Methanol-to-olefin reaction gas washing tower system

Abstract

The utility model provides a methanol-to-olefin reaction gas washing tower system, belongs to the technical field of methanol-to-olefin, and solves the problems of poor effect, high cost, poor operation effect, high investment cost, difficulty in operation and high labor intensity when a reagent is added to relieve blockage in the prior art. The device comprises a washing tower, the bottom of the washing tower is connected with a sewage pool, a pipeline at the bottom of the washing tower is connected with a deoxygenated water inlet pipe a, the deoxygenated water inlet pipe a is provided with a water pressure sensor a and an electromagnetic valve a, and the pipeline at the bottom of the washing tower is provided with an electromagnetic valve b and a flow sensor a. The method comprises the following steps: introducing a catalyst settled at the bottom of a washing tower into a sewage pool so as to relieve the problem of system blockage, when the catalyst blocks a pipeline inlet at the bottom of the tower, closing an electromagnetic valve b, cutting off a pipeline of the sewage pool, opening an electromagnetic valve a on a deoxygenated water inlet pipe a, and backflushing the pipeline inlet at the bottom of the tower by deoxygenated water, the catalyst can continuously flow into the sewage pool, the operation is simple, and the investment cost is low.

Description

Technical Field

[0001] The utility model belongs to the technical field of methanol to olefins, in particular to a methanol to olefins reaction gas washing tower system. Background Art

[0002] Methanol-to-olefins (MTO) plants use methanol as a raw material. By controlling appropriate reaction conditions and using specialized catalysts, the methanol is reacted to produce a reaction gas rich in light olefins. The main products are ethylene and propylene. This gas is then washed through a subsequent quench tower and a water scrubber before entering the reaction gas compressor. The quench tower and water scrubber systems in a MTO plant are responsible for scrubbing small amounts of catalyst entrained in the reaction gas, condensing moisture, and removing impurities.

[0003] The high-temperature reaction gas from the reactor is heat exchanged in the methanol-reaction gas heat exchanger. After heat recovery, the ethylene- and propylene-rich reaction gas enters the lower part of the quench tower. The reaction gas contacts the cooling water at the top of the quench tower from bottom to top, washing away the small amount of catalyst carried in the reaction gas and reducing the reaction gas temperature. The quenched reaction gas enters the lower part of the water scrubber from the top of the quench tower. The reaction gas contacts the washing water from bottom to top, reducing the reaction gas temperature. Finally, the reaction gas enters the compressor of the olefin separation unit for compression and separation.

[0004] At present, the water system of methanol to olefins plants uses a quench tower and a water washing tower. The washed catalyst cannot be completely removed in the water, resulting in the water pump filter screen being unusable and easily damaging the pump seal. In addition, the catalyst carried in the water clogs the heat exchanger and the tower plate, resulting in poor overall equipment operation, high equipment and facility maintenance and repair costs, high energy consumption, and high operating costs. At this stage, methanol to olefins plants generally add reagents to the water system to alleviate the blockage problem, but the effect is poor and the cost is expensive. The overall operation of the water system of methanol to olefins plants is poor, the investment cost is high, the operation is difficult, and the labor intensity is high. Utility Model Content

[0005] In response to the above problems, the purpose of the present invention is to provide a methanol to olefins reaction gas washing tower system, which introduces the catalyst settled at the bottom of the washing tower into a sewage pool to alleviate the problem of system blockage. When the catalyst blocks the pipe inlet at the bottom of the tower, the solenoid valve b is closed to cut off the pipe to the sewage pool, and then the solenoid valve a on the deoxygenated water inlet pipe a is opened. The deoxygenated water backflushes the pipe inlet at the bottom of the tower to ensure that the catalyst can continuously flow into the sewage pool. The operation is simple and the investment cost is low.

[0006] The technical solutions adopted in this utility model are as follows:

[0007] A methanol to olefins reaction gas scrubbing tower system comprises a scrubbing tower, wherein the bottom of the scrubbing tower is connected to a sewage tank via a pipeline, the pipeline at the bottom of the scrubbing tower is connected to a deoxygenated water inlet pipe a, the deoxygenated water inlet pipe a is provided with a water pressure sensor a and a solenoid valve a, and the pipeline at the bottom of the scrubbing tower is provided with a solenoid valve b and a flow sensor a located between the deoxygenated water inlet pipe a and the sewage tank.

