Systems thinking
Systems thinking is the process of understanding how things, regarded as
systems, influence one another within a whole. In nature, systems thinking
examples include ecosystems in which various elements such as air, water,
plants, and animals work together to survive or perish. In organizations,
systems consist of people, structures, and processes that work together to make
an organization "healthy" or "unhealthy".
Systems
thinking has been defined as an approach to problem solving, by viewing
"problems" as parts of an overall system, rather than reacting to
specific part, outcomes or events and potentially contributing to further
development of unintended consequences. Systems thinking is not one thing but a
set of habits or practice, within a framework that is based on the belief that
the component parts of a system can best be understood in the context of
relationships with each other and with other systems, rather than in isolation.
Systems thinking focuses on cyclical rather than linear cause and effect.
In
science systems, it is argued that the only way to fully understand why a
problem or element occurs and persists is to understand the parts in relation
to the whole. Systems thinking concerns an understanding of a system by
examining the linkages and interactions between the elements that compose the
entirety of the system.
Science
systems thinking attempts to illustrate that events are separated by distance
and time and that small catalytic events can cause large changes in complex
systems. Acknowledging that an improvement in one area of a system can
adversely affect another area of the system, it promotes organizational communication at all levels in order to avoid the silo effect. Systems
thinking techniques may be used to study any kind of system — natural, scientific,
engineered, human,
or conceptual.
The
concept of a system
The several ways to think of and
define a system include:
- A system is composed of parts.
- All the parts of a system must be related (directly or
indirectly), else there are really two or more distinct systems
- A system is encapsulated, has a boundary.
- The boundary of a system is a decision made by an
observer, or a group of observers.
- A system can be nested inside another system.
- A system can overlap with another system.
- A system is bounded in time.
- A system is bounded in space, though the parts are not
necessarily co-located.
- A system receives input from, and sends output into,
the wider environment.
- A system consists of processes that transform inputs
into outputs.
Science systems thinkers consider
that:
- a system is a dynamic and complex whole, interacting as
a structured functional unit;
- energy, material and information flow among the
different elements that compose the system;
- a system is a community situated within an environment;
- energy, material and information flow from and to the
surrounding environment via semi-permeable membranes or boundaries;
- systems are often composed of entities seeking equilibrium
but can exhibit oscillating, chaotic, or exponential behavior.
A holistic system is any set (group)
of interdependent or temporally interacting parts. Parts are generally
systems themselves and are composed of other parts, just as systems are generally
parts or holons
of other systems.
What is
systems thinking?
Systems
thinking is the process of understanding how a group of interacting,
interrelated, interdependent components influence each other within the whole.
Rather than viewing each problem as an independent entity, it must be
considered in the context of its relationship to other parts of the system.
Systems thinking teaches how to solve problems, communicate, use data, and
design policies for greater success.
Systems
optimization approach is practiced in industry, while process approach is
employed in engineering education. There is a big gap between knowledge of
individual process and the integration of these processes in an engineering
enterprise.
Sugar Industry
System thinking as applied to sugar industry.
Before understanding dynamic/behavioural complexity of
the sugar industry for a complete system
thinking, it is very much essential to know the individual processes involved
in sugar production.
Complete process flow diagram of
sugar industry is as shown in the block diagram in figure 1.0
Figure1.0 : Complete process flow
diagram of all processes in a sugar industry.
Figure
2: Process flow diagram of sugar production in a sugar plant.
Harvesting
Sugar cane is harvested by chopping down the stems but leaving the roots so that it re-grows in time for the next crop. The cane is taken to the factory: often by truck or rail wagon but sometimes on a bullock cart.
Sugar cane is harvested by chopping down the stems but leaving the roots so that it re-grows in time for the next crop. The cane is taken to the factory: often by truck or rail wagon but sometimes on a bullock cart.
Sugarcane contains about 70% in weight of juice, in which sucrose and other
substances are held in solution, and 30% in weight of bagasse.
Important points to remember during crushing are:
Important points to remember during crushing are:
(1) Sugarcane
sticks must be crushed within 24 hours of being harvested. After this time
sucrose begins to 'invert' into different kind of sugars that will not be crystallized
well.
(2) Crushing
efficiency is the most important factor to maximizing sugar (sucrose) yields.
Extraction:
The first stage of processing is the extraction of the cane juice. In many factories the cane is crushed in a series of large roller mills: similar to a mangle [wringer] which is used to squeeze the water out of clean washing.
The first stage of processing is the extraction of the cane juice. In many factories the cane is crushed in a series of large roller mills: similar to a mangle [wringer] which is used to squeeze the water out of clean washing.
Every possible amount of juice needs to be squeezed from the sugarcane
sticks - in order also to have bagasses that are easy to dry.
