Sulfur Technology Center

Bechtel’s Sulfur Technology Center coordinates the sulfur removal and recovery tech­nology applications in gas processing, refining, gasification, power generation, and other related industries.

Understanding and applying technology are vital aspects of the design and construction of process plants, and individual experience is an essential element for success. Maintaining a core technology team with in-depth experience provides the opportunity to apply proven design techniques, continue the development of design improvements, and keep abreast of emerging technologies developed by others.


  • Gas and liquid treating
  • Combustion system design
  • Sulfur Plant Heat exchanger design
  • Refractory system design
  • Piping layout and planning
  • Piping stress analysis
  • Control instrumentation and systems
  • Materials handling
  • Environmental permitting
  • Modularization

Featured Expertise

  • Amine & Solvent Treating
  • Claus Sulfur Recovery
  • Tail Gas Treating
  • Tail Gas Incineration
  • Sulfur solidification & handling
  • Liquid REDOX sulfur removal and recovery
  • Combustion gas SOX removal

The basic sulfur complex is made up of the following units:

  • An amine treating unit (ATU) to remove hydrogen sulfide and carbon dioxide from various gas and liquid streams using an amine solution or specialty solvent.
  • An amine regeneration unit (ARU) to regenerate the amine solution or specialty solvent.
  • A sour water stripper (SWS) to remove ammonia and hydro­gen sulfide from the sour process waters produced in the facility. Two-tower designs for ammonia recovery are also available.
  • A Claus sulfur recovery unit (SRU) to convert the hydrogen sulfide into elemental sulfur and destroy the ammonia.
  • A tail gas unit (TGU) to remove the residual sulfur compounds from the sulfur recovery unit.
  • A thermal oxidizing unit (TOU) with stack to combust any remaining sulfur compounds in the effluent gas stream to sulfur dioxide and to provide a safe discharge to the atmosphere. This system may include waste heat recovery.

Sulfur Complex Overview

The complex processes sour gas and sour water from various refinery units. The sour gas is processed in an amine unit (ARU) to produce a sweet refinery fuel gas. A solution of amine and water is used to absorb the hydrogen sulfide (H2S) and carbon dioxide (CO2). The amine unit regenerates the amine solution and produces an amine acid gas stream (AAG) for processing in the Claus sulfur recovery units. The sour water is processed in the sour water stripper (SWS) and returns stripped water to the refinery for reuse. The SWS produces a sour water stripper acid gas stream (SWSAG) that contains hydrogen sulfide (H2S) and ammonia (NH3). The sour water stripper acid gas is processed in the Claus sulfur recovery units. A two-tower arrangement is also available if ammonia recovery is desired.

The Claus sulfur recovery units (SRU) process the amine acid gas and the sour water stripper acid gas and produce liquid sulfur. The recovery for the sulfur recovery units is 95-98 wt%. Two parallel Claus units are shown. The tail gas from the sulfur recovery units is processed in a hydrogenation / amine type of tail gas treating unit (TGTU). The TGTU generates a recycle acid gas stream (TGTU-AG) back to the SRU. The overall sulfur recovery for the SRU and TGTU is a minimum of 99.9 percent.

The sulfur degassing unit (SDU) removes the residual H2S in the liquid sulfur from the SRUs, and produces a low H2S concentration liquid sulfur product for sales. The thermal oxidizing unit (TOU) processes the effluent gas from the TGTU (or the SRUs when the TGTU is down) and discharges to the atmosphere through a tall stack.