A finned internal spiral tube heat exchanger for boilers

Abstract

The present invention discloses a finned inner spiral tube heat exchanger for a boiler, which belongs to the technical field of heat exchange equipment and comprises a heat exchange tube, a fin and a spiral channel. The heat exchange tube comprises an outer wall surface and an inner wall surface. Fins are arranged outside the tube wall of the heat exchange tube. The fins are of a spiral structure and are fixed to the heat exchange tube by winding. A space for a first liquid to pass through is formed between the outer wall surface and the inner wall surface of the heat exchange tube. A first liquid inlet is arranged at the bottom of the space and a first liquid outlet is arranged at the top. A spiral channel for a second liquid to pass through is arranged inside the tube wall of the heat exchange tube. The top of the spiral channel is the second liquid inlet and the bottom is the second liquid outlet. By adopting the technical solution of the present invention, the heat of high-temperature exhaust gas can be more utilized compared with a traditional heat exchanger, and the emission temperature of the high-temperature exhaust gas can be lower, thereby achieving the purpose of energy saving and environmental protection. The heat exchanger has the characteristics of simple structure, low processing cost and energy saving and environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of heat exchange equipment, and in particular relates to a fin-type internal spiral tube heat exchanger for a boiler. Background Art

[0002] Heat exchangers are widely used in chemical industry, petroleum, electric power and other fields due to their strong structure, flexible use and strong adaptability. With the special requirements of microelectronics, medical, aerospace and other fields, heat exchangers are developing towards miniaturization. There is a lot of room for improvement in design methods, structural forms, material parameters and other aspects. At present, the research on shell-and-tube heat exchangers is mainly based on the enhancement of convective heat transfer in the tube. The main mechanism is that when heat exchange is carried out, the thermal resistance is mainly concentrated in the boundary layer. The key to enhancing heat transfer is to thin or destroy the boundary layer to achieve the purpose of enhancing heat transfer.

[0003] The heat loss of flue gas in coal-fired power plants is the largest of all heat losses in power plant boilers, generally 5% to 8%, accounting for 80% or more of the total heat loss of the boiler. The main factor affecting the heat loss of flue gas is the flue gas temperature of the boiler. Generally, the heat loss of flue gas increases with every 20°C increase in the flue gas temperature. At present, the traditional heat exchanger has limited heat recovery of high-temperature exhaust gas, resulting in a part of heat loss, causing energy waste, and the temperature of high-temperature exhaust gas emissions is also too high. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a finned internal spiral tube heat exchanger for a boiler, which can utilize more of the heat of high-temperature exhaust gas than traditional heat exchangers and make the discharge temperature of the high-temperature exhaust gas lower, thereby achieving the purpose of energy saving and environmental protection.

[0005] The finned internal spiral tube heat exchanger for a boiler is characterized in that it includes a heat exchange tube, fins and a spiral channel. The heat exchange tube includes an outer wall surface and an inner wall surface. Fins are provided outside the tube wall of the heat exchange tube. The fins are of a spiral structure and are fixed to the heat exchange tube by winding. A space for a first liquid to pass through is formed between the outer wall surface and the inner wall surface of the heat exchange tube. A first liquid inlet is provided at the bottom of the space and a first liquid outlet is provided at the top. A spiral channel for a second liquid to pass through is provided inside the tube wall of the heat exchange tube. The top of the spiral channel is a second liquid inlet and the bottom is a second liquid outlet.

[0006] The fin-type internal spiral tube heat exchanger for a boiler is characterized in that the spiral channel is arranged on the outer wall surface of the heat exchange tube, and the spiral channel is fixed to the outer wall surface of the heat exchange tube by welding.

[0007] The fin-type internal spiral tube heat exchanger for a boiler is characterized in that the fins are fixed to the heat exchange tubes by welding.

[0008] The fin-type internal spiral tube heat exchanger for a boiler is characterized in that the first liquid and the second liquid are both media to be heated in the boiler.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] 1) The technical solution of the present invention can make more use of the heat of high-temperature exhaust gas compared with the traditional heat exchanger, and make the discharge temperature of high-temperature exhaust gas lower, thereby achieving the purpose of energy saving and environmental protection;

[0011] 2) The fins provided in the present invention allow the cooling gas to move along the bending direction of the fins, so that the body separation angle α of the cooling gas's orbital motion becomes larger to 120-140°. The larger the body separation angle, the cooling gas can be better cooled to the back of the heat exchange tube, and the body separation turbulence generated after the back airflow separates from the body will be more concentrated, thereby increasing the heat exchange effect of the heat exchanger;

[0012] 3) The spiral channel provided in the present invention enables the two cooling liquids to cool and absorb heat in a convection mode, and the convection mode setting enables a better heat exchange effect between the two liquids and the high-temperature exhaust gas;

[0013] 4) The present invention has the characteristics of simple structure, low processing cost, energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the external structure of the present invention;

[0015] Figure 2 It is a schematic diagram of the off-body angle structure of the present invention;

[0016] Figure 3 Schematic diagram of the spiral channel structure in the heat exchange tube of the present invention;

[0017] Figure 4 It is a schematic diagram of the overall structure of the heat exchanger of the present invention.

[0018] In the figure: 1-heat exchange tube; 2-fin; 3-spiral channel; 4-first liquid inlet; 5-first liquid outlet; 6-second liquid inlet; 7-second liquid outlet. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings, but the scope of protection of the present invention is not limited to the described scope.

