Lower ethylene oxide plant

Against these disadvantages, however, ethylene oxide involves a lower capital cost when compared with radiation plants. Autoclaving, which does not allow the product to be sealed in its container for treatment, is the quickest and cheapest process where heating of the product is unimportant. Dry heat is exceedingly difficult to apply uniformly owing to the poor thermal conductivity of many materials, and in any case there is an extensive range of products which simply cannot be sterilized thermally. 

A direct ethylene oxidation process for the acetic acid production was commercialized by Denko in 1997. This process is only competitive for small- or medium-scale plants. The raw material ethylene is more expensive than methanol and carbon monoxide, but the investment costs of these plants are much lower. Table 6.15.1 gives an overview of the catalysts, reaction conditions, yield, and byproducts for the major acetic add processes. The different processes are discussed in more detail in Sections 6.15.1-6.15.4. 

Two options are being developed at the moment. The first is to produce 1,2-propanediol (propylene glycol) from glycerol. 1,2-Propanediol has a number of industrial uses, including as a less toxic alternative to ethylene glycol in anti-freeze. Conventionally, 1,2-propanediol is made from a petrochemical feedstock, propylene oxide. The new process uses a combination of a copper-chromite catalyst and reactive distillation. The catalyst operates at a lower temperature and pressure than alternative systems 220°C compared to 260°C and 10 bar compared to 150 bar. The process also produces fewer by-products, and should be cheaper than petrochemical routes at current prices for natural glycerol. The first commercial plant is under construction and the process is being actively licensed to other companies. 

At the same time, advances in our knowledge of metabolic pathways and natural products have not been neglected. Thus, Hopanoids are described. Nitric oxide has been accorded a separate entry, and the five carbon pathway of 5-aminolevulinate synthesis is presented under Porphyrins. Chemiosmosis has been rewritten, and the classification and study of different ATPases is treated more thoroughly. Plant biochemists should note that all aspects of Photosynthesis in higher and lower plants and fungi have been reorganized and rewritten, and that plant hormones (in particular, ethylene and auxins) and phytochromes have been brought up to date. 

Feed ethylene is normally delivered to the plant by a pipeline grid or directly from a cracker on the same site. As the process is highly sensitive to impurities, sulphin compoimds, acetylene and other impurities are removed from the feed ethylene by purification beds. The cleaned feed ethylene is then compressed to the required reaction pressure and enters the reactor loop at the bottom of the reactor. A metal oxide catalyst, alinniniinn alkyl in hydrocarbon as a cocatalyst, lower olefins as comonomers and other auxihary chemicals are fed directly into tire reactor loop. Typically, different product types can be produced by selecting the catalyst system, the comonomers and the reaction conditions. 

Apart from methane, in the sump of the low-pressure column, ethane and propane are often to be found, even if only in traces in the lower vppb-range (pL m ), since these components are not completely retained by the upstream molsieve adsorbers. In industrial areas the LOX-sumps may also contain ethylene in trace amounts. In addition, a number of inert compounds like nitrous oxide enter the cryogenic part of an air separation plant, which could lead to the blockage of pump filters, passages of reboilers and analyzing lines. The following Table 2.10... 

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