Natural gas purification device and online commissioning method thereof

Abstract

The present application relates to a kind of natural gas purification device and its on-line commissioning method, including first absorption tower, separator, hydrolysis reactor, second absorption tower, semi-rich amine liquid buffer tank, pump and amine liquid processing device;Hydrolysis catalyst is arranged in the hydrolysis reactor;It further includes gas phase balance pipeline, one end of the gas phase balance pipeline is communicated with the top of the semi-rich amine liquid buffer tank, the other end of the gas phase balance pipeline is communicated with the exhaust port of the hydrolysis reactor with the communication pipeline of the second gas pipeline.The natural gas purification device provided by the present application can effectively reduce the total sulfur content in natural gas to meet the new national standard requirements, and can also realize on-line commissioning to avoid large amount of natural gas production loss caused by shutdown, simple operation, easy to popularize.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas purification, and in particular to a natural gas purification device and an online operation method thereof. Background Art

[0002] Natural gas raw materials mainly contain harmful gases such as carbonyl sulfide and hydrogen sulfide. Natural gas purification is an important process for obtaining qualified natural gas products. The total sulfur content in the purified natural gas must meet the national standard for Class I gas.

[0003] At present, the natural gas purification device mainly consists of two absorption towers, such as Figure 1 As shown, the natural gas feedstock enters the first absorption tower 1 from the first gas inlet line 101 and comes into countercurrent contact with the amine liquid in the first absorption tower 1. The gas is then discharged from the top of the first absorption tower 1 along the second cross-line valve group 12 and enters the second absorption tower 2. The gas then comes into countercurrent contact with the amine liquid in the second absorption tower 2 and is discharged from the top of the second absorption tower 2. At the same time, the amine liquid enters the top of the second absorption tower 1 from the first liquid inlet line 103, and then the amine liquid is discharged from the bottom of the second absorption tower 1 and passes through the first cross-line valve group 11 into the top of the first absorption tower 1. The amine liquid is then discharged from the bottom of the first absorption tower 1. The discharged amine liquid passes through the amine liquid treatment device system and flows back to the first liquid inlet line 103. The amine liquid can absorb and purify the hydrogen sulfide gas in the natural gas. After purification by the current natural gas purification device, the total sulfur content in the natural gas can be reduced to 40 mg / Nm 3 However, the latest national standard "Natural Gas" (GB17820-2018) issued by the State Administration for Market Regulation has changed the total sulfur content in the first category of gas indicators from the original no more than 60mg / Nm 3 Changed to no more than 20mg / Nm 3 .

[0004] Therefore, it is now necessary to develop a natural gas purification device based on the existing purification device, which can not only effectively reduce the total sulfur content in natural gas to meet the requirements of the new national standard, but also be put into online operation to avoid large-scale natural gas production losses caused by shutdowns. Summary of the Invention

[0005] The purpose of the present invention is to provide a natural gas purification device and an online commissioning method thereof to address the problem that the total sulfur content of the purified natural gas in the existing natural gas purification device is difficult to meet the requirements of the new national standard. The natural gas purification device provided by the present invention can not only effectively reduce the total sulfur content in natural gas to meet the requirements of the new national standard, but also achieve online commissioning to avoid large-scale natural gas production losses due to shutdowns. It is simple to operate and easy to promote.

[0006] In order to achieve the above object, the technical scheme adopted by the present application is:

[0007] A natural gas purification device, comprising a first absorption tower, a separator, a hydrolysis reactor, a second absorption tower, a semi-rich amine liquid buffer tank, a pump and an amine liquid treatment device; the hydrolysis reactor is provided with a hydrolysis catalyst;

[0008] The bottom of the first absorption tower is provided with a first gas inlet pipeline and a second liquid outlet pipeline, and the top of the first absorption tower is provided with a first gas outlet pipeline and a second liquid inlet pipeline; the bottom of the second absorption tower is provided with a second gas inlet pipeline and a first liquid outlet pipeline, and the top of the second absorption tower is provided with a second gas outlet pipeline and a first liquid inlet pipeline; the first gas outlet pipeline is in communication with the gas inlet of the separator and the second gas inlet pipeline respectively, the top gas outlet of the separator is in communication with the gas inlet of the hydrolysis reactor, and the gas outlet of the hydrolysis reactor is in communication with the second gas inlet pipeline;

[0009] The first liquid outlet pipeline is in communication with the liquid inlet of the semi-rich amine liquid buffer tank and the second liquid inlet pipeline respectively; the bottom liquid outlet of the semi-rich amine liquid buffer tank is in communication with the pump; the liquid outlet of the pump is in communication with the second liquid inlet pipeline; the second liquid outlet pipeline is in communication with the amine liquid treatment device, and the liquid outlet of the amine liquid treatment device is in communication with the first liquid inlet pipeline;

[0010] Further comprising a gas phase balance pipeline, one end of the gas phase balance pipeline is in communication with the top of the semi-rich amine liquid buffer tank, and the other end of the gas phase balance pipeline is in communication with the communication pipeline of the gas outlet of the hydrolysis reactor and the second gas inlet pipeline.

