Methanol-to-olefin wastewater treatment system and method

Abstract

The invention discloses a methanol-to-olefin wastewater treatment system and method.The methanol-to-olefin wastewater treatment system comprises a quench tower, a filter circulation tank, an inorganic membrane filter, a stripping tower and a quench water concentrated solution storage tank, the filter circulation tank is connected with the quench tower, the inorganic membrane filter is connected with the filter circulation tank, and the stripping tower is connected with the quench water concentrated solution storage tank; the quenching water is conveyed to the inorganic membrane filter for filtration treatment, the filtered concentrated liquid is returned to the filtration circulation tank for re-circulation, the stripping tower is connected with the inorganic membrane filter, the filtered clear liquid is conveyed to the stripping tower, the quenching water concentrated liquid storage tank is connected with the inorganic membrane filter, and a part of the filtered concentrated liquid is pumped out and conveyed to the quenching water concentrated liquid storage tank. The treatment system provided by the invention can effectively filter catalyst particles in the fluidized bed methanol-to-olefin wastewater, has strong treatment capacity and small occupied area, improves the liquid-solid separation efficiency, reduces the energy consumption and wastewater discharge, and reduces the equipment blockage and maintenance cost.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a methanol to olefins wastewater treatment system and method. Background Art

[0002] The methanol to olefins process in the related art is equipped with a three-stage or four-stage cyclone separator after the reactor. Most of the catalyst particles in the reaction gas are removed after the reaction gas enters the three-stage or four-stage cyclone separator. However, due to the structural limitation of the cyclone separator, it can only separate solid catalyst particles with a particle size greater than 10 microns in the reaction gas, while solid catalyst particles with a particle size less than 10 microns enter the quench water and wash water along with the reaction gas, resulting in heat exchanger blockage and reduced heat exchange capacity during the operation of the wastewater treatment system, affecting the long-term operation of the device. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, an embodiment of the present invention provides a methanol to olefins wastewater treatment system, which plays an important role in achieving long-term stable operation of a fluidized bed methanol to olefins device.

[0005] The methanol to olefins wastewater treatment system of the embodiment of the present invention comprises:

[0006] quench tower;

[0007] A filter circulation tank, the filter circulation tank is connected to the quench tower via a pipeline to transport the quench water to be treated in the quench tower to the filter circulation tank;

[0008] An inorganic membrane filter, wherein the inorganic membrane filter is connected to the filter circulation tank via a pipeline, so as to transport the quench water in the filter circulation tank to the inorganic membrane filter for filtration treatment, and the concentrated liquid filtered by the inorganic membrane filter is returned to the filter circulation tank for recirculation;

[0009] A stripping tower, wherein the stripping tower is connected to the inorganic membrane filter via a pipeline so that the clear liquid filtered by the inorganic membrane filter is transported to the stripping tower;

[0010] A quench water concentrated liquid storage tank is connected to the inorganic membrane filter via a pipeline so as to extract a portion of the concentrated liquid filtered out by the inorganic membrane filter and transport it to the quench water concentrated liquid storage tank.

[0011] The methanol to olefins wastewater treatment system of the embodiment of the present invention can effectively filter the catalyst particles in the fluidized bed methanol to olefins wastewater, has strong treatment capacity, occupies a small area of ​​the device, improves the liquid-solid separation efficiency, reduces energy consumption and wastewater discharge, and reduces equipment blockage and maintenance costs.

[0012] In some embodiments, the amount of concentrate extracted from the concentrate filtered out by the inorganic membrane filter accounts for 10% of the amount of clear liquid filtered out by the inorganic membrane filter.

[0013] In some embodiments, a quench water booster pump is provided on the pipeline between the filter circulation tank and the quench tower, and the quench water booster pump is used to pressurize the quench water to be treated in the quench tower and then transport it to the filter circulation tank.

[0014] In some embodiments, a membrane filtration circulation pump is provided on the pipeline between the inorganic membrane filter and the filtration circulation tank, and the membrane filtration circulation pump is used to drive quenching water to circulate between the inorganic membrane filter and the filtration circulation tank.

[0015] In some embodiments, it also includes:

[0016] A plate-frame filter press, the plate-frame filter press is connected to the quench water concentrate storage tank via a pipeline, so as to transport the concentrated liquid in the quench water concentrate storage tank to the plate-frame filter press for compression and filtration;

[0017] A screw conveyor, the screw conveyor is connected to the plate and frame filter press, so that the filter cake compressed by the plate and frame filter press is conveyed to the waste hopper through the screw conveyor;

[0018] A plate and frame filtered liquid storage tank is connected to the plate and frame filter press via a pipeline so that the clear liquid filtered by the plate and frame filter press is transported to the plate and frame filtered liquid storage tank. The plate and frame filtered liquid storage tank is also connected to the quenching tower via a pipeline so that the clear liquid is transported back to the quenching tower for recycling.

[0019] In some embodiments, a concentrate booster pump is provided on the pipeline between the plate and frame filter press and the quench water concentrate storage tank, and the concentrate booster pump is used to pressurize the concentrate in the quench water concentrate storage tank and then transport it to the plate and frame filter press.

