A thermal mass recovery system and method of operation when a unit FCBs

Abstract

This invention relates to the field of thermal power generation technology, and in particular to a heat and mass recovery system and method for a unit during FCB (Fuel Burner) operation. The system includes a control module 100, a communication module 200, and a distribution and regulation module 300 connected to the turbine unit. The control module 100 releases the working fluid during FCB operation and transmits it to the distribution and regulation module 300 for recovery via the communication module 200. The beneficial effects of this invention are that by recovering the heat and mass during FCB operation, the loss of the unit's working fluid is reduced, and the recovered steam is rationally recycled and utilized, improving the unit's economic efficiency and reducing the risk of short-term water loss.

Description

Technical Field

[0001] This invention relates to the field of thermal power generation technology, and in particular to a heat and mass recovery system and its operating method during the operation of the unit's FCB (Fuel Burner). Background Technology

[0002] FCB (Fast Cut Back) refers to the function of a generator set being disconnected from the power grid due to line faults or power grid failures, instantly removing all external power supply, and rapidly reducing output to maintain its own plant power supply or shutting down the boiler without extinguishing the fire.

[0003] During FCB (Fuel Circuit Breaker) operation, the generator is disconnected from the grid, the turbine and boiler operate normally, the bypass of the operating generator unit is quickly opened, and the boiler rapidly reduces its load to maintain its own power supply (islanding operation). When the bypass capacity of the unit is insufficient, the FCB retrofit of the existing unit can be carried out by adding a PCV valve to quickly release the working fluid, thereby maintaining the stable operation and speed of the turbine.

[0004] However, when the unit's FCB (Fuel Burner) operates under high load, the working fluid release time is prolonged, leading to significant losses of working fluid and heat within the thermal system. Subsequently, if the unit attempts to recover quickly, the severe water loss in the system often hinders the unit's load recovery speed.

[0005] Based on the above problems, we propose a heat and mass recovery system and operating method for unit FCB operation. Summary of the Invention

[0006] In view of the technical problem of significant loss of working fluid and heat during the operation of the unit's FCB, the heat and mass recovery system for unit FCB operation described in this invention is proposed.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a heat and mass recovery system for the operation of the turbine generator set's FCB (Fuel Burner), comprising a control module (100) and a communication module (200) connected to the turbine generator set.

[0008] And the allocation and adjustment module (300);

[0009] The control module (100) releases the working fluid discharged from the unit during FCB operation and transmits it to the distribution and regulation module (300) for recovery through the communication module (200).

[0010] As a preferred embodiment of the heat and mass recovery system when the unit FCB is activated according to the present invention, the control module (100) includes a main steam PCV valve (101) installed on the main steam pipeline of the unit, a superheat PCV valve (102) installed at the inlet of the final stage superheater of the unit, and a cold reheat PCV valve (103) installed on the cold section reheat steam pipeline of the unit.

[0011] As a preferred embodiment of the heat and mass recovery system when the unit's FCB is activated, the system includes: adding an overheat PCV valve (102) or a main steam PCV valve (101) to compensate for insufficient high-pressure bypass capacity of the unit; and adding a cold reheat PCV valve (103) to compensate for insufficient low-pressure bypass capacity of the unit.

[0012] As a preferred embodiment of the heat and mass recovery system during FCB operation of the unit of the present invention, the distribution and regulation module (300) includes a shaft seal steam supply header (301), a shaft seal heater (302), and a condenser (303).

[0013] As a preferred embodiment of the heat and mass recovery system for the unit FCB operation of the present invention, wherein: the connecting module (200) includes a first pipe (201) leading out from the outlet of the main steam PCV valve (101), the first pipe (201) being connected to the shaft seal steam supply header (301), the shaft seal heater (302) and the condenser (303).

[0014] As a preferred embodiment of the heat and mass recovery system when the unit FCB is activated according to the present invention, wherein: the outlet of the superheated PCV valve (102) leads out to a second pipe (202), and the second pipe (202) is connected to the shaft seal steam supply header (301), the shaft seal heater (302), and the condenser (303).

