White water circulating system for coating white cardboard and white water three-stage filtering and recycling method thereof

Abstract

The invention provides a white water circulating system for coating white cardboard and a white water three-stage filtering and recycling method thereof. The white water circulating system comprises a white water tank under a paper machine net, a mixed white water pump, a broken paper high-concentration slag separator and a multi-disc filter, the mixed white water pump is used for mixing water in the white water tank under the paper machine net with the cushion layer pulp through a pipeline and then supplying to the multi-disc filter for graded filtration; the multi-disc filter divides the filtered filtrate into an ultra-clear filtrate tank, a clear filtrate tank and a turbid filtrate tank which are arranged respectively through grading and shunting; filtrate in the turbid filtrate tank is connected with a turbid filtrate pump through a pipeline and circularly flows back to the multi-disc filter; filtrate in the ultra-clear filtrate tank is pumped to a net part of the paper machine for low-pressure spraying; the filtrate of the clear filtrate tank passes through a clear filtrate pump and a gravity filter, the re-treated filtrate is collected in a first ultra-clean water tank, and a part of the filtrate enters a second ultra-clean water tank through a fine filter and is respectively used as water for various spraying and secondary dilution of chemicals at a net part and a pressing part of a paper machine, so that classified filtration and recycling of the white water are realized.

Description

[Technical field]

[0001] The invention relates to papermaking technology, in particular to a white water circulation system for coating white card paper and a three-stage filtering and recycling method for the white water. [Background technology]

[0002] In the production process of white cardboard, papermaking white water refers to the moisture produced by gravity, vacuum suction and mechanical pressing in the wire and press sections of the papermaking process. It usually includes fine fibers, fillers and other small particles that penetrate the fabric together with water, as well as related functional additives added in the papermaking process.

[0003] At present, about 1% to 3% of the total output of paper mills is lost in the white water flowing out under normal production conditions of paper machine equipment. Even if more efficient white water recovery equipment is used, such as multi-disc filters, the average fiber loss is as high as 1% to 1.5% of the total output. If white water is treated as wastewater, it will not only waste available fiber and water resources, but also increase the cost of sewage treatment.

[0004] Fiber recovery refers to the recycling of fibers, fillers, etc. in white water, so that resources can be recycled and reused to achieve the purpose of saving raw material costs. In recent years, due to environmental pressure and the need to reduce costs, papermaking companies have been seeking new methods and technologies to reduce the use of raw materials and clean water, striving to save money and reduce consumption without affecting product quality, reducing costs, and improving the sustainable production capacity of the papermaking industry. In actual production, multi-disc filters are often used to treat white water under the paper machine net to obtain the corresponding filtrate; but the processing accuracy of multi-disc filters alone is far from enough. Even if ultra-clear filtrate is obtained, it cannot meet the level of replacing clean water, resulting in the inability to fully reuse white water in the paper machine. Excess white water can only be discharged, resulting in the loss of available fibers, increased sewage treatment costs, and a higher consumption of clean water per ton of paper for the paper machine.

[0005] It can be seen that there is an urgent need to improve and enhance the existing papermaking white water recovery and utilization system to further increase the white water recovery ratio. [Summary of the invention]

[0006] The white water circulation system for coating white cardboard and the three-stage filtration and recovery method of white water of the present invention can effectively improve the filtration accuracy of white water of a paper machine, further improve the recovery efficiency of available fibers, reduce the suspended matter content of recycled white water, so that treated water with different filtration accuracies can be graded and recycled in different sections of the paper machine, and the ultra-clear water finally obtained meets the requirement of replacing clear water, thereby reducing the consumption of clear water per ton of paper of the paper machine.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is:

[0008] A white water circulation system for coating white cardboard, used for graded filtration and recycling of white water, comprising a white water tank under the paper machine wire, a mixed white water pump, a broke paper high-concentration cleaner and a multi-disc filter, wherein the white water tank under the paper machine wire is used to receive the white water filtered out of the mixed paper machine wire section and the press section, and the broke paper high-concentration cleaner is used to supply cushion pulp after the cleaning;

[0009] The mixed white water pump pumps out the white water in the white water pool under the paper machine through the pipeline, and mixes it with the cushion slurry after deslagging supplied by the broke high-concentration deslagging device through the pipeline to a certain concentration, and then supplies it to the multi-disc filter through the pipeline for graded filtration;

