Method and system for comprehensive energy utilization of semi-coal waste heat and semi-coal gas boiler

Abstract

The present invention discloses a method and system for the comprehensive energy utilization of blue charcoal waste heat and blue charcoal gas boilers, coupling a blue charcoal waste heat boiler system and a blue charcoal gas boiler unit. The method comprises a blue charcoal gas boiler unit, a carbonization furnace, and a blue charcoal waste heat boiler system. A coupling and decoupling valve group is provided between the blue charcoal waste heat boiler system and the blue charcoal gas boiler unit. The coupling and decoupling valve group is used to achieve coupled operation and decoupled independent operation of the two systems. This method is based on the existing gas boiler, has a relatively simple system and low cost, can significantly reduce the waste of blue charcoal sensible heat, reduce the power generation energy consumption of the blue charcoal tail gas boiler unit, and improve the energy utilization rate in the blue charcoal production process.

Description

Technical Field

[0001] The present invention relates to the field of comprehensive energy recovery and utilization in the coal chemical industry, and in particular to a method and system for comprehensive energy utilization of semi-coke waste heat and semi-coke gas boilers. Background Art

[0002] Currently, the lignite production process reaches temperatures as high as 700°C upon exiting the furnace, primarily through wet quenching. This generates a significant amount of wastewater requiring treatment, consuming significant amounts of new water and electricity, and increasing transportation and drying costs. More importantly, a significant amount of the lignite's sensible heat is wasted and not recycled. Waste heat boilers (HRSs) can effectively utilize the sensible heat of the lignite and rapidly cool it, reducing water consumption and pollution in the production process. However, due to the relatively low temperature and poor heat transfer properties of the lignite, the steam parameters generated by HRSs are relatively low, severely limiting their subsequent utilization. The low-parameter steam generation efficiency is too low, limiting its use to limited industrial steam and heat applications.

[0003] Therefore, developing a more effective method for utilizing the sensible heat of lignite is of great significance to the energy conservation, consumption reduction and sustainable development of lignite enterprises. Summary of the Invention

[0004] In response to the technical problems existing in the existing process of utilizing the waste heat of lignite, the present invention proposes a method and system for comprehensive energy utilization of lignite waste heat and lignite gas boilers by coupling the lignite waste heat boiler system and the lignite gas boiler unit. This method is based on the original gas boiler, and the system is relatively simple and low-cost. It can greatly reduce the waste of sensible heat of lignite, reduce the power generation energy consumption of the lignite tail gas boiler unit, and improve the energy utilization rate in the lignite production process.

[0005] The present invention adopts the following technical solutions:

[0006] A system for comprehensive energy utilization of semi-coal waste heat and semi-coal gas boilers, comprising a semi-coal gas boiler unit, a carbonizing furnace, and a semi-coal waste heat boiler system. The semi-coal waste heat boiler system is installed at the rear of the carbonizing furnace and comprises an evaporator, an economizer, a steam drum, a tubular air preheater, and a main steam pipeline of the semi-coal waste heat boiler system. The main steam pipeline of the semi-coal waste heat boiler system is connected to the evaporator, economizer, and steam drum.

[0007] The semi-coal gas boiler unit includes a furnace, boiler heating surface, steam turbine, condenser, low-pressure heater, deaerator and high-pressure heater. The high-parameter steam generated by heat exchange on the boiler heating surface is transported to the steam turbine for power generation. The exhaust steam from the steam turbine is cooled in the condenser and converted into condensate. After passing through the low-pressure heater, deaerator and high-pressure heater, it enters the boiler for circulation. The tail of the carbonization furnace is connected to the furnace through a pipeline, and the semi-coal tail gas generated in the carbonization furnace is connected to the furnace.

[0008] A set of coupling and decoupling valve groups is set between the semi-coal waste heat boiler system and the semi-coal gas boiler unit. The coupling and decoupling valve group includes valve A, valve B, valve C, valve D and valve E.

