Cooling temperature control system and process for distillation recovery of waste lubricating oil

Abstract

The application discloses a cooling temperature control system and process for waste lubricating oil distillation recovery, relates to the technical field of waste oil recovery, and solves the problem that the cooling temperature control system for waste lubricating oil distillation recovery usually adopts simple on-off control of cooling water flow, and constant temperature condensation is difficult to realize due to the simple control mode, which leads to uneven quality of recovered oil products, and overcooling or insufficient cooling is prone to occur, thereby causing energy waste. The application discloses a cooling temperature control system and process for waste lubricating oil distillation recovery, which comprises a distillation tower, an oil storage tank and a cooling temperature control system, and the cooling temperature control system is connected between the distillation tower and the oil storage tank. By adopting closed-loop control of the oil outlet temperature as a main controlled variable and combining a PID algorithm, the application can quickly respond to changes in oil gas temperature and flow, stabilize the oil outlet temperature within the lowest threshold and the highest threshold, improve the uniformity and quality of the recovered oil products, and has good oil outlet stability.

Description

Technical Field

[0001] This invention relates to the field of waste oil recycling, specifically to a cooling temperature control system and process for the distillation and recycling of waste lubricating oil. Background Technology

[0002] The recycling and regeneration of waste lubricating oil is of great significance for environmental protection and resource recycling. Distillation is a key step in the regeneration process of waste lubricating oil. Different fractions in the oil are vaporized by heating and then cooled and recovered by condenser. In this process, temperature control in the condensation and cooling stage is crucial.

[0003] Existing cooling temperature control systems for waste lubricating oil distillation and recovery typically use simple on / off switches to control cooling water flow. This simplistic control method often fails to achieve constant-temperature condensation, leading to uneven quality of the recovered oil and potential overcooling or undercooling, resulting in energy waste. Therefore, these systems do not meet current requirements. To address this, we propose a cooling temperature control system and process for waste lubricating oil distillation and recovery. Summary of the Invention

[0004] The purpose of this invention is to provide a cooling temperature control system and process for the distillation and recovery of waste lubricating oil, in order to solve the problems mentioned in the background art, where the cooling temperature control system for the distillation and recovery of waste lubricating oil usually adopts a simple switch to control the cooling water flow. Due to the simple control method, it is often difficult to achieve constant temperature condensation, resulting in uneven quality of the recovered oil and easy over-cooling or under-cooling, causing energy waste.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a cooling temperature control system for waste lubricating oil distillation and recovery, comprising a distillation tower, an oil storage tank, and a cooling temperature control system, wherein the cooling temperature control system is connected between the distillation tower and the oil storage tank, and includes: A condenser, the input end of which is connected to the oil and gas outlet of the distillation column, the output end of which is connected to the oil inlet of the oil storage tank, and the tube side of which is connected to the cooling module; The cooling module includes a cooling medium storage tank, a variable frequency pump, a three-way solenoid valve, and a condenser tube side connected in sequence by pipes to form a circulation. The three-way solenoid valve includes an inlet, a first outlet, and a second outlet. The inlet of the cooling medium storage tank is connected to the output port of the variable frequency pump. The first outlet of the three-way solenoid valve is connected to the tube side inlet of the condenser. The second outlet of the three-way solenoid valve is connected to the inside of one of the cooling medium storage tanks through a pipe. Temperature sensing module, used to detect temperature parameters of the cooling temperature control system; The refrigeration unit has a spiral coil connected to its output end via a pipeline. The spiral coil is spirally arranged on the pipeline surface of the variable frequency pump inlet. The refrigeration unit is used to rapidly cool the cooling medium inside the cooling medium storage tank.

[0006] Preferably, the temperature sensing module includes an inlet oil temperature detector, an outlet oil temperature detector, and a condensation temperature detector. The inlet oil temperature detector is installed on the surface of the pipe connecting the distillation tower and the condenser, the outlet oil temperature detector is installed on the surface of the pipe connecting the condenser and the oil storage tank, and the condensation temperature detector is installed on the surface of the pipe connecting the condenser and the three-way solenoid valve.

[0007] Preferably, the cooling temperature control system further includes a control unit, which is electrically connected to the temperature sensing module, the refrigeration unit, the variable frequency pump, the three-way solenoid valve and the condenser; The control unit is configured to set a preset threshold for the oil temperature entering the oil storage tank, the preset threshold including a minimum threshold temperature. and highest threshold ; The oil outlet temperature detected by the oil outlet temperature detector As the primary and controlled variable, the operating frequency of the variable frequency pump is adjusted through a preset algorithm; The condensation temperature detected by the real-time monitoring condensation temperature detector To control the start and stop of the refrigeration unit; Based on the oil inlet temperature detected by the oil inlet temperature detector Oil outlet temperature detected by the oil outlet temperature detector The three-way solenoid valve is subjected to composite control to regulate the feed rate of the cooling medium; And when Abnormal temperature, and Unable to stabilize at the lowest threshold and highest threshold During this period, the condenser is started and stopped.

