Alkali liquor filtering device

Abstract

The utility model relates to the field of regenerated cellulose filament dipping technology, in particular to an alkali liquor filtering device which comprises a pore filter, and a filtering tow net is arranged in the pore filter. The filtering tow net is of a multi-layer compact structure composed of soft fibers and can be tightened through a tightening device arranged at the top of the pore filter, so that pores are further reduced, the filtering precision is improved, the high-pressure resistance of the filtering tow net is enhanced, and high-pressure filtering is achieved; the device disclosed by the utility model has an extremely good deep effect and can intercept particles which can reach 5 microns; high-pressure filtration is adopted, and the filtration flow is 3-4 times that of low-pressure filtration; by adopting the filtering system disclosed by the utility model, the occupied area of the filter can be greatly reduced, and the equipment construction and maintenance cost is saved.

Description

Technical Field

[0001] The utility model relates to the field of regenerated cellulose filament impregnation technology, in particular to an alkali solution filtering device. Background Art

[0002] The domestic regenerated cellulose fiber industry generally uses the impregnation process for viscose preparation, and the impregnation alkali liquor recycling process is still adopted during the impregnation process; in the production process, the cellulose alkali liquor treatment process is the first step in manufacturing viscose fiber. During the preparation of viscose, the pulp is first impregnated with a sodium hydroxide aqueous solution with a concentration of about 25%. During the impregnation process, a small amount of alkali liquor participates in the reaction, and most of the alkali liquor is adopted and impregnated to form a porridge for pressing, so that the cellulose is converted into alkali cellulose, hemicellulose is dissolved, and the degree of polymerization is partially reduced; after pressing, the excess alkali liquor is filtered clean and enters the mixing barrel to be mixed with newly added concentrated alkali, desalted water, etc. to a suitable concentration for the next round of impregnation process. The alkali liquor cannot be fully utilized, resulting in waste. Therefore, in the production process of viscose fiber, a large amount of high-concentration alkali liquor rich in hemicellulose, also known as pressing liquid, is generated; in order to reduce production costs, reduce alkali consumption, and protect the environment, alkali recycling must be carried out.

[0003] With the improvement of production environmental protection and energy-saving standards, industry competition is becoming more and more fierce, and the production cost and quality requirements of products are also getting higher and higher. As a result, the demand for new filtration technologies with larger filtration capacity and lower use costs is particularly urgent. In order to reduce production costs, reduce alkali consumption and protect the environment, alkali recovery must be carried out. A lot of research has been carried out on the purification of alkali press liquid. The existing technology mainly uses nanofiltration separation technology to separate alkali liquor from hemicellulose to achieve alkali liquor reuse. For example, plate and frame and microporous filtration are used for pretreatment. After nanofiltration separation, an alkali liquor with a hemicellulose content of 5-8g / L and a cellulose content of 240g / L is obtained. The alkali liquor meets the reuse requirements and the process realizes alkali recovery, but the production consumables and nanofiltration membrane costs are high, resulting in poor economic benefits. Utility Model Content

[0004] The purpose of the utility model is to provide an alkaline solution filtering device with large filtering capacity, high filtering efficiency, and excellent environmental protection and economic benefits.

[0005] Based on the above purpose, the present invention adopts the following technical solutions:

[0006] A alkali solution filtering device comprises a porous filter, wherein the porous filter is provided with an alkali inlet, the alkali inlet is connected to the sewage outlet of the mixing barrel through an alkali inlet pipe, and an alkali inlet valve is provided on the alkali inlet pipe; the porous filter is provided with an alkali outlet, the alkali outlet is connected to the feed port of the mixing barrel through an alkali outlet pipe, and an alkali outlet valve is provided on the alkali outlet pipe; a filtering structure is provided in the porous filter, the filtering structure comprises a filtering wire mesh composed of a plurality of filtering wire bundles; a pollution cleaning structure is provided on the porous filter, and a discharge pipe is provided in cooperation with the pollution cleaning structure.

[0007] Preferably, the bottom ends of the filter bundles are fixedly arranged at the bottom of the porous filter, and the top ends are connected to a tightening device.

