An alkali industry sludge drying treatment system

Abstract

This utility model discloses a sludge drying system for the alkali industry, including a rotary dryer. The input and output ends of the rotary dryer are rotatably connected to a feeding channel and an output channel via rotary joints, respectively. A feed auger and a discharge auger are rotatably connected to the shafts of the feeding and output channels, respectively. This utility model feeds sludge into the rotary dryer, where it is pulverized and propelled into the dryer by the rotating auger and the waste heat flue gas entering the auger from the tail end of the furnace. The sludge continuously contacts the waste heat flue gas entering the dryer from the tail end, increasing the material's dispersion and surface area per unit volume of wet material. The hot air is in a high-speed turbulent state, quickly achieving gas-solid mixing, ensuring the lumpy material is in a good fluidized state and surrounded by the rotating hot air of the dryer. This rapidly evaporates moisture, reducing the sludge moisture content from 80% to below 20% compared to the original process, while also achieving high treatment efficiency and producing no secondary solid waste.

Description

Technical Field

[0001] This utility model relates to the field of sludge drying and treatment technology, and in particular to a sludge drying and treatment system for the alkali industry. Background Technology

[0002] With increasingly stringent environmental regulations, the moisture content of sludge after mechanical vacuum filtration at wastewater treatment plants (generally around 80%) no longer meets current environmental standards. The acceptable equilibrium moisture content for wastewater treatment plants is determined by a combination of factors, including sludge production volume, sludge treatment speed, and sludge treatment costs. Of the 80% water in sludge, approximately 70% is interstitial water, approximately 20% is capillary water, adsorbed water, and structural water (approximately 10%).

[0003] After sludge thickening at wastewater treatment plants, the sludge moisture content is approximately 95%. Mechanical dewatering removes some interstitial water, theoretically reducing the moisture content to 70%. However, achieving this level requires significant investment, resulting in high treatment costs. Some companies advertise processes that mechanical dewatering can reduce sludge moisture content to below 60%, or even below 50%. However, this is difficult to achieve in practice. Even if the target moisture content is reached, it's often achieved by adding solid materials (such as lime) to the sludge. Since the primary principle of current sludge treatment is volume reduction and pollution minimization, adding any solid materials to the sludge, thus creating secondary solid waste, is strictly prohibited.

[0004] Therefore, it is necessary to develop a sludge drying system for the alkali industry. Utility Model Content

[0005] The technical problem to be solved by this utility model is to address the shortcomings of the prior art by providing a sludge drying system for the alkali industry. This system reduces the original high moisture content of the sludge by adding a sludge drying system and a dust removal system to the original mechanical dewatering process of the sewage treatment plant, thereby solving the technical problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0007] A sludge drying system for the alkali industry includes a rotary dryer. The input end and output end of the rotary dryer are rotatably connected to a feeding channel and an output channel respectively via rotary joints. A feeding auger and a discharging auger are rotatably connected at the shaft center of the feeding channel and the output channel respectively. A furnace head auger motor for driving the feeding auger is fixedly connected to the end of the feeding channel, and a furnace tail auger motor for driving the discharging auger is fixedly connected to the end of the output channel.

[0008] The top of the feeding channel is provided with a feed inlet, and a sludge feeder is provided directly above the feed inlet. A flue pipe is connected to one side of the feed inlet, and a dust removal mechanism is provided at the output end of the flue pipe to further remove dust from the flue gas discharged from the rotary drying oven.

[0009] The bottom of the output channel is provided with a sludge discharge port, and the top of the output channel is provided with a waste heat flue gas inlet. The waste heat flue gas inlet is connected to a flue gas inlet pipe, and the input end of the flue gas inlet pipe is provided with a pretreatment mechanism for the preliminary treatment of the flue gas generated by the boiler.

[0010] Preferably, the rotary drying oven includes a horizontal furnace body with an electric heater installed inside, and the horizontal furnace body is inclined downward at a 3% angle in the axial direction;

[0011] The horizontal furnace body is movably mounted on a roller support base at its bottom, and a drive roller is provided on the outside of the horizontal furnace body. The drive roller is connected to the horizontal furnace body via belt drive.