[0010] The multi-disc filter separates the filtered filtrate into three levels and then flows into the ultra-clear filtrate pool, the clear filtrate pool and the turbid filtrate pool which are respectively arranged;

[0011] The turbid filtrate pool is connected to a turbid filtrate pump through a pipeline, and the turbid filtrate pump recycles 100% of the turbid filtrate in the turbid filtrate pool to the multi-disc filter through a reflux pipeline, and repeatedly recycles and reuses it together with white water for multi-disc filtration;

[0012] The ultra-clear filtrate pool is connected to a low-pressure ultra-clear spray pump and a low-pressure filter arranged in sequence through a pipeline, and the low-pressure ultra-clear spray pump pumps the ultra-clear filtrate after low-pressure filtration to the wire part of the paper machine for low-pressure spraying of the wire part;

[0013] The clear filtrate pool is connected to a clear filtrate pump and a multi-disc spray white water pump through pipelines. The multi-disc spray white water pump is connected to the multi-disc filter through pipelines and pumps part of the white water in the clear filtrate pool to the multi-disc filter for pulp stripping spray and screen washing spray.

[0014] The clear filtrate pump is connected to a gravity filter for resource recovery filtration and a white water tower for storing white water through pipelines. The white water tower is connected to at least three white water pumps through pipelines to pump out the white water supplied by the clear filtrate pool for use as water for pulping and concentration adjustment of broken paper under the machine, for dilution and flushing of the slag remover and pressure screen, and for pulping and concentration adjustment of the pulp line.

[0015] The gravity filter is connected to a first ultra-clear water tank for collecting the filtrate generated after the second treatment through a pipeline, and the first ultra-clear water tank is respectively connected to a medium-pressure ultra-clear water pump and a filler preparation ultra-clear water pump through pipelines, the medium-pressure ultra-clear water pump pumps the ultra-clear filtrate in the first ultra-clear water tank to the wire part of the paper machine for medium-pressure spraying of the wire part, and the filler preparation ultra-clear water pump pumps the ultra-clear filtrate in the first ultra-clear water tank to the filler preparation mixer for use as water for filler preparation;

[0016] The first ultra-clear water tank is also connected to a transfer ultra-clear water pump, a fine filter and a second ultra-clear water tank in sequence through pipelines. The transfer ultra-clear water pump pumps the ultra-clear filtrate in the first ultra-clear water tank to the fine filter, and after re-filtration, it is collected in the second ultra-clear water tank for storage. The white water after fine filtration in the second ultra-clear water tank is pumped out by multiple ultra-clear water pumps respectively, and is used as water for high-pressure spraying of the paper machine mesh part, for low-pressure spraying of the paper machine mesh pressure part, and for online dilution of chemicals.

[0017] Preferably, the multi-disc filter is also connected to a broken paper concentration tank through a pipeline for recovering and collecting the concentrated pulp after being processed by the multi-discs.

[0018] Preferably, the clear filtrate pool is also connected to a paper web flushing water pump through a pipeline, and the paper web flushing water pump supplies white water required for paper web flushing to the broken paper flushing point of the couch roll.

[0019] Preferably, a slurry return pipeline is connected between the gravity filter and the turbid filtrate pool, for returning the slurry recovered and filtered by the gravity filter to the turbid filtrate pool for reuse.

[0020] Preferably, at least two slurry pumps are connected between the fine filter and the turbid filtrate pool via a pipeline, and the two slurry pumps pump the filter residue filtered by the fine filter to the turbid filtrate pool for reuse.

[0021] Preferably, the second ultra-clear water tank is connected through pipelines to at least two high-pressure ultra-clear water pumps for high-pressure spray pumping of water for the paper machine wire section, the second ultra-clear water tank is connected through pipelines to at least two low-pressure ultra-clear water pumps for low-pressure spray pumping of water for cleaning and lubrication of scrapers and felts in the paper machine wire section and press section, and the second ultra-clear water tank is also connected through pipelines to a chemical dilution ultra-clear water pump for secondary pumping of water for online dilution of chemicals.

