Ethylene, thermodynamic properties

Hypercompressors. In an LDPE plant a primary compressor, usually of two stages, is used to raise the pressure of ethylene to about 25—30 MPa and a secondary compressor, often referred to as a hypetcomptessot, is used to increase it to 150—315 MPa (22,000—45,700 psi). The thermodynamic properties of ethylene ate such that the secondary compressor requires only two stages and this results in a large pressure difference between the second stage suction and discharge pressures. 

Ethylene is the lightest olefin. It is a colorless, flammable gas with a slightly sweet odor. Physical and thermodynamic properties are given in many references (1 7), and are briefly summarized in Tables 1—3. 

The increasing ranges of pressure and temperature of interest to technology for an ever-increasing number of substances would necessitate additional tables in this subsection as well as in the subsec tion Thermodynamic Properties. Space restrictions preclude this. Hence, in the present revision, an attempt was made to update the fluid-compressibihty tables for selected fluids and to omit tables for other fluids. The reader is thus referred to the fourth edition for tables on miscellaneous gases at 0°C, acetylene, ammonia, ethane, ethylene, hydrogen-nitrogen mixtures, and methyl chloride. The reader is also... 

The process gas of ethylene plants and methyl tertiary butyl ether plants is normally a hydrogen/ methane mixture. The molecular weight of the gas in such processes ranges from 3.5 to 14. The tliermodynamic behavior of hydrogen/methane mixtures has been and continues to be extensively researched. The gas dynamic design of turboexpanders, which are extensively used in such plants, depends on the equations of state of the process gas. Optimum performance of the turboexpander and associated equipment demands accurate thermodynamic properties for a wide range of process gas conditions. 

Figure 11-26. Vapor pressure curve for ethylene refrigerant. (Used by permission Starling, K. E. Fluid Thermodynamic Properties for Light Petroleum Systems, 1973. Gulf Publishing Co., Houston, Texas. All rights reserved.)...

Figure 56. Dependence of the thermodynamic properties of HC1 on co-solvent mole fraction in ethylene glycol + water mixtures at 298 K (Stern and Nobilione, 1968).

Recent investigations have shed light on peculiarities of the NOS action mechanism the role of the H4B cofactor and CaM, and cooperativity in kinetic and thermodynamic properties of different components of the nitric oxide synthesis system. Stop flow experiments with eNOS (Abu-Soud et al., 2000) showed that calmodulin binding caused an increase in NADH-dependent flavin reduction from 0.13 to 86 s 1 at 10 °C. Under such conditions, in the presence of Arg, heme is reduced very slowly (0.005 s 1). Heme complex formation requires a relatively high concentration ofNO (>50 nM) and inhibits the entire process NADH oxidation and citrulline synthesis decreases 3-fold and Km increases 3-fold. NOS reactions were monitored at subzero temperatures in the presence of 50% ethylene glycol as an anti-freeze solvent (Bee et al., 1998). 

Ambrose, D., Hall, D.J. (1981) Thermodynamic properties of organic oxygen compounds. L. The vapour pressures of 1,2-ethanediol (ethylene glycol) and bis(2-hydroxyethyl) ether (diethylene glycol). J. Chem. Thermodyn. 13, 61-66. 

Thermodynamical Properties of Ethylenes Substituted by Heteroatoms or Functional Groups (in kcal mol"1)... 

Temkin and co-workers have investigated the thermodynamic properties of the soluble complexes of unsaturated hydrocarbons with various metal salts with particular reference to their role in catalytic reactions. Using a potentio-metric technique, they were able to calculate the thermodynamic data shown in Table 6 for the silver(I)-acetylene complexes 30) and the silver(I)-ethylene complex 31). The results obtained for acetylene have been related to the low activity of silver salts as catalysts for the hydration of acetylene. For the sil-ver(I)-ethylene complex, the relationship between the ionic concentrations and... 

Should have similar thermodynamic properties to ethylene glycol + water mixtures (so that the size of the radiator will not have to be changed)... 

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