Vacuum Temperature Load Multi-Field Coupled Test System and Its Application Method

Abstract

This invention discloses a vacuum temperature load multi-field coupling test system and its usage method; belonging to the field of sludge or sewage dewatering and drying technology; including a heating device, a loading device, a model box, an air-water separator, and a data acquisition instrument; the model box holds the sludge used in the experiment and serves as a container for conducting rapid sludge dewatering experiments; the heating device changes the temperature of the sludge; the loading device is responsible for squeezing and draining the sludge; the air-water separator is responsible for collecting the water discharged from the sludge and providing the negative pressure required by the system; the data acquisition instrument collects the data generated by the system and adjusts the negative pressure setpoint; during the experiment, the upper drainage device and the lower drainage valve are opened to start vacuum negative pressure dewatering and reduce the moisture content of the sludge; when the vacuum negative pressure makes it difficult for the sludge to continue dewatering, the heating device and the loading device are turned on to carry out deep dewatering until the end of the experiment; this invention has the advantages of high dewatering efficiency, good economic benefits, and low dewatering cost.

Description

Technical Field

[0001] This invention relates to a vacuum temperature load multi-field coupling test system and its application method, belonging to the field of sludge or sewage dewatering and drying technology. Background Technology

[0002] Sludge or wastewater sludge has a high water content, typically between 96% and 99%, requiring volume reduction treatments (concentration, dewatering, drying, etc.). The complex composition, strong hydrophilicity, and high water content of sludge or wastewater sludge make dewatering difficult. Therefore, rapid dewatering of sludge or wastewater sludge has always been a key focus and challenge in sludge or wastewater sludge treatment. Traditionally, top loading of the sludge or wastewater sludge is used. However, due to the high water content and compressibility of sludge or wastewater sludge, the top loading device is easily damaged, leading to incomplete dewatering and low dewatering efficiency. Furthermore, traditional rapid sludge dewatering experimental devices use single-sided vacuum negative pressure drainage, which significantly reduces the dewatering rate in the later stages of the process. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a vacuum temperature load multi-field coupling test system and its usage method.

[0004] The objective of this invention is achieved through the following technical solution: a vacuum temperature load multi-field coupling test system, comprising a heating device, a loading device, a model box, a gas-water separator, and a data acquisition instrument; the model box contains the sludge used in the experiment and serves as a container for conducting rapid sludge dewatering experiments; the heating device changes the temperature of the sludge; the loading device is responsible for squeezing and dewatering the sludge; the gas-water separator is responsible for collecting the water discharged from the sludge, collecting the real-time drainage volume, and providing the vacuum negative pressure required by the system, ensuring that the discharged water does not enter the vacuum pump and avoid damaging the instrument; the data acquisition instrument collects the data generated by the system and adjusts the vacuum negative pressure setpoint.

[0005] Preferably, the heating device includes a circulating water pump, a hot water pipe, a cold water pipe, a water tank, a top opening valve of the water tank, a heating device switch, a temperature adjustment knob, a temperature display screen, a heating device power supply, and a model box top cover. The water tank is connected to the circulating water pump, which pumps hot water from the water tank through the hot water pipe to the top cover of the model box. The top cover of the model box is placed on the sludge inside the model box, transferring heat to the sludge. The circulating water pump pumps cold water from the top cover of the model box through the cold water pipe back to the water tank for heating. The water tank is equipped with a heating wire and a temperature sensor A. The temperature is adjusted by the temperature adjustment knob and the water temperature value is displayed on the temperature display screen. The heating device operates when powered by the heating device power supply. The top opening valve of the water tank controls the operation of the circulating water pump, and the heating device switch controls the heating of the water in the water tank.

[0006] Preferably, the model box top cover includes an upper top cover plate, a lower top cover plate, a top loading device connector, a hot water inlet connector, and a cold water outlet connector; the upper top cover plate and the lower top cover plate are detachably connected; the top loading device connector, the hot water inlet connector, and the cold water outlet connector are respectively disposed on the upper surface of the upper top cover plate; the model box top cover is connected to the loading device through the top loading device connector; the lower top cover plate has an S-shaped water flow groove, one end of which is a hot water inlet corresponding to the hot water inlet connector, and the other end of which is a cold water outlet corresponding to the cold water outlet connector; the lower top cover plate has a temperature sensor probe connected to a data acquisition instrument to record the water temperature in the water flow groove in real time; one end of the hot water inlet connector is connected to a hot water pipe, and the other end of the hot water inlet connector passes through the upper top cover plate and is connected to the hot water inlet; one end of the cold water inlet connector is connected to a cold water pipe, and the other end of the cold water inlet connector passes through the upper top cover plate and is connected to the cold water outlet.

[0007] The heating device uses a water tank and a model box top cover. The water bath heats the top cover of the model box, conducting heat to the sludge. This eliminates the limitations of traditional direct electric heating of the sludge, resulting in more uniform heating of the sludge's surface and downward heat conduction. Furthermore, because the water temperature can be controlled, the effect of temperature gradient changes on sludge dewatering can be studied in experiments. When a vacuum negative pressure is created inside the sludge, the boiling point of the water contained within decreases under this negative pressure. When heated to a temperature other than the reported temperature, the water vaporizes and can pass through narrower pores into the air-water separator, which is beneficial for deep sludge dewatering.

[0008] Preferably, the loading device includes a top loading rangefinder and a top loading device. The top loading device is equipped with a pressure screw, and the lower end of the pressure screw is sequentially equipped with a stepper motor and a pressure sensor, and connected to the top cover of the model box. The stepper motor drives the pressure screw to move vertically up and down within the top loading device. Both the stepper motor and the pressure sensor are connected to a data acquisition device. The data acquisition device applies pressure to the sludge by controlling the stepper motor, and the pressure sensor transmits the pressure magnitude to the data acquisition device in real time. The top loading rangefinder is equipped with a ranging rod, which moves vertically up and down within the top loading rangefinder. The bottom end of the ranging rod is equipped with a top cover contact point that contacts the top cover of the model box. The top cover contact point is connected to the data acquisition device via a data cable to record the descent distance and speed of the top cover of the model box in real time. The descent distance of the ranging rod is the amount of sludge settling.

