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Ice pigging: Culture change, integration in food manufacturing processes, enhanced value with studies on product & sanitising pigs. (AFM 279) - FT1574

Application of ice pigging in the water industry is easier than in the food sector because the inherent problems are easier. In the water industry the fluid (water) is well characterised, the boundary conditions (pipes) well known and similar throughout the industry and, the operators tend to be very well trained with very specific tasks to undertake. In the food manufacturing sector the situation is more demanding; the products show enormous variability, the boundary conditions vary from simple pipes to complex processing equipment, and sometimes the operators are stretched and have demanding production schedules. To achieve the same take-up in the food production sector that the ice pig is enjoying in the water industry we require to innovate the basic technology so that it becomes easy to use, always works and provides compelling benefits. To achieve this the following two major key innovations will be developed, demonstrated and trialed:
1. Integration of the ice pigging technology into working food manufacturing plants. This is more than simply showing that the technology works; it is about integrating a technology which is known to work in the laboratory in a real factory. This will entail integrating a number of diagnostic devices into a Programmable Logic Controller, PLC, which controls valves, pumps, timing etc. The innovation and novelty associated with this are:
a. developing, testing and characterising diagnostic tools and methods to monitor the ice pig as it moves through the plant. The diagnostics must have minimal impact on the plant and must, of course, present no hygiene hazards, be compatible with food production and easy and inexpensive to install.
b. developing our understanding of the thermalhydraulics associated with the ice pig (rate of melting as a function of flow velocity, pipe size and materials, temperature of the environment and of the food products being pigged) such that a simple mathematical model/algorithm can be constructed which can be programmed in the controlling plc of the plant. This is essential, if ice pigging is to become widely adopted in the food production sector; the technology must be integrated into the existing methodologies so that minimal human intervention is required to ‘ice pig’ the various sections of the plant as and when product recovery, product separation or cleaning is required.
c. characterising the performance of the ice pig within complex engineering equipment, such as plate heat exchangers.
2. Enhancing the value the technology provides food manufactures. There are two major items under this enhancement heading; the first is the identification (where possible) of product pigs. These are pigs formed from the inherent food ingredients within the manufacturing lines. The second is the sanitising pig, where appropriate sanitisers are added to the pig. The pig then becomes a soil removing and sanitising device. This could be achieved by a single pig containing a sanitizing/disinfecting medium or a series of pigs (an ice pig train) with the first being the cleaning pig and the second being the disinfecting pig and the last being the neutralising pig ensuring that no undesirable chemicals were left in the system. The innovation and technical challenges associated with these items include:
a. developing an understanding of the effects of freezing point depressants on the resultant ice slurry characteristics.
b. identifying and undertaking experiments on common food materials to characterise their suitability to either act as freezing point depressants or (more attractive) to be capable of being frozen down to suitable pumpable slurries (the product pigs).
c. characterising the effectiveness of sanitizers at low temperatures; for example caustic solutions work best at elevated temperatures, hypochlorites are also more effective at moderate temperatures than at depressed ones. The aim of this part of the project is to identify whether sanitizers blended into the ice pig, perhaps as part of the freezing point depressant, can deliver effective sanitisation effects. The exciting part of this work is that we will be able to use very high concentrations of sanitiser because the volume of the pig will be relatively small compared with the working volume of the plant. Indeed, the ice pig becomes the delivery vehicle for the sanitiser. Success in this area would have significant benefits, including the reduction of total chemical burned on the environment.
Ice pigging is an innovative idea in which crushed pumpable ice is used as a semi-solid object to clean pipes. It was first patented in 2000. Since that date the technique has been demonstrated to work. A significant part of this demonstration was accomplished under a previous DEFRA funded project (AFM163) which ran during t 2001 to 2004. Although the technique works, no significant industrial take-up of the technology occurred in the food manufacturing sector. The technology has been taken up in the water supply industry, indeed, the technology won the Water Industry Achievement Awards for the most Innovative Technology of 20091, 2 .

The objectives of this project are to overcome the hurdles that have delayed the take up of ice pigging in food manufacturing. Specifically the objectives are:
1. To automate and integrate ice pigging into food manufacturing processes,
2. To enhance the technology’s value by developing, testing and characterising the effectiveness of sanitising ice pigs, and,
3. To accelerate culture change and enhance the industry’s awareness of the economic and environmental benefits ice pigging delivers.
Provided we meet these objectives, ice pigging will deliver the benefits to the food manufacturing sector that are currently being enjoyed by the water industry.
Project Documents
• Abstract : AFM279   (22k)
Time-Scale and Cost
From: 2011

To: 2012

Cost: £206,000
Contractor / Funded Organisations
Ziegra lc Machines (UK) Ltd, Diversey Ltd, Barvick Engineering, General Mills Berwick Ltd, ABB Td, PCIP Limited, Greencore Group (UK), Premier Foods Group Ltd, University of Bristol
Fields of Study
Resource Efficient and Resilient Food Chain