K-Patents SeedMaster 2 - Manual (Page 43)

7 CONFIGURE SeedMaster 2 43
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7.4 THIRD INPUT
MAIN DATA INPUT REQUIREMENTS.
SeedMaster 2 relies on the use of on-line process data.
Besides the two obligatory data:
• syrup / mother liquor concentration measured by the refractometer, and
• massecuite temperature
it is advised to use a third on-line input, too.
The primary source of this input may be a standard current transmitter measuring
• massecuite density, or
• massecuite solids content, or
• stirrer motor current or power consumption (power is preferred).
As a last resort (if none of the above is available):
• a single data on crystal content of the massecuite (% by volume) at the end of the strike
determined by the local laboratory can also be used.
On-line data from anyone of the above 3 transmitters are preferred.
Standard current transmitters can be connected directly to SeedMaster 2 using one of its analog input
channels, or to a Process Control System (PCS). In this case measured data can be transmitted to
SeedMaster 2 from the PCS via digital data communication.
OPTIONAL DATA INPUT REQUIREMENT: massecuite level.
Handling the use of different feed syrup purities in the same batch strike.
In some cases feed syrup purity is not constant during a batch strike. The strike is started with a feed syrup
having purity P1, then later on it is continued with an other (P2), and may be it is finished with the last one
(P3), where purities are gradually decreasing (P1 > P2 > P3). In practice the change from one feed syrup to
the next one is carried out when level in the pan reaches some selected limit value. This can be based on
real measured (on-line) data, or if it is not available, on the visual observation of the pan operator. The actual
change of the feed syrup (operating the feed valves) can be implemented either by a PCS, or by the pan
operator.
Supersaturation, the most important parameter of crystallization depends on syrup / mother liquor purity,
therefore changing feed syrup purity should be taken into account.
SeedMaster 2 is prepared to handle the situation in different ways, and, as a result, with different
sophistication depending on the availability of the on-line measurement of massecuite level. It is therefore
important to provide information during configuration on the availability of on-line level data.
If available, level data are used in other calculations as well.
During configuration of THIRD INPUT a question on level measurement (LEVEL MEAS. YES / NO) has to
be answered and the type of input selected (in SET UP INPUTS). If the answer was NO, then instead of
LEVEL data CR. SIZE (mean size) will be displayed on the MAIN DISPLAY.
When on-line level data are in use, information on mean crystal size is still available: go to Display -> Trend
and select CRYSTAL SIZE.
7.4.1 Third input: MASSECUITE DENSITY or MASSECUITE SOLIDS CONTENT
Fig. 7.6 shows “Third input” configuration, when MASSECUITE DENSITY and SENSOR CALIBRATION
(YES) were selected.