A device for treating papermaking tail gas and a method for treating tail gas

Abstract

The technical solution of the present invention is implemented as follows: A treatment device for papermaking exhaust gas is installed on a drying cylinder, including an intake pipeline connected to the drying cylinder for inputting hot gas into the drying cylinder; an exhaust pipeline connected to the drying cylinder for discharging the exhaust gas of the drying cylinder; a first heat exchange mechanism for preheating the gas in the intake pipeline through the exhaust gas; and an exhaust gas recovery mechanism for heating the exhaust gas discharged from the exhaust pipeline and then re-transporting it into the drying cylinder; a concentration detection mechanism for detecting the concentration of impurities in the exhaust gas, and selecting to transport the exhaust gas to the first heat exchange mechanism when the impurities are high, and selecting to transport the exhaust gas to the exhaust gas recovery mechanism when the impurity concentration is low; wherein, the first heat exchange mechanism includes a first heat exchange box installed on the intake pipeline and communicating with the intake pipeline; a first preheating pipe spirally wound and arranged in the first heat exchange box and communicating with the exhaust pipeline; The beneficial effects of the present invention are: recycling the exhaust gas, saving energy and resources, and ensuring stable input of the intake air for drying.

Description

Technical Field

[0001] The present invention relates to the technical field of tail gas treatment, and in particular to a treatment device for papermaking tail gas and a method for treating the tail gas. Background Art

[0002] With the development of the paper industry, people's lives are increasingly inseparable from paper products, which provide great help in people's lives. However, a large amount of waste gas is generated during the papermaking process. If directly discharged into the atmosphere, it will affect air quality. Therefore, there is the birth of waste gas purification devices for papermaking.

[0003] During the papermaking process, a lot of tail gas is generated. For example, the patent publication number CN104727181B discloses a tail gas recovery mechanism for treating the tail gas of a papermaking drying cylinder. It preheats the gas filled in the drying cylinder through the generated tail gas, achieving the full utilization of the tail gas. However, the tail gas used for preheating is still discharged and cannot be recycled, which is not environmentally friendly and the energy is not fully utilized. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a treatment device for papermaking tail gas and a method for treating the tail gas to solve the problems in the above background art.

[0005] The technical solution of the present invention is realized as follows: A treatment device for papermaking tail gas is installed on a drying cylinder, and is characterized in that: it includes an intake pipeline connected to the drying cylinder for inputting hot gas into the drying cylinder; an exhaust pipeline connected to the drying cylinder for discharging the tail gas of the drying cylinder; a first heat exchange mechanism for preheating the gas in the intake pipeline through the tail gas; and a tail gas recovery mechanism for heating the tail gas discharged from the exhaust pipeline and then re-transporting it into the drying cylinder; a concentration detection mechanism for detecting the concentration of impurities in the tail gas. When the impurities are high, the tail gas is selected to be transported to the first heat exchange mechanism, and when the impurity concentration is low, the tail gas is selected to be transported to the tail gas recovery mechanism; wherein, the first heat exchange mechanism includes a first heat exchange box installed on the intake pipeline and communicating with the intake pipeline; a first preheating pipe spirally wound and arranged in the first heat exchange box and communicating with the exhaust pipeline.

[0006] Preferably: The tail gas recovery mechanism includes a recovery pipeline, and a temperature measuring instrument is installed on the recovery pipeline; a heating device is installed on the recovery pipeline; the heating device includes a first box body, and a heating component for heating the gas is arranged therein. The first box body is provided with a feed pipe and a discharge pipe; a switching valve for controlling the communication state between the recovery pipeline and the first box body; a partition plate vertically arranged in the first box body, dividing the interior of the first box body into left and right two cavities. An air passing groove is opened at the bottom of the partition plate; a first piston is arranged in the cavity on the left side of the partition plate, a first spring is arranged at the bottom of the first piston, and the heating component is arranged at the upper end of the first piston.

[0007] Preferably, the tail gas recovery mechanism includes a recovery pipeline, on which a thermometer is installed; a heating device installed on the recovery pipeline; the heating device includes a second box body, inside which a heating component for heating gas and liquid is provided, the heating component is spirally arranged on the inner wall of the second box body, the second box body is filled with liquid, the second box body is provided with a feed pipe and a discharge pipe, and one end of the discharge pipe extends downward to the bottom inside the second box body; a switching valve for controlling the communication state between the recovery pipeline and the first box body; and a second heat exchange mechanism arranged on the intake pipeline, which can hold the liquid in the second box body and preheat the gas in the intake pipeline through the high-temperature liquid.

