No job is too hot too handle

Longley Farm uses HRS heat exchangers to process fresh curds used in a traditional Yorkshire curd tart.

Located near the picturesque North Yorkshire village of Holmefirth, Longley Farm is best known to the Australian food industry as the parent company of Richmond Dairies in Casino, NSW.

Richmond Dairies, which is known for its fast freeze technology, produces a range of dairy ingredients for the food manufacturing industry in Australia and abroad, exporting products around the globe.

Longley Farm has been owned by the Dickinson family since 1948 when brothers Joseph and Edgar inherited their great uncle’s farm together with 10 cows.

Today the farm boasts one of the best Jersey cow herds in the United Kingdom with 300 of its own cattle, and tops up demand with milk from up to 40 trusted farmers around the country, which is used in its award-winning range of dairy products.

The farm also makes its own ice-cream, together with the traditional specialty Yorkshire curd. Longley Farm is the world’s leading commercial manufacturer of this uncooked fresh curd product, which is the key ingredient in a traditional Yorkshire curd tart.

All of Longley Farm’s products are made without the use of artificial additives, colourings, preservatives or stabilisers and are sold in local shops and some national supermarkets.

The need for heat exchangers

Like most dairies, the factory operates a number of heat exchangers to remove the heat from processing and manufacturing its dairy products, which must be chilled for sale.

Most of these are of a traditional plate design, which is fine for simple heating or cooling purposes, but recent upgrades to the machinery which produces fresh cream and Yorkshire curd have seen new corrugated tube type heat exchangers installed.

These new HRS heat exchangers incorporate corrugated tubes that provide a number of advantages over flat plate or smooth tube types.

The biggest advantage is that heat transfer is increased, particularly at higher flow rates, meaning that less heat transfer area is required and resulting in a shorter, more compact design, together with associated cost savings.

This also results in gentler handling of the product during the cooling phase, which is crucial for fresh cream production.

“For a cream process we want the cooling profile to be very gentle and we want to agitate the cream as little as possible,” Longley Farm’s Konrad Schwoch said.

Corrugated tube heat exchangers have a lower pumping requirement than other tube-type heat exchangers as their compact nature results in a lower pressure drop during the heat exchange process. This helps contribute to the long operational life and reduced maintenance of the unit, which has advantages for Longley Farm.

"For me, the value in the tube-type heat exchanger is that it is a more robust piece of equipment,“ Konrad said.

“It’s harder to break and easier and cheaper to service, saving money over the lifespan of the unit.”

Like all HRS heat exchangers, the corrugated tube units are made from high quality stainless steel.

“Because of the innovation you get from HRS, such as multi-tubes and annular spaces, you have a lot more surface area than a traditional tubular heat exchanger,” Konrad said.

“Because of this ... the actual size of the new system is smaller than the old equipment it is replacing, making it easier to incorporate into the factory layout.”

Different design needed for curds

The new heat exchanger chosen to improve Yorkshire curd production is a different design to that used for cream.

This time a corrugated tube design, which specifically increased turbulence, was chosen to help to reduce fouling inside the tubes.

While most dairies make curds and whey by adding bacteria to the milk to turn the lactose into lactic acid and stimulate the proteins to stick together, for Yorkshire curd production Longley Farm adds acid directly to the milk, which is the traditional way of making the product.

“Using this traditional method creates a problem when you want to heat or cool the solution,” Konrad said.

“The curd can be very, very small, so when you are pumping it you get curd mixed into the whey portion.

“When you want to pump it you know you are going to get particulates in it, so we need to use a corrugated tube heat exchanger because traditional plate heat exchangers can easily become blocked with the small bits of curd.”

This unit has been specifically designed by HRS to handle these particulates, even if they reach levels well in excess of those found in normal operation.

“With all our different requirements, including heating and cooling, it can be difficult to automate quite a complex group of processes and not end up with the biggest, most complicated plant in the world,” Konrad said.

“The clever thing has been keeping the heat exchanger solution simple while providing everything we need.”

The compact HRS system sits on a platform above the dairy processing area.