Development of a Representative Sampling and Sample Preparation System
The design of sampling systems for bulk material conveying equipment is highly diverse, meaning that there is rarely just one solution to a given technical challenge. However, the correct application of the standards applicable to the bulk material, the experience-based consideration of the specific material properties, and the local conditions all serve to narrow down the range of possible solutions. Decades of experience, combined with the customer’s expertise and knowledge, make it possible to develop a tailor-made system that meets the properties of the bulk material as well as the requirements of applicable standards and customer specifications.
For quality control of bulk materials purchased from suppliers, an automatic, representative and standards-compliant sampling system was to be developed. The automatic, continuous sampling of the bulk material was to be followed by appropriate sample preparation and sample collection. The customer’s specifications required compliance with international standards for mechanical sampling of the specific bulk material, as well as with additional technical customer requirements.
At the customer’s request, sampling was to be carried out in the discharge trajectory of a conveyor belt transferring material from Level 1 to Level 0. The remaining samples from each delivery unit were to be collected in separate collection containers within the sample collectors. The collection containers filled during the sampling of a delivery unit were to be changed automatically and stored for subsequent collection. In addition, the capacity of the sample collectors was to be designed so that sampling of the next delivery unit could begin immediately after sampling of the previous unit had been completed. The samples were to be collected by the customer’s operating personnel after each delivery unit had been unloaded. Excess material generated during sample preparation was to be returned to the main material flow.
The customer’s facility was an existing plant with limited space available for the intended application – a situation that is not uncommon when sampling systems are retrofitted into existing plants. In order to install the sampling system at the designated location while meeting the customer’s requirements and technical specifications, an extension of the existing steel structure was unavoidable. The challenge was therefore to develop a compact system while taking both the technical requirements and the available space into account.
To provide the required installation height for the necessary sample preparation and sample collection components while keeping the system as compact as possible, a rotary arm sampler was selected as the cross-stream sampler. Due to the operating principle of the rotary arm sampler, the samples taken can be discharged from the slotted sampling vessel at a point approximately 4.5 m above the centerline of the belt drum. This has the advantage of reducing the distance between the sampling point and the sample preparation system to a reasonable level.
The full report can be found in Issue 4/2022 of Schüttgut & Prozess.
