CN113860702B - A multi-field coupled sewage sludge automatic dehydration method - Google Patents

Abstract

The invention discloses a multi-field coupling automatic sewage sludge dewatering method, which comprises the following steps: adding a conditioner and primarily dehydrating the sewage sludge before multi-field coupling dehydration, storing the conditioned sludge in a sludge storage chamber, starting an oil cylinder after opening an electromagnetic valve to press the sludge into a sludge treatment chamber, moving an anode plate to a cathode plate, and maintaining the pressure between the anode plate and the cathode plate; the anode plate and the cathode plate are powered by a direct current power supply, the microwave magnetron is powered by a microwave driving power supply, the ultrasonic controller is powered by an ultrasonic driving power supply, and after sludge is dried, multi-field coupling dehydration is stopped; and the pressure between the anode plate and the cathode plate is increased, high-pressure mechanical filter pressing dehydration is carried out to reduce the water content, and the pressure between the anode plate and the cathode plate is kept after the water content is uniformly distributed; starting a direct-current power supply, a microwave system and an ultrasonic system, and repeatedly carrying out multi-field coupling sludge dewatering; after dehydration, the sludge is automatically treated under the action of an ultrasonic field.

Description

A multi-field coupled sewage sludge automatic dehydration method

Technical field

The present invention relates to the field of sewage sludge treatment, specifically a sewage sludge dehydration method that achieves lower moisture content through the synergistic coupling effect of multi-field coupling (ultrasonic field, microwave field, electric field, mechanical stress field).

Background technique

With the continuous expansion of the construction scale of urban sewage treatment facilities in my country, the amount of sludge produced during sewage treatment has increased dramatically. As of the end of 2019, my country's annual sludge (moisture content is calculated as 80%) production has exceeded 40 million tons, and it is expected to reach 60-80 million tons in 2020. Obviously, the high moisture content of sludge is a bottleneck restricting sludge treatment and disposal. Sludge with high moisture content is not only bulky, but also contains a large amount of organic matter, heavy metals and harmful microorganisms that are easily corrupted or released into the environment, causing secondary problems. Secondary pollution will have adverse effects on subsequent landfilling, incineration, and resource utilization of sludge. Therefore, deep dehydration and reduction of sludge is the primary purpose of sludge treatment and the basis for realizing the "four modernizations" of sludge. The drier the sludge, the more beneficial it is for subsequent treatment and disposal.

Sludge contains large amounts of flocs composed of microorganisms (mainly bacteria) embedded in biopolymers. Its special structure forms a highly porous fractal network containing colloids. The particles behave more like a gel-like material than a traditional particle suspension. This structure makes it difficult to dehydrate. At the same time, Vesilind, Vesilind and Hsu [Smith and Vesilind] respectively defined the existence form of water in sludge. Vesilind divided the water in sludge into four types: interstitial water, also known as free water, and capillary bound water. (interstitial water), surface adsorbed water (surface orvicinal water), and internal water (bound or hydration water). However, single mechanical stress field dehydration can only effectively remove free water in sludge, but it is difficult to remove capillary water from its pores. and adsorbed water, which has great limitations, greatly limiting the dehydration rate of sludge treatment.

Existing sludge deep dehydration technology (vacuum dehydration, continuous belt filter dehydration) and physical dehydration are suitable for dehydration of various mixed sludges, but the dehydration rate is not high. Finally, a dewatered sludge cake with a solid content of 19% can be obtained. . This is also a limitation of the single-field dehydration method, which cannot remove the adsorbed water in the pores.

The idea of the present invention is based on the effect of force field on sludge dehydration. On the basis of force field, ultrasonic field, electric field and microwave field are added, and the dehydration rate is increased through multi-field coupling method. At the same time, in the structure of the device, a feeding system (cylinder, solenoid valve) is set up to achieve the purpose of automatic feeding, and an unloading system (double-hinge fork-type oil cylinder hydraulic lifting platform, screw screw desilting propeller) is set up to achieve automatic unloading. The purpose of the material is to improve the automation level and efficiency of the device.

First, after applying an electric field, the sludge particles are negatively charged, while the water molecules are positively charged. Under the action of the electric field force, the negatively charged sludge particles move toward the anode plate, while the positively charged water molecules move toward the cathode plate. Under the action of the electrochemical reaction, the electrolyzed water moves strongly in a direction, and the temperature and pressure inside the cell increase, causing the cell membrane to rupture and the intracellular water to flow out. Therefore, solid particles are less likely to block the filter media, thereby increasing the dehydration rate.

Then, through the addition of microwave fields and the influence of magnetic fields, when polar molecular dielectrics and non-polar molecular dielectrics are placed in microwave electromagnetic fields, dipoles will be formed or existing dipoles will be rearranged in the dielectric material, and with the high frequency The alternating electromagnetic field swings at a speed of hundreds of millions of times per second. To rearrange the molecules with the direction of the ever-changing high-frequency electric field, it is necessary to overcome the interference and obstruction of the original thermal motion of the molecules and the interaction between molecules, resulting in something like Due to the effect of friction, this process will greatly intensify the molecular motion. At the same time, the electromagnetic field energy is gradually converted into new thermal energy, causing the medium temperature to increase significantly, that is, the entropy increases, the degree of system chaos becomes greater, and the thermal motion of the particles accelerates. This increases the dehydration rate.

At the same time, a large amount of sludge is embedded in the pores of the filter cloth, and the clogged water outlet holes greatly reduce the water outlet efficiency. However, through the ultra-high efficiency vibration of the ultrasonic field, a large amount of sludge on the filter cloth is cleaned, further increasing the efficiency of the water outlet. The efficiency is increased, and the ultrasonic field is also beneficial to cleaning the filter cloth during discharge.

