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Lecture Notes of Industerial Equipments

Barhm Abdullah Mohamad
Erbil Polytechnic University
1.1 Pumps
1.2 Type of pumps
1.2.1 Positive displacement Pumps
1.2.2 The components of rotary pumps
3.2.4 The disadvantage of electrical engine or motors
3.3 Electrical generator
3.3.1 The difference between electrical m...

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Lecture Notes of Industerial Equipments

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Fundamentals of Industrial Equipment provides students with a thorough introduction to the diagnosis, repair, and maintenance of industrial equipment. With comprehensive, up to date coverage of the latest technology in the field, it addresses the equipment used in construction, oil and gas industry, and mining industries.
The primary purpose of mechanical fitting is to transmit forces across parts of a system with as little loss as possible and with minimum of wear. The better the fits the more efficient the system. The primary units required to be fitted are gears, clutches, couplings, belt and chain drives and bearings. To produce these forces there are four main units: pumps, compressors, engines and electrical motors. The major aspects of these devices will be discussed in relation to proper maintenance procedures, fault finding methods and fitting techniques. The information given can be applied in almost every instance of maintenance fitting and will provide a springboard for acquiring more advanced techniques and knowledge in the areas outlined. Where specific areas have not been covered the methods and information given can be interpolated to fit the circumstances at the time.

Fundamentals of Industrial Equipment provides students with a thorough introduction to the diagnosis, repair, and maintenance of industrial equipment. With comprehensive, up to date coverage of the latest technology in the field, it addresses the equipment used in construction, oil and gas industry, and mining industries.
The primary purpose of mechanical fitting is to transmit forces across parts of a system with as little loss as possible and with minimum of wear. The better the fits the more efficient the system. The primary units required to be fitted are gears, clutches, couplings, belt and chain drives and bearings. To produce these forces there are four main units: pumps, compressors, engines and electrical motors. The major aspects of these devices will be discussed in relation to proper maintenance procedures, fault finding methods and fitting techniques. The information given can be applied in almost every instance of maintenance fitting and will provide a springboard for acquiring more advanced techniques and knowledge in the areas outlined. Where specific areas have not been covered the methods and information given can be interpolated to fit the circumstances at the time.


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Lecture Notes of Industerial Equipments

  1. 1. 1 INDUSTRIAL EQUIPMENTS Barhm Abdullah Mohamad Erbil Polytechnic University LinkedIn: Google Scholar: ResearchGate: YouTube channel:
  2. 2. 2 Contents Overview 1.1 Pumps 1.2 Type of pumps 1.2.1 Positive displacement Pumps 1.2.2 The components of rotary pumps 1.2.3 Advantage of positive displacement pumps 1.2.4 Disadvantage of positive displacement pumps 1.3 Dynamic pumps 1.3.1 Centrifugal pump components 1.3.2 Types of casings 1.3.3 Advantage of centrifugal pumps 1.3.4 Disadvantage of centrifugal pumps 2.1 Compressors 2.1.1 Standard Units and Conditions 2.2 Positive displacement compressors 2.2.1 Advantage of positive displacement compressors 2.2.2 Disadvantage of positive displacement compressors 2.3 Dynamic compressor 2.3.1 Centrifugal compressors systems 2.3.2 Axial compressors 2.3.3 Advantage of dynamic compressors 2.3.4 Disadvantage of dynamic compressors 2.4 Stalling phenomenon 2.5 Compressors components 2.5.1 Receiver tanks or the air receivers 2.5.2 Air dryers 2.5.3 Filters 2.5.4 Piping distribution system 3.1 Engines 3.2 Electrical engines 3.2.1 The components of electrical motors 3.2.2 Uses of electrical motors 3.2.3 The advantage of electrical engine or motor
  3. 3. 3 3.2.4 The disadvantage of electrical engine or motors 3.3 Electrical generator 3.3.1 The difference between electrical motors and electrical generators 3.4 External combustion engine 3.4.1 Steam engines 3.5 Internal combustion engine 3.5.1 Type of engine according to design 3.5.2 Type of engine according to fuel combustion 3.5.3 Diesel engine 3.5.4 Engine parts 3.5.5 Engine parameters 3.5.6 The difference between SI engine and CI engine 4.1 Crude oil storages 4.2 Type of crude oil storages 4.3 Crude oil storage components 5.1 Reactors 5.2 Type of reactors according to phase 5.3 Type of reactor according to design 5.4 Catalyst 5.5 Reactor design 6.1 Heating, ventilation and air conditioning [HVAC] 6.2 Refrigeration cycle 6.2.1 Ideal vapor-compression refrigeration cycle process description 7.1 Upstream process sections in oil and gas location 7.1.1 Wellheads 7.1.2 Manifolds 7.1.3 Separation 7.1.4 Metering, storage and export 7.1.5 Utility systems
  4. 4. 4 Overview Fundamentals of Industrial Equipment provides students with a thorough introduction to the diagnosis, repair, and maintenance of industrial equipment. With comprehensive, up-to-date coverage of the latest technology in the field, it addresses the equipment used in construction, oil and gas industry, and mining industries. The primary purpose of mechanical fitting is to transmit forces across parts of a system with as little loss as possible and with minimum of wear. The better the fits the more efficient the system. The primary units required to be fitted are gears, clutches, couplings, belt and chain drives and bearings. To produce these forces there are four main units: pumps, compressors, engines and electrical motors. The major aspects of these devices will be discussed in relation to proper maintenance procedures, fault-finding methods and fitting techniques. The information given can be applied in almost every instance of maintenance fitting and will provide a springboard for acquiring more advanced techniques and knowledge in the areas outlined. Where specific areas have not been covered the methods and information given can be interpolated to fit the circumstances at the time.
  5. 5. 5 Chapter 1 1.1 Pumps A mechanical device using suction or pressure to raise or move liquids and compress gases. Pumps operate by some mechanism (typically reciprocating or centrifugal) and consume energy to perform mechanical work by moving the fluid. Pumps operate via many energy sources, including manual operation, electricity, engines, or wind power, come in many sizes, from microscopic for use in medical applications to large industrial pumps. Mechanical pumps serve in a wide range of applications such as pumping water from wells, in the car industry for water-cooling and fuel injection, in the energy industry for pumping oil and natural gas or for operating cooling towers. In the medical industry, pumps are used for biochemical processes in developing and manufacturing medicine. 1.2 Type of pumps Mechanical pumps according to position may be submerged in the fluid they are pumping or be placed external to the fluid. Pumps can be classified according to the operating principle:
  6. 6. 6 1.2.1 Positive displacement pumps Positive displacement pumps are distinguished by the way they operate when liquid is taken from one end and positively discharged at the other end for every revolution. In all positive displacement type pumps, a fixed quantity of liquid is pumped after each revolution. So, if the delivery pipe is blocked, the pressure rises to a very high value, which can damage the pump. Positive displacement pumps are widely used for pumping fluids other than water, mostly viscous fluids. Positive displacement pumps are further classified based upon the mode of displacement: a) Reciprocating pumps if the displacement is by reciprocation of a piston plunger. Those pumps are used only for pumping viscous liquids and oil wells like chemical injection pump (see fig.1). The components of reciprocating pumps are (rings, piston, rod piston, piston cylinder, inlet and outlet valves and the camshaft. b) Rotary pumps if the displacement is by rotary action of a gear, cam or vanes in a chamber of diaphragm in a fixed casing. Rotary pumps are further classified such as internal gear, external gear, lobe and slide vane. More than 10% of the pumps installed in an industry are rotary pumps. These pumps are used for special services with particular conditions existing in industrial sites like highly viscous petroleum production in vacuum distillation refinery. Fig.1 Reciprocating pumps
  7. 7. 7 1.2.2 The components of rotary pumps a) Housing: to cover and keep the impeller, gears or reciprocating piston with the fluid under high pressure. b) Rotor: to convert kinetic energy to pressure and velocity by rotation. c) Vane: to apply force on the viscous fluid and produce pressure. d) Inlet/outlet valves: to allow the fluid to in or out from the housing. e) Mechanical seals: is a device consist of two-part stator and rotor separated by lubricant gasket, this mechanical seal used to prevent leakage from bearings and casing of most type of pumps. Fig.2 Components of centrifugal pump
  8. 8. 8 Fig.3 External gear rotary pump 1.2.3 Advantage of positive displacement pumps a) Higher pressure produces using regular motor. b) Flow doesn’t change when pressure changes. c) Easy to maintenance. d) Low in cost according to others. e) Easy to operate and fitting. f) Small areas require. 1.2.4 Disadvantage of positive displacement pumps a) Low flow serves. b) Low efficiency due to losses. c) Higher level of safety requires to operating the pump. d) Operate the pump with discharge valve closed may cause damage to the pump casing. e) Used for chemical injection and light duties only.
