Boiler primary air heating structure and heating system

Abstract

The embodiment of the invention provides a boiler primary air heating structure and a heating system, and is applied to the technical field of boiler heating. The heating structure provided by the embodiment comprises a primary air heating system and a condensed water heating system, the primary air heating system comprises a first air heater and a second air heater which are connected through an air conveying pipeline; the condensed water heating system comprises a first water heater, a second water heater and a third water heater which are connected in sequence; the first water heater comprises a first pipeline and a second pipeline; the first pipeline is connected with an inlet pipeline of the first air heater; the second pipeline is connected with an outlet pipeline of the first air heater; the second water heater comprises a third pipeline and a fourth pipeline; the third pipeline is connected with an inlet pipeline of the second air heater; the fourth pipeline is connected with an outlet pipeline of the second air heater. According to the scheme, the heating efficiency of primary air is remarkably improved, and powerful support is provided for efficient operation of the boiler.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of boiler heating, and in particular to a boiler primary air heating structure and a heating system. Background Art

[0002] At present, the primary air heating of domestic coal-fired power station boilers mainly relies on rotary air preheaters, which adopt a three-compartment structure of primary air, secondary air and flue gas. Its working principle is to absorb heat from the flue gas side before the electrostatic precipitator, and rotate the heat to the primary air side by controlling the rotation of the air preheater to heat the cold air, so as to effectively use the exhaust waste heat to increase the boiler inlet air temperature.

[0003] Since the primary air also needs to transport coal powder from the pulverizer, a higher wind pressure is required, which leads to serious primary air leakage in the rotary air preheater, increased power consumption of the primary fan and low efficiency of flue gas waste heat recovery, which in turn leads to low primary air heating efficiency. Summary of the invention

[0004] The embodiments of the present invention provide a boiler primary air heating structure and a heating system, which can improve the heating efficiency when heating the primary air.

[0005] In a first aspect, an embodiment of the present invention provides a boiler primary air heating structure, the heating structure comprising a primary air heating system and a condensate heating system;

[0006] The primary air heating system comprises a first air heater and a second air heater; the first air heater and the second air heater are connected via an air delivery pipeline;

[0007] The condensate heating system comprises a first water heater, a second water heater and a third water heater; the second water heater is connected to the first water heater and the third water heater respectively through a water pipeline;

[0008] The first water heater comprises a first pipe and a second pipe; the first pipe is connected to the inlet pipe of the first air heater; the second pipe is connected to the outlet pipe of the first air heater;

[0009] The second water heater includes a third pipe and a fourth pipe; the third pipe is connected to the inlet pipe of the second air heater; and the fourth pipe is connected to the outlet pipe of the second air heater.

[0010] In one embodiment, the primary air heating system further comprises a third air heater;

[0011] The third air heater and the second air heater are connected via an air delivery duct.

[0012] In one embodiment, the inlet pipe of the third air heater is connected to the cold end reheat steam, and the outlet pipe of the third air heater is connected to the dehydrogenation expansion tank.

[0013] In one embodiment, the condensate heating system further includes an auxiliary water heater;

[0014] The auxiliary water heater is connected to the first water heater and the second water heater respectively through water pipelines.

[0015] In one embodiment, the auxiliary water heater includes a fourth water heater and / or a fifth water heater;

[0016] The fourth water heater and the fifth water heater are connected via a water pipeline.

[0017] In one embodiment, the fifth water heater is a deaerator.

[0018] In one embodiment, the heating structure further includes a low-temperature economizer;

[0019] The first pipeline and the inlet pipeline of the first air heater are connected to form a fifth pipeline; the inlet pipeline of the low-temperature economizer is connected to the first end of the fifth pipeline, and the outlet pipeline of the low-temperature economizer is connected to the inlet pipeline of the first air heater;

[0020] In one embodiment, the heating structure further comprises a bypass economizer;

[0021] The third pipe and the inlet pipe of the second air heater are connected to form a sixth pipe; the inlet pipe of the bypass economizer is connected to the first end of the sixth pipe, and the outlet pipe of the bypass economizer is connected to the inlet pipe of the second air heater.

