A supercritical dual heat pipe heat exchanger for flue gas waste heat recovery

Abstract

This utility model relates to the field of waste heat recovery technology and discloses a supercritical dual heat pipe heat exchanger for flue gas waste heat recovery. It consists of three parts: a gravity heat pipe, a supercritical heat pipe, and a hot water heater. The device uses the gravity heat pipe to absorb waste heat from the flue gas and then transfers the heat to the hot water heater through the supercritical heat pipe. At the same time, the two working fluids for heat exchange are completely separated by the heat-insulating baffle in the middle of the gravity heat pipe. During operation, if a single heat pipe is damaged due to wear, corrosion, overheating, etc., it will not affect the operation of the heat exchanger. It has high reliability for heat exchange of flammable, explosive, and highly corrosive fluids, thereby achieving the purpose of waste heat recovery and reducing overall energy consumption.

Description

Technical Field

[0001] This utility model relates to the field of waste heat recovery technology, specifically a supercritical dual heat pipe heat exchanger for flue gas waste heat recovery. Background Technology

[0002] Waste heat resources refer to energy that, under current conditions, can be recovered or reused but has not yet been utilized, primarily industrial waste heat resources. Industrial waste heat resources are prevalent in industries such as metallurgy, chemicals, building materials, papermaking, textiles, and machinery. They are mainly found in the waste gas, wastewater, and waste heat emitted during the production processes of industrial enterprises' heat conversion equipment and energy-consuming equipment. Among these, flue gas waste heat resources are widely distributed in various smelting furnaces, heating furnaces, and internal combustion engines in industries such as metallurgy, chemicals, building materials, machinery, and power, accounting for approximately 50% of the total waste heat resources and serving as the primary source for waste heat recovery and utilization. Utilizing waste heat recovery technology to recover and utilize this energy can not only reduce energy consumption and production costs but also minimize negative environmental impacts, making it a crucial means of energy conservation and environmental protection.

[0003] In existing technology (CN201764867U), heat dissipation fins are added to the heat dissipation pipe to increase the heat exchange area of ​​the heat dissipation pipe and improve the heat exchange capacity between the heat dissipation pipe and the heated medium, thereby improving the waste heat recovery efficiency of the flue gas waste heat recovery device. However, the heated medium and the flue gas are not completely isolated in this technology. If the heat pipe is damaged, it will cause the equipment to stop operating and the heated medium to enter the flue gas, causing environmental pollution, increasing energy consumption, and increasing environmental thermal pollution. It has defects in terms of energy saving and environmental protection. Utility Model Content

[0004] To address the shortcomings of existing technologies, this invention provides a supercritical dual heat pipe heat exchanger for flue gas waste heat recovery. This device achieves flue gas waste heat recovery while effectively avoiding the drawbacks of existing flue gas waste heat recovery technologies or devices, realizing constant-temperature heat exchange and complete isolation between the heat exchange medium and the flue gas, thus solving the aforementioned technical problems.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a supercritical dual heat pipe heat exchanger for flue gas waste heat recovery, comprising a flue, a gravity heat pipe fixedly inserted inside the flue, the gravity heat pipe being divided into an evaporation section and a condensation section by a heat-insulating partition, the evaporation section being located inside the flue, the condensation section being located inside the supercritical heat pipe, the supercritical heat pipe being fixedly connected to the flue by the heat-insulating partition, and a hot water heater being fixedly inserted inside the cavity of the supercritical heat pipe.

[0006] As a preferred technical solution of this utility model, the gravity heat pipe is provided with a number of sets of fins evenly distributed and fixedly installed on the outer wall of the evaporation section inside the flue to increase the heat exchange area.

[0007] As a preferred technical solution of this utility model, the condensation section of the gravity heat pipe is located at the central axis of the supercritical heat pipe cavity, providing heat transfer of flue gas to the supercritical heat pipe, and hot water heaters that absorb heat from the inside of the supercritical heat pipe are arranged on both sides.

[0008] Compared with the prior art, this utility model provides a supercritical dual heat pipe heat exchanger for flue gas waste heat recovery, which has the following beneficial effects: 1. In this invention, the hot and cold fluids can be completely separated by the heat insulation partition in the middle of the gravity heat pipe. The function of the gravity heat pipe is to transfer the heat of the flue gas to the inside of the supercritical heat pipe. When the heat exchanger tube on the air side of a conventional heat exchanger is worn and damaged, the working fluid inside and outside the heat exchanger tube will flow to each other and leak. However, in this invention, even when the air side of the gravity heat pipe is worn and damaged, the heat exchange side with the supercritical heat pipe can still ensure that the working fluid will not leak. Therefore, when a single heat pipe is damaged due to wear, corrosion, overheating, etc. during operation, it will not affect the operation of the heat exchanger. It has high reliability for heat exchange of flammable, explosive, and highly corrosive fluids.

[0009] 2. The supercritical heat pipe of this invention utilizes the unique properties of the working fluid in the supercritical state to achieve efficient heat energy conversion. When the pressure and temperature of the working fluid exceed its critical point, its physical properties will change, exhibiting high thermal conductivity and low viscosity, thus achieving rapid and efficient heat energy conversion. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the heat exchange process of this utility model.

