System and method for cooperatively treating high-COD (Chemical Oxygen Demand) wastewater and sludge through coal water slurry gasification

Abstract

The invention belongs to the technical field of coal chemical industry and environmental protection, and particularly discloses a system and method for co-processing high-COD wastewater and sludge through coal water slurry gasification. The mixing and conveying unit is used for mixing the mixed liquid of the pretreatment unit with coal slurry to form homogeneous slurry; a combustion control unit; sludge and high-COD wastewater are fully mixed through the pretreatment unit, then pretreated mixed liquid and coal slurry are mixed through the mixing and conveying unit to form homogeneous slurry, finally, the homogeneous slurry is atomized and then enters the gasification furnace, oxygen is introduced into the gasification furnace, the homogeneous slurry is fully combusted, and the high-COD wastewater is obtained. Homogeneous mixing and complete combustion of the high-COD wastewater, the biochemical sludge and the coal slurry are achieved, the treatment cost of the sludge and the high-COD wastewater is reduced, meanwhile, heat values and carbon in the sludge and the high-COD wastewater are recycled, the organic wastewater treatment efficiency is effectively improved, the property of the coal water slurry is not changed, and the yield of wet gas can be guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical fields of coal chemical industry and environmental protection, and particularly relates to a system and method for co - treating high - COD wastewater and sludge by water - coal slurry gasification. Background Art

[0002] High - COD wastewater mainly comes from the wastewater containing a large amount of organic pollutants and being difficult to be biodegraded, which is produced during the production process in the chemical industry with a large amount of organic raw materials and solvents used. Its COD (chemical oxygen demand) value is significantly higher than that of ordinary sewage.

[0003] Currently, during the co - treatment of organic wastewater by gasification, mainly organic wastewater or biochemical sludge is used to prepare water - coal slurry and then fed into a gasification furnace for combustion. For example, patent document CN117264671A discloses a method for modifying and reducing the viscosity of coal chemical sludge and blending it to prepare water - coal slurry, including the following steps: (1) Using aluminate - ammonium ferrous sulfate as a composite conditioner, coupling the composite conditioner with hydrothermal hydrolysis to reduce the viscosity of coal chemical sludge; (2) Blending the viscosity - reduced coal chemical sludge with coal powder, a slurry - making additive, and slurry - making water to prepare water - coal slurry. This invention uses a composite conditioner and hydrothermal hydrolysis coupling to treat coal chemical sludge. After modification, the viscosity of the coal chemical sludge is greatly reduced. When blending and preparing water - coal slurry, the addition amount of coal chemical sludge and the concentration of water - coal slurry are both significantly increased.

[0004] However, when directly mixing wastewater, sludge and coal to prepare slurry, stratification and pipeline blockage are likely to occur, affecting the fluidity and stability of the coal slurry, thus affecting the gasification effect of the coal slurry and reducing the quality of wet gas. Therefore, we need to propose a system and method for co - treating high - COD wastewater and sludge by water - coal slurry gasification to solve the above - mentioned problems, so as to effectively improve the treatment efficiency of organic wastewater, and without changing the properties of the water - coal slurry, ensure the output of wet gas. Summary of the Invention

[0005] The purpose of the present invention is to provide a system and method for co - treating high - COD wastewater and sludge by water - coal slurry gasification, which can effectively improve the treatment efficiency of organic wastewater, and without changing the properties of the water - coal slurry, ensure the output of wet gas, so as to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A system for co - treating high - COD wastewater and sludge by water - coal slurry gasification, comprising: a pretreatment unit, which fully mixes sludge and high - COD wastewater and breaks the cell walls in the biochemical sludge;

[0008] A mixing and conveying unit, which mixes the mixed liquid from the pretreatment unit with coal slurry to form a homogeneous slurry;

[0009] The combustion control unit atomizes the homogeneous slurry transported by the mixing and conveying unit through a burner and then sends it into the gasifier. Oxygen is introduced into the gasifier to enable the homogeneous slurry to burn sufficiently.

