Device for preventing overpressure of flash tank in butadiene production by acetonitrile method

Abstract

The utility model relates to the technical field of butadiene production equipment, and particularly discloses a device for preventing overpressure of a flash tank in butadiene production by an acetonitrile method. According to the device disclosed by the utility model, the gas booster pump and the control and regulation valve with high and low flow alarm are additionally arranged on the torch discharge line, and when the back pressure of the torch affects the discharge and pressure relief of the gas medium of the flash tank, the gas booster pump is started, and the control and regulation valve is used for controlling the discharge amount of the torch, so that the gas in the flash tank is discharged, and the pressure in the flash tank is ensured to be stable. The gas in the flash tank can be continuously discharged to the torch pipe network without being influenced by the back pressure of the torch pipe network, so that the pressure in the flash tank and the distillation tower is stable, the concentration and the water content of regenerated acetonitrile are qualified, the solvent extraction effect is not influenced finally, and the stability of an extraction system and the qualified product are ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of butadiene production equipment, and specifically discloses a device for preventing overpressure of a flash tank in butadiene production by an acetonitrile method. Background Art

[0002] According to the characteristics of the acetonitrile production process, this device is divided into four units: extraction distillation, refining, acetonitrile regeneration and recovery, and chemical preparation. The function of the acetonitrile regeneration unit is to recycle part of the acetonitrile in the system and re-purify it to replenish it into the extraction distillation system to ensure that the extraction effect can meet the requirements.

[0003] The flash tank (V304 tank) is located in the acetonitrile regeneration unit. Its functions are: first, to receive the material condensed from the distillation tower (T304 tower); second, to serve as a buffer tank to provide a stable reflux rate and production rate; third, to discharge the gaseous medium mixed in the medium at the top of the T304 tower to the flare system through the flare line to prevent overpressure of the T304 tower and the V304 tank.

[0004] At present, the main material at the top of the T304 tower is liquid mixed with some gaseous material. The top material enters the V304 tank after passing through the condenser, and some hydrocarbons are discharged through the flare line. The controlled pressure of the T304 tower is relatively low, about 0-0.1MPa, and the pressure in the V304 tank is 0.18MPa. In actual production, the V304 tank is depressurized by the flare pipeline. When material is discharged in the flare line, the back pressure is too high, which affects the pressure release of the medium in the V304 tank, and eventually leads to overpressure of the T304 tower. The consequences of overpressure of the T304 tower are: first, the material balance of the T304 tower is broken; second, the increased operating temperature and operating pressure waste energy; third, the acetonitrile concentration at the top of the tower is reduced, and the increased water content affects the acetonitrile content in the tower, which eventually leads to the inability of the extraction system to operate.

[0005] Therefore, it is necessary to redesign and develop a device to prevent overpressure in the flash tank in the production of butadiene by the acetonitrile method, overcome the above problems and avoid affecting the normal operation of the equipment. Utility Model Content

[0006] The technical solution adopted by the utility model is as follows:

[0007] A device for preventing overpressure of a flash tank in the production of butadiene by an acetonitrile process, comprising a first valve 1, a drain valve, a gas booster pump 5, a regulating valve 7 with a flow rate high and low alarm, and a bypass valve 9;

[0008] The device is used in a local system consisting of a flash tank 12 and a distillation tower 10 in the production of butadiene by the acetonitrile method; the top of the distillation tower 10 is connected to a tower top condenser 11, the tower top condenser 11 is connected to a flash tank 12, the bottom of the flash tank 12 is connected to a distillation tower reflux pump 13, and the other end of the distillation tower reflux pump 13 is connected to the upper side wall of the distillation tower 10; a flare discharge line 19 is provided on the top of the flash tank 12;

[0009] The device is connected to the flare discharge line 19; the first valve 1, the gas booster pump 5, the second valve 6, the regulating valve 7 with high and low flow alarm and the third valve 8 are connected in series in sequence behind the flare discharge line 19; the pipeline behind the third valve 8 branches out a bypass pipeline 15 connected to the flare discharge line 19 in front of the first valve 1; the pipeline between the first valve 1 and the gas booster pump 5 is connected in parallel with a shower valve.

[0010] Preferably, the regulating valve 7 with high and low flow alarm is connected to the second valve 6 and the third valve 8 respectively.

[0011] Preferably, a bypass valve 9 is provided on the bypass line 15 .

[0012] Preferably, there are two shower guide valves, including a first shower guide valve 2 and a shower guide valve 4, which are respectively connected in parallel to the pipeline between the first valve 1 and the gas booster pump 5.