[0009] The data acquisition instrument connects to computer software via a USB interface, enabling two pressurization modes: constant pressure and constant speed. By changing the pressurization parameters, the effects of these parameters on the sludge dewatering process are studied to achieve efficient dewatering. The study of coupling vacuum negative pressure, top loading, and heating to accelerate the rapid dewatering of sludge or silt provides a convenience for developing the theory of bidirectional dewatering and consolidation of sludge under temperature load. The two pressurization methods are implemented by monitoring the distance the measuring rod descends.

[0010] Preferably, the model box includes a base, a sludge tank, a drainage bottom plate, a vacuum bag fixing device, an upper drainage device, and a lower drainage valve; the base has a groove, and the bottom of the sludge tank is connected to the base through the groove; the drainage bottom plate is located inside the sludge tank, forming an open layer between the drainage bottom plate and the base; the drainage bottom plate has N upper drainage holes, N≥10; the upper surface of the base has lower drainage holes; the interior of the base has a drainage channel, which connects to the lower drainage valve; the lower drainage holes, drainage channel, and lower drainage valve are interconnected; the lower drainage valve... The system is connected to an air-water separator. The upper surface of the drainage base plate is covered with permeable geotextile, and above the permeable geotextile is a sludge holding layer. A vacuum bag is placed inside the sludge tank, positioned above the sludge, and its opening is sealed by a vacuum bag fixing device. The side wall of the sludge tank is equipped with an upper drainage device, a vacuum negative pressure sensor, a temperature sensor B, and a pore pressure sensor. The inlet of the upper drainage device is located in the sludge, and its outlet is connected to the air-water separator to drain water from the sludge. The vacuum negative pressure sensor, temperature sensor B, and pore pressure sensor are all connected to a data acquisition instrument. Multiple drainage base plates can be preset in the embodiment, and the influence of different boundary conditions on sludge drainage and consolidation can be studied by changing the drainage base plates.

[0011] Preferably, the sludge tank is provided with stirrups on the outside, and the bottom of the stirrups is connected to the base. The vacuum bag fixing device includes a stirrup ring and a vacuum bag sealing ring. The stirrup ring is set on the top of the model box, and the vacuum bag sealing ring is detachably connected to the stirrup ring. The top of the stirrup passes through the stirrup ring, and the stirrup ring ensures that the side wall of the model box is firmly connected to the base and that there is no air or mud leakage.

[0012] Preferably, there are three vacuum negative pressure sensors, three temperature sensors B, and three pore pressure sensors. The vacuum probe of one vacuum negative pressure sensor, the temperature probe of the temperature sensor B, and the pore water pressure gauge of the pore pressure sensor are respectively distributed in the middle of the sludge. The vacuum probe of the other two vacuum negative pressure sensors, the temperature probe of the temperature sensors, and the pore water pressure gauge of the pore pressure sensors are respectively distributed at the upper and lower ends of the sludge. The number of vacuum negative pressure sensors, temperature sensors B, and pore pressure sensors can be arranged according to actual needs, aiming to measure parameters in the upper, middle, and lower parts of the sludge as much as possible.

[0013] Preferably, the gas-liquid separation device includes a weighing scale, a weighing scale display, a housing, an atmospheric pressure inlet cover, a solenoid valve, a vacuum gauge, and a vacuum pump. The weighing scale is located at the bottom of the housing and is connected to the weighing scale display and a data acquisition instrument. The atmospheric pressure inlet cover, solenoid valve, and vacuum gauge are all located at the top of the housing. A three-way valve is provided on the side wall of the housing, with an upper drain pipe and a lower drain pipe respectively. Both the upper and lower drain pipes are connected to the model box. One end of the solenoid valve is connected to the top of the housing, and the other end of the solenoid valve is connected to the vacuum pump. The solenoid valve is equipped with a negative pressure probe, and the vacuum negative pressure value recorded by the negative pressure probe is directly displayed on the screen of the data acquisition instrument. The solenoid valve is connected to the data acquisition instrument.

[0014] The weighing scale is responsible for weighing the sludge discharge water; the lower drainage pipe connects to the lower drainage valve for lower drainage, which refers to the sludge being drained through the permeable geotextile and drainage base plate into the overhead layer. The loading device compresses the sludge, causing it to seep through the permeable geotextile into the base for drainage; the upper drainage pipe connects to the upper drainage device for upper drainage, which refers to the sludge being dewatered through the upper drainage device within the sludge. When the negative pressure in the air-water separator reaches the set value, the solenoid valve automatically closes; if the negative pressure is insufficient, the solenoid valve automatically opens to compensate.

[0015] Preferably, the loading device and the model box are both mounted on a loading device support. The loading device support includes a loading device platform, a column, and a base plate. The loading device platform is connected to the base plate via the column, and the loading device platform and column support the loading device. The loading device platform has a through hole, and the top of the base plate has two parallel model box sliding rails. The bottom of the model box is slidably connected to the base plate via the model box sliding rails. The bottom of the base plate is equipped with casters.

[0016] The bottom of the model box has a sliding base plate, which makes it easy to pull out the model box to place sludge, install sensors, and place vacuum bags for vacuum sealing; the casters at the bottom of the base plate make it easy to move the loading device bracket, making it convenient to use.

[0017] The method for using a vacuum temperature load multi-field coupled test system is as follows:

[0018] Step 1: Place the permeable geotextile on the drainage base plate and use sealant to firmly attach the edges of the permeable geotextile to the inner wall of the sludge tank; then place the sludge on the permeable geotextile.

[0019] Step 2: Distribute the three vacuum negative pressure sensors, three temperature sensors, and three pore pressure sensors at the top, middle, and bottom positions of the sludge, respectively; then place the vacuum bag into the sludge tank and seal the top of the vacuum bag with the vacuum bag fixing device; finally, place the top cover of the model box into the sludge tank.

[0020] Step 3: Set the maximum and minimum values ​​of the vacuum negative pressure on the data acquisition instrument;

[0021] Step 4: Close the upper drainage device and lower drainage valve of the model box, close the atmospheric pressure connection port cover of the gas-water separator, turn on the vacuum pump, and first evacuate the vacuum in the gas-water separator to the experimental preset value.

