Treating processes

Petroleum contains impurities that have to be removed at different stages of the refinery. Some of the impurities can be harmful to the 

When the sulfur content of the crude oil is low (usually less than one percent by weight), the crude oil is known as a sweet crude, while crude oil with higher concentrations of sulfur is called sour crude. Removal of sulfur and other impurities form part of the treating processes and sulfur itself can form a valuable by-product in a refinery as an input into the chemical industry. Other impurities include nitrogen, oxygen, and salt, as well as small quantities of metals such as vanadium and nickel that are common in certain of the heavier crude oils. As well as extraction processes to purify oil and its products of impurities, specific additives are also used to react with corrosive or odiferous constituents to produce harmless and odorless substances. Such processes are generally termed sweetening processes. 

Another process that is used for treating is the solvent dewaxing process (Fig. 13.15) that accepts lubricating oil and, on occasion, deasphalted oil as the feedstock. 

In solvent dewaxing, the oil is diluted with a solvent that has a high affinity for oil, chilled to precipitate the wax, filtered to remove the wax, stripped of solvent, and dried. The solvents (principally propane, naphtha, methyl ethyl ketone-MEK) act as diluents for the high molecular weight oil fractions to reduce the viscosity of the mixture and provide sufficient liquid volume to permit pumping and filtering. Wax produced by the solvent dewaxing process is used to make (1) paraffins for candle wax, (2) microwax for cosmetics, and (3) wax for petroleum jelly. 

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In almost all heat-treating processes, steel is heated above the point and then cooled at a rate that results in the microstmcture that gives the desired properties (34,37). Process annealing and stress-reheving are exceptions. 

Other gas-treating processes involving sulfolane are (/) hydrogen selenide removal from gasification of coal, shale, or tar sands (qv) (108) (2) olefin removal from alkanes (109) (J) nitrogen, helium, and argon removal from natural gas (110) (4) atmospheric CO2 removal in nuclear submarines (5) ammonia and H2S removal from waste streams (6) H2S, HCl, N2O, and CO2 removal from various streams (111—120) and (7) H2S and SO2 removal from... 

Gas turbine fuels can contain natural surfactants if the cmde fraction is high in organic acids, eg, naphthenic (cycloparaffinic) acids of 200—400 mol wt. These acids readily form salts that are water-soluble and surface-active. Older treating processes for sulfur removal can leave sulfonate residues which are even more powerful surfactants. Refineries have installed processes for surfactant removal. Clay beds to adsorb these trace materials are widely used, and salt towers to reduce water levels also remove water-soluble surfactants. In the field, clay filters designed as cartridges mounted in vertical vessels are also used extensively to remove surfactants picked up in fuel pipelines, in contaminated tankers, or in barges. 

This was an industrial process for chloroform, but there are no plants currendy using this technology. This reaction is possibly an important source of chloroform in the water treating process. 

A bleed from the scmbbing system is sent to a sour slurry stripper. The water is then clarified and can be recycled to minimize the volume of effluent to be biotreated and discharged or evaporated. The acid gas from the acid gas removal system and from the sour slurry stripper is fed to a Claus plant, where salable elemental sulfur (qv) is produced. For maximum sulfur recovery and minimal sulfur emissions, the Shell Claus off-gas treating process (SCOT) is used. 

Shared equipment Design to avoid or minimize use of (e.g. auxiliary process- common equipment for incompatible ing scrubbers ). Pos- materials sihility of incompatible, Implement proper cleaning procedure materials coming between incompatible uses to prevent together. cross contamination Prescrub or treat process streams before transfer to common equipment API RP 750 CCPS G-11 CCPS G-22 Kletz 1991 Lees 1996 NFPA-91... 

There are so many gas treating processes that one hardly knows where to begin. That makes selection of a process for a given situation difficult. Economics will ultimately decide, but some initial rough screening is required to eliminate inordinate study. I have attempted to condense the mass of information in the literature into some brief, user-friendly guidelines for the rough cut. 

Low acid gas partial pressures (product of system pressure and concentration of acid gases—HiS and CO2 in the feed) of roughly 50psi and below. Another way of looking at selection based upon acid gas concentration is Figure 1 in the previous section entitled Gas Treating Processes. 

It is difficult to remove H2S to pipeline quality with a membrane sy stem. Membrane systems have effectively been used as a first step to remove the CO2 and most of the H2S. An iron sponge or other H2S treating process is then used to remove the remainder of the H2S. 

Each of the previous treating processes has advantages relative to the others for certain applications therefore, in selection of the appropriate process, the following facts should be considered ... 

It is important to note tlmt tlic deposition rate is a strong function of particle dimneter tluough the term v, wliich appears twice in tlic deposition flux equation. Equation (9.7.10) must be modified to treat process gas streams discliarging particles of a given size distribution. The suggested procedure is somewhat simihu to tlial for calculating overall collection efficiencies for particulate control equipment (12). For this condition, the overall rale is given by... 

Chen [133] highlights the long-term growth of the technically popular use of bubble cap trays, valve and sieve trays, followed by the increased popularity of packed columns accompanied by the development of random and structured packings. There are some applications in chemical/ petrochemical/petroleum/gas treating processes where one type of contacting device performs better and is more economical than others. Chen [133] points out ... 

E. B. Nelson. Well treating process and composition. Patent CA 1216742, 1987. 

Pump-and-Treat Processes for Groundwater Decontamination 18.8.3.1 AirStripping... 

S.A. Newman, Acid and Sour Gas Treating Processes , Gulf, Houston, 1985, Ch. 20. 

Kvaerner John Brown developed the Super Treat process addressing the H2S inhibition on HDS and favoring the desulfurization on refractory compounds [92], To begin with, they realized that more than 90% of the total produced H2S takes place in the first reaction stage, from the HDS of the most reactive S-compounds. Kvaerner technology... 

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