A desulfurization tank, coal-to-natural gas purification and desulfurization system, and desulfurization method

Abstract

The present invention relates to a desulfurization tank, which includes a shell, an air intake hopper and a venturi tube. The upper part of the shell is inverted with an air intake hopper connected to an external air inlet, and a plurality of venturi tubes are arranged under the air intake hopper. The inlet section, contraction section, throat and diffusion section of the venturi tube are arranged vertically in sequence from top to bottom, and a suction pipe pointing to the vertical inner wall of the shell is arranged horizontally on the throat; an air outlet pipe is arranged on the shell. The beneficial effects of the present invention are: under the continuous action of high-pressure purified gas, the purified gas and the catalyst can be mixed evenly under the action of the venturi tube, thereby improving the desulfurization efficiency. At the same time, the kinetic energy of the original high-pressure purified gas is used to achieve the stirring of the purified gas and the catalyst, without the need for a built-in mechanical stirring device, with high resource utilization and good economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-to-natural gas production, and in particular to a desulfurization tank and a coal-to-natural gas purification and desulfurization system and a desulfurization method. Background Art

[0002] The methanogenic synthesis of coal-to-natural gas uses nickel-based methanogenic catalysts. The characteristics of nickel-based methanogenic catalysts determine that they are very sensitive to sulfur in the purified gas. Very low amounts of sulfur (ppb level) will cause sulfur poisoning of the nickel-based methanogenic catalyst. In order to ensure the safe operation of the nickel-based methanogenic catalyst, a desulfurization system is generally set up in front of the methanogenic reactor to remove sulfur from the purified gas.

[0003] The desulfurization tank of the existing desulfurization system is filled with zinc oxide desulfurizer, which can only remove hydrogen sulfide and carbonyl sulfide in the purified gas, but cannot remove organic sulfur such as thiophene sulfur, mercaptans, sulfides, etc. that may exist in the purified gas, and will still cause poisoning of the nickel-based methanation catalyst.

[0004] When the desulfurization tank is in use, the zinc oxide desulfurizer filled inside is axially distributed into three zones. The upper layer is the saturated zone, which is basically saturated with zinc sulfide. The middle layer is the working zone, also called the mass transfer zone. This zone is the main reaction zone and reacts rapidly. The outlet end of the lower layer is divided into a spare zone, and the interior is still filled with fresh zinc oxide desulfurizer. In actual use, due to uneven loading of the desulfurizer, the temperature, pressure, gas composition concentration and gas flow rate outside the zinc oxide in each zone inside the desulfurization tank are very unstable, resulting in low desulfurization efficiency.

[0005] CN220496003 discloses a two-stage natural gas desulfurization device, which uses a mechanical stirring structure to achieve mixing. However, there are the following problems: the mechanical stirring structure needs to be driven by an electric motor. On the one hand, the stirring blades are easily worn out. On the other hand, the long-term operation of the motor consumes a lot of electricity and has low economic benefits. Summary of the invention

[0006] The purpose of the present invention is to provide a desulfurization tank and a coal-to-natural gas purification and desulfurization system and a desulfurization method to solve the above-mentioned problems existing in the prior art.

[0007] The technical solution of the present invention to solve the above technical problems is as follows:

[0008] A desulfurization tank comprises an outer shell, an air intake hopper and a venturi tube. An air intake hopper connected to an external air inlet is inverted on the upper part of the outer shell, and a plurality of venturi tubes are arranged below the air intake hopper. The inlet section, contraction section, throat and diffusion section of the venturi tube are arranged vertically in sequence from top to bottom, and a suction tube pointing to the vertical inner wall of the outer shell is horizontally connected on the throat; an air outlet pipe is arranged on the outer shell.

[0009] The beneficial effects of the present invention are as follows: under the continuous action of high-pressure purified gas, the purified gas and the catalyst can be evenly mixed under the action of the venturi tube, thereby improving the desulfurization efficiency. At the same time, the kinetic energy of the original high-pressure purified gas is utilized to achieve stirring of the purified gas and the catalyst, without the need for a built-in mechanical stirring device, thereby achieving high resource utilization and good economic benefits.

