unido tool kit 3-textbook

U N I D O C L E A N E R P R O D U C T I O N T O O L K I T

UNITED NATIONS INDUSTRIAL DEVELOPMENT ORGANIZATION

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Material flow analysis

Main directorym

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Textbook 3 - Material flow analysis

3- BACKGROUND MATERIAL

3 Textbook

3.1 Aims and goals of „Material flow analysis“

After working your way through this brochure you will be able to describe and illustrate any material flow occurring in your company and to write a systematic full documentation. You will

• trace the flow of raw materials through the company

• retrace waste to the point where it is generated

• edit data in a decision-oriented form

• identify weaknesses in the production process

• set reasonable priorities for further waste and emission minimization measures.

This will perfectly enable you to fulfil the waste documentation requirements within your firm and to work out an elaborate waste management concept. Furthermore, you will literally detect weak points in material utilisation and define measures to minimise them.

How to use this volume?

All in all you should be able to take four hours to do this: you will need about an hour to go through the introduction and another hour to work through the examples. You should reserve two more hours to study ways of implementing in your own firm what you have learned.

Authors:

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3.2 Material flow analysis defined

The so-called ”material flow analysis“ is a systematic approach aiming to

• present an overview of the materials used in your company,

• identify the point of origin, the volumes as well as the cause of waste and emissions,

• create a basis for an evaluation and a forecast of future developments,

• define strategies to improve the overall situation.

Waste and emission problems of a company arise at those points of production where materials are used, processed or treated. Therefore companies opting for a strategic solution of their environmental problems have to be aware that it is essential to capture the current material flows in a model, in order to identify points of origin, volumes and causes of waste and emissions, to get to know the substances they are dealing with, to estimate their actual value for the process and finally to forecast possible developments in due course. They will have to create an information system enabling the management to retrace material flows within the company, to direct them and to guarantee that they are efficiently used.

„A material flow analysis is a systematic reconstruction of the way a chemical element, a compound or a material takes through the natural and/or the economic cycle. A material flow analysis is generally based on the principle of physical balance“. (German inquiry commission “Schutz des Menschen und der Umwelt“ - protection of man and his environment - of the Deutsche Bundestag, 1993)

A material flow analysis can thus be compared to the tracing of a company map which rather than cities, roads or rivers shows process sequences and material flows as geographical features.

As for the map, a graphical illustration of these features is essential. Therefore it is important to graphically present the information gained through an analysis of material flows with regard to origin, use and treatment of raw and process materials in a way that they can most rapidly and easily be interpreted.

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So far, various types of graphics have been successfully used:

• Flow sheets representing material flows and process sequences,

• Pie charts and histograms illustrating ratios and distribution,

• Time-travel diagrams showing time relations,

• Sankey diagrams visualising material flows correct to scale.

In large companies in the pulp and paper industry as well as in the chemical and petrochemical industries these means of process illustration are already part of day-to-day practice. Why not use these instruments for your own purposes?

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3.3 How to carry out a material flow analysis

A complete material flow analysis is done in seven steps:

1. Defining the aim of the analysis and parameters to be monitored

2. Defining the scope of balance

3. Defining the limits of the balance period

4. Listing and denominating process sequences

5. Designing the flow sheet: material flows - qualitative approach

6. Balances: material flows - quantitative approach

7. Interpretation of results and conclusion

The steps 2 to 5 are also called "system analysis". In this analysis relevant system elements are identified and the relationship between them is shown.

In detail these steps include:

1. Defining parameters:

Which materials are to be traced?

As a first step one has to determine the aim of the material flow analyses to be carried out, as the aim is the starting point from which the parameters to be monitored and the area to be studied are defined. One of the aims of a material flow analysis might be to retrace interesting flows of goods, of certain chemical compounds or of single elements through the company, with regard to various criteria (costs, risks, safe disposal, volumes). The question of how exact this analysis shall be has to be clarified right from the beginning.

