System and method for increasing the amount of municipal sludge co-disposed by a cement production line

Abstract

This invention discloses a system and method for increasing the amount of municipal sludge that can be co-processed in cement production lines, including a sludge indirect drying system, a waste gas treatment system, a sludge pre-incineration system, and a co-processing system. Steam from a waste heat boiler enters the sludge indirect drying system to indirectly heat the sludge, resulting in dry sludge. The dry sludge is then fed into the sludge pre-incineration system, where it comes into contact with high-temperature air drawn from a tertiary air duct for pre-incineration. The steam, after heat exchange with the sludge, produces condensate, which is then deoxygenated by a deaerator before being fed back into the waste heat boiler. The dried gas, after condensation and dehydration, is fed into the high-temperature section of a grate cooler. The resulting environmental waste gas is either fed into the high-temperature section of the grate cooler via a waste gas treatment system or deodorized before being discharged. The high-temperature flue gas and ash generated after pre-incineration are fed into a decomposition furnace, or the ash is cooled and fed into a cement raw material batching system or other comprehensive utilization systems. This invention significantly increases the amount of municipal sludge that can be processed while ensuring stable cement kiln system and clinker quality and environmental protection.

Description

Technical Field

[0001] This invention relates to a system and method for co-processing solid waste in a cement production line, and more particularly to a system and method for increasing the amount of municipal sludge co-processed in a cement production line. Background Technology

[0002] Currently, common methods for treating municipal sewage sludge include sanitary landfill, incineration, and composting for agricultural use. However, because sludge contains numerous harmful substances, simple incineration produces pollutants such as dioxins, causing secondary pollution. Co-processing municipal sewage sludge with cement production systems offers advantages such as cleanliness, safety, and sustainability. Furthermore, municipal sewage sludge contains combustible materials and has a certain calorific value (generally, sludge with 50% water content has a low-temperature calorific value of 1500–2000 kcal / kg), making it a viable alternative fuel for cement production systems. The ash residue from sludge incineration has a main chemical composition similar to that of cement, making it suitable as a raw material for cement production. Therefore, co-processing with cement production lines is one of the ideal methods for disposing of municipal sewage sludge.

[0003] However, the amount of municipal sludge co-processed in cement production lines is generally low. Municipal sludge mainly originates from urban wastewater treatment plants and is a byproduct of wastewater treatment. It has a high moisture content (generally 60%–80%) and low calorific value. When treated using conventional methods, the evaporation of water in the wet sludge absorbs a large amount of heat, increasing the amount of flue gas in the cement kiln. This negatively impacts the safe operation and energy conservation of the cement kiln, affecting the stability of the cement firing system and making it difficult to increase the sludge processing capacity. Reducing the moisture content and increasing the calorific value of municipal sludge are key to improving the co-processing capacity and heat substitution rate of cement production lines. Currently, the main method is to use a pre-drying process for the wet sludge, after which it is fed into the decomposition furnace for further processing. At present, a 7000t / d clinker production line using the pre-drying process can process 900t / d of sludge with a 60% moisture content, with a processing capacity of 0.13 tons / ton of clinker. When the amount of pre-dried sludge to be processed is large, how to feed it into the cement production line and minimize its impact on clinker quality is also a problem that needs to be solved. In addition, safety and environmental protection are also basic requirements in the process of municipal sludge disposal.

