A drying machine steam supply device and process based on dry tail gas waste heat

Abstract

This invention discloses a steam supply device and process for a dryer based on the waste heat of the drying exhaust gas, belonging to the field of steam supply technology for dryers. It includes a dust collector connected to the exhaust gas discharge pipe of the dryer, a heat exchange component on one side of the dust collector, and a heat exchanger connected to the dust collector. The exhaust gas treated by the dust collector exchanges heat with water through an inlet pipe installed on the heat exchanger. A circulating water tank connected to the heat exchanger is installed on one side of the dust collector. Through the heat exchange component, heat pump, and flow control component, the heat of water vapor in the drying exhaust gas is recovered to heat the circulating water. The circulating water is used as the heat source of the heat pump to generate steam above 140°C for the dryer, greatly saving operating costs by more than 40% compared to traditional methods. Furthermore, the condensate from the dryer is discharged into a hot water tank through a drain pipe and a steam trap, and is recycled as a heat source medium for the dryer.

Description

Technical Field

[0001] This invention relates to the field of steam supply technology for dryers, and more particularly to a steam supply device and process for dryers based on the waste heat of the dryer exhaust gas. Background Technology

[0002] In the sludge drying process, wet sludge with high water content is passed through a dryer. Under the heating of a heat source, the water and organic matter in the wet sludge are heated to produce water vapor containing a small amount of volatile organic compounds, which is called drying waste steam or drying tail gas. It is discharged from the exhaust gas outlet of the dryer, and the dried sludge is discharged from the sludge outlet to achieve sludge drying.

[0003] Conventional sludge dryers use purchased steam, natural gas boilers, or electric boilers to generate steam. The steam is used to release heat in the dryer to dry the moisture in the sludge. This type of steam source is expensive (for example, purchased steam costs about 250 yuan / ton). In conventional technology, the drying exhaust gas is directly condensed, and the condensate is sent to the water treatment system, while the non-condensable gas is sent to the exhaust gas treatment device. A large amount of latent heat contained in the water vapor in the drying exhaust gas is not effectively recovered, resulting in significant waste. Summary of the Invention

[0004] The purpose of this invention is to address the problem that the latent heat of vaporization of a large amount of water vapor is not effectively recovered when the dried exhaust gas is directly condensed and sent to the water treatment system and exhaust gas treatment system in conventional technology. Therefore, this invention proposes a steam supply device and process for a dryer based on the waste heat of the dried exhaust gas.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A steam supply device for a dryer based on the waste heat of the dryer exhaust gas includes a dust collector connected to the exhaust gas discharge pipe of the dryer. A heat exchange component is provided on one side of the dust collector. The heat exchange component includes a heat exchanger connected to the dust collector. The exhaust gas treated by the dust collector exchanges heat with water through an air inlet pipe installed on the heat exchanger. A circulating water tank connected to the heat exchanger is installed on one side of the dust collector.

[0007] A heat pump is installed on one side of the circulating water tank. The hot water after heat exchange is sent into the heat pump by the circulating pump installed on the circulating water tank as a heat source to generate steam for the dryer.

[0008] As a further description of the above technical solution:

[0009] The output end of the heat pump is connected to a steam compressor, and the output end of the steam compressor is connected to the steam inlet of the dryer through the installation of a flow control component.

[0010] As a further description of the above technical solution:

[0011] The flow control assembly includes a bracket and a control box mounted on the bracket. A motor with its output end connected to the valve seat is installed on the top of the control box.

[0012] As a further description of the above technical solution:

[0013] The valve seat has an L-shaped channel and a V-shaped channel. At the center of the valve seat, there is a confluence channel that connects to the L-shaped channel and the V-shaped channel. The outlet end of the confluence channel is connected to a conveying pipe that is connected to the steam inlet of the dryer through a rotary joint.

[0014] As a further description of the above technical solution:

[0015] The control box has two inlets connected to an L-shaped channel on its inner wall, and the output end of the steam compressor is connected to one of the inlets through a first air supply pipe, while a second air supply pipe is installed in the other inlet.

[0016] As a further description of the above technical solution:

[0017] The condensate outlet of the dryer is connected to a hot water tank via a drain pipe, and the hot water tank is connected to a heat pump via a water supply pipe.

[0018] As a further description of the above technical solution:

[0019] One end of the heat pump is connected to the heat exchanger via a heat source return water pipe, and the output end of the circulating pump is connected to the heat pump via a heat source supply water pipe.