[0011] The natural gas purification device provided in the application adds a hydrolysis gas pipeline and a new amine liquid flow pipeline in the original device system (a first absorption tower, a second absorption tower and an amine liquid treatment device), the added hydrolysis gas pipeline mainly comprises a separator and a hydrolysis reactor, the new amine liquid flow pipeline mainly comprises a semi-rich amine liquid buffer tank and a pump, if only the hydrolysis gas pipeline is added, the hydrolysis gas pipeline cannot be put into operation on line on the basis of the original amine liquid flow pipeline, which directly causes the flow of amine liquid in the amine liquid flow pipeline to stop, the pressure of the gas-liquid pipeline cannot be balanced, and the amine liquid cannot be circulated under the action of gravity. After being put into operation, the pipeline, which is in communication between the first liquid discharge pipeline and the second liquid inlet pipeline, is closed, natural gas enters the first absorption tower from the first gas inlet pipeline, after countercurrent contact with the amine liquid in the first absorption tower, the gas is discharged from the first gas outlet pipeline; then the natural gas is purified in two ways, the first way is to enter the second gas inlet pipeline along the communication pipeline between the first gas outlet pipeline and the second gas inlet pipeline, after countercurrent contact with the amine liquid in the second absorption tower, the gas is discharged from the second gas outlet pipeline; the second way is to enter the separator to separate the entrained amine liquid, then the gas enters the hydrolysis reactor to perform a high-temperature hydrolysis reaction, and the carbonyl sulfur in the natural gas is converted into hydrogen sulfide and carbon dioxide, then the gas enters the second gas inlet pipeline, after countercurrent contact with the amine liquid in the second absorption tower, the gas is discharged from the second gas outlet pipeline. At the same time, the amine liquid enters the top of the second absorption tower from the first liquid inlet pipeline, then the amine liquid is discharged from the bottom of the second absorption tower and enters the semi-rich amine liquid buffer tank, then the amine liquid is discharged from the bottom of the semi-rich amine liquid buffer tank, transported to the second liquid inlet pipeline through the pump, then the amine liquid is discharged from the second liquid discharge pipeline, and after being discharged, the amine liquid is returned to the first liquid inlet pipeline through the amine liquid treatment device system. By adding the hydrolysis gas pipeline and the new amine liquid flow pipeline, the entire natural gas purification device can not only effectively reduce the total sulfur content in the natural gas to meet the requirements of the new national standard, but also realize on-line operation to avoid a large amount of natural gas production damage caused by shutdown.

[0012] Further, a one-way valve is arranged on the second liquid discharge pipeline. The arrangement of the one-way valve can prevent the amine liquid from flowing back.

[0013] Further, the hydrolysis reactor comprises a heat exchanger, a preheater and a hydrolysis reaction tank; a hydrolysis catalyst is arranged in the hydrolysis reaction tank; a top exhaust port of the separator is in communication with a heating gas inlet port of the heat exchanger, a heating gas outlet port of the heat exchanger is in communication with a gas inlet port of the preheater, a gas outlet port of the preheater is in communication with a gas inlet port of the hydrolysis reaction tank, a gas outlet port of the hydrolysis reaction tank is in communication with a cooling gas inlet port of the heat exchanger, and a cooling gas outlet port of the heat exchanger is in communication with the second gas inlet pipeline.

[0014] Further, the hydrolysis reactor further comprises a cooler, one end of the cooler is communicated with the cooling exhaust port of the heat exchanger, and the other end of the cooler is communicated with the second gas inlet pipeline.

[0015] Further, the amine liquid treatment device comprises a flash tank, an amine liquid regeneration tower, a first lean amine liquid pump, an amine liquid buffer tank and a second lean amine liquid pump; the second liquid outlet pipeline is communicated with the liquid inlet of the flash tank, the liquid outlet of the flash tank is communicated with the liquid inlet at the top of the amine liquid regeneration tower, the liquid outlet at the bottom of the amine liquid regeneration tower is communicated with the liquid inlet of the first lean amine liquid pump, the liquid outlet of the first lean amine liquid pump is communicated with the liquid inlet of the amine liquid buffer tank, the liquid outlet of the amine liquid buffer tank is communicated with the liquid inlet of the second lean amine liquid pump, and the liquid outlet of the second lean amine liquid pump is communicated with the first liquid inlet pipeline.

[0016] Further, the top of the semi-rich amine liquid buffer tank is provided with a first safety valve auxiliary line, and the top of the separator is provided with a second safety valve auxiliary line.

[0017] Further, a first valve group is arranged on the pipeline between the second gas inlet pipeline and the gas phase balance pipeline, a second valve group is arranged on the communication pipeline between the first exhaust pipeline and the separator, and the second cross-line valve group is arranged on the communication pipeline between the first exhaust pipeline and the second gas inlet pipeline.

[0018] An inlet electric valve is arranged on the communication pipeline between the semi-rich amine liquid buffer tank and the pump, an outlet electric valve, a first regulating valve and the third valve group are sequentially arranged on the communication pipeline from the pump to the second liquid inlet pipeline, a reflux pipeline is arranged on the pipeline between the outlet electric valve and the first regulating valve, the reflux pipeline is communicated with the bottom of the semi-rich amine liquid buffer tank, and a reflux valve is arranged on the reflux pipeline; a fourth valve group is arranged on the communication pipeline between the first liquid outlet pipeline and the liquid inlet of the semi-rich amine liquid buffer tank; a fifth valve group is arranged on the gas phase balance pipeline; and the first cross-line valve group is arranged on the pipeline between the first liquid outlet pipeline and the second liquid inlet pipeline.

