Separation Of Air

REPORT ON

AIR SEPARATION PLANT Submitted in partial fulfillment for the award of the degree Of

BACHELOR OF TECHNOLOGY IN MECHANICAL ENGINEERING Submitted by 1.) C.HARI SURYA

11J41A0320

2.) GADDI RAJATH

11J41A0329

3.) KALI CHARAN ORUGANTI

11J41A0339

4.) M.VISHNU

11J41A0359

Under the Supervision of M.RAVI Sr. manager Utilities Department

MALLA REDDY ENGINEERING COLLEGE (Autonomous) (Affiliated to Jawaharlal Nehru Technological University Hyderabad) HYDERABAD 1

MALLA REDDY ENGINEERING COLLEGE (Autonomous) Maisammaguda, Dhulapally, Secunderabad. 500 100

(Affiliated to JNTUH - Hyderabad) Ph: 040-64634234. Fax: 040-23792153 --------------------------------------------------------------------------------------------------------------------------

Department of Mechanical Engineering

CERTIFICATE This is to certify that the industry oriented mini project entitled “STUDY OF AIR SEPARATION PLANT” has been submitted in partial fulfillment of the requirement for the award of degree of Bachelor of Technology in Mechanical Engineering discipline of JNTUH, Hyderabad for the academic year 2014-15 is a record bonafide work carried out by 1.) C.HARI SURYA

11J41A0320

2.) GADDI RAJATH

11J41A0329

3.) KALI CHARAN ORUGANTI

11J41A0339

4.) M.VISHNU

11J41A0359

Supervisor HOD V.NARASIMHA REDDY ASSOCIATE PROFESSOR MECHANICAL ENGINEERING

2

Acknowledgement It is our pleasure to express our thanks to VISAKHAPATNAM STEEL PLANT (RASHTRIYA ISPAT NIGAM LIMITED), our sincere thanks to Training and Development Centre, for allowing us to do our project work for the partial fulfillment of the B.Tech Degree in your reputed organization. It helped us a lot in gaining industrial knowledge and gave us an over view on the practical application of our degree in industries. We specially thank Sri M.RAVI, Sr. Manager of Utilities Department for briefing us the project and guiding us throughout our project time. We would also thank Mr. M.T.JALANDHAR REDDY, Utilities Department for encouraging and guiding us in completing our project work in spite of his busy schedule. We would also like to thank Sri K.HARI BABU Sir DGM (Utilities), in-charge of this project, for his support in completing our project. We also take chance to convey our sincere thanks to all the Utilities Department Employees who helped us in finishing our project.

By C.HARI SURYA GADDI RAJATH KALI CHARAN ORUGANTI M.VISHNU

3

RASHTRIYA ISPAT NIGAM LIMITED VISAKHAPATNAM STEEL PLANT DEPARTMENT OF ASP Certificate of appreciation This is to Certify that this project report entitled ” STUDY OF AIR SEPARATION PLANT ” has being submitted in partial fulfillment for the award of degree of BACHELOR OF TECHNOLOGY in Department of Mechanical Engineering is a inplant training carried out by C.HARI SURYA

(11J41A0320)

GADDI RAJATH

(11J41A0329)

O.KALI CHARAN

(11J41A0339)

M.VISHNU

(11J41A0359)

Their work as project trainee in appreciated and conduct was found good. I wish them good luck in all his future Endeavour.

External Guide: Sri M.RAVI Sr. Manager (Mech.) Utilities Dept.

Visakhapatnam Steel Plant.

4

Contents

Chapter 1:- INTRODUCTION ABOUT VISAKHAPATNAM STEEL PLANT

1. INTRODUCTION TO AIR SEPERATION PLANT MAJOR CONSUMERS, BRIEF PROCESS……….. 9 STORAGE AND DISTRIBUTION……………………13 CYLINDER FILLING STATION………………………. 14 GASEOUS STORAGE SYSTEM……………………... 14

2. CONSTRUCTION, WORKING AND MAINTENANCE OF COMPRESSOR CENTRIFUGAL COMPRESSOR………16 AIR FILTERS………………………………22 SUCTION SILENCER……………………24 INLET GUIDE VANE…………………….24 3. BEARINGS AND SEALS JOURNAL BEARINGS…………………………..27 LABYRINTH SEALS……………………………..27 O-RING SEALS……………………………………28 INTERCOOLER……………………………………29 AFTERCOOLER…………………………………….31 LUBRICATION SYSTEM………………………….31 COUPLING………………………………………….32

4. WORKING OF AIR SEPARATION PLANT WORKING OF CHILLER…………………………34 AIR-WATER TOWER…………………………….35 NITROGEN-WATER TOWER………………….35 AIR DRIERS………………………………………36 HEAT EXCHANGERS…………………………..37

5

DISTILLATION COLUMN………………………38 CHILLERS…………………………………………39

5. CONCLUSION………………………………………………………………………43

6

ABSTRACT

An air separation plant is one in which the various components of air separation plant namely Oxygen, Nitrogen, Argon are separated and are sent to other departments where they are used for cooling, gas cutting, providing an inert atmosphere and so on. In this project, we discuss about the construction, working and maintenance of an air separation plant along with its uses. This project presents clear information about air separation plant with its components described clearly. This project also provides information about the maintenance of driers, distillation tower and air compressor which are the main parts of air separation plant. It also deals with the separation of these gases and their applications for different units in the steel plant. The gases obtained are stored in their liquid form in cryogenic tanks for further use.

7

Overview Separation of air in an air separation plant involves the following steps:1. Compressing the air through an air compressor. 2. Sending the air to air driers to remove moisture, co2 and hydrocarbons. 3. Further cooling in the heat exchanger to cryogenic temperatures. 4. Reducing the pressure of a part of it in the turbine for distillation. 5. Separating out the components in the distillation tower. 6. Storing the liquefied gases in tanks for further use.