[0010] Preferably, the pretreatment unit includes a first static mixer, a buffer tank, and a delivery pump. The output end of the first static mixer is connected to the input end of the buffer tank, the output end of the buffer tank is connected to the input end of the delivery pump, and a double-layer paddle agitator is installed in the buffer tank to achieve full solid-liquid mixing by high-speed shearing and break the cell walls in the biochemical sludge.

[0011] Preferably, the delivery pump is a diaphragm pump. The flow rate of the delivery pump is 0.5 - 10 m 3 / h, the pressure is 4 - 6 MPa, and the particle diameter resistance is ≤ 5 mm.

[0012] Preferably, the input end of the first static mixer is respectively connected to a high-COD wastewater inlet pipe and a sludge inlet pipe. A flow meter F1 and a regulating valve FV1 are installed on the high-COD wastewater inlet pipe, and a flow meter F2 and a regulating valve FV2 are installed on the sludge inlet pipe. A proportional controller YC is connected between the regulating valve FV1 and the regulating valve FV2.

[0013] Preferably, the mixing and conveying unit includes a second static mixer and a pipeline control system. The input pipeline of the pipeline control system is connected to the output end of the delivery pump, the output pipeline of the pipeline control system is connected to the input end of the second static mixer, and the output end of the second static mixer is connected to the burner.

[0014] Preferably, both the first static mixer and the second static mixer include a mixing housing. An SK-type spiral blade mixer is installed inside the mixing housing. The spiral blade inclination angle of the spiral blade mixer is 45 degrees, and the length-diameter ratio of the spiral blade mixer is 8:1.

[0015] Preferably, the pipeline control system includes a cut-off valve connected to the input end of the second static mixer and a manual ball valve connected to the output end of the delivery pump. The output end of the manual ball valve is connected to a first regulating valve. The output end of the first regulating valve is connected to a first flow meter. The output end of the first flow meter is connected to a check valve. The output end of the check valve is connected to the input end of the cut-off valve. A safety interlock mechanism is provided between the cut-off valve and the check valve.

[0016] Preferably, the combustion control unit includes: an oxygen flow rate adjustment module that dynamically adjusts the pure oxygen flow rate according to the COD value of the mixed slurry;

[0017] A temperature feedback control system for real-time monitoring of the temperature in the combustion zone of the gasifier and automatically adjusting the sludge blending ratio;

[0018] Both the oxygen flow rate regulating module and the temperature feedback control system are connected to the first flowmeter.

[0019] Preferably, the temperature feedback control system monitors the temperature of the combustion zone of the gasifier in real time through a Type B thermocouple inserted into the combustion chamber. The set temperature is between 1200 - 1400 °C. When the temperature is higher than the set value, the amount of waste liquid introduced is reduced; when the temperature is lower than the set value, the amount of waste liquid introduced is increased.

[0020] Based on the system for co - treating high - COD wastewater and sludge by water - coal slurry gasification described above, the present invention also provides a method for co - treating high - COD wastewater and sludge by water - coal slurry gasification, including the following steps:

[0021] S1. Mix and treat the COD wastewater and the sewage treatment biochemical sludge in a flow ratio of 1:1 - 3 through a pretreatment unit to obtain a mixed liquid;

[0022] S2. Pump the mixed liquid into the mixing and conveying unit at a flow rate of 0.5 - 10 m 3 / h, and shear - mix it with a coal slurry with a concentration of 60 - 65% to obtain a homogeneous slurry;

[0023] S3. Atomize the homogeneous slurry through a burner and then enter the gasifier, and react with pure oxygen under the conditions of 4.0 MPa and 1300 °C. The COD in the wastewater and the organic matter in the sludge are completely gasified into CO and H2.

