Ammonia gas heating system capable of improving boiler efficiency

Abstract

The utility model discloses an ammonia gas heating system capable of improving boiler efficiency. The ammonia gas heating system comprises a combustion boiler, an ammonia gas burner arranged in the combustion boiler, an air preheater communicated with a smoke outlet of the combustion boiler, and a dust remover, a desulfurizing absorption tower and a chimney which are sequentially communicated with the air preheater in the smoke flowing direction. The system further comprises at least one group of flue gas coolers, a closed circulating heat medium water system and an ammonia gas supply system; the multiple smoke coolers are arranged on the upstream of the chimney in a communicating mode and used for supplying heat to the heating medium water system. Ammonia gas supplied by the ammonia gas supply system is heated by the heating medium water system and then enters the ammonia gas combustor to be combusted. Considering that ammonia gas is dangerous, in order to avoid leakage of the ammonia gas, the heating medium water circulation system is arranged to serve as an energy transfer medium, the problems of pipeline corrosion and abrasion possibly caused by direct contact between an ammonia gas pipeline and flue gas are avoided, and therefore the problem of leakage of the ammonia gas is avoided. And the safety and reliability of the whole system are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of flue gas waste heat recovery, and in particular to an ammonia heating system for improving boiler efficiency. Background Art

[0002] Faced with the development trend of low-carbonization of the global economy, my country has proposed the carbon reduction target of "striving to peak carbon dioxide emissions before 2030 and striving to achieve carbon neutrality before 2060". In the field of traditional coal-fired thermal power generation, ammonia, as an efficient hydrogen storage medium and zero-carbon fuel, has begun to be used as a fuel for boiler combustion, playing a role in replacing coal. In existing thermal power plants, the fuel for boilers is mainly coal, natural gas, and fuel oil. Since these traditional fuels contain carbon, a large amount of carbon dioxide will be produced after combustion to generate electricity, thus affecting the carbon reduction target; and ammonia, as a zero-carbon fuel, can partially or completely replace carbon-based fuels for boiler combustion and power generation. The existing ammonia combustion technology usually sends ammonia at room temperature into the ammonia burner of the boiler for combustion.

[0003] Due to the fuel characteristics of ammonia, a large amount of water will be generated after its combustion. Compared with pure coal-fired boilers, the amount of flue gas after ammonia combustion will increase significantly, and the exhaust gas temperature will increase, resulting in reduced boiler efficiency, increased fuel consumption, and thus increased operating costs, resulting in poor economic efficiency. For example, for the current pure bituminous coal-fired boiler, after 60% ammonia is added for combustion, the exhaust gas temperature of the boiler will increase from about 114°C to about 140°C, and the efficiency of the boiler will drop from 95.1% to 93.35%. In order to avoid reducing the efficiency of the boiler, the prior art generally recovers the waste heat of the high-temperature flue gas after combustion, thereby improving the thermal efficiency of the boiler. Generally speaking, the flue gas is used to heat the ammonia before entering the boiler for combustion. However, ammonia has certain dangers. If the ammonia pipeline is corroded after long-term contact with the flue gas, resulting in ammonia leakage, it will seriously affect the safety of the entire boiler system. Utility Model Content

[0004] The purpose of the utility model is to design an ammonia heating system that can improve boiler efficiency in response to the problem of potential safety hazards in existing flue gas waste heat recovery technology. It can not only recover the flue gas waste heat and improve the boiler efficiency, but more importantly, it improves the safety of the entire system.

[0005] The utility model is realized through the following technical solutions:

[0006] An ammonia heating system for improving boiler efficiency is designed, the ammonia heating system comprising: a combustion boiler, an ammonia burner arranged in the combustion boiler, an air preheater connected to a flue gas outlet of the combustion boiler, and a dust collector, a desulfurization absorption tower and a chimney connected to the air preheater in sequence along a flue gas flow direction;

[0007] The ammonia heating system also includes: at least one set of flue gas coolers, a closed-cycle heat medium water system and an ammonia supply system; several of the flue gas coolers are connected and arranged upstream of the chimney, and are used to provide a heat source for the heat medium water system; the ammonia supplied in the ammonia supply system is heated by the heat medium water system and then enters the ammonia burner for combustion.