[0019] Further, a first sampling port is arranged on the communication pipeline between the exhaust port at the top of the separator and the heating gas inlet of the heat exchanger; and the second sampling port is arranged on the communication pipeline between the hydrolysis reactor and the gas phase balance pipeline.

[0020] Another object of the present application is to provide an online operation method of the natural gas purification device.

[0021] An online commissioning method of a natural gas purification device, before the online commissioning starts and before the online commissioning is completed, natural gas raw materials enter the first absorption tower from a first gas inlet pipeline and are in countercurrent contact with amine liquid in the first absorption tower, and then gas is discharged from the top of the first absorption tower and enters the second absorption tower along the second cross-line valve group, and then the gas is in countercurrent contact with amine liquid in the second absorption tower and is discharged from the top of the second absorption tower; at the same time, amine liquid enters the top of the second absorption tower from the first liquid inlet pipeline, and then the amine liquid is discharged from the bottom of the second absorption tower and enters the top of the first absorption tower along the first cross-line valve group, and then the amine liquid is discharged from the second liquid outlet pipeline, and after being treated in an amine liquid treatment device, the amine liquid is returned to the first liquid inlet pipeline; comprising the following steps:

[0022] Step 1, commissioning preparation is performed;

[0023] Step 2, amine liquid flow conversion commissioning;

[0024] Step 21, slightly open the third valve group, fill the pipeline between the first regulating valve and the third valve group with liquid, and after filling is completed, fully open the third valve group; then, slightly open the fourth valve group to slowly fill the semi-rich amine liquid buffer tank with liquid, when the liquid level of the semi-rich amine liquid buffer tank rises to 40%-60%, open the fifth valve group, the inlet electric valve, and tank pump the pump, after tank pumping is completed, start the pump, slightly open the outlet electric valve to fill the communication pipeline between the first regulating valve and the pump with liquid, after filling is completed, fully open the outlet electric valve, and at the same time, open the reflux valve to perform amine liquid reflux; then open the first regulating valve to feed liquid to the top of the first absorption tower;

[0025] Step 22, fully open the fourth valve group and fully close the first cross-line valve group; then adjust the first regulating valve and fully close the reflux valve, and the liquid level in the semi-rich amine liquid buffer tank is controlled to be 40%-60%; complete the amine liquid flow conversion commissioning;

[0026] Step 3, natural gas flow conversion commissioning: preheat the preheater in advance, fully open the second valve group, and then fully close the second cross-line valve group and fully open the first valve group, to complete the natural gas flow conversion commissioning.

[0027] The present application provides an online commissioning method of a natural gas purification device, which mainly includes three steps, namely, commissioning preparation, amine liquid flow conversion commissioning, and natural gas flow conversion commissioning. Through the cooperation between various devices and the sequence cooperation of amine liquid commissioning first and then gas commissioning, online commissioning is successfully completed, normal circulation of amine liquid is ensured, a large amount of natural gas production loss caused by shutdown is avoided, and the operation is simple and convenient for promotion.

[0028] Further, the step 1 operation preparation specific operation includes: slowly opening the first safety valve vice line to the semi-rich buffer tank connection pipeline to relieve pressure to the high-pressure flare after closing the first safety valve vice line; or / and, closing the first valve group, slowly opening the second valve group, using the first absorption tower top discharged natural gas to charge the gas flow pipeline to 0.5Mpa-1Mpa, then opening the second safety valve vice line to relieve pressure to the high-pressure flare, repeating the operation more than 3 times, then opening the first sampling port and the second sampling port to sample respectively, when the methane content is not less than 96mol%, the natural gas replacement is qualified, then continue to use the first absorption tower top discharged natural gas to charge the gas flow pipeline to balance with the pressure of the second absorption tower, and turn off the second valve group.

[0029] Further, the concentration range of hydrogen sulfide in the natural gas raw material is 5-6mol%; the concentration range of carbonyl sulfur in the natural gas raw material is 100-200mg / Nm 3 ; the mass concentration of the amine solution is 38-50%; after completing the operation, the natural gas flow discharged from the first gas inlet pipeline (101) is 4-13.75x10 4 Nm 3 / h; the amine solution flow discharged from the pump (9) is 160-200t / h.

[0030] Further, the hydrolysis catalyst is an alumina catalyst.

[0031] In summary, due to the adoption of the above technical scheme, the beneficial effects of the present application are:

