Energy utilization device in coal gasification

Abstract

The invention provides an energy utilization device in coal gasification, and relates to the technical field of coal gasification energy conservation. The energy utilization device in coal gasification comprises a hydrogen pressure reduction system and a slag water treatment system; the hydrogen pressure reduction system comprises a first pipeline, at least two expansion machines and at least two generators; the at least two expansion machines are sequentially connected to the first pipeline so as to sequentially reduce the pressure of hydrogen in the first pipeline; the generators are in one-to-one correspondence connection with the expanders; the slag water treatment system comprises a second pipeline, a low-pressure flash tank and a first heat exchanger; the low-pressure flash tank is arranged on the second pipeline and is used for treating slag water; the first heat exchanger is connected with a steam outlet of the low-pressure flash tank, and the first heat exchanger is connected to the first pipeline and located between the two expansion machines so that heat of steam in the low-pressure flash tank can be transmitted to the first pipeline. According to the energy utilization device in coal gasification, waste of pressure energy and heat energy is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of coal gasification energy conservation, and in particular to an energy utilization device in coal gasification. Background Art

[0002] Coal gasification is the process of sending water-coal slurry and oxygen into a gasifier in a certain proportion to carry out a partial oxidation reaction to produce raw coal gas with CO, H2, and CO2 as the main components. After cooling, humidification, and washing by equipment such as a washing tower, it is incorporated into the raw coal gas pipeline network and then sent to subsequent sections for further processing.

[0003] The slag water treatment system conducts high-pressure flash evaporation, low-pressure flash evaporation and vacuum flash evaporation on the slag water produced in the coal gasification process, so as to reduce temperature and pressure, recover part of the heat, concentrate black water, analyze acidic gases, and separate slag and water at the same time to achieve the purpose of recycling.

[0004] Since black water contains sulfur ions and ammonium ions that affect the pH value of water and plasma that is prone to scaling, and black water contains 1-3% ash, the heat in the black water is difficult to be fully utilized. Part of the heat energy can only be lost through water-cooled heat exchange treatment in the form of flash evaporation and condenser; at the same time, the high-pressure hydrogen produced and separated and purified by coal gasification is sent to downstream users after decompression, and is only throttled and expanded through the pressure reducing valve, resulting in a large amount of pressure energy waste. Summary of the invention

[0005] The present application provides an energy utilization device in coal gasification, which is used to solve the problem of waste of heat and pressure energy in the slag water treatment system and hydrogen decompression process in coal gasification.

[0006] The present application provides an energy utilization device in coal gasification, including a hydrogen pressure reduction system and a slag water treatment system;

[0007] The hydrogen pressure reduction system comprises a first pipeline, at least two expanders and at least two generators; the first pipeline is used to transport hydrogen generated in coal gasification, at least two expanders are sequentially connected to the first pipeline to sequentially reduce the pressure of the hydrogen in the first pipeline; the generators are connected to the expanders one by one;

[0008] The slag water treatment system includes a second pipeline, a low-pressure flash tank and a first heat exchanger; the second pipeline is used to transport the slag water generated in the coal gasification, and the low-pressure flash tank is arranged on the second pipeline to treat the slag water; the first heat exchanger is connected to the steam outlet of the low-pressure flash tank, and the first heat exchanger is connected to the first pipeline and located between the two expanders to transfer the heat of the steam in the low-pressure flash tank to the first pipeline.

[0009] In some embodiments, the slag water treatment system further comprises a vacuum flash tank and a second heat exchanger, wherein the vacuum flash tank is located at the rear end of the low-pressure flash tank and connected to the second pipeline, and the second heat exchanger is connected to the steam outlet of the vacuum flash tank;

[0010] The expander includes a first expander, a second expander, and a third expander; the generator includes a first generator, a second generator, and a third generator; the first expander, the second expander, and the third expander are sequentially arranged on the first pipeline; the first generator is connected to the first expander, the second generator is connected to the second expander, and the third generator is connected to the third expander; the first heat exchanger is located between the first expander and the second expander, and the second heat exchanger is connected to the first pipeline between the second expander and the third expander, so as to transfer the heat of the steam in the vacuum flash tank to the first pipeline.

