Buildings com high security


In addition to being the preferred forming technique for ceramic rods and tubes, extmsion processes are used to fabricate the thick green sheets used in many electronic components (24,30,31). The smallest thickness for green sheets prepared by extmsion techniques is about 80 p.m. Organic additives similar to those used in tape casting are employed to form a high viscosity plastic mass that retains its shape when extmded. The extmsion apparatus, schematically shown in Figure 4, consists of a hopper for introduction of the plasticized mass, a de-airing chamber, and either a screw-type or plunger-type transport barrel in which the pressure is generated for passage of the plastic mass through a die of the desired geometry. The plastic mass is extmded onto a carrier belt and passed through dryers to relax the plastic strain remaining after extmsion. The green sheet can be stamped or machine diced to form disks, wafers, or other platelike shapes.  [c.311]

An important variation of this filter is based on replacing the rigid outer waU necessary for containing the feed and the cake on the rotating table by an endless mbber belt. The belt is held under tension and rotates with the table. It is in contact with the table rim except for the sector where the discharge screw is positioned, and where the belt is deflected away from the table to aUow the soHds to be pushed off the table. The cloth can also be washed in this section by high pressure water sprays. This filter, recendy developed in Belgium, is avaUable in sizes up to 250 m, operated at speeds of 2 minutes per revolution, and cake thicknesses up to 200 mm.  [c.395]

In the screw conveyor process, solutions of poly(vinyl acetate) and catalyst are mixed in a high intensity mixer and continuously introduced to a screw-type saponification and conveyor system (270). Downstream details are similar to those found in the belt process.  [c.485]

The cylinder mixer is commonly used for coarse-grained mixes. It is equipped with an axial rotating shaft fitted with several radial arms where paddles are attached. The intensity of this mixer is relatively low to avoid particle breakdown and long mixing times, such as 90 min, are therefore needed to complete the mixing operation. With fine-grained compositions, more intensive mixers may be used with a corresponding reduction in mixing time. Bread or sigma-blade mixers and the high intensity twin-screw mixers of the Wemer-Pfleiderer and Banbury variety are examples of the equipment that can be used on fine-grained compositions. For both mixers temperatures at the time of discharge are 160—170°C.  [c.502]

Other appHcations include (/) recovery of valuable components from metal plating or treating effluents, including the recovery of hydrofluoric and nitric acids by bipolar ED from stainless steel spent pidde Hquor (see Electroplating Metal surface treatments) (2) deashing of beet, cane, or other sugar (qv) juices and molasses. AX membranes are generally subject to fouling by medium molecular weight organic carboxyHc acids in such solutions. Although fouling resistant AX membranes have been proposed, the generally short processing season for such sugar solutions leads to high capital charges. Eurther the additional sugar which could be recovered through desalting is not justified in view of the agricultural poHcies of the sugar producing countries. There are few, if any, ED plants desalting sugar solutions (2) deacidification/acidification of fmit juices (qv). There are a few plants on a commercial scale (4) desalting of soy sauce, amino acid solutions, fermentation (qv) products, etc (see Amino acids). There are a few small ED plants in such appHcations and (3) demineralization of blood plasma (see Eractionation, BLOOD-PLASMAFRACTIONATIOn). There are few such plants.  [c.176]

Cleanliness Hardness Hydrostatic Tests Blade Shaker (Static) Rotor balance O Standard O High Speed Final Surface Inspection Crating inspection Spare Rotor Fit  [c.332]

A control innovation that has potential to broaden the screw compressor s application range is the variable-volume-ratio compressor. [4] A diagram of a low- and a high-volume-ratio compressor is shown together with a movable slide stop, which is used with the slide valve to form a variable volume ratio compressor in Figure 4-19. While the volume ratio terminology is more descriptive, it is more commonly known as built-in pressure ratio. By controlling inlet volume with the slide valve and the discharge volume by use of the slide stop, an infinite number of volume ratios can be achieved (see Figures 4-20 and 4-21).  [c.121]

Orifice scrubbers are used in industrial applications including food processing and packaging (cereal, flour, rice, salt, sugar, etc.) pharmaceutical processing and packaging and the manufacture of chemicals, rubber and plastics, ceramics, and fertilizer. Processes controlled include dryers, cookers, crushing and grinding operations, spraying (pill coating, ceramic glazing), ventilation (bin vents, dumping operations), and material handling (transfer stations, mixing, dumping, packaging). Orifice scrubbers can be built as high-energy units, but most devices are designed for low-energy service.  [c.441]