[0022] According to the above-mentioned three-stage filtering and recycling method of white water in the white water circulation system for coating white cardboard, the following steps are included:

[0023] S1. The mixed white water pump pumps the white water from the white water pool under the paper machine through the pipeline, and mixes it with the cushion pulp after deslagging supplied by the broke high-concentration deslagging device through the pipeline at a certain concentration, and then enters the multi-disc filter through the pipeline for graded filtration;

[0024] S2. After being processed by multiple discs of the multi-disc filter, the concentrated pulp enters the broke concentration tank, and then is refined and mixed into the core layer of the white cardboard in a certain proportion;

[0025] S3. The white water after being treated by the multi-disc filter is divided into three levels: turbid filtrate, clear filtrate and ultra-clear filtrate, and flows into the ultra-clear filtrate pool, the clear filtrate pool and the turbid filtrate pool respectively through pipelines;

[0026] S4, the ultra-clear filtrate pool pumps the ultra-clear filtrate after low-pressure filtration to the wire part of the paper machine through a low-pressure ultra-clear spray pump and a low-pressure filter for low-pressure spraying of the wire part;

[0027] S5. A part of the filtrate in the clear filtrate pool is supplied with white water required for paper web flushing to the broken paper flushing point of the couch roll through the paper web flushing water pump;

[0028] S6. A portion of the filtrate in the clear filtrate pool is pumped to the multi-disc filter through a multi-disc spray white water pump for pulp stripping spray and screen washing spray;

[0029] S7, the turbid filtrate pool recycles 100% of the turbid filtrate in the turbid filtrate pool to the multi-disc filter through the turbid filtrate pump and the reflux pipeline;

[0030] S8. Another part of the filtrate in the clear filtrate pool is supplied to the gravity filter for resource recovery filtration and the white water tower for storing white water through the clear filtrate pump. The gravity filter returns the recovered filtered slurry to the turbid filtrate pool for reuse through the slurry return pipeline.

[0031] S9, white water tower is connected to three white water pumps through pipelines, and white water supplied from the clear filtrate pool is pumped out respectively for use in pulping and concentration adjustment of broken paper under the machine, for dilution and flushing of the slag remover and pressure screen, and for pulping and concentration adjustment of the pulp line;

[0032] S10, the filtrate produced after being treated again by the gravity filter is collected in the first ultra-clear water tank;

[0033] S11, the first ultra-clear water tank pumps a portion of the ultra-clear filtrate to the wire part of the paper machine through a medium-pressure ultra-clear water pump for medium-pressure spraying of the wire part;

[0034] S12, the first ultra-clear water tank uses a filler preparation ultra-clear water pump to pump a portion of the ultra-clear filtrate to the filler preparation mixer for use as filler preparation water;

[0035] S13, the first ultra-clear water tank is also connected to a transfer ultra-clear water pump and a fine filter in sequence through pipelines, the transfer ultra-clear water pump pumps the ultra-clear filtrate in the first ultra-clear water tank to the fine filter, and after re-filtration, the filtrate is collected and stored in the second ultra-clear water tank, and the filter residue is pumped to the turbid filtrate tank for reuse through two slurry pumps;

[0036] S14, a portion of the ultra-clear filtrate from the second ultra-clear water tank is supplied to the wire section of the paper machine through two high-pressure ultra-clear water pumps for high-pressure spraying of the wire section;

[0037] S15, a portion of the ultra-clear filtrate in the second ultra-clear water tank is supplied to the wire section and the press section of the paper machine through a low-pressure ultra-clear water pump for low-pressure spraying to clean and lubricate the scrapers and felts in the wire section and the press section;

[0038] S15, another part of the ultra-clear filtrate in the second ultra-clear water tank is used as water for online chemical dilution through the chemical dilution ultra-clear water pump;

[0039] S16. The white water is filtered through a combination of a gravity filter and a fine filter to replace the clean water used for high-pressure spraying of the network pressure part and secondary dilution of chemicals, thereby achieving graded filtration and recycling of the white water.

[0040] The beneficial effects of the present invention are:

[0041] In the present invention, the multi-disc filter flows the filtered filtrate into the ultra-clear filtrate pool, the clear filtrate pool and the turbid filtrate pool respectively arranged through classification and diversion; the turbid filtrate pool is connected to the turbid filtrate pump through a pipeline to circulate back to the multi-disc filter, and the filtrate in the ultra-clear filtrate pool is pumped to the wire part of the paper machine for low-pressure spraying; part of the white water in the clear filtrate pool is recycled to the multi-disc filter for pulp stripping spraying and wire washing spraying of the multi-disc filter, part of it is used for broken paper flushing at the broken paper flushing point of the couch roll, and part of it is stored in the white water tower for broken paper pulping and pulping under the machine respectively. Water for concentration adjustment, water for dilution and flushing of slag remover and pressure screen, water for pulping and concentration adjustment of pulp line. The clear filtrate pool also collects the treated filtrate again in the first ultra-clear water pool through the clear filtrate pump and gravity filter. Part of the filtrate in the first ultra-clear water pool is used for medium-pressure spraying of the wire section and filler preparation, and the other part of the filtrate in the first ultra-clear water pool is filtered through a fine filter into the second ultra-clear water pool, which are used for high-pressure spraying of the paper machine wire section, low-pressure spraying of the paper machine wire pressure section, and online dilution of chemicals, respectively, to achieve graded filtration and recycling of white water.