[0008] Preferably, the second heat exchange mechanism includes a second heat exchange box, inside which a plurality of preheating channels are vertically arranged, and the preheating channels are communicated with the inside of the second box body; a second preheating pipe wound around each preheating channel, and the second preheating pipe is communicated with the intake pipeline; a return pipe connecting the bottom of the preheating channel and the second box body, and an electromagnetic valve is arranged on the return pipe; a water level sensor installed on the second box body for detecting the water level in the second box body, which is arranged at the same height as the bottom of the feed pipe, and the water level sensor is electrically connected to the electromagnetic valve.

[0009] Preferably, a transition bin is arranged between the second heat exchange box and the recovery pipeline, the recovery pipeline is communicated with the top of the transition bin, and the second heat exchange box is communicated with the bottom of the transition bin.

[0010] Preferably, a temperature control mechanism is arranged at one end of the recovery pipeline close to the drying cylinder, and the temperature control mechanism includes an electric heating pipe arranged on the recovery pipeline; a cold gas storage tank filled with cold gas and communicated with the recovery pipeline; a temperature control valve, and the cold gas storage tank is communicated with the recovery pipeline through the temperature control valve, and the opening and closing of the cold gas storage tank and the cold gas delivery amount are controlled.

[0011] Preferably, the temperature control valve includes a valve body, on which a first valve port, a second valve port and a third valve port are arranged, the first valve port and the second valve port are set as input valve ports, the third valve port is set as an output valve port, the first valve port and the third valve port are communicated with the recovery pipeline, and the second valve port is communicated with the cold gas storage tank; a mounting bracket fixed inside the valve body; a temperature sensing element installed on the mounting bracket and located inside the third valve port; a valve core sliding sleeve connected to the temperature sensing element through a push rod and located at the lower end of the temperature sensing element and moving up and down under the control of the temperature sensing element; and a buffer spring sleeved on the push rod.

[0012] Preferably, the push rod is connected to the valve core sliding sleeve through a bushing, one end of the push rod is inserted into the inside of the bushing, and an overload spring is arranged between the bushing and the push rod.

[0013] A method for treating papermaking tail gas includes the following steps:

[0014] S1: Recover the tail gas generated by the dryer and introduce it into the outlet pipeline. Detect the concentration of impurities in the dryer tail gas through the concentration detection mechanism. Set the standard value of the recovery and utilization concentration in the concentration detection mechanism, and compare and judge the actually detected concentration with the standard value of the recovery and utilization concentration;

[0015] S2: When the impurity concentration is higher than the standard value of the recovery and utilization concentration, the tail gas enters the first heat exchange mechanism, and the tail gas with waste heat is used to preheat the gas in the inlet pipeline; when the impurity concentration is lower than or equal to the standard value of the recovery and utilization concentration, the tail gas is transported to the recovery pipeline for recovery;

[0016] S3: The tail gas in the recovery pipeline is heated by the heating device and enters the temperature control valve from the first valve port. It passes through the valve core sleeve from the bottom gap of the valve core sleeve and is discharged from the third valve port and enters the recovery pipeline through the temperature sensing package. The temperature sensing package senses the temperature of the discharged tail gas. When the temperature is relatively high, the temperature sensing package expands and drives the push rod to move downward, pushing the valve core sleeve to move downward. The gap at the lower end of the valve core sleeve becomes smaller, and the gap at the upper end opens. At this time, the intake volume of the tail gas decreases, and the cold air in the cold air storage tank enters from the gap at the upper end of the valve core sleeve and mixes with the high-temperature tail gas, and the temperature of the tail gas decreases. When the temperature of the tail gas is too low, the push rod drives the valve core sleeve to move upward to reduce or close the gap at the upper end of the valve core sleeve. Finally, the tail gas enters the recovery pipeline at a constant temperature and enters the dryer.