[0008] Preferably, the preset algorithm is a PID algorithm.

[0009] Preferably, the cooling medium is heat transfer oil or an aqueous solution of ethylene glycol.

[0010] A cooling temperature control process for the distillation and recovery of waste lubricating oil includes the following steps: S1: First, set the preset threshold for the oil temperature entering the oil tank in the control unit; S2: Start the distillation column; the oil and gas inside the distillation column enter the condenser through the pipeline. S3: The temperature sensing module monitors the oil inlet temperature at the condenser location in real time. Oil outlet temperature and condensation temperature and transmit the signal to the control unit; S4: The control unit will detect the oil outlet temperature. With minimum threshold and highest threshold The comparison is performed, and two control signals are output through the PID algorithm. One control signal is sent to the three-way solenoid valve to adjust its flow ratio, and the other control signal is sent to the variable frequency pump to adjust its cooling medium delivery rate. The detected condensation temperature is also considered. It monitors and outputs control signals to control the start and stop of the cooling unit; S5: Through the coordinated action of the three-way solenoid valve and the variable frequency pump, the oil outlet temperature at the condenser outlet is increased. Stabilize at the lowest threshold and highest threshold between.

[0011] Preferably, when the distillation stage of the distillation column is switched, the control unit automatically calls the minimum threshold value corresponding to that stage. and highest threshold .

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention employs closed-loop control with oil outlet temperature as the main controlled variable, combined with a PID algorithm, which can quickly respond to changes in oil and gas temperature and flow rate, stabilize the oil outlet temperature within the minimum and maximum thresholds, improve the uniformity and quality of recovered oil, and has good oil outlet stability.

[0013] 2. This invention regulates the flow rate of the cooling medium by using a variable frequency pump to avoid overcooling or undercooling of the oil. Combined with the on-demand start / stop of the control unit, it achieves on-demand energy distribution and significantly reduces system energy consumption. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the cooling temperature control system of the present invention; Figure 2 This is a logic diagram of the cooling temperature control system of the present invention.

[0015] In the diagram: 1. Distillation column; 2. Condenser; 3. Oil storage tank; 4. Three-way solenoid valve; 5. Variable frequency pump; 6. Cooling medium storage tank; 7. Inlet oil temperature detector; 8. Outlet oil temperature detector; 9. Condensation temperature detector; 10. Control unit; 11. Cooling unit. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] Please see Figures 1 to 2 One embodiment of the present invention provides a cooling temperature control system for waste lubricating oil distillation and recovery, comprising a distillation tower 1, an oil storage tank 3, and a cooling temperature control system. The cooling temperature control system is connected between the distillation tower 1 and the oil storage tank 3, and includes: Condenser 2, the input end of condenser 2 is connected to the oil and gas outlet of distillation column 1, the output end of condenser 2 is connected to the oil inlet of oil storage tank 3, and the tube side of condenser 2 is connected to the cooling module. The cooling module includes a cooling medium storage tank 6, a variable frequency pump 5, a three-way solenoid valve 4, and a condenser 2 tube side connected in sequence by pipes to form a circulation. The three-way solenoid valve 4 includes an inlet, a first outlet, and a second outlet. The inlet of the cooling medium storage tank 6 is connected to the output port of the variable frequency pump 5. The first outlet of the three-way solenoid valve 4 is connected to the tube side inlet of the condenser 2. The second outlet of the three-way solenoid valve 4 is connected to the inside of one of the cooling medium storage tanks 6 through a pipe. Temperature sensing module, used to detect temperature parameters of the cooling temperature control system; The refrigeration unit 11 has a spiral coil connected to its output end via a pipeline. The spiral coil is spirally arranged on the pipeline surface of the input port of the variable frequency pump 5. The refrigeration unit 11 is used to rapidly cool the cooling medium inside the cooling medium storage tank 6.

[0018] Preferably, the temperature sensing module includes an inlet oil temperature detector 7, an outlet oil temperature detector 8, and a condensation temperature detector 9. The inlet oil temperature detector 7 is installed on the surface of the pipe connecting the distillation tower 1 and the condenser 2, the outlet oil temperature detector 8 is installed on the surface of the pipe connecting the condenser 2 and the oil storage tank 3, and the condensation temperature detector 9 is installed on the surface of the pipe connecting the condenser 2 and the three-way solenoid valve 4.

