Medical waste sludge direct combustion system

Abstract

The invention relates to the technical field of medical waste sludge treatment, and discloses a medical waste sludge direct combustion system which is characterized in that a medical waste sludge blending combustion line is additionally arranged on a secondary combustion chamber of a medical waste incineration line, sludge slurry is sprayed to the secondary combustion chamber through the medical waste sludge blending combustion line, and the temperature of the secondary combustion chamber is regulated and controlled by utilizing moisture in the sludge slurry; and therefore, the air supply amount of the secondary combustion chamber is reduced, and emission of nitric oxide in tail gas of a medical waste incineration line is reduced. Due to the fact that the sludge slurry contains a large amount of water, after the sludge slurry is sprayed into the secondary combustion chamber of the medical waste incineration line, the temperature of the secondary combustion chamber of the medical waste incineration line is regulated and controlled through the water in the sludge, the air supply amount of the secondary combustion chamber of the medical waste incineration line can be reduced, and emission of nitric oxide (Nox) of the medical waste incineration line is reduced. And the secondary combustion chamber of the medical waste incineration line is a high-temperature environment, and the indoor temperature is more than 1000 DEG C, so that the sludge slurry is sprayed into the secondary combustion chamber of the medical waste incineration line for blending combustion, and the incineration is more thorough.

Description

Technical Field

[0001] This invention relates to the field of medical waste sludge treatment technology, specifically to a direct combustion system for medical waste sludge that can directly inject medical waste sludge into the secondary combustion chamber of a medical waste incineration line for combustion and reduce NOx emissions from the medical waste incineration line. Background Technology

[0002] In existing technologies, sludge treatment mainly involves two methods: drying-forming-incineration and synthetic sludge slurry atomization combustion. For example, Chinese invention patent application CN110030561A discloses a sludge incineration treatment method, which reveals two sludge incineration methods: sludge slurry co-firing incineration and synthetic sludge slurry atomization combustion. Relatively speaking, the sludge slurry co-firing incineration method requires drying and transportation, thus involving complex processes, the generation of volatile organic compounds (VOCs) pollution during disposal, additional investment in environmental protection equipment, and the need for more personnel. Although the synthetic sludge slurry atomization combustion method can achieve sludge preparation before the furnace, saving the processes of off-site slurry preparation and storage, reducing costs and improving efficiency, and the process is environmentally friendly with no wastewater discharge, no odor emission, and zero emissions during production; however, because the sludge has a low calorific value, it needs to be mixed with raw coal to form a coal-water slurry before subsequent combustion.

[0003] In addition, although there are some existing technologies for sludge co-firing, such as the Chinese utility model patent with publication number CN214198691U, the addition of sludge to the original combustion process will more or less affect the original combustion process, and may even lead to the flue gas failing to meet standards. Summary of the Invention

[0004] The purpose of this invention is to provide a direct combustion system for medical waste sludge that can directly inject medical waste sludge into the secondary combustion chamber of a medical waste incineration line for combustion and reduce NOx emissions from the medical waste incineration line. This system aims to provide at least one beneficial option or create conditions to solve one or more technical problems existing in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A direct combustion system for medical waste sludge, the basic concept of which is as follows: A medical waste sludge co-firing line is added to the secondary combustion chamber of a medical waste incineration line. The co-firing line includes a wet ball mill for receiving the medical waste sludge to be incinerated and grinding it into a finer consistency; a mixing tank connected to the output of the wet ball mill for receiving the ground medical waste sludge and adding additives and water to it to form a sludge slurry, thereby improving the dispersibility and reducing the viscosity of the sludge particles, giving it appropriate fluidity; a storage tank connected to the output of the mixing tank for storing the prepared sludge slurry; an electrically heated conveying pipeline connected to the output of the storage tank for conveying the prepared sludge slurry under heat to a sludge atomizing spraying device; and a sludge atomizing spraying device connected to the secondary combustion chamber of the medical waste incineration line for spraying atomized medical waste sludge into the secondary combustion chamber.

[0007] During grinding and refining, the particles of medical waste sludge are refined to 80-200 mesh. In this invention, the particle size of medical waste sludge needs to be strictly controlled; excessively coarse particles will lead to increased viscosity and poor fluidity of the sludge slurry, while excessively fine particles will lead to agglomeration; thus affecting the atomization and spraying effect of the medical waste sludge.

