project report on liquid nitrogen

8/11/2019 Project Report on Liquid Nitrogen

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Project Report On

MANUFACTURING OF LIQUID NITROGEN

Submitted by

TAMBE NINAD RUPCHAND -U07CH152

KATARIWALA JAYMIN SANJAYKUMAR -U07CH123

B.Tech IV

Chemical Engineering

Year 2010-2011

Under the Guidance of

MR. V.N.LAD

Assistant Professor

Chemical Engineering Department

SVNIT

Chemical Engineering DepartmentSardar Vallabhbhai National Institute of Technology, Surat


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CERTIFICATE

This is to certify that the project report titled MANUFACTURING OF LIQUID

NITROGEN

submitted by Mr. TAMBE NINAD RUPCHAND Roll No.U07CH152 and Mr. KATARIWALA JAYMIN SANJAYKUMAR Roll No

U07CH123is a record of bonafide work carried out by them, in partial fulfillment of the

requirement for the award of the Degree of Bachelor of Technology (Chemical

Engineering).

Date: -

Examiner 1: ____________ Examiner 2: ____________

GUIDE

(Mr.V.N.Lad)

Assistant Professor

HOD

(Dr. M. Chakraborty)

Assistant Professor & Head

Chemical Engineering Department Chemical Engineering Department


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ACKNOWLEDGMENT

I would like to express my deep sense of gratitude to my guide Mr.V.N.Lad (Assistant

Professor, CHED, SVNIT, SURAT) forhis valuable guidance and motivation and for his

extreme cooperation to complete my seminar work successfully.

I would like to express my sincere respect and profound gratitude to Dr. M.

Chakraborty (Assistant Professor & Head),of Chemical Engineering Department for

supporting me and providing the facilities for my seminar work.

I appreciate all my colleagues whose direct and indirect contribution helped me a

lot to accomplish this seminar work.

I would also like to thank all the teaching and non teaching staff for cooperating

with me and providing valuable advice which helped me in the completion of this seminar.

TAMBE NINAD RUPCHAND

KATARIWALA JAYMIN SANJAYKUMAR


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CONTENTS

Chapter Page

No

1. Introduction 6

2. Demand and Supply Of Product 7

3. Process Selection And Description (MSDS Of Chemicals Involved) 8

4. Material Balance and Energy Balance 16

5. Thermodynamics 20

6. References 22


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LIST OF MAIN FIGURES

Figure

No

Title Pg

No

1 Sales of Liquid gases 7

2 Process flow diagram of Linde-Frankl process 10

3 Entropy(S) Vs Temperature (T) 20

4 Pressure Vs Temperature (T) 21


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Chapter 1: Introduction

Liquid nitrogenis nitrogen in a liquid state at a very low temperature. It is produced

industrially by fractional distillation of liquid air. Liquid nitrogen is a colorless clear

liquid with density of 0.807 g/mL at its boiling point and a dielectric constant of

1.4. Liquid nitrogen is often referred to by the abbreviation, LN2or "LIN"

Liquid nitrogen is a cryogenic liquid. At atmospheric pressure, it boils at 195.8

C. When insulated in proper containers such as Dewar flasks, it can be transported

without much evaporative loss.

At atmospheric pressure, liquid nitrogen boils at 77 K (196 C; 321F) and is

a cryogenic fluid which can cause rapid freezing on contact with living tissue, which may

lead to frostbite. When appropriately insulated from ambient heat, liquid nitrogen can be

stored and transported, for example in vacuum flasks. Here, the very low temperature is

held constant at 77 K by slow boiling of the liquid, resulting in the evolution of nitrogen

gas. Depending on the size and design, the holding time of vacuum flasks ranges from a

few hours to a few weeks.

Uses:

Liquid nitrogen is a compact and readily transported source of nitrogen gas without

pressurization. Further, its ability to maintain temperatures far below the freezing point of

water makes it extremely useful in a wide range of applications, primarily as an open-

cycle refrigerant, including:

as a coolant for CCD cameras in astronomy

to store cells at low temperature for laboratory work

in cryogenics

as a source of very dry nitrogen gas

for the immersion freezing and transportation of food products

for the cryopreservation of blood, reproductive cells (sperm and egg), and

other biological samples and materials

as a method of freezing water pipes in order to work on them in situations where a

valve is not available to block water flow to the work area

in cryotherapy for removing unsightly or potentially malignant skin lesions such

as warts and actinic keratosis

in the process of promession, a way to dispose of the dead

for cooling a high-temperature superconductor to a temperature sufficient toachieve superconductivity

For the cryonic preservation of humans and pets in the hope of future reanimation.

to preserve tissue samples from surgical excisions for future studies

to shrink-weld machinery parts together


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as a coolant for vacuum pump traps and in controlled-evaporation processes in

chemistry.

as a coolant to increase the sensitivity of infrared homing seeker heads of missiles such

as the Strela 3

as a coolant to temporarily shrink mechanical components during machine assemblyand allow improved interference fits

as a coolant for computers

in food preparation, such as for making ultra-smooth ice cream.

