Boiler flue gas waste heat recovery and utilization system

Abstract

The invention discloses a boiler flue gas waste heat recovery and utilization system which comprises a boiler barrel, one end of the boiler barrel is communicated with a front smoke box, the other end of the boiler barrel is communicated with a rear smoke box, one end of the front smoke box is fixedly provided with a combustor, a combustion opening of the combustor is communicated with a hearth, and the hearth is fixedly installed in the boiler barrel. A transition smoke box is installed at one end of the hearth in a communicating mode, a first return pipe is installed between the transition smoke box and the front smoke box in a communicating mode, and a second return pipe is installed between the front smoke box and the rear smoke box in a communicating mode, so that smoke enters the rear smoke box along the second return pipe and is exhausted from a first smoke exhaust pipe. And the second smoke exhaust pipe exhausts the smoke into the waste heat recovery mechanism. Through the design of the waste heat recovery mechanism, exhausted smoke is used for heating sucked air, high-temperature air is mixed with coal, more sufficient oxygen can be provided when the coal is combusted in the hearth, and the combustion reaction is more complete.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas waste heat recovery equipment, and particularly to a boiler flue gas waste heat recovery and utilization system. Background Technique

[0002] A boiler is an energy conversion device. The energy input into the boiler includes the chemical energy in fuel, electric energy, and the steam, high-temperature water, or organic heat carrier with a certain amount of heat energy output by the boiler. The hot water or steam generated in the boiler can directly provide the required heat energy for industrial production and people's livelihood, or can be converted into mechanical energy through a steam power device, or further converted into electric energy through a generator. The flue gas generated during operation has a relatively high temperature. If directly discharged into the environment, it will cause waste. To ensure the sustainable utilization of resources, a boiler flue gas waste heat recovery device will be set up for recovery.

[0003] For example, the patent with the national authorization patent publication number CN220601543U discloses a boiler flue gas waste heat recovery device, which relates to the technical field of flue gas waste heat recovery equipment. It includes a recovery unit and an air inlet opened at the input end of the recovery unit, and also includes a heat absorption unit arranged at the input part of the recovery unit, a filtering unit and a cleaning unit arranged in the recovery unit, and a discharge unit arranged at the output part of the recovery unit; the heat absorption unit includes a water inlet pipe and a water outlet pipe installed on the side wall of the input part of the recovery unit, and a serpentine heat exchange pipe arranged between the water inlet pipe and the water outlet pipe for heat transfer. The utility model is a boiler flue gas waste heat recovery device. Through the arranged heat absorption unit and filtering unit, during normal operation, the convenient replacement of the filter screen can be realized.

[0004] However, the above-mentioned boiler flue gas waste heat recovery device cannot use the heat in the discharged flue gas to heat the inhaled air and coal mixture to burn in the furnace, so more fuel needs to be consumed to maintain the same output, increasing the operating cost. At the same time, it cannot centrally store the particulate matter filtered from the flue gas, which will cause the particulate matter to be dispersed in different positions, increasing the cleaning difficulty and requiring more manpower and time to clean the particulate matter inside the device, affecting the normal maintenance and operation of the device. Summary of the Invention

[0005] The purpose of the present invention is to provide a boiler flue gas waste heat recovery and utilization system to solve the problem in the above-mentioned background technique that the heat in the discharged flue gas cannot be used to heat the inhaled air and coal mixture to burn in the furnace, so more fuel needs to be consumed to maintain the same output.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A boiler flue gas waste heat recovery and utilization system, comprising: a boiler drum, one end of the boiler drum is connected and installed with a front smoke box, the other end of the boiler drum is connected and installed with a rear smoke box, a burner is fixedly installed at one end of the front smoke box, the combustion port of the burner is communicated with a furnace, the furnace is fixedly installed inside the boiler drum and penetrates through the front smoke box, one end of the furnace is connected and installed with a transfer smoke box, and the transfer smoke box penetrates to the middle part inside the rear smoke box;

[0008] Wherein, a first return pipe is connected and installed between the outer ring part of the transfer smoke box and the inner ring part of the front smoke box, and a second return pipe is connected and installed between the outer ring part of the front smoke box and the outer ring part of the rear smoke box, so that the burner can ignite coal and burn in the furnace after being mixed with air, and the flue gas generated by the combustion enters the transfer smoke box through the furnace and enters the first return pipe. Furthermore, the first return pipe can introduce the flue gas into the front smoke box and then into the second return pipe, and the flue gas can enter the rear smoke box along the second return pipe and be discharged from the first exhaust pipe. The first exhaust pipe is connected and installed on the outer surface of the rear smoke box. During the process that the flue gas passes through the first return pipe and the second return pipe in sequence, the first return pipe and the second return pipe will use the heat of the flue gas to secondary heat the water in the boiler drum;

[0009] Wherein, a dust removal mechanism is connected and installed at one end of the first exhaust pipe, so that the dust removal mechanism filters the discharged flue gas and then discharges it into the second exhaust pipe connected and installed at the other end. In this way, the second exhaust pipe discharges the flue gas into the waste heat recovery mechanism. One end of the waste heat recovery mechanism is connected and installed with a first fan, and the air outlet of the first fan is connected and installed at one end of the air inlet of the burner. Furthermore, the waste heat recovery mechanism can use the waste heat of the flue gas to heat the air inhaled by the first fan, and the heated air enters the burner and is mixed with coal for combustion. Since the air temperature rises, the fuel can more easily reach the ignition point in the furnace, enabling it to burn more fully, thereby reducing the emissions of pollutants such as hydrocarbons, sulfur dioxide, and carbon monoxide;

[0010] Wherein, two groups of support rods are fixedly installed at one end of the boiler drum, and locking sleeve mechanisms are fixedly installed on the upper surfaces of the two groups of support rods. The two groups of locking sleeve mechanisms can be sleeved on the outer surfaces of the joints between the dust removal mechanism and the first exhaust pipe and the second exhaust pipe.

