CN118565225B - A flue gas waste heat recovery system and method for energy-saving heating furnace - Google Patents

Abstract

The present invention relates to the technical field of heating furnaces, and specifically discloses a flue gas waste heat recovery system and method for an energy-saving heating furnace, including a denitrification tower, a softening water device, a deaerator and a steam boiler, wherein the heat exchange tube includes an inner tube body and an outer tube body, the end of the inner tube body extends into the outer tube body, and the inner tube body can move along the length direction of the heat exchange tube; an outer cleaning member is slidably sleeved on the outer tube body along the length direction of the heat exchange tube, and the outer cleaning member can move along the length direction of the heat exchange tube; a clamping member is slidably sleeved on the outer tube body along the length direction of the heat exchange tube, and moves along the length direction of the heat exchange tube synchronously with the outer cleaning member, and the clamping member has a clamp for clamping the inner tube body; the inner cleaning member is arranged in the inner tube body, and is used to clean the inner wall of the inner tube body when the inner tube body moves along the length direction of the heat exchange tube. The flue gas waste heat recovery system and method for an energy-saving heating furnace can realize self-cleaning of smoke and scaling substances inside the equipment without stopping the machine, and prevent equipment blockage.

Description

A flue gas waste heat recovery system and method for energy-saving heating furnace

Technical Field

The present invention relates to the technical field of heating furnaces, and in particular to a flue gas waste heat recovery system and method for an energy-saving heating furnace.

Background Art

A heating furnace is a widely used equipment in the metallurgical industry. Its main function is to heat materials or workpieces (usually metals) to rolling and forging temperatures. A steel heating furnace is a specific type of heating furnace. The flue gas temperature emitted by it is about 320℃~460℃, which contains a large amount of heat energy. If the emitted heat energy is not effectively utilized, it will cause a huge waste of energy. Through the flue gas waste heat recovery system, these heat energies can be effectively converted into reusable energy, such as heat energy or electrical energy, thereby improving the energy utilization efficiency of the entire production process. The flue gas waste heat recovery system usually includes exhaust gas treatment equipment and a heat exchanger. The high-temperature flue gas emitted by the steel heating furnace is treated by the exhaust gas treatment equipment for denitrification and other treatments, and then sent to the heat exchanger to transfer the heat to water or air, thereby recovering the emitted heat energy for other production processes or heating systems.

The flue gas waste heat recovery system has various uses, and the softening water device is one of the application forms. As shown in Figure 7, the high-temperature flue gas discharged from the steel heating furnace is passed into the softening water device, and is discharged after heat exchange with the temporary hard water in the softening water device to heat the temporary hard water, so that the calcium bicarbonate and magnesium bicarbonate contained in the temporary hard water are decomposed by heat, and the calcium and magnesium in the temporary hard water are precipitated into basic carbonates and removed. However, when the high-temperature flue gas exchanges heat with the temporary hard water, the inside of the equipment is prone to blockage due to the deposition and adhesion of smoke or scaling substances in the flue gas, resulting in a decrease in heat transfer efficiency and even equipment failure.

Summary of the invention

The present invention provides a flue gas waste heat recovery system and method for an energy-saving heating furnace, aiming to solve the problem in the related art that the flue gas waste heat recovery system for a heating furnace is prone to blockage due to the deposition and adhesion of smoke dust or scaling substances in the flue gas.

The invention discloses a flue gas waste heat recovery system for an energy-saving heating furnace, comprising a denitrification tower, a softening water device, a deaerator and a steam boiler, wherein the softening water device comprises: a softening tank for containing hard water to be treated; a heat exchange tube, wherein a plurality of heat exchange tubes are arranged in the softening tank, wherein the heat exchange tube comprises an inner tube body and an outer tube body, wherein the end of the inner tube body extends into the outer tube body, and the inner tube body can move along the length direction of the heat exchange tube, so that the end of the inner tube body cleans the inner wall of the outer tube body, and the end of the outer tube body cleans the outer wall of the inner tube body; an external cleaning member, wherein the external cleaning member cleans the outer wall of the inner tube body; and The outer cleaning member is slidably mounted on the outer tube body along the length direction of the heat exchange tube, and the outer cleaning member can move along the length direction of the heat exchange tube so that the outer cleaning member cleans the outer wall of the outer tube body; the clamping member is slidably mounted on the inner tube body along the length direction of the heat exchange tube, and moves along the length direction of the heat exchange tube synchronously with the outer cleaning member, and the clamping member has a clamp for clamping the inner tube body to drive the inner tube body to move along the length direction of the heat exchange tube; the inner cleaning member is arranged in the inner tube body and is used to clean the inner wall of the inner tube body when the inner tube body moves along the length direction of the heat exchange tube. The heat exchange tube is arranged as an inner tube body and an outer tube body which can slide relative to each other, and the movement state of the inner tube body is controlled by a clamping piece. When the clamping piece loosens the inner tube body and the outer cleaning piece moves along the length direction of the heat exchange tube, it is used to clean the outer wall of the outer tube body. When the clamping piece clamps the inner tube body and the inner tube body and the outer cleaning piece move synchronously along the length direction of the heat exchange tube, it is used to clean the inner and outer walls of the heat exchange tube at the same time; thereby, self-cleaning of smoke and scaling substances inside the equipment can be achieved, which can effectively prevent equipment blockage, and can be carried out without stopping the machine to ensure work efficiency.

