Synthetic Refrigerant Demand Sinks

Demand chills for synthetic refrigerants on the eve of a 2010 phase-out; Nestle leads the way to a cool, all-natural future.

By Bob Sperber, Plant Operations Editor

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Most food & beverage plant operations managers charged with overseeing refrigeration and freezing systems have already turned a cold shoulder in the past decade to synthetic refrigerants. They know hydrochlorofluorocarbons (HCFCs) including R-22 will begin a phase-out starting next New Year’s Day.

As with the 1990s phase out of chlorofluorocarbons (CFCs such as R-12, or DuPont's Freon), HCFCs have been long-targeted for obsolescence under the 1987 Montreal Protocol and 1997 Kyoto Protocol due to their depletion of the stratospheric ozone layer and contribution to global warming.

Since the 1990s, R-22, once the workhorse, has all but evaporated from use in large industrial systems. This is especially true at the U.S. and Canadian operations of Nestle, the largest of the Food Processing Top 100©  food & beverage processors. The company has been steadily phasing out synthetic refrigerants, including hydrofluorocarbons (HFCs, including R-134a, common in air conditioning), which are not being banned — at least yet.

HFCs are “wrongly presented as the long-term alternative to CFCs and HCFCs,” José Lopez, Nestle’s executive vice president of corporate operations, said in a public statement last year. He added: “Although these substances do not have an ozone-depleting effect, they have a substantial global warming effect and therefore cannot be considered as acceptable long-term substitutes.”

The move toward natural refrigerants is spreading across the food industry, up and down the cold chain. Companies including Coca-Cola, PepsiCo, Unilever and Carlsberg Group — and McDonald’s in the restaurant sector — are publicly back Refrigerants Naturally (www.refrigerantsnaturally.com), a global private-sector initiative seeking to stamp out synthetic refrigerants down to point-of-sale retail and foodservice locations. Official bedfellows in the alliance include GreenPeace and the United Nations Environment Programme (http://ozone.unep.org).

Synthetic drawbacks
Industrial refrigerant users originally turned to R-22 to escape ammonia’s safety and regulatory issues, and because it is “almost as efficient as ammonia,” says Bruce Badger, president of the International Institute of Ammonia Refrigeration (www.iiar.org), Arlington, Va. “But it has a significant global warming potential as a refrigerant when it leaks to the atmosphere.” He adds that leak rates are higher for R-22 than ammonia in industrial systems.

Cost-wise, R-22 in recent years has risen to roughly $10/lb. to ammonia’s $1/lb. Prices may keep rising, as happened with R-12/Freon, which rose from $1/lb. to $20/lb. The HCFC ban also may translate to fewer and more expensive mechanical parts and supplies, which could affect plant maintenance and reliability.

As synthetics lose favor, natural refrigerants are poised to offer significant cost, efficiency and energy-usage benefits. “Whether or not we all agree that climate change is the result of human activity, the benefit of energy conservation can be justified purely on the business mandate to reduce energy costs,” Badger says.

Making the switch isn’t as easy as making a quick refrigerant substitution. At this point in time, users and their supply-side partners should have a firm grasp on life-cycle costs and a timed strategy for future maintenance, retrofit and replacement schedules.

{br}The ammonia-CO2 solution

In his 2008 statement, Nestlé exec Lopez reiterated the company’s 2001 commitment to continue moving toward eco-friendly natural refrigerants and do away with synthetics.

Especially and whenever feasible,” he said, carbon dioxide (CO2) and ammonia “must be used for all low-temperature applications. Beyond many technical and economical advantages, carbon dioxide is safer for the environment, people and goods … [and]… water or glycol chillers with ammonia refrigerant must also be used for all positive temperature applications.”

Nestlé has been ahead of the curve on ammonia-CO2 systems, installing them since 1990s as part of its R-22 phase-out strategy.

“Our current aim is to minimize ammonia charges within our plants,” says Bent Wiencke, manager of refrigeration engineering for Nestlé U.S. and Nestlé Canada. “But ammonia is still the most efficient choice for our primary use of refrigerant.

