A system for producing hot water by solvent rearrangement heat as heat source for benzene distillation

Abstract

A system of solvent rearrangement heat hot water as the heat source of benzene distillation, the system includes hot water storage tank, the hot water storage tank passes through gas phase cyclohexane condenser and high efficiency heat exchanger in benzene distillation tower in proper order through pipeline and then backflow to hot water storage tank, forms closed cycle loop, the temperature range of hot water in hot water storage tank is 70-90 DEG C, and the outside of the pipeline is provided with heat preservation layer to reduce heat loss. The utility model discloses the advantages in that, can efficiently recover solvent rearrangement waste heat, reduce the energy consumption of benzene distillation.

Description

Technical Field

[0001] This utility model relates to the field of energy-saving technology in chemical production, specifically to a system that uses the heat generated during solvent rearrangement to prepare hot water and uses the hot water as a heat source for benzene distillation. Background Technology

[0002] In chemical production, the condensation process of cyclohexane vapor typically uses circulating water at 32°C as the cooling medium, which presents a significant energy waste problem. On the one hand, the circulating water requires a large amount of energy to maintain the low temperature; on the other hand, the substantial latent heat released during cyclohexane vapor condensation is not effectively utilized, resulting in a double waste of energy. Currently, existing technologies lack efficient systems for recovering and utilizing this waste heat, making it difficult to achieve significant energy savings while ensuring process stability. Summary of the Invention

[0003] This invention aims to solve the problem of serious energy waste in the cyclohexane vapor condensation process in the prior art, and provides a system that can efficiently recover solvent and rearrange waste heat and reduce the energy consumption of benzene distillation.

[0004] The technical solution of this invention is a system for using solvent rearrangement heat to generate hot water as a heat source for benzene distillation. The system includes a hot water storage tank. The hot water storage tank is returned to the hot water storage tank after passing through a gas phase cyclohexane condenser and a high-efficiency heat exchanger in the benzene distillation column via pipelines, forming a closed loop. The hot water temperature in the hot water storage tank is in the range of 70-90℃, and the outside of the pipeline is provided with a heat insulation layer to reduce heat loss.

[0005] Furthermore, the hot water storage tank is connected to the cooling pipe inside the vapor phase cyclohexane condenser via a water supply pump. A first temperature sensor is installed at the water inlet end of the cooling pipe. The first temperature sensor is electrically connected to a controller, and the controller is electrically connected to the water supply pump, used to adjust the flow rate of the water supply pump according to the inlet water temperature.

[0006] Furthermore, a second temperature sensor is provided at the outlet of the cooling pipe, and the cooling pipe is connected to a water supply pipe, which is connected to a temperature control box via a temperature-regulating water pump; the second temperature sensor is electrically connected to a controller, and the controller is electrically connected to the temperature-regulating water pump, used to control the amount of water supplied according to the outlet water temperature.

[0007] Furthermore, the hot water storage tank is equipped with a heating device and a third temperature sensor; the third temperature sensor is electrically connected to the controller, and the controller is electrically connected to the heating device, used to activate the heating device when the hot water temperature is below 70°C.

[0008] Furthermore, the high-efficiency heat exchanger adopts a finned heat exchange structure with a heat exchange efficiency of ≥90%, and the outer shell of the gas phase cyclohexane condenser is made of high-temperature resistant stainless steel with a temperature resistance of ≥120℃.

[0009] Beneficial effects:

[0010] 1. High efficiency and energy saving: By recovering the latent heat of condensation of cyclohexane vapor, the temperature of circulating water is increased from 32℃ to 70-90℃, which can be directly used as a heat source for benzene distillation. According to actual industrial application verification, in the implementation case of a chemical enterprise, the system reduced the energy consumption of the benzene distillation process by 78.6%, which is close to the theoretically calculated energy saving efficiency.

[0011] 2. Intelligent temperature control: The triple temperature sensor works in conjunction with the controller to achieve precise control of the system water temperature, ensuring that the hot water temperature remains stable within the range of 70-90℃, meeting the requirements of the benzene distillation process.

[0012] 3. High adaptability: The high-temperature resistant stainless steel condenser shell and high-efficiency insulation layer design effectively solve the problems of equipment temperature resistance and heat loss in high-temperature hot water circulation, and the system can operate stably for a long time.

[0013] 4. Easy to operate: The automated control system can automatically adjust the water pump flow and water replenishment based on real-time temperature data, reducing manual intervention and improving production efficiency. Attached Figure Description

[0014] Figure 1 : Schematic diagram of the overall system structure.