[0008] When additives and water are added to prepare sludge slurry, the additives are one or more of naphthalene sulfonates, lignin sulfonates, or polycarboxylic acid polymers. The total amount of additives added is 0.5%-1% of the total mass of the sludge slurry; the amount of water added is 80%-90% of the total mass of the sludge slurry. By adding additives and water to prepare sludge slurry, the additives will be adsorbed on the surface of the sludge powder, forming electrostatic repulsion or steric hindrance, preventing the agglomeration of medical waste sludge particles, and reducing the slurry viscosity from tens of thousands of mPa·s to 1000-2000 mPa·s. Furthermore, since the sludge slurry contains a large amount of water, when the sludge slurry is sprayed into the secondary combustion chamber of the medical waste incineration line, the temperature of the secondary combustion chamber can be controlled by the water content in the sludge, which can reduce the air supply to the secondary combustion chamber and reduce nitrogen oxide (NOx) emissions from the medical waste incineration line. Furthermore, since the secondary combustion chamber of the medical waste incineration line is a high-temperature environment with an indoor temperature of over 1000℃, spraying sludge into the secondary combustion chamber of the medical waste incineration line for co-combustion results in more thorough incineration.

[0009] In this invention, qualified sludge slurry refers to sludge slurry that meets the standards for both particle size and viscosity. The particle size is 80-200 mesh, and the viscosity is 1000-2000 mPa·s. To ensure that the sludge slurry in the storage tank meets the standards, this invention also includes a stirrer and a rotational viscometer on the storage tank. The rotational viscometer is used to monitor the viscosity of the sludge slurry in the storage tank online. The operation of the stirrer is controlled according to the monitored viscosity of the sludge slurry to maintain the viscosity of the sludge slurry in the storage tank within the range of 1000-2000 mPa·s (at 25°C). Ultimately, it must meet the requirements of fluidity, stability (72-hour settling layer thickness < 5%), and uniformity (sampling ash content deviation < 1%). This avoids the problems of high conveying resistance and atomization difficulties caused by excessively high viscosity.

[0010] In this invention, the agitator continuously stirs the sludge slurry in the storage tank at a low speed. This ensures that the viscosity of the sludge slurry is within the controllable range and prevents stratification. It also avoids sudden, excessive stirring that could cause air bubbles to be mixed in and affect atomization.

[0011] In this invention, a coarse filter is installed on the connecting pipe between the wet ball mill and the preparation tank to filter out any large particles of sludge; a fine filter is installed at the outlet end of the preparation tank. By setting up coarse and fine filters to filter medical waste sludge and sludge slurry, the risk of clogging caused by large particles is effectively avoided, ensuring the atomization effect.

[0012] In this invention, the coarse filter has a mesh size of 0.5 mm, and the fine filter has a mesh size of 0.3 mm; both the coarse filter and the fine filter are Y-type filters to facilitate the discharge of filter screen residue.

[0013] In this invention, qualified sludge slurry is transported under pressure and heat to a sludge atomizing injection device, ensuring that the sludge slurry in the storage tank is delivered to the device at a stable pressure and flow rate (fluctuation <5%). The delivery pressure is provided by a screw pump, which continuously pushes the sludge slurry by relying on the volume change and movement of the meshing space formed by the pump body and the screw. The delivery pressure can reach 1.0-2.5 MPa, and the flow rate adjustment range is wide.

[0014] In this invention, the electric heat tracing conveying pipeline is made of seamless steel pipe, preferably 20# carbon steel seamless steel pipe, with an inner diameter between DN50 and DN150, determined according to the flow rate, and the flow velocity is controlled at 1.5-2.5 m / s; too low a flow velocity will easily cause sedimentation, while too high a flow velocity will wear down the pipeline. The conveying pipeline is laid at an incline with a slope of 3‰-5‰ to facilitate the installation of a drain valve at the lowest point for periodic slag removal.

[0015] In this invention, the electrically heated conveying pipeline maintains the temperature of the sludge slurry between 15-30℃. Too low a temperature will cause the viscosity to increase, affecting the atomization and combustion load matching of the sludge slurry. To ensure the accuracy of atomization and combustion load matching, a flow control unit is also installed on the electrically heated conveying pipeline. The flow control unit monitors the flow rate in real time through an electromagnetic flow meter, and the PLC control system adjusts the speed of the variable frequency motor of the screw pump to match the sludge slurry flow rate with the combustion load of the medical waste incineration line. Simultaneously, a pressure stabilizing valve is also installed on the electrically heated conveying pipeline to ensure stable slurry pressure entering the sludge atomization and injection device, with pressure fluctuations <3%.

[0016] In this invention, the matching relationship between the sludge slurry flow rate and the incineration load of the medical waste incineration line is determined through experiments.

