A pulping and bleaching device and process

Abstract

The present invention relates to the technical field of pulp bleaching, and discloses a pulp bleaching device, which includes a DHT bleaching tower, an EOP bleaching tower and a D1 bleaching tower. The bottom discharge ends of the DHT bleaching tower, the EOP bleaching tower and the D1 bleaching tower are all connected with pulp feeding pumps. In the present invention, the mixing and heating of the pulp bleaching agent are unified inside the bleaching tower, so that the pulp can be directly mixed and heated during transportation, reducing heat loss. By arranging the spiral pipeline inside the auger, not only can the conveying auger be heated to heat the pulp, but also the bleaching agent entering the inside of the conveying auger can be preheated. At the same time, through the setting of the one-way valve nozzle, the bleaching agent can be injected into the pulp in a spraying manner after preheating, and is mixed and reheated during the transportation of the conveying auger, improving the efficiency. Moreover, after the steam enters the spiral pipeline and is heat-exchanged, the remaining heat enters the bleaching chamber through the waste heat reuse pipeline and is reused again.

Description

Technical Field

[0001] The present invention relates to the technical field of pulp bleaching, and specifically to a pulp bleaching device and process. Background Art

[0002] During pulp production, wood chips on the chemical pulp production line are conveyed to the pre-impregnation tower in the cooking section by a feeding belt. After pre-impregnation is completed, they are pumped into the digester by a wood chip pump for cooking reaction. After cooking, the pulp is stored in the blow tank. The pulp then enters the washing and screening section, is pumped to a first-stage combined screen for screening, the good pulp enters the washer for washing, and then the pulp enters the oxygen delignification reaction. It is then pumped into the unbleached tower for storage, and then the pulp starts to enter the bleaching section. The traditional bleaching process is carried out through three-stage bleaching towers, namely the DHT-stage bleaching tower, the EOP-stage bleaching tower, and the D1-stage bleaching tower, to achieve bleaching. However, the existing pulp bleaching technology currently has the following disadvantages:

[0003] 1. The bleaching agent distribution of the commonly used three-stage bleaching tower is (DHT: EOP: D1 = 76%: 13%: 11%), the distribution is not reasonable enough, the dosage in the DH section is too large; the dosage in the D1 section is too small. After long-term use, it is found that the excessive chlorine dosage in the DHT section causes strong corrosion of the equipment and facilities in the DHT section, so that the equipment and facilities in the DHT bleaching section are frequently damaged.

[0004] 2. In the prior art, before the pulp enters the bleaching tower, it needs to first enter a mixer, and chlorine dioxide is mixed and added in the mixer (chlorine dioxide is pumped from the chlorine dioxide storage tank in the chlorine dioxide preparation workshop, with a temperature of about 12°C, and heated to 40°C through the chlorine dioxide heat exchanger on the pulp line site), and then the pulp mixed with chlorine dioxide is heated to the required temperature with steam (the commonly used planned temperatures are 85°C for DHT, 85°C for EOP, and 80°C for D1) and then pumped into the interior of the bleaching tower for reaction. Since both the mixer and steam heating are carried out outside the bleaching tower, there will be a certain amount of heat loss when pumping into the interior of the bleaching tower, resulting in the pulp inside the bleaching tower being much lower than the planned temperature, thus resulting in a not good enough bleaching effect.

