coal technology

Transcription

coal technology

EBS 425/3 -Mineral Perindustrian
Fossil fuel (Coal)
TEKNOLOGI ARANG BATU – PART II
Coal Processing
Coal that is going to be burned in solid form may go through a variety of
preparation processes. The simplest of these is removing foreign material and
screening for size. Large pieces may be crushed, or the whole mass pulverized
to a certain size. Coal can also be washed or cleaned to remove contaminants. It
is also possible to turn solid coal into a gas or liquid fuel, but these are much
more complex processes, sometimes called clean coal technologies. Coal that
is going to be used in steel making is processed into coke.
Coal Transport
Domestically, coal is moved primarily by barge and rail, although it may initially
move by truck from the mine. In many cases it is transported long distances, for
one of two reasons. First, a particular type of coal may be needed far from
where it is found. Examples include coal with a low sulphur content that reduces
sulfur dioxide emissions, and special coal used to make steel. Second, a lot of
coal is burned to make electricity in places where no coal is found locally, so it
has to be brought in. In addition, some coal is exported by ship, mostly for steel
making in other countries
Calculate coal reserves for each coal bed:
This is the complicated part; most people would hire a registered consulting
geologist or registered mining engineer for this. The process is explained here,
in simplified terms. Each step is done separately for each of the coal beds under
consideration. The first step is to gather as much coal thickness information as
possible for the target coal bed. Information may be obtained from the Mineral
and Geosciences department. Coal Thickness Data Base, and files of local coal
companies, and neighbours and by examining outcrops, digging out the coal,
and possibly drilling boreholes (drilling can be paid for by interested companies).
After coal thickness data are gathered, a map showing coal thick ness trends
(isopach map) is constructed for the target bed. Property lines and the target
coal-bed outcrop lines are added to the map. Next, the area for each thickness
class must be measured (generally in acres). This process is called planimetry.
Planimetry measures the area of the property. With the area and thickness
known, a volume of coal can be calculated, and from this volume, a total
tonnage can be derived. Planimetry can be done by hand using several methods,
but the most accurate is with a mechanical device called a planimeter.
Planimetry can also be done accurately by a computer using special software.
From the calculated areas and the projected thickness trends, a gross reserve
estimate can be calculated; for bituminous coal, there are 1,800 tons for every
acre for every foot of coal (e.g., if you have 2 acres of 2-foot-thick coal, then
you have 7,200 tons of that coal). Many other factors must also be examined to
determine what the coal is worth: quality, mineability, transportation, available
market, etc.
Disedia oleh : Dr. Kamar Shah Ariffin ( 6/30/2003)
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Fossil fuel (Coal)
ENERGY SOURCES
Important properties and Use of Coal
The chief uses of coal mined in the world are electricity generation, heat, and
coking coal for iron and steel making. As an example, in Kentucky,US, 81% of
coal is used to generate electricity. Each of these uses has specific
requirements, but generally a high Btu value, and a low sulphur, ash, and
moisture content are desirable. The important properties of coal are dependent
upon the specific industrial use of the coal. Undesirable chemical constituents in
coal such as sulfur, chlorine, sodium, and various hazardous air pollutants may
be important for some uses of coal. The washability of a coal is a property that
determines how easily these chemical constituents and the ash content of the
coal can be reduced through preparation before the coal is used. Important
handling properties include grindability, content of scaling agents (chlorine and
sodium cause scaling in boilers), and ash fusion. Ash fusion is a property that
indicates whether the ash totally melts (low ash fusion) and must be removed
from the boiler as a liquid, or forms "clinkers" or cinders (high ash fusion) that
must be removed as a solid. Boilers are designed to burn coals with specific ash
fusions for this reason.
In the past, coal had a variety of uses. Gas for gas lights was originally made
from coal in most cities. In fact in Britain this so-called illuminating gas was
made from coal until the 1950's.
Large amounts of coal were once consumed for domestic heating, railroad fuel
and for stationery steam engines. In those days coal was often mined near cities
and wherever the railroads went. Coal was once a very important source of heat
for smelting iron ore for the iron and steel industry, and still is to some degree.
