A Laboratory Manual for Basic Mechanical Engineering, Study Guides, Projects, Research of Mechanical Engineering

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A Laboratory Manual for

BASIC MECHANICAL ENGINEERING

(BE01R00081)

B.E. Semester 1 / 2

(All Branches)

Government Engineering College,

Patan, Gujarat

VISION & MISSION

INSTITUTE

VISION

To prepare Human Resource with value based competency for

technical advancements and growth of society

MISSION

Deliver technical programs and services to cater to the current needs of society

and industry, and to contribute in sustainable growth of society

DEPARTMENT

VISION

To create a center of excellence for imparting education in mechanical engineering

field to meet the current and future challenges of technological and sustainable

development.

MISSION

1. To build an enabling environment for excellent teaching, learning and research in

order to produce entrepreneurs and innovators in the field of Mechanical

Engineering for sustainable improvement.

2. To impart adequate fundamental knowledge, technical and soft skills to students.

3. To develop Mechanical Engineering solutions for the problems of industry and

society.

GUJARAT TECHNOLOGICAL UNIVERSITY

Program Name: Engineering Level: UG Branch:All Course/ Subject Code: BE01R Course/SubjectName: Basic Mechanical Engineering w.e.f.Academic Year: 2025 - 26 Semester: 1 stYear Categoryof theCourse: ESC Prerequisite: Nil Rationale: Knowledge^ of^ basic^ principles^ of^ Mechanical^ Engineering^ is^ required invariousfields of engineering. Course Outcome: AfterCompletionoftheCourse,Studentwillable to: No Course Outcomes RBT^ level 1 Explain the various sources of energy and basic terminology of M engineering Understand 2 Make calculations for commonly used working fluids i.e. Ideal gases and steam Apply 3 Make use of various heat engine cycles and explain construction and working of IC engines Apply 4 Explain working and applications of steam boilers and various energy conversion systems Understand 5 Explain various power transmission elements, construction and working of various clutches; couplings and brakes, and properties of various engineering materials with their applications Understand

Suggested Course Practical List:

1. To understand construction and working of various types of boilers.
2. To understand construction and working of different boiler mountings and accessories.
3. To understand construction features of two/four stoke petrol/diesel engines
4. To determine brake thermal efficiency of an I.C. Engine.
5. To understand construction and working of different types of air compressors.
6. To demonstrate vapor compression refrigeration cycle of domestic refrigerator OR window air conditioner OR split air conditioner.
7. To understand construction, working and application of clutches, coupling sand brakes
8. To understand different arrangements and application of various power transmission drives List of Laboratory/Learning Resources Required: Models of Cochran, Lancashire and Babcock and Wilcox boilers, models of various mountings and accessories, Models of various types of IC engines, Single cylinder two stroke /four stroke petrol/ diesel engine, models of pumps

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GUJARATTECHNOLOGICALUNIVERSITY

ProgramName:Engineering Level: UG Branch:All Course/ Subject Code: BE01R Course/SubjectName:BasicMechanicalEngineering

Government Engineering College, Patan

DEPARTMENT OF MECHANICAL ENGINEERING

Basic Mechanical Engineering - BE01R INDEX Sr. No. Experiment Page Number Dates Sign Grades/ marks

Start End Start

(^1) To understand construction & working of various types of Boilers. 2 To understand construction and working of different boiler mountings & accessories. 3 To understand construction features of two/four stoke petrol/diesel engines. 4 To determine brake thermal efficiency of an I. C. ENGINE. 5 To understand construction and working of different types of air compressors. 6 To demonstrate vapour^ compression refrigeration cycle of a domestic refrigerator OR a window air conditioner OR a split air conditioner 7 To study about construction, working and applications of different types of coupling, clutch and brake. 8 To understand different arrangements and application of various power transmission drives. 9 To understand construction and working of combined separating and throttling calorimeter. 10 To understand construction and working of different types of pumps.

