Energy conservation techniques in ammonia and urea production plants

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17th
Aug,. 2022
DOI: 10.13140/RG.2.2.14959.10403 Research Gate is an academic social networking site
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This is an open access article, Research Gate is a European commercial social networking site for scientists and researchers
Question Answer on Energy Conservation
(Vol-1)
By
Prem Baboo
Retired from National fertilizers Ltd., India
& Dangote fertilizers Ltd., Nigeria
Abstract- G.Cal/ton of Ammonia, G.Cal/ton of
urea is the most important data in fertilizers
industries for performance evaluation. The
energy of the fertilizers is depends upon
Reformer feed & fuel. Earlier thinking
Fertilizers should be produced at any cost we
have nothing to do with energy & pollution and
what environment we don’t know? But today
time has changed. We have to meet the energy &
environment conditions otherwise penalty will
be imposed and your factory will be closed. In
this quiz we will discuss about energy. How to
reduced energy and how to reduced pollution
how to save environment? Etc. Hydrogen and
could be a boon for renewable energy demand.
But greening ammonia, the chemical primarily
used to make fertilizer, will take a lot of heavy
lifting. Green ammonia is two to three times
more expensive than gray ammonia. Depends
upon power source means where we are getting
power from, i.e. Hydro power or non renewable
source.
Q-1- What is energy in G.Cal/ton of different
ammonia plants?
Ans.- Ammonia production is a highly energy
intensive process consuming around 1.8-2.0% of
global energy output each year. Steam methane
reforming accounts for over 80% of the energy
required) and producing as a result about 500
million tons of carbon dioxide (about 1.0-2.0%
of global carbon dioxide emissions.
Following are the energy level for different Fuel
Sr.
No. Ammonia Process
Energy.
G.Cal/ton of
ammonia
Urea Energy, G.Cal Ton of Urea
Non-
Conventional(stripping)
Conventional
Process
1 For Gasification used carbon
and coke
13.5-15.5 9.85 11.31
2 For Heavy oil Feed
Gasification
11.5-14.5 8.91 10.1
3 Naphtha base reforming 9.5-11.0 6.93 8.03
4 Natural Gas based
Reforming
7.4-8.0 5.401 6.104
Table –Energy Comparison

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Fig- India Plants Ammonia Energy
Q-2- How to calculate Energy cost in
Dollar/G.Cal?
Ans.-Suppose one kg CNG cost =1 Dollar
LHV of CNG-47.141 MJ/kg=0.01126 G.Cal/kg
Cost of Energy of CNG=Dollar/G.Cal
Cost of Energy=Dollar/LHV=1/0.01126=$
88.8/G.Cal
Q-3- What is the advantages of Process
condensate stripper operation at higher
pressure? In Ammonia Plant.
Ans. – In some plants the atmospheric pressure
stripper has been installed in the first generation
gas based plants, atmospheric pressure process
condensate stripper has been provided to strip of
NH3, CO2, CH3OH and other impurities from the
process condensate generated in the plant. In this
stripper loop, the overhead condenser is finned
air cooled type and with the passage of time. In
this modification DM water preheating is taking
place from 35°C-72°C. Since further scope is
there for preheating this DM water, a scheme is
designed to preheat the DM water up to
100°C.The stripper bottom hot condensate after
heat exchange with in coming cold process
condensate is being finally cooled from 85°C to
40°C by heat exchange with cooling water
before sending to the condensate polishing unit.
Thus 5.85Gcal/hr heat is being dumped in the
cooling tower. In this modification one plate
type Heat Exchanger can be installed in series
with the earlier installed DM water preheater.
The cold DM water is preheated from 35°C to
65°C in the new preheater by heat exchange
with the hot treated condensate (which was
earlier cooled with cooling water) and finally
heated to 100°C in the over head condenser
before going to the offsite plant de-aerator. In
order to achieve the heat recovery at high temp.
level (100°C) , operating pressure of the stripper
can be raised from 0.4 kg/cm² g (at the bottom)
to 1.6kg/cm²g by installing 2 number control
valves in the vent line of top column and refuse
drum. The other small modifications can be been
incorporated to meet the new operating
conditions are the following:

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1. The CO2 loaded cold condensate
pumps can be replaced with pumps
of high discharge pressure.
2. Low pressure stream injection can
be provided in the upper column.
3. One safety valve can be installed at
the upper column.
4. Seal water coolers can be installed
for the reflux pumps.
5. LP steam injections can be
provided in the pressure transmitter
tapping, safety valve and vent lines
at the upstream of control valves.
6. All the hot lines, which is earlier
without any insulation, to be
insulated to achieve maximum heat
recovery.
After the implementation of this scheme,
LP steam consumption in the offsite de-
aerator will be come down by 9te/hr and
to match the LP steam balance, one back
pressure turbine for BFW pump cam be
stopped in the Ammonia plant.
Necessary modifications can be
incorporated to keep the turbine on auto
start mode.
Saving on account of PC stripper Change over
Sr. No. Parameters
Unit
Existing
Stripper
Proposed MP
stripper
1 Enthalpy of SM steam G cal /ton 0.760 0.760
2 Enthalpy of LP steam G cal /ton 0.690 0.690
3 SL steam requirement Te/hr 18.000 0.000
4 SM steam requirement Te/hr 0.000 30.000
5 SM Steam production Te/hr 0.000 30.000
6 DMW flow in effluent heat exchanger E-
1322 Existing
Te/hr 250.000 0.000
1322 in new proposal A-I
Te/hr 0.000 125.000
3322 in new proposal A-II
Te/hr 0.000 125.000
9 DMW rise in Temp in both cases Deg C 55.000 55.000
10 Heat duty of E-1322 Ammonia-I existing Gcal/hr 13.750 0.000
11 Heat duty of E-1322 Ammonia-I new case G cal/hr 6.875
12 Heat duty of E-1322 Ammonia-II new
cvase
G cal/hr 0.000 6.875
13 Total DWM heat duty G Cal/hr 13.750 13.750
14 SM Steam Saving Tons/hr 0.000 0.000
15 SL Steam Saving T/hr 0.000 18.000
16 Net Energy saving G.Cal/Te
Urea
0.000 0.098
Table Calculation for Energy

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Q-4- How to calculate Ammonia & Urea
Plants Energy
Ans.- Ammonia Energy
Ammonia Energy depends upon following
parameters:
1. Natural gas energy
2. Steam energy
3. Power energy
1. Natural Gas Energy
𝑁𝐺 𝐸𝑛𝑒𝑟𝑔𝑦 =
NG Consumed for ammonia Plant(Feed + Fuel)X NG LHV
Ammonia Daily Production
=G.Cal/Ton of Ammonia
2. Steam Energy – In Ammonia Steam is is exported to others(Urea, CPP etc) plants
𝑆𝑡𝑒𝑎𝑚 𝐸𝑛𝑒𝑟𝑔𝑦 =
Steam Export to other Plants(Enthlapy of HS 805)
=G.Cal/Ton of ammonia
3. Power Energy,
𝑃𝑜𝑤𝑒𝑟 𝐸𝑛𝑒𝑟𝑔𝑦
=
Power Consumed per day of Ammonia Plants X NG per mega wattX NG LHV
=G.Cal/Ton of ammonia
Now Total Ammonia
Energy=(1)+(2)+(3) G.Cal/ton of
Ammonia
UREA PLANTS ENERGY
CALCULATIONS
Urea Energy depends upon following
parameters:
1. Ammonia Energy
2. Steam energy
3. Power energy
1. Ammonia Energy= Specific
consumption of ammonia X ammonia
energy
G.Cal/Ton of Urea
2. 𝑺𝒕𝒆𝒂𝒎 𝑬𝒏𝒆𝒓𝒈𝒚 =
( )
𝟑. 𝑷𝒐𝒘𝒆𝒓 𝑬𝒏𝒆𝒓𝒈𝒚 =
Power Consumed per day of Urea Plants X NG per mega wattX NG LHV
Urea Daily Production
Total Energy of Urea=(1)+(2)+(3)
=G.Cal/Ton of Urea
DIRECT SPECIFIC ENERGY CALCULATION OF COMPLEX (If NG is used)
𝑼𝒓𝒆𝒂 𝑬𝒏𝒆𝒓𝒈𝒚 𝑷𝒐𝒘𝒆𝒓 𝑬𝒏𝒆𝒓𝒈𝒚, 𝑮. 𝒄𝒂𝒍 𝒑𝒆𝒓 𝒕𝒐𝒏 𝒐𝒇 𝒖𝒓𝒆𝒂
=
Total NG Consumption NG X LHV
Urea Daily Production
=G.Cal/Ton of Urea

