Gas inlet temperature adjusting method and system for gas-steam combined cycle unit

Abstract

The invention discloses a gas-steam combined cycle unit inlet air temperature adjusting method and system, and the method comprises the steps that closed cold water passes through a heat supply network secondary heat supply network drain cooler and a waste heat utilization driving steam tertiary drain cooler, and low-grade heat is recycled; the low-grade heat is introduced into inlet air of at least one gas compressor through the water-air heat exchanger, and the inlet air temperature of the gas turbine is adjusted. The wasted low-grade heat is utilized to realize the adjustability of the inlet temperature of the gas compressor, and finally, the start-stop operation time of the unit can be shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of surplus energy utilization of energy systems, and in particular to a method and system for regulating air intake temperature of a gas-steam combined cycle unit. Background Art

[0002] The gas-steam combined cycle unit consists of two Mitsubishi M701F4 gas turbines, two waste heat boilers and one heating steam turbine. Each of the two gas turbines and steam turbine is equipped with a generator, and the gas turbine and steam turbine are arranged on separate shafts. Due to the flexible peak-shaving and fast start-stop speed of the gas turbine, the unit needs to be started and stopped frequently to meet the peak-shaving needs of the power grid. The gas turbine compressor inlet temperature is the key factor restricting the start-stop speed of the unit group and the efficiency of the combined cycle. The current technical problems include:

[0003] 1. Currently, there is only a simple external heater heating system at the gas turbine compressor inlet, and the heating efficiency is extremely limited, mainly serving the purpose of melting ice.

[0004] 2. During startup, the low intake air temperature leads to low exhaust temperature of the gas turbine, which indirectly causes the steam parameters of the waste heat boiler to reach the standard slowly. At this time, the steam is recovered through the bypass and enters the condenser, which is equivalent to the single-cycle operation of the gas turbine. The efficiency of the gas turbine on the startup side is greatly reduced, resulting in an overall decrease in the efficiency of the combined cycle during the startup process.

[0005] 3. At startup, according to the government's environmental protection emission requirements, the gas turbine load is not allowed to be greater than 50% of the rated load before the NOx emissions meet the standards during the startup of the gas turbine. The current constraints on the investment in the denitrification system are the pyrolysis furnace outlet temperature and the SCR reactor inlet flue gas temperature, both of which are subject to the exhaust temperature rise rate of the gas turbine.

[0006] 4. During shutdown, the load of the pre-shutdown side gas turbine is subject to the main steam temperature deviation limit during steam degassing, and the steam degassing operation needs to be performed at 145 MW. The amount of steam discharged into the condenser through the bypass is large, resulting in large heat loss. Summary of the invention

[0007] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0008] In view of the above existing problems, the present invention is proposed.

[0009] Therefore, the present invention provides a gas-steam combined cycle unit intake temperature regulation method and system to solve the problems of insufficient intake temperature regulation capability of the current gas turbine system, resulting in low combined cycle efficiency during startup, difficulty in NOx emission control, and large heat loss during shutdown.

[0010] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0011] In a first aspect, the present invention provides a method for adjusting the inlet air temperature of a gas-steam combined cycle unit, comprising:

[0012] The closed cooling water passes through the secondary heat network drain cooler and the waste heat utilization driven steam tertiary drain cooler to recover low-grade heat;

[0013] Low-grade heat is introduced into at least one compressor inlet air through a water-to-air heat exchanger to regulate the turbine inlet air temperature.

[0014] As a preferred solution of the method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to the present invention, wherein:

[0015] The closed cooling water passes through the secondary heat network drain cooler and the waste heat utilization driving steam tertiary drain cooler, including providing heated closed cooling water to the two fuel engines through the closed cooling water circuit led out from the closed cooling water pump outlet mother pipe.

[0016] As a preferred solution of the method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to the present invention, wherein:

[0017] The recovery of low-grade heat includes boosting the pressure of the closed cooling water by a booster pump, passing through a secondary heat network drain cooler and a waste heat-utilizing steam tertiary drain cooler, and exchanging heat between the closed cooling water and the secondary heat network drain and the tertiary steam drain to absorb low-grade heat.