[0011] In some embodiments, the slag water treatment system also includes a third heat exchanger and a circulating water pipe. The third heat exchanger is arranged at the steam outlet of the first heat exchanger, and the third heat exchanger is used to connect with the circulating water pipe to transfer the residual heat of the steam in the low-pressure flash tank to the circulating water pipe.

[0012] In some embodiments, the slag water treatment system also includes a fourth heat exchanger, which is arranged at the steam outlet of the second heat exchanger and is used to be connected to a circulating water pipe to transfer the residual heat of the steam in the vacuum flash tank to the circulating water pipe.

[0013] In some embodiments, the hydrogen depressurization system further includes a regulating pipeline connected in parallel with the first pipeline, and a pressure reducing valve is disposed on the regulating pipeline to supplement the hydrogen pressure at an end of the first pipeline away from the first expander.

[0014] In some embodiments, the hydrogen pressure at the outlet of the first expander is 3.0 MPa-3.5 MPa, and the hydrogen temperature at the outlet of the second expander is -6°C-3°C;

[0015] The temperature of the hydrogen at the outlet of the first heat exchanger is 122°C-127°C.

[0016] In some embodiments, the hydrogen pressure at the outlet of the second expander is 0.9 MPa-1.1 MPa, and the hydrogen temperature at the outlet of the second expander is 46° C.-50° C.;

[0017] The temperature of the hydrogen at the outlet of the second heat exchanger is 66°C-71°C.

[0018] In some embodiments, a pressure sensor is provided at the outlet end after the first pipeline and the regulating pipeline are connected in parallel. The pressure sensor is electrically connected to the pressure reducing valve. The pressure reducing valve regulates the opening of the pressure reducing valve according to pressure information detected by the pressure sensor to keep the hydrogen pressure at the outlet end after the first pipeline and the regulating pipeline are connected in parallel balanced.

[0019] In some embodiments, a first temperature sensor is provided at the steam outlet end of the third heat exchanger, and a first control valve is provided at one end of the circulating water pipe located at the water inlet of the third heat exchanger. The first control valve is electrically connected to the first temperature sensor, and the first control valve adjusts the opening of the first control valve according to the temperature information detected by the first temperature sensor to keep the steam temperature at the steam outlet end of the third heat exchanger stable.

[0020] In some embodiments, a second temperature sensor is provided at the steam outlet end of the fourth heat exchanger, and a second control valve is provided at one end of the circulating water pipe located at the water inlet of the fourth heat exchanger. The second control valve is electrically connected to the second temperature sensor, and the second control valve adjusts the opening of the second control valve according to the temperature information detected by the second temperature sensor to keep the steam temperature at the steam outlet end of the fourth heat exchanger stable.

[0021] The energy utilization device for coal gasification provided by the present application, through the setting of a hydrogen pressure reduction system and a slag water treatment system, high-pressure hydrogen enters the expander from the first pipeline for pressure reduction, and drives the generator to generate electricity through the expander, and the hydrogen after preliminary pressure reduction enters the first heat exchanger, and exchanges heat with the high-temperature steam generated by the low-pressure flash tank in the slag water treatment system to increase the temperature of the hydrogen, and then enters the expander to reduce the pressure and temperature, so as to drive the generator to operate and generate electricity through the expander, thereby realizing the synchronous utilization of the pressure energy of the high-pressure hydrogen during the pressure reduction process and the thermal energy in the slag water treatment system, reducing the waste of pressure energy and thermal energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0023] Figure 1 Schematic diagram of the structure of the energy utilization device in coal gasification provided in the embodiment of the present application Figure 1 ;

[0024] Figure 2 Schematic diagram of the structure of the energy utilization device in coal gasification provided in the embodiment of the present application Figure 2 .

