CN202733934U - Air preheater - Google Patents

Abstract

The utility model relates to an air preheater which comprises an air through cavity and a flue gas through cavity, wherein a partition plate which is used for preventing gas carry-over from happening between the two through cavities is arranged between the air through cavity and the flue gas through cavity, one or a plurality of gravity assisted heat pipes are mounted on the partition plate, an air inlet of the air through cavity is communicated with an exhaust port of a draught fan, and a thermometer which is used for measuring temperature of preheated air is arranged at the position of an air outlet of the air through cavity. A flue gas outlet of the flue gas through cavity is communicated with a tail flue gas exhaust port of a cast steel plate (CSP) factory roller hearth heating furnace, a flue gas outlet of the flue gas through cavity is communicated with a chimney through a branch flue gas regulation valve, and a main flue gas regulation valve is further arranged between the tail flue gas exhaust port of the CSP factory roller hearth heating furnace and the chimney. According to the air preheater, air is preheated by waste heat of high-temperature tail flue gas of the CSP factory roller hearth heating furnace, preheating temperature can be controlled and adjusted, structure is simple, operation and maintenance are convenient, and heat exchange efficiency is high.

Description

Air preheater

technical field

The utility model relates to an air preheater used in recovery and utilization of flue gas waste heat at the tail of a roller bottom heating furnace in a CSP (thin slab continuous casting and rolling) plant.

Background technique

Compact Strip Production Line, referred to as CSP (Compact Strip Production). It refers to the 50~80 mm thick thin continuous casting slab, which is cut after exiting the continuous casting machine, enters the roller hearth heating furnace, and is used for continuous rolling after exiting the furnace. This process not only makes full use of the heat energy of the billet, but also relies on the special functions and functions of the roller hearth heating furnace to make the continuous casting and continuous rolling production smooth. Therefore, it is being gradually promoted and applied all over the world.

The roller hearth heating furnace in the CSP production line has many functions, one of which is to continuously receive the high-temperature slab produced by the casting machine, and heat and soak it. At present, the temperature of the tail flue gas produced by the combustion of the roller hearth heating furnace is still as high as 400~500°C after treatment and utilization. This part of the tail flue gas is now directly discharged into the atmosphere, which not only causes a huge loss of heat, but also produces greenhouse effect pollution. environment. Therefore, how to recycle and utilize this part of the waste heat of flue gas to achieve the purpose of energy saving and emission reduction is an urgent problem to be solved by manufacturers and various research institutions. The publication number is CN 201322564Y, and the publication date is October 7, 2009. The patent titled air preheater discloses an air preheating device that uses waste heat gas from a bell furnace to preheat air. Seamless steel tubes are used as heat exchange tubes, and spiral fins are welded on the outside of the tube wall to increase the heat transfer area. Compared with ordinary heat exchangers, the heat exchange efficiency of this device has been improved, but there are still many disadvantages as follows: First, the preheating temperature of the air cannot be adjusted to meet certain specific needs. The 2nd, this device structure is comparatively complicated, and manufacturing process is comparatively difficult. The third is that the heat exchange efficiency of the device needs to be further improved. Fourth, the dust carried in the flue gas is easy to gather in the lower part of the flue gas outlet section of the device, which is inconvenient to clean up and very inconvenient to repair and maintain.

Utility model content

The technical problem to be solved by the utility model is to provide an air preheater, the air preheater utilizes the waste heat of the high-temperature flue gas at the tail of the roller bottom heating furnace of the CSP plant to preheat the air, and the preheating temperature is controllable and adjustable , simple structure, convenient operation and maintenance, high heat exchange efficiency.

The technical solution adopted in the utility model is: an air preheater, which includes an air cavity and a flue gas cavity, and a device for preventing the gas from blowing through the two cavities is arranged between the air cavity and the flue gas cavity. partition; one or more gravity heat pipes are installed on the partition, the heat release section of the gravity heat pipe is placed in the air cavity, and the heat absorption section of the gravity heat pipe is placed in the flue gas cavity; the air ventilation The air inlet of the chamber is connected with the outlet of the fan, and the air outlet of the air chamber is provided with a thermometer for measuring the air temperature after preheating; The exhaust port of the flue gas at the furnace tail is connected, and the flue gas outlet of the flue gas cavity is connected with the chimney through the flue gas regulating valve; there is also a Total flue gas regulating valve.

According to the above solution, the surface of the gravity heat pipe is high-frequency welded with several flat fins to increase the heat transfer area.

According to the above scheme, the gravity heat pipe is a circular closed gravity heat pipe, and a negative pressure of 1~2×10 ^-4 Pa is pumped into the closed pipe, and an appropriate amount of liquid heat transfer medium—inorganic salt is filled in the pipe; The pipe fittings of the gravity heat pipe are made of carbon steel.

According to the above scheme, a plurality of ash cleaning doors are arranged in the flue gas cavity.

