Pump and Piping Systems in Power Plants, Exams of Engineering

Download Pump and Piping Systems in Power Plants and more Exams Engineering in PDF only on Docsity! Ref-B practice exam Questions with Answers 2024 What is a jurisdiction? ✔ Each province and territory is its own jurisdiction Explain the intent of the regulation's governing the operation of boilers and pressure equipment? ✔ To give the director or administrator of the department or branch or government a means of evolving, within the framework of the intent of the act, to meet changes in technology, concept, and the use of those variables listed within the scope of the act. Is it more difficult to change an act or a regulation? ✔ The main or primary document is an "act" which must be passed through the jurisdictional legislature. The act then has "regulations" which are pursuant to the enforcement of the act. These regulations are usually under the governance of an official of the government rather than the actual legislature. As a result, it is much easier to have changes made to a regulation than it is to have changes made to an act. What jurisdictional item or legislation is most important to a person interning time make power engineering a career choice? ✔ Power engineers acts and regulations What two Canadian national codes have been adopted by all jurisdictions ✔ CSA B51 and CSA B52 List some of the penalties which may be applied to the holder of a certificate of competency ✔ The regulation will also refer to penalties which may be listed in the pertinent jurisdictional act. These can be fines, certificate suspensions, certificate cancellations, imprisonment. List types of pressure vessels discussed in the CSA B51 section entitled "pressure vessels" ✔ Blowoff vessels, hot water tanks, hydropneumatic tanks, and cushion tanks Explain the two purposes of the CSA B52 code ✔ To provide for the safe design, construction, installation, operation, and repair of refrigerating and air conditioning equipment and systems, and related equipment. To promote uniform requirements among the provinces and territories. Describe the purpose of ASME Section VI - recommended rules for the care and operation of heating boilers and explain how this purpose is achieved. ✔ This code contains rules that have been compiled to assist operators of heating boilers in maintaining their plants in as safe a condition as possible. These rules apply to the boiler proper and to pipe connections up to and including the value of valves required by the ASME code. Rules are also given covering auxiliary equipment in so far as safety is concerned What recommended procedures are covered in ASME Section VI - recommended rules for the care and operation of heating boilers pertaining to the treatment of water in steam and hot water heating boilers? ✔ These recommended procedures cover the treatment of water in steam and hot water boilers. They cover boiler water troubles, chemicals used, function of chemicals, treatment alternatives, blowdown, feeders, and procedures Which of the following items are covered in the appendix or the ASME Boiler and Pressure Vessel Code, Section IV - Heating Boilers? a) approval of new materials under code b) porosity charts for weld radiography c) manufacturer's data report forms and guides d) all of the above ✔ D Which of the ASME codes deal with some conditions which are not encountered in Section I - Power Boilers? a) section VI b) section IV c) section VII d) CSA B51 ✔ C The amount of heat required to raise the temperature of a unit mass if a substance 1 degree Celsius without changing the state of the substance is defined as a) sensible heat b) specific heat c) superheat d) saturated ✔ B _________ heat causes a change in the temperature of a substance without changing its state a) sensible b) specific c) superheat d) saturated ✔ A The first law of thermodynamics states that heat and work are A) 539.45 N B) 1.39 kN C) 735.75 N D) 626.55 N ✔ C A hydraulic plunger has an area of 0.10 m*m and a force of 200 N acts in it. What is the pressure exerted on the plunger? A) 1.64 kPa B) 750 Pa C) 1.84 kPa D) 2 kPa ✔ D Potential energy is the ability of a body to do work by virtue of its A) pressure B) position C) force D) acceleration ✔ B If a welding electrode has the following identifying number E7015 what does the 70 represent? A) 70 mm B) 70000 psi C) 70000 kPa D) best angle to be used when welding ✔ B With straight polarity the welding electrode is connected to A) the positive terminal B) either terminal C) the negative terminal D) a good ground ✔ C Submerged arc welding is A) an oxyacetylene welding process B) an AC electric welding process C) a DV welding process D) an AC or DC electric welding process ✔ D Braze welding is used extensively in the repair of ________ and ________ parts A) wrought iron, cast iron B) stainless steel, carbon steel C) aluminum, white metal D) cast iron, malleable iron ✔ D A method of testing a weld which is quick easy and inexpensive is the A) fluorescent penetrant method B) visual method C) ultrasonic method D) dye penetrant method ✔ B When using radiographic inspections defects such as cracks and porosity show up as _________ on the photographic paper A) hairline cracks B) pinholes C) slag inclusion D) darker shadows ✔ D The method of detection that is effective and widely used to detect leaks in the welded joints of tanks and containers is A) hydrostatic