[0025] Description of reference numerals:

[0026] 100, hydrogen decompression system; 110, first pipeline; 120, expander; 121, first expander; 122, second expander; 123, third expander; 130, expander; 131, first generator; 132, second generator; 133, third generator; 140, regulating pipeline;

[0027] 200, slag water treatment system; 210, second pipeline; 220, low-pressure flash tank; 230, first heat exchanger; 240, vacuum flash tank; 250, second heat exchanger; 260, third heat exchanger; 270, circulating water pipe; 280, fourth heat exchanger;

[0028] 310, pressure reducing valve; 320, pressure sensor; 330, first temperature sensor; 340, first control valve; 350, second temperature sensor; 360, second control valve; 370, third control valve.

[0029] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0030] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0031] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0032] In this application, unless otherwise clearly specified and limited, the terms "installation", "connection", "fixation" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0034] Coal gasification is the process of sending water-coal slurry and oxygen into a gasifier in a certain proportion to carry out a partial oxidation reaction to produce raw coal gas with CO, H2, and CO2 as the main components. After cooling, humidification, and washing by equipment such as a washing tower, it is incorporated into the raw coal gas pipeline network and then sent to subsequent sections for further processing.

[0035] The slag water treatment system conducts high-pressure flash evaporation, low-pressure flash evaporation and vacuum flash evaporation on the slag water produced in the coal gasification process, so as to reduce temperature and pressure, recover part of the heat, concentrate black water, analyze acidic gases, and separate slag and water at the same time to achieve the purpose of recycling.

[0036] Since black water contains sulfur ions and ammonium ions that affect the pH value of water and plasma that is prone to scaling, and black water contains 1-3% ash, the heat in the black water is difficult to be fully utilized. Part of the heat energy can only be lost through water-cooled heat exchange treatment in the form of flash evaporation and condenser; at the same time, the high-pressure hydrogen produced and separated and purified by coal gasification is sent to downstream users after decompression, and is only throttled and expanded through the pressure reducing valve, resulting in a large amount of pressure energy waste.

[0037] In order to solve the above problems, the present application provides a coal gasification energy utilization device. Through the setting of a hydrogen pressure reduction system and a slag water treatment system, high-pressure hydrogen enters the expander from the first pipeline for pressure reduction, and drives the generator to generate electricity through the expander. The hydrogen after preliminary pressure reduction enters the first heat exchanger, and exchanges heat with the high-temperature steam generated by the low-pressure flash tank in the slag water treatment system to increase the temperature of the hydrogen, and then enters the expander to reduce the pressure and temperature, so as to drive the generator to generate electricity through the expander, thereby realizing the synchronous utilization of the pressure energy of the high-pressure hydrogen during the pressure reduction process and the thermal energy in the slag water treatment system, reducing the waste of pressure energy and thermal energy.

[0038] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0039] The present application provides a device for utilizing energy in coal gasification, referring to Figure 1 and Figure 2 , the energy utilization device in coal gasification includes a hydrogen pressure reduction system 100 and a slag water treatment system 200;

[0040] The hydrogen pressure reduction system 100 includes a first pipeline 110, at least two expanders 120 and at least two generators 130; the first pipeline 110 is used to transport hydrogen generated in coal gasification, and at least two expanders 120 are sequentially connected to the first pipeline 110 to sequentially reduce the pressure of hydrogen in the first pipeline 110; the generators 120 and the expanders 130 are connected one by one;

[0041] The slag water treatment system 200 includes a second pipeline 210, a low-pressure flash tank 220 and a first heat exchanger 230; the second pipeline 210 is used to transport the slag water generated in coal gasification, and the low-pressure flash tank 220 is arranged on the second pipeline 210 to treat the slag water; the first heat exchanger 230 is connected to the steam outlet of the low-pressure flash tank 220, and the first heat exchanger 230 is connected to the first pipeline 110 between the two expanders 120 to transfer the heat of the steam in the low-pressure flash tank 220 to the first pipeline 110.

