Methanol washing steam waste heat power generation device and method

Abstract

The invention discloses a methanol washing steam waste heat power generation device and method, and belongs to the technical field of chemical waste heat power generation. The device comprises a power generation mechanism, a steam heat exchange mechanism and a working medium circulation mechanism, and the power generation mechanism is connected with the steam heat exchange mechanism and the working medium circulation mechanism through pipelines; and the steam heat exchange mechanism is connected with the working medium circulating mechanism through a pipeline. According to the methanol washing steam waste heat power generation device and method, methanol steam waste heat generated by the thermal regeneration tower in the methanol washing process is converted into electric energy through the power generation mechanism, efficient waste heat utilization is achieved, circulating water system loads and resource waste are reduced, clean power generation is achieved through environment-friendly working media, and the energy-saving effect is achieved. And a power generation mechanism is flexible in load adjustment, a bypass safety mechanism is arranged, the operation automation degree is high, maintenance is easy and convenient, energy and operation cost of enterprises is reduced while extra power generation benefits are created, green production is assisted, and economic benefits and market competitiveness are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical waste heat power generation, and in particular to a device and method for power generation using waste heat from methanol washing steam. Background Art

[0002] During chemical production, especially in the methanol wash process, large amounts of methanol vapor are generated at the top of the thermal regeneration tower. For example, in most current synthetic ammonia and urea plants, the heat from this vapor is typically cooled by heat exchange with circulating water. This approach presents numerous drawbacks. Firstly, a significant amount of waste heat is wasted and not effectively utilized, which is inconsistent with the development philosophy of energy conservation and emission reduction. Secondly, the use of circulating water for heat exchange increases the load on the circulating water system, consuming more water resources and increasing the operating and maintenance costs of the circulating water equipment. Summary of the Invention

[0003] The purpose of the present invention is to provide a device and method for generating electricity from waste heat of methanol washing steam, which converts the waste heat of methanol steam generated in the thermal regeneration tower in the methanol washing process into electrical energy through a power generation mechanism, thereby achieving efficient utilization of waste heat, reducing the load and resource waste of the circulating water system, and using environmentally friendly working fluids to achieve clean power generation. The power generation mechanism has flexible load adjustment, a bypass safety mechanism, a high degree of operation automation, and simple maintenance. While creating additional power generation income, it reduces the energy and operating costs of the enterprise, promotes green production, and improves economic benefits and market competitiveness.

[0004] To achieve the above-mentioned objectives, the present invention provides a device for generating electricity from waste heat of methanol-washed steam, comprising a power generation mechanism, a steam heat exchange mechanism and a working fluid circulation mechanism, wherein the power generation mechanism is connected to the steam heat exchange mechanism and the working fluid circulation mechanism through pipelines, and the steam heat exchange mechanism is connected to the working fluid circulation mechanism through pipelines.

[0005] Preferably, the power generation mechanism includes a generator, a reducer, and a steam turbine unit, the generator is connected to the reducer, and the reducer is connected to the steam turbine unit.

[0006] Preferably, the steam heat exchange mechanism includes a low-methanol device thermal regeneration tower, a first methanol steam heat exchanger, a second methanol steam heat exchanger, a thermal regeneration tower top heat exchanger and a thermal regeneration tower top reflux tank. The low-methanol device thermal regeneration tower is connected to the first methanol steam heat exchanger and the thermal regeneration tower top heat exchanger respectively, the first methanol steam heat exchanger is connected to the second methanol steam heat exchanger, the second methanol steam heat exchanger and the thermal regeneration tower top heat exchanger are both connected to the thermal regeneration tower top reflux tank, and the thermal regeneration tower top reflux tank is connected to the thermal regeneration tower.

[0007] Preferably, the working fluid circulation mechanism includes a working fluid heat exchanger and a working fluid pump, and the working fluid heat exchanger and the working fluid pump are connected through a pipeline.

[0008] Preferably, the first methanol steam heat exchanger is connected to the steam turbine unit through a first pipeline, and the first methanol steam heat exchanger is connected to the working fluid heat exchanger through a second pipeline. A generator set control valve is installed on the first pipeline, and a working fluid shortcut valve is installed on the second pipeline. The steam turbine unit is connected to the working fluid heat exchanger.

