CN115445290A - Method for reducing moisture content of filter cake of pressure filter - Google Patents
Method for reducing moisture content of filter cake of pressure filter Download PDFInfo
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- CN115445290A CN115445290A CN202211108950.7A CN202211108950A CN115445290A CN 115445290 A CN115445290 A CN 115445290A CN 202211108950 A CN202211108950 A CN 202211108950A CN 115445290 A CN115445290 A CN 115445290A
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- 239000012065 filter cake Substances 0.000 title claims abstract description 111
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000001035 drying Methods 0.000 claims abstract description 242
- 238000005406 washing Methods 0.000 claims abstract description 120
- 238000007599 discharging Methods 0.000 claims abstract description 39
- 238000001914 filtration Methods 0.000 claims abstract description 34
- 239000002002 slurry Substances 0.000 claims abstract description 20
- 239000010413 mother solution Substances 0.000 claims abstract description 3
- 239000000706 filtrate Substances 0.000 claims description 169
- 239000007789 gas Substances 0.000 claims description 91
- 239000007788 liquid Substances 0.000 claims description 75
- 239000012452 mother liquor Substances 0.000 claims description 51
- 239000011261 inert gas Substances 0.000 claims description 5
- 125000006850 spacer group Chemical group 0.000 claims description 4
- 238000009835 boiling Methods 0.000 claims description 2
- 238000004891 communication Methods 0.000 claims description 2
- 238000011010 flushing procedure Methods 0.000 claims description 2
- 239000011268 mixed slurry Substances 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 238000000926 separation method Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000007664 blowing Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- 238000001704 evaporation Methods 0.000 description 5
- 230000008020 evaporation Effects 0.000 description 4
- 238000007670 refining Methods 0.000 description 3
- 239000000835 fiber Substances 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000011085 pressure filtration Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/06—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums
- B01D33/073—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums arranged for inward flow filtration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/58—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element
- B01D33/60—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for washing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/58—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element
- B01D33/62—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying
- B01D33/66—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying by gases or by heating
- B01D33/663—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying by gases or by heating by direct contact with a fluid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/80—Accessories
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/80—Accessories
- B01D33/804—Accessories integrally combined with devices for controlling the filtration
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Filtration Of Liquid (AREA)
Abstract
The invention relates to a method for reducing the moisture content of a filter cake of a pressure filter, wherein the pressure filter comprises a filtering unit, a washing unit, a primary drying unit, a secondary drying unit and a discharging unit, and the method comprises the following steps: step 1, conveying the slurry to a filtering unit for filtering and separating to obtain a filter cake and a mother solution; step 2, conveying the filter cake obtained in the step 1 to a washing unit for washing; step 3, conveying the filter cake washed in the step 2 to a primary drying unit and a secondary drying unit in sequence for drying; step 4, conveying the filter cake subjected to secondary drying in the step 3 to a discharging unit for discharging; the primary drying unit dries the filter cake by adopting gas with fixed pressure, and the secondary drying unit dries the filter cake by adopting gas with fixed flow. The method can obviously reduce the consumption of the drying gas, reduce the moisture content of the filter cake and greatly reduce the energy consumption.
Description
Technical Field
The invention relates to the technical field of refining unit PTA pressure filters in PTA production and preparation, in particular to a method for reducing the moisture content of a PTA pressure filter.
Background
PTA is the main raw material for producing polyester fiber, resin, film and container resin, and is widely applied to the fields of chemical fiber, container, packaging, film production and the like. In recent years, the PTA process is rapidly developed, so that the PTA pressure filtration technology is rapidly developed, the technology integrates filtration, washing and pre-drying into a whole, and the flow of a PTA refining unit is greatly simplified and shortened. The pre-drying greatly reduces the moisture content in the filter cake, and the pre-drying is continuous and stable, thereby greatly reducing the load of a downstream drying section; the PTA pressure filtering technology adopts the processes of 1-stage filtering, 1-2-stage washing, 1-2-stage drying and discharging, slurry is pressurized by a pump and enters a filter, filtering is firstly carried out, the filtered slurry enters a washing area for washing after the filtering is finished, the dried slurry enters a drying area for drying after the washing is finished, and the dried slurry enters a discharging area for discharging after the drying is finished. However, due to the influence of drying media and times and the influence of a control mode, residual liquid in a drum filtrate pipeline cannot be discharged in time, so that the blanking moisture content of filter cakes is obviously higher, and the load of a downstream drying section is increased.