[0017] Some other beneficial effects of the present invention will become more apparent in the following description or will be learned in practice. Attached Figure Description

[0018] Figure 1 The diagram shown is a structural schematic of the direct combustion system for medical waste sludge provided in an embodiment of the present invention.

[0019] Explanation of the reference numerals in the attached figures.

[0020] 1: Wet ball mill; 2: Preparation tank; 3: Slurry storage tank; 4: Electricly heated conveying pipeline; 5: Sludge atomizing injection device; 6: Secondary combustion chamber of medical waste incineration line; 7: Agitator; 8: Rotary viscometer; 9: Coarse filter; 10: Fine filter; 11: Screw pump; 12: Flow control unit; 13: Pressure regulating valve. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] Example.

[0023] A direct combustion system for medical waste sludge includes: a wet ball mill 1 for receiving medical waste sludge to be incinerated and grinding and refining it; a preparation tank 2 connected to the material output end of the wet ball mill 1 for receiving the ground and refined medical waste sludge and for adding additives and water to the ground and refined medical waste sludge to prepare sludge slurry, thereby improving the dispersibility and reducing the viscosity of the sludge particles, giving it corresponding fluidity; a storage tank 3 connected to the material output end of the preparation tank 2 for storing qualified sludge slurry with specific particle size and viscosity; an electrically heated conveying pipeline 4 connected between the discharge end of the storage tank 3 and the inlet end of the sludge atomizing spraying device 5 for conveying the qualified sludge slurry to the sludge atomizing spraying device 5 under heat; and a sludge atomizing spraying device 5 connected to the secondary combustion chamber 6 of the medical waste incineration line for spraying atomized medical waste sludge into the secondary combustion chamber 6. The medical waste incineration line has an incineration chamber, a secondary combustion chamber, and an exhaust gas treatment mechanism. For the specific composition, please refer to the utility model patent previously filed by the applicant with publication number CN222378103U, which will not be repeated in this invention.

[0024] During grinding and refining, the particle size of medical waste sludge needs to be strictly controlled. Excessively coarse particles will increase the viscosity of the sludge slurry and reduce its fluidity, while excessively fine particles are prone to agglomeration. Both of these factors will affect the atomization and spraying effect of the medical waste sludge, thus having an uncontrollable impact on the original incineration process of the medical waste incineration line, easily leading to one or more exhaust gas indicators exceeding the standards. In this embodiment, it is preferable to control the particle size of the medical waste sludge to between 80 and 200 mesh.

[0025] In this embodiment, when additives and water are added to form sludge slurry, the additive is a naphthalene sulfonate, and the amount of additive added is 1% of the total mass of the sludge slurry, while the amount of water added is 85% of the total mass of the sludge slurry. In some embodiments, the additive is one or more of naphthalene sulfonates, lignin sulfonates, or polycarboxylic acid polymers, and the total amount of additive added is appropriately selected between 0.5% and 1% of the total mass of the sludge slurry; the amount of water added is appropriately selected between 80% and 90% of the total mass of the sludge slurry. By adding additives and water to form sludge slurry, the additives will be adsorbed on the surface of the sludge powder, forming electrostatic repulsion or steric hindrance, preventing the agglomeration of medical waste sludge particles, and reducing the slurry viscosity from tens of thousands of mPa·s to 1000-2000 mPa·s.

[0026] Qualified sludge slurry refers to sludge slurry with both particle size and viscosity meeting the standards, that is, sludge slurry with a particle size between 80-200 mesh and a viscosity between 1000-2000 mPa·s. To avoid changes in particle size and viscosity of the sludge slurry caused by particle settling and agglomeration, in this embodiment, it is preferable to equip the sludge storage tank 3 with a stirrer 7 and a rotational viscometer 8. The rotational viscometer 8 is used to monitor the viscosity of the sludge slurry in the storage tank 3 online, and the operation of the stirrer 7 is controlled according to the monitored sludge slurry viscosity to keep the viscosity of the sludge slurry in the storage tank 3 within the range of 1000-2000 mPa·s (at 25°C). Ultimately, it must meet the requirements of fluidity, stability (72-hour settling layer thickness < 5%), and uniformity (sampling ash content deviation < 1%); and avoid the problems of high conveying resistance and atomization difficulties caused by excessive viscosity.

[0027] In this embodiment, it is preferable that the stirring action of the stirrer 7 is continuous low-speed stirring. This can ensure that the viscosity of the mud slurry is within the control range and prevent stratification, and can also avoid sudden excessive stirring that would cause air bubbles to be mixed in and affect atomization.