[0020] In some embodiments, a plate and frame clear liquid booster pump is provided on the pipeline between the plate and frame filtered liquid storage tank and the quenching tower, and the plate and frame clear liquid booster pump is used to pressurize the clear liquid in the plate and frame filtered liquid storage tank and then transport it to the quenching tower.

[0021] In some embodiments, a steam supply device is further included, wherein the steam supply device is connected to the inorganic membrane filter via a pipeline so as to use steam to purge the inorganic membrane filter.

[0022] In some embodiments, it also includes:

[0023] an alkaline washing liquid tank, the alkaline washing liquid tank being connected to the inorganic membrane filter via a pipeline so as to use the alkaline washing liquid to wash the inorganic membrane filter;

[0024] A pickling liquid tank, the pickling liquid tank is connected to the inorganic membrane filter via a pipeline, so as to use the pickling liquid to clean the inorganic membrane filter;

[0025] A nitrogen supply device, wherein the nitrogen supply device is connected to the inorganic membrane filter via a pipeline so as to use nitrogen to purge the inorganic membrane filter after alkali washing or acid washing;

[0026] A fresh water supply device, the fresh water supply device is connected to the inorganic membrane filter via a pipeline, so as to use fresh water to rinse the inorganic membrane filter after alkali washing or acid washing;

[0027] A desalted water supply device is connected to the inorganic membrane filter via a pipeline so as to use the desalted water to flush the inorganic membrane filter after alkali washing or acid washing.

[0028] An embodiment of the present invention further provides a method for treating methanol-to-olefins wastewater, and the method is used in any of the above-mentioned methanol-to-olefins wastewater treatment systems.

[0029] The method for treating methanol-to-olefins wastewater according to an embodiment of the present invention comprises:

[0030] The quench water to be treated is pumped to the filter circulation tank, the quench water in the filter circulation tank is pumped to the inorganic membrane filter for filtration, the filtered clear liquid is transported to the stripping tower, the concentrated liquid returns to the filter circulation tank for continuous circulation, and a part of the concentrated liquid is sent to the plate and frame filter press to filter the catalyst;

[0031] After the inorganic membrane filter runs for a preset cycle, the inorganic ceramic membrane of the inorganic membrane filter is regenerated. During the regeneration process, it goes through drainage, steam purging, alkali washing and nitrogen purging, fresh water flushing, acid washing and nitrogen purging, fresh water flushing, and desalted water flushing in sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a process flow chart of a methanol to olefins wastewater treatment system according to an embodiment of the present invention.

[0033] Figure 2 Schematic diagram of the cross section of an inorganic membrane filter according to an embodiment of the present invention.

[0034] Figure 3 It is a process flow chart of the plate and frame filter press according to an embodiment of the present invention.

[0035] Reference numerals:

[0036] 1-quenching tower, 2-quenching water booster pump, 3-filtration circulation tank, 4-membrane filtration circulation pump, 5-inorganic membrane filter, 6-stripping tower, 7-quenching water concentrate storage tank, 8-concentrate booster pump, 9-plate and frame filter press, 10-screw conveyor, 11-plate and frame filter liquid storage tank, 12-plate and frame clear liquid booster pump, 13-alkaline washing liquid tank, 14-acid washing liquid tank, 15-cleaning liquid pump, 16-neutralization tank, 17-steam supply device, 18-nitrogen supply device, 19-fresh water supply device, 20-desalted water supply device. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0038] The following describes a methanol to olefins wastewater treatment system according to an embodiment of the present invention in conjunction with the accompanying drawings.

[0039] like Figures 1 to 3 As shown, the methanol to olefins wastewater treatment system of the embodiment of the present invention includes: a quenching tower 1, a filtering circulation tank 3, an inorganic membrane filter 5, a stripping tower 6 and a quenching water concentrate storage tank 7.

[0040] The filter circulation tank 3 is connected to the quench tower 1 via a pipeline to transport the quench water to be treated in the quench tower 1 to the filter circulation tank 3. For example, a quench water booster pump 2 is provided on the pipeline between the filter circulation tank 3 and the quench tower 1, and the quench water booster pump 2 is used to boost the quench water to be treated in the quench tower 1 and then transport it to the filter circulation tank 3.

[0041] The inorganic membrane filter 5 is connected to the filter circulation tank 3 via a pipeline to transport the quenching water in the filter circulation tank 3 to the inorganic membrane filter 5 for filtration treatment, and the concentrated solution filtered by the inorganic membrane filter 5 is returned to the filter circulation tank 3 for recirculation. For example, a membrane filtration circulation pump 4 is provided on the pipeline between the inorganic membrane filter 5 and the filter circulation tank 3, and the membrane filtration circulation pump 4 is used to drive the quenching water to circulate between the inorganic membrane filter 5 and the filter circulation tank 3.

[0042] The stripping tower 6 is connected to the inorganic membrane filter 5 via a pipeline, so that the clear liquid filtered out by the inorganic membrane filter 5 is transported to the stripping tower 6 .