[0017] Preferably: In step S2: The temperature of the tail gas is detected by a thermometer in the recovery pipeline, and the supplementary heating temperature value is set; when the temperature of the tail gas is higher than or equal to the supplementary heating temperature value, the tail gas is directly transported to be heated by the heating device; when the temperature of the tail gas is lower than the supplementary heating temperature value, control the switching valve to make it enter the second box body. The heating components in the second box body continuously heat the tail gas and liquid therein. As the tail gas in the second box body increases, the gas squeezes the liquid out of the second box body. The heated high-temperature liquid enters the preheating channel of the second heat exchange box to preheat the gas in the inlet pipeline again. When the liquid in the second box body is discharged to the lower end of the discharge pipe, the heated tail gas in the second box body enters the discharge pipe and enters the recovery pipeline and is heated by the heating device. At this time, the liquid in the second heat exchange box returns to the second box body, and the tail gas continues to enter the second box body, and the tail gas and liquid are circulated and heated and transported in the second box body

[0018] The beneficial effects of the present invention are:

[0019] 1. Different tail gas discharge paths are divided according to the impurity concentration in the tail gas. The tail gas with high impurity concentration is used for preheating and then discharged, making full use of energy. The tail gas with low impurity concentration is heated and recycled. It can not only maintain a certain discharge of impurities in the dryer, but also fully avoid heat loss during recovery and utilization. It is convenient to control and can automatically control the connection of each pipeline through the existing relatively mature control system to realize the automatic treatment of tail gas.

[0020] 2. The recovered tail gas with high and low temperatures is distinguished by temperature. The high-temperature tail gas is directly heated in one step, and the low-temperature tail gas is heated in a multi-stage manner, avoiding excessive energy consumption when the heating device directly heats the low-temperature tail gas and the unstable power fluctuation that affects the heating operation and service life. The low-temperature tail gas is preheated first and then heated, which has high stability, convenient heating, and prolongs the service life of the heating device. At the same time, through the setting of circulating heating, every time the tail gas is transported, it will stay in the first box for a period of time, ensuring that it is slowly heated by the heating component, so that the tail gas slowly warms up in the first box, with stable temperature rise. And a switching valve is configured to simply switch whether the tail gas needs to enter the first box for heating, with stable control.

[0021] 3. For the heating of the tail gas in the second box, it is also carried out in an intermittent transportation manner, with stable heating. At the same time, the liquid is heated, and the heated liquid is circulated and transported out to preheat the incoming gas for the second time. The heat exchange effect of the liquid is higher than the heat exchange efficiency of the gas during the first heat exchange, and the temperature of the heated liquid is higher than the temperature of the directly discharged tail gas, which can preheat the incoming gas again. The multiple preheating of the incoming gas ensures the stability of the incoming gas and achieves the purpose of not needing to set a heating device in the intake pipeline. The gas can directly reach the transportation temperature through multiple preheatings, which is convenient to use. And during the heating process, the tail gas will come into contact with the liquid, and they will come into contact with each other under pressure, which can effectively remove impurities in the tail gas and improve the intake quality.

[0022] 4. By setting a temperature control valve, when the temperature is relatively high, the intake channel of the cold air is automatically opened to supplement cold air, and when the temperature is relatively low, the intake channel of the cold air is automatically closed. And the up and down movement of the valve core sliding sleeve is controlled by the temperature of the output gas, so as to automatically adjust the opening sizes of the cold air channel and the hot air channel, and automatically control and adjust the output temperature to ensure that the temperature of the gas input into the cylinder is always stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a schematic structural diagram of the specific embodiment of the present invention;

[0025] Figure 2 It is a schematic diagram of a state of the first box in the specific embodiment of the present invention;

[0026] Figure 3Another structural schematic diagram of the first box body in the specific embodiment of the present invention;

[0027] Figure 4 Structural schematic diagram of the tail gas recovery mechanism in the specific embodiment of the present invention;

[0028] Figure 5 Structural schematic diagram of the second box body in the specific embodiment of the present invention;

[0029] Figure 6 Structural schematic diagram of the second heat exchange box in the specific embodiment of the present invention;

[0030] Figure 7 Structural schematic diagram of the temperature control mechanism in the specific embodiment of the present invention;

[0031] Figure 8 A state schematic diagram of the temperature control valve in the specific embodiment of the present invention;

[0032] Figure 9 Another structural schematic diagram of the temperature control valve in the specific embodiment of the present invention;