[0022] In one embodiment, the heating structure further includes a low-temperature economizer and a bypass economizer;

[0023] The first pipeline and the inlet pipeline of the first air heater are connected to form a fifth pipeline; the inlet pipeline of the low-temperature economizer is connected to the first end of the fifth pipeline, and the outlet pipeline of the low-temperature economizer is connected to the inlet pipeline of the first air heater;

[0024] The third pipe and the inlet pipe of the second air heater are connected to form a sixth pipe; the inlet pipe of the bypass economizer is connected to the first end of the sixth pipe, and the outlet pipe of the bypass economizer is connected to the inlet pipe of the second air heater.

[0025] In a second aspect, an embodiment of the present invention provides a heating system, which includes a boiler secondary air heating structure and a boiler primary air heating structure provided by any embodiment of the present invention.

[0026] The boiler primary air heating structure and heating system provided by the embodiment of the present invention include a primary air heating system and a condensate heating system; wherein the primary air heating structure includes a first air heater and a second air heater, and the multi-stage heating design mode can make the primary air gradually heated in different heaters, and through the staged heating, the heat can be more fully utilized, so that the primary air can reach a higher temperature; secondly, the condensate heating system provided by the present embodiment includes a first water heater, a second water heater and a third water heater; by connecting the first pipe of the condensate heating system with the inlet pipe of the first air heater, the second pipe with the outlet pipe of the first air heater, the third pipe with the inlet pipe of the second air heater, and the fourth pipe with the outlet pipe of the second air heater, an effective heat exchange is formed between the condensate and the primary air, and when the condensate flows in the first water heater and the second water heater, it can transfer heat to the primary air, which helps to improve the heating efficiency of the primary air. The problem of low heating efficiency and increased power consumption of the primary fan when the flue gas waste heat is used to heat the primary air is improved, and the heating efficiency of the primary air is significantly improved, which provides a beneficial effect of providing strong support for the efficient operation of the boiler.

[0027] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the embodiments of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 is a schematic diagram of an existing boiler primary air heating structure provided in this embodiment;

[0030] Figure 2 is a schematic diagram of a boiler primary air heating structure provided by an embodiment of the present invention;

[0031] Figure 3 is a schematic diagram of another boiler primary air heating structure provided by an embodiment of the present invention;

[0032] Figure 4 It is a schematic diagram of another boiler primary air heating structure provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0035] Before introducing the boiler primary air heating structure provided in this embodiment, the heating structure provided by the existing solution is described in advance. Figure 1 , Figure 1 It is a schematic diagram of the existing boiler primary air heating structure provided in this embodiment.

[0036] exist Figure 1 It can be seen that when a rotary air preheater is used to heat the primary air of a boiler, the rotary air preheater first absorbs heat from the flue gas side (usually in front of the electrostatic precipitator). Flue gas is the waste gas after the boiler is burned and contains a lot of waste heat. Then the air preheater rotates to the primary air side and transfers the absorbed heat to the cold air to heat the primary air, so as to effectively utilize the waste heat of the flue gas and increase the temperature of the air entering the boiler, which helps the fuel burn more fully and reduces fuel consumption.

[0037] Furthermore, in order to make fuller use of the exhaust heat, new units will generally add a low-temperature economizer after the air preheater. Figure 1 As shown in the figure, after the flue gas comes out of the air preheater, it will enter the low-temperature economizer. The low-temperature economizer further reduces the flue gas temperature, and the water side of the low-temperature economizer forms a closed cycle with the heater, etc. The heat medium water absorbs the heat of the flue gas in the low-temperature economizer, and then is used to heat the cold primary air to further improve the heat recovery and utilization efficiency.

[0038] In the existing scheme, since the primary air also needs to transport coal powder from the pulverizer, a higher wind pressure is required. In this case, the primary air leakage problem of the rotary air preheater is more serious. This not only increases the power consumption of the primary fan, because the fan needs more power to maintain sufficient wind pressure and air volume, but also affects the efficiency of flue gas waste heat recovery. Leakage will cause part of the flue gas to be discharged without sufficient heat exchange with the air, resulting in insufficient heat recovery, reducing the economy and environmental protection of the entire system; and the working environment of the low-temperature economizer is harsh, for example, it may face dust, corrosive substances in the flue gas, etc., resulting in a high failure rate. When the heating surface of the low-temperature economizer is partially removed, it is necessary to consider a backup heat source to ensure the normal operation and heat supply of the system. If there is no suitable backup heat source, when the low-temperature economizer fails, the heat supply of the entire system may be affected, thereby affecting the operating efficiency and stability of the boiler.