However, the multi-field coupling dehydration technology currently still has the following main problems: (1) During the electroosmosis process, the moisture content of the sludge near the anode decreases rapidly, and the generation of electrochemical reaction gases and cracks in the sludge cake cause the sewage to sludge. The contact area between the mud cake and the electrode plate decreases, causing the sludge resistance to increase, the current to decrease, and the dehydration effect to deteriorate; (2) During the dehydration process, the electric field and microwave field convert electrical energy into thermal energy, which increases the temperature of the sludge. Increase, in fact, there is a problem of excessive energy consumption; (3) The moisture content of the mud cake is unevenly distributed in the thickness direction, the moisture content of the sludge in the anode layer is low, and water molecules accumulate in the cathode layer, causing pollution near the cathode plate. The moisture content of the mud is high; (4) During the dehydration process, multiple fields are attached to the sludge chamber at the same time, which is prone to experimental risks.

Therefore, the present invention adds a real-time monitoring detection system while coupling dehydration with multiple fields. Through sensor and computer integration, the thrust output by the hydraulic cylinder, the final pressure generated by the cylinder pushing the anode plate, pressure, and sludge stratification are monitored in real time. temperature, mud cake thickness.

Contents of the invention

The technical problem to be solved by the present invention is to provide a multi-field coupling (ultrasonic field, microwave field, electric field, mechanical stress field) sewage sludge automatic dehydration method with good dehydration effect.

The technical solution of the present invention is to provide the following multi-field coupling sewage sludge automatic dehydration method, which includes the following steps:

The sewage sludge is added with conditioners and initially dehydrated before multi-field coupling dehydration. The conditioned sludge is stored in the sludge storage chamber. After opening the solenoid valve, the oil cylinder is started to automatically press the sludge into the sludge treatment chamber. The anode plate is driven by a fully automatic hydraulic system to move toward the cathode plate, and when a certain pressure is reached, the pressure between the anode plate and the cathode plate is maintained; a DC power supply is used to power the anode plate and the cathode plate, and A microwave driving power supply is used to power the microwave magnetron, and an ultrasonic driving power supply is used to power the ultrasonic controller. Based on the sludge temperature, sludge thickness and mechanical pressure values detected by the detection system, the output power required for multi-field coupling is calculated through a computer. , achieving energy-saving coupling dehydration of constant voltage gradient, constant power density microwave field and ultrasonic field with precise control parameters; as the coupling dehydration proceeds, the sludge on the anode plate has a lower moisture content than the cathode plate, and the sludge dries out. At this time, stop the multi-field coupling dehydration; and increase the pressure between the anode plate and the cathode plate, and perform high-pressure mechanical press filtration and dehydration to further reduce the moisture content. After reaching a certain mechanical pressure, the moisture content is evenly distributed, and the anode plate is maintained. and the pressure between the cathode plate; start the DC power supply, microwave system and ultrasonic system, and repeat the multi-field coupling sludge dehydration; after the dehydration is completed, control the double-hinge fork-type oil cylinder hydraulic lifting platform to start, and the high-pressure welding cylinder With the cooperation, the cathode plate slowly exits the sludge treatment chamber. At this time, the screw desludge propeller is controlled. Under the action of the ultrasonic field, the sludge is automatically processed, completing a cycle.

Optionally, the sewage sludge is added with a conditioning agent and preliminary dehydration before multi-field coupling dehydration. The conditioning agent added is Fe ₂ (SO ₄ ) ₃ , FeCl ₃ , CaO and fly ash composite conditioning agent. The total conditioning agent added is The amount is 10-20% of the dry matter mass of the sludge, and the mass percentages of the four conditioners Fe ₂ (SO ₄ ) ₃ , FeCl ₃ , CaO and fly ash are 5-10%, 10-15% and 20-30 respectively. %, 30-45%. The functions of the four conditioners are to increase the sludge potential, increase the sludge floc structure, enhance the microwave heating effect, and create drainage channels to enhance mechanical pressure, electroosmosis, microwave and Due to the multi-field coupling effect of ultrasonic waves, the sludge is initially dehydrated to a moisture content of 75% to 80% after adding a conditioner.

Optionally, the microwave system includes a microwave magnetron, a microwave cooling fan, a microwave driving power supply, an electromagnetic waveguide, and a Teflon conductive screw. The microwave magnetron generates microwaves, and the microwave cooling fan keeps operating to reduce the microwave magnetism. The temperature of the tube is controlled. During the coupling dehydration process, the intensity of the microwave field is controlled by adjusting the microwave drive power supply; the generated microwave conducts the microwave through the cylindrical electromagnetic waveguide, which is placed below the cathode plate with the cathode plate in the middle. There are Teflon conductive screws.

Optionally, the ultrasonic system includes an ultrasonic vibrator, an ultrasonic controller, and an ultrasonic driving power supply. During the coupling dehydration process, the ultrasonic driving power supply supplies power to the ultrasonic vibrator, and the intensity of the ultrasonic wave is controlled by adjusting the ultrasonic controller. The ultrasonic vibrator is attached Attached to the cathode plate, the ultrasonic waves it generates propagate through the metal.

Optional, the power of the microwave system and ultrasonic system can be adjusted, and the output voltage of the DC power supply can be adjusted according to the sludge thickness. The working parameters of multi-field coupling can be dynamically adjusted according to different sludge input amounts, sludge types, and different dehydration stages. Combination to achieve coupling dehydration of constant voltage gradient, constant power density microwave field and ultrasonic field.

Optionally, the fully automatic hydraulic system includes a PLC control device, a hydraulic cylinder, a low-pressure direct-acting relief valve and a high-pressure direct-acting relief valve. The piston end of the hydraulic cylinder is connected to the anode plate, and the The low-pressure direct-acting relief valve and the high-pressure direct-acting relief valve are connected with the hydraulic cylinder.