[0018] As a preferred solution of the method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to the present invention, wherein:

[0019] The method of introducing low-grade heat into at least one compressor inlet air through a water-air heat exchanger comprises the following steps:

[0020] The heated cold water is sent to the water-air heat exchanger;

[0021] In the water-to-air heat exchanger, high-temperature closed cooling water exchanges heat with the air before entering the compressor, transferring heat to the air.

[0022] As a preferred solution of the method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to the present invention, wherein:

[0023] The method of introducing low-grade heat into the inlet air of at least one compressor through the water-air heat exchanger also includes returning the closed cooling water that has released heat to the closed cooling water supply main pipe after the heat exchange is completed.

[0024] As a preferred solution of the method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to the present invention, wherein:

[0025] The regulation of the engine intake air temperature includes adjusting the heat value transferred to the air by controlling the working state of the boost pump and the closed cooling water flow parameters.

[0026] As a preferred solution of the method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to the present invention, wherein:

[0027] The step of regulating the engine intake air temperature further comprises:

[0028] When the unit needs to be started quickly, the air preheating speed entering the compressor is accelerated by increasing the closed cooling water temperature in the intake air temperature control system of the two gas turbines;

[0029] When the load needs to be increased quickly, the fuel combustion efficiency is optimized by adjusting the intake air temperature of the two gas turbines to the optimal value;

[0030] When the load needs to be reduced quickly, the temperature of the air entering the compressor can be quickly reduced by lowering the closed cooling water temperature in the intake air temperature control system of the two gas turbines;

[0031] When a gas turbine needs to be shut down quickly, the air preheating speed entering the compressor is accelerated by increasing the closed cooling water temperature in the intake air temperature control system of the other gas turbine that continues to operate;

[0032] When grid demand fluctuates frequently, the air intake temperature of the two gas turbines is adjusted in real time to quickly adapt to different load requirements.

[0033] In a second aspect, the present invention provides an inlet air temperature regulating system for a gas-steam combined cycle unit, comprising:

[0034] The low-grade heat recovery module is used to recover low-grade heat by shutting off cold water through the secondary heat network drain cooler and the waste heat-driven steam tertiary drain cooler;

[0035] The inlet air temperature regulating module is used to introduce low-grade heat into the inlet air of at least one compressor through a water-air heat exchanger to regulate the inlet air temperature of the combustion engine.

[0036] In a third aspect, the present invention provides a computing device, comprising:

[0037] Memory, used to store programs;

[0038] A processor is used to execute the computer executable instructions, which, when executed by the processor, implement the steps of the gas-steam combined cycle unit intake air temperature regulation method.

[0039] In a fourth aspect, the present invention provides a computer-readable storage medium, comprising: when the program is executed by a processor, the steps of implementing the method for adjusting the intake air temperature of a gas-steam combined cycle unit are implemented.

[0040] Beneficial effects of the present invention: The present invention can significantly improve the exhaust parameters of the gas turbine by introducing low-grade heat into the compressor inlet air, thereby improving the thermal efficiency of the entire system. Due to the improvement of the exhaust parameters of the gas turbine, the outlet steam parameters of the waste heat boiler (usually located after the gas turbine exhaust) will also be improved accordingly, further improving the overall efficiency of the system. By improving the exhaust parameters of the gas turbine and the outlet steam parameters of the waste heat boiler, the de-steaming speed and denitrification input speed of the two-to-one gas-steam combined cycle unit can be accelerated, and the start-up and shutdown peak-shaving response speed of the power plant can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0042] Figure 1 A basic flow chart of a method for regulating the inlet air temperature of a gas-steam combined cycle unit provided by one embodiment of the present invention;

[0043] Figure 2 A schematic diagram of a model of a method for regulating the intake air temperature of a gas-steam combined cycle unit provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the above-mentioned purposes, 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 drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0045] 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.

[0046] 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.