[0005] Based on the above problems, a pulp bleaching device and process are proposed. Summary of the Invention

[0006] To achieve the above object, the present invention is realized through the following technical solutions: A pulping and bleaching device, including a DHT bleaching tower, an EOP bleaching tower, and a D1 bleaching tower. The bottom discharge ends of the DHT bleaching tower, the EOP bleaching tower, and the D1 bleaching tower are all connected with pulp feeding pumps. The DHT bleaching tower, the EOP bleaching tower, and the D1 bleaching tower include a mixing chamber and a bleaching chamber. Inside the mixing chamber, a storage hopper, a conveying chamber, and a driving chamber are sequentially arranged from top to bottom. One side of the storage hopper is provided with a pulp feeding port, and the pulp feeding port is connected with a pulp feeding pipe. A full material sensor is installed on the top of the storage hopper to control the pulp feeding pump to stop when the material is full. A conveying auger is installed inside the conveying chamber. A cloth slot is arranged on the inner top wall of the bleaching chamber, and a linkage transmission component is arranged between the top of the cloth slot and the conveying auger;

[0007] The inside of the conveying auger is hollow, and a steam heating component is arranged inside it. The steam heating component includes a spiral pipeline. One end of the spiral pipeline is connected with the air inlet connection port of the mixing chamber, and the other end of the spiral pipeline extends outside the conveying auger and is connected with a waste heat recycling pipeline. The waste heat recycling pipeline is located inside the bleaching chamber. A liquid flow chamber is formed between the spiral pipeline and the inside of the conveying auger. One-way valve nozzles communicating with a plurality of liquid flow chambers are arranged on the surface of the conveying auger. The air inlet connection port is externally connected with a steam generator;

[0008] On one side of each of the DHT bleaching tower, the EOP bleaching tower, and the D1 bleaching tower, a quantitative storage tank is arranged for storing bleaching agent or clear water. One side of the quantitative storage tank is connected with a liquid extraction pump. The liquid extraction pump is respectively connected with the conveying auger and the cloth slot through a pipeline component. A liquid level sensor is arranged inside the quantitative storage tank to control the linkage transmission component to stop when there is no liquid. Flow meters are arranged on the feed port of the pulp feeding pump and the pipeline component, and a flow regulating valve is also arranged on the pipeline component. A sewage discharge valve is arranged at the bottom of the bleaching chamber. A water inlet valve and a liquid inlet valve are connected to the surface of the quantitative storage tank.

[0009] Preferably, the cloth slot includes a slot body. A water spraying chamber is arranged inside the bottom wall of the slot body. A hollow rotating rod is fixed on the top of the slot body, and the hollow rotating rod communicates with the water spraying chamber. Water spraying ports are arranged at the bottom and side walls of the water spraying chamber. The top of the hollow rotating rod extends into the driving chamber.

[0010] Preferably, the pipeline component includes a liquid delivery pipe connected with the liquid extraction pump. The liquid delivery pipe is connected with the conveying auger through a first sealed rotating member. A three-way solenoid valve is connected to the surface of the liquid delivery pipe. One end of the three-way solenoid valve is connected with a water delivery pipe, and the water delivery pipe is rotationally connected with the hollow rotating rod through a second sealed rotating member.

[0011] Preferably, the linkage drive assembly includes a drive motor installed at the top of the mixing chamber. One end of the drive motor and the conveying auger are connected by a belt drive set. A first gear is also fixed to one end of the conveying auger. The first gear is meshed with a second gear. A rotating rod is fixed at the center of the second gear. One end of the rotating rod extends into the drive chamber. A first bevel gear and a second bevel gear are meshed between the rotating rod and the hollow rotating rod.

[0012] Preferably, a diversion channel is provided at the bottom of the conveying chamber and at one end in the pushing direction of the conveying auger. The diversion channel extends above the cloth trough.

[0013] A pulping and bleaching process includes the following operating steps:

[0014] S1. First, inject bleach accounting for 66%, 13%, and 20% of the total amount of bleach into the quantitative storage tanks connected to the DHT bleaching tower, EOP bleaching tower, and D1 bleaching tower respectively.

[0015] S2. First, convey the unbleached material to the DHT bleaching tower through a feed pump, and start the liquid extraction pump to send in the bleach. Ensure that the feeding speed ratio of the pulp to the bleach is 60 kg / admt. The conveying auger mixes the bleach and the pulp and sends them into the bleaching chamber after heating with steam.