[0010] Based on the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, it also includes a first gas gathering hopper, the upper part of which is sealed with the lower opening of the gas inlet hopper, a first sealing ring for sealing the gap between adjacent inlet sections is arranged at the bottom of the first gas gathering hopper, and a cone cap is arranged in the middle of the first sealing ring.

[0012] The above further beneficial effects are: the high-pressure purifier is diverted to the inlet sections of multiple venturi tubes through the first gas collecting hopper and the cone cap; the first gas collecting hopper and the inlet section are sealed and connected to avoid the gas loss of the high-pressure purified gas.

[0013] Another technical solution of the present invention is as follows:

[0014] A coal-to-natural gas purification and desulfurization system comprises a purified gas heat exchanger, a purified gas separation tank and two desulfurization tanks connected in sequence, wherein the two desulfurization tanks are respectively filled with a zinc oxide desulfurizer and a reduced copper-based desulfurizer.

[0015] Zinc oxide desulfurizer removes hydrogen sulfide and carbonyl sulfide in the purified gas, and reduced copper-based desulfurizer removes thiophene sulfur, mercaptans, sulfides and other organic sulfur in the purified gas.

[0016] Another technical solution of the present invention is as follows:

[0017] A method for purifying and desulfurizing coal-to-natural gas adopts the coal-to-natural gas purification and desulfurization system as mentioned above. The purified gas from the purification device is heated by a purified gas heat exchanger, supplemented with boiler water, and then enters a purified gas separation tank for gas-liquid separation. The purified gas at the outlet of the purified gas separation tank enters a desulfurization tank for desulfurization, and the desulfurized purified gas enters a methanation reactor for reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic structural diagram of a coal-to-natural gas purification and desulfurization system of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of a desulfurization tank of the present invention;

[0020] Figure 3 A cross-sectional view of a desulfurization tank of the present invention;

[0021] Figure 4 The internal structure of a desulfurization tank of the present invention is shown in FIG. Figure 1 ;

[0022] Figure 5 The internal structure of a desulfurization tank of the present invention is shown in FIG. Figure 2 ;

[0023] Figure 6 The figure is a schematic diagram of the diffusion bucket structure of a desulfurization tank of the present invention.

[0024] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0025] 1. Clean gas inlet cut-off valve; 2. Clean gas heat exchanger; 3. Clean gas separation tank; 4. Desulfurization tank; 41. Shell; 42. Air inlet hopper; 43. First gas collecting hopper; 431. First sealing ring; 432. Cone cap; 44. Venturi tube; 441. Inlet section; 442. Contraction section; 443. Throat; 444. Diffusion section; 445. Suction pipe; 45. Second gas collecting hopper; 451. Second sealing ring; 452. Vertical pipe; 4 6. Diffusion hopper; 47. Exhaust pipe; 5. Desulfurization tank outlet shut-off valve; 6. Desulfurization tank outlet flare valve; 7. Inlet temperature sensor; 8. Inlet pressure sensor; 9. Desulfurization tank bed thermocouple; 10. First outlet temperature sensor; 11. Second outlet temperature sensor; 12. Third outlet temperature sensor; 13. Desulfurization tank bed pressure difference sensor; 14. First sampling point; 15. Second sampling point; 16. Third sampling point. DETAILED DESCRIPTION

[0026] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0027] Example 1

[0028] like Figures 2 to 6 As shown, a desulfurization tank, the desulfurization tank 4 includes an outer shell 41, an air inlet hopper 42 and a venturi tube 44, the upper part of the outer shell 41 is invertedly provided with an air inlet hopper 42 which is connected to an external air inlet, and a plurality of venturi tubes 44 are arranged under the air inlet hopper 42, the inlet section 441, the contraction section 442, the throat 443 and the diffusion section 444 of the venturi tube 44 are arranged vertically in sequence from top to bottom, and the throat 443 is horizontally connected with a suction pipe 445 pointing to the vertical inner wall of the outer shell 41; the outer shell 41 is provided with an air outlet pipe 47.

