Device and method for removing yellow grease and pretreating coal-to-olefin waste lye

Abstract

The application discloses a device and method for removing yellow grease and pretreating coal-to-olefin waste alkali liquor, wherein the treatment device comprises a yellow grease remover, a yellow grease tank, a buffer tank, a sulfuric acid filling bag, a catalyst filling bag, an ozone oxidation reactor A, an ozone oxidation reactor B, an ozone generator and a catalyst recovery device. The treatment device and method can automatically remove yellow grease by water power and automatically discharge yellow grease by instruments, and are more flexible in operation. In addition, a pipeline for returning waste alkali at the bottom of the yellow grease tank to the yellow grease remover is additionally arranged, ozone catalytic oxidation is carried out on the waste alkali liquid after yellow grease removal, most of the organic matters are removed, the catalyst is recycled, the effluent water meets the receiving requirements of a sewage treatment plant, and the treatment load of the sewage treatment plant is reduced.

Description

Technical Field

[0001] This invention relates to an apparatus and method for removing grease and pretreatment of coal-to-olefins waste alkaline solution. Background Technology

[0002] The alkaline washing section of a coal-to-olefins plant generates a stream of waste alkaline liquid. Some companies treat this waste alkaline liquid by incineration, while others use wet air oxidation. However, both methods suffer from problems such as high investment, high operating costs, severe blockage, and unstable operation.

[0003] Unsaturated hydrocarbons in waste alkaline solutions undergo free radical reactions under trace oxygen conditions, generating cross-linked polymers. Additionally, oxygen-containing compounds such as aldehydes and ketones in the waste alkaline solutions undergo aldol condensation reactions under alkaline conditions, also forming high-molecular-weight polymers commonly known as "butter." Butter is highly viscous, has poor flowability, and easily clogs equipment and pipes. Furthermore, waste alkaline solutions have high salt content, complex organic pollutant compositions, poor biodegradability, and cannot be directly received by wastewater treatment plants.

[0004] For waste alkali liquid from coal-to-olefins plants, there are domestic cases of directly incinerating it at around 1100℃. However, direct incineration of waste alkali liquid from coal-to-olefins plants presents several challenges: the large volume of waste alkali liquid leads to high investment in incinerators, high operating costs, and a large amount of hazardous waste generated; grease can adhere to nozzles, causing blockages; at high temperatures, molten sodium carbonate can adhere to furnace tubes, causing coking and blockages in the waste heat recovery boiler and quench tower; refractory materials suffer from molten salt corrosion; and the incineration equipment requires frequent shutdowns for maintenance, hindering normal and stable operation.

[0005] Because waste alkaline solutions contain a large amount of grease, methods such as membrane separation, flotation, electrocatalytic oxidation, and strong chemical oxidation cannot operate stably for extended periods. Therefore, the primary task in treating coal-to-olefins waste alkaline solutions is to pretreat the waste alkaline solutions to remove the grease. Only by removing the grease from the waste alkaline solutions can subsequent treatment be facilitated.

[0006] While adding butter inhibitors and optimizing process parameters can reduce the amount of butter produced to some extent, a significant amount still remains. Methods for butter removal include physical separation methods such as gravity separation, coalescence separation, and drum separation; however, due to their respective advantages and disadvantages, these methods have not been widely adopted.

[0007] Currently, in the absence of a suitable technology for treating coal-to-olefins waste alkali, some companies have opted for carbon dioxide adsorption. This process uses a multi-tower alternating adsorption method, which is relatively complex to operate and control, requires a large investment in adsorption and regeneration facilities, and has an adsorbent lifespan of about one year with a short replacement cycle.

[0008] In view of the problems existing in the treatment of coal-to-olefins waste alkaline liquid, it is of great significance to develop a method that can operate stably and continuously, effectively remove grease from the waste alkaline liquid, and allow the grease-free waste alkaline liquid to meet the requirements of wastewater treatment after simple pretreatment. Summary of the Invention

[0009] To address the problems in the prior art, the present invention aims to provide an apparatus and method for removing grease and pretreating coal-to-olefins waste alkaline solution. It can perform fully automated hydraulic grease removal or instrument-controlled grease discharge, offering greater operational flexibility. Furthermore, a pipeline is added to return waste alkali from the bottom of the grease tank to the grease remover. The waste alkaline solution undergoes ozone catalytic oxidation to remove most of the organic matter, the catalyst is recycled, and the waste alkaline solution meets the requirements for wastewater treatment plant acceptance.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A device for removing grease and pretreating coal-to-olefins waste alkaline solution, characterized in that the treatment device comprises:

[0012] The lower part of the grease remover is a vertical flat-top tank, and the top is a straight cylindrical section. The grease remover is equipped with a water distribution ring pipe, which is connected to three water distribution connecting pipes at 120° intervals. The water distribution ring pipe has evenly distributed upward-facing water distribution holes. The connection point of the water distribution connecting pipe is connected to one end of the inlet connecting pipe. The other end of the inlet connecting pipe is equipped with a waste alkali inlet for waste alkali to flow in. Oil and water separation is achieved through the density difference between grease and waste alkali. The upper part of the grease remover contains grease, and the lower part contains grease-removing waste alkali. The outlet connecting pipe is connected to the connection point of eight water collection pipes at 45° intervals. The water collection pipes have evenly distributed downward-facing water collection holes. The outlet connecting pipe is connected, from top to bottom, to a siphon inlet, a grease-removing waste alkali outlet, and a water collection pipe. The straight cylindrical section of the grease remover has an oil outlet, which is connected to the grease outlet of the grease remover via a grease discharge pipe. The grease outlet is connected to a grease tank via a grease delivery pipeline.

[0013] The grease tank has a cylindrical body that changes from round to square, with an angle of 20°-35° between the cylindrical body and the storage tank wall. A grease inlet is provided on the side wall of the cylindrical body for inputting and storing the grease from the grease remover. A grease outlet is provided at the bottom of the cylindrical body, and the grease outlet is connected to the inlet of a screw pump through a valve. The screw pump supplies grease for bagging.

[0014] The buffer tank is connected to the outlet of the degreased waste alkali solution for input. The buffer tank is also connected to the sulfuric acid injection package, through which sulfuric acid is injected to adjust the pH value of the degreased waste alkali solution. The buffer tank is connected to the waste alkali solution inlet of ozone oxidation reactor A via a buffer tank booster pump. Its connecting pipeline is also connected to a cooler, a catalyst injection package, and a catalyst recovery unit for cooling the degreased waste alkali solution. The cooled degreased waste alkali solution, along with the catalyst from the catalyst injection package and the catalyst recovery unit, is sent to ozone oxidation reactor A.

