A photothermal and coal-fired coupled sludge drying system

Abstract

The present invention discloses a photothermal-coal-fired coupled sludge drying system, comprising a sludge pre-dryer, a sludge dryer, a unit steam source module, and a photothermal steam source module; the control device is configured to: when it is detected that the outlet steam of the photothermal steam generator meets the preset sludge drying steam condition, start the photothermal steam drying mode, control the steam input end of the sludge dryer to be connected to the steam output end of the photothermal steam generator, and start the sludge dryer; when it is detected that the outlet steam of the photothermal steam generator meets the non-preset sludge drying steam condition, start the unit auxiliary steam drying mode, control the steam input end of the sludge dryer to be connected to the steam output end of the unit steam source module, and start the sludge dryer. By coupling photothermal and coal to provide a heat source for sludge drying, the impact on the unit thermal system of the coal-fired power plant is reduced or even completely eliminated, and the energy availability of the sludge drying system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sludge drying, and in particular to a photothermal-coal-fired coupled sludge drying system. Background Art

[0002] Sludge from urban sewage treatment plants is a kind of solid waste, mainly composed of sludge from primary sedimentation tanks (sand traps) and oil separators, scum from flotation machines, residual activated sludge, and chemical sludge from other process units. Its composition is relatively complex. Sludge from urban sewage treatment plants generally has a water content of about 80%, is rich in nutrients such as organic matter, and contains a certain amount of heavy metals and harmful substances such as viruses, pathogens, and parasite eggs. In the water treatment industry, "heavy water and light sludge" has long been a common phenomenon. Sludge is still mainly landfilled in traditional ways, and with the changes in climate and seasons, the polluting gases and odors it emits will have a serious impact on surrounding residents.

[0003] Compared with traditional sludge treatment and disposal methods such as sanitary landfill, use as agricultural fertilizer, and pyrolysis, the incineration method has the advantages of volume reduction, resource utilization, harmlessness, rapidity, and energy recovery, and has broad application prospects. Its treatment methods include single incineration and mixed incineration. However, sludge currently has the characteristics of high moisture, high ash content, high viscosity, and low calorific value, which leads to the disadvantages of incomplete incineration and difficult precipitation of volatile matter when sludge is incinerated alone. If the sludge is mixed with coal powder and sent to the existing coal-fired boiler for combustion, the efficient power generation technology and environmental protection management system of the coal-fired unit can be fully utilized, which not only solves the problem of stable combustion of sludge, but also the pollutants generated after combustion can be cleanly treated, without the need to invest in the construction of an incinerator, fundamentally solving the problem of local sludge disposal and environmental pollution; in addition, the calorific value of sludge can be used to generate electricity and generate income, turning waste into treasure. However, coal-fired power plants have high requirements for the safety of equipment operation, and the wet sludge from urban sewage treatment plants has a high moisture content. The mixed fuel formed by directly mixing the wet sludge with coal powder will seriously deviate from the requirements of the coal type designed for the power plant boiler due to its high moisture content. In view of this, in order to ensure the safe and stable operation of coal-fired units that burn sludge for a long time, the existing technology designs and builds a sludge drying system that reduces the moisture content of the wet sludge before burning it. However, the drying system usually uses steam or flue gas as a heat source to dry the sludge, which will inevitably affect the thermal system of the coal-fired power plant unit. Summary of the invention

[0004] The present invention provides a photothermal and coal-fired coupled sludge drying system to solve the technical problem that the existing sludge drying system uses steam or flue gas to dry sludge, which affects the thermal system of the unit. By coupling photothermal and coal to provide a heat source for sludge drying, the impact on the thermal system of the unit of the coal-fired power plant is reduced or even completely eliminated, while the energy utilization rate of the sludge drying system is improved.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a photothermal coal-fired coupled sludge drying system, which at least includes:

[0006] The sludge drying device at least comprises a sludge predryer and a sludge dryer; the sludge output end of the sludge predryer is connected to the sludge input end of the sludge dryer through a conveying pipeline;