[0029] The powdered catalyst is directly filled into the shell 41, and the high-pressure purified gas is blown into the inlet section 441 of the venturi tube 44 through the air inlet hopper 42. When passing through the contraction section 442, the flow rate is accelerated. When the high-pressure purified gas passes through the throat 443, the gas-powder mixture of the catalyst and the purified gas outside the throat 443 is sucked in from the suction pipe 445 and sprayed out at the outlet of the diffusion section 444. Under the continuous action of the high-pressure purified gas, the purified gas and the catalyst can be evenly mixed under the action of the venturi tube 44, thereby improving the desulfurization efficiency. At the same time, the kinetic energy of the original high-pressure purified gas is used to achieve the stirring of the purified gas and the catalyst, without the need for a built-in mechanical stirring device, with high resource utilization and good economic benefits. In specific implementation,

[0030] Example 2

[0031] like Figures 2 to 6 As shown, this embodiment is a further improvement on the basis of embodiment 1, and the details are as follows:

[0032] It also includes a first gas gathering hopper 43, the upper part of which is sealedly connected to the lower opening of the gas inlet hopper 42, and a first sealing ring 431 is provided at the bottom of the first gas gathering hopper 43 to seal the gap between adjacent inlet sections 441, and a cone cap 432 is provided in the middle of the first sealing ring 431. The high-pressure purified gas is diverted to the inlet sections 441 of multiple venturi tubes 44 through the first gas gathering hopper 43 and the cone cap 432; the first gas gathering hopper 43 and the inlet section 441 are sealedly connected to avoid the loss of the high-pressure purified gas.

[0033] Example 3

[0034] like Figures 2 to 6 As shown, this embodiment is a further improvement on the basis of embodiment 2, and the details are as follows:

[0035] It also includes a second gas gathering hopper 45, which is arranged outside the diffusion section 444 with a lower opening gathered toward the middle, and an upper opening of the second gas gathering hopper 45 is arranged with a second sealing ring 451 that seals the gap between adjacent diffusion sections 444, and a vertical pipe 452 fixedly connected to the inner side of the diffusion section 444 is arranged in the middle of the second sealing ring 451, and a diffusion hopper 46 is sealedly connected to the vertical pipe 452. The purified gas of the diffusion section 444 and the gas-powder mixture of the catalyst are gathered into the diffusion hopper 46 through the second gas gathering hopper 45, and rise along the diffusion hopper 46 to the vicinity of the suction pipe 445, and the pneumatic stirring process of the venturi tube 44 is repeated.

[0036] The gas outlet pipe 47 is disposed at the upper portion of the housing 41. The purified gas whose mass is reduced after desulfurization is discharged from the gas outlet pipe 47.

[0037] Example 4

[0038] like Figure 1As shown, a coal-to-natural gas purification and desulfurization system includes a purified gas heat exchanger 2, a purified gas separation tank 3 and two of the above-mentioned desulfurization tanks 4 connected in sequence, and the two desulfurization tanks 4 are respectively filled with a zinc oxide desulfurizer and a reduced copper-based desulfurizer. The zinc oxide desulfurizer removes hydrogen sulfide and carbonyl sulfide in the purified gas, and the reduced copper-based desulfurizer removes organic sulfur such as thiophene sulfur, mercaptan, and sulfide in the purified gas. In specific implementation, the zinc oxide content in the zinc oxide desulfurizer is 90%, the copper oxide content in the reduced copper-based desulfurizer is 5-15%, the total sulfur content in the purified gas before desulfurization is less than 110ppb, and the sulfur content in the purified gas after desulfurization is less than 10ppb.

[0039] Example 5

[0040] like Figure 1 As shown, this embodiment is a further improvement on the basis of embodiment 2, and the details are as follows:

[0041] A purified gas inlet shut-off valve 1 is provided on the upstream pipeline of the purified gas heat exchanger 2; the outlet of the latter desulfurization tank 4 is divided into two paths, one leading to the methanation reactor and the other leading to the flare torch, a desulfurization tank outlet shut-off valve 5 is provided on the upstream pipeline of the methanation reactor, and a desulfurization tank outlet flare torch valve 6 is provided on the upstream pipeline of the flare torch.