To do this, it is recommended to start with a material flow analysis of the company as a whole. In this case, one defines, at the battery limits, which materials and of which value are used in which quantities within the company and also which wastes and emissions (besides the products themselves) leave the company taken as a whole. This is done in the form of an input/output analysis.

Thereby all raw and process materials as well as all energy sources are listed in terms of quantity and value on the basis of stockkeeping or accounting records. Products and emissions are listed using the same procedure. In this context we can speak of a material balance at company level. A more detailed analysis will primarily investigate expensive and ecologically problematic materials. To define priorities, the identified

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material flows are then ranked in order of value and toxicity in the sense of an ABC analysis.

Tip: Take the list which you have drawn up during your work with vol. 1 containing the 10 most expensive raw materials, the 10 most hazardous materials and the 10 most important wastes occurring in your firm. If any data are missing, give an estimation and collect the real data afterwards. Which of these materials do you wish to retrace in detail? What is your most urgent problem? Rank the material flows in order of their value and toxicity in the sense of an ABC analysis. Later on, in a case study, we will trace the flow of water through a brewery. Which material of your firm would you like to retrace in a material flow analysis?

My problem material:

................................................................................

2. The scope of balance

The scope of balance can either comprise the company as a whole or refer to individual processes. Its definition depends once more on the aim of the analysis: first, the company is studied as a whole. In order to identify intervention possibilities, processes will have to be divided into single steps.

How to define the scope of balance

3. The balance period

Choose your own balance period!

It has proven successful to choose a representative period as a balance period. This may be a balance year, a month, a production charge or else a week in production.

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4. Listing and denominating production steps

In the next phase, processes are divided into steps relevant to their respective structure and function and finally represented in a flow chart. This flow chart should be based either on activities or on equipment, on production units or on profit centres. As graphical elements, rectangles will be used to indicate production steps and arrows for material flows.

Listing processes and procedures

5. Designing the flow chart

All relevant data on material flows are also represented (components, value, volumes, data sources, ecological relevance). In the same way, all important data of process sequences (or equipment) such as temperature and batch size have to be documented. These flow charts can also be used for the drawing up of a waste management concept (see Ecoprofit vol. 10).

Flow charts illustrate the production process

6. Balances

When drawing up a balance the principle of conservation has to be kept!

Just as for the entire company, the principle of conservation of masses has to be kept for any of the system elements defined as „production steps“: in a stable system, the mass input into an element has to be equivalent to the output. All raw and process materials input into a certain element have to leave it in the form of either a product or of waste or emissions. For this reason we have to calculate in mass units [kg].

7. Interpretation

How to interpret flow chart and balance sheets

Interpreting a flow chart means to retrace material paths (illustration of the exact point of generation of wastes, establishing relations between raw materials and waste) as well as to introduce key figures in the form of efficiency ratios (cost-efficiency ratio) and performance ratios (real efficiency in comparison with theoretically projected efficiency) for both the company as a whole and the individual production steps.

Tip: See also volume 7 ”Indicators and environmental controlling“.

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By comparing information concerning the real efficiency of processes to reference values, weak spots can be more easily detected. For further analysis these should be ranked in order of priority, which will eventually induce a discussion process within your company. Through the regular updating of process data an instrument for technical controlling is created which permits the documentation of the development of material use and material flows.

Tip: Try to collect information on your particular problem material, machine or process: does the competition also use this material, how much do they use in comparison with you, can your supplier provide you with a satisfying equivalent alternative?

The following strategies could lead to an improved material utilization.

• Good housekeeping in the sense of a thoughtful use and handling of raw and process materials (respect of product formulas, complete emptying of containers, sealing of leakages, ...)

• Substitution of raw and process materials (through raw materials containing neither formaldehyde, nor heavy metals or chloride...)

• Process modifications (e.g. automatic control, ...)

• Product modifications

• Internal recycling (closing of water circuits, recycling of valuable materials within the company, ...)

• External recycling (recycling of scrap, composting biodegradable materials, ...)

