CN-122015110-A - Air preheater and boiler system

CN122015110ACN 122015110 ACN122015110 ACN 122015110ACN-122015110-A

Abstract

The application discloses an air preheater and a boiler system, and belongs to the technical field of boilers. The air preheater comprises a plurality of composite heat pipes and a cooling water collecting and distributing device, wherein the composite heat pipes are three-medium composite heat pipes with built-in cooling water pipes, so that the cooperative heat exchange among smoke, air and cooling water can be realized, the recovered smoke waste heat can heat the air and the cooling water, and the application scene of the air preheater can be widened. The cooling water flow in the composite heat pipe is regulated through the cooling water collecting and distributing device, and the condensation rate of working medium steam is regulated, so that the steam pressure difference and the flow velocity inside the composite heat pipe are changed, the heat transfer quantity of the composite heat pipe is accurately regulated, and the adaptability of the air preheater to load and working condition fluctuation is improved. Therefore, the comprehensive utilization of the waste heat of the flue gas can be realized, the energy waste is reduced, the dependence on a heater is reduced, and the running consumption of the boiler is saved.

Inventors

XU YIFAN
CHEN JIAJIAN
LIN XIANG
XIE QINGLIANG
HUANG JUFU

Assignees

福建龙净环保股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260324

Claims (10)

1. An air preheater is characterized by comprising a plurality of composite heat pipes and a cooling water collecting and matching device; The composite heat pipes are arranged along the flow direction of the flue gas, and comprise pipe bodies, liquid working media packaged in the pipe bodies and cooling water pipes arranged in the pipe bodies; The cooling water collecting and distributing device is communicated with the cooling water pipe and used for adjusting the flow of cooling water in the cooling water pipe.
2. The air preheater according to claim 1, wherein said plurality of composite heat pipes comprises at least one first composite heat pipe and at least one second composite heat pipe arranged in a direction of flue gas flow; the cooling water collecting and distributing device comprises a first collecting and distributing component and a second collecting and distributing component, the first collecting and distributing component is communicated with a cooling water pipe in the first composite heat pipe, and the second collecting and distributing component is communicated with the cooling water pipe in the second composite heat pipe.
3. The air preheater according to claim 2, wherein said first composite heat pipe comprises a first pipe body and flue-side heat fins, and said second composite heat pipe comprises a second pipe body; The flue gas side radiating fins are fixed on the outer side of the pipe section of the first pipe body, which is positioned in flue gas; And the outer side of the pipe section of the second pipe body positioned in the flue gas is a light pipe.
4. An air preheater according to claim 3, wherein at least the section of the second pipe section located in the flue gas is a corrosion resistant section, said corrosion resistant section being corrosion resistant by at least one of the wall thickness of said corrosion resistant section being greater than the wall thickness of said first pipe section, the outside of said corrosion resistant section being coated with a corrosion resistant coating, the material of said corrosion resistant section being a corrosion resistant material.
5. The air preheater according to claim 1, wherein the number of first composite heat pipes in said air preheater is positively correlated with the flue gas temperature prior to flowing through said first composite heat pipes; the number of second composite heat pipes in the air preheater is positively correlated with at least one of sulfur content and ammonia content in the flue gas.
6. The air preheater according to claim 2, wherein said first collector assembly is configured to adjust the output water flow rate such that the temperature of at least a portion of the flue gas flowing through said first composite heat pipe is above a first preset temperature based on at least one of the flue gas temperature and the flue gas flow rate before flowing through said first composite heat pipe; The second collection assembly is configured to adjust the output water flow based on at least one of a flue gas temperature, a flue gas flow, a sulfur content and an ammonia content in the flue gas before flowing through the second composite heat pipe such that a temperature of at least a portion of the flue gas flowing through the second composite heat pipe is below a second preset temperature, the first preset temperature being above a flue gas acid dew point, and the second preset temperature being below the flue gas acid dew point.
7. The air preheater according to claim 2, wherein said first and second collector assemblies each comprise a water inlet header, a water outlet header, and a plurality of connecting tubes, said plurality of composite heat pipes comprising a plurality of said first composite heat pipes and a plurality of said second composite heat pipes arranged in a direction of flue gas flow; The plurality of first composite heat pipes are connected in series through a plurality of connecting pipes of the first collecting and matching assembly to form a first cooling loop, and a water inlet header and a water outlet header of the first collecting and matching assembly are respectively connected to two ends of the first cooling loop; The plurality of second composite heat pipes are connected in series through the plurality of connecting pipes of the second collecting and matching assembly to form a second cooling loop, and the water inlet header and the water outlet header of the second collecting and matching assembly are respectively connected to two ends of the second cooling loop.
8. The air preheater as set forth in claim 7, wherein said connecting tube is detachably connected to said cooling water tubes so that any one of said cooling water tubes can be isolated from the cooling circuit in which it is located.
9. The air preheater according to claim 1, wherein said tube body comprises a condensing tube section in the air, a cooling water tube is disposed in said condensing tube section, and said cooling water tube is U-shaped; The ratio of the outer surface area of the cooling water pipe to the inner surface area of the condensing pipe section is in the range of 0.4-0.75, the ratio of the height of the cooling water pipe to the length of the condensing pipe section in the axial direction of the pipe body is in the range of 0.6-0.9, and the ratio of the outer sectional area of the cooling water pipe to the inner sectional area of the condensing pipe section is in the range of 0.1-0.2.
10. A boiler system comprising a boiler body, a flue connected to the boiler body, and an air preheater disposed in the flue, the air preheater being a regulated heat pipe air preheater as set forth in any one of claims 1-9, the flue comprising a horizontal flue or a vertical flue; When the air preheater is installed in the vertical flue, the composite heat pipe is obliquely arranged relative to the horizontal plane, one end provided with the cooling water pipe faces upwards, and when the air preheater is installed in the horizontal flue, the composite heat pipe is perpendicular to the horizontal plane, and one end provided with the cooling water pipe faces upwards.