test B) ultrasonic test C) fluorescent penetrant D) magparticle ✔ C A gas pocket or weld cavity caused by gas or moisture trapped in a weld is called a A) blow hole B) crack C) crater D) root crack ✔ A A reducing flame is one which is rich in A) oxygen B) acetylene C) nitrogen D) argon ✔ B Down hand is welding performed from the A) upper side of the joint and the weld face is horizontal B) lower side of the joint and the weld face is horizontal C) upper side of the joint and the weld face is vertical D) lower side of the joint and the weld face is vertical ✔ A To cut stainless steel neatly with an Oxyacetylene torch,what must be used? A) an oxygen rich flame B) a plasma torch C) a waster plate of ordinary carbon steel D) excess heat ✔ C The pressure in a fully charged oxygen cylinder is about _____ kPa A) 15400 B) 22500 C) 6500 D) 3300 ✔ A The normal acetylene and oxygen pressures for cutting steel plates are ________ and _________ kPa respectively A) 20 280 B) 10 150 C) 8 100 D) 35 425 ✔ A When a reciprocating pump discharges while it's piston or plunger moves in only One Direction it is termed a A) uniflow unit B) single acting unit C) dynamic unit D) double acting unit E) duplex unit ✔ B What kind of pump would be used to transfer large amounts of liquid A) centrifugal B) a rotary a C) reciprocating D) a sliding vain E) a turbine ✔ A Turbine pumps are best suited for A) low volume service B) high pressure service C) high volume service D) low pressure service C) used in low pressure service D) rejected ✔ D The type of pipe flange gasket not in normal use today is the A) full face B) ring joint C) flat ring D) graphite ✔ D Gaskets are used in pipe flange joints to A) prevent leakage because of small imperfections in the flange face B) allow for pipe expansion between each flanged joint C) make up for the misalignment of the pipe D) provide cushioning in the event of water hammer ✔ A A good rule of thumb to use for the spacing of pipe supports in a piping system is every A) 10 m B) 7.5 m C) 5 m D) 3 m ✔ D The kind of valve that has minimum wire drawing and seat erosion is the A) ball valve B) globe valve C) check valve D) gate valve ✔ B To ensure safe and continuous operation of a pressure reducing valve the valve station should have A) a safety valve on the downstream side B) a bypass loop downstream safety valve and a downstream pressure gauge C) the piping to the station made of at least schedule 80 piping D) a Y strainer immediately after the valve ✔ B What is the maximum temperature for which a non-special alloy steel valve can be used A) 343°C B) 425°C C) 925°C D) 650°C ✔ D Pressure and or temperature rating of a fitting is known as the A) material designation B) identification of the type of construction material C) type of appliance that can be attached to the fitting D) service designation ✔ D The basic type of ball valve requires a _____ turn from the fully open to the fully closed A) half B) quarter C) full D) 3/4 ✔ B Butterfly valves have which of the following advantages A) relatively light weight B) self cleaning C) negligible pressure drop across the valve when fully open D) all of the above ✔ D Relative to lubrication one place where wear is beneficial is A) new Babbitt bearing services which wear smooth B) on pump wear rings C) on the oil pump ceiling surfaces D) on the cylinder walls of internal combustion engines E) in anti-friction bearings ✔ A Grease is not a suitable lubricant A) if the atmosphere contains a lot of moisture B) when the atmosphere is dusty C) if corrosion protection is desired during downtime D) in the food industry E) if a large amount of cooling is desired ✔ E If an oil's viscosity changes much with little temperature change it will have A) a low viscosity index B) a high pour point C) a high carbon residue D) a high viscosity index E) a low pour point ✔ A If you desire and oil to flow at a much lower temperature you would most likely add A) a viscosity index improver B) pour point depressants C) a dispersant D) a thickening agent E) low viscosity oil ✔ B High capacity steam turbine oil's should A) have a low specific heat B) have a very high viscosity C) be fire resistant D) have a low pour point E) mix well with water ✔ C List four properties that affect the type of lubricant that should be chosen for an application ✔ Nature of surfaces to be lubricated, load to be carried, speed of sliding surfaces, operating temperature And oil which has little change in viscosity as the temperature changes will have a _____ viscosity index ✔ High Describe a common method of determining viscosity of an oil ✔ A given quantity of oil is placed in a Saybolt viscosimeter at a controlled temperature. the time for the oil to pass through a standard small diameter tube is measured and this indicates viscosity in Saybolt seconds universal Compressed air tools tend to be A) heavier than equivalent electrical tools B) damaged by overloading C) hot after prolonged operation D) more expensive than electrical tools E) less safe than electrical tools in explosive atmospheres ✔ D In order to protect the driver a start stop air compressor should be equipped with A) an intercooler B) an automatic blowdown system C) safety heads D) pre-start automatic unloading E) manual cylinder bleed Petcocks ✔ D vapour has to be higher than that of the cooling medium therefore the pressure of the vapour has to be such that it's