Business Divisions

RefiningTransformation Process

Refining

Refining is a group of physical chemical processes by which the different components of crude oil are separated and then transformed. ENAP Refining Plants, Aconcagua, Bío Bío and Gregorio have a series of plants that participate in carrying out such process.

A Refining Plant is composed by the following units:

 

Topping (primary fractioning)

Free of water and other impurities crude enters the Refining Plant to start with the primary fractioning process, which consists in the first separation by heating at 370ºC the oil-constituent hydrocarbons, which then are separated into a distillation column called Topping. The lighter or more volatile components are separated at a lower temperature, and they come out through the upper part of the distillation column, while the heaviest products are obtained in its lower part. The products outlet order, according to their volatility, is as follows: liquefied gas, fuels, naphta, kerosene, diesel, gas oil and reduced crude.

Gas oil feeds the Catalytic Cracking and Hydrocracking units. The bottom product, or reduced crude is delivered to the vacuum plants.

The Topping and Vacuum units operate integrated to maximize the thermal exchange, thus reducing the energy and refrigeration consumption.

 

Vacuum Plants (vacuum fractioning)

Its function is to prepare a feeding load, adequate for the Catalytic Cracking and Hydrocracking units, by fractioning the vacuum reduced crude to avoid these products cokification.

The reduced crude originated by the Topping plants is fractioned into gas oil and pitch at low pressure distillation columns. The gas oil is sent to later transformation processes at Catalytic Cracking and Hydrocracking plants. Part of the pitch is sent to the Visbreaker or Viscoreduction plants to obtain fuel oil, and another part of the pitch is sent to the Delayed Coking plants, where it is transformed into diesel and fuel, and the rest corresponds to asphaltic pitch, which is used in the preparation of asphalts used for paving roads and highways.

 

Ethylene Plant (Bío Bío Refining Plant)

Part of the naphta coming from Topping is processed at this plant to produce light gas, liquefied gas, ethylene, propylene and high octane fuel. Ethylene is sent through a gas pipeline to the Petrodow plant, where it is converted into low density poyethylene. The fuel produced at this unit is used in the preparation of 93 and 97 octane special fuel. Propylene is sent to Petroquim plant.

 

Catalytic Reforming

97 octane fuel, liquefied gas and light gas are produced at this plant from naptha originated at the Topping columns. This unit is one of the main hydrogen originators, an element that is used as raw material in the process to obtain products with low sulfur content.

 

Light elements and treatment Recovery Plant.

It is designed to recover propane and butane from different sections of the Refining plant.  The products of this plant are cracking stabilized fuel, propane, butane and refining gas burnt in the furnaces.

 

Alkylation Plant (Aconcagua Refining Plant)

In oil technique, alkylation is the chemical combination between an isoparaffin (isobutane) and an olefin (butylene) to form isomer hydrocarbons (isooctane) which distillate at a fuel range that, given its high octane, is used to prepare aviation fuel.

 

Acid Plant (Aconcagua Refining Plant)

A unit which function is to regenerate the sulfuric acid catalyst (H2S04) used in the Alkylation Plant processing, so that it can be re-utilized.

 

Diesel Production Unit

This unit consists in a vacuum gas oil moderate hydrocracking plant, an intermediate product of the refining process, to obtain diesel with a sulfur low content.  The most important equipment of the unit is the reactor, where the gas oil load, previously heated at a high temperature and in the presence of a catalyst, experiences a combination of cracking and hydrogenation reactions. The reaction products are separated in a fractioning tower, cooled down and sent to storage tanks as low sulfur diesel.

 

Sulfur Recovery Unit

The Sulfur Recovery Unit operates based on the so-called "Claus Reaction", by which a mixture of a given percentage of sulfurous gases thermally reacts at 1300ºC, and catalytically at a lower temperature to originate gaseous sulfur, which liquefies when cooling down in two boilers that generate steam with the recovered energy to be used in Refining.

The product obtained, with a great purity, is loaded liquid at 130ºC by means of an arm installed at a special loading island, into tank trucks to be transported to the facilities of the commercialization companies.

 

Isomerization Unit

This unit increases the octane of the topping fuels, to increase the production of high octane fuels.

 

Hydrocracking

The gas oil originated by all units may also be sent to the hydrocracking unit, which generates: gases (Fuel Gas), hydrocracking naphta, high quality and very low sulfur diesel, and a non converted gas oil, since conversion achieved at this unit is not complete.

This plant transforms the rest of the vacuum gas oil, mainly into diesel and, to a lesser extent, into kerosene, naphta and light gases. Such process consists in the gas oil reaction with hydrogen originated by the Hydrogen Plant. The diesel obtained with this process is of excellent quality, since it contains a very low level of sulfur. The hydrocracking process may also generate aviation kerosene.

 

Visbreaker

The pitch viscosity originated by the Vacuum Unit to generate fuel oil is reduced at this Plant. This unit also generates a small amount of light gases, fuel and diesel.

 

Catalytic Cracking

This plant receives a part of the gas oil from the vacuum columns to transform it into base fuel for the preparation of 93 octane fuel. Light gases used as fuel in the refining process, liquefied gas, propylene, diesel and some fuel oil are also obtained at this plant.

The converter, in turn, has two receptacles that may be superposed, or placed one next to the other: the reactor and the regenerator. Both equipment are interconnected and operate together.

 

Delayed Coking

The vacuum pitch may also be sent to a delayed coking plant or Coker, where it is converted into gases (Fuel Gas), Coker naphta, Coker diesel, Coker heavy gas oil and oil coke. Delayed coking is a thermal cracking process where the necessary heat for the coking reactions is delivered by a furnace. At the furnace outlet, there are two large and high chambers or drums (8-9 meters diameter per 25-30 meters high), and the products are left in one of them for a 24-hour reaction for coking. The other drum is isolated from the process, its coke load being unloaded with water cutting tools, and once it is free of coke it returns to the production line, while the other enters the same unloading or decoking process.

Naphta and Diesel Hydrodesulfurization or Hydrotreatment

At the Hydrotreatment units (HDT) naphta is treated with hydrogen to decrease the sulfur and nitrogen content of reforming supply. Similarly, diesel is treated by means of a Hydrodesulfurization unit that allows the reduction of sulfur contents in this fuel to levels lower than 50 parts per million.

Naphta and diesel produced in the Coker are treated at the HDT unit, generating low sulfur and nitrogen content naphta and diesel.

 

DIPE Plant (Aconcagua Refining Plant)

This unit allows the fulfillment of three purposes: to produce diisopropyl-ether - a compound used in the production of high quality reformulated fuel and catalytic liquefied gas -; to reduce the emission of volatile components into the environment, and to improve the fuels combustion quality.