[0008] Preferably, the washing tower includes an outer shell, a tower sedimentation zone is provided in the outer shell, a tower sieve hole tower tray is provided on one side of the tower sedimentation zone, and a tower bottom overflow tower tray, a tower bottom double overflow tower tray, a tower bottom sieve hole tower tray, a tower bottom grid and a tower bottom sedimentation zone are sequentially provided below the tower sieve hole tower tray.

[0009] Preferably, a bottom extraction port is provided between the bottom sieve tray and the bottom grid, the bottom extraction port is connected to a bottom pump via a pipeline, and the bottom pump is connected to a bottom heat exchanger communicated with the washing tower via a pipeline.

[0010] Preferably, the bottom extraction outlet is connected to the deoxygenated water inlet pipe a through a pipe, and a water pressure sensor b and a solenoid valve c are provided in the pipe connecting the bottom extraction outlet and the deoxygenated water inlet pipe a, and a flow sensor b and a solenoid valve d are provided in the pipe connecting the bottom extraction outlet and the bottom pump.

[0011] Preferably, there are at least two tower bottom extraction outlets, and each tower bottom extraction outlet is connected to the same tower bottom pump through a pipeline.

[0012] Preferably, a tower extraction port is provided in the settling zone in the tower, the tower extraction port is connected to the tower pump through a pipeline, the tower pump is connected to the tower heat exchanger through a pipeline, and the tower heat exchanger is connected to a cooler communicated with the washing tower through a pipeline.

[0013] Preferably, the cooler is connected to a spray head arranged in the sewage tank through a pipeline.

[0014] Preferably, the bottom of the sedimentation zone in the tower is connected to the sewage pool through a pipe, the pipe between the sedimentation zone in the tower and the sewage pool is connected to the deoxygenated water inlet pipe b, the deoxygenated water inlet pipe b is provided with a water pressure sensor c and a solenoid valve e, the pipe between the sedimentation zone in the tower and the sewage pool is provided with a flow sensor c and a solenoid valve f, the flow sensor c and the solenoid valve f are located between the deoxygenated water inlet pipe b and the sewage pool.

[0015] Preferably, a liquid level sensor a is provided on the shell and is located below the sedimentation area in the tower, and a liquid level sensor b is provided on the sedimentation area in the tower.

[0016] Preferably, the tower bottom grid is provided with at least two layers, and the aperture of the tower bottom grid located at the upper layer is larger than the aperture of the tower bottom grid located at the lower layer.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] The catalyst settled at the bottom of the washing tower is introduced into the sewage pool to alleviate the problem of system blockage. When the catalyst blocks the pipe inlet at the bottom of the tower, the solenoid valve b is closed to cut off the pipe to the sewage pool, and then the solenoid valve a on the deoxygenated water inlet pipe a is opened. The deoxygenated water backflushes the pipe inlet at the bottom of the tower to ensure that the catalyst can continuously flow into the sewage pool. The operation is simple and the investment cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A schematic diagram of a process flow provided for an embodiment of the present utility model;

[0021] Figure 2 This is a schematic diagram of the structure of a washing tower provided in an embodiment of the utility model.

[0022] Reference numerals: 1-wash tower; 101-extraction port in the tower; 102-mesh tray in the tower; 103-sedimentation zone in the tower; 104-overflow tray in the tower bottom; 105-mesh tray at the bottom; 106-extraction port at the bottom; 107-sedimentation zone at the bottom; 108-double overflow tray at the bottom; 109-grid at the bottom; 2-bottom pump; 3-heat exchanger at the bottom; 4-pump in the tower; 5-heat exchanger in the tower; 6-cooler; 7-sewage tank; 8-sewage pump; 9-reaction gas inlet pipe; 10 -Reaction gas outlet pipe; 11-Deoxygenated water inlet pipe a; 12-Spray head; 13-Liquid level sensor a; 14-Water pressure sensor b; 15-Water pressure sensor a; 16-Solenoid valve a; 17-Solenoid valve c; 18-Flow sensor b; 19-Solenoid valve d; 20-Flow sensor a; 21-Solenoid valve b; 22-Liquid level sensor b; 23-Flow sensor c; 24-Solenoid valve f; 25-Water pressure sensor c; 26-Solenoid valve e; 27-Deoxygenated water inlet pipe b. DETAILED DESCRIPTION

[0023] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0026] The following combination Figure 1 and Figure 2 The utility model is described in detail.

