Primary and Waste Oil Refineries; Asphalt Production

Envitech serves both primary refineries and waste oil re-refineries. Primary oil refineries convert crude oil into valuable petroleum products through distillation and separation processes. Waste oil re-refiners convert waste oil into base oil products and marine diesel oil (MDO). Both types of facilities can produce asphalt.

Hydrogen sulfide is found in by-product gases from refining crude oil and other industrial processes. A sulfur recovery unit (SRU) recovers sulfur from gaseous hydrogen sulfide by using a multi-step Claus process. A Tail Gas Treatment Unit (TGTU) follows the SRU to recover sulfur and return it to the SRU. An incinerator and waste heat boiler treats the TGTU off-gas oxidizing the remaining sulfur compounds to sulfur dioxide (SO2).

Sulfur containing waste gases at waste oil re-refiners are treated by thermal oxidizers or direct fired heaters to convert sulfur compounds into SO2. Envitech’s packed bed scrubber absorbs the SO2 from the treated gases before exhausting to the atmosphere. Envitech’s proprietary quencher design is used to cool and saturate the gas before the packed bed section. The quencher operates at a lower pressure drop than other available technologies which reduces the system operating cost.

Exhaust Sources:

  • Thermal Oxidizers
  • Direct Fired Heaters
  • Sulfur Recovery Units (SRU’s)


  • Acid gas: SO2