Municipal sludge fire coal coupling power generation system

Abstract

A municipal sludge fire coal coupling power generation system belongs to the field of sludge treatment and mainly comprises a sludge moisture content sensor, a sludge storage bin, a sludge level indicator, a central controller, a fire coal storage bin, a fire coal level indicator, a screw feeder, a reciprocating piston pump, a pipeline pressure sensor, a pumping pipeline, a heating blower, a temperature sensor and a medium-speed coal mill. A peat and coal mixed powder material level meter and a pulverized coal furnace; in the coupling power generation process that municipal sludge and raw coal are mixed and crushed in proportion, calculation and control programs are built in a central controller, and different peat and coal proportions and preheating temperatures are obtained through automatic calculation according to the water content and the heat value of the sludge and the sludge treatment capacity requirement set by a user; and the conveying amount and the preheating temperature of municipal sludge and raw coal are controlled, and it is guaranteed that the peat and coal mixture meets the incineration requirement of a power plant.

Description

Technical Field

[0001] This utility model patent belongs to the field of sludge treatment, specifically relating to a municipal sludge coal-fired power generation system. Background Technology

[0002] Municipal sludge is a concentrated sediment produced during the water treatment process at urban wastewater treatment plants, and is a byproduct of wastewater treatment. Municipal sludge is a flocculent composed of various microorganisms and organic and inorganic particles. It contains large amounts of water, toxic and harmful substances (such as parasite eggs and bacteria), plant nutrients (nitrogen, phosphorus, potassium, etc.), and organic matter (fat, carbohydrates, proteins, etc.), and is prone to decay and odor. If not thoroughly disposed of, it can easily cause secondary pollution to the environment.

[0003] The main characteristics of municipal sewage sludge are high moisture content. After dewatering by centrifuges or filter presses, the moisture content of raw sludge is generally between 60% and 80%. The fixed carbon content in sludge is relatively low, with a lower heating value generally between 560 and 780 kcal / kg, and a maximum of 1000 kcal / kg. The dry heating value is generally around 2500-3000 kcal / kg. The higher the moisture content, the lower the heating value, giving it certain resource recycling value. Traditional treatment methods for municipal sewage sludge mainly involve dewatering and drying followed by incineration. Dewatering is required before incineration, resulting in very high disposal costs. Therefore, treating municipal sewage sludge together with coal for power generation can not only supplement electricity resources but also protect the environment from secondary pollution. However, in current municipal sewage sludge-coal coupled power generation systems, the amount of sludge added significantly affects the combustion effect in the pulverized coal furnace. Currently, it is not possible to automatically adjust the sludge addition amount, nor is it possible to allow users to choose the sludge addition amount while ensuring combustion efficiency. Utility Model Content

[0004] This patent provides a municipal sludge-coal coupled power generation system. In the coupled power generation process of mixing and crushing sludge and raw coal in a certain proportion, the system automatically calculates different sludge-coal ratios and preheating temperatures based on the sludge's moisture content, calorific value, and the user-set sludge treatment volume requirements. It also performs metering control of the amount of raw coal and preheating control to ensure that the sludge-coal mixture meets the requirements for power plant incineration.

[0005] The purpose of this patent is achieved through the following technical solution:

[0006] A municipal sludge-coal coupled power generation system includes a sludge moisture content sensor 1, a sludge storage silo 2, a sludge level gauge 3, a central controller 4, a coal storage silo 5, a coal level gauge 6, a screw feeder 7, a reciprocating piston pump 8, a pipeline pressure sensor 9, a pumping pipeline 10, a heating blower 11, a temperature sensor 12, a medium-speed coal mill 13, a peat-coal mixture level gauge 14, and a pulverized coal furnace 15. The screw feeder 7 is installed below the sludge storage silo 2, and the reciprocating piston pump 8 is installed below the screw feeder 7. The pumping pipeline 10 is connected to the front end of the reciprocating piston pump, and the other end of the pumping pipeline 10 is connected to the medium-speed coal mill 13. The coal storage silo 5 is connected to the medium-speed coal mill 13 via a belt conveyor. The heating blower 11 is connected to the medium-speed coal mill 13 via a pipeline, and the medium-speed coal mill 13 is connected to the pulverized coal furnace 15 via a pipeline. The sludge moisture content sensor 1 is fixedly installed at the bottom of the sludge storage silo 2. The sludge level gauge 3 is fixedly installed inside the sludge storage silo 2. The coal level gauge 6 is fixedly installed in the coal storage silo 5. The pipeline pressure sensor 9 is fixedly installed at the inlet end of the pumping pipeline 10. The temperature sensor 12 is fixedly installed at the bottom of the medium-speed coal mill. The peat-coal mixture level gauge 14 is fixedly installed in the coal mill. The central controller 4 is connected via cables to the temperature sensor 12 in the sludge moisture content sensor 1, the sludge level gauge 3, the screw feeder 7, the reciprocating piston pump 8, the pipeline pressure sensor 9, the heating blower 11, the pulverized coal furnace 15, the medium-speed coal mill 13, the peat-coal mixture level gauge 14, and the coal storage silo 5.