  9. 9. 9 Fig.4 Internal gear rotary pump 1.3 Dynamic pumps Dynamic pumps are also characterized by their mode of operation: a rotating impeller converts kinetic energy into pressure or velocity that is needed to pump the fluid. Centrifugal pumps are pure example of dynamic pumps in industry, typically, more than 75% of the pumps installed in an industry are centrifugal pumps. The fig. 5 shows how this type of pump operates; the liquid is forced into an impeller either by atmospheric pressure or in case of a jet pumps by artificial pressure. The vanes of impeller pass kinetic energy to the liquid, thereby causing the liquid to rotate. The liquid leaves the impeller at high velocity. The impeller is surrounded by a volute casing or in case of a turbine pumps a stationary diffuser ring. The volute or stationary diffuser ring converts the kinetic energy into pressure energy. A centrifugal pump has two main components; First, a rotating component comprised of an impeller and a shaft. And secondly, a stationary component comprised of a casing, casing cover, and bearings.
  10. 10. 10 Fig.5 Centrifugal pump components (Static and Rotor) 1.3.1 Centrifugal pump components a) Impeller An impeller is a circular metallic disc with a built-in passage for the flow of fluid. Impellers are generally made of bronze, polycarbonate, cast iron or stainless steel, but other materials are also used. The number of impellers determines the number of stages of the pump. A single stage pump has one impeller and is best suited for low head (1bar unit pressure = 10-meter head). Impellers can be classified on the basis of which will determine their use major direction of flow from the rotation axis Suction type: single suction and double suction. b) Shaft The main uses of shaft to transfers the torque from the motor to the impeller during the startup and operation of the pump. c) Casing Casings have two functions: I. The main function of casing is to enclose the impeller at suction and delivery ends and thereby form a pressure vessel. II. A second function of casing is to provide a supporting and bearing medium for the shaft and impeller sometimes called (bearing house) or (housing).
  11. 11. 11 1.3.2 Types of casings a) Volute casing (see fig.6) has impellers that are fitted inside the casings. One of the main purposes is to help balance the hydraulic pressure on the shaft of the pump. b) Circular casing (see fig.7) has stationary diffusion vanes surrounding the impeller periphery that convert speed into pressure energy. These casings are mostly used for multi-stage pumps [1] . The casings can be designed as solid casing (one fabricated piece) or split casing (two or more parts together). Fig.6 Volute casing of centrifugal pump Fig.7 Circular casing of centrifugal pump
  12. 12. 12 1.3.3 Advantage of centrifugal pumps a) Larger flow serves. b) Higher efficiency. c) Friction losses are less. d) Less power consumption. e) Easy to maintenance due to multipart. f) More safety and less damage than others. g) Heavy duties, malty purpose pump and widely use. 1.3.4 Disadvantage of centrifugal pumps a) Consider as low-pressure pump. b) Flow changes when pressure changes. c) Higher in cost. d) Big and flat area requires to preventing losses. e) Slip losses due to the speed of impeller (2000-3000) rpm.
  13. 13. 13 Chapter 2 2.1 Compressors Air Compressors is used for machine and tool operation, drilling, painting, soot blowing, instrument operations, and in situ operations (e.g., underground combustion). Pressures range from 5 bar = 500 kpa to the largest usage is at 25 bar = 2500 kpa which is normal plant air pressure range and can appear on the compressor pressure gages by law. Gas compressors are used for refrigeration, air conditioning, heating, pipeline conveying, natural gas gathering, catalytic cracking, polymerization, and in other chemical processes. 2.1.1 Standard Units and Conditions In the ISO system, the standard unit of pressure for compressors is the kilopascal (kPa). In some countries this is the only unit which can appear on the compressor pressure gages by law. In Europe, the European Committee of Manufacturers of Compressors, Vacuum Pumps and Pneumatic Tools (PNEUROP) and, in the United States, the Compressed Air and Gas Institute (CAGI) prefer the bar as the standard unit of pressure. PNEUROP and CAGI have selected as standard conditions 1 bar (14.5 lb/in²) (100 kPa), 20°C (68°F), and 0 percent relative humidity. The unit of flow in the ISO system is m3/s. Other units still in common usage are m3/h, m3/min, and L/s. In the United States the most commonly used units are ft3/min (cfm) and ft3/h (cfh). Power is normally expressed in kilowatts (PNEUROP) and horsepower (CAGI).
