Heat and mass recovery system during FCB action of unit and working method

Abstract

The invention relates to the technical field of thermal power generation, in particular to a heat and mass recovery system and method during FCB action of a unit, and the heat and mass recovery system comprises a control module 100, a communication module 200 and a distribution and adjustment module 300 which are connected with a steam turbine unit; the control module 100 releases a working medium during FCB operation, and the working medium is transmitted to the distribution and adjustment module 300 through the communication module 200 to be recycled. The method has the beneficial effects that the loss of a working medium of the unit is reduced by recovering the heat mass during FCB operation, the recovered steam is reasonably recycled, the economical efficiency of the unit is improved, and the risk of short-time water loss of the unit is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of thermal power generation, in particular to a heat and mass recovery system and a working method when a unit FCB is in operation. Background Art

[0002] FCB (Fast Cut Back) refers to the function of disconnecting a running generator set from the power grid due to line fault or power grid fault, instantly removing all external power supply, and quickly reducing output to maintain its own power supply or shutting down without stopping the boiler without extinguishing the boiler.

[0003] During the FCB process, the generator is disconnected from the grid, the turbine and boiler operate normally, the bypass of the operating generator set is quickly opened, and the boiler quickly reduces its load, achieving rapid output reduction to maintain its own plant power operation (island operation). When the bypass capacity of the unit is insufficient, the FCB transformation of the existing unit can be carried out by installing a PCV valve to quickly discharge the working fluid, thereby maintaining stable operation and speed of the turbine.

[0004] However, when the unit's load is high before FCB action, the working fluid discharge time is long, which will cause a large amount of working fluid and heat loss in the thermal system. Later, if the unit recovers quickly, the system often loses water seriously, which affects the unit's load recovery speed.

[0005] Based on the above problems, we proposed a heat and mass recovery system and working method when the unit FCB is in action. Summary of the invention

[0006] In view of the technical problem of large amount of working fluid and heat loss in the system when the FCB of the above-mentioned unit is in operation, a heat and mass recovery system for the operation of the FCB of the unit in the present invention is proposed.

[0007] In order to solve the above technical problems, the present invention provides the following technical solution: a heat and mass recovery system when the unit FCB is in operation, comprising a control module (100) connected to the steam turbine unit, a communication module (200)

[0008] and a distribution and regulation module (300);

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

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

[0011] As a preferred solution of the heat and mass recovery system when the FCB of the unit is in operation, an overheating PCV valve (102) or a main steam PCV valve (101) is added to compensate for the insufficient high-pressure bypass capacity of the unit; and a cold re-PCV valve (103) is added to compensate for the insufficient low-pressure bypass capacity of the unit.

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

[0013] As a preferred solution of the heat and mass recovery system of the unit FCB during operation of the present invention, the connecting module (200) includes a first pipeline (201) extending from the outlet of the main steam PCV valve (101), and the first pipeline (201) is connected to the shaft seal steam supply main pipe (301), the shaft seal heater (302) and the condenser (303).

[0014] As a preferred solution of the heat and mass recovery system when the FCB of the unit is in operation, the outlet of the superheated PCV valve (102) leads to a second pipeline (202), and the second pipeline (202) is connected to the shaft seal steam supply main pipe (301) and the shaft seal heater (302) and the condenser (303).

[0015] As a preferred solution of the heat and mass recovery system when the FCB of the unit is in operation, the outlet of the cold re-PCV valve (103) leads to a third pipeline (203), and the third pipeline (203) is connected to the shaft seal steam supply main pipe (301) and the shaft seal heater (302) and the condenser (303).

[0016] As a preferred solution of the heat and mass recovery system when the FCB of the unit is in operation, 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 stop valve.

[0017] As a preferred solution of the heat and mass recovery system when the FCB of the unit of the present invention is in operation, the first pipeline (201), the second pipeline (202) and the third pipeline (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 arranged on the branch pipe (204).

[0018] To solve the above technical problems, the present invention provides the following technical solutions: when the FCB is actuated, the relevant PCV valve is opened, the released steam is led to the shaft seal steam supply main pipe, the remaining steam is led to the shaft seal heater, and the steam that cannot be absorbed by the shaft seal heater is released to the condenser.

[0019] The beneficial effects of the present invention are as follows: by recovering the heat mass during the operation of the FCB, the loss of the unit's working fluid is reduced, and the recovered steam is reasonably recycled and utilized, thereby improving the unit's economy and reducing the risk of short-term water loss in the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0021] Figure 1 This is a diagram of the heat and mass recovery system when the FCB of the unit in the present invention is in operation.