[0004] Patent CN212581744U discloses a cement kiln co-processing sludge system with a pretreatment device. This system fully utilizes the waste heat of the cement kiln to pre-treat the sludge, achieving cascade utilization of waste heat resources while reducing the impact of co-processed sludge on the cement kiln process and cement quality. However, this process has two problems: First, the exhaust gas discharged after drying has a high moisture content. Without dehumidification, it enters the calcination system through the grate cooler. The water vapor in the calcination system has no positive effect on pulverized coal combustion; instead, the increased temperature of the water vapor increases coal consumption. Simultaneously, the increased gas volume also leads to some exhaust heat loss, reducing the system's thermal efficiency. Second, the hot flue gas discharged after sludge drying contains a large amount of malodorous gases. Since the clinker temperature at the end of the grate cooler cannot remove malodorous gases such as H2S and NH3, the emissions through the kiln tail chimney pose an environmental pollution problem. Furthermore, the dried sludge is directly fed into the decomposition furnace for treatment. On a large scale, this affects the stability of the cement calcination system and the quality of cement clinker, potentially leading to substandard flue gas emissions. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a system for increasing the amount of municipal sludge that can be co-processed in a cement production line while ensuring the stability of the cement kiln system and clinker quality and meeting environmental protection requirements.

[0006] A second objective of this invention is to provide a method for increasing the amount of municipal sludge that can be co-processed in a cement production line using the system described above.

[0007] Technical Solution: The system for increasing the amount of municipal sludge co-processing in cement production lines according to the present invention includes a sludge indirect drying system using steam for indirect sludge drying, a waste gas treatment system, a sludge pre-incineration system, and a co-processing system. The co-processing system includes a deaerator, a waste heat boiler, a grate cooler, a tertiary air duct, and a decomposition furnace on the cement production line. Steam from the waste heat boiler enters the sludge indirect drying system to indirectly heat the sludge to obtain dry sludge. The dry sludge is then sent to the sludge pre-incineration system, where it comes into contact with high-temperature air drawn from the tertiary air duct for pre-incineration. After heat exchange with the sludge, the steam produces condensate, which is then deoxygenated by the deaerator before being sent to the waste heat boiler. The drying gas generated during the sludge drying process is condensed and dehydrated before being sent to the high-temperature section of the grate cooler. The generated environmental waste gas is sent to the high-temperature section of the grate cooler via the waste gas treatment system or deodorized before being discharged. The high-temperature flue gas and ash generated after pre-incineration are sent to the decomposition furnace, or the ash is cooled and sent to the cement raw material batching system or other comprehensive utilization systems.

[0008] The sludge indirect drying system includes a wet sludge silo, a sludge dryer connected to the wet sludge silo and using steam for indirect sludge drying, a dry sludge storage silo for storing the dried sludge produced after drying, a drying gas condenser for condensing and removing water from the drying gas generated by the sludge, and a condensate tank for storing the condensate produced after heat exchange between steam and sludge. The sludge indirect drying system also includes a sludge pretreatment device for crushing and pretreating lumpy sludge.

[0009] The waste gas treatment system includes a waste gas exhaust fan for extracting environmental waste gas, a first air volume regulating valve for controlling the airflow into the high-temperature section of the grate cooler, an emergency deodorization system connected to the waste gas exhaust fan, and a second air volume regulating valve for controlling the airflow into the emergency deodorization system.

[0010] The sludge pre-combustion system includes a dynamic pre-combustion furnace connected to the sludge indirect drying system for pre-combusting dry sludge, and a third air volume regulating valve located between the gas phase inlet of the dynamic pre-combustion furnace and the tertiary air duct for adjusting the air volume entering the dynamic pre-combustion furnace. It also includes a furnace-front silo located between the material inlet of the dynamic pre-combustion furnace and the sludge indirect drying system, a rotary airlock valve located at the outlet of the furnace-front silo, a screw conveyor located between the rotary airlock valve and the material inlet of the dynamic pre-combustion furnace, a counterweight flap valve located at the material outlet of the dynamic pre-combustion furnace, and an ash cooler connected to the counterweight flap valve for cooling the ash produced after combustion. The dynamic pre-combustion furnace adopts a variable-speed rotary kiln structure to control the amount of dry sludge processed and the residence time.