[0042] Compared with the existing papermaking water treatment process, the present invention adopts the process of three-stage filtration and classification and reuse of white water, and sets a multi-disc filter, a gravity filter, a fine filter and other equipment for three-stage filtration. The filter residues of the gravity filter and the fine filter are reused in the turbid filtrate pool, so as to further improve the recovery efficiency of available fiber; the turbid filtrate, clear filtrate and ultra-clear filtrate obtained by treatment by the multi-disc filter, the ultra-clear water in the first ultra-clear water pool after treatment by the gravity filter, and the ultra-clear water in the second ultra-clear water pool after treatment by the fine filter are respectively classified and reused in different sections of the paper machine, wherein the ultra-clear water in the second ultra-clear water pool meets the requirement of replacing the existing clean water, and can effectively reduce the consumption of clean water per ton of paper of the paper machine.

Brief Description of the Drawings

[0043] Figure 1 It is a schematic diagram of the system principle of the present invention. [Specific implementation method]

[0044] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] In the description of the present invention, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0046] A white water circulation system for coating white cardboard, used for graded filtration and recycling of white water, such as Figure 1 As shown, it comprises a paper machine under-net white water tank 1, a mixed white water pump 2, a broke paper high-concentration cleaner 3 and a multi-disc filter 4. The paper machine under-net white water tank 1 is used to receive and mix white water filtered out of the paper machine under-net and the press part, and the broke paper high-concentration cleaner 3 is used to supply the cushion pulp after the cleaning; the mixed white water pump 2 mixes the white water pumped out of the paper machine under-net white water tank 1 and the cushion pulp after the cleaning supplied by the broke paper high-concentration cleaner 3 through the pipeline to a certain concentration, and then supplies them together through the pipeline into the multi-disc filter 4 for graded filtration; the multi-disc filter 4 diverts the filtered filtrate into three grades and then flows into the ultra-clear filtrate tank 5 and the clear filtrate tank which are respectively arranged. 6 and a turbid filtrate pool 7, the multi-disc filter 4 is also connected to a broken paper concentration pool 8 for recovering and collecting concentrated pulp after multi-disc treatment through a pipeline; the turbid filtrate pool 7 is connected to a turbid filtrate pump 9 through a pipeline, and the turbid filtrate pump 9 recycles 100% of the turbid filtrate in the turbid filtrate pool 7 to the multi-disc filter 4 through a reflux pipeline, and repeatedly recycles and reuses it together with white water for multi-disc filtration; the ultra-clear filtrate pool 5 is connected to a low-pressure ultra-clear spray pump 10 and a low-pressure filter 11 which are arranged in sequence through a pipeline, and the low-pressure ultra-clear spray pump 10 pumps the ultra-clear filtrate filtered by the low-pressure filter 11 at low pressure to the wire part of the paper machine for low-pressure spraying of the wire part.

[0047] Continue as Figure 1As shown, the clear filtrate pool 6 is connected to a clear filtrate pump 12 and a multi-disc spray white water pump 13 through pipelines. The multi-disc spray white water pump 13 is connected to the multi-disc filter 4 through pipelines and pumps part of the white water in the clear filtrate pool 6 to the multi-disc filter 4 for pulp stripping spray and net washing spray of the multi-disc filter 4; the clear filtrate pump 12 is connected to a gravity filter 14 for resource recovery filtration and a white water tower 15 for storing white water through pipelines, and the white water tower 15 is connected to three white water pumps 150 through pipelines. The white water supplied by the clear filtrate tank 6 is pumped out separately for use in pulping and concentration adjustment of broken paper under the machine, for dilution and flushing of the slag remover and pressure screen, and for pulping and concentration adjustment of the pulp line; wherein, the clear filtrate tank 6 is also connected to a paper web flushing water pump 16 through a pipeline, and the white water required for paper web flushing is supplied to the broken paper flushing point of the couch roll through the paper web flushing water pump 16; a pulp return pipeline 17 is also connected between the gravity filter 14 and the turbid filtrate tank 7, which returns the pulp recovered and filtered by the gravity filter 14 to the turbid filtrate tank 7 for reuse.