[0011] Preferably, the locking sleeve mechanism includes a first sleeve, the first sleeve is fixedly installed on the upper surface of the support rod, a second sleeve is rotatably installed at one end of the first sleeve, and the second sleeve can be spliced with the first sleeve by flipping, and the joints between the dust removal mechanism and the first exhaust pipe and the second exhaust pipe can be sleeved inside.

[0012] Preferably, a buckle lock is fixedly installed at one end of the upper surface of the second sleeve. The buckle lock can drive the lock tongue to be buckled on the outer surface of the lock seat through the flipping of the second sleeve, and the lock seat is fixedly installed on the upper surface of the first sleeve.

[0013] Preferably, the dust removal mechanism includes a support frame, and a cyclone dust collector is fixedly installed inside the support frame. The air inlet of the cyclone dust collector can be covered by the first sleeve and the second sleeve and connected to the first exhaust pipe.

[0014] Among them, a second fan is fixedly installed on the upper surface of the cyclone dust collector. The impeller of the second fan rotates inside the air outlet of the cyclone dust collector, so that the impeller of the second fan can quickly extract the filtered flue gas from the inner cylinder of the cyclone dust collector through the air outlet.

[0015] Preferably, one end of the air outlet of the second fan is connected and installed with an extension pipe. The extension pipe of the second fan can be covered by the first sleeve and the second sleeve and connected to the second exhaust pipe.

[0016] Preferably, a dust collection box is connected and installed on the lower surface of the conical barrel ash discharge port of the cyclone dust collector.

[0017] Preferably, the waste heat recovery mechanism includes a frame box, which is connected to the second exhaust pipe. A plurality of heat conduction pipes are longitudinally and fixedly installed inside the frame box. Both ends of the heat conduction pipes penetrate out from both ends inside the frame box, so that the frame box is connected to the air inlet of the first fan through the penetrated heat conduction pipes. A dust-proof net is fixedly installed at the other end of the frame box, and a support is fixedly installed on the lower surface of the frame box.

[0018] Preferably, the second exhaust pipe can discharge the flue gas with waste heat into the frame box, blow through the distance between the plurality of heat conduction pipes and enter the U-shaped pipe. The U-shaped pipe is connected and installed at one end of the frame box, and the heat conduction pipes blown by the flue gas can be heated, and the air sucked by the first fan through the heat conduction pipes can be heated.

[0019] Preferably, the other end of the U-shaped pipe is connected and installed with an economizer, and the other end of the economizer is connected and installed with a smoke exhaust cylinder.

[0020] Preferably, the water pipe in the economizer is connected to the water inlet at the upper end of the outer surface of the boiler drum.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. Through the design of the first return pipe, the second return pipe, the front smoke box, the rear smoke box, the transfer smoke box, the locking sleeve mechanism, the dust removal mechanism and the waste heat recovery mechanism, during use, the burner and the first fan can be started. The first fan will extract external air and supply it into the furnace connected to the burner, so that the burner can ignite the coal and burn it in the furnace in mixture with air. The flue gas generated by the combustion enters the transfer smoke box through the furnace and then enters the first return pipe. Furthermore, the first return pipe can introduce the flue gas into the front smoke box and then into the second return pipe. The flue gas can flow along the second return pipe into the rear smoke box and be discharged from the first exhaust pipe. During the process that the flue gas passes through the first return pipe and the second return pipe in sequence, the first return pipe and the second return pipe will use the heat of the flue gas to reheat the water in the boiler drum, enabling the water in the boiler drum to fully absorb the heat in the flue gas, improving the thermal efficiency of the entire boiler system, making the energy generated by fuel combustion be utilized more fully, reducing energy waste, lowering energy consumption and costs. The flue gas entering the first exhaust pipe will enter the dust removal mechanism connected to it. Furthermore, the dust removal mechanism can filter the discharged flue gas and then discharge it into the second exhaust pipe installed at the other end and connected. The connection between the first exhaust pipe and the second exhaust pipe and the two ends of the dust removal mechanism is covered by the locking sleeve mechanism, allowing it to disconnect from the dust removal mechanism through the flipping of the locking sleeve mechanism after long-term use. Furthermore, the staff can separately remove the dust removal mechanism for maintenance, timely discover and handle the problems existing in the dust removal mechanism, such as cleaning blockages, replacing damaged parts, etc., to ensure the normal operation of the dust removal mechanism. The flue gas entering the second exhaust pipe will enter the waste heat recovery mechanism. One end of the waste heat recovery mechanism is connected to the air inlet of the first fan. Furthermore, the waste heat recovery mechanism can use the waste heat of the filtered flue gas to heat the air inhaled by the first fan. The heated air enters the burner and mixes with the coal for combustion, enabling the fuel to more easily reach the ignition point in the furnace, thereby accelerating the combustion speed, reducing the situation of incomplete combustion, improving the combustion efficiency of the fuel, thus reducing the fuel consumption required for unit steam or hot water production. At the same time, the full combustion of coal can reduce the emissions of pollutants such as hydrocarbons, sulfur dioxide and carbon monoxide.

