A device system and method for coupling sludge drying with a coal-fired generator set

Abstract

The present invention provides a device system and method for coupling sludge drying with a coal-fired power generation unit, wherein the device system comprises a sludge drying device, a coal-fired boiler, a heat exchange device, a first economizer, an air preheating device, a second economizer and a desulfurization and dust removal device connected in sequence; the second economizer is cyclically connected to the sludge drying device via a first pipeline; the method utilizes low-quality hot water at the outlet of the second economizer as a heat source for the sludge drying device, thereby realizing cascade utilization of energy, achieving significant energy-saving effects, and maintaining a relatively low temperature level in the sludge drying device, ensuring safe and reliable operation.

Description

Technical Field

[0001] The present invention relates to the technical field of sludge treatment, and in particular to a device system and method for coupling sludge drying of a coal-fired power generation unit. Background Art

[0002] Sludge is a byproduct of sewage treatment plants, and its output is increasing. Contrary to the continuous increase in sludge output, the sludge treatment and disposal capacity is insufficient and the means are backward. Sludge contains pathogenic microorganisms, parasite eggs, toxic and harmful heavy metals and a large number of difficult-to-degrade substances. If sludge is not treated in a standardized manner, it will directly cause secondary pollution to water bodies, soil and atmosphere, posing a serious threat to the ecological environment.

[0003] Traditional sludge treatment methods include landfill, composting, reclamation and incineration. Improper landfill treatment may cause soil and groundwater pollution, and the large-scale occupation of land will further aggravate the tension of land resources; due to the complex composition of sludge and the large amount of harmful substances contained in it, sludge composting has many difficulties in practical application, and sludge reclamation will cause harm to marine life and seriously pollute the marine environment; sludge incineration is the most "thorough" sludge treatment method, which not only has a fast treatment speed, but also has a high degree of reduction, and energy can be recycled. It is a relatively feasible sludge treatment method. On the one hand, using coal-fired power plants to mix sludge can also harmlessly and reduce the amount of urban sludge, while reducing the construction cost of new sludge treatment plants and sludge transportation costs. On the other hand, the calorific value of sludge can also be used for power generation and heating.

[0004] CN112628736A discloses a sludge-coupled coal-fired generator set recycling treatment system, process and application, which sequentially passes domestic sludge and printing and dyeing sludge in industrial solid waste through a wet sludge storage and conveying system, a sludge drying system, a dry sludge conveying system, and a coal mill, and finally puts it into a boiler for combustion. The treatment process of this system can not only save a large amount of landfill land, but also eliminate the threat of secondary pollution of sludge, and realize the reduction and harmlessness of sludge disposal, without the generation of waste gas and wastewater, and generate calorific value to save coal. However, the treatment system directly uses the steam of the boiler system for sludge drying, which will affect the steam production of the unit under full load and full heating conditions, and have a certain impact on the continuous and stable operation of the unit.

[0005] CN108083607A discloses a sludge drying coupled coal-fired power generation system, including: a sludge pre-treatment dehydration unit for preliminary dehydration of wet sludge raw materials; a sludge indirect drying unit for drying the preliminarily dehydrated sludge; a sludge pneumatic conveying and raw coal mixing unit for conveying the dried sludge to the raw coal bin through a closed conveying method for preliminary mixing with raw coal; a coal powder grinding, conveying and combustion unit for preliminary mixing of sludge and raw coal, and sending them to a coal mill for mixing and grinding, so that the two are fully mixed, and then sent to a coal-fired boiler for combustion. However, the sludge drying coupled coal-fired power generation system uses the tail flue gas filtered by coal or the medium and low temperature steam of the coal-fired boiler system to dry and dehydrate the sludge, which will make the operating temperature of the sludge drying system relatively high, and there is a risk of fire.

[0006] CN110748899A discloses a coal-fired coupled sludge drying and incineration system and method considering waste heat utilization, including: a sludge storage and transportation system, a sludge drying system, a sludge incineration system and a waste heat utilization system; the sludge storage and transportation system includes a wet sludge bin; the sludge drying system includes a sludge dryer; the sludge incineration system includes a dry sludge bin and a coal-fired boiler; the sludge dryer is provided with a dryer sludge inlet, a dryer steam inlet, a dryer tail gas outlet and a dry sludge outlet; the sludge outlet of the wet sludge bin is connected to the dryer sludge inlet of the sludge dryer; the sludge dryer is connected to the dry sludge bin through the dry sludge outlet; the outlet of the dry sludge bin is connected to the fuel inlet of the coal-fired boiler; the steam inlet of the dryer is connected to the steam outlet of the coal-fired boiler; the tail gas outlet of the dryer is connected to the waste heat utilization system. However, the system does not treat the tail gas and condensed water of the sludge dryer, which will cause secondary pollution.