[0011] The deaerator outlet is connected to the waste heat boiler inlet via a feedwater pump. The tertiary air duct is equipped with a tertiary air duct flow regulating valve for adjusting the airflow entering the decomposition furnace and a third air flow regulating valve for adjusting the airflow into the sludge pre-incineration system. Steam generated by the waste heat boiler is sent to the sludge indirect drying system via a steam distributor. A branch pipe connected to the dynamic pre-combustion furnace is provided on the tertiary air duct to send a portion of the high-temperature air from the tertiary air duct into the sludge pre-incineration system. The waste heat boiler includes a kiln head AQC waste heat boiler and a kiln tail SP waste heat boiler.

[0012] The method for increasing the amount of municipal sludge co-processed in cement production lines using the above-described system includes the following steps:

[0013] (A) In the sludge indirect drying system, the wet sludge is indirectly dried using steam generated by the waste heat boiler. The dried sludge is then sent to the sludge pre-incineration system. The steam exchanges heat with the wet sludge to cool down and condenses into condensate, which is then sent to the deaerator. After deaeration, the condensate is sent to the waste heat boiler. The drying gas generated during the drying process is dehydrated by the condenser and then sent to the high-temperature section of the grate cooler for treatment. The environmental waste gas generated during the sludge storage and disposal process enters the waste gas treatment system.

[0014] (B) When the grate cooler stops running, the ambient exhaust gas enters the emergency deodorization system for deodorization and is discharged after meeting the standards; when the grate cooler is running, the ambient exhaust gas enters the high-temperature section of the grate cooler for high-temperature treatment.

[0015] (C) The dry sludge from the indirect sludge drying system and a portion of the high-temperature air from the tertiary air duct enter the sludge pre-incineration system. The high-temperature air is used to pre-treat the dry sludge through incineration. The resulting high-temperature flue gas enters the decomposition furnace, and the ash is cooled and then sent to the cement raw material batching system or other comprehensive utilization systems.

[0016] In step (A), within the sludge indirect drying system, sludge transport vehicles unload high-moisture-content wet sludge into a wet sludge silo. The wet sludge in the silo is then pre-treated by a sludge conveying and pre-treatment system before being sent to the sludge dryer. For sludge with good flowability and a moisture content of approximately 80%, it is pumped into the sludge dryer. For lumpy wet sludge with a moisture content of approximately 60%, a pre-treatment system consisting of a chain conveyor and a crusher is used before the sludge is sent to the sludge dryer. The sludge dryer uses steam to indirectly dry wet sludge. The dried sludge is then conveyed to the dry sludge storage silo by the first dry sludge conveyor. The steam in the sludge dryer exchanges heat with the sludge, cools down, and condenses into condensate, which then enters the condensate tank. The condensate pump sends the condensate to the deaerator. The drying gas generated by the sludge dryer is condensed and dehydrated by the condenser, and then sent to the high-temperature section of the grate cooler for treatment by the drying gas exhaust fan. The condensate generated by the condenser is sent to the sewage treatment facility for treatment or returned to the sewage treatment plant for treatment.

[0017] In step (B), in the waste gas treatment system, the waste gas from the sludge storage workshop and the sludge drying workshop is extracted by the waste gas exhaust fan and sent to the high-temperature section of the grate cooler through the first air volume regulating valve. After exchanging heat with the high-temperature clinker on the grate cooler, the waste gas enters the cement kiln and the decomposition furnace with the secondary and tertiary air of the cement kiln for high-temperature treatment. When the grate cooler stops operating, it is sent to the emergency deodorization system through the second air volume regulating valve for treatment, and then discharged after meeting the standards.

[0018] In step (C), in the sludge pre-incineration system, dry sludge from the dry sludge storage silo is conveyed to the furnace front silo via the second dry sludge conveyor, and then enters the dynamic pre-combustion furnace via the rotary airlock valve and screw conveyor. High-temperature air from the tertiary air duct enters the dynamic pre-combustion furnace via the third air volume regulating valve. The dynamic pre-combustion furnace uses high-temperature air to pre-treat the dry sludge through incineration. The generated flue gas enters the decomposition furnace, and the generated ash enters the ash cooler via the counterweight flap valve for cooling. The cooled ash is then conveyed to the cement raw material batching system or other comprehensive utilization system via a belt conveyor. In the dynamic pre-combustion furnace, the amount of dry sludge processed and the residence time can be controlled by adjusting the rotation speed of the pre-combustion furnace to ensure the pre-treatment effect of the dry sludge. The tertiary air volume entering the dynamic pre-combustion furnace can be controlled by adjusting the air volume regulating valve of the tertiary air duct and the third air volume regulating valve.

