Belt Filter Equipment Industry Sludge Concentration Thickener Filter Press

Working principle of belt concentrated filter press

Belt filter press is a continuous filter, which uses multi-layer polypropylene filter belt to press and dewater the material. This press filtration process can effectively separate the water and solid particles in the suspension, so that the liquid can be purified and the solid can be concentrated or dehydrated.

The flocculant in the flocculant preparation device is pumped to the static mixer, fully mixed with the material, and then enters the concentration section. Under the action of flocculant and gravity, most of the free water is effectively removed in the concentration section, and then sent to the pressure filter section through the unloading mechanism. After gravity dehydration, the material is discharged to the two closed filter belts through the turning mechanism. A pair of main dehydration rollers are pressed and dehydrated, and a series of S-shaped rollers with diameters from large to small are arranged to make the filter cake from small to large.

The whole dehydration procedure of the belt type concentration filter press is continuous, and its working process is generally: flocculation - feeding - gravity dehydration of the concentration section - extrusion and shear force of unloading of the concentration section, so as to achieve the purpose of removing most of the free water and part of the capillary water in the material. -- Gravity dehydration of pressure filter section -- prepressure dehydration of pressure filter section -- press dehydration of pressure filter section -- unloading.

Structure of concentration section of belt filter press:

The concentration section is composed of feeding device, tensioning device, distribution device, chassis, deviation correction device, detection and protection device, washing device, transmission device, unloading device and other parts.

1. Feeding device: a static mixer is arranged before the feeding device to ensure that the sludge and flocculant are fully mixed. A diversion plate is provided inside the feeding device, and the material flows along the diversion plate in a "U" shape and overflows into the chassis.

2. Tensioning device: the device is mainly composed of tensioning roller, self-aligning bearing with slider seat and spring, etc. The bearings at both ends of the tension shaft can move along the guide block, and the tension force of the filter belt can be adjusted by the compression amount of the compression spring under the action of the spring.

3. Dispensing device: the dispensing device is mainly composed of feeding board and support rod. The material can be activated by the feeding board, avoiding the appearance of small puddling on the filter belt, with the function of material separation and aggregate, and improving the drainage effect. The material of the feeding board is flexible wear-resistant material, and the lower edge of the feeding groove is equipped with a sealing rubber plate.

4. Chassis: chassis mainly plays the role of supporting, installing other components, collecting filtrate, and is welded by cold work. The bottom of the chassis is provided with a drain hole, and the middle is provided with a peeping hole for maintenance.

5. Correction device: the device adopts air pressure automatic correction, mainly composed of correction roller, cylinder, induction arm and other parts. When the filter belt is deviated, the sensor rod moves under the action of the filter belt; When the induction rod touches the mechanical button valve, the mechanical button valve controls the reversing of the air control valve, the movement of the correction cylinder, the rotation of the correction roller, the reverse move to the other limit, so as to drive the filter belt to move slowly to the other end. The other side of the induction rod moves under the action of the filter belt, touch the mechanical button valve, control the air control valve reversing, the correction cylinder movement, drive the correction roller rotation while the filter belt slowly moves back; Realize the dynamic balance of the filter belt in a certain range on both sides of the central position, and achieve the function of automatic correction.

6. Detection and protection device: in case the correction device fails and the deviation of one side of the filter belt reaches 40mm, the filter belt will approach and touch the limit switch, and the system will alarm and automatically stop. The limit switch can also measure the break of the filter belt. When the filter belt breaks, the equipment stops running immediately.

Components of belt filter press unit:

Belt type filter press is mainly composed of driving device, frame, press roller, upper filter belt, lower filter belt, filter belt tensioning device, filter belt cleaning device, unloading device, air control system, electrical control system and so on.