[0009] Preferably, a methanol steam shortcut valve is installed on the third pipeline connecting the thermal regeneration tower of the low-methanol device and the thermal regeneration tower top heat exchanger.

[0010] Preferably, the working fluid pump is connected to the second methanol steam heat exchanger, and a methanol steam regulating valve is installed on the fourth pipeline connecting the second methanol steam heat exchanger and the reflux tank at the top of the thermal regeneration tower.

[0011] The present invention also provides a method for generating electricity using waste heat from methanol-washed steam, which uses the above-mentioned device for generating electricity using waste heat from methanol-washed steam, comprising the following steps:

[0012] Step 1: The methanol vapor generated in the thermal regeneration tower of the low-methanol device enters the first methanol vapor heat exchanger to exchange heat with the organic working medium inside, causing the organic working medium to heat up and vaporize. The methanol vapor that has exchanged heat with the working medium enters the second methanol vapor heat exchanger for heat exchange. The condensed methanol enters the reflux tank at the top of the thermal regeneration tower and finally enters the thermal regeneration tower. The organic working medium vaporized in the second methanol vapor heat exchanger enters the first methanol vapor heat exchanger, mixes with the organic working medium vaporized in the first methanol vapor heat exchanger, and enters the steam turbine unit through the first pipeline to drive the generator to generate electricity.

[0013] Step 2: After the organic working fluid enters the power generation mechanism, it is cooled and decompressed to a liquid state. The liquid organic working fluid exiting the power generation mechanism enters the working fluid heat exchanger to exchange heat with the circulating water again to reduce the temperature of the organic working fluid. Finally, the liquid organic working fluid is pressurized by the working fluid pump and sent to the steam heat exchange mechanism for recycling.

[0014] Step 3: When the power generation mechanism is abnormal, the methanol vapor generated in the thermal regeneration tower of the low-methanol device enters the heat exchanger at the top of the thermal regeneration tower through the fourth pipe to exchange heat with the circulating water. The condensed methanol after the heat exchange enters the reflux tank at the top of the thermal regeneration tower and finally enters the thermal regeneration tower. The gaseous organic working fluid enters the working fluid heat exchanger through the second pipe for heat exchange to realize circulation.

[0015] Therefore, the present invention adopts the above-mentioned device and method for generating electricity from waste heat of methanol-washed steam, which has the following beneficial effects:

[0016] (1) Energy saving and consumption reduction: The waste heat of methanol washing steam is converted into electrical energy, which realizes the effective utilization of low-grade thermal energy, reduces energy waste, and reduces the energy consumption cost of the enterprise;

[0017] (2) Environmental protection: The use of environmentally friendly organic working fluids will not cause pollution to the environment during the power generation process, complying with environmental protection requirements and helping enterprises achieve green development;

[0018] (3) Flexible load adjustment: The load adjustment range of the power generation mechanism is wide, up to 30%-110%, and the power generation power can be flexibly adjusted according to the changes in methanol steam production to ensure stable operation of the device and efficient use of energy;

[0019] (4) Simple operation: The power generation mechanism is easy to operate and has a high degree of automation, which reduces the difficulty and labor intensity of manual operation, reduces the risk of human operation errors, and improves the safety and reliability of production;

[0020] (5) Improve economic benefits: Generate additional economic benefits through power generation, enhance the market competitiveness of enterprises, and provide support for the sustainable development of enterprises.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a process flow chart of embodiment 1 of a device and method for generating electricity using waste heat from methanol-washed steam according to the present invention.

[0023] Reference numerals

[0024] 1. Thermal regeneration tower of low-methanol unit; 2. Methanol steam bypass valve; 3. First methanol steam heat exchanger; 4. Second methanol steam heat exchanger; 5. Control valve for generator set; 6. Working fluid bypass valve; 7. Steam turbine unit; 8. Reducer; 9. Generator; 10. Working fluid heat exchanger; 11. Working fluid pump; 12. Methanol steam regulating valve; 13. Heat exchanger at the top of thermal regeneration tower; 14. Reflux tank at the top of thermal regeneration tower. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0026] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0027] Example 1

[0028] like Figure 1 As shown, the present invention provides a device for generating electricity from waste heat of methanol-washed steam, including a power generation mechanism, a steam heat exchange mechanism and a working fluid circulation mechanism. The power generation mechanism is connected to the steam heat exchange mechanism and the working fluid circulation mechanism through pipelines, and the steam heat exchange mechanism is connected to the working fluid circulation mechanism through pipelines.

