What is the Boustead Model?
The Boustead Model is a computer modelling tool
for lifecycle inventory calculations. There are three main groups of files: the program
files, the core data files, and the top data files as shown in Figure 4.
Figure 4. Structure of the
Boustead Model showing the three main groups of files.
The program files are those which allow you to interact
with the model. These produce the screen displays, accept instructions from you via the
keyboard or the mouse carry out all calculations and print out the required results.
The top data files are those created by you and contain
the information for unit operations that you create. At initial installation these files
are empty. Within the top data there are five separate files. These are:
1. Processes. The records in this file are used to set
up unit operations corresponding to the operations you are trying to describe. These are
similar in format to the materials processing operations in the core data. There is
initially space for 6000 operations. This is adequate for most purposes but if you find
that you need to create more than 6000 unit operations there is a facility for increasing
the number of records in this file.
2. Air emissions (user). The records in this file are to
allow you to add air emissions that are not already identified in the core air emission
files. The file contains space for 50 records.
3. Water emissions (user). The records in this file are
to allow you to add water emissions that are not already identified in the core water
emission file. The file contains space for 50 records.
4. Solid wastes (user). The records in this file are to
allow you to add solid waste categories that are not already identified in the core solid
waste file. The file contains space for 50 records.
5. Raw materials (user). The records in this file are to
allow you to add raw materials that are not already identified in the core raw materials
file. The file contains space for 50 records.
The core data files contain information on a range of
different fuel production and materials processing operations. You will need to draw on
these files when constructing your own data sets. Within this core there are eleven files.
These are:
a. Fuel production. The records in this file contain
fuel production data for almost all of the countries around the world as well as data for
the different regions of the USA and Canada.
b. Materials processing. The records in this file
contain actual production data for a wide variety of materials processing and transport
operations.
c. Stand-alone data. The records in this file contain
information on materials production operations, usually averaged over a number of
different production plants. The data in this file do not rely on data anywhere else in
the database and are usually the result of specific industry-based projects. This type of
information usually refers to bulk commodity materials, which are bought on the open
market but the source is usually unknown.
d. Air emissions. The records in this file contain the
names of the air emissions used in the materials processing, fuel production and
stand-alone operations.
e. Water emissions. The records in this file contain the
names of the water emissions used in the materials processing, fuel production and
stand-alone operations.
f. Solid waste. The records in this file contain the
names of the solid waste categories used in the materials processing, fuel production and
stand-alone operations. This is an empirical list containing the main categories of solid
waste that can usually be identified by process operators. It essentially identifies the
wastes that are generated by the process.
g. EU solid waste. In January 2001, the European
Commission published a list of solid waste categories that would be used to report solid
waste emissions within the European Union. It is a somewhat extensive list and is given in
full in the Code Book. This file therefore lists all of the EU categories. This file
essentially categorises the solid wastes by the way in which they may be handled and
subsequently used for other purposes. A detailed list of the categories is given in the
operation Code Book.
h. Raw materials. The records in this file contain the
names of the raw materials used in the materials processing, fuel production and
stand-alone operations.
i. Fuels. The records in this file contain the names of
the fuel types used in the materials processing, fuel production and stand-alone
operations.
j. Feedstocks. The records in this file contain the
names of the feedstock types used in the materials processing, fuel production and
stand-alone operations.
k. Functions. The records in these files are essentially
instructions to force the computer to manipulate data in specific ways. The use of these
functions is discussed in more detail later.
Unit operations
Because of the manner in which The Boustead Model
has evolved over the last twenty years, it is both extremely simple to operate and a
remarkably powerful tool, capable of analysing highly complex systems without resorting to
approximations or simplifications which may otherwise introduce inaccuracies (especially
when dealing with non-linear systems). The key to this combination of power and simplicity
is the unit operation. A unit operation is defined as a process which produces a single
product. The database within the model holds information on a large number of unit
operations. Reference to any unit operation is made using the code number of the record as
a reference.
Each of these unit operations will take its inputs from other upstream
unit operations and its output product will act as a feed for further downstream
operations. In general, the behaviour of a unit operation will be independent of the
upstream operations that are feeding it and the downstream operations that are taking its
products. Therefore the behaviour of any unit operation can be analysed without reference
to the other unit operations within the system.
Since the inputs and outputs to any unit operation depend on
throughput, it is usual to describe the behaviour of a unit operation by normalising all
of the input and output data with respect to unit output of product. Creating subsystems
to describe the real world is very complex this is the purpose of the software
which comprises the Boustead Model.
Extended life-cycle systems usually contain a large number of
operations linked by the flows of materials and energy. These component operations (or
unit operations) are systems similar to that shown in Figure
3 except that they do have a useful product in their outputs.
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