[0032] 1. The natural gas purification device provided by the application adds a hydrolysis gas pipeline and a new amine liquid flow pipeline in the original device system (first absorption tower, second absorption tower and amine liquid treatment device), the added hydrolysis gas pipeline mainly includes a separator and a hydrolysis reactor, and the new amine liquid flow pipeline mainly includes a semi-rich amine liquid buffer tank and a pump. If only the hydrolysis gas pipeline is added, the online operation of the hydrolysis gas pipeline cannot be carried out on the basis of the original amine liquid flow pipeline, which directly leads to the stop of the flow of amine liquid in the amine liquid flow pipeline, the pressure of the gas-liquid pipeline cannot be balanced, and the amine liquid cannot circulate under the action of gravity. After operation, the pipeline connecting the first liquid discharge pipeline and the second liquid inlet pipeline is closed, natural gas enters the first absorption tower from the first gas inlet pipeline, and after countercurrent contact with the amine liquid in the first absorption tower, the gas is discharged from the first gas discharge pipeline. Then the natural gas is purified in two ways. The first way is to enter the second gas inlet pipeline along the communication pipeline between the first gas discharge pipeline and the second gas inlet pipeline, and after countercurrent contact with the amine liquid in the second absorption tower, the gas is discharged from the second gas discharge pipeline. The second way is to enter the separator to separate the entrained amine liquid, and then the gas enters the hydrolysis reactor for high-temperature hydrolysis reaction to convert the carbonyl sulfur in the natural gas into hydrogen sulfide and carbon dioxide. Then the gas enters the second gas inlet pipeline, and after countercurrent contact with the amine liquid in the second absorption tower, the gas is discharged from the second gas discharge pipeline. At the same time, the amine liquid enters the top of the second absorption tower from the first liquid inlet pipeline, and then the amine liquid is discharged from the bottom of the second absorption tower and enters the semi-rich amine liquid buffer tank. Then the amine liquid is discharged from the bottom of the semi-rich amine liquid buffer tank and transported to the second liquid inlet pipeline through the pump. Then the amine liquid is discharged from the second liquid discharge pipeline, and after the amine liquid treatment device, the amine liquid is returned to the first liquid inlet pipeline. By adding the hydrolysis gas pipeline and the new amine liquid flow pipeline, the entire natural gas purification device can not only effectively reduce the total sulfur content in the natural gas to meet the new national standard requirements, but also realize online operation to avoid large natural gas production loss caused by shutdown.

[0033] 2. The application provides an online operation method of a natural gas purification device, which mainly comprises three steps of operation preparation, amine liquid flow conversion operation and natural gas flow conversion operation. Through the cooperation between various devices and the sequence cooperation of amine liquid operation first and then gas operation, the online operation is successfully completed, the normal circulation of the amine liquid is ensured, the loss of a large amount of natural gas production caused by shutdown is avoided, and the operation is simple and convenient for promotion. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of a natural gas purification device of the prior art.

[0035] Figure 2 It is a structural schematic diagram of a natural gas purification device disclosed by the application.

[0036] Figure: 1-First absorption tower; 10-Second crossover valve group; 11-First crossover valve group; 12-First valve group; 13-Second valve group; 14-Fourth valve group; 15-Third valve group; 16-First regulating valve; 17-Return valve; 18-First sampling port; 19-Second sampling port; 101-First gas inlet pipeline; 1011-First gas outlet pipeline; 102-Second gas outlet pipeline; 1021-Second gas inlet pipeline; 103-First liquid inlet pipeline; 1031-First liquid outlet pipeline; 104-Second liquid outlet pipeline; 1041-Second liquid inlet pipeline; 2-Second absorption tower; 22-First safety valve auxiliary line; 23-Second safety valve auxiliary line; 24-Inlet electric valve; 25-Outlet electric valve; 26-Fifth valve group; 27-Check valve; 28-Flash tank; 29-Amine liquid regeneration tower; 30-First lean amine liquid pump; 31-Amine liquid buffer tank; 32-Second lean amine liquid pump; 3-Separator; 4-Heat exchanger; 5-Preheater; 6-Hydrolysis reactor; 7-Cooler; 8-Semi-rich amine liquid buffer tank; 81-Gas phase equilibrium pipeline; 82-Return pipeline; 9-Pump. DETAILED DESCRIPTION

[0037] The present application will be described in further detail below with reference to the drawings.

[0038] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0039] Example 1

[0040] A natural gas purification device, comprising a first absorption tower 1, a separator 3, a hydrolysis reactor, a second absorption tower 2, a semi-rich amine liquid buffer tank 8, a pump 9 and an amine liquid treatment device; the hydrolysis reactor comprises a heat exchanger 4, a preheater 5, a hydrolysis reactor tank 6 and a cooler 7; the hydrolysis reactor tank 6 is provided with a hydrolysis catalyst; the amine liquid treatment device comprises a flash tank 28, an amine liquid regeneration tower 29, a first lean amine liquid pump 30, an amine liquid buffer tank 31 and a second lean amine liquid pump 32;

[0041] The bottom of the first absorption tower 1 is provided with a first air inlet line 101 and a second liquid discharge line 104, and the top of the first absorption tower is provided with a first exhaust line 1011 and a second liquid inlet line 1041; the bottom of the second absorption tower 2 is provided with a second air inlet line 1021 and a first liquid discharge line 1031, and the top of the second absorption tower 2 is provided with a second exhaust line 102 and a first liquid inlet line 103; the first exhaust line 1011 is connected to the air inlet of the separator 3, the second exhaust line 1011 and the first liquid inlet line 103 respectively. The air intake line 1021 is connected, the top exhaust port of the separator 3 is connected to the heating air intake port of the heat exchanger 4, the heating exhaust port of the heat exchanger 4 is connected to the air intake port of the preheater 5, the exhaust port of the preheater 5 is connected to the air intake port of the hydrolysis reaction tank 6, the exhaust port of the hydrolysis reaction tank 6 is connected to the cooling air intake port of the heat exchanger 4, one end of the cooler 7 is connected to the cooling exhaust port of the heat exchanger 4, and the other end of the cooler 7 is connected to the second air intake line 1021.