[0015] Figure 2 Schematic diagram of system control principle.

[0016] As shown in the figure, 1-hot water storage tank, 2-vapor phase cyclohexane condenser, 3-benzene distillation tower, 4-feed water pump, 5-temperature regulating water pump, 6-temperature regulating box, 7-heating device, 8-third temperature sensor, 9-controller, 10-first temperature sensor, 11-second temperature sensor. Detailed Implementation

[0017] like Figure 1 , 2 As shown, a benzene distillation heating system based on solvent rearrangement waste heat recovery mainly consists of a hot water storage tank 1, a vapor-phase cyclohexane condenser 2, and a benzene distillation column 3. The system achieves heat transfer through a closed-loop circulation system: the 70-90°C high-temperature water output from the hot water storage tank 1 flows sequentially through the cooling pipes of the vapor-phase cyclohexane condenser 2 and the high-efficiency heat exchanger in the distillation column 3, before returning to the storage tank via a return pipe, forming a closed loop. All delivery pipelines are equipped with high-performance insulation layers, with a heat loss coefficient ≤5%.

[0018] The core control module includes the following optimized designs:

[0019] 1. Temperature Feedback Water Supply System: The cooling pipeline of the vapor phase cyclohexane condenser 2 is connected to the water supply pump 4, and a first temperature sensor 10 is installed at the water inlet. This sensor and the PLC controller 9 form a closed-loop control system, which dynamically adjusts the flow parameters of the water supply pump 4 through a PID algorithm, achieving a control accuracy of ±0.5°C.

[0020] 2. Outlet water temperature compensation system: A second temperature sensor 11 is installed at the outlet of the cooling pipe, which works in conjunction with the controller 9. When the detected temperature deviates from the set value, the constant temperature water in the temperature control tank 6 is injected into the system as needed by the temperature control water pump 5. The water replenishment flow rate is adjustable from 0 to 20 L / min, and the response time is <3 seconds.

[0021] 3. Heat Source Protection System: The hot water storage tank 1 is equipped with an immersion electric heating device 7, which works in conjunction with a third temperature sensor 8 for joint control. When the temperature of the stored liquid is below the 70°C threshold, the heating program is automatically activated, with a heating rate of up to 2°C / min.

[0022] Technical parameter improvements:

[0023] (1) The high-efficiency heat exchanger adopts a finned heat transfer enhancement structure. After CFD simulation optimization, the actual heat transfer efficiency reaches 92.4%;

[0024] (2) The shell of the vapor phase cyclohexane condenser 2 is made of Cr19Ni10 stainless steel. According to the stress analysis of ANSYS, its creep resistance under 120-150°C conditions meets the requirements of ASME standards.

[0025] Taking the benzene distillation production process of a chemical enterprise as an example, the specific operation process of the system is as follows:

[0026] 1. System Startup: Turn on the water supply pump 4 and the temperature regulating pump 5. Water in the hot water storage tank 1 enters the cooling pipe of the vapor phase cyclohexane condenser 2 through the pipeline. In the initial stage, if the third temperature sensor 8 detects that the water temperature is below 70°C, the controller 9 starts the heating device 7 to preheat the hot water.

[0027] 2. Waste Heat Recovery: In the vapor phase cyclohexane condenser 2, high-temperature cyclohexane vapor exchanges heat with the hot water in the cooling pipes, and the hot water absorbs the latent heat of vapor condensation, raising its temperature to 70-90℃. The first temperature sensor 10 monitors the inlet water temperature of the cooling pipes in real time, and the controller 9 adjusts the flow rate of the water pump 4 according to the temperature data to ensure a stable inlet water temperature.

[0028] 3. Heat Utilization: The heated hot water enters the finned high-efficiency heat exchanger inside the benzene distillation tower 3, providing a heat source for the benzene distillation process. After heat exchange, the temperature of the hot water drops slightly and flows back to the hot water storage tank 1 through pipelines.

[0029] 4. Temperature control: The second temperature sensor 11 monitors the outlet water temperature of the cooling pipe. When the outlet water temperature exceeds 90℃, the controller 9 starts the temperature regulating water pump 5 to replenish low-temperature water from the temperature regulating box 6 to the cooling pipe and adjust the water temperature to a suitable range.

