JPH017701Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a carbon monoxide (hereinafter sometimes referred to as CO) recovery device, and in particular improves the stripping tower installed in the process of desorbing CO from the absorption liquid after absorbing CO. It is related to.

In the chemical industry, CO and H ₂ have recently attracted attention as chemical raw materials, and methods for separating and concentrating them have been of great interest. Furthermore, controlling the stoichiometric ratio of CO and H ₂ to a constant value, that is, controlling the concentration, also has important significance.

Conventionally, in the CO separation and concentration process using the absorption method, the method for desorbing CO from the liquid that has absorbed CO is to increase the temperature or reduce the pressure of the absorption liquid in a stripping tower, and then remove the solvent, etc. that makes up the absorption liquid. The operation is carried out to evaporate the CO and dissipate the absorbed CO along with the solvent vapor.

As the above-mentioned CO absorption liquid, for example,
21708, a solution of cuprous chloride in tris(dimethylamino)phosphine oxide (hereinafter referred to as
(sometimes called HMPA liquid) is superior, but
The boiling point of this liquid at normal pressure is 235°C, which is relatively high. For this reason, in order to obtain vapor from HMPA liquid in a stripping tower, high-pressure steam that provides a temperature above the boiling point of HMPA (235°C) is required, which requires a large amount of thermal energy and reduces CO recovery efficiency. It has drawbacks such as not necessarily being expensive. Furthermore, when the CO recovered in this way is reacted with H ₂ to synthesize, for example, methanol or acetic acid, the CO
There are also disadvantages such as the need for a mixing device for H 2 and H ₂ .

An object of the present invention is to be able to separate CO with high efficiency and with a small amount of heat required even when the boiling point of the absorption liquid is high or its latent heat of vaporization is large.
Our goal is to provide CO recovery equipment.

In order to achieve the above object, this invention includes an absorption tower for absorbing CO through contact with an absorption liquid;
A CO recovery apparatus equipped with a stripping tower for desorbing CO from an absorption liquid after absorbing CO, characterized in that the stripping tower is provided with a supply system for a gas for promoting CO desorption.

In this invention, conventionally known CO absorption liquids are widely applicable, but the above-mentioned cuprous chloride HMPA liquid is particularly preferred.

The gas for promoting CO desorption (hereinafter sometimes referred to as desorption medium) is not particularly limited as long as it is a gas or a mixture thereof that normally exhibits a gas phase and does not dissolve or react with the absorption liquid. However, H ₂ or chlorine (hereinafter sometimes referred to as Ll ₂ ) gas, which can react with CO to produce useful substances in the mixed state after CO recovery, is preferable.

This invention will be explained in more detail below with reference to embodiments shown in the drawings.

The apparatus shown in FIG. 1 consists of a conventional part mainly consisting of an absorption tower 2 and a stripping tower 3 connected by an absorption liquid circulation system, and a desorption medium supply system characteristically provided in the stripping tower 3. has been done. The desorption medium supply system includes a desorption medium storage tank 5, a desorption medium supply pipe 61 communicating with the desorption medium storage tank 5, and a control valve 7 provided in the middle of the pipe 61.
and a desorption medium spouting nozzle 10 provided at the lower part of the stripping tower 3 for supplying the desorption medium sent through the pipe 61 into the stripping tower 3. In addition, 6 is discharged from the upper part of the stripping tower 3.
This is a detector for measuring the concentration of various components in the CO desorbed gas, and the signals obtained are sent through line 101, thereby operating the control valve 7.

In the apparatus configured as described above, the raw material gas containing CO sent through the line 11 is pretreated in the pretreatment device 1 as necessary, and then
The CO2 enters the lower part of the absorption tower 2 through the CO
is selectively absorbed. The exhaust gas after CO absorption is appropriately removed from entrained components and then released into the atmosphere through the exhaust gas line 21 at the top of the absorption tower. On the other hand, the liquid that has absorbed CO is transferred from the absorption liquid line 31 at the bottom of the absorption tower to the heat exchanger 4 by the operation of the pump 8A.
It is sent to the top of the desorption column 3, where it is heated. The absorption liquid flowing down in the desorption tower 3 comes into contact with H ₂ gas, which is a desorption medium, introduced into the desorption tower from the desorption medium tank 5 through a pipe 61 at an elevated temperature of approximately 120°C. This reduces the CO gas concentration around the absorption liquid, accelerates the rate of CO desorption, and almost completely separates the CO in the absorption liquid. CO and
The gas containing H ₂ and absorbent solvent vapor is transferred to the desorption column 3.
After passing through the upper gas line 41, it is led to the cooling tower 9, where the solvent vapor is recovered. The recovered solvent passes through line 71 and is refluxed to the bottom of the desorption column. The absorption liquid from which CO has been separated is transferred from the line 51 at the bottom of the desorption tower 3 to the heat exchanger 4 by the operation of the pump 8B.
It is sent to the upper part of the absorption tower 2 to be cooled, and then returned to the upper part of the absorption tower 2 for circulation. The gas discharged from the upper part of the desorption column 3 contains CO and H ₂ , and the concentration of these is monitored by the detector 6 , and based on this signal, the control valve 7 is operated to maintain a predetermined H ₂ concentration. Be manipulated. It is desirable that the above concentration be suitable for a raw material gas for chemical synthesis. That is, for example, for methanol synthesis, it is preferable that the molar ratio of CO and H ₂ is 1:2.

The above examples use _H2 as the desorption medium,
Although the case of obtaining a raw material gas for synthesis of methanol or acetic acid has been described, it goes without saying that the same process can be carried out using other desorption media, such as Cl ₂ .

In this case, by setting the ratio of CO and Cl ₂ to 1:1, a synthesis gas raw material suitable for phosgene synthesis represented by the following formula (1) can be suitably obtained.

CO + Cl ₂ → COCl ₂ ...(1) The above examples all show normal pressure treatment, but it is clear that the CO diffusion rate can be understood as a function of pressure as shown in equation (2) below. It goes without saying that the rate of desorption can be increased by increasing the amount of desorption medium injected.

CO emission rate ∝k・P _T・Lco ...(2) (In the formula, k is the rate constant, P _T is the operating pressure, and Lco is the CO concentration in the liquid.) As described above, according to this invention, the stripping tower By installing a desorption medium supply system in the
It has become possible to efficiently desorb the absorbent even at a low temperature below the boiling point of the absorbent, thereby reducing the amount of heat required.

Furthermore, by appropriately selecting the type of desorption medium and controlling the amount of injection, it is possible to directly produce raw material gas for chemical synthesis, and economic efficiency can be improved by omitting processes. It became.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a CO recovery device showing an embodiment of this invention. 3...Diffusion tower, 5...Desorption medium storage tank, 6
... Concentration detector, 7 ... Control valve, 10 ... Desorption medium spout nozzle, 61 ... Desorption medium supply piping.

Claims (1)

[Claims for Utility Model Registration] (1) An absorption tower for absorbing carbon monoxide through contact with an absorption liquid, and a stripping tower for desorbing carbon monoxide from the absorption liquid after absorbing carbon monoxide. A carbon monoxide recovery device comprising: a carbon monoxide recovery device, characterized in that the stripping tower is provided with a supply system for a gas for promoting carbon monoxide desorption. (2) A carbon monoxide recovery device according to claim 1 of the utility model registration, characterized in that the gas for promoting carbon monoxide desorption is hydrogen gas. (3) The carbon monoxide recovery device according to claim 1 of the utility model registration, characterized in that the gas for promoting carbon monoxide desorption is chlorine gas.