[0019] Preferably, the cooling temperature control system also includes a control unit 10, which is electrically connected to the temperature sensing module, the refrigeration unit 11, the variable frequency pump 5, the three-way solenoid valve 4 and the condenser 2. Control unit 10 is configured to set a preset threshold for the oil temperature entering the oil storage tank 3, the preset threshold including a minimum threshold temperature. and highest threshold ; Oil outlet temperature detected by oil outlet temperature detector 8 As the primary and controlled variable, the operating frequency of the variable frequency pump 5 is adjusted through a preset algorithm; The condensation temperature detected by the real-time monitoring condensation temperature detector 9 Start-up and shutdown control of refrigeration unit 11; Based on the oil inlet temperature detected by the oil inlet temperature detector 7 The oil outlet temperature detected by the oil outlet temperature detector 8 The three-way solenoid valve 4 is subjected to composite control to regulate the feed rate of the cooling medium; And when Abnormal temperature, and Unable to stabilize at the lowest threshold and highest threshold During this period, start and stop condenser 2.

[0020] Preferably, the preset algorithm is the PID algorithm.

[0021] Preferably, the cooling medium is heat transfer oil or an aqueous solution of ethylene glycol.

[0022] A cooling temperature control process for the distillation and recovery of waste lubricating oil includes the following steps: S1: First, set the preset threshold for the oil temperature entering the oil storage tank 3 in the control unit 10; S2: Start distillation column 1. The oil and gas inside distillation column 1 enter the condenser 2 through the pipeline. S3: The temperature sensing module monitors the oil inlet temperature at position 2 of the condenser in real time. Oil outlet temperature and condensation temperature and transmit the signal to control unit 10; S4: Control unit 10 will detect the oil outlet temperature With minimum threshold and highest threshold The comparison is performed, and two control signals are output through the PID algorithm. One control signal is sent to the three-way solenoid valve 4 to adjust its flow ratio, and the other control signal is sent to the variable frequency pump 5 to adjust its cooling medium delivery rate. The detected condensation temperature is also considered. It monitors and outputs control signals to control the start and stop of the cooling unit 11; S5: Through the coordinated action of the three-way solenoid valve 4 and the variable frequency pump 5, the oil outlet temperature at the outlet of condenser 2 is increased. Stabilize at the lowest threshold and highest threshold between.

[0023] Preferably, when the distillation stage of distillation column 1 is switched, the control unit 10 automatically calls the minimum threshold value corresponding to that stage. and highest threshold .

[0024] Preferably, when the distillation stage of distillation column 1 is switched, the control unit 10 automatically calls the minimum threshold value corresponding to that stage. and highest threshold .

[0025] The core control process of the control unit 10 is as follows: first, set the minimum threshold temperature of the oil entering the oil storage tank 3. and highest threshold .

[0026] Oil outlet temperature detector 8 monitors oil outlet temperature in real time And feed it back to control unit 10, control unit 10 will Compared with the preset minimum threshold and highest threshold Compare them.

[0027] like > This indicates insufficient condensation, and control unit 10 will perform the following operations: A signal is transmitted to the variable frequency pump 5 to increase its operating frequency, thereby increasing the overall circulation flow rate of the cooling medium and enhancing its cooling capacity.

[0028] At the same time, the opening of the three-way solenoid valve 4 may be increased to ensure that sufficient cooling medium flows through the condenser 2.

[0029] like < If this indicates excessive cooling, the control unit 10 will reduce the frequency of the variable frequency pump 5 and decrease the opening of the three-way solenoid valve 4 to reduce cooling capacity and save energy.

[0030] In addition, the condensation temperature detector 9 monitors the initial temperature of the cooling medium exiting the cooling medium storage tank 6. If the ambient temperature is very high, it will cause The temperature is already high, so even with the variable frequency pump 5 fully operational, effective cooling is difficult. At this point, the control unit 10 will start the refrigeration unit 11. The refrigerant flows through the spiral coil across the surface of the variable frequency pump 5's inlet pipe, cooling the cooling medium flowing into the variable frequency pump 5 and improving cooling capacity from the source. When the temperature drops to a sufficient level, the control unit 10 controls the refrigeration unit 11 to shut down.

[0031] Through the aforementioned coordinated control, the system can overcome the influence of fluctuations in external ambient temperature and distillation conditions, and always accurately control the condensation temperature near the set value, thereby achieving high-quality, low-energy continuous production.

