Hexion turns waste into energy saving technology

Casestudytile MomentiveChemicals 001 SL B 201508 Open

Cutting your fuel bill by 90% is no mean feat. Resin manufacturer Hexion (formerly Momentive Specialty Chemicals) explains how it did just that at its Christchurch plant.

Hexion turns waste into energy saving technology [pdf 106 KB]

Overview

Every day for many years, Hexion burned hydrogen as a gas by-product at its Hornby plant in Christchurch, while at the same time paying good coin for relatively dirty light fuel oil to power its operations.

The company knew there was an opportunity to use the hydrogen itself as fuel – it commonly did that overseas – but despite trying over the years it could not get the investment numbers to stack up to convert the plant.

Logically, such a project made a lot of sense: there were large cost savings to be enjoyed if Hexion could make the numbers work and hydrogen was a clean, sustainable fuel. When you burn it, the by-product is water.

The process

Hexion is a global manufacturer or wood panels, resins, industrial resins, coatings and epoxies with four sites in Australia and New Zealand plus a joint-venture site in Western Australia.

In addition to a plant and its local head office in Tauranga, the Hornby facility helped Hexion service demand from the local wood panels industry and from manufacturers of fibreglass insulation.

The process Hexion employs requires it to convert methanol into formaldehyde. Most of its plants use silver as a catalyst in a process that creates significant quantities of hydrogen gas by-product.

Seizing the opportunity

Hydrogen is highly combustible and therefore makes great, renewable fuel used to create steam or electricity at most of Hexion’s global installations.

However, the New Zealand plants were originally built in the 1970s. Converting them to use hydrogen as fuel required significant investment.

“It was an opportunity that had existed for quite some time but the economics have never stacked up,” said project manager David Early. With rising fuel costs that had changed by 2012.

“A few years back the case for it became quite good economically. We put a proposal to the business and they supported us making the investment.”

Expertise needed

The company knew how to integrate a boiler into its process, Early said. What it didn’t know was the best way to set the boiler up. The combustion designs available were old and not necessarily the best way to do the job.

“You need a bit of expertise to make that happen,” Early said.

After a competitive tender, Hexion looked to Brendon Stephenson and his team at Palmerston North-based Energy Plant Solutions to develop an efficient system to manufacture steam from the waste gas.

That included designing, manufacturing, supplying and installing the boiler and control system and some of the associated pipework.

Challenges overcome

The conversion, however, presented two major challenges. First, the waste gas was already being flared and that would continue to some degree to help control environmental emissions. Therefore, two burning heads – the flare and the boiler – had to be integrated to deliver the right amount of energy to each.

Secondly, the waste gas itself was slightly different, containing lower levels of hydrogen than seen elsewhere.

A control system was built to vary the gas flow between the two burners, solving the first issue. It was not particularly complicated, Early said, but because no one in the business had done it before was still quite an achievement.

Energy Plant Solutions also came up trumps building several iterations of the boiler burner head to manage the lower hydrogen content with maximum efficiency.

“They put their heart and soul into delivering that,” Early said. “It works really well.”

Ahead of plan

Because the projected savings would go straight to Hexion’s bottom line as profit, there was pressure to deliver. A Six Sigma expert was assigned to the project to ensure that happened and there was no wastage.

Scheduled delivery was for the end of June, but the new boiler was lit-up well ahead of time on 6 May, delivering an extra eight weeks of cost reductions.

Overnight the project eliminated more than 90% of the plant’s demand for light fuel oil, something Early said made local agency Environment Canterbury very happy.

“It was not the sort of stuff you would consider clean burning fuel,” he said.

As well as reducing atmospheric sulphur, burning hydrogen waste-gas delivered a huge reduction in C02 emissions.

Success delivered

An overnight reduction in fixed costs meant the investment began paying itself back straight away.

“Commercially and economically it made so much sense to do it and the business is absolutely rapt it went so well,” Early said.

There are further benefits to be reaped. Early thinks the boiler’s efficiency can still be improved, perhaps taking fuel savings up to 95%

“That extra 5% is harder to get, but we are still aiming for it,” he said.

Hexion and Energy Plant Solutions won the Large Business Category and were named co-winner of the Innovation category at the 2014 EECA Awards.

Company profile

Hexion Inc. (Hexion), formlery known as Momentive Specialty Chemicals, is the global leader in thermoset resins. Hexion is a global manufacturer operating approximately 60 industrial facilities around the world, including a branch in Hornby, Christchurch.

Hexion won the Large Business category and were named co-winner of the Innovation category at the 2014 EECA Awards.

Key benefits

  • A more than 90% reduction in fuel oil costs has boosted
  • 1300 tonnes of C02 emissions eliminated.
  • PM10 particulate emissions cut by 93% and sulphur discharge by 99%

Key features

Design, manufacture and retrofitting of a boiler and burning head to allow waste gas to be used to generate steam energy.

Development of control systems to share waste gas fuel between the boiler system and the waste gas burner.