RU2156639C1 - Method and press-filter for dehydration of aqueous suspension - Google Patents

Abstract

FIELD: filtration engineering. SUBSTANCE: in a method of dehydration of aqueous suspension including filtration in press-filter, washing of the bulk of precipitate, blowing of the filter routes with pressurized gas, and drying of the bulk of precipitate, washing and drying of precipitate are performed over a shortest way through the bulk of precipitate. Press-filter has plates with cavities on both sides, between which filter cloth and filtrate-withdrawal manifolds are disposed, one of the latter being connected through at least one conduit to cavity space only on one side of each plate and the other to cavity space only on the other side of each plate. Manifolds are interconnected over pipes and with cut-off means. EFFECT: reduced raw material uptake, especially in case of suspensions of water-soluble substances such as sugar. 7 cl, 6 dwg

Description

 The invention relates to filtering technology, to methods and devices used for dewatering aqueous suspensions, and can be used in food, chemical, petrochemical and other industries.

 A known method of dewatering an aqueous suspension, including filtering, drying the sludge by exposure to pressure from the pressing chambers and unloading the sludge (description of the patent of the Russian Federation N 2097103, IPC B 01 D 25/164, publ. 27.11.97, bull. N 33).

 A known method of dehydration of aqueous suspensions, implemented in a device for separating suspensions according to the patent of the Russian Federation N 2040948, IPC B 01 D 25/12, publ. 08/09/95, bull. N 22. The method includes filtering and drying the precipitate by pressure using plates and frames. The specified method does not exclude the loss of nutrients remaining in the sediment and in the structural elements of the filter press.

 Known filter press containing plates with a filter cloth placed between them, a collector for draining the filtrate with feed channels made in the plates, a line for supplying a suspension with valves for draining the suspension and washing water (A.S. USSR No. 1717176, class B 01 D 25/12, 1992).

 The known method and device do not provide savings in raw materials and do not increase the yield of nutrients due to the lack of a number of technological operations and modes.

 The problem to which the claimed invention is directed is the creation of a method and device that provides savings in raw materials and increases the yield of nutrients.

 The technical result is to reduce losses, especially water-soluble nutrients in the filtrate.

 The specified technical result is achieved by the fact that in the method of dewatering an aqueous suspension, which includes filtering in a filter press, washing the sediment thickness, purging the filter lines with gas pressure and drying the sediment thickness by applying a gas flow to it, washing and drying the precipitate is carried out along the shortest path through the sediment thickness .

 In addition, before the start of filtration, the filter is flushed with the direction of the wash to prepare the suspension.

 In addition, before filtering, the filter is flushed with a regenerating solution.

 In addition, the sediment is dried by pressure up to 0.6 MPa for 4.. . 10 minutes, purging of the filter lines is carried out with a pressure of up to 0.6 MPa for 4 ... 5 seconds, washing of the precipitate is carried out at a maximum water pressure of 0.6 MPa for 5 ... 20 minutes.

 The filter press that implements the inventive method includes chamber plates with filter cloth placed between them, a collector for draining the filtrate with supply channels made in the plates, a line for supplying a suspension with valves for draining the suspension and washing water, and a line for supplying washing water, characterized the fact that it is equipped with an additional collector for drainage of the filtrate, the plates are made with recesses on both sides, while one collector is connected by at least one channel with a volume of recesses of only about the other side of each plate, and the other with the recess volume only on the other side of each plate, the suspension supply line is equipped with an air release valve, the washing water supply line is equipped with an air supply valve and is connected to at least one collector for exhaust the filtrate and both collectors are connected to each other by pipes with the possibility of separation.

 In FIG. 1 shows a general view of the filter; in FIG. 2 - a plate of a filter press; in FIG. 3 is a section along BB in FIG. 1; in FIG. 4 is a section along AA in FIG. 1; in FIG. 4 shows a section through a filter in washing mode; in FIG. 5 - in purge mode; in FIG. 6 - in the drying mode.

 The filter press consists of chamber plates 1 (Figs. 1 and 2) with filter cloth 2 fixed on them. Blind cavities are made on both sides of the chamber plates 3. Suspension supply lines 4 and filtrate discharge collectors 5 and 6, respectively, are connected to volumes recesses with channels 7 on one side of each plate and channels 8 on the other side of each plate. The minimum number of channels on one side of each plate is at least one. The slurry supply lines 4 are equipped with shutoff valves. At the inlet, a suspension supply valve 9 is installed, and a solution supply valve 10 for regeneration, a valve 11 for draining the liquid when washing the filter, and an air discharge valve 12 for purging are installed on the outlets of the line. The end of the line is equipped with a valve 13 air supply for purging. The filtrate discharge manifolds 5 and 6 are connected by pipes to the isolation valves 14, 15 and 16, and are also connected to the air supply lines by a valve 17, a water supply valve 18 for washing the sludge and a water supply valve 19 for washing the filter and discharging the regenerating solution. The filtrate drain manifolds are provided with a drying gas vent valve 20 and a residual regenerating solution valve 21. Chamber plates 1 are combined into a single filter press structure using power communication plates 22 and 23. The precipitate 24 separated by the filter cloth 2 is placed in the chambers formed by the opposite recesses 3 of the adjacent plates 1.