[0023] 2. Through the design of the first sleeve, the second sleeve, the lock seat, the buckle lock, the cyclone dust collector, the ash collection box and the second fan, after the flue gas is discharged from the first exhaust pipe, the flue gas can enter the air inlet of the cyclone dust collector along the first exhaust pipe, and the flue gas can enter the interior along the tangential direction of the inner wall of the cyclone dust collector at a relatively high speed, so as to form a strong rotating air flow in the cyclone dust collector and generate a centrifugal force field. During the rotation process, the dust particles in the flue gas are thrown to the outer wall of the cyclone dust collector due to their larger mass under the action of centrifugal force, while the flue gas with lighter mass continues to rotate and moves closer to the central part of the cyclone dust collector. The dust particles thrown to the outer wall slide down along the inner wall of the cyclone dust collector under the combined action of gravity and air flow, and finally fall into the ash collection box for centralized storage, realizing the separation of dust particles from the flue gas, making the flue gas entering the subsequent process cleaner, reducing the wear and blockage of the subsequent equipment, and improving the operation efficiency and stability of the whole system. After centrifugal separation, the clean flue gas forms an upward inner rotating air flow at the central part of the cyclone dust collector and enters the outer cylinder to be sucked by the impeller of the rotating second fan. After the flue gas is sucked by the impeller of the second fan, it will be discharged into the second exhaust pipe through the air outlet;

[0024] Moreover, the connection between the first exhaust pipe and the second exhaust pipe and the two ends of the cyclone dust collector is covered by the first sleeve and the second sleeve. When the cyclone dust collector needs to be repaired after long-term use, the staff can lift the buckle lock at the upper end of the outer surface of the second sleeve to let the buckle lock disengage from the outer surface of the lock seat at the upper end of the outer surface of the first sleeve, that is, the locking of the second sleeve at one end of the first sleeve is released, and the flipped second sleeve can release the covering of the cyclone dust collector with the first exhaust pipe and the second exhaust pipe. Furthermore, the staff can separately remove the cyclone dust collector for repair. And by lifting the tower buckle lock, the locking between the second sleeve and the first sleeve can be easily released, realizing the rapid separation of the cyclone dust collector and the exhaust pipe. The operation is simple and convenient, greatly saving the repair time and labor cost.

[0025] 3. Through the design of the box, heat conduction pipes, U-shaped pipes and economizer, after the filtered flue gas enters the second exhaust pipe, the flue gas can enter the box along the second exhaust pipe, be purged through the distance between multiple groups of heat conduction pipes and enter the U-shaped pipe. The heat conduction pipes purged by the flue gas can be heated, enabling the air sucked by the first fan through the heat conduction pipes to be heated and enter the burner to be mixed with coal for combustion in the furnace. The hot air can provide more sufficient oxygen for the combustion of coal, making the combustion reaction more intense and complete, thereby improving the combustion efficiency, enabling the chemical energy in coal to be more fully converted into other forms of energy such as heat energy, reducing energy waste, and at the same time increasing the temperature in the furnace, making the heat transfer more effective, helping to improve the heating efficiency of the water in the boiler drum, generating more steam or hot water, improving the heat production capacity and heat supply effect of the boiler. The flue gas that has heated the heat conduction pipes will enter the economizer again along the U-shaped pipe, allowing the high-temperature flue gas to flow reversely, enabling the heat of the flue gas to be transferred to the low-temperature water pipes to heat the feed water. During the heat exchange process, the heat of the flue gas is continuously transferred to the feed water, causing the temperature of the feed water to gradually increase while the temperature of the flue gas itself continuously decreases. The heated feed water entering the boiler drum can reduce the fuel consumption to heat the water to the saturated state or generate steam because after the feed water temperature rises, the heat required for the water to reach the saturated temperature or generate steam decreases, thereby improving the overall thermal efficiency of the boiler. The cooled flue gas will be discharged from the exhaust chimney at the other end of the economizer. Description of the Drawings

[0026] Figure 1 Left view overall structural schematic diagram of the boiler flue gas waste heat recovery and utilization system of the present invention;

[0027] Figure 2 Right view overall structural schematic diagram of the boiler flue gas waste heat recovery and utilization system of the present invention;

[0028] Figure 3 Structural schematic diagram of the front smoke box and the rear smoke box of the present invention;

[0029] Figure 4 Structural schematic diagram of the first return pipe and the second return pipe of the present invention;

[0030] Figure 5 Structural schematic diagram of the lock sleeve mechanism of the present invention;

[0031] Figure 6 Structural schematic diagram of the dust removal mechanism of the present invention;

[0032] Figure 7 Structural schematic diagram of the waste heat recovery mechanism of the present invention.

[0033] In the figure: 1. Boiler drum; 101. Front smoke box; 102. Rear smoke box; 103. Support rod; 104. Second return pipe; 105. Burner; 106. First fan; 107. Furnace; 108. Transfer smoke box; 109. First return pipe; 2. Lock sleeve mechanism; 201. First sleeve; 202. Second sleeve; 203. Lock seat; 204. Buckle lock; 3. Dust removal mechanism; 301. Support frame; 302. Cyclone dust collector; 303. Ash collecting box; 304. Second fan; 4. Waste heat recovery mechanism; 401. Frame box; 402. Heat conduction pipe; 403. Dust-proof net; 404. U-shaped pipe; 405. Economizer; 406. Smoke exhaust pipe; 407. Support; 5. First smoke exhaust pipe; 6. Second smoke exhaust pipe. Detailed implementation mode

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] Please refer to Figures 1 - 7 , and the following technical solutions are provided in this embodiment:

[0036] As Figures 1 - 4 shown, a boiler flue gas waste heat recovery and utilization system includes: a boiler drum 1, a front smoke box 101 is connected and installed at one end of the boiler drum 1, a rear smoke box 102 is connected and installed at the other end of the boiler drum 1, a burner 105 is fixedly installed at one end of the front smoke box 101, the combustion port of the burner 105 is communicated with the furnace 107, the furnace 107 is fixedly installed in the boiler drum 1 and penetrates through the front smoke box 101, and one end of the furnace 107 is connected and installed with a transfer smoke box 108, and the transfer smoke box 108 penetrates to the middle part in the rear smoke box 102;