[0033] Examples in the figure are: 1. drying cylinder; 2. intake pipeline; 3. exhaust pipeline; 4. first heat exchange mechanism; 5. tail gas recovery mechanism; 6. concentration detection mechanism; 7. second heat exchange mechanism; 8. temperature control mechanism;

[0034] 41. first heat exchange box; 42. first preheating pipe;

[0035] 51. recovery pipeline; 52. heating device; 521. first box body; 522. heating component; 523. feed pipe; 524. discharge pipe; 525. switching valve; 526. partition board; 527. first piston; 528. first spring; 529. second box body;

[0036] 71. second heat exchange box; 72. preheating channel; 73. second preheating pipe; 74. return pipe; 75. water level sensor; 76. transition bin;

[0037] 81. electric heating pipe; 82. cold air storage tank; 83. temperature control valve; 831. valve body; 832. first valve port; 833. second valve port; 834. third valve port; 835. mounting bracket; 836. temperature sensing package; 837. valve core sliding sleeve; 8370. overload spring; 838. buffer spring; 839. push rod; Specific embodiment

[0038] 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.

[0039] Embodiment 1

[0040] As Figures 1 to 3 shown, the present invention discloses a treatment device for papermaking tail gas, which is installed on the drying cylinder 1. In the specific implementation manner of the present invention, it includes an intake pipeline 2, which is connected to the drying cylinder 1 for inputting hot air into the drying cylinder 1; an exhaust pipeline 3, which is connected to the drying cylinder 1 for discharging the tail gas of the drying cylinder 1; a first heat exchange mechanism 4, which is used for preheating the gas in the intake pipeline 2 through the tail gas; and a tail gas recovery mechanism 5, which is used for heating the tail gas discharged from the exhaust pipeline 3 and then re-transporting it into the drying cylinder 1; a concentration detection mechanism 6, which is used for detecting the concentration of impurities in the tail gas. When the impurities are high, the tail gas is selected to be transported to the first heat exchange mechanism 4, and when the impurity concentration is low, the tail gas is selected to be transported to the tail gas recovery mechanism 5; wherein, the first heat exchange mechanism 4 includes a first heat exchange box 41, which is installed on the intake pipeline 2 and communicates with the intake pipeline 2; a first preheating pipe 42, which is spirally wound and arranged in the first heat exchange box 41 and communicates with the exhaust pipeline 3.

[0041] In this embodiment, the tail gas recovery mechanism 5 includes a recovery pipeline 51, on which a temperature measuring instrument is installed; a heating device 52, which is installed on the recovery pipeline 51; the heating device 52 includes a first box body 521, inside which a heating component 522 for heating the gas is arranged. A feed pipe 523 and a discharge pipe 524 are arranged on the first box body 521; a switching valve 525, which is used for controlling the communication state between the recovery pipeline 51 and the first box body 521; a partition plate 526, which is vertically arranged in the first box body 521 and divides the interior of the first box body 521 into left and right two cavities. An air passing groove is opened at the bottom of the partition plate 526; a first piston 527, which is arranged in the cavity on the left side of the partition plate 526. A first spring 528 is arranged at the bottom of the first piston 527, and the heating component 522 is arranged above the first piston 527.

[0042] When the drying cylinder is working, the tail gas generated during the working process of the drying cylinder enters the exhaust pipeline. The concentration of impurities in the drying cylinder tail gas is detected by the concentration detection mechanism. A recovery and utilization concentration standard value is set in the concentration detection mechanism, and the actually detected concentration is compared with the recovery and utilization concentration standard value for judgment;

[0043] When the impurity concentration is higher than the standard value of the recycling concentration, the tail gas at this time has too high impurities and cannot return to the drying cylinder for recycling. The tail gas enters the first heat exchange mechanism, and the tail gas with waste heat is used to preheat the gas in the intake pipeline. Specifically: the tail gas enters the first preheating pipe in the first box body and is transported and discharged, and the gas in the intake pipeline enters the first box body, contacts the first preheating pipe, is heated and preheated, and then returns to the intake pipeline and is transported into the drying cylinder;

[0044] When the impurity concentration is lower than or equal to the standard value of the recycling concentration, the tail gas is transported to the recovery pipeline for recovery. Specifically: the tail gas enters the recovery pipeline, and the temperature is detected by a thermometer, and the supplementary heating temperature value is set;