From the air-water tower, the cooled air is sent to the driers which remove any content of moisture, carbon-di-oxide and hydrocarbons. After this it is passed through a filter where any impurities such as activated alumina are removed. Now the air is passed to a heat exchanger where its temperature is further reduced to cryogenic levels. From the heat exchanger, this air is sent to the medium pressure coloumn in the distillation tower. A part of the air from the heat exchanger is sent to the expansion turbine where its pressure is reduced and is then sent to the low pressure coloumn in the distillation tower. Finally, in the distillation tower, the compressed air is divided into its components and is liquefied. It is then sent into storage tanks where it is stored for further use.

8

9

10

INTRODUCTION OF VISHAKAPATNAM STEEL PLANT DESCRIPTION: Visakhapatnam Steel Plant, the first coastal-based steel plant of India is located 16km south east of destiny i.e., Visakhapatnam. Bestowed with technologies, VSP has an installed capacity of 3 million tones per annum of liquid steel 2.56 million tones of saleable steel. At VSP there is emphasis on total automation, seamless integration and efficient up gradation, which result in wide range of long and structural products to meet stringent demands of discerning customers within India and abroad.

VSP products meet exalting International quality standards such as JIS,DIN, BIS, BS, etc.VSP has the distinction to be the first integrated steel plant in India to become a fully ISO-9001 certified company. The certificate covers systems of all operational, maintenance, services units. Besides purchase systems, Training and marketing functions spreading over 4 regional Marketing offices and 22 stockyards located all over the country.

VSP by successfully installing & operating efficiently Rs.460 crore worth Of pollution control and environment control equipments and converting the barren landscape by planting more than 3 million plants has made steel plant township and the surrounding areas into a heaven of lush greenery. This has made Steel Township a greater, cleaner and cooler place, which can boast of 3 to 4 degrees lesser temperature even in the peak summer as compared to Visakhapatnam city.

VSP exports pig iron & steel products to Sri Lanka, Myanmar, Nepal, Middle East, USA & South East (Pig Iron). RINL-VSP was awarded “Star Trading House” status during 1997-2000. Having established a fairly dependable export market, VSP plans to make a continuous presence in the export market. Having a total manpower of about 17250 VSP has envisaged a labor productivity of not less than 230 tones per man-year of liquid steel, which is the best in the country and comparable with the international levels.

11

Modern Technology: In Visakhapatnam steel plant modern technology has been adopted in many areas of production, some of them for the first time in the country.  selective crushing of coal  7 meter tall coke ovens  dry quenching of coke  on ground blending of sinter base mix  conveyor charging and bell less top for blast furnace  cast house slag granulation for blast furnace  100% continuous casting of liquid steel  Gas expansion turbine for power generation, utilizing blast furnace top gas pressure.  Hot metal desulphurization  Extensive treatment facilities of effluents for ensuring proper environmental Protection.  Computerization for process control

 Sophisticated high speed and high production rolling mills

Major Production Units of VSP: - Raw Material Handling Plant (RMHP). - Coke Oven & Coal Chemical Department (C & CCD). - Sinter Plant (SP). - Calcining & Refractory Material Plant (CRMP) - Blast Furnace (BF). - Steel Melting Shop (SMS). - Light and Medium Merchant Mill (LMMM). - Medium Merchant and Structural Mill (MMSM). - Wire Rod Mill (WRM). - Roll Shop and Repair Shop (RS & RS).

Service Units (works): - Air Conditioning Systems (ACS). - Central Maintenance – Electrical (CME). - Central Maintenance – Mechanical (CMM). 12

- Civil Engineering Department (CED). - Electrical Repair Shop (ERS). - Electro-Technical Laboratory (ETL). - Energy Management Department (EMD). - Engineering Shops & Foundry (ES & F). - Environment Management Department (En MD). - Field Machinery Department (FMD). - Instrumentation Department (INSTN). - Information Technology Department (ITD). - Maintenance Management System (MMS). - Plant Design (PD). - Power Engineering Maintenance (PEM). - Production Planning & Monitoring Department (PPM). - Quality Assurance & Technology Development (QATD). - Raw Materials Department (RMD). - Refractory Engineering Department (RED). - Safety Engineering Department (SED). - Scrap & Salvage Department (SSD). - Spare Parts Cell (SPC). - Technical Services Department (TSD). - Telecommunications Department (TELE). - Terminal Power Plant (TPP). - Traffic Department - Utilities Department - Water Management Department (WMD)

Non – Works Departments: - Company Affairs Department (CA) - Corporate Strategic Management (CSM) - Finance & Accounts Department (F & A) - Management Services Department (MS) - Marketing Department (MKTG) - Materials Management Department (MM) 13

- Medical Department - Personnel Department - Town Administration Department (TA) - Training and HRD

Other Departments: - Mines Department - Projects Division

The principle of “5S” followed throughout Vishakhapatnam Steel Plan:

The „S‟

Meaning (Japanese)

What is involved

Objective

1 „S‟

Seiri - sorting out

-saving and recovering space

2 „S‟

Seiton - systematic arrangement

3 ‟S‟

Seiso - Spic and Span

4 „S‟

Seikatsu – standardization

5 „S‟

Shitsuke - Self Discipline

-Segregate necessary from unnecessary -Remove what is not required -Decide on frequency of sorting -Arranging in order -A place for everything and every useful thing in its place -Clearing the work place/equipment -Ensuring – Tip Top condition -Working methodology (procedures and work instructions) -Forming the habit -Training -Be disciplined

Core values of RINL • Customer Satisfaction • Continuous Improvement • Commitment • Concern for environment • Creativity and Innovation 14

-Minimizing search time -De-cluttering the workplace

-Inspecting for problems -Taking corrective actions, faster -Achieving higher productivity and better quality -Doing it Right first time and every time

AIR SEPARATION PLANT Air separation plant is one of the major auxiliary units and is adjusted to meet the maximum daily demand of gaseous Oxygen, gaseous Nitrogen and gaseous Argon. The plant has the provision for the production of liquid Nitrogen and liquid Oxygen for storage and utilization during the period of shutdown of the plant.

