Batching

Batch weighing involves sequentially or simultaneously adding ingredients into a vessel by weight and then discharging the batch (sum of all the ingredients) to downstream processors.

The vessel can be a simple hopper or tank, and could contain a built-in mixer, and agitator, or heating and cooling device. Ingredients are conveyed, extruded, vibrated, pumped, hand-delivered, or gravity-fed to gates or valves above the vessel.

Sequential Batching

Sequential batch control is a "gain-in-weight" application where multiple ingredients are added one at a time into a single weigh hopper mounted on, or suspended by one or more load points (load cells and mounting hardware). Hardy's controllers open and close the dispensing gates or valves while weighing the addition of the ingredients. They also open and close the discharge gate or valve of the weigh vessel for total or incremental discharge of the batch contents.

Simultaneous Batching

Simultaneous batch control is a "loss-of-weight" application where multiple ingredients are added to a single vessel at the same time. Hardy controllers dispense ingredients from weigh hoppers and/or feeders. They open and close the dispensing gates or valves of weigh hoppers that are mounted on, or suspended by, one or more load points (load cells and mounting hardware); control the rate of flow of material through feeders on platform scales; open and close the discharge gate or valve of the vessel for total discharge of the batch contents.

Instrumentation and Control

Instrumentation ranges from batch and weight controllers to rate controllers. They can be stand-alone systems or connected to host computers or programmable logic controllers (PLCs). Hardy's batch controller can be run in automatic, semi-automatic, manual or a combination of all three modes Automatic controllers operate gates, valves, feeders and pumps as well as downstream mixers and metered liquids. They automatically tare the net weight and then go to the next ingredient to be batched. Semiautomatic and manual controllers operate gates, valves, feeders, and pumps. The operator must manually re-start the process for each ingredient or sequence. A switch is used on controllers that support automatic, semiautomatic and manual modes to select the desired level of control.

Ingredients and Formulas/Recipes

A batch can consist of single or multiple ingredients in one of more formulas/recipes. Single ingredient batching consists of repeatedly weighing and discharging one ingredient. In multiple ingredient batching, two or more ingredients are weighed either sequentially or simultaneously for a specific formula or recipe Ingredients can range from granular, powder, bulk and dry material to liquids. Some ingredient amounts are so small that they can't be accurately weighed in the same hopper as a major ingredient. Hardy's instruments can pre-weigh these minor ingredients and then automatically feed the material in to the main batch hopper or hold the batch process to allow for material to be added in by hand. In the case of liquids, Hardy's batch controller can meter the material into the weigh hopper. Hardy controllers fit any batch application, from those needing only one formula/recipe, to those utilizing over 250 formulas/recipes, depending on the number of functions in the batch cycle. If a computer or PLC is used to download the formulas/recipes, the number is endless. Formulas/recipes are stored in memory for easy access to authorized operators and to protect against loss of data.

Accuracy (Preact/Jog/Tolerance)

Hardy's batch controllers perform a number of actions to accurately weigh each ingredient of a formula/recipe. First it energizes the proper relay, allowing the gate or valve of the selected material to open. It then de-energizes the relay before the desired weight is reached to compensate for the material that is still in flight. The difference between the relay cutoff weight and the desired weight is known as preact. This early cutoff allows for material ("in-flight") that is past the gate but not yet in the weigh hopper. Hardy's batch controller is equipped with a self-adjusting preact that can evaluate the difference between the desired weight and the actual weight delivered. This value is automatically adjusted to arrive at a more accurate cut-off the next time around. Automatic preact is very important when working with materials whose density changes throughout the day.

For example, molasses will flow faster in the middle of a warm day than in the middle of a cool night. Hardy's batch controller provides separate and non-interacting preact values for each ingredient to arrive at accurate weighments. Individual tolerance values for each ingredient can be set in our batch controller for better control and accuracy. Alarms can be energized and the operator prompted with a display if an ingredient weight is over tolerance. The operator will have the ability to override the error or abort the batch. If the ingredient weight is under the tolerance, the ingredient feed will "jog" on and off to bump more material into the weigh hopper until the weight is within tolerance. Jog on and jog off times are selectable by the operator. All operator actions can be recorded and printed out on reports.

Speed

Accuracy of filling and dispensing is increased even more with the dual speed capabilities of Hardy's controllers. A fast or bulk speed is used for the majority of the process cycle, where valves or gates are wide open to allow maximum flow, and a slow or dribble speed is used for a short duration at the end of a cycle, where the valves or gates are nearly closed. The slow or dribble speed allows for a higher accuracy of hitting the final desired weight without under or overshooting it. As with a gas station pump, most of the material is dispensed quickly and the last is dribbled in to allow the controller to accurately cut off the flow.

Alarms/Interlocks

When the batch controller has energized an ingredient feed output and there is a problem, such as the gate or valve will not open or there is no more ingredient available, the operator will be notified by an alarm based on time. If this timer finished timing and the ingredient is not done weighing, the slow feed alarm will sound. Interlocks are often required to allow the batch controller to receive an input before proceeding with the batch process. These inputs can be from a variety of devices from a discharge gate, pneumatic conveying system, or a cooker. A signal should be present to tell the controller that the vessel's discharge gate is closed before allowing the process to start or continue. It may be necessary for the pressure on a pneumatic conveying system to reach a set point before the batch controller calls for the next ingredient. A food, chemical or textile application may require two ingredients to be weighed and then cooked until a certain temperature is reached before additional ingredients are introduced. Hardy's flexible batch controller allows the user to program a sequence step to look for an external input or to wait for a manual operator input before proceeding. This interlocking capability allows a stand-alone batch controller to interface with a variety of process equipment.

Once the ingredients have been weighed according to the formula or recipe, the batch is discharged. An interlock allows the Hardy batch controller to sample an input signal to determine if it is okay to discharge the batch. This interlock can be controller from a system controller, downstream equipment or wired to manual controls. Once the "Okay-to-discharge" input is received, the controller provides the output to open the discharge gate or valve. Most applications require that the full batch be discharged from the weigh vessel. Hardy's batch controller verifies that the vessel is empty by holding the discharge gate open while monitoring the loss-in-weight. When motion is no longer detected and the scale is within its zero tolerance, the discharge gate is closed. Material can also be dispensed from the weigh vessel by multiple, equal discharges.

Data Management-Inventory/Batch/Formula Reports

Reports can be very useful in batch operations to keep track of inventory, batches and formulas or recipes. Hardy's batch controller has the ability to print out these three different reports. The batch report records the date and time, batch number, which ingredients were processed, how much ingredient was ordered, and how much formula/recipe was actually produced. The inventory report shows how much of each ingredient has been used, how much is available, and how much of each formula/recipe was made. The formula/recipe report shows what ingredients make up the formula and how much of each ingredient is needed for any selected formula/recipe at any time.

WAVERSAVER®, Ignores Vibration

Equipment like line conveyors, augers and mixers in batching operations can cause plant and process vibration. Hardy's WAVERSAVER® technology ignores unwanted vibration signals to provide quick and accurate weight readings. Even mixers can be weighed while they're running!

Calibration Made Easy

Hardy's C2®, Second Generation Calibration eliminates costly scale calibration fees associated with batching systems. C2 allows you to electronically calibrate without test weights, even with material in your vessel. The C2 system consists of Hardy C2-certified load points, weight controllers, junction boxes, and cabling to make scale calibration easier than ever before. Each C2 certified load point contains digital information detailing its unique performance characteristics. The C2 system uses these characteristics to electronically calibrate the scale. When power is applied, the weight controller automatically searches for C2 certified load points and saves the data to memory. The operator enters a reference point and the scale is fully calibrated.

The C2 system reduces downtime for installation and repairs, and eliminates test weight related injuries. In addition, it ends material substitution headaches.

Data Security

Non-volatile memory stores ingredient and formula/recipe data. It also stores the individual preact and jog information for each ingredient. Hardy's Secure Memory Module automatically stores and protects critical data including calibration, setup and operating parameters. If the instrument ever needs replacement, the Secure Memory Module can be transferred to another controller and all critical data is restored, making your batching system operational within minutes.