Steinmüller Africa has developed a header-type high-pressure (HP) feedwater heater designed and manufactured entirely in South Africa. The company says it is the first unit of its kind to be developed and produced locally through its own engineering and manufacturing operations.
The heater uses steam extracted from the turbine to preheat boiler feedwater before it enters the boiler. This reduces the additional heat required to bring the feedwater to operating temperature, improving thermal efficiency.
“The HP Heaters will improve power plant efficiency by using extraction steam from the turbine to heat boiler feedwater before it enters the boiler,” says Moso Bolofo, Executive Director at Steinmüller Africa.
The project took six years from concept to delivery and involved 3D modelling, computational fluid dynamics (CFD) analysis and fabrication at the company’s Pretoria workshop.
A key development was introducing friction welding to join nipples to the heater header. The company initially used submerged arc welding but found that the process did not consistently meet the component’s manufacturing requirements.
Engineers subsequently qualified and introduced friction welding, which Steinmüller Africa says improved weld quality, consistency and production output.
The workshop also introduced Kanban-based production processes and refined its welding and assembly methods. According to the company, these developments have established a repeatable manufacturing process suitable for serial production.
By increasing boiler feedwater temperature, HP heaters can reduce the heat input required from the boiler. Depending on operating conditions, this can contribute to lower fuel consumption, reduced thermal stress on boiler components and reduced demands on coal- and ash-handling systems.
Steinmüller Africa also identifies potential benefits for flue-gas volumes, erosion and boiler tube reliability. The company has not provided quantified operating results for the newly delivered unit.
“This project demonstrates the value of integrated planning, cross-functional collaboration, continuous innovation, and disciplined safety and quality management in delivering a technically complex engineering solution,” says Bolofo.
The delivery demonstrates local manufacturing capability in specialised power-generation equipment and establishes a production process that Steinmüller Africa says can be used for future HP heater orders.