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Q-5- How to calculate Pump head when
following parameters are given?
1. Pump Suction Pressure in kg/cm2
=18.26
kg/cm2
2. Pump discharge pressure in
kg/cm2
=165.8 kg/cm2
3. Specific Gravity of the solution in
kg/m3
=950 kg/m3
4. Flow in m3
/hr=59.72 m3
/hr
Ans.-Head developed by pump= (discharge
pressure- Suction Pressure)*104
*/sp gravity
of the solution
𝐻𝑒𝑎𝑑 𝐷𝑒𝑣𝑒𝑙𝑜𝑝 𝑏𝑦 𝑃𝑢𝑚𝑝 =
(165.8 − 18.26) ∗ 10
950
=1553.05 Meter
Q-24- What is the pump absorbed power from above data?
Ans.-
𝑷𝒖𝒎𝒑 𝒂𝒃𝒔𝒐𝒓𝒃𝒆𝒅 𝑷𝒐𝒘𝒆𝒓 =
Flow ∗ Sp. Gravity ∗ Head ∗ 9.81
3600 ∗ 10^3
𝑷𝒖𝒎𝒑 𝒂𝒃𝒔𝒐𝒓𝒃𝒆𝒅 𝑷𝒐𝒘𝒆𝒓 =
59.72 ∗ 950 ∗ 1553.05 ∗ 9.81
3600 ∗ 10^3
Pump absorbed Power=240.1KW
Q-5-What is the role of S/C ratio in energy
saving in reformer feed?
Ans.-The Higher S/C ratio means more Energy
Consumption. A thumb rule lowering the S/C
ratio from 4 to 3 the energy saving about 0.2
G.Cal/T of Ammonia. Primary reformer inlet
steam-to-carbon (s/c) ratio is an important factor
in reformer design. First, because a high s/c ratio
favors the products in the reforming reaction
equilibrium, maintained to prevent carbon
deposition on the catalyst, shift conversion of
carbon mono oxide and reduce carburization
damage to the tube material. The design
steam/carbon ratio is 2.85-3.0; the optimum S/C
ratio has the advantages low pressure drop in the
front end of ammonia plant. The S/C ratio
depends upon Natural gas
composition. However process efficiency
declines with increasing S/C ratio for storage
applications. It lowers the amount of unreacted
methane(less methane leak), or methane slip, out
of the secondary reformer and increases the
production of hydrogen. Sufficiently above the
ratio where carbon formation on an active
catalyst is possible and sufficiently high to
reduce the methane leakage during Start up.
Q-6- Low pressure drop across Blow down of
steam is beneficial?
Ans.-Yes, during normal operation, the pressure
drop across FV- is measured by delta P a low
pressure drop across FV is beneficial to the
control valve and it is also optimal from an
energy point of view. Too low a level in blow
down will trip the reforming section interlock
safety group . This arrangement prevents the
boilers from running dry. Addition of phosphate
to the steam drum according to the Boiler
recommendation is foreseen by means of dosing
package. The continuous blow down and
intermittent blow down are operated as per
energy saving.
Q-7- What the relation between CO2 slip and
energy in Methanator?
Ans.-A high CO2 slip may be caused by
insufficient liquid circulation and/or insufficient
flashing/regeneration of the solvent. Check
process conditions, i.e. circulation rates, energy
balance, temperatures and pressures. If process
conditions are within the normal range, then
analyze samples of the process gas taken from
the outlet of the absorber bottom section and the
outlet at the top of the absorber to locate the
cause.

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6
CO2 breakthrough from the top of the absorber is
indicated by the online analyzer and/or by an
increasing temperature in the methanator. The
reaction in the methanator is strongly
exothermic; it can lead to temperature runaway
(approximately 60°C per mole% CO2). The CO2
slip should be monitored closely: if it increases,
it is necessary to take immediate action:
1. check the solution circulation rates and
temperatures and adjust if required,
2. reduce the process gas load on the
absorber by venting upstream, HIC
3. check the pressures in the regeneration
section and adjust by means of PIC if
required –
4. Start injection of antifoam solution (if
you suspect foaming - pressure drop
over packing should be checked or, if all
else fails, trip the methanator.
Q-8- What is the effect of bypassing of the
gas-gas exchanger?
Ans.- Low temperature, high pressure and low
water content favor the methanation reaction
equilibrium. However, within the normal
operating range of 280-320°C, equilibrium
conditions are so favorable that catalyst activity
is practically the only factor which determines
the efficiency of the methanation process.
Catalyst activity increases with increasing
temperature, but the catalyst lifetime is also
shortened. Thus the operating temperature
should be as low as possible. The inlet
temperature is controlled by means of TIC A &
B as split range as shown below. From an energy
point of view the bypassing of the gas-gas
exchanger should be minimum. The shell side
flow (methanation gas) through the trim heater is
adjusted by means of the manual butterfly valves
on the trim heater inlet and bypass. Preferably
the output signal from TIC should be around 50-
55%. In this case the tube side flow through the
trim heater (and the duty) will be minimum,
controlled by 11-TV-B (in minimum position)
and the gas-gas exchanger bypass valve TV will
be closed.
Q-9- What is the synthesis loop circulation
rate with energy loss?
Ans.- The circulation rate can be altered within
certain limits by adjusting the recirculation by-
pass. Under normal conditions, the by-pass
should be kept closed in order to operate the
loop at the maximum possible circulation rate.
At a given make-up gas rate, a decrease in the
circulation rate will cause the synthesis loop
pressure to increase and result in an overall

DOI: 10.13140/RG.2.2.14959.10403
This is an open access article, Research Gate is a Europe
energy loss. The circulation rate has a great deal
of influence on catalyst temperatures. An
increase in the circulation will cause
temperatures to fall. To maintain optimal
Q-10- What is the relation of CO
with Energy?
Ans.- The CO2 content is expressed in Nm
ton of solution. The CO2 content of the lean
solution is indicative for the regeneration
efficiency. Lean solution loadings below the
recommended levels may indicate a higher than
required energy consumption for the
regeneration. Lean solution loadings above the
recommended level can be related to operational
or mechanical problems in the regenerator. Too
high loadings of the lean solution additionally
increase the risk of corrosion. Therefore the lean
solution loading should be properly monitored
over time.
Q-11- What is the relation of solvent strength
with energy?
Fig-MDEA density
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energy loss. The circulation rate has a great deal
of influence on catalyst temperatures. An
increase in the circulation will cause
temperatures to fall. To maintain optimal
operation, it is necessary to increase the bed inlet
temperatures at the same time, the hot spot
temperature may decrease because the catalyst
temperature profile has flattened out
What is the relation of CO2 Contents
The CO2 content is expressed in Nm3
per
content of the lean
solution is indicative for the regeneration
efficiency. Lean solution loadings below the
recommended levels may indicate a higher than
required energy consumption for the
regeneration. Lean solution loadings above the
can be related to operational
or mechanical problems in the regenerator. Too
high loadings of the lean solution additionally
increase the risk of corrosion. Therefore the lean
solution loading should be properly monitored
tion of solvent strength
Ans.- The solvent strength is expressed in
weight percent of amine. It is important to
maintain the solvent strength within the
recommended range to ensure effective sour gas
removal and avoid corrosion of the equipmen
A lower than recommended solvent strength will
lead to an increased solvent circulation rate in
order to meet the treated gas specification. A
higher than recommended solvent strength may
lead to an increased energy consumption of the
stripper and the solution pumps. The water
content is expressed in weight percent of water.
The quantity of water per tone
related to the solvent strength. The
determination of the water content should
always be used as cross-check measurement for
the result of the solvent strength analyses.
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operation, it is necessary to increase the bed inlet
time, the hot spot
temperature may decrease because the catalyst
temperature profile has flattened out.
The solvent strength is expressed in
weight percent of amine. It is important to
maintain the solvent strength within the
recommended range to ensure effective sour gas
removal and avoid corrosion of the equipment.
A lower than recommended solvent strength will
lead to an increased solvent circulation rate in
order to meet the treated gas specification. A
higher than recommended solvent strength may
lead to an increased energy consumption of the
olution pumps. The water
content is expressed in weight percent of water.
tone of solvent is
related to the solvent strength. The
determination of the water content should
check measurement for
f the solvent strength analyses.

