EECA Awards honours innovative energy use

Two large regional manufacturing plants have been honoured in this year’s EECA Awards. Dominion Salt, alongside engineers Aurecon New Zealand, won the Innovation Award for an ingenious project that expanded capacity without increasing energy use at the company’s Mt Maunganui plant. And Whangarei-based Golden Bay Cement won the Renewable Energy Award for its long-term project to substitute coal with locally-sourced bioenergy. Winners in nine EECA Award categories were unveiled at a ceremony in Auckland on 23 May. Combined, the EECA Awards entrants have saved or generated energy worth more than $600m, and have saved or avoided more than 1.7m tonnes of CO2 emissions. The Supreme Award, presented by Minister of Energy and Resources Phil Heatley, went to Air New Zealand for energy-saving initiatives that have saved more than $540m in fuel costs.

Dominion Salt – Fisher & Paykel Innovation Award winner
In 2009 Dominion Salt started a major upgrade of its existing vacuum plant to increase the production of food grade and pharmaceutical grade salt. The objective was to cost-effectively increase production by at least 50 percent, or 20,000 tonnes a year, with the focus on manufacturing higher-grade pharmaceutical salt, for which export demand was growing. Before the upgrade, the plant was having to run continuously to cope with demand. The solution involved expanding an existing three-effect vacuum crystallising evaporator into a new five-effect evaporator in such a way that the existing three effects could continuously manufacture pharmaceutical salt, and the two new effects continuously manufacture food-grade salt.

Aurecon’s project involved the installation of new salt crystal evaporation plant, a crystal separation centrifuge, a salt dryer, packing equipment and other utilities including a replacement steam turbine generation set. The new facility increased plant capacity by 63 percent to 76,000 tonnes of salt a year. It has also reduced energy consumption per tonne of product by 33 percent, and improved overall plant energy efficiency by 48 percent.
This was achieved in two ways:
• By incorporating two new effects into the original three-effect salt crystallising evaporator, and using vapour from the new steam-heated first effect to heat the following effects in a multiple-effect configuration.
• By the use of higher energy waste streams, such as waste condensate, to pre-heat the incoming cool air to the new fluid bed dryer. This design modification meant the new dryer required 50 percent less steam than the existing dryer.

The expansion has given Dominion Salt a significant competitive advantage in export markets, as its production costs are lower. It has decreased CO2 emissions by more than 3,000 tonnes. It has also helped with the training of plant operators as the 3-D AutoPlant modelling that Aurecon carried out using laser scanning was used by Dominion Salt maintenance and operations staff to evaluate equipment accessibility and operation. The EECA Award judges described the Dominion Salt upgrade as “an exceptional engineering project.” “It was clever to get two products out for the price of one, without increasing energy costs. This is an example of an established industry applying innovation to existing technology, that over-delivers on productivity targets.”

Golden Bay Cement – Right House Renewable Energy Award winner
In 2004 Golden Bay Cement started substituting the coal used in its cement kiln with locally sourced wood, including demolition and construction waste. This remained at a relatively low level of around 10 percent until mid-2008, when the company completed a capital upgrade on its kiln and carreid out a process trial which highlighted the opportunity to use more even more biofuel as a substitute for coal. The plant is now running on an average of 30 percent wood energy, and has plans to boost that further to 45 percent. This is saving Golden Bay around $3m a year in energy costs, and reducing annual CO2 emissiosn by 58,000 tonnes, which also means lower ETS charges. Golden Bay Cement’s annual thermal energy usage is up to 2.8PJ – the project has made it possible to use around 0.8PJ of biofuel as part of that.

When it first examined the feasibility of biofuel substitution, Golden Bay Cement got design and supply options for a new fuel feed system from international experts that estimated the project costs at $5 million. The company then did an internal review, and with an innovative design that included using recycled material, managed to complete the project for only $1.5 million. The project also involved changing the operating characteristics of the kiln to take account of the energy required to drive off moisture and the impact of the introduced energy, on the chemistry of the final product.

Outside the wood processing industry, which is traditionally a very high bioenergy consumer, Golden Bay Cement is one of the first industries in Northland to use wood biofuel for process heat. According to international benchmarking, the company is now one of the largest users of wood energy in the global cement industry. The judges said that in its large-scale use of biomass for heat, Golden Bay Cement was showing leadership as a major industry outside of the traditional wood processing sector. “This project should be an exemplar for non-traditional users of biomass such as the dairy industry. It’s an innovative use of local resources, with reduced waste to landfill as a bonus.”

Also recognised at the Awards was SCA Hygiene Australasia, highly commended for its conversion to geothermal steam from natural gas; and Life Technologies Christchurch, commended for its heat recovery and other projects that have reduced diesel use at the site by 50 percent.

EECA Awards winners at a glance

Dominion Salt / Aurecon
• Plant capacity: 76,000 tonnes per year.
• Capital investment: $15m (upgrade was needed to meet growing demand).
• Energy savings: $500,000 per year (expected to rise to $900,000 when full capacity reached).
• CO2 avoided: 3,371 tonnes.
• Energy saved over life of the project: 17,550 MWH.

Golden Bay Cement
• Capital investment: $1.5m.
• Energy savings: $3m per year.
• CO2 savings: 210,269 tonnes.
• Bioenergy generated over life of the project: 653,333 MWH.

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