Sewage treatment system and method for coupling side-flow sludge pyrohydrolysis with heat pump waste heat

Abstract

The invention relates to the technical field of sewage treatment, in particular to a sewage treatment system and method for coupling side flow sludge thermal hydrolysis with heat pump waste heat, and the sewage treatment system comprises a biochemical pool, a secondary sedimentation pool, a side flow pool, a thermal hydrolysis module and a water source heat pump module, the heat energy output end of the water source heat pump module is connected with the pyrohydrolysis module, the solid phase output end of the secondary sedimentation tank is connected with the pyrohydrolysis module through a side flow pipeline, and the pyrohydrolysis module is communicated with the biochemical tank through a side flow tank. Heat in sewage flowing out of the secondary sedimentation tank is extracted by the water source heat pump module, after the heat energy grade is improved, a stable reaction temperature condition is provided for the thermal hydrolysis reaction of sludge in the thermal hydrolysis module, the cooperation of a sludge thermal hydrolysis technology and a side flow process is realized, the energy consumption of the thermal hydrolysis reaction is effectively reduced, and the energy consumption is reduced. The temperature condition supply cost of the thermal hydrolysis reaction is reduced, the energy utilization rate is improved, and low-carbon work is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly relates to a sewage treatment system and method coupling sidestream sludge thermohydrolysis with waste heat of heat pump. Background Art

[0002] In a traditional activated sludge sewage treatment system, it generally includes a biochemical reaction tank and a secondary sedimentation tank. The biochemical reaction tank is used for microbial treatment of sewage, and the secondary sedimentation tank is used for separation of sludge and water. To reduce the sludge load of the mainstream system, generally, on the basis of directly returning the sludge from the secondary sedimentation tank to the biochemical reaction tank, a sidestream process is also adopted to separately treat part of the returned sludge (such as anaerobic digestion, biological enhancement, etc.). However, the applicant found in the process of implementing the present invention that in the prior art without relying on external energy, there will be a situation where the carbon source release of sludge in the sidestream process is insufficient and cannot meet the mainstream denitrification demand, and additional carbon sources need to be added. Summary of the Invention

[0003] The purpose of the present invention is to provide a sewage treatment system and method coupling sidestream sludge thermohydrolysis with waste heat of heat pump to solve the above-mentioned technical problems existing in the prior art, mainly including the following two aspects: In the first aspect, a sewage treatment system coupling sidestream sludge thermohydrolysis with waste heat of heat pump is disclosed, which includes a biochemical tank, a secondary sedimentation tank, a sidestream tank, a thermohydrolysis module, a preheating module, and a water source heat pump module. Along the sewage flow direction, the biochemical tank and the secondary sedimentation tank are arranged in sequence. The heat energy collection end of the water source heat pump module is connected to the liquid phase output end of the secondary sedimentation tank, and the heat energy output end of the water source heat pump module is connected to the thermohydrolysis module. The water source heat pump module is used to collect the heat energy of the liquid phase fluid in the liquid phase output end of the secondary sedimentation tank and output it to the thermohydrolysis module after increasing the heat energy grade, so as to realize the thermohydrolysis treatment of sludge by the thermohydrolysis module. The solid phase output end of the secondary sedimentation tank is connected to the input end of the thermohydrolysis module through a sidestream pipeline, and the output end of the thermohydrolysis module is communicated with the biochemical tank through the sidestream tank. The thermohydrolysis module is used to perform thermohydrolysis treatment on the flowing-through sludge; the preheating module includes a gas phase circulation pipeline and a heat exchange component arranged in the gas phase circulation pipeline. The heat exchange component is arranged at the input end of the thermohydrolysis module and is used to preheat the sludge entering the thermohydrolysis module. The thermohydrolysis module includes a reaction chamber. The input end of the gas phase circulation pipeline is communicated with the top of the reaction chamber, and the output end of the gas phase circulation pipeline is arranged in the middle of the reaction chamber. A circulation pump is arranged on the gas phase circulation pipeline; the heat exchange component includes an outer sleeve pipe arranged on the pipeline at the input end of the thermohydrolysis module. There is a preheating air channel between the outer sleeve pipe and the pipeline at the input end of the thermohydrolysis module. The preheating air channel is used to form the gas phase circulation pipeline to realize preheating of the sludge in the pipeline at the input end of the thermohydrolysis module.