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Q-12-How to calculate the solvent strength?
Ans.- The solvent strength is calculated as follows:
𝑆𝑜𝑙𝑣𝑒𝑛𝑡 𝑆𝑡𝑟𝑒𝑛𝑔𝑡ℎ 𝑤𝑡 % =
𝑉 𝐻𝐶𝑙 ∗ 𝑛 𝐻𝐶𝑙
m
F Solvent
where
VHCl Consumption of HCl in ml
nHCl Concentration of HCl in mol/l
m Mass of sample in g
F Solvent =Solvent factor for a MDEA
F. solvent = 10.52
Q-12- How to Calculate CO2 Contents in
Lean solution?
Ans.- This method uses potentio metric titration
with KOH for determination of the total acid gas
content of the solution as CO2.
Reagent is used
1. Distilled water
2. Ethanol, technical grade
Procedure
Prepare a mixture of 1/3 ethanol and 2/3 distilled
water as solvent for the titration. The analysis
has to be carried out in two steps.
Step 1:
Weigh the empty beaker and add 2 –3 g of the
sample. Record the mass of the sample and add
100 ml of the prepared ethanol/water mixture.
Titrate the stirred solution with KOH using the
Titroprocessor at a rate of 1.0 ml/min until a pH
of 13.5 is reached. A clear increase of the
potential should be observed. Record the KOH
consumption. The concentration of KOH has to
be chosen to obtain a KOH consumption of 5 to
20 ml. If the consumption is too low or too high,
the analyses is inaccurate.
Step 2:
Boil off the CO2 from another part of the sample
as described in chapter 2.4 and repeat Step 1
with the CO2-free sample
The acid gas content calculated as CO2 is
obtained according to the follow equation
Evaluation
CO2 Content [wt − %] =
V1
m1
−
V2
m2
∗ ƞKOH ∗ 4.401
The acid gas loading of the solution calculated as CO2 is obtained according to the following equation:
CO2 Loading
Nm3
tsolution
=
V1
m1
−
V2
m2
∗ ƞKOH ∗ 22.414
Where
V1- Volume of KOH consumed in Step 1 in ml
V2- Volume ƞ of KOH consumed in Step 2 in
ml
Ƞ KOH- Normality of KOH in mol/l
M1- Mass of sample in Step 1 in g
M2-mass of sample in step 2 in g
Q-13-How much energy save by purge gas
recovery in ammonia plants?
Ans.-In order to achieve optimum conversion in
synthesis convertor, it is necessary to purge a
certain quantity of gas from synthesis loop so as
to as to reduce inerts concentration in the loop.
Purge gas stream from ammonia process
contains ammonia, hydrogen, nitrogen and other
inert gases. Among them, ammonia itself is the
valuable product lost with the purge stream.
Moreover it has a serious adverse effect on the
environment. This purge gas containing about

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60% Hydrogen was fully utilized as primary
reformer fuel. The recovered hydrogen is sent
back to the synthesis loop to increase production
or save energy, as the quantity of hydrogen
produced by steam reforming can be reduced. A
cryogenic purge gas recovery unit, designed by
M/s L'Air Liquide, France is available in order
to recover H2 from it which is recycled back
convert it to Ammonia while the by - product
tail gas from PGR Unit is burnt as fuel in the
primary reformer . The ammonia recovery unit
removes and recovers the major part of the
remaining ammonia contained in the purge gas,
let down gas and inerts vent gas from loop and
the refrigeration circuit, respectively. The
makeup gas contains small amount of Argon and
Methane. These gases are inerts in the sense that
they pass through the ammonia synthesis
converter without undergoing any chemical
changes. Because of the complexity and cost of
hydrogen production various processes are
employed in the industry to recover hydrogen
from tail gases. Specific industries use specific
hydrogen separation and purification method
based upon their requirement and feed
conditions . This process is based on the
difference in boiling points of liquid gases in the
stream. The basic principle adopted in our
refrigeration circuit is employed.
Following process are used for recovery of
Hydrogen from purge gases.
1. Membrane,
2. Pressure swing adsorption (PSA)
processes and,
3. Cryogenics Process
Factors PSA Membrane Cryogenic
Minimum Feed H2,% 50 15 15
Feed Pressure psig 150-1000 200-2000 200-1200
H2 Purity % 99.9 98 max 97 max
H2 recovery ,% Up to 90 Up to 97 Up to 98
CO+CO2 removal Yes No No
H2 Product pressure Approximately feed Much less than feed Approximately feed
Table -Comparison of H2 purge gas recovery process
Operational consideration of Hydrogen purification technology
Factors PSA Membrane Cryogenic
Feed pre treatment No yes yes
Flexibility Very High High Average
Reliability High high average
By Product recovery No Possible yes
Easy expansion Average high low
Table -Comparison
PURGE GAS RECOVER ADVANTAGES
1. Hydrogen in 15000 Nm³/hr of purge gas
is around 9000 Nm³/hr. The equivalent
feed saving in primary reformer is
around 2.175 T/hr of NG.
2. Or feed can be maintained same increase
ammonia production and hence urea
production provided there are no
bottlenecks.
3. Consequent to this primary reformer
pressure is reduced increasing
conversion and less energy in GV or

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4. back pressure is increased saving energy
in synthesis compressor and better
absorption in GV.
5. Reduction in firing in primary reforming
corresponding to the reduction in feed
and increases in methane slip.
6. Moreover a saving of less than 7 T/h
SM steam in reforming countered by
loss in production of HP steam in RG
boiler.
PURGE GAS RECOVER
DISADVANTAGES
1. Process air to be made up in
secondary reformer equivalent to
hydrogen recovered (for feed 15000
Nm³/hr) is around 3.8 KNm³/hr.
2. However process air reduced due to
reduction in feed is around 3.5
KNm³/hr
3. So net increase in process air in
secondary reformer is around 0.3
KNm³/hr
4. Loss of CO2 around 2.66 KNm³/hr
which means under full load, load
on CDR (Carbon Dioxide Recovery)
is increased being a costly affair.
However energy on GV is also
reduced
Q-14- How much energy saves by installation
of S-50 in ammonia synthesis?
Ans.-Energy saving by Installation of S-50 in
Ammonia Plants
Many plants improved the energy efficiency in
ammonia synthesis section by installing
additional reactor which reduces pressure drop
and increases conversion per pass in the
synthesis loop. A few plants have also changed
the internal of two bed catalyst system to three
bed catalyst system. The reduction in synthesis
loop pressure from above 200 bar to level of 140
bar has been achieved. Except a few old plants,
most plants maintain synthesis loop pressure in
the range of 140-180 kg cm-2.Installation of S-
50 ammonia synthesis converter along with
waste heat boiler in downstream of existing S-
200 ammonia synthesis converter is one of the
major schemes of Energy Saving Project of
Ammonia plant. The energy saving reported
0.18 G.Cal/T of Ammonia. Several ammonia
plants have installed an additional ammonia
synthesis converter in combination with a HP
steam waste heat boiler, downstream of the
existing ammonia converter. The result is
increased conversion per pass, reduced
compression requirements due to the smaller
recycle gas stream, and improved waste heat
recovery. The Topsoe S-250 system uses two
radial flow converters placed in series with
waste heat boilers between the converters and
after the last converter (see Figure). This system
compared to the S-200 series (employing one
converter) is claimed to increase the conversion
per pass and reduce the energy use. Similar
energy savings and increase in the conversion
per pass can also be achieved with the
replacement of the S-200.

