Solid-liquid separation device for methanol-to-olefin quenched water

Abstract

The utility model discloses a solid-liquid separation device for methanol-to-olefin quenched water, which comprises a quench tower and is characterized in that the device further comprises a solid-liquid separator, a filter disc is arranged in the solid-liquid separator, circulating water of the quench tower enters the solid-liquid separator from the upper part, is subjected to solid-liquid separation by the filter disc and then enters the solid-liquid separator, and the solid-liquid separation is carried out by the filter disc. Filtrate returns to the quench tower from a filtrate outlet of the solid-liquid separator; the bottom of the solid-liquid separator is provided with a cleaning liquid discharge port and a slag discharge port, and the upper part is provided with a pressurizing port connected with a nitrogen pipe network. According to the device disclosed by the utility model, the solid-liquid separator is additionally arranged on the quenching water circulating return tower line of the quenching tower, and part of circulating water of the quenching tower is filtered and then is purified to return to the tower, so that the accumulation of solid content in the quenching tower is reduced, and the long-period stable operation of the device is maintained.

Description

Technical Field

[0001] This utility model belongs to the field of methanol-to-olefins (MTO) technology, specifically relating to a methanol-to-olefins quench water solid-liquid separation device. Background Technology

[0002] A methanol-to-olefins (MTO) plant typically consists of four main parts: a reactor, a quench tower, a product separation unit, and an olefin recovery unit. The reactor converts methanol into olefins, while the quench tower is a crucial piece of equipment for cooling and washing a high-temperature gas mixture. The high-temperature gas mixture from the reaction products enters the quench tower, where it is cooled and washed by a quenching agent (such as water and alkali). This process lowers the temperature of the gas mixture to meet the requirements of downstream systems and removes catalyst particles and acidic substances from the mixture. The quenched gas mixture then enters the product separation unit, where olefins are separated and sent to the olefin recovery unit for further separation and purification to obtain high-purity olefin products.

[0003] The methanol-to-olefins (MTO) quench tower has a three-stage water circulation reflux loop, primarily used for deheating the product gas, washing catalyst dust, and neutralizing acidic substances. The quench tower operates under extremely harsh conditions for extended periods. Due to process constraints, catalyst (mainly fine catalyst powder) remains in the quench water for extended periods, making complete removal impossible. This leads to the deposition of these solids in trays, pipeline bends, and other areas. Furthermore, the aldehydes and ketones in the product gas readily undergo condensation reactions under alkaline conditions, forming polymers that, in the presence of fine catalyst powder, further clog tray sieves, liquid reflux distribution pipes, and downcomers. This disrupts the tower's operating conditions, hinders circulation, and reduces washing and neutralization effectiveness. Increased catalyst content and acid-base imbalance in the quench water system exacerbate heat exchanger tube corrosion, posing a threat to the safe and stable operation of the MTO unit and severely impacting its long-term stable operation. Summary of the Invention

[0004] The purpose of this invention is to provide a methanol-to-olefins quench water solid-liquid separation device to solve the problem of poor quench tower circulation washing effect. By filtering part of the quench tower circulating water and returning the purified water to the quench tower, the accumulation of solid content in the quench tower is reduced, and the device is maintained for long-term stable operation.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] A methanol-to-olefins quench water solid-liquid separation device includes a quench tower, characterized in that the device further includes a solid-liquid separator containing a filter plate. Circulating water from the quench tower enters the solid-liquid separator from the top, and after solid-liquid separation by the filter plate, the filtrate returns to the quench tower from the filtrate outlet of the solid-liquid separator. The solid-liquid separator is provided with a cleaning liquid outlet and a slag outlet at the bottom, and a pressurization port at the top, connected to a nitrogen pipeline network.

[0007] Furthermore, the solid-liquid separator includes a pressure vessel with a hollow central rotating shaft. A set of circular filter discs are horizontally mounted on the central rotating shaft. The filter discs are vertically stacked at a certain interval with the central rotating shaft as the center to form a filter stack. Below the filter stack, a set of circular cleaning filter discs are horizontally mounted on the central rotating shaft. The central rotating shaft has an opening in the filter stack section, serving as a filtrate discharge manifold connected to the filtrate outlet. The central rotating shaft is driven by a drive motor.

[0008] Furthermore, the filter material on the filter disc and the cleaning filter disc is selected from wire mesh, textile material, sintered metal or porous plate.

[0009] Furthermore, a differential pressure gauge is installed on the solid-liquid separator.

[0010] Furthermore, the circulating water of the quench tower is pumped into the solid-liquid separator by a bottom circulating pump.

[0011] Furthermore, a safety valve is installed on the solid-liquid separator.