[0004] In the second aspect, a sewage treatment method is disclosed, which uses the above-mentioned sewage treatment system to treat sewage.

[0005] The technical solution adopted by the present invention can achieve the following beneficial effects: In this application, the heat pump module extracts the heat from the sewage flowing out of the secondary sedimentation tank. After improving the heat energy grade, the heat exchange medium is then sent into the hydrothermal hydrolysis module to provide stable reaction temperature conditions for the hydrothermal hydrolysis reaction of the sludge in the hydrothermal hydrolysis module, realizing the coordination of the sludge hydrothermal hydrolysis technology and the side-stream process. Compared with the prior art where a heat source is separately configured to provide reaction temperature conditions for the hydrothermal hydrolysis module, the energy consumption of the hydrothermal hydrolysis reaction is effectively reduced, the supply cost of the reaction temperature conditions for the hydrothermal hydrolysis reaction is reduced, the energy utilization rate is improved, and low-carbon operation is achieved; In addition, the hot air in the hydrothermal hydrolysis module is used to preheat the sludge to be subjected to hydrothermal hydrolysis, which can not only improve the heat energy utilization rate but also avoid local overheating inside the sludge in the hydrothermal hydrolysis module through the control and regulation of the gas phase in the hydrothermal hydrolysis module, affecting the hydrothermal hydrolysis effect of the sludge, realizing the auxiliary regulation of two dimensions of the reaction temperature conditions and reaction pressure conditions for the hydrothermal hydrolysis reaction, promoting the uniform and efficient progress of the hydrothermal hydrolysis reaction inside the sludge, further improving the utilization efficiency of the heat energy resources in the hydrothermal hydrolysis module on the basis of improving the temperature stability of the hydrothermal hydrolysis reaction inside the sludge, enhancing the energy efficiency of the hydrothermal hydrolysis module and the sewage treatment system, and reducing the system operation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0007] Figure 1 is a schematic structural diagram of the sewage treatment system of the present invention; Figure 2 is a schematic diagram of the pipeline connection of the sewage treatment system of the present invention; Figure 3 is a schematic internal structure diagram of the hydrothermal hydrolysis module of the present invention; Figure 4 is a schematic diagram of the pipeline connection of the hydrothermal hydrolysis module of the present invention; Figure 5 is a schematic structural diagram of the stirring shaft and stirring blades of the present invention; Figure 6 is a schematic connection diagram of the control module and the temperature detection unit of the present invention.

[0008] In the figure: 10. Biochemical tank; 20. Secondary sedimentation tank; 210. Liquid phase output end; 220. Solid phase output end; 30. Water source heat pump module; 40. Hydrolysis module; 410. Reaction chamber; 411. Sludge input end; 412. Sludge output end; 420. Stirring blade; 421. Flow-facing surface; 422. Back-flow surface; 423. Air hole; 430. Stirring shaft; 440. Driving unit; 50. Side flow tank; 60. Side flow pipeline; 610. Delivery pump; 70. Preheating module; 710. Outer sleeve pipe; 720. Circulation pump; 730. Pressure relief branch; 740. Coupling; 80. Sludge return pipeline; 910. Control module; 920. Temperature detection unit. Detailed implementation manners

[0009] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention. All other implementation manners obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope protected by the present invention.

[0010] The terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such used data may be interchanged under appropriate circumstances so that the embodiments of this application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. generally belong to the same category, and the number of objects is not limited. For example, the first object may be one or multiple. In addition, "and / or" in the description and claims means at least one of the connected objects, and the character " / " generally indicates an "or" relationship between the associated objects before and after.

