Power plant centrifugal air compressor compression heat coupling utilization system

Abstract

The utility model discloses a power plant centrifugal air compressor compression thermal coupling utilization system, which comprises a combustion boiler, the air preheater, the low-temperature economizer, the electrostatic dust collector, the induced draft fan, the desulfurizing tower and the chimney are sequentially arranged at a flue gas outlet of the combustion boiler in a communicating mode; the centrifugal air compressor is used for generating compressed air, and the centrifugal air compressor can generate compression heat during compression operation; the heating medium water system is used for absorbing the compression heat generated by the centrifugal air compressor so as to heat the system and become a heat source; and the air system serves as a cold source and is used for absorbing heat from the heating medium water system, so that air passing through the air system enters the air preheater after being heated for the first time, and is fed into the combustion boiler after being heated for the second time by the air preheater. According to the compression heat coupling utilization system of the centrifugal air compressor of the power plant, compression heat can be fully recycled, energy waste is avoided, and the purposes of reducing the use amount of closed cold water of the power plant and reducing the investment of a closed cold water system are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat recovery, and in particular to a compression heat coupling utilization system of a centrifugal air compressor in a power plant. Background Art

[0002] Compressed air is the power carrier of pneumatic systems in modern industrial manufacturing, and is widely used in manufacturing and energy-intensive industries. The energy consumption of compressed air generally accounts for about 10% of the total electricity consumption. The energy consumption of air compression is dominant in the entire pneumatic system, up to 40%. The air compressor compression process is close to adiabatic compression. Due to the short compression time and small gas thermal conductivity, the heat generated by the air compressor during compression needs to be taken away as soon as possible, otherwise it will have a relatively large impact on the compression efficiency. How to make good use of the interstage compression heat of the air compressor to further improve the compression efficiency and reduce energy consumption is an important issue currently faced.

[0003] Improving the efficiency of air compressors, reducing air compressor energy consumption, and recovering the compression heat of air compressors are important means. Since the compression heat temperature of multi-stage centrifugal air compressors is relatively low (~120°C), it is difficult to recover it. It is mainly discharged into the atmosphere through air cooling or water cooling, which causes a relatively large waste of energy. At present, the means of recycling the compression heat of air compressors are mainly reflected in measures such as using compression heat to make hot water or using compression heat for refrigeration. Combined with the use of centrifugal air compressors in thermal power plants, the main cooling method for air compressors is to use closed cooling water to cool the air compressors, but this solution will bring two problems: (1) First, the centrifugal air compressor consumes a large amount of closed cooling water, accounting for about 15% of the total closed cooling water volume; (2) Second, this method of using closed cooling water for cooling makes the compression heat of centrifugal air compressors not utilized and directly wasted, resulting in serious waste of resources. Therefore, in order to consider reducing the amount of closed cooling water used in power plants, it is very meaningful to comprehensively utilize the compression heat of air compressors in power plants.

[0004] The existing centrifugal air compressor waste heat utilization system is mainly used for heating, cooling, etc. In power plants, the compression heat of centrifugal air compressors is mainly taken away by cooling water. In particular, the application of large centrifugal air compressors in power plants requires a greatly increased amount of cooling water. If cooling water is still used, the demand for cooling water will increase, resulting in an increase in investment in the cooling water system. Second, the compression heat of large centrifugal air compressors is not fully utilized in power plants, resulting in energy waste. Utility Model Content

[0005] The purpose of the utility model is to: in view of the above-mentioned problems existing in the existing air compressor compression heat recovery method, the utility model designs a power plant centrifugal air compressor compression heat coupling utilization system, which can fully recover and utilize the compression heat and avoid energy waste, and reduce the power plant closed cooling water consumption and reduce the investment in the closed cooling water system.

[0006] In order to achieve the above object, the utility model is realized by the following technical solutions:

[0007] The utility model proposes a compression heat coupling utilization system for centrifugal air compressors in power plants, the system comprising:

[0008] Combustion boilers;

[0009] The air preheater, low-temperature economizer, electrostatic precipitator, induced draft fan, desulfurization tower and chimney arranged at the flue gas outlet of the combustion boiler are sequentially connected, and the low-temperature economizer is used as a heat source to heat the condensate;

[0010] A centrifugal air compressor is used to generate compressed air, and the centrifugal air compressor generates compression heat during compression operation; the compression heat can also be used as a heat source to heat condensate;

[0011] A heat medium water system, which is used to absorb the compression heat generated by the centrifugal air compressor to increase the temperature of the system and become a heat source;

[0012] And an air system, which serves as a cold source for absorbing heat from the heat medium water system, so that the air passing through the air system is heated once and then enters the air preheater, and is then heated twice by the air preheater and then sent to the combustion boiler.