[0008] Preferably, the tightening device includes a cylinder arranged at the top outer side of the pore filter, and a rack is fixedly provided on the piston rod of the cylinder; a gear is provided in cooperation with the rack, and the gear is fixedly provided on a tightening cover provided at the top end of the pore filter; the tightening cover is rotatably matched with the pore filter, and the bottom end of the tightening cover extends into the inner side of the pore filter, and the top end of the filter bundle is connected to the bottom end of the tightening cover.

[0009] Preferably, the porous filter is divided into an inner cavity and an outer cavity by a filter tow mesh, the alkali outlet is arranged at the bottom of the inner cavity, and the alkali inlet is arranged on the side wall of the outer cavity.

[0010] Preferably, the cleaning structure includes a backwash mechanism, which includes a backwash pipe connected to the alkali outlet; the cleaning structure includes a compressed air pipe, one end of the compressed air pipe is connected to the air compressor, and the other end is connected to the outer cavity of the pore filter; a backwash water inlet valve is provided on the backwash pipe, and a compressed air valve is provided on the compressed air pipe.

[0011] Preferably, a discharge pipe is provided at the top of the outer cavity of the pore filter, and the other end of the discharge pipe is connected to the ditch; a backwash drain valve is provided on the discharge pipe.

[0012] Preferably, the alkali outlet of the pore filter is connected to a forward wash drain pipe, which is connected to a recovery tank, and a forward wash drain valve and a recovery pump are sequentially provided on the forward wash drain pipe; the recovery tank is connected to a waste liquid tank through a pipeline, and a recovery pump is provided between the recovery tank and the waste liquid tank.

[0013] The beneficial effects of the utility model include:

[0014] The utility model is equipped with a filter tow net composed of flexible fiber filaments as the filter material, which has an excellent depth effect. According to experimental tests, it can intercept particles with a diameter of up to 5 microns. It also uses soft and tough tow as the filter material, has a long service life, is easy to replace, and has good adaptability to changes in the clarity of the squeezed liquid.

[0015] The utility model is provided with a tightening device, which can effectively improve the high-pressure resistance of the filter bundle, so that it will not be broken down under high-pressure filtration, thereby realizing high-pressure filtration; the filtration flow of the utility model is 3-4 times that of traditional low-pressure filtration. The filtration system made by the alkali liquid circulation filtration process can replace 7-8 traditional alkali liquid plate and frame filters, effectively reducing the equipment footprint and saving a lot of equipment construction, maintenance and labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of the alkali solution filtration process of Example 1 of the present utility model;

[0017] Figure 2 This is a schematic diagram of the structure of the porous filter according to Example 1 of the present utility model;

[0018] Figure 3 This is a schematic structural diagram of the tightening device of Example 1 of the present utility model.

[0019] In the figure: mixing barrel 1; circulation pump 2; alkali inlet valve 3; pore filter 4; alkali inlet 41; filter tow net 42; tightening cover 43; alkali outlet 44; compressed air outlet 45; discharge outlet 46; sewage outlet 47; gear 48; cylinder 5; rack 51; alkali outlet valve 6; plate and frame filter 7; backwash inlet valve 8; compressed air valve 9; backwash drain valve 10; forward wash drain valve 11; recovery pump 12; recovery tank 13; waste liquid tank 14. DETAILED DESCRIPTION

[0020] Example 1

[0021] The following is a further explanation of the present invention in conjunction with specific embodiments. Figure 1 As shown, this embodiment is an alkali liquid filtering device and an alkali liquid filtering system constructed based on the alkali liquid filtering device.

[0022] The impregnation liquid after joint impregnation and squeezing is returned to the mixing tank 1. At this time, the sodium hydroxide concentration is usually 200-260g / L, and the hemicellulose content varies according to the different raw materials, up to 40g / L, usually 20-35g / L, and the turbidity of the alkali solution is around 40; the circulation pump 2 discharges the impregnation liquid in the mixing tank 1 into the pore filter 4 through the alkali inlet valve 3, and operates at an operating pressure of 0.1-0.45Mpa and a temperature of 35-45℃.

