Coal-fired power plant coupling coal low-temperature pyrolysis system and method based on steam extraction of steam turbine

Abstract

The invention discloses a coal-fired power plant coupling coal low-temperature pyrolysis system and method based on steam turbine steam extraction, the system comprises a boiler system and a steam turbine system, the steam turbine system comprises a reheat steam pipeline and a steam extraction pipeline, and the steam extraction pipeline is connected with the reheat steam pipeline; the coal pyrolysis system comprises a pyrolysis furnace, a nitrogen conveying system and a first heat exchanger, the nitrogen conveying system is used for conveying nitrogen to the pyrolysis furnace and comprises a conveying pipeline, the conveying pipeline is connected with the pyrolysis furnace, and the first heat exchanger is provided with a first heat exchange channel and a second heat exchange channel which exchange heat with each other; the first heat exchange channel is connected to the steam extraction pipeline in series, the second heat exchange channel is connected to the conveying pipeline in series, and the steam extraction pipeline is configured to heat nitrogen in the conveying pipeline through the first heat exchanger. According to the system disclosed by the invention, the operation stability and economy of the boiler system can be improved while the upgrading utilization of coal is realized under the condition that the deep peak regulation requirement is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coal-fired thermal power generation and coal chemical technology, in particular to a system and method for coupling coal low-temperature pyrolysis based on steam extraction of a steam turbine in a coal-fired power plant. BACKGROUND

[0002] With the implementation of the policy of "carbon peak and carbon neutrality", coal-fired power plants are changing from the original main position of power generation to basic and regulating power sources, and the requirement for deep load regulation of the unit is increasing. Long-term under-load operation of coal-fired units causes energy devaluation due to steam parameter fluctuation, which has a great impact on the economic efficiency of the power plant. SUMMARY

[0003] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a system for coupling coal low-temperature pyrolysis based on steam extraction of a steam turbine in a coal-fired power plant, which can indirectly provide driving force for coal low-temperature pyrolysis by using the heat of steam extraction of the steam turbine unit in the coal-fired power plant, thereby reducing the impact of under-load operation of the coal-fired boiler on the system operation stability and economy, and realizing the upgrading utilization of coal.

[0004] The present application also proposes a method for applying the above-mentioned system for coupling coal low-temperature pyrolysis based on steam extraction of a steam turbine in a coal-fired power plant.

[0005] The system for coupling coal low-temperature pyrolysis based on steam extraction of a steam turbine in a coal-fired power plant according to the first aspect of the present application comprises: a boiler system and a steam turbine system, the steam turbine system comprising a reheated steam pipeline and a steam extraction pipeline, the reheated steam pipeline being used to transport reheated steam from the boiler system to the steam turbine system, and the steam extraction pipeline being connected to the reheated steam pipeline; a coal pyrolysis system, the coal pyrolysis system comprising a pyrolysis furnace, a nitrogen gas delivery system and a first heat exchanger, the nitrogen gas delivery system being used to deliver nitrogen gas to the pyrolysis furnace, the nitrogen gas delivery system comprising a delivery pipeline, the delivery pipeline being connected to the pyrolysis furnace, wherein the first heat exchanger has first and second heat exchange channels that exchange heat with each other, the first heat exchange channel is connected in series to the steam extraction pipeline, the second heat exchange channel is connected in series to the delivery pipeline, and the steam extraction pipeline is configured to heat the nitrogen gas in the delivery pipeline through the first heat exchanger.

[0006] The system for coupling coal low-temperature pyrolysis to a coal-fired power plant based on steam turbine extraction steam according to the present application is provided with a steam turbine system and a coal pyrolysis system, the steam turbine system includes a reheated steam pipeline and an extraction steam pipeline, the coal pyrolysis system includes a pyrolysis furnace, a nitrogen gas delivery system and a first heat exchanger, the extraction steam pipeline is connected to the reheated steam pipeline and in series with a first heat exchange channel of the first heat exchanger, the delivery pipeline of the nitrogen gas delivery system is connected to the pyrolysis furnace and in series with a second heat exchange channel of the first heat exchanger, so that the reheated steam heats the nitrogen gas in the first heat exchanger, and the heated nitrogen gas enters the pyrolysis furnace to provide a strong reducing atmosphere and a heating source for coal pyrolysis, thereby avoiding problems such as water-cooled wall stress fatigue caused by the furnace temperature fluctuation of the boiler in the boiler system, while meeting the need for deep peak regulation, so as to realize the upgrading utilization of coal and improve the operation stability and economy of the boiler system.

[0007] In some embodiments of the present application, the system for coupling coal low-temperature pyrolysis to a coal-fired power plant based on steam turbine extraction steam further includes a feedwater system and a high-pressure heater feed system, the feedwater system is connected to the boiler system and the high-pressure heater feed system, and the extraction steam pipeline is connected to the high-pressure heater feed system.

[0008] In some embodiments of the present application, the nitrogen gas delivery system further includes a nitrogen gas generator connected to the delivery pipeline.

[0009] In some embodiments of the present application, the pyrolysis furnace has a semi-coke outlet and a volatile outlet, and the coal pyrolysis system further includes a semi-coke collection device connected to the semi-coke outlet and a cooling and separating device connected to the volatile outlet.