Disclosure of Invention
The invention mainly aims to provide a method for reducing the moisture content of a filter cake of a pressure filter, so as to overcome the defect that the moisture content of the filter cake obtained by using the pressure filter is higher in the prior art.
In order to achieve the above object, the present invention provides a method for reducing the moisture content of a filter cake of a filter press comprising a filtering unit, a washing unit, a primary drying unit, a secondary drying unit and a discharge unit, the method comprising the steps of:
step 1, conveying the slurry to a filtering unit for filtering and separating to obtain a filter cake and a mother solution;
step 2, conveying the filter cake obtained in the step 1 to a washing unit for washing;
step 3, conveying the filter cake washed in the step 2 to a primary drying unit and a secondary drying unit in sequence for drying;
step 4, conveying the filter cake subjected to secondary drying in the step 3 to a discharging unit for discharging;
the primary drying unit dries the filter cake by adopting gas with fixed pressure, and the secondary drying unit dries the filter cake by adopting gas with fixed flow.
The method for reducing the moisture content of the filter cake of the pressure filter is characterized in that the pressure of the gas with fixed pressure is 0.2-0.6Mpa, and the volume flow of the gas with fixed flow is 50-1000Nm 3 /h。
The method for reducing the moisture content of the filter cake of the pressure filter comprises a mother liquor chamber, a washing filtrate chamber, a primary drying filtrate chamber and a secondary drying filtrate chamber, wherein the mother liquor is conveyed to the mother liquor chamber through a pipeline, the washing filtrate is conveyed to the washing filtrate chamber through a pipeline, the primary drying filtrate is conveyed to the primary drying filtrate chamber through a pipeline, and the secondary drying filtrate is conveyed to the secondary drying filtrate chamber through a pipeline.
The invention relates to a method for reducing the moisture content of filter cakes of a pressure filter, wherein the pressure filter further comprises a raffinate chamber, the raffinate chamber comprises a liquid discharge port, and the step 4 comprises the following steps: and conveying the filter cake after secondary drying to a discharging unit, discharging secondary drying filtrate remained in the pipeline through a liquid outlet of the residual liquid cavity, then discharging gas from a discharging gas port on the side of the control head into a filtrate pipeline, and performing back flushing discharging on the filter cake.
The invention relates to a method for reducing the moisture content of a filter cake of a pressure filter, wherein the pressure filter comprises a frame, a rotary drum and a control head, the rotary drum is arranged between the frame and the control head, the rotary drum rotates relative to the frame and the control head, the frame comprises a filtering unit, a washing unit, a primary drying unit, a secondary drying unit and a discharging unit, the control head comprises a mother liquor chamber, a washing filtrate chamber, a primary drying filtrate chamber, a secondary drying filtrate chamber and a residual liquor chamber, and the filtering unit, the washing unit, the primary drying unit, the secondary drying filtrate chamber and the discharging unit are respectively arranged in one-to-one correspondence with the mother liquor chamber, the washing filtrate chamber, the primary drying filtrate chamber, the secondary drying filtrate chamber and the residual liquor chamber.
The method for reducing the moisture content of the filter cake of the pressure filter comprises the steps that the filter cake is formed in a rotary drum unit, pipelines are arranged at positions of the rotary drum corresponding to any one of a mother liquor chamber, a washing filtrate chamber, a primary drying filtrate chamber, a secondary drying filtrate chamber and a raffinate chamber, so that the mother liquor is conveyed to the mother liquor chamber through the pipelines, the washing filtrate is conveyed to the washing filtrate chamber through the pipelines, the primary drying filtrate is conveyed to the primary drying filtrate chamber through the pipelines, the secondary drying filtrate is conveyed to the secondary drying filtrate chamber through the pipelines, and the secondary drying filtrate remained in the pipelines is conveyed to the raffinate chamber.