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Case study: analysing the material flow of coffee making

The following case study illustrates the systematic approach of a material flow analysis by means of a simple example: we are going to look into the process of coffeemaking and the related material flows in order to

• allocate the occurring wastes to individual process sequences,

• to quantify the amount of waste produced and

• to define remediary measures.

Two cups of coffee are made. To do this, coffee beans are taken out of a storage box (in this case the packaging is not taken into account) and ground in a coffee grinder. A filter is put into the coffee machine to hold the coffee powder. Then the machine is filled with water and switched on. After about ten minutes the coffee is ready and can be poured into cups.

The energy necessary for the process and the waste heat produced is not taken into account. Likewise the steps of "filter production", " coffee purchasing", "coffee planting", "coffee roasting", "coffee packaging", "coffee storing", "water treatment", "drinking", "disposal of filter" are left out. The main goal of this analysis is to reduce the solid waste to be disposed of. The following list summarizes the individual steps:

1. Parameters considered: material flows (coffee beans, water, filter), going into detail is not necessary in this case.

2. Scope of balance: the process sequence of „coffeemaking“ as well as all other relevant sequences are left out.

3. Balance period: one brew as representative period comprising all relevant activities and materials in usual amounts.

4. Process sequences: ”coffee making“, sub-sequences: coffee grinding, water boiling, brewing.

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5. Designing a flow sheet:

6. Quantitative overview over materials flow:

Filter

Water

Coffee beans

Balance limit

Powder Coffee powderGrinding

Boiling water

Filter

Grounds

Coffee making

Coffee

Complete process

Material flow Mass [g]

Costs [Cent]

Origin/destination

Input: Coffee beans 10 51 Raw material

Water 250 2 Raw material

Filter 2 15 Process material

Output: Coffee 220 256 Product

Residual powder 1 0,02 Non recyclable waste

Used filter 7 1 Non recyclable waste

Coffee grounds 34 7 Non recyclable waste

Balance

Input = Output 262

Data were collected through weighing and measuring as well as through accounting analysis.

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Subsequence of coffee making

Material flow Mass [g]

Input: Coffee powder 9

Water 250

Filter 2

Output: Coffee 220

Used filter 7

Coffee grounds 34

Balance

Input=Output 261

Similar balances should be drawn up for the other two subsequences.

In the following diagram all results of a material flow analysis are graphically demonstrated in form of a Sankey-diagram.

Kaffeebohnen

Wasser

Mühle

Kaffeemaschine

Produkt

Sud - Abfall

Filter

Reinigung

Alle Angaben in Gramm

Erstellt mit S.d r a w

Sankey diagram

10

250

10

262

220

41

2

1

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Description of equipment

Coffee grinder:

Type COGRI I

Capacity 10 g

Power rating 50 W

Coffee machine (the water is boiled and the coffee is made in one and the same machine).

Type COCO II

Capacity 8 cups

Power rating 500 W

The above data were taken from labels and/or the operating instructions.

7. Interpretation:

Generally speaking it has to be stated that the existing coffee machine is badly used: the machine can produce 8 cups, but on average only 2 cups are made at the same time. A better utilization of the capacity could reduce the amount of throw away filters used.

During grinding and coffee brewing solid waste is produced: in the grinding sequence residual powder is left behind in the grinder and in the brewing sequence waste is generated in the form of a used coffee filter containing residual wet ground coffee. For several reasons (hygienic, practical reasons), this waste cannot be re-used. 16 % of the input result in solid waste 70 % of which consist of water. The following strategies to reduce the waste to be disposed of are on offer:

a. Good housekeeping:

Complete emptying of coffee grinder. While the avoided solid waste can be disposed of for only 0,02 Cent, the value of the powder (purchasing costs!) is of 5 Cent.