[0042] By adopting the above technical solution, high-pressure hydrogen enters the expander 120 from the first pipeline 110 to reduce the pressure, and drives the generator 130 to generate electricity through the expander 120. The hydrogen after preliminary pressure reduction enters the first heat exchanger 230, and exchanges heat with the high-temperature steam generated by the low-pressure flash tank 220 in the slag water treatment system 200 to increase the temperature of the hydrogen. The hydrogen then enters the expander 120 to reduce the pressure and temperature, so as to drive the generator 130 to operate and generate electricity through the expander 120, thereby realizing the synchronous utilization of the pressure energy of the high-pressure hydrogen and the thermal energy in the slag water treatment system 200 during the pressure reduction process, thereby reducing the waste of pressure energy and thermal energy.

[0043] In the first heat exchanger 230, the pipeline connected to the first pipeline 110 and the pipeline connected to the steam pipeline in the low-pressure flash tank 220 are two independent pipelines. Heat exchange is only performed in the first heat exchanger 230 to transfer the heat of the high-temperature steam in the low-pressure flash tank 220 to the low-temperature hydrogen in the first pipeline 110.

[0044] In some embodiments, reference Figure 1 The slag water treatment system 200 further includes a vacuum flash tank 240 and a second heat exchanger 250. The vacuum flash tank 240 is located at the rear end of the low-pressure flash tank 220 and is connected to the second pipeline 210. The second heat exchanger 250 is connected to the steam outlet of the vacuum flash tank 240.

[0045] The expander 120 includes a first expander 121, a second expander 122, and a third expander 123, and the generator includes a first generator 131, a second generator 132, and a third generator 133. The first expander 121, the second expander 122, and the third expander 123 are sequentially arranged on the first pipeline 110, the first generator 131 is connected to the first expander 121, the second generator 122 is connected to the second expander 132, and the third generator 133 is connected to the third expander 133; the first heat exchanger 230 is located between the first expander 121 and the second expander 122, and the second heat exchanger 250 is connected to the first pipeline 110 between the second expander 122 and the third expander 123, so as to transfer the heat of the steam in the vacuum flash tank 240 to the first pipeline 110.

[0046] Among them, the first expander 121, the second expander 122, and the third expander 123 are all turbine expanders. The first expander 121 is connected to the first generator 131, so as to utilize the pressure energy of the hydrogen in the first pipeline 110 to drive the first generator 131 to operate, generate electricity, and reduce the pressure of the hydrogen at the same time. The second expander 122 is connected to the second generator 132, so as to utilize the pressure energy and thermal energy of the hydrogen in the first pipeline 110 to drive the second expander 122 to drive the second generator 132 to operate, generate electricity, and realize the temperature and pressure reduction of the hydrogen.

[0047] In the slag water treatment system 200, the slag water is initially treated by the low-pressure flash tank 220, and then treated again by the vacuum flash tank 240, and finally the slag water is discharged into the clarification tank.

[0048] By adopting the above technical solution, the slag water treatment system 200 realizes effective heat recovery and water quality treatment through the technical application of the vacuum flash tank 240 and the second heat exchanger 250. The vacuum flash tank 240 is located at the rear end of the low-pressure flash tank 220, and is connected to the second heat exchanger 250 through the second pipeline 210. The vacuum environment is used to promote the superheating of the liquid and the rapid volatilization into steam. This process will absorb a large amount of heat, thereby realizing efficient heat recovery and water quality pretreatment. The second heat exchanger 250 is connected to the steam outlet of the vacuum flash tank 240, and further utilizes the steam heat to transfer the heat to the hydrogen in the first pipeline 110 through the pipeline, thereby improving the thermal efficiency of the system.

[0049] The hydrogen pressure reduction system 100 realizes effective control of hydrogen pressure and energy recovery through the arrangement of the third expander 123 and the third generator 133. The third expander 123 is located on the first pipeline 110, at the rear end of the second expander 122. Through the working principle of the expander, the high-pressure hydrogen is converted into mechanical energy, and then the third generator 133 is driven to generate electrical energy. This configuration not only optimizes the pressure management of hydrogen, but also improves the energy efficiency of the entire system through energy recovery.

[0050] The three-stage expansion power generation is realized in the process of hydrogen decompression and combined with the slag water treatment system 200, and the steam generated by the low-pressure flash tank 220 and the vacuum flash tank 240 is effectively used in combination with the hydrogen decompression system 100 for comprehensive power generation, thereby reducing energy waste.