[0009] Valve A is connected to the pipeline connecting the main steam pipeline of the semi-coal waste heat boiler system and the main steam pipeline of the semi-coal gas boiler unit after the condenser, valve B is connected to the main steam pipeline of the semi-coal gas boiler unit after the condenser, valve C is connected to the pipeline connecting the deaerator and the main steam pipeline of the semi-coal waste heat boiler system, valve D is connected to the pipeline connecting the low-pressure heater and the main steam pipeline of the semi-coal waste heat boiler system, and valve E is connected to the main steam pipeline of the semi-coal waste heat boiler system.

[0010] Preferably, the carbonization furnace is provided with a scraper and a coke pusher at the bottom of the economizer, and the scraper and the coke pusher push the semi-coke after preliminary cooling into the hopper for accumulation and sedimentation.

[0011] Preferably, the tubular air preheater is arranged in the hopper at the rear of the carbonization furnace, and the blower is connected to the tubular air preheater and, through the tubular air preheater, to the carbonization furnace. The blower sends air into the tubular air preheater to further cool the semi-coke accumulated and settled in the hopper, and the generated hot air is sent to the carbonization furnace for coking, thereby improving combustion efficiency and reducing energy consumption of the carbonization furnace.

[0012] Preferably, an independent cooling water system is provided in the lignite waste heat boiler system, and the cooling water system includes a bypass valve, a plate heat exchanger, and a cooling water tower. The cooling water system is connected in parallel to the main steam pipeline of the lignite waste heat boiler system, and a main valve is provided on the main steam pipeline of the lignite waste heat boiler system.

[0013] Preferably, a semi-coke tail gas cooling and dust removal system is connected to the pipeline connecting the tail end of the carbonization furnace to the furnace.

[0014] Preferably, the condenser includes a low-pressure cylinder and a high-pressure cylinder. The steam after work in the high-pressure cylinder returns to the boiler heating surface for heating or is connected to the high-pressure heater. The steam after work in the low-pressure cylinder enters the condenser, the low-pressure heater or the deaerator.

[0015] Preferably, an electro-hydraulic gate valve is provided at the bottom of the economizer.

[0016] The method for the comprehensive energy utilization of the semi-coke waste heat and semi-coke gas boiler comprises the following steps:

[0017] S1. The carbonization furnace produces semi-coke tail gas and high-temperature semi-coke. The semi-coke tail gas is treated by the semi-coke tail gas cooling and dust removal system and then sent to the semi-coke gas boiler unit furnace for combustion. High-parameter steam is generated by the boiler heating surface and enters the steam turbine for power generation. The exhaust steam of the steam turbine is condensed by the condenser and controlled by the valve. The condensed water enters the semi-coke waste heat boiler system. The semi-coke waste heat boiler system is equipped with an economizer and evaporator in the carbonization furnace. The condensed water is heated by the economizer and then sent to the steam drum. The hot water in the steam drum is heated by the evaporator to become a steam-water mixture and then returned to the steam drum for steam-water separation. The separated saturated steam is returned to the low-pressure heater and deaerator of the semi-coke gas boiler unit through a valve. At this time, the low-pressure heater and deaerator do not need to extract steam from the steam turbine, ensuring the efficiency of the steam turbine.

[0018] S2. The semi-coke waste heat boiler system is equipped with a tubular air preheater in the hopper at the tail end of the carbonization furnace. The semi-coke, after preliminary cooling by the evaporator and economizer, accumulates and settles in the hopper and is further cooled to about 80°C by the air preheater. The cooled semi-coke can be directly stored and transported, while the heated air is sent to the carbonization furnace for low-temperature dry distillation of coal, reducing the energy consumption of the carbonization furnace.

[0019] S3. When the boiler unit needs to be shut down, adjust the coupling and decoupling valve group, close valves A, C, and D, decouple the semi-coal gas boiler unit from the semi-coal waste heat boiler system, and open valve E. At this time, the semi-coal waste heat boiler system operates independently, and the condensed water is circulated in a closed loop. After being heated by the economizer and evaporator arranged in the carbonization furnace, it enters the plate heat exchanger in the independent cooling water system through the opened valve for heat exchange, and then enters the carbonization furnace to cool the semi-coal. The independent cooling water system is equipped with a cooling tower to release the heat in the system;

[0020] S4. When the carbonization furnace needs to be shut down, the gas for the semi-coal gas boiler unit is provided by the gas tank or other carbonization furnace. The two systems are decoupled through the coupling and decoupling valve group. Valves A, C, and D are closed, and valve B is opened. The condensed water directly enters the low-pressure heater and deaerator, and is heated and deoxidized by steam extracted from the steam turbine. At this time, the carbonization furnace, semi-coal waste heat boiler system, and independent cooling water system are all shut down.

