The Specialties of Horizontal Belt Filters - Case Study Example

Better filtration with low energy consumption makes horizontal belt filters a favourite in industry sectors. The main advantage of these filters is that they are very flexible in both operation and adaptation. They can be handled so simply for the filtration of various categories of matter. Though simple by concept, the horizontal belt filters were an invention with momentous impact across many industries. They improved the quality, quantity, speed and reliability of many operations. Generally they are used to separate vacuum and gravity forces of both liquid and solid states of matter. This process can be applied in chemical, petrochemical, uranium, metallurgical and food processing flow sheets. The horizontal belt filter can be operated continuously in the perfect washing process of solid matter. The dewatering after each washing process can be done by applying the force of vacuum on the cake through filter media. This is really a synergistic phenomenon and very effective filter process on energy consumption, cake solids and wash ratio. With the help of these horizontal belt filters, full range of things from coarse granular particles to fibrous or fine slime solid particles can be filtered very effectively. Miraculous Designs, Multifaceted Operations The magical spell that these belt filters exerted on the industries has much to do with their designs and operational flexibilities. There are belt filters with and without washing process. The belt filters without washing, consists a basic flow sheet which can be utilized for the direct dewatering. The aim of this application is to produce a cake with lowest moisture content. The remaining liquid content in the cake is not at all considered even though it is responsible for its original appearance. At the same time in the belt filter with washing process there is a flow sheet which supports the washing of the cake. Here, the liquid which is generally used to wash the cake is also employed to displace the mother liquid. The result of this process is uncontaminated cake. In the belt filters with counter current washing, the flow sheet is provided with a counter current wash system which can be used more as the wash water, better than co-current system. By this arrangement the solid to be washed is dragged towards the filter belt and simultaneously the wash liquid is moved in the opposite direction. For best washing and separation, wash boxes are positioned in between the wash filters. This must be close to the partitions which are situated inside the vacuum box. The efficiency of washing is determined by analyzing the percentage of contaminants remaining in the final cake. Another type of belt filtering is with counter current washing and cloudy recycle. Here the filtration is achieved with the help of permeable filter cloths. During this filtration process solid materials passes into the mother filtrate through the pores situated in the filter cloths. This can be checked by inserting a partition inside the vacuum box. Care should be taken to insert the partition at the point where the slurry feed touches the filter cloths. A small vacuum receiver with seal tank is attached together with this mechanism so that it can remove certain quantity of the cloudy filtrate. The main constituent of this filtrate is solid particles. At the top of the vacuum receiver there is a valve meant to reduce the vacuum force. The flip of cake particle on the filter cloth serves as the filter medium over the porous cloth and thus the mother filtrate can be made free from solid particles. This flow sheet method is generally applied for the preparation of phosphoric acid.(http://www.solidliquid-separation.com/VacuumFilters/Belt/belt.htm) Industrial Application Designs Nowadays these horizontal belt filters are specially designed to meet the current requirements. Hence the components of these belt filters are designed and subjected in such a way to fulfill the prevailing needs. Modern filters are capable of running at high speeds, handling thick and heavy cakes, and able to operate at high temperatures. In short the modern belt filters are capable to work in the midst of most adverse conditions. In order to meet this requirements these belt filters are manufactured with technically advanced materials. (http://www.solidliquid-separation.com/VacuumFilters/Belt/belt.htm ) Some key facts are to be remembered primarily to secure uninterrupted better performance from the belt filters. They are as follows. 1. One main component in this machine is the rubber belt. There are chances that cracks may develop in the rubber belt, which may result in the detachment of the piles which are embedded between the rubber layers. This occurrence will reduce the performance of the belt and hence this fault should be traced out and corrected immediately. 2. The belt which moves over the head and tail pulleys of the device experiences too much force on its either sides. Since the purpose of this belt is to contain the incoming feed, the tearing of edges may spread throughout. Hence the belt should be inspected always to see whether any defect is developed anywhere. 