[0047] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0048] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0049] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] Example 1

[0051] Reference Figure 1 , as one embodiment of the present invention, provides a method for adjusting the inlet air temperature of a gas-steam combined cycle unit, comprising:

[0052] S1: The closed cooling water passes through the secondary heat network drain cooler and the waste heat utilization driving steam tertiary drain cooler to recover the low-grade heat;

[0053] In an embodiment of the present application, cooling water is drawn from the cooling water pump outlet main pipe, and the cooling water passes through the secondary cooling water cooler of the heat network and the tertiary cooling water cooler of the waste heat utilization driven steam in sequence, absorbs the low-grade heat in these equipments, and outputs the heated cooling water, wherein the process is applicable to the simultaneous operation of at least two fuel engines.

[0054] In the embodiment of the present application, the recovered heat comes from low-grade heat from various locations in the entire combined cycle unit that could not be recovered before, such as closed cooling water, heat network secondary steam trap, etc.

[0055] S2: Low-grade heat is introduced into the inlet air of at least one compressor through a water-to-air heat exchanger to regulate the temperature of the gas turbine inlet air.

[0056] In an embodiment of the present application, the heated closed cooling water enters the water-air heat exchanger, transfers heat to the air entering the compressor, increases the intake air temperature, and the closed cooling water after completing the heat exchange returns to the closed cooling water supply main pipe; the heated intake air enters the compressor, wherein this process is applicable to the simultaneous operation of at least two fuel engines.

[0057] In an embodiment of the present application, heat in the heated closed cooling water is transferred to the air entering the compressor through heat exchange, thereby increasing the intake temperature and thus improving the exhaust parameters and overall efficiency of the gas turbine.

[0058] In the embodiment of the present application, after the heat exchange is completed, the closed cold water that has released all the heat is returned to the closed cold water supply main pipe.

[0059] In the embodiment of the present application, regulating the intake air temperature of the combustion engine includes adjusting the heat value transferred to the air by controlling the working state of the boost pump and the closed cooling water flow parameters.

[0060] In an embodiment of the present application, when the unit needs to be started quickly, the closed cooling water temperature in the intake temperature control system of the two gas turbines is increased to speed up the preheating speed of the air entering each compressor. The system can control the intake heating process of the two gas turbines simultaneously or separately as needed to ensure synchronous start-up or start-up in stages according to actual needs.

[0061] In an embodiment of the present application, when the load needs to be increased rapidly, the fuel combustion efficiency is optimized by coordinating and adjusting the intake temperatures of the two gas turbines to the optimal value; the system can dynamically allocate the workload of the two gas turbines according to the grid load demand to achieve the most efficient power output.

[0062] In an embodiment of the present application, when the load needs to be reduced quickly, the air temperature entering each compressor is quickly reduced by lowering the closed cooling water temperature in the intake temperature control system of the two gas turbines; the system supports reducing the load of one or more gas turbines individually or collectively, and flexibly responding to changes in electricity demand under different circumstances.

[0063] In an embodiment of the present application, when rapid shutdown is required, the air temperature entering each compressor is quickly reduced by lowering the closed cooling water temperature in the intake temperature control system of the two gas turbines; the system can achieve orderly shutdown, ensuring that one of the gas turbines is safely stopped without affecting the normal operation of the other.

[0064] In an embodiment of the present application, when the grid demand fluctuates frequently, the intake air temperature of the two gas turbines is adjusted in real time to quickly adapt to different load requirements; the system has an intelligent control function, which can automatically adjust the intake air temperature of the two gas turbines based on the grid dispatching instructions to ensure the stability and response speed of the system.

[0065] In the embodiment of the present application, low-grade heat is recovered by a high-efficiency heat exchanger and used to pre-cool or heat the air entering the compressor to achieve the optimal operating temperature. This optimized lower intake temperature can increase the combined cycle output total power P1, thereby improving the combined cycle efficiency;

[0066] In the embodiment of the present application, the combined cycle efficiency refers to the ratio of the total power output of the combined cycle to the total heat consumed by natural gas when the gas turbine intake temperature is controlled, expressed as:

[0067]

[0068] Where η c is the combined cycle efficiency, P1 is the total output power of the combined cycle, g is the natural gas consumption, m3 / s; LHV is the lower calorific value of natural gas, which is 34570 kJ / m3.

[0069] In the embodiment of the present application, by reducing the intake air temperature, the efficiency of the combustion engine can be improved. The higher density of cold air allows more air to enter the combustion chamber, thereby increasing the output power P2 of the combustion engine. This helps to improve the energy utilization efficiency of the entire system.