[0048] Continue as Figure 1 As shown, the gravity filter 14 is connected to a first ultra-clear water tank 18 through a pipeline for collecting the filtrate generated after re-treatment. The first ultra-clear water tank 18 is respectively connected to a medium-pressure ultra-clear water pump 19 and a filler preparation ultra-clear water pump 20 through pipelines. The medium-pressure ultra-clear water pump 19 pumps the ultra-clear filtrate in the first ultra-clear water tank 18 to the wire section of the paper machine for medium-pressure spraying of the wire section. The filler preparation ultra-clear water pump 20 pumps the ultra-clear filtrate in the first ultra-clear water tank 18 to the filler preparation mixer for filler preparation water.

[0049] Continue as Figure 1 As shown, the first ultra-clear water tank 18 is also connected to a transfer ultra-clear water pump 21, a fine filter 22 and a second ultra-clear water tank 23 in sequence through pipelines. The transfer ultra-clear water pump 21 pumps the ultra-clear filtrate in the first ultra-clear water tank 18 to the fine filter 22. After filtering again, the filtrate is collected in the second ultra-clear water tank 23 for storage. Two slurry pumps 24 are also connected between the fine filter 22 and the turbid filtrate tank 7 through pipelines. The two slurry pumps 24 pump the filter residue produced by the fine filter 22 to the turbid filtrate tank 7 for reuse; in the water supply output to the outside of the second ultra-clear water tank 23, two high-pressure ultra-clear water pumps 25 for high-pressure spray pumping of the paper machine mesh part are connected through pipelines, and two low-pressure ultra-clear water pumps 26 for low-pressure spraying of the paper machine mesh part and the pressing part scraper and felt cloth for cleaning and lubrication are connected through pipelines. A chemical dilution ultra-clear water pump 27 for secondary pumping of water for online dilution of chemicals is also connected through pipelines.

[0050] In this embodiment, the filter residue produced by the gravity filter 14 and the fine filter 22 is returned to the turbid filtrate pool 7, so that the fiber recovery rate of the entire white water circulation system is high. After the white water is filtered by the combination of the gravity filter 14 and the fine filter 22, it can effectively replace the clean water used for the existing high-pressure spraying of the network pressure part and the secondary dilution of chemicals, thereby truly achieving the effect of saving water and reducing emissions.

[0051] In actual production, the gravity filter 14 is a RotoFlexTM1200 gravity filter produced by Kadant Johnson (Wuxi) Technology Co., Ltd. The mesh size of the filter is 150 mesh (100 microns). When the suspended solids content of the influent is ≤60ppm, the maximum processing capacity can reach 250m 3 / h, and the suspended solids content of the ultra-clear water in the first ultra-clear water tank 18 after being treated by the gravity filter 14 is ≤25ppm. The fine filter 22 is a product produced by Kadant Johnson (Wuxi) Technology Co., Ltd. The fine filter 22 contains 15 filter discs with a filtration accuracy of 1-20 microns, and the imported SS content is ≤25ppm. No chemicals need to be added, no slurry layer is required, and no vacuum water leg is required; the maximum allowable water inlet is 220m 3 / h, filtrate volume 150-187m 3 / h, the filtrate enters the 2# ultra-clear water tank, and the ultra-clear water suspended matter content in the second ultra-clear water tank 23 after being treated by the fine filter 22 is ≤10ppm, which meets the requirements of replacing clean water and can ensure that the 0.9mm nozzle in the papermaking industry is not blocked.