[0007] A heat source device, comprising a steam source module for the unit and a photothermal steam source module for converting light energy into fluid thermal energy; the steam output end of the steam source module for the unit and the steam output end of the photothermal steam generator in the photothermal steam source module are respectively connected to the steam input end of the sludge dryer through pipelines;

[0008] A control device configured to:

[0009] When it is detected that the outlet steam of the photothermal steam generator meets the preset sludge drying steam condition, the photothermal steam drying mode is started, the steam input end of the sludge dryer is controlled to be connected to the steam output end of the photothermal steam generator, and the sludge dryer is started;

[0010] When it is detected that the outlet steam of the photothermal steam generator meets the non-preset sludge drying steam conditions, the auxiliary steam drying mode of the unit is started, the steam input end of the sludge dryer is controlled to connect to the steam output end of the steam source module of the unit, and the sludge dryer is started.

[0011] In one embodiment of the present invention, the photothermal-coal-fired coupled sludge drying system further comprises:

[0012] A solar thermal power generation device, which includes a steam turbine, a generator, and a battery pack;

[0013] The steam input end of the steam turbine is connected to the steam output end of the solar thermal steam generator through a pipeline, the output end of the steam turbine is connected to the generator, the power output end of the generator is connected to the battery pack, and the battery pack is connected to the power supply end of the sludge predryer;

[0014] The control device is further configured to:

[0015] When operating in the photothermal power generation mode, the steam output end of the photothermal steam generator is controlled to be connected to the steam turbine so that the generator generates electricity.

[0016] In one embodiment of the present invention, the solar thermal steam source module comprises:

[0017] An expansion tank, a heat transfer fluid pump, a solar collector and the photothermal steam generator;

[0018] The fluid output end of the solar thermal collector is connected to the fluid input end of the solar thermal steam generator, the fluid output end of the solar thermal steam generator is connected to the fluid input end of the heat transfer fluid pump through the expansion tank, and the fluid output end of the heat transfer fluid pump is connected to the fluid input end of the solar thermal collector.

[0019] In one embodiment of the present invention, the solar thermal steam source module further includes a first electrically controlled valve controlled by the control device;

[0020] The steam output end of the photothermal steam generator is connected to the steam input end of the sludge dryer through the first electrically controlled valve.

[0021] In one embodiment of the present invention, the steam source module of the unit includes an auxiliary steam main pipe of the unit and a second electrically controlled valve controlled by the control device;

[0022] The steam output end of the auxiliary steam main pipe of the unit is connected to the steam input end of the sludge dryer through the second electric control valve.

[0023] In one embodiment of the present invention, the sludge drying device further comprises a wet sludge storage bin and a sludge pre-dryer;

[0024] The sludge output end of the wet sludge storage bin is connected to the sludge input end of the sludge predryer through a conveying pipeline, and the sludge output end of the sludge predryer is connected to the sludge input end of the sludge dryer through a conveying pipeline.

[0025] In one embodiment of the present invention, the sludge drying device further includes sewage treatment equipment;

[0026] The input end of the sewage treatment equipment is connected to the sewage discharge end of the sludge dryer.

[0027] In one embodiment of the present invention, the sludge drying device further includes a boiler pulverizing system;

[0028] The dried sludge outlet of the sludge dryer is connected to the boiler pulverizing system through a conveying mechanism.

[0029] In one embodiment of the present invention, the photothermal-coal-fired coupled sludge drying system further comprises:

[0030] Unit condenser, steam cooler, and water supply equipment;

[0031] The heat exchange fluid output end of the sludge dryer is respectively connected to the input end of the unit condenser and the input end of the steam cooler;

[0032] The output end of the steam cooler and the output end of the water replenishment device are connected to the steam recovery end of the photothermal steam generator through a water pump.

[0033] In one embodiment of the present invention, a plurality of manual valves are provided on the connecting pipeline between the steam source module of the unit and the steam input end of the sludge dryer, and on the connecting pipeline between the photothermal steam source module and the steam input end of the sludge dryer.