In US, Coal is truly America's energy strength. It is to the U.S. what crude oil is
to Saudi Arabia.
Industrial Applications: Coal is also used in industrial processes, primarily for
steel making and cement manufacturing. Both uses can release air pollutants.
The Clean Coal Technology Program demonstrated new ways to use coal directly
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Fossil fuel (Coal)
in the blast furnaces of steel mills, rather than converting it to coke (the coking
process releases pollutants which, unless captured, can become harmful air
emissions). Another Clean Coal project tested a new type of scrubber for a
cement kiln that used previously discarded dust from the kiln as a chemical to
absorb sulphur dioxide and chlorine emissions before they escaped into the
atmosphere.
Clean Coal
Clean coal or washed coal is produced by a cleaning process (e.g., coal output
from a coal wash plant). Generally the coal is washed free of clay, shale and
other deleterious substances for transport to users.
Thermal Coal
Coal used for burning in thermal plants to generate electricity. Thermal coals
are generally in the bituminous quality range, having a lower heat content
(joules or BTU's British thermal units) than metallurgical coals, but a higher heat
content than lower grade coals, such as lignite.
Metallurgical Coal (Met Coal)
A coal which can be used to produce metallurgical coke which has a high
compressive strength at elevated temperatures for use in metallurgical furnaces,
not only as fuel, but also to support the weight of the charge (particularly in iron
and steel making).
Today, due to competition from other fuels and other sources of energy, coal is
used mostly to generate electricity. Concern over environmental quality has led
to greater use of low sulphur coal in power plants. This adversely affected
production in States with mostly high sulphur coal, but rejuvenated the industry
in some States with low sulphur coal.
Nowadays most coal is burnt at powers stations to make electricity.
Most coal mined in the world is burned to make electricity. Most people do not
realize that when they use electricity, they are probably also using coal. Of the
coal that is not used to make electricity, most is used to make steam for
heating, as coke in steel making, or is exported. In developing countries half the
world's population depends on coal for heat.
Almost all of the coal consumed in the
world is for electric power generation
by combusting the coal in boilers and
generating steam to power a turbine.
Coal is being used to a limited extent in
gasification based plants to produce gas
to fuel gas turbine based combined
cycles (IGCCs) and in some countries
such as China for chemicals synthesis.
With more advanced gas turbines under
development, coal based IGCC will have
a strong economic and environmental
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Fossil fuel (Coal)
basis to compete with boiler based power plants.
An Energy Bargain
Coal is also an energy bargain for the United
States. Historically it has been the least expensive
fossil fuel available in the country, and in contrast
to other primary fuels, its costs are likely to remain
stable or decline as mine productivity continues to
increase.
During the past decade, in fact, coal prices at U.S.
steam electric power plants actually declined about
30%, in nominal terms, while petroleum and
Average Cost of Fossil Fuels natural gas prices increased by 26% and 60%,
Delivered to Utilities, 1999 respectively.
(Cents per Million Btu)
The low cost of coal is a major reason why the
United States enjoys some of the lowest electricity rates of any free market
economy.
The Nation's Power Workhorse
Because of its abundance and low cost, coal Coal is America's Major
now accounts for more than half of the Source of Electricity
Generation
electricity generated in the United States.
The nation is likely to use more coal in the
future, especially as an expanding digital
economy creates new demands for electricity.
Even with the large projected growth in other
power generation fuels - especially natural
gas - coal will continue to supply about half
the nation's electric power for at least another
Electricity Generation by
20 years. And because of the overall increase
Fuel, 1999
in power demand, the nation will likely
(Million Kilowatt Hours)
require that 20 percent MORE coal be used by
2020.
Environmental problems of coal production and burning
Combustion
The combustion process provides tremendous
amounts of energy from a fuel and this energy
is converted or transformed producing heat for
cooking, making hot water, or to generate steam
for manufacturing or turning a turbine to produce
shaft power and electricity, to produce mechanical
motion as in an auto engine, or thrust as in an
aircraft or shaft power as in a land based engine.
