Advanced evaporation economics

By Kevin T. Higgins

Lower capital cost is only the start of Acqua International's cost effectiveness: greatly reduced energy use is the evaporator's true virtue.

Michael Everton, principal, Acqua America LLC, Tampa, FL

Pre-treatment of by-products and waste streams prior to sale or disposal is becoming standard operating procedure in many segments of food and beverage manufacture, none more so than dairy. However, the cost of concentrating dairy by-products for use as livestock feed can easily exceed its economic value, and that's left many plant operators searching for more efficient technologies. Yet, a New Mexico fluid milk processor may have found one-and it arrived in the 47th state by way of Australia.

The head of Select Milk’s evaporator is 20 ft. above floor level, about half the height that would be required for a conventional evaporator. Permeate arrives under pressure in the 12-in. duct on the right.

The Victoria, Australia-based Acqua International Group's origins are in applying separation technology on offshore oil rigs to recover trace amounts of crude oil from water being discharged back into the sea. Acqua's co-founder and inventor Neville Clarke's signal creation is a twin-entry, matched helical head that improves hydrocyclone efficiency. The head generates a spiraling flow pattern with the in-stream and minimizes pressure drops, contributing to efficiencies in both energy consumption and space utilization. Since incorporating in 2001 as Acqua International Group, Clarke and his colleague, Michael Everton, have adapted the system for several applications in a variety of industries, including a cyclonic falling-film evaporator for dairies. Its first installation came on-line last year to concentrate lactate permeate at Select Milk Producers' plant in Dexter, NM. The project also led to the creation of Acqua Dairy, a joint venture between the two firms to market separation technology in North America.

Food Engineering recently visited the New Mexico facility with Everton, a mechanical engineer with a degree from Monash University in Melbourne, Australia, who worked for Conoco Oil before helping form Acqua. Everton oversaw deployment of the Acqua separator technology at Shell oil sites worldwide and spent a total of four months in New Mexico transferring the technology to the US food and beverage industry.

FE: What advantages does the cyclonic evaporator offer, compared to other falling-film evaporators?

Everton: The most obvious is size: the calandria is approximately half the height of a conventional unit. Besides reducing fabrication costs, a smaller size means a smaller footprint and lower capital costs in the plant. Energy efficiency is another advantage. The heads create a swirling motion, like water going down a drain, with very even distribution. Typically, energy costs can make evaporators very uneconomical to operate. But the helical heads on each of the tubes inside the calandria greatly increase the heat transfer coefficient, while the swirling effect created in the fluid stream reduces burn-on and allows longer production runs between cleaning cycles.

FE: How does the evaporator at Select Milk work?

Everton: Lactate permeate enters a balance tank at 36