[0010] In one embodiment of the present application, the cooling and separating device is provided with a pyrolysis oil outlet and a pyrolysis gas outlet, and the coal pyrolysis system further includes a first storage device connected to the pyrolysis oil outlet and a second storage device connected to the pyrolysis gas outlet.

[0011] In one embodiment of the present application, the steam turbine system includes a condensate pipeline connected to the semi-coke collection device to recover heat energy in the semi-coke.

[0012] In some embodiments of the present application, the coal pyrolysis system further includes a coal bunker and a drying and delivery system connected to the outlet of the coal bunker and the inlet of the pyrolysis furnace.

[0013] In some embodiments of the present application, the coal pyrolysis system further includes a heating system arranged in the pyrolysis furnace, and the heating system is used to heat the pyrolysis furnace.

[0014] The method for coupling low-temperature pyrolysis of coal in a coal-fired power plant based on steam turbine extraction according to the second aspect of the present application is applied to the system for coupling low-temperature pyrolysis of coal in a coal-fired power plant based on steam turbine extraction according to the first aspect of the present application, and the method comprises: conveying coal into a pyrolysis furnace; reheating steam to heat nitrogen; conveying the heated nitrogen into the pyrolysis furnace to heat the coal; pyrolyzing the coal in the pyrolysis furnace; and collecting and processing semi-coke and volatile components generated after pyrolysis.

[0015] The method for coupling low-temperature pyrolysis of coal in a coal-fired power plant based on steam turbine extraction according to the present application can well avoid problems such as stress fatigue of water-cooled walls caused by fluctuations in the furnace temperature of a boiler in a boiler system by using reheated steam to heat nitrogen, so that the heated nitrogen can provide a strong reducing atmosphere and a heating source for coal pyrolysis, thereby meeting the need for deep peak shaving while avoiding the above-mentioned problems, and improving the stability and economy of the operation of the boiler system while realizing the upgrading of coal utilization.

[0016] In some embodiments of the present application, after the collecting and processing of semi-coke and volatile components generated after pyrolysis, the method for coupling low-temperature pyrolysis of coal in a coal-fired power plant based on steam turbine extraction further comprises: grinding the semi-coke; mixing the semi-coke with coal conveyed to a boiler system to form a mixed fuel; and conveying the mixed fuel into a boiler of the boiler system.

[0017] Additional aspects and advantages of the present application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a schematic diagram of a system for coupling low-temperature pyrolysis of coal in a coal-fired power plant based on steam turbine extraction according to an embodiment of the present application;

[0019] Figure 2 is a flowchart of a method for coupling low-temperature pyrolysis of coal in a coal-fired power plant based on steam turbine extraction according to an embodiment of the present application;

[0020] Figure 3 is a flowchart of a method for coupling low-temperature pyrolysis of coal in a coal-fired power plant based on steam turbine extraction according to another embodiment of the present application;

[0021] Figure 4 is another flowchart of a method for coupling low-temperature pyrolysis of coal in a coal-fired power plant based on steam turbine extraction according to an embodiment of the present application.

[0022] REFERENCE NUMERALS:

[0023] 11, boiler; 21, reheated steam pipeline; 22, extraction pipeline; 23, high-pressure cylinder; 24, medium-pressure cylinder; 25, low-pressure cylinder;

[0024] 31. First heat exchanger; 32. Conveying pipeline; 33. Nitrogen generator; 34. Pyrolysis furnace; 35. Coal bunker; 36. Drying and conveying system; 37. Heating system; 38. Semi-coke collection device; 39. Cooling and separation device; 301. First storage device; 302. Second storage device;

[0025] 40. Water supply system; 50. High-pressure steam injection system;

[0026] 100. A coal-fired power plant system coupled with low-temperature coal pyrolysis based on steam extraction from a steam turbine. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0028] The following is for reference. Figure 1 A system 100 based on turbine extraction steam and coupled with low-temperature coal pyrolysis in a coal-fired power plant is described according to an embodiment of the first aspect of the present invention.

[0029] like Figure 1 As shown, a coal-fired power plant coupled with low-temperature coal pyrolysis based on turbine extraction steam, according to a first aspect embodiment of the present invention, includes: a boiler system, a turbine system, and a coal pyrolysis system. The turbine system includes a reheat steam pipeline 21 and an extraction steam pipeline 22. The reheat steam pipeline 21 is used to transport reheat steam from the boiler system to the turbine system, and the extraction steam pipeline 22 is connected to the reheat steam pipeline 21. The coal pyrolysis system includes a pyrolysis furnace 34, a nitrogen delivery system, and a first heat exchanger 31. The nitrogen delivery system is used to deliver nitrogen to the pyrolysis furnace 34. The nitrogen delivery system includes a delivery pipeline 32, which is connected to the pyrolysis furnace 34. The first heat exchanger 31 has a first heat exchange channel and a second heat exchange channel that exchange heat with each other. The first heat exchange channel is connected in series with the extraction steam pipeline 22, and the second heat exchange channel is connected in series with the delivery pipeline 32. The extraction steam pipeline 22 is configured to heat the nitrogen in the delivery pipeline 32 through the first heat exchanger 31.

[0030] In this embodiment, the coal-fired power plant coupled with low-temperature coal pyrolysis based on steam extraction from a steam turbine includes a boiler system, a steam turbine system, and a coal pyrolysis system. The boiler system and the steam turbine system work together to meet the power generation needs of the coal-fired power plant. For example, when the coal-fired power plant is running, the boiler system heats water into high-temperature steam, which is then transported to the steam turbine to drive the turbine to operate. This, in turn, causes the turbine to drive a generator to generate electricity, thereby outputting power to the outside world.

