Sludge drying and sludge fermentation combined device

Abstract

The utility model discloses a sludge drying and sludge fermentation combined device, belongs to the technical field of sludge drying and energy utilization, and aims to solve the problems of high energy consumption and cost, poor treatment effect, low resource utilization rate, great negative influence on the environment and energy waste in the prior art. The present invention comprises: a sludge drying device; a sludge fermentation system; marsh gas output by the sludge fermentation system enters the marsh gas power generation system for power generation, and waste gas and heat exchange hot gas generated by the marsh gas power generation system are connected with the sludge drying equipment for heat supply; the sewage source heat pump system is connected with the sludge drying equipment for heat supply through hot air generated by the sewage source heat pump system, and is connected with a hot water inlet pipe of the sludge fermentation system for heat supply through hot water generated by the sewage source heat pump system; the controller is used for starting and stopping the whole combined device according to the drying temperature and the fermentation temperature.

Description

Technical Field

[0001] The utility model belongs to the technical field of sludge drying and energy utilization, and specifically relates to a combined device for sludge drying and sludge fermentation. Background Art

[0002] With the improvement of urban sewage treatment rate in my country, the amount of sludge generated is also increasing, and the treatment of sludge has become an urgent problem to be solved. In order to better handle these sludges, sludge drying technology has become increasingly important. Under normal circumstances, when the water content is above 85%, the sludge is in a flowing state; when the water content is between 65% and 85%, the sludge is in a plastic state; when the water content is lower than 60%, the sludge is in a solid state; when the water content is lower than 40%, the sludge is in a powdery state. The concentrated sludge is mechanically dehydrated to reduce the water content to 80%, but it is still difficult to meet the requirements of stable incineration. Thermal drying equipment is required to further dry it to below 70%. Sludge drying technology is a technology for dehydrating sludge. Through drying treatment, the water in the sludge can be removed, so that its volume is reduced, the weight is reduced, and it is easy to transport and dispose of. The dried sludge can also be reused as resources such as fertilizers and building materials to achieve resource recycling.

[0003] However, there are still some problems in the practical application of sludge drying technology. First, the drying process consumes a lot of energy and resources, and the cost is high. Secondly, the dried sludge may still contain some toxic and harmful substances, which require further treatment and disposal. In addition, some pollutants such as odorous gases and dust may be produced during the drying process, which will have an impact on the environment and human health. Therefore, while improving the sewage treatment rate, it is necessary to strengthen the research and development and application of sludge drying technology, reduce its energy consumption and cost, improve the treatment effect and resource utilization, and reduce the negative impact on the environment.

[0004] In the prior art, Wang Baozhong designed a dual-source (air source and sewage source) heat pump sludge drying system, which has four operating modes to simulate the process of the dual-source heat pump sludge drying system, but it has problems of long drying time and unstable performance.

[0005] For sludge fermentation systems, currently, the main ways to increase the temperature include using biomass boilers for heating, solar energy heating, electric heating and other methods, which require additional energy input and result in energy waste. Utility Model Content

[0006] The utility model aims to provide a combined device for sludge drying and sludge fermentation to solve the problems of high energy consumption and cost, poor treatment effect, low resource utilization, great negative impact on the environment and energy waste in the prior art.

[0007] In order to achieve the above-mentioned purpose, a combined device for sludge drying and sludge fermentation of the utility model comprises:

[0008] Sludge drying equipment, wherein a drying temperature sensor is provided in a drying chamber of the sludge drying equipment;

[0009] A sludge fermentation system, the sludge fermentation system comprising a hot water inlet pipe and a cold water outlet pipe connected to the sludge fermentation tank, the hot water inlet pipe and the cold water outlet pipe are respectively provided with switch valves, and a fermentation temperature sensor is provided in the biogas chamber of the sludge fermentation system;

[0010] A biogas power generation system, wherein the biogas output by the sludge fermentation system enters the biogas power generation system for power generation, and the waste gas and heat exchange hot gas generated by the biogas power generation system are connected to the sludge drying equipment for heat supply;

[0011] A sewage source heat pump system, wherein the hot gas generated by the sewage source heat pump system is connected to the sludge drying equipment for heating, and the hot water generated by the sewage source heat pump system is connected to the hot water inlet pipe of the sludge fermentation system for heating;

[0012] And a controller, which controls the opening and closing of the valves on the sludge drying equipment, sludge fermentation system, biogas power generation system, sewage source heat pump system and hot water inlet pipe and cold water outlet pipe according to the temperature of the drying temperature sensor and the fermentation temperature sensor.

