Safety analysis of the hottest filtration process

2022-10-18
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Safety analysis of filtration process

there are many kinds of filtration equipment with different structures. According to the different ways of generating pressure difference, it can be divided into gravity type, pressure (suction) filtration type and centrifugal type. Among them, the resolution of gravity filtration is an important parameter of the experimental machine, and the equipment is relatively simple. The following mainly introduces the pressure (suction) filtration and centrifugal filtration equipment

one pressure (suction) filtration equipment

(1) plate and frame filter press plate and frame filter press is an ancient but still widely used filtration equipment, which operates intermittently, and its filtration driving force is external pressure. It is composed of multiple filter plates and filter frames alternately arranged and assembled on the frame, as shown in Figure 8-7. The number of filter plates and frames can be adjusted according to the needs within the length of the base, and the filter area is generally 2 ~ 80m2

the structure of the filter plate and frame is shown in Figure 8-8. Round holes are opened at the four corner ends of the plate and frame. After assembly and compaction, four channels are formed for the circulation of filter slurry, filtrate and washing solution. During assembly, place the filter cloth with holes at the four corners at the junction of the plate and frame, and then use manual, electric or hydraulic transmission to compress the plate and frame. Figure 8-8 (b) shows a filter frame with an empty middle, which is used to accumulate filter residue. There is a dark hole in the round hole in the upper right corner of the filter frame, which is connected with the middle of the frame, from which the filter slurry enters the frame; Figure 8-8 (a) and figure 8-8 (c) are both filter plates, but their structures are different. Figure 8-8 (a) is called non washing plate, and figure 8-8 (c) is called washing plate. There are side holes in the round hole in the upper left corner of the washing plate, which are connected with both sides of the washing plate, from which the washing liquid enters the filter plate; The non washing plate has no such dark hole, and the washing liquid can only pass through the round hole and cannot enter the filter plate. The two sides of the filter plate are evenly provided with crisscross grooves, which can make the filtrate or washing liquid flow in it. In order to distinguish the three, marks such as small buttons are usually cast on the outside of the board and frame. For example, one button represents the washing board, two buttons represent the filter frame, and three buttons represent the non washing board. During assembly, the arrangement order of plates and frames is non washing plate frame washing plate frame non washing plate... Generally, both ends are non washing plates, which is usually the machine heads at both ends

during filtration, the suspension enters the filter frame through the dark hole at the corner of the filter frame through the slurry channel 1 under a certain pressure difference. The filtrate passes through the filter cloth on both sides respectively, and then collects through the adjacent grooves into the filtrate channel 3 for discharge. The solid phase is intercepted and formed into a filter cake in the frame, which can be washed after filtration. When washing, close the feed valve and filtrate discharge valve, and then put the washing hydraulic pressure into the washing solution inlet channel 2, enter the plate surfaces on both sides through the side holes at the corner of the washing plate, then wash the filter cake through a layer of filter cloth and the whole filter cake layer, and then pass through a layer of filter cloth, and then collect it from the recess of the non washing plate, enter the washing solution outlet channel and discharge it. After washing, loosen the pressing device, and then unload, wash, reload and enter the next round of operation

(2) rotary drum vacuum filter rotary drum vacuum filter is a continuous operation filtering equipment. As shown in Figure 8-9, its main part is a horizontal drum with a layer of metal on the surface to avoid scratching the objective lens, covering the filter cloth, and the lower part of the drum is immersed in the filter slurry. The rotating drum is divided into several fan-shaped grids that are not connected with each other along the radial direction, and the small holes on the end face of each grid are connected with the distribution head. With the function of the distribution head, during the rotation of the drum for one week, each grid can complete the filtration, washing, and slag unloading in the future

the distribution head is a key component, which is composed of a fixed disc and a rotating disc, as shown in figure 8-l0. The two are closely fitted by spring pressure. The rotating disc rotates with the drum, and its hole number and hole diameter are consistent with the small holes on the end face of the drum. The fixed disc is provided with five slots (or holes), slot 1 and slot 2 are respectively connected with the vacuum filtrate tank, slot 3 is connected with the vacuum washing tank, and hole 4 and hole 5 are respectively connected with the compressed air pipe. When any small hole on the rotating disc rotates for one cycle, it will be connected with the five slots (holes) on the fixed disc once, so as to complete different operations

 

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