[0029] The power generation mechanism includes a generator 9, a reducer 8, and a steam turbine unit 7. The generator 9 is connected to the reducer 8, which is in turn connected to the steam turbine unit 7. The generator 9 converts the mechanical energy transmitted by the steam turbine unit 7 into electrical energy, achieving the core goal of waste heat power generation. The reducer 8 connects the steam turbine unit 7 and the generator 9, and by reducing the speed and increasing the torque, ensures that the generator 9 operates at a stable speed to meet the power generation needs. The steam turbine unit 7 uses the high-temperature and high-pressure organic working fluid gas to expand and perform work, converting the thermal energy of the organic working fluid into mechanical energy, driving the reducer 8 and generator 9 to operate.

[0030] The steam heat exchange mechanism includes a low-methanol device thermal regeneration tower 1, a first methanol steam heat exchanger 3, a second methanol steam heat exchanger 4, a thermal regeneration tower top heat exchanger 13, and a thermal regeneration tower top reflux tank 14. The low-methanol device thermal regeneration tower 1 is connected to the first methanol steam heat exchanger 3 and the thermal regeneration tower top heat exchanger 13, respectively. The low-methanol device thermal regeneration tower 1 is used to generate high-temperature methanol vapor, providing a heat source for the entire waste heat power generation system. The first methanol steam heat exchanger 3 is used to receive methanol vapor from the low-methanol device thermal regeneration tower 1 and perform heat exchange with the organic working fluid in the first methanol steam heat exchanger 3, causing the organic working fluid to heat up and vaporize, while cooling the methanol vapor. The use of environmentally friendly organic working fluids will not cause pollution to the environment during the power generation process, meeting environmental protection requirements and helping enterprises achieve green development. A methanol steam shortcut valve 2 is installed on the third pipeline connecting the low-methanol device thermal regeneration tower 1 and the thermal regeneration tower top heat exchanger 13. When the power generation mechanism is abnormal, the methanol steam shortcut valve 2 is opened to allow the methanol steam to bypass the first methanol steam heat exchanger 3 and the second methanol steam heat exchanger 4 and directly enter the thermal regeneration tower top heat exchanger 13 for cooling, ensuring that the production process is not interrupted.

[0031] The first methanol vapor heat exchanger 3 is connected to the second methanol vapor heat exchanger 4. The second methanol vapor heat exchanger 4 further exchanges heat with the methanol vapor, enhancing the gasification process of the organic working fluid while further reducing the temperature of the methanol vapor. The second methanol vapor heat exchanger 4 and the thermal regeneration tower overhead heat exchanger 13 are both connected to the thermal regeneration tower overhead reflux tank 14. The thermal regeneration tower overhead heat exchanger 13 uses circulating water to perform a final cooling of the methanol vapor, condensing it into liquid methanol. The thermal regeneration tower overhead reflux tank 14 is connected to the thermal regeneration tower and is used to collect the condensed methanol and return it to the thermal regeneration tower via a pipeline, achieving methanol recycling.

[0032] The working fluid circulation mechanism includes a working fluid heat exchanger 10 and a working fluid pump 11, which are connected by pipes. The working fluid heat exchanger 10 uses circulating water to cool the liquid organic working fluid discharged from the generator 9, reducing its temperature and ensuring that the organic working fluid can fully absorb the heat of the methanol vapor during the next heat exchange. The working fluid pump 11 is connected to the second methanol vapor heat exchanger 4. A methanol vapor regulating valve 12 is installed on the fourth pipe connecting the second methanol vapor heat exchanger 4 to the thermal regeneration tower overhead reflux drum 14. The methanol vapor regulating valve 12 is used to adjust the flow and pressure of the methanol vapor, controlling the amount of methanol entering the thermal regeneration tower overhead reflux drum 14 and ensuring stable system operation. The working fluid pump 11 is used to pressurize the cooled liquid organic working fluid, allowing it to enter the steam heat exchange mechanism (first methanol vapor heat exchanger 3 and second methanol vapor heat exchanger 4) at high pressure, thereby ensuring the circulation power of the organic working fluid.

