FEATURE EFFICIENT PRODUCTS


THE RIGHT CHEMISTRY for saving energy


Motor efficiency is often overlooked completely when chemical companies are


addressing energy saving. Tony Young, director of CP Automation, presents his top tips for ensuring that the motors in your plant run as efficiently as possible


W


ith costs rising, industrial companies need to contain their


electricity usage. But, those companies that do invest time and money in energy reduction rarely get much further than fitting variable speed drives (VSDs) or haggling on price per kilowatt hour. There are, however, a host of additional measures that can be addressed with very little capital expenditure – and they all result in a long-term profit. The technical challenges that face


highly complex chemical plants are great, from the integrations of many different energy sources to maintaining a wide array of energy conversion systems — and let’s not forget the need to effectively use by-product energy. For example, hydrogen is created as a by-product from the manufacturing of chemicals like chlorine. This can be captured and transported for use or used to help power the plants themselves.


TAKING STEPS One of the first steps should always be to ensure you are fitting the right size of motor for your application in the first instance, whether this is for your pumps, fans or compressors. A good provider of motors, controls or VSDs will always offer an audit first which will help you achieve this. Over specifying products ‘for tomorrow’


means bigger energy and maintenance bills. I’ve seen countless motors, which are doing an easy job like water pumping, specified at a much higher capacity than is required. Sometimes this is to the point that the motor costs £2000 but the same job could be done by a motor costing £1000. Furthermore, if you plan to add a VSD


now or later as a retrofit product, ensure that the motor is VSD rated to start with. Otherwise, any retrofit project will involve replacing the motor as well.


KEEP IT SIMPLE The less complex the motor the better. From a repair perspective, if you can use a standard energy efficient motor, which you can switch on and have spin at the


20 SPRING 2021 | ENERGY MANAGEMENT


right speed with no bells or whistles, then use it. It will be cheaper to install, there will be less to go wrong and if something does go wrong the repair will be easier and cheaper. Choosing a high efficiency motor isn’t


always a given in every application. However, with the Eco Design Directive in place we should see less end users specifying low efficiency equipment. Sometimes, simplicity isn’t always


possible and there might be a need for a timing device or soft start to alter the speed. Equally, it may be that you need an extremely high precision motor for your application. Timing devices can be hugely


underused in the chemical industry and are a very cost-effective way of saving energy on non-continuous use applications. Often pumps and ventilators run constantly, even if there are times of day when there is no demand. You’re not just saving energy from


not running a motor unnecessarily, but from elongating the life of your systems. For example, the hydraulic pumping efficiency of your cooling systems will experience less degradation over time and remain optimally efficient for longer. Ultimately, it comes down to how much flow capacity is possible for a given amount of energy. Soft starts are also increasingly


common on pump applications and they dramatically reduce the energy used when starting a motor. They are also common on conveyors, where the smooth start prevents objects from falling. As an alternative to a motor starter resistor or a VSD they can be more profitable, but only if the application is assessed correctly in the first instance and the device is sized appropriately.


CONSIDERATIONS Inevitably one also has to address the availability of the motor at short notice in the event of a replacement being required. Of course, if spares are


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kept in stock this may not be necessary and so, ironically, the harder to get hold of motors are sometimes the best option. This isn’t because they are scarce, but rather because they aren’t mass produced and may be higher quality. So, while a replacement may not always be easy, a repair often is. In this context, when choosing


someone to do the repair job, you should always go to a specialist. If you go to a company that hasn’t carved out a niche in, say, servo motors, you will find that they will simply sub-contract your repair to a specialist; increasing your bill in the process. Another factor to consider is the


environment in which the motor is going to be used. Chemical engineering is a harsh environment, from inorganic industrial plants right up to explosives. Go for a more complex drive that can be boxed away. Regulations for your industry may demand this anyway, but the added bonus is that the motor and drive are protected from ingress and damage. Just implementing a few of these


tips will result in a reduced energy expenditure on running motors, and in all likelihood other associated equipment.


CP Automation www.cpaltd.net


The technical challenges that face highly complex chemical plants are great, from the integrations of many different energy sources to maintaining a wide array of energy conversion systems — and let’s not forget the need to effectively use by-product energy


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