[0013] Specifically, the existing multi-stage centrifugal air compressors mostly use water cooling to cool the air compressors between stages, so that the compression process of the air compressor is close to adiabatic compression, but the compression heat of the air compressor is not utilized, resulting in energy loss. In thermal power plants, air compressors are cooled using closed cooling water, which not only increases the amount of closed cooling water, resulting in an increase in the investment in the closed cooling water system, but also does not utilize the compression heat, resulting in energy loss. The interstage exhaust temperature of the centrifugal air compressor is relatively high, and the interstage heat can be used to heat the boiler cold air, thereby improving the boiler efficiency. It can also be coupled with the flue gas waste heat system of the boiler unit, so that more flue gas temperature can be used to heat the condensate or the interstage compression heat of the air compressor can be directly coupled with the condensate, thereby reducing the heat consumption of the steam turbine and the coal consumption of the unit.

[0014] The design of the utility model aims to recover the inter-stage compression heat loss of centrifugal air compressors in power plants, reduce the amount of closed cooling water, and improve the efficiency of boiler units, and proposes a power plant centrifugal air compressor compression heat coupling utilization system. The utility model uses a heat medium water system to recover the inter-stage compression heat generated by the centrifugal air compressor and utilize it. Through this system, on the one hand, the amount of closed cooling water in the power plant can be reduced, and the investment in the closed cooling water system can be reduced. On the other hand, the inter-stage compression heat of the centrifugal air compressor can be recovered and utilized to the maximum extent. The recovered heat (compression heat) can be used to heat the cold air entering the boiler or to heat condensate, thereby improving the efficiency of the power plant unit. The heat medium water system designed by the utility model is mature in operation, and the heat medium water heats the cold air (such as Figure 1 and Figure 2 ), or directly heat the condensate by compression heat (as shown Figure 3 The systems shown in the figure have been effectively verified in power plants. The utility model is proposed based on the idea of ​​reducing the compression heat loss of the air compressor in combination with the above systems.

[0015] Furthermore, a compression heat coupling utilization system of a centrifugal air compressor in a power plant: the centrifugal air compressor is a multi-stage centrifugal air compressor.

[0016] Furthermore, a compression heat coupling utilization system of a centrifugal air compressor in a power plant is provided: a plurality of interstage coolers are arranged in the centrifugal air compressor, and the heat medium water system is used to absorb the compression heat generated from the interstage coolers.

[0017] Furthermore, a compression heat coupling utilization system of a centrifugal air compressor in a power plant: the interstage cooler includes: interstage cooler I, interstage cooler II and interstage cooler III, etc.

[0018] Furthermore, a compression heat coupling utilization system of a centrifugal air compressor in a power plant: the heat medium water system includes: a heat medium water tank, a heat medium water pump and a heat medium water pipeline; the heat medium water pipeline is connected to the inter-stage coolers, the heat medium water tank is used to provide desalted water to the heat medium water pipeline, and the heat medium water pump drives the desalted water circulation in the heat medium water pipeline.

[0019] Further, a power plant centrifugal air compressor compression heat coupling utilization system: the wind system includes: at least one group of heaters and at least one group of fans;

[0020] The heater is arranged on the heat medium water pipeline and is heated by the heat medium water pipeline; the fan is connected to the heater and is used to send air through the heater and then heat it up once before entering the air preheater.

[0021] Furthermore, a power plant centrifugal air compressor compression heat coupling utilization system: the wind system includes: two groups of heaters and two groups of fans; the two groups of heaters are arranged in parallel on the heat medium water pipeline, and the two groups of fans are connected to the two groups of heaters respectively.

[0022] The utility model also designs another power plant centrifugal air compressor compression heat coupling utilization system, the system comprises:

[0023] A centrifugal air compressor, which is used to generate compressed air, and the centrifugal air compressor generates compression heat during compression operation;

[0024] and a condensate system, wherein the condensate system is used to absorb the compression heat.

[0025] Furthermore, a power plant centrifugal air compressor compression heat coupling utilization system: the centrifugal air compressor is provided with a plurality of interstage coolers; the condensate system includes a condensate inlet pipeline and a condensate return pipeline; the condensate inlet pipeline and the condensate return pipeline are connected to the interstage coolers, and the condensate is used to absorb the compression heat from the interstage coolers.