[0037] Among them, a first return pipe 109 is connected and installed between the outer ring part of the transfer smoke box 108 and the inner ring part of the front smoke box 101, and a second return pipe 104 is connected and installed between the outer ring part of the front smoke box 101 and the outer ring part of the rear smoke box 102, so that the burner 105 can ignite the coal to mix and burn with air in the furnace 107. The flue gas generated by the combustion enters the transfer smoke box 108 through the furnace 107 and enters the first return pipe 109. Furthermore, the first return pipe 109 can introduce the flue gas into the front smoke box 101 and then into the second return pipe 104, and the flue gas can enter the rear smoke box 102 along the second return pipe 104 and be discharged from the first exhaust pipe 5. The first exhaust pipe 5 is connected and installed on the outer surface of the rear smoke box 102. During the process that the flue gas passes through the first return pipe 109 and the second return pipe 104 in sequence, the first return pipe 109 and the second return pipe 104 will use the heat of the flue gas to reheat the water in the boiler drum 1;

[0038] Among them, a dust removal mechanism 3 is connected and installed at one end of the first exhaust pipe 5, so that the dust removal mechanism 3 filters the discharged flue gas and then discharges it into the second exhaust pipe 6 connected and installed at the other end. In this way, the second exhaust pipe 6 discharges the flue gas into the waste heat recovery mechanism 4. One end of the waste heat recovery mechanism 4 is connected and installed with the first fan 106, and the air outlet of the first fan 106 is connected and installed at one end of the air inlet of the burner 105. Furthermore, the waste heat recovery mechanism 4 can use the waste heat of the flue gas to heat the air inhaled by the first fan 106, and the heated air enters the burner 105 to mix and burn with the coal. Since the air temperature rises, the fuel can more easily reach the ignition point in the furnace 107, enabling it to burn more fully, thereby reducing the emissions of pollutants such as hydrocarbons, sulfur dioxide, and carbon monoxide;

[0039] Among them, two groups of support rods 103 are fixedly installed at one end of the boiler drum 1, and locking sleeve mechanisms 2 are fixedly installed on the upper surfaces of the two groups of support rods 103. The two groups of locking sleeve mechanisms 2 can be sleeved on the outer surfaces of the joints between the two ends of the dust removal mechanism 3 and the first exhaust pipe 5 and the second exhaust pipe 6.

[0040] Through the design of the first return pipe 109, the second return pipe 104, the front smoke box 101, the rear smoke box 102, the transfer smoke box 108, the locking sleeve mechanism 2, the dust removal mechanism 3 and the waste heat recovery mechanism 4, during use, the burner 105 and the first fan 106 can be started. The first fan 106 will extract external air and supply it into the furnace 107 connected to the burner 105, so that the burner 105 can ignite the coal and burn it in the furnace 107 in mixture with the air. The flue gas generated by the combustion enters the transfer smoke box 108 through the furnace 107 and then enters the first return pipe 109. Furthermore, the first return pipe 109 can introduce the flue gas into the front smoke box 101 and then into the second return pipe 104. The flue gas can flow along the second return pipe 104 into the rear smoke box 102 and be discharged from the first exhaust pipe 5. During the process that the flue gas passes through the first return pipe 109 and the second return pipe 104 in sequence, the first return pipe 109 and the second return pipe 104 will use the heat of the flue gas to reheat the water in the boiler drum 1, so that the water in the boiler drum 1 can fully absorb the heat in the flue gas, improving the thermal efficiency of the entire boiler system, enabling the energy generated by the fuel combustion to be utilized more fully, reducing energy waste, lowering energy consumption and costs. The flue gas entering the first exhaust pipe 5 will enter the dust removal mechanism 3 connected to it. Furthermore, the dust removal mechanism 3 can filter the discharged flue gas and then discharge it into the second exhaust pipe 6 installed at the other end and connected in communication. The connection between the first exhaust pipe 5 and the second exhaust pipe 6 and the two ends of the dust removal mechanism 3 is covered by the locking sleeve mechanism 2, enabling it to be disconnected from the dust removal mechanism 3 by the flipping of the locking sleeve mechanism 2 after long-term use. Furthermore, the staff can separately remove the dust removal mechanism 3 for maintenance, and can timely discover and handle the problems existing in the dust removal mechanism 3, such as cleaning blockages, replacing damaged components, etc., to ensure the normal operation of the dust removal mechanism 3. The flue gas entering the second exhaust pipe 6 will enter the waste heat recovery mechanism 4. One end of the waste heat recovery mechanism 4 is connected to the air inlet of the first fan 106. Furthermore, the waste heat recovery mechanism 4 can use the waste heat of the filtered flue gas to heat the air inhaled by the first fan 106. The heated air enters the burner 105 and mixes with the coal for combustion, enabling the fuel to more easily reach the ignition point in the furnace 107. Furthermore, the combustion speed can be increased, reducing the situation of incomplete combustion, improving the combustion efficiency of the fuel, thereby reducing the fuel consumption required for the production of unit steam or hot water. At the same time, the full combustion of coal can reduce the emissions of pollutants such as hydrocarbons, sulfur dioxide and carbon monoxide.

[0041] Such as Figures 5 - 6As shown in the figure, the lock sleeve mechanism 2 includes a first sleeve 201, which is fixedly installed on the upper surface of the support rod 103. One end of the first sleeve 201 is rotatably installed with a second sleeve 202. The second sleeve 202 can be spliced with the first sleeve 201 by flipping, and both ends of the dust removal mechanism 3 can be sleeved at the connection between the first exhaust pipe 5 and the second exhaust pipe 6.

[0042] Among them, a buckle lock 204 is fixedly installed at one end of the upper surface of the second sleeve 202. The buckle lock 204 can drive the lock tongue to be buckled on the outer surface of the lock seat 203 through the flipping of the second sleeve 202, and the lock seat 203 is fixedly installed on the upper surface of the first sleeve 201.

[0043] Among them, the dust removal mechanism 3 includes a support frame 301, and a cyclone dust collector 302 is fixedly installed inside the support frame 301. The air inlet of the cyclone dust collector 302 can be covered by the first sleeve 201 and the second sleeve 202 to communicate with the first exhaust pipe 5.

