Pulp filters

Ptdp) filtei. s. These filters employ one or more packs of filtermasse (cellulose fibers compressed to a compact cylinder) stacked into a pressure case. The packs are sometimes supported in individual trays which provide drainage channels and sometimes rest on one another with a loose spacer plate between each two packs and with a drainage screen buried in the center of each pack. The liquid being clarified flows under a pressure of 345 kPa (50 psig) or less through the pulp packs and into a drainage manifold. Flow rates are somewhat less than for disk filters, on the order of 20 L/(min-m ) [0.5 gal/ (min-ft")]. Pulp filters are used chiefly to polish beverages. The filtermasse may be washed in special washers and re-formed into new cakes. 

In the presence of interfering elements, proceed as follows. Neutralise 80-120mL of the solution containing 15-25mg of beryllium with ammonia solution until the hydroxides commence to precipitate. Re-dissolve the precipitate by the addition of a few drops of dilute hydrochloric acid. Add 0.5 g of ammonium chloride and sufficient 0.5M EDTA solution to complex all the heavy elements present. Add a slight excess of dilute ammonia solution, with stirring, boil for 2-3 minutes, add a little ashless filter pulp, filter, and complete the determination as above. 

A product which contains about 2.5 ethoxy groups (47—48%) is thermoplastic and is suitable for commercial and military uses its sp gr is 1.07—1.18, nD 1.47 and softening point 240—45°. It can be prepd in a laboratory, by slowly adding (with stirring) to the pulped filter paper (suspended in 44% aq NaOH so In maintained at 100°) an excess of ethyl chloride (usually 6 moles per one mole of cellulose) and allowing to stand for a while Note In order to obviate to some extent the side reactions of hydrolysis, the procedure is conducted in the presence of large amount of NaCl... 

After lagering, the beer is filtered. Traditionally filtration was carried out using long-fibre pulp filters but these have several disadvantages including cost. Thus, the pulp needs to be washed and pressed into filter-pads before use and when the pads are blinded, they are shredded prior to rewashing of the pulp. In many breweries therefore, rough clarification is carried out... 

Prior to the introduction of filter sheets, many breweries used cellulosic pulp filters or filter mass . A small number of breweries still use them for rough filtration and remarkable strides have been made in reducing the manpower required to maintain them. The pulp is compressed by the breweries into circular thick pads which are fitted into a type of filter frame. 

A significant reason for the majority of oil and fuel system failurcs is the presence of high water levels as dissolved, dispersed, and free water, which degrades the fuels and oils. There are mainly four types of nonwoven filter media fiequently used for the removal of water contaminations contained in a wide range of fuel and oil products, such as aviation fuel, automotive diesel, and hydraulic oils. They include ceUulosic pulp filter, man-made fibre filter, glass fibre media, water adsorption (eg. 

US 4455237 High bulk pulp, filter media utilizing such pulp, related processes. 1984. 

The fluid extracted from fresh pineapple by pressing the pulverized fruit pulp, filtering the juice, adding back some of the pulp, heat processing at 140-145°F (60-63 C), pressure homogenizing to keep the pulp suspended, filling into cans, and pasteurizing at 190 F (88 Q. 

Aloisture Absorbent Synthetic Paper. Processes for making a water absorbent synthetic paper with dimensional stabihty have been developed by several companies. In a process developed by Mitsubishi Rayon, acrylic fiber is insolubilized by hydra2ine and then hydroly2ed with sodium hydroxide. The paper, formed from 100 parts fiber and 200 parts pulp, has a water absorption 28 times its own weight (96). Processes for making hygroscopic fibers have also been reported in the patent Hterature. These fibers are used in moisture absorbing nonwovens for sanitary napkins, filters, and diapers. 

Xanthation. The viscose process is based on the ready solubiUty of the xanthate derivative of ceUulose in dilute sodium hydroxide. The reaction between alkaU ceUulose and carbon disulfide must therefore be as uniform as possible to avoid problems with incompletely dissolved pulp fibers that wUl later have to be filtered out of the viscous solution. 

Filtration of viscose is not a straightforward chemical engineering process. The solution of cellulose xanthate contains some easy-to-deal-with undissolved pulp fibers, but also some gel-like material which is retarded rather than removed by the filters. The viscose is unstable and tends to form more gel as it ages. Its flow characteristics make the material close to the walls of any vessel or pipe move more slowly, get older, and gel more than the mainstream viscose. So while filtration can hold back gels arising from incomplete mixing, new gels can form in the pipework after the filters. 

Multicompartment dmm filters range in size from about 1 m to over 100 m they are widely used in mineral and chemical processing, in the pulp and paper industry, and in sewage and waste materials treatment. 

Rotary kilns and, to a lesser extent, Fluo-SoHds kilns are used to calcine a wet precipitated calcium carbonate filter cake in the kraft or sulfate paper-pulp process (15). Lime is regenerated for use as a causticization reagent in recovering caustic soda for pulp digestion. Losses in lime recovery are replaced by purchased lime (see Paper Pulp). 

In 1992, as much as two-thkds of all spunlace fabrics were used in medical products other appHcations included wipes, industrial apparel, intedinings, absorbent components, filtration, and coating. Medical product appHcations also accounted for about one-thkd of all wet-laid nonwovens other appHcations included tea bags, meat casings, filter media, battery separators, and wipes. Most bonded-pulp fabrics were used as wipes or absorbent components. 

Nonwood fibers are used in relatively small volumes. Examples of nonwood pulps and products include cotton Enters for writing paper and filters, bagasse for cormgated media, esparto for filter paper, or Manila hemp for tea bags. Synthetic pulps which are based on such materials as glass (qv) and polyolefins also are used (see Olefin polymers). These pulps are relatively expensive and usually are used in blends with wood pulps where they contribute a property such as tear resistance, stiffness, or wet strength which is needed to meet a specific product requirement. 

A pilot plant ia India has been estabUshed to extract fiber, pulp, and juice from the leaves of sisal plants. The fiber is sold direcdy or used to manufacture rope, the cmshed pulp is used ia paper processiag, and the juice is an excellent source of hecogenin. During a three- to five-day fermentation of the juice, partial enzymatic hydrolysis causes hecogenin to precipitate as the hemisaponin ia the form of a fine sludge. This sediment is hydrolyzed with aqueous hydrochloric acid, neutralized, and filtered. This filter cake is washed with water and extracted with alcohol. The yield of hecogenin varies between 0.05 and 0.1% by the weight of the leaf (126). 

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