[0034] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0035] (1) By coupling the steam source module of the unit and the solar thermal steam source module, the solar thermal-coal energy combination is realized, and high-temperature steam is synergistically generated for the sludge drying system to dry the sludge, which can improve the energy utilization rate of the sludge drying system.

[0036] (2) When the solar thermal steam drying mode is started and operated, there is no need to use the steam from the auxiliary steam main of the unit. This method has no effect on the thermal system of the unit.

[0037] (3) When the auxiliary steam drying mode of the unit is started and operated, the auxiliary steam supply of the unit is smaller than that when there is no pre-dryer because the sludge is pre-dried by the sludge pre-dryer. This method reduces the impact on the thermal system of the unit.

[0038] (4) When the sludge drying system is performing sludge drying operations, there are two steam sources available for drying the sludge. The heat of one steam source comes from coal, and the heat of the other steam source comes from solar energy. The setting of two steam sources greatly increases the availability of the sludge drying system.

[0039] (5) When there is no need for sludge drying, the steam generated by the solar thermal steam generator can be used to drive a small steam turbine generator set to generate electricity. The generated electricity is stored in a group of batteries. When sludge drying is required, the battery group will power the sludge pre-dryer. This method fully utilizes the output of the solar thermal module. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic structural diagram of a photothermal coal-fired coupled sludge drying system according to one embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the division of a photothermal coal-fired coupled sludge drying system according to one embodiment of the present invention;

[0042] Figure 3 This is an operating principle diagram of a photothermal coal-fired coupled sludge drying system according to one embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the system operation of a photothermal coal-fired coupled sludge drying system in one embodiment of the present invention when the unit is operated in the auxiliary steam drying mode;

[0044] Figure 5 This is a schematic diagram of the system operation of a photothermal coal-fired coupled sludge drying system in one embodiment of the present invention when operating in a photothermal steam drying mode;

[0045] Figure 6 This is a schematic diagram of the system operation of a photothermal coal-fired coupled sludge drying system in one embodiment of the present invention when operating in a power generation mode;

[0046] The reference numerals in the accompanying drawings of the specification are as follows:

[0047] 1. Auxiliary steam main pipe of the unit; 2. The first electric control valve; 3. Electric valve; 4. Wet sludge storage bin; 5. Sludge conveying pipeline; 6. Wet sludge; 7. Sludge pre-dryer; 8. Sludge dryer; 9. Dry sludge; 10. Boiler pulverizing system; 11. Steam turbine; 12. Generator; 13. Battery pack; 14. Sewage treatment equipment; 15. Unit condenser; 16. Steam cooler; 17. Water make-up equipment; 18. Feed water pump; 19. Expansion tank; 20. Heat transfer fluid pump; 21. Solar collector; 22. Photothermal steam generator; 23. The second electric control valve. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] See also Figure 1 , Figure 1 A photothermal-coal-fired coupled sludge drying system according to one embodiment of the present invention is shown, comprising at least:

[0050] The sludge drying device at least comprises a sludge predryer 7 and a sludge dryer 8; the sludge output end of the sludge predryer 7 is connected to the sludge input end of the sludge dryer 8 through a conveying pipeline;

[0051] The sludge drying device also includes a wet sludge storage bin 4, a sludge pre-dryer 7, a sewage treatment device 14, and a boiler pulverizing system 10;

[0052] The sludge output end of the wet sludge storage bin 4 is connected to the sludge input end of the sludge predryer 7 through the sludge conveying pipe 5, the sludge output end of the sludge predryer 7 is connected to the sludge input end of the sludge dryer 8 through the conveying pipe, the input end of the sewage treatment equipment 14 is connected to the sewage discharge end of the sludge dryer 8, and the dried sludge outlet of the sludge dryer 8 is connected to the boiler pulverizing system 10 through a conveying mechanism.

