Non-condensable gas treatment device of crude methanol pre-rectifying tower

Abstract

The utility model discloses a non-condensable gas treatment device for a crude methanol pre-rectifying tower. The non-condensable gas treatment device consists of a pre-rectifying tower, a primary water cooler, a secondary water cooler, a reflux tank, a reflux pump, a separator, a water scrubber, a dilute methanol pump and a sulfur recovery device incinerator, a gas outlet in the top of the pre-rectifying tower is connected with a gas inlet in the top of the first-stage water cooler, and a gas outlet in the top of the first-stage water cooler is connected with a gas inlet in the top of the second-stage water cooler; an air outlet in the top of the secondary water cooler is connected with an air inlet in the middle of the separator; a top gas outlet of the separator is connected with the water scrubber through a bottom non-condensable gas inlet pipe of the water scrubber; the top of the water washing tower is connected with a pressure regulating valve through a water washing tower non-condensable gas outlet pipe; an outlet of the pressure regulating valve is connected with a non-condensable gas blow-down pipe and a non-condensable gas recovery pipe, the non-condensable gas blow-down pipe is emptied at a high point, and the non-condensable gas recovery pipe is connected with an H2S-containing acid gas inlet pipe of an incinerator of the sulfur recovery device. Through the device, the non-condensable gas of the crude methanol pre-rectifying tower is conveyed to the incinerator of the sulfur recovery device for treatment, so that the practicability is high, the equipment investment and the operation cost of a compressor are saved, the environmental pollution is reduced, the energy consumption is reduced, and the production cost is saved.

Description

Technical Field

[0001] This utility model relates to the field of crude methanol pre-distillation, and in particular to a non-condensable gas treatment device for a crude methanol pre-distillation tower. Background Technology

[0002] In methanol production plants, the crude methanol produced in the methanol synthesis process contains not only water but also dozens of trace organic impurities such as aldehydes, ketones, ethers, acid esters, alkanes, amines, and iron carbonyl. It must be distilled to obtain qualified refined methanol. During the distillation of crude methanol, dissolved gases such as H2, CO, CO2, N2, and CH4, as well as low-boiling-point impurities such as dimethyl ether and methyl formate, are first removed in a pre-distillation column. Then, it enters a pressurized distillation column and an atmospheric distillation column to remove water and high-boiling-point impurities, yielding qualified refined methanol. The gas discharged after pre-distillation, containing substances such as H2, CO, CO2, N2, CH4, dimethyl ether, methyl formate, and methanol, is called "non-condensable gas" and has the following characteristics: 1) low pressure, approximately 30 kPa; 2) contains toxic and harmful substances such as H2, CO, CH4, dimethyl ether, and methyl formate, as well as flammable substances; 3) contains methanol.

[0003] In existing technologies, the main methods for treating non-condensable gas in crude methanol pre-distillation towers are as follows: The first method is to directly discharge the non-condensable gas into the atmosphere or through a flare, which has the disadvantages of environmental pollution and lack of recovery of methanol and combustibles. The second method is to first wash the non-condensable gas with water to recover methanol, and then pressurize it before sending it to the fuel gas pipeline for use as fuel. Although this method recovers methanol and combustibles, it increases equipment investment and power consumption during operation. The third method involves first washing the non-condensable gas with water to recover methanol, and then sending it to a coal-fired boiler to recover combustibles. However, since the inlet pressure of the boiler's secondary air vent is negative, the non-condensable gas is easily introduced into the coal-fired boiler. This method eliminates the need for a dedicated compressor to pressurize the non-condensable gas, saving on equipment investment and power consumption during operation. However, this method is only suitable for plants with coal-fired boilers that are close to the methanol distillation unit. If the coal-fired boiler is far from the methanol distillation unit, a compressor is still required to pressurize the non-condensable gas before it can be sent to the coal-fired boiler for processing, which increases equipment investment and power consumption during operation. Summary of the Invention

[0004] The purpose of this invention is to provide a non-condensable gas treatment device for a crude methanol pre-distillation tower, which is suitable for use in coal-to-methanol plants that do not have coal-fired boilers or have coal-fired boilers but are far from the methanol distillation process. Without installing a non-condensable gas compressor, it can recover and treat the pollutants and combustibles contained in the non-condensable gas after methanol recovery, thereby reducing environmental pollution, reducing energy consumption, and saving production costs.