[0015] As a preferred embodiment of the heat and mass recovery system when the unit FCB is activated according to the present invention, wherein: the outlet of the cold reheat PCV valve (103) leads out a third pipe (203), the third pipe (203) is connected to the shaft seal steam supply header (301) and the shaft seal heater (302) and condenser (303).

[0016] As a preferred embodiment of the heat and mass recovery system for the unit FCB operation of the present invention, the interfaces of the first pipe (201), the second pipe (202) and the third pipe (203) are all located after the corresponding PCV valve and before the shut-off valve.

[0017] As a preferred embodiment of the heat and mass recovery system during FCB operation of the unit of the present invention, the first pipe (201), the second pipe (202) and the third pipe (203) are led to the shaft seal heater (302) and the shaft seal steam supply header (301) by a branch pipe (204) before entering the condenser (303), and a valve group (304) is provided on the branch pipe (204).

[0018] To solve the above-mentioned technical problems, the present invention provides the following technical solution: When the FCB is activated, the relevant PCV valves are opened, the released steam is led to the shaft seal steam supply header, the remaining steam is led to the shaft seal heater, and the steam that the shaft seal heater cannot absorb is released to the condenser.

[0019] The beneficial effects of this invention are: by recovering the heat mass during FCB operation, the loss of working fluid in the unit is reduced, and the recovered steam is rationally recycled and utilized, thereby improving the unit's economy and reducing the risk of short-term water loss in the unit. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a diagram of the heat and mass recovery system during the operation of the unit's FCB in this invention.

[0022] Figure 2 This is a flowchart illustrating the system operation method in this invention. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0026] Example 1, referring to Figure 1 This is the first embodiment of the present invention. This embodiment provides a heat and mass recovery system when the unit's FCB is activated, including a control module (100), a communication module (200), and a distribution and regulation module (300) connected to the turbine unit. The control module (100) releases the working fluid discharged from the unit when the FCB is activated, and transmits it to the distribution and regulation module (300) for recovery through the communication module (200).

[0027] Specifically, the control module 100 is responsible for releasing the working fluid in the turbine unit during FCB operation. FCB refers to the islanded operation mode after the unit is disconnected from the grid due to a grid fault, where the operating load is quickly shed to the plant power level. The control module 100 is activated according to the pressure value to quickly release excess steam and prevent the turbine from overspeeding.

[0028] Preferably, the connecting module 200 acts as a bridge between the control module 100 and the distribution and regulation module 300, and is responsible for transmitting the working fluid released during FCB operation, guiding the steam to the distribution and regulation module 300, and ensuring the continuity of steam flow and the sealing of the system.

[0029] In summary, by releasing the working fluid during FCB operation through control module 100 and transmitting it to distribution and regulation module 300 for recovery through connection module 200, the heat and mass recovery system of the turbine unit during FCB operation can be made more efficient, intelligent and safe, and better adaptable to different operating conditions and needs.

[0030] Example 2, refer to Figure 1 This is the second embodiment of the present invention. This embodiment provides a heat and mass recovery system when the unit FCB is activated. The control module (100) includes a main steam PCV valve (101) installed on the main steam pipeline of the unit, a superheat PCV valve (102) installed at the inlet of the final stage superheater of the unit, and a cold reheat PCV valve (103) installed on the cold section reheat steam pipeline of the unit.

[0031] Specifically, an overheat PCV valve (102) or a main steam PCV valve (101) is added to compensate for the insufficient high-pressure bypass capacity of the unit; a cold reheat PCV valve (103) is added to compensate for the insufficient low-pressure bypass capacity of the unit.

[0032] Among them, the main steam PCV valve 101 is installed on the main steam pipeline of the unit. In FCB state, when the high-pressure bypass capacity is insufficient, the main steam PCV valve 101 can be opened quickly to release excess steam and prevent the turbine from overspeeding. The superheat PCV valve 102 is installed at the inlet of the last stage superheater of the unit to control the pressure of superheated steam. When the high-pressure bypass capacity is insufficient, the superheat PCV valve 102 can be opened to release pressure and protect the turbine unit. The cold reheat PCV valve 103 is installed on the cold section reheat steam pipeline to control the pressure of reheat steam. When the low-pressure bypass capacity is insufficient, the cold reheat PCV valve 103 can be opened to release excess steam and maintain system pressure stability.