[0027] Example

[0028] A methanol-to-olefins reaction gas scrubber system includes a scrubber 1. The bottom of the scrubber 1 is connected to a sewage tank 7 via a pipeline. The pipeline at the bottom of the scrubber 1 is connected to a deoxygenated water inlet pipe a11, which is equipped with a water pressure sensor a15 and a solenoid valve a16. The pipeline at the bottom of the scrubber 1 is also equipped with a solenoid valve b21 and a flow sensor a20, located between the deoxygenated water inlet pipe a11 and the sewage tank 7. The middle of the scrubber 1 is connected to a reaction gas inlet pipe 9, and the top of the scrubber 1 is connected to a reaction gas outlet pipe 10. The sewage tank 7 is connected to a sewage pump 8, which pumps sewage to a water treatment unit for subsequent treatment.

[0029] Reactant gas enters scrubber 1 through reactant gas inlet pipe 9. Washing water washes the catalyst from the reactant gas and cools it. The catalyst then flows to the bottom of scrubber 1 along with the washing water. The catalyst that settles at the bottom of scrubber 1 is then directed to sewage tank 7 to alleviate system blockage. When scrubber 1 is operating normally and flow sensor a20 detects that the water flow from the bottom of the scrubber to sewage tank 7 has dropped to 50-60% of normal, indicating that catalyst has blocked the inlet pipe at the bottom of the scrubber, solenoid valve b21 is closed, shutting off the pipe to sewage tank 7. Then, solenoid valve a16 on deoxygenated water inlet pipe a11 is opened, allowing deoxygenated water to backflush the inlet pipe at the bottom of the scrubber, ensuring the pipe is unobstructed and allowing the catalyst to flow smoothly into sewage tank 7. When water pressure sensor a15 detects that the pressure in deoxygenated water inlet pipe a11 is dropping too quickly (i.e., the pressure has been flushed and cleared), solenoid valve b21 is opened and solenoid valve a16 is closed, resuming the catalyst delivery operation.

[0030] The scrubbing tower 1 includes a shell, within which is disposed a mid-tower settling zone 103. A mid-tower sieve tray 102 is disposed on one side of the settling zone 103. Below the sieve tray 102 are sequentially disposed a mid-tower overflow tray 104, a double-overflow tray 108, a bottom sieve tray 105, a bottom grid 109, and a bottom settling zone 107. The bottom settling zone 107 is connected to the sewage tank 7 via a pipeline. The settling zone 107 has a settling height of 5 to 15 meters, while the settling zone 103 has a settling height of 1 to 5 meters. The sieve trays 102 are arranged in two layers.

[0031] The washing tower 1 can be provided with 20 to 40 layers of tower trays, and the lower part of the washing tower 1 can be provided with 15 to 25 layers of sieve tower trays, which can ensure that the tower trays are not blocked, reduce wear and adhesion, and extend the tower operation cycle; the upper part of the washing tower 1 can be provided with 5 to 15 layers of float valve tower trays, which can ensure efficient separation of the tower and great operational flexibility.

[0032] A bottom extraction port 106 is provided between the sieve tray 105 and the bottom grid 109 at the bottom of the tower. This port is connected via a pipeline to a bottom pump 2, which in turn is connected via a pipeline to a bottom heat exchanger 3, which is in communication with the scrubber 1. The water temperature at the bottom of the tower is relatively high, allowing it to directly preheat the methanol feedstock for the methanol-to-olefins unit. Since the feedstock methanol is generally at room temperature when it arrives at the unit from the tank farm, preheating the methanol at the bottom heat exchanger 3 reduces energy consumption and lowers production and operating costs.

[0033] The tower bottom extraction port 106 is connected to the deoxygenated water inlet pipe a11 via a pipe. A water pressure sensor b14 and a solenoid valve c17 are installed in the pipe connecting the tower bottom extraction port 106 to the deoxygenated water inlet pipe a11. A flow sensor b18 and a solenoid valve d19 are installed in the pipe connecting the tower bottom extraction port 106 to the tower bottom pump 2. There are at least two tower bottom extraction ports 106, each connected to the same tower bottom pump 2 via a pipe. Two to four tower bottom extraction ports 106 can be provided.