[0011] For the existing activated sludge process sewage treatment system, to improve the problem of insufficient carbon source release in the side flow process, the sludge hydrolysis technology is generally used to treat the side flow sludge. By decomposing the sludge cell wall at high temperature (120°C - 180°C) and high pressure, organic matter is released. However, the sludge hydrolysis technology requires a large amount of heat, and a separate heat source needs to be configured to meet the heat demand of sludge hydrolysis. The additional configuration of the heat source not only increases the cost of the activated sludge process sewage treatment system but also reduces the energy efficiency of the entire system. To solve the technical problems of high cost and low energy efficiency brought by the sludge hydrolysis technology in combination with the side flow process, the present invention provides a sewage treatment system and method for coupling sludge hydrolysis with heat pump waste heat in the side flow process. By recycling the waste heat of the secondary sedimentation tank effluent, the thermal energy grade of the waste heat is improved through heat pump technology and then supplied to the sludge hydrolysis reaction, realizing the coordination of the low-cost and high-energy-efficiency sludge hydrolysis technology and the side flow process, and effectively improving the concentration of available carbon source, as described in the following embodiments.

[0012] Example 1 Some embodiments of the present application provide a sewage treatment system that couples sidestream sludge hydrothermal hydrolysis with waste heat of a heat pump, as Figure 1 and Figure 2 shown. It includes a biochemical pool 10, a secondary sedimentation tank 20, a sidestream tank 50, a hydrothermal hydrolysis module 40, and a water source heat pump module 30. Along the sewage flow direction, the biochemical pool 10 and the secondary sedimentation tank 20 are arranged in sequence. The heat energy collection end of the water source heat pump module 30 is connected to the liquid phase output end 210 of the secondary sedimentation tank 20, and the heat energy output end of the water source heat pump module 30 is connected to the hydrothermal hydrolysis module 40. The water source heat pump module 30 is used to collect the heat energy of the liquid-phase fluid at the liquid phase output end of the secondary sedimentation tank 20, and after upgrading the heat energy grade, output it to the hydrothermal hydrolysis module 40 to realize the hydrothermal hydrolysis treatment of the sludge by the hydrothermal hydrolysis module 40. The solid phase output end 220 of the secondary sedimentation tank 20 is connected to the sludge input end 411 of the hydrothermal hydrolysis module 40 through a sidestream pipeline 60, and the sludge output end 412 of the hydrothermal hydrolysis module 40 is communicated with the biochemical pool 10 through the sidestream tank 50. The hydrothermal hydrolysis module 40 is used to perform hydrothermal hydrolysis treatment on the flowing sludge. For the sewage flowing out of the secondary sedimentation tank 20, the general temperature is 15°C to 25°C, and there is a certain amount of waste heat that can be utilized. Moreover, the secondary sedimentation tank 20 is close to the sidestream pipeline 60, and the loss and cost are very low during the heat transfer process. Based on this, the water source heat pump module 30 exchanges heat with the liquid phase output end 210 (sewage outlet) of the secondary sedimentation tank 20 to extract the heat in the sewage flowing out of the secondary sedimentation tank 20, and then upgrades the heat energy grade through the compressor in the water source heat pump module 30 to raise the heat exchange medium in the water source heat pump module 30 to 100°C to 150°C, and then sends the heat exchange medium into the hydrothermal hydrolysis module 40. Specifically, the sludge in the hydrothermal hydrolysis module 40 can be heated through a heat exchange coil. First, the sludge in the reaction chamber 410 is heated to 80°C to 100°C (by low-temperature hydrothermal hydrolysis to reduce the excessive decomposition of activated sludge, and preferentially release easily degradable carbon sources such as VFAs and monosaccharides, so that the concentration of dissolved COD (SCOD) in the sludge is increased by 3 to 5 times), providing stable reaction temperature conditions for the sludge to undergo hydrothermal hydrolysis reaction in the hydrothermal hydrolysis module 40. The hydrothermally hydrolyzed sludge enters the biochemical pool 10 through the sidestream tank 50, realizing the coordination of the sludge hydrothermal hydrolysis technology and the sidestream process. Moreover, compared with the prior art where a separate heat source is configured to provide the reaction temperature conditions for the hydrothermal hydrolysis module 40, since the waste heat of the sewage in the secondary sedimentation tank 20 is recycled, the hydrothermal hydrolysis energy consumption is reduced, the supply cost of the hydrothermal hydrolysis reaction temperature conditions is lowered, the energy utilization rate is improved, and the low-carbon operation of the sewage treatment system is realized.