[0016] S3. When the bleach in the quantitative storage tank connected to the DHT bleaching tower is completely pumped out, the conveying auger and the pulp feeding pump stop, completing the quantitative ratio of the pulp and the bleach.

[0017] S4. After the reaction is completed in the bleaching chamber of the DHT bleaching tower, the pulp feeding pump connected to the EOP bleaching tower extracts the pulp in the DHT bleaching tower. At the same time, the bleach in the quantitative storage tank connected to the EOP bleaching tower is extracted. By adjusting the flow rate of the bleach entering and the feeding speed of the pulp feeding pump, ensure that when the extraction of the bleach is completed, the pulp feeding pump finishes extracting the pulp and uniformly imports it into the bleaching chamber of the EOP bleaching tower for reaction.

[0018] S5. Repeat the steps of S3 to import the bleach and the pulp into the bleaching chamber inside the D1 bleaching tower for reaction, completing three bleaching processes.

[0019] Preferably, the bleaching temperature in the DHT bleaching tower is 75 - 85 °C, the bleaching temperature in the EOP bleaching tower is 78 - 85 °C, and the bleaching temperature in the D1 bleaching tower is 75 - 80 °C.

[0020] A pulping and bleaching process also includes a method for cleaning the equipment, and its specific operating steps are as follows:

[0021] a. Inject clean water into the quantitative storage box, then adjust the three-way solenoid valve to make the liquid pump, the hollow rotating rod and the conveying auger all connected, and start the linkage transmission component to drive the conveying auger and the material distribution trough to rotate;

[0022] b. Clean water is sprayed out from the one-way valve nozzle through the conveying auger, and the conveying cavity is fully cleaned under the rotation of the conveying auger. At the same time, the clean water flows to the surface of the material distribution trough through the diversion channel to achieve the effect of cleaning the material distribution trough;

[0023] c. The clean water passes through the rotating hollow rotating rod and flows into the water spraying cavity of the material distributing trough, and is discharged from the water spraying port, so that the clean water is sprayed onto the inner wall of the bleaching chamber for cleaning;

[0024] d. The cleaned water is discharged from the drain valve.

[0025] The present invention provides a pulping and bleaching device and process, which has the following beneficial effects:

[0026] 1. The present invention places the pulp bleaching agent mixing and heating in a unified manner inside the bleaching tower, so that the pulp can be directly mixed and heated during transportation, reducing heat loss. By arranging the spiral pipe inside the auger, not only the conveying auger can be heated to heat the pulp, but also the bleaching agent entering the conveying auger can be preheated. At the same time, through the arrangement of the one-way valve nozzle, the bleaching agent can be injected into the pulp by injection after preheating, and mixed and heated during the transportation process of the conveying auger, thereby improving efficiency. After the steam enters the spiral pipe for heat exchange, the remaining heat of the steam enters the bleaching chamber through the waste heat recycling pipe and is reused, which can avoid excessive heat loss during bleaching.

[0027] 2. The present invention sets a linkage transmission component, a distribution trough, and a pipeline component. The linkage transmission component can drive the conveying auger and the distribution trough to rotate in a linkage manner. The conveying auger is used to mix and convey the slurry. When the distribution trough rotates, the slurry can fall evenly without accumulating in one place. The pipeline component can deliver bleach and clean water. When cleaning is needed, the conveying auger and the distribution trough can spray clean water to clean various parts of the tower body to reduce corrosion.

