A methanol washing device waste heat recovery system
By designing a waste heat recovery system in the methanol washing unit, the coupling of the methanol water washing tower and the thermal regeneration tower was realized, the heat medium circulation was optimized, the problem of low-temperature waste heat not being recovered was solved, energy consumption was reduced, and the methanol circulation efficiency and H2S recovery rate in the tail gas were improved, thus reducing environmental risks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- 呼伦贝尔金新化工有限公司
- Filing Date
- 2025-07-22
- Publication Date
- 2026-08-04
AI Technical Summary
In traditional methanol washing units, low-temperature waste heat is not effectively recovered, leading to energy waste and environmental risks. The material and energy transfer between the methanol water washing tower and the thermal regeneration tower is not optimized, some low-temperature heat sources are not utilized, and sulfur-containing tail gas is directly emitted.
Design a waste heat recovery system for a methanol washing unit. By introducing a flow regulating valve and a gas flow sensor between the methanol water washing tower and the thermal regeneration tower, the two-stage towers are coupled. A methanol cooler is added at the bottom of the thermal regeneration tower to optimize the heat medium circulation and achieve cascade utilization.
It reduces system energy consumption by 15%, increases methanol cycle efficiency by 10%, improves H2S recovery rate in exhaust gas to 98%, avoids environmental risks of low-concentration sulfur emissions, and achieves efficient cascade utilization of low-temperature thermal energy.
Smart Images
Figure CN224593825U_ABST
Abstract
Description
Technical fields: This utility model relates to the field of waste heat recovery, specifically to a waste heat recovery system for a methanol washing device. Background technology: Methanol washing units are key equipment in coal chemical industry, natural gas purification, and other fields used to remove acidic gases (such as H2S and CO2). Their process involves numerous heat exchange and energy recovery stages. Traditional methanol washing units typically employ multi-stage towers (such as methanol water washing towers and thermal regeneration towers) to achieve methanol recycling, offering advantages such as low solvent costs and high purification efficiency. However, their high energy consumption has always been a bottleneck restricting the economic viability of the unit. Specifically: in traditional processes, a large amount of low-temperature waste heat is directly discharged through air or water cooling without recovery, resulting in significant energy waste; the material and energy transfer between the methanol water washing tower and the thermal regeneration tower lacks optimization, and some low-temperature heat sources are not effectively utilized; the sulfur-containing tail gas generated by the thermal regeneration tower is directly discharged or simply treated, wasting sulfur resources and increasing environmental risks. Utility model content: In order to solve the above problems, the purpose of this utility model is to provide a waste heat recovery system for a methanol washing device.
[0004] This utility model is implemented by the following technical solution: A waste heat recovery system for a methanol washing unit includes a methanol water washing tower, a separation tower cooler, a separation tower reflux tank, a first reboiler, a thermal regeneration tower, a thermal regeneration tower cooler, a thermal regeneration tower reflux tank, a second reboiler, a heat exchanger, and a water washing tower. The top outlet of the methanol washing tower is connected to the hot medium inlet of the separation tower cooler via a pipeline. The hot medium outlet of the separation tower cooler is connected to the inlet of the separation tower reflux tank via a pipeline. The outlet of the separation tower reflux tank is connected to the inlet of the first reflux pump via a pipeline. The outlet of the first reflux pump is connected to the top reflux port of the methanol washing tower via a pipeline. The bottom outlet of the methanol washing tower is connected to the inlet of the first reboiler via a pipeline. The outlet of the first reboiler is connected to the middle inlet of the methanol washing tower via a pipeline. The top outlet of the thermal regeneration tower is connected to the heat medium inlet of the thermal regeneration tower cooler via a pipeline; the heat medium outlet of the thermal regeneration tower cooler is connected to the inlet of the thermal regeneration tower reflux tank via a pipeline; the outlet of the thermal regeneration tower reflux tank is connected to the inlet of the second reflux pump via a pipeline; the outlet of the second reflux pump is connected to the top reflux port of the thermal regeneration tower via a pipeline; the bottom outlet of the thermal regeneration tower is connected to the inlet of the second reboiler via a pipeline; and the outlet of the second reboiler is connected to the middle inlet of the methanol washing tower via a pipeline. The top outlet of the methanol washing tower is also connected to the inlet of the thermal regeneration tower via a pipeline. The gas phase outlet of the reflux tank of the thermal regeneration tower is connected to the heat medium inlet of the heat exchanger via a pipeline, the heat medium outlet of the heat exchanger is connected to the bottom air inlet of the water washing tower via a pipeline, and the top exhaust port of the water washing tower is connected to the air inlet of the flare via a pipeline.