[0013] It should be noted that the biochemical pool 10, the secondary sedimentation tank 20, the side flow tank 50, and the water source heat pump technology can all be directly applied using existing technologies. The biochemical pool 10 is used to carry out microbial reaction treatment on sewage to degrade pollutants in the sewage. The secondary sedimentation tank 20 is used to carry out sludge-water separation treatment on the sewage. The side flow tank 50 is used to cache the sludge after the hydrothermal reaction to avoid the impact of high-concentration pollutants on the main process. The water source heat pump module 30 is an energy-saving technology that transfers the heat in the low-temperature heat source in the water source to the high-temperature heat source by consuming a small amount of high-grade energy (such as electric energy). Specifically, it includes an evaporator for absorbing the low-grade heat energy in the environment, a compressor for increasing the temperature and pressure of the refrigerant, a condenser for releasing high-temperature heat to the target medium, and an expansion valve for reducing the pressure of the refrigerant. The water source heat pump module 30 can transfer 3 to 5 parts of environmental heat energy with one part of electric energy, which is more efficient than the existing electric heating technology and more economical than the gas boiler.

[0014] In some embodiments, as Figure 3 and Figure 4 shown, the sewage treatment system further includes a preheating module 70. The preheating module includes a gas-phase circulation pipeline and a heat exchange component provided in the gas-phase circulation pipeline. The heat exchange component is provided at the sludge input end 411 of the hydrothermal module 40 for preheating the sludge entering the hydrothermal module 40. The hydrothermal module 40 includes a reaction chamber 410. The input end of the gas-phase circulation pipeline is communicated with the top of the reaction chamber 410, and the output end of the gas-phase circulation pipeline is provided in the middle of the reaction chamber 410. A circulation pump 720 is provided on the gas-phase circulation pipeline.

[0015] In some embodiments, to improve resource utilization efficiency, the heat exchange assembly may be configured to include an outer sleeve pipe 710 disposed on the pipeline of the sludge input end 411 of the hydrothermal hydrolysis module 40. There is a preheating air passage between the outer sleeve pipe 710 and the pipeline of the sludge input end 411 of the hydrothermal hydrolysis module 40. The preheating air passage is used to form a gas-phase circulation pipeline to preheat the sludge in the pipeline of the sludge input end 411 of the hydrothermal hydrolysis module 40. Since the temperature in the reaction chamber 410 is high, high-temperature and high-pressure water vapor is formed in the top cavity of the reaction chamber 410. The high-temperature and high-pressure water vapor is introduced into the heat exchange assembly through the gas-phase circulation pipeline, which can reduce the temperature and pressure in the reaction chamber. At the same time, when the water vapor passes through the preheating air passage, it preheats the sludge about to enter the reaction chamber 410. Relatively speaking, the residence time of the sludge in the reaction chamber 410 can be shortened, and the efficiency and effect of the sludge hydrothermal hydrolysis reaction can be improved. Then, the heat-exchanged water vapor continues to enter the sludge undergoing hydrothermal hydrolysis reaction in the reaction chamber 410 through the gas-phase circulation pipeline, assisting the sludge hydrothermal hydrolysis reaction to proceed uniformly and efficiently, and avoiding the accumulation of heat energy in the sludge. Part of the heat energy in the sludge is taken away to the top cavity area of the reaction chamber 410, keeping the sludge undergoing hydrothermal hydrolysis reaction in a relatively stable temperature environment, realizing the auxiliary adjustment of the temperature condition and reaction pressure condition of the hydrothermal hydrolysis reaction. On the basis of improving the temperature stability of the hydrothermal hydrolysis reaction, the utilization efficiency of the heat energy resources of the hydrothermal hydrolysis module 40 is effectively improved, the energy efficiency of the hydrothermal hydrolysis module 40 and the sewage treatment system is enhanced, and the system operation cost is reduced.