[0028] 3. The present invention increases the bleaching temperature of each bleaching section, greatly reduces the heat loss under the condition of the same steam temperature, makes the bleaching temperature closer to the preset temperature, and at the same time reduces the bleaching proportion of the DHT section and increases the bleaching proportion of the D1 section, ultimately reducing the bleaching agent consumption in the bleaching section and reducing the corrosion of the equipment and facilities in the DHT section, thereby reducing the quality accidents of the finished product and improving the first-class product rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is an overall schematic diagram of the present invention;

[0030] Figure 2 A perspective view of the mixing chamber and the bleaching chamber in the present invention;

[0031] Figure 3 A cross-sectional view of the mixing chamber and the bleaching chamber in the present invention;

[0032] Figure 4 An internal structure diagram of the conveying auger in the present invention;

[0033] Figure 5 A partial side view of the present invention;

[0034] Figure 6 A cross-sectional view of the cloth chute in the present invention;

[0035] Figure 7 An enlarged view of A in the present invention.

[0036] Wherein, 1, DHT bleaching tower; 2, EOP bleaching tower; 3, D1 bleaching tower; 4, slurry feed pipe; 5, slurry delivery pump; 6, mixing chamber; 61, storage hopper; 62, conveying cavity; 63, drive cavity; 7, bleaching chamber; 8, conveying auger; 81, one-way valve spray head; 82, liquid flow cavity; 9, linkage drive assembly; 91, drive motor; 92, belt drive group; 93, first gear; 94, second gear; 95, first bevel gear; 96, second bevel gear; 10, cloth chute; 101, trough body; 102, hollow rotating rod; 103, water spraying cavity; 104, water spraying port; 105, second sealed rotating member; 106, water supply pipe; 11, steam heating assembly; 111, spiral pipe; 112, waste heat recycling pipe; 113, air inlet connection port; 12, slurry feed inlet; 13, quantitative storage tank; 14, liquid pumping pump; 15, first sealed rotating member; 16, liquid delivery pipe; 17, three-way solenoid valve; 18, full material sensor; 19, flow meter; 20, flow regulating valve; 21, sewage discharge valve. Detailed implementation manners

[0037] 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0038] Embodiment 1:

[0039] As Figures 1-7As shown in the figure, an embodiment of the present invention provides a pulping and bleaching device, including a DHT bleaching tower 1, an EOP bleaching tower 2, and a D1 bleaching tower 3. The bottom discharge ends of the DHT bleaching tower 1, the EOP bleaching tower 2, and the D1 bleaching tower 3 are all connected with pulp feeding pumps 5. The DHT bleaching tower 1, the EOP bleaching tower 2, and the D1 bleaching tower 3 include a mixing chamber 6 and a bleaching chamber 7. Inside the mixing chamber 6, a stock hopper 61, a conveying chamber 62, and a driving chamber 63 are sequentially arranged from top to bottom. On one side of the stock hopper 61, there is a pulp feeding port 12, and the pulp feeding port 12 is connected with a pulp feeding pipe 4. At the top of the stock hopper 61, a full material sensor 18 is installed, which is used to control the pulp feeding pump 5 to stop when the material is full, so as to avoid the accumulation of pulp in case of failure or blockage. Inside the conveying chamber 62, a conveying auger 8 is installed. On the inner top wall of the bleaching chamber 7, there is a cloth trough 10, which can make the pulp be evenly fed at various positions when being introduced into the inside of the bleaching chamber 7, avoiding accumulation only at one place. Between the top of the cloth trough 10 and the conveying auger 8, there is a linkage transmission component 9; so that the pushing and cloth feeding of the pulp are driven by the same power element, in order to maintain the same speed ratio, the feeding effect is better, and at the same time, the energy consumption is more saved;

