In mechanical process technology, even virtually identical products behave differently when being processed. Upstream tests in our technical center serve to qualify bulk solids processes as well as to optimize the configuration of the production process and throughput capacities. Here, process parameters are optimized in machines and systems made to scale for use in later production in life-size systems.
A broad range of screening machines and big bag systems with corresponding dosing and filling equipment facilitate the simulation of various applications in order to produce the corresponding sample products and to test the desired results. At our customers’ request, we can also conduct the experiments together with them.
Technical trials are particularly useful if there is no, or very little, experience with the product being processed to fall back on, as the choice of the right machine will be determined by the product properties. These properties include the bulk weight of the product and variety of grain sizes, flow properties, the moisture content or whether the product is abrasive, caking, dust-forming or fatty.
Optimal machine setup
Which version of the machine and which machine setup will give the best results and to what extent additional features are required, can often be determined by carrying out a technical trial first. In order to achieve the full performance potential of a machine, it must be possible to produce and compare different machine configurations as part of the trials. With the testing of screening processes, such parameters are, for example, the vibration amplitude (for vibration screening machines) or the stroke (for jigger screening machines), the screen angle and the different ways of cleaning the screen mesh.
Predetermined throughput rate
An important requirement when processing bulk solids, and therefore one objective of technical trials, is the achievement of a predefined throughput rate. Bulk solid processing machines are usually part of complex production lines and are integrated into the upstream and downstream manufacturing processes. When carrying out trials, it is important to test the extent to which the predetermined production volume can be processed by the machine being tested. With screening machines it is also about determining the optimal machine size, screening surface and screening settings to attain the required screening performance.
Customers should provide the exact same product for the trials as they will be using in their operation, as each bulk solid has its own specifications. The specific properties of the material also vary between almost identical products, although this is often not apparent at first sight.
Ideally a similar product quantity will be used for trials as would be used in the real operation. If this is not possible, then the trials can also be carried out on a smaller scale and the suitable machine size can be calculated via a scaled-up process. Multiple use of the products is only possible, if their properties do not change through mechanical stress during the trials. If this is the case, then the quantity of the products made available must be much greater so that several trials can still be carried out.
Alongside determining the throughput rate, there are also further objectives that should be clearly defined – e.g. the quality of the solids used in the trial. With screening technology trials the quality of the products is determined, for example, through the selectivity of the screening process, viz. how precisely the material that is screened is separated into different grain sizes. An important aspect in terms of quality (especially with delicate products) is, to what extent the product can be damaged through the procedural process. Small fragments increase the percentage of dust in the product, whereby it can no longer be ideally processed in the later stages of production. Clearly defined limit values for fine particles provide clarification.
The most important parameters in terms of the description of the production environment are: hygiene and safety guidelines, temperature and atmospheric humidity, available floor space and whether the installation location is an ATEX Protection Zone. The more information provided in the run-up to the trials, the better the trial setup can be planned by taking these requirements into consideration.
Sampling and Analysis
Before the beginning of the trial, the bulk solid should be analyzed so that a suitable machine and machine setup for the properties of the product can be selected. Materials for trials that are delivered in large containers, such as big bags, are prone to separation because of how they are transported. Therefore, only special sampling equipment such as a zone sampler, which takes a representative quantity of product from each layer in the storage container, should be used.
If further partial samples are required from the collected material, their composition must correspond exactly to the total quantity. With the aid of rotary dividers, the material can be divided equally between several test tubes. A representative bulk solid analysis is only possible after this test preparation.
Simulation of the real operation
A trial setup is particularly good, if the operating and process requirements of the operator are reconstructed as accurately as possible.
For example, with screening machines it is important that the machines used in the trial setup are fed with material in the same way as they would be during the real operation. Upstream conveyer units and also the angle of repose at which the material is loaded into the machine are important aspects. These determine the type of machine, specific settings or if there is a need for additional equipment. The more flexible the technical center is with regards to the test machines and additional equipment available, the more comprehensive the possibilities to reconstruct and compare different processes.
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