Waste gas treatment and waste heat recovery system of setting machine

Abstract

The invention relates to a waste gas treatment and waste heat recovery system of a setting machine, which is characterized in that a low-wind-resistance venturi tube is firstly used for removing most of medium and long fibers, oil smoke, dust and the like, and a porous light high-temperature-resistant easy-to-clean material has different forms in water during filtration and suspension backwashing; dust and lampblack are filtered in a compact state of the filler; during backwashing, the filler is automatically dispersed by utilizing buoyancy of the filler in water, and the oil sludge is subjected to suspension rotary friction backwashing and oil sludge recovery by virtue of an oil washing aid without manual cleaning. According to the cleanable heat exchanger, the heat exchange pipe with the large tooth pitch and the large pipe pitch is adopted in the cleanable heat exchanger, meanwhile, the spraying and washing device matched with the tooth pitch and the pipe pitch can automatically spray an oil removing agent and hot water when the pressure difference becomes large, oil stains and dust on the surface of the heat exchange pipe can be cleaned, blockage of the heat exchanger is avoided, and reduction of the heat exchange efficiency is reduced.

Description

Technical Field

[0001] This invention relates to the field of clean energy heating technology, specifically a stenter exhaust gas treatment and waste heat recovery system. Background Technology

[0002] Waste gas generated or produced through combustion generally possesses a certain amount of heat, thus allowing for the recovery and utilization of residual heat. However, since waste gas typically contains particulate matter and oily substances, existing equipment suitable for waste heat recovery often suffers from these issues. During long-term heat transfer, particulate matter and oily substances tend to adhere to the walls of the heat exchange tubes, and over time, a thick layer of dust and ash accumulates on the tube surface, making it difficult to clean. This leads to a decrease in the waste heat transfer conversion rate and poses a fire risk. Furthermore, when dealing with high waste gas production rates and rapid flow rates, the waste gas often retains some heat even after waste heat recovery treatment, resulting in poor recovery efficiency and low utilization rate. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a system for treating exhaust gas and recovering waste heat from a stenter.

[0004] To solve the above technical problems, the present invention adopts the following technical solution: A stenter exhaust gas treatment and waste heat recovery system includes a low-resistance venturi tube, a spray filtration system, and a heat exchange system connected in sequence. The inlet of the low-resistance venturi tube is connected to the exhaust gas outlet of the stenter, and the outlet of the low-resistance venturi tube is connected to the spray filtration system. The spray filtration system is used to remove oil fumes and dust from the exhaust gas by spraying circulating water containing nonionic surfactants and by changing the airflow. The spray filtration system is used to filter large particles of dust and oil fumes from the exhaust gas using porous lightweight packing and the spray system, and then inputs the filtered exhaust gas into the heat exchange system. The heat exchange system is used to exchange heat with the filtered exhaust gas. The spray filtration system is equipped with a suspension backwashing system. The suspension backwashing system is used to close the inlet of the low-resistance venturi tube and perform suspension backwashing on the porous lightweight packing of the spray filtration system when the air pressure difference between the inlet and outlet of the spray filtration system is less than a preset threshold. After a preset cleaning time, the inlet of the low-resistance venturi tube is opened.

[0005] Furthermore, the low-resistance venturi tube includes a contraction section, a throat, and a diffuser section arranged sequentially from top to bottom. The length and diameter of the contraction section, throat, and diffuser section are determined and adjusted according to the fiber, dust, and oil fume content in the exhaust gas of the stenter.

