Upgrade to PC control system raises accuracy
Upgrade to PC control system raises accuracy
Cariers PC-based computer
control panel monitors,
interprets and controls
grain driers automatically.
Andy Moore takes a look
at this hi-tech system
CARIER now supplies its NC Continuous Flow driers with an upgraded computer control system.
This, says Carier, enables grain to be dried to previously unobtainable accuracy, which should help producers reap maximum returns from a higher quality crop.
Developed over six months with software companies, Carier believes its new PC operated system could revolutionise the way grain driers are controlled. The key to the system is the "intelligent" control software, which is fed from sensors fitted in the body of the drier and regulates the primary operating functions.
The main sensors monitor heated air and outgoing air temperature plus grain levels in the drying column and discharge hopper. They feed back information to the control software in the panel which runs the main drier functions, including heat output and discharge rate.
The PC works with Cariers PLC control system already fitted to its driers to operate main drying functions, which are displayed and monitored on the built-in 17in screen using Windows-based software and a touch pad.
Before the drier is fired up, the wet grain moisture figure is entered into the computer along with target moisture level and crop type.
"The computer suggests an appropriate ingoing air temperature and a discharge rate from its database to achieve the required moisture content for the selected crop," says Cariers Bill Lewis.
"Depending on crop type, the computer energises the number of burners to give the ingoing hot air temperature required. The amount of time before the top level of grain has passed through the drier and is ready to be sampled is then displayed."
This will vary according to inputs and the driers capacity – the NC range covers throughputs from 14.5t/hour to 84t/hour.
When checking output moisture, the operator can tweak the original settings chosen by the computer. Once grain is coming out at the right moisture target, the system is switched to automatic mode.
This, says Mr Lewis, is when the magic starts. "We know if the moisture content of the ingoing grain starts to change this will result in a variation to the exhaust air temperature. The computer, therefore, adjusts the discharge rate to maintain the set temperature and thereby the required output moisture."
The computer maintains the "air off" temperature by varying the discharge rate to achieve the target moisture content.
If the incoming moisture content starts to drop, the grain passes through the drier more quickly. That reduction in moisture level results in an increase to the exhaust air temperature, which the sensor notes. As a result, the control system gradually increases the discharge rate of the drier until this temperature is back to its set value. The system can be set to remove as much as 10-15% moisture from feed grains and maize in one pass.
Mr Lewis says it reduces both energy costs and the risk of over-drying grain. "If a grower over-dries 500t of grain by 1%, 5t of grain is lost in evaporation. This costs the producer £400.
"With more accurate control, the grower may also avoid penalties by selling higher quality seed or milling grain which may be damaged by overheating.
"And because drying data can be recorded and printed off, the system can ensure grain meets traceablity standards, which are being increasingly demanded throughout the food chain," says Mr Lewis. "The stored information could also be recalled from the database to keep drying procedures constant."
A sophisticated alarm system with full diagnostics is another benefit of the process control software. And for those wanting to get really clever, the drier can even be operated and monitored remotely from a farmhouse kitchen or office via a modem. *