Hydrocracking Heavy Paraffins

In the final step, the waxy heavy paraffin is catalytically hydrogenated, isomer-ized, and hydrocracked in a single trickle-bed reactor over a proprietary catalyst to... 

K-Hexadecane was chosen as model molecule since it is relatively easy to implement and obtain as a pure body. Its reaction network non-exhaustive on Fig. 29—is representative since it includes all the elementary steps involved in the hydrocracking/hydroisomerisation of heavy paraffinic cuts. After reduction, just six kinetic parameters (two for isomerisation, four for cracking) are required to represent this type of network. 

It is evident that the above approach was followed to arrive at a high selectivity towards middle distillates, the prerequisite being a second stage which can convert the heavy wax fraction in the HPS effluent very selectively into middle distillates, the Heavy Paraffin Conversion (HPC) stage (see Fig. 2). In the HPC the waxy product of the HPS is hydro-isomerized and hydrocracked to give the maximum yield of middle distillates. 

The plant includes hydrocracking of the LTFT products over a dual functional catalyst in the Heavy Paraffins Conversion (HPC) unit. The products of the SMDS Bintulu plant include naphtha, kerosene, diesel and some fuel gas. The HPC unit is operated t5q)ically at 30-50 bar total pressure and at a temperature of about 300-350°C, actually performing four functions ... 

Distillates (petroleum), light hydrocracked. See Petroleum distillates, light hydrocracked Distillates (petroleum), solvent-refined heavy paraffinic. See Petroleum distillates, solvent-refined, heavy paraffinic Distillates (petroleum), solvent-refined light naphthenic. See Petroleum distillates, light naphthenic, solvent-refined Distillates (petroleum), solvent-refined (mild) heavy paraffinic. See Petroleum distillates, solvent-refined, heavy paraffinic Distillates (petroleum), solvent-refined (mild) light naphthenic. See Petroleum distillates, light naphthenic, solvent-refined Distillates (petroleum), sweetened middle. See Petroleum distillates, sweetened middle Distilled Lipolan. See Hydrogenated lanolin Distilled fatty acids, cottonseed oil. See Cottonseed acid... 

MECHANISTIC KINETIC MODELING OF HEAVY PARAFFIN HYDROCRACKING... 

Catalytic hydrocracking is a flexible process for the conversion of heavy, hydrogen-deficient oils into lighter and more-valuable produets. Part of its flexibility is its ability to handle a wide range of feeds, from heavy aromatics to paraffinic crudes and cycle stocks. The ability to extend this flexibility to customized product slates depends on the ability to control and manipulate the process chemistry, which is, in turn, enhanced by a rigorous representation of fte process chemistry. This motivates the present interest in a heavy paraffin hydrocracking kinetics model. 

This chapter describes the application of these tools to the development of a mechanistic kinetic model for the catalytic hydrocracking of heavy paraffins. The basic approach and overview synopsis are presented first. This is followed by a detailed description of the steps involved in model formulation, optimization, and use. 

Mechanistic Kinetic Modeling of Heavy Paraffin Hydrocracking... 

The generalized isomorphism algorithm was applied at the carbon and branch number level to reduce the complexity and explosion of modeling heavy paraffin hydrocracking. A thus-deduced Cso paraffin hydrocracking model with 306 species and 4671 reactions at the pathways level was developed from the teachings of the Cie model. 

The Heavy Paraffin Conversion process has now been developed to convert the heavy paraffins selectively into the desired middle distillates, kerosine and gas oil. It is a mild hydrocracking process using a dual functional (Shell proprietary) catalyst. 

Another application of the hydrocracking process could become important during the next decade, when the transformation of natural gas into liquid fuels is considered to be economically feasible. In a route going via the manufacture of synthesis gas and the production of heavy paraffins by Fischer-Tropsch synthesis, a hydrocracking operation could be the final step in order to produce a high quality diesel engine fuel. 

Properly speaking, steam cracking is not a refining process. A key petrochemical process, it has the purpose of producing ethylene, propylene, butadiene, butenes and aromatics (BTX) mainly from light fractions of crude oil (LPG, naphthas), but also from heavy fractions hydrotreated or not (paraffinic vacuum distillates, residue from hydrocracking HOC). 

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