[0015] The ozone oxidation reactor A is equipped with a waste alkali inlet for the inflow of waste alkali for cooling and pH adjustment, catalyst, and reflux catalyst. A perforated water distribution pipe in the ozone oxidation reactor A ensures uniform distribution of the waste alkali. The outlet of the ozone oxidation reactor A is connected to the waste alkali inlet of the ozone oxidation reactor B. The perforated water distribution pipe in the ozone oxidation reactor B also ensures uniform distribution of the waste alkali. The ozone inlets of both the ozone oxidation reactor A and the ozone inlet of the ozone oxidation reactor B are connected to an ozone generator. A perforated gas distribution pipe ensures uniform distribution of the introduced ozone. This process breaks down and oxidizes the recalcitrant organic matter in the waste alkali, which is used to remove grease. The effluent from the ozone oxidation reactor B is connected to the catalyst recovery unit. The catalyst recovery unit is connected to the ozone oxidation reactor A via a catalyst reflux pump. The effluent from the catalyst recovery unit meets the receiving requirements of the wastewater treatment plant, reducing the treatment load on the wastewater treatment plant.

[0016] The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline liquid, wherein: the distance between the oil-water interface in the grease remover and the oil outlet is the oil layer thickness H, H=ρ×Δh / Δρ, where ρ is the density of the waste alkaline liquid in kg / m3, Δh is the vertical distance between the center of the oil outlet and the outlet of the grease-removed waste alkaline liquid in m, and Δρ is the density difference between the waste alkaline liquid and grease in kg / m3; sight glasses a, b, c and d are sequentially arranged on the grease remover and are evenly distributed on the oil layer thickness H;

[0017] The top of the liquid outlet connecting pipe is respectively provided with a pressure gauge port, a breather valve port, a nitrogen seal port and an exhaust gas outlet. The straight section of the grease remover is provided with a grease return port, a level gauge upper port and a grease remover gas connection port in sequence from bottom to top. The grease remover is provided with an upper maintenance manhole and a lower maintenance manhole. The lower part of the grease remover is provided with a level gauge lower port, a temperature instrument port and a utility port in sequence from top to bottom.

[0018] The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline liquid, wherein: the grease remover is a vertical flat-top tank with a diameter of D and a height of L; the vertical distance between the bottom of the grease remover and the water distribution ring pipe is H1, where H1 = (0.45-0.55)L; the distance between the water collection pipe and the bottom of the grease remover is H2, where H2 = 0.3-0.6m; and the vertical distance between the oil outlet of the straight section of the grease remover and the top of the vertical flat-top tank is H3, where H3 ≥ 1.5m.

[0019] The grease discharge pipe makes an angle of 25°-35° with the axis, and the grease outlet is located on the central axis of the straight section of the grease remover;

[0020] Another structure of the grease remover is a spherical tank with a diameter of D. The vertical height between the bottom of the grease remover and the water distribution ring pipe is H1, where H1 = (0.5-0.55)D. The liquid outlet connecting pipe is connected from top to bottom to the siphon inlet, the grease removal waste alkali liquid outlet, and the liquid outlet. The liquid outlet and the vent outlet are positioned opposite each other. The distance between the liquid outlet and the bottom of the grease remover is H2, where H2 = 0.3-0.6m. The angle between the straight section of the grease remover and the axis is 25°-35°. The numbering and structure of other pipe ports are the same as those of the vertical flat-top tank. The structural forms of the grease remover also include vertical inclined-top tanks, vertical domed-top tanks, vertical conical-top tanks, vertical spherical-top tanks, and horizontal tanks. The upper straight section is arranged vertically or inclined.

[0021] The aforementioned apparatus for removing grease and pretreating coal-to-olefins waste alkaline liquid includes: an inlet water flow meter with a flow rate of F1 is installed at the inlet of the waste alkaline liquid; an outlet water flow meter with a flow rate of F2 is installed on the outlet connecting pipe; forced grease removal is performed when F2:F1 < 1, the grease level in the grease remover slowly rises, and the grease is discharged into the grease tank through the grease discharge pipe; when the grease in the grease tank reaches a preset level L1, F2:F1 > 1 is set, and the grease level in the grease remover slowly drops to the normal level, at which point the forced grease removal ends.

[0022] The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline liquid, wherein: the surface hydraulic load of the maximum cross-section inside the grease remover is 0.02-0.1 m3 / (m2•h), preferably, the surface hydraulic load inside the grease remover is 0.03-0.06 m3 / (m2•h).

[0023] The aforementioned apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution, wherein: the waste alkaline solution refers to waste alkaline solution with sodium hydroxide (NaOH) between 1-2 wt%, sodium carbonate (Na2CO3) between 1.5-4 wt%, grease between 2500-6000 mg / L, chemical oxygen demand (COD) between 8000-20000 mg / L, TDS between 40000-80000 mg / L, and pH between 13-14.

[0024] The aforementioned apparatus for removing grease and pretreating coal-to-olefins waste alkaline liquid includes the following: all pipe walls in contact with grease and the inner wall of the grease tank are lined with an oleophobic material to reduce grease adhesion. The oleophobic material is polytetrafluoroethylene (PTFE), silicone, fluorinated ethylene propylene copolymer (FEP), or perfluoroalkoxy resin (PFA). The grease remover, the grease tank, and their inlet and outlet pipelines are all heated by steam, hot water, or electric heating, with the temperature maintained at 35-45°C. Preferably, the heating is electric, with the temperature maintained at 38-42°C.

[0025] The apparatus for removing grease and pretreating coal-to-olefins waste alkaline liquid includes: a gas connection port, a liquid level instrument port, and an observation port sequentially arranged on the top of the grease tank; a temperature instrument port arranged on the side wall of the grease tank; a manhole with a sight glass arranged at the bottom of the grease tank; and the bottom of the grease tank connected to the grease remover via a return pipeline, allowing the waste alkaline liquid at the bottom of the grease tank to return to the grease remover.

[0026] The apparatus for removing grease and pretreating coal-to-olefins waste alkaline solution includes: sulfuric acid injected into the connecting pipeline between the grease remover and the buffer tank to adjust the pH value to 7-9, preferably, the pH value of the waste alkaline solution is adjusted to 7.5-8.5, and the cooler reduces the temperature of the waste alkaline solution to 25-35℃.

[0027] The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution, wherein: the catalyst is an iron-containing catalyst, which is one or a mixture of all iron-containing compounds that can produce Fe2+ or Fe3+, preferably, the iron-containing catalyst is a water-soluble chelate containing Fe2+ or Fe3+; the dosage of the catalyst is such that the iron ion content in the waste alkaline solution is 30-200 mg / L, preferably, the dosage of the catalyst is such that the iron ion content in the waste alkaline solution is 100 mg / L.

