Discontinuous Plants

This quiz was not intended to remotely suggest that plants discontinue inerting tanks containing flammable liquids. It was not to suggest that we re-evaluate the safety precautions in our procedures and design criteria conversely, this exercise emphasizes their importance. 

This plant discontinued operations in 2000 due to the difficulty of obtaining supplies from Japan. 

Imperial Chemical Industries (ICI) operated a coal hydrogenation plant at a pressure of 20 MPa (2900 psi) and a temperature of 400—500°C to produce Hquid hydrocarbon fuel from 1935 to the outbreak of World War II. As many as 12 such plants operated in Germany during World War II to make the country less dependent on petroleum from natural sources but the process was discontinued when hostihties ceased (see Coal conversion PROCESSES,liquefaction). Currentiy the Fisher-Tropsch process is being used at the Sasol plants in South Africa to convert synthesis gas into largely ahphatic hydrocarbons at 10—20 MPa and about 400°C to supply 70% of the fuel needed for transportation. 

Commercial VPO of propane—butane mixtures was in operation at Celanese Chemical Co. plants in Texas and/or Canada from the 1940s to the 1970s. The principal primary products were acetaldehyde, formaldehyde, methanol, and acetone. The process was mn at low hydrocarbon conversion (3—10%) and a pressure in excess of 790 kPa (7.8 atm). These operations were discontinued because of various economic factors, mainly the energy-intensive purification system required to separate the complex product streams. 

Whereas new appHcations of lithium compounds were developed, commercial growth was slow. In 1953 worldwide sales of lithium products, expressed as lithium carbonate, were only ca 1000 metric tons (2). In 1954 the U.S. lithium industry underwent a sudden, very large expansion when the U.S. Atomic Energy Commission required large amounts of lithium hydroxide [1310-65-2] for its nuclear weapons program (see Nuclearreactors). Three domestic producers built 4500-t/yr plants to meet contract commitments with the U.S. government. When these government contracts ended in 1960, capacity exceeded demand and several operations were discontinued. 

India, Goa and Bombay two plants built ca 1950 batch-type open-hearth roasters ceUs are operated discontinuously, the KMnO is crystallized separately in agitated tanks 1,200 114... 

For pipelines in service in chemical plants, it is not usually convenient to place a radiation source inside the pipe and position it to irradiate each welded joint. The radioisotope source container maybe placed on the outer surface of the pipe. The radiation beams then pass through two pipe wall thicknesses to expose films placed diametrically opposite the radiation source, also on the outside of the pipe wall. Other methods, such as magnetic particle inspection of welds in steel pipe, or ultrasonic inspection of welds in pipes of all materials, supplement x-rays in many critical appHcations. The ultrasonic tests can often detect the thin, laminar discontinuities parallel to the pipe surface or the incomplete fusion discontinuities along the weld... 

At Great Salt Lake Minerals Corporation (Utah), solar-evaporated brines are winter-chilled to —3° C in solar ponds. At this low temperature, a relatively pure Glauber s salt precipitates. Ponds are drained and the salt is loaded into tmcks and hauled to a processing plant. At the plant, Glauber s salt is dissolved in hot water. The resulting Hquor is filtered to remove insolubles. The filtrate is then combined with soHd-phase sodium chloride, which precipitates anhydrous sodium sulfate of 99.5—99.7% purity. Great Salt Lake Minerals Corporation discontinued sodium sulfate production in 1993 when it transferred production and sales to North American Chemical Corporation (Trona, California). 

Economic Aspects and Uses. In 1976, one-third of the lithium produced in the United States was extracted from brines of Seades Lake and Silver Peak (44,45). Since then, lithium production at Seades Lake has been discontinued and the lithium concentration at Silver Peak is decreasing. During the 1980s lithium extraction was started at the Salar de Atacama, Chile. This is the largest lithium production plant in the wodd using brine as its raw material. 

Hydrolysis using aqueous alkaH has been found to remove ash material including pyrite. A small pilot plant for studying this process was built at the BatteUe Memorial Institute in Columbus, Ohio (74) and subsequentiy discontinued. Other studies have produced a variety of gases and organic compounds such as phenols, nitrogen bases, Hquid hydrocarbons, and fatty acids totaling as much as 13 wt % of the coal. The products indicate that oxidation and other reactions as weU as hydrolysis take place. 

A thorough analysis should be made before production is stopped on a product that is losing money. Although direct costs of the discontinued product will be saved, overheads are not ehminated, as might be inferred from taking overheads as a percentage of direct material, direct labor, or prime costs. The plant is stiU there, together with its... 