[0043] The quench water concentrate storage tank 7 is connected to the inorganic membrane filter 5 via a pipeline, so that a portion of the concentrate filtered out of the inorganic membrane filter 5 is extracted and transported to the quench water concentrate storage tank 7. The amount of concentrate extracted from the concentrate filtered out of the inorganic membrane filter 5 accounts for 10% of the amount of clear liquid filtered out of the inorganic membrane filter 5.

[0044] like Figure 1As shown, the quench water containing oil and catalyst is pressurized by the quench water booster pump 2, the quench water temperature reaches 120°C, and the pressure reaches 1.3MPaG. After passing through the regulating valve 101, it enters the filter circulation tank 3, wherein the regulating valve 101 controls the quench water flow entering the inorganic membrane filter 5, 101 and the pressure gauge 202 of the filter circulation tank 3 realize single-loop control, and after the clear liquid output of the inorganic membrane filter 5 is adjusted, the regulating valve 101 automatically controls the pressure of the entire system to keep the system pressure at 1.3MPaG.

[0045] like Figure 1 As shown, after the quenching water enters the filtration circulation tank 3, it is sent to the inorganic membrane filter 5 after passing through the membrane filtration circulation pump 4. Five membrane filtration circulation pumps 4 are arranged, three in operation and two in reserve. One membrane filtration circulation pump 4 corresponds to one inorganic membrane filter 5. Each inorganic membrane filter 5 does not interfere with each other. The membrane filtration circulation pump 4 adopts variable frequency control to ensure the circulation amount of quenching water in each filter to prevent catalyst deposition.

[0046] like Figure 1 As shown, the quenching water passes through the membrane filtration circulation pump 4, and each inorganic membrane filter 5 is provided with two groups of filtration modules, which are connected in series and vertically distributed. The quenching water enters from the bottom of the first group of filtration modules, is sent out from the bottom of the second group of filtration modules, and then flows back to the filtration circulation tank 3 to complete the whole cycle.

[0047] like Figure 2 As shown, the ceramic membrane tubes inside each group of filter modules are distributed vertically in a circular shape, which is similar to the arrangement of a fixed tube sheet heat exchanger. The quenching water enters from the bottom, passes through the circular channel in the ceramic membrane tube, flows out from the top, and enters the top of the second group of filter modules. The quenching water enters from the top of the second group of filter modules and flows out from the bottom through the circular channel in the ceramic membrane tube. The quenching water in the ceramic membrane tube flows along the surface of the inorganic ceramic membrane, forming fluid shear conditions on the membrane surface. The filtered clear liquid enters the shell side through the ceramic membrane gap. The shell sides of the two groups of filter modules are connected by pipes. The filtered clear liquid passes through the regulating valve 104 to the stripping tower 6 to achieve the filtering purpose.

[0048] like Figure 1 As shown, the regulating valve 104 controls the clear liquid extraction flow rate. For example, a single inorganic ceramic membrane filter can process 23.5m 3 / h, the outlet regulating valve 104 realizes single-loop control and cooperates with the inlet regulating valve 101 to achieve automatic control as a whole.

[0049] like Figure 1As shown, a remote pressure gauge 204 is provided at the filter inlet, a remote pressure gauge 205 is provided at the top of the pipeline connecting the outlet of the first group of filter modules with the second group of filter modules, a remote pressure gauge 206 is provided at the outlet of the shell side clear liquid side, and a remote pressure gauge 207 is provided at the outlet of the second group of filter modules. The operation status of each inorganic membrane filter 5 is monitored online through the above remote pressure gauges to determine whether regeneration is required.

[0050] like Figure 1 As shown, before the outlet of the inorganic membrane filter 5 returns to the filter circulation tank 3, a concentrated solution is produced and sent to the quench water concentrated solution storage tank 7. For example, the concentrated solution production of a single inorganic ceramic membrane filter is 2.5m 3 / h, to prevent the catalyst from gradually depositing during the inorganic membrane filtration cycle. The concentrated solution production flow rate is controlled by the regulating valve 105. The regulating valve 105 and the concentrated solution flow meter 203 realize single-loop control and realize automatic control of the concentrated solution production.

[0051] Therefore, the methanol to olefins wastewater treatment system of the embodiment of the present invention can effectively filter the catalyst particles in the fluidized bed methanol to olefins wastewater, has strong treatment capacity, occupies a small area of ​​the device, improves the liquid-solid separation efficiency, reduces energy consumption and wastewater discharge, and reduces equipment blockage and maintenance costs.

[0052] like Figure 3 As shown, the methanol to olefins wastewater treatment system according to the embodiment of the present invention further includes: a plate and frame filter press 9, a screw conveyor 10 and a plate and frame filtrate liquid storage tank 11.

[0053] The plate-frame filter press 9 is connected to the quench water concentrate storage tank 7 via a pipeline to transport the concentrate in the quench water concentrate storage tank 7 to the plate-frame filter press 9 for compression and filtration. For example, a concentrate booster pump 8 is provided on the pipeline between the plate-frame filter press 9 and the quench water concentrate storage tank 7, and the concentrate booster pump 8 is used to pressurize the concentrate in the quench water concentrate storage tank 7 and then transport it to the plate-frame filter press 9.