[0028] The apparatus for removing grease and pretreating coal-to-olefins waste alkaline liquid, wherein: the lower part of the ozone oxidation reactor is integrated with a buffer tank, or the ozone oxidation reactor is set separately, with a diameter of D;

[0029] The ozone oxidation reactor A and the ozone oxidation reactor B are respectively provided with a top manhole, a waste gas outlet, and a breathing valve. The side walls of the ozone oxidation reactor A and the ozone oxidation reactor B are respectively provided with a waste alkali inlet, an ozone inlet, a water outlet, an air outlet, a bottom manhole, a water distribution perforated pipe, and a gas distribution perforated pipe.

[0030] A method for removing grease and pretreating coal-to-olefins waste alkaline liquor using the processing apparatus as described in any one of claims 1-11, characterized by comprising the following steps:

[0031] Step 1: The waste alkaline liquid from coal-to-olefins is transported to the degreaser. The waste alkaline liquid containing grease flows into the degreaser through the water distribution hole and is left to stand. The density difference between the grease and the waste alkaline liquid is used to separate the oil and water. The upper part of the degreaser contains grease, and the lower part contains the waste alkaline liquid containing grease.

[0032] Step 2: The separated butter flows into the butter tank for collection. When the butter in the butter tank reaches the preset maximum liquid level L2, the screw pump is started. The waste alkali liquid at the bottom of the butter tank is first returned to the degreaser through the return pipeline. When the butter in the butter tank reaches the liquid level L3, the return pipeline is closed and the butter is bagged. After the butter is bagged, the bagging pipeline and the return pipeline are purged with nitrogen.

[0033] Step 3: After the processing in Step 1 and Step 2, the waste alkali solution for removing grease in the grease remover flows into the buffer tank. The sulfuric acid injection bag injects sulfuric acid into the outlet pipeline of the grease remover to adjust the pH value of the waste alkali solution for removing grease to 7-9.

[0034] Step 4: The degreased alkali solution with adjusted pH is pumped into ozone oxidation reactor A. A cooler is installed in the connecting pipeline to cool the temperature of the degreased alkali solution to 25-35℃. The cooled degreased alkali solution, together with the catalyst from the catalyst injection package and catalyst recovery unit, is sent into ozone oxidation reactor A. The effluent flows by gravity to ozone oxidation reactor B. The ozone generator introduces ozone into ozone oxidation reactor A and ozone oxidation reactor B to break down and oxidize the recalcitrant organic matter in the degreased alkali solution. Ozone is aerated using perforated pipes.

[0035] Step 5: The oxidized waste alkaline solution after removing the grease flows into the catalyst recovery unit for degassing and precipitation separation. The recovered catalyst is returned to the ozone oxidation reactor A, and the effluent meets the receiving requirements of the wastewater treatment plant.

[0036] The beneficial effects of this invention are:

[0037] 1. For coal-to-olefins waste alkaline liquor, the main problem with current industrialized treatment processes is the grease blockage at the front end. This invention employs multiple measures to effectively solve the equipment and pipeline blockage problem. Under nitrogen blanketing conditions, the grease remover, grease tank, and their inlet and outlet pipelines are all heated to improve grease flowability; a specially designed separation device is used for non-powered separation of grease from the waste alkaline liquor; the pipe walls and inner walls of the grease tank in contact with grease are lined with oleophobic materials to prevent grease adhesion and blockage during transportation; the lower part of the grease remover is a full tank, while the upper straight section has a small gas phase space, resulting in high volume utilization and a large grease layer thickness, which is beneficial for grease dehydration and facilitates grease discharge.

[0038] 2. This invention makes full use of the pressure resistance characteristics of cylindrical or spherical tanks. The drain outlet of the waste alkali solution for removing grease and the grease discharge outlet are placed at an appropriate height above the highest point of the cylindrical or spherical tank. By utilizing the full volume of the cylindrical or spherical tank, a larger oil layer thickness and the longest possible residence time of the waste alkali solution for removing grease are obtained with a smaller amount of grease stored, thus achieving ideal separation of grease and waste alkali solution and convenient removal of grease.

[0039] 3. This invention removes the butter from the waste alkali solution, and the butter is bagged, which reduces the COD of the waste alkali solution and creates favorable conditions for further treatment.

[0040] 4. This invention removes the grease from the waste alkali solution, and uses ozone catalytic oxidation to remove most of the organic matter. The catalyst is recovered and reused, saving operating costs. The effluent meets the receiving requirements of wastewater treatment plants, reducing the treatment load on these plants. Compared to directly incinerating the waste alkali solution at 1100℃, this method has lower energy consumption, significantly reducing operating costs and saving investment. Attached Figure Description

[0041] Figure 1 This is a flowchart of the process for removing grease and pretreatment of coal-to-olefins waste alkaline solution;

[0042] Figure 2 This is a process flow diagram of the removal of grease and pretreatment of coal-to-olefins waste alkaline liquor;

[0043] Figure 3 This is a structural diagram of a grease remover (vertical flat-topped can);

[0044] Figure 4 This is a structural diagram of a grease remover (spherical container);

[0045] Figure 5 This is a structural diagram of the water distribution ring pipe for grease removers (vertical flat-top tanks and spherical tanks);

[0046] Figure 6 This is a structural diagram of the water collection pipe of the grease remover (vertical flat-top tank);

[0047] Figure 7This is a schematic diagram of the structure of the grease remover in this invention;

[0048] Figure 8 This is a diagram of the grease groove structure;

[0049] Figure 9 This is a diagram of the lower square tube structure of the grease groove;

[0050] Figure 10 This is a diagram of the lower part of the grease groove, which is a circular shape that transforms into a square shape.

[0051] Figure 11 This is a structural diagram of ozone oxidation reactor A and buffer tank;

[0052] Figure 12 This is a structural diagram of ozone oxidation reactor B;