[0028] In this embodiment, a coarse filter 9 is provided on the connecting pipe between the wet ball mill 1 and the preparation tank 2 to filter out any large particles of sludge; a fine filter 10 is provided at the outlet end of the preparation tank 2. By setting the coarse filter 9 and the fine filter 10 to filter medical waste sludge and sludge slurry, the risk of clogging caused by large particles is effectively avoided, and the atomization effect is ensured.

[0029] When conveying qualified sludge slurry to the sludge atomizing injection device 5 under heat, a pressurized conveying method is used. The sludge slurry in the storage tank 3 is conveyed to the sludge atomizing injection device 5 at a stable pressure and flow rate (fluctuation <5%). The conveying pressure is provided by the screw pump 11, which continuously pushes the sludge slurry by relying on the volume change and movement of the meshing space formed by the pump body and the screw. The conveying pressure can reach 1.0-2.5MPa, and the flow rate adjustment range is wide. Seamless steel pipes are selected for the conveying pipeline, preferably 20# carbon steel seamless steel pipes, with an inner diameter between DN50 and DN150, determined according to the flow rate. The flow velocity is controlled at 1.5-2.5m / s; too low a flow velocity will easily cause sedimentation, and too high a flow velocity will wear down the pipeline. The conveying pipeline is laid at an incline with a slope of 3‰-5‰ to facilitate the installation of a drain valve at the lowest point for periodic slag discharge. When the furnace is shut down, the electric heat tracing conveying pipeline 4 is flushed with clean water at a pressure of 0.8-1.0 MPa to prevent residual sludge from drying and clogging.

[0030] When the qualified sludge slurry is heated and transported to the sludge atomization injection device 5, the temperature of the sludge slurry is maintained at 15-30℃ through the electrically heated conveying pipeline 4. Too low a temperature will cause the viscosity to increase, affecting the atomization injection of the sludge slurry and the matching of the combustion load. To ensure the accuracy of the atomization injection effect and the matching of the combustion load, a flow control unit 12 is also installed on the electrically heated conveying pipeline 4. The flow control unit 12 monitors the flow rate in real time through an electromagnetic flow meter, and the speed of the variable frequency motor of the screw pump 11 is adjusted by the PLC control system to match the sludge slurry flow rate with the incineration load. Simultaneously, a pressure stabilizing valve 13 is also installed on the electrically heated conveying pipeline 4 to ensure that the slurry pressure entering the sludge atomization injection device 5 is stable, with pressure fluctuations <3%.

[0031] In this embodiment, the preferred mesh size of the coarse filter 9 is 0.5 mm, and the preferred mesh size of the fine filter 10 is 0.3 mm. Both the coarse filter 9 and the fine filter 10 are Y-type filters to facilitate the discharge of filter residue. Obviously, those skilled in the art can appropriately adjust the mesh size and / or filter type of the coarse filter 9 and the fine filter 10 according to different actual needs.

[0032] It should be noted that the specific structure of the electric heat tracing pipeline 4 and the specific structure of the sludge atomizing spraying device 5 are common technical knowledge mastered by those skilled in the art, and will not be described in detail here.

[0033] Run the test.

[0034] The following operational tests will be conducted to determine the optimal matching relationship between sludge flow rate and medical waste incineration line incineration load, providing a basis for subsequent operation and control.

[0035] Run test 1.

[0036] Sludge slurry is sprayed at 3% of the amount of medical waste input into the medical waste incineration line, and flue gas data is monitored online.

[0037] Run test 2.

[0038] Sludge slurry is sprayed at 5% of the amount of medical waste input into the medical waste incineration line, and flue gas data is monitored online.

[0039] Run test 3.

[0040] Sludge slurry is sprayed at 10% of the amount of medical waste input into the medical waste incineration line, and flue gas data is monitored online.

[0041] Run test 4.

[0042] Sludge slurry is sprayed at 15% of the amount of medical waste input into the medical waste incineration line, and flue gas data is monitored online.

[0043] Run test 5.

[0044] No sludge slurry was sprayed as a control group, and flue gas data were monitored online.

[0045] The flue gas monitoring data for each operational test are shown in Table 1.

[0046] Table 1. Flue gas monitoring data for each operational test.

[0047]

[0048] Table 1 shows that the flue gas emission concentrations in all operational tests met the emission standards, and the injection of sludge slurry for co-firing significantly reduced the nitrogen oxide content in the flue gas. However, when sludge slurry was injected at 15% of the medical waste input of the medical waste incineration line, the carbon monoxide content in the flue gas increased significantly, indicating that the injected sludge slurry affected the original combustion process. Therefore, in actual operation, the optimal injection volume of sludge slurry is controlled below 10% of the medical waste input of the medical waste incineration line.