  14. 14. 14 2.2 Positive displacement compressors There are two types of positive displacement compressors according to flow and design: a) Reciprocating compressors: consider as positive displacement compressors. This means they are taking in successive volumes of air which is confined within a closed space and elevating this air to a higher pressure. The reciprocating compressor accomplishes this by using a piston within a cylinder as the compressing and displacing element. The reciprocating compressor is considered single acting when the compressing is accomplished using only one side of the piston. A compressor using both sides of the piston is considered double acting. The reciprocating compressor uses a number of automatic spring-loaded valves in each cylinder that open only when the proper differential pressure exists across the valve. Inlet valves open when the pressure in the cylinder is slightly below the intake pressure. Discharge valves open when the pressure in the cylinder is slightly above the discharge pressure. A compressor is considered to be single stage when the entire compression is accomplished with a single cylinder or a group of cylinders in parallel. Many applications involve conditions beyond the practical capability of a single
  15. 15. 15 compression stage. Too great a compression ratio (absolute discharge pressure/absolute intake pressure) may cause excessive discharge temperature or other design problems. For practical purposes most plant air reciprocating compressors over 100 horsepower are built as multi-stage units in which two or more steps of compression are grouped in series. The air is normally cooled between the stages to reduce the temperature and volume entering the following stage. Reciprocating air compressors are available either as air-cooled or water-cooled in lubricated and non-lubricated configurations, may be packaged, and provide a wide range of pressure and capacity selections. Fig.8 Single stage reciprocating compressor b) Rotary screw compressors: Rotary screw compressors are positive displacement compressors. The most common rotary compressor is the single stage helical or spiral lobe oil flooded screw air compressor. These compressors consist of two rotors within a casing where the rotors compress the air internally. There are no valves. These units are basically oil cooled (with air cooled or water-cooled oil coolers) where the oil seals the internal clearances. Since the cooling takes place right inside the compressor, the working parts never experience extreme operating temperatures. The rotary compressor, therefore, is a continuous duty, air cooled or water-cooled compressor package. Because of the simple design and few wearing parts, rotary screw air compressors are
  16. 16. 16 easy to maintain, operate and provide great installation flexibility. Rotary air compressors can be installed on any surface that will support the static weight. The two-stage oil flooded rotary screw air compressor uses pairs of rotors in a combined air end assembly. Compression is shared between the first and second stages flowing in series. This increases the overall compression efficiency up to fifteen percent of the total full load kilowatt consumption. The two-stage rotary air compressor combines the simplicity and flexibility of a rotary screw compressor with the energy efficiency of a two-stage double acting reciprocating air compressor. Two stage rotary screw air compressors are available air cooled, and water cooled and fully packages. The oil free rotary screw air compressor utilizes specially designed air ends to compress air without oil in the compression chamber yielding true oil free air. Oil free rotary screw air compressors are available air cooled, and water cooled and provides the same flexibility as oil flooded rotaries when oil free air is required. Rotary screw air compressors are available air cooled, and water cooled, oil flooded and oil free, single stage and two stages. There is a wide range of availability in configuration and in pressure and capacity. 2.2.1 Advantage of positive displacement compressors a) Higher pressure produces using regular motor. b) Flow depends on pressure ratio of compressor stage. c) Easy to maintenance. d) Low in cost according to others. e) Safety and easy to operate and fitting. f) Small areas require. g) Safety valve release valves are fitted to reduce hazard and damages to compressors. 2.2.2 Disadvantage of positive displacement compressors a) Low flow serves. b) Low efficiency due to losses. c) Air filter and dryers requires to producing wet and dry air that suitable for electrical instruments. d) Higher level of safety requires to operating the compressors. e) Used for light duties, refrigeration and air conditioning only.
  17. 17. 17 Fig.9 Single stage rotary screw air compressor 2.3 Dynamic compressor Dynamic compressors are capable of delivering large volumes of air but little pressure (0.5-3bar). These compressors are usually known as blowers and work by drawing air in and throwing it out with the use of rotary fins, these fins rotate at very high speed. There are two main types of dynamic compressor, they are centrifugal and axial. 2.3.1 Centrifugal compressors Use centrifugal force to hurl air out from the fins, centrifugal systems can generally obtain greater pressures than the axial type of compressor. Centrifugal Compressors The centrifugal compressor considered as dynamic compressor which depends on transfer of energy from a rotating impeller to the air. The rotor accomplishes this by changing the momentum and pressure of the air. This momentum is converted to useful pressure by slowing the air down in a stationary diffuser. The centrifugal air compressor is an oil free compressor by design. The oil lubricated running gear is separated from the air by shaft seals and atmospheric vents. The centrifugal is a continuous duty compressor, with few moving parts, that is particularly suited to high volume applications, especially where oil free air is required. Centrifugal air compressors are water cooled and may be packaged; typically, the package includes the after-cooler and all controls. 2.3.2 Axial compressors Type compressor uses a set of fan blades in line to generate large air flow, pressures from this method aren’t expected to reach much over 0.5 bar. The axial compressors are largely used for ventilation and as part of air processing.
  18. 18. 18 Fig.10 Single stage centrifugal compressor 2.3.3 Advantage of dynamic compressors a) Larger flow serve produces using regular motor. b) Flow depends on pressure ratio of compressor stage. c) Easy to maintenance. d) Higher efficiency. e) Less damage due to centrifugal system. f) Safety and easy to operate. g) Safety valve release valves are fitted to reduce hazard and damages to compressors. h) Dynamic compressors used for heavy duties in industrials. 2.3.4 Disadvantage of dynamic compressors a) Lower pressure produces. b) Higher in cost. c) Big area requires and difficult to install and fitting. d) Air filter and dryers requires to producing wet and dry air that suitable for electrical instruments. e) High electric power requires to operating the compressor.
  19. 19. 19 Fig.11 Axial compressor 2.4 Stalling phenomenon Stalling is an important phenomenon that affects the performance of the compressor. An analysis is made of rotating stall in compressors of many stages, finding conditions under which a flow distortion can occur which is steady in a traveling reference frame, even though upstream total and downstream static pressure are constant. In the compressor, a pressure rise hysteresis is assumed. It is a situation of separation of air flow at the aero-foil blades of the compressor. This phenomenon depending upon the blade profile leads to reduced compression and drop in engine power. Positive Stalling flow separation occurs on the suction side of the blade. Negative Stalling flow separation occurs on the pressure side of the blade. Negative stall is negligible compared to the positive stall because flow separation is least likely to occur on the pressure side of the blade. In a multi-stage compressor, at the high-pressure stages, axial velocity is very small. Stalling value decreases with a small deviation from the design point causing stall near the hub and tip regions whose size increases with decreasing flow rates. They grow larger at very low flow rate and affect the entire blade height. Delivery pressure significantly drops with large stalling which can lead to flow reversal. The stage efficiency drops with higher losses [2] .
  20. 20. 20 Fig.12 Multistage axial compressor 2.5 Compressor components 2.5.1 Receiver tanks or the air receivers a) Provide storage capacity to prevent rapid compressor cycling. b) Reduce wear and tear on compression module, inlet control system, and motor. c) Eliminate pulsing air flow. d) Avoid overloading purification system with surges in air demand. e) Damp out the dew point and temperature spikes that follow regeneration. Fig.13 Multi-stage centrifugal compressor
  21. 21. 21 2.5.2 Air dryers a) Refrigerated air dryers: Refrigerated air dryers remove moisture from the compressed air through a mechanical refrigeration system to cool the compressed air and condense water and lubricant vapor. Most refrigerated dryers cool the compressed air to a temperature of approximately 35°F, resulting in a pressure dew point range of 33°F - 39°F. Keep in mind that this range is also the lowest achievable with a refrigerated design since the condensate begins to freeze at 32°F. b) Desiccant dryers: Desiccant dryers utilize chemicals beads, called desiccant, to adsorb water vapor from compressed air. Silica gel activated alumina and molecular sieve are the most common desiccants used. (Silica gel or activated alumina is the preferred desiccants for compressed air dryers). The desiccant provides an average -40°F pressure dew point performance. Molecular sieve is usually only used in combination with silica gel or activated alumina on -100°F pressure dew point applications. c) Deliquescent air dryers: Deliquescent air dryers utilize an absorptive type chemical, called a desiccant, to provide a 20°F to 25°F dew point suppression below the temperature of the compressed air entering the dryer. The moisture in the compressed air reacts with the absorptive material to produce a liquid effluent which is then drained from the dryer. Keep in mind that this effluent is typically corrosive and must be disposed of in accordance with local regulations. 2.5.3 Filters Coalescing filters are the most common form of compressed air purification. These filters remove liquid water and lubricants from compressed air and are installed downstream in a refrigerated air dryer system or upstream in a desiccant dryer system. Filters are rated according to liquid particle retention size (micron) and efficiency, such as 0.50 micron and 99.99% D.O.P. efficient, or 0.01 micron and 99.9999% D.O.P efficient. Coalescing filters can only remove previously condensed liquids; they do not remove water or lubricant vapors from the compressed air. Any condensation produced from subsequent compressed air cooling will have to be eliminated. When seeking to remove water and lubricant vapors from compressed air, specify an air dryer. 2.5.4 Piping distribution system The piping distribution system not only controls how the air gets from the compressor room to the tools, but it is also a major factor in the energy consumed by the compressor.
