Acid tars (also referred to acid sludge) is a toxic residue produced by refining industry. It is originated due to purification of oil containing products, machines and units by concentrated sulfuric acid. Refinery acid tar is highly viscous tar-like mass with heavy hydrocarbons, sulfuric acid and water content.

The tars are accumulated in sludge pits close to major refineries. These pits are suitable only for temporary storage of hazardous industrial waste, but the storage has lasted way to long. The existence of acid pits pose a treat to the environment by soil degradation, air and water pollution. The liquidation of sludge pits becomes a major possible solution at international waste management market.

The main challenge every acid sludge treatment technology faces with is the sulfuric acid content bringing on the equipment corrosion and affecting the final product quality.

The predominant technology for acid sludge treatment at waste management market based on oxidation principal.  The raw materials are heated under the high temperatures thus converting the sulfur dioxide into sulfuric acid. Other technologies based on either sludge mixing with hydrocarbons or conversion of acid tars to road surfaces components. But most the sludge is incinerated or buried mixed with lime which damage the environment.

Since the appearance of such an important problem, the pyrolysis technology applied in Thermal Decomposition Plant manufactured by IPEC company contains the solution for acid tars treatment. The first plant was designed by the order of Gazpromneft- Lubricants LTD for its lubricant plant to convert the refinery acid sludge into pyrolysis oil.

Treatment process description

• The raw materials are fed by the hoper which is heated by the flues gases to reduce the viscosity of the sludge.
• The feedstock is mixing with neutralized reagent, ammonia water.
• Sludge enters the reactor where it is thermally decomposed under the high temperature to the pyrolysis gas and liquid fuel.
• The neutralization and purification of flue gases is scrubbed of acid components in a multi-stage flue gas cleaning system.

The pretreatment of feedstock is not required; the entire process takes place at the same production line and supervised by automatic control system.

The liquidation of sludge pits eliminate the annual billion payments of environmental fines.

The economic effect is also achieved by obtaining market grade product — liquid fuel. Output of synthetic oil is approximately 30% per ton of raw material. The pyrolysis oil can be used in boilers and generators.

The plant is capable to process a wide range of oil-contaminated waste: oil sludge, crude oil distillation bottoms, heavy oil, etc. Equipment productive capacity is up to 9000 tons per year.

The pyrolysis gas is used as a fuel alternative type to achieve the operating parameters, which leads to further operating costs reduction. The heat recovered in the process can be used for industrial premises heating.

The treatment of 100 kg of sludge will results in 30 kg of liquid fuel, 11 kg of dry residue, 3 liters of water and 38 m³ of gas. The laboratory testing shows the absence of harmful emissions and clearness of fuel. Thermal Decomposition plant provides environmental and industrial safe as well as economic benefits of acid tar treatment.

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