Refinery sour crude

Since aluminum is not attacked by hydrogen sulfide (HjS) solutions, it is used widely as a material in refineries for the handling of hydrocarbons made from sour crudes. In the strongly oxidizing conditions of manufacturing hydrogen peroxide, aluminum is one of the few materials that does not undergo decomposition. 

Sour crude oil - [PETROLEUM - REFINERY PROCESSES, SURVEY] (Vol 18)... 

The process data can now be translated into refinery processing configurations. Figure 8 is a schematic diagram of a typical sour crude refinery. While we realize that there is no such thing as a typical refinery, and many American refineries are not sour crude refineries, this figure represents what we believe to be a reasonable approximation of the type of refinery that will be operating in the United States in 1990. 

Figure 8. Typical American Sour crude refinery...

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. 

Rebalancing of new and existing refinery process capacity to regard shale oil as a primary feed rather than a contaminant - analogous to shifting from a sweet crude refinery to a sour crude refinery - with a corresponding shift of product slate (consistent with overall market demand) to best exploit the different optimum product mixes from shale oil and petroleum. 

The emissions from Claus plants can be expected to present an increasingly serious potential problem in the future as petroleum refineries operate on increasingly sour crudes from the Middle East and elsewhere and as plants are built to desulfurize substitute natural gas (SNG) and liquid fuels from coal. 

The 1989 world production of sulfur in all forms is given in Table 14.1 by region and for major producing countries. Recovered sulfur accounted for 63 percent of brimstone production in 1989. Most of the recovered sulfur was derived from sour gas wells in Canada, the Soviet Union, and the United States. U.S. oil refineries recovered nearly 4 million tons of sulfur from the hydrotreating of sour crudes. Canadian tar-sands comprise the major source of other recovered sulfur production. Frasch and open pit mines in... 

Typical constituents of sour wastewater streams from crude distillation include hydrogen sulfide, ammonia, suspended solids, chlorides, mercaptans, and phenol, characterized by a high pH. Combined flows from atmospheric and vacuum distillation are about 26.0 gallons per barrel of oil, and represent one of the largest sources of wastewater in a refinery. 

Some refineries neutralize the caustic with spent sulfuric acid from other refining processes, and charge it to the sour water stripper. This removes the H2S. The bottoms from the sour water stripper go to the desalter, where the phenolics can be extracted by the crude oil. 

On a qualitative basis, the estimates of recovered sulfur from refinery operations appear to be the most secure. Except for district IV, which depends heavily on the ultimate productivity of the Overthrust Belt, estimates of sulfur production from sour natural gas also seem reliable. The heavy crude oil sulfur output estimate is reasonably firm. Oil shale, tar sands, heavy oil and in situ coal combustion will produce little sulfur even under optimistic scenarios. The smelter acid projection is weak. Metal output may... 

The recovered sulfur industry exists primarily as a result of the necessity of removing sulfur values from hydrocarbon fuels before combustion so that sulfur emissions to atmosphere are reduced. In the case of sour gas, the principal source of recovered sulfur, the product that results from recovery of the sulfur is clean-burning, non-polluting methane. In the case of refineries handling high sulfur crude the product is low sulfur gasoline and oils. Thus every ton of sulfur recovered is a ton that is not added to the atmosphere. The recovery process itself however, is also the subject of optimization and recent developments in recovery efficiency have further ensured that the environmental impact in the immediate vicinity of these desulfurization facilities will be minimized. 

Sulfttr Content. The amount of sulfur in crude is important in terms of handling the crude within the refinery and the undesirable effects of sulfur in finished products. High-sulfur crudes require special materials of construction for refinery equipment because of their corrosiveness. Certain refinery processes require desulfurization of sour charge stocks prior to use as a feedstock, not only because of their corrosiveness, but also because of the effect of sulfur-bearing compounds on expensive catalysts, From the standpoint of the consumer, sulfurous gasoline has an unforgettably offensive odor unless specially sweetened and it may corrode the fuel system and engine parts, as well as pollute the atmosphere after it has been burned,... 

For convenience, the discussion of materials for these various processes is divided into five chapters. Crude units and utilities are discussed in this chapter. FCCs, fluid cokers, delayed cokers, sour water strippers, and sulfur plants are covered in Chapter Two. Desulfurizers, reformers, hydrocrackers, and flue gas are discussed in Chapter Three. Hydrogen plants, methanol plants, ammonia plants, and gas treating are discussed in Chapter Four. Underground piping, pipelines, production equipment, and tankage associated with the refinery industry are covered in Chapter Five. Discussed throughout these chapters are many common environments and equipment (e.g., sour or foul water, distillation, etc.) that appear in the various types of refinery process plants. 

Recovery from sour natural gas and from crude oil was first developed in the USA in 1944, and by 1970 these sources exceeded the total volume of Frasch-mined sulfur for the first time, Canada (Alberta) and France are the principal producers from sour natural gas, which contains 15-20% H2S. The USA and Japan are the largest producers from petroleum refineries. The phenomenal growth of these sources is clear from the following figures (in 10 tonnes) <0,5 (1950) ... 

Selenium enters the refinery as contaminates of processed crude oils. As the refiner processes the cmde oil, the selenium contaminate migrates fi om the crude oil into the refinery s striped sour water (SSW) streams. Once in the SSW stream, the selenium contaminate, which is an environmental concern, is now part of the wastewater stream. The problem for the refiner is how to efficiently remove the selenium prior to discharging the water to an appropriate catch, such as a bay or municipal water treatment plant. 

---