[0020] like Figure 1-4As shown, a finned internal spiral tube heat exchanger for a boiler comprises a heat exchange tube 1, fins 2 and a spiral channel 3. The heat exchange tube 1 comprises an outer wall surface and an inner wall surface. The heat exchange tube 1 is provided with fins 2 on the outside of the tube wall. The fins 2 are of a spiral structure and are fixed to the heat exchange tube 1 by winding and welding. When the cooling gas passes across the tube surface along the heat exchange tube 1 from the outside, the cooling gas will be violently disturbed due to the action of the fins 2, thereby greatly increasing the heat exchange effect. Moreover, since the fins 2 are of a spiral structure and are wound around the heat exchange tube 1, the cooling gas will advance along the bending direction of the fins 2, so that the detachment angle α of the circumferential motion of the cooling gas will be larger. When the fluid flows through the tube surface in a direction perpendicular to the axis of the tube, a flow detachment phenomenon will occur, wherein the angle between the fluid detachment point and the direction of the incoming fluid is called the detachment angle α.

[0021] When the fin 2 is not added, the detachment angle α is 0-80°. After the fin 2 is added, the Reynolds number increases, so that the detachment angle α increases to 120-140°. Once the detachment angle becomes larger, the cooling gas can be better cooled to the side of the heat exchange tube 1 facing away from the cooling gas, and the detachment turbulence generated after the airflow detaches from the back side will also be more concentrated, thereby increasing the heat exchange effect of the heat exchanger.

[0022] The present invention provides a fin-type internal spiral tube heat exchanger for a boiler, wherein a space for a first liquid to pass through is formed between the inner wall surface and the outer wall surface of the heat exchange tube 1, a first liquid inlet 4 is provided at the bottom of the space, and a first liquid outlet 5 is provided at the top thereof, and the first liquid inlet 4 and the first liquid outlet 5 are interconnected.

[0023] The present invention is a fin-type internal spiral tube heat exchanger for a boiler, wherein a spiral channel 3 for a second liquid to pass through is provided in the tube wall of a heat exchange tube 1, the top of the spiral channel 3 is a second liquid inlet 6, and the bottom is a second liquid outlet 7, and the spiral channel 3 is fixed to the outer wall of the heat exchange tube 1 by welding.

[0024] The present invention provides a fin-type internal spiral tube heat exchanger for a boiler, wherein the first liquid and the second liquid are both working fluids to be heated in the boiler.

[0025] Specifically, when the high-temperature exhaust gas passes through the inner wall of the heat exchange tube 1, the second liquid to be heated flows into the spiral channel 3 through the second liquid inlet 6, and the first liquid to be heated flows in from the first liquid inlet 4. Since the spiral channel 3 is welded to the heat exchange tube 1, the first liquid will also move forward along the flat spiral channel 3 after entering. The two cooling liquids are cooled and absorb heat in a convection mode. The convection mode setting makes the heat exchange effect between the two liquids and the high-temperature exhaust gas better. The inlet temperature of the first liquid is relatively low. Under the influence of the second liquid and the high-temperature exhaust gas in the tube, the temperature rises rapidly, making full use of the heat of the high-temperature exhaust gas, and causing the temperature of the exhaust gas to drop to a specified temperature; at the same time, outside the heat exchange tube 1, the cooling gas passes across the tube surface along the heat exchange tube 1 from the outside. The cooling gas will produce severe disturbances due to the fins 2. Before the phase change of the coolant between the tube walls occurs, the excess heat is taken away, so that the maximum temperature of the coolant is maintained below their saturation temperature, making full use of the heat in the high-temperature exhaust gas, and further reducing the temperature of the high-temperature exhaust gas.

[0026] The steam temperature from the low-pressure boiler to the high-pressure boiler is about 400-500°C. When the high-temperature exhaust gas passes through the heat exchange tube 1 of the heat exchanger, if there is only a single inner spiral channel 3 without fins 2, it is easy to reduce the temperature of the high-temperature exhaust gas to below 200°C, causing the first coolant and the second coolant to undergo phase change heat transfer, thereby causing the coolant at the outlet to become steam. After being collected, the temperature of the cooling steam is much lower than the steam temperature in the boiler, resulting in a pressure much lower than the pressure in the boiler. Therefore, the cooling steam cannot be directly put into the boiler for continued heating, but needs to be re-pressurized, resulting in additional energy consumption, which is not in line with the principles of environmental protection and energy saving.

Claims

1. A finned internal spiral tube heat exchanger for a boiler, characterized in that The invention comprises a heat exchange tube (1), a fin (2) and a spiral channel (3), wherein the heat exchange tube (1) comprises an outer wall surface and an inner wall surface, the fin (2) is arranged outside the tube wall of the heat exchange tube (1), the fin (2) is a spiral structure and is fixed to the heat exchange tube (1) by winding, a space for a first liquid to pass through is formed between the outer wall surface and the inner wall surface of the heat exchange tube (1), a first liquid inlet (4) is arranged at the bottom of the space and a first liquid outlet (5) is arranged at the top, a spiral channel (3) is arranged inside the tube wall of the heat exchange tube (1) for a second liquid to pass through, the top of the spiral channel (3) is a second liquid inlet (6) and the bottom is a second liquid outlet (7); The spiral channel (3) is arranged on the outer wall surface of the heat exchange tube (1), and the spiral channel (3) is fixed to the outer wall surface of the heat exchange tube (1) by welding; The first liquid and the second liquid are both media to be heated in the boiler.

2. The finned inner spiral tube heat exchanger for a boiler according to claim 1, characterized in that The fins (2) are fixed to the heat exchange tubes (1) by welding.

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