[0023] The structure of the pore filter 4 is as follows Figure 2As shown, the outer shell of the machine body can be made of materials such as stainless steel or carbon steel coated with epoxy resin; a filter wire mesh 42 is arranged inside it; the filter wire mesh 42 is made of a large number of soft and tough fiber filaments, and its overall structure is cylindrical, with a diameter of about 1m and is provided with three layers; the filter wire mesh divides the interior of the pore filter 4 into two chambers, namely the inner cavity inside the filter wire mesh 42 and the outer cavity outside the filter wire mesh 42; an alkali inlet 41 is provided on the side wall of the pore filter 4, and the alkali inlet 41 is connected to the alkali inlet pipe, which is the entrance for the impregnation liquid to enter the pore filter 4; the alkali inlet 41 is connected to the outer cavity, so that the impregnation liquid enters the outer cavity first after entering the pore filter 4.

[0024] A tightening device is provided on the top of the pore filter 4, and the tightening device includes a tightening cover 43; the tightening cover 43 is rotatably connected to the outer shell of the pore filter 4, and is coaxially arranged with the outer shell of the pore filter 4 so that it can rotate around the central axis; the bottom of the tightening cover 43 extends into the interior of the pore filter 4 and is connected to the filter wire mesh 42. When the tightening cover 43 rotates, it will also drive the filter wire mesh 42 to rotate together, tightening it to improve the high-pressure resistance of the filter wire mesh, and reduce the pores between the wire bundles to improve its filtering accuracy.

[0025] like Figure 3 As shown, a gear 48 is sleeved on the outside of the tightening cover 43, and a rack 51 is provided in cooperation with the gear 48; the rack 51 is fixedly set at the end of the piston rod of a cylinder 5, and the length direction of the rack 51 is the same as the stroke direction of the cylinder 5, so that it can slide along the length direction while the piston rod is telescoping; because the rack 51 and the gear 48 are engaged with each other, when the rack 51 slides, it will drive the gear 48 to rotate, and then drive the tightening cover 43 to rotate and tighten the filter mesh 42; a protective cover is provided outside the gear 48; the cylinder 5 is a double-acting cylinder and is provided with two air inlets; in order to ensure the smooth operation of the cylinder 5, a special solenoid valve and a sufficiently thick compressed air pipe must be provided for the cylinder 5.

[0026] After the impregnation liquid is filtered through the filter mesh 42, the hemicellulose is retained and concentrated; the alkali solution in the filtered liquid is discharged from the alkali outlet 44 provided at the bottom of the inner cavity of the pore filter 4. Figure 1 As shown, after passing through an alkali outlet valve 6, it is discharged back into the mixing barrel 1 through the alkali outlet pipe to be recycled; in this embodiment, suspended particles with a particle size of 5 microns can be filtered. For suspended particles with a particle size less than 5 microns, the processing efficiency can be improved by increasing the squeezing force, replacing finer fiber filaments, or adding flocculants.

[0027] The pore filter 4 in this embodiment is provided with a cleaning structure, including a backwash mechanism and a forward wash mechanism; the backwash mechanism includes a backwash water inlet pipe connected to the alkali outlet 44; a backwash water inlet valve 8 is provided on the backwash water inlet pipe. When backwashing is required, the alkali outlet valve 6 is closed and the backwash water inlet valve 8 is opened to perform backwashing into the pore filter 4; a discharge port 46 is also provided on the outer cavity of the pore filter 4, and the discharge port 46 is connected to the ditch through a discharge pipe. A backwash drain valve 11 is provided on the discharge pipe; when backwashing, the backwash drain valve 11 is opened to discharge the backwash water from the discharge port 46 to the ditch; a compressed air port 45 is also provided on the outer cavity, and the compressed air port 45 is connected to an air compressor through a compressed air pipe. Compressed air can be passed into the outer cavity during backwashing to assist backwashing; a compressed air valve 9 is provided on the compressed air pipe, which is opened during backwashing and closed during normal filtration; the low-concentration alkali solution and hemicellulose concentrate produced by backwashing are recovered into the pre-filtration alkali storage tank for re-filtration treatment.