Optionally, a multi-field coupled sewage sludge automatic dehydration device also includes a detection system, which includes a pressure sensor, a temperature sensor and a displacement sensor. A plurality of concave annular grooves are provided outside the sludge treatment chamber. There is a multi-winding temperature sensor inside, a pressure sensor is installed on the lower side of the hydraulic cylinder, and a pull-wire displacement sensor is installed on the upper side of the pressure sensor.

Optionally, the feeding system includes an oil cylinder, a sludge storage chamber and a solenoid valve. Before dehydration starts, after opening the solenoid valve, the oil cylinder is started, and the sludge is automatically pressed into the sludge treatment chamber.

Optionally, the unloading system includes a double-hinge fork-type oil cylinder hydraulic lifting platform and a screw desludge propeller. After the coupling dehydration is completed, the computer-controlled double-hinge fork-type oil cylinder hydraulic lifting platform is started. With the cooperation of the ultrasonic field, the cathode plate exits the sludge treatment chamber. At this time, the screw rod desludge propeller is controlled to clean the sludge under the cooperation of the ultrasonic field.

Using the above method, compared with the existing technology, the present invention has the following advantages: (1) Due to the charged, colloid and highly compressible porous medium of municipal sludge, the dehydration process is very difficult and the moisture content is high. Through the mechanical pressure stress field , electric field, sound field and other fields are processed in situ at the same time to achieve high dryness dehydration; (2) With the assistance of mechanical filter press dehydration, precise control of microwave fields and ultrasonic fields based on parameter feedback detected by sensors is achieved Multi-field coupling with electro-osmosis, under the simultaneous action of microwaves, ultrasonic waves and electro-osmosis, water molecules move from the anode plate to the cathode plate. As dehydration proceeds, the sludge in the anode layer dries, causing the resistance to increase and the current to decrease. The driving force of electro-osmotic dehydration decreases and the resistance increases. At this time, under the action of the microwave field and the electromagnetic field, the water molecules swing with the high-frequency alternating electromagnetic field at a speed of hundreds of millions of times per second, constantly changing. And rearrange, part of the water can flow back to the anode layer, reduce the resistance of the sludge, increase the current, and make the moisture content in the thickness direction of the sludge evenly distributed. In the next stage of dehydration, the electroosmotic voltage needs to be changed; at the same time, the water inside the sludge is sensitive to the microwave The absorption capacity is very large, resulting in the loss of microwave energy. If the control is not properly controlled, the interior of the sludge will be overheated, causing expansion and maturation. The ultrasonic field can facilitate cavitation, break up the internal floc structure of the sludge in large quantities, and increase the internal water content. Flow rate, and ultrasonic waves will also produce thermal effects inside the sludge. Since the acoustic vibrator is directly attached to the cathode plate, the ultrasonic waves generated by it can propagate in the metal, which can compensate for uneven microwave heating and improve the dehydration effect. The purpose is to make the sludge moisture content more uniform; (3) During the sludge dehydration process, tests have shown that the microwave and ultrasonic energy absorbed by the unit area of sludge is limited, and the added electric field has the best effect at a constant voltage gradient. Most energy efficient. Therefore, the sludge thickness, sludge temperature, and mechanical pressure parameters are collected in real time by sensors and processed by a computer to control the output power of microwaves, ultrasonics, and direct current through calculated control parameters to achieve constant power density and constant power under the most energy-saving conditions. Voltage gradient dehydration target.

Description of drawings

Figure 1 is a schematic structural diagram of a multi-field coupling sewage dehydration device;

Shown in the picture: 1. Sludge treatment chamber, 2. Fully automatic hydraulic system, 2.1. Hydraulic cylinder, 2.2. One-way throttle valve I, 2.3, One-way throttle valve II, 2.4, Electromagnetic reversing valve I , 2.5. Low-pressure direct-acting relief valve, 2.6. High-pressure direct-acting relief valve, 2.7. Electromagnetic reversing valve II, 2.8. Pilot-operated relief valve, 2.9. Hydraulic pump, 2.10. PLC control device, 3. Anode plate, 4. Cathode plate, 5. DC power supply, 6. Water outlet, 6.1, filter cloth, 6.2, fixed frame, 6.3, sealing ring, 7. Microwave system, 7.1, microwave magnetron, 7.2, microwave cooling fan , 7.3. Microwave drive power supply, 7.4. Electromagnetic waveguide, 7.5. Teflon conduction screw, 8. Detection system, 8.1. Pressure sensor, 8.2. Temperature sensor, 8.3. Displacement sensor, 8.4. Computer, 9. Feeding system, 9.1. Oil cylinder, 9.2. Mud storage chamber, 9.3. Solenoid valve, 10. Unloading system, 10.2. Double-hinge fork-type oil cylinder hydraulic lifting platform, 10.1. Screw desilting propeller, 11. Ultrasonic system, 11.1. Ultrasonic vibrator, 11.2, ultrasonic controller, 11.3, ultrasonic driving power supply.

Implementation

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The present invention covers any alternatives, modifications, equivalent methods and solutions within the spirit and scope of the invention. In order to provide the public with a thorough understanding of the present invention, specific details are described in the following preferred embodiments of the present invention, and those skilled in the art can fully understand the present invention without the description of these details. In addition, for the sake of illustration, the drawings of the present invention are not drawn exactly according to the actual scale, and are explained here.

