Flue gas ammonia heat exchange system for improving boiler efficiency

Abstract

The utility model discloses a flue gas ammonia heat exchange system capable of improving boiler efficiency. The heat exchange system comprises a combustion boiler, an ammonia gas burner arranged in the combustion boiler, an air preheater communicated with a flue gas outlet of the combustion boiler, and a dust remover, a desulfurizing absorption tower and a chimney which are sequentially communicated with the air preheater, the system further comprises an ammonia gas supply system and at least one flue gas cooler; the flue gas cooler is communicated with the upstream of the chimney; ammonia gas supplied by the ammonia gas supply system is preheated by the flue gas cooler and then enters the ammonia gas burner. The flue gas-ammonia gas heat exchange system capable of improving the boiler efficiency can improve boiler combustion, improve the boiler efficiency and improve the boiler performance, and is suitable for an ammonia-doped or pure ammonia combustion boiler. According to the flue gas ammonia heat exchange system, the exhaust gas temperature of the combustion boiler can be reduced, the boiler efficiency is improved, the boiler performance is improved, and the purposes of reducing the consumption of ammonia gas and fire coal and saving the fuel cost are achieved.

Description

Technical Field

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

[0002] 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 fuels of boilers are mainly coal, natural gas and fuel oil. Since these traditional fuels contain carbon, they will produce a large amount of carbon dioxide after burning to generate electricity, thus affecting the carbon emission reduction target; ammonia, as a zero-carbon fuel, can partially or completely replace carbon-based fuels for boiler combustion and power generation.

[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 increased operating costs, resulting in poor economic efficiency. For example, for the current pure bituminous coal-fired boiler, after 60% ammonia is added, the boiler exhaust gas temperature increases from 114°C to 140°C, and the boiler efficiency drops from 95.1% to 93.35%. Utility Model Content

[0004] The purpose of the utility model is to design a smoke-ammonia heat exchange system for improving boiler efficiency, thereby solving the above problems in view of the problems of low boiler efficiency and increased operating costs in existing pure coal-fired boilers after ammonia combustion.

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

[0006] A flue gas and ammonia heat exchange system for improving boiler efficiency is provided, the heat exchange system comprising: a combustion boiler, an ammonia burner arranged in the combustion boiler, an air preheater connected to the 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; the heat exchange system also comprises an ammonia supply system and at least one flue gas cooler; the flue gas cooler is connected and arranged upstream of the chimney; the ammonia supplied in the ammonia supply system is preheated by the flue gas cooler and then enters the ammonia burner. Specifically, the combustion boiler can be a pulverized coal boiler, a circulating fluidized bed boiler, a gas boiler or an oil boiler, etc.

[0007] The smoke-ammonia (smoke-ammonia) heat exchange system designed by the utility model for improving boiler efficiency can improve boiler combustion, increase boiler efficiency, and enhance boiler performance, and is suitable for ammonia-blended or pure ammonia combustion boilers.

[0008] Furthermore, a smoke-ammonia heat exchange system for improving boiler efficiency: the heat exchange system further includes an induced draft fan, and the induced draft fan is connected and arranged between the dust collector and the desulfurization absorption tower. That is, the smoke outlet of the dust collector is connected to the smoke inlet of the induced draft fan, and the smoke outlet of the induced draft fan is connected to the smoke inlet of the desulfurization absorption tower.

[0009] Furthermore, a smoke-ammonia heat exchange system for improving boiler efficiency: the number of the flue gas coolers is four; wherein: one flue gas cooler is connected and arranged between the combustion boiler and the air preheater, one flue gas cooler is connected and arranged between the air preheater and the dust collector, and the remaining two flue gas coolers are connected and arranged in sequence between the dust collector and the desulfurization absorption tower.

[0010] Furthermore, a flue gas and ammonia heat exchange system for improving boiler efficiency: the flue gas cooler is set to three. Specifically, the flue gas cooler between the combustion boiler and the air preheater can be subtracted from the above four flue gas coolers to form a three-series flue gas cooler structure.

[0011] Furthermore, a smoke-ammonia heat exchange system for improving boiler efficiency: the flue gas cooler is provided in two; one of the flue gas coolers is connected and arranged between the air preheater and the dust collector, and the other is connected and arranged between the dust collector and the desulfurization absorption tower.

[0012] Furthermore, a smoke-ammonia heat exchange system for improving boiler efficiency: the flue gas cooler is provided in one piece, and the flue gas cooler is connected and arranged between the air preheater and the dust collector, or between the dust collector and the desulfurization absorption tower.

[0013] Beneficial effects of the utility model:

[0014] (1) The smoke-ammonia heat exchange system designed by the utility model for improving boiler efficiency can reduce the exhaust temperature of the combustion boiler, thereby improving the boiler efficiency and performance, thereby reducing the consumption of ammonia and coal and saving fuel costs.

[0015] (2) The smoke-ammonia heat exchange system of the utility model can heat ammonia with the smoke emitted by the combustion boiler, transfer the heat of the originally emitted smoke to the ammonia, and recover the energy that was originally wasted 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 smoke, while reducing the operating costs of the power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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.

[0017] Figure 1 A schematic diagram of the structure of the smoke-ammonia heat exchange system designed for Example 1 of the utility model;

[0018] Figure 2 A schematic diagram of the structure of the smoke-ammonia heat exchange system designed for Example 2 of the utility model;

[0019] Figure 3 A schematic structural diagram of the smoke-ammonia heat exchange system designed for Example 3 of the utility model.

[0020] Markings in the figure: 1-combustion boiler, 2-ammonia burner, 3-air preheater, 4-dust collector, 5-desulfurization absorption tower, 6-chimney, 7-ammonia supply system, 8-flue gas cooler, 9-induced draft fan. DETAILED DESCRIPTION

[0021] 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.