[0005] Furthermore, a flow regulating valve and a gas flow sensor are sequentially installed along the gas direction on the pipeline connecting the top outlet of the methanol washing tower and the inlet of the thermal regeneration tower. The signal output terminal of the gas flow sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminal of the flow regulating valve.
[0006] Furthermore, the top exhaust port of the water washing tower is connected to the air inlet of the sulfur recovery system via a pipeline; a hydrogen sulfide concentration sensor is installed at the top exhaust port of the water washing tower; an exhaust valve is installed on the pipeline connecting the water washing tower and the flare; a recovery valve is installed on the pipeline connecting the water washing tower and the sulfur recovery system; the signal output terminal of the hydrogen sulfide concentration sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminals of the exhaust valve and the recovery valve respectively.
[0007] Furthermore, the bottom outlet of the thermal regeneration tower is connected to the inlet of the methanol cooler via a pipeline, the outlet of the methanol cooler is connected to the inlet of the third reflux pump via a pipeline, and the outlet of the third reflux pump is connected to the inlet of the separation tower reflux tank via a pipeline.
[0008] Furthermore, a liquid level sensor is installed in the reflux tank of the separation tower, and a reflux valve is installed on the pipeline connecting the bottom outlet of the thermal regeneration tower and the inlet of the methanol cooler; the signal output terminal of the liquid level sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminal of the reflux valve.
[0009] Furthermore, the gas phase outlet of the separation tower reflux tank is connected to the gas inlet of the pickling tower via a pipeline.
[0010] Advantages of this utility model: This invention allows a portion of the gas discharged from the top of the methanol washing tower to directly enter the thermal regeneration tower through a flow regulating valve, achieving a coupled design of the two-stage towers. This enables the cascade utilization of heat during the methanol circulation process, reducing system energy consumption by more than 15%. By cooling the methanol at the bottom of the thermal regeneration tower and sending it to the separation tower reflux tank, the liquid level in the reflux tank can be maintained stably, solving the system instability problem caused by liquid level fluctuations in the reflux tank and improving methanol circulation efficiency by 10%. Furthermore, the purity of the product at the top of the methanol washing tower can be controlled. By monitoring the H2S concentration in the exhaust gas from the top of the washing tower and controlling whether to recover the tail gas, the H2S recovery rate in the tail gas is increased to 98%, while avoiding the environmental risks of low-concentration sulfur emissions.
[0011] The efficient and compact waste heat recovery system proposed in this invention optimizes the heat medium circulation, realizes the cascade utilization of low-temperature heat energy, and ultimately reduces steam consumption, providing key technical support for the green and low-carbon transformation of the industry. Attached image description: Figure 1 This is a schematic diagram of the system connection in this embodiment; Figure 2 This is the control principle diagram of this embodiment.
