A preparation method of various mercaptans and thioethers with hydrogen sulfide absorption

Abstract

The present invention discloses a preparation method of various thiols (ethers) with hydrogen sulfide absorption, including a thiol (ether) preparation process and a hydrogen sulfide absorption and desorption process; the hydrogen sulfide absorption and desorption process is carried out by using a hydrogen sulfide absorption and desorption device, which includes a methanol absorption tower, a high-pressure desorption tower and a low-pressure desorption tower. In the method of the present invention, by adding a methanol absorption tower, a high-pressure desorption tower and a low-pressure desorption tower, the pressure of the high-pressure desorption tower can be effectively increased to obtain pure hydrogen sulfide at the top of the high-pressure desorption tower; at the same time, the cost is saved; in the synthesis of methyl mercaptan (ether), the raw material methanol is selected as the absorption liquid, which is easily obtained; when the recycled hydrogen sulfide is returned to the reactor, the methanol brought into the reactor will not affect the reaction; the methanol used as the absorption liquid is recycled, saving the consumption of methanol and reducing the cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of vulcanization technology, and particularly relates to a method for preparing various thiols and thioethers with hydrogen sulfide absorption. Background Art

[0002] In the device where methanol reacts with hydrogen sulfide to produce thiols (thioethers), the syngas generated by the reaction passes through a condenser. The non-condensable gas after condensation contains a large amount of hydrogen sulfide. If the non-condensable gas is directly sent back to the reactor for recycling by using a compressor, the thiols and thioethers in the gas will cause serious corrosion to the seal of the compressor after compression. Moreover, a part of thiols and thioethers still remains in the hydrogen sulfide, and these thiols and thioethers will affect the synthesis reaction, reduce the raw material conversion rate and are not conducive to production. Therefore, in the prior art, the generated hydrogen sulfide cannot be effectively recycled, and often is directly incinerated or sent to the tail gas treatment, which not only wastes costs, but also increases the difficulty of tail gas treatment. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing various thiols and thioethers with hydrogen sulfide absorption to solve the problems in the prior art.

[0004] The present invention is realized by the following technical scheme: A method for preparing various thiols and thioethers with hydrogen sulfide absorption, characterized in that: it includes the processes of preparing thiols and thioethers and absorbing and desorbing hydrogen sulfide; the hydrogen sulfide absorption and desorption process is carried out by using a hydrogen sulfide absorption and desorption device, and this device includes a methanol absorption tower, a high-pressure desorption tower and a low-pressure desorption tower; the synthesis tail gas containing hydrogen sulfide in the process of reacting methanol with hydrogen sulfide to produce thiols and thioethers enters the methanol absorption tower from the bottom, and low-temperature methanol enters from the top, and contacts the non-condensable gas reversely to absorb the hydrogen sulfide in the synthesis tail gas. The non-condensable gas that cannot be absorbed by methanol goes to the tail gas treatment system; among them, there are two streams of methanol entering the methanol absorption tower, one is fresh methanol from the tank area, and the other is recycled methanol sent by the low-pressure desorption tower; the methanol-rich liquid at the bottom of the methanol absorption tower is pressurized by a methanol-rich liquid feeding pump, preheated in a methanol desorption preheater and then enters the high-pressure desorption tower; the methanol-rich liquid enters from the middle of the high-pressure desorption tower, and the top temperature is controlled by the circulating water flow of the built-in condenser; the top gas is hydrogen sulfide, which is recycled and utilized before returning to the reactor; the mixture of methanol, thiols and thioethers at the bottom of the tower is sent to the low-pressure desorption tower by its own pressure; the material output from the high-pressure desorption tower enters from the middle of the low-pressure desorption tower, and the top temperature is controlled by the circulating water flow of the built-in condenser; the methanol lean liquid obtained at the bottom is cooled in multiple stages and then sent back to the top of the methanol absorption tower for recycling, and the thiols and thioethers at the top are cooled and then sent to the thiol purification system.