[0008] It can be understood that the flue gas cooler is used as a heat source to heat the heat medium water system to achieve flue gas cooling and heat medium water system heating. After the flue gas is cooled, it can enter the subsequent discharge process to recover the heat energy carried by the flue gas before it is discharged. The heated heat medium water system is used to heat ammonia. It can be said that the heat medium water system of the utility model is used as an intermediate medium to transfer the waste heat of the flue gas to ammonia. During this process, the flue gas will not directly contact the ammonia pipeline, thereby avoiding corrosion of the ammonia pipeline, solving the problem of ammonia leakage caused by flue gas corrosion of the pipeline, and thus improving the safety of the entire system.

[0009] The ammonia heating system designed by the utility model for improving boiler efficiency can be used in boilers for combustion of ammonia or boilers for combustion of pure ammonia, wherein the boiler can be a pulverized coal boiler, a circulating fluidized bed boiler, a gas boiler or an oil boiler.

[0010] Furthermore, an ammonia heating system for improving boiler efficiency: the heat medium water system includes: a heat medium water pipe, a heat medium water pump and at least one group of ammonia heaters; wherein: the heat medium water pipe is set up in a closed cycle, and is heated by the flue gas cooler; water is provided in the heat medium water pipe, and is driven to circulate by the heat medium water pump; the heat medium water pipe is used to heat the ammonia heater; the ammonia supplied in the ammonia supply system is heated by the ammonia heater and then enters the ammonia burner for combustion.

[0011] Furthermore, an ammonia heating system for improving boiler efficiency: the heat medium water system also includes a condensate water heater for heating condensate water, and the condensate water heater is connected and arranged on the heat medium water pipe and is heated thereby; an inlet valve and an outlet valve are respectively arranged at the inlet and outlet of the condensate water heater; a branch valve is also arranged on the heat medium water pipe.

[0012] Specifically, the condensate water comes from the condensate water system of the power plant, and is heated by the condensate water heater before going to the condensate water system.

[0013] Furthermore, an ammonia heating system for improving boiler efficiency: the condensate heater and the ammonia heater are arranged in series.

[0014] Furthermore, an ammonia heating system for improving boiler efficiency: the condensate heater and the ammonia heater are arranged in parallel.

[0015] Furthermore, an ammonia heating system for improving boiler efficiency is provided: the ammonia heaters are arranged in two groups, and the condensate heater is arranged in parallel with one group of ammonia heaters, and the whole is arranged in series with the other group of ammonia heaters.

[0016] Furthermore, an ammonia heating system for improving boiler efficiency: the ammonia heating system also includes an induced draft fan, and the induced draft fan is connected and arranged between the dust collector and the desulfurization absorption tower.

[0017] Furthermore, an ammonia heating system for improving boiler efficiency: the flue gas cooler is arranged in four groups; wherein: one group of flue gas coolers is connected and arranged between the combustion boiler and the air preheater, another group is connected and arranged between the air preheater and the dust collector, and the remaining two groups are connected and arranged in sequence between the dust collector and the desulfurization absorption tower.

[0018] Furthermore, an ammonia heating system for improving boiler efficiency: the flue gas coolers are arranged in one group, two groups or three groups.

[0019] Specifically, the low-temperature water after being pressurized by the heat medium water pump flows into the flue gas cooler, and the flue gas cooler transfers the heat released by the flue gas to the heat medium water, so that the water temperature of the heat medium water increases, becomes high-temperature water, and flows out of the flue gas cooler. The high-temperature water at the outlet of the flue gas cooler flows into the condensate heater and the ammonia heater again, and after releasing heat and cooling the condensate and ammonia, becomes low-temperature water and enters the heat medium water pump, and the cycle continues. The condensate heater and the ammonia heater in the heat medium water system of the utility model can be arranged in series, in parallel, or in series and in parallel. The heat medium water transfers the heat released by the flue gas to the ammonia and condensate. The heat medium water system is provided with an ammonia heater, and the room-temperature ammonia from the ammonia supply system enters the ammonia heater, absorbs heat and heats up, and then is sent to the ammonia burner of the boiler for combustion. The heat medium water system is provided with a condensate heater, and the condensate from the condensate system of the thermal power plant enters the condensate heater, absorbs heat and heats up, and then returns to the condensate system. When the amount of ammonia is large, the amount of heat medium water entering the condensate heater can be adjusted or closed to adjust the amount of heat released by the flue gas to the condensate (specifically, this can be achieved by adjusting the inlet valve, outlet valve and branch valve; for example, if the amount of heat medium water entering the condensate heater is to be closed, it can be achieved by closing the inlet valve and outlet valve and opening the branch valve at the same time). The condensate heater in the heat medium water system of the utility model can be set or not; when the condensate heater is set, the amount of heat medium water entering the condensate heater can be adjusted or closed to adjust the amount of heat released by the flue gas to the condensate.

