A heater with antifreeze function

Abstract

The present invention discloses an air heater with an antifreeze function, comprising a frame, and an inlet header, an outlet header and a plurality of single-group heat exchangers arranged in the frame, wherein each single-group heat exchanger comprises an upper header, a lower header and a plurality of heat exchange tubes, each heat exchange tube is vertically distributed, the lower end of each heat exchange tube is connected to the lower header, the upper end of each heat exchange tube is connected to the upper header, the upper headers and the lower headers in the front and rear single-group heat exchangers are respectively connected through connecting pipes, and the air heater has excellent antifreeze capability.

Description

Technical Field

[0001] The invention belongs to the technical field of power station boiler flue gas waste heat recovery and relates to an air heater with an antifreeze function. Background Art

[0002] With the implementation of comprehensive ultra-low emissions and the advancement of energy-saving transformation of coal-fired power plants, low-nitrogen combustion systems, flue gas denitrification systems, wet desulfurization systems, wet electrostatic precipitator systems, etc. have been widely used. While meeting environmental protection standards, the above systems have also encountered some problems, such as reduced boiler efficiency and electrostatic precipitator efficiency due to increased exhaust gas temperature, increased air preheater blockage and increased resistance due to increased denitrification ammonia escape rate, increased water consumption of wet desulfurization systems, and increased plant electricity consumption.

[0003] Since the low-temperature economizer system can recover waste heat and save energy, it is also a beneficial supplement to the ultra-low emission transformation of coal-fired power plants. It can cooperate with the transformation of electrostatic precipitators to improve dust removal efficiency and reduce environmental protection transformation costs. It has good economic benefits. Therefore, under the background of ultra-low emission and energy-saving transformation, the low-temperature economizer system has been rapidly developed and further optimized. The low-temperature economizer and heater combined system is based on the low-temperature economizer system. The heater is used to increase the air temperature at the inlet of the air preheater, alleviate the increase in resistance and blockage of the air preheater and low-temperature economizer caused by the increase in ammonia escape rate, and at the same time improve the boiler efficiency and the energy-saving benefits of the low-temperature economizer.

[0004] When the hot water at the outlet of the low-temperature economizer is used as the heat source of the heater, the inlet water temperature of the heater is generally between 100-130℃, and the outlet water temperature is generally controlled at around 70℃; when the condensate of the unit's low-pressure heating system is used as the heat source of the heater, the inlet water temperature of the heater is generally between 80-100℃, and the outlet water temperature is generally controlled at 40℃. The outlet water temperature of the heater in the combined system of low-temperature economizer and heater is relatively low. When the ambient temperature is low and the unit is running at low load, the outlet water temperature of the heater is low and the flow rate is small. In addition, the flow rate between the heat exchange tubes is uneven, which makes it easy for the heat exchange tubes to freeze and crack, and the heater system cannot be put into operation, threatening the safety of the system. The antifreeze problem of the heater seriously affects the application of low-temperature economizers and heater systems in northern regions. Summary of the invention

[0005] The purpose of the present invention is to overcome the disadvantages of the prior art and provide an air heater with an antifreeze function, which has excellent antifreeze capability.

[0006] To achieve the above-mentioned purpose, the air heater with antifreeze function described in the present invention comprises a frame, and a water inlet header, a water outlet header and a plurality of single-group heat exchangers arranged in the frame, wherein each single-group heat exchanger comprises an upper header, a lower header and a plurality of heat exchange tubes, each heat exchange tube is vertically distributed, the lower end of each heat exchange tube is connected to the lower header, the upper end of each heat exchange tube is connected to the upper header, and the upper header in the previous single-group heat exchanger is connected to the upper header in the next single-group heat exchanger through a connecting pipe;

[0007] The lower header in the first single-group heat exchanger serves as the water inlet header of the air heater, and the lower header in the last single-group heat exchanger serves as the water outlet header of the air heater.

[0008] An air inlet and an air outlet are arranged on the side of the frame.

[0009] The heat exchange tubes in the same single group of heat exchangers are arranged in parallel.

[0010] An exhaust pipe and a sewage pipe are arranged on the connecting pipe between the upper header and the lower header.

[0011] Manual stop valves are installed on the exhaust pipe and sewage pipe.

[0012] Adjacent heat exchange tubes are connected via anti-vibration components, and adjacent anti-vibration components are connected via detuning plates and reinforcing tubes.