1. Frame: the belt filter press frame is mainly used to support and fix the press roller system and other components.

2. Press roller system: it is composed of rollers whose diameter is arranged in order from large to small. The sludge is clamped by the upper and lower filter belts, and when it passes through the press roller in turn, a pressure gradient from small to large is formed under the action of the tension of the filter belt, so that the pressing force of the sludge in the process of dehydration is constantly increased, and the water in the sludge is gradually removed.

3. Gravity zone dewatering device: mainly composed of gravity zone bracket and material tank. After flocculation, a large amount of water is removed from the gravity zone, and the fluidity becomes poor, which creates conditions for later extrusion and dehydration.

4. Wedge zone dewatering device: the wedge zone formed by the upper and lower filter belt exerts extrusion pressure on the clamped material and carries out pre-pressure dehydration to meet the requirements of liquid content and liquidity of the material in the pressing and dehydration section.

5.Filter belt: is the main part of the belt filter press, the separation process of solid phase and liquid phase of sludge are above and below the filter belt for the filter medium, under the action of the upper and lower filter belt tension to bypass the press roller and obtain the pressing force required to remove material moisture.

6. Filter belt adjustment device: it is composed of actuator cylinder, adjusting roller signal reverse pressure and electrical system. Its function is to adjust the filter belt deviation caused by uneven tension of the filter belt, roller installation error, uneven feeding and other reasons, so as to ensure the continuity and stability of the belt press filter.

7. Filter belt cleaning device: it is composed of sprayer, cleaning water receiving box and cleaning cover. When the filter belt is walking, it goes through the cleaning device continuously, and is impacted by the pressure water ejected by the sprayers. The remaining materials on the filter belt are separated from the filter belt under the action of pressure water, so that the filter belt is regenerated and prepared for the next dehydration process.

8. Filter belt tensioning device: it is composed of tensioning cylinder, tensioning roller and synchronous mechanism. Its function is to tensioning the filter belt and provide necessary tension conditions for the production of pressing force of pressing dehydration.

9, unloading device: composed of tool holder, unloading roller, etc., its role is to dewater the filter cake and filter belt peeling, to achieve the purpose of unloading.

10.Transmission device: composed of motor, reducer, gear transmission mechanism, etc. It is the power source of filter belt walking, and can meet the requirements of different belt speeds in the process by adjusting the speed of reducer.

Application field of belt filter press

As an advanced filtration equipment, belt filter press is widely used in various fields. The following are the main application areas:

1. Sewage treatment: belt filter press can be used for sludge dewatering in sewage treatment process. In the sewage treatment process, the sludge generated needs to be dehydrated for subsequent treatment and disposal. The belt filter press can dehydrate the sludge efficiently and reduce the moisture content to a lower level.

2. Fine chemical industry: A large number of wastes will be produced in the production process of fine chemical industry, such as waste residue in the production process of dyes and coatings. These wastes contain a lot of water and impurities, and the belt filter press can separate the water and impurities in these waste slag to improve the efficiency of waste treatment.

3. Mineral processing: in the field of mineral processing, a large amount of water slag and mud will be produced during beneficiation and tailings treatment. Belt filter press can separate the water and impurities in these wastes, improve treatment efficiency, and reduce environmental pollution.

4. Food industry: in the food industry, belt filter press can be used in the processing of juice, starch and other materials. By separating moisture and impurities from the material, the quality and yield of the product can be improved.

5. Other fields: in addition to the above application fields, the belt filter press can also be applied to pharmaceutical, papermaking, electroplating and other fields. In these fields, belt filter press, as an advanced filtration equipment, can efficiently deal with various materials, improve production efficiency and product quality.

In short, as an advanced filtration equipment, belt filter press has a wide range of application prospects. In various fields, its high efficiency, energy saving, environmental protection and other characteristics make it an ideal choice for filtration equipment.