[0020] A steam supply process for a dryer based on waste heat from the drying exhaust gas includes the following steps:

[0021] S1. The dryer uses saturated steam as a heat source to indirectly contact the sludge to achieve the effect of drying the sludge. During this process, the water in the sludge is evaporated into water vapor to form drying exhaust gas.

[0022] S2. The temperature of the drying exhaust gas discharged from the dryer is 100℃. After the exhaust gas is removed by the dust collector, it exchanges heat with water through the heat exchanger.

[0023] S3. After heat exchange, the hot water flows into the circulating water tank and is then pumped into the heat pump as a heat source to produce 140-180℃ steam as a heat source for the dryer. In this process, the heat pump can directly produce 140-150℃ steam or 100-130℃ steam, which is then heated and pressurized to 150-180℃ by the steam compressor.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] By setting up heat exchange components, heat pumps, and flow control components, the heat of water vapor in the drying exhaust gas is recovered (about 80% of the heat of the steam entering the dryer enters the evaporated exhaust gas, which has great recovery value). This heats the circulating water and uses the circulating water as the heat source of the heat pump to generate steam above 140°C for the dryer, which greatly saves operating costs, saving more than 40% compared to the traditional method.

[0026] Furthermore, the condensate from the dryer is discharged into the hot water tank through the drain pipe and steam trap, and is recycled as a drying medium, which improves energy utilization efficiency.

[0027] Meanwhile, by adjusting the L-shaped and V-shaped channels of the valve seat, five mixing modes of purchased steam and heat pump steam (purchased only / heat pump only / mixed ratio, etc.) can be achieved to adapt to the dynamic demand when the heat pump capacity fluctuates. Attached Figure Description

[0028] Figure 1 A schematic diagram of the overall state from a first perspective provided according to an embodiment of the present invention is shown;

[0029] Figure 2 A second-view schematic diagram of the overall state provided according to an embodiment of the present invention is shown;

[0030] Figure 3 A schematic diagram of the overall structure of a flow control component provided according to an embodiment of the present invention is shown;

[0031] Figure 4 A schematic diagram of the internal structure of a valve seat provided according to an embodiment of the present invention is shown;

[0032] Figure 5 A schematic diagram of the control box provided according to an embodiment of the present invention is shown;

[0033] Figure 6 A schematic diagram of the overall state from a top-down perspective provided according to an embodiment of the present invention is shown;

[0034] Figure 7 A first example flowchart provided according to an embodiment of the present invention is shown;

[0035] Figure 8 A schematic diagram showing the L-shaped channel fully connected to the inlet according to an embodiment of the present invention is shown;

[0036] Figure 9 A schematic diagram showing the L-shaped channel and the inlet semi-connection provided according to an embodiment of the present invention is shown;

[0037] Figure 10 A schematic diagram showing the V-shaped channel fully connected to one of the inlets according to an embodiment of the present invention is shown;

[0038] Figure 11 A schematic diagram showing the V-shaped channel connected to two inlets according to an embodiment of the present invention is shown;

[0039] Figure 12 A schematic diagram showing the V-shaped channel fully connected to another inlet according to an embodiment of the present invention is shown;

[0040] Figure 13 A second example flowchart provided according to an embodiment of the present invention is shown.

[0041] Legend:

[0042] 10. Dust collector;

[0043] 20. Heat exchange components; 21. Heat exchanger; 22. Circulating water tank; 23. Air inlet pipe; 24. Circulating pump;

[0044] 30. Heat pump; 31. Steam compressor;

[0045] 40. Flow control assembly; 41. Bracket; 42. Control box; 43. Valve seat; 44. L-shaped channel; 45. V-shaped channel; 46. Converging channel; 47. Delivery pipe; 48. Motor;

[0046] 50. Hot water tank; 51. Drain pipe. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0048] like Figure 1 - Figure 13 As shown, the present invention provides:

[0049] A steam supply device for a drying machine based on the waste heat of drying exhaust gas includes a dust collector 10 connected to the exhaust gas discharge pipe of the drying machine. Preferably, the dust collector 10 is a water film dust collector. The drying machine is a disc drying machine, a paddle drying machine, or a thin-layer drying machine. In use, the drying machine uses saturated steam as a heat source to indirectly contact the sludge to achieve the effect of drying the sludge. During this process, the moisture in the sludge is evaporated into water vapor to form drying exhaust gas. The temperature of the drying exhaust gas discharged by the drying machine is about 100°C (most of which is water vapor, and a small amount is air and odorous gases emitted by the sludge). The drying exhaust gas needs to be dusted by the dust collector 10 first. While the dust collector 10 removes dust, it can also maintain the temperature of the exhaust gas and prevent condensation.