[0042] The first liquid discharge pipeline 1031 is respectively connected to the liquid inlet of the semi-rich amine liquid buffer tank 8 and the second liquid inlet pipeline 1041; the bottom liquid discharge port of the semi-rich amine liquid buffer tank 8 is connected to the pump 9; the liquid discharge port of the pump 9 is connected to the second liquid inlet pipeline 1041; the second liquid discharge pipeline 104 is connected to the liquid inlet of the flash tank 28, the liquid discharge port of the flash tank 28 is connected to the liquid inlet at the top of the amine liquid regeneration tower 29, the liquid discharge port at the bottom of the amine liquid regeneration tower 29 is connected to the liquid inlet of the first lean amine liquid pump 30, the liquid discharge port of the first lean amine liquid pump 30 is connected to the liquid inlet of the amine liquid buffer tank 31, the liquid discharge port of the amine liquid buffer tank 31 is connected to the liquid inlet of the second lean amine liquid pump 32, and the liquid discharge port of the second lean amine liquid pump 32 is connected to the first liquid inlet pipeline 103.

[0043] It also includes a gas phase balance pipeline 81, one end of which is connected to the top of the semi-rich amine liquid buffer tank 8, and the other end of the gas phase balance pipeline 81 is connected to the exhaust port of the hydrolysis reactor and the connecting pipe of the second air inlet pipeline 1021.

[0044] The top of the semi-rich amine liquid buffer tank 8 is provided with a first safety valve auxiliary line 22; the top of the separator 3 is provided with a second safety valve auxiliary line 23. A first valve group 12 is arranged on the pipeline between the second gas inlet pipeline 1021 and the gas phase balance pipeline 81; a second valve group 13 is arranged on the communication pipeline between the first gas outlet pipeline 1011 and the separator 3; the second cross-line valve group 10 is arranged on the communication pipeline between the first gas outlet pipeline 1011 and the second gas inlet pipeline 1021; an inlet electric valve 24 is arranged on the communication pipeline between the semi-rich amine liquid buffer tank 8 and the pump 9; an outlet electric valve 25, a first regulating valve 16 and the third valve group 15 are arranged in sequence on the communication pipeline from the pump 9 to the second liquid inlet pipeline 1041, a backflow pipeline 82 is arranged on the pipeline between the outlet electric valve 25 and the first regulating valve 16, the backflow pipeline 82 communicates with the bottom of the semi-rich amine liquid buffer tank 8, and a backflow valve 17 is arranged on the backflow pipeline 82; a fourth valve group 14 is arranged on the communication pipeline between the first liquid outlet pipeline 1031 and the liquid inlet of the semi-rich amine liquid buffer tank 8; a fifth valve group 26 is arranged on the gas phase balance pipeline 81; and the first cross-line valve group 11 is arranged on the pipeline where the first liquid outlet pipeline 1031 communicates with the second liquid inlet pipeline 1041. A first sampling port 18 is arranged on the communication pipeline between the gas outlet at the top of the separator 3 and the heating gas inlet of the heat exchanger 4; and the second sampling port 19 is arranged on the communication pipeline between the hydrolysis reactor and the gas phase balance pipeline 81.

[0045] Example 2

[0046] The natural gas purification device of Example 1 is used in a natural gas purification plant for online operation. In the raw natural gas, the hydrogen sulfide content is 5.55 mol%, the carbonyl sulfide content is 144.25 mg / Nm 3 , the amine liquid is 50 w% MDEA composite solvent, the circulation amount is 180 t / h, and the natural gas is 3 million square meters per day. Before the online operation starts and after the online operation is completed, the raw natural gas from the first gas inlet pipeline 101 enters the first absorption tower 1 and is countercurrently contacted with the amine liquid in the first absorption tower 1, and then the gas is discharged from the top of the first absorption tower 1 and enters the second absorption tower 2 through the second cross-line valve group 12, and then the gas is countercurrently contacted with the amine liquid in the second absorption tower 2 and is discharged from the top of the second absorption tower 2; at the same time, the amine liquid enters the top of the second absorption tower 1 from the first liquid inlet pipeline 103, and then the amine liquid is discharged from the bottom of the second absorption tower 1 and enters the top of the first absorption tower 1 through the first cross-line valve group 11, and then the amine liquid is discharged from the second liquid outlet pipeline 104, and then the discharged amine liquid enters the amine liquid treatment device for treatment and then flows back to the first liquid inlet pipeline 103.

[0047] Online commissioning

[0048] comprising the following steps:

[0049] Step 1, proceed to commissioning;

[0050] Slowly open the first safety valve sub-line 22 to relieve the pressure of the connecting pipeline of the semi-rich buffer tank 8 to the high-pressure flare, then close the first safety valve sub-line 22; or / and, close the first valve group 12, slowly open the second valve group 13, and use the natural gas discharged from the top of the first absorption tower 1 to pressurize the gas flow pipeline to 0.5-1 MPa, then open the second safety valve sub-line 23 to relieve the pressure to the high-pressure flare, and repeat the operation more than 3 times, then open the first sampling port 18 and the second sampling port 19 respectively for sampling, and when the methane content is not less than 96 mol%, the natural gas replacement is qualified, then continue to pressurize the gas flow pipeline with the natural gas discharged from the top of the first absorption tower 1 to balance the pressure of the second absorption tower 2, and close the second valve group 13.