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Fig installation of S-50

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12
Operating conditions
Inlet Gas
Temperature o
C 366
Pressure Kg/cm2
177
Total flow Nm3
/hr 550,656
Composition
H2 Vol% 52.72
N2 Vol% 17.57
Inerts, CH4 + Vol% 9.69
NH3 Vol% 20.02
Outlet Gas
Temperature o
C 419
Pressure Kg/cm2
176
Total flow Nm3
/hr 531,482
Composition
H2 Vol% 49.21
N2 Vol% 16.40
Inerts, CH4 + Vol% 10.04
Catalyst
Type KM1
Size mm 1.5-3
Diameters, OD (effective)/ ID mm 2,896 / 760
Height (excl./incl. bottom cone part) m 20,100 / 21,200
Volume m3
125.4
Table-2
Mechanical Data (Pressure Vessel)
Type Vessel with top manhole
Inner diameter mm 3,000
Inner length (T-T) mm 20,250
Normal operating pressure Kg/cm2
g 177
Design pressure Kg/cm2
g 245
Hydrogen partial pressure, design Kg/cm2
130
Temperature of Operating Design
Cover and cylinder part o
C 366 430
Spherical bottom o
C 366 430
Bottom forging o
C 419 450
Bottom flange o
C 419 450
Nozzle sizes
Main inlet inch 16
outlet inch 16
Table-data

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Installation of S-50 ammonia synthesis converter
along with waste heat boiler in downstream of
existing S-200 ammonia synthesis converter is
one of the major scheme of Energy Saving
Project of Ammonia plant.
Parameters
units
Line-II Line-I
Design Design
Line-I Line-II
Converter inlet flow Nm³/h 658400 766490 656158 645915
Make up gas flow Nm³/h 184520 185800 179904 182780
HG from PGR Nm³/h 0 7160 0 0
Converter Feed comp.
H2 vol% 0.6419 0.6258 0.6415 0.6424
N2 vol% 0.1974 0.2185 0.2132 0.2141
NH3 vol% 0.0450 0.0450 0.0578 0.0559
Ar vol% 0.0327 0.0303 0.0287 0.0291
CH4 vol% 0.0830 0.0804 0.0588 0.0584
Converter outlet
comp. 1.00 1.00 1.00 1.00
H2 vol% 0.5195 0.5118 0.5184 0.5173
N2 vol% 0.1575 0.1706 0.1721 0.1724
NH3 vol% 0.1860 0.1870 0.2094 0.2100
Ar vol% 0.0385 0.0358 0.0329 0.0333
CH4 vol% 0.0985 0.0949 0.0672 0.0670
1.00 1.00 1.00 1.00
Converter inlet pressure kg/cm²g 179.80 195.40 220.00 220.00
Converter outlet
pressure kg/cm²g 178.00 193.40 216.00 216.00
Pressure Drop kg/cm²g 2.00 2.00 4.00 2.00
Ist Bed Temperature
Inlet °C 364.00 363.50
Outlet °C 491.00 498.50
IInd Bed Temperature
Inlet °C 355.00 387.60
Outlet °C 435.00 436.70 457.00 456.00
Table-Data

17th
Aug,. 2022
14
S-50 Loop a philosophy
• Higher conversion 35.5 % as compared
to 28.3% in S-200
• Ammonia concentration at the outlet of
S-50 = 24.35% as compare to 20.02% in
S-200
• Lower circulation rate as compared to S-
200 for same load
• Higher steam generation 82 T/hr as
compared to 70 T/hr in S-200
Sr. No. Energy saving Scheme
Energy saving G.
Cal/Ton of urea
1 Energy saving by Installation of S-50 in Ammonia Plants
0.18
2 Switch over of Low Pressure condensing stripping
section of Ammonia Plant with medium pressure
Process Condensate (stripping )
0.098
3 Installation of VAM in Ammonia-I 0.019
4
Steam turbine of Cooling Tower change over with
motor
0.034
5 Installation of make-up gas chiller 0.012
6
Heat Recovery From PC by Installing DM Water Preheater
in Ammonia-I
0.049
7 Running of motor driven Semi lean pump in GV section 0.024
8
Use of Flash gases from Benfield section as fuel in Steam
Super heater
0.0045
Table-energy saving scheme
Q-15 –How to save energy in CO shift
Converter?
Carbon monoxide generated during reforming is
converted to carbon dioxide and hydrogen in
two stage shift reaction for thermodynamic
considerations. The reaction should go to
completion. Any unconverted carbon monoxide
will have to be converted to methane which
consumes hydrogen. Therefore, in recent times
LT shift guard prior to LT shift reactor has been
installed by a number of ammonia plants in the
country. This is to maximize the conversion of
carbon monoxide. A plant has changed the
internal configuration of LT shift converter from
radial to radial axial to reduce pressure drop
across converter. A number of plants have
carried out modifications in carbon dioxide
recovery section as it has significant energy
saving potential. The endeavor is to reduce
energy consumption in regeneration stage. The
single stage regeneration has been changed to
two-stage regeneration systems by a number of
plants. Plants have also changed to better
solvents. In recent revamps, a few plants have
changed the solvent from hot potassium
carbonate to amine based OASE White. Due to
high solution flow rates, most of the equipment
such as pump, columns, filters, etc were
replaced. More efficient multistage pumps for
lean and semi-lean solution and hydraulic

17th
Aug,. 2022
15
turbines were installed in this section. DM/BFW
heat exchangers were also installed to reduce
process gas temperature going to re-boilers.
With these modifications, regeneration energy of
CO2 removal section was reduced from level of
830 K.Cal Nm3
to 500-550 K.Cal Nm3
of CO2
and hydrogen loss in product CO2 was also
reduced from 0.8 mol% to 0.15 mol% . Excess
steam used in
primary reformer is condensed. The condensate
contains ammonia and methanol. Carbon dioxide
also gets dissolved in the process condensate in
raw gas separator. The older generation plants
were using LP steam for condensate stripping
for removal of dissolved ammonia, carbon
dioxide and methanol. The process condensate is
further treated in polishing unit for removal of
trace amount of ammonia and carbon dioxide.
The treated condensate is cooled from about
1000
C to 40 0
C in water cooler. The LP steam
after stripping is vented through stack and heat
from treated condensate is lost in cooling. The
plants of later generation have medium pressure
condensate stripping. Part of MP steam from
stripper is fed to primary reformer rather
venting. There is also more heat recovery from
outlet condensate with installation of feed
effluent heat exchanger. This scheme has been
implemented by a number of old plants during
recent revamps.
1. Two Stage to three stage Regeneration
2. Replacement of Solvent better used
activator
3. Hydraulic Turbine installed pressure
energy
4. Change Over of Random Packing with
Structured Packing/advanced packing.
5. Modification of Internals in Towers.
Q-16-How to save energy in reforming
section?
Ans.-Following modification can save energy in
reforming sections
1. For improving MOC, by Reformer tubes
of better metallurgy with micro alloy.
Additional
2. Heat Recovery In Reformer Convection
Zone - Installing Additional BFW Coil,
Air Pre-heater
3. Changing coil type exchanger to plate
type heat exchanger for air preheater
4. Modification in reformer burners with
advanced burners.
5. Installation of Pre-reformer.
6. Installation of Reformer Exchanger.
Q-17- What is the Energy structure of NG
Based ammonia Plants?
Ans.- Steam reforming is an endothermic
process, which is carried out at high
temperatures. Thermal energy demand is
supplied by a furnace located in the first
reforming step. This furnace is the main energy
consumer at the site, consuming more than 70%
of the overall fuel supplied to the factory.
Combustion gases from this equipment are sent
to a gases channel where thermal energy is
recovered through several heat exchangers that
preheat process streams and generate steam at
different pressure levels before gases are sent to
the stack. There is no requirement for thermal
energy in the second stage of the reformer
(secondary reformer), since it is supplied by the
combustion reactions produced by introducing
process air into the syngas stream. Heat recovery
boilers generate high pressure steam
downstream of the reforming unit, as well as
after the COto-CO2 conversion unit, where
exothermic reactions take place. Additional high
pressure steam is generated in an auxiliary
boiler, whose combustion gases are sent to the
same combustion exhaust gas channel of the
reforming furnace. The auxiliary boiler is the
second largest energy consumer of the facility,
representing over 20% of total energy

