Flue gas waste heat deep recovery and white mist elimination system and method

Abstract

A system and method for deep recovery of flue gas waste heat and elimination of white mist. The present invention first reduces the flue gas temperature from nearly 90°C to below 30°C through a heat exchange device, and then raises the flue gas temperature to above 50°C through a small amount of heat medium provided by a heating mother pipe to eliminate the white mist in the flue gas. On this basis, the present invention can also add a gas-liquid separation device in the above process to separate and collect the liquefied fine water droplets in the flue gas, reduce the water content in the flue gas, and facilitate the subsequent flue gas treatment equipment to directly absorb and harmlessly treat the flue gas.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, and in particular to a system and method for deep recovery of flue gas waste heat and elimination of white mist. Background Art

[0002] Existing boiler equipment will generate a large amount of flue gas when supplying heat energy and outputting media in urban thermal pipe networks. The flue gas contains water vapor and is mixed with white mist, which affects the environment and is not conducive to the recovery and harmless treatment of the flue gas.

[0003] Existing white mist elimination methods usually require additional heat energy consumption, which is used to increase the flue gas temperature and heat and vaporize the condensed water droplets in the flue gas to eliminate the white mist. However, this method consumes a lot of energy and does not reduce the water vapor content in the flue gas, which is not conducive to the subsequent flue gas treatment process. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a system and method for deep recovery of flue gas waste heat and elimination of white mist. The present invention adopts a two-stage partition wall heat exchanger. The present invention first uses a heat pump to reduce the flue gas temperature from 90°C to 30°C, absorbs latent heat to heat boiler return water, and then uses a small part of boiler supply water to reheat the flue gas to 50°C for discharge, completely eliminating white mist. The present invention specifically adopts the following technical solutions.

[0005] First, in order to achieve the above-mentioned purpose, a flue gas waste heat deep recovery and white mist elimination system is proposed, which includes: a heat exchange device, whose input end receives flue gas, and whose cold supply end receives cold medium, transfers the cold of the cold medium to the flue gas, reduces the flue gas temperature, and discharges the flue gas cooled to below 30°C from the output end; a partition-type heat exchanger, whose input end is connected to the output end of the heat exchange device, and whose heat supply end is connected to the heating main pipe of the boiler, transfers the heat of the medium in the heating main pipe to the flue gas cooled to below 30°C, raises the temperature of the flue gas to above 50°C, and outputs the flue gas heated to above 50°C from the output end; a smoke exhaust device, whose input end is connected to the output end of the partition-type heat exchanger, and whose output end discharges the flue gas.

[0006] Optionally, in the above-mentioned flue gas waste heat deep recovery and white mist elimination system, the heat exchange device includes a heat pump; the cold supply end of the heat pump is connected to the boiler to form a boiler return water heating circuit, and the boiler return water heating circuit has a medium. The medium transfers the waste heat generated by the cooling of the flue gas from the heat output end of the heat pump to the boiler, heats the boiler return water, and supplies the medium that has been cooled after heating the boiler return water to the cold supply end of the heat pump to reduce the flue gas temperature.

[0007] Optionally, in the above-mentioned flue gas waste heat deep recovery and white mist elimination system, the partition wall heat exchanger is a two-stage wall heat exchanger, the output end of the two-stage wall heat exchanger is also connected to a gas-liquid separation device, and the output end of the gas-liquid separation device is connected to the smoke exhaust device.

[0008] Optionally, the above-mentioned flue gas waste heat deep recovery and white mist elimination system, wherein the two-stage partition wall heat exchanger has two parallel sections, and each section includes the following structures: an outer wall, a sealed cavity is formed inside it; blocks are evenly arranged in the sealed cavity formed by the outer wall along a first direction, and the blocks are parallel to each other, one side of the block is fixedly connected to the inner wall of the sealed cavity, and a gap is provided between the other side of the block and the inner wall of the sealed cavity; a spray device is provided in the gap between the block and the inner wall of the sealed cavity, the spray device is connected to the heat supply end, and the spray device sprays a medium above 50°C to both sides of the block; a heat transfer pipe is laid between the blocks in the sealed cavity along the second direction, and the heat transfer pipe passes through the blocks to connect the input and output ends of the partition wall heat exchanger.