The method for reducing the moisture content of the filter cake of the pressure filter comprises the steps that a filtering unit, a washing unit, a primary drying unit, a secondary drying unit and a discharging unit are respectively separated through a separation block, and a mother liquor chamber, a washing filtrate chamber, a primary drying filtrate chamber, a secondary drying filtrate chamber and a residual liquid chamber are respectively separated through the separation block.
The method for reducing the moisture content of the filter cake of the pressure filter is characterized in that the gas is inert gas, other gas or steam.
The method for reducing the moisture content of the filter cake of the pressure filter is characterized in that the number of the liquid discharge ports is at least one.
The method for reducing the moisture content of the filter cake of the pressure filter comprises the steps that a washing unit comprises a primary washing unit and a secondary washing unit, and the filter cake in the step 1 is sequentially conveyed to the primary washing unit and the secondary washing unit for washing.
The invention relates to a method for reducing the moisture content of filter cakes of a pressure filter, wherein a washing liquid entering a washing unit chamber adopts a high-temperature liquid, and the high-temperature liquid means that the liquid temperature is higher than the standard boiling point.
The invention has the beneficial effects that:
1. the invention adopts two-stage drying, the first stage of drying adopts a pressure control mode, liquid in a filter cake is pressed out by gas with fixed pressure based on the filtering principle, and meanwhile, on the pressure setting detail, the washing liquid in adjacent regions can be prevented from leaking to a primary drying region, so that the load of primary drying is reduced, and the moisture content of a product is reduced; the second-stage drying adopts a flow control mode, and adopts large-flow gas to bring out liquid in a filter cake under the action of pressure; the aim of reducing the moisture content of the filter cake can be achieved on the premise of consuming less total gas by adopting two different drying control modes.
2. According to the invention, the liquid outlet is arranged in the residual liquid chamber, so that secondary drying filtrate and tail gas which are not completely discharged in a pipeline connected with the discharging unit can be discharged in time through the liquid outlet after secondary drying, and the secondary drying filtrate and tail gas cannot flow back again along with back blowing gas to enter a dried filter cake, thereby reducing the moisture content of the filter cake.
3. According to the invention, the backpressure is set in the drying gas liquid tank, so that on one hand, the discharged high-temperature liquid can be prevented from flashing, on the other hand, the backpressure is set, the pressure difference before and after drying is controlled, and the situations that the gas is distributed unevenly and the gas is locally short-circuited in the drying process that the drying gas penetrates through the filter cake are avoided, so that the moisture content of the filter cake is reduced, and the drying effect is improved.
4. The invention adopts the washing water with the temperature of more than 140 ℃, can ensure that the temperature of the filter cake is about 140 ℃, thereby evaporating partial liquid by pressure relief and flash evaporation in the discharging area, reducing the moisture content of the filter cake and improving the drying effect.
5. The invention improves the pre-drying technology of the pressure filter from the aspects of process flow, control mode and equipment structure, thereby obviously reducing the consumption of drying gas, reducing the moisture content of filter cakes and greatly reducing the energy consumption.
Drawings
FIG. 1 is a schematic view showing a process for reducing the moisture content of a cake in a pressure filter according to an embodiment of the present invention.
FIG. 2 is a simplified schematic diagram of a pressure filter according to an embodiment of the present invention.
Wherein, the reference numbers:
1-pressure filter
2-mother liquor tank
3-washing filtrate tank
4-dry gas-liquid tank
5-mother liquor pump
6-washing filtrate pump
7-Dry filtrate pump
8-residual liquid tank
9-primary drying air control valve
10-secondary drying air control valve
11-frame
12-filtration Unit
13-mother liquor Chamber
14-spacer Block
15-spacer block
16-control head
17-one-time washing unit
18-spacer block
19-Primary Wash filtrate Chamber
20-Secondary washing Unit
21-spacer block
22-Secondary Wash filtrate Chamber
23-spacer block
24-spacer block
25-Primary drying Unit
26-Primary drying filtrate Chamber
27-pipe line
28-spacer block
29-spacer block
30-Secondary drying Unit
31-Secondary drying filtrate chamber
32-spacer block
33-spacer block
34-discharge Unit
35-residual liquid Chamber
36-spacer block
37-spacer block
38-liquid discharge port
Detailed Description
The following examples of the present invention are described in detail, and the present invention is carried out on the premise of the technical scheme of the present invention, and detailed embodiments and procedures are given, but the scope of the present invention is not limited to the following examples, and the following examples are experimental methods without specific conditions noted, and generally follow conventional conditions.