According to the above solution, the flue gas inlet of the flue gas passage cavity is provided with a flue gas baffle to ensure that the flue gas passes through the heat exchange area reasonably and evenly.

In the utility model, the gravity heat pipe is divided into two sections, the lower section is a heat absorbing section, and the upper section is a heat releasing section. When the high-temperature flue gas scours the heat-absorbing section, the heat absorbed by the liquid heat transfer medium in the tube changes from liquid to gaseous, and the medium rises to the heat-releasing section, releasing heat outward, and the released heat is absorbed by the cold air blown by the fan, and the medium itself condenses As a liquid, it returns to the heat-absorbing section along the tube wall under the action of gravity. Because the tube is in a vacuum state and the thermal resistance is very small, the heat pipe has isothermal characteristics, that is, the temperature difference between the upper end and the lower end is small, has superconducting properties, and has high heat exchange efficiency.

The surface of the gravity heat pipe is high-frequency welded with fins, the surface structure of the fins is flat fins, and the material is made of heat-resistant steel sheets. The flat fins and gravity heat pipes are welded together by high-frequency welding. During the processing, the high-frequency electric induction generated by the high-frequency generator is used to generate high temperature at the contact point between the surface of the gravity heat pipe and the flat fin, and melt the two within a depth range of about 10um, and then pressurize to make the flat fin and the flat fin contact with each other. The gravity heat pipe is connected as a whole.

A flue gas baffle is installed at the flue gas inlet to ensure that the flue gas passes through the heat exchange area reasonably and evenly to achieve the best heat exchange effect. Multiple dust cleaning doors are set in the flue gas passage to facilitate equipment maintenance.

The total flue gas regulating valve and the sub-flue gas regulating valve can be adjusted independently or interlocked with each other.

The beneficial effects of the utility model are as follows: 1. Directly recycle the waste heat of the tail high-temperature flue gas discharged from the roller hearth heating furnace of the CSP factory, and use it to preheat the cold air. Preheating can also be used to heat the operating room in winter, which not only reduces heat loss, improves heat utilization efficiency, but also reduces production costs and environmental pollution. 2. The inside of the gravity heat pipe is in a vacuum state, and the thermal resistance is very small, so the heat pipe has isothermal characteristics, that is, the temperature difference between the upper end and the lower end is small, has superconducting characteristics, and has high heat exchange efficiency. 3. A flue gas baffle is installed at the flue gas inlet to ensure that the flue gas passes through the heat exchange area reasonably and evenly, so that the heat exchange effect can be achieved to the best. 4. There are multiple dust-cleaning doors to facilitate the maintenance of the equipment. 5. The total flue gas regulating valve and the sub-flue gas regulating valve are used together to achieve the purpose of adjusting the preheating temperature.

Description of drawings

Fig. 1 is a schematic structural view of an embodiment of the utility model.

Fig. 2 is a structural schematic diagram of the air cavity and the smoke cavity of the utility model.

In the figure: 1. thermometer, 2. air outlet, 3. air cavity, 4. flat fin, 5. air inlet, 6. total flue gas regulating valve, 7. heat release section, 8. heat absorption section, 9 , Flue gas control valve, 10, flue gas outlet, 11, gravity heat pipe, 12, heat transfer medium, 13, flue gas cavity, 14, dust cleaning door, 15, flue gas inlet, 16, partition, 17, Fan, 18. Flue gas at the end of roller hearth heating furnace in CSP factory, 19. Chimney.

Detailed ways

Further illustrate the embodiment of the present utility model below in conjunction with accompanying drawing.

Referring to FIG. 1 and FIG. 2 , an air preheater includes an air cavity 3 and a flue gas cavity 13 . The right side of described air passage chamber 3 is provided with air inlet 5, and this inlet is connected with the outlet of fan 17; The left side of air passage chamber 3 is provided with air outlet 2, is provided with for measuring preset Thermometer 1 for air temperature after heat. The left side of the flue gas passage 13 is provided with a flue gas inlet 15, which is connected with the outlet of the flue gas 18 at the tail of the roller hearth heating furnace in the CSP factory; the right side of the flue gas passage 13 is provided with a flue gas inlet 15. Outlet 10, the flue gas outlet 10 communicates with the chimney 19 through the flue gas distribution regulating valve 9, and the flue gas distribution regulating valve is used to control the amount of flue gas entering the heat exchanger. Between the air passage chamber 3 and the smoke passage chamber 13, a partition plate 16 is arranged to prevent blow-by of the two chambers. Several gravity heat pipes 11 are installed on the partition 16. The gravity heat pipe 11 is composed of two sections: the lower section is the heat-absorbing section 8, and the upper section is the heat-releasing section 7. The negative pressure of 1~2×10 ^-4 Pa is drawn in the tube, It is filled with an appropriate amount of liquid heat transfer medium 12; several flat fins 4 are welded on the surface of the gravity heat pipe with high frequency to increase the heat transfer area. A total flue gas regulating valve 6 is installed in the pipeline between the flue gas 18 at the end of the roller hearth heating furnace and the chimney 19 in the CSP plant. The total flue gas regulating valve 6 and the sub-flue gas regulating valve 9 jointly control the air temperature after preheating.