  22. 22. 22 Fig.14 Air compressor system and components
  23. 23. 23 Chapter 3 3.1 Engines An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines (such as steam engines) burn a fuel to create heat, which then creates motion. Electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air and others, such as clockwork motors in wind-up toys, use elastic energy. In biological systems, molecular motors, like myosin in muscles, use chemical energy to create motion. In modern usage, the term engines typically describe devices, like steam engines and internal combustion engines, that burn or otherwise consume fuel to perform mechanical work by exerting a torque or linear force to drive machinery that generates electricity, pumps water, or compresses gas. In the context of propulsion systems, an air-breathing engine is one that uses atmospheric air to oxidize the fuel rather than supplying an independent oxidizer, as in a rocket [3] . When the internal combustion engine was invented, the term "motor" was initially used to distinguish it from the steam engine which was in wide use at the time, powering locomotives and other vehicles such as steam rollers. "Motor" and "engine" later came to be used interchangeably in casual discourse. However, technically, the two words have different meanings. An engine is a device that burns or otherwise consumes fuel, changing its chemical composition, whereas a motor is a device driven by electricity, which does not change the chemical composition of its energy source. A heat engine may also serve as a prime mover a component that transforms the flow or changes in pressure of a fluid into mechanical energy. An automobile powered by an internal combustion engine may make use of various motors and pumps, but ultimately all such devices derive their power from the engine. Another way of looking at it is that a motor receives power from an external source, and then converts it into mechanical energy, while an engine creates power from pressure (derived directly from the explosive force of combustion or other chemical reaction, or secondarily from the action of some such force on other substances such as air, water, or steam).
  24. 24. 24 Devices converting heat energy into motion are commonly referred to simply as engines. 3.2 Electrical engines An electric motor is an electric machine that converts electrical energy into mechanical energy. In normal motoring mode, most electric motors operate through the interaction between an electric motor's magnetic field and winding currents to generate force within the motor. In certain applications, such as in the transportation industry with traction motors, electric motors can operate in both motoring and generating or braking modes to also produce electrical energy from mechanical energy. Found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives, electric motors can be powered by direct current (DC) sources, such as from batteries, motor vehicles or rectifiers, or by alternating current (AC) sources, such as from the power grid, inverters or generators. Small motors may be found in electric watches. General purpose motors with highly standardized dimensions and characteristics provide convenient mechanical power for industrial use. The largest of electric motors are used for ship propulsion, pipeline compression and pumped storage applications with ratings reaching 100 megawatts. Electric motors may be classified by electric power source type, internal construction, application, type of motion output, and so on. Devices such as magnetic solenoids and loudspeakers that convert electricity into motion but do not generate usable mechanical power are respectively referred to as actuators and transducers [4] . Electric motors are used to produce linear force or torque (rotary). Fig.15 Electrical engines (Electrical motors).
  25. 25. 25 3.2.1 The components of electrical motors a) Rotor In an electric motor the moving part is the rotor which turns the shaft to deliver the mechanical power. The rotor usually has conductors laid into it which carry currents that interact with the magnetic field of the stator to generate the forces that turn the shaft. However, some rotors carry permanent magnets, and the stator holds the conductors. b) Stator The stationary part is the stator, usually has either windings or permanent magnets. The stator is the stationary part of the motor’s electromagnetic circuit. The stator core is made up of many thin metal sheets, called laminations. Laminations are used to reduce energy losses that would result if a solid core were used. c) Air gap In between the rotor and stator is the air gap. The air gap has important effects, and is generally as small as possible, as a large gap has a strong negative effect on the performance of an electric motor. d) Windings Windings are wires that are laid in coils, usually wrapped around a laminated soft iron magnetic core so as to form magnetic poles when energized with current. Electric machines come in two basic magnet field pole configurations: salient-pole machine and non-salient-pole machine. In the salient pole machine, the pole's magnetic field is produced by a winding wound around the pole below the pole face. In the non-salient pole, or distributed field, or round-rotor, machine, the winding is distributed in pole face slots. A shaded-pole motor has a winding around part of the pole that delays the phase of the magnetic field for that pole. Some motors have conductors which consist of thicker metal, such as bars or sheets of metal, usually copper, although sometimes aluminum is used. These are usually powered by electromagnetic induction. e) Commutator A commutator is a mechanism used to switch the input of certain AC and DC machines consisting of slip ring segments insulated from each other and from the electric motor's shaft. The motor's armature current is supplied through the stationary brushes in contact with the revolving commutator, which causes required current reversal and applies power to the machine in an optimal manner
  26. 26. 26 as the rotor rotates from pole to pole. In absence of such current reversal, the motor would brake to a stop. In light of significant advances in the past few decades due to improved technologies in electronic controller, sensor less control, induction motor, and permanent magnet motor fields, electromechanically commutated motors are increasingly being displaced by externally commutated induction and permanent magnet motors [5] . Fig.16 The structure of electrical motors Fig.17 The electrical motors
  27. 27. 27 3.2.2 Uses of electrical motors a) To convert electrical power to mechanical work. b) To drive rotary machine in industrial like, pumps, fans and lifting system. 3.2.3 The advantage of electrical engine or motor a) Easy operation and maintenance. b) No environment pollution and noise less. c) Not require cooling system. d) Safety and easy control. e) Variable speed. 3.2.4 The disadvantage of electrical engine or motors a) Used in light duties in industrials. 3.3 Electrical generator In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric current to flow through an external circuit. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed air, or any other source of mechanical energy. Generators provide nearly all of the power for electric power grids. The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be mechanically driven to generate electricity and frequently make acceptable generators as you see in fig.18 below: (a) (b) Fig. 18 Electrical generator (a) Electrical generator drive by turbine engine. (b) Electrical generator drive by internal combustion engine.
  28. 28. 28 3.3.1 The difference between electrical motors and electrical generators a) A generator converts electrical energy to mechanical energy, while a motor converts mechanical energy to electrical energy. b) In a generator, a shaft attached to the rotor is driven by a mechanical force and electric current is produced in the armature windings, while the shaft of a motor is driven by the magnetic forces developed between the armature and field; current has to be supplied to the armature winding. c) Motors (generally a moving charge in a magnetic field) obey the Fleming`s Left Hand Rule, while the generator obeys Fleming’s Right Hand Rule. 3.4 External combustion engine The difference between internal and external combustion engines, as their names Suggest, is that the former burn their fuel within the power cylinder, but the latter use their fuel to heat a gas or a vapor through the walls of an external chamber, and the heated gas or vapors is then transferred to the power cylinder. External combustion engines therefore require a heat exchanger, or boiler to take in heat, and as their fuels are burnt externally under steady conditions, they can in principle use any fuel that can burn, including agricultural residues or waste materials. There are two main families of external combustion engines; steam engines which rely on expanding steam (or occasionally some other vapors) to drive a mechanism; or Stirling engines which use hot air (or some other hot gas). The use of both technologies reached their zeniths around 1900 and has declined almost to extinction since [6] . However, a brief description is worthwhile, since: I. They were successfully and widely used in the past for pumping water. II. They both have the merit of being well suited to the use of low-cost fuels such as coal, peat and biomass. III. Attempts to update and revive them are taking place. The primary disadvantage of e.c. engines is that a large area of heat exchanger is necessary to transmit heat into the working cylinder(s) and also to reject heat at the end of the cycle. As a result, e.c. engines are generally bulky and expensive to construct compared with i.c. engines. Also, since they are no longer generally manufactured, they do not enjoy the economies of mass-production available to i.e. engines. They also will not start so quickly or conveniently as an i.c. engine; because it takes time to light the fire and heat the machine to its working temperature.