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b. Other ways of disposal:

Composting the used filter and coffee grounds: The same disposal costs are incurred. On the other hand, composting makes more sense than disposal as it amounts to external recycling of a valuable material.

c. Changing process materials:

Substituting the paper filter through a cleanable gold filter and composting the coffee grounds: the goldfilter permits the costs for the paper filter and disposal to be saved. The time necessary to place the filter in the machine is not taken into account. The time for cleaning the filter is defined as equivalent to the time necessary to take the used paper filter out. The goldfilter is mechanically cleaned. Payback of the goldfilter at a price of 46,- EUR is after 90/0,32 = 281 coffee making processes, i.e. within a year.

Kaffeebohnen

Wasser

Mühle

Kaffeemaschine

Produkt

Sud - Abfall

ReinigungErstellt mit S.d r a w

Alle Angaben in Gramm

Graphic 2

10

243

10

254

220

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d. Minimizing the amount of raw materials used:

Drawing up of a time-travel diagram in order to optimize coffee utilization: the quantities of coffee powder used for each brew are plotted in a diagram and compared to each other. If variation among them or from the predefined reference is more than e.g. 5 %, the causes of these variations have to be discussed in order to define appropriate remediary measures (e.g. use of a dosage device). Further we are determining the indicator “coffee beans consumption per gram finished coffee powder”. In our example this is 0,045 g coffee beans consumption per gram finished coffee.

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3.4 Material flow analysis for water

There are hardly any companies where water is not used in some way.

Water is a precious commodity, which must not be wasted – and further, it is not necessary to treat avoided waste water. Water is

valuable...

...and expensive The operational water management faces considerable costs for the provision of fresh water and waste water discharge as well as for the internal waste water treatment. The costs for the discharge or disposal of water can vary from region to region and range – without internal treatment – between 0,5 and 5 EUR per m3 (in Germany e.g. it is even more expensive in some parts).

The efficient use of water goes hand in hand with CP in terms of ecology and economy. Mostly an efficient use of water, especially measures for warm water, inhere energy saving potentials as well.

These are the reasons why we should focus on the issue “water” in a company and why we should collect data within the scope a of material flow analysis.

In the framework of the water balance the amount of water which goes into the company is going to be measured (input through municipal water, wells...). This amount, of course, has to leave the company again (output through discharge, in the product itself, evaporation...).

Develop a water balance

In the company itself there are different consumers which determine the water consumption.

The aim of the water balance is to identify the streams or technical adjustments which inhere potentials to improve the water consumption in an ecological and economical way - improvements in terms of less water consumption as well as a reduction of the toxic materials in the water.

It is easy to gather data of water compared to many other material flows due to:

• Annual settlement of the provider or disposal companies

• Water meter, water counter

• Mobile discharge meter

• Measuring at consumers (stop watch, bins)

• Estimating, computing

• Water consumption statement of manufactures or plants

• indicators

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The target value for the water consumption of a clerk, according to most books, is:

Administration building: 30-50 litres per day and employee (sanitary and cleaning water)

A whole lot of water saving measures

Economy measures for water can be classified according to the “tree of measures”. The whole lot of measures is very sophisticated and therefore we are now not going to talk about it in detail. The feasibility has to be examined for every single case itself.

• Level 1: measure at source

- dry-cleaning process

- mechanical pre-cleaning

- principles of reverse flow

- cascade-use of waste

- water saving fittings

- high-pressure cleaning appliance

- discharge limiter

- water stop closures

- reduction of harmful waste in the waste water

- separating of waste water streams

- evaluation of data

- use of indicators

- water saving control engineering

- use of rain water

- selection of chemicals and purifiers with minimal water endangerment

- metering systems

- ...

• Level 2: internal recycling multiple-use, and reuse of water Reuse for not critical cleaning purposes, use of cascades, recovery due to

filter systems, closing water cycles...

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One of your task will be to generate a water balance with the work sheets 3-1 and 3-2.

Develop a water balance with the work sheet 4-2

Work sheet 3-2:

In order to get the water input please give the respective annual amounts (also see work sheet 1-2 Volume 1)

Input - consumer - Output

Now you must determine, measure, compute, estimate etc. the amounts of the most important water consumers (see above). If you have not got any important consumers apart from sanitary water, you also can give the percentage in the column “%”.