[0011] The components include: 1. flue; 2. gravity heat pipe; 3. supercritical heat pipe; 4. insulation partition; and 5. hot water heater. Detailed Implementation

[0012] The embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of this utility model.

[0013] In the description of this utility model, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In addition, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0014] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0015] This device consists of three parts: a gravity heat pipe 2, a supercritical heat pipe 3, and a hot water heater 5. The gravity heat pipe 2 is installed in the flue 1 or a newly added side flue duct and is divided into an evaporation section and a condensation section by a heat insulation partition 4. The evaporation section is located inside the flue duct, and the condensation section is located inside the supercritical heat pipe. Its function is to transfer the heat from the flue gas to the working fluid in the supercritical heat pipe 3 and to connect the flue 1 and the supercritical heat pipe 3. The hot water heater 5 is arranged inside the supercritical heat pipe 3. After the working fluid in the supercritical heat pipe 3 absorbs heat and heats up, it condenses and releases heat on the wall of the hot water heater 5. The water inside the hot water heater 5 absorbs heat to complete the heating of the water. In this device, the heat insulation partition is made of two layers of carbon steel or stainless steel plates, with heat insulation material filling the middle to provide heat insulation.

[0016] The biggest difference between this device and existing flue gas waste heat recovery devices lies in its use of dual heat pipes as heat transfer elements. This offers advantages such as high heat transfer efficiency, compact structure, low fluid resistance, and better control of dew point corrosion. In this device, the supercritical heat pipe 3 utilizes the unique properties of the working fluid in the supercritical state to achieve efficient thermal energy conversion. When the pressure and temperature of the working fluid exceed its critical point, its physical properties change, exhibiting higher thermal conductivity and lower viscosity, thus achieving rapid and efficient thermal energy conversion.

[0017] The operation process of this device is as follows: A supercritical dual heat pipe heat exchanger is added to the original flue gas system equipment. It is arranged after the flue gas desulfurization and denitrification device and before the dust collector. It is installed in flue duct 1 or the newly added side flue duct. When the flue gas at a certain temperature flows through the gravity heat pipe 2, the heat carried by the flue gas is first transferred to the working fluid in the evaporation section of the gravity heat pipe 2 through the tube shell. After the working fluid in the evaporation section is heated, it will produce boiling or evaporation, converting the heat of the flue gas into the latent heat of vaporization of the working fluid in the gravity heat pipe 2. The working fluid changes from liquid to gas. The gaseous working fluid flows to the condensation section due to the density difference. In the condensation section, the gaseous working fluid transfers the latent heat of vaporization to the supercritical working fluid in the supercritical heat pipe 3 through the tube shell. The gaseous working fluid condenses into liquid and flows back to the evaporation section for evaporation again under the action of gravity (or liquid wick).

[0018] The gravity heat pipe 2 is located inside the flue 1 and has several sets of fins evenly distributed and fixedly installed on the outer wall of the evaporation section. The fins are designed to increase the heat exchange area while increasing the weight of the equipment by a small amount.

[0019] When this utility model gravity heat pipe is used for waste heat recovery from corrosive flue gas, the heat exchange between the corrosive flue gas and the condensation section of the gravity heat pipe can be controlled by adjusting the length of the evaporation section or the fin spacing during manufacturing. This achieves the purpose of adjusting the wall temperature of the gravity heat pipe, ensuring that the wall temperature is always higher than the dew point temperature of the corrosive flue gas, and setting a certain safety range, thereby avoiding dew point corrosion of the pipe wall.

[0020] After absorbing the latent heat of vaporization released by the gravity heat pipe 2, the working fluid in the supercritical heat pipe 3 will have an increased temperature and will transfer the heat to the hot water heater 5 arranged in the supercritical heat pipe 3. The water in the hot water heater 5 will absorb the heat and complete the heating of the water. At the same time, the temperature of the supercritical working fluid will decrease and exchange heat with the gravity heat pipe 2 again.

[0021] Gravity heat pipe 2 and supercritical heat pipe 3 alternately, thus achieving the transfer and exchange of heat between the two media. The specific heat exchange process is shown in the diagram. Figure 1 .

[0022] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A supercritical dual heat pipe heat exchanger for flue gas waste heat recovery, comprising a flue (1), characterized in that: A gravity heat pipe (2) is fixedly inserted inside the flue (1). The gravity heat pipe (2) is divided into an evaporation section and a condensation section by a heat insulation partition (4). The evaporation section is located inside the flue (1), and the condensation section is located inside the supercritical heat pipe (3). The supercritical heat pipe (3) is fixedly connected to the flue (1) through the heat insulation partition (4). A hot water heater (5) is fixedly inserted inside the cavity of the supercritical heat pipe (3).

2. A supercritical dual heat pipe heat exchanger for flue gas waste heat recovery according to claim 1, characterized in that: The gravity heat pipe (2) is located inside the flue (1) and its outer wall of the evaporation section is uniformly distributed with several sets of fins for increasing the heat exchange area.

3. A supercritical dual heat pipe heat exchanger for flue gas waste heat recovery according to claim 1, characterized in that: The condensation section of the gravity heat pipe (2) is located on the central axis of the cavity of the supercritical heat pipe (3), providing heat transfer of flue gas to the supercritical heat pipe (3), and hot water heaters (5) that absorb heat from the inside of the supercritical heat pipe (3) are distributed on both sides.

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