Energy
Efficiency Improvement for Reducing Carbon Foot-Prints of Refineries
Anand Kumar
Director (R&D)
Indian Oil Corporation Limited
Till
July’98, we used to process crude oil purchased, at about $ 10/bbl. It was
August 1998, when the crude oil prices started looking up and its price peaked
to $ 137/bbl during May this year. More than 13 times increase, in just 10
years. Today, the world economy and industrial growth, is daunted by the
spiraling crude oil prices, scaling new peaks every week, with no relief in
sight and there is no major oil discovery to supplement, ever increasing
supply-demand gap, topped up by experts predicting crude oil prices reaching $
150/bbl soon, and $ 200/bbl, sooner than you think.
Another
point of great concern is the Climate Change
due to Greenhouse gas (GHG) emissions, which will dictate energy usage: its
type, quality and quantity. All these will govern the type of technologies to
be used, which will make the growth and life, both, sustainable. We need energy
for sustaining growth, but we need to cut down on GHG emissions. We know
that the fuels and emissions are almost directly proportional. Higher the fuel,
higher the emissions. The challenge is to reduce emissions for the same amount
of fuel, thus even for higher fuel consumption, the emissions has to be much
lower than what it is now.
Thus,
the efficiency of any machine or technology needs to be defined in a radically
new way. Efficiency shall no more be defined as ratio of out put to input,
but it will be the ratio of emissions from output to input. In fact, I
would like to go a little further, and compare technologies and operations,
based on their life cycle emissions or carbon footprints.
Today,
on the World Environment Day, the UNEP, has very rightly, selected the theme to
ACT on to reduce our Carbon Footprints.
As
we all love our life and that of our children and that of this planet, which
supports our lives, all concerned people and companies have started to adjust
their activities, and develop new strategies with proactive approaches to
reduce their carbon footprints.
One
of many ways of reducing carbon footprint, is to keep shifting the goal post of
efficiencies of plants, equipments, and technologies, and do it faster than
what we have been doing till now. Today, 80 to 85 % of transport fuel
requirement is met by the fossil fuels supplied by the oil companies, of
which, almost 99 % of liquid fuels are the refined products, produced at our
refineries.
Petroleum
consumption in India
may quadruple by 2030-31 from its current level. The Indian refining capacity
is all set to increase faster, i.e from current capacity of 2.98 mmbpd to 4.83
mmbpd by 2015. Therefore, the refineries and the refinery technologists, have to
play greater role in improving the redefined efficiencies of their processes and
fuels.
In
future, Oil companies which are able to improve energy efficiencies of existing
processes and adopt technologies, which are energy efficient and environment friendly,
will only be able to sustain their businesses.
Refining
operations are as such energy intensive. Further, demand for high quality fuels
and necessity to process cheaper, high sulfur and heavy crudes, are forcing
refiners to adopt more and more hydro-processing units, which further increase
energy intensity of the refinery. A large variety of opportunities exist within
petroleum refineries to reduce energy consumption, while maintaining or
enhancing the productivity of the plant. However, selection of the most
favorable energy efficiency opportunities will be refinery specific, which are
always based on detailed study and analysis.
Most
of the refinery fuel is used in furnaces and boilers. While efficiencies
of boilers have gone up to 92-93 %, the efficiency of hydrocarbon furnaces
leaves scope for further improvements. Most of the refineries have already
implemented APH systems, especially in Crude Distillation furnaces to increase
efficiencies from around 75% to 90 %. There is still scope to increase it to 92
%+ and it must be done at the earliest.
The
technologists have to come out with still more efficient PAH systems and
burners for the furnaces and boilers. It may even call for changing the stacks
and stack metallurgy, in order to increase the heat recovery from the flue
gases.
It
is not one time investment. We need to continue to maintain these levels of
efficiencies and keep them improving. For this, following best practices to be
adopted to maintain the furnace / boiler efficiencies at design level:
o
Regular
operation of soot blowers
o
Periodic,
but regular, chemical cleaning of flue gas side surfaces to minimize
deposition in convection and radiation zones
o
Use
of right type of fuel oil filters and heater for better burner operation
o
Ensuring
good fuel atomization at all times
Maximisation of feed
preheat in process
units is another area, which refiners should constantly review. Whenever a plant
undergoes revamp, with attendant changes in feed rate, quality etc, Pinch
technology must be applied to identify the bottleneck of highest efficiency of
plant and equipment and the same to be removed. It has to be made part of the
monitoring and optimization systems of the refineries.