[0070] In the embodiment of the present application, the efficiency of the gas engine refers to the ratio of the output power of the gas engine to the total heat consumed by the natural gas, which is expressed as:

[0071]

[0072] Where η GT is the efficiency of the gas turbine; P2 is the output power of the gas turbine.

[0073] In the embodiment of the present application, by optimizing the intake air temperature, the combined cycle heat rate will decrease, which means that the heat consumed for each 1kW·h of electricity generated is reduced, thus improving energy utilization efficiency and reducing operating costs.

[0074] In the embodiment of the present application, the combined cycle heat rate is defined as the heat consumed per 1kW·h of electrical energy generated, which is an important thermal economy indicator for measuring the intake air temperature control technology, and is expressed as:

[0075]

[0076] In the formula, q e is the combined cycle heat rate, kJ / (kW·h).

[0077] In the embodiment of the present application, by precisely controlling the intake air temperature, the gas turbine can be operated close to its maximum output power, thereby maximizing the gas turbine load rate. This not only improves the flexibility of the system, but also enhances the responsiveness of the system, allowing the power plant to adapt to changes in power demand more quickly.

[0078] In the embodiment of the present application, the engine load rate is defined as the ratio of the engine output power to the maximum power that can be output at the current intake air temperature, expressed as:

[0079]

[0080] In the formula, k p is the engine load rate; Pmax is the maximum power that the engine can output at the current intake temperature, kW.

[0081] In the embodiment of the present application, how to share resources between two gas engines includes system design to support two gas engines to share the same closed cooling water system, and to provide heated closed cooling water to the two gas engines through the closed cooling water circuit drawn from the closed cooling water pump outlet mother pipe. After the closed cooling water passes through the secondary hot network drain cooler and the waste heat utilization driven steam tertiary drain cooler to absorb low-grade heat, it is boosted by a booster pump to ensure sufficient pressure to supply to the two water-air heat exchangers, thereby achieving effective heat distribution. After the heat exchange is completed, the closed cooling water that has released the heat returns to the closed cooling water supply mother pipe, forming a closed loop circulation, thereby improving the efficiency of water resource utilization.

[0082] In an embodiment of the present application, how to synchronously control the intake temperature between the two gas engines includes using a unified control system to synchronously adjust the intake temperature of the two gas engines. The system can monitor and regulate the air temperature before entering each compressor in real time to ensure the optimal operating state of the two gas engines under the same operating conditions. The control system includes but is not limited to setting up multiple temperature sensors for accurately monitoring the temperature changes of each key point, and automatically adjusting the working state of the boost pump and the closed cooling water flow parameters according to a preset algorithm to ensure that the intake temperature of the two gas engines remains consistent or is adjusted differently as needed.

[0083] In the embodiment of the present application, how the two gas turbines can be flexibly adjusted according to changes in grid demand includes the system having the ability to connect to the grid dispatching center, receiving real-time power demand information, and quickly adjusting the working modes of the two gas turbines accordingly. In the case of frequent fluctuations in grid demand, the system can increase or decrease the load by quickly changing the intake temperature, meet the dynamic needs of the power market, and support load sharing strategies. When a single gas turbine is not enough to cope with high loads, the other gas turbine will automatically join the work, and vice versa; when one of them needs maintenance or shutdown, it can seamlessly switch to the other to continue stable power supply.

[0084] In the embodiment of the present application, when the output power of a single gas turbine is insufficient to meet the high load demand of the power grid, the system will automatically activate another standby gas turbine, and coordinate the control of the intake air temperature and fuel supply of the two gas turbines to ensure that the total output power is quickly increased to the required level. Conversely, when the load of the power grid decreases or one gas turbine can bear the load independently, the system will automatically reduce the workload of the second gas turbine or switch it to standby mode to optimize energy efficiency.

[0085] In the embodiment of the present application, an intelligent redundancy mechanism is designed. When one of the gas turbines needs to be shut down due to planned maintenance, fault repair or emergency shutdown, the other gas turbine can immediately take over all loads without affecting the overall power supply stability, thus achieving a seamless transition of power supply. This process is automatically completed by the integrated control system, ensuring that the continuity of power supply of the power grid is not affected and minimizing the impact on the user end.