Preferably, the softening water device also includes a vent pipe and a driving mechanism driven by flue gas, the vent pipe is arranged outside the softening tank and is connected to the plurality of heat exchange pipes for inputting or outputting flue gas; the driving mechanism includes a turbine and a turntable, the turbine is arranged at the inlet end of the vent pipe for being driven by flue gas, the turntable rotates with the turbine, a crank is provided on the turntable, and a rocker is provided on the clamping member or the external cleaning member that reciprocates with the rotation of the crank to drive the clamping member and the external cleaning member to move along the length direction of the heat exchange pipe. The kinetic energy of the flue gas flow is converted into mechanical energy to drive the clamping member and the external cleaning member to move, the transmission structure is simple and reliable, no additional driving source is required, and it conforms to the concept of energy saving and environmental protection.

Preferably, the clamping member is further provided with a telescopic rod for controlling the clamp to move radially along the inner tube body to clamp or release the inner tube body, and the clamp is in a C-shape with its opening facing the inner tube body.

Preferably, the softening water device further comprises a hydraulic mechanism for driving the telescopic rod to extend and retract, the hydraulic mechanism comprises a hydraulic cylinder, a hydraulic plug, an adjusting cam and a follower, the telescopic rod is provided with a hydraulic oil inlet, the hydraulic oil outlet of the hydraulic cylinder is connected with the hydraulic oil inlet of the telescopic rod, the adjusting cam has a guide groove, one end of the follower is fixed with the hydraulic plug, the other end of the follower cooperates with the guide groove, the adjusting cam rotates with the turbine to drive the follower to reciprocate, so that the hydraulic plug reciprocates in the hydraulic cylinder, thereby controlling the extension and retraction of the telescopic rod. The automatic control of the clamp is realized by the cam mechanism and the hydraulic system, which is easy to control and has high transmission efficiency.

Preferably, the adjusting cam is fixed to the sixth gear, a fifth gear is provided between the sixth gear and the delay gear, the fifth gear meshes with the sixth gear, the delay gear rotates with the turbine, and the delay gear is further provided with a delay tooth portion that can mesh with the fifth gear, so as to extend the rotation cycle of the adjusting cam and realize intermittent cleaning of the inner wall of the heat exchange tube.

Preferably, the outer cleaning member and the clamping member are respectively in the shape of a disc, so that the outer cleaning member and the clamping member can stir the water in the softening tank, increase the fluidity of the water in the softening tank, and improve the heat transfer efficiency.

Preferably, the inner cleaning member comprises a fixing rod and a cleaning ring, the fixing rod is fixed to the softening tank, the inner circumference of the cleaning ring is fixed to the fixing rod via a connecting piece, and the outer circumference of the cleaning ring is in contact with the inner wall of the inner tube body.

Preferably, the outer cleaning member is fixedly connected to the clamping member via a connecting rod, and the plurality of inner tube bodies are fixedly connected via a fixing plate.

The present invention also provides a method for recovering waste heat from flue gas of an energy-saving heating furnace, comprising the following steps: a first step, the flue gas is drawn out from the outlet flue of the furnace body and enters a denitrification tower for denitrification treatment; a second step, the flue gas after denitrification enters a softening water device, and the heat in the flue gas is used to heat the hard water to be treated in the softening tank, and the hard water in the softening tank is replaced with softened water; a third step, the softened water is pressurized by a deoxygenation water pump and enters a deaerator for deoxygenation treatment; a third step, the deoxygenated water enters a steam boiler, and the flue gas discharged from the softening water device enters the steam boiler, and the waste heat in the flue gas is used to assist the steam boiler in heating the deoxygenated water, and the water absorbs heat to become hot steam and enters the steam pipe network; a fourth step, the oxygen discharged from the deaerator enters a burner in the furnace body as a combustion aid. The heat energy in the exhaust flue gas is used to heat and soften the hard water, and the waste heat in the flue gas is used again to assist the steam boiler to heat the softened and deoxygenated water for use in the steam network. The oxygen discharged from the deaerator can also be recycled in the heating furnace, which improves the energy utilization efficiency, achieves high efficiency and energy saving, and can significantly reduce production costs.