[0054] The screw conveyor 10 is connected to the plate-frame filter press 9 so that the filter cake compressed by the plate-frame filter press 9 is conveyed to the waste hopper through the screw conveyor 10 .

[0055] The plate-frame filter clear liquid storage tank 11 is connected to the plate-frame filter press 9 via a pipeline, so that the clear liquid filtered by the plate-frame filter press 9 is transported to the plate-frame filter clear liquid storage tank 11. The plate-frame filter clear liquid storage tank 11 is also connected to the quenching tower 1 via a pipeline, so that the clear liquid is transported back to the quenching tower 1 for recycling. For example, a plate-frame clear liquid booster pump 12 is provided on the pipeline between the plate-frame filter clear liquid storage tank 11 and the quenching tower 1, and the plate-frame clear liquid booster pump 12 is used to pressurize the clear liquid in the plate-frame filter clear liquid storage tank 11 and transport it to the quenching tower 1.

[0056] The concentrated liquid extracted from the inorganic membrane filter 5 enters the quench water concentrated liquid storage tank 7 and passes through the quench water concentrated liquid booster pump 8 (one open and one standby), and the temperature reaches 100°C and the pressure reaches 0.8MPaG, and is sent to the plate and frame filter press 9 for filtration. The plate and frame filter press 9 adopts a two-open and one-standby method. The filtered clear liquid is sent to the plate and frame filtered clear liquid storage tank 11, and then sent to the quench tower 1 for recycling after passing through the plate and frame clear liquid booster pump 12 (one open and one standby). After the filtered filter cake is formed, the filter plate is pulled open by the plate pulling trolley of the plate and frame filter press 9. The filter cake falls into the screw conveyor 10 due to gravity, and is transported to the waste hopper by the bolt conveyor and then loaded for processing.

[0057] It should be noted that after the inorganic membrane filter 5 has been running for a period of time, when the pressure difference between the pressure gauge 206 on the clear liquid side and the pressure gauge 204 on the quench water inlet side is greater than 0.25 MPaG, the inorganic ceramic membrane needs to be regenerated. Regeneration uses independent pipeline equipment, mainly using 8% sodium hydroxide solution and 8% nitric acid solution for regeneration, so that the membrane surface is thoroughly cleaned and the filtration flux is fully restored. The entire regeneration process is automatically controlled by programmable valves.

[0058] Among them, the steam, nitrogen, fresh water and desalted water used for regeneration are all connected by external public works, and the sodium hydroxide solution and nitric acid solution used for regeneration are configured in corresponding liquid tanks and can be recycled and reused.

[0059] The inorganic membrane filter 5 undergoes regeneration through drainage, steam purging, alkali washing and nitrogen purging, fresh water rinsing, acid washing and nitrogen purging, fresh water rinsing, and desalted water rinsing, and then regeneration is completed and ready for use. Since the acid and alkali solutions share the same regeneration pipeline, part of the acid and alkali solutions in the pipelines before and after the cleaning liquid pump 15 are discharged to the neutralization tank 16 through a program-controlled valve to be neutralized into a neutral solution, and are regularly sent to sewage treatment.

[0060] like Figure 1 As shown, the drainage stage during the regeneration process of the inorganic membrane filter 5:

[0061] S1: Close the clear liquid flow control regulating valve 104 of the inorganic membrane filter 5.

[0062] S2: The central control reduces the frequency of the corresponding filter circulation pump to 0%.

[0063] S3: Close the filter quench water inlet program-controlled valve 102, and close the quench water outlet program-controlled valve 103.

[0064] S4: After a delay of 30 seconds, open the filter inlet discharge program-controlled valve 109, open the filter outlet discharge program-controlled valve 110, and open the flushing water to quench water concentrate storage tank 7 program-controlled valve 106.

[0065] S5: Open the programmable valve 111 at the top of the filter drain port, open the programmable valve 107 at the bottom of the filter clear liquid outlet, and enter the equipment draining step.

[0066] S6: After draining for 10 minutes, close the programmable valve 111 at the top of the filter and close the programmable valve 107 at the outlet of the clear liquid at the bottom of the filter.

[0067] S7: The programmable valve 110 at the filter concentrate discharge port remains open, the programmable valve 109 at the filter inlet discharge port remains open, and the programmable valve 106 at the inlet of the flushing water to quench water concentrate storage tank 7 remains open.

[0068] like Figure 1 As shown, the methanol to olefins wastewater treatment system according to the embodiment of the present invention further includes a steam supply device 17 , which is connected to the inorganic membrane filter 5 via a pipeline so as to purge the inorganic membrane filter 5 with steam.

[0069] Steam purge stage during the regeneration process of inorganic membrane filter 5:

[0070] S1: Open the filter purge inlet program-controlled valve 108, and open the filter purge steam inlet program-controlled valve 112.

[0071] S2: The purge timer starts for 10 minutes.

[0072] S3: Close the filter purge inlet program-controlled valve 108, and close the filter purge steam inlet program-controlled valve 112.

[0073] S4: Delay for 30 seconds, close the filter inlet discharge program-controlled valve 109, close the filter outlet discharge program-controlled valve 110, and close the flushing water to quench water concentrate storage tank 7 inlet program-controlled valve 106.

