Common faults of plate and frame filter presses and countermeasures

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​As a common device for treating sulfur foam in coking desulfurization, the plate and frame filter press is widely used by coking enterprises due to its simple operation, high safety levels, large processing capacity, and low energy consumption. However, various faults can occur as a result of improper maintenance and management. Based on years of practical experience, the common causes of faults in such filter presses along with corresponding solutions are summarized below for reference. 1. Causes of filter plate damage: (1) Insufficient feeding, blockage in the feed pipe; there is no sulfur paste inside the filter plate to act as a buffer, and when the diaphragm is activated to apply pressure, the filter plate is subjected to compressive forces that lead to its damage. (2) The filter fluid outlet is blocked, preventing the medium from flowing out; as a result, the filter plate is subjected to pressure and gets damaged. (3) An excessively high set extrusion pressure can also cause damage to the filter plate. Treatment measures: (1) When feeding, it is necessary to comprehensively assess whether the tank is full based on factors such as feeding time, feeding flow rate, and feeding pressure; feeding should be stopped once the tank is full before starting diaphragm punching. (2) Regularly inspect the filter cloth and filter plates, and clean away residues in a timely manner. (3) If wear is detected at the feed hole of the filter plate, it should be repaired promptly using large-grain glue or metal repair material. 2. Cause of the spraying phenomenon between filter plates: (1) The compression pressure does not reach the rated value, and an excessively high set value for the feeding pressure can also lead to spraying. (2) Residual sulfur paste at the filter plate joints causes poor bonding, folding or damage to the filter cloth, and damage to the head plate seal. Remedial measures: (1) If it is a manual operation, adjust the clamping pressure setting promptly; the set value must be reached before proceeding to the next step. (2) If wrinkles are found on the filter cloth, clean and smooth them out promptly; if it is damaged, replace it immediately. (3) A special tool for replacing the filter cloth was designed based on the shape of the filter plate, to ensure that the filter plate remains flat during replacement and to prevent deformation. (4) If material spraying occurs on the head plate, check the sealing ring of the head plate as well as the connection flanges attached to the filter cloth, and repair any damage promptly. 3. Causes of uneven filter cake shape or thickness: (1) It may be due to insufficient material supply. (2) The sulfur foam supply concentration is too low. (3) It is also possible that the components are blocked during operation. Countermeasures: (1) While ensuring the normal operation and use of the plate and frame, appropriately increase the feed rate of sulfur foam to guarantee sufficient feeding. (2) Upgrade the existing process to improve the quality of sulfur foam and ensure that its concentration remains within a reasonable range. (3) Regularly clean the filtrate outlet of the plate and frame to ensure the unobstructed flow in the filtrate pipeline. (4) During the filter plate forming process, increase the compression pressure to ensure proper formation of the filter cake. 4. Causes of problems with the slide track: (1) Broken bolts in the slide track, or damage to the track that results in protrusions, can cause the cart to get stuck and fail to move forward despite repeated attempts to make it move. (2) If the slide rail is not level or sags, it can cause the lowering claws to fail to grip the filter plate. Remedial measures: (1) Regularly inspect the slide rails; if any bolts are loose, tighten them or replace them promptly. (2) If the slide is not level, it should be adjusted as a whole promptly. (3) Installing fixing sleeves on the slide bolt, and replacing these sleeves regularly, can prevent wear on the bolt, with good results. 5. Causes of chain-related problems: (1) A loose chain or severe wear on the chain can easily lead to chain jamming or breakage. (2) Severe wear of the sprocket can easily lead to chain engagement. (3) Wear of the tail fixing pin shaft can easily cause the sprocket to wobble, leading to the chain coming loose. Remedial measures: (1) If the chain is found to be too loose, it should be tightened promptly; if the chain is severely worn, it should be replaced in a timely manner. (2) When severe wear is detected on the sprockets and pin shafts, they should be replaced promptly. (3) Lubricate the chain and sprockets once a month using No. 320 lubricant. 6. Causes of faults in the cart mechanism: (1) If the spring that allows the cart to descend is too loose, it will prevent the claw from returning to its initial position. (2) Wear of the tail puller bolt can cause the puller to be uneven, preventing the vehicle from returning. (3) The connecting bolts on the trolley chain links become loose; these bolts are subjected to shear stress, which causes them to break, resulting in the loss of the connecting links. If this is not detected in time, it can lead to the breakage of the chain. (4) The two ends of the trolley are not aligned, causing the filter plates to be pulled at an angle and fall off, preventing proper unloading. Countermeasures: (1) Regularly inspect the components of the trolley; replace any damaged parts promptly, and tighten the connecting bolts at the end of each shift. (2) When chain skipping is detected, use the wooden wedge method to adjust the chains at both ends to be equal. (3) The trolley speed can be adjusted using 2 throttle valves. 7. Hydraulic system issues (1) Causes of oil leakage at the oil pipe fittings: Due to the working environment and duration of use, the oil pipes and fittings tend to age over time, which leads to oil leakage. Solution: Replace the corresponding oil tube. (2) The low-pressure and high-pressure pumps are not working. Cause of failure: The filter press is unable to perform closing and opening functions. Remedial action: Check the oil pump motor and its corresponding circuit module; replace the damaged components. (3) The plate and frame filter press cannot maintain pressure and thus cannot be closed. Cause of failure: The inability of the hydraulic system to maintain pressure is often caused by a failed check valve, and plate and frame filter presses are no exception. Countermeasure: At this time, it is necessary to check the check valve on the main cylinder of the machine head; replacing the damaged check valve will resolve the issue.