[0021] S5. When the semi-coke waste heat boiler system stops operating for some reason or encounters an emergency, the electro-hydraulic plug valve is activated as an emergency measure to spray and cool down the high-temperature semi-coke to prevent the semi-coke production from being interrupted for some reason and ensure the normal and safe operation of the carbonization furnace.

[0022] The beneficial effects of the present invention are:

[0023] (1) The temperature of the semi-coke is relatively high (~700°C) when it is taken out of the furnace. The present invention cools the high-temperature semi-coke to about 150°C by heat exchange with the evaporator and economizer of the semi-coke waste heat boiler system, and then cools the semi-coke to about 80°C by heat exchange with the tubular air preheater. This facilitates the transportation of the semi-coke, eliminates the spray cooling, sewage treatment and drying processes of the semi-coke, saves resource consumption, and reduces energy consumption in subsequent processes.

[0024] (2) The present invention utilizes the waste heat of semi-coke to generate steam, which is then transported to the steam-water system of the semi-coke tail gas boiler unit that utilizes the by-product tail gas of semi-coke to generate electricity for circulation. The coupling of the two improves the recovery efficiency of the semi-coke waste heat and also reduces the power generation energy consumption of the gas boiler unit.

[0025] (3) The tubular air preheater in the semi-coke waste heat boiler system of the present invention utilizes the waste heat of semi-coke to generate hot air and transports it to the carbonization furnace, thereby improving the combustion efficiency and reducing the energy consumption of the carbonization furnace in producing semi-coke;

[0026] (4) The present invention sets up an independent cooling system for the semi-coal waste heat boiler, which ensures that the semi-coal waste heat boiler can operate independently when the gas boiler unit is shut down, and the closed circulation of the working fluid can maintain the water quality requirements, avoiding the corrosion of the hot surface of the semi-coal waste heat boiler, and greatly reducing the operation and maintenance costs;

[0027] (4) The method and system of the present invention are simple to operate, highly economical and relatively low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the present invention;

[0029] 100. Carbonization furnace, 101. Electro-hydraulic gate valve, 102. Coke pusher, 103. Hopper;

[0030] 200. Semi-coal gas boiler unit, 201. Furnace, 202. Boiler heating surface, 203. Steam turbine, 204. Condenser, 205. Low-pressure heater, 206. Deaerator, 207. High-pressure heater;

[0031] 300. Semi-coal waste heat boiler system, 301. Economizer, 302. Evaporator, 303. Steam drum, 304. Tubular air preheater;

[0032] 400. Independent cooling water system, 401. Plate heat exchanger, 402. Cooling water tower, 403. Bypass valve;

[0033] 500, coupling and decoupling valve group, 501, valve A, 502, valve B, 503, valve C, 504, valve D, 505, valve E;

[0034] 600. Semi-coke tail gas cooling and dust removal system. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0036] Example: Figure 1 As shown, a system for comprehensive energy utilization of semi-coal waste heat and semi-coal gas boiler includes a semi-coal gas boiler unit 200, a carbonization furnace 100 and a semi-coal waste heat boiler system 300. The semi-coal waste heat boiler system is installed at the rear of the carbonization furnace and includes an evaporator 302, an economizer 301, a steam drum 303, a tubular air preheater 304 and a main steam pipeline of the semi-coal waste heat boiler system. The main steam pipeline of the semi-coal waste heat boiler system connects the evaporator, economizer and steam drum.