[0012] Preferably, the dust removal mechanism includes a primary dust collector and a secondary dust collector, wherein the input end of the primary dust collector is connected to the output end of the flue gas pipe, the flue gas output end of the primary dust collector is connected to the input end of the secondary dust collector, and the flue gas output end of the secondary dust collector is connected to an induced draft fan for conveying the purified flue gas to the outside.

[0013] Preferably, the pretreatment mechanism includes a bag filter and a blower. The bag filter is connected to the input end of the blower, the flue gas inlet pipe is connected to the output end of the blower, and the input end of the bag filter is connected to the boiler exhaust port.

[0014] Preferably, the output end of the induced draft fan is connected to the desulfurization and ammonia removal tower via a conveying pipeline, and the conveying pipeline is connected to the boiler exhaust port via a T-junction.

[0015] Preferably, solenoid valves are installed on the conveying pipeline, the boiler exhaust port, and the conveying passage of the desulfurization and deammoniation tower, and a sensing module is installed on the conveying pipeline to detect the flue gas treatment status in the conveying pipeline.

[0016] Preferably, the sensing module includes a temperature sensor and a dust concentration detector. The sensing signal is fed back to a microcontroller serving as the control terminal. The input and output terminals of the microcontroller are electrically connected to an A / D converter and a D / A converter, respectively. The temperature sensor and the dust concentration detector are both electrically connected to the A / D converter, and the solenoid valve is electrically connected to the D / A converter.

[0017] The sludge drying system also includes a belt conveyor. Both the primary and secondary dust collectors are equipped with unloaders at their bottoms, allowing the bottom outlets of the primary and secondary dust collectors to switch between open and closed states. When open, the solid impurities captured by the dust collectors are discharged onto the belt conveyor, which is also used to transport sludge falling from the sludge discharge port.

[0018] This utility model has the following beneficial effects:

[0019] By adding a sludge drying system and a dust removal system to the original mechanical dewatering process of the sewage treatment plant, the original sludge with high moisture content is reduced. The sludge is crushed by a rotating auger and the waste heat flue gas entering the auger from the tail end of the furnace and pushed into the drying furnace. It is in continuous and sufficient contact with the waste heat flue gas entering the drying furnace from the tail end to increase the dispersion of the material and the surface area of ​​the wet material per unit volume. The hot air is in a high-speed turbulent state, which quickly achieves gas-solid mixing, so that the lumpy material is in a good fluidized state and surrounded by the hot air of the rotating drying furnace. The moisture is quickly evaporated, reducing the moisture content of the sludge produced by the original process from 80% to below 20%, and the treatment efficiency is high.

[0020] Temperature sensors and dust concentration detectors are used to sense the temperature and dust concentration of the flue gas in the conveying pipeline. Based on emission requirements and environmental indicators, suitable emission conditions are set. When the detected data is lower than the set parameters, emission requirements are met, and the solenoid valves in the conveying path between the conveying pipeline and the boiler exhaust outlet are closed, while the solenoid valves in the conveying path between the conveying pipeline and the desulfurization and deammoniation tower are open. Conversely, when the detected data is higher than the set parameters, emission requirements are not met, and the solenoid valves in the conveying path between the conveying pipeline and the boiler exhaust outlet are open, while the solenoid valves in the conveying path between the conveying pipeline and the desulfurization and deammoniation tower are closed. The small amounts of hydrogen sulfide, ammonia, and other harmful gases released during sludge drying are completely treated using the original thermal power plant's ammonia absorption desulfurization tower tail gas treatment system before being discharged in compliance with standards. This improves environmental protection effectiveness. Attached Figure Description

[0021] Figure 1 Overall flow chart of the sludge drying treatment system provided by this utility model;

[0022] Figure 2 This is a partial structural diagram of the rotary drying oven in this utility model;

[0023] Figure 3 The flowchart of intelligent control of flue gas flow direction for the sludge drying treatment system provided by this utility model.