[0040] The inside of the conveying auger 8 is hollow, and inside it, there is a steam heating component 11. The steam heating component 11 includes a spiral pipeline 111. One end of the spiral pipeline 111 is connected with the air inlet connection port 113 of the mixing chamber 6, and the other end of the spiral pipeline 111 extends out of the conveying auger 8 and is connected with a waste heat recycling pipeline 112. The waste heat recycling pipeline 112 is located inside the bleaching chamber 7, which can keep the pulp entering the bleaching chamber 7 warm, so that it always remains at a relatively high temperature, avoiding excessive heat dissipation. A liquid flow chamber 82 is formed between the spiral pipeline 111 and the inside of the conveying auger 8, so that the bleaching agent chlorine dioxide first enters the liquid flow chamber 82 to contact with the spiral pipeline 111 for preheating, and then is heated again when spraying and mixing with the pulp, and the heating effect is better. On the surface of the conveying auger 8, there are one-way valve nozzles 81 communicated with a plurality of liquid flow chambers 82. The one-way valve nozzles 81 can only spray in one direction, and can prevent the pulp from infiltrating into the inside of the conveying auger 8. The air inlet connection port 113 is externally connected with a steam generator;

[0041] On one side of each of the DHT bleaching tower 1, the EOP bleaching tower 2, and the D1 bleaching tower 3, there is a quantitative storage tank 13, which is used to store bleaching agent or clear water. On one side of the quantitative storage tank 13, there is a liquid extraction pump 14. The liquid extraction pump 14 is connected with the conveying auger 8 and the cloth trough 10 respectively through a pipeline assembly. When the bleaching agent (chlorine dioxide) is injected into the quantitative storage tank 13, the liquid extraction pump 14 is only communicated with the conveying auger 8 through the pipeline assembly, so as to mix the bleaching agent inside the pulp. When clear water is injected into the quantitative storage tank 13, the liquid extraction pump 14 is communicated with both the conveying auger 8 and the cloth trough 10 through the pipeline assembly to thoroughly clean the tower body.

[0042] Inside the quantitative storage tank 13, a liquid level sensor is provided to control the linkage drive assembly 9 to stop when there is no liquid. Flow meters 19 are provided at the feed inlet of the slurry feeding pump 5 and on the pipeline assembly to calculate the flow rate, so as to obtain the total quantity entering. A flow regulating valve 20 is also provided on the pipeline assembly to regulate the flow rate of the bleach entering. A drain valve 21 is provided at the bottom of the bleaching chamber 7. The surface of the quantitative storage tank 13 is connected with a water inlet valve and a liquid inlet valve, and the water inlet valve and the liquid inlet valve are respectively connected with the clean water pipeline and the bleach inlet pipeline for liquid inlet.

[0043] The fabric trough 10 includes a trough body 101. Inside the bottom wall of the trough body 101, a water spraying cavity 103 is provided. At the top of the trough body 101, a hollow rotating rod 102 is fixed. The hollow rotating rod 102 is communicated with the water spraying cavity 103. Water spraying openings 104 are provided at the bottom and side walls of the water spraying cavity 103. The top of the hollow rotating rod 102 extends into the driving cavity 63. The pipeline assembly includes a liquid delivery pipe 16 connected to the liquid pumping pump 14. The liquid delivery pipe 16 is connected to the conveying auger 8 through a first sealed rotating member 15. A three-way solenoid valve 17 is connected to the surface of the liquid delivery pipe 16. One end of the three-way solenoid valve 17 is connected with a water delivery pipe 106. The water delivery pipe 106 is rotationally connected to the hollow rotating rod 102 through a second sealed rotating member 105. The setting of the first sealed rotating member 15 enables the liquid inlet to be unaffected when the conveying auger 8 rotates, and the setting of the second sealed rotating member 105 enables the hollow rotating rod 102 to rotate without being affected.