[0037] The semi-coal gas boiler unit includes a furnace 201, a boiler heating surface 202, a steam turbine 203, a condenser 204, a low-pressure heater 205, a deaerator 206, and a high-pressure heater 207. The high-parameter steam generated by heat exchange on the boiler heating surface is transported to the steam turbine for power generation. The exhaust steam from the steam turbine is cooled in the condenser and converted into condensate. The condensate then passes through the low-pressure heater, deaerator, and high-pressure heater and enters the boiler for circulation. The tail of the carbonization furnace is connected to the furnace through a pipeline, and the semi-coal tail gas generated in the carbonization furnace is connected to the furnace.

[0038] A set of coupling and decoupling valve group 500 is set between the semi-coal waste heat boiler system and the semi-coal gas boiler unit. The coupling and decoupling valve group includes valve A501, valve B502, valve C503, valve D504 and valve E505.

[0039] Valve A is connected to the pipeline connecting the main steam pipeline of the semi-coal waste heat boiler system and the main steam pipeline of the semi-coal gas boiler unit after the condenser, valve B is connected to the main steam pipeline of the semi-coal gas boiler unit after the condenser, valve C is connected to the pipeline connecting the deaerator and the main steam pipeline of the semi-coal waste heat boiler system, valve D is connected to the pipeline connecting the low-pressure heater and the main steam pipeline of the semi-coal waste heat boiler system, and valve E is connected to the main steam pipeline of the semi-coal waste heat boiler system.

[0040] The carbonization furnace is located at the bottom of the economizer and a scraper and a coke pusher 102 are set. The scraper and the coke pusher push the semi-coke after preliminary cooling into the hopper 103 for accumulation and sedimentation.

[0041] The tubular air preheater is located in the hopper at the rear of the carbonization furnace. The blower is connected to the tubular air preheater and, through it, to the carbonization furnace. The blower sends air into the tubular air preheater, further cooling the semi-coke accumulated in the hopper. The resulting hot air is then fed into the carbonization furnace for coking, improving combustion efficiency and reducing energy consumption.

[0042] An independent cooling water system 400 is set up in the semi-coal waste heat boiler system. The cooling water system includes a bypass valve 403, a plate heat exchanger 401, and a cooling water tower 402. The cooling water system is connected in parallel to the main steam pipeline of the semi-coal waste heat boiler system. A main valve is set on the main steam pipeline of the semi-coal waste heat boiler system.

[0043] The pipe connecting the tail end of the carbonization furnace to the furnace is connected to a blue carbon tail gas cooling and dust removal system 600.

[0044] The condenser consists of a low-pressure cylinder and a high-pressure cylinder. Steam from the high-pressure cylinder returns to the boiler's heating surface for heating or is connected to the high-pressure heater. Steam from the low-pressure cylinder enters the condenser, the low-pressure heater, or the deaerator. An electro-hydraulic gate valve 101 is installed at the bottom of the economizer.

[0045] The method for the comprehensive energy utilization of the semi-coke waste heat and semi-coke gas boiler comprises the following steps:

[0046] S1. The carbonization furnace produces semi-coke tail gas and high-temperature semi-coke. The semi-coke tail gas is treated by the semi-coke tail gas cooling and dust removal system and then sent to the semi-coke gas boiler unit furnace for combustion. High-parameter steam is generated by the boiler heating surface and enters the steam turbine for power generation. The exhaust steam of the steam turbine is condensed by the condenser and controlled by the valve. The condensed water enters the semi-coke waste heat boiler system. The semi-coke waste heat boiler system is equipped with an economizer and evaporator in the carbonization furnace. The condensed water is heated by the economizer and then sent to the steam drum. The hot water in the steam drum is heated by the evaporator to become a steam-water mixture and then returned to the steam drum for steam-water separation. The separated saturated steam is returned to the low-pressure heater and deaerator of the semi-coke gas boiler unit through a valve. At this time, the low-pressure heater and deaerator do not need to extract steam from the steam turbine, ensuring the efficiency of the steam turbine.

[0047] S2. The semi-coke waste heat boiler system is equipped with a tubular air preheater in the hopper at the tail end of the carbonization furnace. The semi-coke, after preliminary cooling by the evaporator and economizer, accumulates and settles in the hopper and is further cooled to about 80°C by the air preheater. The cooled semi-coke can be directly stored and transported, while the heated air is sent to the carbonization furnace for low-temperature dry distillation of coal, reducing the energy consumption of the carbonization furnace.