DOI: 10.13140/RG.2.2.14959.10403
consumption. The third-largest thermal energy
consumer is the furnace upstream of the de
sulphurisation reactor, where natural gas is
heated. In addition to natural gas, the purge
stream of the synthesis loop is also used in the
fuel feed network, as it contains high levels of
hydrogen. Due to the exothermic reaction of
ammonia production, the thermal energy
contained in the ammonia synthesis reactor
outlet stream is used to preheat the boiler feed
water. As shown in below figure, heat supplied
to the process through the combustion of natural
gas is subsequently recovered for steam
production (power production) and heating
Fig- Ammonia Energy Flow
Q-18- How much energy save by changing
Cooling water turbine driven pump with
motor if power sufficient available?
Ans.-T
Th
he
e e
en
ne
er
rg
gy
y c
co
os
st
t f
fo
or
r r
ru
un
nn
ni
in
ng
g a
a
t
tu
ur
rb
bi
in
ne
e i
is
s m
mu
uc
ch
h h
hi
ig
gh
he
er
r t
th
ha
an
n e
en
ne
er
rg
gy
y c
r
ru
un
nn
ni
in
ng
g m
mo
ot
to
or
r f
fo
or
r s
sa
am
me
e o
ou
ut
tp
pu
ut
t p
po
ow
w
a
av
va
ai
il
la
ab
bl
le
e.
. B
Ba
as
si
ic
ca
al
ll
ly
y d
du
ue
e t
to
o c
co
og
ge
en
ne
er
ra
a
p
po
ow
we
er
r p
pl
la
an
nt
t
R
Re
ed
du
uc
ct
ti
io
on
n i
in
n 4
40
0 K
Kg
g s
st
te
ea
am
m =
= 8
8 T
To
on
n/
/H
H
17th
Aug,. 2022
largest thermal energy
consumer is the furnace upstream of the de
sulphurisation reactor, where natural gas is
heated. In addition to natural gas, the purge
stream of the synthesis loop is also used in the
contains high levels of
hydrogen. Due to the exothermic reaction of
ammonia production, the thermal energy
contained in the ammonia synthesis reactor
outlet stream is used to preheat the boiler feed
water. As shown in below figure, heat supplied
ocess through the combustion of natural
gas is subsequently recovered for steam
production (power production) and heating
combustion air and other process streams.
Unrecovered heat is removed by cooling towers
and air coolers. High pressure steam mainly
consumed by turbo compressors for process air,
syngas, the ammonia cooling system and
injection to the reforming process. A significant
amount of the steam is also exported to the urea
plant. The natural gas consumption for this site
represents more than 95% of the overall energy
consumption of the factory. The main objective
of the proposed energy efficiency assessment is
to reduce natural gas fuel consumption,
corresponding to 39.8% of the total energy inlet.
How much energy save by changing
Cooling water turbine driven pump with
motor if power sufficient available?
c
co
on
nd
de
en
ns
si
in
ng
g
c
co
os
st
t o
of
f
w
we
er
r i
if
f p
po
ow
we
er
r i
is
s
a
at
ti
io
on
n m
mo
od
de
e o
of
f
H
Hr
r.
.
R
Re
ed
du
uc
ct
ti
io
on
n i
in
n e
ex
xt
tr
ra
ac
ct
ti
io
on
n f
fl
lo
ow
w
c
co
om
mp
pr
re
es
ss
so
or
r =
= 8
8 T
To
on
n/
/H
Hr
r.
.
R
Re
ed
du
uc
ct
ti
io
on
n i
in
n i
in
nl
le
et
t 1
10
00
0K
Kg
g s
st
te
ea
am
m
M
Mo
ot
to
or
r p
po
ow
we
er
r c
co
on
ns
su
um
mp
pt
ti
io
on
n =
= 1
1
E
En
ne
er
rg
gy
y s
sa
av
vi
in
ng
g =
= (
(6
6 x
x 0
0.
.7
77
7
G
G.
.C
Ca
al
l/
/H
Hr
r.
. =
=2
2.
.4
46
6 G
G.
.C
Ca
al
l/
/H
Hr
r.
. O
OR
G
G.
.C
Ca
al
l
I
If
f d
di
iv
vi
id
de
e b
by
y U
Ur
re
ea
a P
Pr
ro
od
du
uc
ct
ti
io
on
n t
t
p
pe
er
r t
to
on
n o
of
f U
Ur
re
ea
a.
. T
Th
hi
is
s w
wi
il
ll
l b
be
e a
a
o
of
f u
ur
re
ea
a
16
combustion air and other process streams.
Unrecovered heat is removed by cooling towers
and air coolers. High pressure steam mainly
compressors for process air,
syngas, the ammonia cooling system and
injection to the reforming process. A significant
amount of the steam is also exported to the urea
plant. The natural gas consumption for this site
of the overall energy
consumption of the factory. The main objective
of the proposed energy efficiency assessment is
to reduce natural gas fuel consumption,
corresponding to 39.8% of the total energy inlet.
o
of
f N
NH
H3
3 s
sy
yn
nt
th
he
es
si
is
s
m
m =
= 6
6 T
To
on
n/
/H
Hr
r.
.
1
1.
.3
35
5 M
MW
WH
H.
.
7
70
0 –
– 1
1.
.3
35
5 x
x 1
1.
.6
6)
)
R
R 2
2.
.4
46
6X
X 2
24
4=
=5
59
9.
.0
04
4
t
th
he
en
n w
wi
il
ll
l g
ge
et
t G
G.
.C
Ca
al
l
a
ab
bo
ou
ut
t 0
0.
.0
03
34
4 G
G.
.C
Ca
al
l/
/t
t

17th
Aug,. 2022
17
Q-19- how much energy saves with Heat Recovery from PC by Installing DM Water Preheater?
Calculation
Sr. No. Parameters Data
Before Modification
1 Steam flow to condensate stripper 20 T/H
2 DM water flow 230 T/H
3 DM water temperature at inlet/outlet 35/71.40
C
4 Heat recovered by DM water 8.4 G.Cal/hr
After Modifications
1 Steam flow to condensate stripper 20 T/H
2 DM water flow 230 T/H
3 DM water temperature at inlet/outlet 38/990
C
4 Heat recovered by DM water 14.1 G.Cal/hr
5 Additional heat recovered 5.7 G.Cal/Hr
6 Fuel saving in boiler due to increase in DM water temperature 5.7 G.Cal/Hr
7 Increase in fuel energy due to c/o of TP-1601B to MP-1601C 0.32 G.Cal/hr
8 Net gain in energy due to scheme 5.7-0.32=5.38G.Cal/Hr
9 Specific energy 5.38 X24/Urea Prod
10 Average Net Energy saved 0.049 G. Cal/ton of Urea
Table- Energy calculations
Q-20-How much energy saves by running of
motor driven Semi lean pump in GV section ?
Ans.- As per original operation philosophy,
both semi lean pumps are to be run with
condensing steam turbines & motor drive to be
kept as standby. Steam was being imported from
offsite. Steam generation being costlier, motor
driven pump was taken in line & one of the
turbine driven pumps can be stopped. This has
resulted in saving of condensing steam & steam
import from offsite.
Energy saving about-0.024 G.Cal/Ton of Urea.
Q-21-What is the minimum consumption for
the production of ammonia from methane, air
and steam?
Ans.- The minimum consumption for the
production of ammonia from methane, air and
steam, calculated from the stoichiometric of the
overall chemical reaction, is 0.44 mole methane
per mole of ammonia. Expressed by its lower
heating value (LHV), this equals an energy input
of 4.98 Gcal per ton of ammonia, which is the
minimum feed. Out of these, 4.44 G.cal are
recovered as chemical energy in the ammonia
product. This is the thermodynamic minimum
net energy input. The difference between these
two is the minimum heat rejection from the ideal
process. This is shown schematically in below
Figure . From the figures it is evident, that the
thermodynamic minimum consumption can only
be realized when the credit is given for the
energy value of the heat rejection.

17th
Aug,. 2022
18
Q-22- In Above it is real or energy
consumption is much higher?
Ans.- In the real process, the energy
consumption is much higher for several reasons,
for example:
1. The process is taking place at elevated
temperatures and pressures.
Unfortunately, a significant portion of
the heating requirements needs higher
temperatures than offered by the hot
process streams that are to be cooled
down. Consequently, perfect heat
integration is impossible. This means,
more energy must be added to the
process, which can be only partly
recovered from it for re-use while the
rest is discharged to the ambient.
2. A commonly used option to utilize the
high-temperature waste heat is its
conversion to mechanical energy by
means of a steam cycle. The mechanical
power serves the power demand of the
pressure changes in the process. As for
thermodynamic reasons heat cannot be
freely converted to mechanical power,
further energy losses are inevitable.
3. Mechanical work must be added to the
process to overcome friction that can be
observed e.g. as pressure drop or as
limited efficiency of machinery.
4. Further irreversibility can be found
where heat is transferred with significant
temperature difference. The temperature
drop causes a loss in the thermodynamic
quality of the transferred heat.
5. The inlet and outlet streams do not come
at standard conditions (e.g. sub cooled
ammonia product).
6. Reactants are not fed in
stoichiometrically but in excess (like
process steam), and are not fully
recovered.
7. Natural gas does not come as pure
methane. It has also CO2 and other gases
as impurities.