[0019] In the co-processing system, steam generated by the AQC waste heat boiler at the kiln head and the SP waste heat boiler at the kiln tail is sent to the sludge dryer via a steam distributor. Excess steam is sent to the turbine for power generation. Condensate from the sludge dryer and turbine, as well as makeup water for the deaerator, is sent to the deaerator. Deoxygenated water from the deaerator is pumped back to the AQC waste heat boiler at the kiln head and the SP waste heat boiler at the kiln tail. High-temperature air generated by the grate cooler is introduced into the decomposition furnace via a tertiary air duct. A branch pipe connecting to the dynamic pre-combustion furnace is also installed on the tertiary air duct. The tertiary air volume entering the dynamic pre-combustion furnace can be controlled by adjusting the tertiary air duct flow regulating valve and the third air volume regulating valve.

[0020] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0021] (1) The municipal sludge is indirectly dried using steam generated by the waste heat boiler of the cement kiln. The dried sludge has a moisture content of 30% to 40% and its volume can be reduced by 60% to 70%, which increases the calorific value of the sludge. The dried sludge can be used as alternative fuel in the cement kiln for co-processing, with little impact on the quality of clinker, which is conducive to improving the fuel substitution rate of the cement kiln. According to thermal calculations and cement batching design, for a 2500t / d clinker production line, this process can process 1700t / d of municipal sludge with a moisture content of 60%. After drying, the sludge has a moisture content of 30%, and the amount of municipal sludge with a moisture content of 60% can be processed to reach 0.68 tons / ton of clinker.

[0022] (2) An indirect sludge dryer is adopted, using steam generated by the waste heat boiler of the cement kiln as the heat source. Steam is readily available, and the modification to the waste heat boiler of the cement kiln is minimal. Because indirect heating with steam is used, the steam does not come into contact with the sludge. After condensation, the steam is recycled back to the waste heat boiler, resulting in high steam utilization. The drying gas generated by sludge drying is mainly water vapor. After condensation and water removal, the gas volume is small, resulting in low energy consumption for high-temperature treatment in the cement production system. After being crushed and agitated by the sludge dryer, the wet sludge becomes uniform granules, which is conducive to further treatment.

[0023] (3) The sludge pre-incineration process is used to pre-treat dry sludge. The generated hot flue gas and combustible gas enter the decomposition furnace, and the generated ash is cooled and sent to the cement raw material batching system or other comprehensive utilization system. This can not only replace the coal used in the decomposition furnace, but also have little impact on the operation of the decomposition furnace and ensure the quality of cement clinker. By adjusting the raw material ratio, the scale of sludge treatment can be greatly increased.

[0024] (4) The waste gas generated during the sludge storage and drying process is sent to the high-temperature section of the grate cooler, where it exchanges heat with the high-temperature clinker and then enters the cement kiln and decomposition furnace for high-temperature treatment with the secondary and tertiary air. The system process is simple and the operating cost is low.

[0025] (5) Using a dynamic pre-combustion furnace with variable speed to treat dry sludge can avoid the problem of incomplete combustion of dry sludge directly into the decomposition furnace, which would affect the stable operation of the cement burning system and the quality of clinker. By adjusting the speed of the pre-combustion furnace, the incineration quality of sludge can be controlled to ensure the treatment effect.

[0026] (6) The flue gas generated by the incineration of dry sludge is sent to the decomposition furnace. The temperature inside the decomposition furnace is as high as 900°C, the residence time is more than 5 seconds, and it is an alkaline environment, which can achieve the complete harmless treatment of the incineration flue gas. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the system structure of the present invention. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings.