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Fossil fuel (Coal)
The chemical energy contained in fossil
and biomass fuels which is released by the
combustion process consists of reactions with
oxygen contained in the air. The fuel bound
energy is first converted to thermal energy
which in turn may be converted to shaft power
and motive power in a reciprocating engine (as
in automobiles, trucks, busses, locomotives and
ships) or in a rotating engine such as a gas
turbine or steam turbine or propulsion energy
(as in jet and prop aircraft). The shaft power may also be used to generate
electric power which involves turning a generator connected to a reciprocating
engine or a gas turbine or a steam turbine. In institutional energy and
manufacturing applications where heat energy is required, the combustion
process is utilized in boilers and furnaces. Internal combustion engines (diesel
engines or gas turbines) in addition to generating electricity may also be used to
provide heat energy by recovery of the energy contained in the exhaust gases.
Such a dual purpose application is called cogeneration and provides for very
efficient utilization of the fuel bound energy. Air conditioning may also be
provided from the heat utilizing an adsorption refrigeration cycle such as the
lithium bromide cycle for moderate temperature refrigeration or an ammonia
absorption cycle for deep refrigeration temperatures. A fuel cell may also be
utilized in a cogeneration mode.
Finally, the familiar barbecue is another example of the application of the
combustion process.
The combustion of fuels requires the consumption of large quantities of air. For
example, 150 Lb of a fuel (oil) requires about 2000 Lb of air and the resulting
CO2 introduced into the atmosphere is about 250 Lb. Small quantities of
pollutants such as NO, CO and hydrocarbons are also formed, these quantities
being negligible from engineering calculations standpoint but very significant
from the environmental standpoint.
Combustion Process. The combustion process involves some 1000 reactions to
complete the oxidation process forming CO2 and H2O, the ultimate products of
combustion. However, pollutants such as CO, HCs, soot, NOx, SO2 are also
formed during the combustion process as a result of the various reactions.
Carbon Monoxide (from Natural Gas Combustion). The CH4 molecule is very
stable and requires high energy atoms to break loose an H atom forming the
CH3 radical which plays a key role in propagating the combustion process. This
process includes the partial oxidation of CH4, oxidation of CO, OH reactions and
NO formation reactions. CO formation involves a number of steps but is a fast
overall reaction while the oxidation of CO to CO2 is very slow and as a result, the
auto engine produces significant amounts of CO due to the short residence time.
In a gas turbine, however, more residence time is available within the
combustor and the CO emissions are much lower. High temperatures and O2
concentrations and large residence times are required for the CO oxidation and
involves the reaction with the OH radical formed during the combustion process.
High CO emission not only means more pollution but also lower thermal
efficiency.
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Fossil fuel (Coal)
Nitrogen Oxides. The NO is produced from (1) high temperature oxidation of
molecular N2 (thermal NO), (2) hydrocarbon radical attack on the molecular N2
(prompt NO), and (3) oxidation of chemically bound nitrogen in the fuel (fuel
NO). The thermal NO, i.e., the formation of NO from the N2 present in the
combustion air requires the breaking of the covalent triple bond in the N2 and
requires very high temperatures and forms by the action of the O radical
produced during the combustion process. Increased temperature, residence
time, and O2 concentration increase NO emissions which is in direct contrast to
the conditions required for CO formation. As much as 60 to 80% of the fuel
bound nitrogen present in fuels such as oil and coal forms NO.
The NO formation reaction suddenly takes off around 2800 deg F or 1540 deg C
and thus a window of opportunity exists to control NO by staying just below this
temperature. Thermal NO formation shows an inverse relationship with respect
to HC and CO emissions when the air to fuel ratio is varied. Control strategies
include (1) burning under lean conditions, (2) staged combustion with rapid
quenching of the flame by the secondary air, (3) pre-mixed burners (ideally,
with variable geometry for varying load of the boiler or engine, and (4) flue gas
recycle. Post combustion processes are also sometimes applied but have certain
disadvantages such as transforming NO into other undesirable species. To meet
the ultra low NOx emissions being mandated, the internal structure of the
combustion process which is complex and combines fluid dynamics, turbulent
mixing, high temperature chemistry and heat transfer need to be understood to
develop new solutions without compromising efficiency at full or partial load.