Check and adjust the belt filter press

In addition to the general inspection of the start-up preparation and operation of the belt filter press, the belt filter press will be in operation with the change of mud, medicine, equipment, etc., at any time, there will be a variety of different working conditions. When the belt filter press is in poor operating conditions, there will be a high moisture content of the mud cake after dehydration, even more than 80% of the moisture content standard. Therefore, for the belt filter press, in addition to the relevant matters should be paid attention to before starting the machine, in the actual operation should be according to the change of the mud into the mud, the belt speed, with tension, sludge conditioning, mud into the amount and mud into the solid load and other aspects of adjustment at any time.

(1) Belt speed: the belt speed of the filter belt generally has a speed regulating hand wheel on the main drive motor of the dewatering machine. The speed can be adjusted according to the actual situation of the mud cake, and the main motor must be kept in operation when adjusting. The walking speed of the filter belt controls the dewatering time of the sludge in each working area, and has an impact on the solid content of the mud cake, the thickness of the mud cake and the difficulty of the mud cake stripping.

When the belt speed is lower, on the one hand, the sludge pump will add more sludge to the filter belt at a fixed sludge speed, on the other hand, the longer the sludge filtration time on the filter belt, so that the mud cake solid content on the filter belt will be higher. The higher the solid content of the sludge cake is, the thicker it is, and the easier it is to peel from the filter belt. On the contrary, the higher the belt speed is, the lower the amount of mud cast per unit time is, the shorter the filtration time is, resulting in an increase in the moisture content of the mud cake and a decrease in the solid content. The thinner the mud cake, the more difficult it is to peel. Therefore, from the mud cake quality, the lower the belt speed, the better, but the speed of the belt directly affects the processing capacity of the dewatering machine, the lower the belt speed, the smaller the processing capacity. For the mixed sludge composed of primary sedimentation sludge and activated sludge or advanced treatment of chemical sludge and activated sludge, the belt speed should be controlled at 2 ~ 5m/min. When the amount of mud is high, take the high belt speed, otherwise take the low belt speed. Because activated sludge is mainly microbial, intercellular water and intracellular water are difficult to be removed by simple pressure filtration. Generally, it is not suitable to carry out belt pressure filtration dehydration alone, otherwise the belt speed must be controlled below 1m/min, and the processing capacity is very low and uneconomical.

 However, it should be noted that regardless of the nature of the mud and the amount of mud into the mud, the belt speed should not exceed 5m/min, too fast belt speed will also cause the roll of the filter belt, etc.

(2)Filter belt tension: according to the structure of the pressure filter dewatering machine, the sludge with polymer flocculant enters the upper and lower tightness of the filter belt, and the water is filtered out through the filter belt under the extrusion between the upper and lower filter belts. In this way, the pressure and shear force applied by the upper and lower filter belts to the sludge layer are directly determined by the tension of the filter belt. Therefore, the tension of the filter belt will affect the solid content of the mud cake. The greater the tension of the filter belt, the water in the sludge is squeezed, the sludge flocs are cut into cakes more thoroughly, so that the sludge in the dewatering machine between the various rollers extrusion degree is higher, more water filtration, also make the final mud cake solid content is higher. For municipal sewage mixed sludge, the general tension should be controlled at 0.3 ~ 0.7MPa, which can be controlled between the median 0.5MPa. Also pay attention to the tension selection to be more appropriate, tension setting is too large, the gap between the upper and lower filter belt is small, the sludge by the positive pressure is too large, from the upper and lower filter belt without pressure between the gap extrusion, so that the sludge in the low pressure area or high pressure area extrusion out of the filter belt, resulting in material running or pressure into the filter belt caused by blockage. Generally, the tension of the upper and lower filter belts can be set equal, and the tension of the upper and lower filter belts can also be adjusted appropriately, so that the tension of the lower filter belt is slightly lower than the upper filter belt, so that the sludge is easy to be gathered into mud cake in the concave area formed by the lower filter belt in the extrusion process of the dewatering machine, which will significantly improve the cake formation rate of the sludge.