[0029] like Figure 1 As shown, the present invention provides a system for increasing the amount of municipal sludge co-processed in cement production lines, including a sludge indirect drying system, a waste gas treatment system, a sludge pre-incineration system, and a co-processing system.

[0030] The sludge indirect drying system includes a wet sludge silo 101 placed in the sludge storage workshop, and a sludge pretreatment device 102, a sludge dryer 103, a first dry sludge conveyor 104, a drying gas condenser 106, a drying gas exhaust fan 107, a condensate tank 108, and a condensate pump 109 placed in the sludge drying workshop; it also includes a dry sludge storage silo 105 placed outside the sludge drying workshop and connected to the first dry sludge conveyor 104. In the sludge indirect drying system, the wet sludge in the wet sludge bin 101 is pre-treated by the sludge pretreatment device 102 and then sent to the sludge dryer 103. The sludge dryer 103 uses steam to indirectly dry the wet sludge. The moisture content of the dried sludge is 30% to 40%. The dried sludge is sent to the dry sludge storage bin 105 by the first dry sludge conveyor 104. The steam is cooled and condensed into condensate, which then enters the condensate tank 108. The condensate pump 109 sends the condensate to the deaerator 401. The drying gas generated by the sludge dryer 103 is condensed and dehydrated by the drying gas condenser 106 and then sent to the high-temperature section of the grate cooler 406 for treatment by the drying gas exhaust fan 107. The condensate generated by the drying gas condenser 106 is sent to the sewage treatment plant for treatment.

[0031] The sludge dryer 103 of this invention can be a disc sludge dryer or a thin-layer sludge dryer, or other indirect drying methods. The sludge pretreatment device 102 employs different equipment and processes depending on the physical state of the wet sludge. For sludge with a moisture content of approximately 80% and good fluidity, it is pumped into the sludge dryer. For lumpy wet sludge with a moisture content of approximately 60%, it is conveyed using a chain conveyor or belt conveyor. A crusher is used for pretreatment, and the crushed sludge is then fed into the sludge dryer 103.

[0032] The waste gas treatment system of the present invention includes a waste gas exhaust fan 201, a first air volume regulating valve 202, a second air volume regulating valve 203, an emergency deodorization system 204, and connecting pipes. The waste gas from the sludge storage workshop and the sludge drying workshop is extracted by the waste gas exhaust fan 201 and sent to the high-temperature section of the grate cooler 406 via the first air volume regulating valve 202. When the grate cooler 406 stops operating, the waste gas is sent to the emergency deodorization system 204 via the second air volume regulating valve 203 for treatment, and then discharged after meeting the standards.

[0033] The sludge pre-incineration system of the present invention includes a second dry sludge conveyor 301, a furnace front silo 302, a rotary airlock valve 303, a screw conveyor 304, a dynamic pre-combustion furnace 305, a counterweight flap valve 306, an ash cooler 307, a belt conveyor 308, and a third air volume regulating valve 309. Dry sludge from the dry sludge storage silo 105 is conveyed to the furnace front silo 302 via the second dry sludge conveyor 301, and then sequentially enters the dynamic pre-combustion furnace via the rotary airlock valve 303 and the screw conveyor 304. High-temperature air from the tertiary air duct 407 enters the dynamic pre-combustion furnace 305 via the third air volume regulating valve 309. The dynamic pre-combustion furnace 305 uses the high-temperature air to pre-treat the dry sludge through incineration. The generated flue gas enters the decomposition furnace 409, and the generated ash enters the ash cooler 307 via the counterweight flap valve 306 for cooling. The cooled ash is then conveyed to the cement raw material batching system via the belt conveyor 308.

[0034] The dynamic pre-combustion furnace 305 of the present invention adopts a rotary kiln structure with variable speed. By adjusting the speed, the amount of dry sludge to be disposed of and the residence time can be controlled to ensure the pre-treatment effect of dry sludge.