[0024] Among them are:

[0025] Rotary drying oven - 1; Feed auger - 2; Furnace head auger motor - 3; Sludge feeder - 4; Feeding channel - 5; Output channel - 6; Discharge auger - 7; Waste heat flue gas inlet - 8; Primary dust collector - 9; Secondary dust collector - 10; Unloader - 11; Exhaust fan - 12; Blower - 13; Belt conveyor - 14; Bag filter - 15; Furnace tail auger motor - 16; Exhaust pipe - 17; Inlet pipe - 18; Desulfurization and deammoniation tower - 19; Boiler exhaust port - 20; Solenoid valve - 21; Temperature sensor - 22; Dust concentration detector - 23; Microcontroller - 24;

[0026] Horizontal furnace body - 101; drive roller - 102; belt - 103. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0028] In the description of this utility model, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this utility model. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the protection scope of this utility model.

[0029] like Figure 1 As shown, an alkali industry sludge drying system includes a rotary dryer 1. The input and output ends of the rotary dryer 1 are rotatably connected to a feeding channel 5 and an output channel 6 via rotary joints, respectively. A feed auger 2 and a discharge auger 7 are rotatably connected at the shaft centers of the feeding channel 5 and output channel 6, respectively. A furnace head auger motor 3 for driving the feed auger 2 is fixedly connected to the end of the feeding channel 5, and a furnace tail auger motor 16 for driving the discharge auger 7 is fixedly connected to the end of the output channel 6. The feeding channel 5... A feed inlet is located at the top, and a sludge feeder 4 is positioned directly above the feed inlet. A flue gas pipe 17 is connected to one side of the feed inlet, and a dust removal mechanism is installed at the output end of the flue gas pipe 17 to further remove dust from the flue gas discharged from the rotary dryer 1. A sludge discharge port is located at the bottom of the output channel 6, and a waste heat flue gas inlet 8 is located at the top of the output channel 6. A flue gas inlet pipe 18 is connected inside the waste heat flue gas inlet 8, and a pretreatment mechanism is installed at the input end of the flue gas inlet pipe 18 for preliminary treatment of the flue gas generated by the boiler. The temperature of the flue gas entering the waste heat flue gas inlet 8 is between 140℃ and 150℃.

[0030] Gas phase process: The waste heat flue gas (140℃-150℃) after dust removal from the power plant is used as the heating medium. It enters the furnace body through the tail end of the drying furnace and comes into full contact with the sludge entering from the head end of the drying furnace. The gas and solid mixture is quickly achieved. Small sludge particles (dust) move upward due to buoyancy greater than gravity. Under the action of the induced draft fan 12, the material passes through the primary dust collector 9 and the secondary dust collector 10 in sequence. The material spirals upward under the entrainment of the gas. Under the action of centrifugal force, the small sludge particles are in the inner ring and the large particles are in the outer ring. When the moisture content reaches the required level, the small particles are carried out by the gas from the center of the drying chamber and sent to the desulfurization and deammoniation tower 19 for further treatment.

[0031] Solid phase process: After mechanical dewatering at the wastewater treatment plant (moisture content is generally around 80%), the sludge is fed into the feeding channel 5 through the sludge feeder 4. Under the conveying of the feeding auger 2, the sludge is fed into the rotary dryer 1 by the rotating auger. During the process, the sludge is further crushed and processed. The crushed sludge is fully fused with the waste heat flue gas entering from the tail of the furnace, which dries it quickly and effectively. Due to the 3% inclination of the furnace body (left lower than right), large sludge particles move continuously towards the tail of the furnace under the action of the rotational force of the dryer. They are discharged from the sludge discharge port through the discharge auger 7. The evaporated water vapor is discharged from the exhaust pipe 17 with the flue gas and further processed.

[0032] like Figure 2 As shown, the rotary dryer 1 includes a horizontal furnace body 101, which is equipped with an electric heater. The horizontal furnace body 101 is inclined downward at a 3% angle in the axial direction, so that large sludge particles entering the horizontal furnace body 101 move from the furnace head to the furnace tail under the action of the rotation force of the rotary dryer 1.

[0033] The horizontal furnace body 101 is movably mounted on a roller support at its bottom, and a drive roller 102 is provided on the outside of the horizontal furnace body 101. The drive roller 102 is connected to the horizontal furnace body 101 by a belt 103.