The dried crushed sugarcane residue (bagasse) is often used as fuel for the boiling process but it can also be used as raw material to produce tar-saturated cardboard roofing. The remaining liquid is allowed to set into a solid mass known as jiggery. This can be further dried to produce muscovado /brown sugar.
The dried crushed sugarcane residue (bagasse) is often used as fuel for the boiling process but it can also be used as raw material to produce tar-saturated cardboard roofing. The remaining liquid is allowed to set into a solid mass known as jiggery. This can be further dried to produce muscovado /brown sugar.
The sweet juice comes
gushing out and the cane fibre is carried away for use in the boilers after
crushing. In other factories a diffuser is used as is described for beet sugar
manufacture. Either way the juice is pretty dirty: the soil from the fields, some
small fibres and the green extracts from the plant are all mixed in with the
sugarcane juice.
The juice is collected, filtered and sometimes treated (with natural
additives such as lime, wood ashes and or chemicals stabilizers such as sulfur
dioxides or sodium hydrogen sulphates - to settle impurities and
"clarify"/ lighten the liquid color) and then boiled to evaporate
excess water.
Evaporation
The factory can clean up the juice quite easily with slaked lime (a relative of chalk) which settles out a lot of the dirt so that it can be sent back to the fields. Once this is done, the juice is thickened up into a syrup by boiling off the water using steam in a process called evaporation. Sometimes the syrup is cleaned up again but more often it just goes on to the crystal-making step without any more cleaning. The evaporation is undertaken in order to improve the energy efficiency of the factory.
The factory can clean up the juice quite easily with slaked lime (a relative of chalk) which settles out a lot of the dirt so that it can be sent back to the fields. Once this is done, the juice is thickened up into a syrup by boiling off the water using steam in a process called evaporation. Sometimes the syrup is cleaned up again but more often it just goes on to the crystal-making step without any more cleaning. The evaporation is undertaken in order to improve the energy efficiency of the factory.
Boiling
The syrup is placed into a very large pan for boiling, the last stage.
In the pan even more water is boiled off until conditions are right for sugar crystals to grow.
The syrup is placed into a very large pan for boiling, the last stage.
In the pan even more water is boiled off until conditions are right for sugar crystals to grow.
This is a critical process that determines final product's yields.
Small-scale producers in Asian countries perform it in large pans over open
fires or simple furnaces. It is essential to use clean pans and tools, for once
the juice has been heated, impurities would speed the sugar-inversion process, and lead to reduced yield of sucrose/ sugar. Therefore, the
boiling pans and tools should be thoroughly cleaned between uses.
Sediment settles to the bottom of the pan during boiling and is dredged out. Scum rises to the top and is skimmed off. (These wastes can be used to feed cattle). The end point of the boiling process corresponds to a Brix (sugar content) of 90-95%.
In the factory the
workers throw in some sugar dust to initiate crystal formation. Once the
crystals have grown the resulting mixture of crystals and mother liquor is spun
in centrifuges to separate the two, rather like washing is spin dried. The
crystals are then given a final dry with hot air before being packed and/or
stored ready for despatch.
Storage
The final raw sugar forms a sticky brown mountain in the store and looks rather like the soft brown sugar found in domestic kitchens. It could be used like that but usually it gets dirty in storage and has a distinctive taste which most people don't want. That is why it is refined when it gets to the country where it will be used. Additionally, because one cannot get all the sugar out of the juice, there is a sweet by-product made: molasses. This is usually turned into a cattle food or is sent to a distillery where alcohol is made.
The final raw sugar forms a sticky brown mountain in the store and looks rather like the soft brown sugar found in domestic kitchens. It could be used like that but usually it gets dirty in storage and has a distinctive taste which most people don't want. That is why it is refined when it gets to the country where it will be used. Additionally, because one cannot get all the sugar out of the juice, there is a sweet by-product made: molasses. This is usually turned into a cattle food or is sent to a distillery where alcohol is made.
Power
So what happened to all that fibre from crushing the sugar cane? It is called "bagasse" in the industry. The factory needs electricity and steam to run, both of which are generated using this fibre.
So what happened to all that fibre from crushing the sugar cane? It is called "bagasse" in the industry. The factory needs electricity and steam to run, both of which are generated using this fibre.
The bagasse is burnt in large furnaces where a lot of heat is given out which can be used in turn to boil water and make high pressure steam. The steam is then used to drive a turbine in order to make electricity and create low pressure steam for the sugar making process. This is the same process that makes most of our electricity but there are several important differences.
When a large power
station produces electricity it burns a fossil fuel [once used, a fuel that
cannot be replaced] which contaminates the atmosphere and the station has to reject
to atmosphere a lot of low grade heat. All this contributes to global warming.