[0051] In some embodiments, reference Figure 1 The slag water treatment system 200 also includes a third heat exchanger 260 and a circulating water pipe 270. The third heat exchanger 260 is arranged at the steam outlet of the first heat exchanger 230. The third heat exchanger 260 is used to be connected to the circulating water pipe 270 to transfer the residual heat of the steam in the low-pressure flash tank 220 to the circulating water pipe 270.

[0052] By setting the third heat exchanger 260, the steam heat energy of the low-pressure flash tank 220 is further utilized, the energy utilization efficiency is improved, and the stability of the system is enhanced. The use of the circulating water pipe 270 helps to maintain the balance of heat and fluid in the system. By reusing the circulating water, the system's dependence on external energy can be reduced, and the system's self-sufficiency can be enhanced, thereby improving the stability and reliability of the entire system. Reducing operating costs, improving energy utilization efficiency and reducing energy waste help reduce greenhouse gas emissions and have a positive effect on environmental protection. In addition, reducing the use of water resources also helps to reduce the pressure on water resources.

[0053] In some embodiments, reference Figure 1 The slag water treatment system 200 also includes a fourth heat exchanger 280, which is arranged at the steam outlet of the second heat exchanger 250 and is used to be connected to the circulating water pipe 270 to transfer the residual heat of the steam in the vacuum flash tank 240 to the circulating water pipe 270.

[0054] By setting up the fourth heat exchanger 280, the steam heat energy of the vacuum flash tank 240 is further utilized, which also achieves the same effect as the low-pressure flash tank 220 in improving the energy utilization efficiency, enhancing the stability of the system, and reducing the operating cost.

[0055] In some embodiments, the hydrogen decompression system 100 further includes a regulating pipeline 140 connected in parallel with the first pipeline 110 . A pressure reducing valve 310 is disposed on the regulating pipeline 140 to supplement the hydrogen pressure at the end of the first pipeline 110 away from the first expander 121 .

[0056] The regulating pipeline 140 is connected in parallel with the first pipeline 110, and a pressure reducing valve 310 is arranged on the regulating pipeline 140. When the hydrogen pressure downstream of the first pipeline 110 fluctuates, the hydrogen can be directly transported downstream by adjusting the pressure reducing valve 310 to keep the hydrogen supply pressure downstream stable.

[0057] In some embodiments, the hydrogen pressure at the outlet of the first expander 121 is 3.0 MPa-3.5 MPa, and the hydrogen temperature at the outlet of the first expander 121 is -6°C-3°C;

[0058] The temperature of hydrogen at the outlet of the first heat exchanger 230 is 122°C-127°C.

[0059] The temperature of the hydrogen outlet of the first heat exchanger 230 is preferably 124°C-125°C.

[0060] In some embodiments, the hydrogen pressure at the outlet of the second expander 122 is 0.9 MPa-1.1 MPa, and the hydrogen temperature at the outlet of the second expander 122 is 46° C.-50° C.;

[0061] The temperature of hydrogen at the outlet of the second heat exchanger 250 is 66°C-71°C.

[0062] The temperature of the hydrogen outlet of the second heat exchanger 250 is preferably 68°C-70°C.

[0063] Through three steps of pressure reduction, the high-pressure hydrogen is regulated to 0.5 MPa and delivered to downstream users, so that the pressure reduction of the high-pressure hydrogen is more stable, which is beneficial to the utilization of pressure energy and is combined with the slag water treatment system 200.

[0064] In some embodiments, reference Figure 2 A pressure sensor 320 is provided at the outlet end after the first pipeline 110 and the regulating pipeline 140 are connected in parallel. The pressure sensor 320 is electrically connected to the pressure reducing valve 310. The pressure reducing valve 310 adjusts the opening of the pressure reducing valve 310 according to the pressure information detected by the pressure sensor 320 to keep the hydrogen pressure at the outlet end after the first pipeline 110 and the regulating pipeline 140 are connected in parallel balanced.

[0065] Furthermore, a controller is provided, which is a computer. The pressure sensor 320 and the pressure reducing valve 310 are both electrically connected to the computer. The computer is provided with a preset pressure value, and the pressure sensor 320 transmits the detected pressure information to the computer, which compares the pressure information with the preset pressure value. When the detected pressure information is greater than the preset pressure value, the computer controls the pressure reducing valve 310 to reduce the opening; when the detected pressure information is less than the preset pressure value, the computer controls the pressure reducing valve to increase the opening. Thus, the pressure of hydrogen delivered to the downstream by the first pipeline 110 is dynamically balanced at any time to maintain the balance of the output hydrogen pressure.

[0066] In some embodiments, reference Figure 2 A first temperature sensor 330 is provided at the steam outlet end of the third heat exchanger 260, and a first control valve 340 is provided at one end of the circulating water pipe 270 located at the water inlet of the third heat exchanger 260. The first control valve 340 is electrically connected to the first temperature sensor 330. The first control valve 340 adjusts the opening of the first control valve 340 according to the temperature information detected by the first temperature sensor 330 to keep the steam temperature at the steam outlet end of the third heat exchanger 260 stable.

[0067] Furthermore, a third control valve 370 is also provided on the first pipeline 110. The third control valve 370 is located at the air inlet of the first expander 121 to adjust the air intake amount of hydrogen entering the first expansion valve. The third control valve 370 is electrically connected to the first temperature sensor 330. The first control valve 340, the first temperature sensor 330 and the third control valve 370 are all electrically connected to the computer.

[0068] In some embodiments, reference Figure 2 A second temperature sensor 350 is provided at the steam outlet end of the fourth heat exchanger 280, and a second control valve 360 ​​is provided at one end of the circulating water pipe 270 located at the water inlet of the fourth heat exchanger 280. The second control valve 360 ​​is electrically connected to the second temperature sensor 350. The second control valve 360 ​​adjusts the opening of the second control valve 360 ​​according to the temperature information detected by the second temperature sensor 350 to keep the steam temperature at the steam outlet end of the fourth heat exchanger 280 stable.

[0069] The steam temperature at the top outlet of the low-pressure flash tank 220 is 133°C-138°C, and the steam enters the clarification tank after passing through the first heat exchanger 230 and the third heat exchanger 260, and the temperature is controlled at 38°C-42°C.

[0070] The steam temperature at the top outlet of the vacuum flash tank 240 is 76°C-80°C, and the steam enters the clarification tank after passing through the second heat exchanger 250 and the fourth heat exchanger 280, and the temperature is controlled at 38°C-42°C.

[0071] When the hydrogen flow rate is low or the steam flow rate of the low-pressure flash tank 220 is high, the cooling capacity of the expansion process is insufficient, and the opening of the third control valve 370 is increased by the computer first. If the temperature measured by the first temperature sensor 330 is still high after it is fully opened, the opening of the first control valve 340 is increased; at the same time, the opening of the second control valve 360 ​​is increased to ensure that the temperature entering the clarification tank remains stable. When the hydrogen flow rate is high or the steam flow rate of the low-pressure flash tank 220 is low, the cooling capacity of the expansion process is large, and the opening of the first control valve 340 is reduced first. If the temperature measured by the first temperature sensor 330 is still low, the opening of the third control valve 370 is reduced, and the opening of the second control valve 360 ​​is reduced at the same time.

[0072] Specific embodiment: The high-pressure room-temperature hydrogen (25°C) of the gasification device PSA unit (Pressure Swing Adsorption, PSA for short) enters the first expander 121 for expansion and power generation, and the outlet pressure is controlled at 3.5MPa. Then the hydrogen (3°C) enters the first heat exchanger 230, and the low-temperature hydrogen is heated to 125°C by the steam (136°C) at the top of the low-pressure flash tank 220, and then enters the second expander 122 for expansion and power generation, and the outlet pressure is controlled at 1.0MPa. Then the hydrogen (48°C) enters the second heat exchanger 250, and the low-temperature hydrogen is heated to 70°C by the gas phase (80°C) at the top of the vacuum flash tank 240, and then enters the third expander 123 for expansion and power generation, and the outlet pressure is controlled at 0.5MPa to be delivered to downstream users.