[0033] Preferably, the distribution and regulation module (300) includes a shaft seal steam supply header (301), a shaft seal heater (302), and a condenser (303).

[0034] Preferably, the communication module (200) includes a first pipe (201) leading out from the outlet of the main steam PCV valve (101), the first pipe (201) being connected to the shaft seal steam supply header (301), the shaft seal heater (302) and the condenser (303).

[0035] Preferably, the outlet of the superheated PCV valve (102) leads to a second pipe (202), which is connected to the shaft seal steam supply header (301), the shaft seal heater (302), and the condenser (303).

[0036] Preferably, a third pipe (203) is led out from the outlet of the cold reheat PCV valve (103), and the third pipe (203) is connected to the shaft seal steam supply header (301), the shaft seal heater (302), and the condenser (303).

[0037] The first pipeline 201 is the main pipeline, leading from the outlet of the main steam PCV valve 101 to the shaft seal steam supply header 301, shaft seal heater 302, and condenser 303. The second pipeline 202 and the third pipeline lead from the outlet of the superheated PCV valve 102 and the outlet of the cold reheat PCV valve 103 to the first pipeline 201, and further to the shaft seal steam supply header 301, shaft seal heater 302, and condenser 303. The condenser 303 is equipped with a second valve group 305 for flow and pressure control. The condenser 303 can increase the absorption capacity of the distribution and regulation module 300. Finally, all excess steam enters the condenser 303 and is discharged when it exceeds the capacity of the condenser 303 (approximately 65% ​​of the main steam volume).

[0038] Preferably, the interfaces of the first pipe (201), the second pipe (202) and the third pipe (203) are all located after the corresponding PCV valve and before the shut-off valve.

[0039] The selection of the pipeline is based on the steam temperature corresponding to the connection location, and the pressure is based on the discharge pressure of the PCV valve outlet, generally 0.2MPa to 0.3MPa. The pipe diameter is calculated based on the parameters corresponding to the temperature and pressure and the pipeline flow velocity. The pipeline interfaces are all located after the corresponding PCV valve and before the shut-off valve, allowing for further control of the steam flow or cutting off the flow when necessary after the PCV valve is opened to discharge the steam.

[0040] Preferably, the first pipe (201), the second pipe (202) and the third pipe (203) are led to the shaft seal heater (302) and the shaft seal steam supply main pipe (301) by a branch pipe (204) before entering the condenser (303), and a valve group (304) is provided on the branch pipe (204).

[0041] The shaft seal steam supply header 301 is used to collect steam from the first pipe 201, the second pipe 202 and the third pipe 203 to provide a stable steam source for the shaft seal system. The shaft seal heater 302 receives steam from the shaft seal steam supply header 301 through the branch pipe 204 to heat the condensate, prevent water from damaging the shaft seal, and recover heat energy. Before entering the shaft seal steam supply header 301, the branch pipe 204 leads the steam to the shaft seal heater 302. A valve group 304 is installed on the branch pipe to control the steam flow and pressure entering the shaft seal heater 302.

[0042] In summary, by adding the first pipe 201, the second pipe 202, and the third pipe 203, the working fluid at the outlet of the main steam PCV valve 101, the superheated PCV valve 102, and the cold reheat PCV valve 103 during FCB operation is recovered, thereby reducing the unit's working fluid loss. Furthermore, after recovering the working fluid during FCB operation, it is utilized in stages for the shaft seal and shaft seal heater 302, thereby improving the unit's economy.

[0043] Example 3, referring to Figure 1 This is the third embodiment of the present invention. This embodiment provides a heat and mass recovery method when the unit's FCB is activated. After the FCB is activated, the power load of the plant equipment is low and the power generation load of the unit is high. It is necessary to quickly release the system steam to avoid the unit overspeeding due to excessive load. The main part of the steam directly enters the boiler reheater through the high-pressure bypass, and the reheat steam directly enters the condenser through the low-pressure bypass. The steam does not do work in the turbine as much as possible. The remaining part of the steam is quickly discharged into the atmosphere through the PCV valve.

[0044] Preferably, when the FCB is activated, all PCV valves are opened, and the released steam is directly led to the shaft seal steam supply header 301 as the shaft seal steam source. Excess steam is led to the shaft seal heater 302 for further utilization.