[0074] like Figure 1 As shown, the methanol to olefins wastewater treatment system according to the embodiment of the present invention further includes: an alkaline washing liquid tank 13, an acid washing liquid tank 14, a nitrogen supply device 18, a fresh water supply device 19 and a demineralized water supply device.

[0075] The alkaline washing liquid tank 13 is connected to the inorganic membrane filter 5 via a pipeline so as to clean the inorganic membrane filter 5 with the alkaline washing liquid.

[0076] The pickling liquid tank 14 is connected to the inorganic membrane filter 5 via a pipeline to use the pickling liquid to clean the inorganic membrane filter 5. The nitrogen supply device 18 is connected to the inorganic membrane filter 5 via a pipeline to use nitrogen to purge the inorganic membrane filter 5 after alkali washing or acid washing. The fresh water supply device 19 is connected to the inorganic membrane filter 5 via a pipeline to use fresh water to rinse the inorganic membrane filter 5 after alkali washing or acid washing. The deionized water supply device is connected to the inorganic membrane filter 5 via a pipeline to use deionized water to rinse the inorganic membrane filter 5 after alkali washing or acid washing.

[0077] Alkali washing and nitrogen purge stages during the regeneration process of inorganic membrane filter 5:

[0078] S1: Open the programmable valve 111 at the top drain port of the filter, open the programmable valve 124 for the inlet of the acid and alkali cleaning solution of the filter, open the programmable valve 115 for returning the alkaline cleaning solution to the alkaline cleaning tank after cleaning, open the programmable valve 118 for the alkaline cleaning solution at the outlet of the alkaline cleaning solution tank 13, open the programmable valve 120 for the inlet of the cleaning solution pump 15, open the programmable valve 122 for the outlet of the cleaning solution pump 15, and open the reflux valve 116 from the outlet of the cleaning solution pump 15 to the alkaline cleaning solution tank 13.

[0079] S2: After determining that the above valve is in the open state, the cleaning liquid pump 15 is started by program control.

[0080] S3: The exhaust timer is turned on for 5 minutes, and the programmable valve 109 on the discharge port of the raw liquid side of the inorganic membrane filter 5 is opened.

[0081] S4: Close the programmable valve 111 at the top of the filter drain port and the reflux valve 116 from the outlet of the cleaning liquid pump 15 to the alkaline washing liquid tank 13; after confirming that 111 is closed, open the programmable valve 107 at the outlet of the clear liquid side of the filter, and the equipment enters the alkaline washing state.

[0082] S5: The alkali cleaning timer is turned on for 30 minutes, and the cleaning liquid pump 15 is stopped after the alkali cleaning is completed.

[0083] S6: Close the programmable valve 107 on the clear liquid outlet side of the filter, close the programmable valve 124 on the acid and alkali cleaning liquid inlet side of the filter, close the programmable valve 118 on the alkali cleaning liquid outlet side of the alkali cleaning liquid tank 13, close the programmable valve 120 on the inlet side of the cleaning liquid pump 15, and close the programmable valve 122 on the outlet side of the cleaning liquid pump 15.

[0084] S7: After confirming that the above valves are completely closed, open the filter outlet discharge programmable valve 110, open the cleaning liquid pump 15 outlet to the neutralization tank 16 programmable valve 123, and open the acid and alkali cleaning liquid to the neutralization tank 16 inlet programmable valve 121.

[0085] S8: Open the filter purge inlet program-controlled valve 108, and open the filter purge nitrogen inlet program-controlled valve 113.

[0086] S9: The drain timer starts for 10 minutes.

[0087] S10: Close the filter purge inlet program-controlled valve 108, and close the filter purge nitrogen inlet program-controlled valve 113.

[0088] S11: After a delay of 30 seconds, close the filter inlet discharge programmable valve 109, close the filter outlet discharge programmable valve 110, close the cleaning liquid pump 15 outlet to the neutralization tank 16 programmable valve 123, and close the acid and alkali cleaning liquid to the neutralization tank 16 inlet programmable valve 121.

[0089] S12: Close the programmable valve 115 for returning the alkaline cleaning liquid to the alkaline washing tank after cleaning, and the alkaline cleaning and nitrogen purging stages are completed.

[0090] Then the fresh water flushing stage of the inorganic membrane filter 5 regeneration process is carried out:

[0091] S1: Open the programmable valve 111 of the drain port at the top of the filter, and open the programmable valve 106 of the flushing water to the quench water concentrate storage tank 7.

[0092] S2: Open the filter fresh water programmable valve 126, start the exhaust timer for 5 minutes, and open the filter inlet exhaust programmable valve 109.

[0093] S3: Close the programmable valve 111 at the top drain port of the filter.

[0094] S4: Open the programmable valve 107 on the outlet side of the clear liquid at the bottom of the filter, start the flushing timer for 10 minutes, and after the timing ends, close the programmable valve 107 on the outlet side of the clear liquid at the bottom of the filter, and close the programmable valve 126 on the fresh water at the filter.

[0095] S5: Open the filter outlet discharge programmable valve 110, open the filter purge inlet programmable valve 108, and open the filter purge nitrogen inlet programmable valve 113.