Description

Air preheater and boiler system Technical Field The application relates to the technical field of boilers, in particular to an air preheater and a boiler system. Background The air preheater is used as heat exchange equipment commonly used in boiler systems, is widely applied to the industrial fields of thermal power generation and the like, and is used for recovering flue gas waste heat and improving boiler efficiency. However, boiler flue gas generally contains SO 2 and escaping ammonia caused by a denitration process, and ammonium bisulfate generated by the reaction of the SO 2 and the escaping ammonia can be condensed and attached to the surface of a heat exchange element in a low-temperature section, SO that the problems of air preheater blockage, resistance rise, heat transfer efficiency reduction and the like are caused. To alleviate the problems of blockage and corrosion caused by ammonium bisulfate, a mode of adding a heater is generally adopted, and the temperature of air entering the air preheater is increased to raise the wall temperature, so that the condensation of sulfuric acid is inhibited. However, the method has limited regulation capability, is difficult to meet the requirement of boiler load fluctuation on accurate control of flue gas temperature, and needs to continuously input a steam heat source under a low-load working condition, so that the operation energy consumption is increased. Disclosure of Invention The embodiment of the application provides an air preheater and a boiler system. The technical scheme is as follows: according to an aspect of the present application, there is provided an air preheater including a plurality of composite heat pipes and a cooling water collecting and distributing device; The composite heat pipes are arranged along the flow direction of the flue gas, and comprise pipe bodies, liquid working media packaged in the pipe bodies and cooling water pipes arranged in the pipe bodies; The cooling water collecting and distributing device is communicated with the cooling water pipe and used for adjusting the flow of cooling water in the cooling water pipe. Optionally, the plurality of composite heat pipes includes at least one first composite heat pipe and at least one second composite heat pipe arranged along a direction in which the flue gas flows; the cooling water collecting and distributing device comprises a first collecting and distributing component and a second collecting and distributing component, the first collecting and distributing component is communicated with a cooling water pipe in the first composite heat pipe, and the second collecting and distributing component is communicated with the cooling water pipe in the second composite heat pipe. Optionally, the first composite heat pipe comprises a first pipe body and a flue gas side radiating fin, and the second composite heat pipe comprises a second pipe body; The flue gas side radiating fins are fixed on the outer side of the pipe section of the first pipe body, which is positioned in flue gas; And the outer side of the pipe section of the second pipe body positioned in the flue gas is a light pipe. Optionally, the pipe section of the second pipe body at least positioned in the flue gas is a corrosion-resistant pipe section, and the corrosion-resistant pipe section is corrosion-resistant by at least one mode that the wall thickness of the corrosion-resistant pipe section is larger than that of the first pipe body, the outer side of the corrosion-resistant pipe section is coated with a corrosion-resistant coating, and the corrosion-resistant pipe section is made of a corrosion-resistant material. Optionally, the number of first composite heat pipes in the air preheater is positively correlated with the flue gas temperature before flowing through the first composite heat pipes; the number of second composite heat pipes in the air preheater is positively correlated with at least one of sulfur content and ammonia content in the flue gas. Optionally, the first collecting and matching component is configured to adjust the output water flow based on at least one of the temperature of the flue gas and the flow rate of the flue gas before the flue gas flows through the first composite heat pipe, so that the temperature of at least part of the flue gas flowing through the first composite heat pipe is higher than a first preset temperature; The second collection assembly is configured to adjust the output water flow based on at least one of a flue gas temperature, a flue gas flow, a sulfur content and an ammonia content in the flue gas before flowing through the second composite heat pipe such that a temperature of at least a portion of the flue gas flowing through the second composite heat pipe is below a second preset temperature, the first preset temperature being above a flue gas acid dew point, and the second preset temperature being below the flue gas acid dew point. Optionally, the first collectin