[0053] Explanation of reference numerals in the attached diagram: Grease remover -1, Waste alkali inlet -101, Drain -102, Waste alkali outlet for grease remover -103, Grease outlet of grease remover -104, Siphon breaker interface -105, Grease return port -106, Gas connection port of grease remover -107, Upper port of level gauge -108, Lower port of level gauge -109, Temperature instrument port -110, Utility port -111, Pressure instrument port -112, Breather valve port -113, Nitrogen seal port -114, Emergency relief port -115. Exhaust gas outlet-116, upper maintenance manhole-117, lower maintenance manhole-118, sight glass a-119, sight glass b-120, sight glass c-121, sight glass d-122, water inlet connecting pipe-1501, water distribution connecting pipe-1502, water distribution ring pipe-1503, water distribution hole-1504, liquid outlet connecting pipe-1505, liquid outlet-1506, grease drain pipe-1507, oil outlet-1508, water collection pipe-1509, water collection hole-1510; grease tank-2, cylinder-201. Butter Inlet - 202, Butter Outlet of Butter Tank - 203, Gas Connection Port of Butter Tank - 204, Temperature Instrument Port - 205, Liquid Level Instrument Port - 206, Observation Port - 207, Manhole with Sight Glass - 208, Valve - 209, Screw Pump - 210, Buffer Tank - 3, Buffer Tank Lifting Pump - 301, Inlet Flow Meter - 401, Outlet Flow Meter - 501, Outlet Regulating Valve - 502, Cooler - 503, Sulfuric Acid Filling Bag - 6, Catalyst Filling Bag - 7, Ozone Oxidation Reactor A - 8 Ozone oxidation reactor B-9, waste alkali inlet-802 / 902, ozone inlet-801 / 901, water outlet-803 / 903, vent outlet-804 / 904, bottom manhole-805 / 905, manhole-806 / 906, exhaust gas outlet-807 / 907, breather valve-808 / 908, water distribution perforated pipe-810 / 910, gas distribution perforated pipe-811 / 911, ozone generator-10, catalyst recovery unit-11, catalyst return pump-1101. Detailed Implementation

[0054] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0055] like Figures 1 to 12 The apparatus shown is a device for removing grease and pretreating coal-to-olefins waste alkaline solution, characterized in that the treatment device comprises:

[0056] The lower part of the grease remover 1 is a vertical flat-topped tank, and its top is a straight cylindrical section. The diameter of the grease remover 1 is D, and its height is L. The distance between the oil-water interface inside the grease remover 1 and the oil outlet 1508 is the oil layer thickness H, where H = ρ × Δh / Δρ, where ρ is the density of the waste alkali solution in kg / m3, Δh is the vertical distance between the center of the oil outlet 1508 and the center of the grease-removing waste alkali solution outlet 103 in meters, and Δρ is the density difference between the waste alkali solution and the grease in kg / m3. Sight glasses a119, b120, c121, and d122 are sequentially arranged on the grease remover 1 and are evenly distributed on the oil layer thickness H. The surface hydraulic load of the largest cross-section inside the grease remover 1 is 0.02-0.1 m³ / (m²•h), preferably 0.03-0.06 m³ / (m²•h). A water distribution ring pipe 1503 is installed inside the grease remover 1. The vertical height between the bottom of the grease remover 1 and the water distribution ring pipe 1503 is H1, where H1 = (0.45-0.55)L. The water distribution ring pipe 1503 is connected to three water distribution connecting pipes 1502 at 120° intervals. Water distribution holes 1504 with upward openings are evenly distributed on the water distribution ring pipe 1503. The connection point of the water distribution connecting pipes 1502 is connected to... One end of the inlet pipe 1501 is connected to a waste alkali inlet 101, which is provided at the other end for the waste alkali to flow in. Oil and water are separated by the density difference between the grease and the waste alkali. The upper part of the grease remover 1 contains grease, and the lower part contains the grease-removing waste alkali. The outlet pipe 1505 is connected to the connection point of eight water collection pipes 1509 at 45° intervals. The water collection pipes 1509 are evenly distributed with downward-facing water collection holes 1510. The top of the outlet pipe 1505 is provided with a pressure gauge port 112, a breather valve port 113, a nitrogen sealing port 114, and a waste gas outlet 116. The outlet pipe 1505 is arranged from top to bottom as follows: The degreaser 1 is connected to the siphon inlet 105, the waste alkali outlet 103, and the water collection pipe 1509. The distance between the water collection pipe 1509 and the bottom of the degreaser 1 is H2, where H2 = 0.3-0.6m. The straight section of the degreaser 1 is provided with an oil outlet 1508, which is connected to the grease outlet 104 of the degreaser through a grease discharge pipe 1507. The grease outlet 104 is connected to the grease tank 2 through a grease conveying pipeline. The angle between the straight section of the degreaser 1 and the axis is 25°-35°. The vertical distance between the oil outlet 1508 of the straight section of the degreaser 1 and the top of the flat-top tank is H3, where H3 ≥ 1.The grease drain pipe 1507 is 5m long, and the angle between the drain pipe 1507 and the axis is 25°-35°. The oil outlet 1508 is located on the central axis of the straight section of the grease remover 1. From bottom to top, the straight section of the grease remover 1 is provided with a grease return port 106, a level gauge upper port 108, and a grease remover air connection port 107. The grease remover 1 is provided with an upper maintenance manhole 117 and a lower maintenance manhole 118. From top to bottom, the lower part of the grease remover 1 is provided with a level gauge lower port 109, a temperature instrument port 110, and a utility port 111.

[0057] Another structure of the grease remover 1 is a spherical tank with a diameter of D. The vertical height between the bottom of the grease remover 1 and the water distribution ring pipe 1503 is H1, where H1 = (0.5-0.55)D. The liquid outlet connecting pipe 1505 is connected from top to bottom to the siphon inlet 105, the grease-removing waste alkali liquid outlet 103, and the liquid outlet 1506. The liquid outlet 1506 corresponds to the position of the vent outlet 102. The distance between the liquid outlet 1506 and the bottom of the grease remover 1 is H2, where H2 = 0.3-0.6m. The angle between the straight section of the grease remover 1 and the axis is 25°-35°. The other pipe port numbers and structures are consistent with those of the vertical flat-top tank. The structural forms of the grease remover 1 also include vertical inclined-top tanks, vertical domed-top tanks, vertical conical-top tanks, vertical spherical-top tanks, and horizontal tanks, with the upper straight section arranged vertically or inclined.

[0058] The grease tank 2 has a cylindrical body 201 that is rounded and then squared. The angle between the cylindrical body 2 and the storage tank wall is 20°-35°. A grease inlet 202 is provided on the side wall of the cylindrical body 201 for the input and storage of grease from the grease remover 1. A grease outlet 203 is provided at the bottom of the cylindrical body 201. The grease outlet 203 is connected to the inlet of the screw pump 210 through a valve 209. The screw pump 210 supplies grease for bagging. The top of the grease tank 2 is provided with a gas connection port 204, a liquid level gauge port 206, and an observation port 207. A temperature gauge port 205 is provided on the side wall of the grease tank 2. A manhole 208 with a sight glass is provided at the bottom of the grease tank 2. The bottom of the grease tank 2 is connected to the grease remover 1 through a return pipeline for the waste alkali solution at the bottom of the grease tank 2 to return to the grease remover 1.