Practical No. 1 AIM: To understand construction & working of various types of Boilers. OBJECTIVES:

1. To understand the working of steam boilers.
2. To differentiate between different types of boilers.

OUTCOMES: To understand and appreciate significance of boilers in different fields of Engineering. THEORY: A boiler is a closed vessel made of steel in which heat is transferred to water by combustion of fuel which vaporizes the water and is converted into steam at desired pressure and temperature. According to Indian boiler regulation (IBR), a boiler is a closed pressure vessel with capacity exceeding 22.75 liters used for generating steam under pressure. The steam produced by the boiler is used for power generation, process heating and space heating. Steam is generated at higher pressure when steam is used for power generation whereas it is generated at lower pressure when it is used for process heating and space heating. **BASIC COMPONENTS OF A BOILER

1. Boiler shell:** It consists of one or more steel plates bent into cylindrical form and riveted or welded together. Various mountings are fitted on it. 2. Grate: It is the platform on which fuel is burnt. It consists of cast iron bars with spacing between them so that air for combustion can pass through them. Ash falls into ash pit constructed below the grate. 3. Furnace: It is a chamber above the grate and below the boiler shell where the fuel is burnt to produce hot gases. It is also called fire box. 4. Setting: It is made of brick. It provides support to the boiler and forms the wall of the furnace and combustion chamber. Its function is to confine heat to the boiler and forms passage for gases. 5. Fire hole: It is the opening from which coal is added to the furnace. 6. Ash pit: It is the area below the grate in which ash of burnt coal is collected. 7. Smoke box: The hot exhaust gases after giving the heat to the water, enter a chamber called smoke box. The gases from smoke box are released to atmosphere through the chimney. It is provided with door for cleaning the fire tubes and the smoke box. 8. Manhole: It is a hole provided in the boiler shell so that a workman can go inside the boiler for inspection, cleaning and maintenance. It is usually oval in shape and a door is provided to close it. 9. Hand hole: It is a hole provided in the boiler shell to give easy access for the purpose of cleaning the water tubes or some internal parts of the boiler. It is also provided with cover. 10. Mud box: It collects all the impurities present in water. It is provided at the lowest part of the boiler. Mud and other impurities are removed from mud box with the help of blow off cock. 11. Anti-priming pipe (Steam collecting pipe): The function of anti-priming pipe is to separate water particles from wet steam and collect dry steam from boiler. 12. Boiler stays: Its function is to prevent bulging of the plates due to pressure of the steam. Various types of stays are (a) direct stays, (b) diagonal or gusset stays and (c) girder stays. 13. Heating surface: Surface of the boiler which is exposed to hot gases on one side and to water on the other side is known as heating surface. CLASSIFICATION OF BOILERS Boilers are mainly classified as follows: 1. According to relative position of hot gases and water (a) Fire tube boiler: Hot flue gases pass through the boiler tubes and water surrounds these tubes. Heat is conducted through the walls of the tubes from the hot gases to the surrounding water. Example: Cochran, Lancashire, Locomotive boiler etc.

6. According to use or application (a) Stationary boilers: These boilers are stationary and cannot be moved from one place to another place. e.g. Boilers used for power generation and industrial boilers used for process heating. (b) Mobile boilers: These boilers are portable and can be moved from one place to another place. e.g. Locomotive boilers. 7. According to number of tubes (a) Single tube boiler: In this type of boiler, there is only one fire or water tube. e.g. Simple vertical boiler, Cornish boiler. (b) Multi-tube boiler: In this type of boiler, there are two or more number of fire or water tubes. e.g. Lancashire, Babcock and Wilcox boiler. 8. According to nature of draught used (a) Natural draught boiler: Chimney is used to produce the draught. (b) Forced draught boiler: Fan is used to produce the draught. (c) Steam jet draught boiler: Steam of the boiler is used to produce the draught. COCHRAN BOILER: Fig. 1.3 Cochran Boiler It is a vertical, multi tabular fire tube boiler used for small capacity steam generation. It is made in different sizes of evaporative capacities ranging from 150-3000 kg/hr and working pressure up to 20 bar. It is modification of simple vertical boilers where heating surface is increased by increasing the number of fire tubes.

