?Structure and working principle of fast-opening diaphragm filter presses

Quick-opening diaphragm filter pressesIt is a kind of integrated separation equipment with machine, electricity and liquid, and the process includes: feeding, pressing, filtering, keeping pressure, pressing, blowing back, loosening, pulling plate, discharging and other processes. Quick openingdiaphragm filter pressThe mechanism includes five major components: frame, unloading mechanism, filtration system, hydraulic system, and electrical control. The frame connects the filtering mechanism and the pull plate mechanism, which is the necessary guarantee for the composition of the equipment. The unloading mechanism is mainly used to remove the filter cake. The filtration part is the core part of the equipment, using the feed pressure and filter cloth to achieve solid-liquid separation. The hydraulic part is the power source of the equipment, which can realise the operation of pressing, making up pressure and loosening. Electrical control is the control centre of the system, with frequency converter, PLC, various types of switches, relays, indicators and other components, is the necessary guarantee for the realization of the functions of the quick-opening diaphragm filter press.

When the diaphragm filter press works, the control system controls the related oil control valve to realise the oil control action, the rodless cavity of the hydraulic cylinder is injected with pressure oil, under the action of oil pressure, the piston rod extends to push the head plate forward to press the filter plate on the equipment, and the filter plate constitutes a sealed filter chamber between the filter plates, at the same time, the coal slurry is pushed by the feed pump, pumped into the filter chamber through the feed hole, and with the help of the pressure of feed pump to realise the separation of solid-liquid. Granularity smaller than the number of filter cloth mesh filtrate outflow, size larger than the number of filter cloth mesh particles remain in the filter chamber; with the continuous feeding, particles in the filter cloth gradually thickened and finally formed a cake, the sensor feedback signal, the system stops the feed pump feeding. The equipment performs the action of inflating the diaphragm filter plate, the volume of the chamber becomes smaller after the filter cloth expands and deforms, and the filter cake is pressed to reduce the water content of the cake. The unloading mechanism pulls off each part of the filter plate step by step, and the filter cake falls down to the conveyor system by its own gravity and the tension of the filter cloth, and then transported to the fine coal system, completing a working process.

The advantages of the filter press are as follows:

• Multi-hydraulic cylinder end face uniform compression, the formation of chamber sealing uniform, and effectively avoid the formation of uneven chamber sealing spray material.
• Adopting two feeding ports. The feeding speed is fast, which is conducive to uniform cloth and good cake forming effect.

The liquid resistance on the surface of the filter plate is small, the coal liquid is discharged smoothly, the filtration is more thorough and the number is fast.

• Fast and thorough discharging.

Fast-opening diaphragm filter press common faults and analysis

Fast-opening diaphragm filter press is widely used in coal processing plant, which effectively improves the production efficiency. In the process of using the fast filter press, some failures will occur due to operation, maintenance, design defects and other factors, mainly as follows.

The filter plate is easy to pull slant, fall off the road, proximity switch failure is high

Unloading action is relatively cumbersome, divided into three times to pull the plate, the number of unloading plate and pulling distance is long, the small chain between the plate pieces fall off, the number of inconsistencies between the two sides of the filter plate will appear the filter plate pulling slanting, off the road phenomenon. The unloading process needs to perform the operation of pulling the plate, the position control of the pulling plate is realised by touching the proximity switch. The three times pulling process needs 7 proximity switches, due to the electronic components are very susceptible to the influence of coal sludge and moisture. This part of the switch is very easy to fail.

Short filter cloth life

The original design of the filter cloth is fixed by the upper hanging cloth pin hole, and the filter cloth is fixed on the filter plate in two times by nylon rope, which causes serious wear and tear of the filter cloth.

runtime interruption

Equipment sometimes stop for no reason, through tracking observation, analysis concluded that due to the fast-opening diaphragm filter press into the feed tube for the steel ring rubber tube, steel ring feed tube in the process of bending will have elastic deformation, in the process of pressing, this deformation caused by the elasticity of the pressure will be on the compression plate to produce the force, due to the direction of the force and the cylinder provided by the opposite direction of the force, it will make the cylinder force becomes smaller, resulting in stopping the push-pin closing is not in place. The electric control system reports a stop and the operation is interrupted [3].