[0022] Figure 2 It is the system working method and flow chart of the present invention. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present 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 term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0026] Example 1, reference Figure 1 , which is the first embodiment of the present invention, and provides a heat and mass recovery system when the unit FCB is in operation, comprising a control module (100) connected to the steam turbine unit, a connection module (200) and a distribution and regulation module (300); the control module (100) releases the working fluid discharged from the unit when the FCB is in operation, and transmits it to the distribution and regulation module (300) through the connection module (200) for recovery.

[0027] Specifically, the control module 100 is responsible for releasing the working fluid in the steam turbine unit under the FCB operating state. FCB refers to the mode of island operation after the unit is disconnected from the power grid after a power grid failure, and the operating load is quickly shed to the plant power level and then the unit operates; the control module 100 is opened according to the pressure value to quickly release excess steam to prevent the steam turbine from overspeeding.

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

[0029] In summary, the working fluid during FCB operation is released through the control module 100 and transmitted to the distribution and regulation module 300 for recovery through the connection module 200, which can make the heat and mass recovery system of the steam turbine unit during FCB operation more efficient, intelligent and safe, and better adapt to different operating conditions and requirements.

[0030] Example 2, reference Figure 1 , which is the second embodiment of the present invention, and provides a heat and mass recovery system when the FCB of the unit is in operation, comprising the control module (100) including a main steam PCV valve (101) arranged on the main steam pipeline of the unit, a superheat PCV valve (102) arranged at the inlet of the last stage superheater of the unit, and a cold reheat PCV valve (103) arranged on the reheat steam pipeline of the cold section of the unit.

[0031] Specifically, an overheating PCV valve (102) or a main steam PCV valve (101) is added to compensate for insufficient high-pressure bypass capacity of the unit; and a cold re-PCV valve (103) is added to compensate for 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 the FCB state, when the high-pressure bypass capacity is insufficient, the main steam PCV valve 101 can be opened quickly to release excess steam to 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 reheated steam. When the low-pressure bypass capacity is insufficient, the cold reheat PCV valve 103 can be opened to release excess steam to maintain system pressure stability.

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

[0034] Preferably, the connecting module (200) comprises a first pipeline (201) extending from an outlet of the main steam PCV valve (101), wherein the first pipeline (201) is connected to the shaft seal steam supply main pipe (301), the shaft seal heater (302) and the condenser (303).

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

[0036] Preferably, the outlet of the cold re-PCV valve (103) leads to a third pipeline (203), and the third pipeline (203) is connected to the shaft seal steam supply mother pipe (301), the shaft seal heater (302) and the condenser (303).

[0037] Among them, the first pipeline 201 is the main pipeline, which is led out from the outlet of the main steam PCV valve 101 to the shaft seal steam supply mother pipe 301, the shaft seal heater 302 and the condenser 303; the second pipeline 202 and the third pipeline are led out from the outlet of the superheated PCV valve 102 and the outlet of the cold re-PCV valve 103 to the first pipeline 201 respectively, and further led out to the shaft seal steam supply mother pipe 301, the shaft seal heater 302 and the condenser 303; a second valve group 305 is provided outside the condenser 303 for flow and pressure control of the condenser 303; the condenser 303 can increase the absorption capacity of the distribution and regulation module 300, and finally all the excess steam enters the condenser 303, and is discharged when it further exceeds the capacity of the condenser 303 (about 65% of the main steam volume).

[0038] Preferably, 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 stop valve.

[0039] Among them, the temperature of the derived pipeline is based on the steam temperature corresponding to the connected position, and its pressure is based on the discharge pressure of the PCV valve outlet, which is generally 0.2MPa~0.3MPa. The pipe diameter is calculated according to the parameters corresponding to the temperature and pressure and the pipeline flow rate; the pipeline interfaces are all located after the corresponding PCV valve and before the stop valve, allowing the stop valve to further control the flow of steam or cut off the flow when necessary after the PCV valve is opened to release the steam.

[0040] Preferably, the first pipeline (201), the second pipeline (202) and the third pipeline (203) are led to the shaft seal heater (302) and the shaft seal steam supply mother 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] Among them, the shaft seal steam supply mother pipe 301 is used to collect steam from the first pipeline 201, the second pipeline 202 and the third pipeline 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 mother pipe 301 through the branch pipe 204, which is used to heat condensate to prevent water from damaging the shaft seal and recover heat energy at the same time; the branch pipe 204 leads the steam to the shaft seal heater 302 before entering the shaft seal steam supply mother pipe 301, and a valve group 304 is arranged on the branch pipe to control the steam flow and pressure entering the shaft seal heater 302.

[0042] In summary, by adding the first pipeline 201, the second pipeline 202 and the third pipeline 203, the working fluid of the main steam PCV valve 101, the outlet of the superheated PCV valve 102 and the cold re-PCV valve 103 during FCB operation is recovered to reduce the working fluid loss of the unit; and after the working fluid during FCB operation is recovered, it is used in the shaft seal and the shaft seal heater 302 in stages to improve the economy of the unit.