[0045] Among them, when the temperature of the tail gas is higher than or equal to the supplementary heating temperature value, the tail gas is directly transported to the heating device, heated to the specified temperature, and then returns to the drying cylinder for cyclic use;

[0046] When the temperature of the tail gas is lower than the supplementary heating temperature value, the control switching valve is controlled to make it enter the first box body. The heating component in the first box body heats up the tail gas. As the tail gas continues to be input into the first box body, the air pressure increases, pushing the first piston to move downward until the first piston moves to the bottom of the air passage groove. At this time, the heated tail gas passes through the partition plate and is discharged from the discharge pipe and returns to the recovery pipeline for transportation; at this time, the air pressure in the first box body decreases when the gas is discharged, and the first spring drives the first piston to move upward to close the air passage groove, and the tail gas continues to be input for heating (heating the tail gas during the process of increasing air pressure), and this cycle is repeated to complete the cyclic heating and gas supply of the tail gas.

[0047] Through the above technical solutions, the beneficial effects of the present invention are as follows:

[0048] 1. Different tail gas discharge paths are divided according to the impurity concentration in the tail gas. The tail gas with high impurity concentration is used for preheating and then discharged, making full use of energy. The tail gas with low impurity concentration is heated and recycled. It can not only keep a certain amount of impurities discharged in the drying cylinder, but also fully avoid heat loss during recycling. It is convenient to control and can automatically control the connection of each pipeline through the existing relatively mature control system to realize the automatic treatment of tail gas.

[0049] 2. The recovered tail gas at high and low temperatures is distinguished by temperature. The high-temperature tail gas is directly heated in one step, while the low-temperature tail gas is heated in a multi-stage manner, avoiding excessive energy consumption when the heating device directly heats the low-temperature tail gas, and the power fluctuation affects the heating operation and service life. The low-temperature tail gas is preheated first and then heated, which has high stability, convenient heating, and extends the service life of the heating device. At the same time, through the setting of circulating heating, every time the tail gas is transported, it will stay in the first box for a period of time, ensuring that it is slowly heated by the heating component, so that the tail gas slowly warms up in the first box, with stable temperature rise. A switching valve is provided to simply switch whether the tail gas needs to enter the first box for heating, and the control is stable.

[0050] Embodiment 2

[0051] As Figures 4 to 6 shown, the difference between this embodiment and the above embodiment is that: in this embodiment, the tail gas recovery mechanism 5 includes a recovery pipeline 51, on which a thermometer is installed; a heating device 52, installed on the recovery pipeline 51; the heating device 52 includes a second box body 529, inside which a heating component 522 for heating gas and liquid is provided, the heating component 522 is spirally arranged on the inner wall of the second box body 529, the second box body 529 is filled with liquid, the second box body 529 is provided with a feed pipe 523 and a discharge pipe 524, and one end of the discharge pipe 524 extends downward to the bottom inside the second box body 529; a switching valve 525, used to control the connection state between the recovery pipeline 51 and the first box body 521; and a second heat exchange mechanism 7, arranged on the intake pipeline 2, capable of carrying the liquid in the second box body 529 and preheating the gas in the intake pipeline 2 through the high-temperature liquid.

[0052] In this embodiment, the second heat exchange mechanism 7 includes a second heat exchange box 71, inside which a plurality of preheating channels 72 are vertically arranged, and the preheating channels 72 are internally connected to the second box body 529; a second preheating pipe 73, wound around each preheating channel 72, and the second preheating pipe 73 is connected to the intake pipeline 2; a return pipe 74, connecting the bottom of the preheating channel 72 and the second box body 529, and an electromagnetic valve is arranged on the return pipe 74; a water level sensor 75, installed on the second box body 529 for detecting the water level in the second box body 529, which is arranged at the same height as the bottom of the feed pipe 523, and the water level sensor 75 is electrically connected to the electromagnetic valve.

[0053] In this embodiment, a transition bin 76 is arranged between the second heat exchange box 71 and the recovery pipeline 51, the recovery pipeline 51 is connected to the top of the transition bin 76, and the second heat exchange box 71 is connected to the bottom of the transition bin 76.