  29. 29. 29 Due to their relatively poor power/weight ratio and also the worse energy/weight ratio of solid fuels, the kinds of applications where steam or Stirling engines are most likely to be acceptable are for static applications such as as irrigation water pumping in areas where petroleum fuels are not readily available but low-cost solid fuels are. On the positive side, e.c. engines have the advantage of having the potential to be much longer lasting than i.c. engines (100-year-old steam railway locomotives are relatively easy to keep in working order, but it is rare for i.c. engines to be used more than 20 years or so engines are also significantly quieter and free of vibrations than i.c. engines. The level of skill needed for maintenance may also be lower, although the amount of time spent will be higher, particularly due to the need for cleaning out the furnace. Modern engineering techniques promise that any future steam or Stirling engines could benefit from features not available over 60 years ago when they were last in general use. is in hand in various countries on a limited, however it will probably be some years before a new generation of multi-fuel Stirling or steam powered pumps become generally available. Fig.19 External combustion engine 3.4.1 Steam engines Only a limited number of small steam engines are available commercially at present most are for general use or for powering small pleasure boats. A serious attempt to develop a 2kW steam engine for use in remote areas was made by the engine designers, Ricardos, in the UK during the 1950s. That development was possibly
  30. 30. 30 premature and failed, but there is currently a revival of interest in developing power sources that can run on biomass-based fuels. However, small steam engines have always suffered from their need to meet quite stringent safety requirements to avoid accidents due to boiler explosions, and most countries have regulations requiring the certification of steam engine boilers, which is a serious, but necessary, inhibiting factor. The principle of the steam engine is illustrated in Fig. 19. Fuel is burnt in a furnace and the hot gases usually pass-through tubes surrounded by water (fire tube boilers). Steam is generated under pressure typically 5 to 10 atmospheres (or 5-10bar). A safety valve is provided to release steam when the pressure becomes too high so as to avoid the risk of an explosion. High pressure steam is admitted to a power cylinder through a valve, where it expands against a moving piston to do work while its pressure drops. The inlet valve closes at a certain point, but the steam usually continues expanding until it is close to atmospheric pressure, when the exhaust valve opens to allow the piston to push the cooled and expanded steam out to make way for a new intake of high-pressure steam. The valves are linked to the drive mechanism so as to open or close automatically at the correct moment. The period of opening of the inlet valve can be adjusted by the operator to vary the speed and power of the engine. 3.5 Internal combustion engine The internal combustion engine is an engine in which the combustion of a fuel (normally a fossil fuel) occurs with an oxidizer (usually air) in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and pressure gases produced by combustion applies direct force to some component of the engine, such as pistons, turbine blades, or a nozzle. This force moves the component over a distance, generating useful mechanical energy. The term internal combustion engine usually refers to an engine in which combustion is intermittent, such as the more familiar four-stroke and two-stroke piston engines, along with variants, such as the Wankel rotary engine. A second class of internal combustion engines use continuous combustion: gas turbines, jet engines and most rocket engines, each of which are internal combustion engines on the same principle as previously described.
  31. 31. 31 Fig.20 Internal combustion engine 3.5.1 Type of engine according to design a) Two stroke engines The two-stroke type of internal combustion engine is typically used in utility or recreational applications which require relatively small, inexpensive, and mechanically simple motors (chainsaws, jet skis, small motorcycles, etc). The two-stroke engine is simple in construction, but complex dynamics are employed in its operation. There are several features unique to a two-stroke engine. First, there is a reed valve between the air-fuel intake and the crankcase. Air-fuel mixture enters the crankcase and is trapped there by the one-way reed valve. Next, the cylinder has no valves as in a conventional four stroke engine. Intake and exhaust are accomplished by means of ports special holes cut into the cylinder wall which allows fuel-air mixture to enter from the crankcase, and exhaust to exit the engine. These ports are uncovered when the piston is in the down position. Air-fuel mixture is drawn into the crankcase from the carburetor or fuel injection system through the reed valve. When the piston is forced down, the exhaust port is uncovered first, and hot exhaust gases begin to leave the cylinder. As the piston is now in the down position, the crankcase becomes pressurized, and when the intake port into the cylinder is uncovered, pressurized air-fuel mixture enters the chamber. Both the intake and exhaust ports are open at the same time, which means the timing and air flow dynamics are critical to proper operation. As the piston begins to move up, the ports are closed off, and the air-fuel mixture compresses and is ignited; the hot gases increase in pressure, pushing the piston down with great force and creating work for the engine [7] .
  32. 32. 32 The major components of two-stroke engines are tuned so that optimum airflow results. Intake and exhaust tubes are tuned so that resonances in airflow give better flow than a straight tube. The cylinder ports and piston top are shaped so that the intake and exhaust flows do not mix. b) Four strokes The four-stroke internal combustion engine is the type most commonly used for automotive and industrial purposes today (cars and trucks, generators, etc). On the first (downward) stroke of the piston, fuel/air is drawn into the cylinder. The following (upward) stroke compresses the fuel-air mixture, which is then ignited expanding exhaust gases then force the piston downward for the third stroke, and the fourth and final (upward) stroke evacuates the spent exhaust gasses from the cylinder. The four-stroke cycle is more efficient than the two-stroke cycle but requires considerably more moving parts and manufacturing expertise. Fig.21 Two stroke engine cycles 3.5.2 Type of engine according to fuel combustion a) Spark ignition engine (gasoline engine): The term spark-ignition engine refers to internal combustion engines, usually petrol engines, where the combustion process of the air-fuel mixture is ignited by a spark from a spark plug. This is in contrast to compression-ignition engines, typically diesel engines, where the heat generated from compression is enough to initiate the combustion process, without needing any external spark.
  33. 33. 33 Spark-ignition engines are commonly referred to as "gasoline engines" in America, and "petrol engines" in Britain and the rest of the world. However, these terms are not preferred, since spark-ignition engines can (and increasingly are) run on fuels other than petrol/gasoline, such as auto gas (LPG), methanol, ethanol, bioethanol, compressed natural gas (CNG), hydrogen, and (in drag racing) nitromethane. A working cycle consists of four-stroke spark-ignition engine is an Otto cycle engine. It consists of following four strokes: suction or intake stroke, compression stroke, expansion or power stroke, exhaust stroke. Each stroke consists of 180 degree rotation of crankshaft rotation and hence a four-stroke cycle is completed through 720 degree of crank rotation. Thus, for one complete cycle there is only one power stroke while the crankshaft turns by two revolutions. Fig.22 P-V Diagram Ideal Otto Cycle 3.5.3 Diesel engine Compression Ignition (CI) The combustion process in a CI engine starts when the air-fuel mixture self-ignites due to high temperature in the combustion chamber caused by high compression.
  34. 34. 34 The diesel engine has the highest thermal efficiency of any standard internal or external combustion engine due to its very high compression ratio. Low-speed diesel engines (as used in ships and other applications where overall engine weight is relatively unimportant) can have a thermal efficiency that exceeds 50%. Diesel engines are manufactured in two-stroke and four-stroke versions. They were originally used as a more efficient replacement for stationary steam engines. Since the 1910s they have been used in submarines and ships. Use in locomotives, trucks, heavy equipment and electric generating plants. Diesel engine based on diesel cycle as shown in diagram below: Fig. 23 P-V Diagram diesel cycle 3.5.4 Engine parts a) Valves The intake and exhaust valves open at the proper time to let in air and fuel and to let out exhaust. Note that both valves are closed during compression and combustion so that the combustion chamber is sealed. b) Piston A piston is a cylindrical piece of metal that moves up and down inside the cylinder.