[0026] Note: Compression heat of centrifugal air compressor: The working principle of centrifugal air compressor is adiabatic compression process. A large amount of compression heat will be generated during the operation of multi-stage centrifugal air compressor.

[0027] Beneficial effects of the utility model:

[0028] The power plant centrifugal air compressor compression heat coupling utilization system designed by the utility model effectively recovers the interstage compression heat generated by the centrifugal air compressor through the heat medium water system, and fully utilizes the interstage compression heat of the centrifugal air compressor to preheat the cold air entering the boiler or heat the condensate, thereby improving the boiler efficiency or reducing the heat consumption of the steam turbine, and reducing the coal consumption of the boiler unit. In addition, since the heat medium water system absorbs the interstage compression heat generated by the centrifugal air compressor, it is no longer necessary to use closed cooling water for cooling the centrifugal air compressor, thereby reducing the amount of closed cooling water used in the power plant, reducing the investment in the closed cooling water system, and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 A schematic diagram of the structure of a power plant centrifugal air compressor compression heat coupling utilization system designed for Example 1 of the utility model;

[0031] Figure 2 A schematic diagram of the structure of a power plant centrifugal air compressor compression heat coupling utilization system designed for Example 2 of the utility model;

[0032] Figure 3 A schematic structural diagram of a compression heat coupling utilization system for a power plant centrifugal air compressor designed for Example 3 of the utility model.

[0033] Markings in the figure:

[0034] 1-combustion boiler, 2-air preheater, 3-low-temperature economizer, 4-electrostatic precipitator, 5-induced draft fan, 6-desulfurization tower, 7-chimney, 8-centrifugal air compressor, 9-heat medium water system, 10-wind system, 11-condensate system, 81-interstage cooler I, 82-interstage cooler II, 83-interstage cooler III, 91-heat medium water tank, 92-heat medium water pump, 93-heat medium water pipeline, 101-heater, 102-fan, 111-condensate inlet pipeline, 112-condensate return pipeline. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the utility model and its application or use. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0036] In the description of the present utility model, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom" and the like indicate positions or positional relationships, which are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Moreover, the terms "first", "second" and the like are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present utility model described herein can be implemented in an order other than those illustrated or described herein.

[0037] Example 1

[0038] like Figure 1 As shown, this embodiment 1 designs a power plant centrifugal air compressor compression heat coupling utilization system, which includes:

[0039] Combustion boiler 1;

[0040] The air preheater 2, the low-temperature economizer 3, the electrostatic precipitator 4, the induced draft fan 5, the desulfurization tower 6 and the chimney 7 arranged at the flue gas outlet of the combustion boiler 1 are sequentially connected. The low-temperature economizer 3 is used as a heat source to heat the condensate water, that is, the low-temperature economizer 3 is provided with a condensate water inlet pipeline and a condensate water return pipeline;

[0041] A multistage centrifugal air compressor 8, in which a plurality of interstage coolers (specifically including an interstage cooler I 81, an interstage cooler II 82 and an interstage cooler III 83) are arranged, the multistage centrifugal air compressor 8 is used to generate compressed air, and the multistage centrifugal air compressor 8 will inevitably generate interstage compression heat when performing air compression operation;

[0042] The heat medium water system 9 includes a heat medium water tank 91, a heat medium water pump 92 and a heat medium water pipeline 93. The heat medium water pipeline 93 is connected in parallel with the interstage cooler I 81, the interstage cooler II 82 and the interstage cooler III 83. The heat medium water tank 91 is used to provide desalted water to the heat medium water pipeline 93. The heat medium water pump 92 drives the desalted water in the heat medium water pipeline 93 to circulate. The circulating desalted water (heat medium water) absorbs the compression heat generated by the multi-stage centrifugal air compressor 8 to heat the desalted water and become a heat source.

[0043] And the wind system 10, which includes two groups of air heaters 101 and two groups of fans 102. The two groups of air heaters 101 are arranged in parallel on the heat medium water pipeline 93, and are heated by the desalted water circulating in the heat medium water pipeline 93; the two groups of fans 102 are connected to the two groups of air heaters 101 respectively, and the two groups of fans 102 are respectively used to send two paths of air (cold air) through the two groups of air heaters 101 for heating once respectively and then enter the air preheater 2 together, and then the air heated once by the air heater 101 is heated twice by the air preheater 2 and sent to the combustion boiler 1. Since the air entering the combustion boiler 1 is heated twice, the temperature of the air is higher, which can improve the boiler efficiency and reduce coal consumption.