[0007] Therefore, there is an urgent need to develop a device system and method for coupling sludge drying of coal-fired power generation units to effectively solve the problem of insufficient steam volume of existing coal-fired power generation units under full load and full heating conditions and the safety and reliability problems in the process of coupling sludge drying of coal-fired power generation units. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a device system and method for coupling sludge drying with a coal-fired generator set. The device does not use the steam of the coal-fired generator set for sludge drying, but instead utilizes the low-quality hot water at the outlet of the second economizer as the heat source of the sludge drying device, thereby maintaining a low temperature level in the sludge drying device and ensuring safe and reliable operation.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a device system for coupling a coal-fired power generation unit with a sludge drying device, the device system comprising a sludge drying device, a coal-fired boiler, a heat exchange device, a first economizer, an air preheating device, a second economizer and a desulfurization and dust removal device connected in sequence; the second economizer is circularly connected to the sludge drying device via a first pipeline.

[0011] In the device system described in the present invention, the second coal-saving device is circularly connected to the sludge drying device via the first pipeline, and the effluent water of the second coal-saving device is used to dry the sludge, thereby realizing the cascade utilization of energy and achieving significant energy-saving effect; compared with the use of flue gas from a coal-fired boiler for sludge drying, the temperature level of the sludge drying device in the device system of the present invention is low, and the operation is safe and reliable; compared with the use of steam from a coal-fired generator set for sludge drying in the prior art, the device system of the present invention will not affect the operation of the coal-fired boiler under full load and full heating conditions, and the coal-fired generator set coupled with the sludge drying device is safe and stable.

[0012] Preferably, the sludge drying device comprises a vacuum dryer.

[0013] Preferably, a water pump is provided on the first pipeline.

[0014] Preferably, the heat exchange device is arranged on the top of the coal-fired boiler.

[0015] Preferably, the device system also includes a steam turbine and a generator.

[0016] Preferably, the heat exchange device, the steam turbine and the first economizer are connected in sequence.

[0017] Preferably, the steam turbine is coaxially connected to the generator.

[0018] Preferably, the steam turbine, the second economizer and the first economizer are connected in sequence.

[0019] Preferably, the device system also includes a gas-solid separation device, a condensation device, a cooling device and a sewage treatment device.

[0020] Preferably, the sludge drying device, gas-solid separation device, condensation device and coal-fired boiler are connected in sequence.

[0021] Preferably, the gas-solid separation device is connected to the coal-fired boiler via a second pipeline.

[0022] The solid particles separated by the gas-solid separation device and the odor generated by the sludge drying device of the present invention enter the coal-fired boiler through the second pipeline for full combustion, and then exchange heat with the flue gas generated by the coal-fired boiler through the heat exchange device, the first economizer, the air preheating device and the second economizer, and finally are treated by the desulfurization and dust removal device to meet the emission standards, without polluting the environment.

[0023] Preferably, the cooling device is cyclically connected to the condensing device.

[0024] Preferably, the condensing device is connected to the sewage treatment device via a condensing water pipe.

[0025] The effluent from the condensing device of the present invention enters a sewage treatment device for treatment, and the treated water that meets the standards is comprehensively utilized on site to achieve zero discharge of wastewater.

[0026] Preferably, the device system also includes a chimney connected to the desulfurization and dust removal device.

[0027] Preferably, the device system further includes a sludge storage device and a sludge conveying device.

[0028] Preferably, the sludge conveying device, the sludge storage device and the sludge drying device are connected in sequence.

[0029] In a second aspect, the present invention provides a method for coupling a coal-fired power generation set with sludge drying, wherein the method is performed using the device system for coupling a coal-fired power generation set with sludge drying described in the first aspect.

