A system and method for coupling municipal sludge drying with a cement production line

Abstract

This invention discloses a system and method for coupling municipal sludge drying with a cement production line, including an indirect drying system, a belt drying system, a waste gas treatment system, a pre-combustion system, and a co-processing system. Steam from a waste heat boiler enters the indirect drying system to indirectly heat the wet sludge, resulting in semi-dry sludge. The semi-dry sludge is granulated to obtain granulated sludge, which is then sent to the belt drying system to contact with hot air at the kiln head for further drying to obtain dry sludge. Steam, after heat exchange with the wet sludge, produces condensate, which is sent to the belt drying system for heat exchange and cooling with hot air at the kiln head before entering a deaerator. The drying gas is condensed and dehydrated before being sent to the high-temperature section of a grate cooler. Environmental waste gas is sent to the high-temperature section of the grate cooler or deodorized before being discharged. The dry sludge is sent to the pre-combustion system, where it contacts the high-temperature air from the grate cooler for pre-combustion. The resulting high-temperature flue gas and ash are sent to a decomposition furnace. This invention fully utilizes multiple waste heat sources from the cement production line to maximize the drying of the sludge, increasing its calorific value while avoiding environmental pollution.

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 coupling municipal sludge drying with 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, municipal sludge generally has a high moisture content, typically 60%–80%. Directly sending it to the decomposition furnace in a cement production line would negatively impact the safe operation and energy conservation of the cement kiln, affecting the stability of the cement calcination system and hindering the increase in sludge disposal capacity. Currently, the main technical approach to increasing sludge disposal capacity and reducing the negative impact of high moisture content is to employ a pre-drying process for wet sludge. The dried sludge is then directly fed into the decomposition furnace or fed into the decomposition furnace after passing through a pre-combustion furnace. However, drying wet sludge requires a significant amount of energy; the higher the degree of sludge drying, the greater the energy consumption. Conversely, lower sludge moisture content results in higher calorific value, which is more beneficial for cement production line processing.

[0004] Patent CN201410792166.1 discloses a method for treating sludge in a cement kiln and a sludge gasification cement kiln system. This invention can significantly increase the scale of sludge treatment; it reduces the difference in morphology between solid sludge directly entering the kiln and the fineness of pulverized coal and cement raw materials, thus increasing mass and heat transfer efficiency. However, this scheme has limited sludge precipitation and does not provide a heat source for the indirect sludge dryer or a solution for treating the drying exhaust gas. The entire sludge drying process does not utilize the system characteristics of the cement kiln, requiring additional heat sources and deodorization systems, increasing system investment and operating costs. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a system that fully utilizes various waste heat sources in the cement production line to dry sludge to the maximum extent, improve the calorific value of the sludge, and at the same time avoid environmental pollution by coupling municipal sludge drying with the cement production line.

[0006] A second objective of this invention is to provide a method for coupling municipal sludge drying with a cement production line using the system described above.

[0007] Technical Solution: The system for coupling municipal sludge drying with a cement production line as described in this invention includes an indirect drying system utilizing steam for indirect sludge drying, a belt drying system, a waste gas treatment system, a pre-combustion system, and a co-processing system. The co-processing system includes a waste heat boiler, a deaerator, a grate cooler, a tertiary air duct, and a decomposition furnace on the cement production line. Steam from the waste heat boiler enters the indirect drying system to indirectly heat the wet sludge, resulting in semi-dry sludge. The semi-dry sludge is granulated to obtain granulated sludge, which is then fed into the belt drying system to directly contact the hot air entering the kiln head for further drying. Steam is then... After heat exchange with wet sludge, the condensate produced is sent to the belt drying system. After heat exchange with the kiln head hot air heated by the granulated sludge, the condensate is cooled and then enters the deaerator. After the kiln head hot air is heated, the granulated sludge is dried again to obtain dry sludge. Then, the kiln head hot air is sent to the high-temperature section of the grate cooler by the exhaust fan. The drying gas produced 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 or deodorized before being discharged. The dry sludge is sent to the pre-combustion system, where it comes into contact with the high-temperature air from the grate cooler drawn from the tertiary air duct for pre-combustion. The high-temperature flue gas and ash produced after pre-combustion are sent to the decomposition furnace.

[0008] The belt drying system includes a belt dryer, a circulating fan, and an exhaust fan. Hot flue gas from the kiln head enters the belt dryer to dry the granulated sludge on the conveyor belt. After being extracted by the circulating fan, it is sent back to the belt dryer for further drying, and then discharged by the exhaust fan to a grate cooler for further treatment.