[0053] The heat source device includes a steam source module for the unit and a photothermal steam source module for converting light energy into fluid thermal energy; the steam output end of the steam source module for the unit and the steam output end of the photothermal steam generator 22 in the photothermal steam source module are respectively connected to the steam input end of the sludge dryer 8 through pipelines;

[0054] The solar thermal steam source module includes:

[0055] An expansion tank 19, a heat transfer fluid pump 20, a solar collector 21, a photothermal steam generator 22, and a first electrically controlled valve 3 controlled by a control device;

[0056] The fluid output end of the solar thermal collector 21 is connected to the fluid input end of the solar thermal steam generator 22, the fluid output end of the solar thermal steam generator 22 is connected to the fluid input end of the heat transfer fluid pump 20 through the expansion tank 19, and the fluid output end of the heat transfer fluid pump 20 is connected to the fluid input end of the solar thermal collector 21; the steam output end of the solar thermal steam generator 22 is connected to the steam input end of the sludge dryer 8 through the first electric control valve.

[0057] The steam source module of the unit includes:

[0058] Auxiliary steam main pipe 1 of the unit, a second electric control valve 23 controlled by the control device;

[0059] The steam output end of the auxiliary steam main pipe 1 of the unit is connected to the steam input end of the sludge dryer 8 through the second electric control valve 23.

[0060] A control device configured to:

[0061] When it is detected that the outlet steam of the photothermal steam generator 22 meets the preset sludge drying steam condition, the photothermal steam drying mode is started, the steam input end of the sludge dryer 8 is controlled to be connected to the steam output end of the photothermal steam generator 22, and the sludge dryer 8 is started;

[0062] When it is detected that the outlet steam of the photothermal steam generator 22 meets the non-preset sludge drying steam conditions, the unit auxiliary steam drying mode is started, the steam input end of the sludge dryer 8 is controlled to connect to the steam output end of the unit steam source module, and the sludge dryer 8 is started.

[0063] In one embodiment of the present invention, the photothermal-coal-fired coupled sludge drying system further includes:

[0064] A solar thermal power generation device, comprising a steam turbine 11, a generator 12, and a battery pack 13;

[0065] The steam input end of the steam turbine 11 is connected to the steam output end of the photothermal steam generator 22 through a pipeline, the output end of the steam turbine 11 is connected to the generator 12, the power output end of the generator 12 is connected to the battery group 13, and the battery group 13 is connected to the power supply end of the sludge pre-dryer 7;

[0066] The control device is further configured to:

[0067] When operating in the CSP power generation mode, the steam output end of the CSP steam generator 22 is controlled to be connected to the steam turbine 11 so that the generator 12 generates electricity.

[0068] In addition, in one embodiment of the present invention, the solar-thermal-coal-fired coupled sludge drying system further includes:

[0069] Unit condenser 15, steam cooler 16, water supply equipment 17;

[0070] The heat exchange fluid output end of the sludge dryer 8 is connected to the input end of the unit condenser 15 and the input end of the steam cooler 16 respectively;

[0071] The output end of the steam cooler 16 and the output end of the water replenishment device 17 are connected to the steam recovery end of the solar thermal steam generator 22 through a water pump.

[0072] In one embodiment of the present invention, a plurality of manual valves 2 are provided on the connecting pipeline between the steam source module of the unit and the steam input end of the sludge dryer 8 and on the connecting pipeline between the photothermal steam source module and the steam input end of the sludge dryer 8 .

[0073] In this embodiment, if Figure 2 As shown, the sludge drying system is mainly divided into a steam module part and a photothermal module part, and the two parts are coupled through a photothermal steam generator 22, which are described in detail below:

[0074] The photothermal module converts solar energy into the heat energy of the heat transfer fluid itself, and is specifically composed of a solar collector 21, a photothermal steam generator 22 (surface heat exchanger), an expansion tank 19, and a heat transfer fluid pump 20 connected by a heat transfer fluid pipeline. During operation, the heat transfer fluid is heated to a certain temperature in the solar collector 21 and then sent to the steam generator for cooling. It is then pressurized by the heat transfer fluid pump 20 and then sent to the solar collector 21 for heating. The volume change of the heat transfer fluid in the pipeline due to thermal expansion and contraction is borne by the expansion tank 19.