(3) Sludge agent: the belt filter press has a strong dependence on sludge flocculation agent and sludge effect. When the flocculation effect of sludge is not good due to insufficient flocculation dosage, the capillary water in the middle of sludge particles cannot be converted into free water and filtered out in the gravity concentration area. Therefore, the sludge from the wedge zone where the upper and lower filter belts meet is still mobile when entering the low pressure area, which cannot be squeezed, resulting in serious sludge running phenomenon. On the contrary, if the dosage is too large, it will not only increase the treatment cost, but more importantly, the excess agent remaining after full reaction with sludge is viscous and adheres to the filter belt, and it is difficult to wash it clean with high-pressure washing water, and the residual agent is easy to cause the water filter gap in the filter belt to be blocked. For the mixed sludge of chemical sludge and biological sludge of urban sewage plant, when polyacrylamide (PAM) is used, the dosage equivalent to dry sludge should generally be between 1 ~ 6kg/t, and the specific dose should be determined after laboratory tests according to the performance and molecular weight of the purchased agent.

(4) The amount of mud and the solid load of mud: the amount of mud and the solid load of mud are two representative indicators of the processing capacity of the belt pressure filter dewatering machine. Sludge intake refers to the amount of wet sludge that can be treated per meter bandwidth in unit time, commonly expressed by q, and the unit is m3/(m•h); Sludge inlet solid load refers to the total amount of dry sludge that can be treated per meter bandwidth in unit time, commonly expressed as qs, and the unit is kg/(m•h). It is obvious that q and qs depend on the belt speed and filter belt tension of the dehydrator and the conditioning effect of the sludge, which in turn depend on the required dehydration effect, namely the solid content of the mud cake and the solid recovery rate. Therefore, when the sludge nature and dewatering effect are certain, q and qs are also certain. If the sludge intake is too large or the solid load is too high, the dewatering effect will be reduced. Generally speaking, q can reach 4 ~ 7m3/(m•h) and q can reach 150 ~ 250kg/(m•h). The bandwidth of the dewatering machine is generally not more than 3m, otherwise, the sludge is not easy to spread evenly.

In the actual operation, the operator should according to the requirements of the mud quality and dehydration effect of the plant, by repeatedly adjusting the belt speed, tension and dosage and other parameters, get the amount of mud and mud solid load of the plant, so as to facilitate the operation and management.

Maintenance of belt sludge filter press

Belt sludge filter press is a kind of more and complicated equipment, which needs regular maintenance to ensure the normal operation of the equipment. The following are some common methods for belt sludge filter press maintenance:

1. Clean the filter belt regularly

Since the belt sludge press compresses and dehydrates the sludge through the filter belt, the filter belt can easily become dirty and messy. If the cleaning and replacement operation is not timely, it will lead to filtration deceleration, operation efficiency reduction, and even cause equipment failure.

Therefore, it is necessary to clean the filter belt regularly to ensure normal work. The way of cleaning is usually to use special cleaning agent and high pressure washing machine to completely remove dirt and impurities on the filter belt.

2. Check the operation of each part of the equipment

In the process of equipment operation, it is necessary to regularly check whether each part of the equipment is running normally, such as checking the operation of the drum, pressure roller, compression belt and dragging system, etc. If there is damage or abnormal sound, it is necessary to deal with it timely.

3. Replace oil products and maintain machinery regularly

Each transmission part of the belt sludge filter press needs to be replaced regularly, such as hydraulic oil and reducer oil, to effectively ensure the normal operation of the equipment. In addition, the machinery should be maintained as if in the oil change, cleaning, anti-corrosion and other maintenance cycle, in order to extend the life of the machinery and improve the efficiency of equipment maintenance.

4. Strictly follow and obey the usage rules

The belt sludge filter press requires an operator's manual to guide its proper use and operation. Therefore, in the process of using the equipment, it is necessary to strictly follow and obey the use rules, do not overload or over-compress the equipment. At the same time, pay attention to the health and safety of the equipment during operation. For example, when the equipment shows abnormal conditions, the equipment should be stopped for maintenance.