[0016] In some embodiments, to optimize the effect of sludge hydrothermal reaction, the hydrothermal reaction module 40 may be provided such that it further includes a driving unit 440 and stirring blades 420 disposed in the reaction chamber 410. The driving unit 440 is configured to control the rotation of the stirring blades 420 by driving a stirring shaft 430. Air holes 423 are provided on the stirring blades 420. The gas phase circulation pipeline further includes a gas transmission channel disposed in the stirring shaft 430. The input end of the gas transmission channel is communicated with the output end of the circulation pump 720 through a coupling 740. On the basis of ensuring the gas path connection between the gas transmission channel and the circulation pump 720, the rotation of the stirring shaft 430 will not be affected. The output end of the gas transmission channel is communicated with the air holes 423, and the stirring blades 420 are fixedly connected to the stirring shaft 430. When performing the sludge hydrothermal reaction, the rotation of the stirring blades 420 can be selectively controlled to accelerate heat conduction, making the temperature distribution in the reaction chamber 410 more uniform and avoiding local overheating or insufficient reaction. On the other hand, the shear force generated on the sludge during the rotation of the stirring blades 420 can further break the sludge flocs and the microbial cell walls, promoting the release of intracellular organic matter and increasing the generated carbon source. When the gas phase circulation pipeline is in operation, the water vapor in the top cavity of the reaction chamber 410 is sucked into the gas phase circulation pipeline. When passing through the preheating air channel, the sludge about to enter the reaction chamber 410 is preheated. Then, the water vapor enters the gas transmission channel in the stirring shaft 430 through the coupling 740, and then is introduced into the sludge through the air holes 423, which can accelerate the removal of the heat energy in the sludge, avoid local overheating, reasonably control the temperature fluctuation range inside the hydrothermally treated sludge, accelerate the contact between the sludge particles and the high-temperature water / steam, strengthen the hydrolysis reaction kinetics, and shorten the reaction time.

[0017] Preferably, the coupling 740 is disposed outside the reaction chamber 410. The driving unit 440 is a prior art and can adopt a servo motor, which will not be elaborated herein.

[0018] In some embodiments, to prevent the sludge from clogging the air holes 423 during the operation of the stirring blades 420, as Figure 5 shown, the air holes 423 can be disposed on the backflow surface 422 of the stirring blades 420, reducing the risk of the air holes 423 being clogged during operation, improving the operation stability and safety of the gas phase circulation pipeline. During the rotation of the stirring blades 420, the contact surface directly contacting the sludge is the upstream surface 421, and the surface corresponding to the upstream surface 421 is the backflow surface 422.

[0019] In some embodiments, to ensure the stable progress of the sludge hydrothermal reaction, along the gravity direction, the stirring blade 420 can be arranged between the sludge input end 411 of the hydrothermal module 40 and the sludge output end 412 of the hydrothermal module 40, and the sludge output end 412 of the hydrothermal module 40 is located at the bottom of the reaction chamber 410, so as to control the residence time of the sludge in the reaction chamber 410. Correspondingly, the heat energy inlet of the heat energy output end of the water source heat pump module 30 is close to the sludge input end 411, and the heat energy outlet is close to the sludge output end 412, so as to improve the heating and temperature rising efficiency of the sludge.

[0020] In some embodiments, the input end of the gas phase circulation pipeline is located above the sludge input end 411 of the hydrothermal module 40, so that the input end of the gas phase circulation pipeline is at the top cavity of the reaction chamber 410, and the newly entered sludge in the reaction chamber 410 will not affect the input end of the gas phase circulation pipeline.

