A supercritical CO2 power generation and steam generation system for reducing burnout and dry quenching

Abstract

The invention relates to the technical field of dry coke quenching, and discloses a supercritical CO2 power generation and steam cogeneration system for dry coke quenching with reduced burnout, comprising a dry quenching furnace, a steam drum and a supercritical CO2 boiler, wherein a primary dust collector is arranged at an output port of circulating gas of the dry quenching furnace, and coke powder in the circulating gas is recovered by the primary dust collector, and then the circulating gas passes through an incinerator, a secondary superheater and a primary superheater in sequence, and then enters the supercritical CO2 boiler through a flue; the supercritical CO2 power generation and steam cogeneration system for dry coke quenching with reduced burnout, by arranging an incinerator at the rear end of the primary dust collector, and not incinerating the circulating gas in an annular channel inside the dry quenching furnace, can recover the coke powder in the circulating gas by the primary dust collector, and reduce the content of the coke powder in the circulating gas, thereby reducing the burnout of the coke powder and avoiding a substantial increase in the temperature of the circulating gas.

Description

Technical Field

[0001] The invention relates to the technical field of dry coke quenching, and in particular to a supercritical CO2 power generation and steam cogeneration system for dry coke quenching with reduced burning loss. Background Art

[0002] Supercritical power generation adopts the Brayton cycle, with gas as the working fluid, and achieves efficient energy conversion through four processes: adiabatic compression, isobaric heat absorption, adiabatic expansion and isobaric cooling. Compared with the traditional steam Rankine cycle, the Brayton cycle has a higher cycle efficiency. The power generation efficiency of supercritical CO2 power generation units within 30MW is higher than that of steam power generation.

[0003] When CDQ is actually in operation, the amount of red coke charged is affected by the coke oven production cycle and maintenance, and the amount and temperature of circulating gas will fluctuate. For example, the design value of CDQ coke cooling capacity is 160 tons / hour. In the actual production process, the corresponding circulating air volume is 229,800m 3 / hour. When production fluctuates or CDQ is under maintenance, the CDQ processing capacity drops to 120 tons / hour and the circulating air volume drops to 120,000m 3 / hour. The circulating air volume decreases, and the total amount of heat energy entering the subsequent heat exchange equipment will decrease, affecting the stability of power generation. The rotor speed of supercritical power generation cannot be greatly reduced, and the CO2 flow rate in the supercritical heat exchanger cannot be greatly reduced. This poses a problem of selecting specifications for supercritical power generation and supercritical heat exchangers in the face of reduced operating conditions.

[0004] During the actual operation of CDQ, air needs to be introduced into the annular air duct to burn the combustible gas in the circulating gas, and burn the coke powder together. The coke powder loss can reach 2%. The large amount of coke powder loss not only causes economic losses, but also releases a lot of heat during the combustion of coke powder, causing the circulating gas temperature to rise to over 980℃. If it directly enters the supercritical heat exchanger, it is easy to cause the heat exchanger pipe temperature to be too high and the pipe burst.

[0005] The patent document that has been published, publication number CN212296940U, discloses a supercritical carbon dioxide Brayton cycle power generation system. The patent describes the composition of supercritical carbon dioxide power generation technology, using a heat exchanger to replace the traditional dry coke quenching boiler. However, when the operating conditions of the dry coke quenching change, no countermeasures are taken, and the phenomenon of unstable power generation of the supercritical power generation rotor still exists.