[0042] An inlet temperature sensor 7 and an inlet pressure sensor 8 are provided on the air inlet of the upper desulfurization tank 4, and a desulfurization tank bed thermocouple 9 is connected in series in the two desulfurization tanks 4; an outlet temperature sensor is provided on the air outlet of the rear desulfurization tank 4; and multiple sampling points are provided on the two desulfurization tanks 4. The inlet temperature sensor 7 is used to monitor the temperature of the purified gas at the inlet of the desulfurization tank 4, and is provided with a high temperature alarm.

[0043] There are three outlet temperature sensors, namely the first outlet temperature sensor 10, the second outlet temperature sensor 11 and the third outlet temperature sensor 12; the two desulfurization tanks 4 are respectively provided with a first sampling point 14 and a second sampling point 15, and a third sampling point 16 is provided on the outlet pipeline of the latter desulfurization tank 4. Three outlet temperature sensors are provided to monitor the outlet purified gas temperature of the desulfurization tank 4, and a high temperature alarm is provided; three sampling points are provided to compare the desulfurization conditions of the purified gas.

[0044] During specific implementation, the desulfurization tank 4 is set in a protection mode, and the desulfurization tank bed thermocouple 9 is set with a six-out-of-two temperature high interlock. After the interlock, the purified gas inlet shut-off valve 1 and the desulfurization tank outlet shut-off valve 5 are closed; the outlet of the latter desulfurization tank 4 is set with a three-out-of-two temperature high interlock, and the purified gas inlet shut-off valve 1 and the desulfurization tank outlet shut-off valve 5 are closed after the interlock; after the interlock is triggered, the bed temperature of the desulfurization tank 4 continues to rise, and the rising rate is greater than 0.1℃ / min, and the flare valve 6 at the outlet of the desulfurization tank is opened for pressure relief, and the pressure relief rate is 0.02MPa / min, and the pressure is continuously relieved until the outlet pressure of the desulfurization tank 4 is less than 0.3MPa; after the desulfurization tank 4 is depressurized, the low-pressure nitrogen at the inlet of the desulfurization tank 4 is opened to continuously purge the desulfurization tank 4, and the purified gas in the desulfurization tank 4 is purged to a combustible gas content of less than 0.5%.

[0045] A desulfurization tank bed pressure difference sensor 13 is provided between the air inlet of the previous desulfurization tank 4 and the air outlet of the next desulfurization tank 4. It is used to monitor the increase of the bed pressure of the desulfurization tank 4 and is provided with a high pressure difference alarm.

[0046] Example 6

[0047] A method for purifying and desulfurizing coal-to-natural gas, using the coal-to-natural gas purification and desulfurization system as described above, wherein the purified gas from the purification device is heated by the purified gas heat exchanger 2, supplemented with boiler water, and then enters the purified gas separation tank 3 for gas-liquid separation, and the purified gas at the outlet of the purified gas separation tank 3 enters the desulfurization tank 4 for desulfurization, and the purified gas after desulfurization enters the methanation reactor for reaction. Boiler water can hydrolyze organic sulfur, and after gas-liquid separation, it can prevent the liquid in the purifier gas from being carried into the desulfurizer. In specific implementation, the purified gas from the purification device (3.2MPa, 40°C, 3.24*10 5 NM 3 / h) is heated to 1600-180°C by the purified gas heat exchanger 2, and after heat exchange, 130-180kg / h of boiler water is added for hydrolysis of carbonyl sulfide, and then enters the purified gas separation tank 3 for gas-liquid separation. The purified gas (160-180°C) at the outlet of the purified gas separation tank 3 enters the desulfurization tank 4 for desulfurization, and the desulfurized purified gas enters the methanation reactor for reaction.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A desulfurization tank, characterized in that: The desulfurization tank (4) comprises an outer shell (41), an air intake hopper (42) and a venturi tube (44); the upper part of the outer shell (41) is provided with the air intake hopper (42) which is connected to the external air inlet; a plurality of venturi tubes (44) are arranged under the air intake hopper (42); the inlet section (441), the contraction section (442), the throat (443) and the diffusion section (444) of the venturi tube (44) are arranged vertically in sequence from top to bottom; the throat (443) is horizontally connected with a suction pipe (445) pointing to the vertical inner wall of the outer shell (41); and the outer shell (41) is provided with an air outlet pipe (47).

