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Feature Heat transfer


Thermal oil solution suits food company just fine


Andy Burns, technical business manager at Global Heat Transfer, describes how the company has helped The Abergavenny Fine Food Company solve thermal oil oxidation issues, reducing explosion risk and equipment damage


hermal oxidation occurs when an oil temperature of over 65˚C and air meet in the same space. This starts a chemical process from the reaction with oxygen, the products of which are organic acids, carbon and sludge. Furthermore, for every increase of 10˚C, the reaction rate doubles. At The Abergavenny Fine Food Company, a medium sized family business pro- ducing snacks, ready meals, diary prod- ucts and desserts, the header tank was in excess of 100˚C and had no nitrogen blanketing system to protect the over- heated oil from the air above it. “We were having a problem with our thermal oil - it was frequently damaging oil circulation pumps,” explained Paul Sanders, site engineering manager at Abergavenny Fine Foods. “We use thermal oil as a means of indirectly heating fryer oil for our breaded party foods line. I had been in the business for a few months when, about three years ago, we got Global Heat Transfer involved. They carried out an analysis of the oil in the system and found that there was a build up of carbon around the pipe work because the oil had not been tested or main- tained for a number of years.” He continued: “The carbon was coming loose and damaging the seals in the circulation pump. Global Heat Transfer put forward their recommen- dations to firstly clean the system, then to refill it, and finally to comply with Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) 2002 using monthly testing and oil analysis.”


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DSEAR legislation requires employ- ers to control the risks to safety from fire and explosions and means more stringent testing for all operators. An effective preventive maintenance pro- gram should include regularly sched- uled and representative analysis of thermal fluids, which benefits users by providing early warnings about process problems, helping maintain a safer working environment, increase system efficiency and saving money while keeping the operator legal under the ATEX 137 regulation.


The regulations complement the requirement to manage risks under the


Process & Control JULY 2012


Management of Health and Safety at Work Regulations 1999. DSEAR put into effect requirements from two European Directives: the Chemical Agents Directive and the Explosive Atmospheres Directive. Global Heat Transfer offers sampling and analysis services of premium qual- ity thermal fluids. The company can service all types of heat transfer sys- tems for clients operating across indus- try sectors both inland and offshore. The 11 point test process goes further than the legislative requirements to show that flash points and correspond- ing auto ignition temperatures are being managed to safe levels.


As part of its 11 point test, Global


Heat Transfer undertakes three main assessments: checking the carbon level and the amount of insoluble particu- lates; closed flash point and the acidity level or total acid number (TAN), which is the amount of potassium hydroxide in mg that is need to neutralise the acids in 1g of oil - an indication of any oxidation or acidic contamination that may be present.


If the carbon level is too high it will result in system fouling which means carbon insoluble particles will stick to the system internals and eventually bake on hard if not cleaned and flushed in time. Carbon fouling can cause heater coil failure, resulting in the risk of fire in the thermal oil if appropriate safety systems are not in place. Global Heat Transfer collects thermal fluid samples in a representative method, by taking a hot, circulating and ‘closed’ sample. This means inaccurate readings, which may have health and


Andy Burns


describes Global Heat Transfer’s 11 point test


A plant room


inspection of the oil based heat transfer system


The thermal fluid controls


safety and legislative implications, are avoided. At The Abergavenny Fine Food Company a team of engineers from Global drained, flushed and cleaned the system using GlobalTherm C1, a combined flushing/cleaning product, exclusive to Global Heat Transfer, before replacing the oil. The dual action power works to rid a heat transfer system of potentially harmful contami- nants such as old/oxidised residual fluids, carbon deposits, loose debris, water and volatile light ends. GlobalTherm C1 is formulated to scour away harsh by-products of syn- thetic and mineral based fluids. It effec- tively displaces and flushes out waste, leaving behind a clean and safe operat- ing system, ready to accept a new charge of heat transfer fluid. It is com- patible with most heat transfer fluids. “Now we have the condition of ther- mal oil under control, and when we carry out our monthly analysis we can pick up an issue before it starts to cause problems,” said Sanders. “We can mon- itor the carbon content and pick up any excess build up of carbon, as well as the acid levels, which can cause corrosion if they go over a certain level. “We can also keep an eye on the flashpoint as well, which was very low in this case. When I joined the com- pany, the oil had not been analysed or changed for seven years prior to Global Heat Transfer getting involved. By that time the damage had been done from the carbon build up in the pipe work, tubes and boiler.”


Sanders commented: “Boiler effi- ciency has improved significantly and has seen our heat-up time reduced by 50%. It is flowing more efficiently and will show a saving in pump life. “At least we can now keep an eye on these things before either a major disas- ter or further damage occurs. We now change the oil annually but we are con- tinually finding improvements in the system which will allow us to extend this period longer and longer.”


Global Heat Transfer T: 01785 760555


www.gobalheattransfer.co.uk 7 Enter 207


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