With New Technology, Buying Decisions Hinge on Efficiency
“There is no magic bullet. It takes a lot of magic bullets,” said Pete Lepschat, director of engineering for Henningsen Cold Storage Co., which is based in Hillsboro, Oregon. “Whether that is a capital investment, a process change or even a paperwork change, there is a never-ending list of possible improvements that we just keep rotating back through.”
Lepschat said improving efficiency has been a priority for the Henningsen family since the company was founded in 1923. “It is a cultural thing for us. Since I’ve been here, it has been a major driver,” he said, adding that through technology and equipment, Henningsen Cold Storage has a corporate-wide specific energy usage rate that is well under half of the industry average. “Our newest plant consumes only around 25 percent of the industry average. When our second biggest cost is 25 percent of the industry average, that is a competitive edge for us.”
Bing Cheng, manager of utilities engineering at Campbell Soup Co., based in Camden, New Jersey, said decisions based on the long-term efficiency of systems have become standard practice for designing and choosing Campbell’s new systems. “Our organization realizes these benefits not only affect our operating costs, but also improve our safety environment in the engine room and reduce our risk in human errors,” he said.
SIZING SYSTEMS CORRECTLY
For Henningsen Cold Storage, the lowhanging fruit was gone a long time ago, and the company has had to become creative. “We’re doing things that are harder for a typical company to justify,” Lepschat said. “We see the benefit so we invest more. The savings compound like interest. It pays off over time.”
Henningsen Cold Storage has built several plants over the past few years, and Lepschat said the company has made a commitment to reduce ammonia charges in their systems. The company’s last plant utilized a central pumpedliquid overfeed ammonia system with an evaporative condenser on the roof. “The charge is very low at 3,000 pounds for a 143,000-square-foot freezer facility with refrigerated docks. That is also our most energy efficient plant,” Lepschat said.
As part of his quest to reduce the ammonia charge, Lepschat recently started investigating carbon dioxide. “I had looked at ultra-low charge packaged NH3 , CO2 trans-critical and CO2 /NH3 cascade,” he said, adding that as part of his research he looked at construction, operating and energy costs. “With conventional ammonia, you have to have someone there every day watching the system. That is a fairly big cost. With CO2 , it is pretty much a hands-off system.” “The Trans-critical CO2 system shaved several weeks off the construction schedule and saved thousands in construction costs.”
The company ended up installing a transcritical CO2 system, which Lepschat said “seems to check all of the boxes.”
Evaluating the system requirements is also a priority for Campbell Soup Co., and the company is careful to size its refrigeration systems to match its cooling loads as closely as possible when rolling out new refrigeration system designs. “Closely matching ammonia compressor capacities to our cooling requirements ensures that we are operating at efficient, full-load conditions,” Cheng said.
What’s more, proper material selection and installation of insulation on piping, vessels and valves have provided longterm efficiencies in reducing heat loss for Campbell’s. In addition, Campbell’s tracks its electrical and water usage, which allows the company to quantify its efficiency gains specifically related to the ammonia refrigeration system.
SELECTING NEW EQUIPMENT
Campbell’s has started to standardize the water treatment system for its condensers, utilizing a system that does not require any traditional water treatment chemicals. “This has reduced our blowdown rates, eliminated the need for chemical treatment equipment and eliminated our chemical material costs,” Cheng said.
Henningsen designs its systems with more heat exchanger surface area. “Larger evaporators and condensers allow us to reduce our pressure differential. Those systems are more efficient,” Lepschat said.
Henningsen has also embraced creative use of waste heat in the systems. “Traditionally, we’d send all of our heat outside and get rid of it into space. We’ve taken to doing things like warming under floors with it in some of the newer facilities,” Lepschat said. “Rather than it being a waste product, now I almost don’t have enough of it.”
The waste heat can also be used to control humidity in parts of the warehouse or heat workshops. “We’d have to pay to heat with gas or electricity and now we’re using waste heat,” Lepschat said. “It is a reasonable investment and provides a reasonable return.”
To reduce maintenance needs on its existing systems, Henningsen has turned to sealless ammonia pumps. “You don’t have to periodically replace the seal, and a common leak point is eliminated. We are also using welded instead of flanged controls and valves for the same reason,” Lepschat said.
Some operators have invested in corrosion-resistant pipe and valve treatments that last the life of the valve train system, which can save time. Traditionally, a facility could shut down for a week to sand and repaint all valves every year or so, but end users can now bypass that whole process and eliminate unnecessary maintenance related to managing corrosion, thus freeing up staff from time spent sanding and painting.