[0075] The steam module part mainly supplies high-temperature steam to the sludge dryer 8 (surface heat exchanger), and its secondary function is to supply high-temperature steam to the small steam turbine generator 12 group. It is specifically composed of steam pipes, water pipes, manual valves 2, electric valves, sludge dryers 8, sludge pre-dryers 7 (electric heating), steam coolers 16 (surface heat exchangers), solar thermal steam generators 22, feed water pumps 18, steam turbines 11, generators 12, and battery packs 13.

[0076] Among them, the steam module part can be divided into the following according to the different steam sources:

[0077] The unit steam source submodule and the solar thermal steam source submodule are coupled through the sludge dryer 8 and the drying steam main pipe. The operating principle is as follows:

[0078] a) When the steam source submodule of the unit is selected for operation, high-temperature steam is supplied by the auxiliary steam main pipe 1 of the unit, and the wet sludge 6 in the wet sludge storage bin 4 is sent to the sludge pre-dryer 7 through the conveying pipeline, and then sent to the sludge dryer 8 to be dried by the high-temperature steam from the auxiliary steam main pipe 1 of the coal-fired unit. The dried sludge is sent to the coal transportation system or the pulverizing system to be mixed with the raw coal, and the water in the wet sludge 6 is heated to form a sludge steam-water mixture and then sent to the sewage treatment equipment 14 for treatment. The cooled steam is sent to the unit condenser 15 for cooling and then returns to the steam turbine thermal system;

[0079] b) When the photothermal steam source submodule is selected for operation, high-temperature steam is provided by the steam generator. The steam can heat the wet sludge in the sludge dryer 8 or drive the small steam turbine generator 12 to generate electricity. If the steam is used to dry the sludge, the wet sludge 6 in the wet sludge storage bin 4 is sent to the sludge pre-dryer 7 through the conveying pipeline, and then sent to the sludge dryer 8 to be dried by the high-temperature steam from the steam generator. The dried dry sludge 9 is sent to the boiler pulverizing system 10 and mixed with raw coal. The moisture in the wet sludge 6 is heated into a sludge steam-water mixture and then sent to the sewage treatment equipment 14 for treatment. The cooled steam is sent to the steam cooler 16 to be cooled into water and then pressurized by the feed water pump 18 to be heated by the steam generator. If the steam is used to generate electricity, the steam is used to drive the small steam turbine generator 12 to generate electricity, and the generated electricity is sent to a group of batteries for storage. The electricity in the battery is mainly used to power the sludge preheater and secondarily to power the DC load of the coal-fired power plant.

[0080] For ease of understanding, please refer to Figures 3 to 6 As shown, the operation mode of the above sludge drying system is:

[0081] When wet sludge is sent to a coal-fired power plant for treatment, the system operates in a drying mode. Generally, high-temperature steam of about 200°C is required to dry the sludge. To explain the present invention, it is required that the steam pressure for drying reaches 10 bar and the temperature reaches 230°C to achieve a better drying effect. The steam parameters of the auxiliary steam main pipe 1 of the coal-fired unit can generally reach this level.

[0082] When the outlet steam parameters of the CSG 22 do not meet the required values, the "Unit Auxiliary Steam Drying Steam Operation Ticket" is executed. For ease of explanation, the corresponding valves are numbered here (the same below), such as Figure 3 The main contents of the operation ticket are:

[0083] 1) Close the electric valves UV102 and UV103 by remote operation;

[0084] 2) Close the manual valves HV102, HV103, and HV202 on site, and confirm again that the electric valves UV102 and UV103 are closed;

[0085] 3) Open the electric valve UV101 by remote operation;

[0086] 4) Open the manual valves HV101, HV301, HV302, and HV201 on site. After the above operation ticket is executed, the steam source submodule of the unit is put into operation, and the system status is as follows: Figure 4 , Figure 4 The black middle valve represents closed, and vice versa represents open. At this time, the wet sludge 6 first passes through the sludge pre-dryer 7 and then is dried by the steam of the auxiliary steam main pipe 1 of the unit in the sludge dryer 8.