[0024] The system and method for co - treating high - COD wastewater and sludge by water - coal slurry gasification proposed by the present invention have the following advantages compared with the prior art:

[0025] 1. Through the pretreatment unit, the sludge and high - COD wastewater are fully mixed first, and then the pretreated mixed liquid is mixed with the coal slurry by the mixing and conveying unit to form a homogeneous slurry. Finally, the homogeneous slurry is atomized and then enters the gasifier, and oxygen is introduced into the gasifier to enable the homogeneous slurry to burn fully, realizing the homogeneous mixing and complete combustion of high - COD wastewater, biochemical sludge and coal slurry, reducing the treatment cost of sludge and high - COD wastewater, while recovering the calorific value and carbon in the sludge and high - COD wastewater, effectively improving the treatment efficiency of organic wastewater, and being able to ensure the output of wet gas without changing the properties of the water - coal slurry. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the present invention;

[0027] Figure 2 is a schematic diagram of the principle of the combustion control unit of the present invention;

[0028] Figure 3 is a schematic cross - sectional structure diagram of the second static mixer of the present invention;

[0029] In the figure: 110, the first static mixer; 111, the buffer tank; 112, the agitator; 113, the transfer pump; 210, the second static mixer; 2101, the mixing housing; 2102, the helical vane mixer; 211, the cut-off valve; 212, the first regulating valve; 213, the first flowmeter; 214, the hand valve ball valve; 215, the check valve; 310, the oxygen flow rate regulating module; 311, the temperature feedback control system; 3, the burner. Specific embodiments

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] The present invention provides a Figures 1-3 system for co-processing high-COD wastewater and sludge by water coal slurry gasification as shown, which includes a pretreatment unit, a mixing and transfer unit, and a combustion control unit. The pretreatment unit fully mixes the sludge and high-COD wastewater, and breaks the cell walls in the biochemical sludge;

[0032] The pretreatment unit includes a first static mixer 110, a buffer tank 111, and a transfer pump 113. The output end of the first static mixer 110 is communicated with the input end of the buffer tank 111, and the output end of the buffer tank 111 is communicated with the input end of the transfer pump 113. And a double-layer paddle agitator 112 is installed in the buffer tank 111, which is used to achieve full solid-liquid mixing by high-speed shearing, break the cell walls in the biochemical sludge, reduce the viscosity of the mixture, and facilitate full gasification. The buffer tank 111 uses a 316L stainless steel inner lining anti-corrosion coating, which is resistant to PH2-12. The rotation speed of the agitator 112 is 200 rpm, and the mixing time ≤ 30 minutes.

[0033] The transfer pump 113 is set as a diaphragm pump. The flow rate of the transfer pump 113 is 0.5-10 m3 / h, and the pressure is 4-6 MPa. The material of the flow-through components of the diaphragm pump is silicon carbide ceramic, and the particle diameter resistant to is ≤ 5 mm, which is convenient for transporting the mixture to the mixing and transfer unit; The transfer pump 113 can also use a high-pressure centrifugal pump to transport the mixture to the mixing and transfer unit;

[0034] The input ends of the first static mixer 110 are respectively connected to a high-COD wastewater inlet pipe and a sludge inlet pipe. A flowmeter F1 and a regulating valve FV1 are installed on the high-COD wastewater inlet pipe, and a flowmeter F2 and a regulating valve FV2 are installed on the sludge inlet pipe. A proportional controller YC is connected between the regulating valve FV1 and the regulating valve FV2. The regulating valve FV1 automatically adjusts the wastewater flow according to the flowmeter F1, the regulating valve FV2 automatically adjusts the sludge flow according to the flowmeter F2, and the proportional controller YC automatically controls the flow ratio of wastewater and sludge. The first static mixer 110 is installed 3 - 5 meters away from the buffer tank 111 to fully mix the sludge and high-COD wastewater and form a uniform mixture;

[0035] The mixing and conveying unit mixes the mixed liquid from the pretreatment unit with the coal slurry to form a homogeneous slurry;

[0036] The mixing and conveying unit includes a second static mixer 210 and a pipeline control system. The input pipeline of the pipeline control system is connected to the output end of the delivery pump 113, the output pipeline of the pipeline control system is connected to the input end of the second static mixer 210, and the output end of the second static mixer 210 is connected to the burner 3;

