- THE MAGAZINE
- FOOD MASTER
Obviously you can’t do without pumps in your plant-whether it’s to pressurize water for cleaning, to move it as an ingredient to a process, or to move a food product from point A to point B, where B might be a filling or packaging stage. But there are ways to think about pump systems that can improve process efficiency, save energy and potentially gain back some floor space as well. All this can be done without sacrificing the quality of food and beverage products that have to be pumped.
However, getting the best results in handling product, moving CIP water/chemicals and saving energy requires input from as many sources as you can get. These include pump suppliers, system integrators, consultants, skid builders and other processors-and events like FE’s Food Automation & Manufacturing Conference (FA&M). (For more on positive displacement pumps and CIP, See “Tech Update: Pumping Systems,” FE, April 2010.)
Smart thinking applicationsWhile the US government has mandated the use of high-efficiency, three-phase motors (Energy Independence and Security Act of 2007) in the 1 to 500hp range beginning this year, the fractional improvement in efficiency gained with using premium-efficient motors won’t compensate for the misapplication of pumps. “Many times we have seen installations that are using the wrong pump for the application or a pump that is sized wrong ‘just because we had it already,’” says Jim LeClair, global product manager for SPX Flow Technology.
Providing the most efficient pump for the application isn’t always obvious. “Many times I see pumps that are put into applications that may not be the best selection,” says Sam Raimond, customer service supervisor at Fristam Pumps USA. “The most common issue I see is trying to fit a large 1750 rpm pump into an application thinking that a lower-speed pump will be gentler on a customer’s product, when many times a more efficient, 3500 rpm pump would handle the product with less shear.”
“Using a pump that is half as efficient can cost you more energy than purchasing a new pump even in a single-year payback scenario,” adds LeClair. “So, the real savings is from making sure the application of the pump within the process is correct.”
These misapplications that LeClair describes could be the use of a rotary lobe pump in a centrifugal application, which creates a huge problem in pumping and energy efficiency-or the use of a very inefficient pump in a process application that would benefit from using a pump with a higher performance specification. For processors without years of experience, pump suppliers and system integrators have a wealth of knowledge about the proper application and sizing of pumps.
Even though this knowledge exists, it is incumbent on processors to get the whole story from suppliers. “There is a glaring market failure to price in all the costs,” says Clyde Smith, Fluid-o-Tech technical manager. “In a perfect world, pumps would be chosen to minimize their total lifecycle costs.” Total lifecycle costs, says Smith, include the initial acquisition price, accumulated energy charges, maintenance costs and disposal/recycling fees.
“When times get tough, there is a tendency for specifiers and end-users to fall into the trap of ‘cheapest is best’ without first considering the host of factors for reducing total cost of ownership,” says Chuck Treutel, Watson-Marlow MasoSine national sales manager. This is especially true for positive displacement pumps, which can be very application specific. Besides normal maintenance, ease of cleaning-whether manual or CIP-is also a major factor in a pump’s overall lifecycle cost. The longer cleaning takes, the longer the line is down.
Pumps that are CIP-able should be engineered with ease of maintenance in mind, says Raimond. For example, Fristam’s FPR centrifugal pumps have front pull-out seals that eliminate the need to remove the pump head during seal change-out, he adds.
Saving electrical energyOptimizing centrifugal pumps for a reverse osmosis (RO) filtration process improved efficiency for a Western US cheese producer; a single pump replacement consumed 15 percent less power than its predecessor. Alfa Laval worked with the processor to determine a suitable replacement pump, and suggested recording all the pertinent power consumption data for one week for one of the existing pumps in its multi-pump RO application.
On a trial basis, the cheese processor installed a Model LKH-PF60 high-pressure centrifugal pump operating at the same duty conditions and recorded all the power consumption data for one week. The resulting information confirmed the LKH-PF60 consumed nearly 15 percent less power than the existing pump, providing an $1800-per-pump-per-year savings on electricity. Considering 2011 energy costs at the processor’s location of 4.5 cents per kilowatt-hour, savings in other parts of the country could be considerably larger, says Chad Hawkins, Alfa Laval sanitary pumps business development manager.