[0006] Furthermore, the spray filtration system includes a housing, and inside the housing, from top to bottom, are arranged a demisting wire mesh, a polygonal ball packing, an upper filter screen, a water spray system, a porous lightweight packing, and a lower filter screen. The upper end of the shell is connected to the heat exchange system inlet through the exhaust gas outlet. An air inlet is provided on the side of the shell below the lower filter screen. The air inlet is connected to the outlet of the low-resistance Venturi tube. A water spray system is provided on both the low-resistance Venturi tube and the upper part of the shell. The water spray system is used to spray water into the low-resistance Venturi tube and on the upper surface of the porous lightweight packing. The low-resistance Venturi tube is used to guide the sprayed exhaust gas to the lower filter screen. The water outlet at the lower end of the shell is connected to a water tank through a water pipe. The porous lightweight packing is used to filter the exhaust gas. The demisting wire mesh and the polygonal ball packing are both used for demisting. The upper filter screen is used to support the polygonal ball packing and limit the upward movement of the porous lightweight packing to its extreme position. A drain outlet is provided on one side of the shell of the porous lightweight packing material, and two inclined jet inlets are provided on both sides of the shell. The drain outlet is connected to a water tank through a water pipe, and the jet inlets are connected to the water tank through a suspension backwashing system. The jet inlets are used to spray water into the porous lightweight packing material to clean the pumice during backwashing and to make the water in the tower rotate. An overflow outlet is provided on the side of the shell above the upper filter screen, and the overflow outlet is connected to the water tank through a water pipe.

[0007] Furthermore, the heat exchange system includes a heat exchanger inlet pipe, a heat exchanger outlet pipe, a cooling water inlet, a cooling water outlet, a spray cleaning system, an inspection port, and a heat exchanger shell; the spray cleaning system is used to spray an aqueous solution of an alkaline nonionic surfactant into the cooling water inlet to clean the heat exchanger tubes, and the heat exchanger inlet pipe and the heat exchanger outlet pipe are located on the same side of the heat exchanger shell.

[0008] Furthermore, it also includes a pressure detection device, which is used to detect the pressure difference between the exhaust gas inlet and outlet of the waste heat recovery system. If the pressure difference exceeds a preset threshold, the exhaust gas inlet of the waste heat recovery system is closed, the inlet of the external exhaust gas treatment system is opened so that the exhaust gas outlet of the stenter is directly connected to the external exhaust gas treatment system, and the suspension backflushing system is started for cleaning. After a preset cleaning time, the exhaust gas inlet of the waste heat recovery system is automatically opened and the inlet of the external exhaust gas treatment system is closed.

[0009] Furthermore, valves are installed on the air intake pipe, the water pipe of the water spray system, the water pipe of the suspension backwash system, and each inlet and outlet of the shell.

[0010] Furthermore, the water spray system employs a volute nozzle.

[0011] Furthermore, an oil-removing agent spraying system is provided between the demisting wire mesh and the polygonal ball packing, the oil-removing agent spraying system being used to spray oil-removing agent onto the polygonal ball packing.

[0012] Compared with the prior art, the present invention, by adopting the above technical solution, has the following advantages: The spray filtration system with suspension backwashing of this invention first utilizes a spray system within a low-resistance venturi tube to remove most of the medium-length fibers, oil fumes, dust, etc. It then utilizes the different states of porous, lightweight, high-temperature resistant, and easy-to-clean materials in water during filtration and suspension backwashing. In a dense state, the packing filters dust and oil fumes. When the pressure difference within the equipment exceeds a certain value, the bypass exhaust gas is opened and directly enters the tail gas treatment system, while the valve entering the preheating and recovery system is closed. Simultaneously, the automatic backwashing system is activated. During backwashing, the porous, lightweight, high-temperature resistant, and easy-to-clean materials maintain their different states in water during filtration and backwashing. During normal filtration, the packing is in a dense state, filtering dust and oil fumes. During backwashing, the packing automatically suspends and disperses in water due to buoyancy. With the aid of an oil-washing agent, the suspended, rotating, and frictional backwashing process recovers oil sludge without the need for manual cleaning. The heat exchanger is designed to be cleanable. It uses heat exchange tubes with large tooth pitch and tube spacing. At the same time, a spray water washing device that is compatible with tooth pitch and tube spacing can automatically spray degreasing agent and hot water when the pressure difference increases, cleaning the oil and dust on the surface of the heat exchange tubes, avoiding blockage of the heat exchanger and reducing the decrease in heat exchange efficiency.