[0006] The patent document that has been published, Publication No. 1, discloses a coke dry quenching system using supercritical carbon dioxide as a circulating gas cooling medium. The document details how to apply a supercritical carbon dioxide boiler to a coke dry quenching system, with the focus on the detailed description of various equipment and processes of supercritical power generation devices. However, for changes in the coke dry quenching operating conditions, the coke dry quenching processing capacity drops to 120 tons / hour, and the circulating air volume drops to 120,000m 3 / , there is no description of the selection of supercritical unit power generation capacity and supercritical heat exchanger selection. Summary of the invention

[0007] In order to solve the problems in the above existing CDQ supercritical CO2 power generation system, the coke powder is seriously burned and the coke powder loss is large. When the CDQ operating conditions fluctuate, the supercritical heat exchanger and the supercritical power generation device are unstable in operation, the present invention is implemented through the following technical scheme: a CDQ supercritical CO2 power generation and steam cogeneration system with reduced burning loss, comprising a CDQ furnace, a steam drum and a supercritical CO2 boiler, a primary dust collector is arranged at the output port of the circulating gas of the CDQ furnace, and the coke powder in the circulating gas is recovered by the primary dust collector, and then the circulating gas passes through the incinerator, the secondary superheater and the primary superheater in sequence, and then enters the supercritical CO2 boiler through the flue;

[0008] The drum is connected to the secondary superheater through a pipeline, and the saturated steam in the drum passes through the secondary superheater and the primary superheater in sequence to form superheated steam, which is then merged into the steam pipe network;

[0009] The circulating gas that has undergone heat exchange in the supercritical CO2 boiler forms a steam-water mixture and then enters the steam drum through a pipeline, and saturated steam is separated from the steam drum.

[0010] Furthermore, the primary dust collector is a double-funnel dust collector.

[0011] Furthermore, after heat exchange in the supercritical CO2 boiler, the circulating gas sequentially enters the bare tube evaporator, the fin evaporator and the steam boiler economizer, and a connecting pipe is provided between the steam boiler economizer and the steam drum.

[0012] Furthermore, the circulating gas output from the steam boiler economizer passes through a secondary dust collector, a circulating fan and a heat pipe economizer in sequence and then returns to the dry quenching furnace.

[0013] Furthermore, the inert gas in the circulating gas is nitrogen.

[0014] The supercritical CO2 power generation and steam cogeneration process for reducing burnout dry quenching includes the following processes:

[0015] S1. Red coke is loaded from the top of the CDQ furnace, and the low-temperature circulating gas absorbs the heat generated by the red coke to form high-temperature gas;

[0016] S2, the high-temperature gas is immersed in the primary dust collector through the output port, and the primary dust collector filters and recovers the coke powder in the high-temperature gas;

[0017] S3, after passing through the primary dust collector, the high-temperature gas enters the incinerator, and air is introduced into the incinerator to burn the hydrogen, carbon monoxide and residual coke powder in the high-temperature gas;

[0018] S4, the high-temperature gas passes through the secondary superheater and the primary superheater in sequence, the saturated steam from the drum passes through the secondary superheater and the primary superheater in sequence, the saturated steam is heated and reduced in pressure to form superheated steam, and then merged into the steam network;

[0019] S5. The supercritical power generation rotor in the supercritical CO2 boiler drives the CO2 circulation, and the circulating gas entering the supercritical CO2 boiler through the flue enters the supercritical CO2 boiler and exchanges heat with the CO2.

[0020] Furthermore, the supercritical CO2 power generation and steam cogeneration process for reducing burnout dry quenching also includes:

[0021] S6. The circulating gas output from the supercritical CO2 boiler passes through the bare tube evaporator, fin evaporator and economizer of the steam boiler in sequence to generate a steam-water mixture, which enters the steam drum through a pipeline;

[0022] S7. The circulating gas leaving the steam boiler enters the secondary dust collector, and then under the action of the circulating fan pressurization, it returns to the CDQ furnace through the heat pipe economizer.