By adopting the above technical scheme, the beneficial effects of the present invention are: the discharged heat energy is recycled and used in the steam pipeline network, which improves the energy utilization efficiency, achieves high efficiency and energy saving, and can significantly reduce the production cost; and the kinetic energy of the flue gas flow is converted into mechanical energy, without the need to set up an additional driving source, and the self-cleaning of smoke and scaling materials inside the equipment can be achieved without stopping the machine, thereby promoting the flow of heat exchange medium, effectively preventing equipment blockage and improving work efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a flue gas waste heat recovery system of an energy-saving heating furnace according to the present invention.

FIG. 2 is a schematic structural diagram of the water softening device in FIG. 1 .

FIG. 3 is a schematic structural diagram of the outer cleaning member in FIG. 2 .

FIG. 4 is a schematic structural diagram of the clamping member in FIG. 2 .

FIG. 5 is a schematic structural diagram of the inner cleaning member in FIG. 2 .

FIG. 6 is a schematic structural diagram of the driving mechanism and the hydraulic mechanism in FIG. 2 .

FIG. 7 is a schematic diagram of the prior art structure.

Reference numerals:

10. Furnace body; 110. Denitration tower; 120. Softening water device; 130. Deaerator; 140. Steam boiler; 20. Softening tank; 30. Ventilation pipe; 40. Heat exchange pipe; 410. Inner tube body; 420. Outer tube body; 50. External cleaning part; 510. Connecting rod; 60. Clamping part; 610. Clamp; 620. Telescopic rod; 6210. Hydraulic oil inlet; 70. Inner cleaning part; 710. Fixing rod; 720. Cleaning ring; 730. Connecting plate; 80, turbine; 810, first gear; 820, second gear; 830, rotating shaft; 840, turntable; 850, crank; 860, rocker; 90, hydraulic cylinder; 910, third gear; 920, delay gear; 9210, delay tooth portion; 930, fifth gear; 940, sixth gear; 950, adjusting cam; 9510, guide groove; 960, follower; 970, hydraulic plug; 980, hydraulic oil outlet.

DETAILED DESCRIPTION

Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

As shown in FIGS. 1 to 6 , the flue gas waste heat recovery system of the energy-saving heating furnace of the present invention includes a furnace body 10 , a denitration tower 110 , a softening water device 120 , a deaerator 130 and a steam boiler 140 .

The softening water device 120 includes a softening tank 20, a vent pipe 30, a heat exchange pipe 40, an external cleaning member 50, a clamping member 60, an internal cleaning member 70, a driving mechanism and a hydraulic mechanism. The vent pipe 30, the driving mechanism and the hydraulic mechanism are arranged outside the softening tank 20, and the heat exchange pipe 40, the external cleaning member 50, the clamping member 60 and the internal cleaning member 70 are arranged inside the softening tank 20.

The softening tank 20 is in a rectangular parallelepiped shape, and the softening tank 20 contains temporary hard water to be treated.

The heat exchange tube 40 is used for heat exchange between flue gas and hard water, and a plurality of heat exchange tubes 40 are arranged in a circular array. The heat exchange tube 40 includes an inner tube body 410 and an outer tube body 420 . A plurality of inner tube bodies 410 are fixedly connected by a fixing plate, and each inner tube body 410 is located between two outer tube bodies 420. The two outer tube bodies 420 are fixedly connected to the softening tank 20 respectively. The two ends of the inner tube body 410 extend into the two outer tube bodies 420 respectively. The inner tube body 410 can reciprocate along the length direction of the heat exchange tube 40, so that the ends of the inner tube body 410 clean the inner wall of the outer tube body 420, scrape and loosen the smoke dust deposited on the inner wall of the outer tube body 420, and carry it out of the device with the flow of the flue gas. At the same time, the ends of the outer tube body 420 clean the outer wall of the inner tube body 410, scrape and loosen the scaling materials deposited on the outer wall of the inner tube body 410, and make them fall to the bottom of the softening tank 20 and be collected and treated together with the carbonate precipitate precipitated in the hard water.