[0013] In the diagram: 1. Methanol washing tower; 2. Separation tower cooler; 3. Separation tower reflux tank; 4. First reflux pump; 5. First reboiler; 6. Thermal regeneration tower; 7. Thermal regeneration tower cooler; 8. Thermal regeneration tower reflux tank; 9. Second reflux pump; 10. Second reboiler; 11. Heat exchanger; 12. Washing tower; 13. Flare; 14. Sulfur recovery system; 15. Methanol cooler; 16. Third reflux pump; 17. Acid washing tower; 18. Gas flow sensor; 19. Hydrogen sulfide concentration sensor; 20. Liquid level sensor; 21. Controller; 22. Exhaust valve; 23. Recovery valve; 24. Flow regulating valve; 25. Reflux valve. Detailed implementation method: The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0015] Example 1: like Figure 1-2 As shown, a waste heat recovery system for a methanol washing unit includes a methanol water washing tower 1, a separation tower cooler 2, a separation tower reflux tank 3, a first reboiler 5, a thermal regeneration tower 6, a thermal regeneration tower cooler 7, a thermal regeneration tower reflux tank 8, a second reboiler 10, a heat exchanger 11, and a water washing tower 12. The top outlet of methanol washing tower 1 is connected to the hot medium inlet of separation tower cooler 2 via a pipeline. The hot medium outlet of separation tower cooler 2 is connected to the inlet of separation tower reflux tank 3 via a pipeline. The outlet of separation tower reflux tank 3 is connected to the inlet of first reflux pump 4 via a pipeline. The outlet of first reflux pump 4 is connected to the top reflux port of methanol washing tower 1 via a pipeline. The bottom outlet of methanol washing tower 1 is connected to the inlet of first reboiler 5 via a pipeline. The outlet of first reboiler 5 is connected to the middle inlet of methanol washing tower 1 via a pipeline. The top outlet of the thermal regeneration tower 6 is connected to the hot medium inlet of the thermal regeneration tower cooler 7 via a pipeline. The hot medium outlet of the thermal regeneration tower cooler 7 is connected to the inlet of the thermal regeneration tower reflux tank 8 via a pipeline. The outlet of the thermal regeneration tower reflux tank 8 is connected to the inlet of the second reflux pump 9 via a pipeline. The outlet of the second reflux pump 9 is connected to the top reflux port of the thermal regeneration tower 6 via a pipeline. The bottom outlet of the thermal regeneration tower 6 is connected to the inlet of the second reboiler 10 via a pipeline. The outlet of the second reboiler 10 is connected to the middle inlet of the methanol water washing tower 1 via a pipeline. The top outlet of methanol washing tower 1 is also connected to the inlet of thermal regeneration tower 6 via a pipeline. The gas phase outlet of the reflux tank 8 of the thermal regeneration tower is connected to the heat medium inlet of the heat exchanger 11 through a pipeline. The heat medium outlet of the heat exchanger 11 is connected to the bottom air inlet of the water washing tower 12 through a pipeline. The top exhaust port of the water washing tower 12 is connected to the air inlet of the flare 13 through a pipeline.
[0016] In this embodiment, the bottom outlet of the thermal regeneration tower 6 is also connected to the inlet of the methanol cooler 15 via a pipeline. The outlet of the methanol cooler 15 is connected to the inlet of the third reflux pump 16 via a pipeline. The outlet of the third reflux pump 16 is connected to the inlet of the separation tower reflux tank 3 via a pipeline. The gas phase outlet of the separation tower reflux tank 3 is connected to the gas inlet of the acid washing tower 17 via a pipeline.
[0017] A flow regulating valve 24 and a gas flow sensor 18 are sequentially installed along the gas direction on the pipeline connecting the top outlet of the methanol washing tower 1 and the liquid inlet of the thermal regeneration tower 6; the top exhaust port of the washing tower 12 is also connected to the gas inlet of the sulfur recovery system 14 through a pipeline; a hydrogen sulfide concentration sensor 19 is installed at the top exhaust port of the washing tower 12; an exhaust valve 22 is installed on the pipeline connecting the washing tower 12 and the flare 13; a recovery valve 23 is installed on the pipeline connecting the washing tower 12 and the sulfur recovery system 14; a liquid level sensor 20 is installed in the separation tower reflux tank 3; and a reflux valve 25 is installed on the pipeline connecting the bottom outlet of the thermal regeneration tower 6 and the inlet of the methanol cooler 15.