[0023] Furthermore, the low-temperature circulating gas in the CDQ furnace is heated from 130°C to 880°C to form high-temperature gas;

[0024] The content of coke powder in the high temperature gas filtered by the primary dust collector does not exceed 5g / m 3 ;

[0025] After the high-temperature gas is burned in the incinerator, the temperature of the high-temperature gas does not exceed 960°C;

[0026] After the saturated steam in the drum passes through the secondary superheater and the primary superheater, the temperature of the saturated steam rises to 450°C and the pressure decreases from 4.5MPa to 4.2MPa;

[0027] After the circulating gas passes through the supercritical CO2 boiler for heat exchange, the CO2 in the supercritical CO2 boiler is heated to 600°C and the circulating gas is cooled to 500°C;

[0028] The circulating gas passes through the steam boiler's bare tube evaporator, finned evaporator and steam boiler economizer, and the temperature drops to 165°C;

[0029] The circulating gas is pressurized by the circulating fan and then returns to the CDQ furnace through the heat pipe economizer, where the temperature of the circulating gas is reduced to 130°C.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The supercritical CO2 power generation and steam cogeneration system for reducing burnout loss of dry coke quenching, by arranging the incinerator at the rear end of the primary dust collector and not burning the circulating gas in the annular channel inside the dry quenching furnace, can use the primary dust collector to recover the coke powder in the circulating gas and reduce the content of coke powder in the circulating gas, which can reduce the burnout loss of coke powder and avoid a substantial increase in the temperature of the circulating gas.

[0032] 2. The supercritical CO2 power generation and steam cogeneration system for reducing burnout dry quenching, before using the supercritical CO2 heat exchanger for heat exchange, arranges the secondary superheater and the primary heat exchanger of the steam boiler in front of the supercritical CO2 boiler, and arranges the light tube evaporator, fin evaporator and the steam boiler economizer under the supercritical CO2 heat exchanger. The steam boiler load can be reduced to 30% of the design value. The circulating gas is first used to convert the saturated steam into superheated steam. On the one hand, it can realize the conversion of steam and ensure that the steam temperature rises to 450℃ and the steam quality. On the other hand, the supercritical CO2 heat exchanger recovers 880-500℃ heat energy. The amount of dry quenching circulating gas is 120000m 3 / hour -240000m 3 / time, the speed of the supercritical power generation rotor can be slightly reduced, and the carbon dioxide flow rate in the supercritical CO2 heat exchanger can be slightly reduced, so as to ensure the smooth operation of the supercritical CO2 heat exchanger and the supercritical power generation device.

[0033] Secondly, the circulating gas can be kept in a relatively mild operating condition of 880-500℃ in the supercritical CO2 heat exchanger, without over-temperature or tube burst. The material selection requirements of the supercritical CO2 heat exchanger can be reduced, and the low-cost super304H material can be selected to replace expensive steels such as 310S or TP347H. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flow chart of the supercritical CO2 power generation and steam cogeneration system for dry coke quenching of the present invention.

[0035] In the figure: 1. CDQ furnace; 2. Primary dust collector; 3. Incinerator; 4. Secondary superheater; 5. Primary superheater; 6. Flue; 7. Steam drum; 8. Supercritical CO2 boiler; 9. Bare tube evaporator; 10. Finned evaporator; 11. Steam boiler economizer; 12. Secondary dust collector; 13. Circulating fan; 14. Heat pipe economizer. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The embodiment of the supercritical CO2 power generation and steam cogeneration system for reducing burnout dry quenching is as follows:

[0038] See also Figure 1 A supercritical CO2 power generation and steam cogeneration system for reducing burnout dry quenching includes a dry quenching furnace 1, a steam drum 7 and a supercritical CO2 boiler 8. The inert gas in the circulating gas of the system is nitrogen. A primary dust collector 2 is arranged at the output port of the circulating gas of the dry quenching furnace 1. The primary dust collector 2 is a double-funnel dust collector. The double-funnel dust collector uses a fan to continuously exhaust air to form a negative pressure inside the funnel of the dust collector. The circulating gas is drawn to the filter bag. When the circulating gas passes through the filter bag, the coke powder is filtered and recovered by the filter bag. The primary dust collector 2 is used to recover the coke powder in the circulating gas. After that, the circulating gas passes through an incinerator 3, a secondary superheater 4 and a primary superheater 5 in sequence, and then enters the supercritical CO2 boiler 8 through a flue 6. The secondary superheater 4 and the primary superheater 5 are both steam superheaters for further heating the steam from the saturation temperature to the superheated temperature. A water spray desuperheater is arranged between the secondary superheater 4 and the primary superheater 5, and the water spray desuperheater is used to spray water for cooling.