[0044] The linkage drive assembly 9 includes a driving motor 91 installed at the top of the mixing chamber 6. The driving motor 91 and one end of the conveying auger 8 are connected with a belt drive group 92. A first gear 93 is also fixed at one end of the conveying auger 8. The first gear 93 is meshed and connected with a second gear 94. A rotating rod is fixed at the center of the second gear 94. One end of the rotating rod extends into the driving cavity 63. A first bevel gear 95 and a second bevel gear 96 are meshed and connected between the rotating rod and the hollow rotating rod 102. During specific use, when the driving motor 91 is started, it drives the belt drive group 92 to rotate. The belt drive group 92 drives the conveying auger 8 to rotate. When the conveying auger 8 rotates, it drives the rotating rod to rotate through the first gear 93 and the second gear 94, so that the rotating rod drives the hollow rotating rod 102 to rotate through the first bevel gear 95 and the second bevel gear 96, thereby driving the fabric trough 10 to rotate in a linkage manner. At the bottom of the conveying cavity 62 and at one end in the pushing direction of the conveying auger 8, a diversion channel is provided, and the diversion channel extends above the fabric trough 10 to facilitate the fabric trough 10 to evenly rotate and distribute the falling slurry.

[0045] Example 2:

[0046] A pulping and bleaching process includes the following operating steps:

[0047] S1. First, inject bleaching agents into the quantitative storage tanks 13 connected to the DHT bleaching tower 1, EOP bleaching tower 2, and D1 bleaching tower 3, accounting for 66%, 13%, and 20% of the total amount of bleaching agents respectively. Through practice, this proportion of chlorine dioxide ultimately reduces the consumption of bleaching agents in the bleaching section and reduces the corrosion of equipment and facilities in the DHT section, while reducing the total COD emissions of bleaching.

[0048] S2. First, convey the unbleached materials to the DHT bleaching tower 1 through the feed pump 5, and start the liquid extraction pump 14 to send in the bleaching agent. Ensure that the feeding speed ratio of the pulp to the bleaching agent is 60 kg / admt. The conveying auger 8 mixes the bleaching agent and the pulp, and after heating with steam, sends them into the bleaching chamber.

[0049] S3. When the bleaching agent in the quantitative storage tank 13 connected to the DHT bleaching tower 1 is completely pumped out, the conveying auger 8 and the pulp feeding pump 5 stop, completing the quantitative ratio of the pulp and the bleaching agent, thus ensuring the ratio of the first bleaching of this batch of pulp.

[0050] S4. After the reaction is completed in the bleaching chamber 7 of the DHT bleaching tower 1, the pulp feeding pump 5 connected to the EOP bleaching tower 2 extracts the pulp in the DHT bleaching tower 1. At the same time, the bleaching agent in the quantitative storage tank 13 connected to the EOP bleaching tower 2 is pumped out. By adjusting the flow rate of the bleaching agent entering and the feeding speed of the pulp feeding pump 5, ensure that when the extraction of the bleaching agent is completed, the pulp feeding pump 5 finishes extracting the pulp, and uniformly imports it into the bleaching chamber 7 of the EOP bleaching tower 2 for reaction. Its flow meter 19 can obtain the flow rates of the incoming pulp and the incoming bleaching agent. The system pre-sets the weight of the pulp after adding the first bleaching agent, and calculates according to the total amount to determine the proportion of the bleaching agent at 13% at the EOP. When the flow rate is such that the bleaching agent and the pulp after the first bleaching are pumped out at the same time, then adjust the size of the flow regulating valve 20. The flow meter 19 monitors in real time whether the actual flow rate is the same as the expected flow rate and gives timely feedback for adjustment.

[0051] S5. Repeat the steps of S3 to import the bleaching agent and the pulp into the bleaching chamber 7 inside the D1 bleaching tower 3 for reaction, completing three bleaching processes, ensuring that the proportion of chlorine dioxide in the DHT section is 66%, the proportion of chlorine dioxide in the E0P section is 13%, and the proportion of chlorine dioxide in the D1 section is 20%, ensuring an accurate ratio and guaranteeing the production quality.

[0052] The bleaching temperature in the DHT bleaching tower 1 is 75 °C, the bleaching temperature in the EOP bleaching tower 2 is 78 °C, and the bleaching temperature in the D1 bleaching tower 3 is 75 °C.

[0053] 1. Reduce quality accidents. The first-class product rate of the 2# pulping and bleaching eucalyptus pulp has increased from 99.5% to 99.9%.

