Methanol process gas recycling system

Abstract

The utility model relates to the technical field of methanol process gas recovery, in particular to a methanol process gas recycling system, which comprises a water scrubber, a double-pipe heater, a membrane separator and a synthetic tower which are sequentially connected, the double-pipe heater is further connected with a heat supply pipe, a steam regulating valve is arranged on the heat supply pipe, and the membrane separator is connected with the steam regulating valve. The sleeve type heater is connected with the membrane separator through a hot air pipe, the hot air pipe is provided with a temperature transmitter which is in communication connection with the steam regulating valve, and the temperature transmitter is close to the membrane separator; in order to solve the problem that the process gas temperature is too high or too low due to unstable steam in the moisture evaporation process of existing process gas, a temperature transmitter on a hot gas pipe is in communication connection with a steam adjusting valve on a heat supply pipe, the steam flow is adjusted according to the real-time temperature of the process gas, the heating stability and reliability of the process gas are improved, and the energy consumption is reduced. The service life of equipment is ensured, and stable and reliable process gas recovery requirements are met.

Description

Technical Field

[0001] The utility model relates to the technical field of methanol process gas recovery, and particularly relates to a methanol process gas recovery and utilization system. Background Technique

[0002] The process gas in the methanol synthesis system is mainly composed of CO, CO2, H2, CH4, and N2. Among them, the effective gases CO, CO2, and H2 will be re-introduced into the synthesis tower through the syngas compressor to participate in the methanol synthesis reaction. However, during the circulation process, the gases such as CH4 and N2 that do not participate in the methanol synthesis reaction in the process gas are increasing, which affects the methanol synthesis reaction.

[0003] In the actual production process, a membrane separator is usually used to filter out the gases such as CH4 and N2 that do not participate in the reaction in the process gas and then transport them to the synthesis tower to ensure the stable synthesis of methanol. For example, the Chinese invention patent application with the application number CN202110667598.X provides a methanol synthesis hydrogen recovery system, and the gas membrane separator is connected to a shell-and-tube heat exchanger to separate the gasified process gas.

[0004] However, by separating the process gas in this way, it is necessary to use a heater to heat the process gas to evaporate the liquid in the process gas. However, when setting a constant temperature, the heating of the process gas will be unstable when the process gas is unstable. When the temperature of the process gas is too high, the polymer membrane structure in the membrane separator will become loose or even torn and damaged, reducing the filtering effect, and at the same time increasing the equipment maintenance cost; while when the temperature is too low, the liquid in the process gas will not be evaporated sufficiently, resulting in blockage of the polymer membrane, which will also reduce the filtering effect and increase the maintenance cost.

[0005] Therefore, the existing methanol process gas recovery system cannot meet the stable and reliable recovery requirements. Content of the Utility Model

[0006] The purpose of the utility model is to provide a methanol process gas recovery and utilization system to solve the technical problem of unstable recovery of methanol process gas at present.

[0007] To achieve the above purpose, the utility model provides the following technical solutions:

[0008] A methanol process gas recovery and utilization system, characterized in that it includes a water washing tower, a shell-and-tube heater, a membrane separator, and a synthesis tower connected in sequence. The shell-and-tube heater is also connected to a heating pipe, and a steam regulating valve is arranged on the heating pipe. The shell-and-tube heater is connected to the membrane separator through a hot gas pipe, and a temperature transmitter communicatively connected to the steam regulating valve is arranged on the hot gas pipe, and the temperature transmitter is close to the membrane separator.

[0009] Further defined, the methanol process gas recovery and utilization system further includes a gas-liquid separator, and the gas-liquid separator is connected between the water washing tower and the shell-and-tube heater.

[0010] Further defined, the membrane separator is provided with a first air inlet, a first air outlet and a second air outlet. The first air inlet is communicated with the hot gas pipe, the first air outlet is communicated with the synthesis tower, the second air outlet is connected with a flare gas branch pipe, and a flare gas regulating valve is arranged on the flare gas branch pipe.

[0011] Further defined, a flow transmitter is further arranged on the hot gas pipe. The flow transmitter is communicatively connected with the flare gas regulating valve, and the flow transmitter is located between the shell-and-tube heater and the temperature transmitter.

[0012] Further defined, a vent pipe is further arranged on the hot gas pipe. A vent valve and a pressure transmitter are arranged on the vent pipe. The pressure transmitter is located between the vent valve and the hot gas pipe, and the vent pipe is located between the flow transmitter and the shell-and-tube heater; the pressure transmitter is communicatively connected with the vent valve.

[0013] Further defined, a permeate gas compressor is arranged between the synthesis tower and the membrane separator, and the first air outlet is connected with the synthesis tower through the permeate gas compressor.

[0014] Further defined, a synthesis gas compressor is arranged between the synthesis tower and the permeate gas compressor, and the permeate gas compressor is connected with the synthesis tower through the synthesis gas compressor.

