Gas products and services company Africa Oxygen (Afrox) launched its new 200 t/d R200-million Pretoria West air-separation unit (ASU) last month.

The investment, which is part of a three- year R1.5-billion investment programme by Afrox and its parent company, The Linde Group, aims to boost customer-service levels and support the company’s growth strategy in South Africa and in emerging sub-Saharan African markets.

The ASU plant produces high-purity oxygen, nitrogen and argon to service the merchant and medical markets in South Africa and in neighbouring countries.

The Linde Group’s engineering division was responsible for the design, supply and building of the new ASU, importing modern technologies to the South African industry.

Owing to market changes, Afrox discontinued the supply of gaseous oxygen and nitrogen in 1999 and operated one of its two 750 t/d ASUs at its Pretoria West facility in maximum turndown mode.

Operating such large plants in turndown mode is highly energy efficient and, taking the age of the plant into account, Afrox replaced the existing technology at the plant, originally commissioned in 1987, with more modern and efficient technology, such as the new 200 t/d ASU.

The ASU is remotely controlled from a global operations facility in the UK, ensuring optimal outputs.

The project included integrating an existing nitrogen liquefier unit into the new ASU at the site and linking production from the ASU to the existing cluster storage tanks.

The cooling water system and the electrical supply and instrumentation were upgraded. Three cold boxes, an air compressor, coolers and pump skids were shipped from Germany to Durban and transported to Pretoria West by road on a flatbed.

“The main cold box is 48 m long, which made it a challenge to transport as an abnormal load and to lift into position on site. For the road transport, cargo permits were required for each district and a police escort all the way from Durban to Pretoria,” explained Afrox MD Brett Kimber.