High-purity steam condensate

Demineralizers are often used to treat raw makeup water or condensate where high purity is required, such as in large central station boHers that operate at high steam pressures. Demineralizers employ a combination of cation and anion exchange to remove additional material, including sodium and ammonium cations. VirtuaHy aH salt anions, such as bicarbonate, sulfate, and chloride, are removed and replaced by hydroxide ions in the demineralizer. 

A mixture of ethylene, high purity oxygen, and recycle gas is reacted in a vertical multitubular reactor filled with silver oxide catalyst. The exothermic heat of reaction is removed by the generation of steam in the reactor shell. The ethylene oxide product is absorbed from the reactor effluent gas with water. It is then recovered from the water stream by steam stripping, partial condensation, and adsorption to form a concentrated aqueous solution. The aqueous solution is further concentrated in a two-stage distillation system. The first-stage separates water and the second removes light ends. 

Following the rinse step, in step 3 of the cycle, the vessel is isolated and heated externally to cause the CO2 to desorb from the sorbent and the pressure to increase. High-pressure steam is then introduced counter-currently to the feed direction in order to push out the CO2 where it is then cooled to condense out water. This resulting CO2 stream is stated as having a purity of up to 99% and part of this can be used for the CO2 rinse step on another bed. 

Hydrogen separation membranes can be used to produce H2-rich streams for either H2 production or power generation with pre-combustion CO2 capture. In the latter case, high purity H2 is not required since it is used to fuel a combustion turbine in fact, dilution with membrane sweep gases such as steam and N2 actually reduces NO, formation by reducing the stoichiometric combustion temperature. In H2 production, high purity H2 (>99.9%) is generally required and only steam, which is easily separated by condensation, can be used as a sweep gas. 

The resistances of the internal electrode fills and external process fluid are normally only a few thousand ohms so that the potential drop due to leakage current flow is negligible. However, high purity water (Le., distilled water, de-ionized water or steam condensate) and non-aqueous solutions have an extremely high resistance (Rg) that approaches the resistance (R ) of the glass. 

CO2 Capture Experiments The experiments of CO2 capmre from a flue gas or synthesis gas were conducted in the gas permeation apparams described earlier (Tee et al., 2006 Zou and Ho, 2006). The gas used contained 20% CO2, 40% N2, and 40% H2. Steam was applied as the sweep gas since water condenses at ambient condition and a high-purity CO2 can be obtained readily from the permeate side. The gas permeation was performed at 110°C to achieve the best membrane separation performance. Feed-side and sweep-side pressures were set at 2 and 1 atm, respectively. A circular gas permeation cell with a membrane area of 45.6 cm was used. Both the retentate and permeate streams leaving the gas permeation apparatus were cooled down to ambient temperature in then-respective water knockout vessels, which removed the water condensed. 

A solution of 225 g. of sodium hydroxide (Note 3) in 250 ml. of water is poured into the reaction mixture. A heavy brown oil separates, consisting of S-2-furfurylisothiourea, which has already partially decomposed to 2-furfuryl mercaptan. The flask is quickly fitted with a steam-inlet tube and condenser. Steam distillation is continued as long as the distillate contains oily drops. The mercaptan is separated from the aqueous phase by means of a separatory funnel (Notes 7 and 8). The product is dried with calcium chloride yield, 313-340 g. (55-60%). The 2-furfuryl mercaptan so obtained is of a high degree of purity (Note 9) but can be distilled without decomposition in a nitrogen atmosphere b.p. 160°/759 mm., 84°/65 mm., n 1.533. 

Different designed solvent recovery systems are used. As an example there is the solvent system that consists of fixed bed adsorbers containing activated carbon and a distillation system. The carbon adsorbs the solvent vapors. Then the beds are steamed in sequence to remove the solvent. The solvent and steam are condensed into a large tank. The distillation system is then used to distill the solvent from the water to a purity of 99.99% so that it can be reused. Because of the high cost of solvent, complex monitoring equipment is used to insure a high rate of recover. 

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