[0013] The sludge drying equipment is a belt dryer, and the low-temperature gas output by the belt dryer is filtered by a second filter and then discharged.

[0014] The biogas power generation system includes a biogas engine, a generator, a first heat exchanger, a first fan, a second heat exchanger, a cooling water pump and a cooling water tower; the biogas engine and the generator are connected to provide mechanical energy; the biogas output by the sludge fermentation system is transported to the biogas engine, and the exhaust gas released by biogas power generation is filtered and transported to the sludge drying equipment for heating; the cold water output by the cooling water tower is heat exchanged with the biogas engine through the first heat exchanger to output hot water, and the output hot water enters the second heat exchanger to exchange heat with the air, and the hot air in the second heat exchanger is blown out by the first fan and transported to the sludge drying equipment for heating; the water exchanged in the second heat exchanger is pumped into the cooling water tower by the cooling water pump and cooled.

[0015] The sewage source heat pump system includes a sewage tank, a first filter, a sewage pump, a sewage heat exchanger, an intermediate water pump, an evaporator, a liquid storage tank, a compressor, a condenser, an expansion valve, a water storage tank, a diverter, a return flow device, a third heat exchanger and a second fan;

[0016] The sewage in the sewage pool is filtered through the first filter by the sewage pump and then pumped into the sewage heat exchanger. The sewage after heat exchange in the heat exchanger flows back to the sewage pool; after the liquid refrigerant in the evaporator and the relatively high-temperature intermediate water have thermal effects, the liquid refrigerant becomes gaseous refrigerant, and the relatively high-temperature intermediate water becomes relatively low-temperature intermediate water; the relatively low-temperature intermediate water is pumped into the sewage heat exchanger through the intermediate water pump to exchange heat with the sewage, and the relatively high-temperature intermediate water after heat exchange flows back to the evaporator; the gaseous refrigerant is stored in the liquid storage tank and then enters the compressor for compression to become high-temperature and high-pressure gas, and the high-temperature and high-pressure gas is condensed by the condenser and becomes liquid refrigerant. The refrigerant then enters the evaporator through the expansion valve; the cold water in the low-temperature water tank in the water storage tank is input into the condenser and becomes hot water after the action of the high-temperature and high-pressure gas, and flows back to the high-temperature water tank of the water storage tank. The hot water output from the high-temperature water tank is divided into two paths through the diverter. The first path is connected to one end of the hot water inlet pipe and input into the sludge fermentation tank for heating, and the second path enters the third heat exchanger for heat exchange with the air. The hot air in the second heat exchanger is blown out through the second fan and transported to the sludge drying equipment for heating; the cold water output from the third heat exchanger and the cold water output from one end of the cold water outlet pipe are merged through the merger and input into the low-temperature tank of the water storage tank.

[0017] A coil is laid inside the sludge fermentation system, the coil water inlet is connected to the other end of the hot water inlet pipe, and the coil water outlet is connected to the other end of the cold water outlet pipe.

[0018] The coil is a steel lined polytetrafluoroethylene tube.

