Acid tars are toxic liquid or semi-liquid residues of mixed chemical composition: unsaturated hydrocarbons, sulfuric acid, water and some other components. This sludge arises from the refining of oils by the concentrated sulfuric acids. The waste materials were mostly stored in open acid tar lagoons that caused a serious pollution problem to the subsoil and ground water, posed potentially great risk to humans and environment. Million tons of acid sludge are deposited in lagoons on-site at the point of manufacture, or in voids or on wasteland close to the point of production worldwide.
Acid sludge neutralization (processing) is a complex practice
The main waste management challenges faced by the petrochemical companies and service companies:
- Acid tars have a very variable composition between sites and even within one lagoon. The amount of sulfuric acid contained in acid tar may reach up to 70%, which leads to rapid corrosion of processing equipment. Special corrosion resistant materials are expensive and thus economic benefit from traditional processing is completely lost.
Acid sludge processing at the pyrolysis plant UTD-2 includes waste neutralizing at an early stage, so the corrosion of the equipment is completely eliminated.
- The high content of sulfuric acid make it difficult to obtain a conditioned product. For example, the newly formed acid tars in small quantities can be mixed with other petroleum products, affecting their quality in the normal range, and the acid sludge from sludge tanks completely unsuitable for such use.
UTD-2 plant is capable to obtain a high-quality product from the raw material of any composition, including sulfuric acid content.
- The most common acid tar treatment technology, high-temperature incineration with sulfur dioxide conversion into sulfuric acid, is underperforming due to the low cost of sulfuric acid and loss of valuable energy hydrocarbon component.
UTD-2 plant is designed to extract hydrocarbon component from acid sludge in the form of commercial-grade fuel oil.
- Acid tar lagoons can be used for waste storage not more than 10 years. That period had passed almost everywhere, sulfur-containing wastes seep into the ground, causing irreparable damage to soils and ecology of the region.
Pyrolysis plant UTD-2 is capable to resolve the acid tar lagoons challenge once for all.
- Petrochemical companies are afraid to invest in new acid tars processing technologies and store them in lagoons on-site at the point of manufacture, which leads to a huge, often irreparable damage to the environment and the huge environmental fines.
UTD-2-200 plant carried out several trial tests of processing acid tars, including the order of PJSC Gazprom – Lubricants and European company EKO OSTA. Considering the composition of waste the sulfuric acid amount were not more than 25%, the results of the pyrolysis of acid tars were positive. Laboratory studies have shown that the processed products: dry residue, synthetic gas and pyrolysis oil, conform to international standards and can be used for other purposes.