[0018] The signal output terminals of the gas flow sensor 18, hydrogen sulfide concentration sensor 19, and liquid level sensor 20 are all connected to the signal input terminal of the controller 21. The signal output terminal of the controller 21 is connected to the signal input terminals of the flow regulating valve 24, the exhaust valve 22, the recovery valve 23, and the return valve 25, respectively.
[0019] Job Description: After the raw gas passes through methanol washing tower 1 to absorb acidic gases, it exits from the top of the tower and splits into two paths: one path is condensed by separator cooler 2 and enters separator reflux tank 3, with the reflux liquid returning to the top of methanol washing tower 1 via first reflux pump 4; the other path enters thermal regeneration tower 6 via flow regulating valve 24 (controlled by gas flow sensor 18 and controller 21). Thermal regeneration tower 6 is used to remove H2S from methanol. As a distillation tower, its power source is the heat exchange between the steam from the second reboiler 10 at the bottom of the tower and methanol. The vapor phase at the top of thermal regeneration tower 6 is condensed by thermal regeneration tower cooler 7 and enters thermal regeneration tower reflux tank 8, with the reflux liquid returning to the top of the tower via second reflux pump 9; the liquid phase at the bottom of the tower is heated by the second reboiler 10 and returned to the middle of methanol washing tower 1. The gas phase outlet of the thermal regeneration tower reflux tank 8 is connected to the heat exchanger 11. The cooled tail gas enters the water washing tower 12 for desulfurization and is then discharged to the flare 13 or the sulfur recovery system 14.
[0020] In this embodiment, the pipeline from the top of methanol washing tower 1 to thermal regeneration tower 6 is equipped with a gas flow sensor 18 and a flow regulating valve 24 to control the flow rate of a gas at 0.3 MPa, a temperature of 95°C, and a flow rate of 14849 m³ / h. 3 / h of methanol vapor is fed into the thermal regeneration tower 6 and used as the power source for the methanol regeneration part of the thermal regeneration tower 6, thereby reducing the steam consumption of the second reboiler 10 and achieving the effect of waste heat recovery.
[0021] A hydrogen sulfide concentration sensor 19 is installed at the exhaust port of the top of the water washing tower 12. When the H2S concentration is >100ppm, the controller 21 closes the exhaust valve 22 and opens the recovery valve 23, and introduces the tail gas into the sulfur recovery system 14 to recover H2S; otherwise, it is discharged into the flare 13.
[0022] A methanol cooler 15 and a third reflux pump 16 are added to the bottom outlet of the thermal regeneration tower 6 to cool part of the methanol before sending it to the separation tower reflux tank 3, thereby controlling the purity of the product at the top of the methanol washing tower 1. A liquid level sensor 20 is installed in the separation tower reflux tank 3. When the liquid level is lower than the set low value, the controller 21 opens the reflux valve 25 to replenish methanol; when the liquid level is higher than the set high value, the controller 21 closes the reflux valve 25 to stop replenishing methanol.
[0023] In this embodiment, a portion of the gas discharged from the top of the methanol washing tower 1 is directly introduced into the thermal regeneration tower 6 through the flow regulating valve 24, realizing a coupled design of the two-stage towers. This allows for the cascaded utilization of heat during the methanol circulation process, reducing system energy consumption by more than 15%. By cooling the methanol at the bottom of the thermal regeneration tower 6 and sending it to the separation tower reflux tank 3, the liquid level in the separation tower reflux tank 3 can be maintained stably, solving the system instability problem caused by liquid level fluctuations in the separation tower reflux tank 3, and improving the methanol circulation efficiency by 10%. On the other hand, the purity of the product at the top of the methanol washing tower 1 can be controlled. By monitoring the H2S concentration in the exhaust gas at the top of the washing tower 12 and controlling whether to recover the tail gas, the H2S recovery rate in the tail gas is increased to 98%, while avoiding the environmental risks of low-concentration sulfur emissions.