[0021] In some embodiments, since the temperature of the sewage generated by the secondary sedimentation tank 20 is greatly affected by the ambient temperature, at different times of the same day or in different seasons, the temperature of the sewage generated by the secondary sedimentation tank 20 will fluctuate to a certain extent, which will lead to certain fluctuations in the heat energy output from the water source heat pump module 30 to the hydrothermal module 40. To reduce the unstable influence caused by the ambient temperature fluctuation, a transfer pump 610 can be arranged on the side flow pipeline 60. The sewage treatment system further includes a control module 910, and the control module 910 is configured to: determine the power of the transfer pump 610 and the circulation pump 720 based on the fluid temperature at the liquid phase output end of the secondary sedimentation tank 20; in the actual application process, based on the sewage temperature change curve collected through prior investigation of the secondary sedimentation tank 20, the upper and lower limits of the heat energy that the water source heat pump module 30 can output can be calculated. When the temperature of the sewage generated by the secondary sedimentation tank 20 becomes lower, the transfer pump 610 can be controlled to reduce the sludge transfer amount, so as to reduce the amount of sludge hydrothermal reaction and / or the residence time of the sludge in the reaction chamber 410. When the temperature of the sewage generated by the secondary sedimentation tank 20 becomes higher, the circulation pump 720 can be controlled to work, and part of the heat energy in the reaction chamber 410 can be used to preheat the sludge through the gas phase circulation pipeline. Further, the power of the transfer pump 610 can be increased synchronously to increase the amount of sludge in the reaction chamber 410 and / or shorten the residence time of the sludge in the reaction chamber 410, so as to realize that when the sewage temperature fluctuates due to the ambient temperature fluctuation, the hydrothermal reaction in the sewage treatment system will not be affected by this situation, and the temperature change brought by this fluctuation can be used to flexibly adjust the working state of the hydrothermal module 40. On the basis of improving the efficiency and effect of the hydrothermal reaction, the resource utilization efficiency is improved, and the waste of peak heat energy and the reduction of the hydrothermal reaction effect at the trough value are avoided.

[0022] In some embodiments, to improve the flexibility of system regulation, it may be set that the gas-phase circulation pipeline further includes a pressure relief branch 730. The heat exchange component is located between the pressure relief branch 730 and the input end of the gas-phase circulation pipeline. The pressure relief branch 730 is used to control the air pressure in the gas-phase circulation pipeline within a preset value. When the temperature in the reaction chamber 410 is too high, the water vapor after preheating the sludge can be discharged from the gas-phase circulation pipeline through the pressure relief branch 730, thereby reducing the temperature and pressure in the reaction chamber 410, increasing the regulation means of the hydrothermal hydrolysis module 40, realizing the automatic regulation of the hydrothermal hydrolysis module 40, and ensuring the stable progress of the sludge hydrothermal hydrolysis reaction.

[0023] In some embodiments, to improve the flexibility of system regulation, such as Figure 6 shown, it may be set that the control module 910 is further configured to: determine the preset value based on the temperature in the reaction chamber 410; when the temperature in the reaction chamber 410 is too high, control the automatic operation of the pressure relief branch 730 by the set preset value. And when the sludge itself parameters change greatly, the hydrothermal hydrolysis reaction conditions need to be adjusted adaptively. At this time, the preset value required for opening the pressure relief branch 730 can be adjusted adaptively.

[0024] In some embodiments, to achieve the automatic operation of system regulation, it may be set that the sewage treatment system further includes a temperature detection unit 920. The temperature detection unit 920 is used to detect the temperature at the output end of the secondary sedimentation tank 20 and / or in the reaction chamber 410. The temperature detection unit 920 is connected to the control module 910, and the control module 910 receives the monitoring signal of the temperature detection unit 920 and controls the delivery pump 610 and the circulation pump 720 to make corresponding responses.

[0025] In some embodiments, the sewage treatment system further includes a sludge return pipeline 80. The secondary sedimentation tank 20 is communicated with the biochemical tank 10 through the sludge return pipeline 80.

[0026] In some embodiments, delivery pumps 610 connected to the control module 910 are respectively arranged on the sludge return pipeline 80 and the sludge output end 412 of the hydrothermal hydrolysis module 40.

[0027] Embodiment 2 Some embodiments of the present application provide a sewage treatment method, using the sewage treatment system in Embodiment 1 to treat sewage.

