Optimal production scheduling for dairy industries

In this work, a complete two-level framework for use in food and in particular dairy industries is proposed. The specific characteristics of the dairy industry have been taken into consideration, in terms of the behavior of food sales over time and the special requirements in the production phase. At the scheduling level, an MILP (Mixed Integer Linear Programming) model of the system was developed, using a continuous representation of time

The challenge of integrating non-continuous processes-milk powder plant case study

The integration of non-continuous processes such as a milk powder plant present a challenge for existing process integration techniques. Current techniques are generally based on steady and continuous operation which for some industries is not the case. Milk production varies considerably during the year as dairy cows in New Zealand are grazed on pasture, which affects the scheduling and operation of plants on site. The frequency and duration of cleaning cycles and non-productive operating states can have a major affect on energy demand and the availability of heat sources and heat sinks. In this paper the potential for indirect heat transfer between the several plants using a heat recovery loop and stratified tank at a typical New Zealand dairy factory is investigated. The maximum amount of heat recovery is calculated for a range of recirculation loop temperatures. The maximum amount of heat recovery can be increased considerably if the temperature of the hot fluid in the recirculation loop is varied depending on which condition the site is operating under

Optimal Schedule of a Dairy Manufactory

This paper deals with short-term scheduling of the dairy industry. Two different approaches are proposed for obtaining the minimal makespan schedules. According to the first, S-graph framework is proposed to find the optimal solution of the flow-shop scheduling problem. The problem is solved by applying the branch and bound technique. The second approach uses the integer programming formulation of the scheduling problem and BASIC genetic algorithm has been used to solve the optimization problem. Both approaches take into consideration volumes of units assigned to perform tasks, and respective size factors that affect the size of batches and their number must be produces to achieve production goals and thus on the schedules duration. Manufacturing of two type curds is used as a case study. The results obtained show that both approaches provide comparable solutions. Both approaches could be seen as a good alternative to project manager to find appropriate schedule of the dairy industry

One and Two Way Packaging in the Dairy Sector

Choosing packaging material for dairy products and soft drinks is an interesting issue at the moment. Discussions arise on the costs impacts and environmental impacts of both one way packaging and reusable packaging. The aim of this article is to develop an evaluation tool providing costs and environmental impacts of the PC-bottle and the GT-packs in the dairy sector, considering forward and return flows. The evaluation tool enables the user to analyse the costs and environmental impacts of a supply chain with and without return flows using scenario analyses with respect to the use of various carrier types and the number of return loops. It appears that costs differences between PC-bottles and GT-pack are quite small. The PC bottle has a better environmental profile than the GT-pack. Scenario analysis on the carriers results in the advice to use preferably roll-in-containers with direct delivery, secondly roll-in-containers with delivery via distribution centers, thirdly in case of direct delivery either cartons or crates and cartons in case of delivery via distribution centers.pricing;supply chain management;reverse logistics;environment;life cycle assessment

Energy and Agriculture in Australia and New Zealand: Politics, Prices and Economic Outcomes

Energy is a significant agricultural input in both Australia and New Zealand. Likewise agriculture in NZ Australia has the potential to produce significant energy sources - the extent to which depends on the price of competing energy sources - particularly oil. Higher energy prices, resulting in changes in land use in North America also have the potential to significantly impact the demand for, and prices received, for Australian and New Zealand agricultural commodities. This paper analyses recent statistics on agricultural energy consumption in both Australia and New Zealand and considers the relationship between energy prices and aggregate economic activity and economic activity in the farm and farm processing sector. It explores the impact of alternative energy price scenarios on Australian and NZ agriculture. It is informed by both CGE analysis of the NZ economy and results of international studies. The evolution of outcomes is sensitive to both global energy prices and the policy responses of the Australian and New Zealand Governments.Farm Management, Resource /Energy Economics and Policy,

Non-continuous and variable rate processes: Optimisation for energy use

The need to develop new and improved ways of reducing energy use and increasing energy intensity in industrial processes is currently a major issue in New Zealand. Little attention has been given to optimisation of non-continuous processes in the past, due to their complexity, yet they remain an essential and often energy intensive component of many industrial sites. Novel models based on pinch analysis that aid in minimising utility usage have been constructed here through the adaptation of proven continuous techniques. The knowledge has been integrated into a user friendly software package, and allows the optimisation of processes under variable operating rates and batch conditions. An example problem demonstrates the improvements in energy use that can be gained when using these techniques to analyse non-continuous data. A comparison with results achieved using a pseudo-continuous method show that the method described can provide simultaneous reductions in capital and operating costs

