Get documents about "Tata Steel harvests hydrogen
Document Sample
INNOVISTA
Tata Steel harvests hydrogen
S
teel-making can be a dirty The idea promised immense
business. The global steel potential. If it worked, hydrogen could
industry is a big emitter of be cheaply generated from water
greenhouse gases, producing 1.9 tonne instead of fossil fuels by using the heat
of carbon dioxide for every tonnes of already trapped in the hot slag.
steel produced. The question of how to Tata Steel’s R&D department
reduce this very large carbon footprint carried out a feasibility study of this
has for long been a prime concern for hydrogen harvesting (H2H) process.
steelmakers. One rather unique The hydrogen harvesting team
solution came up in the course of a consisted of members from research
casual conversation between Tata Sons and development, ferro alloys plant,
Chairman Ratan Tata and Tridibesh Bamnipal; Corus RD&T, IJmuiden; Tata
Mukherjee, deputy managing director, growth shop (TGS); steel-making shop;
Tata Steel, in August 2005. rawmet ferro-chrome and the project
A year earlier, Mr Tata had been monitoring committee. The team first
appointed by the Government of India looked at the thermodynamic
to head its national task force on the calculations of the different reactions
use of hydrogen as an alternative fuel. and tried to determine if the idea had
Hydrogen is considered to be a potential. The report was a
clean and green fuel as it burns without disappointment as it indicated that the
adding greenhouse gases to the gas collected would not be adequate to
atmosphere. Unfortunately, the make the process viable. However, it
commercial production of hydrogen is was decided to conduct a trial, a
still highly dependent on fossil fuels, decision that eventually proved to be
which implies another vicious cycle of the right one. The R&D lab trial with
depletion of natural resources and about 15kg of slag was an unexpected
increases in greenhouse gases. success. The gas collected contained
While chatting in the car on the about 23 per cent hydrogen, along with
way to Kolkata airport, Mr Mukherjee a mix of other gases, including air that
PROMISING suggested to Mr Tata the possibility of gets sucked in during the collection.
hydrogen formation during water This result was enough to
INNOVATION quenching of molten slag. Slag, a by- convince the team of the path-breaking
The company has come up with a product of the steelmaking process, is potential of the idea. They moved into
process that uses waste heat of discharged at temperatures well above top gear, looking for ways to improve
molten slag generated in the steel- 1,500oC. When water is added at this the efficiency of the hydrogen
making process to split water stage, it breaks down into hydrogen and collection, while keeping capital and
molecules (H2O) to collect oxygen molecules, and the oxygen gets operational expenditures low. Fresh
hydrogen that can be used as a trapped by the metal in the slag, thus experiments were conducted over the
low-cost, green fuel. making it theoretically possible to collect next two years with the help of
the hydrogen gas generated. members from the steel-making shop
44 Ta t a R e v i e w O c t o b e r 2 0 0 9
(LD#2), TGS, and ferro alloys and
minerals division (FAMD), with
each yielding higher percentages
of hydrogen.
Innovation
Integrated steel plants use the basic
oxygen-based process of steel-making,
thus producing large volumes of slag, as
much as 120-150kg of slag per tonne of
steel. This slag has to be cooled, but the
granulation or quenching processes that
are normally used for cooling slag are
not environment-friendly. There is a
significant amount of heat (about 550kJ
/ kg of slag) and chemical energy
available in the molten slag that is wasted
The Tata Steel team being awarded by Mr Tata for their innovation, hydrogen harvesting, in
in the cooling processes.
the ‘Promising innovation’ category at the JRD QV Award 2009 function in Mumbai
In Tata Steel’s novel H2H process,
hydrogen-rich gas is produced by critical issues in the selection of in its purest form.
thermo-chemical decomposition of materials. The team had set self-imposed The success of the hydrogen
water in the presence of catalytic fluxes. critical rules like minimum disturbance harvesting process has several
The hot slag plays two roles: (1) It to plant operations, no additional energy remarkable implications for the steel
provides heat for the water decomposition input and low Capex and Opex. Team industry:
reaction, (2) It prevents the reverse members from TGS helped in the design It creates a clean fuel source at
reaction between hydrogen and oxygen and fabrication of pilot and online a low cost by using waste heat
gases as the metal particles and sub- demonstration set-ups. The harsh and waste water.
oxides present in the slag react with the conditions in the reactor make it difficult Hydrogen fuel cells are a new
oxygen. to determine what is happening inside product area with uses in
the H2H reactor. This understanding was transport and other industries.
Hurdles necessary for the optimisation of the The process has the potential of
The main and critical challenge to process and design parameters. The team increasing revenue as well as
the hydrogen harvesting project was finally opted for simulation of the added benefits in terms of carbon
that of safety. The team had to work conditions inside the H2H reactor, using credits and patents.
with molten slag at temperatures above computational fluid dynamic modelling The gas can be used as a fuel in
1,500oC, plus the mix of gases generated tools, with the help of Tata Research drying furnaces, reheating
in the slag-quenching process — Development and Design Centre, to furnaces, ladle pre-heaters, captive
hydrogen and carbon monoxide — are simulate the rate and flow of products of power plants, etc. With this,
not only explosive in nature, they are various reactions inside the reactor. consumption of coal and other
also extremely toxic. The set-up design fossil fuels reduces and CO2
had to be thoroughly checked for Success emissions can come down by
various safety aspects such as gas The team spent a total of four about 25kg / tonne of steel.
leakage, explosive pressure release years working out the dynamics of the The process makes steel-making
mechanism, no water entrapment in process. In 2007, when they worked technology more environment-friendly
molten slag zone, etc. Hazard assessment with 10 tonnes of slag, they managed to by reducing energy consumption and
studies and safety checks were carried collect a gas that had 70 per cent release of smoke and gases into the
out at every stage. This planning, along hydrogen. atmosphere, and improving working
with the efforts of the team to follow and Meanwhile, the R&D team conditions.
maintain safety standards at every stage, continued to find ways to optimise The R&D team has filed four patents
resulted in an accident-free, safe and the results. An online plant for the process. The benefits of the
successful project. demonstration at the Bamnipal process are so remarkable that other
Another challenge was the design ferro-chrome plant of Tata Steel in industries are interested in understanding
and fabrication of the pilot set-up. The Orissa in March 2009 achieved 78 per this process technology. Tata Steel’s
high temperature of molten slag, cent hydrogen. Today the team is hydrogen harvesting process is indeed a
explosive gas mix, corrosive atmosphere, certain that with further improvements, big step forward towards a cleaner,
and cyclic nature of the process were they can capture 95 per cent hydrogen greener metallurgical industry.
Arvind Sridhar
Ta t a R e v i e w O c t o b e r 2 0 0 9 45
Related docs