[0005] To address the aforementioned problems, this utility model provides a non-condensable gas treatment device for a crude methanol pre-distillation tower, comprising a pre-distillation tower, a primary water cooler, a secondary water cooler, a reflux tank, a reflux pump, a separator, a water washing tower, a dilute methanol pump, and a sulfur recovery unit incinerator. The top outlet of the pre-distillation tower is connected to the top inlet of the primary water cooler, the top outlet of the primary water cooler is connected to the top inlet of the secondary water cooler, and the bottom outlet of the primary water cooler is connected to the top of the reflux tank. The top outlet of the secondary water cooler is connected to the middle inlet of the separator, and the bottom outlet of the secondary water cooler is connected to the top of the reflux tank. The bottom outlet of the separator is connected to the top of the reflux tank. The top outlet of the device is connected to the water washing tower via the non-condensable gas inlet pipe at the bottom of the water washing tower; the bottom outlet of the reflux tank is connected to the top of the pre-distillation tower via a reflux pump; the top of the water washing tower is connected to a pressure regulating valve via the non-condensable gas outlet pipe of the water washing tower, and the top of the water washing tower is connected to a demineralized water pipe; the bottom outlet of the water washing tower is connected to the crude methanol feed pipe of the pre-distillation tower via a dilute methanol pump; the outlet of the pressure regulating valve is connected to a non-condensable gas vent pipe and a non-condensable gas recovery pipe, the non-condensable gas vent pipe vents to a high point, and the non-condensable gas recovery pipe is connected to the H2S-containing acid gas inlet pipe of the sulfur recovery unit incinerator; the non-condensable gas vent pipe is equipped with a non-condensable gas vent valve, and the non-condensable gas recovery pipe is equipped with a non-condensable gas recovery valve and a check valve.

[0006] Furthermore, a pressure transmitter is installed at the top of the pre-distillation column. The pressure transmitter is signal-connected to a pressure controller, which is electrically connected to a pressure regulating valve. This is used to control the pressure of the pre-distillation column.

[0007] Furthermore, both the non-condensable gas vent valve and the non-condensable gas recovery valve are remote on / off valves equipped with solenoid valves, used to achieve rapid on / off switching of the non-condensable gas vent valve and the non-condensable gas recovery valve.

[0008] Furthermore, the sulfur recovery unit incinerator is equipped with a flame detector, which is signal-connected to the interlock controller. The interlock controller is electrically connected to the non-condensable gas vent valve and the non-condensable gas recovery valve.

[0009] This invention delivers the non-condensable gas from the crude methanol pre-distillation tower, after cooling, temperature reduction, and water washing to the incinerator of the sulfur recovery unit in a coal-to-methanol plant, which is used to treat H2S-containing acidic gases in the low-temperature methanol washing process, for high-temperature incineration. This method has the following advantages: the sulfur recovery unit is an essential environmental protection device for coal-to-methanol plants; sending the non-condensable gas from the crude methanol pre-distillation tower to the incinerator of the sulfur recovery unit for treatment is highly practical; the pressure of the incinerator in the sulfur recovery unit is 5-10 kPa, and the non-condensable gas has a pressure of approximately 30 kPa. The gas can be fed into the incinerator for processing without the need for an additional compressor, saving on equipment investment and compressor operating costs. VOCs components such as dimethyl ether, methyl formate, and methanol contained in the non-condensable gas are incinerated at high temperatures in the incinerator, reducing environmental pollution. Combustible substances such as H2, CO, CH4, dimethyl ether, methyl formate, and methanol contained in the non-condensable gas are recovered and used as fuel in the incinerator, reducing fuel gas consumption, energy consumption, and production costs. The incinerator is equipped with a flameout protection device, ensuring high safety. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the non-condensable gas treatment unit of the crude methanol pre-distillation tower.

[0011] Figure label:

[0012] 1: Pre-distillation column; 2: Primary water cooler; 3: Secondary water cooler; 4: Reflux tank; 5: Reflux pump; 6: Separator; 7: Water washing tower; 8: Dilute methanol pump; 9: Sulfur recovery unit incinerator; 10: Non-condensable gas inlet pipe of water washing tower; 11: Non-condensable gas outlet pipe of water washing tower; 12: Non-condensable gas vent pipe; 13: Non-condensable gas recovery pipe; 14: Pressure regulating valve; 15: Non-condensable gas vent valve; 16: Non-condensable gas recovery valve; 17: Check valve; 18: Pressure transmitter; 19: Pressure controller; 20: Flame detector; 21: Interlock controller; 22: Non-condensable gas activation / deactivation button. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this utility model. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of this utility model.

[0014] like Figure 1The diagram shows a non-condensable gas treatment device for a crude methanol pre-distillation column, comprising a pre-distillation column 1, a primary water cooler 2, a secondary water cooler 3, a reflux tank 4, a reflux pump 5, a separator 6, a water washing tower 7, a dilute methanol pump 8, and a sulfur recovery unit incinerator 9. The top outlet of the pre-distillation column 1 is connected to the top inlet of the primary water cooler 2, and the top outlet of the primary water cooler 2 is connected to the top inlet of the secondary water cooler 3. The bottom outlet of the primary water cooler 2 is connected to the top of the reflux tank 4. The top outlet of the secondary water cooler 3 is connected to the middle inlet of the separator 6, and the bottom outlet of the secondary water cooler 3 is connected to the top of the reflux tank 4. The bottom outlet of the separator 6 is connected to the top of the reflux tank 4, and the top outlet of the separator 6 is connected to the bottom of the water washing tower. The non-condensable gas inlet pipe 10 is connected to the water washing tower 7; the liquid outlet at the bottom of the reflux tank 4 is connected to the top of the pre-distillation tower 1 through the reflux pump 5; the top of the water washing tower 7 is connected to the pressure regulating valve 14 through the water washing tower non-condensable gas outlet pipe 11, the top of the water washing tower 7 is connected to the demineralized water pipe, and the liquid outlet at the bottom of the water washing tower 7 is connected to the crude methanol feed pipe of the pre-distillation tower 1 through the dilute methanol pump 8; the outlet of the pressure regulating valve 14 is connected to the non-condensable gas vent pipe 12 and the non-condensable gas recovery pipe 13, the non-condensable gas vent pipe 12 vents to a high point, the non-condensable gas recovery pipe 13 is connected to the H2S-containing acid gas inlet pipe of the sulfur recovery unit incinerator 9, the non-condensable gas vent pipe 12 is equipped with a non-condensable gas vent valve 15, and the non-condensable gas recovery pipe 13 is equipped with a non-condensable gas recovery valve 16 and a check valve 17.