[0034] Specifically, in the above technical solution, the dust removal mechanism includes a primary dust collector 9 and a secondary dust collector 10. Both the primary and secondary dust collectors have a central chamber and an outer ring chamber. Small sludge particles (dust) move upwards due to buoyancy exceeding gravity. Under the action of the induced draft fan 12, they first enter the primary dust collector 9 and then the secondary dust collector 10. The material spirals upwards under the entrainment of gas. Under centrifugal force, smaller sludge particles are in the inner ring, and larger particles are in the outer ring. They then settle to the bottom under their own gravity, and can be discharged by opening the unloader 11. Small particles, when the moisture content reaches the required level, are processed and carried out by gas from the center of the drying chamber to the desulfurization tower for washing and dust removal. The input end of the primary dust collector 9 is connected to the output end of the flue gas pipe 17, and the flue gas output end of the primary dust collector 9 is connected to the input end of the secondary dust collector 10. The flue gas output end of the secondary dust collector 10 is connected to the induced draft fan 12 for conveying the purified flue gas externally.

[0035] Specifically, in the above technical solution, the pretreatment mechanism includes a bag filter 15 and a blower 13. The bag filter 15 is connected to the input end of the blower 13, the flue gas inlet pipe 18 is connected to the output end of the blower 13, and the input end of the bag filter 15 is docked with the boiler flue gas outlet 20. Through the action of the blower 13, the waste heat flue gas passing through the bag filter 15 is sent to the waste heat flue gas inlet 8 to enter the furnace body and fully contact and mix to reach the gas-solid mixing state.

[0036] Specifically, in the above technical solution, the output end of the induced draft fan 12 is connected to the desulfurization and deammoniation tower 19 through a conveying pipeline. The desulfurization tower dust removal system including the desulfurization and deammoniation tower 19 is the original equipment of the supporting thermal power plant of the soda ash project; it is divided into a concentration section, a circulating absorption section, and a washing section. It mainly uses the process of re-evaporating and concentrating in the concentration section to absorb a large amount of harmful gases such as hydrogen sulfide and ammonia. The solution has a strong acidity with a pH of 2.5. After being treated and meeting the standards, it is discharged through the chimney to form a complete closed circulation process. And after being treated, the temperature of the flue gas entering the desulfurization and deammoniation tower 19 is 75°C - 85°C, and the conveying pipeline is connected to the boiler flue gas outlet 20 through a three-way pipe. Using the filtered mother liquor in the ammonia method desulfurization of the thermal power plant, the recovery and utilization of ammonia (103.2 t / a) are realized, and the ammonia consumption of the combined soda is reduced. The absorption of ammonia by the desulfurization filtered mother liquor increases the pH, enhancing the absorption of flue gas hydrogen sulfide and ammonia in the circulating concentration section, greatly reducing the sulfate aerosol generated when the flue gas enters the desulfurization tower, and reducing the flue gas dust content by about 20%.

[0037] As Figure 3 shown, solenoid valves 21 are provided on the conveying pipelines of the boiler flue gas outlet 20 and the desulfurization and deammoniation tower 19, and a sensing module is provided on the conveying pipeline for detecting the flue gas treatment status in the conveying pipeline. As an embodiment of the sensing module, it includes a temperature sensor 22 and a dust concentration detector 23. The sensing signal is fed back to the single-chip microcomputer 24 as the control end. The input end and the output end of the single-chip microcomputer 24 are electrically connected to an A / D converter and a D / A converter respectively. Among them, the temperature sensor 22 and the dust concentration detector 23 are both electrically connected to the A / D converter, and the solenoid valve 21 is electrically connected to the D / A converter. The temperature sensor 22 and the dust concentration detector 23 respectively sense the temperature and dust concentration information of the flue gas in the conveying pipeline. According to the emission requirements and environmental protection indicators, the appropriate emission conditions of the flue gas are set. When the detected data is lower than the set parameters, it meets the emission requirements, and the solenoid valve 21 on the conveying pipeline connecting the boiler flue gas outlet 20 is closed, while the solenoid valve 21 on the conveying pipeline connecting the desulfurization and deammoniation tower 19 is opened; when the detected data is higher than the set parameters, it does not meet the emission requirements, and the solenoid valve 21 on the conveying pipeline connecting the boiler flue gas outlet 20 is opened, while the solenoid valve 21 on the conveying pipeline connecting the desulfurization and deammoniation tower 19 is closed.