[0009] Furthermore, the belt drying system also includes a condensate heat exchanger; hot flue gas from the kiln head enters the belt dryer from the upper front section to dry the granulated sludge on the conveyor belt. After being extracted by a circulating fan, it is sent to the rear section of the belt dryer, where it exchanges heat with condensate from the indirect drying system in the condensate heat exchanger to further dry the granulated sludge. The condensate is then discharged from the lower rear section of the belt dryer by an exhaust fan and sent to a grate cooler for treatment. The condensate after heat exchange is sent to a waste heat boiler. The belt drying system also includes a dry sludge bin for storing the dried sludge.

[0010] The indirect drying system includes a wet sludge silo, an indirect sludge dryer, a sludge granulator, a condensate tank for storing condensate, and a drying gas condenser for condensing and removing water from the drying gas. The indirect drying system also includes a sludge conveying and pre-treatment system for crushing and pre-treating lumpy sludge. The wet sludge silo is located in the sludge storage workshop, while the sludge conveying and pre-treatment system, the indirect sludge dryer, the sludge granulator, the drying gas condenser, and the condensate tank are all located in the sludge drying workshop.

[0011] The waste gas treatment system includes a waste gas extraction fan for extracting environmental waste gas, a first airflow regulating valve for controlling the airflow entering the high-temperature section of the grate cooler, an emergency deodorization system connected to the waste gas extraction fan, and a second airflow regulating valve for controlling the airflow entering the emergency deodorization system. The environmental waste gas is generated during the sludge storage and disposal process.

[0012] The pre-combustion system includes a pre-combustion furnace connected to a belt drying system for pre-combusting dry sludge, a branch pipe on the tertiary air duct that connects to the pre-combustion furnace, and a fifth air volume regulating valve on the branch pipe for adjusting the air volume entering the pre-combustion furnace. The pre-combustion system also includes a quantitative feeder connected to the pre-combustion furnace.

[0013] The deaerator is connected to the condensate heat exchanger and the waste heat boiler respectively; the tertiary air duct is located between the high-temperature section of the grate cooler and the decomposition furnace; the kiln head exhaust fan draws the hot air from the grate cooler and sends it to the belt dryer through the third air volume regulating valve, and the excess exhaust is regulated by the fourth air volume regulating valve and discharged into the chimney.

[0014] The method for coupling municipal sludge drying with a cement production line using the above system includes the following steps:

[0015] (A) In the indirect drying system, the wet sludge is indirectly dried using steam fed from the waste heat boiler to obtain semi-dry sludge. The indirect drying system granulates the semi-dry sludge to obtain granulated sludge. The steam exchanges heat with the wet sludge to cool it down and produces condensate, which is then sent to the belt drying system. 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 for treatment. 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.

[0016] (B) The granulated sludge is fed into the belt drying system and comes into direct contact with the kiln head hot air entering the belt drying system for further drying. The condensate from step (A) is cooled down by exchanging heat with the kiln head hot air after heating the granulated sludge and then sent to the deaerator. After the kiln head hot air is heated up, the granulated sludge is dried again to obtain dry sludge. Then the kiln head hot air is sent to the high-temperature section of the grate cooler by the exhaust fan.

[0017] (C) When the grate cooler stops running, the ambient waste gas enters the waste gas treatment system for deodorization and is then discharged; when the grate cooler (502) is running, the ambient waste gas enters the high-temperature section of the grate cooler for treatment.

[0018] (D) The dry sludge obtained in step (B) is sent to the pre-combustion system and comes into contact with the high-temperature air from the grate cooler drawn out by the tertiary air duct (508) in the pre-combustion system for pre-combustion. The high-temperature flue gas and ash generated after pre-combustion are sent to the decomposition furnace.

[0019] In step (A), within the indirect drying system, a sludge transport vehicle unloads high-moisture-content wet sludge into a 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 indirect sludge dryer. For sludge with good flowability and a moisture content of approximately 80%, a sludge pump is used to deliver it to the indirect sludge dryer. For lumpy wet sludge with a moisture content of approximately 60%, a pre-treatment device consisting of a chain conveyor and a crusher is used before the pre-treated sludge is sent to the indirect sludge dryer. The sludge indirect drying machine uses steam generated from the cement production line to indirectly dry wet sludge, reducing the moisture content of the wet sludge to about 40%. The sludge with a moisture content of 40% is sent to the sludge granulator by the first sludge conveyor for granulation. The steam in the sludge indirect drying machine exchanges heat with the sludge, cools down, and condenses into water, which then enters the condensate tank. The condensate pump sends the condensate to the belt drying system. The drying gas generated by the sludge indirect drying machine is condensed and dehydrated by the condenser, and then sent to the high-temperature section of the grate cooler by the drying gas exhaust fan for treatment. The condensate generated by the condenser is sent to the sewage treatment plant.