[0009] Optionally, in the above-mentioned flue gas waste heat deep recovery and white mist elimination system, a regulating valve is also connected between the heat supply end of the partition wall heat exchanger and the heating main pipe of the boiler, and the regulating valve adjusts the flow rate and / or flow of the medium input to the partition wall heat exchanger.

[0010] Optionally, in the above-mentioned flue gas waste heat deep recovery and white mist elimination system, the outer wall of the partition-type heat exchanger is also provided with a drain valve, and the drain valve is connected to the sealed cavity to discharge the medium sprayed by the spraying device in the sealed cavity.

[0011] Optionally, in the above-mentioned flue gas waste heat deep recovery and white mist elimination system, the first direction is perpendicular to the second direction; the block is arranged to be parallel to the spraying direction of the spray device, and a plurality of mounting holes for the heat transfer pipe to pass through are arranged in the block; the heat transfer pipe is provided with multiple bends, and the heat transfer pipe reciprocates through each block through each mounting hole according to the arrangement order of the block.

[0012] At the same time, in order to achieve the above-mentioned purpose, the present invention also provides a method for deep recovery of flue gas waste heat and elimination of white mist, the steps of which include: a first step, inputting the flue gas into a heat exchanger, the heat exchanger receives a cold medium, transfers the coldness of the cold medium to the flue gas, reduces the flue gas temperature, and discharges the flue gas cooled to below 30°C; a second step, inputting the flue gas cooled to below 30°C into a partition-type heat exchanger, the partition-type heat exchanger inputs the medium in the heating main pipe of the boiler, transfers the heat of the medium in the heating main pipe to the flue gas cooled to below 30°C, raises the temperature of the flue gas to above 50°C, and outputs the flue gas heated to above 50°C; a third step, transporting the flue gas heated to above 50°C to a smoke exhaust device to discharge the flue gas.

[0013] Optionally, the above-mentioned method for deep recovery of flue gas waste heat and elimination of white mist, wherein the second step to the third step also includes: first conveying the flue gas heated to above 50°C to a gas-liquid separation device to separate the liquid in the flue gas, and then conveying the remaining flue gas to a smoke exhaust device to discharge the remaining flue gas.

[0014] Beneficial Effects

[0015] The present invention first reduces the flue gas temperature from nearly 90°C to below 30°C through a heat exchange device, and then raises the flue gas temperature to above 50°C through a small amount of heat medium provided by the heating mother pipe, thereby eliminating the white mist in the flue gas. On this basis, the present invention can also add a gas-liquid separation device in the above process to separate and collect the liquefied fine water droplets in the flue gas, reduce the water content in the flue gas, and facilitate the subsequent flue gas treatment equipment to directly absorb and harmlessly treat the flue gas.

[0016] Among them, since the present invention first reduces the flue gas temperature from 90°C to 30°C through the heat exchange device, the present invention can further improve the heating efficiency of boiler return water by utilizing the latent heat of water vapor changing from gas phase to liquid phase. Therefore, it can effectively increase the boiler return water temperature, reduce boiler heat consumption, and save energy.

[0017] Specifically, in the present invention, the temperature of the flue gas can be increased by a two-stage partition wall heat exchanger, and then the remaining water vapor in the flue gas is condensed and recovered by an existing gas-liquid separator. The two-stage partition wall heat exchanger sprays the heat transfer tube that transmits the flue gas with the medium in the heating mother tube, which can increase the contact area between the medium and the flue gas and efficiently perform heat exchange. The spraying process includes the process of evaporation of the medium on the surface of the heat transfer tube, so the efficiency of heat exchange can be further improved. The two sections are connected in parallel and are independent of each other. Unlike the series structure, the parallel method will not affect the efficiency of heat exchange in the two stages due to the residual heat of the medium.