Like dry ice, the main use of liquid nitrogen is as a refrigerant. Among other things, it is

used in the cryopreservation of blood, reproductive cells (sperm and egg), and other

biological samples and materials. It is used medically in cryotherapy to remove cysts and

warts on the skin. It is used in cold traps for certain laboratory equipment and to cool X-ray detectors. It has also been used to cool central processing units and other devices in

computers which are overclocked, and which produce more heat than during normal

operation

Liquid nitrogen production is an energy-intensive process. Currently practical

refrigeration plantsproducing a few tons/day of liquid nitrogen operate at about 50%

of Carnot efficiency

CHAPTER 2: DEMAND SUPPLY DATA FOR LIQUID NITROGENCOMMERCIAL ANALYSIS

Beside liquid nitrogen ,whose application are described below ,industrial gases include-

oxygen argon, acetylene ,hydrogen ,helium and others such as carbon monoxide,nitrous

oxide and other noble gases. The global market share is given as below:-

Figure 1: sales of Liquid gases

Sales

liquid oxygen

ln2

argon

carbon dioxide

acetylene

hydrogen

helium

other


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CHAPTER 3:PROCESS SELECTION AND DESCRIPTION

AIR SEPERATION TECHNOLOGY

Though there are differences in process details displaying desired product mix and other

factors, all air separation plants make use one of the following two types of process

technology:

Cryogenic plants:The air separation technique used in cryogenic plants produce gas and

Liquid products (liquid oxygen, liquid nitrogen etc.) using very low temperature

distillation

which separates air components and produce desired product purities.

Non-cryogenic plants:The air separation technique used in non cryogenic plants produce

gaseous products with near-ambient temperature separation processes. They use

differences in properties like molecular structure, size and mass to produce oxygen or

nitrogen.

As our area of interest is liquification ,this can be done by Low temp. rectification of

liquid air.

This process mainly comprises of two steps. One is the liquefaction & then the separation

of liquid air into oxygen & nitrogen. Since the process mainly requires low temp.,

refrigeration is necessary. Different cycles are in use to have required refrigerating effect

1. Heylandt liquid nitrogen process

2. Claude process

3. Linde frankl process

4. Membrane separation technology

Out of the above processes the Claude process and lindey frankl process are really

important processes for the manufacture of liquid nitrogen.

Briefly giving an overview of these two processes

CLAUDE PROCESS:

This process is characterized by the double expansion engine. After passing through the

preliminary heat exchanger, at 60 atm pressure, part of the air traverses the liquefier from

top to bottom & is admitted to the base of the dephlagmetar after expanded to 4 atm.The

reset is expanded like wise to 4 atm,in the first stage of the expansion engine, after which

it is again separated into two portions. One is added to the partially liquid air behind the

valve; the other is warmed by passing up the upper part of the liquefier, & is then

expanded to 1 atm.

In the second stage of the engine, the expanded air there upon mixes with the cold

nitrogen vapor emerging from the top of the column & returns through the lower part of

the liquefier & through the preliminary heat exchanger. The oxygen in this air is wasted.


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The refrigerant between the tubes of the dephlagmator is liquid nitrogen from the column,

part of which is withdrawn through tube.

LINDE-FRANKL PROCESS:

This is the most important process for the commercial production of liquid nitrogen in this

process at first air is filtered & compressed to 6.8 atm in turbo compressor. During the

compression cooling is done to maintain the temp to 35 -400C.

After compression the ,stream is passed through reciprocating compressor to increase the

pressure to about 200atm.Here the air temp is maintained at 4-80C by intermediate cooling

between stages using cold water obtained by heat exchanger. Then the air goes through

high pressure heat exchanger where the temp of air is brought down to about-120 -140 0C.

