Sugar is like a fine grit material and can be fairly abrasive against soft parts of equipment in a conveying line. However, if the right kind of products and equipment are used correctly, with the right amount of pressure according to the application, this abrasion issue can be rectified.
Pneumatic Conveying Sugar Application Details
A large confectionary company came to AKO UK with a sugar line application enquiry, where the sugar is being pneumatically conveyed and taking a large toll on any soft parts in the line. The company were currently using a butterfly valve with soft seats which were wearing out quickly and were quite expensive to replace, combined with a long lead time for the spares.
The company were using a discharge valve on each receiving hopper, which are charged to 2.0 Bar and the sugar is then transferred through around 60,000kg across the 2 pots intake and around 40,000kg on the internal dense phase conveying system.
Four of the butterfly valves were fitted in total, lasting a maximum of 12 weeks or so, and so the issue was the inconvenient downtime that was caused by having to wait for replacement parts and changing the valves out frequently. The butterfly valves were also giving the company a lot of issues with finds in their sieves weekly.
A further issue inside the hoppers with the sugar building up around the insides was causing a restricted flow and even more downtime when the hoppers had to be scraped out using a rod from the inside.
Replacement Valve Solution
AKO supplied a pneumatic Pinch Valve with FDA approved food quality natural rubber sleeves to replace the butterfly valves within this abrasive sugar application. 2 Bar is not so high as far as line pressure goes, but to reduce the abrasion even further, it was advised that the line pressure was reduced and the company now convey the sugar through their lines at 1 Bar which has already seen significantly longer lifetimes in the rubber sleeves inside the Pinch Valve, compared to the soft seat on the butterfly valves. Natural Rubber is one of the best materials for handling abrasive media.
For better flexibility of the rubber sleeve, AKO also advised that the sleeve should be kept normally open rather than closed. If the bladder inside the valve had to be kept normally closed against no line pressure, then AKO advised to use 2 Bar maximum to fully close the sleeve/bladder.
Clogged Hopper Solution
With regards to the sugar becoming sticky due to temperature changes and building up unwanted areas of product that was restricting the flow, AKO supplied four white food quality Aerator Pads per hopper to help with this. The aerator pads give off a slight aeration/vibration when air is applied to them, allowing any trapped media around them to loosen and shake free, back down into the product flow.
So far, the confectionary company have been using aerator pads on their sugar hoppers for 4 weeks and have noticed dramatic improvements with no more rat holing issues.