Crude charge tank

A sudden drop in furnace feed temperature is commonly caused by a slug of bottoms sediment and water (BSJ crude charge. This happens when a tank in the crude supply system has been cleaned. The silt and waxy dirt were flushed down the crude line to the refinery. A floating suction in the refinery s crude charge tank minimizes the effects of these incidents. 

Bassett, J.D., Research on electrostatic hazards associated with tank washing in very large crude carriers (supertankers) II. Study of the charging mechanism during the production of water aerosols, J. Electrostatics, 1, No. 1, February 1975. 

Depending on the type and efficiency of the extraction equipment, the acetone/ crude lecithin ratio necessary to achieve a 95% phospholipid product is 10-20 1 (v/v). In batch extraction, the tank is charged with acetone prior to crude lecithin... 

The process illustrated here is a simple modification of a previous example. Shown in Fig. 7-25, this modified process prepares the crude ding as a slurry in a feed vessel. The slurry feed was continuously charged to a dissolver that was maintained at a temperature of about 50 C. The feed rate was controlled such that the slurry was put into solution in the dissolver, and the dissolved solution charged continuously to the crystallizer through an in-line filter to remove extraneous insoluble particles and traces of the undissolved product. The crystallizer contained the seed slurry with the correct form at a lower temperature, about 25 C. The crystallizer slurry was continuously filtered through a ceramic cross-flow Alter system with a pore size of 0.2 p-m, and the clear permeate was sent back to the dissolver for further solubilization of product. This was inn until the feed tank was empty and all supersaturation was relieved. The critical parameters for successful development of this process were solubilities of the polymorphs, seeding, and control of supersaturation. 

The charge is now given a neutralizing wash at 40-50 C with a warm sodium carbonate solution, until alkaline to phenolphthalein. When the nitrobenzene is intended for aniline production, this may be followed by a wash with aniline water from the reducer house if any has to be worked up. Otherwise, a final washing with a small quantity of warm water is made. The nitrobenzene is then delivered to its storage tanks, where it is again settled to remove final traces of water. The crude product can now be distilled for commerce or used directly for the preparation of aniline. In some plants where the nitrobenzene is used almost exclusively in the aniline plant, the neutralizing and subsequent washes are omitted. The nitrobenzene delivered to the reducer houses is consequently acid. No harmful effects on the equipment are noticeable, provided the acidity is kept below 0.5 per cent. 

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