The formation of NO2 is not significant during the combustion process, however
the NO oxidizes to NO2 in the atmosphere and thus all NO is potential NO2. NOx
refers to NO plus NO2. Another oxide of nitrogen, N2O which is also formed
during the combustion has become important in recent years due to its role in
the stratosphere as a greenhouse gas. It is formed in significant concentrations
(from an environmental impact standpoint) in fluidized bed combustion.
Steam Turbine
A steam turbine based power plant consists of raising high pressure steam in a
boiler from the thermal energy and expanding the steam in a turbine to
generate shaft power which in turn is converted into electricity in the generator.
Axial flow steam turbines consist of circularly distributed stationary blades called
nozzles which direct steam on to rotating blades or buckets mounted radially on
a rotating wheel. Typically, the blades are short in proportion to the radius of
the wheel, and the nozzles are approximately rectangular in cross section.
Several stages of expansions are obtained by using a series of nozzles and
buckets, with the exhaust from the buckets of one stage flowing directly into the
nozzles of the following stage. A compact machine can be built economically
with ten or more stages for optimum use of high pressure steam and vacuum
exhaust by mounting the wheels of a number of stages on a single shaft, and
supporting the nozzles of all stages from a continuous housing. Large axial
turbines must be operated under such conditions that the exhaust steam does
not contain more than 10 to 13% of liquid since condensate droplets could
seriously erode the high velocity nozzles and blades. The moisture content of
the exhaust is dependent upon the inlet steam pressure/temperature
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Fossil fuel (Coal)
combination. Special moisture removal stages may be incorporated in the design
when the steam superheat temperature is limited.
Steam may be utilized directly in the steam turbine without any superheat as
may be done with low pressure steam, or superheated to increase the cycle
efficiency. Reheat may also be included to further increase the ef ficiency of
converting heat to power by superheating the steam after partial expansion and
admitting the steam thus reheated back into the turbine.
Coal has a very complex structure and being a solid is more difficult to burn.
Coal combustion undergoes devolatilization and combustion of the released
gases, char combustion and fly ash formation which are particles 10um in size
(the low visibility around certain coal fired power plants is due to the fly ash).
Acid mine drainage
Subsidence, Global Warming
Slag (spoil), heaps Acid rain
Clean Coal Technologies
Clean Coal Technologies (CCTs) are defined as 'technologies designed to
enhance both the efficiency and the environmental acceptability of coal
extraction, preparation and use'. These technologies reduce emissions, reduce
waste, and increase the amount of energy gained from each tonne of coal.
Clean coal technologies play a key role in improving coal's environmental
acceptability and performance. Ongoing research ensures that advances are
continually being made in this area. Improvements in coal combustion efficiency
dramatically reduce emissions from coal combustion as the graph below
highlights.
Clean coal technologies are a family of new technological innovations that are
environmentally superior to the technologies in common use today. Clean coal
technologies can be new combustion processes - like fluidized bed combustion
and low-NOx burners - that remove pollutants, or prevent them from forming,
while the coal burns.
Increasing coal combustion technology efficiency from 35 to 40% reduces carbon
dioxide emissions by over 10%.
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Fossil fuel (Coal)
Clean coal technologies can be new pollution control devices - like advanced
scrubbers - that clean pollutants from flue gases before they exit a plant's
smokestack.Still other clean coal technologies can convert coal into fuel forms
that can be cleaned before being burned. For example, a clean coal plant may
convert coal into a gas that has the same environmental characteristics as
clean-burning natural gas.
In US, the Clean Coal Technology Program is primarily targeting for innovative
technologies in four major technology categories:
Advanced Pollution Controls: These devices could be installed on existing
power plants or built into new facilities. Their purpose was to provide more
effective and/or lower cost ways to reduce sulphur dioxide and nitrogen
emissions. Examples of these devices included:
•
•
•
•
•
SO2 control systems: These devices remove sulfur dioxide pollutants from
the combustion gases after they exit
the boiler.
The Pure Air Flue Gas
Scrubber
reduces
SO2
The Clean Coal Technology Program
emissions
by
95%
and
tested two basic versions of this
produces gypsum, a useable
technology:
byproduct.