  35. 35. 35 c) Piston rings Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder. The rings serve two purposes They prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump during compression and combustion. They keep oil in the sump from leaking into the combustion area, where it would be burned and lost. Most cars that "burn oil" and have to have a quart added every 1,000 miles are burning it because the engine is old, and the rings no longer seal things properly. d) Connecting rod The connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates. e) Crankshaft The crankshaft turns the piston's up and down motion into circular motion just like a crank on a jack-in-the-box does. f) Sump The sump surrounds the crankshaft. It contains some amount of oil, which collects in the bottom of the sump (the oil pan). g) Superchargers and turbochargers A supercharger and turbochargers are a "forced induction" system which uses a compressor powered by the shaft of the engine which forces air through the valves of the engine to achieve higher flow. When these systems are employed the maximum absolute pressure at the inlet valve is typically around 2 times atmospheric pressure or more [8] . Fig.24 Turbocharger
  36. 36. 36 3.5.5 Engine parameters a) Indirect injection (IDI): Fuel injection into the secondary chamber of an engine with a divided combustion chamber. b) Bore: Diameter of the cylinder or diameter of the piston face, which is the same minus a very small clearance. c) Stroke: Movement distance of the piston from one extreme position to the other: TDC to BDC or BDC to TDC. d) Clearance: Volume Minimum volume in the combustion chamber with piston at TDC. e) Displacement or displacement volume: Volume displaced by the piston as it travels through one stroke. Displacement can be given for one cylinder or for the entire engine (one cylinder time number of cylinders). Some literature calls this swept volume. Fig.25 Diesel engine with double turbocharger
  37. 37. 37 3.5.6 The difference between SI engine and CI engine a) SI engine spark ignition system ignites the A/F mixture to produce power and not available in CI engine that depend totally on compression ratio and flash point of diesel fuel. b) Fuel injection is direct in CI engine and separated from air, which is different from SI engine are mixed. c) In CI engine thermal efficiency, power and torque are higher than SI engine. d) Compression ratio in CI engine is 8-12, in SI engine around 4-6. e) Fuel consumption in CI engine is less than SI engine. f) CI engine used in heavy duties and SI engine used for light duties.
  38. 38. 38 Chapter 4 4.1 Crude oil storages When we drill wells in a productive field and start production, we need to store and/or transport the fluids to the market. When several oil production wells are present then connection of surface lines could be made in bundles. At the wellhead the separators (single or two stages) can be utilized. They are used to separate the remaining gas in solution by adjusting pressure in the separator. Water is separated due to the gravity difference. Crude oil is fed into crude oil line and gas is flowed through the gas lines. The storage of crude oil, refinery products and natural gas is an important subject. It is needed to store them when they are not used. The necessary conditions must be satisfied during storing. Crude oil is stored in large tanks after produced. When we look at an oil field, we can see large storage tanks clustered together in what is called tank farm. These may run in size from a few hundred to several thousand barrels capacity, according to the production of the wells. In the really big tank farms, it is quite common to see tanks of 55,000 and 80,000 barrels capacity. Other groups of storage tanks may be seen at key points along pipelines, at ports where oil is loaded on tankers, and at the refineries to which crude oil goes to be processed for the market. An enormous amount of crude petroleum is constantly kept stored in such tanks in all parts of the world. The produced natural gas is liquefied before storage. It is also stored in underground formations. Natural gas is injected into suitable formations when market demand is low. Then it is produced when demand is high. Fig.26 Spherical gas tank farm in the petroleum refinery
  39. 39. 39 Reservoirs can be covered; in which case they may be called covered or underground storage tanks or reservoirs. Covered water tanks are common in urban areas. 4.2 Type of crude oil storages Storage tanks are available in many shapes: vertical and horizontal cylindrical; open top and closed top; flat bottom, cone bottom, slope bottom and dish bottom. Large tanks tend to be vertical cylindrical, or to have rounded corners transition from vertical side wall to bottom profile, to easier withstand hydraulic hydrostatically induced pressure of contained liquid. Most container tanks for handling liquids during transportation are designed to handle varying degrees of pressure. There are two basic type of oil storage according to roof design: a) Fixed roof tanks are meant for liquids with very high flash points, (e.g. fuel oil, water, bitumen etc.) Cone roofs, dome roofs and umbrella roofs are usual. These are insulated to prevent the clogging of certain materials, wherein the heat is provided by steam coils within the tanks. Dome roof tanks are meant for tanks having slightly higher storage pressure than that of atmosphere (e.g. slop oil), fixed Roof Tank used for diesel, kerosene, catalytic cracker feedstock, and residual fuel oil. b) Floating roof tanks are broadly divided into external floating roof tanks (usually called as floating roof tanks FR Tanks) and internal floating roof types (IFR Tanks) and used for crude oil, gasoline, and naphtha. c) Bullet tank used for normal butane, propane, and propylene d) Spherical tank used for iso-butane and normal-butane. It is to be noted that fixed roof tanks could be used for storing low amounts of crude oil as compared to the million barrels stored in floating roof tanks. 4.3 Crude oil storage components 1. Storage body or shell. 2. Stairs. 3. Drain valve. 4. Inlet valve. 5. Outlet valve. 6. Fire system. 7. Pressure relief valve. 8. Pressure gage. 9. Level Trans meter.
  40. 40. 40 Fig.27 Fixed roof tank Fig.28 Floating roof tank
  41. 41. 41 Fig.29 Crude oil storage components
  42. 42. 42 Chapter 5 5.1 Reactors Chemical reactors are vessels designed to contain chemical reactions. It is the site of conversion of raw materials like naphtha, kerosene and other materials into products ready to use and is also called the heart of a chemical process. The design of a chemical reactor where the motion of fluid over the catalyst would be synthetic sized on a commercial scale would depend on multiple aspects of chemical engineering. The Since it is a very vital step in the overall design of a process, designers ensure that the reaction proceeds with the highest efficiency towards the desired output, producing the highest yield of product in the most cost-effective way. Reactors are designed based on features like mode of operation or types of phases present or the geometry of reactors. They are thus according to operation of reactor called: a) Batch reactors: A process in which all the reactants are added together at the beginning of the process and products removed at the termination of the reaction iscalled a batch process. In this process, no addition or withdrawal is made while the reaction is progressing (Fig. 30). Batch processes are suitable for small production and for processes where a range of different products or grades is to be produced in the same equipment for example, pigments, dye stuff and polymers. b) Semi continues reactors: A Process that do not fit in the definition of batch or a semi batch reactor is operated with both continuous and batch inputs and outputs and are often referred to as semi continuous or semi-batch. In such semi-batch reactors, some of the reactants may be added or some of the products withdrawn as the reaction proceeds. A semi-continuous process can also be one which is interrupted periodically for some specific purpose, for example, for the regeneration of catalyst, or for removal of gas c) Continuous reactors: A process in which the reactants are fed to the reactor and the products or byproducts are withdrawn in between while the reaction is still progressing. For example, Haber Process for the manufacture of Ammonia. Continuous production will normally give lower production costs as compared to batch production, but it faces the limitation of lacking the flexibility of batch production. Continuous reactors are usually preferred for large scale production.
