Traceability methods for continuous processes

Abstract: The subject of this thesis is traceability in continuous processes, i.e. the ability to trace products or batches through a certain process. Examples of the benefits from traceability are that it minimises the extent to which products are affected by product recalls and assures lot uniformity in production. The traceability in part production is often high, since various kinds of identification markers can be attached to a product or batch and followed. Further, the literature in the traceability field is dominated by descriptions of traceability issues in parts production. However, creating traceability in continuous processes implies vast challenges: process flows can be parallel, serial and reflux; sub processes can be continuous as well as batch-wise. These challenges are not commonly addressed in the research literature about traceability. Continuous processes are commonly found in process industries such as the mining, dairy and food, paper, and steel industries. The purpose of this thesis is to explore and describe how traceability can be improved in continuous processes. A research study consisting of a case study was designed and performed to fulfil the purpose. The results from the study are described in four papers. In Paper 1, various traceability methods that could be used to improve traceability in continuous processes are identified and described together with their advantages and disadvantages. A mind map connecting different terms of traceability found in the literature is also presented. Further, the mind map describes how traceability may be improved in a continuous process. In Paper 2, a procedure to develop a flow simulation model for a process section to improve traceability is presented. The constructed flow model is then used to simulate the product flow in the pelletizing plants at LKAB. In Paper 3, a novel method to create traceability in a granular product flow using radio frequency identification (RFID) technique is presented. RFID is a wireless and automatic data capturing technique. The method showed promising results when it was initially tested at a conveyor. In Paper 4, the RFID technique is tested in two full scale experiments in a distribution chain of iron ore pellets at LKAB. Different types of RFID- tags and tag containers are tested in the experiments. The results of the experiments show that the RFID technique can be used to improve traceability in the distribution chain. Finally, the results from the research study illustrate that it may be possible to improve traceability in continuous processes by applying the presented traceability methods.