Abstract: The depth of water desalination pretreatment technology is an indispensable part of this process directly affects the next depth effect and ion exchange water treatment plant running. In the water pretreatment, filtration is a very important process. for the Liaoning plant chemical factory filters use, the update process, the filter used by filter description of the history and tradition and the modern new filter particulate filter fiber in practical applications contrast, described the advantages of fiber filter. Meanwhile, the practical application of extrusion for the capsule-type fiber filter and fiber filter plate type structure characteristics and to compare the practical application, reflect the skateboard-type fiber filter in water treatment better application of the process.

  Key words: fiber bundle; filter; filter
Many different types of natural water impurities, the quality of these impurities in accordance with the size of the particles can be dispersed accordingly divided into suspended solids, colloidal and dissolved substances. As the power plant have high requirements of water quality, water depth, therefore the need for purification. Natural water by coagulation, sedimentation treatment, although most of the water to remove the suspended solids and colloidal impurities, but there is still a small amount of fine suspended particles left in which to reduce the depth of the water treatment process next adverse effects, ensure the ion exchange device normal operation, the method usually used to further remove the water filtration of suspended impurities. in the past mostly used to filter particulate material filtration technology, filtering technology is now with the development of high precision fiber filter with its filter, sewage capacity Big, big advantage of running output gradually replace the particulate filter [1].

  1 filter used in filter comparison
Traditional filtering techniques are mostly used to filter particulate material, using a filter device of this filter is relatively simple and easy to lapse when the filter layer with anti-wash method to restore its filtering capabilities, but because of particulate filter material limitations, ability to filter the sewage interception, filtration rate and water quality are greatly curtailed. by a filament made of fibers occurred in recent years, alternative to traditional filter media, which to a certain density arrangement of the filter, its fibers, small size, large surface area to greater adsorption. As the fiber flexibility to enable them to achieve density in the filtration process of adjustment, so that the minimum filter layer pores between the fibers much smaller than the traditional use of granular filter media filter (such as quartz sand, etc.) of porous, so it's interception in competence, so as to achieve the purpose of deep filtration. Meanwhile, because of its large run-time efforts (such as quartz sand filter output to 60 t / h, the output fiber filter up to 95 t / h), so overcome by the size of granular filter media filtration precision constraints and other issues [2, 3], and now fiber has been widely used filters device in the. Liaoning plant chemical factory to use the capsule initially extruded fiber filter-based, following a brief of such filters.

  2 Compressed Fiber Filter Capsules 2. 1 the basic structure and working principle
This type of filter (Figure 1) is a new type of soft filler filters do filter. Device has many long fibers within the link in which the lower end of the fiber bundle pulling hammer and equipment with water installations and water installations, in the run-time, by the lower water, the upper water. in the fiber bundle to install several soft capsules, the upper tank with pressurized chamber for the capsule filling, after filling lateral extrusion fiber capsules from the role of fiber compaction and ensure the filtering effect. in equipment and scrubbing the bottom with air duct cleaning when the water pressure chamber capsule extrusion, so that the fibers in a loose state, in order to achieve good cleaning effect.

  2. 2 Use of Chemical factory in Liaoning power plant initially extruded fiber filter capsule gradually replace the granular filter media filters during actual use, this capsule-type fiber filter and the conventional quartz sand, anthracite and other granular filter media filter devices compared to no increase in filtration resistance in the same time, so that the minimum filter layer pores between the fibers is 10 ~ 40 m, greatly increased the filter surface area and surface free capacity, an increase of water impurities particles come into contact with the filter and the adsorption capacity of filter media, thus improving filtration efficiency and interception in capacity. factory in 1998 that a systematic search filter set, the data shown in Table 1.

  By Table 1 data, this device can reduce about 40% water turbidity, iron removal rate of about 30%. Although this filter has more advantages, but there are still many deficiencies. First of all, in addition to capsule, but also with capsule filling, drainage, equipment, complicated, easy to operate; addition, since the capsule during the operation of pulling up the lower part is well received, but also by its internal pressure to outward , resulting in capsule easily broken, and capsules are more expensive, which correspondingly increased equipment maintenance costs; In addition, the replacement of more complex capsules work to repair and maintenance of trouble, increasing the daily workload. To Capsule extruded fiber to overcome the lack of filter, the filter plant to further update this skateboard-type fiber filter.