[0039] In view of this, the boiler primary air heating structure provided in the embodiment of the present application can improve the problems existing in the above-mentioned solution. Figure 2 , Figure 2 This is a schematic diagram of a boiler primary air heating structure provided by an embodiment of the present invention. This embodiment can be applied to the case where the primary air of the boiler is heated to increase the temperature of the primary air entering the boiler. Figure 2 .

[0040] The boiler primary air heating structure provided in the embodiment of the present application includes a primary air heating system 100 and a condensate heating system 200 .

[0041] Among them, the primary air heating system 100 is used to heat the air generated by the primary fan so that the air heated to the target temperature is delivered to the coal mill, and the coal powder from the coal mill is delivered to the boiler through the wind at the target temperature. The appropriate air temperature can make the coal powder ignite and burn better, stabilize the combustion process, reduce incomplete combustion losses, and improve the stability and reliability of boiler operation.

[0042] The condensate heating system 200 is used to heat the condensate, which can increase the feed water temperature entering the boiler. The increase in feed water temperature can make the heat transfer in the boiler more efficient, reduce fuel consumption, and improve the thermal efficiency of the entire thermal cycle, thereby reducing the cost of power generation and improving the economic benefits of the power plant.

[0043] Specifically, in this embodiment, the primary air heating system 100 includes a first air heater 110 and a second air heater 120; the first air heater 110 and the second air heater 120 are connected via an air delivery pipeline.

[0044] Among them, the first air heater 110 is used to heat the wind generated by the primary fan received once to a first temperature, and the second air heater 120 is used to continue to heat the wind of the first temperature to a target temperature, and the hot air heated to the target wind temperature is delivered to the coal mill. In this embodiment, by setting the first air heater 110 and the second air heater 120, a two-stage heating method is adopted, which can make fuller use of the heat source to heat the primary air compared with a single heater. For example, the first air heater 110 can use a relatively low temperature heat source for preliminary heating, and the second air heater 120 can further heat up the heat source using a higher temperature or better quality heat source, so as to realize the step-by-step utilization of the heat source, thereby improving the overall heating efficiency; if one of the heaters fails, the other heater can still maintain a certain degree of heating function, ensuring that the system will not completely lose the ability to heat the primary air, thereby enhancing the stability and reliability of the entire primary air heating system 100. For example, if the first air heater 110 suddenly fails, the second air heater 120 can receive the primary air without preliminary heating. Although it cannot reach the normal final temperature, it can provide primary air at a certain temperature to keep the system running basically while waiting for maintenance.

[0045] In this embodiment, the condensate heating system 200 includes a first water heater 210, a second water heater 220 and a third water heater 230; the second water heater 220 is connected to the first water heater 210 and the third water heater 230 through a water pipeline. In this embodiment, the first water heater 210, the second water heater 220 and the third water heater 230 work together to complete the heating process of the condensate.

[0046] Among them, the first water heater 210 is the starting stage of heating. It first receives low-temperature condensate from equipment such as condensers, and uses a lower-grade heat source or a relatively mild heating method to preliminarily heat the condensate, raising the temperature of the condensate to a certain degree, in preparation for subsequent further heating; after the first water heater 210 transfers the preliminarily heated condensate to the second water heater 220, it uses a higher-grade heat source or a more effective heating method than the first water heater 210 to perform secondary heating on the condensate, so that the temperature of the condensate is further increased. At the same time, it also undertakes the task of conveying the heated condensate to the third water heater 230; the third water heater 230 is the last link of condensate heating. It receives the condensate heated by the first two stages, and uses a high-grade heat source or an efficient heating method to finally heat it, raising the temperature of the condensate to the target temperature that meets the requirements of the thermal system, in preparation for the subsequent entry of the condensate into equipment such as boilers.

[0047] The condensate water heating system 200 provided in this embodiment adopts a three-stage heating method, which can realize the gradual and efficient heating of condensate water according to the characteristics of different heaters and the heat source conditions. This hierarchical heating mode makes full use of energy and improves the thermal efficiency of the entire heating system; the setting of three water heaters can realize the cascade utilization of heat and avoid the energy waste that may occur in a single heater. Heat sources of different temperatures participate in heating at different stages, so that heat can be reasonably utilized according to its quality and energy level, improving the utilization efficiency of energy and reducing energy consumption.