[0028] During the actual working process, sewage first enters the biochemical tank 10, and the biochemical tank 10 is used to carry out microbial reaction treatment on the sewage to degrade the organic matter in the sewage. Then the sewage flows into the secondary sedimentation tank 20, and the secondary sedimentation tank 20 is used to carry out sludge-water separation treatment on the sewage. The sludge generated by the secondary sedimentation tank 20 can be refluxed to the biochemical tank 10 through the sludge reflux pipeline 80, or can be transported to the thermal hydrolysis module 40 through the side flow pipeline 60 for sludge thermal hydrolysis reaction. At the same time, the water source heat pump module 30 exchanges heat with the liquid phase output end 210 (sewage outlet) of the secondary sedimentation tank 20 to extract the heat in the sewage flowing out of the secondary sedimentation tank 20. Then, the heat energy grade is increased by the compressor in the water source heat pump module 30, and the heat exchange medium in the water source heat pump module 30 is heated to 100°C - 150°C. Then the heat exchange medium is sent into the thermal hydrolysis module 40. Specifically, the sludge in the thermal hydrolysis module 40 can be heated through the heat exchange coil. It is preferred to heat the sludge in the reaction chamber 410 to 80°C - 100°C (reduce the excessive decomposition of activated sludge through low-temperature thermal hydrolysis, and preferentially release easily degradable carbon sources such as VFAs and monosaccharides, so that the concentration of dissolved COD (SCOD) in the sludge is increased by 3 - 5 times), providing a stable reaction temperature condition for the sludge to undergo thermal hydrolysis reaction in the thermal hydrolysis module 40. The sludge after the thermal hydrolysis reaction flows through the side flow tank 50 to the biochemical tank 10, realizing the coordination of the sludge thermal hydrolysis technology and the side flow process. And compared with the prior art where a heat source is separately configured to provide the reaction temperature condition for the thermal hydrolysis module, due to the recovery and utilization of the waste heat of the sewage in the secondary sedimentation tank 20, the thermal hydrolysis energy consumption is effectively reduced, the supply cost of the thermal hydrolysis reaction temperature condition is reduced, the energy utilization rate is improved, and low-carbon operation is achieved.

[0029] In some embodiments, the temperature of the sewage flowing out of the secondary sedimentation tank 20 can be obtained. When the temperature of the sewage generated by the secondary sedimentation tank 20 becomes lower, the delivery pump 610 can be controlled to reduce the sludge delivery volume, thereby reducing the amount of sludge thermal hydrolysis reaction and / or the residence time of the sludge in the reaction chamber 410. When the temperature of the sludge generated by the secondary sedimentation tank 20 becomes higher, the circulation pump 720 can be controlled to work, and part of the heat energy in the reaction chamber 410 is used through the gas phase circulation pipeline to preheat the sludge about to undergo thermal hydrolysis reaction. Further, the power of the delivery pump 610 can be synchronously increased, the amount of sludge in the reaction chamber 410 can be increased and / or the residence time of the sludge in the reaction chamber 410 can be shortened, so as to realize that when the sewage temperature fluctuates due to environmental temperature fluctuations, the thermal hydrolysis reaction will not be affected by this situation, and the temperature change brought by the fluctuation can be used to flexibly adjust the working state of the thermal hydrolysis module 40. On the basis of improving the efficiency and effect of the thermal hydrolysis reaction, the resource utilization efficiency is improved, and the situation of peak heat energy waste and valley value reduction of the thermal hydrolysis reaction effect is avoided.

[0030] It should be noted that in this document, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or apparatus. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising that element.