[0031] When the coal-fired power plant is deeply peaking, the boiler system is under load operation, and the electric load of the steam turbine system is reduced to achieve deep peaking. Long-term under load operation of the boiler system causes problems such as decrease in combustion stability and decrease in efficiency, thereby reducing the operation stability and economy of the boiler system.

[0032] Coal pyrolysis is an important means of upgrading and utilizing coal. Coal can be converted into tar, pyrolysis gas and semi-coke products through pyrolysis. Tar can be further converted into diesel, gasoline and other chemical raw materials through hydrofining, supplementing the gap of oil resources. Pyrolysis gas can be directly supplied as industrial fuel or synthesized into natural gas, and semi-coke can be further used as clean power generation or gasification raw material.

[0033] It can be understood that heating is required during coal pyrolysis to reach the required temperature for pyrolysis. In this embodiment, an extraction steam pipeline 22 is arranged in the steam turbine system, the extraction steam pipeline 22 is connected with a reheated steam pipeline 21 of the steam turbine system, a pyrolysis furnace 34, a nitrogen delivery system and a first heat exchanger 31 are arranged in the coal pyrolysis system, a delivery pipeline 32 of the nitrogen delivery system is connected with the pyrolysis furnace 34 and is connected in series with a second heat exchange passage of the first heat exchanger 31, and the extraction steam pipeline 22 is connected in series with a first heat exchange passage of the first heat exchanger 31. In the first heat exchanger 31, the reheated steam in the first heat exchange passage can heat the nitrogen in the second heat exchange passage, and the heated nitrogen is delivered along the delivery pipeline 32 to the pyrolysis furnace 34, so that the nitrogen can provide an inert environment for coal pyrolysis after being introduced into the pyrolysis furnace 34, ensure a strong reducing atmosphere for low-temperature pyrolysis of coal, and enable the pyrolysis furnace 34 to operate stably and efficiently, while the heated nitrogen can be used as a heat source of the pyrolysis furnace 34 to heat the coal in the pyrolysis furnace 34. Exemplarily, the extraction steam pipeline 22 can be provided with components such as valves to control steam extraction, and other components on the extraction steam pipeline 22 and the structure thereof can be flexibly arranged as required, which will not be described in detail here.

[0034] When the coal pyrolysis system is operating, the nitrogen is heated by the first heat exchanger 31 and then flows into the pyrolysis furnace 34 to heat the coal in the pyrolysis furnace 34, so that the coal can reach the pyrolysis temperature and be pyrolyzed, and oxygen can be isolated, so that the coal is pyrolyzed in a high-purity nitrogen atmosphere, the chemical reaction path of the coal is clear, and oxidation and combustion side reactions in the coal pyrolysis process are well avoided, thereby ensuring a pure pyrolysis reaction path, reducing the generation of carbon dioxide and making the composition of the product more stable and controllable. At the same time, the semi-coke produced by coal pyrolysis has a more developed pore structure in a nitrogen atmosphere, so that the produced semi-coke can be used as a high-performance electrode material and a catalyst or adsorbent.

[0035] When the coal-fired power plant is deeply peaking, the steam extraction pipeline 22 can extract part of the steam from the reheated steam pipeline 21 for heating nitrogen, and then provide a heat source for the coal pyrolysis system, so as to reduce the output power when the steam turbine is running while keeping the boiler system running normally, and then reduce the power generation of the coal-fired power plant, thereby meeting the needs of deep peaking, thereby shortening or reducing the time of the boiler system running under load, reducing the under-load operation state of the boiler system, so that the boiler system can better maintain a stable operation state and better economic efficiency during long-term operation.

[0036] In this embodiment, the reheated steam is delivered to the first heat exchanger 31 through the steam extraction pipeline 22, and the reheated steam is used to heat nitrogen, and then the heated nitrogen is used to heat the coal to be pyrolyzed in the pyrolysis furnace 34, so that part of the heat generated by the boiler system during operation can be effectively used in the coal pyrolysis system when the coal-fired power plant is deeply peaking, and the heat of the reheated steam can indirectly heat the pyrolysis furnace 34 through nitrogen, so that the reheated steam in the steam extraction pipeline 22 can still flow back to the boiler system after being heated by the nitrogen in the first heat exchanger 31, thereby realizing the circulation of water in the boiler system, reducing the interference of the reheated steam as a heat source to the boiler system when supplying heat to the coal pyrolysis system, and thereby making the boiler system and the coal pyrolysis system operate stably and reliably, thereby improving the operation stability and reliability of the system 100 of coupling coal low-temperature pyrolysis based on steam turbine extraction of the coal-fired power plant to a certain extent.

[0037] In this embodiment, the reheated steam is delivered to the first heat exchanger 31 through the steam extraction pipeline 22, and the reheated steam is used to heat nitrogen, and then the heated nitrogen is used to heat the coal to be pyrolyzed in the pyrolysis furnace 34, so that part of the heat generated by the boiler system during operation can be effectively used in the coal pyrolysis system when the coal-fired power plant is deeply peaking, and the heat of the reheated steam can indirectly heat the pyrolysis furnace 34 through nitrogen, so that the reheated steam in the steam extraction pipeline 22 can still flow back to the boiler system after being heated by the nitrogen in the first heat exchanger 31, thereby realizing the circulation of water in the boiler system, reducing the interference of the reheated steam as a heat source to the boiler system when supplying heat to the coal pyrolysis system, and thereby making the boiler system and the coal pyrolysis system operate stably and reliably, thereby improving the operation stability and reliability of the system 100 of coupling coal low-temperature pyrolysis based on steam turbine extraction of the coal-fired power plant to a certain extent.