[0020] In the utility model, the flue gas passes through the flue gas cooler and releases heat to the heat medium water, the ammonia passes through the ammonia heater and absorbs heat from the heat medium water and heats up, and the condensed water passes through the condensed water heater and absorbs heat from the heat medium water and heats up. The utility model adopts a closed-cycle heat medium water system, the heat absorbed from the flue gas side is used to heat the heat medium water, the low-temperature heat medium water is heated to become high-temperature heat medium water, and then the high-temperature heat medium water is used to heat the ammonia gas and the condensed water, the high-temperature heat medium water releases heat to become low-temperature heat medium water, and then returns to the flue gas side through the heat medium water pump to absorb heat, and so on.

[0021] Beneficial effects of the utility model:

[0022] (1) The utility model designs an ammonia heating system for improving boiler efficiency. The system utilizes the high-temperature flue gas discharged by the boiler to indirectly heat the ammonia, transfers the heat energy in the originally discharged high-temperature flue gas to the ammonia, and then recovers the originally wasted energy through the combustion of ammonia in the boiler, thereby improving the boiler efficiency, reducing the consumption of fuels such as ammonia and coal, and reducing the emission of pollutants and carbon dioxide in the flue gas, while reducing the operating costs of the power plant.

[0023] (2) Considering that ammonia is dangerous to a certain extent, in order to avoid leakage of ammonia, the utility model sets up a heat medium water circulation system as a medium for energy transfer, avoiding the pipeline corrosion and wear problems that may be caused by direct contact between the ammonia pipeline and the flue gas, thereby avoiding the problem of ammonia leakage and improving the safety and reliability of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] Figure 1 A schematic diagram of the structure of an ammonia heating system for improving boiler efficiency designed for Example 1 of the utility model;

[0026] Figure 2 A schematic diagram of the structure of an ammonia heating system for improving boiler efficiency designed for Example 2 of the utility model;

[0027] Figure 3 A schematic diagram of the structure of an ammonia heating system for improving boiler efficiency designed for Example 3 of the utility model;

[0028] Figure 4 A schematic structural diagram of an ammonia heating system for improving boiler efficiency designed for Example 4 of the utility model.

[0029] Markings in the figure: 1-combustion boiler, 2-ammonia burner, 3-air preheater, 4-dust collector, 5-desulfurization absorption tower, 6-chimney, 7-flue gas cooler, 8-heat medium water system, 9-ammonia supply system, 10-induced draft fan, 81-heat medium water pipe, 82-heat medium water pump, 83-ammonia heater, 84-condensate heater, 85-inlet valve, 86-outlet valve, 87-branch valve. DETAILED DESCRIPTION

[0030] 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.

[0031] 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.

[0032] Example 1

[0033] like Figure 1 As shown, an ammonia heating system for improving boiler efficiency is designed, which includes: a combustion boiler 1, an ammonia burner 2 arranged in the combustion boiler 1, an air preheater 3 connected to the flue gas outlet of the combustion boiler 1, and a dust collector 4, an induced draft fan 10, a desulfurization absorption tower 5 and a chimney 6 connected to the air preheater 3 in sequence along the flue gas flow direction;

[0034] The ammonia heating system further includes: four groups of flue gas coolers 7, a closed-cycle heat medium water system 8 and an ammonia supply system 9; the four groups of flue gas coolers 7 are all connected and arranged upstream of the chimney 6, and are used to provide a heat source for the heat medium water system 8, specifically, one group of flue gas coolers 7 is connected and arranged between the combustion boiler 1 and the air preheater 3, another group is connected and arranged between the air preheater 3 and the dust collector 4, and the remaining two groups are connected and arranged in sequence between the dust collector 4 and the desulfurization absorption tower 5;