[0018] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 It is a schematic diagram of the overall structure of the flue gas waste heat deep recovery and white mist elimination system of the present invention;

[0021] Figure 2 yes Figure 1 The schematic diagram of the structure of the intermediate wall heat exchanger of the system shown;

[0022] In the figure, 1 represents a heat exchange device; 2 represents a partition-type heat exchanger; 21 represents a heat transfer tube; 22 represents an outer wall; 23 represents a block; 24 represents a sprinkler head; 25 represents a gas-liquid separation device; 3 represents a smoke exhaust device; 4 represents a regulating valve; and 5 represents a boiler. DETAILED DESCRIPTION

[0023] In order to make the purpose and technical solution of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0025] The meaning of "and / or" in the present invention means that both the cases where each exists alone or both exist at the same time are included.

[0026] The meaning of "inside" and "outside" in the present invention refers to the direction from the outer wall surface to the inside of the heat transfer tube relative to the partition wall heat exchanger itself, and the opposite direction is outside; it is not a specific limitation on the device structure of the present invention.

[0027] The term “connection” as used in the present invention may mean a direct connection between components or an indirect connection between components via other components.

[0028] Figure 1A flue gas waste heat deep recovery and white mist elimination system according to the present invention comprises:

[0029] The heat exchange device 1 receives flue gas at its input end and receives cold medium at its cold supply end, transfers cold medium to the flue gas to reduce the flue gas temperature, and discharges the flue gas cooled to below 30° C. from the output end;

[0030] The partition wall heat exchanger 2 has an input end connected to the output end of the heat exchange device 1, and a heat supply end connected to the heating main pipe of the boiler, and transfers the heat of the medium in the heating main pipe to the flue gas cooled to below 30°C, raises the temperature of the flue gas to above 50°C, and outputs the flue gas heated to above 50°C from the output end;

[0031] The smoke exhaust device 3 has an input end connected to the output end of the partitioning heat exchanger 2, and an output end thereof exhausts smoke.

[0032] Therefore, the present invention first uses a heat pump as a heat exchange device 1. The cold supply end of the heat pump is connected to the boiler to form a boiler return water heating circuit. The boiler return water heating circuit has a medium. The medium transfers the waste heat generated by the flue gas cooling from the heat output end of the heat pump to the boiler, heats the boiler return water, and supplies the medium cooled after heating the boiler return water to the cold supply end of the heat pump, reducing the flue gas temperature from 90°C to 30°C, absorbing latent heat for heating the boiler return water. Then, by setting a partition heat exchanger, a small part of the boiler supply water is used to reheat the flue gas to 50°C for discharge, completely eliminating the white fog.

[0033] In order to achieve a good heat exchange effect, the partition wall heat exchanger can be specifically used Figure 2 The two-stage wall heat exchanger shown in FIG. The two-stage wall heat exchanger has two sections connected in parallel, each section includes:

[0034] The outer wall 22 has a sealed cavity formed therein;

[0035] The stoppers 23 are evenly arranged in the sealing cavity formed by the outer wall 22 along the first direction, the stoppers 23 are parallel to each other, one side of the stoppers 23 is fixedly connected to the inner wall of the sealing cavity, and a gap is provided between the other side of the stoppers 23 and the inner wall of the sealing cavity;

[0036] A spray device 24, which is disposed in the gap between the stopper 23 and the inner wall of the sealing cavity, the spray device 24 is connected to the heat supply end, and the spray device 24 sprays a medium with a temperature of more than 50°C to both sides of the stopper 23;

[0037] The heat transfer pipe 21 is laid between the blocks 23 in the sealed cavity along the second direction. The heat transfer pipe 21 passes through the blocks 23 to connect the input end and the output end of the partitioning heat exchanger.

[0038] The output end of the two-stage wall heat exchanger is also connected to a gas-liquid separation device 25 , which can be a gas-liquid separator in a baffle separation mode. The output end of the gas-liquid separation device 25 is connected to the smoke exhaust device 3 .