  43. 43. 43 Fig.30 Chemical reactors 5.2 Type of reactors according to phase a) Homogenous phase: Homogeneous reactions are those in which the reactants, products and any catalyst used form one continuous phase; for example, gaseous or liquid. Homogeneous gas phase reactors will always be operated continuously. Tubular (Pipeline) reactors are normally used for homogeneous gas phase reactions, for example, in the thermal cracking of petroleum, crude oil fractions to ethylene. Homogeneous liquid phase reactors may be batch or continuous. b) Heterogeneous phase: In a heterogeneous reaction two or more phases exist and the overriding problems in the reactor design is to promote mass transfer between the phases.
  44. 44. 44 5.3 Type of reactor according to design a) Stirred Tank Reactor: The stirred tank reactor can be considered the basic chemical reactor, modeling on a large scale. Tank sizes range from a few liters to several thousand liters. b) Tubular Reactor: Tubular reactors are generally used for gaseous reactions but are also suitable for some liquid phase reactions. If high heat transfer rates are required small diameter tubes are used to increase the surface area to volume ratio. c) Packed Bed Reactor: Industrial packed bed catalytic reactors range in size from small tubes, a few centimeters diameter to large diameter packed beds. Packed bed reactors are used for gas and gas liquid reactions. Heat transfer rates in large diameter packed beds are poor therefore, where high heat-transfer rates are required, fluidized beds should be considered. d) Fluidized Bed Reactor: A fluidized bed reactor is a combination of the two most common, packed beds and stirred tank, continuous flow reactors. It is very important to chemical engineering because of its excellent heat and mass transfer characteristics. 5.4 Catalyst Catalysis is the increase in the rate of a chemical reaction of one or more reactants due to the participation of an additional substance called a catalyst. Unlike other reagents in the chemical reaction, a catalyst is not consumed by the reaction. With a catalyst, less free energy is required to reach the transition state, but the total free energy from reactants to products does not change. A catalyst may participate in multiple chemical transformations. The effect of a catalyst may vary due to the presence of other substances known as inhibitors or poisons (which reduce the catalytic activity) or promoters (which increase the activity). The opposite of a catalyst, a substance that reduces the rate of a reaction, is an inhibitor. Catalyzed reactions have lower activation energy (rate limiting free energy of activation) than the corresponding un-catalyzed reaction, resulting in a higher reaction rate at the same temperature and for the same reactant concentrations. However, the mechanistic explanation of catalysis is complex. Catalysts may affect the reaction environment favorably, or bind to the reagents to polarize bonds, e.g. acid catalysts for reactions of carbonyl compounds, or form specific intermediates that are not produced naturally, such as platinum or rhenium in catalytic hydrogenation.
  45. 45. 45 Kinetically, catalytic reactions are typical chemical reactions, i.e., the reaction rate depends on the frequency of contact of the reactants in the rate determining step. Usually, the catalyst participates in this slowest step, and rates are limited by amount of catalyst and its "activity". In heterogeneous catalysis, the diffusion of reagents to the surface and diffusion of products from the surface can be rate determining. A nanomaterial-based catalyst is an example of a heterogeneous catalyst. Analogous events associated with substrate binding and product dissociation apply to homogeneous catalysts. Although catalysts are not consumed by the reaction itself, they may be inhibited, deactivated, or destroyed by secondary processes. In heterogeneous catalysis, typical secondary processes include coking where the catalyst becomes covered by polymeric side products. Additionally, heterogeneous catalysts can dissolve into the solution in a solid - liquid system or sublimate in a solid–gas system. Fig. 31 Reactors in reformer unit
  46. 46. 46 5.5 Reactor design In the chemical industry, proper reactor design is crucial because this is where both mixing, and reaction occur. For a mixing sensitive reaction, the rate of mixing affects both the yield and selectivity of the reaction. Poor mixing can lead to side reactions and undesirable by products in competitive reactions. A common industrial example of this is acid/base neutralization in the presence of organic substrates. Rapid, highly turbulent mixings needed to promote the fast-reacting neutralization reaction and inhibit the slower, unwanted side reactions such as hydrolysis. There are many react, or geometries used in the chemical industry, but discussion will be limited to four geometries: pipeline, Tee mixer, static mixer, and stirred tank. Additionally, the effect of feed point location will be discussed. A pipe, or tubular reactor, is the simplest chemical reactor. Reactants are injected in one end and allowed to mix as they flow towards the outlet. Often injection is done with a co-axial jet in the center of the pipe. Turbulent flow requires approximately 50 to 100 pipe diameters to achieve 95% Uniformity within the pipeline. This option is often used successfully in highly turbulent flow where mixing length and time are not important. Fig.32 Chemical reactor
  47. 47. 47 Chapter 6 6.1 Heating, ventilation and air conditioning [HVAC] The heat, ventilation and air conditioning system (HVAC) feeds conditioned air to the equipment and accommodation rooms, etc. Cooling and heating are achieved by water-cooled or water/steam-heated heat exchangers. Heat may also be taken from gas turbine exhaust. In tropical and sub-tropical areas, cooling is achieved by compressor refrigeration units. In tropical areas, gas turbine inlet air must be cooled to achieve sufficient efficiency and performance. The HVAC system is usually delivered as one package and may also include air emissions cleaning. Some HVAC subsystems include: a) Cool: cooling medium, refrigeration system, freezing system b) Heat: heat medium system, hot oil system One function is to provide air to equipment rooms that are secured by positive pressure. This prevents potential influx of explosive gases in case of a leak. c) Ventilating Is the process of "changing" or replacing air in any space to provide high indoor air quality (i.e. to control temperature, replenish oxygen, or remove moisture, odors, smoke, heat, dust, airborne bacteria, and carbon dioxide). Ventilation is used to remove unpleasant smells and excessive moisture, introduce outside air, to keep interior building air circulating, and to prevent stagnation of the interior air [9] . Fig.33 HVAC system
  48. 48. 48 6.2 Refrigeration cycle The vapor compression refrigeration cycle is a common method for transferring heat from a low temperature to a high temperature. The above figure shows the objectives of refrigerators and heat pumps. The purpose of a refrigerator is the removal of heat, called the cooling load, from a low-temperature medium. The purpose of a heat pump is the transfer of heat to a high-temperature medium, called the heating load. When we are interested in the heat energy removed from a low-temperature space, the device is called a refrigerator. When we are interested in the heat energy supplied to the high-temperature space, the device is called a heat pump. In general, the term heat pump is used to describe the cycle as heat energy is removed from the low-temperature space and rejected to the high temperature space. The performance of refrigerators and heat pumps is expressed in terms of Coefficient of Performance (COP). Refrigeration systems are also rated in terms of tons of refrigeration. One ton of refrigeration is equivalent to 12,000 Btu/hr or 211 kJ/min. How did the term “ton of cooling” originate? Reversed Carnot Refrigerator and Heat Pump shown below are the cyclic refrigeration device operating between two constant temperature reservoirs and the T-s diagram for the working fluid when the reversed Carnot cycle is used. Recall that in the Carnot cycle heat transfers take place at constant temperature. If our interest is the cooling load, the cycle is called the Carnot refrigerator. If our interest is the heat load, the cycle is called the Carnot heat pump. Fig.34 Refrigration cycle The vapor-compression refrigeration cycle has four components: evaporator, compressor, condenser, and expansion (or throttle) valve. The most widely used refrigeration cycle is the vapor-compression refrigeration cycle.