[0031] In addition, it should be pointed out that the scope of the methods and apparatuses in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in a reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0032] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A sewage treatment system coupling sidestream sludge hydrothermal hydrolysis with heat pump waste heat recovery, characterized in that, It includes a biochemical pool, a secondary sedimentation tank, a side flow tank, a hydrothermal hydrolysis module, a preheating module, and a water source heat pump module. Along the sewage flow direction, the biochemical pool and the secondary sedimentation tank are arranged in sequence. The heat energy collection end of the water source heat pump module is connected to the liquid phase output end of the secondary sedimentation tank, and the heat energy output end of the water source heat pump module is connected to the hydrothermal hydrolysis module. The water source heat pump module is used to collect the heat energy of the liquid phase fluid at the liquid phase output end of the secondary sedimentation tank, and after increasing the heat energy grade, output it to the hydrothermal hydrolysis module to realize the hydrothermal hydrolysis treatment of sludge by the hydrothermal hydrolysis module. The solid phase output end of the secondary sedimentation tank is connected to the input end of the hydrothermal hydrolysis module through a side flow pipeline, and the output end of the hydrothermal hydrolysis module is communicated with the biochemical pool through the side flow tank. The hydrothermal hydrolysis module is used to perform hydrothermal hydrolysis treatment on the flowing sludge; the preheating module includes a gas phase circulation pipeline and a heat exchange component arranged in the gas phase circulation pipeline. The heat exchange component is arranged at the input end of the hydrothermal hydrolysis module and is used to preheat the sludge entering the hydrothermal hydrolysis module. The hydrothermal hydrolysis module includes a reaction chamber. The input end of the gas phase circulation pipeline is communicated with the top of the reaction chamber, and the output end of the gas phase circulation pipeline is arranged in the middle of the reaction chamber. A circulation pump is arranged on the gas phase circulation pipeline; the heat exchange component includes an outer sleeve arranged on the pipeline at the input end of the hydrothermal hydrolysis module. There is a preheating air channel between the outer sleeve and the pipeline at the input end of the hydrothermal hydrolysis module. The preheating air channel is used to form the gas phase circulation pipeline to realize the preheating of the sludge in the pipeline at the input end of the hydrothermal hydrolysis module.

2. The sewage treatment system with side-stream sludge hydrothermal hydrolysis coupled with heat pump waste heat according to claim 1, characterized in that, The hydrothermal hydrolysis module further includes a driving unit and stirring blades arranged in the reaction chamber. The driving unit is used to control the rotation of the stirring blades by driving a stirring shaft. The stirring blades are provided with air holes. The gas phase circulation pipeline further includes an air delivery channel arranged in the stirring shaft. The input end of the air delivery channel is communicated with the output end of the circulation pump through a coupling, and the output end of the air delivery channel is communicated with the air holes.

3. The sewage treatment system with side-stream sludge hydrothermal hydrolysis coupled with heat pump waste heat according to claim 2, characterized in that, The air holes are arranged on the back flow surface of the stirring blades.

4. A sewage treatment system with side-stream sludge hydrothermal hydrolysis coupled with heat pump waste heat recovery according to claim 2, characterized in that, Along the gravity direction, the stirring blades are located between the input end and the output end of the hydrothermal hydrolysis module, and the output end of the hydrothermal hydrolysis module is located at the bottom of the reaction chamber.

5. A sewage treatment system with side-stream sludge hydrothermal hydrolysis coupled with heat pump waste heat according to claim 2, characterized in that, The input end of the gas phase circulation pipeline is located above the input end of the hydrothermal hydrolysis module.

6. The sewage treatment system with side-stream sludge hydrothermal hydrolysis coupled with heat pump waste heat according to claim 2, characterized in that A delivery pump is arranged on the side flow pipeline. The sewage treatment system further includes a control module, and the control module is configured to: determine the power of the delivery pump and the circulation pump based on the fluid temperature at the liquid phase output end of the secondary sedimentation tank.

7. A sewage treatment system with side-stream sludge hydrothermal hydrolysis coupled with heat pump waste heat recovery according to claim 6, characterized in that, The gas phase circulation pipeline further includes a pressure relief branch. The heat exchange component is located between the pressure relief branch and the input end of the gas phase circulation pipeline. The pressure relief branch is used to control the air pressure in the gas phase circulation pipeline within a preset value.

8. A sewage treatment system with side-stream sludge hydrothermal hydrolysis coupled with heat pump waste heat recovery according to claim 7, characterized in that, The control module is further configured to: determine the preset value based on the temperature in the reaction chamber.

9. A sewage treatment system with side-stream sludge hydrothermal hydrolysis coupled with heat pump waste heat recovery according to any one of claims 1 to 8, characterized in that, The sewage treatment system further includes a temperature detection unit, and the temperature detection unit is used to detect the temperature at the output end of the secondary sedimentation tank and / or the temperature in the reaction chamber; And / or, the sewage treatment system further includes a sludge return pipeline, and the secondary sedimentation tank is communicated with the biochemical pool through the sludge return pipeline.

10. A sewage treatment method, characterized in that, Treat sewage using the sewage treatment system according to any one of claims 1 to 9.

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