[0022] Step 5: Open the upper drainage device and lower drainage valve of the model box, turn on the vacuum pump, and vacuum negative pressure dehydration begins;

[0023] Step Six: When the data on the scale display of the air-water separator remains unchanged for a period of time, indicating that the vacuum negative pressure dewatering makes it difficult for the sludge to continue deep dewatering, start the loading device and turn on the heating device. Use the loading device to pressurize and the heating device to heat the sludge to continue dewatering. After the dewatering experiment is completed, turn off the vacuum pump, heating device, and loading device, and open the atmospheric pressure connection port cover of the air-water separator.

[0024] Step 7: Reset the loading device, remove the top cover of the model box, remove the vacuum bag, and take samples of the dewatered sludge for further processing and analysis;

[0025] Step 8: Open the drain valve of the gas-water separator to drain the water from the gas-water separator. The experiment is now complete.

[0026] The present invention has the following beneficial effects: (1) The present invention is the first to couple double-sided vacuum negative pressure, top loading and heating to accelerate the rapid dewatering of sludge or sludge, which provides convenience for the development of the theory of bidirectional dewatering and consolidation of sludge under temperature load; firstly, double-sided vacuum negative pressure is used for dewatering to reduce the water content of sludge. When the vacuum negative pressure makes it difficult for the sludge to continue dewatering, a heating device and a loading device are used for deep dewatering, which reduces the damage to the loading device and improves the dewatering efficiency of sludge.

[0027] (2) The bottom vacuum combined loading sludge double-sided rapid dewatering treatment in this invention adopts a loading device that can control the pressurization speed and pressurization magnitude, which can make the pressurizing screw adjust the position of the pressurizing top cover in a timely manner according to the dissipation of the excess pore water pressure during the sludge dewatering process, so that the sludge is always under a certain external load for double-sided dewatering.

[0028] (3) The present invention uses a water bath heating device to get rid of the constraints of traditional direct electric heating of sludge. Instead, it heats the top cover of the model box and conducts heat to the sludge. This makes the upper surface of the sludge more evenly heated and the heat conduction downward more uniform. In addition, since the water temperature can be controlled, the effect of temperature gradient change on sludge dewatering effect can be studied in the experiment.

[0029] (4) In this invention, the solenoid valve controls the magnitude of the vacuum negative pressure of the device. The solenoid valve only opens to compensate for the negative pressure when the negative pressure in the gas-water separator is less than the preset value, which ensures the stability of the single experimental negative pressure environment and also saves electricity.

[0030] (5) The device of the present invention combines the advantages of each, and can effectively solve the problem of clogging in the filtration and drainage system, so that the water content of sludge or sludge is reduced rapidly, reducing the volume and amount of sludge or sludge to be treated. At the same time, the rapid reduction of the water content of sludge or sludge can also reduce the difficulty of subsequent treatment of sludge or sludge. It realizes a composite dewatering method that is simple to operate, has high dewatering efficiency, good economic benefits, and low dewatering cost. At the same time, it studies theoretical issues such as multi-field coupling in the sludge dewatering process.

[0031] (6) The device of the present invention can be pre-set with multiple drainage base plates in the embodiments, and the influence of different boundary conditions on sludge drainage consolidation can be studied by changing the base plates.

[0032] (7) All experimental data are recorded on the computer software via data cable, which completely avoids human observation errors and greatly saves experimental time; the integration of the experimental system and software makes it possible to control the experiment through the computer, greatly improving the degree of automation. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the vacuum temperature load multi-field coupling test system of the present invention;

[0034] Figure 2 This is a schematic diagram of the heating device in this invention;

[0035] Figure 3 This is a schematic diagram of the structure of the model box top cover in this invention;

[0036] Figure 4 This is a schematic diagram of the model box structure in this invention;

[0037] Figure 5 This is a schematic diagram of the model box structure in this invention;

[0038] Figure 6 This is a schematic diagram showing the distribution of the vacuum negative pressure sensor, temperature sensor B, or pore pressure sensor in this invention;

[0039] Figure 7 This is a schematic diagram of the loading device structure in this invention;

[0040] Figure 8 This is a schematic diagram of the structure of the loading device bracket in this invention;

[0041] Figure 9 This is a schematic diagram of the gas-water separator in this invention;

[0042] Figure 10 This is a schematic diagram of the data acquisition device in this invention;

[0043] Figure 11 This is a schematic diagram of the structure of the vacuum pump and the vacuum negative pressure filtration hose in this invention.

[0044] The components include: 1. Heating device; 11. Circulating water pump; 12. Hot water pipe; 13. Cold water pipe; 14. Water tank; 141. Water tank top opening valve; 142. Heating device switch; 143. Temperature adjustment knob; 144. Temperature display screen; 15. Model box top cover; 151. Top cover upper plate; 1511. Top loading device connector; 1512. Hot water inlet connector; 1513. Cold water outlet connector; 1514. Top cover upper plate screw hole; 1515. Top loading device connector fixing bolt; 1516. Hose threaded connector; 1517. Circulating water hose; 152. Top cover lower plate; 1521. Water flow groove; 1522. Hot water inlet; 1523. Cold water outlet; 1524. Top cover lower plate screw hole; 16. Heating device power supply; 17. Drain pipe;

[0045] 2. Loading device; 21. Top loading rangefinder; 211. Rangefinder rod; 212. Top cover contact point; 22. Top loading device; 221. Pressure screw; 222. Stepper motor; 223. Pressure sensor;

[0046] 3. Model box; 31. Base; 311. Lower drainage hole; 312. Lower drainage valve; 32. Sludge tank; 33. Drainage base plate; 331. Upper drainage hole; 332. Drainage base plate bracket; 34. Upper drainage device; 35. Vacuum negative pressure sensor; 36. Temperature sensor B; 37. Pore pressure sensor; 38. Elevated layer;

[0047] 4. Gas-liquid separator; 41. Weighing scale; 42. Weighing scale display; 43. Housing; 431. Atmospheric pressure connection port cover; 432. Solenoid valve; 433. Vacuum gauge; 44. Three-way valve; 441. Upper drain pipe; 442. Lower drain pipe; 45. Gas-liquid separator drain port; 46. Gas-liquid separator drain valve; 47. Vacuum pump; 471. Vacuum filtration tube adapter; 472. Fastening ring; 48. Vacuum negative pressure filtration hose;

