Balancing highly efficient handling with low energy costs is an increasing concern for food and beverage manufacturers and the ability to meet process needs precisely, without wasted energy is high on the industry’s agenda.
Food manufacture, of course, covers both hygiene critical duties and non-hygiene critical material handling. For example, waste materials demand efficient handling, particularly because of the very strict control of waste materials entering the environment. Processes that involve solids reduction and separating out coarse particles from liquid flow are essential to ensure optimum treatment effectiveness is achieved and any appropriate legislation is met.
Progressing cavity (PC) and rotary lobe pumps are perhaps the two most versatile positive displacement pumps for a wide range of food manufacture applications and food waste handling.
Maximum Efficiency
One of the reasons these pumps work so well in food and beverage applications is because their flow rate is directionally proportional to pump speed. Maximum efficiency is maintained at any pump speed, which means that the pumping rate can be carefully controlled to meet process demands through the use of variable speed drives, without wasting energy.
A direct benefit of this is occurs in dosing and batching, where very accurate (better than ±5%) control of flow is possible, a performance that cannot be achieved with high speed operation centrifugal pumps, which inherently overrun.
Another advantage of PC and rotary lobe pumps is that they will easily transfer liquids over a large range of viscosities, i.e. from water through to viscous syrups or concentrates and even semi solid pastes and slurries containing soft and hard solids. Liquids containing entrained gases e.g. contaminated liquids are also not a problem.
Flexible Design
One major feature is that they are often very flexible with regard to location in a plant. This is as a result of the positive displacement action, which provides excellent lift (suction) at the inlet so that submersing the pump in the medium or full priming is not required.
The pumping action of both PC and rotary lobe pumps is quite gentle with minimum shear. Thus, if the liquid in the cavity is carrying solids, they go through the pump intact. Both types of pump can be safely used with difficult and movement sensitive products like yoghurt, without destroying its consistency.
Both PC and rotary lobe pumps can draw liquids through macerators and grinders, which makes them able to handle food waste which has been macerated. At the discharge side they can operate effectively against pressure, so that relatively long runs of small bore pipework are practicable, which facilitates easier plant design and installation economy in many processes.
Critical Processes
These pumps are highly efficient at handling difficult to transfer viscous products like sugar syrups, sauces, soups and gravies, with or without solid inclusions. For temperature critical processes, the rotary lobe pumps feature an all metal pumping chamber which can be encased in a heating or cooling jacket, which enables them to maximise handling efficiency, with a standard temperature range of -20°C to +100°C (+200°C on special designs).
Pumping media like meat slurries, pastes and pâtés is often a difficult process, especially where cartilage, offal and gelatinous substances are involved, making the material effectively non-flowing. For these applications, a PC pump positively fed by a screw conveyor with an enlarged throat or inlet provides the power to move this media efficiently over extended distances to where they are required for the process.
Easy to Clean
Hygiene is, of course, a very high priority for food and drink manufacturers. Both PC and rotary lobe pumps include wetted metal parts in 316 stainless steel, and can be supplied with hygienic fittings as well. All pumping chambers are designed for easy cleaning without any areas where product can collect.
PC pumps are available with food approved grades of resilient stators, while rotary lobe pumps are additionally available with EHEDG certification to meet the highest standards. Both are suitable for Clean-in-Place and Sterilisation-in-Place routines, enabling complete cleaning regimes to be implemented without dismantling pipework.
The hygiene credentials and practical design of the progressing cavity and rotary lobe pumps makes them ideal for food and beverage manufacture applications. Their ability to offer a very wide range of pumping solutions, from processing the raw material to handling waste, enables manufacturers to use these high performance products to reduce energy consumption and, importantly, achieve measureable cost savings across the board.
Headquartered in the UK, NOV Mono is a designer and manufacturer of pumps, parts, grinders, screens and packaged systems.