2 Fast-opening diaphragm filter press technology transformation programme

Aiming at the above several typical faults, combined with the actual situation of the site, the following technical transformation programme is proposed.

Use of the pulling plate trolley to realise the pulling plate action, reduce the number of proximity switches and optimise the structure of some parts on the filter plate.

The unloading mechanism includes: reducer, drive shaft, chain, sprocket and other parts. At the beginning of unloading, the compression plate opens, and the motor at the support seat pulls the cylinder seat, compression plate and other parts through the chain traditional system to pull the first part of the filter plate away; the proximity switch gives a signal after the filter plate is in place, the motor at the thrust plate starts to run, drives the spacer plate to move and pulls the second part of the filter plate away; the proximity switch gives a signal after the second part of the filter plate is in place and pulls the third part of the filter plate away, and the cake falls off under the gravity and the tension of the filter plate. The filter cake is discharged under gravity and the tension of the filter plate. Realise the process of discharging material once. The plate is pulled three times during the process. The technical modification programme is as follows.

Simplify the process of pulling the board, the frequency conversion motor drives the pulling board trolley to realise the pulling board action.

The technologically modified pulling board system mainly includes: frequency conversion gear motor, sprocket, pulling board trolley, chain and so on. Under the control of the electric control system, the chain drive by the gear motor to achieve the action of the pulling plate trolley. Adopting segmented pulling method, the filter plate adopts 3-ring small chain link, the compression plate pulls open the first group of filter plate, the pulling plate trolley group pulls open the remaining group of plates at one time, shortening the unloading distance, the smooth and reliable process of opening and closing of the filter plate and simplifying the unloading process due to the pulling plate trolley unloading the number of proximity switches is changed to 2, which greatly reduces the failure rate of the link.

Optimisation of the chain structure between the filter plates

Simplify the small chain between the filter plate on the basis of keeping the length unchanged, as shown in Figure 2, the chain is changed from a 7-ring chain to a 3-ring chain, which is convenient for the maintenance personnel to find out whether there is any distortion and misalignment of the small chain when they are overhauling the filter plate and cloth, and then they can adjust it in time once they find it. Once found, it can be adjusted in time. From the root to avoid the speed imbalance between the two sides of the filter plate in the pulling process, effectively avoiding the filter plate pulling inclined.

Optimisation of the structure of the shaft of the filter plate support arm

As the positioning tube for the interference fit pressed in, time is easy to fall off, the small chain is easy to derail the twist, the original positioning tube positioning to shoulder positioning. Completely eliminate this phenomenon, to ensure the smooth pulling of the filter plate plays a fundamental role.

Modification of the centre hole of the filter cloth

The original design of the filter cloth structure is a two-piece combination structure, sewn together at the centre hole, when the filter cloth is disassembled, one side of the filter cloth needs to be rolled into a tube, passed through the centre hole on the filter plate, and then laid out, and then finally the filter cloth is tied to the filter plate with a nylon rope. During the operation process, there will be folds at the centre hole, and these folds will be repeatedly folded during the backblowing and pressing process, and after repeated folding, the folds will be broken and the filter cloth will be damaged. The problem to be solved for this phenomenon is the folding problem at the centre. Therefore, the filter cloth is transformed into a single piece type, and the cloth clamp is used in connecting, fixing and sealing, which completely eliminates the phenomenon of breakage at the centre hole of the filter cloth.

Change the bending direction of the feed tube, so that the elastic force generated by it and with the oil

Cylinder force in the same direction for the process of feeding due to the bending of the feed pipe generated by the elasticity caused by the stop push in place, the fast-opening diaphragm filter press feeding hose, protective sleeve direction for rearrangement. Related parts rotate 180 °, so that the feeding tube from clockwise bending to anti-clockwise bending. This way such as the elasticity direction of the feed tube.

concluding remarks

In conclusion, with the development of China's roof coal mining technology, the application of roof coal hydraulic support in the actual production will be more and more extensive, in the actual application of the operation, in order to better meet the application requirements, the hydraulic support of the frame type more and more, the structure is more and more stable, the mechanical properties will be more and more strong, which will be better to ensure that the roof coal mining operation of the safe and efficient production, the future of China's roof coal mining technology will also be China's roof coal mining technology will achieve long-term healthy and sustainable development.