[0048] 5. Data acquisition unit; 51. Conversion button; 52. Negative pressure increase button; 53. Negative pressure decrease button; 54. Vacuum negative pressure value display screen; 55. USB interface; 57. Data aggregation and transmission cable;

[0049] 6. Permeable geotextile; 7. Sludge; 8. Vacuum bag; 81. Stirrup; 82. Stirrup ring; 83. Vacuum bag sealing ring; 84. Vacuum bag sealing stud; 85. Vacuum bag sealing nut;

[0050] 9. Loading device bracket; 91. Loading device platform; 92. Column; 93. Base plate; 94. Casters; 95. Model box moving slide rail. Implementation

[0051] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0052] A vacuum temperature load multi-field coupling test system includes a heating device 1, a loading device 2, a model box 3, a gas-water separator 4, and a data acquisition instrument 5. The model box 3 contains the sludge 7 used in the experiment and serves as a container for the rapid dewatering experiment of the sludge 7. The heating device 1 is responsible for injecting hot water into the top cover 15 of the model box and changing the temperature of the sludge 7. The loading device 2 is responsible for squeezing and draining the sludge 7 to remove more water. The gas-water separator 4 is responsible for collecting the water discharged from the sludge 7, collecting the real-time drainage volume, and providing the vacuum negative pressure required by the system. The data acquisition instrument 5 collects the data generated by various sensors in the system and adjusts the vacuum negative pressure setpoint.

[0053] During the experiment, the edges of the permeable geotextile were first firmly attached to the inner wall of the sludge tank with sealant. The sludge was placed on the permeable geotextile, and three vacuum negative pressure sensors, three temperature sensors (B), and three pore pressure sensors were arranged at the top, middle, and bottom, respectively. Then, a vacuum bag was placed in the sludge tank and fitted with a vacuum bag sealing ring. The top cover of the model box was then placed inside the model box. When placing the vacuum bag, it was ensured that the vacuum bag could extend within the sludge tank to prevent damage when the top cover of the model box was lowered vertically. The maximum and minimum values ​​of the vacuum negative pressure were set on the data acquisition instrument. The upper drainage device and lower drainage valve of the model box were closed, and the atmospheric connection valve (atmospheric pressure connection port cover) of the air-water separator was closed. The vacuum pump was turned on, and the operation program began. Each sensor started automatically recording data. The upper drainage device and lower drainage valve of the model box were turned on, and vacuum negative pressure dewatering began. When vacuum negative pressure dewatering made it difficult for the sludge to continue dewatering, the heating device and loading device were turned on to conduct a deep dewatering experiment until dewatering was completed.

[0054] The heating device 1 includes a circulating water pump 11, a hot water pipe 12, a cold water pipe 13, a water tank 14, a water tank top opening valve 141, a heating device switch 142, a temperature adjustment knob 143, a temperature display screen 144, a heating device power supply 16, and a model box top cover 15.

[0055] Water tank 14 is connected to circulating water pump 11. Hot water pipe 12 and cold water pipe 13 are both connected to water tank 14. Circulating water pump 11 draws hot water from water tank 14 and pumps it to the top cover 15 of model box through hot water pipe 12. In the experiment, the top cover 15 of model box is placed on the sludge 7 in model box 3 to transfer the temperature to the sludge 7. Circulating water pump 11 draws out the cooled water in the top cover 15 of model box through cold water pipe 13 and pumps it back to water tank 14 for reheating, so as to achieve continuous heat transfer to the sludge.

[0056] The water tank 14 is equipped with a heating wire and a temperature sensor A. The temperature is adjusted by the temperature adjustment knob 143 and the water temperature value is displayed on the temperature display 144. The heating device 1 is powered by the heating device power supply 16. The valve 141 on the top of the water tank controls the operation of the circulating water pump 11. The heating device switch 142 controls the heating of the water in the water tank 14. The heating device is equipped with a drain pipe 17 for easy replacement of the water in the water tank 14. The heating device has a built-in chip that sets the maximum temperature to 60℃. The vacuum sealing bag is made of polyethylene. Excessive temperature can easily damage the sealing bag and impair the system's airtightness. Water will not boil and vaporize at near 100℃ when the pressure is less than one atmosphere. Setting the temperature too high is unnecessary, saving energy and avoiding scalding from excessive temperature.

[0057] The model box top cover 15 has a circular structure. The model box top cover 15 is connected to the hot water pipe 12 and the cold water pipe 13 by a circulating water hose 1517. The model box top cover 15 includes an upper top cover plate 151, a lower top cover plate 152, a top loading device connector 1511, a hot water inlet connector 1512, and a cold water outlet connector 1513. The upper top cover plate 151 and the lower top cover plate 152 are detachably connected. The upper top cover plate 151 has four upper top cover plate screw holes 1514, and the lower top cover plate has upper top cover plate screw holes 1524 corresponding to the upper top cover plate screw holes 1514. The upper top cover plate 151 and the lower top cover plate 152 are connected by fixing bolts. To prevent the circulating water inside from overflowing, quick-drying sealant is applied to the edge of the joint surface between the upper top cover plate and the lower top cover plate for sealing.

[0058] The top loading device connector 1511, hot water inlet connector 1512, and cold water outlet connector 1513 are respectively located on the upper surface of the top cover plate 151. The top loading device connector 1511 is fixed to the top cover plate 151 by the top loading device connector fixing bolt 1515. The top cover 15 of the model box is connected to the pressure screw 221 of the top loading device 22 of the loading device 2 through the top loading device connector 1511. The top loading device connector 1511 is located in the circular position of the top cover plate 151. The ends of the hot water inlet connector 1512 and the cold water outlet connector 1513 are both provided with internal threads. One end of the two circulating water hoses 1517 is connected to the hose thread connector 1516 and is respectively connected to the internal threads of the hot water inlet connector 1513 and the cold water outlet connector 1513. The other ends of the two circulating water hoses 1517 are respectively connected to the hot water pipe 12 and the cold water pipe 13 of the heating device 1.

[0059] The lower plate 152 of the top cover is provided with an S-shaped water flow groove 1521. One end of the water flow groove 1521 is a hot water inlet 1522 and corresponds to a hot water inlet connector 1512. The other end of the water flow groove 1521 is a cold water outlet 1523 and corresponds to a cold water outlet connector 1513. The lower plate 152 of the top cover is provided with a temperature sensor probe and is connected to the data acquisition instrument 5 to record the water temperature in the water flow groove 1521 in real time.