[0038] The sludge drying treatment system also includes a belt conveyor 14, and unloaders 11 are installed at the bottom of the primary dust collector 9 and the secondary dust collector 10, which allows the bottom outlets of the primary dust collector 9 and the secondary dust collector 10 to switch between open and closed states. When open, the solid impurities captured by the dust collector are discharged onto the belt conveyor 14. The belt conveyor 14 is also used to transport the sludge falling from the sludge discharge port, and the treated sludge is directionally transported for recycling.

[0039] In use, this invention utilizes waste heat from power plants as the heat source for drying sludge. After mechanical dewatering at the wastewater treatment plant (with a moisture content generally around 80%), the sludge is fed into the feeding channel 5 via a sludge feeder 4. Driven by the feeding auger 2 and the furnace head auger motor 3, the sludge is pulverized and propelled into the drying furnace by the rotating auger and the waste heat flue gas entering the auger from the tail end of the furnace. It maintains continuous contact with the waste heat flue gas entering the drying furnace from the tail end to increase the dispersion of the material and the surface area per unit volume of wet material. Because the feeding auger pulverizes the material and creates a dispersion effect, while the hot air entering the drying chamber is in a high-speed turbulent state, gas-solid mixing is quickly achieved, placing the lumpy material in a good fluidized state surrounded by the rotating hot air of the drying furnace. During the drying process of mass and heat transfer between the material and the hot air, most of the moisture evaporates in this stage. After the material is crushed and the moisture evaporates, the large sludge particles move towards the tail of the furnace under the rotational force of the drying furnace (the furnace body is lower on the left and higher on the right, with a 3% inclination), and enter the output channel 6. Under the action of the furnace tail auger motor 16 of the discharge auger 7, they fall onto the belt conveyor 14. The small sludge particles (dust) move upward due to buoyancy being greater than gravity. Under the action of the induced draft fan 12, they pass through the primary dust collector 9 and the secondary dust collector 10 in sequence. The material spirals upward under the entrainment of the gas. Under the action of centrifugal force, the small sludge particles are in the inner ring and the large particles are in the outer ring. When the moisture content reaches the required level, the small particles are carried out by the gas from the center of the drying chamber to the desulfurization tower for washing and dust removal. The large particles fall onto the belt conveyor 14. The sludge that passes the test and analysis is transported to the treatment plant for processing. The unqualified sludge is recycled back into the above process until it passes the test, thereby ensuring that the product has uniform moisture content and particle size.

[0040] This application introduces embodiments to verify the rationality of the above solution. Three on-site tests (using this system and the above process) were conducted, with 5.25 tons, 6.5 tons, and 6.8 tons of sludge collected in each test. After treatment with the above solution, the moisture content of the dried sludge was measured to be 13.2%, 15.4%, and 15.6%, respectively. This demonstrates that this application can effectively reduce the moisture content of sludge produced by the mechanical vacuum filtration dewatering process in wastewater treatment plants from 80% to below 20%. It can also reduce the emission index of odorous pollutant ammonia nitrogen; on-site tests showed that the original index of 16 kg / h can be reduced to 3.1 kg / h (at a height of 30 meters).

[0041] This system innovates upon existing equipment and processing technology. Based on the original mechanical dewatering process of sludge in the sewage treatment plant, a new sludge drying system and dust removal system are added to reduce the original sludge with high moisture content. Furthermore, the original ammonia absorption desulfurization tower tail gas treatment system of the thermal power plant is used to completely treat the small amount of harmful gases such as hydrogen sulfide and ammonia released during the sludge drying process before they are discharged in compliance with standards.

[0042] The embodiments of this utility model have been described in detail above with reference to the accompanying drawings, but this utility model is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of this utility model, and these variations still fall within the protection scope of this utility model.