MAJOR CONSUMERS: Total requirements of Oxygen, Nitrogen and Argon all over the plant for three million tones stage is 24.248 Nm3/hr and 32 Nm3/hr respectively. Out of this Steel Melting Shop (SMS) requires 97.3% of Oxygen for LD converters blowing and LD vessel heating. 65.47% of Nitrogen produced is consumed by Blast Furnace continuous casting department requirement of Argon for homogenization of steel is 93.75%. The basic principle is separation of main constituents of air i.e. Oxygen (Boiling Point of -182.8 degrees centigrade at 1atm pressure) and Nitrogen(Boiling Point of -195.7 degrees centigrade at 1atm pressure) that is carried out by liquefying the air and separating by utilizing the boiling point difference for distillation.

BRIEF PROCESS: Air is sucked from the atmosphere through a pulse type filter where the dust is removed and then compressed in an air compressor to 7.4KSCA (kg per square cm absolute). This air is pre-cooled in air water tower to 10 degrees centigrade and sent to purification unit for removal of moisture, carbon dioxide and other hydrocarbons. The purified air passes through the main heat exchanger where it is cooled to its dew point, currently with the outgoing product i.e. Oxygen, Nitrogen and waste Nitrogen from the rectification column. A part of air is taken at an intermediate point and expanded in an expansion turbine to provide necessary cold to compensate the thermal losses of the system. The air from the exchangers will be sent to distillation system, which separates air into Oxygen, Nitrogen and Argon.

15

For the production of Argon, a gaseous flow is picked at a suitable point in the upper column of the distillation system(where Argon contents are maximum) and sent to crude Argon rectification column to produce crude Oxygen containing 2-3% Oxygen and small amount of Nitrogen as impurities. Oxygen is separated in warm Argon purification unit, the Oxygen reacts with Hydrogen in presence of palladium (catalyst). Hydrogen required will be taken from water electrolysis plant (capacity 30 Nm3/hr). Nitrogen is separated by distillation in pure Argon column.

STORAGE AND DISTRIBUTION: Gaseous Oxygen and Nitrogen from cold box is compressed to 40KSCA, 10KSCA respectively by centrifugal compressors and supplied directly to the consumers by pipelines. The liquid Oxygen and Nitrogen will be stored in storage tanks and pumped to 40KSCA by centrifugal pumps and vaporized by water bath type with steam injection and supplied to consumers at the time of emergency. Liquid Argon from cold box is collected in the liquid Argon tanks and cold converters. From cold converters liquid Argon is vaporized in atmospheric vaporizers and supplied to con casting department at 7 KSCA.

CYLINDER FILLING STATION: Liquid Oxygen, Nitrogen and Argon will be pumped by reciprocating pumps to a pressure of 165KSCA, vaporized, filled and delivery into cylinders through manifolds of 4, 2, 2 respectively.

GASEOUS STORAGE SYSTEM: Gaseous Oxygen from the storage will be stored in 8 numbers if buffer vessels near SMS (Steel Melt Shop) of 100m3 water volume at 40KSCA. This pressure is reduced to 18KSCG and supplied to SMS. Gaseous Oxygen is stored near ASP in 3 numbers of 100m³ water volume buffer vessels and pressure is reduced to 12-18KSCG and supplied for autogenic needs all over the plant. Gaseous Nitrogen is stored in 6 numbers of buffer vessels of 125m³ water volume of 40KSCG, 2 numbers buffer vessels of 100 m³ water volume at 40KSCG for emergency needs of Blast Furnace. In addition, Nitrogen storage tanks are provided at desulphurization plant and SMS gas cleaning plant.

16

17

CENTRIFUGAL COMPRESSOR: Centrifugal compressor is a non positive or steady flow rotary compressor. A centrifugal compressor consists of an impeller rotating at high speed (20000-30000rpm). The impeller consists of a disc on which radial blades are attached. The air enters the impeller eye and flows radially outward with increasing pressure and temperature. In impeller a static pressure of air increases from eye to the tip in order to provide the centripetal force on the air. From the impeller the air enters a diffuser, which provides a gradually increasing area to convert kinetic energy to pressure energy. In Single stage centrifugal compressors a pressure ratio of 4:1 can be obtained. Pressure in multi stage compression can go upto 10 bar. The impeller may be a single sided or double sided. In double sided impeller suction takes place from both sides.

18

Components of a simple centrifugal compressor: A simple centrifugal compressor has the following four components: inlet, impeller/rotor, diffuser, and collector. If you look carefully at figure you will be able to identify each of these 4 components of the flow path. With respect to the figure, the flow (working gas) enters the centrifugal impeller axially from right to left. As a result of the impeller rotating clockwise when looking downstream into the compressor, the flow will pass through the volute's discharge cone moving away from the figure's viewer.

Discharge volute: qualitative view of the flow

Inlet The inlet to a centrifugal compressor is typically a simple pipe. It may include features such as a valve, stationary vanes/airfoils (used to help swirl the flow) and both pressure and temperature instrumentation. All of these additional devices have important uses in the control of the centrifugal compressor.