There are a number of other mixing configurations that have widespread applications to both liquid-solid and solid-solid blending operations. Emulsifiers are used as an alternative to slow-speed impeller mixing or high-pressure homogenization for a wide range of processing requirements. Typical applications include the preparation of adhesives (e.g., asphalts, carbon dispersions, clay dispersions, dyestuffs, paints and inks, lacquers), cosmetics (e.g., creams, emulsions, hand lotions, perfumes, shampoos, deodorants), foods (e.g., chocolate coatings, mustard, soft drinks, sugar emulsions), pharmaceuticals (e.g., antibiotics, ointments, reducing animal tissues), plastics (e.g., cold cutting resins, polyester dispersions, resin solutions) and various miscellaneous mixtures such as floor polishes, gum dispersions, lubricants, petroleum emulsions, etc. These types of mixers normally are used in dished or conical bottom vessels. The mixing process can be thought of as performed in three stages. In the first stage, the high-speed rotor operating at close clearance to the stator draws material in from the bottom of the mixing vessel and subjects it to intense mixing. In stage 2, the rotor accelerates the product toward the blade periphery. There it is expelled through openings in the stator into the body of the mix while undergoing an intensive mechanical and hydraulic shearing action. At the same time, new material is drawn  [c.440]

As the screw rotates inside the barrel, the movement of the plastic along the screw is dependent on whether or not it adheres to the screw and barrel. In theory there are two extremes. In one case the material sticks to the screw only and therefore the screw and material rotate as a solid cylinder inside the barrel. This would result in zero output and is clearly undesirable. In the second case the material slips on the screw and has a high resistance to rotation inside the barrel. This results in a purely axial movement of the melt and is the ideal situation. In practice the behaviour is somewhere between these limits as the material adheres to both the screw and the barrel. The useful output from the extruder is the result of a drag flow due to the interaction of the rotating screw and stationary barrel. This is equivalent to the flow of a viscous liquid between two parallel plates when one plate is stationary and the other is moving. Superimposed on this is a flow due to the pressure gradient which is built up along the screw. Since the high pressure is at the end of the extruder the pressure flow will reduce the output. In addition, the clearance between the screw flights and the barrel allows material to leak back along the screw and effectively reduces the output. This leakage will be worse when the screw becomes worn.  [c.251]

Screw compressors have no clearance volume, and may work at high compression ratios without loss of volumetric efficiency . In all screw compressors, the gas volume will have been reduced to a pre-set proportion of the inlet volume by the time the outlet port is uncovered, and this is termed the built-in pressure ratio. At this point, the gas within the screws is opened to condenser pressure and gas will flow inwards or outwards through the discharge port if the pressures are not equal.  [c.50]

Expression Dewaterings of Fibrous Materials. Fibrous materials are frequently dewatered in belt-filter, screw, disk, and roU presses and in batch pot and cage presses. Table 1 Hsts appHcations of screw, roU, and pot presses. Screw and high pressure belt presses are continuous and have replaced batch pot and cage presses in most appHcations. Traditionally, however, batch presses have been used for squee2ing cocoa butter from cocoa beans, which require pressures up to 41 MPa (6000 psi) (39). A description of many types of batch presses is included in Reference 40.  [c.19]

The photoreceptor should be mechanically robust. This term was coined to reflect the combined mechanical durabiUty, high scratch- and abrasion-(wear) resistance, high flexibiUty, resistance to cracking and cra ving if the photoreceptor is used as a flexible belt or scroU, smoothness, which is beheved to enable efficient cleaning of residual toner particles, as well as a chemical resistance to corotron effluents containing o2one, oxides of nitrogen, and other corrosive elements, compounds, or ions.  [c.130]

D-fructose, C HijOo. Crystallizes in large needles m.p. 102-104 C. The most eommon ketose sugar. Combined with glucose it occurs as sucrose and rafftnose mixed with glucose it is present in fruit juices, honey and other products inulin and levan are built of fructose residues only. In natural products it is always in the furanose form, but it crystallizes in the pyranose form. It is very soluble in  [c.182]

Smooth PVDF profiles of all types—film, sheet, rod, profile, pipe, tubing, fiber, monofilament, wire insulation, and cable-jackets—can be extmded no heat stabilizers are needed. In both molding and extmsion operations, care must be exercised to eliminate hang-up zones in the equipment where molten resin (at 230—260°C) can stagnate and thermally decompose with time. Equipment built with material of constmction used for processing polyolefins or PVC is adequate for long-term or high shear processing, a highly wear-resistant alloy such as Xaloy 306 for barrel liner and SAE 4140 steel for the screw is suggested. Gradual transition-type screws having L/D ratios at least 20 1, ample metering sections, and compression ratio of about 3 are recommended. Temperature profiles vary from 190 to 290°C depending on resin grade and shape being extmded. Water quenching is practiced for wire insulation, tubing, and pipe, whereas sheet and flat film are melt-cast on poHshed steel roUs operating at 65—150°C (157).  [c.388]