[0044] The power plant centrifugal air compressor compression heat coupling utilization system designed in this embodiment 1 uses the compression heat of the centrifugal air compressor 8 to heat the cold air entering the combustion boiler 1, thereby improving the boiler efficiency. At the same time, because the air entering the combustion boiler 1 has been heated by the compression heat, the heat energy consumed by the high-temperature flue gas in the air preheater 2 when heating the air again will be reduced, so that more flue gas energy will enter the low-temperature economizer 3 and be used to heat condensate, thereby reducing the heat consumption of the steam turbine. This system design of the utility model changes the original method of using closed cooling water to cool the centrifugal air compressor to using desalted water circulating in the heat medium water system for cooling, which can reduce the amount of closed cooling water used in the power plant and save costs.

[0045] The power plant centrifugal air compressor compression heat coupling utilization system designed in this embodiment 1 recovers the compression heat of the centrifugal air compressor due to the setting of the heat medium water system 9, avoiding the waste of compression heat. The compression heat of the centrifugal air compressor is fully absorbed by the heat medium water system 9, and the heat medium water after absorbing the compression heat is used to heat the cold air entering the boiler, so that the cold air can enter the combustion boiler 1 after being heated, thereby achieving the purpose of improving the boiler efficiency. In addition, due to the setting of the heat medium water system 9, the cold air first completes heat exchange and temperature increase with the heat medium water, and then exchanges heat with the high-temperature flue gas in the air preheater 2. At this time, since the cold air has been heated by the heat medium water, it can absorb less heat when it exchanges heat with the high-temperature flue gas again, so the flue gas temperature flowing out of the outlet of the air preheater 2 will be higher, so that the low-temperature economizer 3 has more flue gas heat to heat the condensate, reducing the heat consumption of the steam turbine.

[0046] This structural design of the present embodiment 1 can reduce the amount of closed cooling water, thereby reducing the investment in the closed cooling water system. After adopting this system, the compression heat of the centrifugal air compressor is absorbed by heat medium water. On the one hand, the compression heat of the air compressor is fully recovered to reduce energy consumption; on the other hand, the temperature of the cold air entering the combustion boiler is increased by the heat medium water system, and more flue gas heat can be used to heat the condensate, thereby improving the efficiency of the unit. Seeking a suitable air compressor cooling method in a large centralized gas supply station in a power plant can fully recover the interstage compression heat of the centrifugal air compressor, avoid energy waste, and reuse it in the unit cold air and condensate system, which has a significant effect on improving furnace efficiency and reducing steam turbine heat consumption, thereby reducing the unit coal consumption index.

[0047] Example 2

[0048] like Figure 2 As shown, this embodiment 2 designs a power plant centrifugal air compressor compression heat coupling utilization system, which includes:

[0049] Combustion boiler 1;

[0050] The air preheater 2, the low-temperature economizer 3, the electrostatic precipitator 4, the induced draft fan 5, the desulfurization tower 6 and the chimney 7 arranged at the flue gas outlet of the combustion boiler 1 are sequentially connected. The low-temperature economizer 3 is used as a heat source to heat the condensate water, that is, the low-temperature economizer 3 is provided with a condensate water inlet pipeline and a condensate water return pipeline;

[0051] A multistage centrifugal air compressor 8, in which a plurality of interstage coolers (specifically including an interstage cooler I 81, an interstage cooler II 82 and an interstage cooler III 83) are arranged, the multistage centrifugal air compressor 8 is used to generate compressed air, and the multistage centrifugal air compressor 8 will inevitably generate interstage compression heat when performing air compression operation;

[0052] The heat medium water system 9 includes a heat medium water tank 91, a heat medium water pump 92 and a heat medium water pipeline 93. The heat medium water pipeline 93 is connected in parallel with the interstage cooler I 81, the interstage cooler II 82 and the interstage cooler III 83. The heat medium water tank 91 is used to provide desalted water to the heat medium water pipeline 93. The heat medium water pump 92 drives the desalted water in the heat medium water pipeline 93 to circulate. The circulating desalted water (heat medium water) absorbs the compression heat generated by the multi-stage centrifugal air compressor 8 to heat the desalted water and become a heat source.