19

Centrifugal impeller: The key component that makes a compressor centrifugal is the centrifugal impeller. It is the impeller's rotating set of vanes (or blades) that gradually raises the energy of the working gas. This is identical to an axial compressor with the exception that the gases can reach higher velocities and energy levels through the impeller's increasing radius.

In

many

modern

high-efficiency

centrifugal

compressors the gas exiting the impeller is traveling near the speed

of

sound.

Impellers

are

designed

in

many

configurations including "open" (visible blades), "covered or shrouded", "with splitters" (every other inducer removed) and "w/o splitters" (all full blades). Figure 3.1 show open impellers with splitters. Most modern high efficiency impellers use "back sweep" in the blade shape. Euler‟s pump and turbine equation plays an important role in understanding impeller performance.

Diffuser The next key component to the simple centrifugal compressor is the diffuser. Downstream of the impeller in the flow path, it is the diffuser's responsibility to convert the kinetic energy (high velocity) of the gas into pressure by gradually slowing (diffusing) the gas velocity. Diffusers can be vaneless, vaned or an alternating combination. High efficiency vaned diffusers are also designed over a wide range of solidities from less than 1 to over 4. Hybrid versions of vaned diffusers include: wedge, channel, pipe and pipe diffusers. There are turbocharger applications that benefit by incorporating no diffuser. Bernoulli's fluid dynamic principal plays an important role in understanding diffuser performance.

Collector The collector of a centrifugal compressor can take many shapes and forms. When the diffuser discharges into a large empty chamber the centrifugal compressors collector may be referred to as a Plenum. When the diffuser discharges into a device that looks somewhat like a snail shell, bull's horn or a French horn, the collector is likely to be referred to as a volute or scroll. As the

20

Name implies, a collector‟s purpose is to gather the flow from the diffuser discharge annulus and deliver this flow to a downstream pipe. Either the collector or the pipe may also contain valves and instrumentation to control the compressor. For example, a turbocharger blow-off valve.

WORKING CONDITIONS OF THE COMPRESSOR: Stator motor winding 1 temperature Stator motor winding 2 temperature Stator motor winding 3 temperature Stator motor winding 4 temperature Stator motor winding 5 temperature Stator motor winding 6 temperature Motor drive end (DE) bearing temp Motor non-drive end (NDE) bearing temp Hot air temp Motor DE vibrations Motor NDE vibrations Suction pressure Stage 1 discharge pressure Stage 2 discharge pressure Stage 3 discharge pressure Stage 4 discharge pressure Oil pressure before compressor Cooling water flow Discharge pressure Discharge flow Suction flow Stage 1 Suction temperature Stage 1 Discharge temperature Stage 2 suction temperature Stage 2 discharge temperature Stage 3 suction temperature Stage 3 discharge temperature Stage 4 suction temperature Stage 4 discharge temperature After cooler temperature Radial bearing 1st stage temperature Radial bearing 2nd stage temperature Radial bearing 3rd stage temperature Radial bearing 4th stage temperature Bull gear drive end Bull gear pump end

94.4 ºc 91.8 ºc 92.5 ºc 59.6 ºc 59.4 ºc 91.9 ºc 63.3 ºc 63 ºc

130 130 130 130 130 130 83 83

120 120 120 120 120 120 75 75

92 ºc 11.7 microns 8.9 microns 147.06 mmWC 0.58 kg/cm² 1.93 kg/cm² 3.48 kg/cm² 6.16 kg/cm² 1.89 kg/cm² 1283.06 Nm³/hr 5.99 kg/cm² 84037.2 Nm³/hr 1171.5 mmWC 33 ºc 91 ºc 40 ºc 109 ºc 48 ºc 86 ºc 42 ºc 94 ºc 43 ºc 51 ºc 51 ºc 54 ºc 54 ºc 51 ºc 52 ºc

120 xx xx xx xx xx Xx xx xx xx xx xx xx

105 Xx Xx Xx Xx Xx Xx Xx Xx Xx Xx Xx Xx

138 xx 136 xx 121 xx 124 xx 80 80 80 80 80 80

133 53 131 56 116 57 119 55 75 75 75 75 75 75

21

Oil temperature after cooling Temperature of oil in tank Temperature of oil before oil cooler(tank) Differential pressure across air filter Differential pressure across oil filter 1st stage Vertical vibrations 1st Stage horizontal vibrations 2nd Stage vertical vibrations 2nd stage horizontal vibrations Pin 3rd vertical Pin 3rd horizontal Pin 4th vertical Pin 4th horizontal Bull gear vibrations compressor side Bull gear vibrations pump side

45 ºc 46.4 ºc 61 ºc

xx

52

55 xx

45 52

60.7mmWC 0.6kg/cm² 42.1 microns 31.3 microns 29.6 microns 68.9 microns 10.4 microns 9.3 microns 13.8 microns 14.1 microns 40.8 microns 40.4 microns

xx xx 144 144 144 144 126 126 126 126 178 178

1 1 100 100 100 100 88 88 88 88 126 126

Colour code for gas lines in ASP: Name of the gas Oxygen (99.5% purity) Oxygen (gen. purpose) Nitrogen (Low Pressure) upto 1kg/cm² Nitrogen(High Pressure) Upto 6kg/cm² Argon Compressed air Compressed air (dry)

