Sulfuric operating dilution range

In conventional alkylation operations, 98 wt. %, sulfuric acid is used as the catalyst, although some processes use HF.The spent alkylation acid, withdrawn as 88-92% acid, is not consumed in the chemical sense, but is diluted by carbonaceous material and small amounts of water. Acid reconditioning is usually completed in a separate plant. The range in makeup acid requirement and in octane quality varies with plant design, with type of feedstock, and with alkylate product rate. A wide variety of feedstocks can be processed through alkylation plants, as both low and high boiling olefins can be alkylated. 

A modification of this technology has been used to treat solutions of ammonium salts and free ammonia. The stripped ammonia in the exit air stream subsequently is absorbed into a dilute sulfuric acid solution in a packed column. The air leaving this absorber is ammonia-free, thus it is recycled back through the stripping column in a closed cycle. Such a system is described in U.S. patent 3,920,419 [10]. This process is operated at a temperature range of 140 to 180°F in order to raise the vapor pressure of the dissolved ammonia. At such temperatures only 50 to 100 CFM of air per gpm is needed to remove 99% of the ammonia from the feed. By minimizing the recycled air flow, the diameters of the stripper and absorber are reduced. 

Select one of the suggested curves outlined in Table 2. Prepare a series of calibration standards by making dilutions of the stock solution to cover the range of operation and consisting of sulfur type and matrix similar to samples to be analyzed. 

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