1. M. Nageswar Rao,
Sr.Mgr.(EMD)
Date: 09.10.2015
Venue: EDC, Simhadri

2. Presentation layout
 Need for Hydrogen
 Facts & Merits of Hydrogen
 Technologies of Hydrogen production
 Hydrogen generation at Simhadri
 Safety aspects
 Statutory requirements
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3. Need for Hydrogen
 Generator cooling
 Stator core
 Rotor core
 Rotor winding
3

4. Facts about hydrogen
 Lightest element
 Atomic number 1.
 Density of Hydrogen =0.07
 Most abundant element in the Universe. Not
naturally found in atomic state on earth. Bound to
other elements as Compound.
 Normal boiling point of – 253°C (- 423°F)
 Flammable
 Colourless & Odorless
 Non Toxic & Non Corrosive
4

5. Merits of hydrogen
 Thermal conductivity 5 times more than air.
 Higher specific heat
 3.42 at 0 degC as compared to 0.237 of air.
 538 degC is ignition temp in air.
 Low density& light gas (14 times lighter)
 Very good heat transfer property.
 Less drag, Low windage & frictional losses.
 Better circulation.

6. BUT ITS MIXTURE WITH AIR IS
EXPLOSIVE
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7. Technologies of H2 production
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 Electrolysis of water
 Electro-chemical cell
 Natural H2 extraction

8. H2 production in Simhadri
 Alkaline Electrolysis
 Suited for stationary applications
 produce high purity hydrogen.
 significantly costlier.
 High rate of gas generation
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9. Alkaline Electrolysis
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10. Inputs required
 DM water (Conductivity < 1 μS/cm)
 Rectifier (Direct current)
 KOH electrolyte solution (Caustic Potash Solution
sp.gr. of 1.25 @15.5degC) – increase conductivity
 Cooling water
 Instrument Air
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11. Process flow
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12. Process flow
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13. Main components
 Rectifiers : Make M/s HIND, (DC 9V, 2270A)
 Electrolyser (Stuart Cell)
 Gas Holders (Liquid Floating Type)
 Compressors (Diaphragm Type)
 Purification Skid
 Manifold
 Vacuum Pump
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14. Rectifier
Parameter Rating
Input 3-ph, 415V ac, 45A
Output DC 9V,
2270A (20% -100% operating range),
6pulse o/p
Type of control Constant current by means of SCR
Specification IEC-146
Cooling Air forced (Rectifier & control panel)
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15. Rectifier
 6-pulse centre-tap
converter with Inter
group reactor.
 It is formed by 2 no.s of 3-
ph half wave converters
with a phase shift of л
connected in parallel
through IGR.
 Each SCR conducts for
2 л /3 (л /3 if no IGR)
 IGR absorbs
instantaneous Potential
difference between
common cathodes.
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16. Stuart Cell
 Sealed Unipolar type Cells
 3- plate cell having
 1 nickel plated iron anode plate
 2 iron cathode plates
 MOC: Mild Steel / IS: 2062 / 1079
 KOH solution (concentration of 28-
30%)
 Low Voltage system to ensure safe
condition (2.2 volts Each)
 Capacity : 3.75 cum/hr @2800A
 Two streams in service
 Capacity 2X 3.75 =7.5 cum/hr
 Generated H2 Gas Purity > 99.8%
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17. Gas holder
 Two gas holders
 One for receive gas from
generation
 Other for supply gas to the
compressors.
 Buffer vessel
 Water sealed liquid floating
 MOC : mild steel
 Tank & Bell construction
 Operating Pressure 125 mmwc
 Limit Switches on both high and
low levels of the tank to
maintain right amount of Gas
within the vessel with all
necessary interlocks.
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18. Compressors
 Diaphragm Type
 Two Stage compression
 1 st 20 kg/cm2
 2nd 170 kg/cm2
 Isothermal Process of
compression
 Hydraulic oil is the
motivating force
 Cap: 4.7 cum/hr (Each)
 Two in service , One as
stand by.
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19. Purification skid
 Removal of O2 impurity in H2
gas by means of a Catalytic
purifier (Palladium based).
 Coalescing Filters to remove
moisture in H2 gas.
 Dual Tower regenerative
Desiccant Dryer (Molecular
Sieve) to achieve the necessary
Dew Point.
 Filters to remove particulate
carry over traces in the product
H2 gas
 Generated H2 gas
 purity > 99.99% ,
 Due point < - 40 Deg.C.
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20. Manifold
 Filling of high purity H2 in
cylinders at high pressure @
140 kg /cm2
 Provision for connecting to
vacuum pump for ensuring
“No foreign gas/ positive
hydrogen
 Provision for venting to
atmosphere in case of purity
less than required.
 Maintain positive pressure in
hydrogen cylinder to prevent
introduction of air
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21. Process parameters
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Parameter Value
DM water conductivity < 4 μS/cm
Sp.gr. of electrolyte KOH 1.20 -1.23
Cell voltage 2.2V
Current 2000Amps
Operating Temp 50 degC
Purity >99.99%
Dew point < -40 deg C
Filled Cylinder Pressure 140kg/cm2

22. Generation capacity
 Generation @ 2800A
 Hydrogen (99.8%) : 7.5 cum/hr
 Oxygen : 3.75 cum/hr
 Bottling
 Hydrogen (>99.9%) : 1 Cyl @ 140 kg/cm2
 Oxygen : To vent
 Daily average : 5-6 Cyls.
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23. Safety aspects
 KOH is strong Alkali , hazardous,
Use PPE Ensure Availability of
Emergency Shower
 Oxygen generated is combustible &
hence to be vented . Ensure no
open flames near venting area.
 H2 is flammable and may form
mixtures with air that are
flammable or explosive.
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24. Statutory Requirements
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License/ Testing Frequency
License from ministry of explosives
for
• Generation
• Filling
• Storage
• Night Shift operation
Expiring on
30.09.2015
Hydro static Stretch test of Cylinders
@250kg/cm2
Every 5 years

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