Gas stripping

Traditional Processes. The two primary stripping vapors are steam and air. Steam is used when the concentration of bromine in brine is greater than 1000 ppm. The advantage is that bromine can be condensed direcdy from the steam. Air is used when seawater is the source of bromine because very large volumes of stripping gas are needed and steam would be too expensive. When air is used the bromine needs to be trapped in an alkaline or reducing solution to concentrate it. 

By-product formation can also be reduced by use of a stripping gas or vacuum to faciUtate removal of ammonia (88) however, sublimation of urea becomes excessive if the pressure is too low. Addition of ammonium salts (eg, CU, NO7, or ) (89—91), acids, or pyrolysis of preformed urea salts, eg,... 

Seal legs are frequently used in conjunction with solids-flow-control valves to equ ize pressures and to strip trapped or adsorbed gases from the sohds. The operation of a seal leg is shown schemati-caUy in Fig. 17-19. The sohds settle by gravity from the fluidized bed into the seal leg or standpipe. Seal and/or stripping gas is introduced near the bottom of the leg. This gas flows both upward and downward. Pressures indicated in the ihustratiou have no absolute value but are only relative. The legs are designed for either fluidized or settled solids. 

Check the stripping gas, if applicable, to be sure there is a positive flow of gas. Be sure steam is not back-flowing into the accumulator from the reboiler. 

Be sure the stripping gas valve is open and the accumulator is vented to the atmosphere. 

Amine strippers use heat and steam to reverse the chemical reactions with CO2 and H2S. The steam acts as a stripping gas to remove the COo and HjS from the liquid solution and to cairy these gases to the overhead. To promote mixing of the solution and the steam, the stripper is a trayed or packed tower with packing normally used for small diameter columns. 

If a very lean glycol is required, it may be necessary to use stripping gas. A small amount of wet natural gas can be taken from the fuel stream or contactor inlet stream and injected into the reboiler. The stripping gas can be taken from the fuel stream or the contactor inlet stream and injected into the reboiler. The leaness" of the gas depends on the purity of the wet glycol and the number of stages below the reconcentrator. The stripping gas is saturated with water at the inlet temperature and pressure conditions. but adsorbs water at the reboiler conditions of atmospheric pres-... 

I riethylene glycol—Most common. Reconcentrate at 340 F to 4()0°F for high purity. At contactor temperatures in excess ot 1 2(1 F tends to have high vapor Ilis.scs to gas. Dew point depressions up to 150 F are possible with stripping gas. 

When higher lean glycol concentrations are required, stripping gas can be added to the reboiler, or the reboiler and still column can be operated at a vacuum. 

The lean glycol concentration leaving the reboiler can be lowered by contacting the glycol with stripping gas. Often, wet gas that is saturated with water vapor at ambient temperature and 25 to 100 psig is used. Al 25 psig and 100°F this gas is saturated with 1,500 Ib/MMscf of water vapor. At atmospheric pressure and the temperatures in the reboiler the gas can absorb over 100,000 Ib/MMscf. 

Stripping gas will have the effect of requiring reduced top still temperature to produce the same reflux rate. 

Sat w/water at 1,000 psig, 100°F Dehydrate to 7 Ib/MMscf Use triethylene glycol No stripping gas,... 

These gas transfer membranes or membrane contactors employ microporous polypropylene hollow fiber membranes arranged in a modular design. Oxygenated water flows on the shell side of the hollow fibers, and a strip gas (such as nitrogen) or a vacuum is applied to the inside (lumenside), with the hollow fibers acting as a support medium for intimate contact between the water and gas phases. 

The aqueous stream is at higher pressure than the strip gas (or vacuum) and fast diffusive transport of dissolved gases takes place. Gas transfer membrane technology is suitable for deaeration of boiler feed, building water, and other applications, and produces water with DO levels down to 1 ppb 02. 

V total voluM of stripping gas passed through the solution. In the - Bost favorable case, that of volatile nonpolar analytes, KV will... 

The coke oven is treated in the by-product plant to recover some important chemicals from it, after which the coke oven gas is used as gaseous fuel in the furnaces of steel plant. Coke oven gas is emitted at about 700 °C and is cooled to 80 °C with ammoniacal liquor (NH4OH) by spraying its goose neck. Here, the tar from the coke oven gas is condensed and separated in the separator. A further cooling of the gas to about 30 °C is accomplished in the primary cooler by water, and a further quantity of tar is condensed. The last traces of tar vapour present in the gas are removed in the next operation, which involves bringing the cooled gas to the electrostatic tar precipitator. This sends the tar-stripped gas to the... 

Stripping with steam, air or under vacuum (followed by a further treatment of the stripping gas). Applicable to volatile pollutants... 

Stripping (hydrogen sulphides) followed by treatment of the stripping gas... 

In this process developed by Lurgi [17], the phenolic effluent is contacted with the solvent in a multistage mixer-settler countercurrent extractor (Fig. 10.8). The extract, containing phenol, is separated into phenol and solvent by distillation and solvent is recycled to the extractor. The aqueous raffinate phase is stripped from solvent with gas, and the solvent is recovered from the stripping gas by washing with crude phenol and passed to the extract distillation column. 

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