[0060] One end of the hot water inlet connector 1512 is connected to the hot water pipe 12, and the other end of the hot water inlet connector 1512 passes through the top cover plate 151 and is connected to the hot water inlet 1522. One end of the cold water inlet connector 1513 is connected to the cold water pipe 13, and the other end of the cold water inlet connector 1513 passes through the top cover plate 151 and is connected to the cold water outlet 1523.

[0061] The loading device 2 includes a top loading rangefinder 21 and a top loading device 22. The top loading device 22 is equipped with a pressure screw 221. The lower end of the pressure screw 221 is equipped with a stepper motor 222 and a pressure sensor 223 in sequence and is connected to the top loading device connector 1511 of the top cover 15 of the model box. The stepper motor 222 drives the pressure screw 221 to move vertically up and down in the top loading device 22. Both the stepper motor 222 and the pressure sensor 223 are connected to the data acquisition instrument 5. The data acquisition instrument 5 applies pressure to the sludge by controlling the stepper motor 222. The pressure sensor 223 transmits the pressure magnitude to the data acquisition instrument 5 in real time.

[0062] The top loading rangefinder 21 is equipped with a rangefinder rod 211. The rangefinder rod 211 moves vertically up and down inside the top loading rangefinder 21. The bottom end of the rangefinder rod 211 is equipped with a top cover contact point 212 that contacts the top cover 15 of the model. The top cover contact point 212 is connected to the data acquisition instrument 5 through a data cable to record the descent distance and speed of the top cover 15 of the model box in real time.

[0063] The distance the top cover of the model box descends is the amount of sludge settling. During the experiment, the top loading device applies pressure to the sludge in two modes under the control of the data acquisition instrument: one is constant pressure and the other is constant speed.

[0064] Constant pressure: By setting a constant pressure on the data acquisition unit, the stepper motor speed is controlled to lower the pressure screw to apply pressure to the sludge. During this process, the speed of the pressure screw changes, but the pressure applied to the sludge remains constant. Constant speed: By setting a constant speed on the data acquisition unit, the stepper motor speed is controlled to lower the pressure screw to apply pressure to the sludge. During this process, the pressure on the sludge changes, but the descent speed of the pressure screw remains constant. In constant pressure or constant speed mode, the model box top cover descends, and the distance it descends also lowers, which represents the amount of sludge settling.

[0065] Model box 3 is cylindrical and includes a base 31, a sludge tank 32, a drainage base plate 33, a vacuum bag fixing device, an upper drainage device 34, and a lower drainage valve 312; the sludge tank 32 is made of transparent acrylic material.

[0066] The base 31 has a groove, and the bottom of the sludge tank 32 is connected to the base 31 through the groove and secured with sealant. A hoop 81 is provided on the outside of the sludge tank 32, and the bottom of the hoop 81 is connected to the base 31. The vacuum bag fixing device includes a hoop ring 82 and a vacuum bag sealing ring 83. The hoop ring 82 is located on the top of the model box 3, and the vacuum bag sealing ring 83 is detachably connected to the hoop ring 82. The top of the hoop 81 passes through the hoop ring 82, and the hoop ring 82 ensures that the side wall of the model box is firmly attached to the base 31. The connection is firm and airtight, and mud-free; the top of the hoop 81 passing through the hoop ring 82 is provided with a threaded vacuum bag sealing stud 84. When sealing, first insert the vacuum bag 8 into the model box 3, then let the edge of the vacuum bag 8 cover the vacuum bag sealing stud 84, cover it with the vacuum bag sealing ring 83, the vacuum bag sealing ring 83 is provided with a hole corresponding to the vacuum bag sealing stud 84, and finally tighten the vacuum bag sealing nut 85 and the vacuum bag sealing stud 84 to complete the sealing of the vacuum bag 8.

[0067] The drainage base plate 33 is located inside the sludge tank 32, and an open layer 38 is formed between the drainage base plate 33 and the base 31. The drainage base plate 33 is provided with N upper drainage holes 331, N≥10. The upper surface of the base 31 is provided with a drainage base plate bracket 332 for supporting the drainage base plate 33. The upper surface of the base 31 is provided with a lower drainage hole 311. The interior of the base 31 is provided with a drainage channel, which is connected to a lower drainage valve 312. The lower drainage hole 311, the drainage channel, and the lower drainage valve 312 are interconnected. The lower drainage valve 312 is connected to the lower drainage pipe 442 of the gas-water separator 4.

[0068] During the experiment, a permeable geotextile 6 was placed on the upper surface of the drainage base plate 33 as an infiltration layer. Above the permeable geotextile 6 was a sludge holding layer. The sludge 7 was placed on the permeable geotextile 6. The water removed from the sludge seeped into the overhead layer 38 and was then pumped out by the internal air-water separator 4. A vacuum bag 8 was provided in the sludge box 32. The vacuum bag 8 was located above the sludge 7, and the opening of the vacuum bag 8 was sealed by a vacuum bag fixing device.

[0069] The lower drainage refers to the sludge being drained through the permeable geotextile and drainage base plate into the overhead layer. The upper drainage refers to the sludge being dewatered through the upper drainage device inside the sludge. The upper drainage device is equipped with an upper drainage filter element to filter the sludge.

[0070] One cm above the drainage base plate 33, an upper drainage device 34, a vacuum negative pressure sensor 35, a temperature sensor B 36, and a pore pressure sensor 37 are respectively installed on the outer wall of the sludge tank. The inlet of the upper drainage device 34 is located in the sludge, and the outlet of the upper drainage device 34 is connected to the upper drainage pipe 441 of the gas-liquid separator 4 to drain the water in the sludge 7. The vacuum negative pressure sensor 35, the temperature sensor B 36, and the pore pressure sensor 37 are all connected to the data acquisition instrument 5. The data collected by the vacuum sensor can not only be transmitted to the data acquisition instrument, but also has a vacuum degree electronic display, which can read the vacuum degree value in real time.

