BECHTEL BHTS: Sustainability through improvement of WWT technology

Martin A. Taylor is a Sulfur Technologist for Bechtel Hydrocarbon Technology Solutions, Inc. (BHTS) based in Houston, TX, USA. His experience includes design, troubleshooting, consulting, commissioning, and start-up of Sulphur-related units. Martin has patents and patents pending for technologies in and around the Sulphur industry. He recently participated in ASIA-TECH 2016: Asia Downstream Technology Forum held in Bangkok from 11 to 12 October 2016.

You were among our respected speakers at the ASIA-TECH 2016 which has been recently held in Bangkok. What were the main issues you addressed in your presentation at the event?

At the recent ASIA-TECH 2016, I discussed latest improvements in the Waste Water Treatment (WWT) technology that have resulted in 4 patents pending, addressing capex, opex and ammonia product quality.

Could you outline the main features of WWT technology?

WWT is the original two-tower Sour Water Stripping (SWS) technology invented by Chevron in the 1960’s and now licensed by BHTS.  It allows recovery of salable ammonia from refinery or gasifier sour water, while simultaneously expanding the Claus sulfur recovery unit.  It does this at a fraction of the capex required for a new Sulphur Recovery Unit (SRU) train and does not require an air permit.

In your presentation you are advising to take the Sour Water Stripper Acid Gas Stream (SWSAG) as the starting point rather than the sour water. What is the advantage of this?

Starting with the SWSAG results in a more concentrated sour water feed to the WWT unit, which in turn reduces capital and operational expenditures.

According to your presentation, WWT does not require new air permit. Could you elaborate on this? Does this mean it is more eco-friendly?

The air permit question and eco-friendly question have the

same explanation, and the answer is yes.  When burnt in the Claus SRU, the resulting combustion products (nitrogen and water) continue to float through the system through the various reactors, condensers, and reheaters. The water is condensed in the Quench Tower (aka Contact Condenser) in a reduction-amine type Tail Gas Treating Unit (TGTU), and the nitrogen continues to the Thermal Oxidizer (aka Incinerator).  There, the nitrogen must be heated with the other processes gases to ~650-815 C by using fuel gas or natural gas.  All such burners generate a degree of CO and NOx as byproducts, so removing ammonia from the SRU feed makes WWT an eco-friendly technology, as does recovering a popular fertilizer (ammonia).  If ammonia is recovered as anhydrous or aqueous ammonia, nothing is incinerated, so NOx and CO emissions are reduced.

Alternately, a new SRU would result in more fuel gas firing in the Incinerator, resulting in more CO and NOx.  Thus, the need for a new air permit.

How does Bechtel / BHTS contribute to the sustainable development of our industry?

We approach sustainability holistically. It is not any single activity but rather the totality of our efforts to execute projects with excellence. By improving the sustainability in the equipment, materials, and services we procure, we are improving the quality of our projects while at the same time helping to protect people and the environment, promote economic development, and partner with communities and society.

We also require our suppliers and contractors to comply with all applicable national legislation, export-import rules, regulatory requirements, and project-specific sustainability requirements established by our customers.