[0013] The heat exchange tube is an annular fin heat exchange tube.

[0014] The upper header is provided with lifting lugs.

[0015] The present invention has the following beneficial effects:

[0016] During the specific operation of the air heater with antifreeze function described in the present invention, the heat exchange tubes are arranged vertically, the air heater is arranged in staggered and countercurrent, the working fluid flows through the air heater in a bottom-in-top-out manner, and flows vertically in the heat exchange tubes, so as to avoid freezing and cracking caused by the inability to drain the accumulated water in the heat exchange tubes when the conventional heat exchange tubes are arranged horizontally. The heat exchange tubes are directly connected to the upper header and the lower header, and no elbows are provided, so as to reduce the number of weak positions of the heat exchange tubes and prevent the elbows of the heat exchange tubes from freezing and cracking. The upper headers and the lower headers in adjacent single-group heat exchangers are connected by connecting pipes to evenly distribute the working fluid flow rate, so that the working fluid flow deviation in each heat exchange tube fluctuates within a smaller range, thereby increasing the working fluid flow rate in the heat exchange tubes. The structure is simple, and the workload of operation, inspection and maintenance is small. It can alleviate the current situation of frequent freezing and cracking of heat exchange tubes in hot water air heaters in northern regions, and greatly improve the antifreeze ability of the air heater.

[0017] Furthermore, the connecting pipe is provided with an exhaust pipe and a sewage pipe, and the exhaust point and the sewage point are respectively located at the highest position and the lowest position of the heater, so that the working fluid in the upper header, the lower header and the heat exchange tube can be completely discharged when the heater is out of operation. The heater is composed of several single sets of heat exchangers connected in series or in parallel, and the heat exchange tubes are connected by anti-vibration components, which effectively avoids the vibration of the heater caused by resonance when air flows through the heat exchange tubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a front view of a single group heat exchanger 2 in the present invention;

[0019] Figure 2 It is a side view of a single group heat exchanger 2 in the present invention;

[0020] Figure 3 It is a side view of a single group heat exchanger 2 in the present invention;

[0021] Figure 4 It is a top view of a single group of heat exchangers 2 in the present invention;

[0022] Figure 5 is a layout diagram of the heat exchange tube 11 in the present invention;

[0023] Figure 6 It is the connection diagram of the anti-vibration assembly in the present invention;

[0024] Figure 7 This is a connection diagram of the header in the present invention.

[0025] Among them, 1 is an anti-vibration assembly, 2 is a single-group heat exchanger, 3 is an upper header, 4 is a lower header, 5 is a detuning plate, 6 is a reinforcement pipe, 7 is a connecting pipe, 8 is a water inlet header, 9 is a water outlet header, 10 is a frame, 11 is a heat exchange tube, 12 is a lifting ear, 13 is an exhaust pipeline, and 14 is a sewage pipeline. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0027] refer to Figures 1 to 7The air heater with antifreeze function described in the present invention comprises a frame 10 and a water inlet header 8, a water outlet header 9 and a plurality of single-group heat exchangers 2 arranged in the frame 10, wherein each single-group heat exchanger 2 comprises an upper header 3, a lower header 4 and a plurality of heat exchange tubes 11, each heat exchange tube 11 is vertically distributed, the lower end of each heat exchange tube 11 is connected to the lower header 4, the upper end of each heat exchange tube 11 is connected to the upper header 3, the upper header 3 in the previous single-group heat exchanger 2 is connected to the upper header 4 in the next single-group heat exchanger 2 through a connecting pipe 7; the lower header 4 in the first single-group heat exchanger 2 serves as the water inlet header 8 of the air heater, and the lower header 4 in the last single-group heat exchanger 2 serves as the water outlet header 9 of the air heater, and the side of the frame 10 is provided with an air inlet and an air outlet.

[0028] The heat exchange tubes 11 in the same single group of heat exchangers 2 are arranged in parallel; an exhaust pipe 13 and a sewage pipe 14 are provided on the connecting pipe 7 between the upper header 3 and the lower header 4, and manual stop valves are provided on the exhaust pipe 13 and the sewage pipe 14.

[0029] Adjacent heat exchange tubes 11 are connected via anti-vibration components 1 , and adjacent anti-vibration components 1 are connected via detuning plates 5 and reinforcing tubes 6 . The heat exchange tubes 11 are annular fin heat exchange tubes, and a lifting lug 12 is provided on the upper header 3 .

