PROCESS EQUIPMENT UPDATE
can be added if and when extra capacity is required. Although allowing for the additional space and infrastructure may incur some cost, this is likely to be less than a much larger over-specified unit and will save money in the long term when expansion is required.
PRODUCT DAMAGE Inappropriate product handling can easily affect key quality parameters, such as taste, appearance or viscosity. Such issues can occur from thermal or physical treatment, or both. Common examples include rough handling of cream causing curdling; pizza sauce losing its viscosity so that it falls off the pizza; fats and spreads becoming demulsified; and fruit juices losing their fresh taste when pasteurised. All of these effects, and more, could
have been prevented by using the right heat exchanger in the first place. For example, not only are scraped-surface heat exchangers good at preventing fouling with viscous products, they can also handle sauces more gently than a turbulent tubular design, retaining the all- important product characteristics.
LACK OF BACKUP OR SAFETY SYSTEMS If a pump fails elsewhere in the system, material may remain too long in the heat exchanger, becoming too hot or too cold. Tis can result not only in product damage, but can also have additional effects on the equipment. A well-designed heat exchanger should
therefore include failsafes to prevent damage from occurring in the event of a system failure elsewhere in the production line – for example, heating coils or a diversion system to prevent chilled products from freezing in the event of pump failure. It is also important to make sure that heat exchanger equipment is included within any monitoring and alarm systems.
INSUFFICIENT CLEANING OR MAINTENANCE Heat exchangers that are designed to be easy to service are more likely receive the prescribed levels of maintenance. Being able to remove and inspect individual components or tubes separately and easily is the key starting point. Te way in which tubeplates and covers are attached is just one of many small details that can have a big effect, as can the siting of drain plugs and inspection covers.
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not perform optimally for the product and service fluid in question. Although intentionally supplying misleading information is extremely rare (not to mention counter-productive), seemingly inconsequential information can sometimes be overlooked. It may appear as if the heat exchanger designers and engineers require an unnecessary amount of information, but this is only because they have the experience to know what variables will affect the performance and longevity of such an important asset – so trust them, and provide as much information as you can.
Corrugated tube heat exchangers
Shortcuts in maintenance can not only affect heat exchanger performance, they can also affect the safety of food and pharmaceutical products; for example, by allowing contamination to occur through leakage. In the worst case, insufficient maintenance or inspection could lead to a failure to spot cracks or corrosion, resulting in major issues that could have been prevented.
Any good heat exchanger design should therefore make routine checking and cleaning as quick and hassle-free as possible.
POOR ENERGY EFFICIENCY Te potential for heat regeneration or product-to-product heat transfer should not be overlooked when designing your heat exchanger system, as in most cases, there will be some ‘heat’ (or cooling effect) left over in the service fluid after it has passed through the heat exchanger. Using a design that reuses (or
‘regenerates’) this heat will reduce overall energy and running costs. For example, a pasteurisation and cooling system could use the heat removed from the product during the cooling phase to supplement the heat input used for pasteurisation. Where two low to medium viscosity products need heating and cooling, it may even be possible to use a product-to-product heat exchanger, removing the additional costs and complications associated with a service fluid system.
INCORRECT DESIGN PARAMETERS If the information provided to the designers of the heat exchanger is wrong or incomplete, then the installed unit will
Any uncertainty should be flagged up immediately; rather than guessing, it is much better to measure the required parameters, even if this involves sending product off for third-party analysis. Failure to obtain the correct information will result in a heat exchanger that, at best, is inefficient and, at worst, inoperable. In some cases, a heat exchanger is used for something different to its original design. For example, a product recipe may be changed, a new product may be introduced or the characteristics of a waste stream are altered as a result of different processes elsewhere in the production line. Whenever any changes are made, the heat exchanger supplier should be consulted as simple adjustments or modifications will often help to maintain optimum heat exchanger performance. Tis is by no means an exhaustive list, and the severity of almost all of the issues listed above can range from mild inconvenience or extra costs, through to severe and catastrophic equipment failure. Safety must always be the prime concern and any equipment that is potentially unsafe should not be used until it has been checked and certified by a competent authority. For less serious issues, if you find
that processing is taking longer than anticipated, or you are spending longer than expected cleaning your heat exchanger, it may be time to get a second opinion.
Matt Hale is with HRS Heat Exchangers.
www.hrs-heatexchangers.com
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