[0038] Since the coal pyrolysis system needs to deliver coal to the pyrolysis furnace 34, and the boiler system also needs to supply coal during operation, in this embodiment, the boiler system is coupled with the steam turbine system and the coal pyrolysis system, so that the boiler system and the coal pyrolysis system can use the same coal source, for example, the coal pyrolysis system can use the coal in the coal bunker 35 supplied to the boiler system for coal pyrolysis and upgrading, thereby reducing the transportation cost of the coal required for coal pyrolysis to a certain extent, and making the system 100 of coupling coal low-temperature pyrolysis based on steam turbine extraction of the coal-fired power plant operate more economically.

[0039] The system 100 for coupling coal low-temperature pyrolysis based on steam turbine extraction of a coal-fired power plant according to the embodiment of the present application is provided with a steam turbine system and a coal pyrolysis system. The steam turbine system comprises a reheat steam pipeline 21 and an extraction pipeline 22. The coal pyrolysis system comprises a pyrolysis furnace 34, a nitrogen delivery system, and a first heat exchanger 31. The extraction pipeline 22 is connected with the reheat steam pipeline 21 and in series with a first heat exchange passage of the first heat exchanger 31. The delivery pipeline 32 of the nitrogen delivery system is connected with the pyrolysis furnace 34 and in series with a second heat exchange passage of the first heat exchanger 31. The reheat steam heats the nitrogen in the first heat exchanger 31. The heated nitrogen enters the pyrolysis furnace 34 to provide a strong reducing atmosphere for coal pyrolysis and a heating source. Thus, the problems of water-cooled wall stress fatigue caused by the furnace temperature fluctuation of the boiler 11 in the boiler system can be avoided in the case of meeting the need of deep peak regulation. Thus, the coal upgrading utilization is realized, and the boiler system operation stability and economy are improved.

[0040] In some embodiments of the present application, as shown in Figure 1 The system 100 for coupling coal low-temperature pyrolysis based on steam turbine extraction of a coal-fired power plant can further comprise a feedwater system 40 and a high-pressure heater feed system 50. The feedwater system 40 is connected with the boiler system and the high-pressure heater feed system 50. The extraction pipeline 22 is connected with the high-pressure heater feed system 50.

[0041] In the embodiment, the feedwater system 40 is connected with the boiler system and the high-pressure heater feed system 50. The feedwater system 40 supplies water to the boiler system to meet the operation needs of the boiler system and the steam turbine system. The high-pressure heater feed system 50 is used for heating the feedwater. The extraction pipeline 22 is connected with the high-pressure heater feed system 50. The reheat steam in the extraction pipeline 22 can heat the nitrogen and then enter the high-pressure heater feed system 50 to heat the feedwater. Finally, the water flows to the feedwater system 40 through the deaerator. Thus, the circulation of the water is realized. The waste heat of the reheat steam can be well recycled. Thus, the system 100 for coupling coal low-temperature pyrolysis based on steam turbine extraction of a coal-fired power plant can operate more efficiently and the energy utilization efficiency is higher.

[0042] In some embodiments of the present application, as shown in Figure 1 The nitrogen delivery system can further comprise a nitrogen generator 33 connected with the delivery pipeline 32.

[0043] In the embodiment, the nitrogen delivery system comprises the nitrogen generator 33 connected with the delivery pipeline 32. The structure is simple and can meet the operation needs of the nitrogen delivery system.

[0044] In some embodiments of the present application, as shown in Figure 1As shown, the pyrolysis furnace 34 can have a semi-coke outlet and a volatile outlet, and the coal pyrolysis system can further include a semi-coke collecting device 38 connected to the semi-coke outlet, and a cooling and separating device 39 connected to the volatile outlet.

[0045] In this embodiment, the pyrolysis furnace 34 is provided with a semi-coke outlet and a volatile outlet, and the coal pyrolysis system is further provided with a semi-coke collecting device 38 and a cooling and separating device 39, which can meet the needs of storing and processing the products after coal pyrolysis. The semi-coke generated after coal pyrolysis can be discharged from the semi-coke outlet and recycled and stored by the semi-coke collecting device 38, and the volatiles generated after coal pyrolysis can flow out from the volatile outlet and be transported to the cooling and separating device 39 for cooling and separating treatment, so as to form pyrolysis oil and pyrolysis gas, which are convenient for subsequent processing and use. For example, the pyrolysis gas obtained by the cooling and separating device 39 can be added to the boiler system as fuel as needed, and the pyrolysis oil can be used as a chemical raw material, and the like. In this embodiment, other components of the nitrogen gas delivery system and operations, such as the components for driving pumps, control valves, and the like, to meet the needs of nitrogen gas delivery, are known to those of ordinary skill in the art, and will not be described in detail here.