[0030] The method of the present invention takes into account that the second economizer in the coal-fired unit is a flue gas deep waste heat utilization device, and the outlet water temperature of the second economizer is 85-95°C, while the inlet water temperature required by the sludge drying device is exactly 85-95°C. After the sludge is dried, the outlet water temperature is reduced to 65-75°C, which can be used as the inlet water of the second economizer for heat exchange with the flue gas. The present invention utilizes the perfect match between the inlet and outlet water temperatures of the sludge drying device and the inlet and outlet water temperatures of the second economizer, thereby achieving perfect coupling between the coal-fired power generation unit and the sludge drying device.

[0031] Preferably, the method comprises the following steps:

[0032] After the wet sludge is treated by the sludge drying device, dried sludge is obtained, and the dried sludge enters the coal-fired boiler for combustion. The generated flue gas is successively heat-exchanged by the heat exchange device, the first economizer, the air preheating device and the second economizer, and then enters the desulfurization and dust removal device for treatment and then discharged; part of the effluent from the second economizer enters the first economizer, and the other part enters the sludge drying device to dry the wet sludge, and the effluent from the sludge drying device returns to the second economizer for circulation.

[0033] The ratio of the effluent of the second economizer to the first economizer and the sludge drying device is not limited in the present invention, and needs to be adjusted according to the actual operation conditions. When the moisture content of the wet sludge is high or the amount of wet sludge is large, the amount of water entering the sludge drying device from the effluent of the second economizer is greater than the amount of water entering the first economizer; when the amount of wet sludge is small in actual operation, the amount of water entering the sludge drying device from the effluent of the second economizer is less than the amount of water entering the first economizer.

[0034] The flue gas of the present invention is discharged through a chimney after being processed in a desulfurization and dust removal device.

[0035] Preferably, the moisture content of the wet sludge is 75% to 85%, for example, it may be 75%, 76%, 78%, 80%, 82%, 84% or 85%.

[0036] The wet sludge of the present invention is transported to the sludge storage device by a closed sludge transport vehicle, and then transported to the sludge drying device by the sludge transport device for drying treatment.

[0037] Preferably, the moisture content of the dried sludge is 35% to 45%, for example, it may be 35%, 37%, 39%, 40%, 42%, 44% or 45%.

[0038] Preferably, the outlet water temperature of the second economizer is 85-95°C, for example, it may be 85°C, 87°C, 89°C, 90°C, 92°C, 93°C or 95°C.

[0039] Preferably, the outlet water temperature of the sludge drying device is 65-75°C, for example, it can be 65°C, 67°C, 69°C, 70°C, 72°C, 73°C or 75°C.

[0040] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0041] As a preferred technical solution of the present invention, the method comprises the following steps:

[0042] Wet sludge with a moisture content of 75% to 85% is treated by a sludge drying device to obtain dried sludge with a moisture content of 35% to 45%. The dried sludge enters a coal-fired boiler for combustion, and the generated flue gas is sequentially heat-exchanged by a heat exchanger, a first economizer, an air preheater and a second economizer, and then enters a desulfurization and dust removal device for treatment and discharge; a part of the effluent from the second economizer with a temperature of 85 to 95°C enters the first economizer, and the other part enters the sludge drying device to dry the wet sludge, and the effluent from the sludge drying device with a temperature of 65 to 75°C returns to the second economizer for circulation; the steam generated by the heat exchanger enters a steam turbine to perform work, driving a generator to generate electricity; the gas generated by the sludge drying device enters a gas-solid separation device for separation, the solid particles discharged from the bottom of the gas-solid separation device enter a coal-fired boiler for combustion, and the gas discharged from the top of the gas-solid separation device enters a condensation device for condensation, and then enters a sewage treatment device for treatment.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] (1) The device system of the coal-fired power generation unit coupled with the sludge drying device provided by the present invention connects the second economizer with the sludge drying device in a circular manner, and uses the effluent of the second economizer to dry the sludge, thereby realizing the cascade utilization of energy and having a significant energy-saving effect. In addition, the temperature level of the sludge drying device is low, below 100°C, and the operation is safe and reliable.

[0045] (2) The device system for coupling the coal-fired power generation unit with the sludge drying device provided by the present invention does not affect the operation of the coal-fired boiler under full load and full heating conditions, and the device for coupling the coal-fired power generation unit with the sludge drying device is safe and stable;

[0046] (3) The method of coupling sludge drying with a coal-fired power generation unit provided by the present invention reduces the energy consumption of the sludge drying device, and the odor generated during the sludge drying process is fully burned in the coal-fired boiler and discharged in compliance with the standards after flue gas treatment, without causing secondary pollution to the environment, and has good economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of a device system for a coal-fired power generation unit coupled with sludge drying provided in a specific embodiment of the present invention.