[0019] The beneficial effects of the utility model are as follows: the utility model of a combined device for sludge drying and sludge fermentation and its operation control method use hot air as a drying medium to heat dry the sludge. After treatment, the moisture content of the sludge can be reduced to less than 10%, the microbial activity is inhibited, and it is convenient for transportation and long-term storage. The waste heat of sewage has great potential, especially for sewage treatment plants, it is a renewable energy source that is easy to use, and it is both economical and ecological. The present application uses the waste heat of sewage to carry out in-situ sludge drying treatment. On the one hand, it can overcome the heat energy loss caused by the transmission of heat sources outside the plant. On the other hand, the substantial reduction in the amount of sludge after drying can also reduce the energy consumption of sludge transportation and corresponding carbon emissions. The waste heat of sewage can also provide a heat source for the biogas warming system. A large amount of waste heat will be generated during the biogas power generation process. This waste heat can be recovered and used to dry the sludge, thereby improving the efficiency of energy utilization. The waste heat utilization of the biogas engine of the biogas power generation system can produce hot water at 90° or even higher temperatures. The exhaust gas temperature discharged by the biogas engine can reach between 300°C and 500°C, or even higher, and can be supplied to the sludge for drying after treatment. The sewage source heat pump system can heat water to a temperature range of 20-40℃.

[0020] In the process of sludge treatment, the utility model utilizes the renewable energy inside the sewage treatment plant to meet its own needs, and through multi-energy complementarity to offset the huge energy consumption required for sludge treatment, thereby achieving the composite energy of urban sewage treatment plants to "energy saving, carbon reduction and efficiency improvement" and realize the goal of near-zero carbon operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of a combined device for sludge drying and sludge fermentation of the utility model;

[0022] Figure 2 It is a schematic diagram of a biogas power generation system in a combined device for sludge drying and sludge fermentation of the utility model;

[0023] Figure 3 The utility model is a schematic diagram of a sewage source heat pump system in a combined device for sludge drying and sludge fermentation. DETAILED DESCRIPTION

[0024] The embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0025] See also Figure 1-Figure 3 The utility model provides a combined device for sludge drying and sludge fermentation, comprising:

[0026] Sludge drying equipment, wherein a drying temperature sensor is provided in a drying chamber of the sludge drying equipment;

[0027] A sludge fermentation system, the sludge fermentation system comprising a hot water inlet pipe and a cold water outlet pipe connected to the sludge fermentation tank, the hot water inlet pipe and the cold water outlet pipe are respectively provided with switch valves, and a fermentation temperature sensor is provided in the biogas chamber of the sludge fermentation system;

[0028] Biogas power generation system, the biogas output by the sludge fermentation system passes through a desulfurizer, a dehydrator and a gas storage tank in sequence and then enters the biogas power generation system to generate electricity, and the waste gas and heat exchange hot gas generated by the biogas power generation system are connected to the sludge drying equipment for heat supply;

[0029] A sewage source heat pump system, wherein the hot gas generated by the sewage source heat pump system is connected to the sludge drying equipment for heating, and the hot water generated by the sewage source heat pump system is connected to the hot water inlet pipe of the sludge fermentation system for heating;

[0030] And a controller, which controls the opening and closing of the valves on the sludge drying equipment, sludge fermentation system, biogas power generation system, sewage source heat pump system and hot water inlet pipe and cold water outlet pipe according to the temperature of the drying temperature sensor and the fermentation temperature sensor.

[0031] The sludge drying device adopts a belt dryer with a simple structure, easy to operate, maintain and control. The low-temperature gas output by the belt dryer is discharged after being filtered by the second filter. The belt dryer is provided with a drying chamber, and a conveyor belt is provided in the drying chamber. The conveyor belt leads from the entrance of the drying chamber to the outlet. The wet sludge is sent to the conveyor belt from the entrance of the drying chamber, and the dried dry sludge is sent to the outlet of the drying chamber by the conveyor belt. The belt dryer has strong adaptability and can adapt to various materials and materials of different shapes. It can not only perform a certain shearing action on the material, which is conducive to the diffusion of water molecules inside the material and accelerates the drying speed, but also effectively utilize various heat sources, such as hot water, steam, thermal oil, etc. This makes the drying process more uniform and of good quality, and greatly reduces the occurrence of coking. In addition, during the operation of the dryer, the environment is good, there is no dust and exhaust gas emission, it is harmless to workers and the environment, and it is an environmentally friendly and efficient sludge drying equipment.