[0013] The stenter's flue gas is filtered through a spray filtration system to remove dust and oil fumes before entering the heat exchanger, solving the problems of heat exchanger blockage and fire. The spray filtration system is equipped with three sprays (low-resistance venturi tube pre-spray, sprayer spray, and natural spray formed by water leaking from the lower filter screen) and two filtration stages. Large dust and oil fumes are filtered by the packing material, while small dust and oil fumes are removed by a water curtain formed by circulating water. An automatic oil removal and cleaning system is also included. The water spray not only removes dust but also backwashes the filter media, reducing blockage. If blockage occurs, the packing material automatically disperses due to buoyancy in the water, and with the help of an oil-washing agent, the adhering dust and oil are removed through backwash water circulation, eliminating the need for manual cleaning.

[0014] High-humidity, hot gas (>90℃) after dust and fumes removal enters the heat exchanger for heat exchange, recovering heat energy while reducing the flue gas emission temperature. The recovered hot water (>60℃) meets production requirements; the flue gas temperature drops below 45℃. The inlet and outlet pipes of the heat exchanger are located on the same side of the heat exchanger shell, forming a U-shape. When cleaning is required, a cleaning solution can be added by spraying for soaking. Inspection ports are provided on the top and sides of the heat exchanger to observe the degree of cleaning. If cleaning is incomplete, manual intervention can be carried out through the inspection ports.

[0015] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the system principle of the present invention; Figure 2Schematic diagram of the spray filtration system.

[0017] The attached diagram lists the components represented by each number as follows: 1. Inlet pipe; 2. Low-resistance Venturi tube; 3. Shell; 4. Porous lightweight packing; 5. Water spray system; 6. Suspension backwash system; 7. Water tank; 8. Polygonal spherical packing; 9. Demisting mesh; 10. Exhaust gas outlet; 11. Heat exchanger inlet pipe; 12. Heat exchanger outlet pipe; 13. Cooling water inlet; 14. Cooling water outlet Detailed Implementation

[0018] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0019] like Figure 1 As shown, a stenter exhaust gas treatment and waste heat recovery system includes a low-resistance venturi tube, a spray filtration system, and a heat exchange system connected in sequence. The inlet of the low-resistance venturi tube is connected to the exhaust gas outlet of the stenter, and the outlet of the low-resistance venturi tube is connected to the spray filtration system. The spray filtration system is used to remove oil fumes and dust from the exhaust gas by spraying circulating water containing nonionic surfactants and by changing the airflow. The spray filtration system is used to filter large particles of dust and oil fumes from the exhaust gas using porous lightweight packing and the spray system, and then inputs the filtered exhaust gas into the heat exchange system. The heat exchange system is used to exchange heat with the filtered exhaust gas. The spray filtration system is equipped with a suspension backwashing system. The suspension backwashing system is used to close the inlet of the low-resistance venturi tube and perform suspension backwashing on the porous lightweight packing of the spray filtration system when the air pressure difference between the inlet and outlet of the spray filtration system is less than a preset threshold. After a preset cleaning time, the inlet of the low-resistance venturi tube is opened.

[0020] The low-resistance venturi tube 2 is used to guide the sprayed exhaust gas below the lower filter screen. The water outlet at the lower end of the housing 3 is connected to the water tank 7 through a water pipe. A water spray system 5 is provided on both the low-resistance venturi tube and the upper part of the housing 3. The water spray system 5 is used to spray water into the low-resistance venturi tube and on the upper surface of the porous lightweight packing 4. The porous lightweight packing 4 is used to filter the exhaust gas. The demisting wire mesh 9 and the polygonal ball packing 8 are both used for demisting. The upper filter screen is used to support the polygonal ball packing 8 and limit the upward movement of the porous lightweight packing 4 to its limit position. A drain outlet is provided on one side of the shell 3 of the porous lightweight packing 4, and two inclined jet inlets are provided on both sides of the shell 3. The drain outlet is connected to the water tank 7 through a water pipe, and the jet inlets are connected to the water tank 7 through a suspension backwashing system 6. The jet inlets are used to spray water into the porous lightweight packing 4 to clean the pumice during backwashing and to make the water in the tower rotate. An overflow outlet is provided on the side of the shell 3 above the upper filter screen, and the overflow outlet is connected to the water tank 7 through a water pipe.