[0039] In such a partition-type heat exchanger, the blocks can be arranged to be staggered on the upper wall and the lower wall of the sealed cavity. The spray device can be arranged on the upper wall of the sealed cavity, and the spray device is directly opposite to the block connected to the lower wall to spray the medium to the block. The mounting hole inside the block is passed through by the heat transfer tube, and the heat transfer tube can be bent and arranged into several layers, and each layer is staggered to facilitate receiving the sprayed medium. In this way, the heat medium is evenly divided by the blocks and sprayed on each section of the bend of the heat transfer tube. When the heat medium drips from the surface of the heat transfer tube to the bottom of the sealed cavity, its heat is taken away by the heat transfer tube, condensed and cooled at the bottom, and then the medium sprayed by the spray device 24 in the sealed cavity can be discharged through the drain valve arranged at the lower part of the outer wall 22 of the partition-type heat exchanger 2 and connected to the drain valve in the sealed cavity.

[0040] In order to control the amount of spraying medium and adjust the heat provided by the medium to the flue gas in the heat transfer tube, a regulating valve 4 is also connected between the heat supply end of the partition wall heat exchanger 2 and the heating main pipe of the boiler. The regulating valve 4 adjusts the flow rate and / or flow of the medium input to the partition wall heat exchanger 2.

[0041] The baffles of the partition-type heat exchanger can be evenly arranged along the horizontal direction of the heat transfer tube. The baffles are arranged perpendicular to the heat transfer tube, and the heat transfer tube is divided into different small sections. The medium sprayed by the spray head between the sections can flow out through the gap between the baffle and the side wall of the sealing cavity to avoid siltation.

[0042] The block 23 is arranged parallel to the spraying direction of the spray device 24, and a plurality of mounting holes for the heat transfer tube 21 to pass through are arranged in the block 23; the heat transfer tube 21 is provided with a plurality of bends, and the heat transfer tube 21 reciprocates through each of the mounting holes and passes through each of the blocks according to the arrangement sequence of the block 23.

[0043] Therefore, the present invention can realize waste heat recovery of flue gas, eliminate white mist, reduce the moisture content in flue gas, and avoid the subsequent treatment of flue gas being diluted and affecting the treatment effect due to excessive moisture contained in the flue gas by the above system according to the following steps:

[0044] In the first step, the flue gas is input into the heat exchanger, the heat exchanger receives the cold medium, transfers the coldness of the cold medium to the flue gas, reduces the flue gas temperature, and discharges the flue gas cooled to below 30°C;

[0045] In the second step, the flue gas cooled to below 30°C is input into the partitioning heat exchanger 2, and the partitioning heat exchanger 2 inputs the medium in the heating main pipe of the boiler, transfers the heat of the medium in the heating main pipe to the flue gas cooled to below 30°C, raises the temperature of the flue gas to above 50°C, and outputs the flue gas heated to above 50°C;

[0046] The third step is to transport the flue gas heated to above 50° C. to the smoke exhaust device 3 to exhaust the flue gas.

[0047] Among them, the second step and the third step also include: firstly conveying the flue gas heated to above 50°C to the gas-liquid separation device 25 to separate the liquid in the flue gas, and then conveying the remaining flue gas to the smoke exhaust device 3 to discharge the remaining flue gas. Since the gas-liquid separation device separates the condensed water droplets from the flue gas, the water content of the flue gas can be further reduced, thereby ensuring the efficiency of subsequent harmless treatment and recovery of the flue gas.