[0039] The steam drum 7 is connected to the secondary superheater 4 through a pipeline. The saturated steam in the steam drum 7 passes through the secondary superheater 4 and the primary superheater 5 in sequence to form superheated steam, which is then merged into the steam network.

[0040] The circulating gas that has undergone heat exchange in the supercritical CO2 boiler 8 forms a steam-water mixture and then enters the steam drum 7 through a pipeline, from which saturated steam is separated.

[0041] After heat exchange in the supercritical CO2 boiler 8, the circulating gas enters the bare tube evaporator 9, the fin evaporator 10 and the steam boiler economizer 11 in sequence. A connecting pipeline is provided between the steam boiler economizer 11 and the steam drum 7. The steam-water mixture generated by the circulating gas passing through the bare tube evaporator 9, the fin evaporator 10 and the steam boiler economizer 11 is transported to the steam drum 7 through the pipeline.

[0042] The circulating gas output from the steam boiler economizer 11 returns to the CDQ furnace 1 through the secondary dust collector 12, the circulating fan 13 and the heat pipe economizer 14 in sequence.

[0043] The supercritical CO2 power generation and steam cogeneration process for reducing burnout dry quenching includes the following processes:

[0044] 1. Inert gas and red coke heat exchange process: This process uses nitrogen as the main component as inert gas to recover the heat generated by the red coke in the dry quenching furnace 1, and the circulating gas is heated from 130°C to 880°C. The annular air duct of the dry quenching furnace 1 will not be incinerated with air, and the combustibles in the circulating gas will not burn in the dry quenching furnace 1, avoiding the combustion of the combustibles in the circulating gas and causing a substantial increase in the temperature of the circulating gas.

[0045] 2. The high temperature circulating gas at 880℃ carries a large amount of coke powder, about 25g / m 3 , enters the primary dust collector 2, and uses the primary dust collector 2 to recover a large amount of coke powder. The coke powder content in the circulating gas drops to below 5g / m3, and then enters the incinerator 3 at the top. Before the circulating gas enters the incinerator 3, the coke powder in the circulating gas is first filtered and recovered. On the one hand, it avoids the incineration of coke powder and reduces the loss of coke powder; on the other hand, it reduces the amount of combustibles in the circulating gas and avoids a substantial increase in the temperature of the circulating gas when the circulating gas burns in the incinerator 3.

[0046] 3. Process of burning combustible components: A portion of air is introduced into the burner 3 at the top to burn hydrogen, carbon monoxide and residual coke powder in the circulating gas, and the circulating gas continues to heat up to a maximum of 960°C. Since the coke powder content in the circulating gas is greatly reduced, the coke powder loss is small, and the circulating gas temperature rises slightly, not exceeding 960°C.

[0047] 4. Superheated steam process: 960℃ circulating gas enters the secondary superheater 4 and primary superheater 5 of the steam boiler to produce superheated steam. The saturated steam from the drum 7 passes through the secondary superheater 4 and primary superheater 5, and the temperature is raised to 450℃, and the pressure is reduced from 4.5MPa to 4.2MPa. The generated superheated steam is incorporated into the steam network for use.

[0048] The amount of CDQ circulating gas is 120000m 3 / hour -240000m 3 / time, the steam boiler secondary superheater 4 and primary heat exchanger 5 are arranged in front of the supercritical CO2 boiler 8, and the heat energy of the high-temperature section of the circulating gas is used to superheat the medium-pressure steam first, ensuring that the steam temperature reaches 450°C. If the supercritical CO2 boiler 8 is placed in front of the steam boiler superheater, when the circulating gas volume changes from 240,000m 3 / h down to 120000m 3 / , the supercritical CO2 boiler 8 will intercept most of the heat of the circulating gas, while the steam boiler obtains too little heat and the steam temperature cannot reach 450℃, which affects the stability of the medium-pressure steam network and reduces the use value of the steam.