One worked inside the existing
ductwork of a power plant. These
devices are suitable for smaller,
older plants with limited space for
adding equipment. Typically these
devices can reduce sulfur pollutants
by 50 to 70%.
For larger plants with the available
space, the Clean Coal Technology
Program tested advanced flue gas
desulfurization
technologies,
or
scrubbers.
These
devices
are
typically built as separate modules
and can reduce sulfur pollutants by more than 90%. In the Clean Coal
program, the advanced scrubbers were designed to remove the sulphur in an
environmentally safe, solid powder rather than the difficult-to-handle sludge
of older technologies.
NOx control technology: These devices reduce emissions of nitrogen
oxides (NOx). Three basic categories were tested:
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Fossil fuel (Coal)
•
B&W's
Low-NOx
Burner
is one of a new class of lowpolluting
burners
being
installed on nearly 75% of U.S.
coal boilers.
•
•
(1) new combustor designs (low-NOx
burners) that retard the formation of
nitrogen oxides by carefully controlling the
way coal burns. These devices reduce NOx
by 37 to 68%;
(2) "reburning" technology where
natural gas or coal is burned above the
main combustion zone in such a way that
nitrogen oxide pollutants are broken down
into harmless molecular nitrogen before
they leave the boiler. Reburning can reduce
NOx emissions by 50 to 67%; and
(3) scrubbing systems that inject
ammonia or urea into combustion flue
gases to remove nitrogen oxide pollutants.
Non-catalytic technologies can reduce NOx
by 30 to 50% while selective catalytic
systems can eliminate 80 to 90%+ of NOx.
Several Clean Coal Technology projects combined both sulphur and nitrogen
pollutant controls.
Advanced Power Generation Technologies: These were complete electric
power generating systems that offered superior efficiency and environmental
performance over conventional coal-burning systems. Four major categories of
power generating systems were demonstrated in the Clean Coal Technology
Program:
Fluidized Bed Combustion: Fluidized bed
combustors remove pollutants inside the boiler
- no scrubber or post-combustion sulfur and
nitrogen controls are needed.
Rather than burning coal as a blown-in
powder, fluidized beds mix pulverized coal with
limestone and suspend the mixture on jets of
air in a floating "bed" that resembles a boiling
fluid. The limestone removes sulfur as it is
released from the burning coal and converts it
into an environmentally benign powder. The
turbulent actions also reduces the temperature
of the combustion process below the threshold
where large amounts of NOx form. Fluidized
bed systems can reduce sulfur dioxide by 90 to
95% and nitrogen oxides by 90% or more.
The Nucla Fluidized Bed
System
helped pioneer fluidized bed
technology at utility scale.
The Clean Coal Technology Program demonstrated fluidized bed systems that
burn coal under atmospheric and pressurized conditions.
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TECO's Gasification Power
•
Plant
is one of the world's cleanest
and most fuel efficient coal
plants.
Fossil fuel (Coal)
Gasification Combined Cycle:
These
systems
depart
from
coal
combustion altogether. Instead, coal is
turned into a gas which can be cleaned of
its impurities, virtually to same levels as
natural gas. Then the gas is burned in a
gas turbine to generate one source of
electricity. Exhaust from the gas turbine is
hot enough to boil water, creating steam
to drive a steam turbine and generate a
second
source
of
electricity.
This
"combined cycle" technology offers a new
technological approach for increasing
power plant fuel efficiencies. Initial
gasification-based plants could boost
efficiencies by as much as 20% over
conventional coal-burning power plants,
and improved versions might eventually
double today's efficiencies.
Gasification combined cycle technologies are among the cleanest ways to
generate electricity from coal. As much as 95 to 99% of the sulfur and nitrogen
impurities in the coal gas can be removed by known chemical processes. These
pollutants can be converted into useable products, such as chemicals and
fertilizers.
•
•
Coal-Fired Diesel Engine: One Clean Coal Technology project is
preparing to test a diesel engine that uses coal-oil or coal-water slurry
fuel. The diesel engine would power an electrical generator to produce
electricity onsite.