[0049] It should also be noted that the above embodiments only illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Parts not described in the specific embodiments are all prior art or common knowledge.

Claims

1. A medical waste sludge direct combustion system, characterized in that, The medical waste and sludge blending line is added to the second combustion chamber of the medical waste incineration line, slurry is sprayed into the second combustion chamber through the medical waste and sludge blending line, the moisture in the slurry is used to control the temperature of the second combustion chamber, thereby reducing the air supply amount of the second combustion chamber and reducing the emission of nitrogen oxides in the tail gas of the medical waste incineration line; The medical waste and sludge blending line comprises: A wet ball mill is used to receive and grind the medical waste and sludge to be incinerated; A preparation tank is connected to the output end of the wet ball mill and is used to receive the ground medical waste and sludge, add additives and water to the ground medical waste and sludge to prepare slurry, thereby improving the dispersibility and reducing the viscosity of the slurry particles, and making the slurry have corresponding fluidity; A slurry storage tank is connected to the output end of the preparation tank and is used to store the qualified slurry; An electric heat tracing conveying pipeline is connected to the output end of the slurry storage tank and is used to heat and convey the qualified slurry to a slurry atomization and spraying device; The slurry atomization and spraying device is connected to the second combustion chamber of the medical waste incineration line and is used to spray atomized medical waste slurry into the second combustion chamber of the medical waste incineration line; A conveying pump is used to convey the slurry in the slurry storage tank to the slurry atomization and spraying device; During grinding, the particles of the medical waste and sludge are ground to 80-200 mesh; When the additives and water are added to prepare the slurry, the additives are one or more of naphthalene sulfonate, lignin sulfonate or polycarboxylic acid high molecular compound, the total amount of the additives is 0.5%-1% of the total mass of the slurry, the amount of water is 80%-90% of the total mass of the slurry, the viscosity of the slurry is controlled to be between 1000-2000 mPa·s, the 72-hour sedimentation layer thickness is less than 5%, and the ash deviation is less than 1%.

2. The medical waste sludge direct combustion system according to claim 1, characterized in that, A stirrer and a rotary viscometer are arranged on the slurry storage tank, the viscosity of the slurry in the slurry storage tank is monitored online by the rotary viscometer, the stirrer is controlled to operate according to the monitored viscosity of the slurry, and the viscosity of the slurry in the slurry storage tank is kept within the range of 1000-2000 mPa·s, the 72-hour sedimentation layer thickness is less than 5%, and the ash deviation is less than 1%.

3. The medical waste sludge direct combustion system according to claim 2, characterized in that, The stirrer continuously stirs the slurry in the slurry storage tank.

4. The medical waste sludge direct combustion system according to claim 1, characterized in that, A coarse filter is arranged on the connecting pipeline between the wet ball mill and the preparation tank, and a fine filter is arranged at the outlet end of the preparation tank.

5. The medical waste sludge direct combustion system according to claim 4, wherein, Both the coarse filter and the fine filter are Y-type filters.

6. The medical waste sludge direct combustion system according to claim 1, wherein, The qualified slurry is heat-conveyed to the slurry atomization and spraying device by pressurized conveying, so that the slurry in the slurry storage tank is conveyed to the slurry atomization and spraying device at a stable pressure and flow rate.

7. The medical waste sludge direct combustion system according to claim 6, wherein, The conveying pressure of the pressurized conveying is provided by a screw pump, the conveying pressure range is 1.0-2.5 MPa, and the flow rate is controlled to be between 1.5-2.5 m / s.

8. The medical waste sludge direct combustion system according to claim 1, wherein, The electric heat tracing conveying pipeline is a seamless steel pipe with an inner diameter of DN50-DN150; the electric heat tracing conveying pipeline is laid in an inclined manner with a slope of 3‰-5‰.

9. The medical waste sludge direct combustion system according to claim 1, wherein, The electric heat tracing conveying pipe maintains the temperature of the sludge slurry between 15-30℃, and a flow control unit is further arranged on the electric heat tracing conveying pipe, the flow control unit monitors the flow in real time through an electromagnetic flowmeter, and the sludge slurry flow is adjusted by a PLC control system, so that the sludge slurry flow matches the incineration load of the medical waste incineration line; a pressure stabilizing valve is further arranged on the electric heat tracing conveying pipe, which is used to ensure that the pressure of the sludge slurry entering the sludge atomizing and spraying device is stable, and the pressure fluctuation is less than 3%.

10. The medical waste sludge direct combustion system according to claim 1, wherein, The spraying amount of the sludge slurry is controlled to be less than 10% of the medical waste input amount of the medical waste incineration line.

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