Steel Vats and Control Networks, the New Tradition in Winemaking

Wine is a very simple thing to make. Unless, of course, you own a large modern winery. In which case, the wine fermenting in the huge stainless steel vats is subject to many variables that need to be carefully monitored and controlled, foremost of which are temperature and density of the fermenting “must” (the crushed grapes).

In the early ‘90s, Dynasty Winery in China began using electronic controls for winemaking. Dynasty’s first systems were centralized control systems that used either a PC or a PLC, and breakdowns in communications were frequent. It soon became clear that these sytems weren't meeting Dynasty’s winemaking needs or standards.

These relatively new systems—less than two years old—had to be replaced. Dynasty needed another solution—fast.

When the Vine Ripens, LonWorks Ferments

In 1994, Dynasty Winery hired Rissun Corporation to design a temperature control system using a new, more reliable technology. So Rissun began developing a LonWorks®based Temperature Control System for 58 fermentation tanks in the Penglai/Shandong subsidiary of Dynasty Winery.

At two locations on each fermentation tank, temperature sensors constantly test the temperature of the fermenting must. The information from these sensors is used to determine when to operate an electromagnetic valve that supplies water for cooling. The complete system uses eight control nodes plus one PC-based host monitoring node. The control nodes are based on LonWorks TP/XF-78 control modules.

Reliability Multiplies While Cost Divides

By using LonWorks technology, not only does the reliability of the temperature control system meet Dynasty’s standard, but the cost of the control system is about two thirds of the cost of the previous temperature control system.

Moreover, it took only three months to develop the new system—atremendous time savings. In addition, the expansion and maintenance of the system became much easier. Using a PC with menu-driven software, the winery staff readily monitors the tanks and collects data from the network. In 1995, Dynasty Winery ordered two more LonWorks based temperature control systems from Rissun. One is used to control and monitor 56 fermentation tanks; nine control nodes and one host node are used. The second new system is used to control 117 fermentation tanks; sixteen control nodes and one host node are used. The networks are interfaced to the host sytem using an SLTA/2.

Besides providing temperature control, all these systems are able to compile various statistics, to print reports, draw temperature curves, and to carry out production management. Each system has a printer for writing report forms and drawing temperature curves.

The Next Step: Automatic Density Measuring

The success of the temperature measurement system was just a beginning. Next, Dynasty Winery asked Rissun to develop a LonWorks based density measurement capability for their Tianjin winery.

As part of the quality control process, the density of the grape juice must be constantly monitored. Consequently, density measurements must be taken regularly. And, until recently, density measurements during the fermentation process had to be taken manually. The big disadvantage of manually testing density is that it is very time consuming; the fermentation tanks are arranged in separate groups in a very large area, which takes time to cover. Another disadvantage is measurements are not very accurate since they tend to be somewhat subjective; there are a lot of factors that need to be interpreted correctly to produce an accurate measurement. Finally, the measurements are in anything but "real time." In the new system, the density is determined by the difference in pressure measured by two separate pressure transducers, which are mounted on a tank at a specific vertical distance. The analog pressure signals are amplified, filtered, and converted into digital signals by a Neuron Chip node. The node calculates a midvalue from the sampled values and averages the abstracted midvalues. Finally an average value is sent about 100 meters away to the monitoring station, which is connected to the same LonWorks network as the temperature sensors. The monitoring station digitally filters the averaged values and determines the density of the fermenting grape juice in the tank.

Using the Neuron Chip, Rissun was able to develop a highly accurate electronic density measurement node. The LonWorks based system makes the density measurement process more accurate and efficient. Dynasty Winery needed this system developed quickly, also. It took Rissun only four and a half months to develop the density measurement system using LonWorks technology. The quick schedule was an amazing feat since the technical requirements for this process are very tight — the accuracy of measurement must reach 0.1% FSO (full scale output). The quick development time was only one factor that made use of LonWorks technology so attractive. Development and installation costs were very low also.

The advantages LonWorks technology brought to this project are clear. The system met the expected technical specifications and goals: the accuracy of the density measurement was significantly enhanced; the system operates reliably with no defects or mistakes; finally, system expansion and maintenance can be accomplished very easily.

More Improvements in the Works
Today, Dynasty Winery is looking into added functions such as automatic level measurement within individual tanks, computing various statistics, printing additional report forms and density curves, and carrying out production management. With LonWorks technology, this can be done by the monitoring station while temperature and density nodes continue with their functions.

In modern winemaking, the advent of stainless steel vats did a lot to improve the quality levels of wine. But electronically controlling the fermentation process and density measuring is taking quality to even greater heights.

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