The invention provides a method for reducing the moisture content of a filter cake of a pressure filter, wherein the pressure filter comprises a filtering unit, a washing unit, a primary drying unit, a secondary drying unit and a discharging unit, and the method comprises the following steps:
step 1, conveying PTA slurry to a filtering unit for filtering and separating to obtain a filter cake and a mother liquor;
step 2, conveying the filter cake obtained in the step 1 to a washing unit for washing;
step 3, conveying the filter cake washed in the step 2 to a primary drying unit and a secondary drying unit in sequence for drying;
step 4, conveying the filter cake after secondary drying in the step 3 to a discharging unit for discharging;
the primary drying unit dries the filter cake by adopting gas with fixed pressure, and the secondary drying unit dries the filter cake by adopting gas with fixed flow.
The pressure filter adopts two-stage drying, the first stage of drying adopts a pressure control mode, and based on the filtering principle, liquid in a filter cake is pressed out by gas with fixed pressure, so that the moisture content of a product is reduced; the second stage drying adopts a flow control mode, and adopts large-flow gas to bring out liquid in a filter cake under the action of pressure; the aim of reducing the moisture content of the filter cake can be achieved on the premise of consuming less total gas by adopting two different drying control modes.
The present invention is not particularly limited to the type of slurry, and may be any slurry as long as it is a suspension of solid and liquid, for example, PTA slurry. The invention is not particularly limited to the specific structure of the pressure filter, for example, the pressure filter commonly used in the field, the pressure filter comprises a filtering unit, a washing unit, a primary drying unit, a secondary drying unit and a discharging unit, slurry is conveyed to the filtering unit for filtering and separating to form a filter cake, and then the filter cake sequentially passes through the washing unit, the primary drying unit, the secondary drying unit and the discharging unit.
The primary drying unit of the present invention employs a fixed pressure gas to dry through the filter cake, in one embodiment, a fixed pressure gasThe pressure of the gas is 0.2-0.6Mpa; the secondary drying unit of the invention dries the filter cake with a fixed flow of gas, in one embodiment a fixed flow of gas having a volumetric flow rate of 50-1000Nm 3 H is used as the reference value. The invention can achieve the drying purpose and further reduce the consumption of the drying gas by optimizing the pressure and the flow, for example, the gas quantity is saved by 20 percent compared with the gas with fixed pressure or the gas with fixed flow used in the two drying processes.
The drying gas is not particularly limited in the present invention, and may be, for example, an inert gas, other gas such as compressed air, or steam; the gas may be a normal temperature gas or a high temperature gas. The drying gas used in the primary drying unit and the secondary drying unit of the present invention may be the same or different, and the present invention is not particularly limited.
In one embodiment, the PTA pressure filter comprises a frame, a rotary drum and a control head, wherein the frame is a cylindrical hollow structure and is divided into a plurality of areas along the circumferential direction, namely a filtering unit, a washing unit, a primary drying unit, a secondary drying unit and a discharging unit, and two adjacent units are separated by a separation block. The rotating drum is of a cylindrical hollow structure, the control head is of a cylinder, the rotating drum is arranged between the frame and the control head and rotates relative to the frame and the control head, and the rotating drum is sleeved on the control head and the frame. The control head is divided into a plurality of areas along the circumferential direction, namely a mother liquid chamber, a washing filtrate chamber, a primary drying filtrate chamber, a secondary drying filtrate chamber and a residual liquid chamber, two adjacent chambers are spaced by a spacer block, and the mother liquid chamber, the washing filtrate chamber, the primary drying filtrate chamber, the secondary drying filtrate chamber and the residual liquid chamber are respectively arranged in one-to-one correspondence with the filtering unit, the washing unit, the primary drying unit, the secondary drying unit and the discharging unit.