[0096] S6: The drain timer starts for 10 minutes.

[0097] S7: Close the programmable valve 108 at the filter purge inlet, and close the programmable valve 113 at the nitrogen purge inlet of the inorganic membrane filter 5.

[0098] S8: After a delay of 30 seconds, close the filter inlet discharge program-controlled valve 109, and close the filter outlet discharge program-controlled valve 110.

[0099] S9: Close the programmable valve 106 for flushing water to the quench water concentrate storage tank 7, and the fresh water flushing stage is completed.

[0100] The acid washing and nitrogen purging phase of the inorganic membrane filter 5 regeneration process begins:

[0101] S1: Open the programmable valve 111 at the top drain port of the filter, open the programmable valve 124 at the filter acid and alkali cleaning solution inlet, open the programmable valve 114 at the acid cleaning solution tank inlet, open the programmable valve 119 at the acid cleaning solution tank 14 outlet, open the programmable valve 120 at the cleaning solution pump 15 inlet, open the programmable valve 122 at the cleaning solution pump 15 outlet, open the reflux valve 117 from the cleaning solution pump 15 outlet to the acid cleaning solution tank 14, and after confirming that the above valves are open, start the cleaning solution pump 15 by program control.

[0102] S2: The exhaust timer starts for 5 minutes.

[0103] S3: Open the filter inlet discharge program-controlled valve 109, close the reflux valve 117 from the outlet of the cleaning liquid pump 15 to the pickling liquid tank 14, and close the filter top drain port program-controlled valve 111.

[0104] S4: Open the programmable valve 107 on the outlet side of the clear liquid under the filter, the equipment enters the pickling state, the pickling timer starts for 30 minutes, and the cleaning liquid pump 15 is stopped.

[0105] S5: Close the programmable valve 107 on the clear liquid outlet side of the filter, close the programmable valve 124 on the acid and alkali cleaning liquid inlet side of the filter, close the programmable valve 119 on the acid cleaning liquid tank 14 outlet side, close the programmable valve 120 on the cleaning liquid pump 15 inlet side, and close the programmable valve 122 on the cleaning liquid pump 15 outlet side.

[0106] S6: After confirming that the above valves are closed, open the filter outlet discharge programmable valve 110, open the cleaning liquid pump 15 outlet to the neutralization tank 16 programmable valve 123, and open the acid and alkali cleaning liquid to the neutralization tank 16 inlet programmable valve 121.

[0107] S7: Open the filter purge inlet program-controlled valve 108, and open the filter purge nitrogen inlet program-controlled valve 113.

[0108] S8: The drain timer starts for 10 minutes.

[0109] S9: Close the filter purge inlet program-controlled valve 108, and close the filter purge nitrogen inlet program-controlled valve 113.

[0110] S10: Delay for 30 seconds, close the filter inlet discharge programmable valve 109, close the filter outlet discharge programmable valve 110, close the cleaning liquid pump 15 outlet to the neutralization tank 16 programmable valve 123, close the acid and alkali cleaning liquid to the neutralization tank 16 inlet programmable valve 121.

[0111] S11: Close the acid cleaning liquid tank inlet liquid program-controlled valve 114, and the acid cleaning and nitrogen purging stages are completed.

[0112] The fresh water flushing stage in the regeneration process of the inorganic membrane filter 5 is performed again, which is the same as the fresh water flushing stage after the alkaline washing and nitrogen purge stages are completed, and will not be repeated here.

[0113] Finally, the desalted water flushing stage during the regeneration of the inorganic membrane filter 5 is performed:

[0114] S1: Open the programmable valve 111 of the drain port at the top of the filter, and open the programmable valve 106 of the flushing water to the quench water concentrate storage tank 7.

[0115] S2: Open the program-controlled valve 125 at the filter desalted water inlet.

[0116] S3: The exhaust timer starts for 5 minutes.

[0117] S4: Open the filter inlet discharge programmable valve 109.

[0118] S5: Close the programmable valve 111 at the top drain port of the filter;

[0119] S6: Open the program-controlled valve 107 at the outlet of the clear liquid side of the filter.

[0120] S7: The rinse timer starts for 10 minutes.

[0121] S8: Close the programmable valve 107 on the clear liquid outlet side of the filter, and close the programmable valve 125 on the desalted water inlet side of the filter.

[0122] S9: Delay for 30 seconds, close the filter inlet discharge programmable valve 109, and close the flushing water to quench water concentrate storage tank 7 programmable valve 106.

[0123] S10: The desalted water flushing phase ends and the equipment enters standby mode.

[0124] The control logic of the methanol to olefins wastewater treatment system of the embodiment of the present invention adopts an automatic control system that uses the pressure gauge 202 of the filter circulation tank 3 to control the quench water flow meter 201 of the filter circulation tank 3. That is, the signal of the pressure transmitter of the filter circulation tank 3 is connected to the DCS, and the DCS controls the opening of the liquid inlet valve 101 according to the change of pressure, so as to change the flow of the quench water entering the filter circulation tank 3 to change the pressure of the filter circulation tank 3, thereby achieving the purpose of stably controlling the pressure of the filter circulation tank 3.

