Wash tower acid

Wash tower acid (scrubber discharge from the roaster acid plant). Typically this flow is about 25 m /h and it contains 10 g/L H2SO4, 0.5 g/L HF, 1 g/L HCl and 0.5 g/L Zn. 

These two streams cannot be treated in the SRB plant because their sulfate content is too high, and in case of the wash tower acid, the fluoride content is also high. Between 1995 and 1999 various processes were studied to treat these streams. The objective was to develop a process that allowed a direct purge of these streams or to have the capability of bleeding them, after a final treatment, to the SRB plant. Extensive testwork was done at the laboratory and pilot plant scale. Based on these results, the biological process route was chosen. 

Neutralization of the wash tower acid, WTA, with calcine... 

Bulk and suspension polymerisation are the most commonly used techniques. In bulk polymerisation styrene is heated to 80°C for about 2 days to get a viscous solution of polymer in styrene. The solution is then fed to a tower wherein polymerisation is completed at 100°C, 150C° and 180C° stagewise. In suspension process, styrene is suspended in dimineralised water in presence of suspending agent and initiator like benzoyl peroxide and heated to 20°C. The product is washed with acid, water and dried. 

A liquid/liquid separation of product and catalyst is done in separate vessels after the reaction has taken place. The reaction mixture is sent to a gas separator and from there to a counter current washing tower (a simple phase separator is shown in the figure) in which the effluent is treated with aqueous Na2C03. The acidic HCo(CO)4 is transformed into the water soluble conjugate base NaCo(CO)4. The product is scrubbed with water to remove the traces of base. The oxo-crude goes to the distillation unit. 

Ammonia is added to dust free, hot flue gas on the pressurized side of the blower. After passing through a regenerative heat exchanger (W4) the flue gas/ammonia mixture is treated in the first wash tower (B4) with a wash solution, formed by the ammonia, acidic components of the flue gas and water fed into the tower. Here the following reactions proceed simultaneously ... 

Water washing drilling mud from a plugged tower Acidize/degrease trays Reestablished liquid seal Foaming of degraded glycol... 

Whynes has presented data on the concentration of fluosilicic acid in equilibrium with SiF4 vapors these are reproduced in Figure 6-13. The curves indicate that an exhaust gas containing 0.3% silicon tetrafluoiide can produce a solution containing about 32% fluosilicic acid at temperatures below 70°C. This has been confirmed in a plant wash-tower by continuously recirculating the solution for several hours. 

So, the moment the manufacturing process stopped in 2005, the inside temperature of the first-turn chimney liner had reached up to 220 °C. At operation of the third-turn chimney liner at the entrance towards a wash tower there were drops of 84 % sulfur acid on surface FRP. 

In a typical gas oil design, the lighter products overhead from the quench tower/primary fractionator are compressed to 210 psi, and cooled to about 100°F. Some Q plus material is recovered from the compressor knockout drums. The gases are ethanolamine and caustic washed to remove acid gases sulfur compounds and carbon dioxide, and then desiccant dried to remove last traces of water. This is to prevent ice and hydrate formation in the low temperamre section downstream. 

Forms azeotropic mixts with butyl ale, acetic acid, heptane, toluene, nitroethane, perchioro-ethylene, w, etc. Prepn is by reacting propyl ale with coned nitric acid (d 1.41g/cc) dissolved in ethylacetate at 20°, followed by distn of the product. NPN can also be preod bv reacting a continuous stream of propyl ale below the surface of stirred mixed acid (20% nitric acid, 68% sulfuric acid and 12% w by wt) in a cooled (0—5°) open stainless steel vessel. Addnl mixed acid is also simultaneously introduced at about a third of the depth of the liq. An overflow pipe maintains a constant reactant level and the effluent prod is sepd, washed with 10% aq Na carbonate soln and dried by passage thru a Filtrol packed tower. Contact time of reactants can vary from 0.6 to 15 mins using about 50% isopropanol at 0° to yield 66.5% NPN (Ref 3b)... 

This method gives a somewhat tower yield than method 1. Dissolve 14.1 g l-nitro-3-butanone in 30 ml glacial acetic acid and heat to 35° add slowly with stirring to a solution of 5.3 g bromine in 10 ml glacial acetic acid. Evaporate in vacuum, dissolve residue in ether and wash with water, NaHC03 and water. Dry and evaporate in vacuum the ether (can distill 84/2) to get 6 g 1 -nitro-4-Br-3-butanone (1). Add 4.4 g (I) to 25 ml 48% HBr and reflux three hours. Add 50 ml water and steam distill. Neutralize the distillate with K carbonate and extract with ether. Dry and evaporate the extract (can distill 128/20) to get 5.6 g 2-Br-5-Br-methyl-isoxazole... 

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