[0005] Furthermore, in the hydrogen sulfide absorption and desorption device: a fresh methanol input pipeline is provided at the bottom of the methanol absorption tower to maintain the liquid level in the tower, a low-temperature methanol input pipeline is provided at the upper part to absorb hydrogen sulfide gas, and the top of the tower is connected to a gas-liquid separation tank to recover part of the methanol; a non-condensable gas discharge pipeline is provided at the top of the gas-liquid separation tank and is equipped with a regulating valve to control the tower top pressure, and the bottom is connected to the bottom of the tower through a pipeline. The rich liquid after absorption is sent to the high-pressure desorption tower by a pump; a condenser I is provided at the upper part of the high-pressure desorption tower, and a reboiler I is provided at the lower part. The middle part of the high-pressure desorption tower is connected to the bottom of the methanol absorption tower through a methanol-rich liquid transfer pipeline, and a methanol-rich liquid feeding pump is provided on the methanol-rich liquid transfer pipeline; a hydrogen sulfide discharge pipeline is provided at the top of the high-pressure desorption tower and is equipped with a regulating valve to control the tower top pressure, and a methanol-containing mercaptan transfer pipeline is provided at the bottom and is sent to the low-pressure desorption tower by its own pressure; a condenser II is provided at the upper part of the low-pressure desorption tower, and a reboiler II is provided at the lower part; the middle part of the low-pressure desorption tower is connected to the methanol-containing mercaptan transfer pipeline; a mercaptan discharge pipeline is provided at the top of the low-pressure desorption tower and is equipped with a regulating valve to control the tower top pressure, and a methanol lean liquid transfer pipeline is provided at the bottom; the methanol lean liquid transfer pipeline is respectively connected to the methanol buffer tank feeding pipeline of the mercaptan and thioether production main device and the circulating methanol pipeline of the hydrogen sulfide absorption device. The methanol lean liquid enters the methanol absorption tower after being cooled by a cooler through the circulating methanol pipeline of the hydrogen sulfide absorption device, and enters the methanol buffer tank of the subsequent section through the methanol buffer tank feeding pipeline of the mercaptan and thioether production main device.

[0006] Furthermore, the temperature of the methanol absorption tower is -20~10°C, and the pressure is 0.1~1 MpaG; the temperature of the high-pressure desorption tower is 100~250°C, and the pressure is 1~3 MpaG; the temperature of the low-pressure desorption tower is 100~250°C, and the pressure is 0.1~1 MPaG.

[0007] Furthermore, the absorption tower and the desorption tower are one of a packed tower, a structured packing tower, and a plate tower.

[0008] The advantages of the present invention are as follows: By adding a methanol absorption tower, a high-pressure desorption tower, and a low-pressure desorption tower, the recovery of hydrogen sulfide becomes possible. The present invention has the following advantages: The pressure of the high-pressure desorption tower can be effectively increased to obtain pure hydrogen sulfide at the top of the high-pressure desorption tower; the high-pressure desorption tower solves the problem that hydrogen sulfide cannot be transported to equipment with a higher pressure; the excessive hydrogen sulfide is recovered and used as a raw material in the reactor, saving costs; in the synthesis of methyl mercaptan and thioether, methanol as a raw material is selected as the absorption liquid, which is easy to obtain; when the recovered hydrogen sulfide is returned to the reactor, bringing methanol into the reactor will not affect the reaction; the methanol used as the absorption liquid is recycled, saving the amount of methanol used and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is the overall structural schematic diagram of the present invention;

[0010] Figure 2 It is the process flow diagram of the present invention. Detailed implementation manners

[0011] As Figure 1-2 shown, the present invention discloses a preparation method of various mercaptans and thioethers with hydrogen sulfide absorption, including the steps of reacting methanol with hydrogen sulfide to generate mercaptans and thioethers, and the steps of hydrogen sulfide absorption and desorption; the hydrogen sulfide absorption and desorption steps are carried out by using a hydrogen sulfide absorption and desorption device, which includes a methanol absorption tower, a high-pressure desorption tower and a low-pressure desorption tower; the synthesis tail gas containing hydrogen sulfide in the step of reacting methanol with hydrogen sulfide to generate mercaptans and thioethers enters the methanol absorption tower from the bottom, and low-temperature methanol enters from the top, and contacts the non-condensable gas reversely to absorb hydrogen sulfide in the mercaptan synthesis tail gas. The absorption purpose is achieved by controlling the flow rate of low-temperature methanol. A high flow rate results in a large absorption amount; the non-condensable gas that cannot be absorbed by methanol goes to the tail gas treatment system; the methanol component entering the methanol absorption tower is divided into two parts, one part is fresh methanol from the tank area, and the other part is recycled methanol sent from the low-pressure desorption tower; the methanol-rich liquid at the bottom of the methanol absorption tower is pressurized by a methanol-rich liquid feeding pump, preheated in a methanol desorption preheater and then enters the high-pressure desorption tower; the methanol-rich liquid is fed into the middle of the high-pressure desorption tower, and the top temperature is controlled by the circulating water flow rate of the built-in condenser; the top pressure is controlled by interlocking the gas-phase pipe regulating valve with the top pressure gauge, and the hydrogen sulfide in the top gas is recycled and utilized before returning to the reactor; the steam pipeline regulating valve at the bottom reboiler is interlocked with the bottom thermometer to control the bottom temperature, and the methanol, mercaptan and thioether mixture at the bottom is sent to the low-pressure desorption tower by its own pressure; the material from the high-pressure desorption tower is fed into the middle of the low-pressure desorption tower, and the top temperature is controlled by the circulating water flow rate of the built-in condenser; the steam pipeline regulating valve at the bottom reboiler is interlocked with the bottom thermometer to control the bottom temperature, and the methanol lean liquid with higher purity is obtained at the bottom, and after being cooled in multiple stages, it is sent back to the top of the methanol absorption tower for recycling, and the mercaptan and thioether at the top are sent to the mercaptan purification system for further purification treatment.