DOI: 10.13140/RG.2.2.14959.10403
Q-23 – A major question How to Load
Ammonia converter catalyst?
Ans.-The answer is not easy catalyst loading is
very typical steps. A catalyst loading box is put
into position and a manifold is mounted below
the loading box. The purpose of the manifold is
to make connection of one to four loading hoses
possible. Each loading hose is connected to the
manifold in one end and the hose length is
adjusted to extend a few meters down the first
bed. Hereafter, the hoses are connected to a ring
assembly . The loading hose should be of
appropriate stiffness (e.g. polyethylene) a
have an ID of approximately 70 mm. In order to
ensure free-flowing catalyst in the loading hose,
the outlet from the loading box has to be
restricted, e.g. by an orifice plate with an ID of
50 mm.
Lifting
After the catalyst is screened into the hopper,
is lifted to the top of the converter and the
catalyst is charged into the loading box.
17th
Aug,. 2022
A major question How to Load
The answer is not easy catalyst loading is
very typical steps. A catalyst loading box is put
into position and a manifold is mounted below
the loading box. The purpose of the manifold is
to make connection of one to four loading hoses
oading hose is connected to the
manifold in one end and the hose length is
adjusted to extend a few meters down the first
bed. Hereafter, the hoses are connected to a ring
assembly . The loading hose should be of
appropriate stiffness (e.g. polyethylene) and
have an ID of approximately 70 mm. In order to
flowing catalyst in the loading hose,
the outlet from the loading box has to be
restricted, e.g. by an orifice plate with an ID of
After the catalyst is screened into the hopper, it
is lifted to the top of the converter and the
catalyst is charged into the loading box.
Showerhead
The number of showerheads/loading hoses to be
used is determined by the space restrictions
inside the converter. Also the crane speed is
taken into consideration. Normally, the crane
lifting the catalyst to the loading box will be the
bottleneck, so the number of
showerheads/loading hoses can be adjusted to
match the speed at which the catalyst can be
lifted to the loading box. To ensure uniform
drizzle an orifice is placed inside the
showerhead pipe just above the cone.
Showering
During the charging of the catalyst, the persons
showering should keep the catalyst surface as
horizontal as possible by guiding the loading
hoses and loading ring, so that the showerhead is
moved from side to side, in the middle of the
area between outer screen panels and centre
screen. The catalyst should not be allowed to
pile up in heaps as this would tend to cause some
segregation of the different catalyst parti
19
The number of showerheads/loading hoses to be
used is determined by the space restrictions
inside the converter. Also the crane speed is
eration. Normally, the crane
lifting the catalyst to the loading box will be the
bottleneck, so the number of
showerheads/loading hoses can be adjusted to
match the speed at which the catalyst can be
lifted to the loading box. To ensure uniform
orifice is placed inside the
showerhead pipe just above the cone.
During the charging of the catalyst, the persons
showering should keep the catalyst surface as
horizontal as possible by guiding the loading
so that the showerhead is
moved from side to side, in the middle of the
area between outer screen panels and centre
screen. The catalyst should not be allowed to
pile up in heaps as this would tend to cause some
segregation of the different catalyst particle

DOI: 10.13140/RG.2.2.14959.10403
sizes, giving a less homogeneous loading. The
gentle drizzle of catalyst will ensure a good,
Freefalling height
Initially, the catalyst has a high freefalling height
but during loading, this height is continuously
reduced. In order to ensure the high filling
density, it is important to keep the freefalling
height at minimum 2.0 m. Therefore, when the
freefalling height reaches 2.0 m, the length of
the loading hoses has to be reduced to ensure
that the catalyst falling height is minimum 2.0
m. When loading the top of the 1st bed, it may
also be necessary to lift the catalyst loading box
as well in such a way that the minimum catalyst
loading height is observed.
Loading speed
The expected loading speed is in the range of 1
4 m3 of catalyst per hour provided that the
proper equipment is available. Safety during
Fig- Catalyst loading Sequence
17th
Aug,. 2022
sizes, giving a less homogeneous loading. The
gentle drizzle of catalyst will ensure a good,
uniform loading with a high density without the
need for traditional catalyst vibration.
h freefalling height
but during loading, this height is continuously
reduced. In order to ensure the high filling
density, it is important to keep the freefalling
height at minimum 2.0 m. Therefore, when the
freefalling height reaches 2.0 m, the length of
the loading hoses has to be reduced to ensure
that the catalyst falling height is minimum 2.0
m. When loading the top of the 1st bed, it may
also be necessary to lift the catalyst loading box
as well in such a way that the minimum catalyst
The expected loading speed is in the range of 1-
4 m3 of catalyst per hour provided that the
proper equipment is available. Safety during
loading In order to avoid accidents with the
loading hose falling down full of catalyst, the
flow of catalyst must never be stopped from the
bottom of the bed. As an extra safety precaution,
it is recommended securing the hose with a rope.
Personnel inside the ammonia converter
covering the centre screen opening etc. must at
all times wear a safety harness.
Purging with Nitrogen
During some periods of the catalyst loading, it is
mandatory to have nitrogen available for
purging. In all catalyst beds, a nitrogen pipe is
installed, which can be used for local purging of
the bed (capacity corresponding
velocity in the catalyst bed of 2
Personnel should not be present in the converter
when nitrogen is connected.
20
uniform loading with a high density without the
need for traditional catalyst vibration.
loading In order to avoid accidents with the
loading hose falling down full of catalyst, the
flow of catalyst must never be stopped from the
bottom of the bed. As an extra safety precaution,
it is recommended securing the hose with a rope.
Personnel inside the ammonia converter
covering the centre screen opening etc. must at
y harness.
During some periods of the catalyst loading, it is
mandatory to have nitrogen available for
purging. In all catalyst beds, a nitrogen pipe is
installed, which can be used for local purging of
the bed (capacity corresponding to a linear
velocity in the catalyst bed of 2-4 m/min).
Personnel should not be present in the converter

DOI: 10.13140/RG.2.2.14959.10403
After purging with nitrogen
Whenever the converter has been purged with
nitrogen, the air supply should be re
and the oxygen level should be checked before
any entry into the converter. Oxygen masks
should be available when entering the converter
after nitrogen purging. Entry into an oxygen
depleted atmosphere could be fatal in a few
seconds.
During loading
When pre reduced catalyst is loaded, two
nitrogen supply lines should be available, one
for the local nitrogen pipe and one for a
sparger/spear (half a meter of metal pipe with
holes), which can be inserted in a local hot spot.
For safety reasons, the nitrogen should not be
connected.
Use of nitrogen
The local nitrogen pipe and the sparger/spear
should be used in case of heating of the
prereduced catalyst already loaded into the
converter. Further, it should be connected when
Fig- Catalyst Loading
17th
Aug,. 2022
been purged with
nitrogen, the air supply should be re-established
and the oxygen level should be checked before
any entry into the converter. Oxygen masks
should be available when entering the converter
after nitrogen purging. Entry into an oxygen-
d atmosphere could be fatal in a few
When pre reduced catalyst is loaded, two
nitrogen supply lines should be available, one
for the local nitrogen pipe and one for a
sparger/spear (half a meter of metal pipe with
be inserted in a local hot spot.
For safety reasons, the nitrogen should not be
The local nitrogen pipe and the sparger/spear
should be used in case of heating of the
prereduced catalyst already loaded into the
, it should be connected when
the loading is interrupted for longer periods of
time, i.e. during the night or rainfall, to prevent
entrance of humid air.
Purging after loading
After the loading of the pre reduced catalyst in a
bed is completed, the cover i
continuing the loading or boxing up, the catalyst
bed should be purged for four hours through the
local nitrogen pipe to ensure that no humidity
left in the bed will cause the catalyst to heat.
Nitrogen supply after box-up
A nitrogen supply through the converter outlet
pipe should be arranged to make it possible to
establish a slightly positive nitrogen pressure in
the converter when it is loaded and closed until
the start-up of the converter. Humidity and
oxygen levels in the catalyst b
by a few pressurizations and depressurizations of
the converter with nitrogen. Thereafter, the
converter is kept pressurized with nitrogen at
about 4-5 kg/cm2 g until start-
21
the loading is interrupted for longer periods of
time, i.e. during the night or rainfall, to prevent
After the loading of the pre reduced catalyst in a
s installed. Before
continuing the loading or boxing up, the catalyst
bed should be purged for four hours through the
local nitrogen pipe to ensure that no humidity
left in the bed will cause the catalyst to heat.
up
pply through the converter outlet
pipe should be arranged to make it possible to
establish a slightly positive nitrogen pressure in
the converter when it is loaded and closed until
up of the converter. Humidity and
oxygen levels in the catalyst beds are decreased
by a few pressurizations and depressurizations of
the converter with nitrogen. Thereafter, the
converter is kept pressurized with nitrogen at
-up.

