High-pressure removal with water

High-Pressure Removal with Water. Paint can be removed from a metallic substrate (e.g., grids and skids) by the high kinetic energy of a high-pressure (70 100 MPa) water Jet. 

The cassiterite ore is obtained by dredging, open-cast mining, or gravel-washing, in which the ore is washed out of the deposit with high-pressure jets of water. The cassiterite has a density 2.5 times that of sand, and the ore is concentrated by gravity. It is roasted to remove arsenic and sulfur, and to convert metal sulfides into oxides, then it is reduced by smelting with coal or fuel oil in a reverberatory, rotary, or electric furnace (Equation 1.1.1). 

Water imbibed with superabsorbent polymers can hardly be removed even by applying high pressure, but the water absorbed is gradually removed by drying in air. In Fig. 8, the time dependence of decrease of water absorbed with vinyl alcohol/acrylic acid copolymers by drying at the temperatures of 20""C, 50""C, and 100°C is shown. 

The reverse-flow tank reactor is based on the use of a high-pressure tank with hot and cold zones (Fig. 4). The high-pressure feed is injected downward into the center region where oxidation of the organics and precipitation of salts occur. The produced gases move up and leave through the exit at the top. The lower section is cooled by injecting cold water, and hence remains in the liquid phase in which salts dissolve. The salts are easily removed off the reactor as brine from the... 

An alternative to drilling is to use a bullet or scraper that is "fired" along the length of the tube to scrape away the deposit. The projectile is propelled through the tube by a stream of high pressure air or water or both. The technique is only applicable to the inside of tubes. Examples of scrapers or bullets are shown on Fig. 15.11. It will be seen that in general the cleaners have a core with a surrounding open scraper structure that facilitates deposit removal and carries debris forward. 

Most of the water is removed as bottoms in colitrtm C-1 (Fig. 11.4-6). The liquid azeotropic overhead fraction is pressurized to approximately 4 bar and fed irrto a membrane stack (5-7 stages). Water preferably penetrates the membrane. Due to the high pressure difference the water-rich permeate is flashed in the merrrbrane. After eorrdensation it is recycled into eolrrrtm C-1. The retentate is very rieh in orgarric compounds and, in turn, often meets the product specification. If not, the retentate is fed into column C-2 for further purificatioa Decisive for the process is the availabihty of efficient membranes with both a high capacity and a high selectivity. 

The cross section of a standard cell is shown in Fig. 1. A balanced dimension of channel cross section and contact area has to be found for the channel design. To permit a high power density, the channel depth is limited. A high pressure drop supports water removal and gas distribution between the channels. A low pressure drop ensures good system efficiency. One limiting factor of mass transport is the width of the contact area. With increased production of water in the contact area, oxygen diffusivity is hindered more and more, i.e., these areas become more and more inactive. 

The dibenzyl ketone has a very high b.p. (ca. 200°/21 mm.) and this remains in the flask when the unsymmetrical ketone has been removed by distillation. The dialkyl ketone has a comparatively low b.p. and is therefore easily removed by fractionation under normal pressure acetone is most simply separated by washing with water. In this way methyl benzyl ketone (R = CHj), ethyl benzyl ketone (R = CHgCH,) and n-propyl benzyl ketone (R = CHjCHjCH,) are prepared. By using hydrocinnamic acid in place of phenylacetic acid ... 

Pollution Prevention. Procedures haven been developed for recovery of composite ammonium perchlorate propellant from rocket motors, and the treatment of scrap and recovered propellant to reclaim ingredients. These include the use of high pressure water jets or compounds such as ammonia, which form fluids under pressure at elevated temperature, to remove the propellant from the motor, extraction of the ammonium perchlorate with solvents such as water or ammonia as a critical fluid, recrystalli2ation of the perchlorate and reuse in composite propellant or in slurry explosives or conversion to perchloric acid (166,167). 

Hydrazine forms a high (120.5°C) boiling azeotrope with water that has a composition of 58.5 mol % (71.48 wt %) N2H4 at 102.6 kPa (1.02 atm) pressure. This comphcates the separation of hydrazine from water in the manufacturing process because it necessitates the removal of a large amount of water in order to approach the azeotropic composition. 

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