Monitoring and optimal management approaches to reduce water and energy consumption in milk processing processes

This paper proposes a methodology for the monitoring and optimal management of milk processing processes to reduce water and energy consumption. First, the key variables that should be measured to characterize the water/energy consumption are identified. Then, a monitoring system that is integrated with the current SCADA system already deployed in the production process has been developed that is able to evaluate the energy consumptions not directly computed from the available sensors. From real historical measurement records of the different subprocesses, their efficiency is determined. This information is used for developing an optimal management system that allows reducing the water/energy consumption. The work presented in this paper has been developed in the context of the European project named EnReMilk that aims to introduce significant water and energy in several milk processing processes by the introduction of new processing and management technologies. The assessment the proposed approach is based on the comparison with the current baseline consumptions.Peer ReviewedPostprint (author's final draft

A life cycle based method to minimise environmental impact of dairy production through product sequencing

The trend of increasing the number of dairy products for sale affects their environmental impact in a life cycle perspective. During dairy processing, the production schedule is affected by more frequent product changes, hence also cleaning operations. This causes more milk waste, use of cleaning agents and water. The amount of milk waste depends on the product change technique used, which is determined by the characteristics of the product. A method was designed to calculate the sequence, which, for a given set of yoghurt products, minimises milk waste. A heuristic method, based on the strive to minimise production waste combined with production rules, was worked out. To determine whether the heuristic solution gives the best possible sequence from an environmental perspective, an optimisation was also made. The analytical method used for optimisation was able to handle 21 products and verified the heuristic method for a waste minimised sequence up to that level. It is also highly probable that for sequences including a greater number of items waste can be minimised with the same heuristic method. A successful demonstration of the possibility to make a more complete environmental assessment was fulfilled by connecting the sequencing model to conventional life cycle assessment methodology

Optimal batch scheduling of a multiproduct dairy process using a combined optimization/constraint programming approach

This paper presents the optimal batch scheduling of a multi-product dairy process using an approach that combines optimization and constraint programming techniques. A suitable model describing the subprocesses and production rules is developed allowing to obtain scheduling constraints relating the production process and the machines available together with their relative efficiencies. After the scheduling problem has been formulated, the batch scheduling of a real powder milk/yogurt process is obtained in an optimal manner using the proposed approach with the objective of meeting customers’ deadlines considering the efficiencies/costs of available alternative machines. Results using real consumer orders on some representative scenarios corresponding to the dairy production plant used as a case study are provided. This application shows a formulation closer to the engineering problem description thanks to the constraint-based language that facilitates the adaptation of the optimization objectives and constraints to real applications.Peer ReviewedPostprint (author's final draft

Supply chain planning in the food industry : a systematic literature review

PURPOSE: Advanced Planning Systems (APS) can contribute to improved decision making and enhanced efficiency along complex food supply chains. This paper presents a systematic literature review of supply chain planning (SCP) in the food industry. In particular, the literature on three increasingly important planning tasks supported by APS is examined, namely Supply Chain Network Design, Sales & Operations Planning and Production Planning & Scheduling. METHODOLOGY: A literature review is conducted by systematically collecting the existing literature published between 1998 and 2020 and classifying it based on three planning tasks supported by APS modules (Supply Chain Network Design, Sales & Operations Planning and Production Planning & Scheduling). Furthermore, research papers are categorized according to the product under consideration, geographic region and method. FINDINGS: Multiple models for SCP practices have been developed. The modelling literature is fragmented around specific challenges faced in food supply chains. Empirical literature including case studies on the implementation of APS is sparse. The findings suggest that developed models for the three examined planning tasks are only implemented to a limited extent in practice. ORIGINALITY: This paper focuses on three planning tasks that are of increasing relevance for the food industry. The literature review can help practitioners within the food industry to get insights regarding the opportunities offered by the three software modules examined in this paper. Further research should be conducted in these areas to make literature on SCP more practically relevant for managers