The solution of the present invention is: the conditioned sludge is stored in the sludge storage chamber 9.2. After opening the solenoid valve 9.3, the oil cylinder 9.1 is started to automatically press the sludge into the sludge treatment chamber 1. The anode plate 3 is Driven by a fully automatic hydraulic system, it moves toward the cathode plate 4, and when a certain pressure is reached, the pressure between the anode plate 3 and the cathode plate 4 is maintained; a DC power supply 5 is used to supply power to the anode plate 3 and cathode plate 4. And the microwave drive power supply 7.3 is used to power the microwave magnetron 7.1, and the ultrasonic drive power supply 11.3 is used to power the ultrasonic controller 11.2. According to the sludge temperature, sludge thickness and mechanical pressure values detected by the detection system 8, it is calculated by the computer 8.4 Multi-field coupling requires output power, and precise control parameters are used to achieve energy-saving coupling dehydration of constant voltage gradient, constant power density microwave field and ultrasonic field; as the coupling dehydration proceeds, the sludge on the anode plate 3 is compared with the cathode The moisture content of plate 4 is low and the sludge is dried. At this time, the multi-field coupling dehydration is stopped; and the pressure between the anode plate 3 and the cathode plate 4 is increased to perform high-pressure mechanical filter dehydration to further reduce the moisture content and reach a certain mechanical After the pressure and moisture content are evenly distributed, maintain the pressure between the anode plate 3 and the cathode plate 4; start the DC power supply 5, the microwave system 7 and the ultrasonic system 11, and repeat the multi-field coupling sludge dehydration again. After the dehydration is completed, the computer 8.4 controls the double-hinge fork-type oil cylinder hydraulic lifting platform to start. With the cooperation of the HSG high-pressure welding cylinder (as an implementation mode of the hydraulic oil cylinder 2.1), the cathode plate 4 slowly exits the sludge treatment chamber 1 , at this time, the screw sludge removal propeller 10.1 is controlled. Under the action of the ultrasonic field, the sludge is automatically processed, completing a cycle. A multi-field coupling sewage sludge dehydration device based on mechanical filter press, including sludge treatment chamber 1, fully automatic hydraulic system 2, DC power supply 5, microwave system 7, feeding system 9, unloading system 10 and ultrasonic system 11, The feeding system 9 is connected to the side of the sludge treatment chamber 1. The anode plate 3 and the cathode plate 4 are provided in the sludge treatment chamber 1. The anode plate 3 is arranged in the sludge treatment chamber 1. In the upper part of the chamber 1, the cathode plate 4 is arranged in the lower part of the sludge treatment chamber 1. The positive and negative poles of the DC power supply 5 are connected to the anode plate 3 and the cathode plate 4 respectively. The anode plate 3 There are water outlets 6 on both the cathode plate and the cathode plate 4. A filter cloth 6.1 is laid on the water outlet holes 6. The microwave system 7 is arranged on the lower part of the cathode plate 4; the ultrasonic system 11 is arranged on the cathode plate 4. The lower part; the unloading system 10 is arranged below the cathode plate 4; the anode plate 3 is connected to the fully automatic hydraulic system 2 used to drive the movement of the anode plate 3.

The idea of the present invention is based on the effect of force field on sludge dehydration. On the basis of force field, ultrasonic field, electric field and microwave field are added, and the dehydration rate is increased through multi-field coupling method. At the same time, in the structure of the device, a feeding system (cylinder, solenoid valve) is set up to achieve the purpose of automatic feeding, and an unloading system (double-hinge fork-type oil cylinder hydraulic lifting platform, screw screw desilting propeller) is set up to achieve automatic unloading. The purpose of the material is to improve the automation level and efficiency of the device.

First, after an electric field is applied, the sludge particles are negatively charged, while the water molecules are positively charged. Under the action of the electric field force, the negatively charged sludge particles move toward the anode plate, while the positively charged water molecules move toward the cathode plate. Under the action of the electrochemical reaction, the electrolyzed water moves strongly in a direction, and the temperature and pressure inside the cell increase, causing the cell membrane to rupture and the intracellular water to flow out. Therefore, solid particles are less likely to block the filter media, thereby increasing the dehydration rate.

Then, through the action of additional microwave fields, ultrasonic fields, and electromagnetic fields, when polar molecular dielectrics and nonpolar molecular dielectrics are placed in microwave electromagnetic fields, dipoles will be formed or existing dipoles will be rearranged in the dielectric material, and as the The high-frequency alternating electromagnetic field swings at a speed of hundreds of millions of times per second. To rearrange the molecules in the direction of the ever-changing high-frequency electric field, it is necessary to overcome the interference and obstruction of the original thermal motion of the molecules and the interaction between molecules. Producing an effect similar to friction, this process will greatly intensify the molecular motion. At the same time, the electromagnetic field energy will gradually be converted into new thermal energy, causing the temperature of the medium to increase significantly, that is, the entropy will increase, the degree of system chaos will increase, and the sub-thermal motion will At the same time, the ultrasonic field can facilitate cavitation, break up the internal floc structure of the sludge in large quantities, increase the flow rate of internal water, and the ultrasonic waves will also produce thermal effects inside the sludge to compensate for the unevenness of microwave heating, thereby improving the dehydration rate. .

At the same time, a large amount of sludge is embedded in the pores of the filter cloth, and the clogged water outlet holes greatly reduce the water outlet efficiency. However, through the ultra-high frequency oscillation of the ultrasonic field, a large amount of sludge on the filter cloth is cleaned, further increasing the It improves efficiency, and the ultrasonic field is also beneficial to cleaning the filter cloth during discharge.

While coupling dehydration with multiple fields, the present invention adds a real-time monitoring detection system. Through sensor and computer integration, the invention real-time monitors the thrust output by the hydraulic cylinder, the final pressure generated by the cylinder pushing the anode plate, the pressure, and the sludge stratification. Temperature, mud cake thickness.

As shown in Figure 1, the multi-field coupling sewage sludge dehydration device of the present invention is schematically illustrated.