[0048] The above is only an embodiment of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A flue gas waste heat deep recovery and white mist elimination system, characterized in that: include: A heat exchange device (1) receives flue gas at its input end and receives cold medium at its cold supply end, transfers coldness of the cold medium to the flue gas to reduce the temperature of the flue gas, and discharges the flue gas cooled to below 30° C. from its output end; The partition wall heat exchanger (2) has an input end connected to the output end of the heat exchange device (1), and a heat supply end connected to the heating main pipe of the boiler, and transfers the heat of the medium in the heating main pipe to the flue gas cooled to below 30° C., raises the temperature of the flue gas to above 50° C., and outputs the flue gas heated to above 50° C. from the output end; A smoke exhaust device (3), the input end of which is connected to the output end of the partitioning heat exchanger (2), and the output end of which exhausts smoke; The heat exchange device (1) comprises a heat pump; The cold supply end of the heat pump is connected to the boiler to form a boiler return water heating loop. The boiler return water heating loop has a medium. The medium transfers the waste heat generated by cooling the flue gas from the heat output end of the heat pump to the boiler to heat the boiler return water. The medium cooled after heating the boiler return water is supplied to the cold supply end of the heat pump to reduce the flue gas temperature. The partition wall heat exchanger (2) is a two-stage wall heat exchanger, the output end of the two-stage wall heat exchanger is also connected to a gas-liquid separation device (25), and the output end of the gas-liquid separation device (25) is connected to the smoke exhaust device (3); The two-stage wall heat exchanger has two stages connected in parallel, each stage comprising the following structures: an outer wall (22) having a sealed cavity formed therein; Blocks (23) are evenly arranged along a first direction in the sealed cavity formed by the outer wall (22), the block blocks (23) are parallel to each other, one side of the block blocks (23) is fixedly connected to the inner wall of the sealed cavity, and a gap is provided between the other side of the block blocks (23) and the inner wall of the sealed cavity; a spray device (24), which is arranged in a gap between the stopper (23) and the inner wall of the sealed cavity, the spray device (24) being connected to the heat supply end, and the spray device (24) spraying a medium with a temperature of more than 50° C. onto both sides of the stopper (23); A heat transfer pipe (21) is laid between the blocks (23) in the sealed cavity along the second direction, and the heat transfer pipe (21) passes through the blocks (23) to connect the input end and the output end of the partitioning heat exchanger (2); The first direction is perpendicular to the second direction; The block (23) is arranged parallel to the spraying direction of the spraying device (24), and a plurality of mounting holes for the heat transfer pipe (21) to pass through are arranged in the block (23); The heat transfer tube (21) is provided with a plurality of bends, and the heat transfer tube (21) reciprocates through the mounting holes and passes through the blocks according to the arrangement sequence of the blocks (23).

2. The system for deep recovery of flue gas waste heat and elimination of white mist according to claim 1, characterized in that: A regulating valve (4) is also connected between the heat supply end of the partitioning heat exchanger (2) and the heat supply main pipe of the boiler, and the regulating valve (4) regulates the flow rate and / or flow rate of the medium input into the partitioning heat exchanger (2).

3. The flue gas waste heat deep recovery and white mist elimination system according to claim 1 or 2, characterized in that: The outer wall (22) of the partition-type heat exchanger (2) is also provided with a drain valve, which is connected to the sealed cavity and discharges the medium sprayed by the spray device (24) in the sealed cavity.

4. A method for deep recovery of flue gas waste heat and elimination of white mist applied to the system described in any one of claims 1 to 3, characterized in that the steps include: In the first step, the flue gas is input into the heat exchanger, the heat exchanger receives the cold medium, transfers the coldness of the cold medium to the flue gas, reduces the flue gas temperature, and discharges the flue gas cooled to below 30°C; In the second step, the flue gas cooled to below 30° C. is input into the partition-type heat exchanger (2), the partition-type heat exchanger (2) inputs the medium in the heating main pipe of the boiler, transfers the heat of the medium in the heating main pipe to the flue gas cooled to below 30° C., raises the temperature of the flue gas to above 50° C., and outputs the flue gas heated to above 50° C.; The third step is to transport the flue gas heated to above 50° C. to the smoke exhaust device (3) to exhaust the flue gas.

5. The method for deep recovery of flue gas waste heat and elimination of white mist according to claim 4, characterized in that: The second step and the third step also include: first conveying the flue gas heated to above 50° C. to a gas-liquid separation device (25) to separate the liquid in the flue gas, and then conveying the remaining flue gas to a smoke exhaust device (3) to exhaust the remaining flue gas.

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