Ivan Zytynski, from The Spray Nozzle People, says swapping your spray balls and spinning nozzles for rotary jet cleaners is key to achieving sustainability


ith focus intensifying on environmental issues, legislation

increasing and likely to become more stringent, most businesses are considering their impact on the environment. With greater public concern over environmental issues, sustainable and efficient manufacturing processes are no longer only the preserve of accountants and senior engineering management - they are now a marketing and PR issue as well. As a result, engineers are receiving

edicts from management to cut waste and increase the sustainability profile of the company. Here, we look at methods of optimising tank cleaning systems as a way of meeting sustainability targets, and it’s clear that some quick wins with significant efficiencies are possible by optimising tank cleaning processes. The true cost of water, both in

environmental impact and in fiscal terms, is often under appreciated. Firstly, there is the cost of purchasing the water, which is increasing and will continue to rise as pressure on the world’s water systems increase. The cost per m3

water to businesses is significant, but it’s only part of the true cost. Many applications require

water to be heated, especially in cleaning applications. Water with its high specific heat capacity means it takes a lot of energy to heat water to the temperatures needed for optimal cleaning.

The cost of waste-water disposal varies.

Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) are metrics used by the water treatment industry to effectively measure how dirty waste water is. The food and dairy industry often has very high BOD levels resulting in higher waste water treatment costs per m3


Caustics used to break down oils, fats or greases and acids to break down mineral deposits, are common in many tank cleaning systems. These chemicals are not cheap and their usage only adds to the cost of treating the waste water used. There are two commonly deployed

methods of reducing energy/water usage in tank cleaning systems:


Heat recovery –Many factories produce excess heat in their processes and good heat management systems can divert waste heat to be used in other applications like cleaning. This “free” heat is a key method in reducing environmental impact and meeting sustainability targets. Recycle water CIP –Most clean in place

(CIP) systems will reuse waste water from previous cleans. The pre-rinse and even main clean can often be performed with dirty water. Of course, there is a limit to how many times cleaning fluid can be recycled in this way and eventually all the waste liquid needs to be removed from the CIP system.

Once heat recovery and water recycling efficiencies have been realised to their full, where next for the environmentally responsible manufacturer? Optimising the cleaning

of new

mix – One still often overlooked saving can be found by optimising the cleaning mix. The basic theory underpinning any cleaning operation is that there are four contributory factors in cleaning: heat, time, chemical action and mechanical action. An increase in one element will mean that the other elements can be reduced without compromising overall

cleaning effectiveness. From a sustainability

perspective, there is a logical choice

of which element to increase and increasing heat is only going to see the environmental costs rise. Chemical action of course should immediately be seen as a non-starter. Increasing time might seem beneficial but in reality, a time increase in cleaning often means using more water so, again, it’s a non-starter if our goal is to improve sustainability. This leaves mechanical action as the obvious “green” candidate to increase. If we can improve the impact of the

cleaning system, then the other elements can be reduced accordingly. This means the same level of cleaning can be achieved with less heat, chemicals, water and possibly in less time too. The overall mechanical action delivered to the tank wall is dictated by the energy transferred from the pump to the wall.

The true cost of water, both in environmental impact and in fiscal terms, is often under appreciated

The Orbitor ECO Fast Cycle Jet Cleaner (left)

The more efficiently the energy from the pump is transferred to the wall, the greater the mechanical action component. Nozzle/tank cleaner selection has a

significant effect on the efficiency of this energy transfer process. With simple spray balls and spinners the motion of the liquid between the tank cleaning device and the wall is highly turbulent and dissipated. This has the advantage of spreading out the liquid to cover a wider area but means losing most of the energy available to generate mechanical action. Both these styles of tank cleaner have

poor mechanical action. Somewhat counter intuitively, increasing

the fluid pressure does not help. Anything much above 2.5 bar fluid pressure supplying spray balls or spinning spray balls is will simply atomise the fluid more and the extra energy will not translate to additional mechanical action.

ROTARY JET CLEANERS The type of tank cleaning heads that can improve mechanical action are rotary jet cleaners. These produce laminar flow jets which deliver high impact cleaning to each part of the tank as they move through their cleaning cycle. The laminar jet is the key to delivering as much energy as possible from the pump to the tank wall. With this style of cleaner, increasing fluid pressure at the pump means more energy does make it to the tank wall, rather than being wasted in generating chaotic and turbulent flow. The advanced nozzles on these

machines mean the fluid stays as a coherent jet for many metres at pressures in excess of 10 bar and increasing


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