When the moisture content of the sewage sludge to be treated is high, pretreatment needs to be performed before entering the treatment of the present invention. The specific implementation of the pretreatment can be implemented using existing technology. The pretreatment refers to reducing the sludge moisture content to 75% to 80% through mechanical filter press dehydration, and adding a compound conditioner (Fe ₂ (SO ₄ ) ₃ + FeCl ₃ + CaO) to improve the sewage quality of the present invention. Sludge treatment efficiency. Before mechanical press filtration, Fe ₂ (SO ₄ ) ₃ +FeCl ₃ +CaO+fly ash composite conditioner, in which the calorific value of activated sludge (dry basis) after microwave conditioning gradually decreases with the increase of microwave radiation time, FeCl ₃ The addition of activated sludge floc can increase the activated sludge floc and reduce EPS, and increase the calorific value of activated sludge. Microwave coupling FeCl ₃ conditioning further enhances the dehydration performance of activated sludge; at the same time, FeCl ₃ is in the process of coupling with ultrasonic waves. The sludge specific resistance, VSS/SS, filter cake moisture content and filtrate turbidity were reduced to 0.29×109s ² /g, 0.580, 82.09% and 31.22NTU respectively, improving the ultrasonic efficiency under constant power density; during the electroosmosis process, organic matter was removed from The cathode migrates towards the anode. After adding Fe ₂ (SO ₄ ) ₃ , the migration amount of organic matter increases, the pH of the cathode mud cake becomes larger and the pH of the anode mud cake becomes smaller, and the pH gradient of the cathode and anode mud cakes increases. During the electroosmosis process, the Zeta potential of the original mud is mainly Affected by the pH of the mud cake; the Zeta potential of the conditioning mud is mainly affected by the ionic strength. The addition of ions in Fe ₂ (SO ₄ ) ₃ will increase the conductivity of the sludge, while CaO and fly ash can increase the internal pore structure of the sludge. , which is conducive to the free flow of water inside, so the addition of conditioner can increase the rate of electroosmotic dehydration to a certain extent.

The sludge is stored in the sludge storage chamber 9.2. After opening the solenoid valve 9.3, the oil cylinder 9.1 is started to automatically press the sludge into the sludge treatment chamber 1. The anode plate 3 is driven by the fully automatic hydraulic system and moves toward the cathode. The plate 4 moves, and when a certain pressure is reached, the pressure between the anode plate 3 and the cathode plate 4 is maintained; a DC power supply 5 is used to power the anode plate 3 and the cathode plate 4, and a microwave driving power supply 7.3 is used to power the microwave magnetron The pipe 7.1 is powered, and the ultrasonic drive power supply 11.3 is used to power the ultrasonic controller 11.2. According to the sludge temperature, sludge thickness and mechanical pressure values detected by the detection system 8, the output power required for multi-field coupling is calculated through the computer 8.4 to accurately The control parameters realize the coupling dehydration of constant voltage, constant power density microwave field and ultrasonic field; as the coupling dehydration proceeds, the sludge on the anode plate 3 has a lower moisture content than the cathode plate 4, and the sludge dries, and stops at this time Multi-field coupling dehydration; and increase the pressure between the anode plate 3 and the cathode plate 4, perform high-pressure mechanical filter dehydration to further reduce the moisture content, reach a certain mechanical pressure, and after the moisture content is evenly distributed, the anode plate 3 and the cathode are maintained The pressure between the plates 4; start the DC power supply 5, the microwave system 7 and the ultrasonic system 11, and repeat the multi-field coupling sludge dehydration again. After the dehydration is completed, the computer 8.4 controls the double-hinge fork-type oil cylinder hydraulic lifting platform to start. With the cooperation of the HSG high-pressure welding cylinder (as an implementation mode of the hydraulic oil cylinder 2.1), the cathode plate 4 slowly exits the sludge treatment chamber 1 , at this time, the screw sludge removal propeller 10.1 is controlled. Under the action of the ultrasonic field, the sludge is automatically processed, completing a cycle.

The hydraulic system includes a PLC control device 2.10, a hydraulic cylinder 2.1, a low-pressure direct-acting relief valve 2.5, and a high-pressure direct-acting relief valve 2.6. The piston end of the hydraulic cylinder 2.1 is connected to the anode plate 3. The low-pressure direct-acting relief valve 2.5 and the high-pressure direct-acting relief valve 2.6 are connected with the hydraulic cylinder 2.1. Since the pressure is different in different dehydration stages, the pressure applied to the anode plate 3 by the hydraulic cylinder 2.1 is adjusted through the PLC control device.

The microwave system includes a microwave magnetron 7.1, a microwave cooling fan 7.2, a microwave driving power supply 7.3, an electromagnetic waveguide 7.4, and a Teflon conductive screw 7.5. During the coupling dehydration process, the intensity of the microwave field can be controlled by adjusting the driving power supply. . At the same time, the microwave magnetron 7.1 generates microwaves, and the microwave cooling fan 7.2 keeps operating to reduce the temperature of the microwave magnetron 7.1. The generated microwave conducts the microwave through the cylindrical electromagnetic waveguide 7.4, which is placed below the cathode plate 4. A Teflon conductive screw 7.5 is placed in the middle of the cathode plate. Teflon is a good microwave conductive material and can be used to isolate pollution. The mud conducts microwaves as it releases water.

The ultrasonic system includes an ultrasonic vibrator 11.1, an ultrasonic controller 11.2, and an ultrasonic driving power supply 11.3. During the coupling dehydration process, the intensity of the ultrasonic wave can be controlled by adjusting the ultrasonic controller 11.2. At the same time, the ultrasonic vibrator 11.1 is directly attached to the cathode plate, and the ultrasonic waves generated by it can propagate in the metal, thereby cleaning the filter cloth.