[0015] Further defined, a sampling port is arranged on the membrane separator, and the sampling port is communicated with the first air outlet.

[0016] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0017] 1. In order to solve the problem that the process gas temperature is too high or too low due to unstable steam during the evaporation of moisture in the existing process gas, the temperature transmitter on the hot gas pipe is communicatively connected with the steam regulating valve on the heating pipe, so as to realize the adjustment of the steam flow rate according to the real-time temperature of the process gas, improve the stability and reliability of the process gas heating, ensure the service life of the equipment, and meet the stable and reliable process gas recovery requirements.

[0018] 2. The present utility model also arranges a gas-liquid separator to reduce the moisture content in the process gas, thereby increasing the evaporation efficiency by reducing the difficulty of moisture evaporation, reducing the blockage of the membrane separator, and further improving the reliable recovery of the methanol process gas.

[0019] 3. The present utility model realizes the recovery and utilization of process gas by arranging a permeate gas compressor and a syngas compressor between the synthesis tower and the membrane separator, which are used to pressurize and input the filtered permeate gas into the synthesis tower for methanol synthesis; at the same time, the non-permeate gas is recovered and utilized through the flare gas branch pipe to meet the recovery requirements of the process gas.

[0020] 4. The present utility model is provided with a flow transmitter on the heating pipe and communicatively connected to the flare gas regulating valve, which is used to increase the output flow of the non-permeate gas when the supply flow of the process gas is too large, ensure the separation quality of the process gas in the membrane separator, avoid the untimely separation of the process gas and input it into the synthesis tower, and further ensure the stable and reliable recovery of the process gas. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the methanol process gas recovery and utilization system of the present utility model;

[0022] In the figure: 1 - water washing tower; 2 - shell-and-tube heater; 3 - membrane separator; 4 - heating pipe; 5 - hot gas pipe; 6 - gas-liquid separator; 7 - permeate gas compressor; 8 - syngas compressor; 9 - synthesis tower; a - steam regulating valve; b - temperature transmitter; c - flare gas branch pipe; d - flare gas regulating valve; e - flow transmitter; f - pressure transmitter; g - sampling port. Detailed Embodiments

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present utility model clearer, the present utility model will be further described in detail below with reference to the drawings and embodiments. The specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model. Specific details such as specific system structures and technologies are proposed to more thoroughly understand the embodiments of the present utility model. The described embodiments are some embodiments of the present disclosure, but not all of the embodiments. However, those skilled in the art should understand that the present utility model can also be implemented in other embodiments without these specific details. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present disclosure.

[0024] Embodiment 1

[0025] Reference Figure 1, this embodiment provides a methanol process gas recovery and utilization system, which includes a water washing tower 1, a shell-and-tube heater 2, a membrane separator 3, and a synthesis tower 9 connected in sequence. Among them, the process gas filters out the methanol therein through the water washing tower 1 and then is input to the shell-and-tube heater 2. The shell-and-tube heater 2 heats the process gas after filtering out methanol to evaporate the internal moisture to obtain heated process gas. Then, the heated process gas is passed through the membrane separator 3 to obtain permeate gas containing CO, CO2, and H2 and non-permeate gas containing CH4 and N2. The permeate gas is transported to the synthesis tower 9 to continue participating in methanol synthesis, realizing the recovery and utilization of the process gas.

[0026] Specifically, in order to avoid that when the process gas flow rate is unstable, providing constant steam to the shell-and-tube heater 2 to maintain a constant temperature will increase the temperature of the process gas when the process gas flow rate is low and decrease the temperature of the process gas when the process gas flow rate is high, resulting in unstable heating of the process gas, damaging the membrane separator 3, making the recovery of methanol process gas unstable and unreliable, and reducing the working efficiency.

[0027] Therefore, a steam control valve a is selected to be set on the heat supply pipe 4 for supplying steam to the shell-and-tube heater 2, and a temperature transmitter b is set on the hot gas pipe 5 between the shell-and-tube heater 2 and the membrane separator 3. By setting the target temperature range and communicatively connecting the temperature transmitter b with the steam control valve a, the opening of the steam control valve a is reduced when the process gas temperature is on the high side, and the opening of the steam control valve a is increased when the process gas temperature is on the low side, ensuring stable and reliable heating of the process gas and meeting the actual recovery requirements.

[0028] Furthermore, in order to reduce the moisture content in the process gas, a gas-liquid separator 6 is selected to be set between the shell-and-tube heater 2 and the water washing tower 1 for filtering out the moisture in the process gas, improving the working efficiency of the shell-and-tube heater 2, improving the reliability of moisture evaporation in the process gas, and further improving the recovery reliability of the methanol process gas.

[0029] Furthermore, the membrane separator 3 is provided with a first air inlet, a first air outlet, and a second air outlet. Among them, the first air inlet is connected to the hot gas pipe 5 for inputting the heated process gas into the membrane separator 3 for separation. After the process gas enters the membrane separator 3, it permeates from the shell side to the membrane core side, and permeate gas is obtained on the membrane core side, and the non-permeate gas that does not permeate into the membrane core side is the non-permeate gas.