[0125] The automatic control system is used to control the back pressure of the clear liquid side of the first and second components of the inorganic membrane filter 5 by the clear liquid flow rate out of the inorganic membrane filter 5, and adjust the clear liquid flow rate. That is, the signal of the inorganic membrane clear liquid electromagnetic flowmeter transmitter is connected to the controller, and the controller controls the opening of the first and second filter component outlet automatic regulating valve according to the change of the flow rate, changes the back pressure of the permeation side of the first and second components, and adjusts the clear liquid flow rate of the first and second components, so as to achieve the purpose of stably controlling the clear liquid flow rate of the inorganic membrane filter 5.

[0126] The discharge flow rate of the concentrated liquid from the inorganic membrane filter 5 is adjusted by the solid content of the concentrated liquid from the inorganic membrane filter 5, and the automatic control system for controlling the solid content of the concentrated liquid at the outlet of the filter is adopted. That is, according to the solid content of the concentrated liquid, the signal of the electromagnetic flowmeter transmitter of the inorganic membrane concentrated liquid is connected to the DCS controller, and the controller controls the opening of the concentrated liquid discharge automatic regulating valve 105 according to the set flow parameters, and changes the discharge flow rate of the concentrated liquid, so as to achieve the purpose of stably controlling the solid content of the concentrated liquid from the inorganic membrane filter 5.

[0127] In summary, the methanol to olefins wastewater treatment system of the embodiment of the present invention uses the membrane filtration circulation pump 4 to force circulation filtration, the filtration flow is large, and the catalyst in the wastewater is not easy to deposit. In addition, during the circulation process of the concentrated liquid, 10% of the clear liquid output is extracted and sent to the plate and frame filter press 9, further preventing the catalyst from being gradually deposited during the inorganic ceramic membrane filtration circulation process.

[0128] The filtration method adopts the cross-flow filtration method. The liquid in the filter is a cross-flow and tangential flow process. The liquid flows along the surface of the inorganic ceramic membrane, forming fluid shear conditions on the membrane surface, making it difficult for pollutants to stay on the membrane surface. The inorganic ceramic membrane can be used for a long time and repeatedly.

[0129] One of the inorganic membrane filters 5 in the system is always in the regeneration stage to ensure that the output of the clear liquid is continuous and stable.

[0130] The membrane filtration circulation pump 4 adopts frequency conversion control. During the regeneration stage of the inorganic ceramic membrane filter, the filtration circulation pump frequency is reduced to the minimum, and the frequency is increased when the regeneration is completed and put into use. The whole process is controlled by the central control, which reduces manpower and keeps the regeneration time to the shortest.

[0131] The following describes a method for treating methanol-to-olefins wastewater according to an embodiment of the present invention. The method is used for any of the above-mentioned methanol-to-olefins wastewater treatment systems.

[0132] The method for treating methanol-to-olefins wastewater according to an embodiment of the present invention comprises:

[0133] The quench water booster pump 2 is used to send the quench water to the filter circulation tank 3, and then to the inorganic membrane filter 5 for filtration through the membrane filtration circulation pump 4. The inorganic membrane filter 5 is arranged vertically. After entering the inorganic membrane filter 5, the quench water is filtered by cross-flow. The filtered clear liquid goes to the stripping tower 6, and the concentrated liquid returns to the filter circulation pump for continuous circulation. The inorganic membrane filter 5 adopts a three-in-one standby mode, and each inorganic membrane filter 5 corresponds to a membrane filtration circulation pump 4.

[0134] A portion of the concentrated liquid (10% of the clear liquid production) is produced and sent to the quench water concentrated liquid storage tank 7, and then sent to the plate and frame filter press 9 for filtration via the concentrated liquid booster pump 8. The filtered clear liquid returns to the quench tower 1, and the filter cake formed by filtration is loaded onto a truck through a screw conveyor 10 for processing. The plate and frame filter press 9 adopts two in operation and one in reserve.

[0135] After a long period of operation, when the pressure difference between the clear liquid extraction side and the filter inlet pressure is greater than 0.25 MPaG, the inorganic ceramic membrane is regenerated. The regeneration equipment includes an alkaline washing liquid tank 13, an acid washing liquid tank 14, a cleaning liquid pump 15, a steam supply device 17, a nitrogen supply device 18, a fresh water supply device 19, and a demineralized water supply device.

[0136] The inorganic ceramic membrane to be regenerated is isolated by a programmable valve and the liquid is discharged to the quench water concentrate storage tank 7. Each inorganic ceramic membrane filter is equipped with a dedicated regeneration pipeline, and its material is isolated by a programmable valve. When the inorganic ceramic membrane is regenerated, the programmable valve is opened in sequence to drain, steam purge, alkali wash and nitrogen purge, fresh water rinse, acid wash and nitrogen purge, fresh water rinse, and desalted water rinse. After completing the above steps, the online cleaning of the inorganic ceramic membrane filter is completed.