[0048] In the figure: 1-enclosed sludge transport vehicle; 2-sludge storage bin; 3-plunger pump; 4-sludge dryer; 5-coal-fired boiler; 6-air preheater; 7-second economizer; 8-desulfurization and dust removal device; 9-chimney; 10-steam turbine; 11-generator; 12-water pump; 13-cyclone dust collector; 14-condenser; 15-cooling tower; 16-wastewater treatment device; 17-first economizer; 18-heat exchange device; 19-first pipeline; 20-second pipeline; 21-condensate pipeline. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0050] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0051] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0052] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0053] Those skilled in the art should understand that the present invention necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing a complete process, but the above content does not belong to the main inventive point of the present invention. Those skilled in the art can add layouts on their own based on the process flow and equipment structure selection, and the present invention does not make special requirements and specific limitations on this.

[0054] Example 1

[0055] This embodiment provides a device system for coupling a coal-fired power generation unit with a sludge drying unit, and its schematic diagram is shown in FIG. Figure 1As shown, the device system includes a sludge dryer 4, a coal-fired boiler 5, a heat exchange device 18, a first economizer 17, an air preheater 6, a second economizer 7 and a desulfurization and dust removal device 8 which are connected in sequence; the second economizer 7 is circularly connected to the sludge dryer 4 via a first pipeline 19.

[0056] The first pipeline 19 is provided with a water pump 12; the heat exchange device 18 is provided on the top of the coal-fired boiler 5; the device system further comprises a steam turbine 10 and a generator 11; the heat exchange device 18, the steam turbine 10 and the first economizer 17 are connected in sequence; the steam turbine 10 is coaxially connected with the generator 11. The steam turbine 10, the second economizer 7 and the first economizer 17 are connected in sequence.

[0057] The device system also includes a cyclone dust collector 13, a condenser 14, a cooling tower 15, a closed sludge conveying vehicle 1 and a sewage treatment device 16; the sludge dryer 4, the cyclone dust collector 13, the condenser 14 and the coal-fired boiler 5 are connected in sequence; the cyclone dust collector 13 is connected to the coal-fired boiler 5 via a second pipeline 20. The cooling tower 15 is cyclically connected to the condenser 14; the condenser 14 is connected to the sewage treatment device 16 via a condensed water pipeline 21. The device system also includes a chimney 9 connected to the desulfurization and dust removal device 8, a sludge storage bin 2 and a plunger pump 3 connected to the sludge dryer 4 in sequence; the wet sludge is transported to the sludge storage bin 2 via the closed sludge conveying vehicle 1.

[0058] This embodiment also provides a method for coupling sludge drying with a coal-fired power generation unit, the method being performed using the above-mentioned device system and comprising the following steps:

[0059] The wet sludge with a moisture content of 80% is transported to the sludge storage bin 2 by the closed sludge transport vehicle 1, and then transported to the sludge dryer 4 by the plunger pump 3 for drying treatment to obtain dried sludge with a moisture content of 40%. The dried sludge enters the coal-fired boiler 5 for combustion, and the generated flue gas is successively heat-exchanged by the heat exchange device 18, the first economizer 17, the air preheater 6 and the second economizer 7, and then enters the desulfurization and dust removal device 8 for treatment, and then discharged through the chimney 9; part of the water discharged from the second economizer 7 with a temperature of 90°C enters the first economizer 17, and the other part enters through the first pipeline 19 The sludge dryer 4 dries the wet sludge, and the effluent from the sludge dryer with a temperature of 70°C returns to the second economizer 7 for circulation; the steam generated by the heat exchange device 18 enters the steam turbine 10 to perform work, driving the generator 11 to generate electricity; the gas generated by the sludge dryer 4 enters the cyclone dust collector 13 for separation, and the solid particles discharged from the bottom of the cyclone dust collector 13 enter the coal-fired boiler 5 for combustion through the second pipeline 20, and the gas discharged from the top of the cyclone dust collector 13 enters the condenser 14 for condensation, and then enters the sewage treatment device 16 for treatment through the condensate pipeline 21.