[0048] Furthermore, in this embodiment, the first water heater 210 includes a first pipe L1 and a second pipe L2; the first pipe L1 is connected to the inlet pipe a of the first wind heater 110; the second pipe L2 is connected to the outlet pipe b of the first wind heater 110; the second water heater 220 includes a third pipe L3 and a fourth pipe L4; the third pipe L3 is connected to the inlet pipe c of the second wind heater 120; the fourth pipe L4 is connected to the outlet pipe d of the second wind heater 120.

[0049] Specifically, when the condensed water flows in the first water heater 210, it can transfer heat to the first air heater 110 through the pipe connected to the first pipe L1 and the inlet pipe a of the first air heater 110. Through heat exchange, it is helpful to improve the efficiency of heating the wind generated by the primary fan to the first temperature in the first air heater 110, and improve the utilization efficiency of heat. At the same time, the second water heater 220 is connected to the inlet pipe c of the second air heater 120 through the third pipe L3, and the fourth pipe L4 is connected to the outlet pipe d of the second air heater 120, further providing heat for the primary air in the second air heater 120, and further improving the efficiency of heating the primary air to the target temperature in the second air heater 120. The primary air heating structure provided in this embodiment forms a complete heat exchange synergistic system.

[0050] For example, when condensed water flows through various water heaters, the heat it carries can be accurately transferred to different heating stages of the primary air according to different heat exchange requirements, so that the heat will not be wasted but will be reasonably absorbed by the primary air, thereby improving the heating efficiency of the primary air.

[0051] In the solution provided by this embodiment, if a certain wind heater fails, the water heater connected to it can still interact with other parts through the pipeline to a limited extent to maintain the basic operation of the system, so as not to completely paralyze the entire system. For example, if the first wind heater 110 fails, the first water heater 210 can temporarily obtain a certain amount of heat from other parts or maintain the circulation of the medium through the second pipeline L2 to ensure the stability of the system. The connection between the water heater and the wind heater helps the system to balance and adjust parameters such as pressure and flow during operation. When the inlet or outlet parameters of the wind heater change, the water heater connected to it can fine-tune the overall parameters of the system through the feedback of the pipeline, so that the system can adapt to changes more quickly and maintain stable operation.

[0052] As can be seen from the figure, the first pipe L1 and the second pipe L2 are the corresponding positions of the water supply pipe connecting the first water heater 210 and the second water heater 220, respectively. Valves are provided in the first pipe L1 and the second pipe L2, respectively, and valves are provided at the connection between the first pipe L1 and the inlet pipe a of the first air heater 110, the connection between the second pipe L2 and the outlet pipe b of the first air heater 110, the connection between the third pipe L3 and the inlet pipe c of the second air heater 120, and the connection between the fourth pipe L4 and the outlet pipe d of the second air heater 120. The purpose of setting the valve is to control the direction of the condensate circuit by controlling the opening or closing of the valve; different heat exchange efficiencies can also be achieved by controlling the opening degree of the valve.

[0053] The boiler primary air heating structure provided in this embodiment includes a primary air heating system and a condensate heating system; wherein, the primary air heating structure includes a first air heater and a second air heater, and this multi-stage heating design can gradually heat the primary air in different heaters, and through staged heating, the heat can be more fully utilized, so that the primary air can reach a higher temperature; secondly, the condensate heating system provided in this embodiment includes a first water heater, a second water heater and a third water heater; by connecting the first pipe of the condensate heating system to the inlet pipe of the first air heater, the second pipe to the outlet pipe of the first air heater, the third pipe to the inlet pipe of the second air heater, and the fourth pipe to the outlet pipe of the second air heater, an effective heat exchange is formed between the condensate and the primary air, and when the condensate flows in the first water heater and the second water heater, it can transfer heat to the primary air, which helps to improve the heating efficiency of the primary air. The problem of low heating efficiency and increased power consumption of the primary fan when the existing flue gas waste heat is used to heat the primary air is improved, and the heating efficiency of the primary air is significantly improved, which provides a beneficial effect of providing strong support for the efficient operation of the boiler.

[0054] Please refer to Figure 3 , Figure 3 This is a schematic diagram of another boiler primary air heating structure provided by an embodiment of the present invention. Figure 2 The relationship between the embodiments provided is Figure 2 Further refinements of the corresponding features of the signal transmission device are provided in the embodiments.