[0037] Both the first static mixer 110 and the second static mixer 210 include a mixing housing 2101. Inside the mixing housing 2101, a spiral vane mixer 2102 of the SK type is installed. The helix angle of the spiral vanes of the spiral vane mixer 2102 is 45 degrees, that is, the angle between the helix of the spiral vanes and the axis is 45 degrees, and the length-diameter ratio of the spiral vane mixer 2102 is 8:1, that is, the conveying length of the spiral vanes is 8 times the vane diameter, ensuring the non-settling mixing of high-solid-content media. Among them, the concentration of the high-solid-content media is ≤15%;

[0038] The pipeline control system includes a cut-off valve 211 connected to the input end of the second static mixer 210 and a manual ball valve 214 connected to the output end of the delivery pump 113. The output end of the manual ball valve 214 is connected to a first regulating valve 212. The output end of the first regulating valve 212 is connected to a first flowmeter 213. The output end of the first flowmeter 213 is connected to a check valve 215. The output end of the check valve 215 is connected to the input end of the cut-off valve 211. A safety interlock mechanism is provided between the cut-off valve 211 and the check valve 215. Among them, the cut-off valve 211 is a pneumatic quick-close valve with a response time < 1s and is interlocked with the pressure sensor in the safety interlock mechanism; the first regulating valve 212 is a pneumatic proportional valve with an accuracy of ±2% FS and is used to receive the feedback signal from the flowmeter; the first flowmeter 213 is a Coriolis mass flowmeter with a temperature resistance of -50°C - 200°C and a measurement error ≤ 0.5%.

[0039] AsFigure 3 As shown, the safety interlock mechanism includes a pressure sensor P2 for monitoring the pressure in the combustion chamber of the gasifier and a pressure sensor P1 installed between the shut-off valve 211 and the check valve 215. The difference between the pressure sensor P1 and the pressure sensor P2 is calculated as the pressure difference. When the pressure suddenly rises, the shut-off valve 211 is closed urgently and the nitrogen purge pipeline is started at the same time. The nitrogen purge pipeline is installed after the shut-off valve 211. The nitrogen purge pipeline prevents the combustible gas (such as coal gas) from mixing with air or other oxidizing gases by filling the system with nitrogen, thereby reducing the risk of explosion. For example, For example, during the gas medium replacement process in the gas / air injection pipeline, nitrogen purging can prevent the gas and air from mixing at high temperatures and causing explosion accidents; nitrogen purging can quickly replace residual combustible gases, toxic gases or impurities in the pipeline, preventing these substances from accumulating in the system or mixing with subsequent process gases, thereby ensuring the purity and safety of the process flow; and after the shut-off valve 211 is urgently closed, nitrogen purging can quickly reduce the pressure and temperature in the pipeline, reduce the risk of equipment damage caused by sudden pressure rise or high temperature, and create safe conditions for subsequent maintenance or restart.

[0040] The combustion control unit atomizes the homogeneous slurry transferred by the mixing and conveying unit through the burner 3 and then enters the gasifier, and introduces oxygen into the gasifier to fully burn the homogeneous slurry;

[0041] The combustion control unit includes an oxygen flow regulating module 310 and a temperature feedback control system 311, both of which are connected to the first flowmeter 213; the oxygen flow regulating module 310 dynamically adjusts the pure oxygen flow rate according to the COD value of the mixed slurry, and automatically adjusts the valve position of the oxygen regulating valve according to the value displayed on the online oxygen meter in the gas phase out of the gasifier to control the oxygen flow into the furnace, maintains the oxygen volume content in the process gas less than 0.5%, and sets the temperature between 0-0.5%. When the oxygen content is higher than the set value, the valve position of the oxygen regulating valve is reduced, and when the oxygen content is lower than the set value, the valve position of the oxygen regulating valve is increased, so as to avoid the risk of temperature loss or explosion in the combustion zone due to excessive oxygen, and prevent incomplete combustion caused by insufficient oxygen;

[0042] The temperature feedback control system 311 is used to monitor the temperature of the gasifier combustion zone in real time and automatically adjust the sludge mixing ratio. The temperature feedback control system 311 monitors the temperature of the gasifier combustion zone in real time through a B-type thermocouple inserted into the combustion chamber. The set temperature is between 1200-1400°C. When the temperature is higher than the set value, the amount of waste liquid introduced is reduced, and when the temperature is lower than the set value, the amount of waste liquid introduced is increased to prevent excessive temperature from causing equipment damage or the production of harmful by-products.