[0012] Preferably, in the hydrogen sulfide absorption and desorption device, it includes a methanol absorption tower 1, a high-pressure desorption tower 2, and a low-pressure desorption tower 3; a fresh methanol input pipeline 11 is provided at the bottom (bottom of the tower kettle) of the methanol absorption tower 1, a low-temperature methanol input pipeline 12 is provided at the upper part, and the top is connected to a gas-liquid separation tank 14; a non-condensable gas discharge pipeline 13 is provided at the top of the gas-liquid separation tank, and a regulating valve is provided to control the tower top pressure, and the bottom is connected to the bottom of the tower through a pipeline; a condenser I 21 is provided at the upper part of the high-pressure desorption tower 2, and a reboiler I 22 is connected through a circulation pipeline on the outer side of the lower part. The middle part of the high-pressure desorption tower is connected to the bottom of the methanol absorption tower through a methanol-rich liquid transfer pipeline 23, and a methanol-rich liquid feeding pump 24 is provided on the methanol-rich liquid transfer pipeline; a hydrogen sulfide discharge pipeline 25 is provided at the top of the high-pressure desorption tower, and a regulating valve is provided to control the tower top pressure, and a mercaptan-containing methanol transfer pipeline 26 is provided at the bottom; a heat exchanger 4 is provided between the mercaptan-containing methanol transfer pipeline 26 and the methanol-rich liquid transfer pipeline 23 for heat exchange; a condenser II 31 is provided at the upper part of the low-pressure desorption tower 3, and a reboiler II 32 is connected through a circulation pipeline on the outer side of the lower part; the middle part of the low-pressure desorption tower is connected to the mercaptan-containing methanol transfer pipeline 26; a mercaptan discharge pipeline 33 is provided at the top of the low-pressure desorption tower, and a regulating valve is provided to control the tower top pressure, and a methanol lean liquid transfer pipeline 34 is provided at the bottom; the methanol lean liquid transfer pipeline is respectively connected to the raw material methanol pipeline 35 and the circulating methanol pipeline 36 through a tee, and the circulating methanol pipeline 36 is connected to the low-temperature methanol input pipeline through a cooler 15 (which can be regarded as a pipeline with a cooler in the middle).

[0013] Preferably, in the hydrogen sulfide absorption and desorption device: a fresh methanol input pipeline is provided at the bottom of the methanol absorption tower to maintain the liquid level in the tower, a low-temperature methanol input pipeline is provided at the upper part to absorb hydrogen sulfide gas, and the top of the tower is connected to a gas-liquid separation tank to recover part of the methanol; a non-condensable gas discharge pipeline is provided at the top of the gas-liquid separation tank and is equipped with a regulating valve to control the tower top pressure, the bottom is connected to the bottom of the tower through a pipeline, and the absorbed rich liquid is sent to the high-pressure desorption tower by a pump; a condenser I is provided at the upper part of the high-pressure desorption tower, a reboiler I is provided at the lower part, the middle of the high-pressure desorption tower is connected to the bottom of the methanol absorption tower through a methanol rich liquid transfer pipeline, and a methanol rich liquid feeding pump is provided on the methanol rich liquid transfer pipeline; a hydrogen sulfide discharge pipeline is provided at the top of the high-pressure desorption tower and is equipped with a regulating valve to control the tower top pressure, and a thiol-containing methanol transfer pipeline is provided at the bottom and is sent to the low-pressure desorption tower by its own pressure; a condenser II is provided at the upper part of the low-pressure desorption tower, a reboiler II is provided at the lower part; the middle of the low-pressure desorption tower is connected to the thiol-containing methanol transfer pipeline; a thiol discharge pipeline is provided at the top of the low-pressure desorption tower and is equipped with a regulating valve to control the tower top pressure, and a methanol lean liquid transfer pipeline is provided at the bottom; the methanol lean liquid transfer pipeline is respectively connected to the methanol buffer tank feeding pipeline of the main device for producing thiol and thioether and the circulating methanol pipeline of the hydrogen sulfide absorption device. The methanol lean liquid enters the methanol absorption tower after being cooled by a cooler through the circulating methanol pipeline of the hydrogen sulfide absorption device, and enters the methanol buffer tank of the subsequent process section through the methanol buffer tank feeding pipeline of the main device for producing thiol and thioether.

