Fruitmasters stores around 9 million kilos of top, soft and stonefruit under DCA conditions in the cooling houses. For each new fruit variety, even for each part, the optimal conditions must be created. Aspects such as the ripeness during harvest, the (micro)climate in the orchard and the fruit size all influence the shelf life. There is therefore no standard recipe for optimal storage. There must be constant monitoring, measuring and adjustments.
Frequent gas analysis
Three ULO measuring stations are adapted into Fruitmasters' cooling houses. The gas analysis for 20 storage cells takes place through measuring tubes. The regulation measures the conditions in a cell very frequently and notifies the user if there are any deviations from the set value points.
Nijssen's control system regulates all the functions of the cooling installation. All ULO components in the installation are also integrated into the set-up. Gas measurements are carried out and the set up to control the aeration, CO2 scrubbers and the nitrogen generator. Every cooling cell can be controlled individually or as part of a group.
Large amounts of data traffic
"The data management was one of the challenges for this set up," according to technical engineer Edwin Snabel of Nijssen. "Monitoring the conditions in all cooling cells generates a huge amount of data - especially in the large scale environment of Fruitmasters. Smart solutions for data traffic have been applied in the software. This means the system can control and respond quickly and efficiently."
Quicker response to deviation
"Because we now measure and register more, we can respond to deviations quicker," says Harry Beelen, cool house manager at Fruitmasters. "It is also now simpler to interpret tendencies in the storage process."
Automatically adjusting positions
If desired the intelligent system adapts the storage conditions automatically, based on decision rules defined by the user. "We are still working on further automating the controls," says Leon Lommerse, senior automation consultant at Nijssen. "So that the system automatically moves to a certain action when it measures certain values in temperature, oxygen, CO2 and air humidity. Of course the user always chooses what they will let go either manually or completely automatically."
Quick set up based on recipes
With around 350 settings and measurement per cooling cell, custom control threatens to be a huge task. The control therefore offers the opportunity to capture the basic conditions and for each variety and set a basic recipes for the different phases in storage. Through user friendly menus adjustment is possible on all parameters. The basic recipes are stored on the control computer, so that unlimited recipes can be defined.
All actions, alarms and log data are stored by the system and can easily be recovered for analysis. Detailed oversight and graphs give insight into the conditions in every cooling cell. Of course, all information can also be printed and exported. A full report of each party is available. "It is important for us to be able to capture the cooling process accurately," says Harry Beelen. "With around 50 million kilos of fruit in storage we have a big responsibility."
Queue management creates calm, energy efficient process
Besides safeguarding optimal storage condition, an efficient use of energy in the installation is also important. The use can be greatly limited by choosing energy efficient components. But the control is also of great influence. The advanced queue management cases a lower energy use and calm in the installation. The cold supply is optimally spread through a prioritisation of the cool demand from the storage cells. This calm in the installation also benefits the climate in the cells - a win-win situation.
Newest hardware and development surroundings
For the standard version of the self developed control system, Nijssen uses Hitachi with Codesys runtime. Fruitmasters chose Siemens PLC's (S7-1500 and S7-1200) and the Siemens TIA Portal development surroundings. The Siemens OPC-server takes care of the communication between the PLCs and the user friendly visualisation. "All knowledge stored in the Codesys surroundings was worked out again in the Siemens surroundings," says Leon Lommerse. "Not just the new DCA set up, but also the rest of the control was also converted."
When developing the new control system use was made of the expertise of Frank van de Geijn, consultant Post Harvest Technology at Wageningen UR. Harry Beelen was also closely involved. "I am very satisfied," indicated Harry Beelen. "Nijssen has more than kept its promise. Based on our specifications they built a completely new software packaged in 14 weeks, tested it and used. Plus; the system works better than expected! A great performance, especially with the size of this project."
More information on the DCA control? Nijssen will be present at the Growers' Day at Fruitmasters on Wednesday 9 December, as well as at the Fruitteelt Vakbeurs (20-21 January 2016 in Houten).