[0137] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0138] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0139] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0140] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0141] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0142] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A methanol to olefins wastewater treatment system, characterized in that: include: quench tower; A filter circulation tank, the filter circulation tank is connected to the quench tower via a pipeline to transport the quench water to be treated in the quench tower to the filter circulation tank; An inorganic membrane filter, wherein the inorganic membrane filter is connected to the filter circulation tank via a pipeline, so as to transport the quench water in the filter circulation tank to the inorganic membrane filter for filtration treatment, and the concentrated liquid filtered by the inorganic membrane filter is returned to the filter circulation tank for recirculation; A stripping tower, wherein the stripping tower is connected to the inorganic membrane filter via a pipeline so that the clear liquid filtered by the inorganic membrane filter is transported to the stripping tower; A quench water concentrated liquid storage tank is connected to the inorganic membrane filter via a pipeline so as to extract a portion of the concentrated liquid filtered out by the inorganic membrane filter and transport it to the quench water concentrated liquid storage tank.

2. The methanol to olefins wastewater treatment system according to claim 1, characterized in that: The amount of the concentrate extracted from the concentrate filtered out by the inorganic membrane filter accounts for 10% of the amount of the clear liquid filtered out by the inorganic membrane filter.

3. The methanol to olefins wastewater treatment system according to claim 1, characterized in that: A quenching water booster pump is provided on the pipeline between the filter circulation tank and the quenching tower. The quenching water booster pump is used to pressurize the quenching water to be treated in the quenching tower and then transport it to the filter circulation tank.

4. The methanol to olefins wastewater treatment system according to claim 1, characterized in that: A membrane filtration circulation pump is provided on the pipeline between the inorganic membrane filter and the filtration circulation tank, and the membrane filtration circulation pump is used to drive quenching water to circulate between the inorganic membrane filter and the filtration circulation tank.

5. The methanol to olefins wastewater treatment system according to any one of claims 2 to 4, characterized in that: Also includes: A plate-frame filter press, wherein the plate-frame filter press is connected to the quench water concentrate storage tank via a pipeline, so as to transport the concentrated liquid in the quench water concentrate storage tank to the plate-frame filter press for compression and filtration; A screw conveyor, the screw conveyor is connected to the plate and frame filter press, so that the filter cake compressed by the plate and frame filter press is conveyed to the waste hopper through the screw conveyor; A plate and frame filtered liquid storage tank is connected to the plate and frame filter press via a pipeline so that the clear liquid filtered by the plate and frame filter press is transported to the plate and frame filtered liquid storage tank. The plate and frame filtered liquid storage tank is also connected to the quenching tower via a pipeline so that the clear liquid is transported back to the quenching tower for recycling.

6. The methanol to olefins wastewater treatment system according to claim 5, characterized in that: A concentrate booster pump is provided on the pipeline between the plate-frame filter press and the quench water concentrate storage tank, and the concentrate booster pump is used to pressurize the concentrate in the quench water concentrate storage tank and then transport it to the plate-frame filter press.

7. The methanol to olefins wastewater treatment system according to claim 5, characterized in that: A plate-frame clear liquid booster pump is provided on the pipeline between the plate-frame clear liquid storage tank and the quenching tower, and the plate-frame clear liquid booster pump is used to pressurize the clear liquid in the plate-frame clear liquid storage tank and then transport it to the quenching tower.

8. The methanol to olefins wastewater treatment system according to any one of claims 6 and 7, characterized in that: It also includes a steam supply device, which is connected to the inorganic membrane filter via a pipeline to purge the inorganic membrane filter with steam.

9. The methanol to olefins wastewater treatment system according to claim 8, characterized in that: Also includes: an alkaline washing liquid tank, the alkaline washing liquid tank being connected to the inorganic membrane filter via a pipeline so as to use the alkaline washing liquid to wash the inorganic membrane filter; A pickling liquid tank, the pickling liquid tank is connected to the inorganic membrane filter via a pipeline, so as to use the pickling liquid to clean the inorganic membrane filter; A nitrogen supply device, wherein the nitrogen supply device is connected to the inorganic membrane filter via a pipeline so as to use nitrogen to purge the inorganic membrane filter after alkali washing or acid washing; A fresh water supply device, the fresh water supply device is connected to the inorganic membrane filter via a pipeline, so as to use fresh water to rinse the inorganic membrane filter after alkali washing or acid washing; A desalted water supply device is connected to the inorganic membrane filter via a pipeline so as to use the desalted water to flush the inorganic membrane filter after alkali washing or acid washing.

10. A method for treating methanol to olefins wastewater, characterized in that: The treatment method is used in the methanol to olefins wastewater treatment system according to claim 9, and the treatment method comprises: The quench water to be treated is pumped to the filter circulation tank, the quench water in the filter circulation tank is pumped to the inorganic membrane filter for filtration, the filtered clear liquid is transported to the stripping tower, the concentrated liquid returns to the filter circulation tank for continuous circulation, and a part of the concentrated liquid is sent to the plate and frame filter press to filter the catalyst; After the inorganic membrane filter runs for a preset cycle, the inorganic ceramic membrane of the inorganic membrane filter is regenerated. During the regeneration process, it goes through drainage, steam purging, alkali washing and nitrogen purging, fresh water flushing, acid washing and nitrogen purging, fresh water flushing, and desalted water flushing in sequence.

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