HZI’s Energetic Innovation

With the construction of Hitachi Zosen Inova’s first Australian waste to energy plant, Waste Management Review explores the role of innovation in the budding sector.

When the first iPhone was released in 2007, it started an innovation race in the smart phone industry to create multifunctional products.

Since then, 18 models of iPhone have been released, each with new features to allow Apple to continue playing a role as a market leader in the industry.

Waste to energy (WtE) companies like Hitachi Zosen Inova (HZI) also engage in the cycle of innovation, and are constantly researching, upgrading and retrofitting new technologies to keep their competitive edge.

Dr. Marc Stammbach, Managing Director at Hitachi Zosen Inova Australia (HZIA), says that because of the costs involved in building and running a plant over its long lifespan, it is important to find innovations that boost their efficiencies even by a small percentage.

“While one or two per cent may not sound like much, it adds up to tens of thousands of extra tonnes of waste processed per year,” Marc says.

“If we were to compare this with Formula 1, a vehicle which has an engine that is two per cent more powerful can mean the difference between first and second place.”

Once an innovation has been designed, built and tested at scale in a plant, it’s rolled out to early adopters and later becomes a standard offering for all future plants.

An example of this is HZI’s Low Excess Air Combustion Process (LEAP), which was first introduced at an industrial scale in Switzerland in 2015 at the Renergia Perlen facility.

A typical LEAP setup contains two phases, the mixed and partial combustion and the full combustion stage.

In the first stage, the primary gas from the grate is mixed and partially combusted with recirculated flue gas (RFG).

This gas contains no residual oxygen but is rich in carbon dioxide, hydrocarbons, hydrogen and nitrous oxides.

On the bottom ash discharge side, secondary air is used and mixed with the partially combusted RFG. This second stage oxidises the homogenised gas from stage one and helps increase the electricity production by 2.6 per cent and reduce the amount of ammonium hydroxide needed for the removal of nitrous oxide by 30 per cent.

This process increases the plant’s energy efficiency, as less thermal energy is lost in the process while also reducing the amount of nitrous oxides that are emitted.

HZI estimates that based on 50 per megawatt hour and 0.2 per kilogram of ammonium hydroxide, a plant with LEAP would save 215,000 (AUD 341,000) per line annually.

Marc says that low excess air combustion is used in combustion processes in all sorts of formats, whether it’s a jet engine or a family car, but for plants which cost millions of dollars, the implementation of the new technology must be done correctly.

“If you can increase the energy output of a facility by even a couple of per cent, that’s of great interest to us and our clients,” he says.

“Once we have proven the system, we introduce it quickly across our new plant offerings, as it gives us a major cost advantage and lower operational costs.

“Because of the increased efficiency of the system, plants can operate longer, which allows more waste to be burnt and ensures a facility’s profitability,” he adds.

The LEAP technology will be rolled out in HZIA’s upcoming WtE facility set to be built in East Rockingham in Western Australia.

The plant will aim to convert around 300,000 tonnes of residual waste per year into baseload energy, producing 29 megawatts of electricity at full capacity, which is enough to power 36,000 homes. The Rockingham Resource Recovery Facility is the first project of its kind for HZI in Australia and will divert 96 per cent of the Eastern Metropolitan Regional Council’s waste from landfill.

TREASURE FROM TRASH

Marc explains that HZI strongly believes in source separation of recyclables, organics and extracting the value from residual waste in Australia by turning it into energy instead of burying it in a landfill.

To harness the remaining valuable resources in the residual waste stream, the company has developed a patented recycling process which can extract valuable metals and minerals from the bottom ash. This method takes advantage of the increasing amount of electronic waste in feedstock.

Two of the methods that HZI have implemented are HZI Grate for Riddlings and HZI DryMining, both of which focus on the fine fractions smaller than 10 millimetres that are conventionally difficult to extract. There is value in this fraction as around 70 per cent of metals such as gold, aluminium, copper and zinc are found as fine fragments in the bottom ash.

The HZI Grate for Riddlings process separates the fine fractions directly from the grate and gives the smaller valuable particles access to fall through narrow gaps where they are sorted and removed.

HZI DryMining uses an automated treatment tower for the dry fine bottom ash, which can be managed directly from the control room.

The towers can process 10 tonnes per hour, with ferrous metals being separated before non-ferrous metals are sieved and sorted by density.

Marc says he is excited for the future of the waste industry and is eager to see how HZI’s innovations will contribute to it.

“It’s also exciting to see the interest in WtE increasing, especially as awareness around landfill issues grows.”