[0030] Specific test data:

[0031] 1. System parameters:

[0032] Cyclohexane vapor flow rate: 1050 kg / h (measured average);

[0033] Benzene distillation tower capacity: 800 kg / h;

[0034] Hot water storage tank volume: 50 m³;

[0035] Pipe insulation material: aluminum silicate fiber (thermal conductivity ≤0.035 W / (m・K));

[0036] Material of the vapor phase cyclohexane condenser shell: 310S high temperature resistant stainless steel (temperature resistance ≥120℃);

[0037] Comparison conditions: The original process (32℃ circulating water condensation) and this system were operated simultaneously, using the same cyclohexane steam treatment rate and benzene distillation load.

[0038] 2. Experimental data recording:

[0039]

[0040] 3. Energy efficiency calculation

[0041] Theoretical calculation correction:

[0042] Total energy consumption of the original process: 10,215,300 kJ / h;

[0043] New process energy consumption: 225,600 kJ / h (energy consumption for circulating water heating only);

[0044] Energy saving rate = (1 - (225600 / 10215300)) × 100% = 97.8%;

[0045] After considering equipment efficiency (90%) and heat loss (5%), the energy saving rate is corrected to: 97.8% × 0.9 × 0.95 = 83.1%;

[0046] Actual operating data: 30 consecutive days of operation.

[0047] The daily average energy saving rate is as follows:

[0048] Minimum energy saving rate: 78.6%; Maximum energy saving rate: 85.2%; Average energy saving rate: 81.3%.

[0049] 4. Verification of key issues

[0050] Heat loss control:

[0051] The measured heat loss rate of the pipe insulation layer was 4.8%, which meets the design requirements (≤5%), and no significant heat waste was observed.

[0052] Equipment high temperature resistance:

[0053] The outer shell temperature of the vapor phase cyclohexane condenser remained stable at 95~110℃ for a long period of time, and the 310S stainless steel material did not show deformation or corrosion, meeting the temperature resistance requirements.

[0054] System stability:

[0055] The triple temperature sensor (first temperature sensor, second temperature sensor, and third temperature sensor) is linked with the controller to ensure that the hot water temperature fluctuation range is ≤±3℃, thus ensuring the stability of the benzene distillation process.

[0056] 5. Experimental Conclusions

[0057] Test data shows that the system can achieve an energy saving rate of 78.6% to 85.2% in actual industrial applications, with an average energy saving rate of 81.3%, which is highly consistent with the theoretical calculation value (81%).

Claims

1. A system for using solvent rearrangement heat to generate hot water as a heat source for benzene distillation, characterized in that: The system includes a hot water storage tank (1). The hot water storage tank (1) flows back to the hot water storage tank (1) after passing through the high-efficiency heat exchangers in the vapor phase cyclohexane condenser (2) and benzene distillation tower (3) in sequence through the pipe, forming a closed loop. The hot water temperature in the hot water storage tank (1) is in the range of 70-90℃, and the outside of the pipe is provided with a heat insulation layer to reduce heat loss.

2. The system for generating hot water by solvent rearrangement as a heat source for benzene distillation according to claim 1, characterized in that: The hot water storage tank (1) is connected to the cooling pipe in the vapor phase cyclohexane condenser (2) via a water supply pump (4). A first temperature sensor (10) is provided at the water inlet end of the cooling pipe. The first temperature sensor (10) is electrically connected to the controller (9). The controller (9) is electrically connected to the water supply pump (4).

3. The system for using solvent rearrangement heat to generate hot water as a heat source for benzene distillation according to claim 2, characterized in that: The cooling pipe outlet is equipped with a second temperature sensor (11), the cooling pipe is connected to a water supply pipe, and the water supply pipe is connected to the temperature control box (6) through a temperature control water pump (5); the second temperature sensor (11) is electrically connected to the controller (9), and the controller (9) is electrically connected to the temperature control water pump (5) to control the amount of water supply according to the outlet water temperature.

4. The system for using solvent rearrangement heat to generate hot water as a heat source for benzene distillation according to claim 1, characterized in that: The hot water storage tank (1) is equipped with a heating device (7) and a third temperature sensor (8); the third temperature sensor (8) is electrically connected to a controller (9), and the controller (9) is electrically connected to the heating device (7) to start the heating device (7) when the hot water temperature is below 70°C.

5. The system for generating hot water from solvent rearrangement as a heat source for benzene distillation according to claim 1, characterized in that: The high-efficiency heat exchanger adopts a finned heat exchange structure with a heat exchange efficiency of ≥90%. The outer shell of the gas phase cyclohexane condenser (2) is made of high-temperature resistant stainless steel with a temperature tolerance of ≥120℃.

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