 The claimed method is implemented as follows.

 First, the aqueous suspension is filtered in a chamber filter press, then the precipitate is washed, directing the washing liquid through the thickness of the sediment. At the end of the flushing, the filter press lines are purged with gas pressure and the contents of the lines are returned to the suspension accumulator. After purging the lines, the precipitate is dried by directly applying gas to it. Before filtering begins, the filter is washed with the direction of the wash to prepare the suspension. Periodically, before the start of filtration, the filter is flushed with a regenerating solution. Recommended sediment drying modes: pressure - up to 0.6 MPa for 4 ... 10 minutes. When purging the filter lines, the pressure is up to 0.6 MPa for 4 ... 5 seconds. When washing the sediment: the maximum water pressure of 0.6 MPa for 5 ... 20 minutes.

 The filter press operates as follows.

 In the filtration mode (Fig. 1.3), valves 9, 14 and 16 are opened, while the suspension is fed directly to the line 4, and from it to the chambers formed by the chamber plates 1. The solid component of the suspension is retained by the filter cloth 2, and the filtrate through the channels 7 and 8 enters the collectors 5 and 6, and from there through valves 15 and 16 to the filtrate collector (not shown).

 In the washing mode (Fig. 1,4), the valves 15 and 18 are open, and through the valve 18, the washing liquid passes through the manifold 6, channels 8 into the chambers. Then it passes along the shortest path through the thickness of sediment 24 and then through channels 7 and collector 5, then through valve 15 to a filtrate collector (not shown). The washing liquid may be directed through valve 20 to prepare a suspension.

 In purge mode (Fig. 1,5), valve 12 and valve 13 are open. The gas pressure through valve 13 is distributed along line 4 and removes sediment and residual slurry that accumulate there through valve 12 and enter the suspension accumulator (not shown).

 In the drying mode (Fig. 1,6), the valve 17 and the valve 20 open. The gas pressure through the valve 17 acts through the collectors 6 and channels 8 directly on the sediment 24. The gas is released through the valve 20.

 After drying the sediment, the chambers are emptied and the filter rinsing mode is performed, for which valves 18, 14 and 11 are opened. The washing liquid through the collectors 5 and 6, channels 7 and 8 enters the filter press chambers. It seeps in countercurrent through the filter cloth 2, washing away the impurities from it, and then through the suspension supply line 4, valve 11 enters the suspension.

 In the regeneration mode of the filter cloth, the valves 10, 14 and 19 are open, while through the valve 10 a regenerating solution is supplied, which enters the filter press chambers through line 4, washes the fabric 2, dissolving its impurities and carries them through channels 7 and 8, one way through the manifold 5 through the valve 14 to the valve 19, the other way through the collector 6 to the valve 19. At the end of the regeneration mode, the remnants of the regenerating solution are drained from the filter press through the valve 21.

 The claimed inventions can reduce the consumption of feedstock for filtering, especially when cleaning suspensions of water-soluble substances, such as sugar in the sugar industry. The use of a similar method in the processing of sugar beets can reduce the loss of sugar in the saturation sediment from 0.15 to 0.02% by weight of beets.

Claims (7)

 1. A method of dewatering an aqueous suspension, including filtering in a filter press, washing the thickness of the sediment, purging the filter lines with gas pressure and drying the thickness of the sediment by exposing it to a gas stream, characterized in that the washing and drying of the precipitate is carried out along the shortest path through the thickness of the sediment.  2. The method according to claim 1, characterized in that before starting the filtration, the filter is rinsed with the direction of the rinse to prepare the suspension.  3. The method according to claim 1 or 2, characterized in that before filtering, the filter is washed with a regenerating solution.  4. The method according to any one of claim 1, 2 or 3, characterized in that the precipitate is dried by pressure up to 0.6 MPa for 4 ... 10 minutes  5. The method according to any one of claim 1, 2, 3 or 4, characterized in that the purge of the filter lines is carried out with a pressure of up to 0.6 MPa for 4 ... 5 s.  6. The method according to any one of claim 1, 2, 3, 4 or 5, characterized in that the washing of the precipitate is carried out at a maximum water pressure of 0.6 MPa for 5 ... 20 minutes.  7. A filter press containing plates with a filter cloth placed between them, a collector for draining the filtrate with supply channels made in the plates, a line for supplying a suspension with valves for draining the suspension and washing water, and a line for supplying washing water, characterized in that it is equipped with an additional collector for drainage of the filtrate, the plates are made with recesses on both sides, while one collector is connected by at least one channel with the volume of the recesses on only one side of each plate, and the other with the volume of the recesses is only on the other side of each plate, the suspension supply line is equipped with an air release valve, the washing water supply line is equipped with an air supply valve and is connected to at least one collector to discharge the filtrate, and both collectors are connected to one another pipes with the possibility of separation.

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