Base colour Azure blue

First band Canary yellow

Second band Canary yellow

Azure blue

Canary yellow

Signal red

Canary yellow

black

-

Canary yellow

black

Black

Canary yellow Sky blue Sky blue

Blue white white

White

22

FEED AIR COMPRESSOR The bull gear of the compressor is run with the help of a 11KV D.C motor whose shaft is coupled to that of the bull gear. A flexible gear coupling is used to ensure that any misalignment between the shafts of the motor and the bull gear is compensated for. This coupling also reduces any vibration and damps any noise produced. The feed air compressor consists of inlet air filters which cleanse the incoming air of dust particles and foreign impurities. This air then passes through a suction silencer which helps in noise reduction. After passing through the suction silencer it is made to pass through an inlet guide vane which streamlines and regulates the flow of air. In cases the air filters get clogged with dust particles the air from the intake pipe is made to flow in the reverse direction through which the dust particles are blown off to the external atmosphere. The air from the inlet guide vane is then passed axially to the impeller which acts as feed and comes out radially into the intercooler. The cross section of the air flow passage increases with radius in order to convert the kinetic energy of the air into potential energy. The pressure at the end of compression is about 0.9 kg/cm². Now this air from the compressor passes through the intake pipes of the intercooler which is a large shell consisting of a large number of tubes through which the cooling water flows. This means that the intercooler acts as a multi tube-multi pass heat exchanger. The air here is cooled to the required temperature from where it is sent to the intercooler outlet. This completes the first stage of inter-cooling. This air is then sent to the second compressor for compression where the pressure increases to about 2kg/cm². It again passes through a second intercooler where the temperature is reduced to the required level. In this way another two stages of compression and a single stage of inter-cooling take place. After every stage of compression the temperature of the feed air increases. Therefore it is passed through an after-cooler after the fourth stage of compression. Thus this entire process of compression is termed isothermal as at the end of all the four stages of compression the temperature is maintained the same as the initial temperature.

23

AIR FILTERS A particulate air filter is a device composed of fibrous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air. A chemical air filter consists of an absorbent or catalyst for the removal of airborne molecular contaminants such as volatile organic compounds or ozone. Air filters are used in applications where air quality is important, notably in building ventilation systems and in engines. Some buildings, as well as aircraft and other man-made environments (e.g., satellites and space shuttles) use foam, pleated paper, or spun fiberglass filter elements. Another method, air ionizers, use fibers or elements with a static electric charge, which attract dust particles. The air intakes of internal combustion engines and compressors tend to use either paper, foam, or cotton filters. Oil bath filters have fallen out of favor. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluiddynamics of the air-compressor part of the Gas Turbines. Pleated paper filter elements are the nearly exclusive choice or automobile engine air cleaners, because they are efficient, easy to service, and cost-effective. The "paper" term is somewhat misleading, as the filter media are considerably different from papers used for writing or packaging, etc. There is a persistent belief amongst tuners, fomented by advertising for aftermarket non-paper replacement filters, that paper filters flow poorly and thus restrict engine performance. In fact, as long as a pleated-paper filter is sized appropriately for the airflow volumes encountered in a particular application, such filters present only trivial restriction to flow until the filter has become significantly clogged with dirt. Construction equipment engines also use this. Oil-wetted polyurethane foam elements are used in some aftermarket replacement automobile air filters. Foam was in the past widely used in air cleaners on small engines on lawnmowers and other power equipment, but automotive-type paper filter elements have largely supplanted oilwetted foam in these applications. Depending on the grade and thickness of foam employed, an oil-wetted foam filter element can offer minimal airflow restriction or very high dirt capacity, the latter property making foam filters a popular choice in off-road rallying and other motorsport applications where high levels of dust will be encountered.

24

Oil Bath Air Filters: An oil bath air cleaner consists of a sump containing a pool of oil, and an insert which is filled with fiber, mesh, foam, or another coarse filter media. When the cleaner is assembled, the mediacontaining body of the insert sits a short distance above the surface of the oil pool. The rim of the insert overlaps the rim of the sump. This arrangement forms a labyrinthine path through which the air must travel in a series of U-turns: up through the gap between the rims of the insert and the sump, down through the gap between the outer wall of the insert and the inner wall of the sump, and up through the filter media in the body of the insert. This U-turn takes the air at high velocity across the surface of the oil pool. Larger and heavier dust and dirt particles in the air cannot make the turn due to their inertia, so they fall into the oil and settle to the bottom of the base bowl. Lighter and smaller particles are trapped by the filtration media in the insert, which is wetted by oil droplets aspirated there into by normal airflow. Oil bath air cleaners were very widely used in automotive and small engine applications until the widespread industry adoption of the paper filter in the early 1960s. Such cleaners are still used in off-road equipment where very high levels of dust are encountered, for oil bath air cleaners can sequester a great deal of dirt relative to their overall size without loss of filtration efficiency or airflow. However, the liquid oil makes cleaning and servicing such air cleaners messy and inconvenient, they must be relatively large to avoid excessive restriction at high airflow rates, and they tend to increase exhaust emissions of unburned hydrocarbons due to oil aspiration when used on spark-ignition engines.

25

Suction Silencers

Compressor Silencers

AIR COMPRESSOR SUCTION SILENCER

RINL

SUCTION SILENCER : Suction silencers can be rectangular or cylindrical in construction. The circular silencer is made of concentric annular acoustic cylinder enclosed in a robust steel casing with transition cone or dished end at both ends with inlet and outlet nozzles. The air/ gas enters the silencer and passes through the annular space between the concentric annular acoustic cylinders where the sound energy is absorbed. The straight flow path through annular acoustic cylinder ensures minimum pressure drop. Either steel, galvanized steel or stainless steel is provided for internals.

Inlet guide vanes Engine downsizing is potentially one of the most effective strategies being explored to improve fuel economy. A main problem of downsizing using a turbocharger is the small range of stable functioning of the turbocharger centrifugal compressor at high boost pressures. Several stabilization techniques were studied to increase the compressor operating range without sacrificing the compressor efficiency. The paper presents an experimental study of one of these techniques, the axial variable inlet guide vanes (VIGV).