Construction (1) It consists of a cylindrical shell with its crown having hemispherical shape as shown in Fig. 1.3. The furnace is also hemispherical in shape. The hemispherical crown of the boiler shell gives maximum space and strength to withstand the pressure of steam inside the boiler. (2) The hemispherical shape of the furnace can withstand intense heat and permits maximum absorption of radiant heat. The grate is placed at the bottom of the furnace and the ash pit is located below the grate. (3) The coal is fed to the grate through the fire door and ash formed is collected in the ash pit located just below the grate. The furnace is connected to the combustion chamber by a flue pipe. The back of the combustion chamber is lined with fire bricks. (4) About 160 to 170 fire tubes (generally 6.25 cm in diameter) are placed horizontally and these connect the combustion chamber and the smoke box. (5) A manhole is provided at the top of the shell for cleaning. Number of hand holes are also provided around the outer shell for cleaning purpose. Smoke box is provided with doors for cleaning of the interior of fire tubes. (6) Various mountings like pressure gauge, water level indicator, safety valve, fusible plug, blow off cock, steam stop valve and feed check valve are provided for proper functioning of the boiler. Working (1) The water is supplied to the boiler through the feed check valve. The combustion of fuel and air produces the hot gases. These gases enter through the flue pipe into the combustion chamber. (2) The hot gases then enter horizontal fire tubes and transfer large portion of heat to the water by convection. (3) The hot gases coming out of the fire tubes enter the smoke box and finally they are discharged to the atmosphere through chimney. The ash is collected in the ash pit below the grate. (4) After passing through anti-priming pipe, steam is collected from top of the shell by operating the steam stop valve. Advantages

1. It is compact, requires minimum floor area.
2. Initial cost of the boiler is low.
3. Any type of fuel can be used with this boiler.
4. All fire tubes are of same size, so one tube in spare is sufficient for replacement. Disadvantages
5. For small size boiler, efficiency is low.
6. Steam space is less, due to which water particles along with steam may enter the steam pipe. Such steam is not desirable for power production.
7. Interiors are not readily accessible for cleaning, maintenance and repair due to vertical design.
8. It is difficult to maintain steady steam pressure as the water storing capacity is small. Specifications Shell diameter = 2.75 m Height = 5.75 m Working pressure = 6.5 bar Heating surface area 120 m Steam capacity = 3500 kg/hr (Max. = 4000 kg/hr) Efficiency = 70 to 75 %

gases. (6) This regulates the combustion rate as well as steam generation rate. These dampers are operated by chains passing over a pulley at the front of the boiler. (7) The boiler is fitted with usual mounting and accessories. The top view of the boiler shell has anti- priming pipe, safety valve, low water and high steam alarm and man hole. (8) Pressure gauge and water level indicator are provided in front of the boiler and blow off cock at the bottom of the shell. Fusible plug is mounted on top of each main flue tube just above the grate. Working (1) Fuel is burnt on the fire grate and hot flue gases pass through the two internal fire tubes and reaches the back end of the boiler where they dip and enter into the bottom flue passage (Fig.1.4 a) ‘A’. (2) After coming out from passage ‘A’ at the front of the boiler, the hot flue gases then divide into two and pass through the two side flues B and C (Fig.1.4a). (3) Then they move along the two side flues and then are discharged through the chimney (Fig.1.4.c). (4) As the heat is transferred by two internal flue tubes, bottom flue and side flue, heat of flue gases is utilized effectively. Advantages

1. Its heating surface area per unit volume of the boiler is considerably large.
2. It is easy to inspect and clean.
3. Less operating and maintenance cost.
4. Load fluctuations can be easily met by this boiler due to large reserve capacity of water.
5. By incorporating economiser and super heater, overall efficiency of the boiler can be increased up to 80 - 85 %. Disadvantages
6. Boiler has considerable brickwork which occupies large floor area.
7. Furnace is inside the flue tubes which reduces the surface area available for burning of coal.
8. Maximum pressure is limited to 16 bar because of huge size of shell and brickwork setting.
9. Rate of generation of steam is slow due to large reservoir capacity of the boiler. Specifications Shell diameter = 2 to 3 m Length of the shell = 7 TO 9 m Working pressure = 16 bar Steam capacity = 8000-9000 kg/hr Efficiency = 50 to 70 %

