Tony Goodman Systems Consulting Ltd.
Tony Goodman
Tekmi Tunnel Pasteuriser
This was an old unit with no documentation, designed in an era where utility costs were far less significant than today.
Further, due to staff changeover no-one on the site understood how it was actually supposed to work.
The Client asked to investigate why water usage was 950 hl/day (30 hl/hr) with consequent steam, chemical and effluent costs.
The investigation required a basic diagram to be created to allow the functionality to be revealed.
 
Investigation
The investigation revealed some interesting facts:
- In Standby mode the shared small Pasteurisation/Heating & Cooling baths were continually overflowing to drain
- The Reclaim Tank was Isolated from the return route because it was overflowing to the floor in the above state
- The Preheat Bath temperature control loops were constantly hunting between steam and fresh water addition
 
After studying the design, reading the control software and undertaking some control tests it was established that:
- In Standby mode certain valve seals were so degraded that there was continual flow when "shut" leading to the overflows
- Remedying this allowed the Reclaim Tank to be recommissioned
- The cooling water on the Preheat baths temperature controls was isolated to prevent the control hunting   
- Current constant steam pressure of 6 bar was modified so that after initial start-up and warming it reduced to 3.5 bar to give more controllable heated during the "balanced" production phase - which removed the need for cooling water
 
The only remaining reason the cold water is needed is during "run-out" when the heat content of the bottles needs to be removed as the last bottles exit the pasteuriser. This function was replaced by using the top-up function from the Reclaim Tank.
So why was this not always the case? One can only surmise that in some climates it might be necessary but the when the machine was designed utility usage was simply not a consideration.
The end result:
Water consumption fell from 30 hl/hr to 6 hl/hr with no product issues.
For the future a recommendation was made to remove the water control valves and fit steam isolation ball valves to prevent further wastage from water and steam passing when the control valves were at 0%.