In this embodiment, a plurality of cleaning doors 14 are arranged in the flue gas passage 13 to facilitate maintenance of the equipment. The flue gas inlet 15 of the flue gas passage cavity 13 is provided with a flue gas baffle to ensure that the flue gas passes through the heat exchange area reasonably and evenly. The gravity heat pipe 11 is a circular closed gravity heat pipe, and the pipe fittings are made of carbon steel.

During operation, the flue gas at the end of the roller hearth heating furnace of the CSP plant passes through the total flue gas regulating valve 6 and enters the chimney 19, and is directly discharged into the air. Part of the high-temperature flue gas enters the flue gas cavity 13 through the flue gas inlet 15, flows through the gravity heat pipe 8, and performs heat exchange. , directly into the air. The gravity heat pipe 8 is scoured by the high-temperature flue gas, the heat absorption section 8 starts to absorb heat, and the liquid heat transfer medium 12 in the tube absorbs heat and becomes gaseous, and rises to the heat release section 7 . At this time, the cold air blown to the air cavity 3 by the fan 17 absorbs the heat released by the heat release section 7, becomes hot air, and is discharged through the air outlet 2, and the discharged hot air can be detected by the thermometer 1. After the liquid heat transfer medium 12 in the exothermic section 7 releases heat, it condenses from a gaseous state to a liquid state, and returns to the heat absorption section 8 along the inside of the tube wall of the gravity heat pipe 11 under the action of gravity. The liquid heat transfer medium 12 is in the whole working process form a self-circulation.

In the above process, the temperature of the heated air can be adjusted and controlled by adjusting the opening of the total flue gas regulating valve 6 installed at the high-temperature flue gas outlet and the sub-smog gas regulating valve 9 at the low-temperature flue gas outlet: when preheating When the temperature of the hot air is too high, the opening of the main flue gas regulating valve 6 and the opening of the sub regulating valve 9 can be adjusted to make most of the high-temperature flue gas directly discharged from the high-temperature flue gas outlet to reduce the amount of air entering The high-temperature flue gas that participates in heat exchange in the preheater and reduces the residence time of the high-temperature flue gas in the air preheater; when the temperature of the hot air after preheating is low, the opening of the total flue gas regulating valve 6 can be adjusted small Adjust the degree and adjust the opening degree of the regulating valve 9, so that most of the high-temperature flue gas enters the air preheater to participate in heat exchange, and prolongs the residence time of the high-temperature flue gas in the air preheater.

In addition, in order to facilitate inspection and maintenance, several dust-cleaning doors 14 are arranged in the flue gas cavity. After the dust carried in the flue gas gathers at the bottom of the flue gas cavity, it can be cleaned through the dust-cleaning doors 14 .

The above are only preferred embodiments of the present utility model, and are not intended to limit the present utility model in any form. Those skilled in the art make some simple modifications, equivalent changes or modifications using the technical content disclosed above, and all fall under Within the protection scope of the present utility model.

Claims (5)

1. A kind of air preheater, it is characterized in that: comprise air through chamber and flue gas through chamber, be provided with between air through chamber and flue gas through chamber and prevent the dividing plate of two through chambers from gas-by-passing; Said One or more gravity heat pipes are installed on the clapboard, the heat release section of the gravity heat pipe is placed in the air cavity, and the heat absorption section of the gravity heat pipe is placed in the flue gas cavity; the air inlet of the air cavity is connected to the air cavity The discharge port of the fan is connected, and the air outlet of the air cavity is provided with a thermometer for measuring the air temperature after preheating; The exhaust port is connected, and the flue gas outlet of the flue gas cavity is connected with the chimney through a separate flue gas regulating valve; there is also a total flue gas regulating valve between the flue gas exhaust port at the end of the roller hearth heating furnace of the CSP plant and the chimney . 2. The air preheater according to claim 1, characterized in that: the surface of the gravity heat pipe is high-frequency welded with several flat fins to increase the heat transfer area. 3. The air preheater according to claim 1 or 2, characterized in that: the gravity heat pipe is a circular closed gravity heat pipe, and a negative pressure of 1~2×10 ^-4 Pa is drawn in the closed pipe, and The tube is filled with a liquid heat exchange medium; the material of the gravity heat pipe is carbon steel. 4. The air preheater according to claim 1, characterized in that: the flue gas passage is provided with a plurality of dust removal doors. 5. The air preheater according to claim 1 or 4, characterized in that: the flue gas inlet of the flue gas cavity is provided with a flue gas baffle to ensure that the flue gas passes through the heat exchange area reasonably and evenly.

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