[0034] When the washing tower 1 is operating normally and the flow sensor b18 monitors that the inlet flow of the tower bottom pump 2 drops to 60-80% of the normal value, the solenoid valve d19 of the other pipeline is opened. When the flow reaches 100% of the normal value, the original solenoid valve d19 is closed and the original solenoid valve c17 is opened for backwashing. When the water pressure sensor b14 detects that the pressure of the deoxygenated water inlet pipe a11 drops too fast (that is, it has been flushed and unobstructed), the solenoid valve c17 is closed. At this time, this pipeline is standby, with high operational flexibility and low labor intensity.

[0035] A tower extraction port 101 is provided in the tower settling zone 103. This port is connected to a tower pump 4 via a pipeline, which in turn is connected to a tower heat exchanger 5 via a pipeline. This heat exchanger 5 is connected to a cooler 6, which is in communication with the scrubbing tower 1, via a pipeline. One or two tower extraction ports 101 may be provided. The water temperature in the tower is moderate, and the tower heat exchanger 5 can directly serve as the reboiler for each olefin separation tower, achieving significant efficiency, low energy consumption, and low production and operating costs. Cooler 6 can be a circulating water cooler or an air cooler, with the appropriate cooling method selected based on local conditions and costs.

[0036] The extraction outlet 101 in the tower and the extraction outlet 106 at the bottom of the tower are of umbrella cap type, and the umbrella cap can be provided with a filter screen.

[0037] The cooler 6 is connected to a spray head 12 set in the sewage pool 7 through a pipe. Because the water temperature at the bottom of the tower is high, the water discharged into the sewage pool 7 will produce gas. The low-temperature water cooled by the cooler 6 is used to spray the sewage pool 7 to prevent the gas from entering the atmosphere, which has a good environmental protection effect and is more environmentally friendly.

[0038] The bottom of the settling area 103 in the tower is connected to the sewage tank 7 via a pipe. A deoxygenated water inlet pipe b27 is connected to the pipe between the settling area 103 and the sewage tank 7. A water pressure sensor c25 and a solenoid valve e26 are installed in the pipe between the settling area 103 and the sewage tank 7. A flow sensor c23 and a solenoid valve f24 are also installed in the pipe between the settling area 103 and the sewage tank 7. The flow sensor c23 and the solenoid valve f24 are located between the deoxygenated water inlet pipe b27 and the sewage tank 7. When the scrubber 1 is operating normally and the flow sensor c23 detects that the water flow from the settling area 103 to the sewage tank 7 has dropped to 50-60% of the normal value, the solenoid valve f24 is closed and the solenoid valve e26 is opened for backwashing. When the water pressure sensor c25 detects that the pressure in the deoxygenated water inlet pipe b27 is dropping too fast (i.e., the flushing is clear), the solenoid valve f24 is opened and the solenoid valve e26 is closed, and sewage transportation begins. Deoxygenated water can be used for backwashing when the scrubber 1 fails, and can be used to fill the scrubber during startup and shutdown, making operation more flexible, easy to control, and less labor-intensive. The deoxygenated water inlet pipe b27 can share a pipe with the deoxygenated water inlet pipe a11.

[0039] The outer shell is equipped with a liquid level sensor a13 located below the tower settling zone 103, and a liquid level sensor b22 is installed above the tower settling zone 103. Liquid level sensor a13 monitors the liquid level in the tower bottom settling zone 107, while liquid level sensor b22 monitors the liquid level in the tower settling zone 103 to ensure that the liquid level meets production requirements.

[0040] The tower bottom grid 109 is provided with at least two layers, and the aperture of the tower bottom grid 109 located at the top is larger than the aperture of the tower bottom grid 109 located at the bottom. The two layers of tower bottom grid 109 at the bottom of the scrubbing tower 1 are used as baffles to buffer the fluctuations of the catalyst after entering the bottom, which is beneficial for the catalyst to settle, and the effect is obvious.

[0041] A PLC controller can be set up to connect the flow sensor, water pressure sensor and solenoid valve, and automatically control the opening and closing of the relevant solenoid valves according to the sensor signals to achieve automated operation.