condensing temperature is 15 to 20°C higher than the temperature of the cooling medium Describe the purpose of the economizer in a refrigeration system ✔ There are two main purposes of an economizer wine is that it increases the capacity of a system of a given size and second it reduces the power consumption required to compress the paper as the vapour from the economizer provides intercooling between the two compressor stages Refrigerant condensers ✔ Cool the gas refrigerant discharged from the compressor and condenser the vapour to a liquid What is the term used to describe the device used on a centrifugal chiller to improve efficiency and provide an inter-cooling affect ✔ Economizer Another name for direct refrigeration system is ✔ Direct expansion system What is the refrigerant in a lithium bromide system ✔ Water Why are ammonia refrigeration systems not used in air conditioning applications? ✔ Due to the toxic properties of ammonia Most lithium bromide absorption systems are put in place where there is cheap excess heat or waste heat available. What is this heat primarily used for? ✔ To evaporate the water out of the weak lithium bromide An absorption system requires less cooling water than a compression system? T or F ✔ False An absorption system requires more equipment and piping than a compression system? T or F ✔ True Which compressor type requires the use of a shaft seal? ✔ Open type In a rotating vane rotary compressor, a good seal is maintained between the vanes and the cylinder by ✔ Centrifugal force Describe the function of a safety head in a reciprocating compressor ✔ It is possible that under certain conditions liquid refrigerant may enter the compressor through the suction. To prevent damage to the compressor by the hydraulic pressure resulting from trapped liquid at the end of the compression stroke, compressors are often fitted with a safety head. This head is kept firmly in place by a heavy spring during normal operation, but the entire head will lift when the pressure in the cylinder becomes too high, due to liquid refrigerant in the cylinder. This allows the liquid to pass into the discharge line without doing any damage. Describe the operation of a rotating sliding cane compressor ✔ The rotating cane compressor consists of a cylindrical rotor having radial slots into which sliding vanes fit. The rotor is mounted eccentrically in the cylinder so that it nearly touches the wall between suction and discharge ports. During operation, the vanes move back and forth in the slots of the rotating rotor when they follow the contour of the cylinder wall, but the edges are held firmly against the wall due to centrifugal force so that a good seal is maintained. The refrigerant vapour is drawn in through suction slots or ports in the cylinder wall in the section of the cylinder where there volume of the space between the vanes, rotor and wall is increasing. This vapour is trapped between the vanes and pushed toward the section with decreasing volume. As a result, the vapour is compressed. This compressed vapour is forced into the discharge line via discharge ports in the cylinder walls and a reed or check valve. Describe what problems will be caused by leaking valves on refrigeration compressors. ✔ Leaking valves allow some of the hot compressed vapour to flow back from the discharge line into the compressor or from the compressor back into the suction line. This will result in reduced output of the compressor and thus the capacity of the refrigeration system. It will also cause the compressor to operate at higher then usual temperature, which could result in compressor damage if the faulty valves are not repaired in time. Large ammonia refrigeration compressors commonly use a packing gland to seal between the crank shaft and casing. Explain how this gland is lubricated. ✔ A lantern ring is placed between the two sets of packing. Lubrication oil is pumped to this ring, which distributes the oil between the rotating shaft and the packing. Describe the operation of a centrifugal compressor ✔ The centrifugal compressor consists essentially of a bladed wheel or impeller, which rotates at high speed. The impeller is surrounded by a volute shaped casing, and in many cases, by a ring of diffuser vanes in addition to the casing. The refrigerant vapour from the suction line is drawn into the centre or eye of the impeller. From there the vapour is forced radially outwards to the impeller periphery by the action of centrifugal fore due to the rapidly rotating impeller. The vapour leaves the impeller at high velocity, and then flows through the nozzle-shaped channels (diffusers) where some of the velocity is converted into pressure. Then the vapour passed through the volute casing where a further conversion of velocity into pressure takes place. Write down the formula that is used to determine the piston displacement of a refrigeration compressor and explain the meaning of each term. ✔ V = A * L * N * R V = volume in m^3/min A = cross sectional area of cylinder in m^2 L = length of stroke in m N = number of cylinders R = revolutions per minute What type of evaporator contains only a small amount of liquid refrigerant at any given time? ✔ Dry or expansion What kind of an evaporator can be easily cleaned and defrosted manually without interrupting the cooling process ✔ Plate surface Which type of condenser users the least amount of cooling