[0073] Comparative Example: The biggest difference from the embodiment is that a pressure reducing valve is used instead of an expander to realize the pressure reducing expansion process. Specifically, the high-pressure and room-temperature hydrogen (25°C) of the gasification device PSA unit is directly passed through a pressure reducing valve for pressure reducing expansion, and the outlet pressure is controlled at 0.5MPa. After the slag water passes through the low-pressure flash tank, the top gas phase (136°C) is cooled to 40°C through a heat exchanger, and the bottom liquid phase enters the vacuum flash tank for further flashing, and the top gas phase (80°C) is cooled to 40°C through a heat exchanger and enters the clarification tank together with the liquid phase.

[0074] The examples and comparative examples of the present application were implemented in a gasification device with an effective gas capacity of 180,000 Nm3 / h for comparison.

[0075] Table 1 Comparison table of examples and comparative examples

[0076] Example Comparative Example Power generation per hour kWh 2876 0 Circulating water consumption t / h 1456 1669 Income (10,000 yuan / year) 1483.58 0

[0077] Among them, the price of public works: electricity 0.63 yuan / kWh, circulating water 0.2 yuan / ton, and the annual operation of the device is calculated based on 8,000 hours.

[0078] As can be seen from Table 1, in this embodiment, the circulating water consumption of the gasification device is reduced by 213t / h, and at the same time, the power generation income can be 2876kWh per hour. Compared with the control proportion, the income is 14.8358 million yuan / year, and the energy-saving effect and economic benefits are obvious.

[0079] In the coal gasification energy utilization device provided in the present application, high-pressure hydrogen enters the first expansion machine 121 from the first pipeline 110 for pressure reduction, and drives the first generator 131 to generate electricity through the first expansion machine 121. The hydrogen after preliminary pressure reduction enters the first heat exchanger 230, and exchanges heat with the high-temperature steam generated by the low-pressure flash tank 220 in the slag water treatment system 200 to increase the temperature of the hydrogen, and then enters the second expansion machine 122 for pressure reduction and temperature reduction, so as to drive the second generator 132 to operate and generate electricity through the second expansion machine 122, thereby realizing the synchronous utilization of the pressure energy of the high-pressure hydrogen during the pressure reduction process and the thermal energy in the slag water treatment system 200, thereby reducing the waste of pressure energy and thermal energy.

[0080] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the present application. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0081] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A device for utilizing energy in coal gasification, characterized in that: It comprises a hydrogen pressure reduction system (100) and a slag water treatment system (200); The hydrogen pressure reduction system (100) comprises a first pipeline (110), at least two expanders (120) and at least two generators (130); the first pipeline (110) is used to transport hydrogen generated in coal gasification, and at least two expanders (120) are sequentially connected to the first pipeline (110) to sequentially reduce the pressure of the hydrogen in the first pipeline (110); the generators (120) are connected to the expanders (130) in a one-to-one correspondence; The slag water treatment system (200) comprises a second pipeline (210), a low-pressure flash tank (220) and a first heat exchanger (230); the second pipeline (210) is used to transport the slag water generated in the coal gasification, and the low-pressure flash tank (220) is arranged on the second pipeline (210) to treat the slag water; the first heat exchanger (230) is connected to the steam outlet of the low-pressure flash tank (220), and the first heat exchanger (230) is connected to the first pipeline (110) and is located between the two expanders (120) to transfer the heat of the steam in the low-pressure flash tank (220) to the first pipeline (110).

