K-Patents SeedMaster 2 - Manual (Page 45)

7 CONFIGURE SeedMaster 2 45
45
Third input: MASSECUITE SOLIDS CONTENT
Parameters:
Remarks:
SEED CRYSTAL SIZE Mean crystal size data is required (mm)
PRODUCT CRYSTAL SIZE Mean crystal size data is required (mm).
CR. CONT. (LAB, STR. END) Crystal content by the lab at the end of strike (% by volume).
LEVEL MEAS. YES / NO
LENGTH OF CRYST. TIME Time from seeding till end of strike (min). Only if previous answer was NO.
CONC. (REFR., SEED) Concentration (refr.) in the seeding point (%).
MA. SOL. (LAB, STR. END) Massecuite solids content measured by the lab at the end of strike (%).
MA. SOL. (SEED.) Massecuite solids content measured by the solids content measuring
instrument in the seeding point (%).
MA. SOL. (STR. END) Massecuite solids content measured by the solids content measuring
instrument at the end of strike (%).
NOTE:
If the answer to LEVEL MEAS. was YES, PAN MAX. LEVEL (%) will replace LENGTH OF CRYST. TIME.
7.4.2 Third input: MOTOR CONSUMPTION
PRINCIPLE OF OPERATION
Using the current or power consumption (power is preferred) as “Third input” for SeedMaster 2 offers the
least expensive solution, because only an inexpensive (probably already existing) current or power
transmitter is required.
The current or power consumption of a motor driving the stirrer in a vacuum pan depends on the viscosity /
consistency of the syrup or massecuite.
Viscosity is the property of a liquid (in this case: sugar syrup, or mother liquor), characterized by the force
acting against movement depending on the solution concentration and temperature.
Consistency is the property similar to viscosity of a mixture of a liquid and solid particles (in this case:
massecuite), depending again on solution concentration, temperature and solids (in this case: crystal)
content.
When crystal content is low, consistency barely exceeds the viscosity of the surrounding mother liquor.
Increasing crystal content, however, increases massecuite consistency, which exceeds several times liquid
viscosity. The consistency over viscosity ratio at the end of a strike can increase up to 25-30. This proves the
statement that as crystallization proceeds, the output of a consistency probe used in sugar crystallization
control is governed more and more by increasing crystal content.
The trend of motor power consumption versus time in Fig. 7.7 shows the change of viscosity (up to point 1)
and consistency (from point 1 to pan discharge) as reflected in motor power consumption. In the figure:
0
Start of strike (motor switched ON)
1 Seeding
2 Crystal content is about 20-25 (% by volume), (PHASE 1 END)
3 Crystal content is about 32-36 (% by volume)
4 End of strike (motor switched OFF)
P (kW) P (kW)
PHASE 1 END PHASE 1 END
PHASE 1 PHASE 1
0 1 2 3 4 Time 0 1 2 3 4 Time
a) b)
Fig. 7.7 Typical trends of single-speed motors
In Fig. 7.7 a) motor power from point 0 to 1 (the time needed to concentrate the syrup for seeding) is
characterized by only a small increase in motor power. From point 1 to 2 crystal content increases to about
20-25 %. It is reflected in very slowly increasing power consumption. Between points 2 and 3 crystal growth
begins to increase more rapidly, faithfully reflected in the power consumption. Finally, from point 3 crystal