17th
Aug,. 2022
22
Q-22- Who manufactured Green ammonia?
Ans.- Following companies are produced green
ammonia.
1. Topsoe has developed process
technologies and catalysts for
production of green ammonia entirely
from renewable sources – wind, water,
and air. Over the past 70 years, Topsoe
has earned a reputation for being a
trusted supplier to the ammonia
industry.
1. The world first Green Ammonia plant
was made by Kapsom,At present,
Kapsom has developed four standard
series of synthetic ammonia plant
products of 2000 tons/year, 5000
tons/year, 10000 tons/year and 20000
tons/year. At the same time, our R&D
personnel are developing the skid-
mounted standardized designs for three
medium and large capacity synthetic
ammonia plants of 50,000 tons/year,
100,000 tons/year and 200,000
tons/year.
2. Stamicarbon Green Ammonia
Technology plots a clear course towards
green fertilizer production from nature’s
elements – solar, wind energy, hydrogen
from water– instead of fossil fuels - and
nitrogen from the air. It, therefore,
represents a significant leap forward for
sustainability within the fertilizer
industry, while also offering exciting
opportunities for collaboration between
the fertilizer and energy markets.
3. Thyssenkrupp developed small scale
green Ammonia Plant.
Q-23-What is the Importance of Green
ammonia as Carbon free environment?
As a carbon-free asset, green ammonia has
several potential applications, including: Long
duration renewable storage. As a transport fuel
for fuel cells vehicles. As a feedstock as green
fertilizer (production at point of
consumption).The importance of ammonia is
self-evident. It is not only an important chemical
raw material for modern industry and
agricultural fertilizers, but also one of the main
carriers of hydrogen energy. However, 98% of
the feedstock for ammonia production comes
from fossil fuels. With the intensification of
global warming and environmental issues, it is
inevitable to find an appropriate green
alternative to achieve low energy consumption,
low emission, sustainable and efficient ammonia
production. Green synthetic ammonia
technology came into being. Green ammonia
production is where the process of producing
ammonia is 100% renewable and carbon-free.
One way of producing green ammonia is by
using hydrogen from water electrolysis and
nitrogen separated from the air.
Q-24- how Green Ammonia used as a fuel?
Ans.- There are a few key ways ammonia can be
used as a fuel. One is by "cracking" it back into
H2 and N2 gases, and then using the hydrogen,
either as a combustion fuel or to produce
electricity via a fuel cell. By volume, ammonia
(15.6 MJ/l) carries 70 percent more energy than
liquid hydrogen (9.1 MJ/l at cryogenic
temperatures) and nearly three times as much
energy as compressed hydrogen gas (5.6 MJ/l at
a pressure of 700 bar). By weight, ammonia
carries 6,250 WH/kg – unsurprisingly far less
than hydrogen's 33,300-odd WH/kg. But it's
more than 20 times the specific energy of today's
lithium batteries, and more than enough to
account for the inefficiencies introduced when
you extract the energy. Diesel, as the dominant
fossil fuel for long haul shipping, is of course
considerably better, giving you 38.6 MJ/l and
12,667 WH/g in a combustion cycle. But
ammonia's numbers are enough to bring it into

17th
Aug,. 2022
23
The conversation, and diesel's days are
numbered. There are a few key ways ammonia
can be used as a fuel. One is by "cracking" it
back into H2 and N2 gases, and then using the
hydrogen, either as a combustion fuel or to
produce electricity via a fuel cell. Efficiency-
wise, Australia's CSIRO calculates ammonia
returns about 2,094 WH/kg when converted to
hydrogen and run through a PEM fuel cell.
That's about 19 percent of the 10 MWH/ton of
renewable energy it takes to create the ammonia.
Another option is to burn the ammonia directly
as a combustion fuel, combining it with oxygen
to release energy, with nitrogen gas and water
the only exhaust products. This is not super
simple – ammonia doesn't burn at lower
temperatures, so typically another combustion
fuel needs to be used in conjunction. Also, if the
combustion process isn't well managed, it can
release large amounts of nitrous oxide, a potent
greenhouse gas. But when done properly,
CSIRO calculates it returns 2,315 WH/kg, or 21
percent of the energy input for ammonia
synthesis. A third is to use ammonia directly as a
fuel for a high-temperature solid oxide fuel cell
(SOFC) creating electricity with nitrogen and
water as by-products. This is much more
efficient, returning as much as 5,510 WH/kg, or
50 percent of the energy input. A drawback here
is that SOFC technology is expensive and tends
to work slowly, offering poor power density –
but it's possible to run a hybrid system off a
single fuel tank, converting a percentage of the
ammonia fuel to hydrogen when burst power is
needed.
Q-24 How to avoid CO2 Breakthrough in
Process?
Ans.-Gas CO2 breakthrough from the top of the
absorber is indicated by the online analyzer
and/or by an increasing temperature in the
Methanator. The reaction in the Methanator is
strongly exothermic; it can lead to temperature
runaway (approximately 60°C per mole% CO2).
The CO2 slip should be monitored closely: if it
increases, it is necessary to take immediate
action: -
1. Check the solution circulation rates and
temperatures and adjust if required, -
2. Reduce the process gas load on the
absorber by venting upstream, -
3. Check the pressures in the regeneration
section and adjust by means of PIC- if
required.
Start injection of antifoam solution (if you
suspect foaming - pressure drop over packing’s
should be checked or, if all else fails, trip the
Methanator. A high CO2 slip may be caused by
flashing/regeneration of the solvent. Check
cause.
CO2 Breakthrough in Process Gas
CO2 breakthrough from the top of the absorber
is indicated by the online analyzer (AI) and/or
by an increasing temperature in the Methanator.
The reaction in the Methanator is strongly
exothermic; it can lead to temperature runaway
(approximately 60°C per mole% CO2). The CO2
slip should be monitored closely: if it increases,
it is necessary to take immediate action: - check
the solution circulation rates and temperatures
and adjust if required, - reduce the process gas
load on the absorber by venting upstream, (HIC)
- check the pressures in the regeneration section
and adjust by means of PIC if required - Start
injection of antifoam solution (if you suspect
foaming - pressure drop over packing’s should
be checked or, if all else fails, trip the
Methanator. A high CO2 slip may be caused by