Now the air undergoes expansion to about 6.5 atm in the expansion engine .The

temperature of air is brought down to -170 to-1740Cby joule Thompson effect. Now the

air will be in liquid.This saturation liquid is fed to Linde rectification column. This column

may be single, double or compound depending on requirement. the liquid product coming

out will have a purity of about 99.4 -99.99%.This liquid is partially vaporized in

condenser, to liquefy the nitrogen vapor &the rest may be taken as liquid product or it

may be obtained in gaseous state if it is used for cooling of incoming air, the other

products that obtained are pure nitrogen of purity above 98% & waste nitrogen product of

purity of about 92-96%.These cold streams are utilized for cooling air, this process is most

economical for tonnage nitrogen plants &most widely used in the world


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Figure2: flow diagram of Linde-Frankl process

Process Variables

1.

Initial temperature: The initial or the entrance temp for air is an independent variable.

Although it varies from 10 to 500C depending on the weather conditions and the type of

after cooler, for most cases, it is assumed as 27-300C.

2. Initial pressure: This is an important variable; it is independent in the case of liquid

oxygen process. The lowest allowable value of pressure is controlled by the saturation

temp. Of air or nitrogen, this must be higher than the boiling point of oxygen at column

pressure. In a double column, the air pressure must be such that the nitrogen will condense

at the temp of boiling point of oxygen in order to produce reflux. This will be in the 4-

6.5atm range, depending on the pressure in the lower pressure column, and on the

necessary temperature difference in the condenser boiler.

3. Temperature approaches: An analysis of the process shows that it is necessary to

establish the minimum temp approaches for heat exchangers.For the exchange of sensible

heat, the minimum approach has to be 3-50C

4. Intake temperature to expander: this variable has the flexibility of being at almost any

value between the room temp and one close to that of air liquefaction, without appreciableeffect on the efficiency of expander. It is so chosen that the exhaust is saturated vapor.

5. Purity of product gases: this is fixed at some value less than 100%,with due regard to

certain limitation that may set a definite upper limit with a single column.


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6. Heat leak: this is one of the most difficult variables to be selected since it depends on

factors which cannot readily be evaluated in advance. For e.g. the size of the plant is of at

most importance. Although the leak on an hourly basis increases when expressed the basis

increases as plant size increases when expressed the basis of a unit of air treated or oxygen

produced, it decreases and in large plants, is almost negligible.

7. Energy requirement: once the various quantities, temp, pressure are established the

work done by the compressors and expanders, and hence the energy requirements can be

easily calculated.

8. Sizes of equipment units:The thermodynamic analysis plays an important role in this

variable, since it deals with the driving forces in the heat exchangers and in distillation

columns.

The type of column chosen also plays a big role in the operation of the unit. There

are 3 types of columns that can be used for rectification namely simple, double and

compound. Simple consists of only an exhausting column and liquid feed to it consists

only the reflux. It has an adv of simplicity and economy of distribution and construction.

The compound column has both exhausting and enriching sections, but it must be

provided with a source of refrigeration at a very low temp, i.e. below the B.P.of nitrogen

at the operating pressure of the column.

The double column has two rectification columns operated at two different pressures, so

chosen that the nitrogen at high pressure column condenses at a temperature above the

boiling point of oxygen of low pressure column. Usually the pressure in the high pressure

column is 6-7 atm and in the other is 1.5-2 atm. This has the adv of high yield without

auxiliary refrigeration, but it is expensive and complicated to manufacture. But on the

tonnage scale, double column is preferred of high yield and high purity.

Selection of Process

Prior to the selection of the process it should be emphasized that there are so many

adjustable variables involved, it is very difficult to put all on a comparable basis. Usually

on the smallest scale, the most important economic factors are capital and labor charges.

Thermodynamic efficiency and hence power charges for compression are of less

consequence.

Charges for material such as compressor oil, chemicals for air purification are small in

relation to the other costs. The labor charges also decreases when the scale increases and

in this cases the capital costs and power costs dominate. When the plant produce a liquid

product, as in this case the power requirement to provide necessary refrigeration is

considerably increased and thermodynamic efficiency is of much importance.


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The essential requirement on a general scale is a cheap and simple plant, easy to operate

for which a thermodynamic efficiency is not needed. But if the liquid is produced on a

large scale, the thermodynamic efficiency becomes important.

As the purpose of this project is to design large scale oxygen product plant the only

process that seems economical is the LINDE FRANKLPROCESS.