[0071] There are three vacuum negative pressure sensors 35, three temperature sensors B 36, and three pore pressure sensors 37. The vacuum probe of one vacuum negative pressure sensor, the temperature probe of temperature sensor B, and the pore water pressure gauge of pore pressure sensor are distributed in the middle of sludge 7. The vacuum probe of one vacuum negative pressure sensor, the temperature probe of temperature sensor B, and the pore water pressure gauge of pore pressure sensor are distributed at the upper end of sludge 7. The vacuum probe of another vacuum negative pressure sensor, the temperature probe of temperature sensor B, and the pore water pressure gauge of pore pressure sensor B are distributed at the lower end of sludge 7.

[0072] The gas-liquid separation device 4 includes a weighing scale 41, a weighing scale display 42, a housing 43, an atmospheric pressure connection port cover 431, a solenoid valve 432, a vacuum gauge 433, and a vacuum pump 47; the housing 43 is made of transparent acrylic material.

[0073] The weighing scale 41 is located at the bottom of the housing 43. The weighing scale 41 is connected to the weighing scale display 42. The weighing scale is responsible for recording the weight of the sludge discharge water and is connected to the data acquisition instrument 5. The atmospheric pressure connection port cover 431, the solenoid valve 432, and the vacuum gauge 433 are all located at the top of the housing 43. The atmospheric pressure connection port cover 431 is bolted to the top of the housing 43.

[0074] The side wall of the housing 43 is provided with a three-way valve 44. The three-way valve 44 is provided with an upper drain pipe 441 and a lower drain pipe 442. One end of the three-way valve 44 is connected to the side wall of the housing 43, one end is connected to the upper drain pipe 441, and the other end is connected to the lower drain pipe 442. The upper drain pipe 441 is connected to the upper drain device 34 of the model box 3, and the lower drain pipe 442 is connected to the lower drain valve 312 of the model box 3. One end of the solenoid valve 432 is connected to the top of the housing 43, and the other end of the solenoid valve 432 is connected to the vacuum pump 47 through the vacuum negative pressure suction hose 48.

[0075] Solenoid valve 432 is equipped with a negative pressure probe. Solenoid valve 432 is connected to data acquisition instrument 5. When the negative pressure in the gas-water separator reaches the set value, solenoid valve 432 automatically closes. When the negative pressure is insufficient, solenoid valve 432 automatically opens to compensate.

[0076] The bottom of the gas-water separator 3 is provided with a gas-water separator drain port 45, which is connected to a gas-water separator drain valve 46. After the experiment, drainage and subsequent cleaning work are carried out through the gas-water separator drain port 45 and the gas-water separator drain valve 46.

[0077] The vacuum negative pressure filtration hose 48 is connected to the vacuum pump 47 via the vacuum filtration tube converter 471 and the fastening ring 472.

[0078] The data acquisition unit 5 is equipped with a maximum and minimum negative pressure value conversion button 51, a negative pressure increase button 52, and a negative pressure decrease button 53. The maximum and minimum negative pressure value conversion button 51 is used to switch between the maximum and minimum negative pressure values. The vacuum negative pressure value display screen 54 displays the real-time adjustment of the negative pressure. The data acquisition unit 5 is powered by a power cord 56 and connected to a computer via a USB interface. The data aggregation and transmission lines connect to the sensors inside the device to receive data from the entire device. Except for the temperature sensor A in the water tank of the heating device, all data from the other devices are aggregated by the data acquisition unit and displayed on the computer via the USB interface and the accompanying software. The data includes the temperature sensor data in the top cover of the model box, the pressure sensor data on the top loading device, the sludge settling amount detected by the distance measuring rod, the vacuum degree probe of the three vacuum negative pressure sensors in the sludge, the temperature probe of the three temperature sensors B, the pore water pressure gauge data of the three pore pressure sensors, the vacuum negative pressure value at the solenoid valve, and the sludge drainage amount at the weighing scale. On the computer software connected via the USB interface of the data acquisition instrument 5, you can set the loading pressure and speed of the top loading device, set start or pause, and read and plot all the data collected by the data acquisition instrument.

[0079] The pressure screw 221, stepper motor 222, top loading rangefinder 21, and model box 3 of the loading device 2 are all mounted on the loading device support 9. The loading device support 9 includes a loading device platform 91, a column 92, and a base plate 93. The loading device platform 91 is connected to the base plate 93 through the column 92. The loading device platform 91 and the column 92 support the loading device. The loading device platform 91 has a through hole so that the pressure screw 221 can smoothly extend into the top cover 15 of the model box 3. The top of the base plate 93 has two parallel model box moving slide rails 95. The bottom of the model box 3 is slidably connected to the base plate 93 through the model box moving slide rails 95. This facilitates the model box to be pulled out from the loading device support, loaded with sludge, and covered with a vacuum bag. The bottom of the base plate 93 has casters 94 to facilitate the movement of the model box and the loading device support.

[0080] The method for using the vacuum temperature load multi-field coupling test system is as follows:

[0081] Step 1: Cut the permeable geotextile to the size of the inner diameter of the model box, place it on the drainage base plate, and use sealant to firmly attach the edges of the permeable geotextile to the inner wall of the sludge box, ensuring that no sludge leaks from the edges of the drainage base plate; place the sludge on the permeable geotextile; wrap the vacuum probe of the vacuum negative pressure sensor, the temperature probe of temperature sensor B, and the pore water pressure gauge of the pore pressure sensor with geotextile, making sure that sludge particles cannot enter the probes;

[0082] Step 2: Distribute three vacuum negative pressure sensors, three temperature sensors, and three pore pressure sensors at the top, middle, and bottom of the sludge, respectively, so that one set of sensors measures parameters near the top of the sludge, one set measures parameters near the middle of the sludge, and one set measures parameters near the bottom of the sludge; then place the vacuum bag into the sludge tank and seal the top of the vacuum bag with the vacuum bag fixing device; finally, place the top cover of the model box into the sludge tank.

[0083] Step 3: Set the maximum and minimum values ​​of the vacuum negative pressure on the data acquisition instrument; for example, if a negative pressure of -80 kPa is required, the minimum negative pressure should be set to -80 kPa and the maximum negative pressure to -79 kPa. If both are set to the same negative pressure value, the vacuum compensation solenoid valve will start as soon as the air pressure changes slightly, which will greatly reduce the life of the solenoid valve.