[0043] The combustion control unit realizes safe, stable, efficient and environmentally friendly operation during the gasifier combustion process through double closed-loop control of oxygen concentration and temperature, effectively improves the treatment efficiency of organic wastewater, and can ensure the output of wet gas without changing the properties of the water coal slurry.

[0044] Based on the system for co-processing high-COD wastewater and sludge by water coal slurry gasification described above, the present invention also provides a method for co-processing high-COD wastewater and sludge by water coal slurry gasification, which includes the following steps:

[0045] S1. Mix and treat the COD wastewater and the biochemical sludge of the sewage treatment at a flow rate ratio of 1:1 - 3 through a pretreatment unit to obtain a mixed liquid; as Figure 1 shown, the high-COD wastewater enters the first static mixer 110 through the pipeline 101, and the sludge enters the first static mixer 110 through the pipeline 102. The pretreatment unit is first fully mixed in the first static mixer 110 and then put into the buffer tank 111, and stirred until the solid content ≤ 15%;

[0046] S2. Pump the mixed liquid into the mixing and conveying unit at a flow rate of 0.5 - 10 m3 / h, and perform shear mixing with the coal slurry with a concentration of 60 - 65% to obtain a homogeneous slurry;

[0047] S3. Atomize the homogeneous slurry through the burner 3 and then enter the gasifier, and react with pure oxygen under the conditions of 4.0 MPa and 1300 °C. The COD in the wastewater and the organic matter in the sludge are completely gasified into CO and H2, so that the carbon and calorific value in the high-concentration wastewater can be recovered.

[0048] By first fully mixing the sludge and the high-COD wastewater, then mixing the pretreated mixed liquid with the coal slurry to form a homogeneous slurry, and finally atomizing the homogeneous slurry and entering the gasifier, and introducing oxygen into the gasifier to make the homogeneous slurry burn fully, the homogeneous mixing and complete combustion of the high-COD wastewater, biochemical sludge and coal slurry are realized, the treatment cost of the sludge and high-COD wastewater is reduced, and at the same time, the calorific value and carbon in the sludge and high-COD wastewater are recovered, effectively improving the treatment efficiency of organic wastewater, and can ensure the output of wet gas without changing the properties of the water coal slurry.

[0049] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A system for co - treating high - COD wastewater and sludge by coal - water slurry gasification, characterized in that: include: The pretreatment unit fully mixes the sludge and high-COD wastewater and breaks down the cell walls in the biochemical sludge; A mixing and conveying unit, which mixes the mixed liquid from the pretreatment unit with the coal slurry to form a homogeneous slurry; The combustion control unit atomizes the homogeneous slurry transmitted by the mixing and conveying unit through a burner (3) and then enters the gasification furnace, and introduces oxygen into the gasification furnace to fully burn the homogeneous slurry.

2. The system for co - treating high - COD wastewater and sludge by water - coal slurry gasification according to claim 1, characterized in that: The pretreatment unit comprises a first static mixer (110), a buffer tank (111) and a delivery pump (113), wherein the output end of the first static mixer (110) is connected to the input end of the buffer tank (111), the output end of the buffer tank (111) is connected to the input end of the delivery pump (113), and a double-layer paddle-type agitator (112) is installed in the buffer tank (111) for achieving sufficient mixing of solid and liquid by high-speed shearing and breaking cell walls in the biochemical sludge.