26

CLOSED INLET GUIDE VANE

OPEN INLET GUIDE VANE

The efficiency drop at particular points of functioning of low flow rate was explained by the non symmetric flow downstream the VIGVs at high vane setting angles Its purpose is to direct gasflow toward the expander wheel at the correct angle while also providing control of mass flow through the turbine.

27

28

BEARINGS The bearings in gas and steam turbines provide support and positioning for the rotating components. Radial support is generally provided by journal or roller bearings and axial positioning is provided by thrust bearings. The essential difference between ball bearings and roller bearings are that ball bearings have a lower carrying capacity and higher speeds while the roller bearings have higher load carrying capacity and lower speeds. Journal bearings may be either full round or split; the lining may be heavy as used in large sized bearings for heavy machinery or thin as used in precision insert type bearings in internal combustion engines. Most sleeve bearings are of the split type for convenience in servicing and replacement. Often in split bearings where the load is entirely downward, the top half of the bearing acts only as a cover to protect the bearing and to hold the oil fittings.

SEALS

A labyrinth seal is a type of mechanical seal that provides a tortuous path to help prevent leakage. An example of such a seal is sometimes found within an axle's bearing to help prevent the leakage of the oil lubricating the bearing. A labyrinth seal may be composed of many grooves that press tightly inside another axle, or inside a hole, so that the fluid has to pass through a long and difficult path to escape. Sometimes screw threads exist on the outer and inner portion. These interlock, to produce the long characteristic path which slows leakage. For labyrinth seals on a rotating shaft, a very small clearance must exist between the tips of the labyrinth threads and the running surface. Labyrinth seals on rotating shafts provide non-contact sealing action by controlling the passage of fluid through a variety of chambers by centrifugal motion, as well as by the formation of controlled fluid vortices. At higher speeds, centrifugal motion forces the liquid towards the outside and therefore away from any passages. Similarly, if the labyrinth chambers are correctly designed, any liquid that has escaped the main chamber becomes entrapped in a labyrinth chamber, where it is forced into a vortex-like motion. This acts to prevent its escape, and also acts to repel any other fluid. Because these labyrinth seals are non-contact, they do not wear out. 29

Many gas turbine engines, having high rotational speeds, use labyrinth seals due to their lack of friction and long life. Labyrinth seals are also found on pistons, which use them to store oil and seal against high pressure during compression and power strokes, as well as on other non-rotating shafts. In these applications, it is the long and difficult path and the formation of controlled fluid vortices plus some limited contact-sealing action that creates the seal.

o-ring

An O-ring, also known as a packing, or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, creating a sealat the interface. The O-ring may be used in static applications or in dynamic applications where there is relative motion between the parts and the O-ring. Dynamic examples include rotating pump shafts and hydraulic cylinder pistons. O-rings are one of the most common seals used in machine design because they are inexpensive, easy to make, reliable, and have simple mounting requirements. They can seal tens of megapascals (thousands of psi) of pressure.

30

Intercooler An intercooler is any mechanical device used to cool a fluid, including liquids or gases, between stages of a multi-stage heating process, typically a heat exchanger that removes waste heat in a gas compressor.[1] They are used in many applications, including air compressors, air conditioners, refrigerators, and gas turbines.

When air is compressed to 100 psi without heat Loss, the final temperature is about 485°F. The increase in temperature raises the pressure of the air under compression, thus necessitating an in-crease in work to compress the air. After the air is discharged into the receiver tank and lines, the temperature falls rapidly to near that of the surrounding atmosphere, thereby losing part of the energy generated during compression. The ideal compressor would compress the air at a constant temperature, but this is not possible. In multistage compressors, the work of compressing is divided between two or more stages, depending on the final discharge pressure required. An 31

INTERCOOLER is used between the stages to reduce the temperature of compression from each stage. Theoretically, the intercooler should be of sufficient capacity to reduce the temperature between stages to that of the lowpressure cylinder intake. Actually, intercooling has three purposes: to increase compressor efficiency, to prevent excessive temperatures within the compressor cylinders, and to condense out moisture from the air. Most intercoolers are either the shell and tube, air-towater heat

exchangers

or the air-cooled radiator-type

heat

exchangers.

3.Aftercoolers Moisture carried in air transmission lines is undesirable because it causes damage to airoperated tools and devices. AFTERCOOLERS are installed in compressor discharge lines to lower the air discharge temperature, thus condensing the moisture and allowing it to be removed. Also, the cooling effect allows the use of smaller discharge piping LUBRICATION SYSTEM Servo prime oils premium quality lubricants especially formulated to give outstanding performance and long life in modern steam, gas and hydraulic turbines. Servoprime oils are manufactured from selectively refined distilled base stocks and contain carefully chosen antioxidant, rust inhibitor and defoamant additives. Servoprime LP oils are special purpose low pour turbine oils. These oils have been tested for radiation stability and found suitable for use in turbines exposed to radiation encountered in nuclear power plants. PERFORMANCE STANDARDS Servoprime oils meet the following specification: • Turbine oil requirements of BHEL • BS 489/1983 • GE, USA specification GEK-27070 • IS: 1012 19871987 (Reaffirmed)