[0049] 5. Supercritical process: The supercritical power generation rotor in the supercritical CO2 boiler 8 drives the CO2 circulation, and exchanges heat with the CDQ circulating gas in the supercritical CO2 heat exchanger of the supercritical CO2 boiler 8. The supercritical CO2 is heated to 600°C, and the CDQ circulating gas is reduced from 880°C to 500°C. The supercritical CO2 power generation capacity is 15MW. The supercritical CO2 heat exchanger is a forced circulation heat exchanger. The flow rate of supercritical CO2 in the supercritical CO2 heat exchanger is high, and the flow rate drop cannot exceed 20%. The supercritical CO2 power generation unit is used for CDQ, and the power generation capacity cannot be set to a large power.

[0050] 6. Steam boiler saturated steam process: The circulating gas enters the steam boiler's bare tube evaporator 9, finned evaporator 10, and steam boiler economizer 11 to produce a steam-water mixture. The steam-water mixture passes through the steam drum 7 to separate 4.5MPa saturated steam. The saturated steam passes through the pipeline into the steam boiler's secondary superheater 4 and primary superheater 5, and is heated to 450°C. The circulating gas leaves the steam boiler, the temperature drops to 165°C, and then enters the secondary dust collector 12 for dust removal.

[0051] 7. Pressurization process: The circulating fan 13 pressurizes the circulating gas, and the circulating gas passes through the heat pipe economizer 14, and the circulating gas is reduced to 130° C. The circulating gas returns to the CDQ furnace 1 to continue to exchange heat with the red coke.

[0052] 8. When the CDQ working condition fluctuates, the circulating air volume decreases, and the minimum drops to 120,000m 3 / hour, the supercritical power generation rotor speed is slightly adjusted downward, the adjustment range is less than 20%, and the supercritical power generation rotor speed was 7200 rpm before the reduction. The speed is reduced to 5760 rpm, and the speed no longer decreases. The CO2 flow rate in the supercritical CO2 heat exchanger drops by less than 20%, and the heat exchange capacity decreases slightly, with a decrease of less than 15%. The steam capacity of the steam boiler is greatly adjusted, and the steam capacity is reduced from 60 tons / hour to 25 tons / hour. The steam boiler adopts natural circulation, and the minimum operating load of the boiler can be reduced to 30% of the design value, that is, from 60 tons / hour to 18 tons / hour.

[0053] When the CDQ supercritical CO2 power generation and steam cogeneration system of this embodiment is in operation, the parameters of the CDQ heat exchange part refer to Table 1:

[0054] Table 1

[0055]

[0056] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A supercritical CO2 power generation and steam cogeneration system for reducing burnout dry quenching, comprising a dry quenching furnace (1), a steam drum (7) and a supercritical CO2 boiler (8), characterized in that: A primary dust collector (2) is arranged at the output port of the circulating gas of the dry quenching furnace (1), and the coke powder in the circulating gas is recovered by the primary dust collector (2). The circulating gas then passes through the incinerator (3), the secondary superheater (4) and the primary superheater (5) in sequence, and then enters the supercritical CO2 boiler (8) through the flue (6); The annular air duct of the CDQ furnace (1) will not allow air to be incinerated, and the combustibles in the circulating gas will not burn in the CDQ furnace (1), thereby preventing the combustion of the combustibles in the circulating gas from causing a significant increase in the temperature of the circulating gas; The steam drum (7) is connected to the secondary superheater (4) through a pipeline, and the saturated steam in the steam drum (7) passes through the secondary superheater (4) and the primary superheater (5) in sequence to form superheated steam, which is then merged into the steam pipe network; The circulating gas that has undergone heat exchange in the supercritical CO2 boiler (8) forms a steam-water mixture and then enters the steam drum (7) through a pipeline, and saturated steam is separated from the steam drum (7); After heat exchange in the supercritical CO2 boiler (8), the circulating gas sequentially enters the bare tube evaporator (9), the finned evaporator (10) and the steam boiler economizer (11); a communicating pipe is provided between the steam boiler economizer (11) and the steam drum (7).