[0052] In this embodiment, the white water circulation system of the coated white cardboard corresponds to the three-stage filtration and recovery method of white water, such as Figure 1 As shown, the following steps are included:

[0053] S1, the mixed white water pump 2 pumps the white water from the white water tank 1 under the paper machine through the pipeline, and the broken paper high-concentration cleaner 3 supplies the deslagging cushion slurry through the pipeline, and after mixing at a certain concentration, enters the multi-disc filter 4 through the pipeline for graded filtration;

[0054] S2. After being processed by the multi-disc filter 4, the concentrated pulp enters the broke paper concentration tank 8, and then is refined and mixed into the core layer of the white cardboard in a certain proportion;

[0055] S3, the white water after being treated by the multi-disc filter 4 is divided into three levels: turbid filtrate, clear filtrate and ultra-clear filtrate, and flows into the ultra-clear filtrate pool 5, the clear filtrate pool 6 and the turbid filtrate pool 7 through pipelines respectively;

[0056] S4, the ultra-clear filtrate pool 5 pumps the ultra-clear filtrate after low-pressure filtration to the wire part of the paper machine through the low-pressure ultra-clear spray pump 10 and the low-pressure filter 11 for low-pressure spraying of the wire part;

[0057] S5, a part of the filtrate in the clear filtrate pool 6 is supplied with white water required for paper web flushing to the broken paper flushing point of the couch roll through the paper web flushing water pump 16;

[0058] S6, a part of the filtrate in the clear filtrate pool 6 is pumped to the multi-disc filter 4 through the multi-disc spray white water pump 13, and is used for pulp stripping spray and screen washing spray of the multi-disc filter 4;

[0059] S7, the turbid filtrate pool 7 is pumped to the multi-disc filter 4 through the turbid filtrate pump 9 and the reflux pipeline to recycle 100% of the turbid filtrate in the turbid filtrate pool 7, and repeatedly recycled and reused with the white water for multi-disc filtration;

[0060] S8, another part of the filtrate in the clear filtrate pool 6 is supplied to the gravity filter 14 for resource recovery filtration and the white water tower 15 for storing white water through the clear filtrate pump 12, and the gravity filter 14 returns the recovered filtered slurry to the turbid filtrate pool 7 for reuse through the slurry return pipeline 17;

[0061] S9, the white water tower 15 is connected to three white water pumps 150 through pipelines, and the white water supplied from the clear filtrate pool 6 is pumped out respectively for use in pulping and concentration adjustment of broken paper under the machine, for dilution and flushing of the slag remover and pressure screen, and for pulping and concentration adjustment of the pulp line;

[0062] S10, the filtrate produced after being processed again by the gravity filter 14 is collected in the first ultra-clear water tank 18;

[0063] S11, the first ultra-clear water tank 18 pumps a portion of the ultra-clear filtrate to the wire section of the paper machine through the medium-pressure ultra-clear water pump 19 for medium-pressure spraying of the wire section;

[0064] S12, the first ultra-clear water tank 18 pumps a portion of the ultra-clear filtrate to the filler preparation mixer through the filler preparation ultra-clear water pump 20 for filler mixing;

[0065] S13, the first ultra-clear water tank 18 is also connected to a transfer ultra-clear water pump 21 and a fine filter 22 in sequence through pipelines. The transfer ultra-clear water pump 21 pumps the ultra-clear filtrate in the first ultra-clear water tank 18 to the fine filter 22. After re-filtration, the filtrate is collected and stored in the second ultra-clear water tank 23, and the filter residue is pumped to the turbid filtrate tank 7 for reuse through two slurry pumps 24;

[0066] S14, a portion of the ultra-clear filtrate from the second ultra-clear water tank 23 is supplied to the wire section of the paper machine through two high-pressure ultra-clear water pumps 25 for high-pressure spraying of the wire section;

[0067] S15, a portion of the ultra-clear filtrate from the second ultra-clear water tank 23 is supplied to the wire section and the press section of the paper machine through the low-pressure ultra-clear water pump 26, and is used for low-pressure spraying to clean and lubricate the scrapers and felts of the wire section and the press section;

[0068] S15, another part of the ultra-clear filtrate in the second ultra-clear water tank 23 is used as water for online chemical dilution through the chemical dilution ultra-clear water pump 27;

[0069] S16. The white water is filtered through a combination of the gravity filter 14 and the fine filter 22 to replace the clean water used for high-pressure spraying of the network pressure part and secondary dilution of chemicals, thereby achieving graded filtration and recycling of the white water.

[0070] In this embodiment, three-stage filtration by equipment such as a multi-disc filter 4, a gravity filter 14 and a fine filter 22 is used to achieve the reuse of white water after three-stage filtration and classification, which not only improves the recovery efficiency of available fibers, but also allows the ultra-clear water generated and stored in the second ultra-clear water tank 23 after being processed by the fine filter 22 to be graded and reused in different sections of the paper machine, thereby meeting the requirement of replacing existing clean water, effectively reducing the consumption of clean water per ton of paper in papermaking production, and effectively achieving energy conservation and consumption reduction in the papermaking industry.