[0053] And a wind system 10, which includes a group of heaters 101 and a group of fans 102. The heater 101 is arranged on the heat medium water pipeline 93, and is heated by the desalted water circulating in the heat medium water pipeline 93; the fan 102 is connected to the heater 101, and the fan 102 is used to send air (cold air) through the heater 101 for primary heating and then enter the air preheater 2, and then send it to the combustion boiler 1 after secondary heating in the air preheater 2. Since the air entering the combustion boiler 1 is heated twice, the temperature of the air is higher, which can improve the boiler efficiency and reduce coal consumption.

[0054] Example 3

[0055] like Figure 3 As shown, this embodiment 3 provides a power plant centrifugal air compressor compression heat coupling utilization system that is different from embodiments 1 and 2, and the system includes:

[0056] A multi-stage centrifugal air compressor 8, wherein a plurality of interstage coolers (specifically, interstage cooler I, interstage cooler II, and interstage cooler III) are provided, and the multi-stage centrifugal air compressor 8 is used to generate compressed air. The multi-stage centrifugal air compressor 8 generates compression heat during compression operation;

[0057] And a condensate system 11, which includes a condensate inlet pipeline 111 and a condensate return pipeline 112. The condensate inlet pipeline 111 and the condensate return pipeline 112 are connected to the intercooler I, the interstage cooler II and the interstage cooler III respectively, and the condensate in the pipeline is used to absorb compression heat from each interstage cooler.

[0058] In the present embodiment 3, the multi-stage centrifugal air compressor 8 is not coupled with the combustion boiler of the power plant, but the multi-stage centrifugal air compressor 8 is directly coupled with the condensate system 11; the multi-stage centrifugal air compressor 8 in the present embodiment 3 is also provided with an interstage cooler I, an interstage cooler II and an interstage cooler III, and the interstage compression heat generated by the multi-stage centrifugal air compressor 8 can be directly used to heat the condensate, thereby reducing the heat consumption of the steam turbine.

[0059] Specifically, the compression process of a centrifugal air compressor is approximately adiabatic compression, and compressed air of appropriate pressure is generated through a multi-stage compression process. The inter-stage cooling of the air compressor is currently mainly achieved through cooling water or air cooling.

[0060] In combination with Examples 1 to 3, the compression heat utilization system in the utility model is divided into two typical processes. The first process is that chemically desalted water enters the heat medium water system through the heat medium water tank, and the heat medium water (desalted water) enters the interstage cooler (Ⅰ, Ⅱ, Ⅲ) of the centrifugal air compressor after being pressurized by the heat medium water pump. The heat medium water absorbs the compression heat of the compressed air through the interstage cooler to achieve the purpose of cooling the centrifugal air compressor, thereby maintaining the adiabatic compression process of the centrifugal air compressor. The heated heat medium water enters the heater 101, and the cold air absorbs heat in the heater 101 to increase the wind temperature entering the air preheater 2. The heat medium water returns to the inlet of the heat medium water pump 92 after releasing heat in the heater 101, and then enters the interstage cooler of the centrifugal air compressor again after being pressurized by the heat medium water pump, thereby completing a cycle.

[0061] The second process is that the condensate enters the interstage cooler (Ⅰ, Ⅱ, Ⅲ) of the centrifugal air compressor through the condensate pipe. The condensate absorbs the compression heat of the compressed air through the interstage cooler to maintain the adiabatic compression process of the centrifugal air compressor. The heated condensate returns to the condensate system. This process can reduce the heat consumption of the steam turbine.

[0062] The utility model makes full use of the interstage compression heat of the centrifugal air compressor to heat the cold air or condensate, recovers the interstage compression heat of the air compressor, improves the boiler efficiency or reduces the heat consumption of the steam turbine, and reduces the coal consumption of the unit. In addition, in the structural design of the utility model, since the cooling of the centrifugal air compressor no longer requires closed cooling water, the amount of closed cooling water used in the power plant is reduced, and the investment in the closed cooling water system is reduced.

[0063] After adopting the system of the utility model, the interstage compression heat of the centrifugal air compressor 8 is used to heat the boiler cold air or the steam turbine condensate, which can effectively improve the boiler efficiency or reduce the heat consumption of the steam turbine. In addition, the investment in the closed cold water system in the power plant can be reduced, especially in the promotion of large-scale centralized gas supply stations in power plants. The use of closed cold water systems will be more complicated. The system design of the utility model can greatly reduce the investment in the cooling water system, and at the same time couple the boiler cold air or condensate system 11 to achieve full and reasonable utilization of energy.