[0044] Among them, a second fan 304 is fixedly installed on the upper surface of the cyclone dust collector 302. The impeller of the second fan 304 rotates inside the air outlet of the cyclone dust collector 302, so that the impeller of the second fan 304 can quickly extract the filtered flue gas from the inner cylinder of the cyclone dust collector 302 through the air outlet.

[0045] Among them, one end of the air outlet of the second fan 304 is connected and installed with an extension pipe. The extension pipe of the second fan 304 can be covered by the first sleeve 201 and the second sleeve 202 to communicate with the second exhaust pipe 6. A dust collection box 303 is connected and installed on the lower surface of the conical cylinder ash discharge port of the cyclone dust collector 302.

[0046] Through the design of the first sleeve 201, the second sleeve 202, the lock seat 203, the buckle lock 204, the cyclone dust collector 302, the ash collection box 303 and the second fan 304, after the flue gas is discharged from the first exhaust pipe 5, the flue gas can enter the air inlet of the cyclone dust collector 302 along the first exhaust pipe 5, and the flue gas enters the interior along the tangential direction of the inner wall of the cyclone dust collector 302 at a relatively high speed, so as to form a strong rotating airflow in the cyclone dust collector 302, generating a centrifugal force field. During the rotation process, the dust particles in the flue gas are thrown to the outer wall of the cyclone dust collector 302 due to their larger mass under the action of centrifugal force, while the flue gas with lighter mass continues to rotate and moves closer to the central part of the cyclone dust collector 302. The dust particles thrown to the outer wall slide down along the inner wall of the cyclone dust collector 302 under the combined action of gravity and airflow, and finally fall into the ash collection box 303 for centralized storage, realizing the separation of dust particles from the flue gas, making the flue gas entering the subsequent process cleaner, reducing the wear and blockage of subsequent equipment, and improving the operation efficiency and stability of the whole system. After centrifugal separation, the clean flue gas forms an upward inner rotating airflow at the central part of the cyclone dust collector 302 and is sucked into the impeller of the rotating second fan 304 in the outer cylinder. After the flue gas is sucked into the impeller of the second fan 304, it is discharged into the second exhaust pipe 6 through the air outlet;

[0047] Moreover, the connection between the first exhaust pipe 5 and the second exhaust pipe 6 and both ends of the cyclone dust collector 302 are covered by the first sleeve 201 and the second sleeve 202. When the cyclone dust collector 302 needs to be overhauled after long-term use, the staff can lift the buckle lock 204 at the upper end of the outer surface of the second sleeve 202, so that the buckle lock 204 disengages from the outer surface of the lock seat 203 at the upper end of the outer surface of the first sleeve 201, that is, the locking of the second sleeve 202 at one end of the first sleeve 201 is released. The flipped second sleeve 202 can then release the covering of the cyclone dust collector 302 with the first exhaust pipe 5 and the second exhaust pipe 6. Furthermore, the staff can separately remove the cyclone dust collector 302 for overhaul. And by lifting the tower buckle lock 204, the locking between the second sleeve 202 and the first sleeve 201 can be easily released, realizing the quick separation of the cyclone dust collector 302 from the exhaust pipe. The operation is simple and convenient, greatly saving the overhaul time and labor cost.

[0048] As Figure 7 shown, the waste heat recovery mechanism 4 includes a frame box 401. The frame box 401 is connected to the second exhaust pipe 6. A plurality of heat conduction pipes 402 are longitudinally and fixedly installed in the frame box 401. Both ends of the heat conduction pipes 402 penetrate out from both ends inside the frame box 401, so that the frame box 401 is connected to the air inlet of the first fan 106 through the penetrated heat conduction pipes 402. A dust-proof net 403 is fixedly installed at the other end of the frame box 401, and a support 407 is fixedly installed on the lower surface of the frame box 401.

[0049] In this way, the second exhaust pipe 6 can discharge the flue gas with residual heat into the box 401, blow through the distance between multiple groups of heat conduction pipes 402, and enter the U-shaped pipe 404. The U-shaped pipe 404 is connected and installed at one end of the box 401, and the heat conduction pipes 402 blown by the flue gas can be heated. The air sucked by the first fan 106 through the heat conduction pipes 402 can be heated. The other end of the U-shaped pipe 404 is connected and installed with an economizer 405, and the other end of the economizer 405 is connected and installed with an exhaust chimney 406. The water pipe in the economizer 405 is communicated with the water inlet at the upper end of the outer surface of the boiler drum 1.

[0050] Through the design of the box 401, the heat conduction pipes 402, the U-shaped pipe 404 and the economizer 405, after the filtered flue gas enters the second exhaust pipe 6, the flue gas can enter the box 401 along the second exhaust pipe 6, blow through the distance between multiple groups of heat conduction pipes 402, and enter the U-shaped pipe 404. The heat conduction pipes 402 blown by the flue gas can be heated, enabling the air sucked by the first fan 106 through the heat conduction pipes 402 to be heated and enter the burner 105 to be mixed with coal and burned in the furnace 107. The hot air can provide more sufficient oxygen for the combustion of coal, making the combustion reaction more intense and complete, thereby improving the combustion efficiency, enabling the chemical energy in the coal to be more fully converted into other forms of energy such as heat energy, reducing energy waste, and at the same time increasing the temperature in the furnace 107, making the heat transfer more effective, helping to improve the heating efficiency of the water in the boiler drum 1, generating more steam or hot water, improving the heat generation capacity and heat supply effect of the boiler. The flue gas that has heated the heat conduction pipes 402 will enter the economizer 405 again along the U-shaped pipe 404, allowing the high-temperature flue gas to flow reversely, enabling the heat of the flue gas to be transferred to the low-temperature water pipe to heat the feed water. During the heat exchange process, the heat of the flue gas is continuously transferred to the feed water, causing the temperature of the feed water to gradually increase, while the temperature of the flue gas itself continuously decreases. The heated feed water entering the boiler drum 1 can reduce the fuel consumption to heat the water to the saturated state or generate steam because after the temperature of the feed water increases, the heat required to heat the water to the saturated temperature or generate steam decreases, thereby improving the overall thermal efficiency of the boiler. The cooled flue gas will be discharged from the exhaust chimney 406 at the other end of the economizer 405.