[0021] In one embodiment, the heat exchange system includes a heat exchanger inlet pipe, a heat exchanger outlet pipe 2, a cooling water inlet 3, a cooling water outlet 4, a spray cleaning system, an inspection port 5, and a heat exchanger shell 6; the spray cleaning system is used to spray an aqueous solution of an alkaline nonionic surfactant into the cooling water inlet 3 to clean the heat exchanger tubes, and the heat exchanger inlet pipe and the heat exchanger outlet pipe 2 are located on the same side of the heat exchanger shell 6.

[0022] As one implementation method, a pressure detection device is also included. The pressure detection device is used to detect the pressure difference between the exhaust gas inlet and exhaust gas outlet of the waste heat recovery system. If the pressure difference exceeds a preset threshold, the exhaust gas inlet of the waste heat recovery system is closed, the inlet of the external exhaust gas treatment system is opened so that the exhaust gas outlet of the stenter is directly connected to the external exhaust gas treatment system, and the suspension backflushing system is started for cleaning. After a preset cleaning time, the exhaust gas inlet of the waste heat recovery system is automatically opened and the inlet of the external exhaust gas treatment system is closed.

[0023] As one implementation method, valves are provided on the air intake pipe, the water pipe of the water spray system 5, the water pipe of the suspension backwash system 6, and each inlet and outlet of the housing 3.

[0024] In one implementation, the water spray system employs a volute nozzle.

[0025] In one embodiment, an oil-removing agent spraying system is provided between the demisting wire mesh 9 and the polygonal ball packing 8, and the oil-removing agent spraying system is used to spray oil-removing agent onto the polygonal ball packing 8.

[0026] The workflow of this invention is as follows: During normal operation, the exhaust gas from the stenter passes through a low-resistance venturi tube spray filter for preliminary oil removal before entering the spray filtration system heat exchanger. The spray filtration system removes dust and oil fumes before entering the heat exchanger, addressing the issues of clogging and fire hazards. The spray filtration system features three spray stages (pre-spray from the low-resistance venturi tube, spray from the sprayer, and natural spray formed by water leaking from the lower filter screen) and two filtration stages. Large dust and oil fumes are filtered by packing material, while a water curtain formed by circulating water removes smaller dust and oil fumes. The high-humidity, hot gas (>90℃) after dust and oil fume removal enters the heat exchanger for water-gas heat exchange, recovering heat energy while reducing the exhaust gas temperature. The recovered hot water (>60℃) meets production requirements, and the exhaust gas temperature drops below 45℃.

[0027] When the device needs to be cleaned after a period of use, the suspension backwashing system in the spray filtration system will automatically start according to the pressure difference setting to rinse the porous lightweight packing. During backwashing, the packing will automatically disperse due to the buoyancy of the packing in the water. With the help of the oil washing agent, the backwashing will be suspended and the oil sludge will be recovered. No manual cleaning is required. The upper filter screen can limit the porous lightweight packing. When the water is higher than the overflow port, it can flow out to the water tank to prevent overflow.

[0028] The above description provides examples of the preferred embodiments of the present invention. Parts not detailed herein are common knowledge to those skilled in the art. The scope of protection of the present invention is determined by the claims. Any equivalent modifications based on the technical teachings of the present invention are also within the scope of protection of the present invention.

Claims

1. A system for treating exhaust gas and recovering waste heat from a stenter, characterized in that, The system includes a low-resistance venturi tube, a spray filtration system, and a heat exchange system connected in sequence. The inlet of the low-resistance venturi tube is connected to the exhaust outlet of the stenter, and the outlet of the low-resistance venturi tube is connected to the spray filtration system. The spray filtration system removes oil fumes and dust from the exhaust gas by spraying circulating water containing nonionic surfactants and by changing the airflow. The spray filtration system uses porous lightweight packing and the spray system to filter large particles of dust and oil fumes from the exhaust gas and inputs the filtered exhaust gas into the heat exchange system. The heat exchange system is used to exchange heat with the filtered exhaust gas. The spray filtration system is equipped with a suspension backwashing system. The suspension backwashing system closes the inlet of the low-resistance venturi tube and performs suspension backwashing on the porous lightweight packing of the spray filtration system when the air pressure difference between the inlet and outlet of the spray filtration system is less than a preset threshold. After a preset cleaning time, the inlet of the low-resistance venturi tube is opened.