As the most important adv here is the high purity of liquid nitrogen (99.5) %, although the

work of liquefaction of air is about 3.5kwh/gallon which is relatively higher than other

process. Also the outgoing streams from the rectification column are used effectively in

supplying the required refrigeration for cooling the incoming air.

In view of all the above cited advantages the process. For this project is linde-frankl.

Material Data Safety Sheet

1. Chemical Product

Product Name:Nitrogen, refrigerated liquid

Trade Names:Liquid Nitrogen

Chemical Name:Nitrogen

Synonyms:Nitrogen (cryogenic liquid)

Chemical Family:Cryogenic liquid

2. Hazards Identification

Extremely cold liquid and gas under pressure.

Can cause rapid suffocation.

Can cause severe frostbite.

May cause dizziness and drowsiness.

Self-contained breathing apparatus and protective clothing may be required by rescueworkers.

Under ambient conditions, this is a colorless, odorless, cryogenic liquid.OSHA REGULATORY STATUS:This material is considered hazardous by the OSHA

Hazard

Communications Standard (29 CFR 1910.1200).

POTENTIAL HEALTH

EFFECTS:

Effects of a Single (Acute) Overexposure

Inhalation.Asphyxiant. Effects are due to lack of oxygen. Moderate concentrations may

cause headache, drowsiness, dizziness, excitation, excess salivation, vomiting, andunconsciousness. Lack of oxygen can kill.

Skin Contact.No harm expected from vapor. Cold gas or liquid may cause severe

frostbite.

Swallowing.An unlikely route of exposure, but severe frostbite of the lips and mouth may


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result from contact with the liquid.

Eye Contact.No harm expected from vapor. Cold gas or liquid may cause severe frostbite.

Effects of Repeated (Chronic) Overexposure.No harm expected.

Other Effects of Overexposure.Asphyxiant. Lack of oxygen can kill.

Medical Conditions Aggravated by Overexposure.The toxicology and the physical and

chemical properties of nitrogen suggest that overexposure is unlikely to aggravate existing

medical conditions.

3. Composition

COMPONENT CAS NUMBER CONCENTRATION

Nitrogen 7727-37-9 >99%

4. First Aid Measures

INHALATION: Remove to fresh air. If not breathing, give artificial respiration. Ifbreathing is difficult, qualified personnel may give oxygen. Call a physician.

SKIN CONTACT: For exposure to liquid, immediately warm frostbite area with warm

water not to exceed 105F (41C). In case of massive exposure, remove clothing while

showering with warm water. Call a physician.

SWALLOWING: An unlikely route of exposure. This product is a gas at normal

temperature and pressure.

EYE CONTACT: Immediately flush eyes thoroughly with warm water for at least 15

minutes. Hold the eyelids open and away from the eyeballs to ensure that all surfaces are

flushed thoroughly. See a physician, preferably an ophthalmologist, immediately.

5. Fire Fighting Measures

FLAMMABLE PROPERTIES:Nitrogen cannot catch fire.

SUITABLE EXTINGUISHING MEDIA:Nitrogen cannot catch fire. Use media

appropriate for surrounding fire

PRODUCTS OF COMBUSTION:Not applicable.

Specific Physical and Chemical Hazards.Heat of fire can build pressure in cylinder andcause it to rupture. No part of cylinder should be subjected to a temperature higher than

125F (52C). Liquid nitrogen containers are equipped with pressure relief devices.

Venting vapors may obscure visibility. Liquid causes severe frostbite, a burn-like injury

6. Accidental Release Measures

Personal Precautions.Asphyxiant. Lack of oxygen can kill. Evacuate all personnel from

danger area. Use self-contained breathing apparatus and protective clothing where needed.

Liquid causes severe frostbite, a burn-like injury. (See section 2.) Shut off flow if you cando so without risk. Avoid contact with spilled liquid and allow it to evaporate. Ventilatearea of leak or move container to a well-ventilated area. Test for sufficient oxygen,

especially in confined spaces, before allowing reentry.

Environmental Precautions. Prevent waste from contaminating the surrounding

environment. Keep personnel away. Discard any product, residue, disposable container, or

liner in an environmentally acceptable manner, in full compliance with federal, state, and

local regulations. If necessary, call your local supplier for assistance.


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7. Handling and Storage

PRECAUTIONS TO BE TAKEN IN HANDLING:Do not get liquid in eyes, on skin, or

on clothing. Never allow any unprotected part of your body to touch uninsulated pipes or

vessels containing cryogenic fluids. Flesh will stick to the extremely cold metal and will tear

when you try to pull free. For liquid withdrawal, wear face shield and cryogenic gloves (see

section 8).

