Ethylene glycol vapor pressure

A stream of ethylene glycol vapor at its normal boiling point and 1 atm flowing at a rate of 175 kg/min is to be condensed at constant pressure. The product stream from the condenser is liquid glycol at the condensation temperature. 

Fig. 1. Vapor pressures of glycols at various temperatures. A, ethylene glycol B, diethylene glycol C, triethylene glycol and D, tetraethylene glycol.

Membrane Pervaporation Since 1987, membrane pei vapora-tion has become widely accepted in the CPI as an effective means of separation and recovery of liquid-phase process streams. It is most commonly used to dehydrate hquid hydrocarbons to yield a high-purity ethanol, isopropanol, and ethylene glycol product. The method basically consists of a selec tively-permeable membrane layer separating a liquid feed stream and a gas phase permeate stream as shown in Fig. 25-19. The permeation rate and selectivity is governed bv the physicochemical composition of the membrane. Pei vaporation differs From reverse osmosis systems in that the permeate rate is not a function of osmotic pressure, since the permeate is maintained at saturation pressure (Ref. 24). 

Liquid Sorption. If a moist gas is passed through sprays of a liquid sorbent, such as lithium chloride or an ethylene glycol solution, moisture is removed from the air at a rate depending on the vapor pressure difference. This is a function of the absorbent concentration and is maintained at the required level by a regeneration cycle. The regeneration process is continuous and is achieved by allowing a percentage of the chemical into the exhaust-heated air. 

Calculate the vapor pressure of water over each of the following ethylene glycol (C2H602) solutions at 22°C (vp pure water = 19.83 mm Hg). Ethylene glycol can be assumed to be nonvolatile. 

A two-step methanolysis-hydrolysis process37 has been developed which involves reaction of PET with superheated methanol vapors at 240-260°C and atmospheric pressure to produce dimethyl terephthalate, monomethyl terephthalate, ethylene glycol, and oligomeric products in the first step. The methanolysis products are fractionally distilled and the remaining residue (oligomers) is subjected to hydrolysis after being fed into the hydrolysis reactor operating at a temperature of ca. 270°C. The TPA precipitates from the aqueous phase while impurities are left behind in the mother liquor. Methanolysis-hydrolysis leads to decreases in the time required for the depolymerization process compared to neutral hydrolysis for example, a neutral hydrolysis process that requires 45 min to produce the monomers is reduced... 

C12-0064. Ethylene glycol, an automobile coolant, has the chemical formula HOCH2 CH2 OH. Calculate the vapor pressure of water above a coolant solution containing 65.0 g of ethylene glycol dissolved in 0.500 L of water (density = 1.00 g/mL), at 100 °C, the boiling point of pure water. 

Ethylene glycol is not as active in depression of the freezing point as methanol, but it has a very low vapor pressure evaporation loss in a coolant system is due more to the evaporation of water than to the evaporazation of ethylene glycol. Furthermore, the flammability problem is literally eliminated. 1 1 mixtures of ethylene glycol and water do not exhibit a flash point at all. 

Coupling Medium. Distilled water has proven to be more effective than tap water as the conducting liquid as evidenced by greater cavitation in the reaction flasks (and faster reaction rates). Moreover, distilled water leads to significantly less corrosion of the bath walls. Other low vapor pressure liquids such as ethylene glycol can be used. 

SI water= ethylene glycol water where APwater = vapor pressure lowering of water, H20... 

CH2OH)2 (g). Vapor pressure data on ethylene glycol were reported by de Forcrand.33 Louguinine2 measured the heat of condensation. These data yield V = —14.3 and —11.8, respectively. 

Choose as standard states for water and ethylene glycol the pure liquids at 1 bar and for ethylene oxide the pure ideal gas at 1 bar. Assume that the Lewis/Randall rule applies to the water in the liquid phase and that the vapor phase is an ideal gas. The partial pressure of ethylene oxide., river the liquid phase is given by, ... 

The vapor pressure of ethylene glycol at 25 °C is so low that its concentration in the vapor phase is negligible. 

In the glycol reactor (2), sufficient residence time is provided to react (noncatalytically) all of the ethylene oxide. Operating pressure of the reaction is controlled at a level that limits or avoids vaporization of ethylene oxide from the aqueous solution. 

Reported vapor pressures of ethylene glycol at various temperatures and the coefficients for the vapor... 

FIGURE 11.1.1.15.1 Logarithm of vapor pressure versus reciprocal temperature for ethylene glycol. 

Water was selected for the sealing liquid for which EG(Ethylene Glycol) could be a candidate. EG shows a very low vapor pressure but too high solubility for acetone. As acetone is less soluble in water than in EG, in spite of higher vapor pressure, water was used for sealing liquid and the moisture included in the emitted stream from the pump was supposed to be captured in diyers. 

Test your program by fitting the data for ethylene glycol given in Problem 6.4. Then use your formula to estimate the vapor pressures of this substance at 50 C, 80°C, and 110°C, and the boiling points at 760 mm Hg and 2000 mm Hg. In which of the last two values would you have the least confidence Explain your reasoning. 

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