Retrofitted boilers and burners provide reduced electricity consumption and improved combustion efficiency that can benefit the boiler industry, which is facing rising energy costs, says combustion control specialist Steam House Africa project engineer Lionel Naudè.

“In these times of increasing energy costs, there is demand for retrofitting burners that have mechanical linkages and on-off controls with electronic servocontrols and exhaust gas analysis, allowing for active fuel adjustments to keep combustion at an optimum.

“Depending on the installation, a 5% to 7% fuel saving is readily achievable,” he explains.

He recommends the use of UK company Energy Technology Control’s range of electric burner management systems that have been adopted by several reputable European and US burner manufacturers. Steam House Africa is the local distributor of this brand.

The company also carries out retrofits on coal-fired boilers, using the CAL programmable logic controller-based system, incorporating variable-speed drives on fans and stokers, thereby reducing electrical consumption and doing away with the older system of dampers and linkages to obtain a consistent combustion efficiency.

“Sometimes, taking one’s eye off the detail leads to deteriora- tion and acceptance of a lesser efficiency. Coal plants are a rugged environment but good efficiencies can still be achieved,” he says.

Further, Steam House Africa also carries out a survey and analysis of the combustion emissions, boiler operations and boiler plants to establish the extent of savings that can be achieved by doing things differently, Naudè says.

Installation Internationalisation is both beneficial and flawed, as there are aspects of boiler design and manufacturing that have exposed faults in the finished product, says Steam House Africa CEO Glen Fourie.

“In our opinion, in the attempt to rework standards to meet a lowest common denominator, old-fashioned quality has been sacrificed. The call is for designs that are closer to the margin than, say, the British Standards allow for,” he states.

This will result in improved cost effectiveness, as boilers can be manufactured with thinner materials and will, therefore, be cheaper. This will be an advantage when budgeting short-term.

Fourie says the workmanship of certain brands of boilers imported into South Africa does not meet the company’s expectations, but says this is an advantage to mechanical designers and contractors, as they are able to repair and replace boilers more frequently and the importers get to sell more ‘disposable’ boilers.

Nevertheless, he maintains that there are good-quality imports with reputations that are easily verifiable; however, they come at a higher price.

“The imports we are referring to are liquid- and gas-fuel boilers, since coal boilers no longer meet environmental requirements in Europe,” he says.

In a recently completed project for dairy producer Danone, in Boksburg, Steam House Africa converted the facility’s coal-fired boilers to gas-fired boilers.

The company was asked to gut the boiler house and remove all coal-fired equipment, while retaining only the steel structure.

Fourie says the final product was a new boiler house with two new 15 t gas-fired boilers, a new hotwell tank, an economiser and new pipework. Steam House Africa was involved in the design, construction and com- missioning of the plant.

Energy Considerations E

nergy savings in an indus- trial plant are possible, but, compared with Europe, South Africa has a long way to go in terms of implementing actions to conserve energy.

Fourie suggests that some of these savings can be achieved through a plant survey of steam pipe insulation, condensate recovery and the use and conditioning of steam traps.

“Other aspects may include exhaust gas heat recovery and variable-speed fan drives. In isolation, these ideas will reduce costs, but there may be synergies in coupling ideas across systems to exploit larger gains,” he says.

Steam House Africa also consults with international experts in the design of heat exchangers to verify duties and produces three-dimensional model plants to ensure that they will all fit into the available space.

The company also designs and builds turnkey plants for industrial-scale users. This covers steam plants, coal handling conveyor installations, ash handling conveyors and bespoke systems for food processing, or press heating and cooling to reduce cycle times.