[0035] The heat medium water system 8 includes: a heat medium water pipe 81, a heat medium water pump 82, a group of ammonia heaters 83 and a condensate water heater 84 for heating condensate water; the heat medium water pipe 81 is arranged in a closed cycle and is equipped with heat medium water driven by the heat medium water pump 82 to circulate, the heat medium water pipe 81 is connected to four groups of flue gas coolers 7 in sequence and the flue gas coolers 7 provide heat for them (specifically, heat the water therein); the condensate water heater 84 and the ammonia heater 83 are connected to the heat medium water pipe 81 in series, and the condensate water heater 84 is connected to the condensate water heater 84 in series. A heat medium water inlet valve 85 and a heat medium water outlet valve 86 are respectively arranged at the inlet and outlet of 4, and a branch valve 87 is also arranged on the heat medium water pipe 81 in parallel with the inlet valve 85; the hot water in the heat medium water pipe 81 is used to heat the ammonia heater 83 and the condensate heater 84; the pipeline for supplying ammonia in the ammonia supply system 9 is arranged in the ammonia heater 83, and the ammonia in the pipeline is heated by the ammonia heater 83 and then enters the ammonia burner 2 for combustion; the condensate from the condensate system of the power plant is heated by the condensate heater 84 and then goes to the condensate system.

[0036] In the utility model, the heat medium water transfers the heat released by the flue gas in the flue gas cooler 7 to the ammonia and condensed water. The heat medium water system 8 is provided with an ammonia heater 83, and the room temperature ammonia from the ammonia supply system 9 enters the ammonia heater 83, absorbs heat and heats up, and is sent to the ammonia burner 2 of the boiler 1 for combustion. The heat medium water system 8 is provided with a condensed water heater 84, and the condensed water from the low-pressure heater of the condensed water system of the thermal power plant enters the condensed water heater 84, absorbs heat and heats up, and then returns to the condensed water system. The utility model realizes the heating of ammonia and condensed water at the same time, thereby maximizing the recovery of flue gas waste heat.

[0037] When the amount of ammonia is large, the amount of heat medium water entering the condensate heater 84 can be adjusted or closed, and the amount of heat released by the flue gas to the condensate can be adjusted. For example, if the amount of heat medium water entering the condensate heater 84 needs to be closed, it can be achieved by closing the inlet valve 85 and the outlet valve 86 and opening the branch valve 87 at the same time.

[0038] Example 2

[0039] like Figure 2 As shown, an ammonia heating system for improving boiler efficiency is designed, which includes: a combustion boiler 1, an ammonia burner 2 arranged in the combustion boiler 1, an air preheater 3 connected to the flue gas outlet of the combustion boiler 1, and a dust collector 4, an induced draft fan 10, a desulfurization absorption tower 5 and a chimney 6 connected to the air preheater 3 in sequence along the flue gas flow direction;

[0040] The ammonia heating system further includes: a set of flue gas coolers 7, a closed-cycle heat medium water system 8 and an ammonia supply system 9; the flue gas cooler 7 is connected and arranged between the air preheater 3 and the dust collector 4, and is used as a heat source for the heat medium water system 8;

[0041] Among them, the heat medium water system 8 includes: a heat medium water pipe 81, a heat medium water pump 82 and a group of ammonia heaters 83; the heat medium water pipe 81 is set in a closed cycle and is equipped with heat medium water driven by the heat medium water pump 82 to circulate, the heat medium water pipe 81 is connected to the flue gas cooler 7 and is heated by the flue gas cooler 7; the ammonia heater 83 is connected to the heat medium water pipe 81, and the pipeline for supplying ammonia in the ammonia supply system 9 is set in the ammonia heater 83. The ammonia in the pipeline is heated by the ammonia heater 83 and enters the ammonia burner 2 for combustion.

[0042] The utility model uses the heat medium water system 8 as the intermediate heat transfer medium. First, the heat medium water system 8 absorbs the heat energy of the flue gas in the flue gas cooler 7, and then transfers it to the ammonia, so as to transfer the heat energy originally in the flue gas to the ammonia and then bring it back to the boiler for combustion, thus completing the recovery of energy in the flue gas and improving the boiler efficiency. At the same time, this method of the utility model also avoids direct contact between the high-temperature flue gas and the ammonia pipeline, avoids the problem of ammonia leakage caused by pipeline corrosion, and greatly improves the reliability of the system.

[0043] Example 3

[0044] like Figure 3 As shown, an ammonia heating system for improving boiler efficiency is designed, which includes: a combustion boiler 1, an ammonia burner 2 arranged in the combustion boiler 1, an air preheater 3 connected to the flue gas outlet of the combustion boiler 1, and a dust collector 4, an induced draft fan 10, a desulfurization absorption tower 5 and a chimney 6 connected to the air preheater 3 in sequence along the flue gas flow direction;

[0045] The ammonia heating system further includes: two groups of flue gas coolers 7, a closed-cycle heat medium water system 8 and an ammonia supply system 9; the two groups of flue gas coolers 7 are both connected and arranged upstream of the chimney 6, and are used to provide a heat source for the heat medium water system 8, specifically, one group of flue gas coolers 7 is connected and arranged between the air preheater 3 and the dust collector 4, and the other group is connected and arranged between the induced draft fan 10 and the desulfurization absorption tower 5;