The unloading system includes a double-hinge fork-type oil cylinder hydraulic lifting platform 10.2 and a screw desludge propeller 10.1. After the coupling dehydration is completed, the computer 8.4 controls the double-hinge fork-type oil cylinder hydraulic lifting platform 10.2 to start. In the hydraulic oil cylinder 2.1 With the cooperation of the ultrasonic field, the cathode plate 4 slowly exits the sludge treatment chamber. At this time, the screw desludge propeller 10.1 is controlled to clean the sludge under the cooperation of the ultrasonic field, completing a cycle.

The feeding system includes an oil cylinder 9.1, a mud storage chamber 9.2, and a solenoid valve 9.3. Before the coupling dehydration starts, the solenoid valve 9.3 can be opened and the oil cylinder 9.1 can be started to automatically press the sludge into the sludge treatment chamber 1.

There are multiple concave annular grooves on the outside of the sludge treatment chamber 1, and a multi-winding temperature sensor 8.2 is provided inside. This sensor is close to the sludge and has high sensitivity. After being connected to a computer, it can monitor the sludge in real time. layer temperature.

A pressure sensor 8.1 is provided on the lower side of the hydraulic cylinder 2.1. This sensor is in direct contact with the sludge anode plate. Compared with the thrust output by the hydraulic station, it can more intuitively reflect the size of the pressure field and has high sensitivity. After being connected to a computer, the pressure can be monitored in real time. size, and calculate the possible pressure through P=F/S.

The pressure sensor 8.1 is provided with a pull-wire displacement sensor 8.3 on the upper side. This sensor can reflect the pushing distance of the oil cylinder more intuitively and has high sensitivity. After being connected to a computer, the displacement can be monitored in real time, and through D (mud cake thickness) = H (contamination Mud thickness)-S (displacement) to calculate the thickness of the mud cake.

The sewage sludge dehydration device adopts an alternating variable pressure dehydration mode. After the high-pressure mechanical filter press dehydration, the moisture content between the two polar plates changes from uneven to uniform, and then multi-field coupling dehydration is performed again, and so on until Meet the expected sludge moisture content requirements. Due to the adoption of the alternating voltage transformer dehydration mode, the anode plate sludge is rehydrated, changing from dry sludge to wet sludge, and then back to the coupling dehydration stage of electroosmosis and mechanical filtration. At this time, high and low pressure The regulating device is switched to low pressure and dehydrated together with electroosmosis.

Seal rings 6.3 are respectively provided between the anode plate 3, the cathode plate 4 and the sludge treatment chamber 1. The insulating rings insulate the anode plate 3, the cathode plate 4 and the sludge treatment chamber 1 from each other. The anode plate 3 and the cathode are insulated from each other. Plate 4 is made of electrical corrosion-resistant material (titanium alloy).

The anode plate 3 and the hydraulic cylinder 2.1 are connected by threads, and the movement of the cylinder can be controlled by the PLC control program to control the position of the anode plate, so that the entire device can realize the mechanized operation of automatic withdrawal, greatly reducing the need for manual withdrawal. burden and improve the automation level and efficiency of the device.

An aluminum shell and a microwave detector are added to the outside of the entire device to monitor the leakage concentration of microwaves in the air in real time to ensure the safety of the experiment.

A microwave system 7, an ultrasonic system 11, and an unloading system 10 are provided on the lower side of the cathode plate 4. The microwave system 7 is transmitted to the lower side of the cathode plate through a special electromagnetic waveguide 7.4. The microwave system 11 is connected to the microwave vibrator 11.1 placed on the lower side of the cathode plate through a wire. In the unloading system 10, due to the double-hinge fork-type oil cylinder hydraulic lifting platform 10.2 It is placed directly under the cathode plate under force. During the unloading process of the filter cloth 6.1, the microwave system 7 and the ultrasonic system 10 can be used to clean the sludge on the surface of the filter cloth.

The sludge treatment chamber 1 may also be a rectangular cylinder, and the shape of the sludge treatment chamber 1 does not affect the implementation of the present invention.

The hydraulic system includes a hydraulic real-time control system and a high and low pressure regulating device. The hydraulic real-time control system is part of the hydraulic system. Considering the external factors affecting the cylinder during operation, the working state is often unstable. Therefore, this paper designs a hydraulic real-time control system to adjust the output pressure of the hydraulic station when the oil cylinder filter pressure state does not meet the standard. The hydraulic real-time control system designed in this article is based on an embedded development control system with a single-chip microcomputer as the core. It controls the stepper motor by receiving signals from the pressure sensor on the lower side of the oil cylinder. The high and low pressure regulating device is another part of the hydraulic system. Although there are many ways to achieve its function, this embodiment still lists a detailed preferred embodiment, that is, the high and low pressure regulating device includes a one-way throttle valve. I2.2, one-way throttle valve II2.3, electromagnetic reversing valve I2.4, electromagnetic reversing valve II2.5, low-pressure direct-acting relief valve 2.6, high-pressure direct-acting relief valve 2.7, pilot-operated overflow valve The flow valve 2.8 and the hydraulic pump 2.9, the one-way throttle valve I2.2 and the one-way throttle valve II2.3 are respectively connected with the inlet and outlet of the hydraulic cylinder 2.1 and the electromagnetic reversing valve I2.4. The pilot relief valve 2.8 is connected with the electromagnetic reversing valve I2.4 and the electromagnetic reversing valve II2.7. The electromagnetic reversing valve II2.7 is connected with the low-pressure direct-acting relief valve 2.5 and the high-pressure direct-acting relief valve. The valve 2.6 is connected. The low-pressure direct-acting relief valve 2.5 and the high-pressure direct-acting relief valve 2.6 are used to adjust the outlet pressure of the hydraulic pump 2.9 through the electromagnetic reversing valve II 2.7, thereby adjusting the sludge pressing pressure at low pressure. The pressure on the sludge is 0.05-0.5MPa, and the pressure on the sludge during high-pressure pressing is 3-5MPa. In addition, the high and low pressure regulating devices can be equipped with motors, oil tanks, oil suction filters, coolers, air filters, liquid level gauges, pressure gauges and other components.