[0042] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A methanol to olefins reaction gas scrubbing tower system, comprising a scrubbing tower (1), characterized in that: The bottom of the washing tower (1) is connected to a sewage tank (7) via a pipeline. The pipeline at the bottom of the washing tower (1) is connected to a deoxygenated water inlet pipe a (11). A water pressure sensor a (15) and a solenoid valve a (16) are provided on the deoxygenated water inlet pipe a (11). The pipeline at the bottom of the washing tower (1) is provided with a solenoid valve b (21) and a flow sensor a (20) located between the deoxygenated water inlet pipe a (11) and the sewage tank (7).

2. A methanol to olefins reaction gas scrubbing tower system according to claim 1, characterized in that: The washing tower (1) comprises an outer shell, wherein a tower sedimentation zone (103) is provided in the outer shell, a tower sieve tray (102) is provided on one side of the tower sedimentation zone (103), and a tower bottom overflow tray (104), a tower bottom double overflow tray (108), a tower bottom sieve tray (105), a tower bottom grid (109) and a tower bottom sedimentation zone (107) are sequentially provided below the tower sieve tray (102).

3. A methanol to olefins reaction gas scrubbing tower system according to claim 2, characterized in that: A tower bottom extraction port (106) is provided between the tower bottom sieve tray (105) and the tower bottom grid (109); the tower bottom extraction port (106) is connected to a tower bottom pump (2) via a pipeline; and the tower bottom pump (2) is connected to a tower bottom heat exchanger (3) communicating with the washing tower (1) via a pipeline.

4. A methanol to olefins reaction gas scrubbing tower system according to claim 3, characterized in that: The tower bottom extraction outlet (106) is communicated with the deoxygenated water inlet pipe a (11) through a pipeline, and a water pressure sensor b (14) and a solenoid valve c (17) are provided in the pipeline connecting the tower bottom extraction outlet (106) and the deoxygenated water inlet pipe a (11), and a flow sensor b (18) and a solenoid valve d (19) are provided in the pipeline connecting the tower bottom extraction outlet (106) and the tower bottom pump (2).

5. A methanol to olefins reaction gas scrubbing tower system according to claim 4, characterized in that: At least two tower bottom extraction ports (106) are provided, and each tower bottom extraction port (106) is connected to the same tower bottom pump (2) via a pipeline.

6. The methanol to olefins reaction gas scrubbing tower system according to claim 2, characterized in that: The tower settling zone (103) is provided with a tower extraction port (101), the tower extraction port (101) is connected to a tower pump (4) via a pipeline, the tower pump (4) is connected to a tower heat exchanger (5) via a pipeline, and the tower heat exchanger (5) is connected to a cooler (6) in communication with the washing tower (1) via a pipeline.

7. The methanol to olefins reaction gas scrubbing tower system according to claim 6, characterized in that: The cooler (6) is connected to a spray head (12) arranged in a sewage tank (7) via a pipeline.

8. The methanol to olefins reaction gas scrubbing tower system according to claim 2, characterized in that: The bottom of the sedimentation zone (103) in the tower is connected to the sewage pool (7) through a pipeline. The pipeline between the sedimentation zone (103) in the tower and the sewage pool (7) is connected to a deoxygenated water inlet pipe b (27). A water pressure sensor c (25) and a solenoid valve e (26) are provided in the deoxygenated water inlet pipe b (27). A flow sensor c (23) and a solenoid valve f (24) are provided on the pipeline between the sedimentation zone (103) in the tower and the sewage pool (7). The flow sensor c (23) and the solenoid valve f (24) are located between the deoxygenated water inlet pipe b (27) and the sewage pool (7).

9. The methanol to olefins reaction gas scrubbing tower system according to claim 2, characterized in that: The shell is provided with a liquid level sensor a (13) located below the sedimentation zone (103) in the tower, and the sedimentation zone (103) in the tower is provided with a liquid level sensor b (22).

10. The methanol to olefins reaction gas scrubbing tower system according to claim 2, characterized in that: The tower bottom grid (109) is provided with at least two layers, and the aperture of the tower bottom grid (109) located at the upper side is larger than the aperture of the tower bottom grid (109) located at the lower side.

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