2. The energy utilization device in coal gasification according to claim 1, characterized in that: The slag water treatment system (200) further comprises a vacuum flash tank (240) and a second heat exchanger (250), wherein the vacuum flash tank (240) is located at the rear end of the low-pressure flash tank (220) and connected to the second pipeline (210), and the second heat exchanger (250) is connected to the steam outlet of the vacuum flash tank (240); The expander (120) includes a first expander (121), a second expander (122), and a third expander (123); the generator includes a first generator (131), a second generator (132), and a third generator (133); the first expander (121), the second expander (122), and the third expander (123) are sequentially arranged on the first pipeline (110); the first generator (131) is connected to the first expander (121); the second generator (122) is connected to the third expander (123); The first heat exchanger (230) is located between the first expander (121) and the second expander (122), and the second heat exchanger (250) is connected to the first pipeline (110) located between the second expander (122) and the third expander (123) so as to transfer the heat of the steam in the vacuum flash tank (240) to the first pipeline (110).

3. The energy utilization device in coal gasification according to claim 2, characterized in that: The slag water treatment system (200) further comprises a third heat exchanger (260) and a circulating water pipe (270), wherein the third heat exchanger (260) is arranged at the steam outlet of the first heat exchanger (230), and the third heat exchanger (260) is used to be connected to the circulating water pipe (270) to transfer the residual heat of the steam in the low-pressure flash tank (220) to the circulating water pipe (270).

4. The energy utilization device in coal gasification according to claim 3, characterized in that: The slag water treatment system (200) further comprises a fourth heat exchanger (280), which is arranged at the steam outlet of the second heat exchanger (250), and the fourth heat exchanger (280) is used to be connected to the circulating water pipe (270) to transfer the residual heat of the steam in the vacuum flash tank (240) to the circulating water pipe (270).

5. The device for utilizing energy in coal gasification according to any one of claims 1 to 4, characterized in that: The hydrogen pressure reduction system (100) further comprises a regulating pipeline (140) connected in parallel with the first pipeline (110), and a pressure reducing valve (310) is provided on the regulating pipeline (140) for replenishing the hydrogen pressure at an end of the first pipeline (110) away from the first expander (121).

6. The device for utilizing energy in coal gasification according to any one of claims 1 to 4, characterized in that: The hydrogen pressure at the outlet of the first expander (121) is 3.0 MPa-3.5 MPa, and the hydrogen temperature at the outlet of the first expander (121) is -6°C-3°C; The temperature of the hydrogen at the outlet of the first heat exchanger (230) is 122°C-127°C.

7. The energy utilization device in coal gasification according to any one of claims 2 to 4, characterized in that: The hydrogen pressure at the outlet of the second expander (122) is 0.9 MPa-1.1 MPa, and the hydrogen temperature at the outlet of the second expander (122) is 46° C.-50° C.; The temperature of the hydrogen at the outlet of the second heat exchanger (250) is 66°C-71°C.

8. The device for utilizing energy in coal gasification according to claim 5, characterized in that: A pressure sensor (320) is provided at the outlet end after the first pipeline (110) and the regulating pipeline (140) are connected in parallel. The pressure sensor (320) is electrically connected to the pressure reducing valve (310). The pressure reducing valve (310) regulates the opening of the pressure reducing valve (310) according to pressure information detected by the pressure sensor (320) so as to keep the hydrogen pressure at the outlet end after the first pipeline (110) and the regulating pipeline (140) are connected in parallel balanced.

9. The device for utilizing energy in coal gasification according to claim 3, characterized in that: A first temperature sensor (330) is provided at the steam outlet end of the third heat exchanger (260), and a first control valve (340) is provided at one end of the circulating water pipe (270) located at the water inlet of the third heat exchanger (260). The first control valve (340) is electrically connected to the first temperature sensor (330). The first control valve (340) regulates the opening of the first control valve (340) according to the temperature information detected by the first temperature sensor (330) to keep the steam temperature at the steam outlet end of the third heat exchanger (260) stable.

10. The device for utilizing energy in coal gasification according to claim 4, characterized in that: A second temperature sensor (350) is provided at the steam outlet end of the fourth heat exchanger (280), and a second control valve (360) is provided at one end of the circulating water pipe (270) located at the water inlet of the fourth heat exchanger (280). The second control valve (360) is electrically connected to the second temperature sensor (350). The second control valve (360) regulates the opening of the second control valve (360) according to the temperature information detected by the second temperature sensor (350) to keep the steam temperature at the steam outlet end of the fourth heat exchanger (280) stable.

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