[0043] Example 3, reference Figure 1 , which is the third embodiment of the present invention. This embodiment provides a heat and mass recovery method when the FCB of the unit is in action. After the FCB is in action, 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 overload and cause the unit to overspeed. The main part of the steam directly enters the boiler reheater through the high-pressure bypass, and the reheated steam directly enters the condenser through the low-pressure bypass. The steam is not used to 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 actuated, all PCV valves are opened, and the released steam is directly led to the shaft seal steam supply main pipe 301 as the shaft seal steam source, and the excess steam is led to the shaft seal heater 302 for further use.

[0045] In summary, after the working fluid during FCB operation is recovered, it is used in the shaft seal 301 and the shaft seal heater 302 to improve the economy of the unit; and after the working fluid of the entire system is recovered, the risk of short-term water loss of the unit is reduced, and the energy utilization efficiency is improved, which is conducive to the rapid restart and recovery of the unit.

[0046] Example 4, reference Figure 1 , which is the fourth embodiment of the present invention. This embodiment takes a 300MW unit as an example. Its maximum PCV total discharge is 70% of the THA flow, about 700t / h. According to 90% of the maximum discharge that can be recovered, the recoverable quality is:

[0047] 700t / h×90%=630t / h,

[0048] The PCV is 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 is only considered to be recovered to the shaft seal heater and the shaft seal main pipe (considered at 5%), and the available enthalpy difference is considered at 2700kJ / kg, which is:

[0053] 3500kg×5%×2700kJ / kg=472.5MJ

[0054] The recovered heat is converted into the amount of standard coal. The calorific value of standard coal is about 29.3MJ / kg. Therefore:

[0055]

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

[0057] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0058] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0059] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0060] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A heat and mass recovery system for a unit FCB in operation, characterized by: include, A control module (100), a communication module (200) and a distribution and regulation module (300) connected to the steam turbine unit; The control module (100) releases the working fluid discharged from the unit when the FCB is in operation, and transmits it to the distribution and regulation module (300) through the communication module (200) for recovery.

2. The heat and mass recovery system during FCB operation of the unit as claimed in claim 1, characterized in that: The control module (100) comprises a main steam PCV valve (101) arranged on the main steam pipeline of the unit, a superheat PCV valve (102) arranged at the inlet of the final superheater of the unit, and a cold reheat PCV valve (103) arranged on the reheat steam pipeline of the cold section of the unit.

3. The heat and mass recovery system during FCB operation of the unit as claimed in claim 2, characterized in that: An overheating PCV valve (102) or a main steam PCV valve (101) is added to compensate for the insufficient high-pressure bypass capacity of the unit; and a cold re-PCV valve (103) is added to compensate for the insufficient low-pressure bypass capacity of the unit.

4. The heat and mass recovery system during FCB operation of the unit as claimed in claim 3, characterized in that: The distribution and regulation module (300) comprises a shaft seal steam supply main pipe (301), a shaft seal heater (302) and a condenser (303).

5. The heat and mass recovery system during FCB operation of the unit as claimed in claim 4, characterized in that: The communication module (200) comprises a first pipeline (201) extending from an outlet of the main steam PCV valve (101), wherein the first pipeline (201) is connected to the shaft seal steam supply main pipe (301), the shaft seal heater (302) and the condenser (303).

6. The heat and mass recovery system during FCB operation of the unit as claimed in claim 5, characterized in that: The outlet of the superheated PCV valve (102) leads to a second pipeline (202), and the second pipeline (202) is connected to the shaft seal steam supply main pipe (301), the shaft seal heater (302) and the condenser (303).

7. The heat and mass recovery system during FCB operation of the unit as claimed in claim 6, characterized in that: The outlet of the cold re-PCV valve (103) leads to a third pipeline (203), and the third pipeline (203) is connected to the shaft seal steam supply main pipe (301), the shaft seal heater (302) and the condenser (303).

8. The heat and mass recovery system during FCB operation of the unit as claimed in claim 7, characterized in that: 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 stop valve.

9. The heat and mass recovery system during FCB operation of the unit as claimed in claim 8, characterized in that: The first pipeline (201), the second pipeline (202) and the third pipeline (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 arranged on the branch pipe (204).

10. A heat and mass recovery method during FCB operation of a unit, characterized in that: It comprises a heat and mass recovery system when the FCB of the unit is in operation as claimed in any one of claims 1 to 9; and When FCB is actuated, the relevant PCV valve opens, the released steam is led to the shaft seal steam supply main pipe, 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.

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