Although a BINSERT blender often requites more recinculation to achieve an acceptable blend than a multitube blender, it has a number of potential advantages including ease of cleaning siace all of the internal parts ate exposed and accessible blending cohesive, ie, nonfree-flowing materials siace the outlet can be sized as large as necessary for flow blending materials with high angles of internal friction and materials which ate highly segregating, eg, containing a wide range of particle sizes low headroom requirements siace the walls of the outer hopper can be made relatively shallow no mechanical moving parts other than perhaps a feeder, eg, belt, screw, or rotary valve used at the outlet to control the discharge rate, and a recinculation system and it can often be retrofitted to an existing storage bia causiag it to act as an ia-bia blender.  [c.562]

Water removed from the pulp slurry during washing passes through a mat of paper fibers. As more water is removed from the pulp, the pulp consistency at the washer discharge increases. Commercial washers can be classified on the basis of their discharge pulp consistency (23). Low consistency (<8%) washers employ sidehill screens and gravity deckers. Intermediate consistency (8—15%) washers are high speed belt washers, inclined screw extractors, and vacuum filters. High consistency washers (>15%) are screw presses and belt presses. Cellulose fiber loss is a function of washer design and pulp discharge consistency (23).  [c.8]

Vacuum drying is similar to atmospheric drying but does not require as high a temperature to drive the moisture loss it can be performed in a considerably smaller tower. Wet soap, heated to around 130—150°C in a low pressure heat exchanger, is sprayed onto the walls of an evacuated tower using a nozzle. The nozzle can either be unidirectional, mounted on a rotating shaft, or statically mounted and multidirectional. Cooling and drying is achieved in one step through the rapid release of moisture as vapor, which occurs upon introduction of superheated soap into the vacuum chamber (foule-Thompson cooling). The dried, cooled soap is scraped off the tower wall with a scraper blade mounted on a rotating shaft. The moisture in the dried soap is dependent on the flow rate, the temperature of the soap, and the pressure in the vacuum chamber the last also controls the final temperature of the soap. The dried soap is obtained at the bottom of the tower in the form of small pellets through an airlock created by the screw extmsion of the soap through a multiholed orifice plate. Vacuum drying has a number of advantages over atmospheric flash drying, including the lower pressure steam requirements, lower overall temperatures, and the more compact drying system/tower.  [c.156]

Another example of an alternative nutritive sweetener is fmctose [57-48-7]. Although naturally occurring and yielding ca 4 kcal/g (16.7 kJ/g), the same as sugar, fmctose does not cause a fluctuation ia blood sugar, ie, glucose levels after ingestion, making fmctose a better choice for diabetics (2). Fmctose is also more potent than sugar (ca 1.5 times) and therefore can be cost-effective for the food iadustry. The most popular form of fmctose used ia beverage products is a 55 45 mixture with glucose, usually referred to as high fmctose com symp (HFCS) (see Syrups). Fmctooligosaccharide, about half as sweet as sucrose, is alow calorie (ca 2 kcal/g (8.37 kJ /g)) sweetener approved for food use only ia Japan (3).  [c.272]

Continuous Saponification. There are several types of continuous processes, each with benefits and drawbacks. The basic premise is that continuous mixing is not required after the poly(vinyl acetate) and the caustic is mixed (261). Several designs for the high intensity mixing unit have been suggested in order to obtain efficient mixing and minimi2e fouling (262,263). Further handling of the reaction mixture on an industrial scale employs such techniques as the belt process, the slurry process, and the screw conveyor process.  [c.484]

Development of a flash coal pyrolysis reaction system was also carried out by Lurgi-Rhurgas (39). During the time period from 1940 to 1960 units processing 10 t/h were operated, and a small commercial plant was built and has operated ia the former Yugoslavia since 1963. As shown in Figure 9, coal is rapidly heated by mixing with hot recycled char in a screw conveyor-type reactor. Volatiles recovery is completed at 750°C in vessel number 4. A typical product distribution for this system operating on a high volatile West Virginia biturninous coal gave a tar yield of 28 wt %, char of 58 wt %, and gas + liquor of 14 wt % on a basis of MAF coal.  [c.288]

The premix is then melt compounded in a high shear extmder where the ingredients are compacted, the resin melts, and individual components are thoroughly dispersed in molten resin. These compounding machines generate sufficient heat through mechanical shear so that after start-up, htde external heat needs to be suppHed. Both single-screw machines such as the Buss Ko-kneader and twin-screw extmders such as the Werner Pdeiderer or Baker Perkins are used (see Plastics processing). Residence time in the extmder is in the range of 0.5—1.0 minutes, and melt temperatures for thermosetting materials normally mn from 60—140°C, slightly above the melting temperature of the resin. Because of the low temperatures and short residence time, Htde if any reaction between the resin and curing agents occurs. The molten compound is cooled rapidly by passing it through the nip of a water-cooled roU and subsequendy onto a continuous stainless steel water-cooled belt or dmm. The cooled compound is broken into small chips, about 10 x 12 mm, suitable for fine grinding. Thermosetting resins are quite friable and are usually ground to final particle size in an air classifying mill. In this grinder, a blower generates an air stream in which the product is entrained. A variable speed separator reduces air dow through the mill so that the larger particles are returned to the grinding chamber. The fine powder is separated from the air stream by a cyclone or dust collector. Finished powder can be packaged directiy from the cyclone, or screened to be sure there are no large particles in the final product. Frequentiy, a coUoidal siUca or alumina is mixed with the powder to improve handling and dry free-dow characteristics (53).  [c.323]