[0084] Step 4: Close the upper drainage device and lower drainage valve of the model box, close the atmospheric pressure connection port cover of the gas-water separator, turn on the vacuum pump, and first evacuate the vacuum in the gas-water separator to the experimental preset value.

[0085] Step 5: Connect the data acquisition instrument to the computer software, set the time interval for each sensor to record data, and click the Start Experiment button. Each sensor will then start recording data automatically. Open the upper drainage device and lower drainage valve of the model box, turn on the vacuum pump, and vacuum dehydration will begin.

[0086] Step Six: When the data on the scale display of the air-water separator remains unchanged for a period of time, indicating that the vacuum negative pressure dewatering makes it difficult for the sludge to continue deep dewatering, start the loading device, set the top loading pressure or loading speed, turn on the heating device, and set the heating water temperature. Use the loading device to pressurize and the heating device to heat the sludge to continue dewatering. After 24 hours, click to stop the experiment. After the dewatering experiment is completed, turn off the vacuum pump, heating device, and loading device, and open the atmospheric pressure connection port cover of the air-water separator.

[0087] Step 7: Use computer software to reset the loading device, remove the top cover of the model box, remove the vacuum bag, and take samples of the dewatered sludge for further processing and analysis.

[0088] Step 8: Open the drain valve of the air-water separator to drain the water from the separator and clean the model box. Remove the air-water separator and the sensors contaminated with sludge. The experiment is now complete.

[0089] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. However, the above description is merely a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other embodiments derived by those skilled in the art without departing from the technical solution of the present invention should be covered within the patent scope of the present invention.

Claims

1. A vacuum temperature load multi-field coupled test system, characterized in that, The system includes a heating device (1), a loading device (2), a model box (3), an air-water separator (4), and a data acquisition instrument (5). The model box (3) contains the sludge (7) used in the experiment and serves as the container for the rapid dewatering experiment of the sludge (7). The heating device (1) heats the top cover of the model box, causing the upper surface of the sludge to be heated, thus changing the temperature of the sludge (7). The loading device (2) is responsible for squeezing and draining the sludge, and can record the descent distance and speed of the top cover of the model box in real time. The air-water separator (4) is connected to the model box (3) and is responsible for collecting the water discharged from the sludge and collecting the real-time drainage volume and... Provide the vacuum negative pressure required by the system; the heating device (1), loading device (2), model box (3), and gas-water separator (4) are respectively connected to the data acquisition instrument (5). The data acquisition instrument (5) collects the data generated by the system and adjusts the vacuum negative pressure setting value. The data collected by the system includes the temperature sensor data in the top cover of the model box, the pressure sensor data and sludge settling amount in the loading device, the vacuum degree probe of the vacuum negative pressure sensor in the sludge, the temperature probe of the temperature sensor B and the pore water pressure gauge of the pore pressure sensor, the vacuum negative pressure value of the gas-water separator (4) and the sludge drainage amount; The model box (3) includes a base (31), a sludge box (32), a drainage bottom plate (33), a vacuum bag fixing device, an upper drainage device (34), and a lower drainage valve (312). The base (31) is provided with a groove, and the bottom of the sludge tank (32) is connected to the base (31) through the groove. The drainage bottom plate (33) is located inside the sludge tank (32), and an open layer (38) is formed between the drainage bottom plate (33) and the base (31). The drainage base plate (33) is provided with N upper drainage holes (331), N≥10. The upper surface of the base (31) is provided with lower drainage holes (311). The interior of the base (31) is provided with a drainage channel. The drainage channel is connected to the lower drainage valve (312). The lower drainage holes (311), drainage channel, and lower drainage valve (312) are interconnected. The lower drainage valve (312) is connected to the gas-water separator (4). The upper surface of the drainage base plate (33) is provided with a permeable geotextile (6), and above the permeable geotextile (6) is a sludge holding layer. The sludge box (32) is provided with a vacuum bag (8), which is located above the sludge (7). The opening of the vacuum bag (8) is sealed by a vacuum bag fixing device. The sludge tank (32) is equipped with an upper drainage device (34), a vacuum negative pressure sensor (35), a temperature sensor B (36), and a pore pressure sensor (37) on its side wall. The inlet of the upper drainage device (34) is located in the sludge, and the outlet of the upper drainage device (34) is connected to the gas-water separator (4) to discharge the water in the sludge (7). The vacuum negative pressure sensor (35), the temperature sensor B (36), and the pore pressure sensor (37) are all connected to the data acquisition instrument (5).

2. The vacuum temperature load multi-field coupling test system according to claim 1, characterized in that, The heating device (1) includes a circulating water pump (11), a hot water pipe (12), a cold water pipe (13), a water tank (14), a water tank top opening valve (141), a heating device switch (142), a temperature adjustment knob (143), a temperature display screen (144), a heating device power supply (16), and a model box top cover (15). The water tank (14) is connected to the circulating water pump (11). The circulating water pump (11) extracts the hot water from the water tank (14) and pumps it into the top cover (15) of the model box through the hot water pipe (12). The top cover (15) of the model box is placed on the sludge (7) in the model box (3) and transfers the temperature to the sludge (7). The circulating water pump (11) extracts the cold water in the top cover (15) of the model box through the cold water pipe (13) and pumps it back into the water tank (14) for heating. The water tank (14) is equipped with a heating wire and a temperature sensor A. The temperature is adjusted by the temperature adjustment knob (143) and the water temperature value is displayed on the temperature display (144). The heating device (1) is powered on by the heating device power supply (16). The valve (141) at the top of the water tank controls the operation of the circulating water pump (11). The water in the water tank (14) is heated by the heating device switch (142).