[0054] 2. After the available chlorine content of DHT is reduced, the pH value of the DHT section increases, and the overall equipment corrosion is reduced.

[0055] 3. After the overall chlorine consumption is reduced, the total COD emission of the 2# bleaching process is reduced by 120 mg / l.

[0056] 4. The chlorine consumption of the bleaching agent in the 2# bleaching process of the pulping workshop is reduced from 69 kg / ton of pulp to 60 kg / ton of pulp, and the available chlorine consumption per ton of pulp is reduced by 9 kg / ton of pulp.

[0057] 5. Direct economic benefit evaluation: Calculated based on an annual output of 140,000 tons of eucalyptus pulp, the annual cost savings = 140,000 tons / year × (9.0 kg / ton of pulp ÷ 2.63) × 8000 yuan / ton of chlorine dioxide / 1000 = 3.832 million yuan; (Note: The unit price of chlorine dioxide is calculated at 8.0 yuan / kg).

[0058] Example 3:

[0059] A pulping and bleaching process further includes a method for cleaning the equipment, and the specific operation steps are as follows:

[0060] a. Inject clean water into the quantitative storage tank 13, then adjust the three-way solenoid valve 17 to make the liquid extraction pump 14 communicate with the hollow rotating rod 102 and the conveying auger 8, and start the linkage transmission assembly 9 to drive the conveying auger 8 and the cloth trough 10 to rotate;

[0061] b. The clean water is sprayed out from the one-way valve nozzle 81 through the conveying auger 8, and comprehensively cleans the conveying cavity 62 under the rotation of the conveying auger 8. At the same time, the clean water flows to the surface of the cloth trough 10 through the diversion channel to achieve the effect of cleaning the cloth trough 10;

[0062] c. The clean water flows through the rotating hollow rotating rod 102 and into the water spraying cavity 103 of the cloth trough 10, and is discharged from the water spraying port 104, so that the clean water is sprayed onto the inner wall of the bleaching chamber 7 for cleaning;

[0063] d. The cleaned water is discharged from the sewage valve 21.

[0064] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pulp bleaching device, comprising a DHT bleaching tower (1), an EOP bleaching tower (2) and a D1 bleaching tower (3), wherein the bottom discharge ends of the DHT bleaching tower (1), the EOP bleaching tower (2) and the D1 bleaching tower (3) are all connected with a pulp feeding pump (5), and is characterized in that: The DHT bleaching tower (1), EOP bleaching tower (2) and D1 bleaching tower (3) include a mixing chamber (6) and a bleaching chamber (7). Inside the mixing chamber (6), a storage hopper (61), a conveying chamber (62) and a driving chamber (63) are sequentially arranged from top to bottom. One side of the storage hopper (61) is provided with a slurry inlet (12), and the slurry inlet (12) is connected to a slurry feed pipe (4). A full - material sensor (18) is installed at the top of the storage hopper (61) to control the slurry - feeding pump (5) to stop when the material is full. Inside the conveying chamber (62), a conveying auger (8) is installed. On the inner top wall of the bleaching chamber (7), a cloth - distributing trough (10) is provided. A linkage transmission assembly (9) is arranged between the top of the cloth - distributing trough (10) and the conveying auger (8). At the bottom of the conveying chamber (62) and at one end in the pushing direction of the conveying auger (8), a diversion channel is provided, and the diversion channel extends above the cloth - distributing trough (10). The inside of the conveying auger (8) is hollow, and a steam heating assembly (11) is arranged inside it. The steam heating assembly (11) includes a spiral pipe (111). One end of the spiral pipe (111) is connected to the air - inlet connection port (113) of the mixing chamber (6), and the other end of the spiral pipe (111) extends outside the conveying auger (8) and is connected to a waste - heat recycling pipe (112). The waste - heat recycling pipe (112) is located inside the bleaching chamber (7). A liquid - flow cavity (82) is formed between the spiral pipe (111) and the inside of the conveying auger (8). One - way valve nozzles (81) communicating with the liquid - flow cavity (82) are arranged on the surface of the conveying auger (8). The air - inlet connection port (113) is externally connected to a steam generator. On one side of each of the DHT bleaching tower (1), EOP bleaching tower (2) and D1 bleaching tower (3), a quantitative storage tank (13) is provided for storing bleaching agent or clear water. One side of the quantitative storage tank (13) is connected to a liquid - pumping pump (14). The liquid - pumping pump (14) is connected to the liquid - flow cavity (82) and the cloth - distributing trough (10) respectively through a pipeline assembly. A liquid - level sensor is arranged inside the quantitative storage tank (13) to control the linkage transmission assembly (9) to stop when there is no liquid. Flow meters (19) are arranged at the feed inlet of the slurry - feeding pump (5) and on the pipeline assembly. A flow - regulating valve (20) is also arranged on the pipeline assembly. A drain valve (21) is arranged at the bottom of the bleaching chamber (7). A water inlet valve and a liquid inlet valve are connected to the surface of the quantitative storage tank (13).