For the waste water discharge please declare whether you discharge directly (in a river, a so called on-site preflooder) or if you discharge indirectly in a canal and then in a public and external sewage plant. Discharging

waste water: - direct - indirect - contaminants - limits - treatment

Please also name important substances of content, which are discharged in your company (substances which are beyond the condition of sanitary water) as well as important limit values you have to comply. In the case you pre-treat your waste water internally (oil separator, biological treatment, heavy metal precipitation), please briefly describe this process.

3.5 Information sources

System analysis for material flow

First of all, a flow diagram has to be drawn. The data sheet specially designed for this purpose (worksheet 1, process flow chart) is meant to be self-explanatory.

In order to carry out a material flow analysis in our case study the following data are necessary:

• Type

• Quantity

• Value

• Point of use or of generation

Now you have to find out these information in a company. The worksheets, 3-2 (water data sheet) and for any other material flows than water the worksheet 3-3, should help you in doing so.

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The columns “number” and “identification” are for the characterisation of the material flow. The numbering and consumer/identification in the worksheets 3-2 and 3-3 should conform with the flows in the process flow chart (3-1).

Balances in mass units (kg, t, g)

Balances are usually made in dimensions (kg, t, g), because in this particular case the mass balance has to be applied. Therefore in the material chasing sheet the flows should also be given in masses if there are no other important reasons. For the water balance we use m³ (1 m³ = 1.000 litre), because it is more common for water. Moreover the density is more or less equal at the considered temperature- and pressure level (~ 1 kg/l).

Water balance in m³

In the bottom line of the sample page you will find a list of possible data sources. Data concerning inputs are available from various accounts in the accounting department such as raw and process materials or from the logistics department in the form of material numbers.

Data concerning process flows are available from the computer department (e.g. production planning and control), from the foreman or the workshop masters themselves, from job planning or production records. If all these sources do not permit the collection of the necessary data on quantities and value you will have to carry out your own measurements or to rely on estimations.

Output data are usually accessible through control sheets.

This will permit the flow of a certain material to be retraced from the point of entry into the company, following its way through diverse processes to the point of output. Ideally you will be able to draw up a coherent material balance: input has to be equivalent to output. The same applies to detailed balances and individual process sequences.

A good estimation is always to prefer to having no balance at all; an estimation with an accuracy of 80-90% is sufficient.

3.6 Material flow analysis in SMEs (Small and medium-sized enterprises)

There are many problems you can face when establishing a detailed material flow analysis in a SME:

Typical problems

• No process control system

• No measuring devices

• Too little time and personnel

• Too little knowledge about material flow balances

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• Little insight in necessities – the benefit of a material flow analysis

• The costs are in no proportion to the benefits

• No typical production companies

• Big inaccuracy

Important recommendations: Awareness and recom-mendations • Material flow analysis have to be done in iteration steps

• Estimating is better than doing nothing

• Even with estimation it is possible to improve

• 80 - 90% accuracy is sufficient

• Use simple measurement devices

• Use of indicators (also see Volume 9 Environmental Controlling)

• If necessary contact your supplier or plant manufacturer

• Precise instructions or recipes for material flow analyses are not that essential, helpful: creative procedure.

Just the development/working with the balances sometimes leads to improvement. Important!: Interpretation and translation of the results into the respective language of the target group ($, kg, pictures, comparisons...).

3.7 The use of data sheets and EDP-Programs

Tools to gather data are available in the literature in form of data gathering sheets, check lists and interview models. They can be used especially for the careful documentation of the waste avoidance project and as help for the search for emission avoidance potentials. Before they are used, however, they should be checked in terms of there usefulness in the particular case and if necessary be adapted. In no case they should be given further to progress without making any comment.

Tip: Make sure that you fully understand the datasheet in the appendix of this volume! Make sure that you fully understand the checklists for waste avoidance in volume 1!

In every office today PC and spreadsheet programs, for example MS-Excel, are standard equipment. They can also be very helpful in terms of data administration, and for the development of graphic analyses and presentations.

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