[0035] The co-processing system of the present invention includes a deaerator 401, a feed water pump 402, a kiln tail SP waste heat boiler 403, a kiln head AQC waste heat boiler 404, a steam distributor 405, a grate cooler 406, a tertiary air duct 407, a tertiary air duct air volume regulating valve 408, and a decomposition furnace 409. Steam generated by the kiln tail SP waste heat boiler 403 and the kiln head AQC waste heat boiler 404 is sent to the sludge dryer 103 via the steam distributor 405. Excess steam is sent to a steam turbine for power generation. Condensate from the sludge dryer 103 and the steam turbine, as well as deaerator makeup water, are fed into the deaerator 401. Deoxygenated water generated by the deaerator 401 is sent to the kiln tail waste heat boiler 403 and the kiln head waste heat boiler 404 via the feed water pump 402. The high-temperature air generated by the grate cooler 406 is connected to the decomposition furnace 409 through the tertiary air duct 407. At the same time, the tertiary air duct 407 is equipped with a branch pipe that connects to the dynamic pre-combustion furnace 305. The tertiary air volume entering the dynamic pre-combustion furnace 305 can be controlled by adjusting the tertiary air volume regulating valve 408 and the third air volume regulating valve 309.

[0036] The method for increasing the amount of municipal sludge co-processed in cement production lines using the above-described system includes the following steps:

[0037] (S1) In the indirect sludge drying system, a sludge transport vehicle unloads high-moisture-content wet sludge into a wet sludge silo 101. The wet sludge in the wet sludge silo 101 is pre-treated by a sludge pre-treatment device 102 and then sent to a sludge dryer 103. For sludge with good fluidity and a moisture content of about 80%, it is pumped into the sludge dryer 103. For lumpy wet sludge with a moisture content of about 60%, it is conveyed by a chain conveyor or belt conveyor and pre-treated by a crusher. The crushed sludge is then sent to the sludge dryer 103. The sludge dryer 103 indirectly dries wet sludge using steam. The dried sludge is then conveyed to the dry sludge storage silo 105 via the first dry sludge conveyor 104. The steam in the sludge dryer 103 exchanges heat with the sludge to cool down and condense into water, which then enters the condensate tank 108. The condensate pump 109 sends the condensate to the deaerator 401. The drying gas generated by the sludge dryer 103 is condensed and dehydrated by the drying gas condenser 106, and then sent to the high-temperature section of the grate cooler 409 for treatment by the drying gas exhaust fan 107. The condensate generated by the drying gas condenser 106 is sent back to the sewage treatment plant for treatment.

[0038] (S2) In the waste gas treatment system, the waste gas from the sludge storage workshop and the sludge drying workshop is extracted by the waste gas exhaust fan 201 and sent to the high-temperature section of the grate cooler 406 through the first air volume regulating valve 202. After exchanging heat with the high-temperature clinker on the grate cooler, the waste gas enters the cement kiln and the decomposition furnace with the secondary and tertiary air for high-temperature treatment. When the grate cooler 406 stops running, it is sent to the emergency deodorization system 204 through the second air volume regulating valve 203 for treatment and is discharged after meeting the standards. The temperature entering the cement kiln is as high as 1300℃ and the temperature entering the decomposition furnace is as high as 900℃.

[0039] (S3) In the sludge pre-incineration system, dry sludge from the dry sludge storage 105 is sent to the furnace front silo 302 via the second dry sludge conveyor 301, and then enters the dynamic pre-combustion furnace 305 via the rotary airlock valve 303 and the screw conveyor 304. High-temperature air from the tertiary air duct 407 enters the dynamic pre-combustion furnace 305 via the third air volume regulating valve 309. The dynamic pre-combustion furnace 305 uses tertiary air to pre-treat the dry sludge for incineration. The generated flue gas enters the decomposition furnace 409. The generated ash enters the ash cooler 307 via the heavy hammer flap valve 306 for cooling. The cooled ash is sent to the cement raw material batching system via the belt conveyor 308.