Wherein, the PTA slurry forms a filter cake in the rotary drum after passing through the frame, and the mother liquor enters a mother liquor chamber of the control head after passing through the rotary drum. The rotary drum is provided with a pipeline corresponding to any one of a mother liquor chamber, a washing filtrate chamber, a primary drying filtrate chamber, a secondary drying filtrate chamber and a residual liquid chamber, so that the mother liquor is conveyed to the mother liquor chamber through the pipeline, the washing filtrate is conveyed to the washing filtrate chamber through the pipeline, the primary drying filtrate is conveyed to the primary drying filtrate chamber through the pipeline, the secondary drying filtrate is conveyed to the secondary drying filtrate chamber through the pipeline, and the secondary drying filtrate remained in the pipeline is conveyed to the residual liquid chamber.
In detail, the liquids flowing through the zone of the drum corresponding to the mother liquor chamber are all transported to the mother liquor chamber through the pipeline, the liquids flowing through the zone of the drum corresponding to the washing filtrate chamber are all transported to the washing filtrate chamber through the pipeline, the liquids flowing through the zone of the drum corresponding to the primary drying filtrate chamber are all transported to the primary drying filtrate chamber through the pipeline, and the liquids flowing through the zone of the drum corresponding to the secondary drying filtrate chamber are all transported to the secondary drying filtrate chamber through the pipeline. In one embodiment, the pipeline is arranged on an inner cylinder of the rotary drum which is in contact with the control head.
The filter press of the invention leads each area filter cake of the rotary drum to pass through a filtering unit, a washing unit, a primary drying unit, a secondary drying unit and a discharging unit in turn by the rotation of the rotary drum, and pipelines connected with the rotary drum can also pass through mother liquor, washing filtrate, primary drying filtrate and secondary drying filtrate in turn. When a certain area of filter cake in the rotary drum rotates to a position corresponding to the discharging unit and the residual liquid cavity, residual liquid of secondary drying filtrate can be stored in a pipeline connected with the rotary drum in the area.
The number of the liquid discharge ports is not particularly limited in the present invention, and may be one or more than one as long as the ports are provided in the residual liquid chamber.
In one embodiment, the filter press of the present invention further comprises a mother liquid tank, a washing filtrate tank and a drying gas liquid tank. The mother liquor tank is communicated with the mother liquor chamber so as to convey the mother liquor to the mother liquor tank through the mother liquor chamber; the wash filtrate tank is in communication with the wash filtrate chamber to deliver wash filtrate through the wash filtrate chamber to the wash filtrate tank; the drying gas liquid tank is communicated with the primary drying filtrate chamber and the secondary drying filtrate chamber so as to convey the primary drying filtrate and the secondary drying filtrate to the drying gas liquid tank through the primary drying filtrate chamber and the secondary drying filtrate chamber. In another embodiment, the dry gas fluid reservoir can set a backpressure, on one hand, the flash evaporation of the discharged high-temperature liquid can be avoided, on the other hand, the backpressure is set, the differential pressure before and after drying is controlled, the situation that dry gas penetrates through a filter cake in the drying process, the gas distribution is uneven, and the local short circuit of the gas occurs is avoided, so that the moisture content of the filter cake is reduced, and the drying effect is improved.
In one embodiment, the pressure filter of the present invention further comprises a residual liquid tank communicated with the residual liquid chamber for conveying the secondary drying filtrate remaining in the pipeline to the residual liquid tank through a liquid outlet of the residual liquid chamber.
In one embodiment, the washing unit of the present invention comprises a primary washing unit and a secondary washing unit, and the step 1 filter cake is sequentially transferred to the primary washing unit and the secondary washing unit for washing. Accordingly, the washing filtrate chamber comprises a primary washing filtrate chamber into which the primary washing filtrate flows and a secondary washing filtrate chamber into which the secondary washing filtrate flows.