Slagging Combustor: Another type of clean coal technology is a
slagging combustor, so-named because it removes the coal ash as a
molten slag in the combustor rather than the boiler. This prevents ash
from building up on the furnace walls and degrading the boiler's
efficiency. The Clean Coal Technology Program tested slagging
combustors for both industrial and utility applications.
Advanced Coal Processing: The Clean Coal Technology Program tested
several technologies for changing coal into cleaner forms of fuel.
One of the most successful projects in this category is the Liquid Phase Methanol
Process, a process in which coal gas is converted into methanol by bubbling it
through a special reaction vessel filled with catalyst particles suspended in a
liquid slurry. Methanol can be used as a fuel or as a feedstock for several
chemical manufacturing processes.
Other Clean Coal Technology projects examined ways to upgrade low-quality
coals, such as those found in the Western U.S., into fuels with much higher
heating values. One technology converted coal into both solid and liquid forms,
both of which could be burned as clean fuels. Another project developed a
personal computer software package that could assist utilities in selecting the
optimal quality coal for a specific type of boiler.
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Fossil fuel (Coal)
Coal Consumption1 and Recoverable Reserves
The following table shows the coal consumption and the estimated reserves in
1995 in some countries (multiply ST by 0.9072 to obtain MT or Mega Gram):
Country
Consumption, 10 ST
Reserves, 10 ST
Australia
123
196,630
China
1,464
126,200
Germany
284
26,455
India
327
75,009
Japan
140
886
South Korea
52
202
Mexico
12
1,300
U.S.
941
268,500
TOTAL WORLD
5,117
1,142,968
The Changing face of the U.S. Energy Needs
Year
Significant Events
1700's
Steam engine powered by wood.
1800's
Steam engine powered by coal.
Oil well drilling.
Refinement of crude oil.
Internal combustion engine.
1900's
1920's
Coal provides 80% of the Nation's needs.
~1945
Oil replaces
generation.
1990's
Fossil fuelsd provided 80% of the Nation's energy
supply.
coal
except
for
electrical
power
Some converted to coke for use in metals smelting.
Among the most important resources of an industrial society are those that
provide energy - this is what we use to drive machines and use to produce other
materials (eg. smelting of metals).
For much of history main source of energy (fuel) was wood (technically
renewable). Now fuels dominated by fossil fuels (80%) with hydro (5%) nuclear
(7%) renewables (5%)
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Fossil fuel (Coal)
Major Energy Uses for Fossil Fuels
Fuel
*Sector.......................Major use
Industrial...................Heating
Commerical................Heating
Residential.................Heating and cooking
Natural gas
Coal
Industrial...................Electrical
industrial processes
Commerical................Lighting
Residential.................Lighting
power
generation
and
All sectors.................Transportation
Industrial ..................Heating
Residential ................Heating
Oil
* Sectors arranged in descending order of magnitude.
Present day breakdown of energy supply in the U.S.
Source
Percentage supplied
Oil
44
Natural Gas
25
Coal
23
Nuclear, hydro, and all other sources 12
FORMS OF ENERGY
Energy is the capacity to do work, but is present in different forms:
kinetic: motion, heat, electricity
potential(stored): chemical, nuclear, elastic, gravitational, elecromagnetic
Can be converted from one form to another, eg.
chemical —> electrical (battery)
electrical —> kinetic (electric motor) etc etc.
Rate of consumption of energy is called power
UNITS OF ENERGY
Basic unit of energy in SI (system internationale) is the joule
One joule is defined as the energy needed to raise the temperature of one
kilogram of water by 1o C)
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Fossil fuel (Coal)
Power is the rate of use of energy or energy/time
Thus, energy = power x time
Basic unit of power - the use of one joule/second is called the watt
Other units:
Kilowatt-hour (kw-hr)= 1000 watts x 60x60 joules
1 kw-hr= 3.6 x 106 joules
Calorie = 4.18 joules
1 kw-hr = 8.6 x 105 calories
(note that a dietetic calorie, the type talked about in diets, is really a kilocalorie
- that is equal to 1000 calories!)