[0013] Furthermore, a check valve 3 is provided on the pipeline between the first shower valve 2 and the shower valve 4 .

[0014] Preferably, a sewage delivery pipeline 18 is provided at the bottom of the distillation tower 10 .

[0015] Furthermore, a sewage extraction pump 17 is provided between the distillation tower 10 and the sewage delivery pipeline 18 .

[0016] Preferably, an acetonitrile feed line 16 is provided on the upper wall of the distillation tower 10 .

[0017] Preferably, the distillation tower reflux pump 13 is connected in parallel with the pipeline between the distillation tower 10 to branch out a solvent acetonitrile extraction line 14, which goes to the extraction system to replenish the regenerated acetonitrile.

[0018] Preferably, the regulating valve 7 with high and low flow alarm has windows of high flow threshold and low flow threshold. When the flow through the regulating valve 7 with high and low flow alarm is higher than the high flow threshold or lower than the low flow threshold, the alarm sounds.

[0019] Beneficial effects achieved by the utility model:

[0020] The device disclosed by the utility model adds a gas booster pump and a control regulating valve with high and low flow alarms on the flare discharge line. When the flare back pressure affects the discharge pressure relief of the flash tank gas medium, the gas booster pump is started, and the control regulating valve is used to control the flare discharge volume, so as to realize the discharge of the gas in the flash tank and ensure the stability of the pressure in the flash tank. The gas in the flash tank can be continuously discharged to the flare pipe network, and is no longer affected by the back pressure of the flare pipe network. The pressure in the flash tank and the distillation tower can be stabilized, so that the concentration and water content of the regenerated acetonitrile are qualified, and finally the solvent extraction effect is not affected, so as to ensure the stability of the extraction system and the qualified product. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The utility model is a schematic diagram of a device for preventing overpressure of a flash tank in producing butadiene by an acetonitrile process. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is further described in detail in conjunction with the following embodiments. It should be noted that the utility model is not limited to the following embodiments.

[0023] Example 1

[0024] like Figure 1 As shown, a device for preventing overpressure of a flash tank in the production of butadiene by an acetonitrile process comprises a first valve 1, a drain valve, a gas booster pump 5, a regulating valve 7 with a flow rate high and low alarm, and a bypass valve 9;

[0025] The device is used in a local system consisting of a flash tank 12 and a distillation tower 10 in the acetonitrile process for producing butadiene; the top of the distillation tower 10 is connected to a tower top condenser 11, the tower top condenser 11 is connected to a flash tank 12, the bottom of the flash tank 12 is connected to a distillation tower reflux pump 13, and the other end of the distillation tower reflux pump 13 is connected to the upper side wall of the distillation tower 10; a flare discharge line 19 is provided on the top of the flash tank 12; a sewage delivery pipeline 18 is provided at the bottom of the distillation tower 10; a sewage extraction pump 17 is provided between the distillation tower 10 and the sewage delivery pipeline 18; an acetonitrile feed line 16 is provided on the upper side wall of the distillation tower 10; a solvent acetonitrile extraction line 14 is branched out in parallel from the pipeline between the distillation tower reflux pump 13 and the distillation tower 10 to the extraction system to replenish the regenerated acetonitrile.

[0026] The device is connected to the flare discharge line 19; the first valve 1, the gas booster pump 5, the second valve 6, the regulating valve 7 with high and low flow alarm and the third valve 8 are connected in series in sequence behind the flare discharge line 19; the pipeline behind the third valve 8 branches out a bypass pipeline 15 connected to the flare discharge line 19 in front of the first valve 1; the bypass pipeline 15 is provided with a bypass valve 9; the pipeline between the first valve 1 and the gas booster pump 5 is connected in parallel with a drain valve; there are two drain valves in total, including a first drain valve 2 and a drain valve 4, which are respectively connected in parallel to the pipeline between the first valve 1 and the gas booster pump 5; a check valve 3 is provided on the pipeline between the first drain valve 2 and the drain valve 4; the regulating valve 7 with high and low flow alarm is connected to the second valve 6 and the third valve 8 before and after, respectively.

[0027] The regulating valve 7 with high and low flow alarm has windows of high flow threshold and low flow threshold. When the flow through the regulating valve 7 with high and low flow alarm is higher than the high flow threshold or lower than the low flow threshold, the alarm sounds.