Expression is the appHcation of mechanical stress to a matrix of particles in the fully formed cake (12). Expression, which refers to squee2ing the sohds rather than the slurry (19), is used to further reduce void space in order to separate more Hquid from the soHds. Expression dewatering is most effective with compressible cakes (12,20) of particle si2es below 50 p.m (7), superflocculated cakes or cakes otherwise containing loosely entrapped Hquid, and organic solids containing Hquid-fiHed ceUs that must be mptured for effective dewatering. Filters that use expression include variable-chamber plate-and-frame filters, belt-filter presses, very high pressure belt presses (21,22), tube presses, and screw presses. Tube presses can exert pressures up to 14 MPa (2000 psi) (23), the highest pressure of any of these expression devices. After pressing, an air-blow step can be added to further reduce the entrained moisture (23). Screw presses are used primarily with fibrous or polymeric materials containing entrapped Hquid. Pressures up to 110 MPa (16,000 psi) have been measured in these devices at the points between the screw and screen when solids are present (24).  [c.19]

Some processing of organic chemicals by electrolysis for commercial purposes was carried out in the first half of the twentieth century. These were limited in number and mostiy small-scale appHcations. The industrial uses of electroorganic synthesis on a large scale have been very few. The first large plant was built by Adas Powder Co. in 1937 for the manufacture of sorbitol [50-70-4] and mannitol [87-78-5] using the cathodic reduction of glucose (see Sugar alcohols) (98). Production was at the rate of 1400 t/yr, but by 1947 this process was superseded by a high pressure catalytic hydrogenation method. In 1964, Nalco s tetraalkjllead process at Freeport, Texas came on stream. It had an original capacity of 14,000 t/yr tetramethyUead [75-74-1/, Q]H., ] h or 18,000 t/yr tetraethyllead [78-00-2], CgH2QPb. In the next year, Monsanto started production of adiponitrile [111-69-3], CgHgN2, by the electrohydrodimerization of acrylonitrile [107-13-1] at Decatur, Alabama, at similar rates.  [c.97]

The basic process steps for converting com into ethanol are degermination, milling, separation of starch-bearing endosperm from hulls, slurrying—hquefaction, hydrolysis of starch to sugar, fermentation, distillation, and dehydration (205). The hydrolysis or saccharification is usually carried out with an amylase enzyme and the fermentation is usually by the yeast Saccharomjces cerevisiae. Com can be prepared for fermentation by three different processes whole-grain grinding, dry milling, and wet milling. Whole-grain grinding requites the least capital investment but generates only one by-product, distiUers-dried grains (DDG) which is used to supplement animal feed. This process does not include the degermination step. A dry mill has the next lowest capital investment, but generates only the lower valued by-products including DDG. A wet mill is often built in conjunction with a plant that produces high fmctose com symp from part of the starch, which is used as a beverage sweetener. Other by-products from a wet mill are com gluten and com gluten meal, which are used for animal feeds. While more expensive to build and operate, the greater variety of by-products can help offset the price of com. Most of the fuel alcohol plants use the dry-mill or wet-mill process.  [c.409]

Capacity requirement is a prime factor in conveyor selection. Belt conveyors, which can be manufac tured in relatively large sizes to operate at high speeds, deliver large tonnages economically. On the other hand, screw conveyors become extremely cumbersome as they get larger and cannot be operated at high speeds without creating serious abrasion problems.  [c.1912]

In injection moulding a screw preplasticiser is preferred with melt temperatures in the usual range 335-400°C. Mould temperatures are in the range 100-160°C, the higher temperatures giving the more stress-free mouldings. Because of the high melt viscosity generous cross-section runners and gates are required. With time a black layer of degraded polymer may build up on the cylinder wall and eventually pull away, giving black marks to the moulding. This necessitates periodic purging. Purging should also be carried out if the machine to be used has been employed for moulding other polymers. Highly stabilised polypropylene and (more expensive) polycarbonates can be employed for this purpose.  [c.601]


See pages that mention the term Buildings com high security : [c.1644]    [c.4]    [c.217]    [c.616]    [c.198]   
Plant Engineer's Handbook (2001) -- [ c.51 ]