3. The system for co - treating high - COD wastewater and sludge by water - coal slurry gasification according to claim 2, wherein: The delivery pump (113) is configured as a diaphragm pump, the flow rate of the delivery pump (113) is 0.5-10 m3 / h, the pressure is 4-6 MPa, and the particle diameter is ≤5 mm.

4. The system for co-processing high-COD wastewater and sludge by water coal slurry gasification according to claim 2, wherein: The input end of the first static mixer (110) is connected to a high-COD wastewater inlet pipe and a sludge inlet pipe, respectively. A flow meter F1 and a regulating valve FV1 are installed on the high-COD wastewater inlet pipe, and a flow meter F2 and a regulating valve FV2 are installed on the sludge inlet pipe. A proportional controller YC is connected between the regulating valves FV1 and FV2.

5. A system for co-processing high-COD wastewater and sludge by water coal slurry gasification according to claim 2, characterized in that: The mixing and conveying unit comprises a second static mixer (210) and a pipeline control system, wherein the input end pipeline of the pipeline control system is connected to the output end of the delivery pump (113), the output end pipeline of the pipeline control system is connected to the input end of the second static mixer (210), and the output end of the second static mixer (210) is connected to the burner (3).

6. The system for co - treating high - COD wastewater and sludge by water - coal slurry gasification according to claim 5, characterized in that: The first static mixer (110) and the second static mixer (210) both include a mixing shell (2101), an SK-type helical blade mixer (2102) being installed inside the mixing shell (2101), the helical blade inclination angle of the helical blade mixer (2102) being 45 degrees, and the aspect ratio of the helical blade mixer (2102) being 8:

1.

7. The system for co - treating high - COD wastewater and sludge by water - coal slurry gasification according to claim 6, characterized in that: The pipeline control system comprises a shut-off valve (211) connected to the input end of the second static mixer (210) and a hand valve ball valve (214) connected to the output end of the delivery pump (113); the output end of the hand valve ball valve (214) is connected to the first regulating valve (212); the output end of the first regulating valve (212) is connected to the first flow meter (213); the output end of the first flow meter (213) is connected to the check valve (215); the output end of the check valve (215) is connected to the input end of the shut-off valve (211); and a safety interlock mechanism is provided between the shut-off valve (211) and the check valve (215).

8. A system for co - treating high - COD wastewater and sludge by water - coal slurry gasification according to claim 7, characterized in that: The combustion control unit comprises: an oxygen flow rate regulating module (310) for dynamically adjusting the pure oxygen flow rate according to the COD value of the mixed slurry; A temperature feedback control system (311) for real-time monitoring of the temperature in the combustion zone of the gasifier and automatically adjusting the sludge blending ratio; Both the oxygen flow rate regulating module (310) and the temperature feedback control system (311) are connected to the first flowmeter (213).

9. A system for co-processing high-COD wastewater and sludge by coal water slurry gasification according to claim 8, characterized in that: The temperature feedback control system monitors the temperature in the combustion zone of the gasifier in real time through a Type B thermocouple inserted into the combustion chamber. The set temperature is between 1200 - 1400 °C. When the temperature is higher than the set value, the amount of waste liquid introduced is reduced; when the temperature is lower than the set value, the amount of waste liquid introduced is increased.

10. A method for co - treating high - COD wastewater and sludge by water - coal slurry gasification, based on the system for co - treating high - COD wastewater and sludge by water - coal slurry gasification according to any one of claims 1 - 9, characterized in that: It includes the following steps: S1. Mix and treat the COD wastewater and the sewage treatment biochemical sludge in a flow ratio of 1:1 - 3 through a pretreatment unit to obtain a mixed liquid; S2. Pump the mixture into the mixing and conveying unit at a flow rate of 0.5 - 10 m 3 / h, and shear-mix it with the coal slurry with a concentration of 60 - 65% to obtain a homogeneous slurry; S3. Atomize the homogeneous slurry through a burner and introduce it into the gasifier, where it reacts with pure oxygen under the conditions of 4.0 MPa and 1300 °C. The COD in the wastewater and the organic matter in the sludge are completely gasified into CO and H2.

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