Crude Oil and Refinery Products

It is estimated that annually some 6 million t crude oil and refinery products are introduced into the sea [6]. Of this amount, probably about 40% is crude oil (natural influences, in-shore production, tanker accidents and transportation by tanker) and about 60% are further processed petroleum fractions (refineries, rivers, town sewage, transportation means, precipitation from the atmosphere) [6]. This annual emission into the seas can, in addition to other fractions, correspond to about 75,000 t benzene, 480,000 t toluene, 560,0001 xylenes, and at least 40,0001 naphthalenes. 

Various types of non-hydrocarbon compounds occur in crude oils and refinery streams. The most important are the organic sulfur, nitrogen, and oxygen compounds. Traces of metallic compounds are also found in all crudes. The presence of these impurities is harmful and may cause problems to certain catalytic processes. Fuels having high sulfur and nitrogen levels cause pollution problems in addition to the corrosive nature of their oxidization products. 

Petroleum Stocks Primary stocks of crude oil and petroleum products held in storage at (or in) leases, refineries, natural gas processing plants, pipelines, tankfarms and bulk terminals that can store at least 50,000 barrels of petroleum products or that can receive petroleum products by tanker, barge or pipeline. 

Oil refineries and bulk storage of crude oil and petroleum products (ISBN 1 85112303 2). 

Refining companies are successfully implementing supply chain integrated solutions to solve these problems and improve refinery operation and profitability. However, these applications depend on the availability of accurate and live data. Some points of the supply chain— in particular planning and operation areas—are greatly influenced by the availability of reliable and updated crude oil libraries reflecting the information of the crude oil and the products that will be obtained in the different processes. 

Hydrogen is essential in the hydro-treatment processes used in refineries, or in complex bio-refineries, for the production of high-quality fuels with low environmental impact (e.g. desulfiirizafion and intense dearomatization) and for the eonversion of heavy crude oil and hy-products into middle distillates. The importance of H2 is also well known in petroehemistry (the synthesis of methanol, dimethyl ether, ammonia or hydrocarbons via Fischer-Tropsch). It also has potential as an energy vector for its clean fuel eharacterisfies. 

Refinery margins depend on location, size, automation, complexity, and cmde and product prices. A good indicator of margins is the crack spread - the difference in price between crude oil and refined products. 

Before proceeding, it is helpful to examine how a typical cat cracker fits into the refinery process. A petroleum refinery is composed of several processing units that convert raw crude oil into usable products such as gasoline, diesel, and jet fuel (Figure 1-4). 

The problem is to allocate optimally the crudes between the two processes, subject to the supply and demand constraints, so that profits per week are maximized. The objective function and all constraints are linear, yielding a linear programming problem (LP). To set up the LP you must (1) formulate the objective function and (2) formulate the constraints for the refinery operation. You can see from Figure El6.1 that nine variables are involved, namely, the flow rates of each of the crude oils and the four products. 

Very little information could be identified dealing with -hexane levels in sediments and soils. -Hexane has been identified among the contaminants in an offsite oilfield-disposal pit in New Mexico (Eiceman et al. 1986). Since w-hcxanc is a trace constituent of crude oil and natural gas, as well as a component of refined petroleum products, soil or sediment contamination with -hexane can be expected near oilfield production sites, large soil spills, slush pits and other areas around refineries, and in waste sites where petroleum products or other -hexane-containing wastes had been disposed. Detections would also be likely near many tank storage facilities, pipelines, truck or rail transfer sites, car repair facilities, automobile assembly or storage facilities, and auto and truck fueling facilities (DeLuchi 1993). 

Liquefied petroleum gas (LPG) was used as fuel for the first time in the USA in 1912. Under the general term natural gas liquids (NGL), 60% of global LPG originates as a fraction separated from methane during the production of oil and gas the remaining 40% are generated as a by-product from the fractionated distillation of crude oil in refineries. Liquefied petroleum gas is a mixture of propane and butane, with the mixing ratio dependent on the country and season. 

A refinery converts crude oil and other hydrocarbon feedstocks into useful products and raw materials for other industries (Figure 4.5). Refining involves the separation and blending, purifying and quality improvement of desired petroleum products. The primary products of a refinery are as follows ... 

The products derived from petroleum are produced in refineries using a fundamental separation process called distillation. The principal method for separating crude oil into useful products is through distillation. Distillation is the heating process whereby hydrocarbons, which make up the crude oil, are converted to vapor form and are... 

The source of these compounds is varied. The butanes are found naturally in crude oils and natural gas. They, plus the olefins, are products of various refinery processes and of olefins plants. They are separated by fractionation, except for butadiene and isobutylene, which are sometimes recovered by extractive distillation. They all vaporize at room temperature, so they are handled in closed, pressurized systems.. 

The petroleum industry, one of the world s largest industries, has four major branches [1]. The production branch explores for oil and brings it to the surface in oilfields. The transportation branch sends crude oil to refineries and delivers the refined products to consumers. The refining branch processes crude oil into useful products. The marketing branch sells and distributes the petroleum products to consumers. The subject of this chapter is the treatment of liquid wastes from the production and refining branches. 

Caustics are widely used in petroleum refineries. Typical uses are to neutralize and to extract acidic materials that may occur naturally in crude oil, acidic reaction products that may be produced by various chemical treating processes, and acidic materials formed during thermal and catalytic cracking such as H2S, phenolics, and organic acids. 

The objective function can assume different representation with regards to the system under study. A commonly used objective of an industrial process is to maximize profit or to minimize the overall costs. The former is adopted in this work. In this model, the whole refinery is considered to be one process, where the process uses a given petroleum crude to produce various products in order to achieve specific economic objectives. Thus, the objective of the optimization at hand is to achieve maximum profitability given the type of crude oil and the refinery facilities. No major hardware change in the current facilities is considered in this problem. The... 

The above objective represents a minimization of the annualized cost which comprises crude oil cost, refineries operating cost, refineries intermediate exchange piping cost, production system expansion cost, and export revenue. The operating cost of each process is assumed to be proportional to the process inlet flow and is expressed on a yearly basis. 

Table 3.8 shows the new strategic plan for all refineries in terms of crude oil supply combinations, production expansions, and integration network design between the refineries. In response to the increase in the diesel production requirements by more... 

---