32

APPLICATION Servoprime oils are recommended for use in the lubrication system of steam, gas and hydraulic turbines operating under all service conditions. In addition, Servoprime oils give outstanding performance in hydraulic systems, circulating lubrication systems, enclosed bearings and other industrial machines in which long trouble free service of lubricant is required.Servoprime LP oils are meant for low temperature applications such as Rotoflow expanders and Turbo- compressors used in refrigerationapplications. PERFORMANCE BENEFITS • Provide excellent long term protection against rust and corrosion • Readily separate from water • Ensure long service life since they possess outstanding oxidation stability • Reduced tendency to foam • Able to release entrained air at a rapid rate COUPLING Lubricated gear-type couplings have been used in many turbomachinery installations. This type of coupling has some drawbacks which become obvious after years of operation. Such as: • wear occurs between the gear teeth which increases the operating clearances of the coupling. • any malfunction or incorrect maintenance of the lubrica- tion system can lead to a rapid deterioration of the toothed joint. • the high rotational velocity of the coupling tends to make it act somewhat like a centrifuge causing wear particles and dirt to collect inside the coupling. This effect is ampli- fied if the oil spray system is not working properly. The effects of the above problems can lead to: • Increasing levels of vibration amplitude; • Seizing of the coupling increasing the effects of residual misalignment on the turbomachinery; • Higher maitenance expenditures For these reasons maintenance of couplings on a routine basis is needed. On modern compressors dry flexible element couplings are utilized which overcome the problems listed for the lubricated couplings. The dry flexible element is maintenance free since there are no moving parts. There are different types of flexible element coupling available to fit most applications. The flexible element coupling can be retro-fit without modifying the turbo machinery rotor and the coupling guard arrangement. In most cases, the replacement coupling can be selected to have similar stiffness as the original gear coupling in order to avoid changes to 33

the rotor dynamic behaviour of the machine. Dry couplings are mainly divided into two categories: diaphragm couplings and multiple membrane couplings. DIAPHRAGM COUPLINGS : The torque is transmitted by the coupling hub bolted to one/two diaphragms welded to the spacer. The main advantage of this type of coupling is the simple configuration and therefore the limited problems in balancing.

34

35

WORKING OF CHILLER The basic components used in a chiller are:1. Evaporator 2. Compressor 3. Condenser 4. Expansion valve T he main principle of the refrigeration system is to absorb heat from the given body or system and maintain it below the atmospheric temperature. The refrigerants used in the refrigeration system are mostly liquids. In this case, the refrigerant used is R134a. The refrigerant is allowed to flow in a closed system-shells or tubes. In the following case water is to be cooled. The water at a certain temperature is sent into the cylinder where the refrigerant flows through the tubes. The refrigerant absorbs the heat from the water and as a result the phase change of the refrigerant takes place. This is because the boiling point of the refrigerant used is quite low. The water which is cooled is further cooled by sending it into the nitrogen --water tower, where the nitrogen absorbs the heat from the water. As result the water attains a very low temperature when compared to the inlet temperature. This water is sent into the air-water tower to reduce the temperature of air which is compressed and sent from the compressor. The water absorbs the heat from the air and is sent into drier. The warm water is sent into the chiller to cool it and this cycle is repeated again.

AIR-WATER TOWER The air water tower is the starting end of the air-separation plant. It consists of a long coloumn in which air is passed from the lower end and water is passed from the lower end of the tower. The air being hot rises upward and the water being cooler flows downwards without any effort. As a result, the water absorbs heat energy from the hot air thereby resulting in cooling action on 36

the air. However during this process some amount of moisture from the water also mixes into air and therefore air needs to be freed from moisture in the following section. Thus the main aim of the air-water tower is to cool the compressed air from the compressor which is about 45 degrees Celsius to about 10 degrees Celsius.

NITROGEN-WATER TOWER

The cooling water required for the air-water tower comes from this tower. In this tower, water from the pump house is first sent here in order to minimize the amount of heat required for cooling it in order to cool the air in the air-water tower. Waste Nitrogen gas which is already cooled to a temperature of about 18 degrees Celsius. This cooled water is now sent to a chiller where the water is further cooled before it is sent to the air-water tower. In some cases, both nitrogen gas and the water may be of nearly equal temperature. In such cases, the nitrogen gas which is unsaturated absorbs moisture from the water and in turn cools it. This process is called evaporative cooling.

AIR DRIERS These driers play a pivotal role in the purification of air from the compressor outlet. They consist of two levels-namely the higher and the lower levels. The lower level consists of activated alumina while the higher level consists of molecular sieves. The level consisting of activated alumina is used to purify the air of moisture while the higher level is used to cleanse the air of any unabsorbed hydrocarbons and carbon-di-oxide.

Air Filters:- From the air driers, the air is passed into the air filters where the dry air emerging from the driers is filtered so as to remove any chemicals which might have seeped into the air from the molecular sieves or parts of activated alumina. 37

From the air filters, this air is passed on to the heat exchanger. Cleaning is generally done in the air filters to prevent any damage due to chemical action inside the heat exchanger. Heat exchanger:- The heat exchanger consists of two sections. The second section is used generally when one is under repair or is being recharged. Here the air is divided into six sections. Here the air which is initially at a temperature of 10 degrees Celsius is brought down to a temperature of about -170 degrees Celsius. Generally a counterflow heat exchanger is employed as it has a higher efficiency as compared to the other types of heat exchangers. A part of this air is sent to an expansion turbine where the pressure reduces from 6 bar to 0.6 bar. The remaining air in the heat exchanger is sent directly to the medium pressure chamber in the distillation column. The air leaving the expansion turbine is sent to the low pressure chamber in the distillation coloumn. Thus the medium pressure column consists of air at a pressure of 6 bar while the low pressure column consists of air at a pressure of 0.6 bar.

Also a heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall to prevent mixing or they may be in direct contact.[1] They are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, natural gas processing, and sewage treatment. The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air.

Shell and tube heat exchangers consist of a series of tubes. One set of these tubes contains the fluid that must be either heated or cooled. The second fluid runs over the tubes that are being heated or cooled so that it can either provide the heat or absorb the heat required. A set of tubes is called the tube bundle and can be made up of several types of tubes: plain, longitudinally finned, etc. Shell and tube heat exchangers are typically used for high-pressure applications (with

38

pressures greater than 30 bar and temperatures greater than 260 °C). This is because the shell and tube heat exchangers are robust due to their shape.