[0046] The heat medium water system 8 includes: a heat medium water pipe 81, a heat medium water pump 82, a group of ammonia heaters 83 and a condensate water heater 84 for heating condensate water; the heat medium water pipe 81 is arranged in a closed cycle and is equipped with heat medium water driven by the heat medium water pump 82 to circulate, and the heat medium water pipe 81 is connected to the two groups of flue gas coolers 7 in turn and is heated by them; the condensate water heater 84 and the ammonia heater 83 are connected to the heat medium water pipe 81 in parallel, and the inlet and outlet of the condensate water heater 84 are respectively provided with A heat medium water inlet valve 85 and a heat medium water outlet valve 86, and a branch valve 87 are also arranged on the heat medium water pipe 81 in parallel with the inlet valve 85; the hot water in the heat medium water pipe 81 is used to provide heat for the ammonia heater 83 and the condensate heater 84; the pipeline for supplying ammonia in the ammonia supply system 9 is arranged in the ammonia heater 83, and the ammonia in the pipeline is heated by the ammonia heater 83 and then enters the ammonia burner 2 for combustion; the condensate from the condensate system of the power plant is heated by the condensate heater 84 and then goes to the condensate system.

[0047] The utility model is provided with a closed-loop heat medium water system 8, which includes a heat medium water pump 82, a condensate water heater 84 and an ammonia heater 83. The low-temperature water after being pressurized by the heat medium water pump 82 flows into two groups of flue gas coolers 7 in sequence. The flue gas cooler 7 transfers the heat released by the flue gas to the low-temperature water, so that the water temperature is increased, and becomes high-temperature water, which flows out of the flue gas cooler 7. The high-temperature water heated by the flue gas cooler 7 flows into the condensate water heater 84 and the ammonia heater 83 arranged in parallel in two ways respectively. After the condensate water and ammonia are cooled by heat release, they are both turned into low-temperature water. The two ways of low-temperature water merge into one way and enter the heat medium water pump 82, which drives the circulation.

[0048] Example 4

[0049] like Figure 4 As shown, an ammonia heating system for improving boiler efficiency is designed, which includes: a combustion boiler 1, an ammonia burner 2 arranged in the combustion boiler 1, an air preheater 3 connected to the flue gas outlet of the combustion boiler 1, and a dust collector 4, an induced draft fan 10, a desulfurization absorption tower 5 and a chimney 6 connected to the air preheater 3 in sequence along the flue gas flow direction;

[0050] The ammonia heating system further includes: two groups of flue gas coolers 7, a closed-cycle heat medium water system 8 and an ammonia supply system 9; the two groups of flue gas coolers 7 are both connected and arranged upstream of the chimney 6, and are used to provide a heat source for the heat medium water system 8, specifically, one group of flue gas coolers 7 is connected and arranged between the dust collector 4 and the induced draft fan 10, and the other group is connected and arranged between the induced draft fan 10 and the desulfurization absorption tower 5;

[0051] The heat medium water system 8 comprises: a heat medium water pipe 81, a heat medium water pump 82, two groups of ammonia heaters 83 and a condensate water heater 84; the heat medium water pipe 81 is arranged in a closed cycle and is equipped with heat medium water driven by the heat medium water pump 82 to circulate, and the heat medium water pipe 81 is connected to the two groups of flue gas coolers 7 in sequence and is heated by them; the condensate water heater 84 and one group of ammonia heaters 83 are connected to the heat medium water pipe 81 in parallel, and after parallel connection, the whole is arranged in series with another group of ammonia heaters 83; at the same time, at the inlet of the condensate water heater 84, the heat medium water pump 82 is connected to the two groups of flue gas coolers 7 in sequence, and ... A heat medium water inlet valve 85 and a heat medium water outlet valve 86 are respectively arranged at the outlet, and a branch valve 87 is also arranged on the heat medium water pipe 81 in parallel with the inlet valve 85; the hot water in the heat medium water pipe 81 is used to heat the ammonia heater 83 and the condensate heater 84; the pipeline for supplying ammonia in the ammonia supply system 9 is arranged in the ammonia heater 83, and the ammonia in the pipeline is heated in turn by two groups of ammonia heaters 83 and then enters the ammonia burner 2 for combustion; the condensate from the condensate system of the power plant is heated by the condensate heater 84 and then goes to the condensate system.