[0032] The biogas power generation system includes a biogas engine, a generator, a first heat exchanger, a first fan, a second heat exchanger, a cooling water pump and a cooling water tower; the biogas engine and the generator are connected to provide mechanical energy; the biogas output by the sludge fermentation system is transported to the biogas engine, and the waste gas released by biogas power generation is filtered and transported to the sludge drying equipment for heating; the cold water output by the cooling water tower is heat exchanged with the biogas engine through the first heat exchanger to output hot water, and the output hot water enters the second heat exchanger for heat exchange with the air, and the hot air in the second heat exchanger is blown out by the first fan and transported to the sludge drying equipment for heating; the water exchanged in the second heat exchanger is pumped into the cooling water tower by the cooling water pump and cooled. The biogas engine is a gas generator set, in which the fuel is biogas, and the working principle of the biogas engine is to convert the heat energy generated by the combustion of biogas into power, thereby driving the generator to rotate, thereby generating electrical energy.

[0033] The working process of the biogas power generation system is as follows: the biogas produced by anaerobic fermentation treatment is used on the biogas engine, and a comprehensive power generation device and a generator are installed to generate electricity and heat energy. The biogas power generation system is equipped with a cooling water tower and a cooling water pump, which helps to keep the system temperature stable and ensure the normal operation of the system. The function of the cooling water tower is to collect the heat in the system and dissipate it to the surrounding environment. The cooling water tower is made of metal materials and has high heat dissipation performance. They can dissipate heat to the surrounding environment through radiation or conduction to reduce the temperature of the system. The function of the cooling water pump is to circulate the cooling water in the system to absorb and dissipate the heat in the system. The cooling water pump is driven by a motor to extract the cooling water from the water tank or water pipe through the pipeline system and transport it to the cooling water tower. When the cooling water flows out of the cooling water pump, it is absorbed and dissipated to the surrounding environment to reduce the temperature of the system. The cooling water exchanges heat with the generator set through the first heat exchanger, takes away the heat generated by the generator set, and thus maintains the normal operating temperature of the generator set. Then it exchanges heat with the air in the second heat exchanger. The heated air and high-temperature exhaust gas generated by biogas power generation are sent to the sludge drying equipment.

[0034] The sewage source heat pump system includes a sewage tank, a first filter, a sewage pump, a sewage heat exchanger, an intermediate water pump, an evaporator, a liquid storage tank, a compressor, a condenser, an expansion valve, a water storage tank, a diverter, a return flow device, a third heat exchanger and a second fan;

[0035] The sewage in the sewage pool is filtered through the first filter by the sewage pump and then pumped into the sewage heat exchanger. The sewage after heat exchange in the heat exchanger flows back to the sewage pool; after the liquid refrigerant in the evaporator and the relatively high-temperature intermediate water have thermal effects, the liquid refrigerant becomes gaseous refrigerant, and the relatively high-temperature intermediate water becomes relatively low-temperature intermediate water; the relatively low-temperature intermediate water is pumped into the sewage heat exchanger through the intermediate water pump to exchange heat with the sewage, and the relatively high-temperature intermediate water after heat exchange flows back to the evaporator; the gaseous refrigerant is stored in the liquid storage tank and then enters the compressor for compression to become high-temperature and high-pressure gas, and the high-temperature and high-pressure gas is condensed by the condenser and becomes liquid refrigerant. The refrigerant then enters the evaporator through the expansion valve; the cold water in the low-temperature water tank in the water storage tank is input into the condenser and becomes hot water after the action of the high-temperature and high-pressure gas, and flows back to the high-temperature water tank of the water storage tank. The hot water output from the high-temperature water tank is divided into two paths through the diverter. The first path is connected to one end of the hot water inlet pipe and input into the sludge fermentation tank for heating, and the second path enters the third heat exchanger for heat exchange with the air. The hot air in the second heat exchanger is blown out through the second fan and transported to the sludge drying equipment for heating; the cold water output from the third heat exchanger and the cold water output from one end of the cold water outlet pipe are merged through the merger and input into the low-temperature tank of the water storage tank.