The ventilation pipes 30 are disposed at both ends of the softening tank 20 in the length direction and are respectively connected to a plurality of outer tube bodies 420 for inputting or outputting flue gas.

The external cleaning member 50 is disc-shaped and is slidably mounted outside the outer tube body 420 along the length direction of the heat exchange tube 40. The external cleaning member 50 can reciprocate along the length direction of the heat exchange tube 40, so that the external cleaning member 50 cleans the outer wall of the outer tube body 420, scrapes off and loosens the scaling materials deposited on the outer wall of the outer tube body 420, and makes them fall to the bottom of the softening tank 20, and are collected and processed together with the carbonate precipitates precipitated in the hard water. At the same time, the external cleaning member 50 can also stir the water in the softening tank 20, increase the fluidity of the water in the softening tank 20, and improve the heat transfer efficiency.

The clamping member 60 is disc-shaped and is slidably mounted outside the inner tube body 410 along the length direction of the heat exchange tube 40. The clamping member 60 and the outer cleaning member 50 are fixedly connected by a connecting rod 510, so that the clamping member 60 and the outer cleaning member 50 can move back and forth synchronously along the length direction of the heat exchange tube 40. The clamping member 60 also has the function of stirring the water in the softening tank 20. The clamping member 60 includes a clamp 610 and a telescopic rod 620. The clamping member 60 is provided with a plurality of through holes corresponding to the inner tube body 410. The size of the through holes is larger than the outer diameter of the inner tube body 410. The four through holes at the top of the clamping member 60 are respectively installed with clamps 610. The clamp 610 is in a C shape with its opening facing the inner tube body 410, and is used to clamp the inner tube body 410 to drive the inner tube body 410 to move along the length direction of the heat exchange tube 40; the telescopic rod 620 is connected to the clamp 610 in a one-to-one correspondence, and is used to control the radial movement of the clamp 610 along the inner tube body 410 to clamp or release the inner tube body 410. The telescopic rod 620 is provided with a hydraulic oil inlet 6210.

The inner cleaning member 70 is arranged in the inner tube body 410. The inner cleaning member 70 includes a fixing rod 710, a cleaning ring 720 and a connecting piece 730. The fixing rod 710 is fixed to the softening tank 20, the inner peripheral side of the cleaning ring 720 is fixed to the fixing rod 710 through the connecting piece 730, and the outer peripheral side of the cleaning ring 720 is in contact with the inner wall of the inner tube body 410, and is used to clean the inner wall of the inner tube body 410 when the inner tube body 410 moves along the length direction of the heat exchange tube 40, and to scrape and loosen the smoke and dust deposited on the inner wall of the inner tube body 410, so that it can be taken out of the device with the flow of smoke.

The driving mechanism includes a turbine 80, a first gear 810, a second gear 820, a rotating shaft 830, a rotating disk 840, a crank 850 and a rocker 860. The turbine 80 is arranged at the inlet end of the vent pipe 30 and is used to be driven by the flue gas. The turbine 80 is fixed to the first gear 810 through a connecting shaft. The rotating disk 840 is fixed to the top of the rotating shaft 830, and the second gear 820 is fixed to the bottom of the rotating shaft 830. The second gear 820 is meshed with the first gear 810 to realize that the rotating disk 840 rotates with the turbine 80; the rotating disk 840 is rotatably connected with a crank 850, and the crank 850 is rotatably connected with a rocker 860. The rocker 860 is fixed on the clamp 60, so that when the rotating disk 840 rotates, the crank 850 is driven to rotate, and the crank 850 drives the rocker 860 to reciprocate along the length direction of the heat exchange tube 40, thereby driving the clamp 60 and the external cleaning member 50 to reciprocate along the length direction of the heat exchange tube 40.