[0033] The first methanol steam heat exchanger 3 is connected to the steam turbine unit 7 via a first pipeline. The first methanol steam heat exchanger 3 is connected to the working fluid heat exchanger 10 via a second pipeline. The first pipeline is equipped with a generator set inlet control valve 5, which controls the flow of organic working fluid into the steam turbine unit 7, adjusting the power generation capacity to meet different operating conditions. A working fluid bypass valve 6 is installed on the second pipeline. In the event of an abnormality in the working fluid circulation system, this valve is opened, allowing the organic working fluid to bypass the steam turbine unit 7 and enter the working fluid heat exchanger 10 directly for cooling, thus protecting the equipment. The steam turbine unit 7 is connected to the working fluid heat exchanger 10.

[0034] The present invention also provides a method for generating electricity using waste heat from methanol-washed steam, which uses the above-mentioned device for generating electricity using waste heat from methanol-washed steam, comprising the following steps:

[0035] Step 1: The methanol vapor generated in the thermal regeneration tower 1 of the low-methanol device enters the first methanol vapor heat exchanger 3 to exchange heat with the organic working medium inside, causing the organic working medium to heat up and vaporize. The methanol vapor that has exchanged heat with the working medium enters the second methanol vapor heat exchanger 4 for heat exchange. The condensed methanol enters the reflux tank 14 at the top of the thermal regeneration tower and finally enters the thermal regeneration tower. The organic working medium vaporized in the second methanol vapor heat exchanger 4 enters the first methanol vapor heat exchanger 3, mixes with the organic working medium vaporized in the first methanol vapor heat exchanger 3, and enters the steam turbine unit 7 through the first pipeline to drive the generator 9 to generate electricity.

[0036] Step 2: After entering the power generation mechanism, the organic working fluid is cooled and decompressed to a liquid state. The liquid organic working fluid exiting the power generation mechanism enters the working fluid heat exchanger 10 to exchange heat with the circulating water again to reduce the temperature of the organic working fluid. Finally, the liquid organic working fluid is pressurized and sent to the steam heat exchange mechanism for recycling through the working fluid pump 11.

[0037] Step 3: When the power generation mechanism is abnormal, open the methanol steam shortcut valve 2 and the working fluid shortcut valve 6. Part of the methanol steam generated by the low-methanol device thermal regeneration tower 1 enters the thermal regeneration tower top heat exchanger 13 through the fourth pipeline to exchange heat with the circulating water. The methanol condensed after the heat exchange enters the thermal regeneration tower top reflux tank 14 and finally enters the thermal regeneration tower. The other part of the methanol steam enters the first methanol steam heat exchanger 3 and the second methanol steam heat exchanger 4 to exchange heat with the working fluid to vaporize the working fluid. The gaseous organic working fluid enters the working fluid heat exchanger 10 through the second pipeline to exchange heat, thereby realizing circulation.

[0038] Before starting step 1, the device needs to be inspected to see if all equipment, pipelines, and valves are normal, if the organic working fluid level is appropriate, and if the electrical system is intact. Then, the working fluid pump 11 is started to circulate the organic working fluid in the system to establish a stable pressure.

[0039] When introducing methanol vapor, slowly open the valve for methanol vapor to enter the first methanol vapor heat exchanger 3 to allow methanol vapor to gradually enter the device. Pay attention to controlling the steam flow and pressure to avoid shock.

[0040] Monitor operating parameters: Closely monitor the temperature, pressure, and flow of methanol vapor, the temperature, pressure, and liquid level of the organic working fluid, as well as the voltage, current, and power of the generator 9 to ensure stable operation of the device.

[0041] When shutdown is required, first close the methanol steam valve to stop steam from entering. After the temperature and pressure of the entire device have dropped, stop the working fluid pump 11 and perform maintenance work on the device.

[0042] Therefore, the present invention adopts the above-mentioned device and method for generating electricity from waste heat of methanol washing steam, and converts the waste heat of methanol steam generated in the thermal regeneration tower in the methanol washing process into electrical energy through a power generation mechanism, which not only realizes efficient utilization of waste heat and reduces the load and resource waste of the circulating water system, but also uses environmentally friendly working fluids to achieve clean power generation. The power generation mechanism has flexible load adjustment, a bypass safety mechanism, a high degree of operation automation, and simple maintenance. While creating additional power generation income, it reduces the company's energy and operating costs, promotes green production, and improves economic benefits and market competitiveness.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A device for generating electricity from waste heat of methanol-washed steam, characterized in that: It includes a power generation mechanism, a steam heat exchange mechanism and a working fluid circulation mechanism. The power generation mechanism is connected to the steam heat exchange mechanism and the working fluid circulation mechanism through pipelines respectively, and the steam heat exchange mechanism is connected to the working fluid circulation mechanism through pipelines.