[0036] The working process of the sewage source heat pump system is that the sewage pump extracts sewage from the sewage pool to the sewage heat exchanger to exchange heat with the intermediate water, where the intermediate water is pumped out from the evaporator by the intermediate water pump. After the sewage is heat exchanged, it flows back to the sewage pool. The outlet of the evaporator is connected to the intermediate water pump; in the evaporator, the intermediate water is in cyclic contact with the refrigerant. The heat of the intermediate water is absorbed by the refrigerant, causing the water temperature to drop. After absorbing the heat, the refrigerant evaporates into a gaseous state and then enters the compressor. The compressor inhales the gaseous refrigerant sent from the evaporator and compresses it into a high-temperature and high-pressure gas. This process consumes electrical energy. The compressed high-temperature and high-pressure gas is sent to the condenser. The high-temperature and high-pressure gas enters the condenser and exchanges heat with the cold water flow sent from the water storage tank. The gas condenses into liquid after releasing heat. This process requires releasing a lot of heat. The cold water passing through the condenser is heated and sent to the high-temperature water tank of the water storage tank. The hot water in the high-temperature water tank is indirectly heat-exchanged with the air in the third heat exchanger. After the air is heated, it is blown into the sludge dryer through the fan for sludge drying. Another part of the water in the high-temperature water tank is directly used to heat the sludge fermentation system through the hot water inlet pipe. The liquid refrigerant flows into the evaporator through the expansion valve to complete the circulation.

[0037] The sludge fermentation system is provided with a coil, the coil water inlet is connected to the other end of the hot water inlet pipe, and the coil water outlet is connected to the other end of the cold water outlet pipe. The heat source of the sludge fermentation system comes from the sewage source heat pump system. First, cold water flows from the cold water outlet pipe through the manifold into the low-temperature water tank of the water storage tank.

[0038] Coils are laid on the inner wall of the sludge fermentation system. After the hot water in the high-temperature water tank of the water storage tank is diverted by the diverter, part of it enters the coil through the hot water inlet pipe. The hot water in the coil can provide heat for the fermentation tank in winter or low temperature environment, so that the fermentation process can be carried out at a suitable temperature. Appropriate heating can accelerate the activity of microorganisms, thereby accelerating the decomposition of organic matter and completing the fermentation process faster. It should be noted that during the design and construction process, it is necessary to ensure that the material of the coil can withstand the acid and alkali environment during the fermentation process, and to do a good job of anti-corrosion treatment to prevent the coil from being corroded and perforated and causing leakage. Therefore, the pipe material is selected as a steel-lined PTFE pipe. The inner wall of this pipe is coated with a layer of polytetrafluoroethylene (PTFE), which has extremely strong corrosion resistance and good thermal stability, and is suitable for environments with strong acidity and alkali and large temperature changes. At the same time, in order to ensure safe operation, regular maintenance and inspection are required to promptly discover and deal with possible problems. It is used to improve the efficiency of biogas production. While treating sludge, the system achieves the purpose of improving the quality and efficiency of energy.

[0039] An operation control method of a combined device for sludge drying and sludge fermentation is as follows: starting the sludge drying equipment, the sludge fermentation system and the biogas power generation system through a control system; collecting the drying temperature inside the sludge drying equipment through a drying temperature sensor, and collecting the fermentation temperature inside the sludge fermentation system through a fermentation temperature sensor;

[0040] If the drying temperature is greater than 90°C, the controller controls the biogas power generation system to shut down; if the drying temperature is less than 60°C, the controller controls the sewage source heat pump system to start;

[0041] When the sewage source heat pump system is turned on, if the fermentation temperature is less than 36°C, the controller controls the switch valves on the hot water inlet pipe and the cold water outlet pipe to open; if the fermentation temperature is greater than or equal to 36°C, the controller controls the switch valves on the hot water inlet pipe and the cold water outlet pipe to close.