BABCOCK ANDWILCOX BOILER

It is a horizontal, stationary, multi-tubular, externally fired, natural circulation type boiler. This boiler produces steam at maximum pressure up to 40 bar with maximum evaporating capacity of 40,000 kg/hr. Its efficiency is 60 to 80 %. It is suitable for power generation in small size thermal power plant and for process heating. Fig. 1.5 Babcock and Wilcox boiler Construction (1) It consists of three main parts: boiler shell, water tubes and furnace. Boiler shell, also known as water and steam drum is made of high-quality steel and lies in horizontal position. (2) Water tubes are placed below the shell. Shell is connected by short tube with the uptake header or riser and by longer tube with down take header as shown in Fig. 1.5. (3) Water level is kept slightly above the centre line of the drum. Water tubes of around 10 cm in diameter are connected to the uptake and down take header and kept inclined at an angle of 15° to the horizontal to promote natural circulation of water. (4) The headers are provided with hand holes in the front of the tubes and are covered with caps. The furnace is arranged below the uptake header. A super heater is placed between the drum and water tubes. Baffle plates are provided around the water tubes to improve circulation of hot gases. (5) A mud box is fitted to the down header. The impurities in water and mud are collected in the mud box and are blown off periodically by blow off valve. To access the interior of the boiler it is provided with doors. (6) This is necessary for cleaning the outer surface of the water tubes and to remove soot from the surface. The damper is placed at the inlet of the chimney to regulate the draught. (7) Various mountings like steam pressure gauge, water level indicator, feed check valve, safety valve etc. are provided for proper functioning of the boiler. Working (1) Water is fed to the drum through the feed check valve. Water flows by gravity and fills the inclined tubes and the headers. Thereafter water is collected in the drum. Coal is fed to the grate through the fire door. Combustion of fuel produces flue gases. (2) The hot gases rise upward and pass across the left side portion of the water tubes. The baffles deflect the flue gases due to which flue gases travel in zigzag manner over the water tubes and along the super heater.

Practical No. 2 AIM: To understand construction and working of different boiler mountings & accessories THEORY : Different fittings and devices necessary for operation and safety of a boiler are known as boiler mountings. They are mounted on the boiler and are compulsory as per IBR for safe operation of the boiler. According to Indian boiler regulation (IBR) following mountings should be fitted to the boiler. Sr. No. Name of mounting Quantity (in number) 1 Safety valve 2 2 Water level indicator 2 3 Pressure gauge 1 4 Steam stop valve 1 5 Feed check valve 1 6 High steam and low water safety valve

7 Blow off cock 1 8 Fusible plug 1 9 Manhole 1 10 Mud hole 1 Pressure Gauge Function: It measures and indicates the steam pressure in the boiler. Location: It is mounted in front and top of the boiler shell so that it is easily visible to the operator. Fig. 2.1 Pressure gauge Construction (1) Commonly used pressure gauge known as Bourdon pressure gauge is shown in Fig. 2.1. It consists of elastic metallic tube made from high quality phosphor bronze. It is of elliptical cross-section and bend in the form of circular arc. (2) One end of the tube is closed by plug and other end is connected to steam space of the boiler.

(3) The pressure gauge is connected to the steam space of the boiler through U-tube siphon. Siphon is filled with water which prevents the hot steam from entering the Bourdon tube and keeps the gauge comparatively cool. (4) The closed end of the tube is attached by links to a toothed quadrant which in turn meshes with a small pinion fitted on the central spindle. (5) A pointer as shown in Fig. 2.1 is attached to the spindle on a dial gauge. The dial gauge is usually constructed to indicate up to double the maximum working pressure. Working (1) The steam pressure forces the water from the siphon tube into elliptical tube and this causes the tube to become circular in cross-section and straightens the tube, causing the tube at the end to move outwards. (2) This outward movement is magnified and transmitted by link, toothed quadrant and pinion causing the pointer to move and show pressure on the graduated dial. (3) The movement of the free end of the elliptical tube is proportional to the difference between external and internal pressure on the tube. (4) Since the outside pressure is atmospheric, pressure gauge measures steam pressure minus atmospheric pressure i.e. gauge pressure. Water Level Indicator Function : It indicates water level inside the boiler to the observer and warns the operator to take corrective action if the level of water falls below the minimum level. Location : It is located in front of the boiler in such a position so that it is easily seen by boiler operator. Fig. 2.2 Water level indicator Construction (1) Fig. 2.2 shows schematic diagram of water level indicator. Two water level indicator are provided on all the boilers. (2) The water level indicator is attached to front plate of the boiler. It consists of a metal tube and a glass tube with marking whose end pass through stuffing box. Glass tube is made of toughened glass so that it can withstand the boiler pressure. (3) The upper and lower end of these tubes are connected to two hollow gun metal casting. Upper casting has steam cock and lower casting has water cock.