[0051] Step 2, convert the amine liquid process to commissioning;

[0052] Step 21, slightly open the third valve group 15 to fill the pipeline between the first regulating valve 16 and the third valve group 15 with liquid, and then fully open the third valve group 15 after the liquid filling is completed; then, slightly open the fourth valve group 14 to slowly fill the semi-rich amine liquid buffer tank 8 with liquid, and when the liquid level of the semi-rich amine liquid buffer tank 8 rises to 40%-60%, open the fifth valve group 26 and the inlet electric valve 24 to tank pump the pump 9, and after the tank pumping is completed, start the pump 9, slightly open the outlet electric valve 25 to fill the communication pipeline between the first regulating valve 16 and the pump 9 with liquid, fully open the outlet electric valve 25 after the liquid filling is completed, and open the reflux valve 17 for amine liquid reflux; then open the first regulating valve 16 to the top of the first absorption tower 1;

[0053] Step 22, fully open the fourth valve group 14 and fully close the first cross-line valve group 11; then adjust the first regulating valve 16 and fully close the reflux valve 17, and control the liquid level in the semi-rich amine liquid buffer tank 8 at 40%-60%; complete the conversion of the amine liquid process to commissioning;

[0054] Step 3, convert the natural gas process to commissioning: preheat the preheater in advance, fully open the second valve group 13, then fully close the second cross-line valve group 10 and fully open the first valve group 12, and complete the conversion of the natural gas process to commissioning.

[0055] Commissioning in use

[0056] The first exhaust pipeline 1011 is connected with the second gas inlet pipeline 102, and the gas is discharged from the second exhaust pipeline 102 after countercurrent contact with the amine liquid in the second absorption tower 2. The second route is to enter the separator 3 to separate the entrained amine liquid, and then the gas is heated to 110 DEG C in the heat exchanger, and then the natural gas is continuously heated to 130 DEG C in the preheater, and then the gas enters the hydrolysis reaction tank 6 to carry out high-temperature hydrolysis reaction under the condition of catalyst, and the carbonyl sulfur in the natural gas is converted into hydrogen sulfide and carbon dioxide, and then the gas enters the second gas inlet pipeline 1021, and the gas is discharged from the second exhaust pipeline 102 after countercurrent contact with the amine liquid in the second absorption tower 2. At the same time, the amine liquid enters the top of the second absorption tower 2 from the first liquid inlet pipeline 103, and then the amine liquid is discharged from the bottom of the second absorption tower 2 and enters the semi-rich amine liquid buffer tank 8, and then the amine liquid is discharged from the bottom of the semi-rich amine liquid buffer tank 8 and is transported to the second liquid inlet pipeline 1041 through the pump 9, and then the amine liquid is discharged from the second liquid outlet pipeline 104, and the second liquid outlet pipeline 104 is connected with the liquid inlet of the flash tank 28, and the light hydrocarbon and a small amount of hydrogen sulfide in the rich liquid are flashed out at low pressure. The liquid outlet of the flash tank 28 is connected with the liquid inlet at the top of the amine regeneration tower 29, and the regeneration tower is a packed tower, and the heat source is provided by low-pressure steam, and the hydrogen sulfide and other acidic gases in the rich liquid are resolved under the condition of low pressure and high temperature in the tower to realize the regeneration of the rich liquid. The liquid outlet at the bottom of the amine regeneration tower 29 is connected with the liquid inlet of the first lean amine liquid pump 30, the liquid outlet of the first lean amine liquid pump 30 is connected with the liquid inlet of the amine buffer tank 31, the liquid outlet of the amine buffer tank 31 is connected with the liquid inlet of the second lean amine liquid pump 32, and the liquid outlet of the second lean amine liquid pump 32 is connected with the first liquid inlet pipeline 103.

[0057] After testing, the total sulfur of the natural gas discharged from the second exhaust pipeline 102 is reduced to 9.52 mg / Nm 3 .

[0058] The natural gas purification device provided by the application adds a hydrolysis gas pipeline and a new amine liquid flow pipeline in the original device system (a first absorption tower, a second absorption tower and an amine liquid treatment device), the added hydrolysis gas pipeline mainly comprises a separator and a hydrolysis reactor, the new amine liquid flow pipeline mainly comprises a semi-rich amine liquid buffer tank and a pump, if only the hydrolysis gas pipeline is added, the online operation of the hydrolysis gas pipeline cannot be carried out on the basis of the original amine liquid flow pipeline, which directly leads to the stop of the flow of amine liquid in the amine liquid flow pipeline, the pressure of the gas-liquid pipeline cannot be balanced, and the amine liquid cannot be circulated under the action of gravity. By adding the hydrolysis gas pipeline and the new amine liquid flow pipeline, the entire natural gas purification device can not only effectively reduce the total sulfur content in natural gas to meet the requirements of the new national standard, but also realize online operation to avoid a large amount of natural gas production loss caused by shutdown. The application provides an online operation method of the natural gas purification device, which mainly comprises three steps, namely, operation preparation, amine liquid flow conversion operation and natural gas flow conversion operation, by cooperation between various devices and cooperation of the sequence of amine liquid operation first and then gas operation, the online operation is successfully completed, the normal circulation of amine liquid is ensured, a large amount of natural gas production loss caused by shutdown is avoided, the operation is simple, and the method is convenient to popularize.

