The Added Value of Simulation during Liquid Bulk Terminal Design
2009.PEL.7382 - R. van Duijn 6
Summary
Conceptual design of liquid bulk terminals is one of the main activities which are conducted at Royal Haskoning’s business group Industrial Installations. It would be beneficial if designers could gain instant insight in (future) terminal performance capabilities based on variable design input
parameters, without the need to setup a new calculation model for each new project. Furthermore, there are some design aspects which cannot be considered at all using conventional methods. Added insight could be achieved with the help of a dynamic simulation design support tool.
The objective of this thesis has been to develop a design support tool which can be used alongside conventional design methods. The research question is to what extent this tool has an added value to the design process.
Liquid bulk terminals can be divided in three major groups: the buffer storage terminal, the
independent storage terminal and the trading terminal. Functionally, these terminals differ only slightly from each other. The primary functions of the terminal are: to connect different modalities together, to provide a buffer for (temporary) storage and to change product flow size and behaviour.
The design process at Royal Haskoning Industrial Installations can be recognized as steps from the Innovation model. The design steps and the Innovation model have been compared, and the steps during which simulation can be of added value are identified: simulation is applicable during concept design, and the first step of basic design (similar to the function and process design steps from the Delft Systems Approach, respectively). Therefore, it is concluded that the simulation model should be applicable to both function and process design steps. In the model, these are called the dimensioning and control phase.
The main reasons why the model is chosen to be a discrete-event simulation model are: developing a simulation model generates questions about the behaviour of the system, and modelling therefore leads to a better understanding of the system. Simulation shows dynamic behaviour of variables. Uncertainties can be modelled with stochastics. Modular, object-oriented design is easily expandable to suit specific needs.
A conceptual model has been developed, and a process description language is formulated to provide a means to understand the model without knowledge of programming language. In this way, an entire design team is able to provide useful input, and simulation becomes an interdisciplinary activity.
The intention of the simulation model during the dimensioning phase is purely to get an insight in the size of operations, informing the designers about the dimensions in which the terminal operates. Control routines will be left out of the scope in this phase. This phase in the model corresponds to the function design phase of the design trajectory. An important feature of this phase is the absence of definitions of process equipment to support the terminal functions. Only the providing and retrieving
The Added Value of Simulation during Liquid Bulk Terminal Design
2009.PEL.7382 - R. van Duijn 7 modalities are specified as physical equipment; the terminal itself can be regarded as a series of functions without the constraints imposed by selecting equipment.
The control phase uses the output from the first phase, e.g. storage levels and other specifications, to determine the equipment needed to satisfy the requirements. This phase corresponds to the process design phase of the design trajectory. Because of the imposed restrictions that arise from selected objects from the equipment aspect (e.g. limited storage, limited berthing capacity), this phase introduces the need for control: the processes need to be steered into the right direction in order to keep the model running as intended.
To examine the performance of the model, experiments have been conducted using data from a project that was in its conceptual design phase at Royal Haskoning Industrial Installations.
Experiments show that the simulation model is capable of delivering outcomes that would have been otherwise left unnoticed in the conceptual design phase. Outcomes from the model predicted the needed capacity for a vapour treatment unit more precisely than was possible with basic static calculations. Other outcomes of the model predicted some potential difficulties with relative low storage capacities in combination with large vessel capacities for certain products.
The model has proven to be able to provide the design team with additional information regarding terminal design, already in an early stage of the design process.
Developing the simulation model will generate additional insight and new questions about the process which leads to a better understanding of the project. The strength of the model in itself is that it gives useful additional information which otherwise might not have been recognized, in this early stage of the project.
Being a generic model also adds to the strength of the tool. However, as a result of this generic character the model may require expansion in order to be able to answer the full spectrum of design considerations.
On the other hand, the setup of the model allows for easy expansion of the model with additional functions, and more detailing in the processes, resulting in a tool that can significantly facilitate the concept design phase of liquid bulk terminals.