[0015] A pressure transmitter 18 is installed at the top of the pre-distillation column 1. The pressure transmitter 18 is connected to a pressure controller 19 via signal, and the pressure controller 19 is electrically connected to a pressure regulating valve 14. This is used to control the pressure of the pre-distillation column. The pressure controller detects the pressure through the pressure transmitter and opens the pressure regulating valve when the preset value is reached.

[0016] Both the non-condensable gas vent valve 15 and the non-condensable gas recovery valve 16 are remote on / off valves equipped with solenoid valves, used to enable rapid on / off switching of the non-condensable gas vent valve and the non-condensable gas recovery valve.

[0017] The sulfur recovery unit incinerator 9 is equipped with fuel gas pipes and air pipes to provide fuel gas and oxygen for the incineration of non-condensable gas discharged from the pre-distillation tower 1 and H2S-containing acid gas from the low-temperature methanol washing process.

[0018] A flame detector 20 is installed on the sulfur recovery unit incinerator 9. The flame detector 20 is signal-connected to the interlock controller 21, which is electrically connected to the non-condensable gas vent valve 15 and the non-condensable gas recovery valve 16. The interlock controller 21 is controlled by the non-condensable gas activation / deactivation button 22. When the flame detector 20 detects a flame in the sulfur recovery unit incinerator 9, non-condensable gas can be activated, and the interlock controller 21 controls the non-condensable gas vent valve 15 to be fully closed and the non-condensable gas recovery valve 16 to be fully open. When the flame detector 20 detects no flame in the sulfur recovery unit incinerator 9, or when the non-condensable gas is manually deactivated, the interlock controller 21 controls the non-condensable gas vent valve 15 to be fully open and the non-condensable gas recovery valve 16 to be fully closed.

[0019] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of this utility model and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this utility model should be included within its protection scope. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A non-condensable gas treatment device for a crude methanol pre-rectification column, characterized by, The pre-distillation column, the first water cooler, the second water cooler, the reflux tank, the reflux pump, the separator, the water washing tower, the dilute methanol pump and the sulfur recovery device incinerator are connected; the top gas outlet of the pre-distillation column is connected with the top gas inlet of the first water cooler, the top gas outlet of the first water cooler is connected with the top gas inlet of the second water cooler, and the bottom liquid outlet of the first water cooler is connected with the top of the reflux tank; the top gas outlet of the second water cooler is connected with the middle gas inlet of the separator, and the bottom liquid outlet of the second water cooler is connected with the top of the reflux tank; the bottom liquid outlet of the separator is connected with the top of the reflux tank, and the top gas outlet of the separator is connected with the water washing tower through the non-condensable gas inlet pipe at the bottom of the water washing tower; the bottom liquid outlet of the reflux tank is connected with the top of the pre-distillation column through the reflux pump; the top of the water washing tower is connected with the pressure regulating valve through the non-condensable gas outlet pipe of the water washing tower, the top of the water washing tower is connected with the desalted water pipe, and the bottom liquid outlet of the water washing tower is connected with the crude methanol feeding pipe of the pre-distillation column through the dilute methanol pump; the outlet of the pressure regulating valve is connected with the non-condensable gas vent pipe and the non-condensable gas recovery pipe, the non-condensable gas vent pipe is vented at a high point, the non-condensable gas recovery pipe is connected with the H2S-containing acid gas inlet pipe of the sulfur recovery device incinerator, the non-condensable gas vent pipe is provided with a non-condensable gas vent valve, and the non-condensable gas recovery pipe is provided with a non-condensable gas recovery valve and a check valve.

2. The non-condensable gas treatment apparatus for a crude methanol pre-rectification column according to claim 1, characterized by, The top of the pre-distillation column is provided with a pressure transmitter, the pressure transmitter is signal-connected with a pressure controller, and the pressure controller is electrically connected with the pressure regulating valve.

3. The non-condensable gas treatment apparatus for a crude methanol pre-rectification column according to claim 1, characterized by, The non-condensable gas vent valve and the non-condensable gas recovery valve are remote on-off valves with electromagnetic valves.

4. The non-condensable gas treatment apparatus for a crude methanol pre-rectification column according to claim 1, characterized by, The sulfur recovery device incinerator is provided with a flame detector, the flame detector is signal-connected with an interlocking controller, and the interlocking controller is electrically connected with the non-condensable gas vent valve and the non-condensable gas recovery valve.

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