[0032] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A cooling temperature control system for waste lubricating oil distillation and recovery, comprising a distillation column (1), an oil storage tank (3), and a cooling temperature control system, wherein the cooling temperature control system is connected between the distillation column (1) and the oil storage tank (3), characterized in that, include: The input end of the condenser (2) is connected to the oil and gas outlet of the distillation column (1), the output end of the condenser (2) is connected to the oil inlet of the oil storage tank (3), and the tube side of the condenser (2) is connected to the cooling module. The cooling module includes a cooling medium storage tank (6), a variable frequency pump (5), a three-way solenoid valve (4), and a condenser (2) connected in sequence by pipes to form a circulation. The three-way solenoid valve (4) includes an inlet, a first outlet, and a second outlet. The inlet of the cooling medium storage tank (6) is connected to the output port of the variable frequency pump (5). The first outlet of the three-way solenoid valve (4) is connected to the inlet of the condenser (2). The second outlet of the three-way solenoid valve (4) is connected to the interior of one of the cooling medium storage tanks (6) through a pipe. Temperature sensing module, used to detect temperature parameters of the cooling temperature control system; The refrigeration unit (11) has a spiral coil connected to its output end via a pipeline. The spiral coil is spirally arranged on the pipeline surface of the input port of the variable frequency pump (5). The refrigeration unit (11) is used to rapidly cool the cooling medium inside the cooling medium storage tank (6).

2. The cooling temperature control system for waste lubricating oil distillation and recovery according to claim 1, characterized in that, The temperature sensing module includes an inlet oil temperature detector (7), an outlet oil temperature detector (8), and a condensation temperature detector (9). The inlet oil temperature detector (7) is installed on the surface of the pipe connecting the distillation tower (1) and the condenser (2). The outlet oil temperature detector (8) is installed on the surface of the pipe connecting the condenser (2) and the oil storage tank (3). The condensation temperature detector (9) is installed on the surface of the pipe connecting the condenser (2) and the three-way solenoid valve (4).

3. The cooling temperature control system for waste lubricating oil distillation and recovery according to claim 2, characterized in that, The cooling temperature control system also includes a control unit (10), which is electrically connected to the temperature sensing module, the refrigeration unit (11), the variable frequency pump (5), the three-way solenoid valve (4) and the condenser (2); The control unit (10) is configured to set a preset threshold for the oil temperature entering the oil storage tank (3), the preset threshold including a minimum threshold temperature. and highest threshold ; The oil outlet temperature detected by the oil outlet temperature detector (8) As the main controlled variable, the operating frequency of the variable frequency pump (5) is adjusted by a preset algorithm; The condensation temperature detected by the real-time monitoring condensation temperature detector (9) , to control the start and stop of the refrigeration unit (11); The oil inlet temperature is detected by the oil inlet temperature detector (7), and the oil outlet temperature is detected by the oil outlet temperature detector (8). The three-way solenoid valve (4) is subjected to composite control to regulate the feed rate of the cooling medium; And when Abnormal temperature, and Unable to stabilize at the lowest threshold and highest threshold During this period, start and stop the condenser (2).

4. The cooling temperature control system for waste lubricating oil distillation and recovery according to claim 3, characterized in that, The preset algorithm is the PID algorithm.

5. A cooling temperature control system for waste lubricating oil distillation and recovery according to claim 3, characterized in that, The cooling medium is heat transfer oil or an aqueous solution of ethylene glycol.

6. A cooling temperature control process for a cooling temperature control system for waste lubricating oil distillation and recovery according to any one of claims 1-5, characterized in that, Includes the following steps: S1: First, set the preset threshold for the oil temperature entering the oil storage tank (3) in the control unit (10); S2: Start the distillation tower (1), and the oil and gas inside the distillation tower (1) enter the condenser (2) through the pipeline; S3: The temperature sensing module detects the oil inlet temperature at the condenser (2) location in real time. Oil outlet temperature and condensation temperature And transmit the signal to the control unit (10); S4: The control unit (10) will detect the oil outlet temperature. With minimum threshold and highest threshold By comparing the two signals, the PID algorithm outputs two control signals. One control signal is sent to the three-way solenoid valve (4) to adjust its flow ratio, and the other control signal is sent to the variable frequency pump (5) to adjust its cooling medium delivery rate and to monitor the detected condensation temperature. Monitor and output control signals to control the start and stop of the cooling unit (11); S5: Through the synergistic action of the three-way solenoid valve (4) and the variable frequency pump (5), the oil outlet temperature at the outlet of the condenser (2) is increased. Stabilize at the lowest threshold and highest threshold between.

7. The cooling temperature control process of the cooling temperature control system for waste lubricating oil distillation and recovery according to claim 6, characterized in that, When the distillation stage of the distillation column (1) is switched, the control unit (10) automatically calls the minimum threshold degree corresponding to that stage. and highest threshold .

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