[0051] In order to verify the strengthening effect of preheated air on combustion, in this embodiment, the preheated air combustion enhancement factor equation is introduced:

[0052]

[0053] Among them:

[0054] Tair is the preheated air temperature (K);

[0055] T0 is the ambient temperature (300K);

[0056] Rfuel is the fuel reactivity coefficient (0.85 for coal);

[0057] is the mass flow rate (kg / s);

[0058] Cp is the specific heat capacity of air (1005 J / kg·K);

[0059] For example, when the preheated air temperature is increased from 300K to 450K, the coal fuel flow rate is 0.5kg / s, and the air flow rate is 6kg / s: Ec≈32.7. When this value is greater than the reference value of 20, the combustion efficiency is increased by 12% and CO emissions are reduced by 45%, which verifies the strengthening effect of preheated air on combustion and shows that preheating can greatly improve combustion efficiency, reduce CO emissions, and has high energy-saving and environmental protection value.

[0060] In order to improve the heat transfer efficiency, the first return pipe 109 and the second return pipe 104 provided in this embodiment are both spiral pipes. At the same time, this embodiment introduces the equivalent heat transfer equation of the spiral return pipe:

[0061]

[0062] in:

[0063] Qdual is the total heat transfer of the double return pipe (W-watt), which is calculated by the system heat load demand and represents the comprehensive heating capacity of the flue gas to the boiler water when passing through the first and second return pipes;

[0064] L is the total effective heat transfer length of the first and second return pipes (m), which is designed according to the size of the boiler shell (e.g. 3-15m). The length directly affects the heat transfer area and determines the residence time together with the flue gas velocity;

[0065] k1 and k2 are spiral turbulence correction coefficients (dimensionless), k1 = 0.8 ~ 1.2, k2 = 0.9 ~ 1.1, obtained through experimental calibration or CFD simulation fitting, reflecting the disturbance intensity of the spiral structure on the flue gas flow pattern, and are related to the tube wall roughness and spiral angle;

[0066] N1 and N2 are the spiral turns of the first and second return pipes. The first return pipe has N1=5-12, and the second return pipe has N2=3-8. The more turns, the more intense the smoke rotation and the stronger the boundary layer destruction effect, but the flow resistance increases.

[0067] D1 and D2 are the inner diameters of the first and second return pipes (m), D1 = 0.1-0.3m, D2 = 0.2-0.4m, and the flow rate must be 1-5m / s. The pipe diameter determines the flue gas flow rate and pressure drop. The optimization of the D2 / D1 ratio can balance heat transfer and resistance;

[0068] Re is the Reynolds number of the flue gas, Re = ρvd / μ, where v, ρ, and μ are the fluid flow velocity, density, and viscosity coefficient respectively, and d is the inner diameter of the pipe. Generally, the value range is 10 4 -10 5 (turbulent state);

[0069] Pr is the Prandtl number of the flue gas. The typical value of coal-fired flue gas is 0.6 - 0.7, which reflects the ratio of momentum diffusion to heat diffusion of the flue gas and affects the intensity of convective heat transfer;

[0070] ΔTm is the logarithmic mean temperature difference (unit: K), which is calculated from the flue gas inlet temperature Tin, outlet temperature Tout, and boiler water temperature Twater. The calculation formula is as follows:

[0071] The temperature difference potential driving heat transfer needs to be corrected in combination with countercurrent / cocurrent arrangements.

[0072] r o ,r i are the outer radius and inner radius of the return pipe (wall geometric parameters). For example: r i = 0.075m, r o = 0.085m (corresponding to a wall thickness of 10mm), which determines the thermal resistance of the pipe wall ln(r o / r i ) / λwall. The thermal resistance of thick-walled pipes is large but the mechanical strength is high;

[0073] λWall is the thermal conductivity of the pipe wall (W / m·K). For carbon steel: 45 - 50, for stainless steel: 15 - 20, for copper: 380 - 400. High thermal conductivity materials (such as copper) can reduce the pipe wall thermal resistance, but the cost and corrosion resistance need to be considered;

[0074] H water is the convective heat transfer coefficient on the water side, with the unit of W / (m 2 ·K). For natural convection: 200 - 500, for forced convection: 1000 - 5000. It is related to the water flow velocity, temperature, and boiler water circulation method. Increasing the flow velocity can significantly enhance heat transfer.

[0075] Technical influence of the number of spiral turns (N1, N2)

[0076] Positive effect: Increasing the number of spiral turns can strengthen turbulence, break the thermal boundary layer, and increase the heat transfer coefficient, (hgas ∝ N 0.5 );

[0077] Negative effect: It leads to an increase in flow resistance (ΔP ∝ N 1.2 ) and fan energy consumption, and multi-objective optimization is needed for balance.

[0078] Technical impact of the pipe diameter ratio (D2 / D1): When the ratio > 1, the flue gas velocity in the second return pipe decreases, prolonging the heat exchange time but possibly causing ash accumulation; when the ratio < 1, the flow velocity increases, the heat transfer coefficient increases, but the pressure loss rises.

[0079] Technical impact of the overall heat transfer coefficient (denominator term):

[0080] The denominator term represents the total thermal resistance, including the wall conduction ln(r o / r i ) / λwall) and the convection on the water side (1 / h water ). When the heat transfer on the water side is dominant (h water is low), the water circulation system needs to be optimized.

[0081] The specific process of the example parameter design is as follows:

[0082] 1. Goal setting: It is required that Qdual = 1.5 MW, the boiler water temperature Twater = 150 °C, and the flue gas inlet temperature Tin = 600 °C.