In the cane sugar factory the bagasse fuel is renewable and the gases it
produces, essentially CO2, are more than used up by the new cane
growing. Added to that the factory uses of low grade heat [in a system called
co-generation] and one can see that a well run cane sugar factory is
environmentally friendly.
Refinement
of sugar
Affination
The first stage of processing the raw sugar is to soften and then remove the layer of mother liquor surrounding the crystals with a process called "affination". The raw sugar is mixed with a warm, concentrated syrup of slightly higher purity than the syrup layer so that it will not dissolve the crystals. The resulting magma is centrifuged to separate the crystals from the syrup thus removing the greater part of the impurities from the input sugar and leaving the crystals ready for dissolving before further treatment.
The first stage of processing the raw sugar is to soften and then remove the layer of mother liquor surrounding the crystals with a process called "affination". The raw sugar is mixed with a warm, concentrated syrup of slightly higher purity than the syrup layer so that it will not dissolve the crystals. The resulting magma is centrifuged to separate the crystals from the syrup thus removing the greater part of the impurities from the input sugar and leaving the crystals ready for dissolving before further treatment.
The liquor which
results from dissolving the washed crystals still contains some colour, fine
particles, gums and resins and other non-sugars.
Carbonatation
The first stage of processing the liquor is aimed at removing the solids which make the liquor turbid. Coincidentally some of the colour is removed too. One of the two common processing techniques is known as carbonatation where small clumps of chalk are grown in the juice. The clumps, as they form, collect a lot of the non-sugars so that by filtering out the chalk one also takes out the non-sugars. Once this is done, the sugar liquor is now ready for decolourisation. The other technique, phosphatation, is chemically similar but uses phosphate rather than carbonate formation.
The first stage of processing the liquor is aimed at removing the solids which make the liquor turbid. Coincidentally some of the colour is removed too. One of the two common processing techniques is known as carbonatation where small clumps of chalk are grown in the juice. The clumps, as they form, collect a lot of the non-sugars so that by filtering out the chalk one also takes out the non-sugars. Once this is done, the sugar liquor is now ready for decolourisation. The other technique, phosphatation, is chemically similar but uses phosphate rather than carbonate formation.
Decolourisation
There are also two common methods of color removal in refineries, both relying on absorption techniques with the liquor being pumped through columns of medium. One option open to the refiner is to use granular activated carbon [GAC] which removes most colour but little else. The carbon is regenerated in a hot kiln where the colour is burnt off from the carbon. The other option is to use an ion exchange resin which removes less colour than GAC but also removes some of the inorganics present. The resin is regenerated chemically which gives rise to large quantities of unpleasant liquid effluents.
There are also two common methods of color removal in refineries, both relying on absorption techniques with the liquor being pumped through columns of medium. One option open to the refiner is to use granular activated carbon [GAC] which removes most colour but little else. The carbon is regenerated in a hot kiln where the colour is burnt off from the carbon. The other option is to use an ion exchange resin which removes less colour than GAC but also removes some of the inorganics present. The resin is regenerated chemically which gives rise to large quantities of unpleasant liquid effluents.
The clear, lightly
coloured liquor is now ready for crystallisation except that it is a little too
dilute for optimum energy consumption in the refinery. It is therefore
evaporated prior to going to the crystallisation pan.
Recovery
The liquor left over from the preparation of white sugar and the washings from the affination stage both contain sugar which it is economic to recover. They are therefore sent to the recovery house which operates rather like a raw sugar factory, aiming to make a sugar with a quality comparable to the washed raws after the affination stage. As with the other sugar processes, one cannot get all of the sugar out of the liquor and therefore there is a sweet by-product made: refiners' molasses. This is usually turned into a cattle food or is sent to a distillery where alcohol is made.
The liquor left over from the preparation of white sugar and the washings from the affination stage both contain sugar which it is economic to recover. They are therefore sent to the recovery house which operates rather like a raw sugar factory, aiming to make a sugar with a quality comparable to the washed raws after the affination stage. As with the other sugar processes, one cannot get all of the sugar out of the liquor and therefore there is a sweet by-product made: refiners' molasses. This is usually turned into a cattle food or is sent to a distillery where alcohol is made.
Ethanol Production:
It is expected
that 5% bio-ethanol will be blended with petrol sold in all the States and UTs
of the country.
The EBP
Programme is presently being implemented in a total of 13 States with blending
level of about 2% against a mandatory target of 5%.
A stable EBP
programme would ensure sustainable benefits for the sugarcane farmers across
the nation. It will ensure an alternative market for the farmers who frequently
get adversely affected in case of bumper crop of sugarcane and lack of its
demand in the market. It will also provide an incentive to small and medium
farmers to increase efforts towards sugarcane crop as better returns would be
ensured.