2. The supercritical CO2 power generation and steam cogeneration system for reducing burnout dry quenching according to claim 1 is characterized by: The primary dust collector (2) is a double-funnel type dust collector.

3. The supercritical CO2 power generation and steam cogeneration system for reducing burnout dry quenching according to claim 2 is characterized by: The circulating gas output from the steam boiler economizer (11) passes through a secondary dust collector (12), a circulating fan (13) and a heat pipe economizer (14) in sequence and then returns to the dry quenching furnace (1).

4. The supercritical CO2 power generation and steam cogeneration system for reducing burnout dry quenching according to claim 1 is characterized by: The inert gas in the circulating gas is nitrogen.

5. The supercritical CO2 power generation and steam cogeneration system for reducing burnout dry quenching according to claim 3 or 4, characterized in that: It also includes the supercritical CO2 power generation and steam cogeneration process for reducing burnout dry quenching, including the following processes: S1, red coke is loaded from the top of the CDQ furnace (1), and the low-temperature circulating gas absorbs the heat generated by the red coke to form high-temperature gas; S2, the high-temperature gas is immersed in the primary dust collector (2) through the output port, and the primary dust collector (2) filters and recovers the coke powder in the high-temperature gas; S3, after the high-temperature gas passes through the primary dust collector (2), it enters the incinerator (3), air is introduced into the incinerator (3), and hydrogen, carbon monoxide and residual coke powder in the high-temperature gas are burned; S4, the high-temperature gas passes through the secondary superheater (4) and the primary superheater (5) in sequence, the saturated steam from the steam drum (7) passes through the secondary superheater (4) and the primary superheater (5) in sequence, the saturated steam is heated and reduced in pressure to form superheated steam, and then is incorporated into the steam network; S5. The supercritical power generation rotor in the supercritical CO2 boiler (8) drives the CO2 to circulate, and the circulating gas entering the supercritical CO2 boiler (8) through the flue (6) enters the supercritical CO2 boiler (8) to exchange heat with the CO2.

6. The supercritical CO2 power generation and steam cogeneration system for reducing burnout dry quenching according to claim 5 is characterized by: The burn-loss reduction dry quenching supercritical CO2 power generation and steam cogeneration process also includes: S6, the circulating gas output from the supercritical CO2 boiler (8) passes through the bare tube evaporator (9), the finned evaporator (10) and the economizer (11) of the steam boiler in sequence, and generates a steam-water mixture, which enters the steam drum (7) through a pipeline; S7. The circulating gas leaving the steam boiler enters the secondary dust collector (12), and then, under the action of the circulating fan (13) pressurizing, passes through the heat pipe economizer (14) and returns to the CDQ furnace (1).

7. The supercritical CO2 power generation and steam cogeneration system for reducing burnout dry quenching according to claim 6 is characterized by: The low-temperature circulating gas in the dry quenching furnace (1) is heated from 130° C. to 880° C. to form high-temperature gas; The content of coke powder in the high-temperature gas filtered by the primary dust collector (2) does not exceed 5 g / m 3 ; After the high-temperature gas is burned in the incinerator (3), the temperature of the high-temperature gas does not exceed 960° C. After the saturated steam in the steam drum (7) passes through the secondary superheater (4) and the primary superheater (5), the temperature of the saturated steam rises to 450° C. and the pressure decreases from 4.5 MPa to 4.2 MPa; After the circulating gas passes through the supercritical CO2 boiler (8) for heat exchange, the CO2 in the supercritical CO2 boiler (8) is heated to 600° C., and the circulating gas is cooled to 500° C.; The circulating gas passes through the bare tube evaporator (9), the finned evaporator (10) and the steam boiler economizer (11) and the temperature thereof drops to 165°C; The circulating gas is pressurized by the circulating fan (13) and then returns to the dry quenching furnace (1) through the heat pipe economizer (14). The temperature of the circulating gas is reduced to 130°C.

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