[0083] 2. Preliminary selection of parameters:

[0084] Let L = 10 m, D1 = 0.2 m, D2 = 0.3 m, N1 = 10, N2 = 6, k1 = 1.0, k2 = 1.0.

[0085] 3. Calculate Re and Pr:

[0086] The flue gas density ρ is 0.45 kg / m³, the viscosity u is 3.5x10 -5 Pa·s, and the flow velocity v is 3 m / s → Re = (ρvD1) / u = 7714.

[0087] The flue gas cp = 1.1 kJ / (kg·K), λgas = 0.055 W / (m·K) → Pr = (ucp) / λgas = 0.68.

[0088] 4. Solve for △Tm

[0089] Assume the flue gas outlet temperature T out is 400 °C → △Tm = 258.5 K.

[0090] 5. Calculate the total heat transfer:

[0091] Substitute into the formula to get Qdual = 1.52 MW, meeting the design requirements.

[0092] Through the coupling of the number of spiral turns, the pipe diameter ratio, and the turbulence correction factor, the collaborative heat transfer mechanism of the double return pipe is quantified, guiding the balance of heat transfer, pressure loss, and material cost during design, and greatly improving the accuracy compared with traditional empirical formulas.

[0093] Summarize and sort out the working steps of this solution according to the above technical solution: When in use, the burner 105 and the first fan 106 can be started, and the first fan 106 will extract external air and supply it into the furnace 107 connected to the burner 105, so that the burner 105 can ignite the coal and burn it in the furnace 107 after mixing with the air. The flue gas generated by the combustion enters the transfer smoke box 108 through the furnace 107 and enters the first return pipe 109. Then, the first return pipe 109 can introduce the flue gas into the front smoke box 101 and enter the second return pipe 104. The flue gas can flow along the second return pipe 104 into the rear smoke box 102 and be discharged from the first exhaust pipe 5. During the process that the flue gas passes through the first return pipe 109 and the second return pipe 104 in sequence, the first return pipe 109 and the second return pipe 104 will use the heat of the flue gas to reheat the water in the boiler drum 1, so that the water in the boiler drum 1 can fully absorb the heat in the flue gas. The flue gas entering the first exhaust pipe 5 will enter the air inlet of the cyclone dust collector 302 connected to it, and the flue gas will enter the interior at a high speed along the tangential direction of the inner wall of the cyclone dust collector 302, thus forming a strong rotating airflow inside the cyclone dust collector 302 and generating a centrifugal force field. During the rotation process, the dust particles in the flue gas are thrown towards the outer wall of the cyclone dust collector 302 due to their large mass under the action of centrifugal force, while the lighter flue gas continues to rotate and moves towards the central part of the cyclone dust collector 302. The dust particles thrown to the outer wall slide down along the inner wall of the cyclone dust collector 302 under the combined action of gravity and airflow, and finally fall into the ash collection box 303 for centralized storage, realizing the separation of dust particles from the flue gas. After centrifugal separation, the clean flue gas forms an upward inner rotating airflow in the central part of the cyclone dust collector 302 and is sucked into the impeller of the rotating second fan 304 in the outer cylinder. After the flue gas is sucked into the impeller of the second fan 304, it will be discharged into the second exhaust pipe 6 through the air outlet. The flue gas can flow along the second exhaust pipe 6 into the frame box 401, blow through the distance between multiple heat conduction pipes 402 and enter the U-shaped pipe 404. The heat conduction pipes 402 blown by the flue gas can be heated, enabling the air sucked by the first fan 106 through the heat conduction pipes 402 to be heated and enter the burner 105 to be mixed with the coal and burn in the furnace 107. The hot air can provide more sufficient oxygen for the combustion of the coal, making the combustion reaction more intense and complete, thereby improving the combustion efficiency. The flue gas heated by the heat conduction pipes 402 will flow along the U-shaped pipe 404 and enter the economizer 405 again, allowing the high-temperature flue gas to flow in the reverse direction, enabling the heat of the flue gas to be transferred to the low-temperature water pipes to heat the feed water. During the heat exchange process, the heat of the flue gas is continuously transferred to the feed water, causing the temperature of the feed water to gradually increase, while the temperature of the flue gas itself decreases continuously. The heated feed water enters the boiler drum 1, which can reduce the fuel consumption to heat the water to the saturated state or generate steam. Because after the temperature of the feed water increases,The heat required for water to reach the saturation temperature or generate steam is reduced, thereby improving the overall thermal efficiency of the boiler. The cooled flue gas will be discharged from the exhaust chimney 406 at the other end of the economizer 405.

[0094] In summary: This system uses the discharged flue gas to heat the sucked air. The high-temperature air mixed with coal can provide more sufficient oxygen during combustion in the furnace 107, making the combustion reaction more intense and complete, reducing energy waste. At the same time, it can increase the temperature in the furnace 107, making heat transfer more effective, helping to improve the heating efficiency of the water in the boiler drum 1, generating more steam or hot water, and enhancing the heat generation capacity and heating effect of the boiler.

[0095] Parts not involved in the present invention are the same as or can be implemented using existing technologies. Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A boiler flue gas waste heat recovery and utilization system, characterized in that: include: A boiler barrel (1), wherein one end of the boiler barrel (1) is connected to a front smoke box (101) and is installed thereon, and the other end of the boiler barrel (1) is connected to a rear smoke box (102) and is installed thereon, a burner (105) is fixedly installed at one end of the front smoke box (101), a combustion port of the burner (105) is connected to a furnace (107), the furnace (107) is fixedly installed in the boiler barrel (1) and passes through the front smoke box (101), a transfer smoke box (108) is connected to one end of the furnace (107), and the transfer smoke box (108) passes through the middle section of the rear smoke box (102).

