Ammonia Process Description-1

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANTFEEDSTOCKS AND RAW MATERIALS

Nitrogen and hydrogen are the two basic raw materials used in the manufacture of ammonia.

Nitrogen is available in abundance, the source being atmosphere.

The sources of hydrogen for nitrogenous fertilizer production are natural gas, naphtha, fuel oil, coal and from electrolysis of water.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANTSHORT DESCRIPTION ABOUT DIFFERENT FEEDSTOCKS

Natural gas

Natural gas composition varies with location. Higher the concentration of Methane, lower will be the C : H ratio. The natural gas occurs either in association with crude petroleum or as non-associated gas. When it occurs as non-associated gas, it is called free gas and when it occurs in association with crude petroleum, it is called associated gas.


Typical compositions of free gas & associated gas Constituents

Associated Gas (Vol. per cent)Free gas

CH4 69.2 80.2 C2H6 13.5 8.0 C3H8 9.3 4.4 C4H10 4.0 1.9 C5H12 1.7 0.8 O2, N2, CO2 etc.2.3 4.7


Naphtha

The light distillate fraction of petroleum produced during the refining of crude oil with maximum boiling point in the range of 94 deg – 232 deg C is called straight-run naphtha.


Typical analysis of Naphtha Sp Gravity 0.700-0.715 Sulphur 0.15 % max Lead 1.7 ppm Chloride 0.4 ppm Paraffin 79 % Olefin 1 % Naphthalene 14 % Aromatic 6 % C/H ratio (by weight) 5.45-5.42 Boiling point range 94 deg – 232 deg C


Fuel oil or heavy petroleum fractionThese are heavy residual fractions obtained by primary distillation and cracking of crude oil. The heavy fraction could be fuel oil, high sulphur heavy stock or low sulphur heavy stock.

LigniteLignite is inferior coal, containing high water and having low heat value and mechanical strength.

CoalThe estimated coal resources in India are to the tune of 81 billion tones. Two fertilizer plants namely Ramagundam and Talcher are based on coal gasification.


Coke Oven gas

Coke oven gas is produced during coal carbonization in steel plant. This gas contains Hydrogen methane, carbon monoxide etc, which can be used for ammonia manufacturing. The fertilizer plant at Rourkela is based on coke oven gas.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT

COMMERCIAL AVAILABLE AMMONIA TECHNOLOGY

Haber suggested that ammonia can be produced by synthesis reaction of H2 & N2 in the ratio 3 to 1 at high pressure and high temperature in presence of iron catalyst.

Due to advancement of technology, ammonia production was commercialized and specific energy consumption also reduced.

Various commercial ammonia process/ technologies available are


COMMERCIAL AVAILABLE AMMONIA TECHNOLOGY

Haldor Topsoe Process ICI Process (AMV Process) MW Kellogg Low Energy Process C. F. Braun KTI PARC Process Humphery & Glasgow (MDF &LEAD Process)


INSTALLED CAPACITY - 1520 MTPD

PROCESS LICENSOR - HALDOR TOPSOE, DENMARK

PROCESS TECHNOLOGY - NG STEAM REFORMING

RAW MATERIAL - FEED-NG

FUEL – NG AND/OR NAPHTHA

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT NG FEED STOCK SPECIFICATION

Ammonia plant can be fed with one of the feed/fuel gas having the following characteristics at battery limits:

CASE A CASE B CASE C Rich Gas After LPG extraction Lean gas

Methane 78.84 83.29 98.39 Ethane 7.23 7.60 1.40 Propane 4.59 2.10 0.10 I-Butane 0.88 - - N-Butane 1.10 - - I-Pentane 0.26 - - N-Pentane 0.24 - - Hexane 0.26 - - Carbon Dioxide 6.49 6.9 - Oxygen 0.10 0.10 0.10 Nitrogen 0.01 0.01 0.01

Total Sulfur content as H2S Normal 10ppm Design 50ppm Pressure 43 Kg/cm2g Temperature 30 C

Natural gas 98% CH4

Recycle Hydrogen

HP Steam

Steam Comb.Air

Natural gas Purge gas

Stack

DesulphurizerR-1201/1202

Primary Reformer

Sec. Reformer

RG Boiler

0.3%CH4950 Deg C

Boiler feed water

HTShift

FT

Make up syn gas

210 Kg/cm2 & 23 Deg C

CO2TO

UREA

FPT

CO2 Removal

Lean and Semi Lean GV Solution

E1311

0.1%CO2

320 Deg C

Methanator

338 Deg C

Final gas cooler

Separator

Syn gas compressor

M/U gas chiller

26 Kg/Cm2 38 Deg C

BFW Pre heater

T

SEPL

LTShift

BFW Pre heater

Separator

CG boiler

Trim heater

74.2% H2 & 24.77% N2

1.03% CH4/Ar

Process air

From 2d Stage

387 Deg C

32Kg/Cm2

BFW fromE1502

BFW

Surplus syn gas

10.95% CH4

770 Deg C

360 Deg C 12.96% CO

427 Deg C 3.09% CO

221 Deg C 0.25% CO

17.75% CO2

200 Deg C

NG NAPHTHA (MSM3/DAY) (MT/DAY)