[0052] The low-temperature water after being pressurized by the heat medium water pump 82 flows into the two groups of flue gas coolers 7 in sequence. The flue gas cooler 7 transfers the heat released by the flue gas to the heat medium water in the heat medium water pipe 81, so that the water temperature of the heat medium water increases and becomes high-temperature water. After the high-temperature water flows out of the flue gas cooler 7, it flows into the condensate heater 84 and the ammonia heater 83 arranged in parallel in two ways. After the condensate and ammonia are cooled by heat release, they are all turned into low-temperature water. The two low-temperature waters merge into one and then enter another group of ammonia heaters 83 arranged in series. The low-temperature water after the ammonia is cooled by heat release enters the heat medium water pump 82 and is driven by it to circulate. Although the temperature of the merged low-temperature water is reduced, it is still higher than that of ammonia, and the ammonia can be used for waste heat. In this embodiment 4, the ammonia is heated separately by the two groups of ammonia heaters 83, and the heating effect is better. The temperature of the ammonia entering the ammonia burner 2 is relatively higher, and the energy recovery effect is relatively better.

[0053] 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. An ammonia heating system for improving boiler efficiency, characterized in that: The ammonia heating system comprises: a combustion boiler (1), an ammonia burner (2) arranged in the combustion boiler (1), an air preheater (3) connected to the flue gas outlet of the combustion boiler (1), and a dust collector (4), a desulfurization absorption tower (5) and a chimney (6) connected to the air preheater (3) in sequence along the flue gas flow direction; The ammonia heating system further comprises: at least one set of flue gas coolers (7), a closed-cycle heat medium water system (8) and an ammonia supply system (9); a plurality of the flue gas coolers (7) are connected and arranged upstream of the chimney (6) and are used to provide a heat source for the heat medium water system (8); the ammonia supplied in the ammonia supply system (9) is heated by the heat medium water system (8) and then enters the ammonia burner (2) for combustion.

2. The ammonia heating system for improving boiler efficiency according to claim 1, characterized in that: The heat medium water system (8) comprises: a heat medium water pipe (81), a heat medium water pump (82) and at least one set of ammonia heater (83); Wherein: the heat medium water pipe (81) is set in a closed cycle, and is heated by the flue gas cooler (7); water is set in the heat medium water pipe (81), and is driven to circulate by the heat medium water pump (82); the heat medium water pipe (81) is used to heat the ammonia heater (83); The ammonia supplied from the ammonia supply system (9) is heated by the ammonia heater (83) and then enters the ammonia burner (2) for combustion.

3. The ammonia heating system for improving boiler efficiency according to claim 2, characterized in that: The heat medium water system (8) further comprises a condensate water heater (84) for heating condensate water, and the condensate water heater (84) is connected to and provided on the heat medium water pipe (81) and is heated thereby; an inlet valve (85) and an outlet valve (86) are respectively provided at the inlet and outlet of the condensate water heater (84); and a branch valve (87) is also provided on the heat medium water pipe (81).

4. The ammonia heating system for improving boiler efficiency according to claim 3, characterized in that: The condensate heater (84) and the ammonia heater (83) are arranged in series.

5. The ammonia heating system for improving boiler efficiency according to claim 3, characterized in that: The condensate heater (84) and the ammonia heater (83) are arranged in parallel.

6. The ammonia heating system for improving boiler efficiency according to claim 3, characterized in that: The ammonia heaters (83) are arranged in two groups, and the condensate heater (84) is arranged in parallel with one group of the ammonia heaters (83), and then the whole is arranged in series with the other group of the ammonia heaters (83).

7. The ammonia heating system for improving boiler efficiency according to claim 1, characterized in that: The ammonia heating system further comprises an induced draft fan (10), and the induced draft fan (10) is arranged in communication between the dust collector (4) and the desulfurization absorption tower (5).

8. The ammonia heating system for improving boiler efficiency according to claim 1, characterized in that: The flue gas coolers (7) are arranged in four groups; Among them: one group of flue gas coolers (7) is connected and arranged between the combustion boiler (1) and the air preheater (3), another group is connected and arranged between the air preheater (3) and the dust collector (4), and the remaining two groups are connected and arranged in sequence between the dust collector (4) and the desulfurization absorption tower (5).

9. The ammonia heating system for improving boiler efficiency according to claim 1, characterized in that: The flue gas coolers (7) are arranged in one group, two groups or three groups.

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