Use a suitable hand truck to move containers. Always handle and store cryogenic containersin an upright position. Do not drop or tip containers, or roll them on their sides. Open valve

slowly. Close container valve after each use; keep closed even when empty. If valve is hard

to open, discontinue use and contact your supplier. For other precautions in using nitrogen,

see section 16.

PRECAUTIONS TO BE TAKEN IN STORAGE:Store and use with adequate

ventilation.

Store only where temperatures will not exceed 125F (52C). Do not store in a confinedspace.

Cryogenic containers are equipped with a pressure relief device and a pressure controlling

valve. Under normal conditions, these containers will periodically vent product. Useadequate pressure relief devices in systems and piping to prevent pressure buildup;entrapped liquid can generate extremely high pressures when vaporized by warming

8. Exposure Controls/Personal Protection

COMPONENT OSHA PEL ACGIH TLV-TWA (2007)

Nitrogen Not Established. Simple asphyxiant

ENGINEERING CONTROLS:

Local Exhaust.Use a local exhaust system, if necessary, to prevent oxygen deficiency.

Mechanical (General).General exhaust ventilation may be acceptable if it can maintain an

adequate supply of air.

Special.None

Other.None

PERSONAL PROTECTIVE EQUIPMENT:

Skin Protection. Wear loose-fitting, cryogenic gloves, metatarsal shoes for container

handling,

and protective clothing where needed. Cuffless trousers should be worn outside the shoes.

Select in accordance with OSHA 29 CFR 1910.132 and 1910.133. Regardless of protective

equipment, never touch live electrical parts.

Eye/Face Protection. Safety glasses and a full face shield are recommended. Select in

accordance with OSHA 29 CFR 1910.133.

Respiratory Protection. Use air-supplied respirators where local or general exhaust

ventilation is inadequate. Air-supplied respirators must be used in confined spaces or in an

oxygen- deficient atmosphere. Respiratory protection must conform to OSHA rules as

specified in 29 CFR 1910.134. Select in accordance with 29 CFR 1910.134 and ANSI

Z88.2.


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9. Physical and Chemical Properties

APPEARANCE: Colorless liquid

ODOR: Odorless

ODOR THRESHOLD: Not applicable

PHYSICAL STATE Cryogenic liquid

pH: Not applicable.

MELTING POINTat 1 atm: -346F (-210C)

BOILING POINTat 1 atm: -320.44F (-195.80C

FLASH POINT(test method): Not applicable

EXPANSION RATIOfor liquid at boiling 1 to 696.5

point to gas at 70F (21.1C):

EVAPORATION RATE(Butyl Acetate = 1): Not applicable

FLAMMABILITY: Nonflammable

FLAMMABLE LIMITS IN AIR, % by volume: LOWER:Not applicable.UPPER:Not applicable

LIQUID DENSITYat boiling point and 1 atm: 50.7 lb/ft3(808.5 kg/m3)

VAPOR PRESSUREat 68F (20C): Not applicable

VAPOR DENSITYat 70F (21.1C) and 1 atm 0.0724 lb/ft3(1.160 kg/m3)

SPECIFIC GRAVITY(H2O = 1) at 19.4F (-7C): Not available.

SPECIFIC GRAVITY(Air = 1) at 70F (21.1C) 0.967

and 1 atm:SOLUBILITY IN WATER,vol/vol at 32F (0C): 0.023

PARTITION COEFFICIENT: n-octanol/water: Not availableAUTOIGNITION TEMPERATURE: Not applicable.

DECOMPOSITION TEMPERATURE: Not available

PERCENT VOLATILES BY VOLUME: 100

MOLECULAR WEIGHT: 28.01

MOLECULAR FORMULA: N2

6. Stability and ReactivityCHEMICAL STABILITY: Stable

CONDITIONS TO AVOID: High temperatures, exposure to lithium,neodymium, titanium and magnesium

INCOMPATIBLE MATERIALS: None known.

HAZARDOUS DECOMPOSITION PRODUCTS:None known.

POSSIBILITY OF HAZARDOUS REACTIONS: May Occur

Under certain conditions, nitrogen can react violently with lithium, neodymium, titanium

[above1472F (800C)], and magnesium to form nitrides. At high temperature, it can also

combine with oxygen and hydrogen.