[0007] The sludge storage silo 2 stores municipal sludge, and the coal storage silo 5 stores coal lumps. The screw feeder 7 transports the municipal sludge from the sludge storage silo 2 to the reciprocating piston pump 8, which then pumps the sludge through the pumping pipe 10 to the medium-speed coal mill 13. The medium-speed coal mill 13 grinds the peat mixture into powder and sends it to the pulverized coal furnace for combustion. The heating blower 11 generates heated air and sends it to the medium-speed coal mill 13 to heat the peat mixture within it.

[0008] The municipal sludge coal-fired power generation system incorporates sludge in a weight ratio ranging from 4 wt% to 15 wt%, automatically selecting different sludge incorporation amounts based on varying sludge calorific values, moisture content, and user sludge treatment requirements.

[0009] The central controller 4 has built-in calculation and control programs that can automatically calculate the amount of coal to be transported based on the user's heating demand and control the municipal sludge coal-fired power generation system.

[0010] Furthermore, the central controller 4 has a built-in calculation and control program, the flowchart of which is as follows: Figure 2As shown, the main steps include:

[0011] S1. When the system restarts and starts running, such as Figure 2 As shown, the central controller 4 will initialize, setting the number of cycles (flag) to 0, and initializing the calorific values ​​of sludge and coal to 600 kcal / kg and 7000 kcal / kg, respectively.

[0012] S2. The system requires users to select the city's sludge treatment volume requirements. Users can choose from five options: "highest sludge content", "high sludge content", "medium sludge content", "low sludge content" and "no sludge content".

[0013] S3. Using the moisture content sensor 1 in the sludge storage silo 2 to measure the moisture content of the municipal sludge. (Unit: wt%) is tested, and the sludge dosage is calculated based on the sludge treatment volume requirement input by the user in S2. Actual preheating temperature of peat mixture The calculation formula is:

[0014] When the "maximum sludge content" is

[0015]

[0016]

[0017] When "high sludge content"

[0018]

[0019]

[0020] When "medium sludge content"

[0021]

[0022]

[0023] When "low sludge content"

[0024]

[0025]

[0026] When "no sludge added"

[0027]

[0028]

[0029] in This refers to the calorific value of coal, expressed in kcal / kg. The value is the lower heating value based on sludge, and the unit is kcal / kg; The specific heat capacity of the peat mixture is expressed in kJ / (kg). ℃), the default value is 1 kJ / (kg) ℃); the default preheating temperature for peat mixtures is The unit is ℃, and the default value is 50℃.

[0030] Based on the user's set calorific value requirement and the combustion efficiency in the pulverized coal furnace (Default value is 90%), the calculated conveying capacity of the peat mixture is then obtained. (Unit: kg / s), the formula is:

[0031]

[0032] g represents the user-defined heat demand, expressed in kcal / s.

[0033] S4. Sludge transport volume calculated based on S3 Actual preheating temperature of peat mixture It controls the rotational speed of the screw feeder, the conveying speed of the reciprocating piston pump, and the temperature and air volume of the blower.

[0034] When the density of urban sewage sludge is 1100 kg / m³, the pumping speed of a reciprocating piston pump is... for:

[0035]

[0036] in The unit is m / s. This represents the inner radius of the piston cylinder in a reciprocating piston pump, expressed in meters (m).

[0037] Rotation speed of screw feeder for:

[0038]

[0039] in The unit is RPM. The inner radius of the screw feeder is in meters (m). The pitch is expressed in meters (m).