water? ✔ Evaporative The purpose of a condenser in a refrigeration system is to? ✔ To remove the latent heat from the refrigerant What are two disadvantages of flooded evaporators ✔ Require more refrigerant, require more space What are two methods of reducing liquid carryover with flooded shell and tube evaporators? ✔ Mist eliminators, surge drums Natural draft cooling towers operate most effectively in large open spaces and ✔ Where wind is relatively constant A bypass valve, which prevents water flow over the fill of a tower during cold weather, should not be closed until the water temperature reaches ✔ 27°C Scaling is not as severe in towers when compared to boilers because ✔ Temperatures are not as high List four factors that affect the rate of heat transfer in a Cooling tower ✔ Relative velocity of both the air and water during contact Area of water surface in contact with air Length of contact time between air and water Difference between inlet water temperature and inlet air wet bulb temperature (relative humidity of air) A pressure-actuated control can be used together with an automatic expansion valve. T or F ✔ False The high-pressure cutout switch must be situated after the first stop valve. T or F ✔ False The chilling coil in an automatic purger has a primary function of ✔ Separating refrigerant vapour from the noncondensable gases to be purged High head pressure in a refrigerating system usually indicates ✔ Air or non condensable gases in the system A sulphur candle is used to test for ✔ Ammonia leaks What can cause a high discharge pressure in refrigeration systems ✔ And overcharged system, noncondensable gases Two devices used to detect leaks in a Freon refrigeration system, besides soap solutions are ✔ Halide torch and electronic leak detector What two checks can be used to determine if charging of a refrigeration system is complete ✔ Recommended weight from the manufacturer and sight glass on the receiver To avoid liquid slugging in a direct expansion evaporator after shutting down a reciprocating or rotary compressor refrigerating system which of the following measures needs to be taken? A) pump down the compressor B) fill the compressor with liquid refrigerant C) fill the evaporator with refrigerant vapour D) open all the suction valves on the connecting condenser line E) discharge all the condenser refrigerant into the evaporator ✔ A Checking the condition of electrical starters and contactors is categorized under what maintenance schedule ✔ Annual Checking the operation of the compressor lube oil pump, as well as the cooling coil, heater and oil reservoir level is ✔ Weekly maintenance List ten benefits that are realized by implementation of a preventative maintenance system in a refrigeration plant ✔ -more dependable service from the equipment -increased operating efficiency and a reduction in energy consumption -elimination or reduction of major breakdown repairs -reduction of overall maintenance costs -efficient scheduling of maintenance operations -reduces spare parts inventory required -control of labour and material costs -better mean of identifying causes of breakdowns -extended life expectancy of plant and equipment -accumulation of history records for each piece of equipment Concentration of the lithium bromide can be most easily controlled by what means ✔ Controlling the temperature in the generator During seasonal start up when should the purge pump be started ✔ 30 minutes after the start-up Explain why crystallization in a lithium bromide absorption refrigeration system is undesirable ✔ It can block piping, it can block passages, it can restrict flow Describe the steps that are taken to add octyl alcohol wetting agent to a lithium bromide system ✔ Connect a charging tube to the access valve located in top of the concentrator sump. Raise the open end of the tube and fill it with distilled water to remove all the air. Place the open end of the tube in a flask containing the recommended amount of alcohol. With the unit in operation slowly open the access valve allowing the alcohol to be drawn into the system quickly close the valve the instant that the last of the alcohol leaves the flask The temperature of the concentrated solution in a lithium bromide absorption refrigeration system may drop after the unit is shut down for an extended period. Explain how crystallization is avoided during this time. ✔ During the shutdown of the unit there is a dilution step where the dilute and concentrated solution are mixed together to produce and intermediate solution which will not crystallize as the temperature drops while the unit is shut down Air is approximately what composition by volume? ✔ 79% nitrogen 21% oxygen The volume of standard air is ✔ 0.833 kg/m^3 of dry air The difference between the wet and dry bulb readings is called the ✔ wet-bulb depression The term __________ applies to the percentage of moisture in the air as compared to the amount of moisture that the air can hold at a specific temperature ✔ Relative humidity The values of standard temperature and pressure of air that are used for evaluating air handling equipment are ✔ 1 kg of dry air at 21°C and 101 kPa abs The body needs considerable time to adjust when moving from one space to another when temperature and humidity conditions vary widely. This may be described as a) shock effect b) comfort zone c) comfort condition d) effective temperature