[0071] The above-described embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. Except for the cases listed in the specific embodiments, all equivalent changes made according to the shape, structure and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A white water circulation system for coating white cardboard, used for graded filtration and recycling of white water, characterized in that: It includes a white water tank under the paper machine wire, a mixed white water pump, a broke paper high-concentration cleaner and a multi-disc filter. The white water tank under the paper machine wire is used to receive the white water filtered out of the mixed paper machine wire part and the press part. The broke paper high-concentration cleaner is used to supply the cushion pulp after the cleaning. The mixed white water pump pumps out the white water in the white water pool under the paper machine through the pipeline, and mixes it with the cushion slurry after deslagging supplied by the broke high-concentration deslagging device through the pipeline to a certain concentration, and then supplies it to the multi-disc filter through the pipeline for graded filtration; The multi-disc filter separates the filtered filtrate into three levels and then flows into the ultra-clear filtrate pool, the clear filtrate pool and the turbid filtrate pool which are respectively arranged; The turbid filtrate pool is connected to a turbid filtrate pump through a pipeline, and the turbid filtrate pump recycles 100% of the turbid filtrate in the turbid filtrate pool back to the multi-disc filter through a reflux pipeline, and repeatedly recycles and reuses it together with white water for multi-disc filtration; The ultra-clear filtrate pool is connected to a low-pressure ultra-clear spray pump and a low-pressure filter arranged in sequence through a pipeline, and the low-pressure ultra-clear spray pump pumps the ultra-clear filtrate after low-pressure filtration to the wire part of the paper machine for low-pressure spraying; The clear filtrate pool is connected to a clear filtrate pump and a multi-disc spray white water pump through pipelines, and the multi-disc spray white water pump is connected to the multi-disc filter through pipelines, and the water in the clear filtrate pool is recycled to the multi-disc filter for pulp stripping spray and screen washing spray; The clear filtrate pump is connected to a gravity filter for resource recovery filtration and a white water tower for storing white water through pipelines. The white water tower is connected to at least three white water pumps through pipelines to pump out the white water supplied by the clear filtrate pool for use as water for pulping and concentration adjustment of broken paper under the machine, for dilution and flushing of the slag remover and pressure screen, and for pulping and concentration adjustment of the pulp line. The gravity filter is connected to a first ultra-clear water tank for collecting the filtrate generated after the second treatment through a pipeline, and the first ultra-clear water tank is respectively connected to a medium-pressure ultra-clear water pump and a filler preparation ultra-clear water pump through pipelines, the medium-pressure ultra-clear water pump pumps the ultra-clear filtrate in the first ultra-clear water tank to the medium-pressure spray of the wire part of the paper machine, and the filler preparation ultra-clear water pump pumps the ultra-clear filtrate in the first ultra-clear water tank to the filler preparation mixer for use as filler preparation water; The first ultra-clear water tank is also connected to a transfer ultra-clear water pump, a fine filter and a second ultra-clear water tank in sequence through pipelines. The transfer ultra-clear water pump pumps the ultra-clear filtrate in the first ultra-clear water tank to the fine filter, and after filtering the residue again, it is collected in the second ultra-clear water tank for storage. The white water after fine filtration in the second ultra-clear water tank is pumped out by multiple ultra-clear water pumps for high-pressure spraying water for the paper machine wire part, low-pressure spraying water for the paper machine wire part and the pressing part, and water for online dilution of chemicals.

2. A white water circulation system for coating white cardboard according to claim 1, characterized in that: The multi-disc filter is also connected to a broken paper concentration tank through a pipeline for recovering and collecting concentrated pulp after being processed by the multi-discs.

3. A white water circulation system for coating white cardboard according to claim 1, characterized in that: The clear filtrate pool is also connected to a paper web flushing water pump through a pipeline, and the paper web flushing water pump supplies white water required for paper web flushing to the broken paper flushing point of the couch roll.

4. A white water circulation system for coating white cardboard according to claim 1, characterized in that: A slurry return pipeline is also connected between the gravity filter and the turbid filtrate pool, for returning the slurry recovered and filtered by the gravity filter to the turbid filtrate pool for reuse.

5. The white water circulation system for coating white cardboard according to claim 1, characterized in that: At least two slurry pumps are connected between the fine filter and the turbid filtrate pool through a pipeline, and the two slurry pumps pump the filter residue filtered by the fine filter to the turbid filtrate pool for recycling.