3. There is facility to clean the vacuum box by moving it to one side. Hence the timely cleaning of the inner components can be performed easily. There are possibilities to loose the force of vacuum while reinstating the same in to the machine. Hence care should be taken to seal the antifriction liners of the vacuum box against the sacrificial wear belts and also with the bottom portion of the main belt. 4. It is always advised to inspect the wear belt of the machine. This is to confirm that they are in good condition. Any ignorance on the wear belt will destroy the performance of the main belt in later stages, and the damages that ensue will be beyond prediction. The looming damage is warrant enough to always keep a vigilant eye on the wear belt machine. 5. Another thing that needs to be checked on the wear belt is the sealing between the stationary vacuum box and the moving belt. Hence the inspection of the wear belt is a very important factor. 6. The life of the belt and the drive mainly depends on the water lubrication mechanism in between the surfaces of the moving and stationary parts. Hence the inlets to those parts must be observed and cleaned perfectly. 7. Alignment of the filter is the other important thing to be examined always. This is only applicable to larger filters. Fault in the alignment on account of varied setting is affected on the building foundation only during the first year. The misalignment causes the following difficulties also. There may be difficulties in sealing the long and segmented vacuum boxes all along the filter. Another difficulty is uneven cake washing. This happens across the filter when the thickness of the cake may taper in one direction. The alignment across the filter is very important as far as the thin cakes are concerned. A 2 meter wide belt having slope 0.5% reduces the 20 mm cake thickness on one side from 20 mm to 10 mm. Apart from the cake washing process the functioning of horizontal belt filters are employed in various sections in the industrial sectors. When there are high requirements of solid settlement in an industry the assistance of belt filters are considered. This is the reliable alternative compared to other means of solid settlement. Complete processing of feed materials in the industrial sectors can be performed with the help of these filter belts. When maximum product recovery is needed, belt filter is the most suitable and reliable machine.(http://www.solidliquidseparation.com/VacuumFilters/Belt/belt.htm ) Low cost, wide-range operability In industrial sectors these belt filters are mainly used in view to reduce the operational cost. These machines provide maximum profit in minimal operational cost. The implementation of belt filter ensures a flexible range of operational conditions. For achieving this advantage no extra expense is required by the concerned industrial sector. If an industry requires simplicity in operation and maintenance belt filter system is the very suitable and faithful machinery. This machinery can also be implemented if the process contract needs abundance of perfect construction materials. The qualitative feature of this belt filter is the high filtration rate with low energy consumption. This feature of the horizontal belt filter has made it an unquestionable choice for many industries like minerals processes, metallurgical ores, power wastes, chemical processing and food processing. The main reasons behind this choice can be stated as follows. The horizontal belt filters ensures reliable extraction efficiency and increased production. They have reduced operational costs with maximum efficiency on filtration in comparison with other filtration devices. Creation of low cake moisture content is the other main reason for choosing this system in industrial sectors. They ensure maximum cake purity under minimum specific cost. They can also be applied for multistage washing process. Thus the invention of the horizontal belt filters has improved the cake washing process in the industrial sectors to a considerable level. This coupled with other quality maintenance procedures has ushered in an era of high quality at affordable costs, which would not have been the case without horizontal belt filters. The extreme importance that these filters bear in the industry has led to intensive research and development in related areas. Significant developments can be expected in recent years bringing in new designs and operational modes of these belts. And that will bring in better quality at lower costs. (http://www.solidliquid-separation.com/VacuumFilters/Belt/belt.htm ) References Belt filters (Online) Available at: http://www.westech-inc.com/product.cfm?itemid=106[Accessed 18 November 2010] DY belt filters press (Online) Available at: http://www.hehuajixie.com/pages/dy_belt_filter_press-en.htm [Accessed 18 November 2010] vacuum belt filters (Online) Available at: http://www.rpaprocess.com/produtos/produtos.php?is=2&pid=4 [Accessed 18 November 2010] Horizontal Vacuum Belt Filters (Online) Available at: http://www.westech-inc.com/public/brochures/HorizontalBeltFilter1.pdf [Accessed 18 November 2010] Used filters (online) Available at http://www.ippe.com/FILTER/tabid/103/CategoryId/FILTER/Default.aspx?kw=belt%20filters&nw=search&cr=4383424723&gc [Accessed 18 November 2010] horizontal belt filters(online) Available at http://www.flsmidth.com/en-US/Products/Product+Index/All+Products/Vacuum+Filtration/HorizontalBeltFilters/HorizontalBeltFilt [Accessed 18 November 2010] Read More