It can be seen that the present invention can adopt the following stages of work:

① Pretreatment dehydration and automatic feeding stage: sewage sludge enters the pretreatment dehydration device and is squeezed in the pretreatment dehydration device to achieve preliminary mechanical filter press dehydration, reducing the sludge moisture content to 75%-80%; this dehydration In this stage, the reduction of sewage sludge can be achieved to a great extent. In this stage, medium and low pressure mechanical filter press is used, and the pressure is generally 0.1-0.5MPa; in this stage, the sewage sludge with higher moisture content enters. In the pretreatment and dehydration stage before the device of the present invention, Fe ₂ (SO ₄ ) ₃ +FeCl ₃ +CaO composite conditioner is added to the sludge with a moisture content lower than 80% to condition the sludge to improve mechanical filter press and mechanical The three-field coupling dehydration characteristics of electroosmosis, microwave, and ultrasonic waves in the pressure-holding stage allow the conditioned sludge to directly enter the mud storage device of the present invention for dehydration;

② Multi-field coupling (ultrasonic field, ultrasonic field, microwave field, electric field, mechanical field) dehydration stage: After step ①, the sewage sludge is stored in the mud storage chamber. After opening the solenoid valve and the oil cylinder, the sludge is automatically pressed in In the sludge treatment chamber, preliminary mechanical pressure filtration and dehydration are performed. After reaching a certain pressure, the mechanical pressure between the anode plate and the cathode plate is maintained to ensure good contact between the two plates and the sludge. The positive and negative poles of the DC power supply are electrically connected to the anode plate and cathode plate respectively. The power supply voltage is determined according to the sludge treatment volume (mud cake thickness), and the voltage gradient is set to 10-30V/cm. The multi-field coupled anode plate and cathode plate are placed in the sludge treatment chamber. A DC power supply is used to power the anode plate and cathode plate. A microwave driving power supply is used to power the microwave magnetron and the ultrasonic system is turned on. After this step, the sludge is treated The moisture content can reach 50%-60%. In step ②, the pressure of the mechanical filter press is in a variable range. As the filter press proceeds, the amount of sludge between the anode plate and the cathode plate decreases, requiring further pressurization. The pressure in this stage is 0.05-0.5 MPa.

During the dehydration process, the water flowing out from electroosmosis and mechanical pressure filtration passes through the filter cloth laid on the anode plate and cathode plate and flows out through the water outlet hole. The filter cloth (the material of which is not limited to traditional cloth, all materials capable of filtering can be considered as filter cloth) and the filter cloth wrapping the cathode plate are made of stainless steel, which is beneficial to improving the electroosmotic dehydration effect.

③ Multi-field coupling (ultrasonic field, ultrasonic field, microwave field) filter press dehydration and discharge stage: After step ②, the sludge moisture content of the anode plate is low and the sludge is dry. At this time, the multi-field coupling dehydration is disconnected , and increase the pressure between the anode plate and the cathode plate to achieve high-pressure mechanical filter dehydration. The sludge moisture flows in both directions to the cathode plate and the anode plate, making the moisture content between the two plates even. This dehydration stage is high-pressure dehydration, and the pressure provided to the sludge is 3-5MPa.

After the dehydration is completed, the computer controls the hydraulic lifting platform of the double-hinge fork-type oil cylinder to start. With the cooperation of the HSG high-pressure welding cylinder, the cathode plate slowly exits the sludge treatment chamber. At this time, the screw desludge propeller is controlled to operate in the ultrasonic field. With the cooperation of , the sludge is cleaned and a cycle is completed.

The above only describes the preferred embodiments of the present invention, but should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. In short, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

Claims (4)