[0059] The outlet 103 of the degreased waste alkali solution is connected to the buffer tank 3 for inputting the degreased waste alkali solution. The buffer tank 3 is connected to the sulfuric acid injection package 6. Sulfuric acid is injected into the pipeline connecting the degreaser 1 and the buffer tank 3 to adjust the pH value of the degreased waste alkali solution to 7-9. Preferably, the pH value of the waste alkali solution is adjusted to 7.5-8.5. The buffer tank 3 is connected to the waste alkali solution inlet 802 of the ozone oxidation reactor A8 through the buffer tank lift pump 301. Its connecting pipeline is also connected to the cooler 503, the catalyst injection package 7, and the catalyst recovery unit 11 for cooling the degreased waste alkali solution. The cooled degreased waste alkali solution, together with the catalyst from the catalyst injection package 7 and the catalyst recovery unit 11, is sent to the ozone oxidation reactor 8.

[0060] The ozone oxidation reactor A8 is equipped with a waste alkali inlet 802 for the inflow of waste alkali, catalyst, and reflux catalyst for cooling and pH adjustment. A perforated water distribution pipe 810 in the ozone oxidation reactor A8 ensures uniform distribution of the waste alkali. The outlet 803 of the ozone oxidation reactor A8 is connected to the waste alkali inlet 902 of the ozone oxidation reactor B9. A perforated water distribution pipe 910 in the ozone oxidation reactor B9 ensures uniform distribution of the waste alkali. The ozone inlet 801 of the ozone oxidation reactor A8D and the ozone inlet 901 of the ozone oxidation reactor B9 are connected to the ozone generator 10. Perforated gas distribution pipes 811 / 911 ensure uniform distribution of the introduced ozone. This process breaks down and oxidizes the recalcitrant organic matter in the waste alkali, which is used to remove grease. The lower part of the ozone oxidation reactor may be equipped with an integrated buffer tank or a separate ozone oxidation reactor, with a diameter of D. The ozone oxidation reactors A8 and B9... The ozone oxidation reactors A8 and B9 are respectively equipped with a top manhole 806 / 906, an exhaust gas outlet 807 / 907, and a breather valve 808 / 908. The side walls of the ozone oxidation reactors A8 and B9 are respectively equipped with a waste alkali inlet 802 / 902, an ozone inlet 801 / 901, a water outlet 803 / 903, an air outlet 804 / 904, a bottom manhole 805 / 905, a water distribution perforated pipe 810 / 910, and an air distribution perforated pipe 811 / 911.

[0061] The effluent from outlet 903 of ozone oxidation reactor 9 is connected to catalyst recovery unit 11; catalyst recovery unit 11 is connected to ozone oxidation reactor 8 through catalyst return pump, and the effluent from catalyst recovery unit 11 meets the receiving requirements of wastewater treatment plant, reducing the treatment load of wastewater treatment plant.

[0062] A flow meter 401 with a flow rate of F1 is installed at the waste alkali inlet 101, and a flow meter 501 with a flow rate of F2 is installed on the outlet connecting pipe. Forced grease removal is performed when F2:F1 < 1. The grease level in the grease remover 1 rises slowly, and the grease is discharged into the grease tank 2 through the grease discharge pipe 1507. When the grease tank 2 reaches the preset level L1, F2:F1 > 1 is set, and the grease level in the grease remover 1 slowly drops to the normal level, thus ending the forced grease removal.

[0063] The waste alkaline solution refers to a waste alkaline solution with sodium hydroxide (NaOH) between 1-2 wt%, sodium carbonate (Na2CO3) between 1.5-4 wt%, butter between 2500-6000 mg / L, chemical oxygen demand (COD) between 8000-20000 mg / L, TDS between 40000-80000 mg / L, and pH between 13-14.

[0064] All pipe walls in contact with grease and the inner wall of the grease tank 2 are lined with an oleophobic material to reduce grease adhesion. The oleophobic material is polytetrafluoroethylene (PTFE), silicone, fluorinated ethylene propylene copolymer (FEP), or perfluoroalkoxy resin (PFA). The grease remover 1, the grease tank 2, and their inlet and outlet pipelines are all heated by steam, hot water, or electric heating, and the temperature is maintained at 35-45°C. Preferably, the heating is electric heating, and the temperature is maintained at 38-42°C.

[0065] The catalyst is an iron-containing catalyst, which is one or a mixture of all iron-containing compounds that can produce Fe2+ or Fe3+. Preferably, the iron-containing catalyst is a water-soluble chelate containing Fe2+ or Fe3+. The dosage of the catalyst is such that the iron ion content in the waste alkaline solution is 30-200 mg / L. Preferably, the dosage of the catalyst is such that the iron ion content in the waste alkaline solution is 100 mg / L.

[0066] A method for removing grease and pretreating coal-to-olefins waste alkaline liquor, characterized by comprising the following steps:

[0067] Step 1: The waste alkaline liquid from coal-to-olefins is transported to the degreaser 1. The waste alkaline liquid containing grease flows into the degreaser 1 through the water distribution hole 1504 and is left to stand. The density difference between the grease and the waste alkaline liquid is used to separate the oil and water. The upper part of the degreaser 1 contains grease, and the lower part contains the waste alkaline liquid containing grease.

[0068] Step 2: The separated butter flows into the butter tank 2 for collection. When the butter in the butter tank 2 reaches the preset maximum liquid level L2, the screw pump 210 is started. First, the waste alkali liquid at the bottom of the butter tank 2 is returned to the degreaser 1 through the return pipeline. When the butter in the butter tank 2 reaches the liquid level L3, the return pipeline is closed, and the butter is bagged. After the butter is bagged, the bagging pipeline and the return pipeline are purged with nitrogen.

[0069] Step 3: After the processing in Step 1 and Step 2, the waste alkali solution for removing grease in the grease remover 1 flows into the buffer tank 3. The sulfuric acid injection bag 6 injects sulfuric acid into the outlet pipeline of the grease remover 1 to adjust the pH value of the waste alkali solution for removing grease to 7-9.

[0070] Step 4: The degreased alkali solution with adjusted pH is sent to ozone oxidation reactor A8 via booster pump 301. A cooler is installed in the connecting pipeline to cool the temperature of the degreased alkali solution to 25-35℃. The cooled degreased alkali solution, along with the catalyst from catalyst injection package 7 and catalyst recovery unit 11, is sent into ozone oxidation reactor A8. The effluent flows by gravity to ozone oxidation reactor B9. Ozone generator 10 introduces ozone into ozone oxidation reactor A8 and ozone oxidation reactor B9 to break down and oxidize the organic matter in the degreased alkali solution that is difficult to biodegrade. Ozone is aerated using perforated pipes.

[0071] Step 5: The oxidized waste alkaline solution after removing the grease flows into the catalyst recovery unit 11 for degassing and sedimentation separation. The recovered catalyst is returned to the ozone oxidation reactor A8, and the effluent meets the receiving requirements of the wastewater treatment plant.