[0086] In the embodiments of the present application, optimized operations under different working conditions are achieved, for example:

[0087] Quick start: Start two gas turbines simultaneously or separately as needed to reach full power output as quickly as possible.

[0088] Rapidly increase load: Dynamically adjust the fuel input and intake temperature of the two gas turbines according to grid demand to maximize power generation efficiency.

[0089] Rapid load reduction: Reduce the load of one or more gas turbines individually or collectively to flexibly respond to the low period after the peak of electricity consumption.

[0090] Rapid shutdown: Orderly stop of one gas turbine without affecting the normal operation of another, ensuring grid stability.

[0091] When the unit is configured with two units driving one, it is necessary to quickly stop one gas turbine and increase the intake air temperature to ensure smooth degassing at a relatively high steam inlet temperature on the turbine side at low load. For example, under normal circumstances, the unit can degas smoothly at a load of 150MW. By increasing the intake air temperature, the system can still meet the main steam temperature requirements at a load of 90MW, ensuring smooth degassing.

[0092] It should be noted that by optimizing the intake air temperature, not only the overall efficiency of the system is improved, but also the flexibility of the system is enhanced, allowing the power plant to respond more quickly to changes in power demand and reduce pollutant emissions during the start-up and shutdown process. This not only improves the economic benefits of the enterprise, but also enhances environmental benefits and social responsibility.

[0093] It should be noted that according to the inherent characteristics of the gas turbine, the closer the gas turbine is to the temperature control load, the higher the gas turbine first-stage turbine inlet temperature (TIT), the higher the exhaust temperature, and the higher the thermal efficiency of the gas turbine. Because the change in atmospheric ambient temperature has a significant impact on the output and efficiency of the gas turbine, when the gas turbine manufacturer designs, the overall efficiency is basically designed according to the ISO operating conditions or the ambient temperature corresponding to the annual average temperature. When it deviates from the design conditions, the gas turbine will control the gas turbine exhaust temperature through IGV control technology to keep the combined cycle at a higher level. When the ambient temperature deviates too much from the design conditions, the compressor output will deviate from the design conditions by more than 30%. The IGV opening is restricted by factors such as anti-surge and stall. Each gas turbine manufacturer has set a minimum IGV opening. The Mitsubishi M701F4 unit's IGV minimum opening makes the compressor output about 70% of the design output. Therefore, during the low temperature period in winter, when the gas turbine runs below 50% load, the fuel air is relatively small, resulting in low gas turbine exhaust temperature. The turbine parameters cannot be quickly increased to the steam parameters, which restricts the advantage of rapid start-up of the gas turbine.

[0094] It should be noted that the temperature before the gas turbine is determined by the unit load, gas temperature, IGV opening, and compressor inlet temperature. The unit load is determined by the grid dispatch. Among them, the gas temperature is a constant during operation, the IGV opening is automatically controlled by the manufacturer's setting logic, and only the compressor inlet temperature can be adjusted through the inlet heating system. When the temperature control condition is not entered, if the inlet temperature is increased while the load remains unchanged, the temperature before the turbine will increase, the corresponding gas turbine exhaust parameters will increase, and the combined cycle efficiency will increase.

[0095] It should be noted that the intake air heating can be put into operation simultaneously or separately, which is more flexible and requires matching flow and head. If two gas turbines supply steam at the same time, the main steam temperature of the two gas turbines can be quickly matched according to the recent heating start-up or exit of a single gas turbine to achieve the steam paralleling condition, or the intake air heating system can be put into operation to maintain a higher main steam temperature at a lower load to complete the steam decompression.

[0096] This embodiment also provides an inlet air temperature adjustment system for a gas-steam combined cycle unit, comprising:

[0097] The low-grade heat recovery module is used to recover low-grade heat by shutting off cold water through the secondary heat network drain cooler and the waste heat-driven steam tertiary drain cooler;

[0098] The inlet air temperature regulating module is used to introduce low-grade heat into the inlet air of at least one compressor through a water-air heat exchanger to regulate the inlet air temperature of the combustion engine.