3. The vacuum temperature load multi-field coupling test system according to claim 2, characterized in that, The model box top cover (15) includes an upper top cover plate (151), a lower top cover plate (152), a top loading device connector (1511), a hot water inlet connector (1512), and a cold water outlet connector (1513); the upper top cover plate (151) and the lower top cover plate (152) are detachably connected. The top loading device connector (1511), hot water inlet connector (1512) and cold water outlet connector (1513) are respectively set on the upper surface of the top cover plate (151), and the top cover (15) of the model box is connected to the loading device (2) through the top loading device connector (1511). The lower plate (152) of the top cover is provided with an S-shaped water flow groove (1521). One end of the water flow groove (1521) is a hot water inlet (1522) and corresponds to a hot water inlet connector (1512). The other end of the water flow groove (1521) is a cold water outlet (1523) and corresponds to a cold water outlet connector (1513). The lower plate (152) of the top cover is provided with a temperature sensor probe and is connected to a data acquisition instrument (5) to record the water temperature in the water flow groove (1521) in real time. One end of the hot water inlet connector (1512) is connected to the hot water pipe (12), and the other end of the hot water inlet connector (1512) passes through the top cover plate (151) and is connected to the hot water inlet (1522). One end of the cold water inlet connector (1513) is connected to the cold water pipe (13), and the other end of the cold water inlet connector (1513) passes through the top cover plate (151) and is connected to the cold water outlet (1523).

4. The vacuum temperature load multi-field coupling test system according to claim 2, characterized in that, The loading device (2) includes a top loading rangefinder (21) and a top loading device (22); The top loading device (22) is equipped with a pressure screw (221). The lower end of the pressure screw (221) is equipped with a stepper motor (222) and a pressure sensor (223) and is connected to the top cover (15) of the model box. The stepper motor (222) drives the pressure screw (221) to move vertically up and down in the top loading device (22). Both the stepper motor (222) and the pressure sensor (223) are connected to the data acquisition instrument (5). The data acquisition instrument (5) applies pressure to the sludge by controlling the stepper motor (222). The pressure sensor (223) transmits the pressure magnitude to the data acquisition instrument (5) in real time. The top-loaded rangefinder (21) is equipped with a rangefinder rod (211). The rangefinder rod (211) moves vertically up and down inside the top-loaded rangefinder (21). The bottom end of the rangefinder rod (211) is equipped with a top cover contact point (212) and contacts the top cover (15) of the model box. The top cover contact point (212) is connected to the data acquisition instrument (5) through a data cable to record the descent distance and speed of the top cover (15) of the model box in real time.

5. The vacuum temperature load multi-field coupling test system according to claim 1, characterized in that, The sludge box (32) is provided with a hoop (81) on the outside. The bottom of the hoop (81) is connected to the base (31). The vacuum bag fixing device includes a hoop ring (82) and a vacuum bag sealing ring (83). The hoop ring (82) is set on the top of the model box (3). The vacuum bag sealing ring (83) is detachably connected to the hoop ring (82).

6. The vacuum temperature load multi-field coupling test system according to claim 1, characterized in that, The vacuum negative pressure sensor (35), temperature sensor B (36), and pore pressure sensor (37) are each in three parts. The vacuum probe of one vacuum negative pressure sensor, the temperature probe of temperature sensor B, and the pore water pressure gauge of pore pressure sensor are respectively distributed in the middle of the sludge (7). The vacuum probe of the other two vacuum negative pressure sensors, the temperature probe of temperature sensor B, and the pore water pressure gauge of pore pressure sensor are respectively distributed at the upper and lower ends of the sludge (7).

7. The vacuum temperature load multi-field coupling test system according to claim 1, characterized in that, The gas-water separator (4) includes a scale (41), a scale display (42), a housing (43), an atmospheric pressure connection port cover (431), a solenoid valve (432), a vacuum gauge (433), and a vacuum pump (47). The weighing scale (41) is located at the bottom of the housing (43), and is connected to the weighing scale display (42) and the data acquisition instrument (5). The atmospheric pressure port cover (431), the solenoid valve (432), and the vacuum gauge (433) are all located at the top of the housing (43). The side wall of the housing (43) is provided with a three-way valve (44). The three-way valve (44) is provided with an upper drain pipe (441) and a lower drain pipe (442). The upper drain pipe (441) and the lower drain pipe (442) are both connected to the model box (3). One end of the solenoid valve (432) is connected to the top of the housing (43), and the other end of the solenoid valve (432) is connected to the vacuum pump (47). The solenoid valve (432) is equipped with a negative pressure probe and is connected to the data acquisition instrument (5).

8. The vacuum temperature load multi-field coupling test system according to claim 1, characterized in that, The loading device (2) and the model box (3) are both mounted on the loading device support (9). The loading device support (9) includes a loading device platform (91), a column (92), and a base plate (93). The loading device platform (91) is connected to the base plate (93) through the column (92). The loading device platform (91) and the column (92) support the loading device. The loading device platform (91) has a through hole. The top of the base plate (93) has two parallel model box moving slide rails (95). The bottom of the model box (3) is slidably connected to the base plate (93) through the model box moving slide rails (95). The bottom of the base plate (93) has casters (94).

9. The method of using the vacuum temperature load multi-field coupling test system according to any one of claims 1-8, characterized in that, The method is as follows: Step 1: Place the permeable geotextile on the drainage base plate and use sealant to firmly attach the edges of the permeable geotextile to the inner wall of the sludge tank; then place the sludge on the permeable geotextile. Step 2: Distribute the three vacuum negative pressure sensors, three temperature sensors, and three pore pressure sensors at the top, middle, and bottom positions of the sludge, respectively; then place the vacuum bag into the sludge tank and seal the top of the vacuum bag with the vacuum bag fixing device; finally, place the top cover of the model box into the sludge tank. Step 3: Set the maximum and minimum values ​​of the vacuum negative pressure on the data acquisition instrument; Step 4: Close the upper drainage device and lower drainage valve of the model box, close the atmospheric pressure connection port cover of the gas-water separator, turn on the vacuum pump, and first evacuate the vacuum in the gas-water separator to the experimental preset value. Step 5: Open the upper drainage device and lower drainage valve of the model box, turn on the vacuum pump, and vacuum negative pressure dehydration begins; Step Six: When the data on the scale display of the air-water separator remains unchanged for a period of time, that is, when the vacuum negative pressure dewatering makes it difficult for the sludge to continue deep dewatering, start the loading device and turn on the heating device. Use the loading device to pressurize and the heating device to heat the sludge to continue dewatering. After the dehydration experiment is completed, turn off the vacuum pump, heating device, and loading device, and open the atmospheric pressure connection port cover of the gas-water separator; Step 7: Reset the loading device, remove the top cover of the model box, remove the vacuum bag, and take samples of the dewatered sludge for further processing and analysis; Step 8: Open the drain valve of the gas-water separator to drain the water from the gas-water separator. The experiment is now complete.

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