[0055] Specifically, the primary air heating system 100 provided in this embodiment also includes a third air heater 130; wherein the third air heater 130 and the second air heater 120 are connected through an air supply pipe; the inlet pipe e of the third air heater 130 is connected to the cold end reheat steam 131, and the outlet pipe f of the third air heater 130 is connected to the dehydrogenation expansion tank 132.

[0056] In the normal primary air heating process, the primary air first enters the first air heater 110, and after preliminary heating, enters the second air heater 120 through the air duct. In the second air heater 120, the primary air continues to be heated. Under normal circumstances, if the second air heater 120 can successfully heat the primary air to the target air temperature, the third air heater 130 will not be put into use. At this time, the hot air heated to the target air temperature is directly transported to the coal mill through the connecting pipe for drying and transportation of coal powder; when the second air heater 120 fails to heat the primary air to the target temperature, the primary air will enter the third air heater 130 through the air duct. The inlet pipe e of the third air heater 130 is connected to the cold end reheat steam 131, and the cold end reheat steam 131 provides an additional heat source for the third air heater 130. The primary air absorbs heat in the third air heater 130, completes the supplementary heating process, and after reaching the target air temperature, the pipe on the other side of the third air heater 130 is transported to the coal mill. At the same time, the drain generated by the third air heater 130 is discharged to the drain expansion tank through the outlet pipe.

[0057] This embodiment greatly improves the reliability of heating the primary air to the target temperature by setting the third air heater 130. When the second air heater 120 is unable to heat the primary air to a suitable temperature due to a fault, load change, etc., the third air heater 130 can intervene in time to ensure that the hot air temperature entering the coal mill meets the standard, ensure the normal drying and transportation of coal powder, and avoid affecting the combustion efficiency and stability of the boiler due to insufficient air temperature; by setting the third air heater 130, the flexibility of the system can be enhanced, that is, the operator can flexibly decide whether to put the third air heater 130 into use according to the actual primary air temperature. This flexibility enables the system to quickly adjust the heating strategy according to different operating conditions and requirements, and better adapt to the complex and changing production environment.

[0058] Preferably, please continue to refer to Figure 3In the solution provided in this embodiment, the condensate water heating system 200 further includes an auxiliary water heater 240. The auxiliary water heater 240 is respectively connected to the first water heater 210 and the second water heater 220 through a water pipeline. In this embodiment, by arranging the auxiliary water heater 240 between the first water heater 210 and the second water heater 220, the condensate water coming out of the first water heater 210 can be further assisted to be heated by one level to prevent the outlet water temperature from failing to meet the standard.

[0059] Further, in the present embodiment, the auxiliary water heater 240 includes a fourth water heater 241 and / or a fifth water heater 242. Specifically, the number of levels of the water heaters in the present embodiment can be determined according to actual needs. If multi-stage heating is required, the fourth water heater 241 and the fifth water heater 242 can be set at the same time. If not required, only the fourth water heater 241 or the fifth water heater 242 can be set, depending on the actual setting. When the condensed water flows between the first water heater 210 and the second water heater 220, the auxiliary water heater 240 is connected to them through a water pipe. The fourth water heater 241 can participate in the heating of the condensed water at an appropriate time according to the system requirements to further increase the temperature of the condensed water.

[0060] When the fourth water heater 241 and the fifth water heater 242 are provided at the same time, the fourth water heater 241 and the fifth water heater 242 are connected by a water pipeline. The fourth water heater 241 and the fifth water heater 242 are connected by a water pipeline, which can make the condensed water flow in an orderly manner between the two. According to the operation of the system, the condensed water can exchange and transfer heat between the fourth water heater 241 and the fifth water heater 242, so as to realize multi-stage heating and optimization treatment of the condensed water.

[0061] Preferably, the fifth water heater 242 in this embodiment is a deaerator. The deaerator plays an important dual role of deoxidation and heating. After the condensate enters the fifth water heater 242, it will not only continue to heat the condensate, but also deoxidize the condensate. The deoxidation process is to remove the oxygen dissolved in the condensate to prevent corrosion of subsequent equipment (such as boilers). In this process, the temperature of the condensate will continue to rise due to heating.