2. The device for generating electricity from waste heat of methanol-washed steam according to claim 1, characterized in that: The power generation mechanism includes a generator, a reducer and a steam turbine unit. The generator is connected to the reducer, and the reducer is connected to the steam turbine unit.

3. The device for generating electricity from waste heat of methanol-washed steam according to claim 2, characterized in that: The steam heat exchange mechanism includes a low-methanol device thermal regeneration tower, a first methanol steam heat exchanger, a second methanol steam heat exchanger, a thermal regeneration tower top heat exchanger and a thermal regeneration tower top reflux tank. The low-methanol device thermal regeneration tower is connected to the first methanol steam heat exchanger and the thermal regeneration tower top heat exchanger respectively, the first methanol steam heat exchanger is connected to the second methanol steam heat exchanger, the second methanol steam heat exchanger and the thermal regeneration tower top heat exchanger are both connected to the thermal regeneration tower top reflux tank, and the thermal regeneration tower top reflux tank is connected to the thermal regeneration tower.

4. The device for generating electricity from waste heat of methanol-washed steam according to claim 3, characterized in that: The working fluid circulation mechanism includes a working fluid heat exchanger and a working fluid pump, and the working fluid heat exchanger and the working fluid pump are connected through a pipeline.

5. The device for generating electricity from waste heat of methanol-washed steam according to claim 4, characterized in that: The first methanol steam heat exchanger is connected to the steam turbine unit through a first pipeline, and the first methanol steam heat exchanger is connected to the working fluid heat exchanger through a second pipeline. A generator set control valve is installed on the first pipeline, and a working fluid shortcut valve is installed on the second pipeline. The steam turbine unit is connected to the working fluid heat exchanger.

6. The methanol-washed steam waste heat power generation device according to claim 3, characterized in that: A methanol steam shortcut valve is installed on the third pipeline connecting the low-methanol unit thermal regeneration tower and the thermal regeneration tower top heat exchanger.

7. The device for generating electricity from waste heat of methanol-washed steam according to claim 4, characterized in that: The working fluid pump is connected to the second methanol steam heat exchanger, and a methanol steam regulating valve is installed on the fourth pipeline connecting the second methanol steam heat exchanger and the reflux tank at the top of the heat regeneration tower.

8. A method for generating electricity from waste heat of methanol-washed steam, characterized in that: The device for generating electricity using waste heat from methanol-washed steam according to any one of claims 1 to 7 comprises the following steps: Step 1: The methanol vapor generated in the thermal regeneration tower of the low-methanol device enters the first methanol vapor heat exchanger to exchange heat with the organic working medium inside, causing the organic working medium to heat up and vaporize. The methanol vapor that has exchanged heat with the working medium enters the second methanol vapor heat exchanger for heat exchange. The condensed methanol enters the reflux tank at the top of the thermal regeneration tower and finally enters the thermal regeneration tower. The organic working medium vaporized in the second methanol vapor heat exchanger enters the first methanol vapor heat exchanger, mixes with the organic working medium vaporized in the first methanol vapor heat exchanger, and enters the steam turbine unit through the first pipeline to drive the generator to generate electricity. Step 2: After the organic working fluid enters the power generation mechanism, it is cooled and decompressed to a liquid state. The liquid organic working fluid exiting the power generation mechanism enters the working fluid heat exchanger to exchange heat with the circulating water again to reduce the temperature of the organic working fluid. Finally, the liquid organic working fluid is pressurized by the working fluid pump and sent to the steam heat exchange mechanism for recycling. Step 3: When the power generation mechanism is abnormal, the methanol vapor generated in the thermal regeneration tower of the low-methanol device enters the heat exchanger at the top of the thermal regeneration tower through the fourth pipe to exchange heat with the circulating water. The condensed methanol after the heat exchange enters the reflux tank at the top of the thermal regeneration tower and finally enters the thermal regeneration tower. The gaseous organic working fluid enters the working fluid heat exchanger through the second pipe for heat exchange to realize circulation.

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