17th
Aug,. 2022
24
Flashing/regeneration of the solvent. Check
cause.Figure- 13Increased CO2 slip
breakthrough due to kinetic limitation of the
system (example) Break-through in top section
If the CO2 breakthrough is found to occur only
in the top of the absorber, analyze the lean
solution. Too high of a CO2 load in the lean
solution redirects the problem to the stripper.
Check the energy balance, reboiler performance
and circulation. Check the stripper CO2
concentration profile and pressure drop to
identify possible misdistribution. If the lean
solution CO2 load is close to the design level, the
problem is due to insufficient mass transfer in
the top of the absorber. Determine the content of
activator, total amine and MDEA. Check the
pressure drops and concentration profile to
identify possible maldistribution. Break-through
in bottom section If the CO2 breakthrough is also
found in the bottom part of the absorber, analyze
the semi lean solution. Too high of a CO2 load in
the semi lean solution redirects the problem to
the LP flash drum. Check pressure, pressure
drops and energy balance (e.g. heat from the
stripper). If the CO2 load is below or close to the
design level, the problem is due to insufficient
mass transfer in the bottom part. Determine the
content of activator and total amine. Check the
pressure drops and concentration profile to
identify possible mal-distribution.
Q-25- How to compare energy wise in
Horizontal and vertical Converter?
Ans.- Following table energy wise comparison
Vertical Converter Horizontal Converter
Topsoe's low energy ammonia process scheme can
be optimized for a wide range of operating
conditions by selecting proper process technology
and by adjusting the process parameters. Topsoe's
ammonia plant designs are characterized by being
highly energy efficient. Compared to the S-200
converters, the presence of three catalyst beds
offers higher conversion into ammonia and hence
increased production efficiency. Alternatively, the
catalyst volume can be reduced, which lowers
investment costs compared to the previous
generation of converter design. When the S-300
basket is installed in an existing ammonia converter
pressure shell as part of a revamp project,
significant energy savings can be achieved. These
advantages can be obtained in connection with the
revamp of both Topsoe and non-Topsoe designed
converter types. The Purge gas recovery system is
installed separately.
A clean, dry make-up gas reduces the load on the
synloop compressor and refrigeration systems,
providing operational cost savings. Mild reforming
temperatures are used as methane slip is
unimportant, which reduces fuel consumption and
increases tube life. Higher loop conversion is
achieved with low inerts. Purifier plants operate at
some of the lowest proven energy consumption; a
recent plant achieved an energy consumption of 6.5
G.cal /MT(ISBL, LHV basis) slip is unimportant,
which reduces fuel consumption and increases tube
life. Higher loop conversion is achieved with low
inerts. Purifier plants operate at some of the lowest
proven energy consumption; a recent plant
achieved an energy consumption of 6.5 G.cal
/MT(ISBL, LHV basis). No separate purge gas
recovery unit is needed because purge gas rejected
from the syn loop is passed through the Purifier™
unit. Very clean make-up gas provided by KBR's
Purifier™ process lowers synthesis pressure,
catalyst volume and purge rate, which means that
smaller synloop equipment can be used.
Table- Comparison of Horizontal and vertical Converter energy wise

17th
Aug,. 2022
25
Q-26-What is the concept of Casale in
Converter w.r.t. Energy?
Ans.-Casale Internals Design Overview
Both isothermal and adiabatic installed
technologies share the common advantages of
the well-known Casale layout. The selected
configuration, namely 2 converters in series
(isothermal followed by adiabatic), gives high
per-pass conversion. This helps reduce the
circulation of the loop and therefore the total
pressure drop. Another factor positively
affecting the synthesis loop pressure drop is the
single-bed configuration of both converters, with
the application of Casale Axial-radial
technology, which is shown in Figure-20. As
will be explained in later sections of this paper,
the reduced load on the synthesis gas
compressor recycle wheel helped obtain
considerable energy saving.
Isothermal Converter
As mentioned above, the first of the two
converters has an isothermal design. This
converter was designed with one axial radial bed
directly cooled by plates immersed in the
catalyst. This allows a simple mechanical
design, which can be installed in a shorter time
in the existing converter with respect to multi-
bed layouts. The exchanger plates are arranged
radically-in a vertical fashion and the cold gas
inside the plates flows in parallel with the
reacting gas in the catalyst.
Isothermal converter concept
The Casale Isothermal Ammonia Converter
(IAC) replaces the commonly used multiple
adiabatic catalyst bed design and offers higher
per pass conversion. The design is based on the
use of cooling plates, directly immersed into the
catalyst to continuously remove the heat while
the reaction proceeds. As indicated in Figure 3
below, the converter is designed to precisely
follow the maximum reaction rate curve,
therefore obtaining the maximum achievable
conversion per pass. The design of the internals
has been carried out thanks to the advanced
modeling software, internally developed by
Casale, with the aim of obtaining the optimal
reaction path inside the converter.
Converter temperature control the converter
performance is optimized by controlling two
main variables: the inlet temperature of cooling
plates and the inlet temperature of the catalyst
bed. The plate’s inlet temperature is regulated
with 122-C bypass valves. The catalyst inlet
temperature is then regulated by mixing the hot
gas from the plates with a colds hot stream of
fresh gas. The efficient mixing of control
streams is provided by carefully designed
mixing devices, assuring the uniform conditions
of the gas entering the catalyst bed
Reliability of Casale Internals
The internals of the converters are designed in
order to allow free thermal expansion of all
components. The nozzle connections between
cartridge and pressure vessel and the connection
to the exchanger plates inside the cartridge use
expansion joints with internal sleeves, while all
the other joints internal to the cartridge use the
Casale patented elastic ring seal. In particular,
the internal connection between the bottom of
the 122-C and the outlet pipe with elastic ring
seal, allows for easy and fast maintenance since
the 122-C can be removed without cutting welds
inside the converter in an inert atmosphere.
Installation is easy as well and, as per Casale’s
well proven design, no welding on existing
pressure parts are performed. Moreover the
single bed configuration simplifies the design
while increasing the converter reliability and the
catalyst volume.
Materials selection
The exchanger plates consist of AISI 321
stainless steel. The selected material of
construction for the plates is based on proven
technology that has been installed in other
converters. It should be noted that the operating
conditions of the exchanger plates are milder

DOI: 10.13140/RG.2.2.14959.10403
than the rest of the internals (e.g. collectors)
since the cold gas flowing inside the plates keeps
the metal temperature at lower levels. The rest of
the internals have the same design features of all
Casale ammonia converters. In general
internals are constructed from AISI 321 stainless
steel, while thin parts like expansion joint
bellows are made of Inconel alloy 600.
Adiabatic Converter
In addition to the revamping of the first
synthesis converter, CFI requested that Casale
assess the feasibility of revamping the existing
Fig-Adiabatic Vs Isothermal
Conclusion
Energy is the prime mover of ammonia plant
because the 78-80 % energy of urea plant
depends upon Ammonia plant, rest of urea
depends upon steam & Power. Even a small
variation in ammonia plant for energy will be a
big change for urea plant energy.
is the continuous process ,Today’s ammonia
17th
Aug,. 2022
than the rest of the internals (e.g. collectors)
since the cold gas flowing inside the plates keeps
ure at lower levels. The rest of
the internals have the same design features of all
In general all the
internals are constructed from AISI 321 stainless
steel, while thin parts like expansion joint
oy 600.
In addition to the revamping of the first
synthesis converter, CFI requested that Casale
assess the feasibility of revamping the existing
additional converter. The second converter had
been idled for several years. As a result,
walled converter, which has no internal
cartridge, is now retrofitted to a single bed
adiabatic with Casale axial
design. It is in series, after the isothermal
converter and it shares with the isothermal
converter the well-proven features of Casale
internals described above. reliability and the
catalyst volume.
Energy is the prime mover of ammonia plant
80 % energy of urea plant
Ammonia plant, rest of urea
depends upon steam & Power. Even a small
variation in ammonia plant for energy will be a
Improvement
is the continuous process ,Today’s ammonia
plants are with energy consumptions near 7.0
7.4 G.cal per ton of ammonia already close to
the thermodynamic minimum energy input of
4.44 G.cal per ton. Therefore, it is getting more
and more difficult to find further reductions. In
addition to that, at low gas cost, the higher
investment for further energy saving is not
always justified. The earlier developments were
26
additional converter. The second converter had
been idled for several years. As a result, this hot
walled converter, which has no internal
cartridge, is now retrofitted to a single bed
adiabatic with Casale axial-radial internals
. It is in series, after the isothermal
converter and it shares with the isothermal
features of Casale
reliability and the
plants are with energy consumptions near 7.0-
G.cal per ton of ammonia already close to
the thermodynamic minimum energy input of
4.44 G.cal per ton. Therefore, it is getting more
and more difficult to find further reductions. In
addition to that, at low gas cost, the higher
rgy saving is not
The earlier developments were

17th
Aug,. 2022
27
focused on utilizing high grade waste heat. Of
late, the focus shifted to utilize low grade heat.
Most of the energy consumed is for the
manufacture of ammonia and urea. Typically,
ammonia production fuel costs account for about
65% of the overall energy costs. The wide
adoption of best practice technologies in
ammonia manufacturing has the potential to
decrease the fuel use for energy purposes by
14%.Despite what efficiency measures you may
have implemented in the past, there is always
room for additional cost-effective energy
efficiency improvements that will pay your
company back tenfold and grow your bottom
line!
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Energy conservation techniques in ammonia and urea production plants

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