[0020] In step (B), in the belt dryer system, the granulated sludge from the sludge granulator is heated and dried on the conveyor belt of the belt dryer by hot flue gas at a temperature of 80℃~120℃ from the kiln head, further drying it to a moisture content of ≤10%, and then sent to the dry sludge silo; the hot flue gas from the kiln head enters the belt dryer through the upper part of the front section of the belt dryer to dry the granulated sludge on the conveyor belt, and after being extracted by the circulating fan, it is sent to the rear section of the dryer, where it is heated by the condensate heat exchanger to dry the granulated sludge again, and then discharged from the lower part of the rear section by the exhaust fan to the grate cooler in the cement production line for treatment; the condensate is cooled by the condensate heat exchanger and then sent to the deaerator, and the water in the deaerator is sent to the waste heat boiler of the cement production line.

[0021] In step (C), 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 for treatment through the first air volume regulating valve. When the grate cooler stops running, it is sent to the emergency deodorization system in the waste gas treatment system through the second air volume regulating valve for treatment, and then discharged after meeting the standards.

[0022] In step (D), in the pre-combustion system, the second sludge conveyor transports the sludge from the dry sludge silo to the metering feeder, and then sends it into the pre-combustion furnace for pre-combustion incineration. The resulting flue gas and ash are sent to the decomposition furnace for treatment.

[0023] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects: (1) The municipal sludge is dried in two stages using the steam and kiln head hot air generated by the cement production line. This not only utilizes the waste heat of the cement kiln, but also dehydrates and dries the municipal sludge. The moisture content of the dried sludge is ≤10%, and the calorific value of the sludge is greatly improved. The dried sludge can be used as alternative fuel for co-processing in the cement kiln. (2) The sludge indirect drying machine is used as the first stage of the sludge drying process. The indirect drying machine dries the sludge to 40% and uses steam for indirect heating. The steam does not come into contact with the sludge, and the condensate produced can be recycled. At the same time, the amount of waste gas produced is small and the amount of water vapor is large, which is convenient for condensation, collection and disposal. For 80% of the sludge dried to 10%, this stage can remove 86% of the moisture. After the 40% of the sludge is granulated by the sludge granulator, the surface area increases, which is convenient for further drying. At the same time, the high temperature steam can also play a role in high-temperature sterilization of the sludge, which is beneficial to the hygiene and safety of the working environment. (3) Using a belt dryer as the second-stage drying process can further dry the sludge to 10%. The sludge from the first stage is not only at a high temperature, but also has an increased surface area after being processed by the granulator, which is beneficial to the drying operation of the belt dryer. At the same time, the belt dryer uses circulating hot air, which can also utilize the heat of the condensate water with a temperature ≥100℃ in the first stage, thereby improving the heat utilization rate of the steam waste heat. (4) Compared with using only an indirect sludge dryer, this invention uses two-stage drying, which not only realizes the utilization of the kiln head exhaust gas, but also has the advantage of low moisture content after sludge drying. Compared with using only a belt dryer, this invention has the advantages of small overall equipment footprint, good sludge drying effect, small system air volume, small exhaust gas volume, and low energy consumption through the cascade utilization of steam. Overall, it achieves a 1+1>2 effect. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the system structure of the present invention. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings.

[0026] like Figure 1 As shown, the present invention provides a system for coupling municipal sludge drying with a cement production line, including an indirect drying system, a belt drying system, a waste gas treatment system, a pre-combustion system, and a co-processing system.