2. The pulp bleaching equipment according to claim 1, characterized in that: The cloth trough (10) includes a trough body (101). A water spraying cavity (103) is arranged inside the bottom wall of the trough body (101). A hollow rotating rod (102) is fixed at the top of the trough body (101). The hollow rotating rod (102) is communicated with the water spraying cavity (103). Water spraying openings (104) are formed in the bottom and side walls of the water spraying cavity (103). The top of the hollow rotating rod (102) extends into the driving cavity (63).

3. The pulping and bleaching equipment according to claim 2, characterized in that: The pipeline assembly includes a liquid delivery pipe (16) connected to a liquid extraction pump (14). The liquid delivery pipe (16) is connected to a conveying auger (8) through a first sealed rotating part (15). A three-way solenoid valve (17) is connected to the surface of the liquid delivery pipe (16). One end of the three-way solenoid valve (17) is connected to a water delivery pipe (106). The water delivery pipe (106) is rotationally connected to the hollow rotating rod (102) through a second sealed rotating part (105).

4. The pulping and bleaching equipment according to claim 3, characterized in that: The linkage transmission assembly (9) includes a driving motor (91) installed on the top of the mixing chamber (6). A belt transmission group (92) is connected between the driving motor (91) and one end of the conveying auger (8). A first gear (93) is further fixed at one end of the conveying auger (8). The first gear (93) is meshed with a second gear (94). A rotating rod is fixed at the center of the second gear (94). One end of the rotating rod extends into the driving cavity (63). A first bevel gear (95) and a second bevel gear (96) are meshed between the rotating rod and the hollow rotating rod (102).

5. A cleaning process for a pulping and bleaching device, characterized in that: Cleaning the pulping and bleaching equipment according to claim 4 includes the following specific operation steps: a. Inject clean water into the quantitative storage tank (13). Then adjust the three-way solenoid valve (17) to make the liquid extraction pump (14) communicate with both the hollow rotating rod (102) and the conveying auger (8), and start the linkage transmission assembly (9) to drive the conveying auger (8) and the cloth trough (10) to rotate; b. The clean water is sprayed out from the one-way valve nozzle (81) through the conveying auger (8), and the conveying cavity (62) is comprehensively cleaned under the rotation of the conveying auger (8). At the same time, the clean water flows to the surface of the cloth trough (10) through the diversion channel to achieve the effect of cleaning the cloth trough (10); c. The clean water flows through the rotating hollow rotating rod (102) and into the water spraying cavity (103) of the cloth trough (10), and is discharged from the water spraying opening (104) to spray the clean water onto the inner wall of the bleaching chamber (7) for cleaning; d. The water after cleaning is discharged from the sewage valve (21).

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