The hydraulic mechanism includes a hydraulic cylinder 90 , a third gear 910 , a delay gear 920 , a fifth gear 930 , a sixth gear 940 , an adjustment cam 950 , a follower 960 and a hydraulic plug 970 . The third gear 910 is fixed on the rotating shaft 830 to rotate with the rotating shaft 830. The third gear 910 is meshed with the delay gear 920. The bottom end of the adjusting cam 950 is fixed to the sixth gear 940. A fifth gear 930 is provided between the sixth gear 940 and the delay gear 920. The fifth gear 930 is meshed with the sixth gear 940. The delay gear 920 is provided with a delay tooth portion 9210 that can mesh with the fifth gear 930, so that the delay gear 920 rotates several circles with the turbine 80, driving the adjusting cam 950 to rotate one circle, thereby extending the rotation period of the adjusting cam 950; the adjusting cam 950 has a guide groove 9510, and the guide groove 9510 includes a horizontal groove, a spiral groove and a vertical groove that are sequentially connected along the circumference of the adjusting cam 950, and the follower 960 slides The follower 960 is assembled on the rotating shaft 830, and a spring is provided between the follower 960 and the rotating shaft 830 to apply elastic force to the follower 960, so that the follower 960 has a tendency to move downward, thereby helping the follower 960 to reset; one end of the follower 960 is fixed to the hydraulic plug 970, and the other end of the follower 960 cooperates with the guide groove 9510 to achieve that when the adjusting cam 950 rotates, the follower 960 is driven to move along the guide groove 9510, so that the follower 960 moves back and forth in the vertical direction, and the hydraulic plug 970 moves back and forth in the hydraulic cylinder 90 to adjust the hydraulic oil pressure output by the hydraulic cylinder 90. The hydraulic oil outlet 980 of the hydraulic cylinder 90 is connected to the hydraulic oil inlet 6210 of the telescopic rod 620 through a hydraulic pipe, so as to control the extension and retraction of the telescopic rod 620 through a hydraulic mechanism.

The method for recovering waste heat from flue gas of an energy-saving heating furnace comprises the following steps:

In the first step, the flue gas is led out from the outlet flue of the furnace body 10 and enters the denitrification tower 110 for denitrification treatment.

In the second step, the flue gas after denitration enters the softening water device 120, and the flue gas enters the heat exchange tube 40 from the ventilation pipe 30. The heat in the flue gas is used in the heat exchange tube 40 to heat the hard water to be treated in the softening tank 20, and the hard water in the softening tank 20 is replaced with softened water. When the flue gas passes through the ventilation pipe 30, it drives the turbine 80 to rotate. The turbine 80 drives the second gear 820 to rotate through the first gear 810. The second gear 820 drives the rotating shaft 830 and the turntable 840 to rotate synchronously. The turntable 840 drives the crank 850 to rotate around the center of the turntable 840. The crank 850 drives the rocker 860, the clamping member 60 and the external cleaning member 50 to reciprocate along the length direction of the heat exchange tube 40. The outer wall of the outer tube body 420 is cleaned and the water in the softening tank 20 is stirred at the same time; when the rotating shaft 830 rotates, the delay gear 920 is driven to rotate through the third gear 910. After the delay gear 920 rotates several circles, the fifth gear 930 engages with the delay tooth portion 9210, driving the sixth gear 940 and the adjusting cam 950 to rotate one circle, so that the follower 960 is raised and lowered once, and then the clamp 610 is clamped and released on the inner tube body 410 once through the hydraulic cylinder 90. When the clamp 610 clamps the inner tube body 410, the clamp 60 drives the inner tube body 410 to move back and forth along the length direction of the heat exchange tube 40, so as to clean the inner and outer walls of the heat exchange tube 40 at the same time.

In the third step, the softened water is pressurized by a deoxygenation pump and then enters the deaerator 130 for deoxygenation treatment.

In the third step, the deoxygenated water enters the steam boiler 140, and the flue gas discharged from the softening water device 120 enters the steam boiler 140. The waste heat in the flue gas is used to assist the steam boiler 140 to heat the deoxygenated water. The water absorbs heat and becomes hot steam and enters the steam network.

In the fourth step, the oxygen exhausted from the deaerator 130 enters the burner in the furnace body 10 as a combustion aid.

In this way, the flue gas waste heat recovery system of the energy-saving heating furnace of the present invention recycles the discharged heat energy and uses it for the steam pipeline network, thereby improving energy utilization efficiency, achieving high-efficiency energy saving, and significantly reducing production costs; and the kinetic energy of the flue gas flow is converted into mechanical energy without the need to set up an additional driving source, thereby achieving self-cleaning of smoke and scaling materials inside the equipment without stopping the machine, promoting the flow of heat exchange medium, and effectively preventing equipment blockage and improving work efficiency.