[0027] The indirect drying system of the present invention includes a wet sludge silo 101 placed in a sludge storage workshop, a sludge conveying and pretreatment system 102 placed in a sludge drying workshop, an indirect sludge dryer 103, a first sludge conveyor 104, a sludge granulator 105, a condensate tank 106, a condensate pump 107, a drying gas condenser 108, and a drying gas exhaust fan 109. In the indirect drying system, the wet sludge in the wet sludge bin 101 is pre-treated by the sludge conveying and pre-treatment system 102 and then sent to the sludge indirect dryer 103. The sludge indirect dryer 103 uses steam generated by the cement production line to indirectly dry the wet sludge. The dried sludge is sent to the sludge granulator 105 by the first sludge conveyor 104 for granulation. The granulated sludge is sent to the belt drying system for further drying. The steam is cooled and condensed into water and enters the condensate tank 106. The condensate pump 107 sends the condensate to the condensate heat exchanger 204 located in the belt drying system. The drying gas generated by the sludge indirect dryer 103 is condensed and dehydrated by the condenser 108 and then sent to the high-temperature section of the grate cooler 502 for treatment by the drying gas exhaust fan 109.

[0028] The sludge indirect drying machine 103 of the present invention can be a disc sludge indirect drying machine or a thin-layer sludge indirect drying machine, etc., which are forms of indirect drying. The sludge conveying and pretreatment system 102 adopts different equipment and processes according to the physical state of the wet sludge. For sludge with good fluidity and a water content of about 80%, it is fed into the sludge indirect drying machine by sludge pumping. For lumpy wet sludge with a water content of about 60%, it is conveyed by a chain conveyor and crushed by a crusher. After pretreatment, it is fed into the sludge indirect drying machine 103.

[0029] The belt drying system of the present invention is also placed in the sludge drying workshop, specifically including a belt dryer 201, a circulating fan 202, an exhaust fan 203, a condensate heat exchanger 204, and a dry sludge bin 205; wherein the exhaust fan 203 and the dry sludge bin 205 are placed outside the sludge drying workshop. Granulated sludge from sludge granulator 105 is heated and dried on the conveyor belt of belt dryer 201 by hot flue gas discharged from kiln head exhaust fan 503 of cement production line. After further drying, it is sent to dry sludge bin 205. Hot flue gas from kiln head enters belt dryer 201 through the upper part of the front section to dry granulated sludge on conveyor belt. After being extracted by circulating fan 202, it is sent to the rear section of belt dryer 201. After being heated by condensate heat exchanger 204, the sludge is dried again. After being discharged from the lower part of the rear section by exhaust fan 203, it is sent to grate cooler 502 in cement production line for treatment. The condensate after heat exchange is sent to deaerator 507.

[0030] The waste gas treatment system of the present invention includes a waste gas exhaust fan 301, a first air volume regulating valve 302, a second air volume regulating valve 303, an emergency deodorization system 304, and connecting pipes. The waste gas from the sludge storage workshop and sludge drying workshop is extracted by the waste gas exhaust fan 301 and sent to the high-temperature section of the grate cooler 502 via the first air volume regulating valve 302. When the grate cooler 502 stops operating, the waste gas is sent to the emergency deodorization system 304 via the second air volume regulating valve 303 for treatment, and then discharged after meeting the emission standards.

[0031] The pre-combustion system of this invention includes a second sludge conveyor 401, a quantitative feeder 402, and a pre-combustion furnace 403. A branch pipe 405 connected to the pre-combustion furnace 403 is provided on the tertiary air duct, and a fifth airflow regulating valve 404 for adjusting the airflow entering the pre-combustion furnace 403 is provided on the branch pipe 405. The second sludge conveyor 401 transports dry sludge from the dry sludge silo to the quantitative feeder 402 for metering, and then feeds it into the pre-combustion furnace 403. High-temperature air from the grate cooler enters the pre-combustion furnace through the branch pipe 405 on the tertiary air duct to pre-combust and burn the dry sludge. The resulting flue gas and ash are sent to a decomposition furnace 501 for treatment. When the amount of ash produced is large, the ash can be sent to a cement raw material batching system or other comprehensive utilization systems.

[0032] The co-processing system includes a waste heat boiler (not shown in the figure), a decomposer 501, a grate cooler 502, a kiln head exhaust fan 503, a third air volume regulating valve 504, a fourth air volume regulating valve 505, a chimney 506, and a deaerator 507. The deaerator is connected to both the condensate heat exchanger and the waste heat boiler. A tertiary air duct 508 is installed between the high-temperature section of the grate cooler 502 and the decomposer 501. The kiln head exhaust fan 503 draws hot air from the grate cooler 502 and sends it to the belt dryer 201 via the third air volume regulating valve 504. Excess exhaust is regulated by the fourth air volume regulating valve 505 and discharged into the chimney 506.

