Let us spray

The process industries are continually looking for new ways to achieve higher throughputs, superior process efficiency and better product quality.

Mostly, they look to achieve these aims by improving the equipment that they use for the job of processing. Or, by altering the way they organise each stage of the process; switching, for example, from continuous to batchwise production so that they have more flexibility to respond to the market.

It is only rarely that most companies look at peripherals such as cleaning-in-place (CIP) as a way of improving productivity, rather than simply meeting self-imposed and legislated hygiene requirements. However this is definitely an area in which improved cleaning and sterilising can be reflected in better performance and profitability. Particularly when it comes to the tanks, silos and other storage vessels on which so many processes depend.

Properly planned and executed, tank cleaning does more than bring tanks back to their specified hygiene level. It can also improve process performance, slash consumption of water, energy and chemicals. Consequently, it boosts profitability.

Alfa Laval’s Toftejorg tank cleaning systems are among the most advanced available today, and are in use across the process industries around the globe. In the brewery sector, Toftejorg rotary cleaning machines are used from the brew house to the bright beer tanks as an essential part of the CIP process. The same is increasingly true in the wine and soft drinks sectors.

In the food industry, rotary cleaners remove burnt food residues and biofilm and clean tanks equipped with agitators or baffles. In both the pharmaceutical and personal care markets, Toftejorg products meet the hygienic standards of the FDA, EHEDG and other approval authorities and are suitable for a wide range of viscous, foaming and thixotropic products.

However, it is in the dairy sector that many of the toughest cleaning/sterilising challenges are to be found. Rotary heads are used to clean milk, cheese and yoghurt storage vessels using either permanent or retractable systems.

Dairies are facing unprecedented pressure in terms of environmental issues and profit. The market, in the shape of the large supermarket chains, squeezes profitability from one direction while new environmental initiatives do the same from the other. Consequently, anything that can improve efficiency while also reducing environmental impact must be good news.

That is where Alfa Laval’s Toftejorg Sani-Mega rotary sprayheads come in. They are ideal for the vital job of CIP of all kinds of silos and other storage vessels around the dairy. Installations both in Europe and in the UK have demonstrated the equipment’s ability to generate savings of 50% or more in pre-rinse flow rates when used to clean raw milk silos; sufficient to pay back the initial capital investment in 12 months or less.

These savings are based on the results of extended field trials at dairies with a typical throughput of several million litres of milk every week. Until fairly recently, most of these dairies cleaned their raw milk silos using conventional means such as high pressure, high speed, rotary sprayballs.

Although the configuration can, obviously, vary from dairy to dairy and tank to tank, one of the most common involves mounting two fixed sprayballs in the top dish of the tank with a third located near the bottom-mounted agitators. Conventional spray ball installations operate at high speeds (250 rpm) under applied water pressure and use a straightforward deluging action to clean the silo interior.

In a typical CIP process a dairy pumps up to 40 000 litres/hr of liquid through the CIP system. If it performs 25 raw milk silo CIP operations every week and uses approximately 16 000 litres of fresh water for each operation, its total consumption is close to 400 000 litres per week. This could add up to an annual water effluent charge of £50 000 or more.

The difference in performance and efficiency when conventional sprayballs are replaced by Toftejorg Sani-Mega sprayheads is dramatic. In contrast with the deluging action of the high-speed sprayballs, Alfa Laval’s Toftejorg Sani-Mega operates at low speeds (5rpm) and cleans through impingement and high levels of turbulence.

The system scrubs the silo’s sides with fan-shaped jets that cascade down the walls to produce a vortex action once they reach the silo bottom and outlet. An internal turbine and gear system enables the cleaning process to be controlled with great accuracy while the option of a unique feedback system enables the whole process to be repeated and recorded indefinitely.

While a typical sprayball would use 5500 litres of fresh water for each CIP cycle, the Sani-Mega unit almost halves the required volume , to around 2700 litre/hr.

It also does the same with energy costs. For optimum CIP efficiency, the silo walls must be heated to 70 degrees C. The fan-shaped spray provided by the Sani-Mega transfers heat to the internal skin more rapidly. Consequently, the silo attains optimum temperature just as fast as with a sprayball and, frequently, even quicker.

Based on these cost and efficiency gains, it is reasonably easy to calculate the savings provided by reductions in extras such as annual effluent disposal costs and then to set these against the original capital cost of replacing sprayballs with the Toftejorg sprayheads. On average, this worked out at 10-12 months depending on the number of silos and the local legislation governing white water disposal.

Now, it isn’t even necessary to install a rotary cleaning machine to see if it will work. Alfa Laval has developed software called TRAX, which makes it possible to simulate the tank conditions and the performance of the machine in terms of detergent distribution and wetting intensity. The optimum configuration can be determined before the equipment is installed, saving even more time and money.

Peter Rose is marketing manager for Alfa Laval in the UK.