[0048] S3. When the boiler unit needs to be shut down, adjust the coupling and decoupling valve group, close valves A, C, and D, decouple the semi-coal gas boiler unit from the semi-coal waste heat boiler system, and open valve E. At this time, the semi-coal waste heat boiler system operates independently, and the condensed water is circulated in a closed loop. After being heated by the economizer and evaporator arranged in the carbonization furnace, it enters the plate heat exchanger in the independent cooling water system through the opened valve for heat exchange, and then enters the carbonization furnace to cool the semi-coal. The independent cooling water system is equipped with a cooling tower to release the heat in the system;

[0049] S4. When the carbonization furnace needs to be shut down, the gas for the semi-coal gas boiler unit is provided by the gas tank or other carbonization furnace. The two systems are decoupled through the coupling and decoupling valve group. Valves A, C, and D are closed, and valve B is opened. The condensed water directly enters the low-pressure heater and deaerator, and is heated and deoxidized by steam extracted from the steam turbine. At this time, the carbonization furnace, semi-coal waste heat boiler system, and independent cooling water system are all shut down.

[0050] S5. When the semi-coke waste heat boiler system stops operating for some reason or encounters an emergency, the electro-hydraulic plug valve is activated as an emergency measure to spray and cool down the high-temperature semi-coke to prevent the semi-coke production from being interrupted for some reason and ensure the normal and safe operation of the carbonization furnace.

[0051] The embodiment described above is only a preferred solution of the present invention and does not limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solution described in the claims.

Claims

1. A system for comprehensive energy utilization of semi-coal waste heat and semi-coal gas boiler, characterized by: It includes a semi-coal gas boiler unit, a carbonizing furnace and a semi-coal waste heat boiler system. The semi-coal waste heat boiler system is installed at the rear of the carbonizing furnace and includes an evaporator, an economizer, a steam drum, a tubular air preheater and a main steam pipeline of the semi-coal waste heat boiler system. The main steam pipeline of the semi-coal waste heat boiler system connects the evaporator, economizer and steam drum. The semi-coal gas boiler unit includes a furnace, boiler heating surface, steam turbine, condenser, low-pressure heater, deaerator and high-pressure heater. The high-parameter steam generated by heat exchange on the boiler heating surface is transported to the steam turbine for power generation. The exhaust steam from the steam turbine is cooled in the condenser and converted into condensate. After passing through the low-pressure heater, deaerator and high-pressure heater, it enters the boiler for circulation. The tail of the carbonization furnace is connected to the furnace through a pipeline, and the semi-coal tail gas generated in the carbonization furnace is connected to the furnace. A set of coupling and decoupling valve groups is set between the semi-coal waste heat boiler system and the semi-coal gas boiler unit. The coupling and decoupling valve group includes valve A, valve B, valve C, valve D and valve E. Valve A is connected to the pipeline connecting the main steam pipeline of the semi-coal waste heat boiler system and the main steam pipeline of the semi-coal gas boiler unit after the condenser; valve B is connected to the main steam pipeline of the semi-coal gas boiler unit after the condenser; valve C is connected to the pipeline connecting the deaerator and the main steam pipeline of the semi-coal waste heat boiler system; valve D is connected to the pipeline connecting the low-pressure heater and the main steam pipeline of the semi-coal waste heat boiler system; valve E is connected to the main steam pipeline of the semi-coal waste heat boiler system; The tubular air preheater is arranged in the hopper at the rear of the carbonization furnace, and the blower is connected to the tubular air preheater and is connected to the carbonization furnace through the tubular air preheater; An independent cooling water system is provided in the blue coal waste heat boiler system. The cooling water system includes a bypass valve, a plate heat exchanger, and a cooling water tower. The cooling water system is connected in parallel to the main steam pipeline of the blue coal waste heat boiler system. A main valve is provided on the main steam pipeline of the blue coal waste heat boiler system.