1. An automatic dehydration method for sewage sludge by multi-field coupling is characterized in that: the multi-field coupling sewage sludge automatic dehydration device comprises a sludge treatment chamber (1), a full-automatic hydraulic system (2), a direct current power supply (5), a microwave system (7), a feeding system (9), a discharging system (10), an ultrasonic system (11) and a detection system (8), wherein the feeding system (9) is communicated with the side part of the sludge treatment chamber (1), an anode plate (3) and a cathode plate (4) are arranged in the sludge treatment chamber (1), the anode plate (3) is arranged on the upper part of the sludge treatment chamber (1), the cathode plate (4) is arranged on the lower part of the sludge treatment chamber (1), the anode and cathode of the direct current power supply (5) are respectively connected with the anode plate (3) and the cathode plate (4), water outlets (6) are formed in the anode plate (3) and the cathode plate (4), filter cloth (6.1) is laid on the water outlets (6), and the microwave system (7) is arranged on the lower part of the cathode plate (4). The ultrasonic system (11) is arranged at the lower part of the cathode plate (4); the discharging system (10) is arranged below the cathode plate (4); the anode plate (3) is connected with a full-automatic hydraulic system (2) for driving the anode plate (3) to move; the detection system (8) detects the temperature, mechanical pressure and sludge thickness of the sludge in the dehydration process so as to uniformly control and coordinate the full-automatic hydraulic system (2), the direct-current power supply (5), the microwave system (7), the feeding system (9), the discharging system (10) and the ultrasonic system (11); the feeding system comprises an oil cylinder (9.1), a sludge storage chamber (9.2) and an electromagnetic valve (9.3), wherein before dehydration starts, the electromagnetic valve (9.3) is opened, the oil cylinder (9.1) is started, and sludge is automatically pressed into the sludge treatment chamber (1); the full-automatic hydraulic system comprises a PLC control device (2.10), a hydraulic cylinder (2.1), a low-pressure direct-acting overflow valve (2.5) and a high-pressure direct-acting overflow valve (2.6), wherein the piston end of the hydraulic cylinder (2.1) is connected with an anode plate (3), and the low-pressure direct-acting overflow valve (2.5) and the high-pressure direct-acting overflow valve (2.6) are communicated with the hydraulic cylinder (2.1); the discharging system comprises a double-hinged fork type oil cylinder hydraulic lifting platform (10.2) and a screw rod mud removing propeller (10.1), after coupling dehydration is finished, the double-hinged fork type oil cylinder hydraulic lifting platform (10.2) is controlled by a computer (8.4) to start, under the cooperation of the hydraulic oil cylinder (2.1), a cathode plate (4) is withdrawn from a mud treatment cavity, at the moment, the screw rod mud removing propeller (10.1) is controlled, and mud is cleaned under the cooperation of an ultrasonic wave field; the microwave system (7) comprises a microwave magnetron (7.1), a microwave cooling fan (7.2), a microwave driving power supply (7.3), an electromagnetic waveguide (7.4) and a Teflon conducting screw (7.5), microwaves are generated by the microwave magnetron (7.1), the microwave cooling fan (7.2) keeps running to reduce the temperature of the microwave magnetron (7.1), and the intensity of a microwave field is controlled by adjusting the microwave driving power supply (7.3) in the coupling dehydration process; the generated microwaves are conducted through a cylindrical electromagnetic waveguide (7.4), the electromagnetic waveguide (7.4) is arranged below a cathode plate (4), and a Teflon conducting screw (7.5) is arranged in the middle of the cathode plate; the ultrasonic system comprises an ultrasonic vibrator (11.1), an ultrasonic controller (11.2) and an ultrasonic driving power supply (11.3), wherein in the coupling dehydration process, the ultrasonic driving power supply (11.3) supplies power to the ultrasonic vibrator (11.1), the intensity of ultrasonic waves is controlled by adjusting the ultrasonic controller (11.2), the ultrasonic vibrator (11.1) is attached to a cathode plate, and ultrasonic waves generated by the ultrasonic vibrator propagate in metal;

the method comprises the following steps:

the method comprises the steps that conditioner adding and preliminary dehydration are carried out on sewage sludge before multi-field coupling dehydration, the conditioned sludge is stored in a sludge storage chamber (9.2), an oil cylinder (9.1) is started after an electromagnetic valve (9.3) is opened, so that the sludge is automatically pressed into a sludge treatment chamber (1), an anode plate (3) moves towards a cathode plate (4) under the driving of a full-automatic hydraulic system, and the pressure between the anode plate (3) and the cathode plate (4) is kept when a certain pressure is reached; the direct-current power supply (5) is adopted to supply power to the anode plate (3) and the cathode plate (4), the microwave driving power supply (7.3) is adopted to supply power to the microwave magnetron (7.1), the ultrasonic driving power supply (11.3) is adopted to supply power to the ultrasonic controller (11.2), and the energy-saving coupling dehydration of the constant-voltage gradient, the constant-power density microwave field and the ultrasonic field is realized by calculating the output power required by multi-field coupling through the computer (8.4) according to the sludge temperature, the sludge thickness and the mechanical pressure value detected by the detection system (8); along with the progress of coupling dehydration, the water content of the sludge of the anode plate (3) is lower than that of the sludge of the cathode plate (4), and the sludge is dried, so that multi-field coupling dehydration is stopped; the pressure between the anode plate (3) and the cathode plate (4) is increased, high-pressure mechanical filter pressing dehydration is carried out, so that the water content is further reduced, a certain mechanical pressure is achieved, and after the water content is uniformly distributed, the pressure between the anode plate (3) and the cathode plate (4) is kept; starting a direct current power supply (5), a microwave system (7) and an ultrasonic system (11), and repeatedly carrying out multi-field coupling sludge dehydration again; after dehydration is completed, the hydraulic lifting platform of the double-hinged fork-type oil cylinder is controlled to start, the cathode plate (4) slowly withdraws from the sludge treatment cavity (1) under the cooperation of the hydraulic oil cylinder (2.1), at the moment, the screw rod sludge removal propeller (10.1) is controlled, and the sludge is automatically treated under the action of an ultrasonic field, so that one cycle is completed.

2. The multi-field coupling automatic sewage sludge dewatering method according to claim 1, wherein: the added conditioning agent is Fe ₂ (SO ₄ ) ₃ 、FeCl ₃ The total addition amount of the conditioning agent is 10-20% of the dry matter mass of the sludge, and Fe ₂ (SO ₄ ) ₃ 、FeCl ₃ The mass percentages of the four conditioning agents of CaO and fly ash are 5-10%,10-15%, 20-30% and 30-45% respectively.

3. The multi-field coupling automatic sewage sludge dewatering method according to claim 1, wherein: the power of the microwave system (7) and the ultrasonic system (11) is regulated, the output voltage of the direct current power supply (5) is regulated according to the sludge thickness, and the working parameter combination of multi-field coupling is dynamically regulated according to different sludge feeding amounts, sludge types and sludge thicknesses in different dewatering stages, so that the coupling dewatering of a constant voltage electric field, a constant power density microwave field and an ultrasonic field is realized.

4. The multi-field coupling automatic sewage sludge dewatering method according to claim 1, wherein: the detection system (8) comprises a pressure sensor (8.1), a temperature sensor (8.2) and a displacement sensor (8.3), wherein a plurality of concave annular grooves are formed in the outer side of the sludge treatment chamber (1), a plurality of winding-type temperature sensors (8.2) are arranged in the concave annular grooves, the pressure sensor (8.1) is arranged on the lower side of the hydraulic cylinder (2.1), and a stay-supported displacement sensor (8.3) is arranged on the upper side of the pressure sensor (8.1).