[0054] During operation, when the exhaust gas temperature is higher than or equal to the supplementary heating temperature value, the exhaust gas is directly transported to the heating device to be heated to the specified temperature and then returned to the drying cylinder for recycling;

[0055] When the exhaust gas temperature is lower than the supplementary heating temperature value, the switching valve is controlled to make the exhaust gas enter the second box body. The heating components in the second box body continuously heat the exhaust gas and liquid therein. As the exhaust gas in the second box body increases, the air pressure in the second box body increases, and the gas presses the liquid out of the second box body from the upper part. The heated high-temperature liquid enters the heat exchange pipeline from the discharge pipe, passes through the transition bin, and enters the preheating channel of the second heat exchange box to preheat the gas input into the second heat exchange pipe in the intake pipe again. When the water level sensor detects that the liquid level in the second box body is lower than the lower end of the discharge pipe, at this time, the heated exhaust gas in the second box body enters the discharge pipe and enters the recovery pipeline and is heated by the heating device. At the same time, the current valve on the return pipe opens, and the liquid in the second heat exchange box returns to the second box body under the action of gravity (a transfer pump can be set when necessary). After inputting for a certain period of time, the solenoid valve is closed. At this time, the liquid level is higher than the bottom of the discharge pipe again, and the exhaust gas stops discharging. The returned liquid and the input exhaust gas continue to enter the second box body for heating until the air pressure in the second box body presses the liquid into the second heat exchange box again, realizing the cyclic heating and transportation of the exhaust gas and liquid in the second box body;

[0056] Among them, due to the setting of the transition bin, the liquid enters the preheating channel of the second heat exchange box from the bottom of the transition bin, and the gas returns to the recovery pipeline from the upper part of the transition bin for transportation, ensuring stable transportation.

[0057] Through the above technical solution, the heating of the exhaust gas in the second box body is carried out in the same intermittent transportation method, with stable heating. At the same time, the liquid is heated, and the heated liquid is cyclically transported out to preheat the incoming gas for the second time. The heat exchange effect of the liquid is higher than the heat exchange efficiency of the gas during the first heat exchange. Moreover, the temperature of the heated liquid is higher than the temperature of the directly discharged exhaust gas, and it can preheat the incoming gas again. The multiple preheating of the incoming gas ensures the stability of the incoming gas, achieving the purpose of not needing to set a heating device in the intake pipeline. The gas transportation temperature is directly reached through multiple preheating, which is convenient to use; and during the heating process, the exhaust gas will come into contact with the liquid, and they come into contact with each other under pressure, which can effectively remove impurities in the exhaust gas and improve the intake quality.

[0058] Example 3

[0059] As Figures 7 to 9As shown in the figure, the difference between this embodiment and the above embodiment is that in this embodiment, a temperature control mechanism 8 is provided at one end of the recovery pipeline 51 close to the drying cylinder 1. The temperature control mechanism 8 includes an electric heating tube 81 provided on the recovery pipeline 51; a cold air storage tank 82 filled with cold air and communicated with the recovery pipeline 51; and a temperature control valve 83. The cold air storage tank 82 is communicated with the recovery pipeline 51 through the temperature control valve 83, and the opening and closing of the cold air storage tank 82 and the cold air delivery volume are controlled.

[0060] In this embodiment, the temperature control valve 83 includes a valve body 831. A first valve port 832, a second valve port 833 and a third valve port 834 are provided on the valve body 831. The first valve port 832 and the second valve port 833 are set as input valve ports, and the third valve port 834 is set as an output valve port. The first valve port 832 and the third valve port 834 are communicated with the recovery pipeline 51, and the second valve port 833 is communicated with the cold air storage tank 82; a mounting bracket 835 fixed inside the valve body 831; a temperature sensing bulb 836 mounted on the mounting bracket 835 and located inside the third valve port 834; a valve core sliding sleeve 837 connected to the temperature sensing bulb 836 through a push rod 839 and located at the lower end of the temperature sensing bulb 836 and controlled by the temperature sensing bulb 836 to move up and down; and a buffer spring 838 sleeved on the push rod 839.

[0061] In this embodiment, the push rod 839 is connected to the valve core sliding sleeve 837 through a bushing. One end of the push rod 839 is inserted into the interior of the bushing, and an overload spring 8370 is provided between the bushing and the push rod 839.