As a result of the successful trial, additional LKH pumps were purchased. Fewer were required to do the same work, reducing costs and increasing available floor space. In this RO application, LKH pumps can handle throughputs up to 1,200gpm with inlet pressures up to 600psi. In a series configuration, the pumps are daisy-chained inlet-to-outlet, and pressures are controlled by using VFDs and pressure transmitters on each pump, rather than running the pumps at full speed and using valves to control the pressure, says Hawkins.
According to Darryl Wernimont, POWER Engineers market specialist, using VFDs with pumps saves energy, considerably reduces wear and tear on the pump and completely eliminates the throttling valve. VFDs also present a power factor of 1.0 to the electric utility system-even with less-than-optimal pumps. This is good for two reasons. First, power companies like to see proper loading of their circuits. And second, when a plant’s power factor is off (highly inductive or capacitive reactance) from 1.0, the processor may have to invest in power factor correction equipment and/or pay the utility additional charges.
The use of VFDs with brushless DC motors for speed control also saves energy costs, says Smith. Brushless DC motors consume electricity more or less in proportion to their pump load. Therefore, exactly matching the motor to the pump load for the purpose of efficiency isn’t necessary. In fact, says Smith, good load matching can be difficult and sometimes impossible to do.
Compressed air savingsWithout a doubt, compressed air usage is one of the biggest utility expenditures for any plant. The problem is, according to seepex President Mike Dillon, maintenance and process engineers don’t often think to look at the cost of compressed air because it simply gets lost in the overall electric bill-unless someone connects a monitor to the compressors.
According to the US Department of Energy’s “Energy Tips-Compressed Air” Tip Sheet #2 (August 2004), a “potentially inappropriate use” for air as an energy source is in the powering of air-operated diaphragm pumps. It suggests solutions such as using proper regulators, adding speed control and/or migrating to an electric pump instead.
Energy consumption wasn’t the only reason Pukka Pies, located in Syston, Leicestershire, UK decided to replace its pneumatically operated air pumps with MasoSine SPS 2.5 pumps to transfer meat fillings. Noise levels and long cycle times were two other factors in making the change.
“We were using a pneumatic air pump to transfer pre-cooked meat from a 200-liter-capacity, low-level hopper to a top hopper ready for the depositor to fill the pies,” says Simon Kemp, maintenance manager. “In the first instance, the pump was very noisy, and we wanted to improve the working conditions for our bakery operatives. We also found that the meat mixture-which is rich, thick and full of meat chunks and, therefore, must not be damaged-was problematic for the pumps we had on site,” he adds. “We needed to find a pump that could suction-lift the mixture from the mixing bowl up to the depositor feed hopper while maintaining product integrity.”
The pie manufacturer asked for information on Watson-Marlow’s MasoSine positive-displacement (PD) pumps, and was introduced to the SPS 2.5 model, a pump suited to high-pressure, hygienic operations in food plants. The pump’s sinusoidal rotor produces powerful suction with low shear, low pulsation and gentle handling.
“With the installation of the first MasoSine SPS 2.5, we managed to lower noise from 94 dB peak to 74 dB peak,” says Kemp. (In terms of human sound perception, a 10 dB decrease sounds half as loud as the original; a 20 dB decrease sounds one-fourth as loud as the original level.)
The process of transferring meat to the top level depositor feed hopper is controlled by the processor’s own VFD system. In combination with the easily integrated SPS series pump, which has plenty of lift for the dense pie fillings, the new system is delivering a further benefit of 20 percent faster pumping times.
“Furthermore, since the installation of the first MasoSine pump around two years ago, we now use far less compressed air-to the tune of 660 l (23 cu. ft.) per minute,” says Kemp. “This obviously equates to significant savings in our energy consumption.” Kemp also reports the pumps are easy to dismantle and clean. “It only takes around 20 minutes before we are ready to go again, which is quicker than using our previous air pumps.”