The Event Data Store, applying specifically to nuclear power plants but discontinued because of high cost (approximately 1000 times normal rates)... 

Total reflux exists in a distillation column, whether a binary or multicomponent system, when all the overhead vapor from the top tray or stage is condensed and returned to the top tray. Usually a column is brought to equilibrium at total reflux for test or for a temporary plant condition which requires discontinuing feed. Rather than shut down, drain and then re-establish operating conditions later, it is usually more convenient and requires less... 

Because of their cellular or open-matrix construction, most insulants have an inherent ability to absorb sound, act as panel dampers and reduce noise breakout from plant by their ability to be a flexible or discontinuous link between an acoustically active surface and the outer cladding. This secondary aspect of thermal insulation specification will gain more prominence when the UK adopts the EC Directive 86/1888, Protection of workers from the risks related to exposure to noise at work . 

While ideally structures should be designed and fabricated so that environment-sensitive cracking is avoided, in practice it is sometimes necessary to live with the problem. This implies an ability to detect and measure the size of cracks before they reach the critical size that may result in catastrophic failure. Such inspection has important implications for plant design, which should be such as to allow inspection at relevant locations. The latter are regions of high residual stress (welded, bolted or riveted joints) and regions of geometrical discontinuity (notches, crevices, etc.) where stress or environment concentration may occur. 

A total of eight separate leather facilities were surveyed for the presence of N-ni croso compounds and two of these were resurveyed, Four of the eight plants were found to have airborne NDMA at levels greater than 0.5 yg/m. Table IV summarizes the operations of each plant and the highest level of NDMA found at that plant. The use of.DMAS is associated with the presence of airborne NDMA. Even a facility which had recently discontinued the use of DMAS, and another which used DMAS on an experimental basis, contained airborne NDMA. 

Automated titrations can be divided into discontinuous and continuous, the former representing a discrete sample analysis, as a batch titration is the usual laboratory technique and the latter a flow technique, which is used less frequently in the laboratory, e.g., in kinetic studies, but is of greater importance in plant and environment control. 

For desorption the vapor desorbed from the silica gel has to be condensed. For this reason a low temperature heat sink is required. The hydraulics of the plant provides two heat sinks a 10 m3 rain water cistern and the thermal solar plant. With these heat sinks two desorption modes could be carried out a desorption with simultaneous condensation of the vapor an a second mode in which the desorption and condensation were not done simultaneously. If desorption and condensation of the vapour occur at the same time, then the condensation heat is rejected via the rain water cistern. The condensation heat can also be removed by the solar plant when the desorption and condensation operation are discontinuous. In this case the solar plant heats up the adsorber during daytime but no condensation is done. The condensation take place through the solar system during the night given correspondingly low outside temperatures. 

Oxidation of benzene to phenol. This was attempted in the former U.S.S.R. and Japan on a pilot-plant scale. High yields were reported, but full-scale operation apparently was discontinued because of destruction of product by irradiation and the possibility of explosion in the reaction vessel. The latter danger can be controlled in the oxidation of halo-genated hydrocarbons such as trichloro- or tetrachloroethylenes, where a chain reaction leads to the formation of dichloro- or trichloro-acetic acid chlorides through the respective oxides. 

Hydromorphological alterations (hydropower plants, destruction of riparian quality, biological discontinuity, ecological minimum flows, etc.)... 

Plants readily accumulate lead from soils of low pH or low organic content however, uptake is significantly reduced after the application of lime or phosphate, which converts lead to hydroxides, carbonates, or phosphates of relatively low solubility (Demayo et al. 1982). Lead persists for lengthy periods in forest litter the estimated Tb 1/2 is 220 years (Turner et al. 1985). High levels of lead persisted for at least 6 years in litter, soil, amphibians, and mammals after zinc smelting was discontinued in Palmerton, Pennsylvania (Storm et al. 1994). Lead seems to be tightly bound by... 

The Hogshooter plant, located in the United States, has a range of operation from 120 X 106 to 200 X 106 lb/year. The variable cost structure is rather complicated due to the effects of extreme reaction conditions, separation tower limitation, and several byproducts, which are affected by environmental considerations. These considerations cause a discontinuity in the incremental variable cost curve at 140 X 106 lb/year as given by the following equations ... 

Le Maguer and Yao (1995) presented a physical model of a plant storage tissue based on its cellular structure. The mathematical equivalent of this model was solved using a finite element-based computer method and incorporated shrinkage and different boundary conditions. The concept of volume average was used to express the concentration and absolute pressure in the intracellular volume, which is discontinuous in the tissue, as a... 

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