Petroleum coke is used primarily in the manufacture of carbon anodes for several metallurgical industries, especially primary aluminum production. The anode manufacturing process requires that the coke have a low volatile content. The starting material for anode production is termed green petroleum coke, a byproduct of petroleum refining. A petroleum coke calciner is a furnace used in the heat treatment of the green coke to remove the residual volatile hydrocarbons, increase the density of the coke and improve the ability of the anode to conduct electricity.
The rotary kiln process is favored in North America for its ease of operation and versatility. Typical temperatures for a rotary coke calcining kiln are between 2200°F (1200°C) and 2400°F (1315°C). Alumina-silica refractories in the 40% to 70% Al2O3 range are appropriate for these normal operating temperatures.
Petroleum coke calcining operators prefer single-layer brick linings using rotary kiln block (RKB’s). For the rotary kiln burning zone, RESCAL 70D is selected for standard service, due to its excellent durability and good thermal spalling resistance. At elevated temperatures, the burning zone refractory may exhibit alkali-related spalling. 60% Al2O3 products feature better alkali resistance, and SENECA 60 P or KRIAL 60 are based on refractory mullite raw materials and may offer better service than 70% Al2O3 class refractories in high alkali environments. The lower temperature zones of the rotary kiln can be lined with fireclay (40% Al2O3) brick refractories for reduced cost and weight benefits in comparison to 60% and 70% Al2O3 brick. PATRIOT HF is an appropriate brick brand for this service. The rotary kiln may also be equipped with air injection tuyeres, which can be lined with high alumina castable, including QUIKTURN 60 PC.
The calcined petroleum coke usually discharged into a rotary cooler. SENECA 60 P or PATRIOT rotary kiln block can be utilized for the cooler lining. In some cases where it is desirable to anchor the refractory lining to the rotary cooler shell, low-cement high alumina castables, like QUIKTURN 60 PC and R-MAX PC QT, give excellent service. R-MAX PC QT is an excellent selection for abrasion resistance in the chute that breaches the rotary kiln and the cooler.
Upstream of the rotary kiln is a large chamber that burns the volatile hydrocarbons and dust from the kiln exhaust gas. Some designs utilize suspended brick wall constructions for the lining. It is possible that high temperatures from the combustion of the volatile hydrocarbons will require elevated temperature load-bearing ability for the brick refractory. KRIAL 60 is a mullite-based, high-fired brick that can meet the load-bearing requirements for the afterburner. Other designs specify high alumina refractory castables and gunning mixes, including QUIKTURN 60 PC and QUIKTURN 60G.
Resco’s technical specialists will evaluate your process and conditions to provide customized solutions to reduce downtime and extend refractory service life.