British thermal units (BTU)
= 252 calories
= 2.93 x 104 kw-hr = 1.053x103 joules
Quad= 10 15 BTU = 1.05 x 1018 joules = 2.93 x 1011 kw-hr
For coal
1 metric ton coal = 0.66 metric tons of oil = 5 bbl of oil
1 metric ton coal = 2.85 x 1010 joules = 7.95 x 10 3 kw-hr = 2.7 x 10 7 BTU
For petroleum
Oil is measures in barrels (bbl);
1barrel = 42 gallons(US),
7.5 barrels = 1metric ton
1bbl = 5.7 x 10 9 joules = 1.59 x 10 3 kw-hr = 5.4 x 106 BTU
SPECIFIC ENERGY OF COAL
There are two ways to express the specific energy (SE), the Gross SE and the
Net SE. The difference between the two comes from the way in which the water
in the coal is treated in the measurement of SE. The normal laboratory
measurement for SE will report the Gross SE.
When the coal is burnt, water in the coal is evaporated, and the water which is
formed from combustion of the hydrogen in the coal is also evaporated. The
heat required for evaporation of this water is the difference between gross and
net SE, and the formula to calculate the Net SE from the Gross SE is as follows:
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Fossil fuel (Coal)
It does not matter which basis (adb, daf, etc) for SE, H2O and H2 are used, as
long as they are all the same. However, the net SE is really only relevant for "as
received" or "as fired" coal.
For bituminous coals the difference between Net and Gross SE is approximately
1.0 MJ/kg (ar), or 240 kcal/kg (ar).
One Tonne of Coal
Mass Balance
Energy Balance
ENERGY CONSUMPTION PATTERNS
Energy is just like the other resources discussed - the richer consume more
than the poor. Note that much of this is not just direct consumption, but is the
energy invested in the manufacture of articles.
US with about 5% of world population consumes about 33% energy.
Reserves and Production
Estimated reserves are based on geological probabilities of existing fossil
fuels. There is no way to verify these reserves without exploratory drilling.
Proven reserves may increase or decresase with the price of oil. The extent of
the reserves is calculated from sinking numerous wells to define the extent of
the field.
Production refers to the withdrawal of the fossil fiuel from the field. It generally
limited to 10% of the remaining reserves.
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Fossil fuel (Coal)
When will fossil fuels run out?
Coal
•
•
•
•
•
•
•
the U.S. reserves are estimated at 29% of the world's supply.
Estimated to last 150-300 years even with a tripled consumption rate.
Natural gas
Methane reserves to run out sometime between 2025-2050
LPG (liquid petroleum gas) = propane and butane.
Crude oil
Estimates range from 2010-2050
Sustainable Development - the Role of Coal
Sustainable development has three inter-related pillars: economic, social and
environmental. They have equal status and an integrated approach is needed to
ensure that all can be met. Sustainable development requires secure and
reliable access to affordable energy. For the two billion people who lack it,
access to modern energy and in particular to electricity, is essential for
generating local industry and employment, alleviating poverty and improving
public health.
Coal is an essential element of global sustainable development. It is the world’s
most widely available, affordable and secure source of energy.
This section looks at the overall challenge of sustainable development and the
contribution coal makes to the three pillars of sustainable development.
Arang Batu - Bahan Api
Kandungan galian dan organan di dalam batu batan menyebabkannya
sangat bernilai daripada segi ekonomi. Batu-batan yang boleh digunakan
sebagai bahan api ialah gambut, arang batu perang (lignit), bitumen dan arang
batu wap, antrasit dan minyak galian. Bahan api ini dijadikan sebagai sumber
haba dan tenaga di rumah dan di kilang kilang. Pengkarbonan arang batu
menghasilkan arang kok dan gas arang batu. Arang kok digunakan di relau
bagas, manakala gas aran batu di unakan di rumah untuk memasak. Arang batu
melalui proses pemisahan kimia boleh menghasilkan lebih kurang 200, 000 hasil
sampingan seperti tar, minyak wangi, racun rumpai, baja, racun serangga dan
bahan letupan. Minyak galian pula menghasilkan petroleum yang sangat penting
untuk perusahaan pengangkutan dunia. Plastik adalah hasil sampingan
petroleum yang boleh dijadikan berbagai barang kerana ia ringan dan tahan
lama.
15
Page 15 of

coal technology

Transcription

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