[0062] During operation, the preheated tail gas returns to the recovery pipeline again, and then is supplemented with heat by the heating device and enters the temperature control valve from the first valve port, passes through the valve core sliding sleeve from the bottom gap of the valve core sliding sleeve and is discharged from the third valve port and enters the recovery pipeline through the temperature sensing bulb. The temperature sensing bulb senses the temperature of the discharged tail gas. When the temperature is relatively high, the temperature sensing bulb expands and drives the push rod to move downward, pushing the valve core sliding sleeve to move downward. The gap at the lower end of the valve core sliding sleeve becomes smaller, and the gap at the upper end opens. At this time, the intake volume of the tail gas decreases, and the cold air in the cold air storage tank enters from the gap at the upper end of the valve core sliding sleeve and mixes with the high-temperature tail gas, and the temperature of the tail gas decreases. When the temperature of the tail gas is too low, the push rod drives the valve core sliding sleeve to move upward to reduce or close the gap at the upper end of the valve core sliding sleeve. Finally, the tail gas enters the recovery pipeline and then enters the drying cylinder at a constant temperature;

[0063] Through the above technical solution, since there will be a certain error in the temperature of the gas heated by the heating device, by setting the temperature control valve, when the temperature is relatively high, the intake channel of the cold air is automatically opened to supplement the cold air, and when the temperature is relatively low, the intake channel of the cold air is automatically closed, and the up and down movement of the valve core sliding sleeve is controlled by the temperature of the output gas, so as to automatically adjust the opening sizes of the cold air channel and the hot air channel, and automatically control and adjust the output temperature to ensure that the temperature of the gas entering the cylinder body is always stable.

[0064] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A treatment device for papermaking exhaust gas, installed on a drying cylinder, characterized in that: including an intake pipeline, connected to the drying cylinder for inputting hot air into the drying cylinder; an exhaust pipeline, connected to the drying cylinder for discharging the tail gas of the drying cylinder; a first heat exchange mechanism for preheating the gas in the intake pipeline by the tail gas; and a tail gas recovery mechanism for heating the tail gas discharged from the exhaust pipeline and then re - conveying it into the drying cylinder; a concentration detection mechanism for detecting the concentration of impurities in the tail gas. When the impurities are high, the tail gas is selected to be conveyed to the first heat exchange mechanism, and when the impurity concentration is low, the tail gas is selected to be conveyed to the tail gas recovery mechanism; wherein, the first heat exchange mechanism includes a first heat exchange box, installed on the intake pipeline and communicating with the intake pipeline; a first preheating pipe, spirally wound and arranged inside the first heat exchange box, and communicating with the exhaust pipeline; the tail gas recovery mechanism includes a recovery pipeline; a heating device, installed on the recovery pipeline; a temperature control mechanism is arranged at one end of the recovery pipeline close to the drying cylinder, and the temperature control mechanism includes an electric heating pipe, arranged on the recovery pipeline; a cold air storage tank, filled with cold air inside, and communicating with the recovery pipeline; a temperature control valve, the cold air storage tank is communicated with the recovery pipeline through the temperature control valve, and controls the opening and closing of the cold air storage tank and the cold air delivery volume.

2. The treatment device for papermaking tail gas according to claim 1, wherein: the heating device includes a first box body, inside which there is a heating component for heating the gas. The first box body is provided with a feed pipe and a discharge pipe; a switching valve for controlling the connection state between the recovery pipeline and the first box body; a partition plate, vertically arranged inside the first box body, dividing the inside of the first box body into left and right two cavities. An air - passing groove is opened at the bottom of the partition plate; a first piston, arranged in the cavity on the left side of the partition plate. A first spring is arranged at the bottom of the first piston, and the heating component is arranged at the upper end of the first piston.

3. The treatment device for papermaking tail gas according to claim 1, wherein: the heating device includes a second box body, inside which there is a heating component for heating the gas and liquid. The heating component is spirally arranged on the inner wall of the second box body. The second box body is filled with liquid. The second box body is provided with a feed pipe and a discharge pipe, and one end of the discharge pipe extends downward to the bottom inside the second box body; a switching valve for controlling the connection state between the recovery pipeline and the first box body; and a second heat exchange mechanism, arranged on the intake pipeline, capable of carrying the liquid in the second box body and preheating the gas in the intake pipeline by the high - temperature liquid.