[0033] The process of coupling municipal sludge drying with a cement production line using the above system includes the following steps:

[0034] (S1) In the indirect 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 conveying and pre-treatment system 102 before being sent to the indirect sludge dryer 103. For sludge with good flowability and a moisture content of about 80%, it is pumped into the indirect sludge dryer 103. For lumpy wet sludge with a moisture content of about 60%, it is conveyed by a chain conveyor and crushed by a crusher before being sent to the indirect sludge dryer 103. The sludge indirect drying machine 103 uses steam generated from the cement production line to indirectly dry wet sludge, reducing the moisture content of the wet sludge to about 40%. The sludge with a moisture content of 40% is sent to the sludge granulator 105 via the first sludge conveyor 104 for granulation. The steam in the sludge indirect drying machine 103 exchanges heat with the sludge, cools down, and condenses into water, which then enters the condensate tank 106. The condensate pump 107 sends the condensate to the belt dryer 201. The drying gas generated by the sludge indirect drying machine 103 is condensed and dehydrated by the condenser 108 and then sent to the high-temperature section of the grate cooler 502 for treatment by the drying gas exhaust fan 109. The condensate generated by the condenser 108 is sent to the sewage treatment plant.

[0035] (S2) In the belt drying system, the granulated sludge from the sludge granulator 105 is heated and dried on the conveyor belt of the belt dryer 201 by hot flue gas at a temperature of 80℃~120℃ from the kiln head, and further dried to a moisture content of ≤10%, and then sent to the dry sludge bin 205; the hot flue gas from the kiln head enters the belt dryer 201 through the upper part of the front section of the belt dryer 201 to dry the granulated sludge on the conveyor belt, and is then extracted by the circulating fan 202 and sent to the rear section of the belt dryer 201, where it is heated by the condensate heat exchanger 204 to dry the sludge again, and is then discharged from the lower part of the rear section by the exhaust fan 203 and sent to the grate cooler 502 in the cement production line for treatment; the condensate is cooled by the condensate heat exchanger 204 and sent to the deaerator 507, and the water in the deaerator 507 is sent to the waste heat boiler of the cement production line.

[0036] (S3) 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 301 and sent to the high-temperature section of the grate cooler 502 for treatment via the first air volume regulating valve 302. When the grate cooler 502 stops running, it is sent to the emergency deodorization system 304 for treatment via the second air volume regulating valve 303, and discharged after meeting the standards.

[0037] (S4) In the pre-combustion system, the second sludge conveyor 401 transports the sludge from the dry sludge silo 205 to the metering feeder 402 for metering, and then feeds it into the pre-combustion furnace 403 for pre-combustion. The air volume of the high-temperature section of the grate cooler 502 entering the pre-combustion furnace 403 is adjusted by the fifth air volume regulating valve 404. The generated flue gas and ash are sent to the decomposition furnace 501 for treatment. When the amount of ash generated is large, the ash is sent to the cement raw material batching system or other comprehensive utilization systems.

Claims

1. A system for coupling municipal sludge drying with a cement production line, characterized in that, The system includes an indirect drying system utilizing steam for indirect sludge drying, a belt drying system, a waste gas treatment system, a pre-combustion system, and a co-processing system. The co-processing system includes a waste heat boiler, a deaerator (507), a grate cooler (502), a tertiary air duct (508), and a decomposition furnace (501) on the cement production line. Steam from the waste heat boiler enters the indirect drying system to indirectly heat the wet sludge, resulting in semi-dry sludge. The semi-dry sludge is granulated to obtain granulated sludge, which is then fed into the belt drying system to directly contact the kiln head hot air for further drying. Steam, after heat exchange with the wet sludge, generates condensate, which is then fed into the belt drying system to further dry the granulated sludge. After the kiln head hot air is heated and cooled, it enters the deaerator (507). After the kiln head hot air is heated, it dries the granulated sludge again to obtain dry sludge. Then, the kiln head hot air is sent to the high-temperature section of the grate cooler (502) by the exhaust fan (203). The drying gas generated during the sludge drying process is sent to the high-temperature section of the grate cooler (502) after being condensed and dehydrated. The generated environmental waste gas is sent to the high-temperature section of the grate cooler (502) through the waste gas treatment system or discharged after deodorization. The dry sludge is sent to the pre-combustion system and comes into contact with the high-temperature air from the grate cooler (502) drawn from the tertiary air duct (508) for pre-combustion. The high-temperature flue gas and ash generated after pre-combustion are sent to the decomposition furnace (501). The belt drying system includes a belt dryer (201), a circulating fan (202), and an exhaust fan (203). Hot flue gas from the kiln head enters the belt dryer (201) to dry the granulated sludge on the conveyor belt. After being extracted by the circulating fan (202), it is sent back to the belt dryer (201) for further drying, and then discharged by the exhaust fan (203) to a grate cooler (502) for further treatment. The belt drying system also includes a condensate heat exchanger (204). The hot flue gas from the kiln head enters the belt dryer (201) from the upper part of the front section to dry the granulated sludge on the conveyor belt. After being drawn out by the circulating fan (202), it is sent to the rear section of the belt dryer (201). After being heated by the condensate heat exchanger (204), the sludge is dried again. After being discharged from the lower part of the rear section of the belt dryer (201) by the exhaust fan (203), it is sent to the grate cooler (502) for treatment. The condensate after heat exchange is sent to the deaerator (507).