The lower end of the spindle is connected to the valve and upper end is connected to the hand wheel through a gland. The gland prevents leakage of steam. Working (1) The spindle is rotated by means of a hand wheel. The rotation of the spindle causes the valve to move up and down. (2) When the hand wheel is rotated anticlockwise, the valve lifts up and steam is allowed to pass through the clearance between valve and its seat. (3) The amount of steam passing to the steam pipe is controlled by the valve lift. When hand wheel is rotated clockwise, it closes the steam passage. (4) When the valve touches the valve seat, flow of steam completely stops. Feed Check Valve Function : Its function is to supply high pressure feed water to the boiler and to prevent back flow of water from the boiler when the feed pump is not working or when feed pump pressure is less than the boiler pressure. Location : It is fitted to the boiler shell slightly below the normal water working level of the boiler. Construction (1) It consists of non-return valve, water inlet pipe, water outlet pipe, spindle, gland, and hand wheel as shown in Fig. 2.4. (2) Check valve also known as non-return valve automatically moves up and down on its seat. It operates automatically due to pressure difference of water and allows water to flow in one direction only i.e. from feed pump to boiler. (3) Valve can be raised or lowered on the gun metal sheet with the help of spindle and hand wheel. (4) The inlet pipe is connected with delivery pipe of feed pump while the outlet pipe is connected to the boiler. Fig. 2.4 Feed check valve Working (1) When the feed pump is operating, it generates pressure which is higher than the boiler pressure. (2) This causes the non-return valve to open and allows flow of water in the boiler. The lift of the valve is controlled by moving the spindle up and down with the hand wheel. Thus the flow of water to the boiler can be controlled. (3) In case of pump failure or when the pump is not operating, boiler pressure becomes more than the pressure of feed water. (4) This causes the non-return valve to rest on its seat closing the water passage and stops the return flow of water from boiler to delivery pipe of water.

Blow off Cock Fig. 2.5 Blow off cock Function It performs two functions:

1. To discharge mud, sediments and heavy deposits periodically which settle down at the bottom of the boiler while the boiler is in operation.
2. To empty the boiler for cleaning, inspection and repair. Location: It is fitted to the lowest part of the water space either directly on the boiler shell or to a pipe connected with the boiler. Construction (1) It consists of a conical gun metal plug fitted accurately in a conical casing. The plug has a slot in it. The casing consists of two flanges, one is connected to the boiler shell and other one to pipe which takes discharge out of the boiler. (2) Casing is packed with asbestos packing in grooves around top and bottom of the plug. (3) The shank of the plug passes through stuffing box and gland which are provided to avoid leakage of water. (4) Yoke provided at top of shank keeps the plug in its position. (5) Two vertical slots are provided at the top for fixing the box spanner. The plug shank can be rotated by means of box spanner. Working (1) When the plug is rotated, the slot in the plug is brought in line with the passage of the casing. This causes the water to flow out of the boiler. (2) The flow of water through the boiler can be stopped by rotating the plug in such a way that solid portion of the plug comes in line with the passage of the casing as shown in Fig. 2.5. Fusible Plug Function The function of the fusible plug is to put off the fire in the furnace of a boiler when the water level in the boiler falls below the safe minimum level thereby preventing an explosion which may take place due to overheating of tubes and shell.