Low level heat recovery should also engage the attention of
refiners. A case in point is use of column overhead vapors for heating crude
oil as implemented only in some of the Indian refineries. Feasibility of
heat integration between process units should also be considered at design
stage itself with use of hot feed in down stream process units instead of
cooling, storage and reheating.
Best
practices to be followed in this area are;
o
Periodic
performance monitoring of heat exchangers trains and coolers
o
Periodic
chemical cleaning of heat exchangers.
o
Isolating
and cleaning of fouled exchangers
o
Maintaining
water velocities in condensers and coolers
o
Maintaining
cooling water quality through effective cooling water management program
o
Back
flushing of coolers and condensers, whenever required
Maintaining
optimum reflux ratios, low pressure operation, wherever possible, optimizing
pump arounds are some of the operational best practices, which can reduce
energy consumption. Advanced
process control techniques have already been implemented in many refineries
for optimization of yield and energy consumption.
Hydrogen management in refineries can significantly
reduce operating cost as well as energy consumption in hydrogen production. Use
of hydrogen rich off gases in process units directly in other hydroprocessing
units, wherever possible or recovery of hydrogen from off gases through PSA are
economical options available for refineries.
Modern
FCC designs use power recovery turbines
or turbo expander to drive compressor/ air blower. Power recovery turbines have
already been installed in Hydrocrackers.
Use of hollow FRP fan blades in cooling towers/ air coolers have
significantly reduced energy consumption. Variable
frequency drives are increasingly adopted in air coolers as well as ID/ FD
fans for energy savings. A survey can be organized to identify pumps where
higher pressures are generated than required for reduction of impeller size.
To reduce Fugitive Emissions, use of double mechanical seals
in pumps for light hydrocarbon services, like LPG, naphtha has become a rule,
which improves safety as well.
Efficiency improvements in steam
generation,
distribution and end-use provide major energy savings. Steam can be
economically generated through waste heat recovery from flue gases and
cogeneration with power from gas turbines. The co-generated steam can further
be used to drive steam turbine for additional power. Pressure reduction through
PRVs should be avoided and use of back pressure turbines should be considered
especially for services where turbo drives are preferred due to process safety
considerations. Installation of capacitor banks for improving power factor also
results in energy efficiency improvement.
Condensate recovery is one area which has been neglected
in most of the refineries. Condensate recovery at different pressure levels can
generate additional flash steam at lower levels and hot liquid condensate can
be used directly as make up to de-aerators. This will have additional benefit
of cost and energy reduction in production of DM water. Use of proper selection
of steam traps and their maintenance is key to saving precious steam.
Double seals in floating roof tanks, vapour recovery from tank wagon and
truck loading areas are some of measures that should be adopted to minimize
fugitive emissions. Use of Zero leak control valve (class VI) where required
can significantly reduce refinery flaring.
Flare gas recovery (or zero flaring), and new ignition systems with
low-pilot-gas consumption can reduce the amount of flared gas considerably.
Proper selection of insulations
like mattresses, pre cast insulation for low temperature applications and
calcium silicate insulation for high temperature applications can considerably
reduce heat losses.
An organization-wide energy management
program is essential
to create a foundation for improvement and to provide guidance for managing
energy. This typically involves establishing an energy policy, creating a
cross-functional energy team, developing a baseline performance, benchmarking
to set goals for improvement, implementing energy saving schemes and assessing
performance through regular reviews. Periodic energy auditing through in-house
as well as external consultants and setting higher benchmarks is necessary to
keep pace with best in the world. Improvement in energy efficiency will
minimize carbon foot prints in refinery operations. Carbon credits could also
be gainfully utilized through CDM to economically justify some of the energy
conservation projects which otherwise are not viable.
The
performance of refineries of future shall, besides many other factors, shall be
measured by its carbon footprints. We need to start transforming our refineries
by taking them in to future, by adopting low carbon process and technologies
and by supporting transport and auto sector to leave minimum carbon foot print.
Their carbon footprint will include refiners and marketers as well.
The
refineries, in order to leave behind a very faint carbon footprint has to make
their products carbonless, and operations with ZERO EMISSION, A TOTAL
RECYCLE OF ITS EFFLUENTS, and today is the auspicious day to start.
I we should rivers and sea to generate Electricity seems like the cheapest way, as you do not have to invest anything :)
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