[0050] In order to use the treated exhaust gas for heat exchange, a heat exchange assembly 20 is provided on one side of the dust collector 10. The heat exchange assembly 20 includes a heat exchanger 21 connected to the dust collector 10. The exhaust gas treated by the dust collector 10 exchanges heat with water through the air inlet pipe 23 installed on the heat exchanger 21. A circulating water tank 22 connected to the heat exchanger 21 is installed on one side of the dust collector 10.

[0051] like Figure 1 , Figure 2 , Figure 6 and Figure 7 As shown, in order to use the hot water after heat exchange as a heat source to produce steam, a heat pump 30 is provided on one side of the circulating water tank 22. The hot water after heat exchange is sent into the heat pump 30 by the circulating pump 24 installed on the circulating water tank 22 as a heat source to produce steam for the dryer.

[0052] Specifically, the condensate outlet of the dryer is connected to a hot water tank 50 via a drain pipe 51. Preferably, a steam trap is installed on the drain pipe 51, which automatically removes steam condensate and non-condensable gases such as air from the drain pipe 51 without leaking steam.

[0053] The hot water tank 50 is connected to the heat pump 30 through a water supply pipe. Meanwhile, one end of the heat pump 30 is connected to the heat exchanger 21 through a heat source return water pipe, and the output end of the circulating pump 24 is connected to the heat pump 30 through a heat source supply water pipe.

[0054] The output of heat pump 30 is connected to steam compressor 31. Specifically, the exhaust gas, after dust removal (dust content less than 20 mg / Nm³), 3 The water undergoes heat exchange with heat exchanger 21, and the hot water after heat exchange flows into circulating water tank 22 and is then sent by circulating pump 24 to heat pump 30 as a heat source to produce 140-180℃ steam as a heat source for the dryer (at this time, the COP of heat pump 30 can reach 2.13 or above). It is worth noting that in this process, heat pump 30 can directly produce 140-150℃ steam or 100-130℃ steam, which is then heated and pressurized to 150-180℃ by steam compressor 31.

[0055] It should be noted that the dotted line in the flowchart represents the circulation of low-temperature hot water entering heat exchanger 21, heating up, and then entering heat pump 30. After releasing heat and cooling down at the cold end, it re-enters heat exchanger 21, forming a cycle. The dashed line represents the circulation of steam generated by heat pump 30, which releases heat and condenses into water in the dryer before being sent back to heat pump 30 to generate steam. Heat pump 30 transfers the heat absorbed at the cold end from heat exchanger 21 to the hot end to generate steam, which is then provided as a heat source to the dryer.

[0056] like Figure 1 , Figure 3 , Figure 4 and Figure 5As shown, in order to control the steam flow rate into the dryer, the output end of the steam compressor 31 is connected to the steam inlet end of the dryer by installing a flow control component 40.

[0057] The flow control assembly 40 includes a bracket 41 and a control box 42 mounted on the bracket 41. In particular, the control box 42 includes a box body with a sealing cover installed on the box body. A valve seat 43 is rotatably connected inside the control box 42. Preferably, the valve seat 43 is composed of an upper seat body and a lower seat body spliced ​​together. A motor 48 with an output end connected to the valve seat 43 is installed on the top of the control box 42.

[0058] like Figure 8 - Figure 12 As shown, an L-shaped channel 44 and a V-shaped channel 45 are provided inside the valve seat 43. A confluence channel 46 connected to the L-shaped channel 44 and the V-shaped channel 45 is provided at the center of the valve seat 43. The outlet end of the confluence channel 46 is connected to a conveying pipe 47, one end of which is connected to the steam inlet end of the dryer, through a rotary joint.