[0040] The temperature of the pulverized coal mixture ground in the medium-speed coal mill 13 is lower than the actual preheating temperature of the pulverized coal mixture calculated in S3. At this time, the temperature and air volume of the blower are slowly increased, while the temperature of the pulverized coal mixture ground in the medium-speed coal mill 13 is lower than the actual preheating temperature of the pulverized coal mixture calculated in S3. At this time, slowly reduce the temperature and air volume of the blower's output air.

[0041] S5. After S4 is completed, the central controller 4 will detect the levels of sludge, coal, and peat powder respectively using sludge level gauge 3, coal level gauge 6, and peat powder level gauge 14. If any of the three material levels are abnormal, the central controller 4 will issue a prompt and alarm. The system will automatically shut down when the coal level reaches 0. The central controller 4 will also monitor the pumping pressure in the pipeline in real time using pipeline pressure sensor 9. When the pressure exceeds 20 MPa, an alarm will be triggered, and the pumping of municipal sludge will be stopped.

[0042] S6. Two hours after all the tests in S5 are normal, the central controller 4 begins to calculate the calorific value per unit mass of the peat mixture in the pulverized coal furnace over the past hour. The unit is kcal / kg. The number of cycles is calculated as flag = flag + 1, the result is 1, and then stored.

[0043] S7. Determine if there is an average calorific value for the two sludge mix ratios, i.e., whether flag is 2. If this is determined to be "No", the previously calculated sludge content will be reduced by 50%, and the sludge moisture content will be detected using a moisture content detector in the sludge storage silo. .

[0044] S8. Return to S3 and recalculate the sludge delivery volume. Actual preheating temperature of peat mixture Then, execute S4, S5, and S6 in sequence.

[0045] S9. Next, determine if there is an average calorific value for both sludge mix ratios, i.e., whether flag is 2. This will be determined as "yes," yielding the calorific values ​​for the two sludge mix ratios (respectively...). and The calorific value per unit mass of peat mixture in a pulverized coal furnace (respectively) and At this point, the central controller 4 further calculates the correct calorific value of the coal. and the calorific value of sludge The calculation formula is as follows:

[0046]

[0047]

[0048] Correct calorific value of coal and the calorific value of sludge Replace their respective default values ​​and set the loop count flag to 1.

[0049] S10. Based on the correct calorific value of coal in S9. and the calorific value of sludge Then, return to S3 to calculate the corrected coal-sludge ratio, check the sludge moisture content, and recalculate the preheating temperature of the coal-sludge mixture. Finally, start the program to run in a loop.

[0050] Compared with existing technologies, this patent has the following beneficial effects:

[0051] 1) Based on the traditional municipal sludge coal-fired power generation system, this patent adds a variety of detection devices, which can automatically calculate the calorific value of coal and sludge, thereby automatically calculating the preheating temperature of the sludge-coal mixture, and using a heated blower for heating, saving a lot of manpower and material resources, and achieving the effect of automatic control.

[0052] 2) The power generation system provided by this patent allows users to set the current sludge treatment volume and the current calorific value of the pulverized coal furnace. Attached Figure Description

[0053] Figure 1 This is a structural diagram of the municipal sludge coal-fired power generation system of this patent.

[0054] In the diagram: 1-Sludge moisture content sensor, 2-Sludge storage silo, 3-Sludge level gauge, 4-Central controller, 5-Coal storage silo, 6-Coal level gauge, 7-Screw feeder, 8-Reciprocating piston pump, 9-Pipeline pressure sensor, 10-Pumping pipeline, 11-Heating blower, 12-Temperature sensor, 13-Medium-speed coal mill, 14-Peat and coal mixture level gauge, 15-Pulverized coal furnace.

[0055] Figure 2 This is a flowchart of the coal-sludge ratio control program in the municipal sludge-coal coupled power generation system of this patent. Detailed Implementation

[0056] The present patent will be further described in detail below with reference to the accompanying drawings and embodiments.

[0057] Example 1:

[0058] See Figure 1 This embodiment provides a municipal sludge coal-fired power generation system, including the following steps:

[0059] like Figure 1The municipal sludge coal-fired power generation system shown includes a sludge moisture content sensor 1, a sludge storage silo 2, a sludge level gauge 3, a central controller 4, a coal storage silo 5, a coal level gauge 6, a screw feeder 7, a reciprocating piston pump 8, a pipeline pressure sensor 9, a pumping pipeline 10, a heating blower 11, a temperature sensor 12, a medium-speed coal mill 13, a peat and coal mixture level gauge 14, and a pulverized coal furnace 15.