[0060] Example 2

[0061] This embodiment provides a device system for coupling a coal-fired power generation unit with sludge drying, and the device system is the same as that in Embodiment 1.

[0062] This embodiment also provides a method for coupling sludge drying with a coal-fired power generation unit, the method being performed using the above-mentioned device system and comprising the following steps:

[0063] The wet sludge with a moisture content of 75% is transported to the sludge storage bin by a closed sludge transport vehicle, and then transported to the sludge dryer by a plunger pump for drying treatment to obtain dried sludge with a moisture content of 45%. The dried sludge enters the coal-fired boiler for combustion, and the generated flue gas is sequentially heat-exchanged by the heat exchanger, the first economizer, the air preheater and the second economizer, and then enters the desulfurization and dust removal device for treatment and is discharged through the chimney; part of the effluent from the second economizer with a temperature of 85°C enters the first economizer, and the other part enters the sludge dryer through the first pipeline to dry the wet sludge, and the effluent from the sludge dryer with a temperature of 65°C returns to the second economizer for circulation; the steam generated by the heat exchanger enters the steam turbine to work, driving the generator to generate electricity; the gas generated by the sludge dryer enters the cyclone dust collector for separation, the solid particles discharged from the bottom of the cyclone dust collector enter the coal-fired boiler for combustion through the second pipeline, and the gas discharged from the top of the cyclone dust collector enters the condenser for condensation, and then enters the sewage treatment device for treatment through the condensate pipe.

[0064] Example 3

[0065] This embodiment provides a device system for coupling a coal-fired power generation unit with sludge drying, and the device system is the same as that in Embodiment 1.

[0066] This embodiment also provides a method for coupling sludge drying with a coal-fired power generation unit, the method being performed using the above-mentioned device system and comprising the following steps:

[0067] Wet sludge with a moisture content of 85% is transported to a sludge storage bin by a closed sludge transport vehicle, and then transported to a sludge dryer by a plunger pump for drying treatment to obtain dried sludge with a moisture content of 35%. The dried sludge enters a coal-fired boiler for combustion, and the generated flue gas is sequentially heat-exchanged by a heat exchanger, a first economizer, an air preheater and a second economizer, and then enters a desulfurization and dust removal device for treatment and is discharged through a chimney; a portion of the effluent from the second economizer with a temperature of 95°C enters the first economizer, and the other portion enters the sludge dryer through a first pipeline to dry the wet sludge, and the effluent from the sludge dryer with a temperature of 75°C returns to the second economizer for circulation; the steam generated by the heat exchanger enters a steam turbine to work, driving a generator to generate electricity; the gas generated by the sludge dryer enters a cyclone dust collector for separation, the solid particles discharged from the bottom of the cyclone dust collector enter a coal-fired boiler for combustion through a second pipeline, and the gas discharged from the top of the cyclone dust collector enters a condenser for condensation, and then enters a sewage treatment device for treatment through a condensate water pipeline.

[0068] It can be seen from Examples 1 to 3 that the device system and method for coupling sludge drying with a coal-fired power generation unit provided by the present invention uses the effluent from the second economizer as the heat source of the sludge dryer to dry the wet sludge, and the effluent from the sludge dryer returns to the second economizer for circulation, re-absorbs heat and then heats the wet sludge, and the inlet water temperature of the sludge dryer perfectly matches the inlet and outlet water temperature of the second economizer, and there will be no problem of heat waste or the need for additional heat, thereby achieving perfect coupling between the coal-fired power generation unit and the sludge dryer. Moreover, the temperature of the entire set of sludge dryers is within 100°C, and the system operates safely and reliably.

[0069] Comparative Example 1

[0070] This comparative example provides a device system for coupling a coal-fired power generation unit with a sludge drying unit. The device system is the same as Example 1 except that "the second economizer is not connected to the sludge dryer in a circulation manner, and a flue gas bypass pipe is provided to connect the coal-fired boiler and the water supply device, and the water supply device is connected to the sludge drying device via a water supply pipe."