[0040] (S4) In the dynamic pre-combustion furnace 305, the amount of dry sludge to be disposed of and the residence time are controlled by adjusting the rotation speed of the dynamic pre-combustion furnace 305 to ensure the pre-treatment effect of the dry sludge; the amount of tertiary air entering the dynamic pre-combustion furnace 305 is controlled by adjusting the tertiary air duct air volume regulating valve 408 and the tertiary air volume regulating valve 309.

[0041] (S5) In the cement production line co-processing system, the steam generated by the kiln tail SP waste heat boiler 403 and the kiln head AQC waste heat boiler 404 is sent to the sludge dryer via the steam distribution cylinder 405. Excess steam is sent to the steam turbine for power generation. The sludge dryer 103, the steam turbine condensate, and the deaerator makeup water are sent to the deaerator 401. The deoxygenated water generated by the deaerator 401 is sent to the kiln tail SP waste heat boiler 403 and the kiln head AQC waste heat boiler 404 via the feed water pump 402. The high-temperature air generated by the grate cooler 406 is connected to the decomposition furnace 409 via the tertiary air duct 407. At the same time, the tertiary air duct 407 is equipped with a branch pipe connected to the dynamic pre-combustion furnace 305. The tertiary air volume entering the dynamic pre-combustion furnace 305 is controlled by adjusting the tertiary air duct air volume regulating valve 408 and the third air volume regulating valve 309.

[0042] In the above steps, to maximize efficiency, the sludge drying process is carried out intermittently. Taking advantage of the peak-valley electricity price difference, during off-peak electricity price periods, the waste heat boiler supplies the maximum amount of steam to the sludge dryer 103, increasing the amount of wet sludge dried and storing a sufficient amount of dry sludge. During peak electricity price periods, the sludge dryer 103 is shut down or only a few units are operated to ensure the continuity of sludge treatment, and the maximum amount of steam is supplied to the waste heat power generation system.

Claims

1. A system for increasing the amount of municipal sludge co-processed in a cement production line, characterized in that it comprises: The system includes an indirect sludge drying system that uses steam to indirectly dry sludge, a waste gas treatment system, a sludge pre-incineration system, and a co-processing system. The co-processing system includes a deaerator (401), a waste heat boiler, a grate cooler (406), a tertiary air duct (407), and a decomposition furnace (409) on the cement production line. Steam from the waste heat boiler enters the indirect sludge drying system to indirectly heat the sludge to obtain dry sludge. The dry sludge is then sent to the sludge pre-incineration system, where it comes into contact with the high-temperature air drawn from the tertiary air duct (407) for pre-incineration. After exchanging heat with the sludge, the steam produces condensate, which is then deoxygenated by the deaerator (401) and sent to the waste heat boiler. The drying gas generated during the sludge drying process is condensed and dehydrated before being sent to the high-temperature section of the grate cooler (406). The generated environmental waste gas is sent to the high-temperature section of the grate cooler or deodorized before being discharged through the waste gas treatment system. The high-temperature flue gas and ash generated after pre-incineration are sent to the decomposition furnace (409), or the ash is sent to the cement raw material batching system or other comprehensive utilization system after cooling. The sludge pre-incineration system includes a dynamic pre-combustion furnace (305) connected to the sludge indirect drying system for pre-incinerating dry sludge, and a third air volume regulating valve (309) located between the gas phase inlet of the dynamic pre-combustion furnace (305) and the tertiary air duct (407) for regulating the air volume entering the dynamic pre-combustion furnace (305); the tertiary air duct (407) is provided with a branch pipe connected to the sludge pre-incineration system for sending high-temperature air from the tertiary air duct into the sludge pre-incineration system; the third air volume regulating valve (309) is located on the branch pipe. The sludge pre-incineration system also includes a heavy hammer flap valve (306) located at the material outlet of the dynamic pre-combustion furnace (305) and an ash cooler (307) connected to the heavy hammer flap valve (306) for cooling the ash produced after combustion. The waste heat boilers include a kiln head AQC waste heat boiler (404) and a kiln tail SP waste heat boiler (403); the steam generated by the kiln tail SP waste heat boiler (403) and the kiln head AQC waste heat boiler (404) is sent to the sludge dryer (103) via a steam distributor (405).