Diaphragm pumps, which can be used in product unloading or filler feed applications, do use compressed air, and while air operation provides a great deal of flexibility, this style pump has the reputation of being a high-energy user, says Wallace Wittkoff, hygienic director, PSG-Wilden/Mouvex. “A key reason for traditionally high energy usage is not from what most people might think: that the pump concept is inefficient. The primary reason is that the pumps are operated in an inefficient way because of their design,” he says.
One solution to this problem that Wilden introduced some time ago-and is still in use today-can be found in its PX diaphragm air motor system. This system, according to Wittkoff, does for diaphragm pumps what trimming impellers or using VFDs has done for centrifugal pumps. The system makes sure the air volume (which correlates to energy) that goes through the pump matches the displacement of the diaphragm, which equals the displacement of the product pumped. Without this system, much more air goes through the pump and out the muffler than is actually needed.
Nevertheless, eliminating an untuned, air-operated PD pump altogether and using an electrically powered PD pump can pay for itself pretty quickly, says Dillon. Depending on the application, Dillon has seen ROIs typically shorter than a year and, in some cases, a couple of months. The process of converting electrical energy to compressed air, and then using air to create mechanical energy to run a pump, is inefficient.
Energy savings slipping away?In PD applications, rotary pumping systems with eccentric disc technology often represent a good choice for viscous liquids, but according to Wittkoff, these pumps can have their share of slippage when pumping water-like liquids with a viscosity of 1 centipoise (cps). “Positive displacement pumps by definition should have little slip, but the reality is that with low-viscosity products [pumped] against pressures greater than 100psi, slip can be more than 80 percent.” A typical lobe pump handling a water-like substance would nominally have a flow of 40gpm against 100psi pressure, but would actually pump only at 5gpm. The 35gpm difference is what “slips” and represents 88 percent of the amount of energy expended in unnecessary pumping. As the pump further wears, its slip approaches 100 percent, indicating time for a rebuild.
According to Wittkoff, slip can be minimized by designing the pump to be “self-adjusting,” so the pump maintains its clearances as it ages, and slip can be held constant throughout the useful life of the pump. Mouvex engineers have been able to create a pump (under conditions of a 1cps product pumped against 100psi pressure) whose slip at a flow of 40gpm can be held to 4gpm. This represents a 10 percent loss, which remains constant after several million cycles as the pump automatically adjusts clearances as it ages. Higher-viscosity liquids will have less slip through the pump.
Progressive cavity pumps and lobe pumps have similar wear issues, according to Dillon. seepex’s Model SST/SCT pumps all have adjustable stators. This means the compression between the rotor and stator can be set for the individual application. The most commonly touted advantage of the adjustable stator is that it lasts longer than conventional, molded-to-metal designs. The real benefit, however, is that only enough compression (also torque) needs to be added to overcome the differential pressure of the application, says Dillon.
Molded-to-metal stators and lobe pumps typically come with a set or standard amount of compression, so the torque required is always in excess of what is required for the application. “As the compression decreases through erosion and natural wear, the pump’s mechanical efficiency improves, but then once it wears too much, the volumetric efficiency starts to erode,” says Dillon. Model SST pumps provide an adjustable stator (smart stator technology) that allows the peak overall best efficiency to be maintained over the entire lifetime of the pump, adds Dillon. The user can minimize the depression and determine the best efficiency point, maximizing both mechanical efficiency and volumetric efficiency.
Selection depends on the applicationProgressive cavity pumps can improve efficiencies in applications where existing pumps fail to deliver at very low temperatures. For example, Bulmers was experiencing problems at its cider plant when an existing pump had problems offloading a tanker truck of cider concentrate due to pressure in the pipe work. The pump took four hours to unload the tanker, and it also created unnecessary waste as it couldn’t completely empty the tanker.
To provide a solution, a Mono Helios progressive cavity pump was installed at the plant to offload the concentrated apple juice used to make cider. The self-priming pump has a capacity of 3170g/hr. (12 cu.-m/hr.) at a pressure of 137psi (9.5 bar), and handles high viscosities and solids in suspension. The flow is unaffected by system pressure changes. “The Helios pump has more than met our performance criteria and is able to offload the tanker in less than two hours, avoiding any demurrage charges,” says John Williams, cider production manager. “It handles the cold, high-viscosity apple juice very well and is quiet in operation with very little vibration.”