Distillation coloumn:- This is the main part of the air separation plant. It consists of three chambers. 1. Medium pressure chamber 2. Low pressure chamber 3. Pure Nitrogen chamber

Medium pressure chamber:- In this chamber air at a pressure of 6 bar is passed up through the bottom of the chamber where it meets cooling water. Thus a rich mixture of about 40 percent oxygen is formed. This gets precipitated at the bottom of the chamber. Low pressure chamber:- This chamber consists of air at a pressure of about 0.6 bar. It also consists of a heat exchanger surrounded by liquid oxygen. Here the components of air namely argon,oxygen and nitrogen separate out. Argon and oxygen form a liquid mixture while nitrogen separates out as a gas. Even though the temperature here is not maintained at the respective boiling temperatures of the gases, these temparatures are obtained directly due to the very low pressure maintained here. Pure nitrogen chamber:- Nitrogen being the more volatile gas of all the three rises upward and in collected in the pure nitrogen chamber. In the medium pressure chamber mixtures of oxygen, argon and moisture are collected at different levels in different proportions. These are then sent to the pure nitrogen chamber where nitrogen which is warmer than the other two removes the moisture from their mixture. This cycle is repeated until two different mixtures are obtained-one with oxygen content of 90 percent and the other with argon content of about 95 percent.

39

Distillation tower

Chiller A chiller is a machine that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. This liquid can then be circulated through a heat exchanger to cool air or equipment as required. As a necessary byproduct, refrigeration creates waste heat that must be exhausted to ambient or, for greater efficiency, recovered for heating purposes. Concerns in design and selection of chillers include performance, efficiency, maintenance, and product life cycle environmental impact. In air conditioning systems, chilled water is typically distributed to heat exchangers, or coils, in air handling units or other types of terminal devices which cool the air in their respective space(s), and then the water is re-circulated back to the chiller to be cooled again. These cooling coils transfer sensible heat and latent heat from the air to the chilled water, thus cooling and usually dehumidifying the air stream. A typical chiller for air conditioning applications is rated between 15 and 1500 tons (180,000 to 18,000,000 BTU/h or 53 to 5,300 kW) in cooling capacity, and at least one manufacturer can produce chillers capable of up to 6,000 tons of

40

cooling. Chilled water temperatures can range from 35 to 45 °F (2 to 7 °C), depending upon application requirements. In industrial application, chilled water or other liquid from the chiller is pumped through process or laboratory equipment. Industrial chillers are used for controlled cooling of products, mechanisms and factory machinery in a wide range of industries. They are often used in the plastic industry in injection and blow molding, metal working cutting oils, welding equipment, die-casting and machine tooling, chemical processing, pharmaceutical formulation, food and beverage processing, paper and cement processing, vacuum systems, X-ray diffraction, power supplies and power generation stations, analytical equipment, semiconductors, compressed air and gas cooling. They are also used to cool high-heat specialized items such as MRI machines and lasers, and in hospitals, hotels and campuses. Chillers for industrial applications can be centralized, where a single chiller serves multiple cooling needs, or decentralized where each application or machine has its own chiller. Each approach has its advantages. It is also possible to have a combination of both centralized and decentralized chillers, especially if the cooling requirements are the same for some applications or points of use, but not all. Decentralized chillers are usually small in size and cooling capacity, usually from 0.2 tons to 10 tons. Centralized chillers generally have capacities ranging from ten tons to hundreds or thousands of tons. Chilled water is used to cool and dehumidify air in mid- to large-size commercial, industrial, and institutional (CII) facilities. Water chillers can be water-cooled, air-cooled, or evaporatively cooled. Water-cooled chillers incorporate the use of cooling towers which improve the chillers' thermodynamic effectiveness as compared to air-cooled chillers. This is due to heat rejection at or near the air's wet-bulb temperature rather than the higher, sometimes much higher, dry-bulb temperature. Evaporatively cooled chillers offer higher efficiencies than air-cooled chillers but lower than water-cooled chillers. Water-cooled chillers are typically intended for indoor installation and operation, and are cooled by a separate condenser water loop and connected to outdoor cooling towers to expel heat to the atmosphere.

41

Air-cooled and evaporatively cooled chillers are intended for outdoor installation and operation. Air-cooled machines are directly cooled by ambient air being mechanically circulated directly through the machine's condenser coil to expel heat to the atmosphere. Evaporatively cooled machines are similar, except they implement a mist of water over the condenser coil to aid in condenser cooling, making the machine more efficient than a traditional air-cooled machine. No remote cooling tower is typically required with either of these types of packaged air-cooled or evaporative cooled chillers. Where available, cold water readily available in nearby water bodies might be used directly for cooling, place or supplement cooling towers. The Deep Lake Water Cooling System in Toronto, Canada, is an example. It uses cold lake water to cool the chillers, which in turn are used to cool city buildings via a district cooling system. The return water is used to warm the city's drinking water supply, which is desirable in this cold climate. Whenever a chiller's heat rejection can be used for a productive purpose, in addition to the cooling function, very high thermal effectiveness is possible.

Simple condenser and evaporator

42

43

44

CONCLUSION Thus in this project, we have seen the actual operation of an air separation plant, and the working of the machinery involved in the separation of air. We have also discussed the various components of the air separation plant in detail using diagrams and also the functioning of heat exchangers, turbines and a screw chiller. The above points discussed in this project give us a clear idea about the functioning of an air separation plant including heat exchangers and turbines.

45

46