[0014] Preferably, the temperature of the methanol absorption tower is -20~10°C, the pressure is 0.1~1 MpaG, and a chilled water heat exchanger is installed inside the tower bottom to ensure the tower bottom temperature and improve the absorption effect;

[0015] The temperature of the high-pressure desorption tower is 100~250°C, the pressure is 1~3 MpaG, and a condenser is installed inside the tower top to control the reflux ratio by adjusting the heat loads at the tower top and bottom, saving costs;

[0016] The temperature of the low-pressure desorption tower is 100~250°C, the pressure is 0.1~1 MPaG, and a condenser is installed inside the tower top to control the reflux ratio by adjusting the heat loads at the tower top and bottom, saving costs.

[0017] Preferably, the absorption tower and the desorption tower include, but are not limited to, random packing, structured packing, and plate towers.

[0018] In the present invention, the definition of methanol is only for the convenience of description. For example, fresh methanol refers to the methanol input from the outside; methanol rich liquid and methanol lean liquid are distinguished according to the methanol content; low-temperature methanol refers to methanol with a relatively low temperature; raw material methanol is the methanol that can be used as a raw material after being discharged from the system; circulating methanol refers to the methanol recycled within the system. Example

[0019] This device is used in the device of a certain company for the reaction of methanol and hydrogen sulfide to produce mercaptan (thioether).

[0020] In the original device for the reaction of methanol and hydrogen sulfide to produce mercaptan (thioether), the syngas generated by the reaction passes through a condenser. The non-condensable gas after condensation contains a large amount of hydrogen sulfide. Previously, the non-condensable gas was directly sent back to the front of the reactor for recycling by using a compressor. The mercaptan and thioether in the gas will cause serious corrosion to the seals of the compressor after compression, seriously affecting the service life of the equipment. And there is still a part of mercaptan and thioether in the hydrogen sulfide. These mercaptan and thioether will affect the synthesis reaction, reduce the raw material conversion rate, which is not conducive to production, and the generated hydrogen sulfide cannot be effectively recycled. It is often directly incinerated or sent to the tail gas treatment, which not only wastes costs but also increases the difficulty of tail gas treatment.

[0021] After the transformation using this solution, the device adds a high-pressure stripping tower to replace the original hydrogen sulfide compressor, solving the problem of serious corrosion of the compressor seals. The low-pressure stripping tower further separates methanol and mercaptan to obtain purer hydrogen sulfide, solving the problem that the return of mercaptan and thioether to the original reactor reduces the raw material conversion rate and is not conducive to production. In the synthesis of methyl mercaptan and thioether, the raw material methanol is selected as the absorbent, which is easy to obtain and does not affect the reaction when returning to the reactor with hydrogen sulfide. The methanol used as the absorbent can be recycled, saving the amount of methanol used and reducing costs.

[0022] In this embodiment, the parameters of the main production device are as follows:

[0023] Scale of the device: Processing acidic gas 900 - 1200 kg / h; Operating time: Continuous production for 7200 hours / year; Operating flexibility range: Acidic gas 900 - 1200 kg / h.

[0024] In this embodiment: The composition of the acidic gas is H2S: 65 - 70%, H20: 0.2 - 0.3%, CH3OH: 2 - 3%, CH3SH: 8 - 10%, CH3SCH3: 0.3 - 0.5%, others (CH4 / CO / CO2 / N2 / H2): 14 - 17%; Feed flow rate 900 - 1200 kg / h; Feed temperature 0 - 5°C; Feed pressure 0.25 - 0.28 MPa. Fresh methanol feed rate 1000 - 1900 kg / h; Feed temperature ≤30°C; Feed pressure 0.5 - 0.55 MPa.