“If we wanted to eliminate ammonia completely, one alternative would be a CO2 transcritical system,” he says of the higher-pressure, all-CO2 systems, “but nobody has developed a system yet that we believe is reliable enough.”

The most common CO2 strategy for industrial users is the hybrid ammonia-CO2 cascade system. There are various configurations, but generally they involve an ammonia system confined to the refrigeration engine room, and a secondary system carrying a much greater quantity of CO2 being circulated through process equipment such as a blast, tunnel or spiral freezer. The CO2 is then piped back to the engine room where the ammonia system scrubs off the heat the CO2 refrigerant picked up in the process and dissipates it, typically to the atmosphere through a roof vent.

Nestlé has pioneered ammonia-CO2 cascade systems in varied applications, including:

  • The 2000 commissioning of the largest CO2-ammonia cascade system “built in the past 50 years” at its Nescafé factory in Hayes, England, because no commercial scraped-surface heat exchange system was available for freezing coffee liquor.
  • The 2003 commissioning of “one of the first and world's largest” ammonia-CO2 systems at Nestle USA’s prepared meals plant in Jonesboro, Ark.
  • The 2005 commissioning of an ice cream freezer in Thailand despite that country's distant phase-out date for developing countries — 2040 under the Montreal Protocol.

The company has sourced technology from across the globe, at times co-designing them when they weren’t available. “On one hand, customizing systems to our needs gives us a competitive advantage,” Wiencke says. “On the other hand, we don’t want to be the lone ranger. We want this technology to be readily available, which will result in lower costs for everyone.”

Better than recirculation pumps

JBT LVS

Click to Enlarge
JBT’s compact LVS system eliminates traditional pump recirculation to reduce refrigerant charge. In a cascade system, it separates liquid from CO2 before sending saturated vapor through the plant to engine room compressors.

While Wiencke notes that most of the innovation in CO2 systems is being driven by end users, there are exceptions. One such food supplier is the Low Volume System (LVS) from JBT FoodTech (www.jbtfoodtech.com) Sandusky, Ohio. It replaces the traditional pump recirculation loop with a more compact alternative that increases refrigerant efficiency by reducing the pressure drop and temperature fluctuations — problems found in a traditional pump recirculation system.

The technology helps low-side refrigerant loops run more efficiently at lower temperatures than that of standard of pumped recirculation systems while minimizing refrigerant volumes.

A traditional recirculation system pumps liquid refrigerant (for example, CO2) to an evaporation coil in the plant floor freezing system, which could require a piping run of 500 or 800 ft. from the compressor machinery in the engine room. A combination of liquid and vapor refrigerant exiting the process must take that long trip to the refrigeration system’s compressor, requiring extra energy for pumps and often a long piping run up to the rooftop and back down, incurring pressure drop.

Instead, the LVS technology removes the liquid from this loop before it returns to the engine room by collecting it in a vessel and sending only vapor to the engine room. “So the vessel acts as a separator, and can reduce the need for additional equipment while also lowering energy requirements” says Tera Bristow, refrigeration systems engineer with JBT FoodTech.

Since 2001 the LVS system has grown in use from fewer than 15 percent of freezers early in the decade to roughly 60 percent of the freezers the company ships today. This is largely due to JBT offering the technology as a retrofit that can be “piggybacked” to existing and new freezers. Bristow adds that “a new freezer with LVS generally costs the same or less than a complete, traditional system when estimating new refrigeration system costs. But the energy savings — and your decrease in variable costs over the years — are substantial. It's a no-brainer to justify based on the energy savings alone.”

When one food plant upgraded four process freezing lines with LVS — and added a fifth — energy savings were $569 per day over the prior four-line system, JBT reports. LVS systems also are in use at Nestlé. Wiencke says, “Not only has it made them safer and more reliable, but the low volume system also has delivered other operational benefits to our production lines.”

If the pace of innovation picks up, ammonia and CO2 in particular will increasingly prove the winning combination for low-temperature process freezing applications, as will ammonia and other natural refrigerants in cold storage and medium-temperature applications.

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