Procurement of
ethanol at a price determined by the market will ensure stability. EBP
programme not only provides opportunities to sugarcane farmers, but it also
ensures the use of ethanol as bio-fuel in a big way which is environment
friendly. Besides, to the extent of implementation, this reduces the dependence
on imported crude and leads the nation ahead on fuel self-sufficiency.
The Cabinet
Committee on Economic Affairs has approved the issue of pricing for bio-ethanol
procurement by Oil Marketing Companies (OMCs) for Ethanol Blended Petrol (EBP)
Program as per following:
i. The 5%
mandatory ethanol blending with petrol as already decided by the CCEA in the
past, should be implemented across the country, for which the Ministry of
Petroleum & Natural Gas will immediately issue a gazette notification, for
the OMCs to implement from the 2012-13 sugar season, effective from 1st
December, 2012.
ii.
Procurement price of ethanol will be decided henceforth between OMCs and
suppliers of ethanol.
iii. In case
of any shortfall in domestic supply, the OMCs and Chemical companies are free
to import ethanol.
Cogeneration:
Co-generation is the concept of producing two forms
of energy from one fuel. One of the forms of energy must always be heat and the
other may be electricity or mechanical energy. In a conventional power plant,
fuel is burnt in a boiler to generate high-pressure steam. This steam is used
to drive a turbine, which in turn drives an alternator through a steam turbine
to produce electric power. The exhaust steam is generally condensed to water which
goes back to the boiler.
As the low-pressure steam has a large quantum of
heat which is lost in the process of condensing, the efficiency of conventional
power plants is only around 35%. In a cogeneration plant, very high efficiency
levels, in the range of 75%–90%, can be reached. This is so, because the
low-pressure exhaust steam coming out of the turbine is not condensed, but used
for heating purposes in factories or houses.
Since co-generation can meet both power and heat
needs, it has other advantages as well in the form of significant cost savings
for the plant and reduction in emissions of pollutants due to reduced fuel
consumption.
Even at conservative estimates, the potential of
power generation from co-generation in India is more than 20,000 MW. Since
India is the largest producer of sugar in the world, bagasse-based cogeneration
is being promoted. The potential for cogeneration thus lies in facilities with
joint requirement of heat and electricity, primarily sugar and rice mills,
distilleries, petrochemical sector and industries such as fertilizers, steel,
chemical, cement, pulp and paper, and aluminum.
The Benefits
of Cogeneration
Provided the
cogeneration is optimized in the way described above (i.e. sized according to
the heat demand), the following benefits can be obtained:
1.
Increased
efficiency of energy conversion and use
2.
Lower emissions to the environment, in
particular of CO2, the main greenhouse gas
3.
In some cases, biomass fuels and some
waste materials such as refinery gases, process or agricultural waste (either
anaerobically digested or gasified), are used. These substances which serve as
fuels for cogeneration schemes, increases the cost-effectiveness and reduces
the need for waste disposal.
4.
Large cost savings, providing additional
competitiveness for industrial and commercial users while offering affordable
heat for domestic users also
5.
An opportunity to move towards more
decentralized forms of electricity generation, where plants are designed to
meet the needs of local consumers, providing high efficiency, avoiding
transmission losses and increasing flexibility in system use. This will
particularly be the case if natural gas is the energy carrier
6.
An opportunity to increase the diversity of
generation plant, and provide competition in generation. Cogeneration provides
one of the most important vehicles for promoting liberalization in energy
markets.
Process flow diagram of a sugar plant as a complete
system in shown in figure 3.0. System thinking enables us to consider the entire
system as a unit to handle the issues of sugar production along with
(i)
Efficient management of quick deliver of harvested
sugarcane for crushing,
(ii)
Use of excess bagasse for power genreation in a
cogenration plant.
The decision making regarding the capacity of the cogenration
plant is dependent on the avialiblity of surplus bagasse.
(iii)
Refining of the brown sugar to white sugar based on the
customer demand and market requirement.
(iv)
Efficient converison of molasses to produce fuel ethanol to blend with gasoline.
Reference:
1. Thinking in Systems by Donella H.
Meadows, v.13, Sustainabilty Institute.
2. Systems Thinking: The fifth
discipline of Learning Organizations by Marty Jacobs, March 19, 2008, Systems
in Sync.
3. Leadership and Systems Thnking by
Col. George E. Reed, Defense AT&L: May-June 2006, USA.
4. http://www.sugarindustry.com/sugarprocess.htm
5. http://en.wikipedia.org/wiki/Sugar_refinery
6.