[0071] This comparative example also provides a method for coupling sludge drying with a coal-fired power generation unit, the method being carried out using the above-mentioned device system and comprising the following steps:

[0072] After the wet sludge with a moisture content of 80% is treated by the sludge dryer, the dried sludge with a moisture content of 40% is obtained. The dried sludge enters the coal-fired boiler for combustion. The flue gas generated is successively heat-exchanged by the heat exchanger, the first economizer, the air preheater and the second economizer, and then enters the desulfurization and dust removal device for treatment. A part of the flue gas is heated by the flue gas bypass to heat the feed water, and the heated feed water enters the sludge dryer to dry the wet sludge, and the other part is discharged through the chimney. The outlet water of the second economizer with a temperature of 90°C enters the first economizer, and the steam generated by the heat exchanger enters the steam turbine to work and drive the generator to generate electricity; the gas generated by the sludge dryer enters the gas-solid separation device for separation, and the solid particles discharged from the bottom of the gas-solid separation device enter the coal-fired boiler for combustion. The gas discharged from the top of the gas-solid separation device enters the condensation device for condensation and enters the sewage treatment device for treatment.

[0073] Comparative Example 2

[0074] This comparative example provides a device system for coupling a coal-fired power generation unit with a sludge drying device. The device system is the same as Example 1 except that "the second economizer is not connected to the sludge dryer in a circulation manner, and a heat return water pipe is provided to be connected to the sludge drying device."

[0075] This comparative example also provides a method for coupling sludge drying with a coal-fired power generation unit, and the method is carried out using the above-mentioned device system. The method is the same as Example 1 except that "return water from the heating system is used to enter the sludge dryer to dry the wet sludge".

[0076] It can be seen from comparative examples 1 to 2 that the use of feed water heated by flue gas bypass or return water from the heating system to enter the sludge dryer to dry the wet sludge will cause the temperature of the sludge dryer to be high, posing a risk of fire.

[0077] In summary, the device system and method for coupling a coal-fired power generation unit with sludge drying provided by the present invention utilize the low-quality hot water at the outlet of the second economizer as the heat source of the sludge drying device, thereby realizing cascade utilization of energy and achieving significant energy-saving effects. At the same time, a relatively low temperature level is maintained in the sludge drying device, ensuring safe and reliable operation.

[0078] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A device system for coupling a coal-fired power generation unit with a sludge drying unit, characterized in that: The device system comprises a sludge drying device, a coal-fired boiler, a heat exchange device, a first coal-saving device, an air preheating device, a second coal-saving device and a desulfurization and dust removal device which are connected in sequence; the second coal-saving device is cyclically connected to the sludge drying device via a first pipeline; the heat exchange device is arranged on the top of the coal-fired boiler; the device system also comprises a steam turbine and a generator; the heat exchange device, the steam turbine and the first coal-saving device are connected in sequence; The steam turbine, the second economizer and the first economizer are connected in sequence; The device system also includes a gas-solid separation device, a condensation device, a cooling device and a sewage treatment device; The sludge drying device, gas-solid separation device, condensation device and coal-fired boiler are connected in sequence; The gas-solid separation device is connected to the coal-fired boiler via a second pipeline; The method for coupling sludge drying with a coal-fired power generation unit is carried out using the device system, and the method comprises the following steps: Wet sludge with a moisture content of 75% to 85% is treated by a sludge drying device to obtain dried sludge with a moisture content of 35% to 45%. The dried sludge enters a coal-fired boiler for combustion, and the generated flue gas is sequentially heat-exchanged by a heat exchanger, a first economizer, an air preheater and a second economizer, and then enters a desulfurization and dust removal device for treatment and discharge; part of the effluent from the second economizer with a temperature of 85 to 95°C enters the first economizer, and the other part enters the sludge drying device to dry the wet sludge, and the effluent from the sludge drying device with a temperature of 65 to 75°C returns to the second economizer for circulation; the steam generated by the heat exchanger enters a steam turbine to perform work, driving a generator to generate electricity; the gas generated by the sludge drying device enters a gas-solid separation device for separation, the solid particles discharged from the bottom of the gas-solid separation device enter a coal-fired boiler for combustion, and the gas discharged from the top of the gas-solid separation device enters a condensation device for condensation, and then enters a sewage treatment device for treatment.

2. The device system according to claim 1, characterized in that: The steam turbine is coaxially connected with the generator.

3. The device system according to claim 1, characterized in that: The cooling device is cyclically connected with the condensing device.

4. The device system according to claim 1, characterized in that: The condensing device is connected to the sewage treatment device via a condensing water pipeline.

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