While a progressive cavity pump solved Bulmers’ tanker unloading problem, this type of pump was not the best solution for Parmalat SpA, a dairy in Parma, Italy. The dairy was looking for a solution to pump a milk product containing Omega 3, milk powder and chocolate milk. The pump had to run 12 hours a day and meet EHEDG/3-A/FDA regulations. The dairy was looking for a pump that would have a lower total cost of ownership in terms of maintenance.
The dairy chose Alfa Laval’s OptiLobe rotary lobe pump. After 16 months of operation, the pump required no spare parts replacement, which lowered maintenance costs compared to the older pump. “The OptiLobe pump is very compact and easy to operate,” says Gianpaolo Saccani, Parmalat’s chief maintenance engineer who is responsible for all the company’s plants that prepare raw materials for the UHT production lines. “But most importantly, it is really hygienic.”
Continuous processingWhat does an oil refinery have in common with a beverage or food processing plant? Not a lot. But for some food and beverage processing plants, the commonality might be more observable-that is, if a particular application lends itself to continuous processing/blending instead of batch processing. Of course, there are a lot of “ifs,” but, according to Dillon, if a process can be converted from batch to a continuous blending system, there are a lot of savings-time, space, energy and money. The controls are available, pump technology now includes metering devices, and the sensors/transmitters are available to close the control loop. Dillon already has carbonated beverage customers and even dog food processors that are adopting this technology. Dillon says he is already supplying skid manufacturers with pumps to design and build continuous blending systems.
Wittkoff calls this process “inline formulation,” and for applications that lend themselves to this technology, the pluses are: Mixing tanks are no longer needed; batch processes no longer need to run, but are converted to a continuous process; formulated product goes straight to filling/packaging, eliminating holding vessels; and in the conversion, floor space is freed up with the elimination of mixing/holding tanks and vessels. The system allows for quick changeovers and the elimination of several steps. The biggest drawback, Wittkoff says, is that pumps still have too much slip to provide a consistent process with some liquids. Nevertheless, products that work well with this scenario are toothpaste and certain pet foods where viscosities are greater than 1cps.
This continuous blending concept has already been applied successfully in certain pharma and bio-pharma applications, says Matt Glicken, VP sales and marketing, SensiBlend. SensiBlend, a maker of skid-based systems using all of the pumping, metering and controlling techniques already described, is finding interest in CPG and beverage applications. Glicken says FDA’s Process Analytical Technology (PAT), which was conceived for pharma, is used in this continuous process system and automatically builds in regulatory compliance, making it applicable for food and beverage as well.
In a continuous blending system, smart sensors measure both chemical and physical properties of the product against preset standard values. The system software adjusts proportioning on-the-fly, based on these measurements, to guarantee product quality, adds Glicken. With an inline, real-time system, quality control is integrated into the process. Less waste and simplified production are among the advantages of a system that can be employed for functional beverages, soft drinks and other products.
While energy savings plays a subservient role to maintaining the quality of product as it’s being pumped, nevertheless, the right pump for the right application-whether centrifugal or PD-can change the energy-savings picture significantly. In this era of constrained budgets, maintaining product quality and saving energy don’t have to be mutually exclusive.
For more information:
Jim LeClair, SPX Flow Technology, 800-252-5200, firstname.lastname@example.org
Clyde Smith, Fluid-o-Tech, 860-276-9270, email@example.com
Michael Dillon, seepex Inc., 937-864-7150, firstname.lastname@example.org
Wallace Wittkoff, Pump Solutions Group-Wilden/Mouvex, 909-722-1900, email@example.com
Chad Hawkins, Alfa Laval, 262-605-2600, firstname.lastname@example.org
Chuck Treutel, Watson-Marlow, 608-883-6851, email@example.com
Matt Glicken, SensiBlend, 203-858-0032, firstname.lastname@example.org
Darryl Wernimont, POWER Engineers, Inc., 904-318-7186, email@example.com
Sam Raimond, Fristam Pumps, 608-203-2041, firstname.lastname@example.org