[0059] The above merely describes preferred embodiments of the application and is not intended to limit the application, and any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A natural gas purification apparatus, characterized by, It comprises a first absorption tower (1), a separator (3), a hydrolysis reactor, a second absorption tower (2), a semi-rich amine liquid buffer tank (8), a pump (9) and an amine liquid treatment device; the hydrolysis reactor is provided with a hydrolysis catalyst; The bottom of the first absorption tower (1) is provided with a first gas inlet pipeline (101) and a second liquid outlet pipeline (104), the top of the first absorption tower is provided with a first gas outlet pipeline (1011) and a second liquid inlet pipeline (1041); the bottom of the second absorption tower (2) is provided with a second gas inlet pipeline (1021) and a first liquid outlet pipeline (1031), the top of the second absorption tower (2) is provided with a second gas outlet pipeline (102) and a first liquid inlet pipeline (103); the first gas outlet pipeline (1011) is communicated with the gas inlet of the separator (3) and the second gas inlet pipeline (1021) respectively, the top gas outlet of the separator (3) is communicated with the gas inlet of the hydrolysis reactor, the gas outlet of the hydrolysis reactor is communicated with the second gas inlet pipeline (1021); a one-way valve is arranged on the second liquid outlet pipeline (104); The first liquid outlet pipeline (1031) is communicated with the liquid inlet of the semi-rich amine liquid buffer tank (8) and the second liquid inlet pipeline (1041) respectively; the bottom liquid outlet of the semi-rich amine liquid buffer tank (8) is communicated with the pump (9); the liquid outlet of the pump (9) is communicated with the second liquid inlet pipeline (1041); the second liquid outlet pipeline (104) is communicated with the amine liquid treatment device, and the liquid outlet of the amine liquid treatment device is communicated with the first liquid inlet pipeline (103); It also comprises a gas phase balance pipeline (81), one end of the gas phase balance pipeline (81) is communicated with the top of the semi-rich amine liquid buffer tank (8), and the other end of the gas phase balance pipeline (81) is communicated with the communication pipeline of the gas outlet of the hydrolysis reactor and the second gas inlet pipeline (1021).

2. The natural gas cleaning device according to claim 1, characterized in that The hydrolysis reactor comprises a heat exchanger (4), a preheater (5) and a hydrolysis reaction tank (6); the hydrolysis reaction tank (6) is provided with a hydrolysis catalyst; the top gas outlet of the separator (3) is communicated with the heating gas inlet of the heat exchanger (4), the heating gas outlet of the heat exchanger (4) is communicated with the gas inlet of the preheater (5), the gas outlet of the preheater (5) is communicated with the gas inlet of the hydrolysis reaction tank (6), the gas outlet of the hydrolysis reaction tank (6) is communicated with the cooling gas inlet of the heat exchanger (4), and the cooling gas outlet of the heat exchanger (4) is communicated with the second gas inlet pipeline (1021).

3. The natural gas cleaning device of claim 2, wherein, The hydrolysis reactor further comprises a cooler (7), one end of the cooler (7) is communicated with the cooling gas outlet of the heat exchanger (4), and the other end of the cooler (7) is communicated with the second gas inlet pipeline (1021).

4. The natural gas cleaning device of claim 1, wherein The amine liquid treatment device comprises a flash tank (28), an amine liquid regeneration tower (29), a first lean amine liquid pump (30), an amine liquid buffer tank (31) and a second lean amine liquid pump (32); the second liquid discharge pipeline (104) is communicated with the liquid inlet of the flash tank (28), the liquid outlet of the flash tank (28) is communicated with the liquid inlet at the top of the amine liquid regeneration tower (29), the liquid outlet at the bottom of the amine liquid regeneration tower (29) is communicated with the liquid inlet of the first lean amine liquid pump (30), the liquid outlet of the first lean amine liquid pump (30) is communicated with the liquid inlet of the amine liquid buffer tank (31), the liquid outlet of the amine liquid buffer tank (31) is communicated with the liquid inlet of the second lean amine liquid pump (32), and the liquid outlet of the second lean amine liquid pump (32) is communicated with the first liquid inlet pipeline (103).

5. A natural gas cleaning device according to any one of claims 1-4, characterized in that The top of the semi-rich amine liquid buffer tank (8) is provided with a first safety valve auxiliary line (22); and the top of the separator (3) is provided with a second safety valve auxiliary line (23).