[0046] In one embodiment of the present application, as shown in Figure 1 The cooling and separating device 39 is provided with a pyrolysis oil outlet and a pyrolysis gas outlet, and the coal pyrolysis system can further include a first storage device 301 connected to the pyrolysis oil outlet and a second storage device 302 connected to the pyrolysis gas outlet.

[0047] In this embodiment, the coal pyrolysis system is provided with the first storage device 301 and the second storage device 302, the first storage device 301 is connected to the pyrolysis oil outlet, and the second storage device 302 is connected to the pyrolysis gas outlet, which has a simple structure and enables the pyrolysis oil and the pyrolysis gas produced after the treatment of the cooling and separating device 39 to be temporarily stored in the first storage device 301 and the second storage device 302 respectively, so that the coal pyrolysis system can be stably and efficiently operated continuously. For example, the first storage device 301 and the second storage device 302 can be tanks or boxes, and the first storage device 301 and the second storage device 302 can be flexibly arranged according to the storage needs.

[0048] Optionally, in one embodiment of the present application, the steam turbine system can include a condensate pipeline connected to the semi-coke collecting device 38 to recover heat energy in the semi-coke.

[0049] The steam turbine system in the embodiment includes a condensate pipeline, which can deliver condensate back to the boiler system, so as to realize the circulating flow of water in the boiler system, the steam turbine system and the feedwater system 40, and meet the operation needs of the boiler system and the steam turbine system. The condensate pipeline is connected with the semi-coke collecting device 38 to recover the heat energy in the semi-coke. For example, the semi-coke collecting device 38 can be provided with a storage cavity for accommodating semi-coke, and the condensate pipeline can pass through the storage cavity, so that the heat of the semi-coke can be transferred to the condensate, thereby recovering and utilizing the heat energy in the semi-coke, making the heat energy more fully recovered and utilized, and making the energy utilization efficiency of the system 100 for coupling the low-temperature pyrolysis of coal based on the steam turbine extraction steam of the coal-fired power plant higher and the operation more efficient.

[0050] In some embodiments of the present application, as shown in Figure 1 The coal pyrolysis system can further include a coal bunker 35 and a drying and conveying system 36 connected with the outlet of the coal bunker 35 and the inlet of the pyrolysis furnace 34.

[0051] The coal pyrolysis system in the embodiment includes a coal bunker 35 and a drying and conveying system 36 connected with the outlet of the coal bunker 35 and the inlet of the pyrolysis furnace 34, which is simple in structure. The coal bunker 35 can supply coal to the pyrolysis furnace 34 to meet the operation needs of the coal pyrolysis system. The coal is conveyed through the drying and conveying system 36, which can dry the coal before conveying it to the pyrolysis furnace 34 to meet the conveying needs of the coal, so as to make the efficiency of the coal pyrolysis in the pyrolysis furnace 34 higher and the quality of the pyrolysis products better.

[0052] In some embodiments of the present application, as shown in Figure 1 The coal pyrolysis system can further include a heating system 37 arranged in the pyrolysis furnace 34 and used for heating the pyrolysis furnace 34.

[0053] The coal pyrolysis system in the embodiment further includes a heating system 37 arranged in the pyrolysis furnace 34 and used for heating the pyrolysis furnace 34, which can improve the stability of the operation of the coal pyrolysis system, so that the heating system 37 can be used as a supplemental heat source when the extraction steam of the extraction pipeline 22 is insufficient. For example, when the boiler system and the steam turbine system are in the peak operation stage, the pyrolysis furnace 34 can be heated by the heating system 37 to supplement the heat required for the coal pyrolysis, so as to make the coal pyrolysis system always maintain a high-efficiency and stable operation state in the long-term operation process, thereby making the system 100 for coupling the low-temperature pyrolysis of coal based on the steam turbine extraction steam of the coal-fired power plant operate more stably and reliably. Exemplarily, the heating system 37 can heat the pyrolysis furnace 34 in an electric heating manner, and the heating system 37 can be provided with electric energy by the coal-fired power plant.

[0054] In an embodiment of the present application, the coal low-temperature pyrolysis system coupled with the coal-fired power plant based on steam extraction of a steam turbine 100 can further comprise an electrical control system, which can be communicatively connected with the drying and conveying system 36, the pyrolysis furnace 34, the cooling and separating device 39, and the semi-coke collecting device 38 in the coal pyrolysis system. In this way, the electrical control system can well control the operation of the coal pyrolysis system. For example, the electrical control system can make corresponding adjustments and controls on the process parameters of the drying and conveying system 36, the pyrolysis furnace 34, the cooling and separating device 39, and the semi-coke collecting device 38 based on the type of coal, so that the coal pyrolysis system can operate more stably and efficiently.

[0055] Reference will be made to Figures 1-4 a method of coal low-temperature pyrolysis coupled with a coal-fired power plant based on steam extraction of a steam turbine according to an embodiment of the second aspect of the present application.

[0056] As Figures 1-4 shown, the method of coal low-temperature pyrolysis coupled with a coal-fired power plant based on steam extraction of a steam turbine according to an embodiment of the present application is applied to the coal low-temperature pyrolysis system coupled with a coal-fired power plant based on steam extraction of a steam turbine 100 according to an embodiment of the first aspect of the present application. The method comprises: conveying coal into the pyrolysis furnace 34; reheating steam to heat nitrogen; conveying the heated nitrogen into the pyrolysis furnace 34 to heat the coal; pyrolyzing the coal in the pyrolysis furnace 34; and collecting and processing the semi-coke and volatile matter generated after pyrolysis.