[0012] Furthermore, the nitrogen pipeline is connected to the pressurization port of the solid-liquid separator via a pressure reducing valve and a pressure gauge.

[0013] Beneficial Effects: This utility model's methanol-to-olefins quench water solid-liquid separation device utilizes a solid-liquid filtration device added to the return line at the bottom circulation pump outlet of the quench tower. This allows a portion of the quench tower's circulating water to pass through the solid-liquid filtration device before being returned to the tower as purified water, reducing the accumulation of solids within the quench tower and increasing the operability of drainage and slag discharge. This utility model features a high degree of automation, low maintenance costs, and closed-loop slag discharge with no environmental hazards. It effectively improves the long-term operational capability of the quench tower, reduces costs, maintenance costs, and operational risks in the production of ethylene and other products, resulting in significant economic benefits. Attached Figure Description

[0014] Figure 1 is a schematic diagram of the solid-liquid separation device for rapid cooling water in methanol-to-olefins according to this utility model.

[0015] The components include: 1. Quenching tower; 2. Solid-liquid separator; 3. Filter plate; 4. Cleaning filter plate; 5. Drive motor; 6. Circulating pump; 7. Differential pressure gauge; 8. Pressure reducing valve; 9. Pressure gauge; 10. Feed valve; 11. Safety valve; 12. Slag discharge valve; 13. Filtrate valve; and 14. Cleaning liquid valve. Detailed Implementation

[0016] The technical solution of this utility model will be further described in detail below through specific embodiments. However, it should be noted that the following embodiments are only used to describe the content of the invention and do not constitute a limitation on the protection scope of this utility model.

[0017] like Figure 1 As shown, the methanol-to-olefins quench water solid-liquid separation device of this invention includes a quench tower 1 and a solid-liquid separator 2. The circulating water of the quench tower 1 enters the solid-liquid separator 2 from the upper part by the circulating pump 6. After solid-liquid separation, the filtrate returns to the quench tower 1 from the filtrate outlet at the lower part of the solid-liquid separator 2.

[0018] The solid-liquid separator 2 is a centrifugal solid-liquid separation filter, mainly composed of a pressure vessel with a hollow central rotating shaft. Around the central rotating shaft, a set of circular filter discs 3 are vertically stacked at a certain interval on the upper part of the central rotating shaft. The filter discs 3 can be covered with wire mesh, textile material, sintered metal, or perforated plates. The spacing of the filter discs 3 is adjustable. The central rotating shaft and the filter discs 3 form a filter stack and can rotate around the shaft. The central rotating shaft has an opening in the filter stack section, serving as a filtrate discharge manifold connected to the filtrate outlet. Below the filter stack, a set of circular cleaning filter discs 4 are horizontally mounted on the central rotating shaft. The central rotating shaft is connected to an external drive motor 5. Starting the drive motor 5 rotates the filter discs 3, which can remove the filter cake on the filter discs 3.

[0019] The solid-liquid separator 2 is equipped with a cleaning liquid outlet and a slag outlet at the bottom, and a pressurization port at the top, which is connected to a nitrogen pipeline. A pressure reducing valve 8 and a pressure gauge 9 are installed before the pressurization port. The solid-liquid separator 2 is also equipped with a differential pressure gauge 7 and a safety valve 11.

[0020] The function of the filter stack is to achieve solid-liquid separation through filtration. After filtration by filter plate 3, the filtrate flows out of the filtrate outlet through filter plate 3 and the central rotating shaft, and a filter cake is formed on filter plate 3. The function of cleaning filter plate 4 is to drain or filter the remaining feed in the container through the cleaning system, which can minimize the remaining feed in solid-liquid separator 2 after the batch is completed.

[0021] When the solid-liquid separator 2 is pressurized, the filtrate passes through the filter disc 3 and the central rotating shaft, and a filter cake forms on the filter disc 3, achieving solid-liquid separation. After filtration, the remaining feed in the container is filtered through the cleaning filter disc 4 or drained; then the filter cake is washed or dried with appropriately heated gas and discharged through the cleaning liquid outlet. To clean the solid-liquid separator 2, the filter stack is rotated at an appropriate speed, and the filter disc assembly generates centrifugal force, discharging the filter cake. The filter cake can be discharged as a slurry or as a dry material.