[0060] A screw feeder 7 is installed below the sludge storage silo 2, and a reciprocating piston pump 8 is installed below the screw feeder 7. The front end of the reciprocating piston pump is connected to a pumping pipe 10, and the other end of the pumping pipe 10 is connected to a medium-speed coal mill 13. The coal storage silo 5 is connected to the medium-speed coal mill 13 via a belt conveyor. The heating blower 11 is connected to the medium-speed coal mill 13 via a pipe, and the medium-speed coal mill 13 is connected to a pulverized coal furnace 15 via a pipe. The sludge moisture content sensor 1 is fixedly installed at the bottom of the sludge storage silo 2, the sludge level gauge 3 is fixedly installed inside the sludge storage silo 2, the coal level gauge 6 is fixedly installed in the coal storage silo 5, the pipeline pressure sensor 9 is fixedly installed at the inlet end of the pumping pipeline 10, the temperature sensor 12 is fixedly installed at the bottom end of the medium-speed coal mill, and the peat-coal mixture level gauge 14 is fixedly installed in the coal mill. The central controller 4 is connected via cables to the sludge moisture content sensor 1, the sludge level gauge 3, the screw feeder 7, the reciprocating piston pump 8, the pipeline pressure sensor 9, the heating blower 11, the medium-speed coal mill 13 and its temperature sensor 12 and peat-coal mixture level gauge 14, the coal storage silo 5 and its temperature sensor, and the pulverized coal furnace 15.

[0061] See Figure 1 and Figure 2 This embodiment provides a municipal sludge coal-fired power generation system, including the following steps:

[0062] S1. When the system restarts and starts running, such as Figure 2 As shown, the central controller 4 will initialize, setting the number of cycles (flag) to 0, and initializing the calorific values ​​of sludge and coal to 600 kcal / kg and 7000 kcal / kg, respectively.

[0063] S2. The system requires users to select the city's sludge treatment capacity requirements. Users should select "maximum sludge dosage".

[0064] S3. Using the moisture content sensor 1 in the sludge storage silo 2 to measure the moisture content of the municipal sludge. The test was conducted, and the result was 60 wt%. At this point, based on the user's input sludge treatment requirement in S2 being "maximum sludge dosage," the sludge dosage was calculated. Actual preheating temperature of peat mixture The calculation formulas are respectively

[0065]

[0066]

[0067] in This refers to the calorific value of coal, expressed in kcal / kg. The value is the lower heating value based on sludge, and the unit is kcal / kg; The specific heat capacity of the peat mixture is expressed in kJ / (kg). ℃), the default value is 1 kJ / (kg) ℃); the default preheating temperature for peat mixtures is The unit is ℃, and the default value is 50℃.

[0068] The amount of sludge added can be calculated. Preheating temperature

[0069] Based on the user's set calorific value requirement and the combustion efficiency in the pulverized coal furnace (Default value is 90%), the calculated conveying capacity of the peat mixture is then obtained. (Unit: kg / s), the formula is:

[0070]

[0071] g represents the user-defined heat demand, expressed in kcal / s. The user-defined value is 1.3. 105 kcal / s. The conveying capacity of the peat mixture can be calculated. It is 22.5 kg / s.

[0072] S4. Sludge transport volume calculated based on S3 Actual preheating temperature of peat mixture It controls the rotational speed of the screw feeder, the conveying speed of the reciprocating piston pump, and the temperature and air volume of the blower.

[0073] The density of municipal sludge is 1100 kg / m³. The inner radius of the piston cylinder in the user's reciprocating piston pump... If the pumping speed is 0.15m, then the pumping speed of the reciprocating piston pump is... for:

[0074]

[0075] in The unit is m / s, which can be calculated. .

[0076] For the user's screw feeder inner diameter pitch The rotational speed of the screw feeder The calculation formula is:

[0077]

[0078] The rotational speed of the screw feeder can be calculated. RPM.

[0079] The temperature of the pulverized coal mixture ground in the medium-speed coal mill 13 is lower than the actual preheating temperature of the pulverized coal mixture calculated in S3. At this time, the temperature and air volume of the blower are slowly increased, while the temperature of the pulverized coal mixture ground in the medium-speed coal mill 13 is lower than the actual preheating temperature of the pulverized coal mixture calculated in S3. At this time, slowly reduce the temperature and air volume of the blower's output air.

