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Continuous Control Versus Batch Control |
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Continuous Control Versus Batch Control
Batch Control - As the name would indicate a blender designed with batch control makes
batches. Each component is metered in one at a time into a scale. After all the components have
been added the scale is dumped into a mechanical type mixer. The batch is then mixed for a time
and the cycle is repeated.
Continuous Control - A blender designed with continuous control weighs each bin
individually. The components are metered in simultaneously in the correct proportions. With
continuous control the blend is achieved without the need of a mechanical mixer. A blender that
uses continuous technology constantly does rate checks and makes speed adjustments to
maintain the correct proportions.
 Advantages of Continuous Control over Batch Control. Following is a list of
the advantages that using continuous control offers over batch control:
1. Accuracy. CRG Logics, Inc. incorporates PID loops in the continuous control
algorithms. This allows the system to constantly check and adjust speeds to maintain
exact blend ratios. The longer a continuous blender runs the more accurate it is.
Accuracies of better than 0.1% are easily achieved with a continuous blender.
2. Simplicity. A continuous blender is easier to operate than a batch blender. The blender
can be started and stopped at any given instant. A batch blender must finish its batch
before being stopped. If it is stopped in the middle of a batch, that batch will not be
accurate and usually needs to be thrown away.
3. Variation. With a continuous blender, upsets in the process are easily filtered and will
not cause drastic changes in the blend (example; Bumping of a scale). If a scale were
bumped during a batch, with a batch blender, the results of that particular batch would
be extremely inaccurate. This could lead to upsets in a process that could give way to
poor bubble/web stability and/or out of spec material.
4. Maintenance. The CRG Logics, Inc. continuous blender has no moving parts. This gives
way to far less maintenance and breakdowns of the equipment.
5. Cost of ownership. Due to reduction in maintenance costs and improved accuracies the
cost of ownership of a CRG Logics, Inc. continuous blender is far less than any other
blender on the market today.
6. Lower % on additives. With smaller batch blenders the load cells decrease in size
substantially and are rated in grams as opposed to pounds. When adding a minor
ingredient of .5% to a 2000-gram batch, the weight becomes so minuet it is impossible to
control. A continuous blender controls by rate, so a larger sample can be taken. This
allows accurate control down to substantially lower rates than a batch blender.
7. Higher rates. Batch blenders meter each component one at a time. Continuous blenders
meter all the components simultaneously allowing much higher rates than batch
blenders. Some batch blenders will meter all the components simultaneously on some of
the batches to speed the system up. This is very dangerous because these batches are not
weighed. This results in inaccurate inventory numbers and inaccurate batches.
8. Instantaneous rate information. Instantaneous throughputs of the system or any of its
individual components are displayed. This is not possible with an averaging batch type
system.
Advantages of Batch Control over Continuous Control. Following is a list of
the advantages that using batch control offers over continuous control:
1. Initial Cost. The initial cost of a batch blender is typically less than a continuous
blender.
2. Calibration. With a continuous blender each component is weighed. With a batch
blender there is only one scale. Therefore calibrating a batch blender is a little bit
quicker.
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