[0057] The method of coal low-temperature pyrolysis coupled with a coal-fired power plant based on steam extraction of a steam turbine in the present embodiment comprises: conveying coal into the pyrolysis furnace 34; reheating steam to heat nitrogen; conveying the heated nitrogen into the pyrolysis furnace 34 to heat the coal; pyrolyzing the coal in the pyrolysis furnace 34; and collecting and processing the semi-coke and volatile matter generated after pyrolysis. During the operation of the coal low-temperature pyrolysis system coupled with a coal-fired power plant based on steam extraction of a steam turbine 100, the drying and conveying system 36 can convey the coal in the coal bunker 35 into the pyrolysis furnace 34. The nitrogen conveying system conveys the nitrogen generated by the nitrogen generator 33 to the first heat exchanger 31 through the conveying pipeline 32. The steam extraction pipeline 22 extracts steam from the reheated steam pipeline 21 and conveys the reheated steam to the first heat exchanger 31. In the first heat exchanger 31, the reheated steam heats the nitrogen. The heated nitrogen is sent into the pyrolysis furnace 34 along the conveying pipeline 32. The nitrogen heats the coal in the pyrolysis furnace 34, so that the coal is pyrolyzed. The semi-coke generated by the pyrolysis of the coal is discharged from the pyrolysis furnace 34 and collected and processed by the semi-coke collecting device 38. The volatile matter generated by the pyrolysis of the coal is conveyed into the cooling and separating device 39 for cooling and separating treatment, so as to obtain pyrolysis oil and pyrolysis gas. The pyrolysis oil and the pyrolysis gas can be respectively stored by the first storage device 301 and the second storage device 302.

[0058] According to the method for coupling low-temperature coal pyrolysis of a coal-fired power plant based on steam turbine extraction steam provided in the embodiments of the present application, the heated nitrogen gas is introduced into the pyrolysis furnace 34 to provide a strong reducing atmosphere for coal pyrolysis and a heating source, so that the problems of water-cooled wall stress fatigue caused by the furnace temperature fluctuation of the boiler 11 in the boiler system can be avoided in the case of meeting the need for deep peak shaving, thereby realizing the quality upgrading of coal and improving the operation stability and economy of the boiler system.

[0059] In some embodiments of the present application, as shown in Figure 3 After the semi-coke and volatile matter generated after pyrolysis are collected and treated, the method for coupling low-temperature coal pyrolysis of a coal-fired power plant based on steam turbine extraction steam further includes: grinding the semi-coke; mixing the semi-coke with the coal delivered to the boiler system to form a mixed fuel; and delivering the mixed fuel into the boiler 11 of the boiler system.

[0060] In the present embodiment, after the semi-coke and volatile matter generated after pyrolysis are collected and treated, the semi-coke is ground, mixed with the coal delivered to the boiler system to form a mixed fuel, and delivered into the boiler 11 of the boiler system. After the semi-coke is collected by the semi-coke collecting device 38, the ground semi-coke is mixed with the coal delivered to the boiler system and then delivered into the boiler 11 of the boiler system, so as to be used as the fuel required for the operation of the boiler system.

[0061] In the present embodiment, the semi-coke is ground to meet the requirements of the boiler 11 for coal powder combustion, so that the semi-coke can be efficiently and stably combusted in the boiler 11 after being mixed with the coal delivered to the boiler 11. In the present embodiment, the semi-coke mixed with the coal delivered to the boiler 11 is delivered into the boiler 11, so that the semi-coke can replace part of the raw coal as the fuel of the boiler 11, thereby reducing the operation cost of the boiler system to some extent and making the coal resources more fully utilized.

[0062] The system 100 for coupling low-temperature coal pyrolysis of a coal-fired power plant based on steam turbine extraction steam according to one specific embodiment of the present application will be described below with reference to Figure 1

[0063] As shown in Figure 1 The system 100 for coupling low-temperature coal pyrolysis of a coal-fired power plant based on steam turbine extraction steam includes a boiler system, a steam turbine system, a high-pressure heater inlet steam system 50, a coal pyrolysis system, a feedwater system 40, and an electrical control system. The boiler system includes a boiler 11, the steam turbine system includes a reheat steam pipeline 21, an extraction steam pipeline 22, a condensate pipeline, a high-pressure cylinder 23, a medium-pressure cylinder 24, and a low-pressure cylinder 25, and the coal pyrolysis system includes a nitrogen gas delivery system, a first heat exchanger 31, a pyrolysis furnace 34, a coal bunker 35, a drying delivery system 36, a heating system 37, a semi-coke collecting device 38, a cooling and separating device 39, a first storage device 301, and a second storage device 302. ​

[0064] The boiler 11 is used to supply steam and reheat steam to the high pressure cylinder 23, the reheat steam pipeline 21 delivers reheat steam to the medium pressure cylinder 24, the exhaust steam of the medium pressure cylinder 24 is delivered to the low pressure cylinder 25, the exhaust steam of the low pressure cylinder is cooled by the condenser to form condensate water, the condensate water flows to the feed water system 40 along the condensate water pipeline, the feed water system 40 heats the condensate water and delivers it back to the boiler 11, thereby completing the recycling of water.