For Henningsen, other changes, such as investing in LED lighting to reduce the heat load inside of the freezer box and adding high-speed doors to freezer openings to minimize infiltration, have provided additional efficiency gains. “It is a death by 1,000 cuts kind of scenario. Many small savings measures add up and compound over time,” Lepschat said.
TURNING TO AUTOMATION
Campbell’s systems are fully automated, which ensures equipment is operating at optimum efficiencies. “We also operate our compressors at the lowest suction pressure, while maintaining our plant cooling load requirements,” Cheng said.
Campbell’s provides variable frequency drives on its condenser fan motors, which can help stabilize head pressures. “Condensers experience variable load conditions and having them on variable frequency drives eliminates the on/off conditions, which is inefficient,” Cheng said.
For the past 20 years, everything refrigeration related has been computer controlled at Henningsen, and the company has used variable frequency drives for the past 20 years. “We wouldn’t do a plant without VFD fans on condensers and evaporators and variable speed compressors. Those give us a huge bang for the buck,” Lepschat said.
Because most of Campbell’s systems are controlled automatically, operators can focus on monitoring and maintenance related tasks. “This also reduces the risk of human error and provides for a safer working environment in the ammonia engine room,” Cheng said.
Lepschat said training staff is a top priority. “You can take the best designed or the most capable, efficient system and put in an operator that doesn’t know what he is doing, and is all for naught,” he said, adding that he focuses on teaching critical thinking to employees. “If they know the theory behind what is happening and don’t take things for granted they are much better at finding ways for things to be improved.”
DRAWING ON DATA
Gathering and tracking data on refrigeration systems, maintenance and repair can help operators take a risk-based approach to repairs and replacements, which can improve safety and ultimately reduce expenses.
Lepschat said data is king and Henningsen Cold Storage logs large quantities of information. “It goes into the database. We have information in there from the day we installed the system right up to now. You can trend things over time, like pressures and temperatures,” he said. “All of our engineers are looking around in there for trends heading the wrong direction or things that pop up that aren’t right.”
Peter Thomas, president of Resource Compliance Inc., based in Dinuba, California, said gathering and tracking data is essential to predicting when equipment may fail in the future, which can improve operating efficiency by eliminating unnecessary downtime. “Collecting data quarterly for compressor vibration analysis can be thankless to an owner who is trying to cut costs, but could be the difference of tens of thousands in repairs later on,” he said.
Campbell’s monitors, tracks and trends operating data associated with our refrigeration systems through its programmable logic controllers/human machine interfaces. “This provides insight into our operating efficiencies and helps us in troubleshooting,” Cheng said.
In addition, Campbell’s operators perform daily checks of its refrigeration systems, which help identify any anomalies or maintenance issues. “We also perform five-year mechanical integrity audits to check any deterioration in our piping, vessels and insulation systems,” Cheng said.
Lepschat said the goal is to use data and information to get to predictive maintenance rather than reactive or preventative maintenance. “The idea is to do inspections of that device, piece or part and use tracking and trending along with history to predict what needs to be done and to do it at the optimum time which is just before it fails. We do a lot of that now,” he said.
Henningsen has also taken many of its inspections to the next level, which provides a clearer picture of equipment condition. Rather than doing a semiannual vibration analysis, the company does semi-annual shock-pulse monitoring, which Lepschat said is, “10 levels above basic vibration analysis. We actually invested in our own SPM equipment and sent all of our operators to factory training, enabling them to take readings as often as they want.”
Henningsen also invests in more advanced oil analysis. “You can do the basic one and it gives you information on water and wear metals, or you can spend a few more dollars for one that also gives you viscosity, total acid number, and a lot of other useful info.” Lepschat said, adding that the company has invested in oil filtration systems which have virtually eliminated compressor oil changes. “I have plants built in 1996 with the original oil in the screw compressors, which still tests fine every six months. I’ve eliminated the cost of oil, the labor to change it and the danger associated with opening the system to get the oil in and out”. “The compressors still look like new inside when we have them torn down for internal inspections
While vibration analysis and electrical tests have become common practice for larger companies, it can be difficult to educate the owners of smaller companies on the value, plus it can be a challenge for them to find qualified personnel to interpret the results of the data that is collected, Thomas said.
“Smaller companies need to partner with competent contractors and consultants that they can trust guide them through the process,” Thomas said. “It is unlikely that a small business will have qualified staff to obtain or even interpret the results, so it is important to have business partners that can help.
Consultants can help companies get more value out of their five-year inspections, Thomas said. “Different consultants may have strengths in different areas — vibration analysis, piping inspection, ultrasonic thickness testing, RAGAGEP, etc.,” he said. “Make sure that the inspector’s qualifications are suitable to what the business needs are.”
