The Design and Operation of Rotary Drum Vacuum Filters - Coursework Example

Student’s Name Institution Instructor’s Name Subject Introduction Being one of the oldest filters applied in industries that deal with chemicals, the Rotary Vacuum Drum Filter belongs to the group known as the bottom feed group. The machine offers great flexibility for the industry in the meeting of the many needs of the many products that require separation of the solids from liquids. The filter offers a good experience ranging from simple separations to the most complex of the multi-stage applications which might involve clarification, filtration, extraction, and even dying. The Rotary drum offers a continuous operation, application versatility and a wide range of sizes in the industrial process. (Halberthal) The Vacuum filter consists of different parts that make it effective for the chemical process industry. The following are the various parts of the Rotary Vacuum drum filter; a.) The Drum b.) The Internal Piping c.) The Drum Deck d.) The Filter Cloth e.) The Cake Discharge Mechanism f.) The Drum Speed Variation g.) The Agitator h.) The Tank i.) The Cake Washing Manifold j.) Control Instrumentation Design of the rotary drum vacuum filters The rotary drum vacuum filter specifically discharges the filter cake with the help of one of the several of its arrangements. The mechanism of discharging the filter cake is selected depending on the characteristics of process material not forgetting how it readily releases from the filter media. The following are some of the design mechanisms; (Richard J. Wakeman) The rotary drum vacuum filters has a Flexi belt Discharge which features a filter belt that passes over the roll on a variable speed discharge at the same time this flexi belt has raised helix in that position to have the cake removal be positive. The flexi belt is applied where there is the requirement of washing the filter medium in the efforts to prevent blinding. In other case, the flexi belt is used to enable the discharge of cakes which are thin; when needed. It is also used to discharge dry cakes or the sluice also known as the wet cakes. (Richard J. Wakeman) The Flexibelt Discharge has various applications which make its processes efficient; Corn Gluten Starch Pharmaceuticals Fermentation Broths Pigments Organic/Inorganic Chemicals Water Softening Sludge Steel Mill Waste Hydroxide Sludge Industrial Wastewater When a direct filtration against a medium of maybe cloth is not possible, the Precoat discharge is used, this is because the cake can not be removed from the cloth , in other case when this method is applied is when blinding is indicated. The method is in most occasions used for; (Richard J. Wakeman) For slimy, sticky, oily and blinding solids. For clear filtrates. For filtering dilute slurries with varying feed concentrations. For the discharge of very thin filter cakes. The precoat Discharge has the following applications:- Corn Syrup Clarification Fruit Juices and Wines Pharmaceuticals Fermentation Broths Food Processing Wastes Hydroxide Sludge Slop Oil Flexographic Ink Wastes Industrial Wastewater Scarper Discharge Used along with the air blowbacks, the Scraper discharge is used to release the filter cake from the medium of cloth which is usually above the scraper. The scraper discharge is used for: (mline-Sanderson) Fast filtering materials. Filtering/dewatering crystalline solids or granular. Discharging cakes which exceed a thickness of 1/4". Non-blinding cakes where cloth washing is not required. A typical scraper discharge has the following applications: Flue Gas Desulfurization (FGD) Scrubber Sludge FGD Gypsum Dewatering and Cake Washing for Wallboard Inorganic Chemicals and Minerals Pigment Processing Plastics Resins (Polymers) Calcium Compounds Titanium Dioxide Edible Oil Dewaxing Roll Discharge The fittings of the roll discharge usually have very tight filter medium, this is to help in retaining small particles ion the process. The Roll Discharge is used for the following processes; (mline-Sanderson) discharging cakes which are very thin and sticky (tacky) discharging materials which are dilatent and thixotropic applications of small size particles A Roll Discharge consists of the following applications; Kaolin Clay Titanium Dioxide Pigments Ceramic Materials Magnesium Hydroxide String Discharge The String discharge plays the role of utilizing the parallel strings which are closely spaced in order to lift the cake from the cloth. The cake is then released after the strings pass over a discharge roll. A long life for the filter medium since there is no the occurrence of any mechanical wear on the filter medium. This filter medium is used for all the discharging of cohesive cakes and also for the discharging of gelatinous cakes. (steadfastequipment) A typical string discharge contains the following applications; Starch Fruit Juice Fermentation Broths Mineral Processing Operation of rotary drum vacuum filters In order to complete an entire cycle of filtration, the rotary drum filter is supposed to complete a full geometry turn of 360 degrees. The operation of the vacuum drum filters is the similar since they are all made up of an inner rotating drum which is encased in a cylinder trough on the outside. Inside the drum, there is a fabric filter which covers it. In the action of operation, the vacuum is pulled from the inside as a result pulling the filtrate to the inside resulting the deposition of the solid matter on the fabric. The filtrate is routed from the drum after being pulled to the channels which are in the interior of the drum. Due to the fact that the drum keeps rotating, the process is a continuous one. In the process of rotation, the liquids pour out leaving the solids to dry as a result of the air that passes over them from the vacuum on the drum. Here is what takes place in the process. Cake formation The “apparent submerge” is usually 33-35% due to the face the overflow weir is set to the maximum in the slurry levels in a period of 4 hours. A cake starts to form once an application of a sector enters into the submerged vacuum and forms fully once it reaches the point where there is an emergence of the sector from the slurry. Cake washing and drying The cycle of drying the portion commences after the cake emerges from the sector as the non-wash applications get on until the time the vacuum is cut off. When the cake washing is required, the time frame for the process is 30 minutes. Cake discharge After the vacuum is cut off for the entire sector, air blow starts in order to facilitate discharge of the cake. The drum filters are normally operated in a low pressure blow depending on the application. Blow is applied on the scrapper on the roll and discharge mechanisms, for the flexi belt mechanism vacuum cuts-off once the medium being filtered leaves the drum. Dead Zone The sector passes through the zone after the blow is cut off; the zone is blocked with bridges to block any air from being drawn through the filter media which is exposed for this might cause the loss of vacuum. Works Cited Halberthal, Josh. The Rotary Drum Filter. 2006. 23 November 2009 . mline-Sanderson. Rotary Drum Vacuum Filters. 2009. Kamline-Sanderson. 23 November 2009 . Richard J. Wakeman, E. S. Tarleton. “Solid/liquid separation: scale-up of industrial equipment.” Richard J. Wakeman, E. S. Tarleton. Elsevier, 2005. 339 pages. steadfastequipment. Design Operational Details. 18 November 2009. 23 November 2009 . Read More