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Reducing waste at an in-container sterilization

Wingelaar, L. (2008) Reducing waste at an in-container sterilization. Master's Thesis / Essay, Industrial Engineering and Management.

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Purpose - The aim of this research is to come up with proposals that will reduce the amount off spec products that are produced at the in-container sterilization stage and to reduce the total water consumption of this particular stage at Propack, a subsidiary of Royal Friesland Foods. At the stage coffee supplements in bottles and dairy-based products in cans are treated. Furthermore, stage consists out of two nearly identical Stork hydrostatic sterilization towers, ‘C4’ and ‘C5’. Research limitations - The research was limited to a period of 5 months and the scope of this research was on the sterilization stage. Methodology – This research follows the regulative cycle. First the problem of off spec products is quantified with the use of production data. Theory about sterilization and product properties that are affected by this treatment is explored to gain insight in the process and the reasons why products are rejected. The backbone of this research is a comprehensive Root Cause Analysis (RCA). Various RCA tools are evaluated; eventually the Fault Tree Analysis (FTA) tool is selected. With the use of the FTA a number of presumptive causes that lead to off spec products are identified. These presumptive causes are verified with a variety of techniques and tools including interviews with directly and indirectly involved personnel, observations, tracer measurements and a Matlab simulation. Last step is the development of solutions for the identified root causes. Furthermore, a thorough system analysis, which is part of a FTA, showed opportunities to reduce the water consumption of the stage. Findings - The FTA resulted in 22 presumptive causes that could lead to the production of off spec products. After a thorough verification process 5 root causes were identified: (1) too much steam is injected in C4 due to failing temperature controllers (2) the inlet water can be too cold (3) a blocked filter in the water circulation (4) the design of the products feed system (5) mistakes of operators while setting the sterilization temperature. Furthermore, a number of 3 external root causes have been identified but these were beyond the scope of this research and are therefore not further investigated. Regarding the water consumption; after analyzing the system it was found that C4 uses significantly more water than C5 (60% to 40% of the total consumption). It was found that this is also caused by the failing controllers of C4. The company is advised to conduct a research to investigate the possibilities of water recycling at the stage. Solutions - Several solutions are proposed to solve the identified root causes. The most important proposal is the replacement of the instrumentation of the steam injection control schemes of C4; this will lead to a reduction of off spec products and a reduction in water consumption; the Net Present Value of this solution is estimated to be nearly €80.000 over 5 years while the initial investments are €7.700. Other solutions include the installation of flow rate recorders and displays to improve process monitoring by operators; better monitoring enables earlier problem notification which reduces the impact the problem. To solve the problem with the cold inlet water, a plate heat exchanger is designed. The Net Present Value of this project is currently unacceptable, therefore this proposal is rejected. Originality - Currently there is hardly any literature available about in-container sterilization. This research provides insights in relevant aspects of operating an incontainer sterilization stage form both a technological and management point of view. However, the outcome of this research is not general applicable as the systems are, at least to a certain extent, custom designed and only a limited range of dairy products are considered. This research might be useful as a case study for a theoretical evaluation of the RCA methodology and techniques.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Industrial Engineering and Management
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 07:29
Last Modified: 15 Feb 2018 07:29

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