Hydrotreating resid processing

This section covers recent advances in the application of three-phase fluidization systems in the petroleum and chemical process industries. These areas encompass many of the important commercial applications of three-phase fluidized beds. The technology for such applications as petroleum resid processing and Fischer-Tropsch synthesis have been successfully demonstrated in plants throughout the world. Overviews and operational considerations for recent improvements in the hydrotreating of petroleum resids, applications in the hydrotreating of light gas-oil, and improvements and new applications in hydrocarbon synthesis will be discussed. 

In reality, particularly with conventional hydrotreating type processes, the driving force may be insufficient to approach equilibrium. For example, the catalyst mediating the saturation reaction may have low activity for hydrogenation and/or the residence time for the reaction may be too brief, resulting in a basestock that falls well short of the equilibrium lines defined by the process H2 pressure. Furthermore, polar compounds present in the feed may hamper the inherent saturation activity by poisoning sites that mediate hydrogenation. 

Several hydrocarbon processes are available for upgrading resid hydrotreating, Fluid Catalytic Cracking (FCC), coking etc., some more capital intensive than others. The most widely prevalent process is the FCC process. Therefore any advances in processing resid in FCC units will have wide application. This paper deals with concepts for developments in resid cracking, particularly in resid FCC development, evaluation and application. 

Crude oil contains a number of elements other than carbon and hydrogen, which produce severe environmental impacts and must be removed. [1, 2] The principal method of their removal is catalytic hydrotreating. Many of the important crude oils have sulfur contents 1-6% by weight and nitrogen up to one percent. Ttic most important metals are vanadium and nickel, which may be as high as 1000 parts per million. These elements tend to be much more concentrated in the heavier portions in the crude oil, particularly in the residuum after distillation atmospheric resid boils above 650° F and vacuum resid boils above 1020° F. The process of hydrodesulfurization (HDS) is often carried out in parallel or in series with the process of hydrodemetallation (HDM). 

A spent resid hydrotreating catalyst was regenerated on a seni-commercial scale using a proprietary process in which the Nl+V metals were first extracted and Chen the catalyst was decoked (ref. 14). The catalyst was a high surface area GoCrNo/ganuna-alumina desulfurization catalyst that had... 

Hydroconversion (variously referred to as hydrotreating and hydrocracking) is a group of refining processes in which the feedstock is heated with hydrogen under pressure. The outcome is the conversion of resids to a range of products. 

In the Schroeder process (Figure 19.19), pulverized, dry coal is hydrogenated at pressures and temperatures of approximately 500°C (930°F) and 2000 psi (13.8) in an entrained system in which the residence time of the feed coal is less than 1 min. The products are separated into light liquids (approximately 30%), heavy liquids (approximately 5%), char (5%), and gases (30%). The heavy liquids can be hydrotreated to produce further quantities of usable (light) liquids. The reaction may be accelerated by the use of ammonium molybdate (1% w/w) that has been impregnated on to the coal. 

Over the years, FCC has evolved into a very flexible process that can take a wide variety of other feedstocks, including hydrotreated gas oils, deasphalted oils, slop oils, and lube extracts. In addition, many modern FCC units are capable of the direct processing of atmospheric residue or vacuum residue, which is called residual or resid fluid catalytic cracking (RFCC). 

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