FEED TO REFORMER 1.008 NAFUEL TO REFORMER 0.273 NILOR* OR*0.137 110FUEL TO SUPER HEATER 0.068 NILOR* OR*0.017 45(* IN CASE OF MIX-FUEL FIRING)

KRIBHCO SHYAM FERTILISERS LTD

AMMONIA PLANT RAW MATERIAL CONSUMPTION

KRIBHCO SHYAM FERTILISERS LTD

AMMONIA PLANT ENERGY CONSUMPTION

The Theoretical Specific energy consumption is 4.46 Gcal/te of Ammonia.

The actual Specific energy consumption is 7.6 Gcal/te of Ammonia.

The difference between these two energies is due to loss of energy from Flue gas of primary reformer and heat loss in cooling tower.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT MAJOR PROCESS STEPS

HYDRO-DESULPHURISATION PRIMARY & SECONDARY REFORMING CO SHIFT CONVERSION CO2 REMOVAL SYSTEM METHANATION COMPRESSION AMMONIA SYNTHESIS PROCESS CONDENSATE TREATMENT PURGE GAS RECOVERY

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT HYDROGENATION

Natural Gas mainly containing methane (98%) and higher hydrocarbon has 10-50 ppm of sulphur. This sulphur is poisonous to Primary reformer Catalyst and LTS catalyst. In desulphurization process sulphur content is reduced to 0.05 ppm.

Hydrogen is added to Natural gas and sent to Hydrogenator. Here Hydrogen reacts with Sulphur and Hydrogen Sulphide is formed.

H2+S H2S

Type of catalyst TK-251 (Catalyst Ni & Mo) Volume of catalyst 8.9 M3

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT DESULPHURISATION

After hydrogenation the process gas is passed through the absorption vessels where the H2S is absorbed on ZNO

ZnO+H2S↔ZnS+H2O (Catalyst ZnO) Type of catalyst HTZ-3 of HTAS Volume of catalyst 13.8 M3

There are two ZNO absorbers in series and one can be isolated in running for replacement of catalyst.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT PRIMARY REFORMER

It is a side fired tubular primary reformer with flue gas heat recovery section. Natural gas is reformed with steam to produce a mixture of hydrogen, carbon monoxide, carbon dioxide and methane.

The reforming reaction is endothermic. The heat required for reforming reaction is supplied by 576 radiant burners.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT PRIMARY REFORMER

The favorable conditions for reformer reaction are low pressure and high temperature.

CH4+2H2O↔CO2+4H2 -- HEAT

CO2+H2↔CO+H2O -- HEAT

There are two chambers and each chamber contains 144 tubes. Catalyst volume in Primary reformer is 44 M3

Primary reformer outlet Methane is approx. 11 %.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT SCHEMATIC DIAGRAM OF PRIMARY REFORMER

ID Fan

Stack

FD Fan

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT SECONDARY REFORMER

Function of secondary Reformer is to reform the Primary Reformer exit residual methane and to add Nitrogen to the process gas.

This is achieved by mixing a stoichiometric quantity of process air to the primary reformer exit gases in Secondary Reformer.

The Oxygen present in the air burns with Hydrogen and provides heat for further reforming reaction.

Secondary Reformer outlet gas mixture contains hydrogen, nitrogen, carbon monoxide, carbon dioxide and methane (0.3%).

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT WASTE HEAT RECOVERY

High temperature process gas exit secondary Reformer at 950 deg C is cooled down in Waste Heat Boiler to 360 deg C and in turn high pressure steam (115 Kg/cm2g) is produced. This Saturated Steam produced is super heated to 510 deg C and utilized as driving force for Syn gas turbine which in turn generate Medium Pressure steam.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT SECONDARY REFORMER AND RG BOILER

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT SHIFT CONVERSION

Carbon monoxide is converted to carbon dioxide in two stage shift conversion bringing down the carbon-monoxide content from 12.95% to 0.3 % in the process gas.In the first stage the reaction rate will be higher at High temperature and in the Second stage equilibrium conditions are favorable at low temperature.

CO+H2O ↔ CO2+H2+HEAT

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT SHIFT CONVERSION

High temperature Shift converter

Catalyst volume 100 M3

Type of Catalyst SK-201 of HTAS

CO Content reduced to 3.09% from 12.96%.