[0028] The backwash is controlled by two signals. One is a time control signal sent by the timer of the filter controller to perform backwashing at a fixed time. The other is a pressure signal monitored by pressure transmitters respectively installed on the alkali inlet and outlet pipes. When the pressure difference between the two chambers inside the pore filter 4 reaches the set value, the backwash operation can also be started. The filter controller controls the timing of each step according to the results of on-site debugging. During the backwash process, the cylinder 5 is reversed at the same time to expand the pores of the filter tow mesh 42 to facilitate backwashing. The action time and number of cylinder 5 will affect the backwash effect. These two parameters are also determined by on-site debugging. Each backwash lasts about 2 minutes, and the backwash water consumption is 0.5%-2% of the treated water volume.

[0029] In this embodiment, a traditional plate and frame filter 7 is also provided, and valves are provided at its inlet and outlet. When the pore filter 4 is undergoing backwashing, the inlet and outlet valves of the plate and frame filter 7 can be opened to maintain the continuous operation of the entire filtering mechanism.

[0030] In this embodiment, a forward washing mechanism is further provided on the pore filter 4, including a forward washing drain pipe connected to the alkali outlet 44; a forward washing drain valve 11 is provided on the forward washing drain pipe, and the other end of the forward washing drain pipe is connected to the recovery tank 13 through a recovery pump 12; the recovery tank 13 is then connected to the waste liquid tank 14 through a recovery valve and a recovery pump in turn; during forward washing, the alkali outlet valve 6 is closed and the forward washing drain valve 11 is opened, and flushing water is introduced from the alkali inlet 41, then enters the inner cavity through the filter tow mesh 42, and is then discharged from the alkali outlet 44, and the waste water is discharged through the forward washing drain pipe; a sewage outlet 47 is also provided at the bottom of the outer cavity of the pore filter 4, which is controlled by a sewage valve to discharge the waste water in the outer cavity during forward washing.

[0031] Example 2

[0032] The technical solution used in this embodiment is substantially the same as that in embodiment 1, the main difference being that a plate and frame filter 7 is not provided in this embodiment, but two porous filters 4 are provided in parallel; the two porous filters operate simultaneously and are automatically controlled by a PLC control system; the backwashing of the porous filters is interlocked with subsequent equipment, and two porous filters 4 are not allowed to be backwashed simultaneously to ensure continuous operation of the filters.

[0033] Example 3

[0034] The technical solutions used in this embodiment are substantially the same as those used in Example 2, with the difference being that, in this embodiment, 100 cubic meters of hemicellulose pressed liquid are introduced, the sodium hydroxide concentration in the feed is 230 g / L, and the hemicellulose concentration is 25 g / L; the liquid enters the pore filter 4 at a temperature of 37°C and is subjected to pore filter treatment at a pressure of 0.2 MPa; and the pore filter is backwashed according to changes in the filter inlet pressure and the filter outlet flow conditions to clean out the alkaline liquid impurities remaining on the filter tow mesh 42 and recover the impurities.

[0035] The above operation is automatically repeated according to the process parameter setting conditions of the pore filter until the concentration of the alkali solution treated by the pore filter remains unchanged; the turbidity of the alkali solution in this embodiment is finally controlled below 8ntu, meeting the production requirements of the squeezed alkali solution.

[0036] Example 4

[0037] The technical solutions used in this embodiment are substantially the same as those used in Example 3, with the difference being that, in this embodiment, 100 cubic meters of hemicellulose pressed liquid are introduced, the sodium hydroxide concentration in the feed is 260 g / L, and the hemicellulose concentration is 28 g / L; the liquid enters the pore filter 4 at a temperature of 40°C and is subjected to pore filter treatment at a pressure of 0.15 MPa; and the pore filter is backwashed according to changes in the filter inlet pressure and the filter outlet flow conditions to clean out the alkaline impurities remaining on the filter tow mesh 42 and recover the impurities.