[0059] The control box 42 has two inlets on its inner wall that are connected to the L-shaped channel 44. The output end of the steam compressor 31 is connected to one of the inlets through the first air supply pipe. The other inlet is equipped with a second air supply pipe. Preferably, both the first and second air supply pipes are equipped with solenoid valves. The valve seat 43 is used to control the amount of external steam and heat pump 30 steam supplied into the confluence channel 46 when the solenoid valve is open. This enables five different scenarios: the amount of external steam supplied is the same as the amount of heat pump 30 steam supplied; the amount of external steam supplied is greater than the amount of heat pump 30 steam supplied; the amount of external steam supplied is less than the amount of heat pump 30 steam supplied; only external steam is supplied; or only heat pump 30 steam is supplied.

[0060] Specifically, the second steam supply pipe is used to transport external steam (specifically, purchased steam, steam generated by an electric boiler, or steam generated by a gas boiler). In particular, the two inlets are also arranged in an L-shape and can be connected to the L-shaped channel 44. At the same time, when the L-shaped channel 44 is fully connected to the two inlets, when the valve seat 43 is driven by the motor 48 to rotate counterclockwise or clockwise, the connection state between the two ports of the L-shaped channel 44 and the two inlets remains the same. It is worth noting that the rotation angle must be less than 30°.

[0061] When the counterclockwise rotation exceeds 30°, one end of the V-shaped channel 45 will gradually rotate to connect with the second air supply pipe. When the V-shaped channel 45 is fully connected with the second air supply pipe, the first air supply pipe is not connected to the port of any channel. In this state, only external steam can enter the valve seat 43.

[0062] When the valve seat 45 continues to rotate counterclockwise, the other end of the V-shaped channel 45 will begin to connect with the first container pipe, and the degree of connection will gradually increase. During this process, the degree of connection between the V-shaped channel 45 and the second gas supply pipe will gradually decrease. When it is fully connected with the first gas supply pipe, the second gas supply pipe will not connect with any port of the channel. This allows for five different scenarios to be achieved by rotating the valve seat 43 to different angles: the external steam supply is the same as the steam supply of the heat pump 30, the external steam supply is greater than the steam supply of the heat pump 30, the external steam supply is less than the steam supply of the heat pump 30, only external steam is supplied, or only the steam supply of the heat pump 30 is supplied. These scenarios are designed to meet different steam supply requirements. It is particularly important to note that when the steam supply of the heat pump 30 cannot meet the supply demand, the ratio of the external steam supply to the steam supply of the heat pump 30 needs to be adjusted.

[0063] Finally, it should be noted that during use, the condensate from the dried exhaust gas must be treated to meet standards before being discharged (not shown in the figure), and the non-condensable gas must be treated to meet standards before being discharged.

[0064] Specifically, the steam supply device for this dryer, based on the waste heat from the drying exhaust gas, operates as follows:

[0065] 1. Exhaust gas treatment stage: The 100℃ exhaust gas (containing 95% water vapor + 5% air / odor gas) discharged from the dryer enters the dust collector 10 for dust removal, maintaining the temperature to prevent condensation, and reducing the dust content to <20mg / Nm³.

[0066] 2. Heat exchange and recovery stage: The exhaust gas after dust removal enters the heat exchanger 21 through the air inlet pipe 23 and exchanges heat with the circulating water. The hot water flows into the circulating water tank 22 and is transported to the heat pump 30 by the circulating pump 24 as a heat source.

[0067] 3. Steam generation stage: Heat pump 30 uses the heat of circulating water to generate steam at 100-150℃. If higher parameters are required, the steam is pressurized to above 150℃ by steam compressor 31 and delivered to flow control component 40.

[0068] 4. Flow regulation stage: The valve seat 43 is rotated by the motor 48 to adjust the connection between the L-shaped channel 44 and the V-shaped channel 45.

[0069] Rotate counterclockwise <30°: L-shaped channel 44 connects the first gas supply pipe (heat pump steam) and the second gas supply pipe (purchased steam) to achieve mixing ratio;

[0070] Rotate counterclockwise >30°: The V-shaped channel 45 is gradually connected to the second gas supply pipe, enabling the supply of only externally purchased steam;

[0071] Continue rotating until the V-shaped channel 45 is fully connected to the first gas supply pipe: achieving heat pump steam supply only;

[0072] 5. Steam supply stage: The regulated steam is sent to the dryer through the conveying pipe 47, and serves as a heat source to indirectly contact the sludge to achieve drying.

[0073] 6. Condensate circulation stage: The condensate from the dryer is discharged into the hot water tank 50 through the drain pipe 51 and the steam trap, and is used as a heat source medium for the dryer in a circulating manner, which reduces the consumption of softened water and improves energy utilization efficiency.