[0072] Example 1: Treatment of grease removal from coal-to-olefins waste alkaline liquor (spherical tank)

[0073] Waste alkali liquid from the alkali washing tower of a coal chemical plant is introduced into a grease remover 1 via the drain outlet. The grease remover 1 is a spherical tank with dimensions D=3m, H1=1.5m, H2=0.3m, H3=1.5m, and Δh=0.14m. The waste alkali liquid flow rate is controlled at 0.25 m³ / h. All pipe walls in contact with grease and the inner wall of the grease tank are lined with polytetrafluoroethylene (PTFE). The grease remover, grease tank, and their inlet and outlet pipelines are electrically heated to maintain a temperature of 38-42℃. After standing for several days, oil-water separation is performed using the density difference between the grease and the waste alkali liquid. The upper part of the grease remover 1 contains grease, and the lower part contains the grease-removed waste alkali liquid. The separated grease is either forcibly discharged or flows by gravity into the grease tank 2, which has dimensions of φ0.8×2m. The composition information of the waste alkali liquid in the buffer tank inlet pipeline is analyzed, and the results are listed in Table 1 below.

[0074] Table 1. Composition Information of Waste Alkali Solution

[0075]

[0076] “CODcr” represents chemical oxygen demand; “TDS” represents total dissolved solids (which may also be referred to as salt in this application).

[0077] On day 9, a flow meter is installed on the inlet pipeline of the grease remover, with a flow rate of F1. A flow meter and regulating valve are installed on the outlet pipeline of the grease remover's waste alkali solution, with a flow rate of F2. The forced grease removal is set to F2:F1=0.9, and the liquid level in the grease remover slowly rises, with the grease being discharged into the grease tank. When the grease tank reaches the designated liquid level of 1m, F2:F1=1.1 is set, and the liquid level in the grease remover slowly drops to the normal liquid level, ending the forced grease removal. On day 14, the grease accumulated at the top flows by gravity through the grease outlet to the grease tank. When it reaches the highest liquid level of 1.7m, the grease is bagged. First, the return line valve is opened, and the grease removal screw pump is started to return the waste alkali solution at the bottom of the grease tank to the grease remover. When the grease tank drops to the designated liquid level of 1.3m, the return line is closed, and the grease is bagged. After the grease is bagged, the bagging pipeline and the return pipeline are purged with nitrogen.

[0078] Example 2: Treatment and pretreatment of grease removal from coal-to-olefins waste alkaline liquor (vertical flat-top tank)

[0079] Waste alkali liquid from the alkali washing tower of a coal-to-olefins unit in a coal chemical enterprise is introduced into a degreasing tank 1. The degreasing tank is a vertical flat-top tank with dimensions of D=2.8m, L=3m, H1=1.6m, H2=0.3m, H3=1.5m, and Δh=0.2m. The waste alkali liquid flow rate is controlled at 0.3m³ / h. All pipe walls in contact with grease and the inner wall of the grease tank are lined with polytetrafluoroethylene (PTFE). The degreasing tank, grease tank, and their inlet and outlet pipelines are electrically heated to maintain a temperature of 38~42℃. After standing for several days, oil-water separation is performed using the density difference between grease and waste alkali liquid. The upper part of the degreasing tank 1 contains grease, and the lower part contains the degreased waste alkali liquid. The separated grease is discharged by forced discharge or by gravity into grease tank 2, which has dimensions of φ1×3m. The composition information of the waste alkali liquid in the buffer tank inlet pipeline is analyzed, and the results are listed in Table 1 below.

[0080] Table 1. Component Information of Waste Alkali Solution

[0081]

[0082] “CODcr” represents chemical oxygen demand; “TDS” represents total dissolved solids (which may also be referred to as salt in this application).

[0083] On day 20, a flow meter is installed on the inlet pipeline of the grease remover, with a flow rate of F1. A flow meter and regulating valve are installed on the outlet pipeline of the grease remover's waste alkali solution, with a flow rate of F2. The forced grease removal is set to F2:F1=0.95, and the liquid level in the grease remover slowly rises, with the grease being discharged into the grease tank. When the grease tank reaches the designated liquid level of 1.2m, F2:F1=1.1 is set, and the liquid level in the grease remover slowly drops to the normal liquid level, ending the forced grease removal. On day 25, the grease accumulated at the top flows by gravity through the grease outlet to the grease tank. When it reaches the highest liquid level of 2.5m, the grease is bagged. First, the return line valve is opened, and the grease removal screw pump is started to return the waste alkali solution at the bottom of the grease tank to the grease remover. When the grease tank drops to the designated liquid level of 2.2m, the return line is closed, and the grease is bagged. After the grease is bagged, the bagging pipeline and the return pipeline are purged with nitrogen.

[0084] After processing the grease, the waste alkali solution from the grease remover flows by gravity to buffer tank 3. Sulfuric acid injection package 6 injects concentrated sulfuric acid into the outlet pipeline of the grease remover 1, adjusting the pH to 7.5-8.5. The waste alkali solution enters buffer tank 3, and is then sent to ozone oxidation reactor A8 via buffer tank lift pump 301. Buffer tank 3, integrated at the bottom of the ozone oxidation reactor, has dimensions of φ0.75×2m. A cooler 503 is installed on the outlet pipeline of buffer tank lift pump 301, which lowers the temperature of the waste alkali solution to approximately 33℃. Catalyst injection package 7 then injects catalyst into buffer tank lift pump 301. Catalyst is injected into the outlet pipeline 01, and simultaneously fed into ozone oxidation reactor A8 along with the return catalyst from return pump 1101. The effluent from ozone oxidation reactor A8 flows by gravity to ozone oxidation reactor B9. Ozone is introduced into both reactors A8 and B9 via ozone generator 10 to break down and oxidize the recalcitrant organic matter in the waste alkaline solution. Both reactors A8 and B9 have a diameter of φ0.75×7m and are equipped with a 7kg / h ozone generator 10. Ozone aeration is achieved using perforated pipes. The hydraulic retention time for both reactors A8 and B9 is 17h. The effluent from reactor B9 flows by gravity to catalyst recovery unit 11. Catalyst recovery unit 11 returns the catalyst to the feed pipeline of reactor A8 via catalyst return pump 1101. The effluent from catalyst recovery unit 11 is sent to the wastewater treatment plant. The COD index of the effluent from catalyst recovery unit 11 is shown in Table 2 below.

[0085] Table 2. Catalyst recovery unit effluent data (unit: mg / L)

[0086]

[0087] The pilot plant performed grease removal treatment on coal-to-olefins waste alkaline liquor, proving the feasibility of the waste alkaline liquor treatment system. After three months of continuous and stable operation of the pilot plant, the equipment and pipelines were inspected. No blockage was found in the grease tank discharge pipeline, and the COD of the catalyst recovery unit effluent remained stable below 1200 mg / L.