  49. 49. 49 In an ideal vapor-compression refrigeration cycle, the refrigerant enters the compressor as a saturated vapor and is cooled to the saturated liquid state in the condenser. It is then throttled to the evaporator pressure and vaporizes as it absorbs heat from the refrigerated space. The ideal vapor-compression cycle consists of four processes. Fig.35 The vapor-compression refrigeration cycle 6.2.1 Ideal vapor-compression refrigeration cycle process description 1-2 Isentropic compression 2-3 Constant pressure heat rejection in the condenser 3-4 Throttling in an expansion valve 4-1 Constant pressure heat addition in the evaporator
  50. 50. 50 Fig.36 Expansion valve in refrigeration system To increase the [COP] of the cycle, increase the evaporation temperature or decrease the condensing temperature. However, you can’t achieve as cold of a temperature now, and your heat exchanger will need to be larger since temperature difference is smaller, 2-4% increase in [COP] per degree temperature change. COPR = Desired output Required input = Cooling effect Work input = QL …………………… (1) COPHP = Desired output Required input = Heating effect Work input = QH …………………… (2) COPHP = COPR + 1 …………………… (3)
  51. 51. 51 Chapter 7 7.1 Upstream process sections in oil and gas location We will go through each section in detail in the following chapters. The summary below is an introductory synopsis of each section. The activities up to the producing wellhead (drilling, casing, completion and wellhead) are often called “pre-completion,” while the production facility is “post-completion.” For conventional fields, they tend to be roughly the same in initial capital expenditure. 7.1.1 Wellheads The wellhead sits on top of the actual oil or gas well leading down to the reservoir. A wellhead may also be an injection well, used to inject water or gas back into the reservoir to maintain pressure and levels to maximize production. Fig.37 Wellheads Once a natural gas or oil well is drilled and it has been verified that commercially viable quantities of natural gas are present for extraction, the well must be “completed” to allow petroleum or natural gas to flow out of the formation and up to the surface. This process includes strengthening the well hole with casing, evaluating the pressure and temperature of the formation, and installing the proper equipment to ensure an
  52. 52. 52 efficient flow of natural gas from the well. The well flow is controlled with a choke. We differentiate between, dry completion (which is either onshore or on the deck of an offshore structure) and subsea completions below the surface. The wellhead structure, often called a Christmas tree, must allow for a number of operations relating to production and well work over. Well work over refers to various technologies for maintaining the well and improving its production capacity. 7.1.2 Manifolds Onshore, the individual well streams are brought into the main production facilities over a network of gathering pipelines and manifold systems. The purpose of these pipelines is to allow setup of production "well sets" so that for a given production level, the best reservoir utilization well flow composition (gas, oil, water), etc., can be selected from the available wells. For gas gathering systems, it is common to meter the individual gathering lines into the manifold as shown in this picture. For multiphase flows (combination of gas, oil and water), the high cost of multiphase flow meters often leads to the use of software flow rate estimators that use well test data to calculate actual flow. Offshore, the dry completion wells on the main field center feed directly into production manifolds, while outlying wellhead towers and subsea installations feed via multiphase pipelines back to the production risers. Risers are a system that allows a pipeline to "rise" up to the topside structure. For floating structures, this involves a way to take up weight and movement. For heavy crude and in Arctic areas, diluents and heating may be needed to reduce viscosity and allow flow. Fig.38 Manifolds and gathering
  53. 53. 53 7.1.3 Separation Some wells have pure gas production which can be taken directly for gas treatment and/or compression. More often, the well produces a combination of gas, oil and water, with various contaminants that must be separated and processed. The production separators come in many forms and designs, with the classic variant being the gravity separator. In gravity separation, the well flow is fed into a horizontal vessel. The retention period is typically five minutes, allowing gas to bubble out, water to settle at the bottom and oil to be taken out in the middle. The pressure is often reduced in several stages (high pressure separator, low pressure separator, etc.) to allow controlled separation of volatile components. A sudden pressure reduction might allow flash vaporization leading to instability and safety hazards [10] . Fig.39 Crude oil separator 7.1.4 Metering, storage and export Most plants do not allow local gas storage, but oil is often stored before loading on a vessel, such as shuttle tanker taking oil to a larger tanker terminal, or direct to a crude carrier. Offshore production facilities without a direct pipeline connection generally rely on crude storage in the base or hull, allowing a shuttle tanker to offload about once a week. A larger production complex generally has an associated tank farm terminal allowing the storage of different grades of crude to take up changes in demand, delays in transport, etc. Metering stations allow operators to monitor and manage the natural gas and oil exported from the production installation. These employ specialized meters to measure the natural gas or oil as it flows through the pipeline, without impeding its movement. This metered volume represents a transfer of ownership from a producer to a customer (or another division within the company) and is called custody transfer metering. It forms the basis for invoicing the sold product and
  54. 54. 54 also for production taxes and revenue sharing between partners. Accuracy requirements are often set by governmental authorities. Typically, a metering installation consists of a number of meters runs so that one meter will not have to handle the full capacity range and associated proved loops so that the meter accuracy can be tested and calibrated at regular intervals. Fig.40 Tank storage and transportation 7.1.5 Utility systems Utility systems are systems which do not handle the hydrocarbon process flow but provide some service to the main process safety or residents. Depending on the location of the installation, many such functions may be available from nearby infrastructure, such as electricity. Many remote installations are fully self-sustaining and must generate their own power, water, etc. Fig.41 Circulation system
  55. 55. 55 Units Some common units used in the industries are listed here as a representative selection of US and metric units, since both are used in different parts of the industries. The non-standard factors differ slightly between different sources. API American Petroleum Institute crude grade API = (141.5 / Specific gravity) – 131.5 Spec gravity = 141.5/(API + 131.5) kg/l Bl Barrel (of oil) 1 Bl = 42 Gallons 1 Bl = 159 liters 1 Bl equiv. to 5487 scf = 147 scm gas Bpd Barrel per day 1 Bpd ≈ 50 tons/tons per year BTU British thermal unit 1 BTU = 0.293 Wh = 1,055 kJ Cal Calorie 1 Cal = 4,187 J (Joules) MMscf Million standard cubic feet 1 MMscf = 23.8 TOE ≈ 174 barrels psi Pounds per square-inch 1 psi = 6.9 kPa = 0.069 atm Scf Standard cubic feet (of gas) defined by energy, not a normalized volume 1 scf = 1000 BTU = 252 kcal = 293 Wh = 1,055 MJ ≈ 0.0268 scm Scm Standard cubic meter (of gas, also Ncm) Defined by energy content 1 Scm = 39 MJ = 10.8 kWh 1 Scm ≈ 37.33 Scf (not a volume conv.) 1 Scm ≈ 1.122 kg TOE Tons oil equivalent Range 6.6 - 8 barrels at API range 8 - 52 1 TOE = 1000 kg = 1 Ton (metric) oil 1 TOE = 1 Tone oil (US) 1 TOE ≈ 7.33 Barrels (at 33 API) 1 TOE ≈ 42.9 GJ =11,9 MWh 1 TOE ≈ 40.6 MMBTU 1 TOE ≈ 1.51 ton of coal 1 TOE ≈ 0.79 ton LNG 1 TOE ≈ 1,125 Scm = 42,000 Scf kWh Kilowatt hour= 1000 joules * 3600 S 1 kWh = 3.6 MJ = 860 kcal = 3,413 BTU
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