In one embodiment, the method for reducing the moisture content of filter cake of a pressure filter is used for reducing the moisture content of the filter cake formed by PTA slurry, and comprises the following steps as shown in figure 1 and figure 2:
(1) The PTA slurry in the PTA slurry tank enters a pressure filter 1 through the pressurization of a slurry pump, enters a filtering unit 12 through a feeding area of a frame 11 of the pressure filter 1 for filtering and separation to respectively obtain mother liquor, pipeline residual mother liquor (the mother liquor residual in a pipeline 27) and filter cakes, and the filter cakes are formed on a rotary drum; the mother liquor passing through the rotary drum enters the mother liquor tank 2 through a mother liquor chamber 13 of a control head 16 of the pressure filter 1 and is output through a mother liquor pump 5 connected with the mother liquor tank 2; the line residual mother liquor enters the next chamber of the control head 16 as the drum rotates, i.e. the primary wash filtrate chamber 19.
(2) The filter cake is conveyed to a primary washing unit 17, primary washing water is pressurized by a washing water pump and enters the primary washing unit 17 of the frame 11 for washing, and primary washing filtrate, primary washing filtrate remained in a pipeline and a filter cake after primary washing are respectively obtained; the primary washing filtrate flowing through the rotary drum enters the washing filtrate tank 3 through the primary washing filtrate chamber 19 of the control head 16 and is output through the washing filtrate pump 6 connected with the washing filtrate tank 3; the line residual primary wash filtrate enters the next chamber of the control head 16, the secondary wash filtrate chamber 22, as the drum rotates.
(3) With the rotation of the rotary drum, the filter cake after the primary washing is conveyed to a secondary washing unit 20, secondary washing water enters the secondary washing unit 20 of the frame 11 through the pressurization of a washing water pump for washing, and secondary washing filtrate, pipeline residual secondary washing filtrate and secondary washed filter cake are obtained respectively; the secondary washing filtrate enters the washing filtrate tank 3 through the secondary washing filtrate chamber 22 of the control head 16 and is output through the washing filtrate pump 6 connected with the washing filtrate tank 3; the secondary wash filtrate remaining in the line enters the next chamber of the control head as the drum rotates, the primary dry filtrate chamber 26.
(4) With the rotation of the rotary drum, conveying the filter cake after the secondary washing to a primary drying unit 25 for primary drying, and allowing the pressurized drying gas to enter the primary drying unit 25 of the frame 11 through a primary drying gas control valve 9 to obtain primary drying filtrate, primary drying tail gas, primary drying filtrate remained in the pipeline, primary drying tail gas remained in the pipeline and filter cake after primary drying; the primary drying filtrate and the primary drying tail gas enter the drying gas liquid tank 4 through the primary drying filtrate chamber 26 of the control head 16; the pipeline residual primary drying filtrate and the pipeline residual primary drying tail gas enter the next chamber of the control head 16 along with the rotation of the rotary drum, namely a secondary drying filtrate chamber 31.
Wherein, the drying gas can be inert gas, other gas or steam; the control mode of the primary drying control valve 9 adopts pressure control, and the primary drying control valve is set to ensure that the pressure of the drying gas is the same as that of the adjacent secondary washing unit 20 or slightly higher than that of the secondary washing unit 20, so that the liquid in the secondary washing unit 20 cannot leak to the primary drying unit 20 under the action of differential pressure, and the work load of the primary drying unit 20 is reduced; the drying gas liquid tank 4 can be set with back pressure, so that the discharged high-temperature drying gas liquid can not be subjected to flash evaporation, and meanwhile, the short circuit when the drying gas penetrates through a filter cake can not occur, and the drying effect is improved.
(5) With the rotation of the rotary drum, the filter cake after primary drying is conveyed to a secondary drying unit 30, the drying gas with pressure enters the secondary drying unit 30 of the frame 11 through a secondary drying gas control valve 10 to carry out secondary drying, and secondary drying filtrate, secondary drying tail gas, secondary drying filtrate residual in the pipeline, secondary drying tail gas residual in the pipeline and filter cake after secondary drying are respectively obtained; the secondary drying filtrate and the secondary drying tail gas enter the drying gas liquid tank 4 through the secondary drying filtrate chamber 31 of the control head 16; the secondary drying filtrate remained in the pipeline and the secondary drying tail gas remained in the pipeline enter the next chamber of the control head 16, namely a residual liquid chamber 35 along with the rotation of the rotary drum, and are discharged through a liquid discharge port 38 on the residual liquid chamber 35.