Claims

1. A preparation method of various mercaptans and thioethers with hydrogen sulfide absorption, characterized in that: Including the preparation of mercaptans and thioethers and the absorption and analysis process of hydrogen sulfide; The hydrogen sulfide absorption and analysis process is carried out using a hydrogen sulfide absorption and analysis device, which includes a methanol absorption tower, a high-pressure analysis tower and a low-pressure analysis tower; The synthesis tail gas containing hydrogen sulfide in the process of methanol and hydrogen sulfide reacting to form mercaptan and thioether enters the methanol absorption tower from the bottom of the tower, and low-temperature methanol enters from the top of the tower, and contacts with the non-condensable gas in reverse to absorb the hydrogen sulfide in the synthesis tail gas. The non-condensable gas that cannot be absorbed by methanol goes to the tail gas treatment system; There are two streams of methanol entering the methanol absorption tower, one is fresh methanol from the tank area, and the other is recycled methanol from the low-pressure desorption tower; the methanol-rich liquid at the bottom of the methanol absorption tower is pressurized by the methanol-rich liquid feeding pump and sent to the methanol desorption preheater for preheating before entering the high-pressure desorption tower; The methanol-rich liquid is fed from the middle of the high-pressure desorption tower, and the top temperature is controlled by the circulating water flow of the built-in condenser; the hydrogen sulfide in the top gas is recycled before returning to the reactor; the methanol, mercaptan, and sulfide mixture at the bottom of the tower is sent to the low-pressure desorption tower by its own pressure; The material output from the high-pressure analysis tower is fed into the middle of the low-pressure analysis tower, and the top temperature of the tower is controlled by the circulating water flow of the built-in condenser; the methanol-lean liquid obtained at the bottom of the tower is sent back to the top of the methanol absorption tower for recycling after multi-stage cooling, and the mercaptan sulfide at the top of the tower is sent to the mercaptan purification system after cooling.

2. The preparation method of various mercaptans and thioethers with hydrogen sulfide absorption according to claim 1, characterized in that: In the hydrogen sulfide absorption and analysis device: The bottom of the methanol absorption tower is provided with a fresh methanol input pipeline to maintain the liquid level in the tower, and the upper part is provided with a low-temperature methanol input pipeline to absorb hydrogen sulfide gas. The top of the tower is connected to the gas-liquid separation tank to recover part of the methanol; the top of the gas-liquid separation tank is provided with a non-condensable gas discharge pipeline and a regulating valve to control the pressure at the top of the tower, and the bottom is connected to the bottom of the tower through a pipeline, and the rich liquid after absorption is pumped into the high-pressure analysis tower; The upper part of the high-pressure analysis tower is provided with a condenser I, and the lower part is provided with a reboiler I. The middle part of the high-pressure analysis tower is connected with the bottom of the methanol absorption tower through a methanol rich liquid delivery pipeline, and a methanol rich liquid feeding pump is provided on the methanol rich liquid delivery pipeline; the top of the high-pressure analysis tower is provided with a hydrogen sulfide discharge pipeline and a regulating valve to control the tower top pressure, and the bottom is provided with a mercaptan-containing methanol delivery pipeline to be delivered to the low-pressure analysis tower by its own pressure; A condenser II is arranged at the upper part of the low-pressure analysis tower, and a reboiler II is arranged at the lower part; the middle part of the low-pressure analysis tower is connected with a mercaptan-containing methanol conveying pipeline; a mercaptan discharge pipeline is arranged at the top of the low-pressure analysis tower and a regulating valve is provided to control the tower top pressure, and a methanol lean liquid conveying pipeline is arranged at the bottom; the methanol lean liquid conveying pipeline is respectively connected with the methanol buffer tank feed pipeline of the mercaptan and thioether production main unit and the circulating methanol pipeline of the hydrogen sulfide absorption unit, and the methanol lean liquid enters the methanol absorption tower after being cooled by a cooler through the circulating methanol pipeline of the hydrogen sulfide absorption unit, and enters the methanol buffer tank of the subsequent section through the methanol buffer tank feed pipeline of the mercaptan and thioether production main unit.

3. A method for preparing various thiols and thioethers with hydrogen sulfide absorption according to claim 1, characterized in that: The methanol absorption tower has a temperature of -20~10°C and a pressure of 0.1~1MpaG; the high-pressure desorption tower has a temperature of 100~250°C and a pressure of 1~3MpaG; The temperature of the low-pressure analysis tower is 100~250℃ and the pressure is 0.1~1MPaG.

4. A method for preparing various thiols and thioethers with hydrogen sulfide absorption according to claim 1, characterized in that: The absorption tower and the stripping tower are one of the bulk packing, structured packing and plate column.

Images