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Energas successfully completes turnkey gas power plant project

Leveraging its vast experience in turnkey gas power plant projects, Energas recently prevailed against an array of challenges to deliver a complex and time-constrained project within acceptable time and budget.   

As more industrial operations increasingly look to alternative energy supply to curb the impact of incessant nationwide load shedding, Energas has in recent years seen increased demand for natural gas projects for own power generation.

The company has recently delivered a large project of this nature. In fact, the project consisted of two sub-projects owned by two different organisations. 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.  

The boiler and engine upgrade project commenced in September 2020, following the order of long lead time equipment such as gas engines and boilers. The gas supply project – which was due to start at the same time – only commenced some 10 months later in July 2021.

Project acceleration was key to catching up on lost time, which saw the HPCMS project being completed in January 2022. The boiler and engine project – which could only be commissioned after the gas supply installation – was commissioned a month later in February 2022.

“In the end, the gas supply project was delayed by two months due to the National Energy Regulator of South Africa (NERSA) and Council approvals, but overall, the project was still within an acceptable delivery timeframe and budget,” says Laetitia Jansen van Vuuren, product manager at Energas.

Scope of projects

With the high-pressure Sasol gas pipeline running close to Reckitt’s boundary fence, it was considered cost-effective to convert the coal fired steam boilers to piped gas and generate electricity with gas gensets. The scope of the project included a tie-in to the existing pipeline, installation of an underground pipeline to Reckitt and the HPCMS connection. 

Energas designed and supplied skid-mounted HPCMS stations. It 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 solutions offer many benefits for the client.   It reduces field construction time and overall project schedule. We also conduct a complete factory test before shipment, thus reducing risk. In addition, the skids are  easy to install in remote areas, and customers have peace of mind thanks to single source accountability.”

The turnkey boiler and engine upgrade project entailed the supply and installation of a new gas reticulation pipeline from the HPCMS to the engines; four 500-kW 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.

Talking points

There are two major talking points to the turnkey boiler and engine upgrade project. Firstly, explains Van Vuuren, it’s the heat recovery from engine exhaust gas; usually, the heat is discharged into the atmosphere, but in this instance the exhaust gas is used, thus increasing efficiency.

The exhaust heat from the engines is 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. 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 is now been replaced with a waste heat steam boiler. When more steam is required than what could be recovered, the additional steam is 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,” she explains.

Secondly, having four smaller engines (4x 500 kW) instead of a single large engine (1x 2 MW) 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, adds Van Vuuren, one or two engines can switch off while the other operates at a higher and more efficient load.

Not without challenges

Despite an array of challenges, the projects have been completed successfully, showcasing Energas’ unparalleled expertise in this field. One of the biggest challenges was the Covid-19 pandemic and the associated travel restrictions that made it difficult for the commissioning teams from R Schmitt Enertec (engines) and Viessmann (boilers) to assist with the start-up and troubleshooting. Both the teams had to resort to remote commissioning.

“By its nature, the system is complex – integration between the municipal grid, four engines, waste heat boiler and back-up boiler with only remote assistance was not straightforward. The master controller is the key component to ensure that synchronisation between the grid and engines are done automatically. The grid is backup for the engines in case of maintenance or high load steps, but if there is loadshedding the engines need to continue operating in island mode,” concludes Van Vuuren