2. The system for coupling municipal sludge drying with a cement production line according to claim 1, characterized in that, The indirect drying system includes a wet sludge silo (101), an indirect sludge dryer (103), a sludge granulator (105), a condensate tank (106) for storing condensate, and a drying gas condenser (108) for condensing and removing water from the drying gas.

3. The system for coupling municipal sludge drying with a cement production line according to claim 1, characterized in that, The indirect drying system also includes a sludge conveying and pretreatment system (102) for crushing and pretreating lumpy sludge.

4. The system for coupling municipal sludge drying with a cement production line according to claim 1, characterized in that, The waste gas treatment system includes a waste gas exhaust fan (301) for extracting environmental waste gas, a first air volume regulating valve (302) for controlling the air volume entering the high-temperature section of the grate cooler (502), an emergency deodorization system (304) connected to the waste gas exhaust fan (301), and a second air volume regulating valve (303) for controlling the air volume entering the emergency deodorization system (304).

5. The system for coupling municipal sludge drying with a cement production line according to claim 1, characterized in that, The pre-combustion system includes a pre-combustion furnace (403) connected to a belt drying system for pre-combustion of dry sludge. A branch pipe (405) connected to the pre-combustion furnace (403) is provided on the tertiary air duct (508). A fifth air volume regulating valve (404) is provided on the branch pipe (405) for regulating the air volume entering the pre-combustion furnace (403).

6. The system for coupling municipal sludge drying with a cement production line according to claim 5, characterized in that, The pre-combustion system also includes a quantitative feeder (402) connected to the pre-combustion furnace (403).

7. The system for coupling municipal sludge drying with a cement production line according to claim 1, characterized in that, The kiln head exhaust fan (503) draws out the hot air from the grate cooler (502) and sends it into the belt dryer (201) through the third air volume regulating valve (504). Excess exhaust is regulated by the fourth air volume regulating valve (505) and discharged into the chimney (506).

8. A method for coupling municipal sludge drying with a cement production line using the system described in claim 1, characterized in that, Includes the following steps: (A) In the indirect drying system, the wet sludge is indirectly dried by the steam fed into the waste heat boiler to obtain semi-dry sludge. The indirect drying system granulates the semi-dry sludge to obtain granulated sludge. The steam exchanges heat with the wet sludge to cool down and generate condensate, which is then sent to the belt drying system. 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 (502) for treatment. The generated environmental waste gas is sent to the high-temperature section of the grate cooler (502) or deodorized before being discharged through the waste gas treatment system. (B) The granulated sludge is fed into the belt drying system and comes into direct contact with the kiln head hot air entering the belt drying system for further drying. The condensate from step (A) is cooled down by exchanging heat with the kiln head hot air after heating the granulated sludge and then sent to the deaerator (507). After the kiln head hot air is heated up, the granulated sludge is dried again to obtain dry sludge. Then the kiln head hot air is sent to the high temperature section of the grate cooler (502) by the exhaust fan (203). (C) When the grate cooler (502) stops running, the ambient waste gas enters the waste gas treatment system for deodorization and is then discharged; when the grate cooler (502) is running, the ambient waste gas enters the high-temperature section of the grate cooler (502) for treatment. (D) The dry sludge obtained in step (B) is sent to the pre-combustion system and comes into contact with the high-temperature air from the grate cooler (502) drawn from the tertiary air duct (508) for pre-combustion. The high-temperature flue gas and ash generated after pre-combustion are sent to the decomposition furnace (501).

Images