Wherein, the drying gas medium can be inert gas or other gases; the control mode of the secondary drying air control valve 10 adopts flow control, the drying air flow of the control valve is set, the residual filtrate in the filter cake is brought out by using large drying air flow, and the liquid content in the filter cake is reduced; the drying gas liquid tank 4 is provided with back pressure, so that the discharged high-temperature drying gas liquid can not flash, short circuit when the drying gas penetrates through a filter cake can not occur, and the drying effect is improved; the liquid discharge port 38 discharges the secondary drying filtrate remained in the pipeline and the secondary drying tail gas remained in the pipeline, so that the phenomenon that the secondary drying filtrate remained in the pipeline and the secondary drying tail gas remained in the pipeline are reversely blown back to the filter cake under the action of the unloading gas and the back blowing gas is avoided, the liquid content in the filter cake is increased, and the moisture content of the filter cake is increased.
(6) After the secondary drying is finished, along with the rotation of the rotary drum, the filter cake enters the discharging unit 34 of the frame 11, discharging gas and back blowing gas enter from the discharging gas port and the back blowing gas port of the control head 16 to carry out back blowing on the filter cake, and the filter cake is discharged to downstream equipment to be output.
In one embodiment, spacer blocks 14, 18, 23, 28, 33, 37 divide frame 11 into filtration unit 12, primary wash unit 17, secondary wash unit 20, primary drying unit 25, secondary drying unit 30, and discharge unit 34. The control head 16 is divided into a mother liquor chamber 13, a primary washing filtrate chamber 19, a secondary washing filtrate chamber 22, a primary drying filtrate chamber 26, a secondary drying filtrate chamber 31 and a residual liquor chamber 35 by a separation block 15, a separation block 21, a separation block 24, a separation block 29, a separation block 32 and a separation block 36. The isolation blocks 14, 18, 23, 28, 33 and 37 are arranged in one-to-one correspondence with the isolation blocks 15, 21, 24, 29, 32 and 36.
In one embodiment, the primary drying air control valve 9 and the secondary drying air control valve 10 are one of a pneumatic control valve, an electric control valve, or other valves having a regulation control function.
The washing water can be washing water with the temperature of more than 140 ℃, so that the temperature of the filter cake can be ensured to be about 140 ℃, and partial liquid is evaporated out by pressure relief and flash evaporation in the discharging area, thereby reducing the moisture content of the filter cake and improving the drying effect.
The invention provides a method for reducing the moisture content of a filter cake of a pressure filter, which is particularly suitable for PTA slurry and can be used in a pressure filtering process of a PTA slurry refining unit. The invention is characterized in that the pre-drying technology of the pressure filter is improved from three aspects of process flow, control principle and equipment structure through calculation, thereby obviously reducing the consumption of drying gas, reducing the moisture content of filter cakes and greatly reducing the energy consumption. By adopting the method, the moisture content in the obtained filter cake can be further reduced to be within 7.5wt% from the previous 10wt%, and the method has obvious effect.
The method is not only suitable for PTA slurry, but also suitable for separating and predrying other solid-liquid mixed slurry.
The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A method for reducing the moisture content of the filter cake of a pressure filter, which is characterized in that the pressure filter comprises a filtering unit, a washing unit, a primary drying unit, a secondary drying unit and a discharging unit, and the method comprises the following steps:
step 1, conveying the slurry to a filtering unit for filtering and separating to obtain a filter cake and a mother solution;
step 2, conveying the filter cake obtained in the step 1 to a washing unit for washing;
step 3, conveying the filter cake washed in the step 2 to a primary drying unit and a secondary drying unit in sequence for drying;
step 4, conveying the filter cake subjected to secondary drying in the step 3 to a discharging unit for discharging;
the primary drying unit dries the filter cake by adopting gas with fixed pressure, and the secondary drying unit dries the filter cake by adopting gas with fixed flow.
2. The method for reducing the moisture content of the filter cake of a pressure filter according to claim 1, wherein the pressure of said gas of fixed pressure is 0.2-0.6Mpa and the volumetric flow rate of said gas of fixed flow rate is 50-1000Nm 3 H; and/or the washing liquid entering the washing unit adopts high-temperature liquid, and the temperature of the high-temperature liquid is higher than the standard boiling point.
