4. Atmospheric and vacuum crude

DISTILLATION UNIT (AVT)

Vocabulary to be remembered:

yield - выход, отбор

fuel - топливо

lubricating oil - смазочное масло

atmospheric and vacuum crude - атмосферно-вакуумная трубчатка (АВТ)

distillation unit

two stage distillation unit - АВТ

light distillates - светлые нефтепродукты

re-run - вторичная перегонка

caustic washing - выщелачивание

processing section - технологический узел

naphtha - лигроин

blending stock - продукт для смешения

reduced crude - мазут, отбензиненная нефть

finished lubricating oil grades - товарные смазочные масла

feed / charge stock - сырье (для загрузки)

asphaltic residue - гудрон

caustic treatment outfit - узел защелачивания

investment cost - капитальные затраты

heat recovery - регенерация тепла

manpower - обслуживающий персонал

intermediate tankage - промежуточная емкость

trouble free operation - бесперебойная работа

bottom product - остаток

run - перегонять

Petroleum refineries can be designed with various processing tendencies, such as fuel production, with a yield of automotive, aviation and diesel fuels, or combination fuel and lube oil production in which lubricating oils are obtained along with fuels. Organic synthesis processes are applied in some refineries, especially in large ones.

Primary distillation of petroleum crudes is the initial step in all refineries, apart from the crude purification process. Such distillation is accomplished in atmospheric and two-stage crude distillation units. Two-stage distillation units can be applied for various crude types. The process equipment of such units is designed for handling not only ordinary but also highly sulphurous crudes. The total yield of light distillates mounts to within 50 and 53%.

The equipment set applied in the units provides for stabilization and re-run of gasoline, caustic washing of all light products, preparation of the necessary chemical solutions, etc.

The following are the main processing sections of a typical two-stage crude distillation unit:

1. Atmospheric distillation section for primary distillation of crude oil and production of gasoline, naphtha, kerosene, diesel blending stock. The bottom product is reduces crude.

2. Vacuum distillation unit where the reduced crude is subjected to further processing in order to obtain either oil distillates suitable for conversion into finished oil grades or in a wide fraction used as feed stock for catalytic cracking units. Asphaltic residue is here the bottom product.

3. Stabilization and re-run section for separation of light volatile hydrocarbons and production of finished distillates.

4. Caustic treatment outfit for light distillates.

The above combination of several processes in a single unit permits to cut down the investment cost and to achieve high economy in operating by virtue of heat recovery and utilization of heat exchange, accompanied by bringing down the operative manpower to a minimum and by considerable reduction of intermediate tankage and piping length. Up-to-date instruments and automatic control equipment are widely used in these distillation units.

It should be borne in mind that reliable and trouble-free operation of these units calls for charge stock containing not more than 50 mg of salt per litre. If the salt content exceeds this value, the crude to be handled should undergo a pre-refining purification process in special dehydrating and desalting units where it loses its salt, water and sediment before it is delivered to the two-stage distillation unit.

EXERCISES

Ex.1. Answer the questions: