Our options in material transfer and batching systems are designed for optimal ingredient addition to various processes.
Coperion K-Tron’s batching systems are available in a variety of configurations dependent upon the accuracy requirements. After transfer from the material source, the ingredients are usually delivered to the batching station. This station can include volumetric metering devices, such as screw feeders or valves, which deliver the product to a hopper on load cells. This method is called Gain-in-Weight (GIW) batching. Alternatively, the station can include gravimetric feeding devices, such as screw or vibratory feeders, mounted on load cells or scales, which deliver the product to the process by means of Loss-in-Weight (LIW) feeding. In some cases where small amounts of micro ingredients are required for a total overall batch, both methods are employed: LIW feeders for the micros and minors, and GIW batchers for the major ingredients.
Gain-in-Weight-batching principle
In GIW batching volumetric metering devices sequentially feed multiple ingredients into a collection hopper mounted on load cells. Each feeder delivers approximately 90% of the ingredient weight at high speed, slowing down towards the end of the cycle to deliver the last 10% at a reduced rate to ensure higher accuracy. The GIW controller monitors the weight of each ingredient and signals each volumetric feeder to start, increase or reduce speed, or stop accordingly. Once all the ingredients have been delivered, the batch is complete and the mixture is discharged into the process below. It should be noted that this type of batching method is sequential for each ingredient, and therefore generally results in a longer overall batching time than with LIW batching if the number of ingredients is high.
Loss-In-Weight-batching principle
LIW batching is used when the accuracy of individual ingredient weights in the completed batch is critical or when the batch cycle times need to be very short. Gravimetric feeders operating in batch mode simultaneously feed multiple ingredients into a collection hopper. Adjustment of the delivery speed (on/off, fast/slow) lies with the LIW feeder controls and the smaller weighing systems deliver highly accurate batches for each ingredient. Once all the ingredients have been delivered, the batch is complete and the mixture is delivered to the process below. Since all ingredients are being delivered at the same time, the overall batch time as well as further processing times downstream are greatly reduced. This method of batching is often used for micros (such as trace elements, vitamins and probiotics), due to the highly accurate requirement of their weight in the mix as well as their ingredient cost. In some cases the LIW feeder for the probiotic material can even be located within a protected enclosure or glove box, in order to ensure no contamination from the environment and a completely contained delivery of the ingredient to the process below.
Multi destination majors batching
When major ingredient batching requires a single ingredient to be delivered to multiple or multiple ingredients delivered to a single destination, scale hoppers with specialty Aeropass™ valves mounted above the scale hopper can be used. After the material is discharged from a source such as a silo or bulk bag, it will typically drop through an Aerolock™ rotary valve, through a sifter (if required), and then into the conveying line. Once in the convey line, it is then transported to the Aeropass™ valve, located above a scale hopper.
Aeropass principle of operation
The Aeropass™ valve operates on a diverter type principle and is ideal for diverting material directly into a hopper from a conveying line. Due to the valve’s low-clearance height, it is ideal when requiring inline diverters in tight spaces. The valve includes an internal wafer type device which allows for the discharge of material into the hopper below when activated in the correct discharge position. When the scale hopper below indicates the batch is complete based on the weight signal, the Aeropass™ valve can be immediately shut. This allows for the transfer of the excess material in the conveying line either to the next process or scale hopper, or back into the original source. This closed loop design results in a more efficient method of product transfer with higher product yields.
Batch weighing with scale hoppers
Scale hoppers are receiving hoppers suspended on load cells for ingredient batch weighing. The material resides in the scale hopper until the precise weight and/or combination of materials is achieved. With the scale weighing system, weigh accuracies of +/- 0.5% of the full scale capacity can be expected. Once the desired weight has been achieved, the mixer then calls for material, a butterfly valve opens and the material in the scale hopper is discharged.
The transfer of the ingredient as well as the method of batching will depend on a number of parameters including the accuracy requirements as well as the ingredient characteristics. Specialty dosing stations with multiple feeders can be easily designed for the optimal in cleaning and accessibility.