[0080] S5. After S4 is completed, the central controller 4 will detect the levels of sludge, coal, and peat powder respectively using sludge level gauge 3, coal level gauge 6, and peat powder level gauge 14. If any of the three material levels are abnormal, the central controller 4 will issue a prompt and alarm. The system will automatically shut down when the coal level reaches 0. The central controller 4 will also monitor the pumping pressure in the pipeline in real time using pipeline pressure sensor 9. When the pressure exceeds 20 MPa, an alarm will be triggered, and the pumping of municipal sludge will be stopped.

[0081] S6. After all the tests in S5 have been normal for 2 hours, the central controller 4 begins to calculate the average calorific value of the peat mixture in the pulverized coal furnace over the past hour as 1.2658 kcal. From 105 kcal / s, the calorific value of the peat mixture can be calculated to be 5.63. 103 kcal / kg. Calculate the number of cycles: flag = flag + 1. The result is 1, and this value is stored.

[0082] S7. Determine if there is an average calorific value for the two sludge mix ratios, i.e., whether flag is 2. If this is determined as "No", the previously calculated sludge content will be reduced by 50%, i.e., 0.045 wt%, and the sludge moisture content will be detected using a moisture content detector in the sludge storage silo. The test result was still 60 wt%.

[0083] S8. Return to S3 and recalculate the sludge delivery volume. Actual preheating temperature of peat mixture The steps S4, S5, and S6 were executed sequentially, resulting in a final calorific value of 5.87 for the peat mixture with a sludge content of 0.045 wt%. 103 kcal / kg.

[0084] S9. Next, determine if there is an average calorific value for the two sludge mix proportions, i.e., whether flag is 2. This will be determined as "yes," yielding the unit mass calorific value (5.63 wt%) of the peat mixture in the pulverized coal furnace for the two sludge addition amounts (0.09 wt% and 0.045 wt%, respectively). 103 kcal / kg and 5.87 (103 kcal / kg), at which point the central controller 4 further calculates the correct calorific value of the coal. and the calorific value of sludge The calculation formula is as follows:

[0085]

[0086]

[0087] Calculate the correct calorific value of coal The calorific value of sludge is 6800 kcal / kg. Set the value to 700 kcal / kg, replace the default values, and set the number of cycles (flag) to 1.

[0088] S10. Based on the correct calorific value of coal in S9. and the calorific value of sludge Then, return to S3 to calculate the corrected coal-sludge ratio, check the sludge moisture content, and recalculate the preheating temperature of the coal-sludge mixture. Finally, start the program to run in a loop.

Claims

1. A municipal sludge coal-fired cogeneration system, characterized by, It contains sludge moisture content sensor (1), sludge storage bin (2), sludge level meter (3), central controller (4), coal storage bin (5), coal level meter (6), screw feeder (7), reciprocating piston pump (8), pipeline pressure sensor (9), pumping pipeline (10), heating air blower (11), temperature sensor (12), medium-speed coal mill (13), sludge-coal mixed powder level meter (14), pulverized coal furnace (15); The screw feeder (7) is installed below the sludge storage bin (2), the reciprocating piston pump (8) is installed below the screw feeder (7), the pumping pipeline (10) is communicated in front of the reciprocating piston pump, the other end of the pumping pipeline (10) is communicated with the medium-speed coal mill (13), the coal storage bin (5) is connected to the medium-speed coal mill (13) through a belt conveyor, the heating air blower (11) is communicated with the medium-speed coal mill (13) through a pipeline, the medium-speed coal mill (13) is communicated with the pulverized coal furnace (15) through a pipeline; The sludge moisture content sensor (1) is fixedly installed at the bottom of the sludge storage bin (2), the sludge level meter (3) is fixedly installed in the sludge storage bin (2), the coal level meter (6) is fixedly installed in the coal storage bin (5), the pipeline pressure sensor (9) is fixedly installed at the inlet end of the pumping pipeline (10), the temperature sensor (12) is fixedly installed at the bottom end of the medium-speed coal mill (13), the sludge-coal mixed powder level meter (14) is fixedly installed in the coal mill, and the central controller (4) is connected with the sludge moisture content sensor (1), the sludge level meter (3), the screw feeder (7), the reciprocating piston pump (8), the pipeline pressure sensor (9), the heating air blower (11), the pulverized coal furnace (15), the temperature sensor (12) and the sludge-coal mixed powder level meter (14) in the medium-speed coal mill (13), and the temperature sensor (12) in the coal storage bin (5) through a cable.

Images