6. The natural gas cleaning device of claim 5, wherein, A first valve group (12) is arranged on the pipeline between the second gas inlet pipeline (1021) and the gas phase balance pipeline (81); a second valve group (13) is arranged on the communication pipeline between the first gas discharge pipeline (1011) and the separator (3); and a second cross-line valve group (10) is arranged on the communication pipeline between the first gas discharge pipeline (1011) and the second gas inlet pipeline (1021). An inlet electric valve (24) is arranged on the communication pipeline between the semi-rich amine liquid buffer tank (8) and the pump (9); an outlet electric valve (25), a first regulating valve (16) and a third valve group (15) are sequentially arranged on the communication pipeline from the pump (9) to the second liquid inlet pipeline (1041); a backflow pipeline (82) is arranged on the pipeline between the outlet electric valve (25) and the first regulating valve (16), the backflow pipeline (82) is communicated with the bottom of the semi-rich amine liquid buffer tank (8), and a backflow valve (17) is arranged on the backflow pipeline (82); a fourth valve group (14) is arranged on the communication pipeline between the first liquid discharge pipeline (1031) and the liquid inlet of the semi-rich amine liquid buffer tank (8); a fifth valve group (26) is arranged on the gas phase balance pipeline (81); and a first cross-line valve group (11) is arranged on the pipeline between the first liquid discharge pipeline (1031) and the second liquid inlet pipeline (1041).

7. The natural gas cleaning device of claim 6, wherein A first sampling port (18) is arranged on the communication pipeline between the gas inlet of the heat exchanger (4) and the gas outlet of the top of the separator (3); and a second sampling port (19) is arranged on the communication pipeline between the hydrolysis reactor and the gas phase balance pipeline (81).

8. A method of on-line commissioning of a natural gas treatment plant according to any one of claims 1-7, characterized in that, Before the online operation starts and before the online operation is completed, the natural gas raw material enters the first absorption tower (1) from the first gas inlet pipeline (101) and is in countercurrent contact with the amine liquid in the first absorption tower (1), and then the gas is discharged from the top of the first absorption tower (1) and enters the second absorption tower (2) through the second cross pipeline valve group (10), and after the gas is in countercurrent contact with the amine liquid in the second absorption tower (2), the gas is discharged from the top of the second absorption tower (2); at the same time, the amine liquid enters the top of the second absorption tower (2) from the first liquid inlet pipeline (103), and then the amine liquid is discharged from the bottom of the second absorption tower (2) and enters the top of the first absorption tower (1) through the first cross pipeline valve group (11), and then the amine liquid is discharged from the second liquid discharge pipeline (104), and after the discharged amine liquid is treated in the amine liquid treatment device, it is returned to the first liquid inlet pipeline (103); The method comprises the following steps: Step 1, operation preparation is performed; Step 2, amine liquid process conversion operation is performed; Step 21, the third valve group (15) is slightly opened, the pipeline between the first regulating valve (16) and the third valve group (15) is filled with liquid, the third valve group (15) is fully opened after the liquid filling is completed; then, the fourth valve group (14) is slightly opened to slowly fill the semi-rich amine liquid buffer tank (8) with liquid, when the liquid level of the semi-rich amine liquid buffer tank (8) rises to 40%-60%, the fifth valve group (26) and the inlet electric valve (24) are opened to tank pump the pump (9), after the tank pumping is completed, the pump (9) is started, the outlet electric valve (25) is slightly opened to fill the communication pipeline between the first regulating valve (16) and the pump (9) with liquid, after the liquid filling is completed, the outlet electric valve (25) is fully opened, and the reflux valve (17) is opened to return the amine liquid; then the first regulating valve (16) is opened to fill the top of the first absorption tower (1) with liquid; Step 22, the fourth valve group (14) is fully opened and the first cross pipeline valve group (11) is fully closed; then the first regulating valve (16) is adjusted and the reflux valve (17) is fully closed, and the liquid level in the semi-rich amine liquid buffer tank (8) is controlled at 40%-60%; the amine liquid process conversion operation is completed; Step 3, natural gas process conversion operation: the preheater is preheated in advance, the second valve group (13) is fully opened, and then the second cross pipeline valve group (10) is fully closed and the first valve group (12) is fully opened, and the natural gas hot process conversion operation is completed.

9. The method of claim 8, wherein the natural gas purification plant is an ammonia plant. The step 1 commissioning operation includes: slowly opening the first safety valve sub-line (22) to release the pressure of the connecting pipeline of the semi-rich amine liquid buffer tank (8) to the high-pressure flare, then closing the first safety valve sub-line (22); or / and, closing the first valve group (12), slowly opening the second valve group (13), using the natural gas discharged from the top of the first absorption tower (1) to pressurize the gas flow pipeline to 0.5-1 MPa, then opening the second safety valve sub-line (23) to release the pressure to the high-pressure flare, repeating the operation more than 3 times, then opening the first sampling port (18) and the second sampling port (19) to take samples respectively, when the methane content in the sampling is not less than 96 mol%, the natural gas replacement is qualified, then continuing to pressurize the gas flow pipeline with the natural gas discharged from the top of the first absorption tower (1) to balance the pressure with the second absorption tower (2), and closing the second valve group (13).

10. The method of claim 8 or 9, wherein the natural gas purification apparatus is an ammonia plant. The concentration of hydrogen sulfide in the natural gas raw material ranges from 5 to 6 mol%; the concentration of carbonyl sulfide in the natural gas raw material ranges from 100 to 200 mg / Nm 3 ; the mass concentration of the amine solution is 38% to 50%; after being put into operation, the natural gas flow discharged by the first gas inlet pipeline (101) is 4 to 13.75 x 10 4 Nm 3 / h; and the amine solution flow discharged by the pump (9) is 160 to 200 t / h.

Images