[0030] In order to ensure the quality of the permeate gas, a sampling port g is selected to be set on the permeate gas pipe communicated with the first air outlet for sampling to detect the components of the permeate gas.

[0031] The permeate gas is transported from the first outlet to the synthesis tower 9 through the permeate gas pipe, and the non-permeate gas is output through the second outlet.

[0032] In order to utilize the non-permeating gas to avoid waste and environmental pollution, a flare gas branch pipe c is selected to be connected to the second outlet for transporting the non-permeating gas to the flare for combustion; a flare gas regulating valve d is provided on the flare gas branch pipe c for regulating the flow rate of the non-permeating gas.

[0033] Furthermore, in order to prevent the membrane separator 3 from being unable to separate the process gas in time when the flow rate of the process gas is too large, resulting in the permeating gas transported to the synthesis tower 9 being doped with non-permeating gas, a flow transmitter e is selected to be provided on the hot gas pipe 5. The flow transmitter e is communicatively connected to the flare gas regulating valve d and is used to increase the opening degree of the flare gas regulating valve d when the flow rate of the process gas increases, so as to increase the output flow rate of the non-permeating gas, ensure the separation efficiency and quality of the membrane separator 3, and further improve the stability and reliability of the methanol process gas recovery.

[0034] Meanwhile, a vent pipe is also provided on the hot gas pipe 5. A pressure transmitter f and a vent valve are provided on the vent pipe. The pressure transmitter f is communicatively connected to the vent valve and is used to open the vent valve when the pressure in the hot gas pipe 5 is too high to ensure operation safety.

[0035] Furthermore, in order to prevent the permeating gas from being unable to be smoothly input into the synthesis tower 9 due to insufficient pressure, a permeating gas compressor 7 is preferably provided between the synthesis tower 9 and the membrane separator 3. The permeating gas compressor 7 is communicated with the first outlet.

[0036] Preferably, a syngas compressor 8 is provided between the synthesis tower 9 and the permeating gas compressor 7 to ensure the pressure boost of the permeating gas and ensure reliable recovery.

[0037] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0039] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A methanol process gas recovery and utilization system, characterized in that: The invention comprises a water washing tower (1), a sleeve-type heater (2), a membrane separator (3) and a synthesis tower (9) which are connected in sequence, the sleeve-type heater (2) is also connected to a heating pipe (4), a steam regulating valve (a) is arranged on the heating pipe (4), the sleeve-type heater (2) is connected to the membrane separator (3) through a hot air pipe (5), a temperature transmitter (b) which is in communication connection with the steam regulating valve (a) is arranged on the hot air pipe (5), and the temperature transmitter (b) is close to the membrane separator (3).

2. The methanol process gas recovery and utilization system according to claim 1, characterized in that: The methanol process gas recovery and utilization system further comprises a gas-liquid separator (6), and the gas-liquid separator (6) is connected between the water washing tower (1) and the sleeve-type heater (2).

3. The methanol process gas recovery and utilization system according to claim 2, characterized in that: The membrane separator (3) is provided with a first air inlet, a first air outlet and a second air outlet, the first air inlet is connected to the hot air pipe (5), the first air outlet is connected to the synthesis tower (9), the second air outlet is connected to the flare gas branch pipe (c), and the flare gas branch pipe (c) is provided with a flare gas regulating valve (d).

4. The methanol process gas recovery and utilization system according to claim 3, characterized in that: The hot gas pipe (5) is also provided with a flow transmitter (e), which is communicatively connected with the flare gas regulating valve (d), and is located between the sleeve-type heater (2) and the temperature transmitter (b).

5. The methanol process gas recovery and utilization system according to claim 4, characterized in that: The hot gas pipe (5) is also provided with a vent pipe, and the vent pipe is provided with a vent valve and a pressure transmitter (f). The pressure transmitter (f) is located between the vent valve and the hot gas pipe (5), and the vent pipe is located between the flow transmitter (e) and the sleeve heater (2); the pressure transmitter (f) is communicatively connected with the vent valve.

6. The methanol process gas recovery and utilization system according to claim 5, characterized in that: A permeate gas compressor (7) is provided between the synthesis tower (9) and the membrane separator (3), and the first gas outlet is connected to the synthesis tower (9) through the permeate gas compressor (7).

7. The methanol process gas recovery and utilization system according to claim 6, characterized in that: A synthesis gas compressor (8) is arranged between the synthesis tower (9) and the permeate gas compressor (7), and the permeate gas compressor (7) is connected to the synthesis tower (9) via the synthesis gas compressor (8).

8. The methanol process gas recovery and utilization system according to claim 7, characterized in that: The membrane separator (3) is provided with a sampling port (g), and the sampling port (g) is communicated with the first gas outlet.

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