2. The system for increasing the amount of municipal sludge co-processed by a cement production line according to claim 1, characterized in that, The sludge indirect drying system includes a wet sludge silo (101), a sludge dryer (103) connected to the wet sludge silo (101) and using steam to indirectly dry the sludge, a dry sludge storage silo (105) for storing the dried sludge produced after drying, a drying gas condenser (106) for condensing and removing water from the drying gas produced by the sludge, and a condensate tank (108) for storing the condensate produced after the steam exchanges heat with the sludge.

3. The system for increasing the amount of municipal sludge co-processed by a cement production line according to claim 1, characterized in that, The sludge indirect drying system also includes a sludge pretreatment system (102) for crushing and pretreating lumpy sludge.

4. The system for increasing the amount of municipal sludge co-processed by a cement production line according to claim 1, characterized in that, The waste gas treatment system includes a waste gas exhaust fan (201) for extracting environmental waste gas, a first air volume regulating valve (202) for controlling the air volume entering the high-temperature section of the grate cooler (406), an emergency deodorization system (204) connected to the waste gas exhaust fan (201), and a second air volume regulating valve (203) for controlling the air volume entering the emergency deodorization system (204).

5. The system for increasing the amount of municipal sludge co-processed in a cement production line according to claim 1, characterized in that, The sludge pre-incineration system also includes a furnace front silo (302) connected to the dynamic pre-combustion furnace (305), a rotary airlock valve (303) located at the discharge port of the furnace front silo (302), and a screw conveyor (304) located between the rotary airlock valve (303) and the material inlet of the dynamic pre-combustion furnace (305).

6. The system for increasing the amount of municipal sludge co-processed in a cement production line according to claim 1, characterized in that, The dynamic pre-combustion furnace (305) adopts a rotary kiln structure with variable speed to control the amount of dry sludge disposed of and the residence time.

7. The system for increasing the amount of municipal sludge co-processed in a cement production line according to claim 1, characterized in that, The outlet of the deaerator (401) is connected to the inlet of the waste heat boiler via a water pump; a tertiary air duct (407) is provided with a tertiary air duct flow regulating valve (408) for regulating the air volume entering the decomposition furnace (409); the steam generated by the waste heat boiler enters the sludge indirect drying system via a steam distribution cylinder (405).

8. A method for increasing the amount of municipal sludge co-processed in a cement production line using the system described in claim 1, characterized in that, Includes the following steps: (A) In the sludge indirect drying system, the wet sludge is indirectly dried by the steam generated by the waste heat boiler. The dried sludge is sent to the sludge pre-incineration system. The steam exchanges heat with the wet sludge to cool down and condense into condensate, which is then sent to the deaerator (401). After deaeration, it is sent to the waste heat boiler. The drying gas generated during the drying process is condensed and dehydrated before being sent to the high-temperature section of the grate cooler (406) for treatment. The environmental waste gas generated during the sludge storage and disposal process enters the waste gas treatment system. (B) When the grate cooler (406) stops running, the environmental waste gas enters the emergency deodorization system for deodorization and is discharged after meeting the standards; when the grate cooler (406) is running, the environmental waste gas enters the high-temperature section of the grate cooler (406) for high-temperature treatment. (C) The dry sludge from the sludge indirect drying system and part of the high-temperature air from the tertiary air duct (407) enter the sludge pre-incineration system. The high-temperature air is used to pre-treat the dry sludge by incineration. The generated high-temperature flue gas enters the decomposition furnace (409). The ash is cooled and then sent to the cement raw material batching system or other comprehensive utilization system.

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