As more industrial operations increasingly look to alternative energy supply to curb the impact of incessant nationwide load shedding, Energas has seen increased demand for natural gas projects for own power generation.
The company has recently delivered a large project, comprising two sub-projects. The first one was a tie-in and High Pressures Customer Metering (HPCMS) gas supply project for Sasol, and the second was a boiler and engine upgrade project for Reckitt. In both instances, Energas was the turnkey contractor.
Scope of projects
With the high-pressure Sasol gas pipeline running close to Reckitt’s boundary fence, it was considered cost-effective to use piped gas for its own power generation with gas fired boilers replacing previous coal fired boilers. The scope of the project included a tie-in to the existing pipeline, installation of an underground pipeline to Reckitt and the HPCMS.
Energas supplied a skid-mounted HPCMS station which is designed, shop-fabricated and assembled, fully-tested and packaged before being transported to site. The skid includes filtration, pressure reduction, over-pressure protection and metering. The station reduces the pressure from 35 bar (inlet line pressure) down to 1 bar (outlet pressure to the user) within one stage of pressure reduction.
The skid-mounted HPCMS solution offers many benefits for the client. It reduces field construction time and overall project schedule. A complete factory test is carried out before shipment, thus reducing risk.
The turnkey boiler and engine upgrade project entailed the supply and installation of a new gas reticulation pipeline from the HPCMS to four 500kW gas engines (gensets); a new gas-fired steam boiler; a waste-heat boiler that uses exhaust heat from the engines to produce steam; interconnecting piping; a new gas engine building and associated electrical infrastructure.
Heat Recovery
The heat from engines is usually discharged into the atmosphere, but in this instance the exhaust heat from the engines will be used in a waste heat boiler. This free steam will result in a substantial annual saving in the gas bill. Projections show that a substantial saving can be realised, compared with importing electricity from the grid in the first year of operation. The accumulated saving over 10 years, based on inflation and price assumptions, is substantially more than the project value.
“The client operated a coal fired boiler, but it will now be replaced with a waste heat steam boiler. When more steam is required than what could be recovered, the additional steam will be supplied with natural gas as fuel source. The waste heat boiler is a combination boiler; it works by recovering energy from the exhaust heat and also has a gas burner. When the waste heat boiler is being serviced or the engines are not working, there is a standby gas boiler to ensure continuous supply of steam to the plant,” explained a spokesperson.
Having four smaller engines (4x 500kW) instead of a single large engine (1x 2MW) allows continuous power supply to the plant. When one engine is serviced, the other three can still operate. Or if the plant’s usage is low, one or two engines can switch off while the other operates at a higher and more efficient load.
For further information contact: Laetitia Botha Email: laetitia@energas.co.za Web: www.energas.co.za