[0087] When wet sludge is sent to a coal-fired power plant for treatment, the system operates in a drying mode. When the steam parameters at the steam generator outlet reach the required values, the "Solar Thermal Drying Steam Operation Ticket" is executed. Figure 3 As shown, the main contents of the operation ticket are:

[0088] 1) Close the electric valves UV101 and UV103 by remote operation;

[0089] 2) Close the manual valves HV101, HV103, and HV201 on site, and confirm again that the electric valves UV101 and UV103 are closed;

[0090] 3) Open the electric valve UV102 by remote operation;

[0091] 4) Open the manual valves HV102, HV301, HV302, and HV202 on site. After the above operation ticket is executed, the solar thermal steam source submodule is put into operation, and the system status is as follows: Figure 5 , Figure 5The black middle valve represents closing, and vice versa represents opening. At this time, the wet sludge 6 first passes through the sludge pre-dryer 7 and then is dried in the sludge dryer 8 by the steam generated by solar thermal energy.

[0092] When there is no wet sludge to be treated in the coal-fired power plant due to various reasons, the system operates in power generation mode, such as Figure 3 The "Solar Thermal Power Generation Operation Ticket" is shown. The main contents of the operation ticket are:

[0093] 1) Close the electric valves UV101 and UV102 by remote operation;

[0094] 2) Close the manual valves HV101, HV301, HV302, HV201, and HV202 on site, and confirm again that the electric valves UV101 and UV102 are closed;

[0095] 3) Open the electric valve UV103 by remote operation;

[0096] 4) Open the manual valves HV102 and HV103 on site. After the above operation ticket is executed, the solar thermal steam source submodule is put into operation, and the system status is as follows: Figure 6 , Figure 6 The black valve means it is closed, and vice versa means it is open. At this time, the steam generated by solar thermal energy is used to drive the small steam turbine 11 generator 12 to generate electricity, and the electric energy is stored in the battery group 13. When there is sludge to be dried, the battery group 13 will supply power to the sludge pre-dryer 7.

[0097] In summary, the embodiments of the present invention have the following beneficial effects:

[0098] (6) By coupling the steam source module of the unit and the solar thermal steam source module, the solar thermal-coal energy combination is realized, and high-temperature steam is synergistically generated for the sludge drying system to dry the sludge, which can improve the energy utilization rate of the sludge drying system.

[0099] (7) When the solar thermal steam drying mode is started and operated, there is no need to use the steam from the auxiliary steam main pipe 1 of the unit. This method has no effect on the thermal system of the unit.

[0100] (8) When the auxiliary steam drying mode of the unit is started and operated, because the sludge pre-dryer 7 pre-dries the sludge, when a certain amount of wet sludge is dried, the auxiliary steam supply of the unit is smaller than when there is no pre-dryer. This method reduces the impact on the thermal system of the unit.

[0101] (9) When the sludge drying system is performing sludge drying operations, there are two steam sources available for drying the sludge. The heat of one steam source comes from coal, and the heat of the other steam source comes from solar energy. The setting of two steam sources greatly increases the availability of the sludge drying system.

[0102] (10) When there is no need to dry the sludge, the steam generated by the photothermal steam generator 22 can be used to drive a small steam turbine generator set to generate electricity. The generated electricity is stored in a group of batteries. When the sludge needs to be dried, the group of batteries 13 supplies power to the sludge pre-dryer 7. This method fully utilizes the output of the photothermal module.