[0062] The condensate heating system provided in this embodiment can further heat the condensate on the basis of the first water heater 210 and the second water heater 220 by providing an auxiliary water heater 240, especially the fourth water heater 241, to form a multi-stage heating system, so that the temperature of the condensate can be raised more fully, the step-by-step utilization of heat can be achieved, and the heating efficiency of the entire condensate heating system can be improved. For example, in some high-parameter thermal systems, multi-stage heating can make more full use of the waste heat or other available heat sources of the system, so that the condensate reaches a higher temperature, thereby increasing the feed water temperature entering the boiler, which helps to improve the thermal efficiency of the entire thermal cycle; the fifth water heater 242 acts as a deaerator to deoxygenate the condensate, which can prevent the oxygen in the water from corroding subsequent equipment, such as preventing the corrosion of equipment such as boiler pipes and turbine blades, thereby extending the service life of the equipment and ensuring the safe and stable operation of the entire thermal system. The orderly flow and heating of the condensate between multiple heaters helps to ensure the stability of the condensate temperature and quality, avoid the interruption of the condensate heating process of the entire system due to the failure or performance degradation of a single heater, and improve the fault tolerance and stability of the system.

[0063] For further information, please refer to Figure 4 , Figure 4 It is a schematic diagram of another boiler primary air heating structure provided in an embodiment of the present invention.

[0064] In the solution provided in this embodiment, the heating structure further includes a low-temperature economizer 310 and / or a bypass economizer 320 .

[0065] Among them, the first pipe L1 and the inlet pipe a of the first air heater 110 are connected to form a fifth pipe L5; the inlet pipe g of the low-temperature economizer 310 is connected to the first end m of the fifth pipe L5, and the outlet pipe h of the low-temperature economizer 310 is connected to the inlet pipe a of the first air heater 110; and / or, the third pipe L3 and the inlet pipe c of the second air heater 120 are connected to form a sixth pipe L6; the inlet pipe j of the bypass economizer 320 is connected to the first end n of the sixth pipe L6, and the outlet pipe k of the bypass economizer 320 is connected to the inlet pipe c of the second air heater 120.

[0066] In this embodiment, the inlet pipe g of the low-temperature economizer 310 is connected to the first end m of the first pipe L1 of the first water heater 210, which means that the condensed water flows out from the first end m of the first pipe L1 and enters the inlet pipe g of the low-temperature economizer 310. The low-temperature economizer 310 usually uses the heat of the low-temperature flue gas such as the tail of the boiler to heat the medium. After absorbing the heat, the temperature of the condensed water increases and flows out from the outlet pipe h of the low-temperature economizer 310, and then enters the inlet pipe a of the first air heater 110, participating in the heating process of the primary air in the first air heater 110, so as to further improve the heating efficiency of the primary air by the first air heater 110. And / or, the condensed water flows out from the first end n of the third pipe L3 and enters the inlet pipe j of the bypass economizer 320. The bypass economizer 320 adjusts the heat of the medium according to system requirements. After completing the heat exchange, the condensed water flows out from the outlet pipe k of the bypass economizer 320 and enters the inlet pipe c of the second air heater 120, and is used in the second air heater 120 to heat the primary air and supplement or adjust the heat required by the second air heater 120.

[0067] The solution provided in this embodiment can effectively recycle and utilize the waste heat of low-temperature flue gas such as the tail of the boiler through the low-temperature economizer, and transfer the heat that might have been wasted to the first air heater, thereby improving the energy utilization rate of the entire system, enabling the system to make more full use of energy, reduce energy waste, and reduce the energy consumption and operating costs of the system; and by preheating the medium entering the first air heater, the thermal stress of the first air heater during the heating process is reduced, and fatigue damage to the equipment caused by thermal expansion and contraction is reduced, which helps to extend the service life of the first air heater and its related pipes, valves and other equipment, and reduce equipment maintenance costs. Through the bypass economizer, the heat of the incoming medium can be flexibly supplemented or adjusted according to the actual needs of the second air heater, ensuring that the second air heater can obtain the medium of suitable temperature under different working conditions, thereby improving the heating efficiency of the second air heater and further improving the thermal efficiency of the entire system. Moreover, when problems occur in the main heating circuit of the second air heater, the bypass economizer can share part or all of the heating task, preventing the main heating equipment from being damaged due to overload or abnormal operating conditions, thereby protecting the second air heater and the equipment of the entire system, reducing the frequency of equipment maintenance and replacement, improving equipment availability, and reducing the cost of the equipment throughout its life cycle.