2. A boiler flue gas waste heat recovery and utilization system according to claim 1, characterized in that: A first return pipe (109) is installed between the outer ring portion of the transfer smoke box (108) and the inner ring portion of the front smoke box (101), and a second return pipe (104) is installed between the outer ring portion of the front smoke box (101) and the outer ring portion of the rear smoke box (102), so that the burner (105) can ignite the coal and mix it with air in the furnace (107) for combustion, and the smoke generated by the combustion passes through the furnace (107) into the transfer smoke box (108) and into the first return pipe (109), thereby enabling the first return pipe (104) to ignite the coal and mix it with air in the furnace (107). The pipe (109) introduces the smoke into the front smoke box (101) and into the second return pipe (104), so that the smoke can enter the rear smoke box (102) along the second return pipe (104) and be discharged from the first smoke exhaust pipe (5). The first smoke exhaust pipe (5) is connected and installed on the outer surface of the rear smoke box (102). When the smoke passes through the first return pipe (109) and the second return pipe (104) in sequence, the first return pipe (109) and the second return pipe (104) will use the heat of the smoke to perform secondary heating on the water in the boiler drum (1); One end of the first smoke exhaust pipe (5) is connected and installed with a dust removal mechanism (3), and the dust removal mechanism (3) filters the exhausted smoke before discharging it into the second smoke exhaust pipe (6) connected and installed at the other end, so that the second smoke exhaust pipe (6) discharges the smoke into the waste heat recovery mechanism (4), one end of the waste heat recovery mechanism (4) is connected and installed with the first fan (106), and the air outlet of the first fan (106) is connected and installed with one end of the air inlet of the burner (105), so that the waste heat recovery mechanism (4) can use the waste heat of the smoke to heat the air sucked in by the first fan (106), and the heated air enters the burner (105) and is mixed with coal for combustion; Two groups of support rods (103) are fixedly mounted on one end of the boiler drum (1), and locking sleeve mechanisms (2) are fixedly mounted on the upper surfaces of the two groups of support rods (103). The two groups of locking sleeve mechanisms (2) can be mounted on the outer surfaces of the connection between the two ends of the dust removal mechanism (3) and the first smoke exhaust pipe (5) and the second smoke exhaust pipe (6).

3. A boiler flue gas waste heat recovery and utilization system according to claim 2, characterized in that: The locking sleeve mechanism (2) comprises a first sleeve (201), the first sleeve (201) being fixedly mounted on the upper surface of the support rod (103), a second sleeve (202) being rotatably mounted on one end of the first sleeve (201), the second sleeve (202) being capable of being spliced ​​with the first sleeve (201) by flipping, and being capable of sheathing the connection between the two ends of the dust removal mechanism (3) and the first smoke exhaust pipe (5) and the second smoke exhaust pipe (6).

4. A boiler flue gas waste heat recovery and utilization system according to claim 3, characterized in that: A buckle lock (204) is fixedly mounted on one end of the upper surface of the second sleeve (202). The buckle lock (204) can drive the lock tongue to be buckled on the outer surface of the lock seat (203) by turning the second sleeve (202). The lock seat (203) is fixedly mounted on the upper surface of the first sleeve (201).

5. A boiler flue gas waste heat recovery and utilization system according to claim 4, characterized in that: The dust removal mechanism (3) comprises a support frame (301), a cyclone dust collector (302) is fixedly installed in the support frame (301), and the air inlet of the cyclone dust collector (302) can be covered by the first sleeve (201) and the second sleeve (202) so as to be connected to the first smoke exhaust pipe (5); A second fan (304) is fixedly installed on the upper surface of the cyclone dust collector (302), and the impeller of the second fan (304) rotates in the air outlet of the cyclone dust collector (302), so that the impeller of the second fan (304) can quickly allow the inner cylinder of the cyclone dust collector (302) to extract the filtered flue gas through the air outlet.

6. A boiler flue gas waste heat recovery and utilization system according to claim 5, characterized in that: An extension pipe is installed at one end of the air outlet of the second fan (304), and the extension pipe of the second fan (304) can be covered by the first sleeve (201) and the second sleeve (202) to communicate with the second smoke exhaust pipe (6).

7. A boiler flue gas waste heat recovery and utilization system according to claim 6, characterized in that: The lower surface of the cone-shaped ash discharge port of the cyclone dust collector (302) is connected to an ash collection box (303) installed thereon.

8. The boiler flue gas waste heat recovery and utilization system according to claim 6, characterized in that: The waste heat recovery mechanism (4) comprises a frame box (401), the frame box (401) is connected to the second smoke exhaust pipe (6), a plurality of groups of heat-conducting pipes (402) are longitudinally fixedly installed in the frame box (401), both ends of the heat-conducting pipes (402) are passed through the two ends of the frame box (401), so that the frame box (401) is connected to the air inlet of the first fan (106) through the passed heat-conducting pipes (402), a dustproof net (403) is fixedly installed at the other end of the frame box (401), and a support (407) is fixedly installed on the lower surface of the frame box (401).

9. A boiler flue gas waste heat recovery and utilization system according to claim 8, characterized in that: The second smoke exhaust pipe (6) can discharge the smoke with residual heat into the frame box (401) to be blown through the distance between the multiple groups of heat-conducting pipes (402) and enter the U-shaped pipe (404). The U-shaped pipe (404) is connected and installed at one end of the frame box (401), and the heat-conducting pipe (402) blown by the smoke can be heated, and the first fan (106) can be heated by the air sucked by the heat-conducting pipe (402).

10. A boiler flue gas waste heat recovery and utilization system according to claim 9, characterized in that: The other end of the U-shaped tube (404) is connected to an economizer (405) installed thereon, and the other end of the economizer (405) is connected to a smoke exhaust chimney (406) installed thereon. The water pipe in the economizer (405) is connected to the water inlet at the upper end of the outer surface of the boiler tube (1).

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