3. The method for reducing the moisture content of a filter cake of a pressure filter according to claim 1, wherein the pressure filter further comprises a mother liquor chamber, a washing filtrate chamber, a primary drying filtrate chamber and a secondary drying filtrate chamber, the mother liquor is transported to the mother liquor chamber through a filtrate line, the washing filtrate is transported to the washing filtrate chamber through a filtrate line, the primary drying filtrate is transported to the primary drying filtrate chamber through a filtrate line, and the secondary drying filtrate is transported to the secondary drying filtrate chamber through a filtrate line.
4. A method for reducing the moisture content of a filter cake in a pressure filter according to claim 3, wherein the pressure filter further comprises a raffinate chamber, said raffinate chamber comprising a drain, said step 4 being: and conveying the filter cake after secondary drying to a discharging unit, discharging secondary drying filtrate remained in a filtrate pipeline through a liquid outlet of the residual liquid cavity, and then discharging gas from a discharging gas port at the side of the control head into a filtrate pipeline to perform back flushing discharging on the filter cake.
5. A method for reducing the moisture content of a filter cake in a filter press according to claim 4, wherein the filter press comprises a frame, a drum and a control head, the drum being arranged between the frame and the control head, the drum being rotatable relative to the frame and the control head, the frame comprising a filter unit, a washing unit, a primary drying unit, a secondary drying unit and a discharge unit, the control head comprising a mother liquor chamber, a washing filtrate chamber, a primary drying filtrate chamber, a secondary drying filtrate chamber and a raffinate chamber, the filter unit, the washing unit, the primary drying unit, the secondary drying unit and the discharge unit being arranged in one-to-one correspondence with the mother liquor chamber, the washing filtrate chamber, the primary drying filtrate chamber, the secondary drying filtrate chamber and the raffinate chamber, respectively.
6. The method of claim 5, wherein the filter cake is formed in a drum unit, the drum is provided with a pipeline at a position corresponding to any one of the mother liquor chamber, the wash filtrate chamber, the primary dry filtrate chamber, the secondary dry filtrate chamber and the raffinate chamber, so that the mother liquor is transported to the mother liquor chamber through the pipeline, the wash filtrate is transported to the wash filtrate chamber through the pipeline, the primary dry filtrate is transported to the primary dry filtrate chamber through the pipeline, the secondary dry filtrate is transported to the secondary dry filtrate chamber through the pipeline, and the secondary dry filtrate remaining in the pipeline is transported to the raffinate chamber.
7. The method for reducing the moisture content of the filter cake of a pressure filter according to claim 1, wherein the filtration unit, the washing unit, the primary drying unit, the secondary drying unit and the discharge unit are separated by a spacer, and the mother liquor chamber, the washing filtrate chamber, the primary drying filtrate chamber, the secondary drying filtrate chamber and the raffinate chamber are separated by a spacer.
8. The method for reducing the moisture content of a filter cake of a pressure filter according to claim 1, wherein the gas is an inert gas, another gas or steam; the method is used for separating solid-liquid mixed slurry; the washing unit comprises a primary washing unit and a secondary washing unit, and the filter cake in the step 1 is sequentially conveyed to the primary washing unit and the secondary washing unit for washing.
9. The method for reducing the moisture content of filter cake of a pressure filter according to claim 4, wherein the number of said liquid discharge ports is at least one.
10. The method for reducing the moisture content of a filter cake of a pressure filter according to claim 3, wherein the pressure filter further comprises a mother liquor tank, a washing filtrate tank and a drying gas liquid tank; the mother liquor tank is communicated with the mother liquor chamber so as to convey the mother liquor to the mother liquor tank through the mother liquor chamber; the wash filtrate tank is in communication with the wash filtrate chamber to deliver wash filtrate to the wash filtrate tank through the wash filtrate chamber; the drying gas liquid tank is communicated with the primary drying filtrate chamber and the secondary drying filtrate chamber so as to convey the primary drying filtrate and the secondary drying filtrate to the drying gas liquid tank through the primary drying filtrate chamber and the secondary drying filtrate chamber; the dry gas tank sets a back pressure.
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