Industrial water: how to reduce OPEX

Most industrial companies will have strategies for managing capital expenditure – CAPEX – and operating expenditure – OPEX. CAPEX generally refers to investment in capital plant and machinery, with decisions normally involving significant sums. By their very nature, these are taken infrequently and, once made, leave little room for subsequent cost or efficiency savings to be made.

By comparison, operating expenditure, which essentially covers the costs that a company incurs as a result of carrying out its day-to-day business, offers far greater scope for making short term savings and improvements to operating margins. This is especially true for businesses where profitability depends on the cost of each item manufactured, or where unforeseen events are having short-term impacts on operations – Covid being perhaps the most obvious example.

Many industrial processes use considerable volumes of water. This can range from boiler feed to product makeup, temperature regulation and equipment washdown. In each case, water normally has to be purified to the appropriate quality and, in most instances, treated before it can be either recycled or discharged to drain.

Industrial energy
The manufacturing and process industries account for around 20% of all energy consumed in the UK¹. Although this figure has gradually declined over the past two decades, the cost of energy still represents a significant proportion of manufacturing overheads. A significant proportion of energy is used by electric motors and pumps, many of which are used in water purification and wastewater treatment plant; motors, for example, use around 45% of all industrial energy, while pumps account for some 20% of energy usage².

Clearly, replacing aging constant speed motors with variable speed drives (VSD) represents an easy win. Yet, according to drive manufacturer ABB only 23% of industrial motors are equipped with VSDs.³ This is despite the fact that the payback for upgrading can often be measured in months, with energy savings thereafter going straight to the bottom line.

We typically fit pumps with VSDs to all our industrial water purification systems. Although this can add a small premium to the initial purchase price, the benefits to each customer are rapidly realised, in terms of energy savings and reduced maintenance costs – both of which contribute to lower OPEX. There are also benefits to be made through more accurate control of process operations, which can help to reduce maintenance costs and, in some applications, improve product quality.

Boiler feed
High pressure boilers for the generation of process heating water or steam can also add significantly to levels of OPEX – a factor that has been exacerbated in recent months by increasingly volatile global markets for electricity, gas and oil. For example, official UK Government figures for December 2021 show year-on-year increases of over 7% for users of heavy fuel oils, 16% for electricity users, and over 60% for industrial gas users⁴.

Although boilers are not the only industrial systems that consume energy, they nonetheless account for a significant proportion of all energy used at many manufacturing and process sites. This is especially true in applications where large volumes of live steam are required and where the nature of the boiler system means that boiler blowdowns have to be made regularly, to purge impurities and prevent problems of wet steam, carryover and scaling.  Each blowdown will waste considerable energy.

One of the key factors determining the frequency and length of blowdowns is the purity of the boiler feedwater. Most industrial boiler systems will use a simple water softener to control the concentration of scale-inducing minerals in the feedwater. Chemicals may also be added to the feed and process water to reduce the risk of scaling still further. However, neither method will resolve the problem of dissolved solids (such as inorganic salts and carbonates), which are the primary cause of wet steam, carryover and scaling.

The problem of dissolved solids – or ‘Total Dissolved Solids’ (TDS) to be correct – can only be fully addressed by extending the water purification system to include a reverse osmosis (RO) unit and associated filtration devices. Although this will require a degree of investment the payback in terms of reduced boiler blowdowns can be remarkably fast. For example, the energy and wastewater costs associated with a typical 8 tonne/hour boiler in a live steam application, with just a softening system in place, could be reduced by more than £50,000 per year. This equates to an ROI of around 12 months, with subsequent savings going straight to the bottom line – and, of course, if the option of leasing rather than outright purchase is used then it becomes much simpler to justify the installation of the additional water purification equipment.

Wastewater
Similar opportunities to reduce OPEX can be found by considering methods of recycling waste process water, either for return to the original process or for lower category duties such as equipment washdown. Given the increasingly tough environmental legislation and the rising charges from most authorities for disposal of wastewater to drain, it makes sense to adopt a proactive approach to the management of wastewater streams, as methods of both cost reduction and sustainability.

This approach will involve investment in appropriate water treatment systems, but as with the boiler feedwater example above the payback periods can be relatively fast – often in just a few months.

Reducing OPEX
Given that the manufacturing and process industries use significant volumes of water – it’s estimated that over 145,000 litres of water are required to produce a typical family saloon car, while 75 litres are required to make a pint of beer⁵ – then anything that can be done to reduce consumption will have a direct impact on operating costs.

Cutting OPEX successfully requires a careful analysis of existing systems, a clear picture of future requirements and a planned and proactive strategy. Working with experts that know the best approaches is therefore essential. That’s where our team come in, with the knowledge, experience and resources to help you make significant reductions in OPEX.