluene is effective because it has low movement resistance, that is, it reduces the viscosity of the absorbing liquid.

〔Effect of the invention〕

As described above, according to the present invention, the absorption liquid can be recycled and used by efficiently removing 113Po, which is generated by the hydrolysis of hmpa in the absorption liquid and causes a decrease in the CO absorption performance of the absorption liquid. In this case, the performance of the absorption liquid can be stabilized over a long period of time, and CO can be efficiently separated and concentrated.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram showing an embodiment of the CO separation/concentration device according to the present invention, and Fig. 2 is a conventional CO separation/concentration device.
It is a system configuration diagram showing the t position. 1...Absorption tower, 2...Rich liquid line, 3...Heat exchanger, 4...
...Stripper, 5...Reboiler, 6.
...Lean liquid line, 7...Absorption liquid cooler, 8...Bypass line, 9A, 9B...
... Suction S: Y-nit, 10... Control valve, 12... pH detector, 14...
...Capacitor, 16...Drain separator.

Claims (5)

[Claims] (1) an absorption tower that brings a carbon monoxide absorption liquid containing cuprous chloride and tris(dimethylamino)phosphine oxide into contact with a gas containing carbon monoxide, and absorbs carbon monoxide into the absorption liquid; A desorption tower that heats the absorption liquid from this absorption tower to diffuse carbon monoxide, and an absorption liquid line that supplies the absorption liquid from which carbon monoxide has been liberated from this desorption tower to the absorption tower. The carbon monoxide separation/concentration device is characterized in that an adsorption unit for adsorbing and removing H_3PO_4 produced by hydrolysis of tris(dimethylamino)phosphine oxide in the absorption liquid is installed in the middle of the absorption liquid line. Separation/concentration equipment. (2) The carbon monoxide separation/concentration device according to claim 1, wherein the adsorption unit has a bed of a solid basic compound formed therein. (3) The carbon monoxide separation/concentration apparatus according to claim 1, wherein the adsorption unit is provided in the absorption liquid line near the bottom of the desorption column. (4) The unit is installed in a bypass line branched from the absorption liquid line, and a pH detector for detecting the pH of the absorption liquid is provided downstream of the absorption liquid line from the absorption unit, and a pH detector is provided on the upstream side of the absorption unit. 2. The carbon monoxide separation/concentration device according to claim 1, wherein the bypass line is provided with a control valve that operates based on a signal from the pH detector. (5) The monoxide according to any one of claims 1 to 4, wherein the adsorption unit is installed in two columns in parallel in the bypass line, and the inflow of the absorption liquid to each column can be switched. Carbon separation and concentration equipment.