[0038] The above operation is automatically repeated according to the process parameter setting conditions of the pore filter until the concentration of the alkali solution treated by the pore filter remains unchanged; the turbidity of the alkali solution in this embodiment is finally controlled below 12ntu, meeting the production requirements of the squeezed alkali solution.

[0039] Example 5

[0040] The technical solutions used in this embodiment are substantially the same as those used in Example 4, with the difference being that, in this embodiment, 100 cubic meters of hemicellulose pressed liquid are introduced, the sodium hydroxide concentration in the feed is 200 g / L, and the hemicellulose concentration is 20 g / L; the liquid enters the pore filter 4 at a temperature of 45°C, and is subjected to pore filter treatment at a pressure of 0.15 MPa; the number of filter layers of the pore filter tow is adjusted from 3 layers to 2 layers of tow, thereby reducing the filtration pressure and delaying the operation time of the pore filter; and the pore filter is backwashed according to changes in the filter inlet pressure and the filter outlet flow conditions to clean out the alkaline impurities remaining on the filter tow mesh 42 and recover them.

[0041] The above operation is automatically repeated according to the process parameter setting conditions of the pore filter until the concentration of the alkali solution treated by the pore filter remains unchanged; the turbidity of the alkali solution in this embodiment is finally controlled below 15ntu, which meets the production requirements of the squeezed alkali solution.

[0042] The above description is only a further explanation of the present invention in combination with specific embodiments. All descriptions do not limit the scope of protection of the present invention. Any changes or replacement solutions that can be easily thought of by any technician in this field within the technical scope disclosed by the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A alkali solution filtering device, comprising a pore filter, characterized in that: The porous filter is provided with an alkali inlet, which is connected to the sewage outlet of the mixing barrel through an alkali inlet pipe, and an alkali inlet valve is provided on the alkali inlet pipe; the porous filter is provided with an alkali outlet, which is connected to the feed port of the mixing barrel through an alkali outlet pipe, and an alkali outlet valve is provided on the alkali outlet pipe; a filtering structure is provided in the porous filter, and the filtering structure includes a filter bundle net composed of multiple filter bundles; a pollution cleaning structure is provided on the porous filter, and a discharge pipe is provided in cooperation with the pollution cleaning structure.

2. The alkali solution filtering device according to claim 1, characterized in that: The bottom ends of the filter bundles are fixedly arranged at the bottom of the pore filter, and the top ends are connected with a tightening device.

3. The alkali solution filtering device according to claim 2, characterized in that: The tightening device includes a cylinder arranged at the top outside the pore filter, and a rack is fixedly provided on the piston rod of the cylinder; a gear is provided in cooperation with the rack, and the gear is fixedly provided on the tightening cover provided at the top end of the pore filter; the tightening cover is rotatably matched with the pore filter, and the bottom end of the tightening cover extends into the inner side of the pore filter, and the top end of the filter bundle is connected to the bottom end of the tightening cover.

4. The alkali solution filtering device according to claim 1, characterized in that: The porous filter is divided into an inner cavity and an outer cavity by a filter wire mesh. The alkali outlet is arranged at the bottom of the inner cavity, and the alkali inlet is arranged on the side wall of the outer cavity.

5. The alkali solution filtering device according to claim 4, characterized in that: The cleaning structure includes a backwash mechanism, which includes a backwash pipe connected to the alkali outlet; the cleaning structure includes a compressed air pipe, one end of which is connected to the air compressor and the other end is connected to the outer cavity of the pore filter; a backwash water inlet valve is provided on the backwash pipe, and a compressed air valve is provided on the compressed air pipe.

6. The alkali solution filtering device according to claim 5, characterized in that: The discharge pipe is arranged on the top of the outer cavity of the pore filter, and the other end of the discharge pipe is connected to the ditch; a backwash drain valve is arranged on the discharge pipe.

7. The alkali solution filtering device according to claim 6, characterized in that: The alkali outlet of the pore filter is connected to a forward wash drain pipe, which is connected to a recovery tank. A forward wash drain valve and a recovery pump are sequentially provided on the forward wash drain pipe; the recovery tank is connected to a waste liquid tank through a pipeline, and a recovery pump is provided between the recovery tank and the waste liquid tank.

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