[0099] Furthermore, it also includes:

[0100] Memory, used to store programs;

[0101] A processor is used to load the program to execute the method for regulating the intake air temperature of a gas-steam combined cycle unit.

[0102] This embodiment also provides a computer-readable storage medium storing a program, and when the program is executed by a processor, the method for adjusting the intake air temperature of a gas-steam combined cycle unit is implemented.

[0103] The storage medium proposed in this embodiment and the method for regulating the air intake temperature of a gas-steam combined cycle unit proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0104] Through the above description of the implementation methods, the technicians in the relevant field can clearly understand that the present invention can be implemented by means of software and necessary general hardware, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ReadOnly, Memory, ROM), random access memory (RandomAccess Memory, RAM), flash memory (FLASH), hard disk or optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform the methods of various embodiments of the present invention.

[0105] Example 2

[0106] Figure 2 In one embodiment of the present invention, a gas-steam combined cycle unit inlet air temperature control system is provided, comprising a low-grade heat recovery module and an inlet air temperature control module.

[0107] In the embodiment of the present application, the low-grade heat recovery module includes closed cooling water passing through the heat network secondary heat network drain cooler and the waste heat utilization driving steam tertiary drain cooler to recover the low-grade heat;

[0108] In an embodiment of the present application, the intake air temperature adjustment module includes introducing low-grade heat into the inlet air of at least one compressor through a water-air heat exchanger to adjust the intake air temperature of the combustion engine.

[0109] In the embodiment of the present application, the gas-steam combined cycle unit inlet air temperature control system further includes: Figure 2 As shown, the compressor 100, the turbine 200, the combustion chamber 300, the heat network secondary heat network drain cooler 400, the waste heat utilization driving steam tertiary drain cooler 500 and the water-air heat exchanger 600 are composed;

[0110] In the embodiment of the present application, the compressor 100 is connected to the water-air heat exchanger 600, which means that the air is preheated by passing through the water-air heat exchanger before entering the compressor.

[0111] In the embodiment of the present application, the compressor 100 is connected to the combustion chamber 300, and the compressed air and fuel from the compressor 100 pass through the combustion chamber 300 to transfer the high-temperature and high-pressure gas after combustion into the turbine 200. The compressor 100 compresses the external air to increase its pressure and temperature, providing the necessary conditions for the combustion process. The turbine 200 uses the high-temperature and high-pressure gas to drive the turbine to rotate, generate mechanical energy, and drive a generator or other loads.

[0112] In the embodiment of the present application, the combustion chamber 300 is connected to the turbine 200, and the high-temperature and high-pressure gas from the combustion chamber 300 passes through the turbine 200 to discharge the expanded exhaust gas out of the system. The combustion chamber 300 mixes and burns the compressed air with the fuel to generate high-temperature and high-pressure gas to drive the turbine to rotate.

[0113] In the embodiment of the present application, the water-air heat exchanger 600 is connected to the heat network secondary heat network drain cooler 400; the heat network secondary heat network drain cooler 400 is connected to the closed cooling water pump outlet main pipe; the closed cooling water drawn from the closed cooling water pump outlet main pipe first enters the heat network secondary heat network drain cooler 400, the heat network secondary heat network drain cooler 400 is connected to the waste heat utilization driven steam third-level drain cooler 500, and the closed cooling water supply main pipe is connected to the output end of the water-air heat exchanger 600. The heat network secondary heat network drain cooler 400 recovers the low-grade heat in the heat network secondary drain through heat exchange and heats the closed cooling water. The waste heat utilization driven steam third-level drain cooler 500 recovers the low-grade heat in the steam third-level drain through heat exchange and further heats the closed cooling water. The water-air heat exchanger 600 transfers the heat in the heated closed cooling water to the air entering the compressor 100 through heat exchange to increase the intake temperature.

[0114] In the embodiment of the present application, the closed cold water drawn from the closed cold water pump outlet mother pipe first enters the heat network secondary heat network drain cooler 400, where the closed cold water absorbs low-grade heat from the heat network secondary drain, and the temperature rises. The heated closed cold water continues to flow into the waste heat utilization driven steam third-stage drain cooler 500, further absorbing low-grade heat from the steam third-stage drain, and the temperature further rises. After being heated twice, the closed cold water finally enters the water-air heat exchanger 600, transfers heat to the intake air that is about to enter the compressor 100, increases the intake air temperature, and after completing the heat exchange, the closed cold water returns to the closed cold water supply mother pipe to form a closed-loop system.