[0028] In this embodiment, valve 1, drain valve 2, check valve 3, drain valve 4, gas booster pump 5, valve 6, regulating valve 7 with high and low flow alarm, valve 8, bypass valve 9 are added to the flare discharge line of tank V304 to achieve the external discharge of gas medium in tank V304 and stabilize the pressure of tank V304 and tower T304. In specific operation:

[0029] When the regulating valve 7 with high and low flow alarm and the gas booster pump 5 need to be repaired, the valves 1 and 8 are closed and the bypass valve 9 is opened to realize non-stop maintenance of the related facilities.

[0030] The check valve 3 can prevent the pressure increase caused by gas backflow, and the drain valve 2 and the drain valve 4 serve as the discharge vents when the system is replaced.

[0031] The gas booster pump 5 serves as a gas booster facility for exhaust gas from the V304 tank.

[0032] The regulating valve 7 with high and low flow alarm is used as a flow pressure regulation control. The discharge gas flow is controlled by adjusting the valve opening to ensure the stability of the pressure in the V304 tank. The regulating valve has a high and low flow alarm to remind the operator to prevent the phenomenon of too low or too high flow being ignored.

Claims

1. A device for preventing overpressure of a flash tank in the production of butadiene by an acetonitrile process, characterized in that: It comprises a first valve (1), a shower valve, a gas booster pump (5), a regulating valve with a high and low flow alarm (7), and a bypass valve (9); The device is a local system composed of a flash tank (12) and a distillation tower (10) used in the production of butadiene by the acetonitrile method; the top of the distillation tower (10) is connected to a tower top condenser (11), the tower top condenser (11) is connected to the flash tank (12), the bottom of the flash tank (12) is connected to a distillation tower reflux pump (13), and the other end of the distillation tower reflux pump (13) is connected to the upper side wall of the distillation tower (10); a flare discharge line (19) is provided at the top of the flash tank (12); The device is connected to a flare discharge line (19); a first valve (1), a gas booster pump (5), a second valve (6), a regulating valve (7) with a high and low flow alarm, and a third valve (8) are sequentially connected in series behind the flare discharge line (19); a bypass line (15) is branched from the pipeline behind the third valve (8) and connected to the flare discharge line (19) before the first valve (1); and a drain valve is connected in parallel to the pipeline between the first valve (1) and the gas booster pump (5).

2. The device for preventing overpressure of a flash tank in the production of butadiene by the acetonitrile process according to claim 1, characterized in that: The regulating valve (7) with high and low flow alarm is connected to the second valve (6) and the third valve (8) respectively.

3. The device for preventing overpressure of a flash tank in the production of butadiene by the acetonitrile process according to claim 1, characterized in that: The bypass pipe (15) is provided with a bypass valve (9).

4. The device for preventing overpressure of a flash tank in the production of butadiene by the acetonitrile process according to claim 1, characterized in that: There are two shower guide valves, including a first shower guide valve (2) and a shower guide valve (4), which are respectively connected in parallel to the pipeline between the first valve (1) and the gas booster pump (5).

5. The device for preventing overpressure of a flash tank in the production of butadiene by the acetonitrile process according to claim 4, characterized in that: A check valve (3) is provided on the pipeline between the first shower guide valve (2) and the shower guide valve (4).

6. The device for preventing overpressure of a flash tank in the production of butadiene by the acetonitrile process according to claim 1, characterized in that: A sewage delivery pipeline (18) is provided at the bottom of the distillation tower (10).

7. The device for preventing overpressure of a flash tank in the production of butadiene by the acetonitrile process according to claim 6, characterized in that: A sewage extraction pump (17) is provided between the distillation tower (10) and the sewage delivery pipeline (18).

8. The device for preventing overpressure of a flash tank in the production of butadiene by the acetonitrile process according to claim 1, characterized in that: An acetonitrile feed line (16) is provided on the upper side wall of the distillation tower (10).

9. The device for preventing overpressure of a flash tank in the production of butadiene by the acetonitrile process according to claim 1, characterized in that: The pipeline between the distillation tower reflux pump (13) and the distillation tower (10) is connected in parallel to branch out a solvent acetonitrile extraction line (14), which goes to the extraction system to replenish the regenerated acetonitrile.

10. The device for preventing overpressure of a flash tank in the production of butadiene by the acetonitrile process according to claim 1, characterized in that: The regulating valve (7) with a high and low flow alarm has windows with a high flow threshold and a low flow threshold. When the flow through the regulating valve (7) with a high and low flow alarm is higher than the high flow threshold or lower than the low flow threshold, an alarm sounds.

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