[0065] The extraction steam pipeline 22 is connected with the reheat steam pipeline 21 and the feed water system 40, the first heat exchange passage of the first heat exchanger 31 is connected in series with the extraction steam pipeline 22, the nitrogen delivery system includes a nitrogen generator 33 and a delivery pipeline 32, the delivery pipeline 32 is connected with the nitrogen generator 33 and the pyrolysis furnace 34, the second heat exchange passage of the first heat exchanger 31 is connected in series with the delivery pipeline 32, the high pressure heater feed system 50 is connected with the extraction steam pipeline 22 and the feed water system 40, and the feed water system 40 is connected with the boiler system. The drying delivery system 36 is connected with the coal bunker 35 and the pyrolysis furnace 34, the semi-coke collecting device 38 is connected with the semi-coke outlet and the volatile outlet of the pyrolysis furnace 34 respectively, the first storage device 301 and the second storage device 302 are connected with the pyrolysis oil outlet and the pyrolysis gas outlet of the cooling separation device 39 respectively, and the heating system 37 is arranged in the pyrolysis furnace 34.

[0066] When the coal-fired power plant is deeply peak-regulated, the extraction steam pipeline 22 can extract steam from the reheat steam pipeline 21 to heat the nitrogen, so that the temperature of the nitrogen can be increased to the temperature required for coal pyrolysis, while the drying delivery system 36 dries the coal in the coal bunker 35 and delivers it to the pyrolysis furnace 34, the nitrogen is introduced into the pyrolysis furnace 34 to heat the coal, so that the coal is pyrolyzed in the pyrolysis furnace 34, the semi-coke produced by the pyrolysis furnace 34 is delivered to the semi-coke collecting device 38, the volatile is delivered to the cooling separation device for cooling and separation, the pyrolysis oil is stored in the first storage device 301, and the pyrolysis gas is stored in the second storage device 302. When the steam turbine system is in the peak period, the heating system 37 can be used as a backup heat source to heat the outer wall of the pyrolysis furnace 34 to supplement the heat required for coal pyrolysis.

[0067] The semi-coke collecting device 38 can be condensed by the condensate water pipeline to recover part of the waste heat in the semi-coke, and the semi-coke can also be ground and mixed with the coal into the boiler 11 to participate in combustion. The other components and operations of the boiler system, the steam turbine system, the coal pyrolysis system, the feed water system 40, the high pressure heater feed system 50 and the electrical control system in this embodiment are known to those skilled in the art, and will not be described in detail here.

[0068] According to an embodiment of the present invention, a coal-fired power plant coupled with low-temperature coal pyrolysis based on turbine extraction steam is provided. By setting up a turbine system and a coal pyrolysis system, the turbine system includes a reheat steam pipeline 21 and an extraction steam pipeline 22, and the coal pyrolysis system includes a pyrolysis furnace 34, a nitrogen conveying system and a first heat exchanger 31. The extraction steam pipeline 22 is connected to the reheat steam pipeline 21 and connected in series with the first heat exchange channel of the first heat exchanger 31. The conveying pipeline 32 of the nitrogen conveying system is connected to the pyrolysis furnace 34 and connected in series with the second heat exchange channel of the first heat exchanger 31, so that the reheat steam heats the nitrogen in the first heat exchanger 31. The heated nitrogen enters the pyrolysis furnace 34 to provide a strong reducing atmosphere and a heating source for coal pyrolysis. In this way, while meeting the needs of deep peak shaving, it can effectively avoid problems such as stress fatigue of the water-cooled wall caused by furnace temperature fluctuations in the boiler 11 in the boiler system, thereby improving the operational stability and economy of the boiler system while realizing the upgrading and utilization of coal.

[0069] The following will refer to Figures 1-4 A method for coupled low-temperature coal pyrolysis in a coal-fired power plant based on steam extraction from a steam turbine, according to a specific embodiment of the present invention, is described.

[0070] like Figures 1-4 As shown, during the operation of the system 100 of a coal-fired power plant coupled with low-temperature coal pyrolysis based on steam extraction from a steam turbine, the drying and conveying system 36 can transport coal in the coal bunker 35 to the pyrolysis furnace 34. The nitrogen conveying system transports nitrogen produced by the nitrogen generator 33 to the first heat exchanger 31 through the conveying pipeline 32. The steam extraction pipeline 22 extracts steam from the reheat steam pipeline 21 and transports the reheat steam to the first heat exchanger 31. In the first heat exchanger 31, the reheat steam heats the nitrogen. The heated nitrogen is sent to the pyrolysis furnace 34 along the conveying pipeline 32. The nitrogen heats the coal in the pyrolysis furnace 34, causing the coal to pyrolyze. The semi-coke produced by the coal pyrolysis is discharged from the pyrolysis furnace 34 and collected and processed by the semi-coke collection device 38. The volatile matter produced by the coal pyrolysis is transported to the cooling and separation device 39 for cooling and separation processing, thereby obtaining pyrolysis oil and pyrolysis gas. The pyrolysis oil and pyrolysis gas can be stored in the first storage device 301 and the second storage device 302, respectively.

[0071] Furthermore, the semi-coke can be ground and mixed with the coal fed to the boiler 11 to form a mixed fuel, which is then supplied to the boiler 11 to participate in the combustion of the boiler system.

[0072] According to the method for coupling coal low-temperature pyrolysis of the coal-fired power plant based on steam turbine extraction steam according to the embodiment of the application, the heated nitrogen enters the pyrolysis furnace 34 to provide a strong reducing atmosphere and a heating source for coal pyrolysis by heating the nitrogen with the reheated steam, so that the problems of water-cooled wall stress fatigue caused by the furnace temperature fluctuation of the boiler 11 in the boiler system can be well avoided under the condition of meeting the need of deep peak regulation, so that the coal upgrading utilization is realized, and the boiler system operation stability and economy are improved.

[0073] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0074] In addition, the terms "first", "second" are only for descriptive purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "plurality" is two or more, unless otherwise specifically limited.

[0075] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection, or communication; can be directly connected, or indirectly connected through an intermediate medium; can be the communication or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0076] In the description of the specification, the description using the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the particular feature, structure, material or characteristic being described is included in at least one embodiment or example of the present application. The illustrative appearances of the above-mentioned terms in various places in the specification are not necessarily referred to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Furthermore, the description herein of certain examples does not necessarily exclude these examples from the scope of the application, and these examples can be combined with each other for the purpose of patentable inventions.

[0077] Although the embodiments of the present application have been shown and described, it would be appreciated by those skilled in the art that changes, modifications, alternatives and variations to these embodiments could be made without departing from the principles and spirit of the application, and the scope of the application is defined by the claims and their equivalents.

Claims

1. A system for coupling coal low-temperature pyrolysis to a coal-fired power plant based on steam turbine extraction steam, characterized in that, The system comprises: a boiler system and a steam turbine system, the steam turbine system comprising a reheat steam pipeline (21) for delivering reheat steam from the boiler system to the steam turbine system, and a steam extraction pipeline (22) connected to the reheat steam pipeline (21); a coal pyrolysis system, the coal pyrolysis system comprising a pyrolysis furnace (34), a nitrogen delivery system for delivering nitrogen to the pyrolysis furnace (34), and a first heat exchanger (31), the nitrogen delivery system comprising a delivery pipeline (32) connected to the pyrolysis furnace (34), wherein the first heat exchanger (31) has first and second heat exchange channels that exchange heat with each other, the first heat exchange channel is connected in series to the steam extraction pipeline (22), and the second heat exchange channel is connected in series to the delivery pipeline (32), and the steam extraction pipeline (22) is configured to heat the nitrogen in the delivery pipeline (32) through the first heat exchanger (31).

2. The system for coupling coal pyrolysis at low temperature to a coal-fired power plant based on steam turbine extraction steam according to claim 1, characterized in that, Further comprising: a feedwater system (40) connected to the boiler system and a high-pressure feedwater heater system (50), and the steam extraction pipeline (22) is connected to the high-pressure feedwater heater system (50).

3. The system of claim 1, wherein the coal pyrolysis is performed at a temperature of 450-550°C. The nitrogen delivery system further comprises a nitrogen generator (33) connected to the delivery pipeline (32).

4. The system of claim 1, wherein the coal pyrolysis is performed at a temperature of 350-550°C. The pyrolysis furnace (34) has a semi-coke outlet and a volatile outlet, and the coal pyrolysis system further comprises: a semi-coke collection device (38) connected to the semi-coke outlet; a cooling and separation device (39) connected to the volatile outlet.

5. The system of claim 4, wherein the coal pyrolysis is performed at a temperature of 450-550°C. The cooling and separation device (39) is provided with a pyrolysis oil outlet and a pyrolysis gas outlet, and the coal pyrolysis system further comprises:

6. The system of claim 4, wherein the coal pyrolysis is performed at a temperature of 450-550°C. a first storage device (301) connected to the pyrolysis oil outlet and a second storage device (302) connected to the pyrolysis gas outlet.

7. The system of claim 1, wherein the coal pyrolysis is performed at a temperature of 350-550°C. The steam turbine system comprises a condensate pipeline connected to the semi-coke collection device (38) to recover heat energy in the semi-coke.

8. The system of claim 1, wherein the coal pyrolysis is performed at a temperature of 350-550°C. The coal pyrolysis system further comprises a coal bin (35) and a drying and delivery system (36) connected to an outlet of the coal bin (35) and an inlet of the pyrolysis furnace (34).

9. A method for coupling coal low temperature pyrolysis to a coal-fired power plant based on steam turbine extraction steam, characterized in that, The coal pyrolysis system further comprises a heating system (37) provided in the pyrolysis furnace (34), and the heating system (37) is configured to heat the pyrolysis furnace (34). The method applied to the system for coupling coal pyrolysis at low temperature based on steam turbine steam extraction of any one of claims 1-8, the method comprising: delivering coal into the pyrolysis furnace (34); heating nitrogen by reheat steam; delivering the heated nitrogen into the pyrolysis furnace (34) to heat the coal; pyrolyzing the coal in the pyrolysis furnace (34); collecting semi-coke and volatiles generated after pyrolysis.

10. The method of coupling coal pyrolysis at low temperature to a coal-fired power plant based on steam turbine extraction steam according to claim 9, characterized in that, After the collection process of the semi-coke and volatile components generated after pyrolysis, the method of coupling coal low-temperature pyrolysis based on steam turbine extraction of a coal-fired power plant further comprises: Grinding the semi-coke; Mixing the semi-coke with coal delivered to the boiler system to form a mixed fuel; The mixed fuel is fed into the boiler (11) of the boiler system.

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