[0022] Terminology explanation:

[0023] (1) Ammonia-blended combustion: adding ammonia as fuel to a traditional coal-fired, gas-fired or oil-fired boiler to participate in boiler combustion together with the original coal, gas or oil.

[0024] (2) Pure ammonia combustion - using ammonia as the only fuel for boiler combustion.

[0025] Example 1

[0026] like Figure 1 As shown, a flue gas and ammonia heat exchange system for improving boiler efficiency, the heat exchange 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, an induced draft fan 9, a desulfurization absorption tower 5 and a chimney 6 connected to the air preheater 3 in sequence;

[0027] It also includes an ammonia supply system 7 and four flue gas coolers 8, and one of the flue gas coolers 8 is connected and arranged between the combustion boiler 1 and the air preheater 3, another flue gas cooler 8 is connected and arranged between the air preheater 3 and the dust collector 4, and the remaining two flue gas coolers 8 are connected and arranged between the dust collector 4 and the desulfurization absorption tower 5 in sequence, and the induced draft fan 9 is also arranged between the two flue gas coolers 8; the ammonia supply system 7 is relatively independently arranged, and the ammonia supplied from the ammonia supply system 7 is preheated by the above-mentioned four flue gas coolers 8 in sequence and then enters the ammonia burner 2 for combustion to replace part or all of the coal, thereby effectively reducing carbon dioxide emissions.

[0028] Room temperature ammonia from the ammonia supply system 7 passes through a plurality of flue gas coolers 8, absorbs the heat released by the boiler flue gas, and raises the temperature of the ammonia. After flowing out of the flue gas cooler 8, the ammonia enters the ammonia burner 2 of the boiler for combustion.

[0029] Example 2

[0030] like Figure 2 As shown, a flue gas and ammonia heat exchange system for improving boiler efficiency, the heat exchange 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, an induced draft fan 9, a desulfurization absorption tower 5 and a chimney 6 connected to the air preheater 3 in sequence;

[0031] It also includes an ammonia supply system 7 and a flue gas cooler 8, and the flue gas cooler 8 is connected and arranged between the air preheater 3 and the dust collector 4; the ammonia supply system 7 is relatively independently arranged, and the ammonia supplied from the ammonia supply system 7 is preheated by the flue gas cooler 8 and then enters the ammonia burner 2 for combustion to replace part or all of the coal, thereby effectively reducing carbon dioxide emissions.

[0032] Example 3

[0033] like Figure 3 As shown, a flue gas and ammonia heat exchange system for improving boiler efficiency, the heat exchange 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, an induced draft fan 9, a desulfurization absorption tower 5 and a chimney 6 connected to the air preheater 3 in sequence;

[0034] It also includes an ammonia supply system 7 and two flue gas coolers 8, and one of the flue gas coolers 8 is connected and arranged between the air preheater 3 and the dust collector 4, and the other flue gas cooler 8 is connected and arranged between the dust collector 4 and the desulfurization absorption tower 5 (specifically, it is arranged between the induced draft fan 9 and the desulfurization absorption tower 5); the ammonia supply system 7 is relatively independently arranged, and the ammonia supplied from the ammonia supply system 7 is preheated by the above-mentioned two flue gas coolers 8 in turn and then enters the ammonia burner 2 for combustion to replace part or all of the coal, thereby effectively reducing carbon dioxide emissions.

[0035] The working principle of this utility model:

[0036] First, the high-temperature flue gas from the outlet of the air preheater 3 of the combustion boiler 1 releases heat through the flue gas cooler 8, and the room-temperature ammonia passing through the flue gas cooler 8 completes the heat exchange with the high-temperature flue gas. At this time, the flue gas is cooled and the ammonia is heated. The heated ammonia enters the ammonia burner 2 for combustion, and the cooled flue gas is discharged through the chimney 6 after dust removal and desulfurization. Ammonia completes the role of bringing the heat energy originally wasted in the high-temperature flue gas back to the boiler for re-combustion, realizing the recovery of flue gas heat energy, which can improve the efficiency of the boiler, reduce the consumption of fuels such as ammonia and coal, and reduce the emission of pollutants and carbon dioxide in the flue gas, while reducing the operating costs of the power plant. In addition, ammonia is easy to condense, and preheating ammonia can also prevent it from condensing during the process of being transported to the ammonia burner 2.

[0037] 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 smoke-ammonia heat exchange system for improving boiler efficiency, characterized in that: The heat exchange 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; It also includes an ammonia supply system (7) and at least one flue gas cooler (8); the flue gas cooler (8) is arranged upstream of the chimney (6); the ammonia supplied by the ammonia supply system (7) is preheated by the flue gas cooler (8) and then enters the ammonia burner (2).

2. A smoke-ammonia heat exchange system for improving boiler efficiency according to claim 1, characterized in that: The heat exchange system further comprises an induced draft fan (9), and the induced draft fan (9) is arranged in communication between the dust collector (4) and the desulfurization absorption tower (5).

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

4. The smoke-ammonia heat exchange system for improving boiler efficiency according to claim 3, characterized in that: The number of the flue gas coolers (8) is three.

5. The smoke-ammonia heat exchange system for improving boiler efficiency according to claim 1, characterized in that: The flue gas cooler (8) is provided in two pieces; One of the flue gas coolers (8) is arranged in communication between the air preheater (3) and the dust collector (4), and the other is arranged in communication between the dust collector (4) and the desulfurization absorption tower (5).

6. The smoke-ammonia heat exchange system for improving boiler efficiency according to claim 1, characterized in that: The flue gas cooler (8) is provided in one piece, and the flue gas cooler (8) is arranged in communication between the air preheater (3) and the dust collector (4), or between the dust collector (4) and the desulfurization absorption tower (5).

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