4. The treatment device for papermaking tail gas according to claim 3, wherein: The second heat exchange mechanism includes a second heat exchange box, inside which there are several vertical preheating channels, and the preheating channels communicate with the inside of the second box body; a second preheating pipe, wound around each preheating channel, and the second preheating pipe communicates with the intake pipeline; a return pipe, connecting the bottom of the preheating channel and the second box body, and an electromagnetic valve is arranged on the return pipe; a water level sensor, installed on the second box body for detecting the water level in the second box body, which is arranged at the same height as the bottom of the feed pipe. The water level sensor is electrically connected to the electromagnetic valve.

5. The treatment device for papermaking tail gas according to claim 4, characterized in that: A transition bin is arranged between the second heat exchange box and the recovery pipeline. The recovery pipeline communicates with the top of the transition bin, and the second heat exchange box communicates with the bottom of the transition bin.

6. The treatment device for papermaking tail gas according to claim 5, characterized in that: The temperature control valve includes Valve body, on which a first valve port, a second valve port and a third valve port are provided. The first valve port and the second valve port are set as input valve ports, and the third valve port is set as an output valve port. The first valve port and the third valve port are communicated with a recovery pipeline, and the second valve port is communicated with a cold gas storage tank; Installation bracket, fixed inside the valve body; Thermal bulb, installed on the installation bracket and located inside the third valve port; Spool sleeve, connected to the thermal bulb through a push rod and located at the lower end of the thermal bulb, moving up and down under the control of the thermal bulb; Buffer spring, sleeved on the push rod.

7. The treatment device for papermaking tail gas according to claim 6, characterized in that: The push rod is connected to the spool sleeve through a bushing. One end of the push rod is inserted into the interior of the bushing, and an overload spring is provided between the bushing and the push rod.

8. A method for treating papermaking tail gas, applicable to a papermaking tail gas treatment device as described in claim 7, characterized in that, Including the following steps: S1: Recover the tail gas generated by the dryer into the outlet pipeline, detect the concentration of impurities in the dryer tail gas through a concentration detection mechanism, set a recovery and utilization concentration standard value in the concentration detection mechanism, and compare and judge the actually detected concentration with the recovery and utilization concentration standard value; S2: When the impurity concentration is higher than the recovery and utilization concentration standard value, the tail gas enters the first heat exchange mechanism, and the tail gas with waste heat is used to preheat the gas in the inlet pipeline; when the impurity concentration is lower than or equal to the recovery and utilization concentration standard value, the tail gas is transported to the recovery pipeline for recovery; S3: The tail gas in the recovery pipeline enters the temperature control valve from the first valve port after being heated by a heating device, passes through the spool sleeve from the bottom gap of the spool sleeve and is discharged from the third valve port, passes through the thermal bulb and enters the recovery pipeline. The thermal bulb senses the temperature of the discharged tail gas. When the temperature is relatively high, the thermal bulb expands and drives the push rod to move downward, pushing the spool sleeve to move downward. The gap at the lower end of the spool sleeve becomes smaller, and the gap at the upper end opens. At this time, the intake volume of the tail gas decreases, and the cold gas in the cold gas storage tank enters from the gap at the upper end of the spool sleeve and mixes with the high-temperature tail gas, and the temperature of the tail gas decreases. When the temperature of the tail gas is too low, the push rod drives the spool sleeve to move upward to reduce or close the gap at the upper end of the spool sleeve. Finally, the tail gas enters the recovery pipeline at a constant temperature and enters the dryer.

9. A method for treating papermaking tail gas according to claim 8, characterized in that: In step S2: The temperature of the tail gas in the recovery pipeline is detected by a thermometer, and a supplementary heating temperature value is set; When the temperature of the tail gas is higher than or equal to the supplementary heating temperature value, the tail gas is directly transported to be heated by a heating device; when the temperature of the tail gas is lower than the supplementary heating temperature value, control the switching valve to make it enter the second box body. The heating component in the second box body continuously heats the tail gas and liquid therein. As the tail gas in the second box body increases, the gas squeezes the liquid out of the second box body. The heated high-temperature liquid enters the preheating channel of the second heat exchange box to preheat the gas in the inlet pipeline again. When the liquid in the second box body is discharged to the lower end of the discharge pipe, the heated tail gas in the second box body enters the discharge pipe and enters the recovery pipeline and is heated by a heating device. At this time, the liquid in the second heat exchange box returns to the second box body, and the tail gas continues to enter the second box body, and the tail gas and liquid are circulated and heated and transported in the second box body.

Images