7. Toxicological Information

ACUTE DOSE EFFECTS:Nitrogen is a simple asphyxiantSTUDY RESULTS: None known

8. Ecological Information

ECOTOXICITY:No adverse ecological effect expected.


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OTHER ADVERSE EFFECTS:Nitrogen does not contain any Class I or Class II ozone-

depleting chemicals9. Disposal Considerations

WASTE DISPOSAL METHOD: Do not attempt to dispose of residual or unused

quantities. Return cylinder to supplier.

CHAPTER 4. MASS AND HEAT BALANCE

Basis: 10 tonnes/day ln2 ,

10 tonnes/day gaseous nitrogen and 2 tonnes per day waste nitrogen gas

So total nitrogen production = 22 T/day

= (22*1000)/(24*14)

= 65.476 kg moles/hr

At standard temperature and pressure,

1kg.mole occupies 22.4m3

Nitrogen produced in volumetric units =65.476*22.4

=1466.66Nm3/hr

Standard analysis of air:

Component volume%

Nitrogen 78.03

Oxygen 20.99

Argon 0.94

Hydrogen 0.01

Helium 0.0003

Krypton 0.00011

Xenon 0.00009

Carbon dioxide 0.03-0.06

Moisture 0.02-0.05

Quantity of intake air:

Capacity of the unit = 1466.66m3/hr of nitrogen

Volume % of nitrogen in the air =78%

Quantity of air needed =1466.66/0.78

=1880.34m3/hr

Assuming about 15% less of air due to removal of moisture, CO2and from possible leaks.

The quantity needed = 1880.34+1880.34 *.15

=2162.393m3/hr

Thus this much amount of air is required for production of 10 tonnes of liquid nitrogen

Heat balance: At turbo compressor


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Mass Balance at Columns:

Let the liquid to vapor ratio at the top of both columns to be .58

So L1/V1=L2/V2=.58

Suffix 1 for upper column

Now V2=34.20472

L2=.58*34.20472=19.8387kg moles /hr

This L2 comes out of condenser in vapor state and fed at the top of upper column as

liquid after passing through expansion valve

.58V1+19.838=V1

.42V1=19.838 so V1=4723.5kg moles/hr

The amount L1 refluxed to the lower column after condensation occurs in the condenser

=.58*4723.5

= 2739.63 kg moles/hr

Let F=amount of feed =96.834kgmoles/hr

W=bottom product from lower which is refluxed back to the top column ( rich liq)

S=side stream from lower column, which is refluxed back to top column (impure

liquid)

Xf=mole fraction of N2in feed = .79

Xw=mole fraction of N2 inrich liquid =.65

Xs= mole fraction of N2 inIPL=.96

X1= mole fraction of N2 in top product = .9999

Now, from overall& component balance

F=W+S+L2 ---- (1)

FXF =WXw +SXs + X1L2---- (2)

From (1) 96.834 = W + S +19.8387

W +S = 76.99----- (3)

From (2) (96.834*.079) = (W*.65)+(S*.96)+(19.8387*0.9999)----- (4)

56.67 = .65W + .96S

Multiplying (3) by .65

Solving (3) and (4) we get

S=21.377419 kg moles /hr

&

W = 76.67-21.377419 = 55.61258 kg moles/hr


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CHAPTER 5: THERMODYNAMICS

The simplest liquefaction process is the Linde or Joule-Thompson expansion cycle Some of the

steps in the process are

1. Gas is compressed at ambient pressure

2. Cooled in a heat exchanger

3. Passed through a throttle valve - isenthalpic Joule- Thompson expansion - producing liquid

Figure3: Entropy(S) Vs Temperature (T)

The ideal work of liquefaction for nitrogen is only 0.207 kWh/kg

(0.094kWh/lb)


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Figure 4: Pressure Vs Temperature


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References

Department of mechanical and aerospace engineering-NASA hydrogen research-

pdf

US Patent 4072023 - Air-rectification process and apparatus Air liquefaction:distillation

Encyclopedia of separation science 2007 science direct

R.Agrawal, D.M. herron

MSDS worldwide library-praxair

Cryogenic air separation history and technological progress

www.linde-india.com

American Chemical society journal , some aspects of gas separation at low

temperatures by W. H. Granville

Wikipedia

5pengineeringcro&eng srl -nitrogenhpn(pdf)
http://www.linde-india.com/http://www.linde-india.com/http://www.linde-india.com/


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project report on liquid nitrogen

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