[0030] The inlet and outlet dimensions of the upper header 3 and the lower header 4 are φA=76mm, the dimensions of the upper header 3 and the lower header 4 are φB=219mm, and the number of heat exchange tubes 11 in a single group of heat exchangers 2 is three, wherein the angle α between the heat exchange tubes 11 on both sides and the center lines of the upper header 3 and the lower header 4 is 40°, the height H between the starting position of the annular fins of the heat exchange tubes 11 on both sides and the center line of the header is 185mm, and the height h between the starting position of the bends of the heat exchange tubes 11 on both sides and the starting position of the annular fins of the heat exchange tubes 11 is 56mm.

[0031] The connecting pipe 7 is made of φ76m steel pipe; the anti-vibration component 1 is in the form of a plywood, the material of the plywood is Q235B, the thickness δ=6mm, the width B=40mm, and the two sets of plywood are connected by a steel plate with a thickness of δ=6mm.

[0032] The detuning plate 5 is made of Q235B steel plates, the reinforcing tube 6 is a φ32 round tube, and the detuning plate 5 and the anti-vibration component 1 are spot welded firmly.

[0033] The specific working process of the present invention is:

[0034] The air enters the heater, and the working medium in the heat exchange tube 11 heats the air. The heater is arranged in staggered and countercurrent, and the air flows outside the heat exchange tube 11. The working medium enters the heater from the water inlet header 8, and then leaves the heater from the water outlet header 9. The working medium flows vertically in the heat exchange tube 11 to avoid freezing and cracking caused by the inability to drain the water in the tube when the heat exchange tube 11 is arranged horizontally. When the working medium flows through the upper header 3 and the lower header 4, since the heat exchange tube 11 is directly connected to the upper header 3 and the lower header 4, no elbow is set, and the upper header 3 and the lower header 4 are connected by several connecting pipes 7 to ensure the uniform distribution of the working medium flow rate. The heater avoids freezing and cracking of the heat exchange tube 11 due to weak elbows and deviation of the working medium flow rate during operation. The heat exchange tubes 11 are connected by an anti-vibration component 1 to effectively avoid the vibration of the heater caused by resonance when the air flows through the heat exchange tube 11. When the heater stops running, the working medium in the heat exchange tube 11, the upper header 3 and the lower header 4 is exhausted through the exhaust pipe 13 and the sewage pipe 14, and there is no water accumulation structure in the heater.

Claims

1. A heater with antifreeze function, characterized in that: The invention comprises a frame (10), an inlet header (8), an outlet header (9) and a plurality of single-group heat exchangers (2) arranged in the frame (10), wherein each single-group heat exchanger (2) comprises an upper header (3), a lower header (4) and a plurality of heat exchange tubes (11), each heat exchange tube (11) is vertically distributed, the lower end of each heat exchange tube (11) is connected to the lower header (4), the upper end of each heat exchange tube (11) is connected to the upper header (3), and the upper header (3) in the previous single-group heat exchanger (2) is connected to the upper header (3) in the next single-group heat exchanger (2) via a connecting pipe (7); The lower header (4) in the first single-group heat exchanger (2) serves as a water inlet header (8) of the air heater, and the lower header (4) in the last single-group heat exchanger (2) serves as a water outlet header (9) of the air heater; An air inlet and an air outlet are arranged on the side of the frame (10); The heat exchange tubes (11) in the same single group of heat exchangers (2) are arranged in parallel; Adjacent heat exchange tubes (11) are connected via anti-vibration components (1), and adjacent anti-vibration components (1) are connected via detuning plates (5) and reinforcing tubes (6); The number of heat exchange tubes (11) in a single group of heat exchangers (2) is three, wherein the angle α between the heat exchange tubes (11) on both sides and the center lines of the upper header (3) and the lower header (4) is 40°.

2. The air heater with antifreeze function according to claim 1, characterized in that: An exhaust pipe (13) and a sewage discharge pipe (14) are arranged on the communication pipe (7).

3. The air heater with antifreeze function according to claim 2, characterized in that: Manual stop valves are provided on the exhaust pipe (13) and the sewage pipe (14).

4. The air heater with antifreeze function according to claim 1, characterized in that: The heat exchange tube (11) is an annular fin heat exchange tube.

5. The air heater with antifreeze function according to claim 1, characterized in that: A lifting lug (12) is provided on the upper header (3).

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