The calcination process involves placing raw "green" petroleum coke into rotary kilns to heat it. This removes volatile material, purifies the coke for further processing, and provides energy for the aluminum industry.
Calcined petcoke is low in ash and is preferred by brick and glass manufacturers. It is also used to manufacture fertilizers.
The high carbon content of calcined petroleum coke makes it a versatile fuel source that can be used in many industrial applications. In addition, calcined petcoke has low ash content and is less polluting than coal. This makes it an attractive option for industries looking to reduce their energy costs and environmental impact.
The process of refining crude oil into gasoline, diesel, and jet fuel produces a number of heavy fractions that are further refined into petroleum coke. The process of producing petroleum coke involves heating the hydrocarbon molecules to high temperatures in a coking unit.
The resulting coke is usually fuel grade, although it can be produced as anode grade for Hall-Heroult aluminum smelting. The quality of GPC depends on the refinery’s crude oil blend, with delayed cokers running on heavier crude oils producing more resid and lower quality GPC. Independent or merchant calciners typically blend different qualities of GPC together to produce calcined petcoke that meets anode specifications for sulfur and trace metals.
The low ash content of calcined petroleum coke makes it useful as an alternative fuel for coal-fired power plants. It has a gross calorific value of about 8000 kcal/kg.
When burned, it emits less sulfur and volatile compounds than coal. The combustion of petcoke can also help to reduce greenhouse gas emissions.
Crushed and screened calcined petroleum coke mixed with a binder is used to make low ash, low phosphorus alternate fuel that can substitute scarce high ash byproduct coke in shaft furnaces and cupolas in the production of metals such as iron and steel. The mix is pre-soaked with 5-10% water, kneaded in the presence of steam, briquetted and cured in a controlled oxidizing atmosphere. This process is more economical than using byproduct coke as fuel. The slurry is also suitable for cofiring with heavy oil. This combination is also used in carbon products such as graphite electrodes and carbon brushes. It is also used as a raw material in the manufacture of activated carbon, which has many uses including water treatment and air purification.
The high heat capacity of calcined petroleum coke makes it an ideal material for carbon anodes in the Hall-Heroult aluminum smelting process. It also has a low impurity level and is readily available at relatively low cost. This combination of characteristics has led the industry to develop a variety of calcining technologies and to utilize a mixture of shaft and rotary cokes in the Hall-Heroult plant.
Sponge coke has a wide range of domain sizes with open porosity and a mixed optical texture sometimes called a granular texture. Shot coke has a spherical particle shape and dense, isotropic texture. Both are widely used for anode production and have a lower CTE than bauxite or natural graphite.
Many rotary kilns are configured to have waste heat energy recovery systems that capture the hot flue gas that exits the kiln countercurrent to the coke bed and is passed through a pyroscrubber and into a steam recovery system that produces electricity with a turbine generator. These systems have become nearly mandatory for new calcining plants to improve project economics.
The low sulfur content of calcined petroleum coke makes it suitable for use as an industrial fuel. It also has a high fixed carbon content, which makes it an excellent material for use in the production of carbon products, such as graphite electrodes and carbon brushes, and as a raw material for chemicals like carbon black, which is used to make inks, plastics, sunscreens, and other colored pigments.
The petroleum coke produced by the delayed coking unit in an oil refinery can be either fuel or anode grade. If the coke has a low metal content, it is used for anode baking in aluminium and steel smelters. Otherwise, it is used as fuel coke in the furnaces.
The sizing of the petroleum coke and its calcination in a rotary kiln are critical to the quality of the final product. The sizing process ensures that the petcoke is fed at the correct rate into the kiln and that the temperature of the calcination is consistent.
English
Write a Message