[0045] In summary, recovering the working fluid during FCB operation and utilizing it in shaft seal 301 and shaft seal heater 302 improves the unit's economy. Furthermore, recovering the working fluid of the entire system reduces the risk of short-term water loss in the unit and improves energy utilization efficiency, which is beneficial for the unit to start up and recover quickly again.

[0046] Example 4, refer to Figure 1 This is the fourth embodiment of the present invention. Taking a 300MW unit as an example, its maximum total PCV discharge is 70% of the THA flow rate, approximately 700t / h. Based on the calculation of 90% of the maximum discharge, the recoverable working mass is:

[0047] 700t / h × 90% = 630t / h

[0048] The PCV remains fully open for 20 seconds during FCB operation, that is:

[0049]

[0050] The total recyclable mass is:

[0051] 630t / h×0.00556h=3.5t=3500kg

[0052] The total recovered heat only considers recovery to the shaft seal heater and shaft seal header (at 5%), and the usable enthalpy difference is considered to be 2700 kJ / kg, which is:

[0053] 3500kg×5%×2700kJ / kg=472.5MJ

[0054] The recovered heat is converted into the amount of standard coal, which has a calorific value of approximately 29.3 MJ / kg. Therefore:

[0055]

[0056] In summary, the FCB (Fuel Burner) operation can significantly recover the heat released by the turbine unit, which not only improves energy efficiency but also helps reduce environmental pollution and operating costs. The recovered heat is equivalent to a certain amount of coal combustion, which is of great significance in energy management and environmental protection.

[0057] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0058] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the best mode of carrying out the invention as currently considered, or those features that are not relevant to implementing the invention) may be omitted.

[0059] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0060] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A heat and mass recovery system during a unit FCB action, characterized in that: include, The control module (100), the communication module (200), and the distribution and regulation module (300) are connected to the steam turbine unit. The control module (100) releases the working fluid discharged from the unit during FCB operation and transmits it to the distribution and regulation module (300) for recovery through the communication module (200); The control module (100) includes a main steam PCV valve (101) installed on the main steam pipeline of the unit, a superheat PCV valve (102) installed at the inlet of the final stage superheater of the unit, and a cold reheat PCV valve (103) installed on the cold section reheat steam pipeline of the unit. The distribution and regulation module (300) includes a shaft seal steam supply header (301), a shaft seal heater (302), and a condenser (303). The connection module (200) includes a first pipe (201) leading out from the outlet of the main steam PCV valve (101), the first pipe (201) being connected to the shaft seal steam supply header (301), the shaft seal heater (302) and the condenser (303). The outlet of the superheated PCV valve (102) leads to a second pipeline (202), which is connected to the shaft seal steam supply header (301), the shaft seal heater (302), and the condenser (303). The outlet of the cold reheat PCV valve (103) leads out a third pipe (203), which is connected to the shaft seal steam supply header (301), the shaft seal heater (302), and the condenser (303). The first pipe (201), the second pipe (202) and the third pipe (203) are led to the shaft seal heater (302) and the shaft seal steam supply header (301) by a branch pipe (204) before entering the condenser (303). A valve group (304) is provided on the branch pipe (204).

2. The heat mass recovery system during a pack FCB action as claimed in claim 1, wherein: Add an overheat PCV valve (102) or a main steam PCV valve (101) to compensate for the insufficient high-pressure bypass capacity of the unit; add a cold reheat PCV valve (103) to compensate for the insufficient low-pressure bypass capacity of the unit.

3. The heat and mass recovery system during a pack FCB action as claimed in claim 2, wherein: The interfaces of the first pipeline (201), the second pipeline (202) and the third pipeline (203) are all located after the corresponding PCV valve and before the shut-off valve.

4. A method for heat and mass recovery during unit FCB operation, characterized in that: Includes the heat and mass recovery system during FCB operation of the unit as described in any of claims 1 to 3; and, When the FCB operates, the relevant PCV valves open, releasing steam to the shaft seal steam supply header. The remaining steam is then directed to the shaft seal heater, and any steam that the shaft seal heater cannot handle is released to the condenser.

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