Heavy crude, processing problems

In order to satisfy the changing pattern of product demand, significant investments in refining conversion processes will be necessary to profitably utilize the heavy oils and residua. The most efficient and economical solution to this problem will depend to a large extent on individual refinery situations. However, the most promising technologies will likely focus on the conversion of vacuum residua and extra-heavy crude oils into useful low-boiling and middle distillate products. 

The problem is that American refineries are generally equipped in a manner that makes it difficult to impossible for them to process the heavy crude, and heavy crude contains high quantities of sulfur that must be dealt with in an environmentally acceptable manner. Refining heavy crude is more complex and more costly. 

Various industrial processes have been developed to convert heavy crude oils into transport fuels [3,4], Most of those in use are based on residual cracking or on hydroprocessing over cobalt-molybdenum, nickel-molybdenum or nickel-tungsten based catalysts [3], Given the nature of the feed and the severity of the processing, it is not surprising that catalyst deactivation is a major problem. 

Desired minerals are always mixed with other rocks that must be separated. In many cases, particularly for more valuable metals, the mineral that is sought is less than 1% of the ore. This requires processing of the ore, a procedure called beneficiation, which produces relatively large amounts of finely divided by-product rock. For economic reasons, beneficiation is usually carried out at the mine site with the residues returned to the mine or left in piles at the site. As a result, water pollution problems may develop from the leaching of mine spoils. Some communities in the vicinity of lead mines have been contaminated by lead from mine residues, with particular concern over the health of exposed children. Spoils from iron mining in Minnesota have contaminated water with an asbestos-like mineral associated with the iron ore, requiring remedial action that has cost millions of dollars. Enormous piles of tar-contaminated sand are left over from the extraction by hot water of heavy crude oil from tar sands in the Canadian province of Alberta. 

The problems encountered in processing the heavy feedstocks can be directly equated to the amount of complex, higher-boiling constituents in the residual portion of the oil. Refining these feedstocks is not just a matter of applying know-how derived from refining conventional crude oils but requires knowledge of the composition of these more complex feedstocks. 

Chapters 5 and 6 of Part III of the book introduce the reader to the science of crude oil refining. An illustration of the complete process scheme that starts from crude oil all the way to final products is given. In particular, the process route of crude oil from the well to the gas station and indeed the car tank is provided. These chapters also present the techniques and technologies involved in most of the important processes used in modern petroleum refineries for processing light and heavy distillate fractions. Chapter 7 in Part III looks at ecological problems that... 

With present technology it is entirely possible to process the bulk of the crude oil into petrochemicals, and several approaches to this problem have been considered. In this study we consider the approach in which ethylene is produced by conventional steam cracking and the heavy residual petroleum fractions are converted into steam cracker charge by means of residue hydrocracking through the H-Oil process. 

The presence of emulsions in petroleum recovery operations is generally undesirable. Dehydration of the oil is demanded for various reasons. Among the foremost reasons are the high costs associated with transportation, corrosion, and heat demands, in addition to the problems caused by the presence of water/ solids in the refining of crudes or in the upgrading of heavy oils and bitumen. This chapter reviews the chemical dehydration of crudes, heavy oils, and bitumen. First, we present a brief introduction on the extraction processes and the emulsions involved, followed by an outline of the scope of this review. 

---