HEAT TRANSFER


40th Anniversary 40yrasrevinnAht04 HEATERS THAT GO ON AND ON


include their ease of use, compact size, safer operation when compared to steam generators, precise heat control, low exhaust emissions and energy efficiency. They also operate outside the Pressure Systems Safety Regulations as the fluid is not maintained in the liquid phase by pressure, so statutory inspections are eliminated. But one aspect that frequently gets


overlooked is the longevity thermal fluid heaters enjoy. With sustainability a key issue, plant longevity is not only about reducing capex, but also reducing wastage and equipment redundancy. A Babcock Wanson thermal fluid heater will


usually run for more than 100,000 hours, although we are still servicing heaters that are more than 40 years old and working away every day quite happily! It would be difficult to find any equipment that can match this level of service. There’s no secret elixir for long life, the


Chris Horsley, process engineering director at Babcock Wanson, promotes the longevity of thermal fluid heaters in process applications


F


or a process heating equipment manufacturer, you might just say thermal fluid heaters are bad for


business. They just go on and on - frequently for 20 years and often longer - and maintenance and service requirements are low, a fraction of the cost of maintaining an equivalent heat output steam plant. Even when the heaters themselves might


be at the end of their working life, the pipe work system and other plant is often as good as new, so upgrades are simple and cost effective to implement at any time. Thermal fluid heating is based on a similar


principle to a simple hot water system. It consists of a heater connected to carbon steel flow and return pipework which can provide heat to one or more users or systems. Instead of water running through the pipework, a thermal fluid is used as the heat transfer medium. Different fluids can be used to meet specific process heating requirements including high temperature operations and processes requiring heating and cooling, making it a very flexible system. Thermal fluid heaters have rapidly grown in


popularity across all industry sectors over the years. This is mainly due to their benefits which


STEAM INFUSION REDUCES COOKING TIMES Thermal process solutions provider, Holmach is launching a range of cooking systems powered by


OAL’s Steam Infusion Vaction technology. Aptly named the Perficooker, the machines range in size from 300-3000 litre cookers and can incorporate evaporation, homogenising and an optional jacket system that will allow in-vessel cooling, should temperatures need to be reduced for gelling or crystallisation. Steam Infusion is a direct contact heating process whereby steam condenses on the surface of a


liquid, gently yet rapidly cook a range of food and beverages up to a temperature of 140°C. The Steam Infusion Vaction Pump rapidly heats, mixes and pumps food ingredients and products. By varying the steam pressure and flow rate through the pump, the processing conditions change, from gentle cooking to intense mixing and pumping with a homogenising effect. The Pump (In-Tank and In-Line) can heat 1,000kg of product from 15°C to 90°C in under 10 minutes with no burn-on or particulate damage. In partnership with Perfinox, the vessels are built in-house and can be shaped to fit in with existing


installations. Heating times for products such as meat ragu, soups, sauces and preserves can be reduced. The reduced cooking times maintain flavour and texture better than traditional hemi- spherical cooking technology and are designed to both CE and anticipated UKCA standards. In addition, the cookers can be paired with scraped surface heat exchangers for further product


treatment or linked to vacuum coolers or inline pouch chillers if hot fill is used. Holmach


www.holmach.co.uk


thermal fluid heaters’ longevity is a direct result from their passive nature (there are very few moving parts) and the swapping out of water for a thermal fluid as the heat transfer medium. Unlike water and steam based systems, thermal fluid heaters are unaffected by corrosion caused by water over time, or by ambient temperature where water freezing within pipes leads to costly failures. In fact, most thermal fluids are mineral oil based so are effectively lubricants that help keep the system components protected in use. However, not all thermal fluid heaters are


equal, so it pays to do your homework. Heaters that will best stand the test of time are mostly designed for a downward fired configuration which ensures stress free and unrestricted expansion of the heater coils during normal operation. Also look for a heater that has been designed with a barrier between the hot combustion gases and the outer structure, as this will help provide long heater life as the higher pressure and cooler outer air helps prevent any escape of combustion gases as the plant ages over time. Babcock Wanson’s TPC and EPC range of thermal fluid heaters, for example, come with an integral, air-cooled outer case that provides this barrier, as well as acting as both a combustion air pre-heater/ economiser. Lastly, ensure the heater is fully integrated and has a factory tested control system. It’s also vital that the thermal fluid heater is


correctly installed, commissioned and maintained. ‘Thermal Fluid Systems - A Practical Guide for Safe Design, Operation and Maintenance’ from the Combustion Engineering Association (CEA) proffers good advice for safe and efficient operation.


Babcock Wanson www.babcock-wanson.com


52 DECEMBER 2020/JANUARY 2021 | PROCESS & CONTROL


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