In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims (2)

1. The utility model provides a flue gas waste heat recovery system of energy-conserving heating furnace, includes denitration tower, softened water device, deaerator and steam boiler, its characterized in that, softened water device includes: the softening tank is used for containing hard water to be treated; the heat exchange pipes are arranged in the softening tank, the heat exchange pipes comprise inner pipe bodies and outer pipe bodies, the end parts of the inner pipe bodies extend into the outer pipe bodies, the inner pipe bodies can move along the length direction of the heat exchange pipes, the end parts of the inner pipe bodies clean the inner walls of the outer pipe bodies, and meanwhile the end parts of the outer pipe bodies clean the outer walls of the inner pipe bodies; the outer cleaning piece is sleeved outside the outer tube body in a sliding manner along the length direction of the heat exchange tube, and can move along the length direction of the heat exchange tube, so that the outer cleaning piece cleans the outer wall of the outer tube body; the clamping piece is sleeved outside the inner tube body in a sliding manner along the length direction of the heat exchange tube and synchronously moves along the length direction of the heat exchange tube with the outer cleaning piece, and the clamping piece is provided with a clamp for clamping the inner tube body so as to drive the inner tube body to move along the length direction of the heat exchange tube; the inner cleaning piece is arranged in the inner tube body and is used for cleaning the inner wall of the inner tube body when the inner tube body moves along the length direction of the heat exchange tube; the vent pipe is arranged outside the softening tank and is communicated with the plurality of heat exchange pipes and used for inputting or outputting smoke;

The driving mechanism comprises a turbine and a rotary table, the turbine is arranged at the inlet end of the vent pipe and is used for being pushed by flue gas, the rotary table rotates along with the turbine, a crank is arranged on the rotary table, and a rocker which moves reciprocally along with the rotation of the crank is arranged on the clamping piece or the outer cleaning piece so as to drive the clamping piece and the outer cleaning piece to move along the length direction of the heat exchange pipe;

the clamping piece is also provided with a telescopic rod for controlling the clamp to move along the radial direction of the inner pipe body so as to clamp or loosen the inner pipe body, and the clamp is C-shaped with an opening facing the inner pipe body;

The water softening device also comprises a hydraulic mechanism for driving the telescopic rod to stretch out and draw back, the hydraulic mechanism comprises a hydraulic cylinder, a hydraulic plug, an adjusting cam and a driven piece, the telescopic rod is provided with a hydraulic oil inlet, a hydraulic oil outlet of the hydraulic cylinder is communicated with the hydraulic oil inlet of the telescopic rod, the adjusting cam is provided with a guide groove, one end of the driven piece is fixed with the hydraulic plug, the other end of the driven piece is matched with the guide groove, and the adjusting cam rotates along with the turbine to drive the driven piece to reciprocate, so that the hydraulic plug reciprocates in the hydraulic cylinder, and the telescopic rod is controlled to stretch out and draw back;

the adjusting cam is fixed with a sixth gear, a fifth gear is arranged between the sixth gear and the delay gear, the fifth gear is meshed with the sixth gear, the delay gear rotates along with the turbine, and a delay tooth part capable of being meshed with the fifth gear is further arranged on the delay gear;

the outer cleaning piece and the clamping piece are respectively disc-shaped;

The inner cleaning piece comprises a fixing rod and a cleaning ring, the fixing rod is fixed with the softening tank, the inner peripheral side of the cleaning ring is fixed on the fixing rod through a connecting sheet, and the outer peripheral side of the cleaning ring is attached to the inner wall of the inner pipe body;

the outer cleaning piece is fixedly connected with the clamping piece through a connecting rod, and a plurality of inner tubes are fixedly connected through a fixed disc.

2. A flue gas waste heat recovery method of an energy-saving heating furnace, characterized in that the flue gas waste heat recovery system of the energy-saving heating furnace according to claim 1 is adopted, comprising the following steps:

firstly, leading out flue gas from an outlet flue of a furnace body, and enabling the flue gas to enter a denitration tower for denitration treatment;

secondly, the flue gas after denitration enters a water softening device, the heat in the flue gas is utilized to heat the hard water to be treated in the softening tank, and the hard water in the softening tank is replaced by the softened water;

thirdly, the softened water is pressurized by an oxygen removal water pump and then enters an oxygen remover for oxygen removal treatment;

Thirdly, the deoxidized water enters a steam boiler, the flue gas discharged from the water softening device enters the steam boiler, the waste heat in the flue gas is utilized to assist the steam boiler to heat the deoxidized water, and the water absorbs heat to become hot steam and enters a steam pipe network;

and fourthly, oxygen discharged from the deaerator enters a burner in the furnace body to be used as a combustion improver.