[0068] The heating system provided in the embodiment of the present invention includes a boiler secondary air heating structure and a boiler primary air heating structure provided in any one of the above embodiments.

[0069] The boiler secondary air heating structure is used to heat the secondary air to increase the temperature of the secondary air. When the hot secondary air is mixed with the fuel in the furnace, it can better contact with the fuel particles and be evenly distributed, promote the full mixing of the fuel and the air, create favorable conditions for the complete combustion of the fuel, make the combustion reaction more intense and complete, thereby improving the combustion efficiency and reducing the loss of incomplete combustion; and the higher temperature secondary air can provide more heat and energy for the combustion reaction, reduce the ignition temperature of the fuel, advance the ignition time, and speed up the combustion process. For example, in a pulverized coal boiler, the hot secondary air can make the pulverized coal reach the ignition point faster and burn quickly, improve the stability and efficiency of combustion, enable the fuel to release more heat in a shorter time, and increase the thermal power of the boiler.

[0070] Since the heating system provided by the embodiment of the present invention adopts all the technical solutions of all the embodiments of the above-mentioned boiler primary air heating structure, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0071] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A boiler primary air heating structure, characterized in that: The heating structure includes a primary air heating system and a condensate heating system; The primary air heating system comprises a first air heater and a second air heater; the first air heater and the second air heater are connected via an air delivery pipeline; The condensate heating system comprises a first water heater, a second water heater and a third water heater; the second water heater is connected to the first water heater and the third water heater respectively through a water pipeline; The first water heater comprises a first pipe and a second pipe; the first pipe is connected to the inlet pipe of the first air heater; the second pipe is connected to the outlet pipe of the first air heater; The second water heater includes a third pipe and a fourth pipe; the third pipe is connected to the inlet pipe of the second air heater; and the fourth pipe is connected to the outlet pipe of the second air heater.

2. The boiler primary air heating structure according to claim 1, characterized in that: The primary air heating system further comprises a third air heater; The third air heater and the second air heater are connected via an air delivery duct.

3. The boiler primary air heating structure according to claim 2, characterized in that: The inlet pipe of the third air heater is connected to the cold end reheat steam, and the outlet pipe of the third air heater is connected to the de-watering expansion tank.

4. The boiler primary air heating structure according to claim 1, characterized in that: The condensate heating system also includes an auxiliary water heater; The auxiliary water heater is connected to the first water heater and the second water heater respectively through water pipelines.

5. The boiler primary air heating structure according to claim 4, characterized in that: The auxiliary water heater includes a fourth water heater and / or a fifth water heater; The fourth water heater and the fifth water heater are connected via a water pipeline.

6. The boiler primary air heating structure according to claim 5, characterized in that: The fifth water heater is a deaerator.

7. The boiler primary air heating structure according to claim 1, characterized in that: The heating structure also includes a low-temperature economizer; The first pipe and the inlet pipe of the first air heater are connected to form a fifth pipe; the inlet pipe of the low-temperature economizer is connected to the first end of the fifth pipe, and the outlet pipe of the low-temperature economizer is connected to the inlet pipe of the first air heater.

8. The boiler primary air heating structure according to claim 1, characterized in that: The heating structure also includes a bypass economizer; The third pipe and the inlet pipe of the second air heater are connected to form a sixth pipe; the inlet pipe of the bypass economizer is connected to the first end of the sixth pipe, and the outlet pipe of the bypass economizer is connected to the inlet pipe of the second air heater.

9. The boiler primary air heating structure according to claim 1, characterized in that: The heating structure also includes a low-temperature economizer and a bypass economizer; The first pipeline and the inlet pipeline of the first air heater are connected to form a fifth pipeline; the inlet pipeline of the low-temperature economizer is connected to the first end of the fifth pipeline, and the outlet pipeline of the low-temperature economizer is connected to the inlet pipeline of the first air heater; The third pipe and the inlet pipe of the second air heater are connected to form a sixth pipe; the inlet pipe of the bypass economizer is connected to the first end of the sixth pipe, and the outlet pipe of the bypass economizer is connected to the inlet pipe of the second air heater.

10. A heating system, characterized in that: The heating system comprises a boiler secondary air heating structure and a boiler primary air heating structure as described in any one of claims 1-9.

Images