[0024] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A methanol wash unit waste heat recovery system characterized by, It includes a methanol washing tower, a separation tower cooler, a separation tower reflux tank, a first reboiler, a thermal regeneration tower, a thermal regeneration tower cooler, a thermal regeneration tower reflux tank, a second reboiler, a heat exchanger, and a washing tower. The top outlet of the methanol washing tower is connected to the hot medium inlet of the separation tower cooler via a pipeline. The hot medium outlet of the separation tower cooler is connected to the inlet of the separation tower reflux tank via a pipeline. The outlet of the separation tower reflux tank is connected to the inlet of the first reflux pump via a pipeline. The outlet of the first reflux pump is connected to the top reflux port of the methanol washing tower via a pipeline. The bottom outlet of the methanol washing tower is connected to the inlet of the first reboiler via a pipeline. The outlet of the first reboiler is connected to the middle inlet of the methanol washing tower via a pipeline. The top outlet of the thermal regeneration tower is connected to the heat medium inlet of the thermal regeneration tower cooler via a pipeline; the heat medium outlet of the thermal regeneration tower cooler is connected to the inlet of the thermal regeneration tower reflux tank via a pipeline; the outlet of the thermal regeneration tower reflux tank is connected to the inlet of the second reflux pump via a pipeline; the outlet of the second reflux pump is connected to the top reflux port of the thermal regeneration tower via a pipeline; the bottom outlet of the thermal regeneration tower is connected to the inlet of the second reboiler via a pipeline; and the outlet of the second reboiler is connected to the middle inlet of the methanol washing tower via a pipeline. The top outlet of the methanol washing tower is also connected to the inlet of the thermal regeneration tower via a pipeline. The gas phase outlet of the reflux tank of the thermal regeneration tower is connected to the heat medium inlet of the heat exchanger via a pipeline, the heat medium outlet of the heat exchanger is connected to the bottom air inlet of the water washing tower via a pipeline, and the top exhaust port of the water washing tower is connected to the air inlet of the flare via a pipeline.
2. A methanol wash unit waste heat recovery system according to claim 1, wherein, A flow regulating valve and a gas flow sensor are sequentially installed along the gas direction on the pipeline connecting the top outlet of the methanol washing tower and the inlet of the thermal regeneration tower. The signal output terminal of the gas flow sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminal of the flow regulating valve.
3. The methanol wash unit waste heat recovery system of claim 1, wherein, The top exhaust port of the water washing tower is also connected to the air inlet of the sulfur recovery system via a pipeline; a hydrogen sulfide concentration sensor is installed at the top exhaust port of the water washing tower; an exhaust valve is installed on the pipeline connecting the water washing tower and the flare; a recovery valve is installed on the pipeline connecting the water washing tower and the sulfur recovery system; the signal output terminal of the hydrogen sulfide concentration sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminals of the exhaust valve and the recovery valve respectively.
4. The methanol wash unit waste heat recovery system of claim 1, wherein, The bottom outlet of the thermal regeneration tower is also connected to the inlet of the methanol cooler via a pipeline, the outlet of the methanol cooler is connected to the inlet of the third reflux pump via a pipeline, and the outlet of the third reflux pump is connected to the inlet of the separation tower reflux tank via a pipeline.
5. A methanol wash unit waste heat recovery system as claimed in claim 4, wherein, A liquid level sensor is installed in the reflux tank of the separation tower, and a reflux valve is installed on the pipeline connecting the bottom outlet of the thermal regeneration tower and the inlet of the methanol cooler; the signal output terminal of the liquid level sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the signal input terminal of the reflux valve.
6. The methanol wash unit waste heat recovery system of claim 1, wherein, The gas phase outlet of the separation tower reflux tank is connected to the gas inlet of the pickling tower via a pipeline.