2. The desulfurization tank according to claim 1, characterized in that: It also includes a first gas gathering hopper (43), the upper part of which is sealedly connected to the lower opening of the gas inlet hopper (42), and the bottom of the first gas gathering hopper (43) is provided with a first sealing ring (431) for sealing the gap between adjacent inlet sections (441), and the middle part of the first sealing ring (431) is provided with a cone cap (432).

3. The desulfurization tank according to claim 2, characterized in that: It also includes a second gas gathering hopper (45), the diffusion section (444) is provided with a second gas gathering hopper (45) with a lower opening converging toward the middle, the second gas gathering hopper (45) is provided with a second sealing ring (451) at the upper opening for sealing the gap between adjacent diffusion sections (444), the middle of the second sealing ring (451) is provided with a vertical pipe (452) fixedly connected to the inner side of the diffusion section (444), and the vertical pipe (452) is sealingly connected to the diffusion hopper (46).

4. According to the desulfurization tank of claim 3, the gas outlet pipe (47) is arranged on the upper part of the outer shell (41).

5. A coal-to-natural gas purification and desulfurization system, characterized in that: It comprises a purified gas heat exchanger (2), a purified gas separation tank (3) and two desulfurization tanks (4) as claimed in any one of claims 1 to 4 which are connected in sequence, wherein the two desulfurization tanks (4) are respectively filled with a zinc oxide desulfurizer and a reduced copper-based desulfurizer.

6. The coal-to-natural gas purification and desulfurization system according to claim 5, characterized in that: A purified gas inlet shut-off valve (1) is provided on the upstream pipeline of the purified gas heat exchanger (2); the outlet of the latter desulfurization tank (4) is divided into two paths, one leading to the methanation reactor and the other leading to the flare torch; a desulfurization tank outlet shut-off valve (5) is provided on the upstream pipeline of the methanation reactor, and a desulfurization tank outlet flare torch valve (6) is provided on the upstream pipeline of the flare torch.

7. The coal-to-natural gas purification and desulfurization system according to claim 5, characterized in that: An inlet temperature sensor (7) and an inlet pressure sensor (8) are arranged on the air inlet of the upper desulfurization tank (4), and desulfurization tank bed thermocouples (9) are connected in series in the two desulfurization tanks (4); an outlet temperature sensor is arranged on the air outlet of the rear desulfurization tank (4); and a plurality of sampling points are arranged on the two desulfurization tanks (4).

8. The coal-to-natural gas purification and desulfurization system according to claim 7, characterized in that: There are three outlet temperature sensors, namely a first outlet temperature sensor (10), a second outlet temperature sensor (11) and a third outlet temperature sensor (12); the two desulfurization tanks (4) are respectively provided with a first sampling point (14) and a second sampling point (15), and a third sampling point (16) is provided on the outlet pipeline of the latter desulfurization tank (4).

9. The coal-to-natural gas purification and desulfurization system according to claim 5, characterized in that: A desulfurization tank bed pressure difference sensor (13) is provided between the air inlet of the previous desulfurization tank (4) and the air outlet of the next desulfurization tank (4).

10. A method for purifying and desulfurizing coal-to-natural gas, characterized in that: Using the coal-to-natural gas purification and desulfurization system as described in any one of claims 5 to 9, the purified gas from the purification device is heated by the purified gas heat exchanger (2), supplemented with boiler water, and then enters the purified gas separation tank (3) for gas-liquid separation. The purified gas at the outlet of the purified gas separation tank (3) enters the desulfurization tank (4) for desulfurization, and the desulfurized purified gas enters the methanation reactor for reaction.

Images