[0088] As can be seen from the embodiments, the method for removing grease and pretreatment of coal-to-olefins waste alkaline solution according to the present invention is feasible.

[0089] The above embodiments are merely illustrative examples of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make simple modifications or substitutions based on the above embodiments without departing from the technical concept of the present invention, but these modifications or substitutions will still fall within the scope of protection of the present invention.

Claims

1. A device for removing grease and pretreating coal-to-olefins waste alkaline solution, characterized in that, The processing device includes: The lower part of the grease remover (1) is a vertical flat-top tank, and its top is a straight cylindrical section. The interior of the grease remover (1) is equipped with a water distribution ring pipe (1503), which is connected to three water distribution connecting pipes (1502) at 120° intervals. The water distribution ring pipe (1503) is evenly distributed with upward-facing water distribution holes (1504). The connection point of the water distribution connecting pipe (1502) is connected to one end of the water inlet connecting pipe (1501). The other end of the water inlet connecting pipe (1501) is equipped with a waste alkali inlet (101) for waste alkali to flow in. Oil and water are separated by the density difference between grease and waste alkali. The upper part of the grease remover (1) is grease, and its lower part is... The outlet pipe (1505) is connected to the connection point of eight water collection pipes (1509) at 45° angles to each other. The water collection pipes (1509) are evenly distributed with downward-facing water collection holes (1510). The outlet pipe (1505) is connected to the siphon port (105), the outlet of the waste alkali solution for removing grease (103), and the water collection pipes (1509) from top to bottom. The straight section of the grease remover (1) is provided with an oil outlet (1508). The oil outlet (1508) is connected to the grease outlet (104) of the grease remover through the grease discharge pipe (1507). The grease outlet (104) is connected to the grease tank (2) through the grease conveying pipeline. The cylindrical body (201) of the grease tank (2) is round to square. The angle between the cylindrical body (1) and the storage tank wall is 20°-35°. A grease inlet (202) is provided on the side wall of the cylindrical body (201) for the grease to be input and stored in the grease remover (1). A grease outlet (203) is provided at the bottom of the cylindrical body (201). The grease outlet (203) is connected to the inlet of the screw pump (210) through a valve (209). The screw pump (210) supplies grease for bagging. The buffer tank (3) is connected to the outlet (103) of the degreased waste alkali liquid for input. The buffer tank (3) is connected to the sulfuric acid injection bag (6) and sulfuric acid is injected through its connecting pipeline to adjust the pH value of the degreased waste alkali liquid. The buffer tank (3) is connected to the waste alkali liquid inlet (802) of the ozone oxidation reactor A (8) through the buffer tank lift pump (301). Its connecting pipeline is also connected to the cooler (503), the catalyst injection bag (7), and the catalyst recovery device (11) for cooling the degreased waste alkali liquid. The cooled degreased waste alkali liquid is sent to the ozone oxidation reactor A (8) together with the catalyst from the catalyst injection bag (7) and the catalyst recovery device (11). The ozone oxidation reactor A (8) is equipped with a waste alkali inlet (802) for the inflow of waste alkali, catalyst, and reflux catalyst for cooling and pH adjustment. The perforated water distribution pipe (810) of the ozone oxidation reactor A (8) provides uniform distribution of the waste alkali. The outlet (803) of the ozone oxidation reactor A (8) is connected to the waste alkali inlet (902) of the ozone oxidation reactor B (9). The perforated water distribution pipe (910) of the ozone oxidation reactor B (9) provides uniform distribution of the waste alkali. The ozone inlet (801) of the ozone oxidation reactor A (8) and the ozone oxidation... The ozone inlet (901) of reactor B (9) is connected to the ozone generator (10). The gas distribution perforated pipe (811 / 911) provides uniform distribution of the introduced ozone, which breaks down the chains of the organic matter that is difficult to biodegrade in the waste alkali solution of grease and performs ozone oxidation. The effluent outlet (903) of the ozone oxidation reactor B (9) is connected to the catalyst recovery unit (11). The catalyst recovery unit (11) is connected to the ozone oxidation reactor A (8) through the catalyst return pump. The effluent from the catalyst recovery unit (11) meets the receiving requirements of the sewage treatment plant and reduces the treatment load of the sewage treatment plant.

2. The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution as described in claim 1, characterized in that: The distance between the oil-water interface inside the degreaser (1) and the oil outlet (1508) is the oil layer thickness H, where H = ρ × Δh / Δρ, ρ is the density of the waste alkali solution in kg / m3, Δh is the vertical distance between the center of the oil outlet (1508) and the degreaser waste alkali solution outlet (103) in m, and Δρ is the density difference between the waste alkali solution and the grease in kg / m3. Sight glasses a (119), b (120), c (121) and d (122) are sequentially arranged on the degreaser (1) and are evenly distributed on the oil layer thickness H. The top of the liquid outlet connecting pipe (1505) is provided with a pressure instrument port (112), a breather valve port (113), a nitrogen sealing port (114) and a waste gas outlet (116). The straight section of the grease remover (1) is provided with a grease return port (106), a level gauge upper port (108) and a grease remover gas connection port (107) from bottom to top. The grease remover (1) is provided with an upper maintenance manhole (117) and a lower maintenance manhole (118). The lower part of the grease remover (1) is provided with a level gauge lower port (109), a temperature instrument port (110) and a utility port (111) from top to bottom.

3. The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution as described in claim 1, characterized in that: The grease remover (1) is a vertical flat-top tank with a diameter of D and a height of L. The vertical distance between the bottom of the grease remover (1) and the water distribution ring pipe (1503) is H1, where H1 = (0.45-0.55)L. The distance between the water collection pipe (1509) and the bottom of the grease remover (1) is H2, where H2 = 0.3-0.6m. The vertical distance between the oil outlet (1508) of the straight section of the grease remover (1) and the top of the vertical flat-top tank is H3, where H3 ≥ 1.5m. The grease discharge pipe (1507) has an angle of 25°-35° with the axis, and the oil outlet (1508) is located on the central axis of the straight section of the grease remover (1). Another structure of the grease remover (1) is a spherical tank with a diameter of D. The vertical height between the bottom of the grease remover (1) and the water distribution ring pipe (1503) is H1, where H1 = (0.5-0.55)D. The liquid outlet connecting pipe (1505) is connected from top to bottom to the siphon inlet (105), the grease removal waste alkali liquid outlet (103), and the liquid outlet (1506). The liquid outlet (1506) is located opposite to the vent (102). Correspondingly, the distance between the liquid outlet (1506) and the bottom of the grease remover (1) is H2, where H2 = 0.3~0.6m. The angle between the straight section of the grease remover (1) and the axis is 25°-35°. The numbering and structure of other pipe ports are consistent with those of the vertical flat-top tank. The structural forms of the grease remover (1) also include vertical inclined-top tanks, vertical domed-top tanks, vertical conical-top tanks, vertical spherical-top tanks, and horizontal tanks. The upper straight section is arranged vertically or inclined.