Low temperature Shift converter

Catalyst volume 116 M3

Type of Catalyst C-18 G/7 of Sud-Cheme

CO Content reduced to 0.25% from 3.09%.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT CARBON DIOXIDE REMOVAL

Giammarco Vetrocoke (GV) solution is used to absorb carbon dioxide from the process gas thus reducing carbon dioxide content from 17.72% to 0.05% in gas mixture in CO2 absorber.

GV solution contains

Potassium Carbonate Glycine Di Ethanol Amine Vanadium penta oxide

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT CARBON DIOXIDE REMOVAL

In this Glycine and DEA are used as activator. Vanadium Penta oxide works as corrosion

inhibitor. GV solution rich in Carbon dioxide is

regenerated in HP & LP regenerators by giving heat & Carbon dioxide is sent to Urea Plant.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT METHANATION

Oxides are harmful for synthesis converter catalyst. 0.25 % Carbon monoxide from LTS outlet and 0.05% Carbon dioxide from CO2 Absorber are converted into methane in this step.CO+3H2↔ CH4+H2O+HEAT CO2+4H2↔ CH4+2H2O+HEAT

Catalyst Volume 30 M3 Catalyst type PK-5 of HTAS. The exit process gas (Synthesis Gas) contains mainly a

mixture of hydrogen and nitrogen in the ratio of 3:1.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT SYNTHESIS GAS COMPRESSION

Synthesis gas is compressed to 210 Kg/cm2g in synthesis gas compressor. This compressor has four stages and one recycle stage. This compressor was supplied by BHEL.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT AMMONIA SYNTHESIS

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT AMMONIA SYNTHESIS

Conversion of this gas mixture into ammonia takes place in TOPSOE-S200 radial flow converter. Gas inlet temperature is 224 deg C. Converter has two beds with inter-bed heat exchanger.

3H2+N2↔2NH3+HEAT Catalyst volume is 100 M3. Type of catalyst KM1R/KM1 of HTAS. Converter outlet gas at 455 deg C is cooled in various

heat exchangers and finally separated at 2 deg C in Ammonia Separator.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT REFRIGERATION SYSTEM

Gas mixture containing ammonia is cooled down to separate liquid ammonia from the gases by providing ammonia refrigeration. Separated liquid ammonia is sent to Urea Plant at 2 deg C temperature. In case Urea Plant is not in operation, product Ammonia can be sent to Ammonia Storage at -33 deg C.

The operating pressure of chillers 0.05 Kg/cm2g 3.5 Kg/cm2g 6.5 Kg/cm2g

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT UTILITIES : STEAM SYSTEM

Steam Type SH SM SLQuality Superheated PressureKg/cm2g 110 38 3.5 Temperature C 510 381

260 There are two service boilers and two HRSG boilers

in offsite which can generate 100te/hr each at 112Kg/cm2 and 510 DegC. Normally one service boiler and one HRSG boiler are in service. High pressure steam from boiler is distributed to Ammonia plant and Urea plant. In KSFL SH steam pressure is maintained by Offsite.

The SH steam is used in running Syn gas turbine and CO2 turbines.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT UTILITIES : ELECTRIC POWER

Alternating Current 11000 V 3 phase 50 Hz 3300 V 3 phase 50 Hz 415 V 3 phase 50 Hz 240 V 1 phase 50 Hz

Instrumentation and Control

115 V 1 phase 50 Hz

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT UTILITIES : COOLING WATER

Inlet temperature to the unit 34C Outlet temperature from the unit 44C Fouling factor for shell side 0.0006

m2hC/Kcal

Fouling factor for tube side 0.0006 m2hC/Kcal

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT UTILITIES : COOLING WATER

Ammonia cooling tower was designed by Paharpur.

There are six cells and each cell is provided with an induced draft fan.

There are three cooling water pumps out of which one is motor driven and two are condensing turbine driven.

The normal cooling water flow is 20,000 M3/hr and CW header pressure is 3 Kg/cm2g.

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT UTILITIES : PURE NITROGEN

In KSFL Nitrogen generation plant is not available. So Pure Nitrogen is purchased as per requirement from outside agencies

Quality of Nitrogen Nitrogen plus noble gases 99.99 % vol (min.) Carbon dioxide NT Carbon monoxide NT Water NT Oxygen 10 ppm (max.) Pressure 6 Kg/cm2g Temperature 40 C

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT PRODUCT SPECIFICATION

Ammonia Quality Ammonia 99.5 wt % max. Moisture 0.5 wt % max. Oil 10 ppm max. Temperature 12/-33 C Pressure 25/5 Kg/cm2g

KRIBHCO SHYAM FERTILISERS LTDAMMONIA PLANT PRODUCT SPECIFICATION

Carbon Dioxide:

Composition, dry: CO2 98.7 % vol H2 0.8 % vol N2 0.5 % vol Temperature 40 C Pressure 0.8Kg/cm2g Water saturated


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Ammonia Process Description-1

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