[0115] Through this connection relationship, the present invention effectively recovers low-grade heat and uses it to increase the inlet temperature of the gas turbine, thereby significantly improving the exhaust parameters and overall efficiency of the gas turbine.

[0116] 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 method for regulating the inlet air temperature of a gas-steam combined cycle unit, characterized in that: include: The closed cooling water passes through the secondary heat network drain cooler and the waste heat utilization driven steam tertiary drain cooler to recover low-grade heat; Low-grade heat is introduced into at least one compressor inlet air through a water-to-air heat exchanger to regulate the turbine inlet air temperature.

2. The method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to claim 1, characterized in that: The closed cooling water passes through the secondary heat network drain cooler and the waste heat utilization driving steam tertiary drain cooler, including providing heated closed cooling water to the two fuel engines through the closed cooling water circuit led out from the closed cooling water pump outlet mother pipe.

3. The method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to claim 1, characterized in that: The recovery of low-grade heat includes boosting the pressure of the closed cooling water by a booster pump, passing through a secondary heat network drain cooler and a waste heat-utilizing steam tertiary drain cooler, and exchanging heat between the closed cooling water and the secondary heat network drain and the tertiary steam drain to absorb low-grade heat.

4. The method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to claim 1 or 2, characterized in that: The method of introducing low-grade heat into at least one compressor inlet air through a water-air heat exchanger comprises the following steps: The heated cold water is sent to the water-air heat exchanger; In the water-to-air heat exchanger, high-temperature closed cooling water exchanges heat with the air before entering the compressor, transferring heat to the air.

5. The method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to claim 3, characterized in that: The method of introducing low-grade heat into the inlet air of at least one compressor through the water-air heat exchanger also includes returning the closed cooling water that has released heat to the closed cooling water supply main pipe after the heat exchange is completed.

6. The method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to claim 5, characterized in that: The regulation of the engine intake air temperature includes adjusting the heat value transferred to the air by controlling the working state of the boost pump and the closed cooling water flow parameters.

7. The method for adjusting the inlet air temperature of a gas-steam combined cycle unit according to claim 6, characterized in that: The step of regulating the engine intake air temperature further comprises: When the unit needs to be started quickly, the air preheating speed entering the compressor is accelerated by increasing the closed cooling water temperature in the intake air temperature control system of the two gas turbines; When the load needs to be increased quickly, the fuel combustion efficiency is optimized by adjusting the intake air temperature of the two gas turbines to the optimal value; When the load needs to be reduced quickly, the temperature of the air entering the compressor can be quickly reduced by lowering the closed cooling water temperature in the intake air temperature control system of the two gas turbines; When a gas turbine needs to be shut down quickly, the air preheating speed entering the compressor is accelerated by increasing the closed cooling water temperature in the intake air temperature control system of the other gas turbine that continues to operate; When the grid demand fluctuates frequently, the inlet air temperature of the two gas turbines is adjusted in real time to quickly adapt to different load requirements; When a single gas turbine cannot independently bear the grid load, the second gas turbine will be automatically started and its working status will be adjusted; When one gas turbine meets the current grid load demand, the second gas turbine is switched to standby mode.

8. A system based on the gas-steam combined cycle unit inlet temperature adjustment method according to claim 1, characterized in that: The low-grade heat recovery module is used to recover low-grade heat by shutting off cold water through the secondary heat network drain cooler and the waste heat-driven steam tertiary drain cooler; The inlet air temperature regulating module is used to introduce low-grade heat into the inlet air of at least one compressor through a water-air heat exchanger to regulate the inlet air temperature of the combustion engine.

9. A computing device, characterized in that include: Memory, used to store programs; A processor is used to load the program to execute the steps of the method for adjusting the intake air temperature of a gas-steam combined cycle unit as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a program, characterized in that: When the program is executed by the processor, the steps of the method for regulating the intake air temperature of a gas-steam combined cycle unit as described in any one of claims 1 to 7 are implemented.

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