[0103] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A photothermal-coal-fired coupled sludge drying system, characterized in that: At least: The sludge drying device at least comprises a sludge predryer and a sludge dryer; the sludge output end of the sludge predryer is connected to the sludge input end of the sludge dryer through a conveying pipeline; A heat source device, comprising a steam source module for the unit and a photothermal steam source module for converting light energy into fluid thermal energy; the steam output end of the steam source module for the unit and the steam output end of the photothermal steam generator in the photothermal steam source module are respectively connected to the steam input end of the sludge dryer through pipelines; A control device configured to: When it is detected that the outlet steam of the photothermal steam generator meets the preset sludge drying steam condition, the photothermal steam drying mode is started, the steam input end of the sludge dryer is controlled to be connected to the steam output end of the photothermal steam generator, and the sludge dryer is started; When it is detected that the outlet steam of the photothermal steam generator meets the non-preset sludge drying steam condition, the auxiliary steam drying mode of the unit is started, the steam input end of the sludge dryer is controlled to be connected to the steam output end of the steam source module of the unit, and the sludge dryer is started; The photothermal-coal-fired coupled sludge drying system further comprises: A solar thermal power generation device, which includes a steam turbine, a generator, and a battery pack; The steam input end of the steam turbine is connected to the steam output end of the solar thermal steam generator through a pipeline, the output end of the steam turbine is connected to the generator, the power output end of the generator is connected to the battery pack, and the battery pack is connected to the power supply end of the sludge predryer; The control device is further configured to: When operating in a photothermal power generation mode, controlling the steam output end of the photothermal steam generator to be connected to the steam turbine so that the generator generates electricity; The photothermal steam source module comprises: An expansion tank, a heat transfer fluid pump, a solar collector and the photothermal steam generator; The fluid output end of the solar thermal collector is connected to the fluid input end of the photothermal steam generator, the fluid output end of the photothermal steam generator is connected to the fluid input end of the heat transfer fluid pump through the expansion tank, and the fluid output end of the heat transfer fluid pump is connected to the fluid input end of the solar thermal collector; The photothermal-coal-fired coupled sludge drying system further comprises: Unit condenser, steam cooler, and water supply equipment; The heat exchange fluid output end of the sludge dryer is respectively connected to the input end of the unit condenser and the input end of the steam cooler; The output end of the steam cooler and the output end of the water replenishment device are connected to the steam recovery end of the photothermal steam generator through a water pump.

2. The photothermal-coal-fired coupled sludge drying system according to claim 1, characterized in that: The solar thermal steam source module further includes a first electrically controlled valve controlled by the control device; The steam output end of the photothermal steam generator is connected to the steam input end of the sludge dryer through the first electrically controlled valve.

3. The photothermal-coal-fired coupled sludge drying system according to claim 1, characterized in that: The steam source module of the unit includes an auxiliary steam main pipe of the unit and a second electrically controlled valve controlled by the control device; The steam output end of the auxiliary steam main pipe of the unit is connected to the steam input end of the sludge dryer through the second electric control valve.

4. The photothermal-coal-fired coupled sludge drying system according to claim 1, characterized in that: The sludge drying device also includes a wet sludge storage bin; The sludge output end of the wet sludge storage bin is connected to the sludge input end of the sludge predryer through a conveying pipeline.

5. The photothermal-coal-fired coupled sludge drying system according to claim 1, characterized in that: The sludge drying device also includes sewage treatment equipment; The input end of the sewage treatment equipment is connected to the sewage discharge end of the sludge dryer.

6. The photothermal-coal-fired coupled sludge drying system according to claim 1, characterized in that: The sludge drying device also includes a boiler pulverizing system; The dried sludge outlet of the sludge dryer is connected to the boiler pulverizing system through a conveying mechanism.

7. The photothermal-coal-fired coupled sludge drying system according to claim 1, characterized in that: A plurality of manual valves are arranged on the connecting pipeline between the steam source module of the unit and the steam input end of the sludge dryer, and on the connecting pipeline between the photothermal steam source module and the steam input end of the sludge dryer.

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