[0064] The utility model is based on the basic principle of centrifugal air compressor operation and the idea of ​​waste heat utilization in power plants, and fully recovers the inter-stage compression heat of the air compressor and reuses it in the cooling air system or the steam turbine condensate system. The utility model fully utilizes the compression heat of the air compressor, couples the boiler cooling air, thereby improving the boiler efficiency, or couples the steam turbine condensate system to reduce the heat consumption of the steam turbine. On the one hand, it achieves reasonable recovery of compression heat, and on the other hand, it reduces the amount of cooling water used in the power plant, thereby optimizing the cooling water investment. The utility model fully utilizes waste heat, and in a large centralized gas supply station in a power plant, finds a suitable air compressor cooling method, avoids the construction of a larger cooling water system, saves space, and only adds a heat medium water system or a condensate system to achieve cooling of the centrifugal air compressor, while reducing the initial investment in the construction of a large air compressor station.

[0065] The above preferred embodiments of the utility model are only used to explain the utility model, and are not used to limit the utility model. Any obvious changes or modifications derived from the technical solution of the utility model are still within the protection scope of the utility model.

Claims

1. A power plant centrifugal air compressor compression heat coupling utilization system, characterized in that: The system includes: Combustion boiler (1); An air preheater (2), a low-temperature economizer (3), an electrostatic precipitator (4), an induced draft fan (5), a desulfurization tower (6) and a chimney (7) are sequentially connected to the flue gas outlet of the combustion boiler (1), wherein the low-temperature economizer (3) is used as a heat source to heat condensate; A centrifugal air compressor (8) for generating compressed air, wherein the centrifugal air compressor (8) generates compression heat during compression operation; A heat medium water system (9) for absorbing the compression heat generated by the centrifugal air compressor (8) to increase the temperature of the system and become a heat source; and an air system (10) which serves as a cold source and is used to absorb heat from the heat medium water system (9), so that the air passing through the air system (10) is heated once and then enters the air preheater (2), and is then heated twice by the air preheater (2) and then sent to the combustion boiler (1).

2. The power plant centrifugal air compressor compression heat coupling utilization system according to claim 1, characterized in that: The centrifugal air compressor (8) is a multi-stage centrifugal air compressor.

3. A power plant centrifugal air compressor compression heat coupling utilization system according to claim 1 or 2, characterized in that: The centrifugal air compressor (8) is provided with a plurality of interstage coolers, and the heat medium water system (9) is used to absorb the compression heat generated from the interstage coolers.

4. The power plant centrifugal air compressor compression heat coupling utilization system according to claim 3, characterized in that: The interstage cooler comprises: an interstage cooler I (81), an interstage cooler II (82) and an interstage cooler III (83).

5. The power plant centrifugal air compressor compression heat coupling utilization system according to claim 3, characterized in that: The heat medium water system (9) comprises: a heat medium water tank (91), a heat medium water pump (92) and a heat medium water pipeline (93); The heat medium water pipeline (93) is connected to each inter-stage cooler, the heat medium water tank (91) is used to provide desalted water to the heat medium water pipeline (93), and the heat medium water pump (92) drives the desalted water in the heat medium water pipeline (93) to circulate.

6. The power plant centrifugal air compressor compression heat coupling utilization system according to claim 5, characterized in that: The wind system (10) comprises: at least one set of air heaters (101) and at least one set of fans (102); The air heater (101) is arranged on the heat medium water pipeline (93) and supplies heat to the heat medium water pipeline (93); the fan (102) is arranged in communication with the air heater (101), and the fan (102) is used to send air through the air heater (101) to be heated once and then enter the air preheater (2).

7. The power plant centrifugal air compressor compression heat coupling utilization system according to claim 6, characterized in that: The wind system (10) comprises: two groups of air heaters (101) and two groups of fans (102); Two groups of air heaters (101) are arranged in parallel on the heat medium water pipeline (93), and two groups of fans (102) are arranged in communication with the two groups of air heaters (101) respectively.

8. The power plant centrifugal air compressor compression heat coupling utilization system according to claim 1, characterized in that: The system includes: Centrifugal air compressor (8); and a condensate system (11), wherein the condensate system (11) is used to absorb the compression heat.

9. The power plant centrifugal air compressor compression heat coupling utilization system according to claim 8, characterized in that: The centrifugal air compressor (8) is provided with a plurality of interstage coolers; the condensate system (11) comprises a condensate inlet pipeline (111) and a condensate return pipeline (112); The condensate inlet pipeline (111) and the condensate return pipeline (112) are connected to the intercoolers at each stage, and the condensate is used to absorb compression heat from the intercoolers at each stage.

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