[0074] 7. Emission treatment stage: The exhaust gas condensate is treated by the water treatment system to meet the standards before being discharged, and the non-condensable gas is purified by the exhaust gas treatment device before being discharged to ensure environmental compliance.

[0075] A steam supply process for a dryer based on waste heat from the drying exhaust gas includes the following steps:

[0076] S1. The dryer uses saturated steam as a heat source to indirectly contact the sludge to achieve the effect of drying the sludge. During this process, the water in the sludge is evaporated into water vapor to form drying exhaust gas.

[0077] S2. The temperature of the drying exhaust gas discharged from the dryer is 100℃. After the exhaust gas is removed by the dust collector 10, it exchanges heat with water through the heat exchanger 21.

[0078] S3. After heat exchange, the hot water flows into the circulating water tank 22 and is then sent by the circulating pump 24 to the heat pump 30 as a heat source to produce 140-180℃ steam as a heat source for the dryer. In this process, the heat pump 30 can directly produce 140-150℃ steam or 100-130℃ steam, which is then heated and pressurized to 150-180℃ by the steam compressor 31.

[0079] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A steam supply device for a dryer based on waste heat from the dryer exhaust gas, comprising a dust collector (10) connected to the exhaust gas discharge pipe of the dryer, characterized in that, A heat exchange assembly (20) is provided on one side of the dust collector (10). The heat exchange assembly (20) includes a heat exchanger (21) connected to the dust collector (10). The exhaust gas treated by the dust collector (10) exchanges heat with water through an air inlet pipe (23) installed on the heat exchanger (21). A circulating water tank (22) connected to the heat exchanger (21) is installed on one side of the dust collector (10). A heat pump (30) is provided on one side of the circulating water tank (22). The hot water after heat exchange is sent into the heat pump (30) by the circulating pump (24) installed on the circulating water tank (22) as a heat source to generate steam for supplying the dryer. The output end of the heat pump (30) is connected to a steam compressor (31), and the output end of the steam compressor (31) is connected to the steam inlet of the dryer through a flow control assembly (40). The flow control assembly (40) includes a bracket (41) and a control box (42) mounted on the bracket (41). A motor (48) with its output end connected to the valve seat (43) is installed on the top of the control box (42). The valve seat (43) is provided with an L-shaped channel (44) and a V-shaped channel (45). The valve seat (43) is provided with a confluence channel (46) at the center, which is connected to the L-shaped channel (44) and the V-shaped channel (45). The outlet end of the confluence channel (46) is connected to a conveying pipe (47) with one end connected to the steam inlet end of the dryer through a rotary joint. The control box (42) has two inlets connected to the L-shaped channel (44) on its inner wall, and the output end of the steam compressor (31) is connected to one of the inlets through the first gas supply pipe, and the other inlet is equipped with a second gas supply pipe.

2. The steam supply device for a dryer based on waste heat from drying exhaust gas according to claim 1, characterized in that, The condensate outlet of the dryer is connected to a hot water tank (50) via a drain pipe (51), and the hot water tank (50) is connected to a heat pump (30) via a water supply pipe.

3. A steam supply device for a dryer based on waste heat from drying exhaust gas according to claim 2, characterized in that, One end of the heat pump (30) is connected to the heat exchanger (21) through a heat source return water pipe, and the output end of the circulating pump (24) is connected to the heat pump (30) through a heat source supply water pipe.

4. The steam supply process of a steam supply device for a dryer based on waste heat from drying exhaust gas according to any one of claims 1-3, characterized in that, Includes the following steps: S1. The dryer uses saturated steam as a heat source to indirectly contact the sludge to achieve the effect of drying the sludge. During this process, the water in the sludge is evaporated into water vapor to form drying exhaust gas. S2. The temperature of the drying exhaust gas discharged from the dryer is 100℃. After the exhaust gas is cleaned by the dust collector (10), it exchanges heat with water through the heat exchanger (21). S3. After heat exchange, the hot water flows into the circulating water tank (22) and is then sent by the circulating pump (24) to the heat pump (30) as a heat source to produce 140-180℃ steam as a heat source for the dryer. In this process, the heat pump (30) directly produces 140-150℃ steam, which is then heated and pressurized to 150-180℃ by the steam compressor (31).

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