[0042] In this system, the sludge fermentation system and the sludge drying system are two major energy-consuming equipment, and the biogas power generation system and the sewage source heat pump system are devices that provide heat energy. The biogas fermentation temperature can be divided into a normal temperature fermentation zone of 10℃-26℃, a medium temperature fermentation zone of 28℃-38℃, and a high temperature fermentation zone of 46℃-60℃. Since the medium temperature anaerobic fermentation raw materials have a high gas production rate and good economic benefits, they have become the first choice for most biogas projects. During the operation of the biogas engineering system, when the fermentation tank temperature is ≥36℃, the sewage source heat pump system heating system does not heat the sludge fermentation system; when the fermentation tank temperature is <36℃, the sewage source heat pump system heating system heats the sludge fermentation system. In the sewage source heat pump system, heat can be absorbed from the sewage in the sewage pool, and the heat is transferred to the water flowing through the condenser through the condenser.

[0043] Sludge evaporation and dehydration drying is divided into high-temperature drying and low-temperature drying. High-temperature drying will cause the harmful substances in the sludge to volatilize, and the stability and safety of high-temperature equipment are poor, so it has been gradually eliminated, so low-temperature drying is now generally used. Sludge low-temperature drying is a subdivision technology of sludge drying. The main drying temperature is below 90 degrees, which belongs to low-temperature drying. The present application adopts the form of low-temperature drying. Low-temperature drying uses circulating hot air (about 70 degrees) to evaporate the moisture in the sludge. Due to the low temperature, harmful substances do not decompose and cannot volatilize, and the stability and safety of the equipment are greatly improved. When the temperature of the sludge drying equipment is less than 60°C, the biogas power generation waste gas heating is started. The sludge drying equipment is mainly provided by the waste heat of biogas power generation and the waste heat of sewage.

[0044] The hot air used in the sludge drying equipment releases heat and becomes low-temperature wet air with a high moisture content. It may contain some impurities in the exhaust gas produced by the biogas engine and will not be recycled but discharged directly.

[0045] The temperature of the waste gas produced by the biogas power generation system can reach between 300℃ and 500℃, or even higher, but it contains impurities. A filtering device is set on the low-temperature gas passing through the outlet of the drying equipment to filter out some of the impurities and avoid impact on the outside world.

[0046] Before the sewage enters the sewage heat exchanger, it will pass through the first filter to filter out impurities in the sewage to avoid affecting the heat exchange effect and possibly blocking the heat exchanger.

[0047] A liquid storage tank is set up in the sewage source heat pump system. The liquid storage tank is mainly used to store refrigerant to ensure that the refrigerant is sufficient during the circulation process; the liquid storage tank can store excess heat medium to ensure that the water flow on the heat pump side matches the gradually changing water flow on the heat source side, thereby stabilizing the operation of the system. It provides buffer space to prevent abnormal pressure, improve the efficiency of the heat pump, and extend its service life.

[0048] During the biogas power generation process, the electricity generated by the biogas engine is used to meet all or part of the electricity demand of the sewage treatment plant. When the output is lower than the demand, the electricity is provided by the power grid. A hot water diverter and a cold water concentrator are set on the water storage tank side. The hot water in the water storage tank is diverted to the sludge fermentation system and indirectly to the sludge drying system. The low-temperature water after heat exchange flows into the high-temperature water storage tank through the concentrator to complete the cycle.