6. A white water circulation system for coating white cardboard according to claim 1, characterized in that: The second ultra-clear water tank is connected to at least two high-pressure ultra-clear water pumps for high-pressure spray pumping of paper machine wire section through pipelines, and the second ultra-clear water tank is connected to at least two low-pressure ultra-clear water pumps for low-pressure spray pumping of paper machine wire section and press section scraper and felt cleaning and lubrication through pipelines. The second ultra-clear water tank is also connected to a chemical dilution ultra-clear water pump for secondary pumping of water for online dilution of chemicals through pipelines.

7. The three-stage filtering and recycling method for white water of a white water circulation system for coating white cardboard according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. The mixed white water pump pumps the white water from the white water pool under the paper machine through the pipeline, and supplies the white water to the deslagging cushion slurry through the pipeline with the broke high-concentration deslagging device. After mixing at a certain concentration, the mixed white water enters the multi-disc filter through the pipeline for graded filtration. S2. After filtering by the multi-disc filter, the concentrated pulp enters the broke concentration tank, and then is refined and mixed into the core layer of white cardboard in a certain proportion; S3. The white water after being treated by the multi-disc filter is divided into three levels: turbid filtrate, clear filtrate and ultra-clear filtrate, and flows into the ultra-clear filtrate pool, the clear filtrate pool and the turbid filtrate pool respectively through pipelines; S4, the ultra-clear filtrate pool pumps the ultra-clear filtrate after low-pressure filtration to the wire part of the paper machine for low-pressure spraying through a low-pressure ultra-clear spray pump and a low-pressure filter; S5. A part of the filtrate in the clear filtrate pool is supplied with white water required for paper web flushing to the broken paper flushing point of the couch roll through the paper web flushing water pump; S6. A portion of the filtrate in the clear filtrate pool is recycled to the multi-disc filter through the multi-disc spray white water pump for pulp stripping spray and screen washing spray; S7, the turbid filtrate pool recycles 100% of the turbid filtrate in the turbid filtrate pool back to the multi-disc filter through the turbid filtrate pump and the reflux pipeline; S8. Another part of the filtrate in the clear filtrate pool is supplied to the gravity filter for resource recovery filtration and the white water tower for storing white water through the clear filtrate pump. The gravity filter returns the recovered filtered slurry to the turbid filtrate pool for reuse through the slurry return pipeline. S9, white water tower is connected to three white water pumps through pipelines, and white water supplied from the clear filtrate pool is pumped out respectively for use in pulping and concentration adjustment of broken paper under the machine, for dilution and flushing of the slag remover and pressure screen, and for pulping and concentration adjustment of the pulp line; S10, the filtrate produced after being treated again by the gravity filter is collected in the first ultra-clear water tank; S11, the first ultra-clear water tank pumps a portion of the ultra-clear filtrate to the medium-pressure spraying of the wire part of the paper machine through the medium-pressure ultra-clear water pump; S12, the first ultra-clear water tank uses a filler preparation ultra-clear water pump to pump a portion of the ultra-clear filtrate to the filler preparation mixer for use as filler preparation water; S13, the first ultra-clear water tank is also connected to a transfer ultra-clear water pump and a fine filter in sequence through pipelines, the transfer ultra-clear water pump pumps the ultra-clear filtrate in the first ultra-clear water tank to the fine filter, and the filtrate is collected and stored in the second ultra-clear water tank after re-filtration, and the filter residue is pumped to the turbid filtrate tank for recycling through two slurry pumps; S14, a portion of the ultra-clear filtrate from the second ultra-clear water tank is supplied to the wire section of the paper machine through two high-pressure ultra-clear water pumps for high-pressure spraying of the wire section; S15, a portion of the ultra-clear filtrate in the second ultra-clear water tank is supplied to the wire section and the press section of the paper machine through a low-pressure ultra-clear water pump for low-pressure spraying to clean and lubricate the scrapers and felts in the wire section and the press section; S15, another part of the ultra-clear filtrate in the second ultra-clear water tank is used as water for online chemical dilution through the chemical dilution ultra-clear water pump; S16. The white water is filtered through a combination of a gravity filter and a fine filter to replace the clean water used for high-pressure spraying of the network pressure part and secondary dilution of chemicals, thereby achieving graded filtration and recycling of the white water.

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