2. The system for comprehensive energy utilization of semi-coal waste heat and semi-coal gas boiler according to claim 1 is characterized in that: The carbonization furnace is provided with a scraper and a coke pusher at the bottom of the economizer, and the scraper and the coke pusher push the semi-coke after preliminary cooling into the hopper for accumulation and sedimentation.

3. The system for comprehensive energy utilization of semi-coal waste heat and semi-coal gas boiler according to claim 1 is characterized in that: The pipe connecting the tail end of the carbonization furnace to the furnace is connected to a blue carbon tail gas cooling and dust removal system.

4. The system for comprehensive energy utilization of semi-coal waste heat and semi-coal gas boiler according to claim 1 is characterized in that: The condenser includes a low-pressure cylinder and a high-pressure cylinder. The steam after work in the high-pressure cylinder returns to the boiler heating surface for heating or is connected to the high-pressure heater. The steam after work in the low-pressure cylinder enters the condenser, the low-pressure heater or the deaerator.

5. The system for comprehensive energy utilization of semi-coal waste heat and semi-coal gas boiler according to claim 1 is characterized in that: An electro-hydraulic plug valve is provided at the bottom of the economizer.

6. A method for comprehensive energy utilization of semi-coal waste heat and semi-coal gas boiler according to any one of claims 1 to 5, characterized in that: The method steps are: S1. The carbonization furnace produces semi-coke tail gas and high-temperature semi-coke. The semi-coke tail gas is treated by the semi-coke tail gas cooling and dust removal system and then sent to the semi-coke gas boiler unit furnace for combustion. High-parameter steam is generated by the boiler heating surface and enters the steam turbine for power generation. The exhaust steam of the steam turbine is condensed by the condenser and controlled by the valve. The condensed water enters the semi-coke waste heat boiler system. The semi-coke waste heat boiler system is equipped with an economizer and evaporator in the carbonization furnace. The condensed water is heated by the economizer and then sent to the steam drum. The hot water in the steam drum is heated by the evaporator to become a steam-water mixture and then returned to the steam drum for steam-water separation. The separated saturated steam is returned to the low-pressure heater and deaerator of the semi-coke gas boiler unit through a valve. At this time, the low-pressure heater and deaerator do not need to extract steam from the steam turbine, ensuring the efficiency of the steam turbine. S2. The semi-coke waste heat boiler system is equipped with a tubular air preheater in the hopper at the tail end of the carbonization furnace. The semi-coke, after preliminary cooling by the evaporator and economizer, accumulates and settles in the hopper and is further cooled to about 80°C by the air preheater. The cooled semi-coke is directly stored and transported, while the heated air is sent to the carbonization furnace for low-temperature dry distillation of coal, reducing the energy consumption of the carbonization furnace. S3. When the boiler unit needs to be shut down, adjust the coupling and decoupling valve group, close valves A, C, and D, decouple the semi-coal gas boiler unit from the semi-coal waste heat boiler system, and open valve E. At this time, the semi-coal waste heat boiler system operates independently, and the condensed water is circulated in a closed loop. After being heated by the economizer and evaporator arranged in the carbonization furnace, it enters the plate heat exchanger in the independent cooling water system through the opened valve for heat exchange, and then enters the carbonization furnace to cool the semi-coal. The independent cooling water system is equipped with a cooling tower to release the heat in the system; S4. When the carbonization furnace needs to be shut down, the gas for the semi-coal gas boiler unit is provided by the gas tank or other carbonization furnace. The two systems are decoupled through the coupling and decoupling valve group. Valves A, C, and D are closed, and valve B is opened. The condensed water directly enters the low-pressure heater and deaerator, and is heated and deoxidized by steam extracted from the steam turbine. At this time, the carbonization furnace, semi-coal waste heat boiler system, and independent cooling water system are all shut down. S5. When the semi-coke waste heat boiler system stops operating for some reason or encounters an emergency, the electro-hydraulic plug valve is activated as an emergency measure to spray and cool down the high-temperature semi-coke to prevent the semi-coke production from being interrupted for some reason and ensure the normal and safe operation of the carbonization furnace.

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