2. The stenter exhaust gas treatment and waste heat recovery system according to claim 1, characterized in that, The low-resistance venturi tube (2) includes a contraction section, a throat, and a diffusion section arranged sequentially from top to bottom. The length and diameter of the contraction section, throat, and diffusion section are determined and adjusted according to the fiber, dust, and oil fume content in the exhaust gas of the stenter.

3. The stenter exhaust gas treatment and waste heat recovery system according to claim 1, characterized in that, The spray filtration system includes a housing, and inside the housing (3) are arranged from top to bottom a demisting wire mesh (9), a polygonal ball packing (8), an upper filter screen, a water spray system (5), a porous lightweight packing (4), and a lower filter screen; The upper end of the shell (3) is connected to the heat exchange system inlet through the exhaust gas outlet (10). An air inlet is provided on the side of the shell (3) below the lower filter screen. The air inlet is connected to the outlet of the low-resistance venturi tube. A water spray system (5) is provided above the low-resistance venturi tube and the shell (3). The water spray system (5) is used to spray water into the low-resistance venturi tube and on the upper surface of the porous lightweight packing (4). The low-resistance venturi tube is used to guide the exhaust gas after spraying into the lower filter screen. The water outlet at the lower end of the shell (3) is connected to the water tank (7) through a water pipe. The porous lightweight packing (4) is used to filter the exhaust gas. The demisting wire mesh (9) and the polygonal ball packing (8) are both used for demisting. The upper filter screen is used to support the polygonal ball packing (8) and limit the upward movement of the porous lightweight packing (4) to the limit position. A drain outlet is provided on one side of the shell (3) of the porous lightweight packing (4), and two inclined jet inlets are provided on the shells (3) on both sides. The drain outlet is connected to the water tank (7) through a water pipe, and the jet inlets are connected to the water tank (7) through a suspension backwashing system (6). The jet inlets are used to spray water into the porous lightweight packing (4) to clean the pumice during backwashing and to make the water in the tower rotate. An overflow outlet is provided on the side of the shell (3) above the upper filter screen, and the overflow outlet is connected to the water tank (7) through a water pipe.

4. The stenter exhaust gas treatment and waste heat recovery system according to claim 1, characterized in that, The heat exchange system includes a heat exchanger inlet pipe (11), a heat exchanger outlet pipe (12), a cooling water inlet (13), a cooling water outlet (14), a spray cleaning system, an inspection port (15), and a heat exchanger shell (16). The spray cleaning system is used to spray an aqueous solution of an alkaline nonionic surfactant into the cooling water inlet (13) to clean the heat exchanger tubes. The heat exchanger inlet pipe (11) and the heat exchanger outlet pipe (12) are located on the same side of the heat exchanger shell (16).

5. The stenter exhaust gas treatment and waste heat recovery system according to claim 1, characterized in that, It also includes a pressure detection device, which is used to detect the pressure difference between the exhaust gas inlet and outlet of the waste heat recovery system. If the pressure difference exceeds a preset threshold, the exhaust gas inlet of the waste heat recovery system is closed, the inlet of the external exhaust gas treatment system is opened so that the exhaust gas outlet of the stenter is directly connected to the external exhaust gas treatment system, and the suspension backflushing system is started for cleaning. After a preset cleaning time, the exhaust gas inlet of the waste heat recovery system is automatically opened and the inlet of the external exhaust gas treatment system is closed.

6. The stenter exhaust gas treatment and waste heat recovery system according to any one of claims 3 or 4, characterized in that, Valves are installed at each inlet and outlet of the air inlet pipe (1), the water pipe of the water spray system (5), the water pipe of the suspension backwash system (6), and the shell (3).

7. The stenter exhaust gas treatment and waste heat recovery system according to claim 4, characterized in that, The water spray system uses a spiral nozzle.

8. The stenter exhaust gas treatment and waste heat recovery system according to claim 2, characterized in that, An oil-removing agent spraying system is provided between the demisting wire mesh (9) and the polygonal ball packing (8), and the oil-removing agent spraying system is used to spray oil-removing agent onto the polygonal ball packing (8).

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