4. The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution as described in claim 1, characterized in that: A flow meter (401) with a flow rate of F1 is installed at the waste alkali inlet (101). A flow meter (501) with a flow rate of F2 is installed on the outlet connecting pipe. Forced grease removal is set to F2:F1<1. The grease level in the grease remover (1) rises slowly. The grease is discharged into the grease tank (2) through the grease discharge pipe (1507). When the grease in the grease tank (2) reaches the preset level L1, F2:F1>1 is set. The grease level in the grease remover (1) drops slowly to the normal level, and forced grease removal ends.

5. The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution as described in claim 1, characterized in that: The surface hydraulic load of the maximum cross-section inside the degreaser (1) is 0.02~0.1 m3 / (m2•h), preferably, the surface hydraulic load inside the degreaser (1) is 0.03~0.06 m3 / (m2•h).

6. The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution as described in claim 1, characterized in that: The waste alkaline solution refers to a waste alkaline solution containing 1-2 wt% sodium hydroxide (NaOH), 1.5-4 wt% sodium carbonate (Na2CO3), 2500-6000 mg / L butter, 8000-20000 mg / L chemical oxygen demand (COD), 40000-80000 mg / L total dissolved solids (TDS), and a pH between 13 and 14.

7. The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution as described in claim 1, characterized in that: All pipe walls in contact with the grease and the inner wall of the grease tank (2) are lined with oleophobic material to reduce grease adhesion. The oleophobic material is polytetrafluoroethylene (PTFE), silicone, fluorinated ethylene propylene copolymer (FEP) or perfluoroalkoxy resin (PFA). The grease remover (1), the grease tank (2) and its inlet and outlet pipelines are all heated by steam heating, hot water heating or electric heating, and the temperature is maintained at 35-45℃. Preferably, the heating is electric heating and the temperature is maintained at 38-42℃.

8. The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution as described in claim 1, characterized in that: The top of the grease tank (2) is provided with a gas connection port (204), a liquid level instrument port (206) and an observation port (207) in sequence. The side wall of the grease tank (2) is provided with a temperature instrument port (205). The bottom of the grease tank (2) is provided with a manhole with a sight glass (208). The bottom of the grease tank (2) is connected to the degreaser (1) through a return pipeline, so that the waste alkaline liquid at the bottom of the grease tank (2) can be returned to the degreaser (1).

9. The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution as described in claim 1, characterized in that: Sulfuric acid is injected into the connecting pipeline between the degreaser (1) and the buffer tank (3) to adjust the pH value to 7-9. Preferably, the pH value of the waste alkali solution is adjusted to 7.5-8.5, and the cooler (503) reduces the temperature of the waste alkali solution to 25-35°C.

10. The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution as described in claim 1, characterized in that: The catalyst is an iron-containing catalyst, which is one or a mixture of all iron-containing compounds that can produce Fe2+ or Fe3+. Preferably, the iron-containing catalyst is a water-soluble chelate containing Fe2+ or Fe3+. The dosage of the catalyst is such that the iron ion content in the waste alkaline solution is 30-200 mg / L. Preferably, the dosage of the catalyst is such that the iron ion content in the waste alkaline solution is 100 mg / L.

11. The apparatus for removing grease and pretreatment of coal-to-olefins waste alkaline solution as described in claim 1, characterized in that: The ozone oxidation reactor has an integrated buffer tank at the bottom, or the ozone oxidation reactor is set up separately, with a diameter of D; The ozone oxidation reactor A (8) and the ozone oxidation reactor B (9) are respectively provided with a top manhole (806 / 906), an exhaust gas outlet (807 / 907), and a breather valve (808 / 908). The side walls of ozone oxidation reactor A (8) and ozone oxidation reactor B (9) are respectively provided with waste alkali inlet (802 / 902), ozone inlet (801 / 901), water outlet (803 / 903), air outlet (804 / 904), bottom manhole (805 / 905), water distribution perforated pipe (810 / 910), and gas distribution perforated pipe (811 / 911).

12. A method for removing grease and pretreating coal-to-olefins waste alkaline liquor using the processing apparatus as described in any one of claims 1-11, characterized in that, Includes the following steps: Step 1: The waste alkaline liquid from coal-to-olefins is transported to the degreaser (1). The waste alkaline liquid containing grease flows into the degreaser (1) through the water distribution hole (1504) and is left to stand. The oil and water are separated by the density difference between the grease and the waste alkaline liquid. The upper part of the degreaser (1) contains grease, and the lower part contains the waste alkaline liquid containing grease. Step 2: The separated butter flows into the butter tank (2) for collection. When the butter in the butter tank (2) reaches the preset maximum liquid level L2, the screw pump (210) is started. First, the waste alkali liquid at the bottom of the butter tank (2) is returned to the degreaser (1) through the return pipeline. When the butter in the butter tank (2) reaches the liquid level L3, the return pipeline is closed and the butter is bagged. After the butter is bagged, the bagging pipeline and the return pipeline are purged with nitrogen. Step 3: After the processing of Step 1 and Step 2, the waste alkali liquid for removing grease in the grease remover (1) flows into the buffer tank (3), and the sulfuric acid injection bag (6) injects sulfuric acid into the outlet pipeline of the grease remover (1) to adjust the pH value of the waste alkali liquid for removing grease to 7-9. Step 4: The degreased alkali liquid with adjusted pH is sent to ozone oxidation reactor A (8) via booster pump (301). A cooler is installed in the connecting pipeline to cool the temperature of the degreased alkali liquid to 25-35℃. The cooled degreased alkali liquid, along with the catalyst from the catalyst injection package (7) and catalyst recovery unit (11), is sent into ozone oxidation reactor A (8). The effluent flows by gravity to ozone oxidation reactor B (9). Ozone generator (10) introduces ozone into ozone oxidation reactor A (8) and ozone oxidation reactor B (9) to break down and oxidize the organic matter in the degreased alkali liquid that is difficult to biodegrade. Ozone is aerated using perforated pipes. Step 5: The oxidized waste alkaline liquid after removing the grease flows into the catalyst recovery unit (11) for degassing and precipitation separation. The recovered catalyst is returned to the ozone oxidation reactor A (8), and the effluent meets the receiving requirements of the sewage treatment plant.

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