Product-to-product heat recovery

WASTEWATER, SEWAGE, effluents and sludge are useful sources of energy with the potential to heat (or in some circumstances cool) other products or materials in industrial processes. The DTR Series of double tube heat exchangers from HRS is designed to maximise direct (product-to-product) energy recovery from such low viscosity materials, allowing valuable heat to be recaptured before the effluent enters final treatment or is discharged to the environment.

Where biological water treatments are employed, it may be necessary to reduce the temperature of the effluent before treatment. For aerobic decomposition or other biological treatments, temperatures between 25 and 35 degrees C are recommended; with activity ceasing above 50 degrees C. However, the temperature of discharged cooling water is often around 40 degrees C1; while work in Switzerland suggests that domestic wastewater typically has a temperature around 20 degrees C and rarely falls below 10 degrees C.2 Capturing the effluent closer to its source can result in higher temperatures.

Making use of any available heat is good for both your pocket and the environment, reducing the energy required for heating, with a corresponding drop in greenhouse gas emissions. Discharging water which is closer to ambient temperatures is also much better for the wider environment. HRS Heat Exchangers have designed the DTR Series specifically to use low viscous products (or waste streams) as the heating (or cooling) medium. The DTR series is perfect for direct sludge to sludge heat recovery and environmental industry heat recovery.

The tube-in-tube design means that the DTR series copes well with fluids that contain particles, without the worry of blockages impeding the flow of product or heating medium. Special stainless steel corrugated tubes are used to increase heat transfer and reduce fouling, making the DTR Series more efficient than similar smooth tube heat exchanger designs.

The inner tube of the DTR Series is removable for inspection, cleaning and maintenance, meaning that both the tube and shell sides can be inspected and cleaned, while the corrugated tube technology that HRS is so well known for improves heat transfer, yet reduces potential fouling compared to standard smooth tube heat exchangers. This allows the product or waste stream to run in both the inner and tubes. It also allows for easier and faster cleaning, so overall there is less operational downtime, even with high fouling products.

For large installations, multiple units can be interconnected and mounted in a frame, and a range of options, including thermal insulation and cladding in materials including stainless steel are available.

DETAILS, PH: 09 889 6045, EMAIL: INFO@HRS- HE.COM

ARCACTIVE’S transformational battery technology – AACarbon – has been unanimously saluted by leaders in the world’s lead battery sector by winning the 2020 Sally Breidegam Miksiewicz Innovation Award from the Battery Council International (BCI).

The BCI award celebrates innovation throughout all areas of battery manufacturing, recycling and distribution process, including packaging, technology, equipment, safety, and chemistry.

Christchurch-based ArcActive has re-engineered the negative electrode of the lead battery to remove the lead grid and replace it with a non-woven carbon fibre fabric (AACarbon).

The benefit of this innovation is that it solves a decades old technical challenge (as identified by the Consortium for Battery Innovation) – how to achieve high and sustained dynamic charge acceptance (DCA) while delivering low water consumption.

Stuart McKenzie, managing director of ArcActive, says the real environmental value, however, is how the technology delivers costeffective decarbonisation by reducing fuel use.

“Many people think electric vehicles (EVs) will be a near term step change in CO2 emissions from transportation, which represents 20 percent of global CO2 emissions,” McKenzie says. “In fact, fuel efficiency improvements to traditional vehicles will make a more significant impact in the next few decades. The IEA in its World Energy Outlook forecasts 300 million EVs will avoid the consumption of 3.3 million barrels of oil a day in 2040. But it forecasts improvements in the efficiency of the non-electric car fleet will avoid the use of nine million barrels per day by 2040.

“ArcActive’s technology will double the fuel efficiency (resulting in CO2 reduction) of the hybrid system in micro hybrid vehicles (from around three percent to six percent) – which are forecast to be the mass market car for decades to come.”

McKenzie says the lead battery as we know it today was first patented in 1881 and while there has been re-engineering over the years, the same fundamental electrode design has remained unchanged.

“ArcActive’s technology transforms dynamic charge acceptance (DCA).

Our carbon fibre fabric increases a lead battery’s ability to capture large pulses of energy (DCA), while optimizing its life and preventing water loss under these highly demanding conditions.”

The ArcActive team has been working on the technology for nine years.

“It’s been a huge challenge, so to receive this recognition from our peers is really meaningful,” McKenzie says. “Global battery makers have made a huge contribution with manufacturing, technical support and market development. I would like also to thank ArcActive’s staff, New Zealand investors and Government R&D funders who have stayed with us. Persistence is paying off.”

Roger Miksad, executive vice president of BCI, said Arc Active was selected from 13 submissions for the award, which showcases innovation and advances that will continue to impact the lead battery industry.

Chairman of ArcActive Bruce Munro says the company’s technology provides a dropin replacement for existing negative electrodes as it can be manufactured in existing factories with minimal changes.

“With lead batteries representing 70 percent of global rechargeable battery production, the ability to leverage off installed production capacity is hugely attractive as battery makers are able to re-energise their product portfolio with minimal investment,” he says.

“The fact that patented IP out of Christchurch, New Zealand has solved the biggest challenge facing battery manufacturers should not be underestimated for its global impact.”

The initial application for ArcActive technology is in batteries for micro-hybrid vehicles (MHVs). A micro hybrid vehicle uses a ‘start-stop system’, where the engine turns off when the car comes to a halt and restarts automatically when the brake is released.

It also applies to brake energy recovery. Higher levels of DCA in a battery allow more of the available energy from regenerative braking to be captured. That means the battery can reliably service the vehicle’s electrical loads at the same time as greater fuel economy is achieved. In turn, CO2 emissions are reduced, helping automakers meet the increasingly tough emission standards now imposed by regulators.

AACarbon is also fully compatible with the lead battery recycling process, helping retain the unrivalled leadership of lead batteries as the most recycled product in the world.

McKenzie says the ArcActive battery DCA performance is comparable with Li-ion battery systems, but at a significantly lower cost.

“Other applications that will need this sort of high performance include batteries for supporting intermittent renewable generation. We will have a competitive offering for this market as it further develops.”

STUART MCKENZIE