Claims

1. A combined device for sludge drying and sludge fermentation, characterized in that: include: A sludge drying device, wherein a drying temperature sensor is provided in a drying chamber of the sludge drying device; A sludge fermentation system, the sludge fermentation system comprising a hot water inlet pipe and a cold water outlet pipe connected to the sludge fermentation tank, the hot water inlet pipe and the cold water outlet pipe are respectively provided with switch valves, and a fermentation temperature sensor is provided in the biogas chamber of the sludge fermentation system; A biogas power generation system, wherein the biogas output by the sludge fermentation system enters the biogas power generation system for power generation, and the waste gas and heat exchange hot gas generated by the biogas power generation system are connected to the sludge drying equipment for heat supply; A sewage source heat pump system, wherein the hot gas generated by the sewage source heat pump system is connected to the sludge drying equipment for heating, and the hot water generated by the sewage source heat pump system is connected to the hot water inlet pipe of the sludge fermentation system for heating; And a controller, which controls the opening and closing of the valves on the sludge drying equipment, sludge fermentation system, biogas power generation system, sewage source heat pump system and hot water inlet pipe and cold water outlet pipe according to the temperature of the drying temperature sensor and the fermentation temperature sensor.

2. A combined device for sludge drying and sludge fermentation according to claim 1, characterized in that: The sludge drying equipment is a belt dryer, and the low-temperature gas output by the belt dryer is filtered by a second filter and then discharged.

3. A combined device for sludge drying and sludge fermentation according to claim 1, characterized in that: The biogas power generation system includes an engine, a generator, a first heat exchanger, a first fan, a second heat exchanger, a cooling water pump and a cooling water tower; the engine and the generator are connected to provide mechanical energy; the biogas output by the sludge fermentation system is transported to the biogas engine, and the exhaust gas released by the biogas power generation is filtered and transported to the sludge drying equipment for heating; the cold water output by the cooling water tower is heat exchanged with the engine through the first heat exchanger to output hot water, and the output hot water enters the second heat exchanger to exchange heat with the air, and the hot air in the second heat exchanger is blown out by the first fan and transported to the sludge drying equipment for heating; the water exchanged in the second heat exchanger is pumped into the cooling water tower by the cooling water pump and cooled.

4. A combined device for sludge drying and sludge fermentation according to claim 1, characterized in that: The sewage source heat pump system includes a sewage tank, a first filter, a sewage pump, a sewage heat exchanger, an intermediate water pump, an evaporator, a liquid storage tank, a compressor, a condenser, an expansion valve, a water storage tank, a diverter, a return flow device, a third heat exchanger and a second fan; The sewage in the sewage pool is filtered through the first filter by the sewage pump and then pumped into the sewage heat exchanger. The sewage after heat exchange in the heat exchanger flows back to the sewage pool; after the liquid refrigerant in the evaporator and the relatively high-temperature intermediate water have thermal effects, the liquid refrigerant becomes gaseous refrigerant, and the relatively high-temperature intermediate water becomes relatively low-temperature intermediate water; the relatively low-temperature intermediate water is pumped into the sewage heat exchanger through the intermediate water pump to exchange heat with the sewage, and the relatively high-temperature intermediate water after heat exchange flows back to the evaporator; After being stored in a liquid storage tank, the gaseous refrigerant enters the compressor for compression to become a high-temperature and high-pressure gas. After being condensed by the condenser, the high-temperature and high-pressure gas becomes a liquid refrigerant and then enters the evaporator through the expansion valve; the cold water in the low-temperature water tank in the water storage tank is input into the condenser and reacts with the high-temperature and high-pressure gas to become hot water and flow back to the high-temperature water tank of the water storage tank. The hot water output from the high-temperature water tank is divided into two paths by a diverter. The first path is connected to one end of the hot water inlet pipe and input into the sludge fermentation tank for heating, and the second path enters the third heat exchanger for heat exchange with the air. The hot air in the second heat exchanger is blown out by the second fan and transported to the sludge drying equipment for heating; the cold water output from the third heat exchanger and the cold water output from one end of the cold water outlet pipe are merged by a merger and input into the low-temperature tank of the water storage tank.

5. A combined device for sludge drying and sludge fermentation according to claim 4, characterized in that: A coil is laid inside the sludge fermentation system, the coil water inlet is connected to the other end of the hot water inlet pipe, and the coil water outlet is connected to the other end of the cold water outlet pipe.

6. A combined device for sludge drying and sludge fermentation according to claim 5, characterized in that: The coil is a steel lined polytetrafluoroethylene tube.

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