Claims

1. A sludge drying system for the alkali industry, comprising a rotary dryer (1), characterized in that: The input end and output end of the rotary drying oven (1) are rotatably connected to the feeding channel (5) and the output channel (6) respectively via rotary joints. The feeding channel (5) and the output channel (6) are rotatably connected to the axis of the feeding channel (5) and the output channel (6) respectively. The end of the feeding channel (5) is fixedly connected to the furnace head auger motor (3) for driving the feeding auger (2), and the end of the output channel (6) is fixedly connected to the furnace tail auger motor (16) for driving the output auger (7). The top of the feeding channel (5) is provided with a feed inlet, and a sludge feeder (4) is provided directly above the feed inlet. A flue pipe (17) is connected to one side of the feed inlet, and a dust removal mechanism is provided at the output end of the flue pipe (17) for further dust removal of the flue gas discharged from the rotary drying oven (1). The bottom of the output channel (6) is provided with a mud discharge port, and the top of the output channel (6) is provided with a waste heat flue gas inlet (8). The waste heat flue gas inlet (8) is connected to a flue gas inlet pipe (18), and the input end of the flue gas inlet pipe (18) is provided with a pretreatment mechanism for the preliminary treatment of the flue gas generated by the boiler.

2. The sludge drying system for the alkali industry according to claim 1, characterized in that: The rotary drying oven (1) includes a horizontal furnace body (101) with an electric heater installed inside. The horizontal furnace body (101) is inclined downward at a 3% angle in the axial direction. The horizontal furnace body (101) is movably mounted on a roller support at its bottom, and a drive roller (102) is provided on the outside of the horizontal furnace body (101). The drive roller (102) is connected to the horizontal furnace body (101) by a belt (103).

3. The sludge drying system for the alkali industry according to claim 2, characterized in that: The dust removal mechanism includes a primary dust collector (9) and a secondary dust collector (10). The input end of the primary dust collector (9) is connected to the output end of the exhaust pipe (17). The flue gas output end of the primary dust collector (9) is connected to the input end of the secondary dust collector (10). The flue gas output end of the secondary dust collector (10) is connected to an induced draft fan (12) for conveying the purified flue gas to the outside.

4. The sludge drying system for the alkali industry according to claim 3, characterized in that: The pretreatment mechanism includes a bag filter (15) and a blower (13). The bag filter (15) is connected to the input end of the blower (13), the flue gas inlet pipe (18) is connected to the output end of the blower (13), and the input end of the bag filter (15) is connected to the boiler exhaust port (20).

5. The sludge drying system for the alkali industry according to claim 3, characterized in that: The output end of the induced draft fan (12) is connected to the desulfurization and ammonia removal tower (19) through a conveying pipeline, and the conveying pipeline is connected to the boiler exhaust port (20) through a three-way pipe.

6. The sludge drying system for the alkali industry according to claim 5, characterized in that: Solenoid valves (21) are installed on the conveying pipeline and the conveying passage of the boiler exhaust port (20) and the desulfurization and deammoniation tower (19). A sensing module is installed on the conveying pipeline to detect the flue gas treatment status in the conveying pipeline.

7. The sludge drying system for the alkali industry according to claim 6, characterized in that: The sensing module includes a temperature sensor (22) and a dust concentration detector (23). The sensing signal is fed back to a microcontroller (24) which serves as the control terminal. The input and output terminals of the microcontroller (24) are electrically connected to an A / D converter and a D / A converter, respectively. The temperature sensor (22) and the dust concentration detector (23) are both electrically connected to the A / D converter. The solenoid valve (21) is electrically connected to the D / A converter.

8. The sludge drying system for the alkali industry according to claim 3, characterized in that: It also includes a belt conveyor (14), and both the primary dust collector (9) and the secondary dust collector (10) are equipped with unloaders (11) at the bottom, so that the bottom outlets of the primary dust collector (9) and the secondary dust collector (10) can switch between open and closed states. When open, the solid impurities captured by the dust collector are discharged onto the belt conveyor (14), and the belt conveyor (14) is also used for conveying mud material falling from the mud discharge port.

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