[0022] During the operation of the quench tower, the liquid phase circulation of quench water is established through the circulating pump 6, and a portion of the quench water is discharged. The feed valve 10 is opened to control the water inflow, and the filtrate valve 13 is opened to return the quench tower 1. When the differential pressure of the solid-liquid separator 2 exceeds the set value during operation, the feed valve 10 and the filtrate valve 13 are closed, and nitrogen gas after pressure reduction is introduced for pressurization. The cleaning liquid valve 14 is opened, and the remaining material in the solid-liquid separator passes through the cleaning filter plate 4 and is discharged from the cleaning liquid outlet. After the liquid is drained, the cleaning liquid valve 14 is closed, and the drive motor 5 is started to rotate the filter plate 3 and the cleaning filter plate 4 to remove the filter cake on the filter plate 3 and the cleaning filter plate 4 until the differential pressure is restored. The motor is stopped, nitrogen gas after pressure reduction is introduced for pressurization, and the bottom slag discharge valve 12 is opened to discharge slag. After completion, the slag discharge valve 12 is closed, and the feed and discharge system is put into operation to maintain operation.

[0023] The specific operation of the methanol-to-olefins quench water solid-liquid separation device is as follows:

[0024] 1) During the operation of the quench tower 1, liquid phase circulation is established through the circulating pump 6 to maintain the discharge of some quench water;

[0025] 2) Open the feed valve 10 to control the water flow rate, open the filter valve 13 to return the filtered quench water to the quench tower 1, and control the solid-liquid separator 2 to process load at 5t / h;

[0026] 3) Observe the differential pressure change of solid-liquid separator 2, gradually increase the influent flow rate to 10t / h. If the differential pressure gauge 7 of solid-liquid separator 2 rises above the set value, close the feed valve 10 and the filter valve 13.

[0027] 4) Pressurize with depressurized nitrogen, open cleaning liquid valve 14, and the remaining material in the solid-liquid separator passes through cleaning filter plate 4 and is discharged from cleaning liquid outlet. After the liquid is drained, close cleaning liquid valve 14, start drive motor 5 to rotate filter plate 3 and cleaning filter plate 4 to remove filter cake on filter plate 3 and cleaning filter plate 4 until the filter plate differential pressure is restored, then stop drive motor 5.

[0028] 5) Pressurize the solid-liquid separator 2 with nitrogen gas after depressurization from the pipeline network;

[0029] 6) Open the bottom slag discharge valve 12 to discharge slag, then close it afterward;

[0030] 7) Activate the feed valve 10 and the filter valve 13 in sequence to maintain operation, and set the program to automatic.

Claims

1. A methanol-to-olefins quench water solid-liquid separation device, comprising a quench tower (1), characterized in that, The device also includes a solid-liquid separator (2), which contains a filter plate (3). The circulating water of the quench tower (1) enters the solid-liquid separator (2) from the top. After solid-liquid separation by the filter plate (3), the filtrate returns to the quench tower (1) from the filtrate outlet of the solid-liquid separator (2). The bottom of the solid-liquid separator (2) is provided with a cleaning liquid outlet and a slag outlet, and the top is provided with a pressurization port connected to a nitrogen pipeline.

2. The methanol-to-olefins quench water solid-liquid separation apparatus according to claim 1, characterized in that, The solid-liquid separator (2) includes a pressure vessel with a hollow central rotating shaft. A set of circular filter discs (3) are horizontally mounted on the central rotating shaft. The filter discs (3) are vertically stacked with the central rotating shaft as the center and at a certain interval to form a filter stack. Below the filter stack, a set of circular cleaning filter discs (4) are horizontally mounted on the central rotating shaft. The central rotating shaft has an opening in the filter stack section, which serves as a filtrate discharge manifold connected to the filtrate outlet.

3. The methanol-to-olefins quench water solid-liquid separation apparatus according to claim 2, characterized in that, The central rotating shaft is driven by a drive motor (5).

4. The methanol-to-olefins quench water solid-liquid separation apparatus according to claim 2, characterized in that, The filter materials on the filter disc (3) and the cleaning filter disc (4) are selected from wire mesh, textile materials, sintered metal or porous plates.

5. The methanol-to-olefins quench water solid-liquid separation apparatus according to claim 1, characterized in that, A differential pressure gauge (7) is installed on the solid-liquid separator (2).

6. The methanol-to-olefins quench water solid-liquid separation apparatus according to claim 1, characterized in that, The circulating water of the quench tower (1) is sent to the solid-liquid separator (2) by the bottom circulating pump (6).

7. The methanol-to-olefins quench water solid-liquid separation apparatus according to claim 1, characterized in that, A safety valve (11) is installed on the solid-liquid separator (2).

8. The methanol-to-olefins quench water solid-liquid separation apparatus according to claim 1, characterized in that, The nitrogen pipeline is connected to the pressurization port of the solid-liquid separator (2) via a pressure reducing valve (8) and a pressure gauge (9).

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