Petroleum visbreaking

Visbreaking A thermal cracking process which reduces the viscosity of the residues from petroleum distillation, so that they may be handled at lower temperatures. It is essentially a high-temperature, noncatalytic pyrolytic process conducted in the presence of steam. See also HSC. 

Visbreaking is a mild thermal pyrolysis of heavy petroleum fractions whose object is to reduce fuel production in a refinery and to make some gasoline. 

In cokers and visbreakers, heavy feedstocks are converted to petroleum coke, oil, light hydrocarbons (benzene, naphtha, liquefied petroleum gas), and gas (Chapter 7). Depending on the process, hydrogen is present in a wide range of concentrations. Since petroleum coking processes need gas for heating purposes,... 

Thermal cracking processes are commonly used to convert petroleum residua into distillable liquid products examples of thermal cracking processes currently in use are visbreaking and coking delayed coking. 

A considerable number of tests are available to estimate the sulfur in petroleum or to study its effect on various products, particularly hydrogen suthde (ASTM D-5705, ASTM D-6021), that can result as a product of thermal processes, such as visbreaking. Hydrogen sulhde dissolved in petroleum is normally determined by absorption of the hydrogen sulhde in a suitable solution that is subsequently analyzed chemically (Doctor method) (ASTM D-4952, IP 30) or by the formation of cadmium sulfate (IP 103). 

In crude oil refining, the visbreaker process, the delayed coking process (see Chapter 13.1.2) and thermal cracking are used in the middle-temperature range to convert heavy petroleum residues into lighter gasoline fractions and middle distillates. The aromaticity of the fractions recovered, however, is relatively low. 

DelBianco, A. Garuti, G. Pirovano, C. Russo, R. Thermal cracking of petroleum residues. 3. Technical and economical aspects of hydrogen donor visbreaking, Fuel, 1995, 74, 756-760. 

To feed the reactor, the plastics waste has previously undergone visbreaking alone or in the mixture with heavy petroleum derived vacuum residues [390-392]. 

As in the case of other important reactions occurring in the conversion of petroleum fractions, e.g., catalytic cracking and hydrocracking, in the case of visbreaking lumping approach has been widely used for modeling reaction kinetics. Lnmped kinetics is used due to the complexity of visbreaking feed and prodnct, which makes... 

Mittal, S., Maiti, R.N., Lahiri, R.N., Ram Babu, D. 1999. Modelling and simulation of visbreaker. In Proceedings of Third International Petroleum Corference and Exploration, PETROTECH-99, New Delhi, India, p. 349. 

Negin, K.M., Van Tine, RM. 2004. FW/UOP visbreaking process. In Handbook of Petroleum Refining Processes, McGraw HUl, New York, Chapter 12.3. 

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