e) air/motion effect ✔ A Which of the following statements about effective temperature is true? A) it can be easily determined by using a thermometer B) relative humidity does not affect the relative temperature C) for each combination air velocity remains the same D) the test involved people all dressed in different amounts of clothing for each combination E) charts with metric units cannot be used for making adjustments in SI units ✔ C Effective temperature can be defined as a measure of comfort which involves the combined effects of the dry bulb temperature relative humidity and site movement. T or F ✔ True Which of the following is not a centrifugal fan? A) backward inclined fan wheel B) forward curved fan wheel C) the propeller fan D) radial blade fan E) backward inclined airfoil blade fan ✔ C Centrifugal fans are classified as ✔ Backward inclined, straight, backward inclined with airfoil blades, forward curved Control of the static pressure and horsepower requirements at a given speed is obtained by using The purpose of the flow switch or sail switch used with hot water coils is to ✔ Close the outside air dampers and stop the fan if the flow of water is interrupted due to pump failure or closing of the hand valve Which steam trap is preferred for use with steam coils operating at low and medium steam temperatures ✔ Float and thermostatic trap The inverted bucket trap is used when the steam pressure is ✔ Higher than 172 kPa A modulating valve can be used for a steam coil when the air inlet temperature is below 1.5 C? T or F ✔ False To offset the heat gain through the buildings exterior shell from solar radiation, the atmosphere surrounding the building and internal sources of heat what is required? ✔ A cooling system When a system draws in only room air, conditions it, and then returns it into the room, it is called ✔ Full recirculation The unitary air conditioning system which used a direct expansion refrigeration system to provide cooling and dehumidification in a local area without ductwork is called ✔ Window air conditioner Which of the following statements about multi zone systems is true? A) the cooling coils are installed in line B) the dampers are our of phase by ten degrees C) when the hot deck is fully opened the cold deck is fully closed D) the system can not operate a humidifier E) all of the above ✔ C The supply temperature of the cold deck air in a dual duct system is 12.5 C? T or F ✔ True A system used extensively in hotels and motels due to its minimal space requirement, relatively low initial cost, and high degree of individual zone control is called a) a hydronic heat pump system b) an induction system c) a variable volume system with perimeter heating d) a fan coil unit with make up air system e) a compartmental atomizing system ✔ D The funds available for the air conditioning portion of the building refers to which factor of system selection? a) Building function b) Capital cost c) Building layout d) Operating costs e) Maintenance requirements ✔ B Which system provides the best control for room conditions on a year round basis? ✔ Four pipe arrangement The recovery system which has a capillary wick structure consisting of fine circumferential striations machined on its external surface is called a a) heat valve b) runaround system c) heat pump d) thermal wheel e) heat pipe ✔ E What is the maximum capacity of a heat pipe? ✔ When the evaporator is lowered below the horizontal The C.O.P. Of a heat pump increases as the outside air temperature drops? T or F ✔ False To provide a two position damper equipped with a fan that provides 100% outdoor air with a ratio of damper opening what is required? ✔ A gradual switch In severely cold weather what adjustment must be made to properly preheat the outside air? a) The temperature controller's throttling range must be increased b) The outdoor damper should be closed c) Two separate preheater coils should be installed d) Damper must be heated e) Preheat coil temperature should be increased ✔ C Air conditioning with respect to heating coils is achieved in which of the following ways? A) a combination of tempering control functions B) the selected mixing of warm return air and cooler outside air C) selective heating by passing air through the heating coils D) proportioning the amount of air flow through the face damper for heat addition or through the bypass dampers for no heat addition E) all of the above ✔ E To prevent too frequent starting and stopping of the compressor in a cooling system what should be done? ✔ Run the compressor continuously and modulate refrigerant flow To control static pressure in the air ducts a differential pressure controller is installed. How does the controller control static pressure? ✔ Modulating fan inlet dampers In order to convert 1 pound of saturated NH3 liquid to saturated NH3 gas, approximately how much heat must be absorbed into the liquid at SAT conditions ✔ 561 BTU's A refrigerant line contains ammonia at the following conditions 80 F 120 psig ✔ The line contains vapour 100 C is ✔ 212 F Copper tubing is never used with ✔ Ammonia A compressor is properly matched with a drive motor on a system that works at a -10 F evaporating temperature. If the roof temperature is allowed to go up to 30 F and then is pulled back down to -10 F then ✔ The drive motor may pull more amps while pulling down. The compressor efficiency will drop while pulling down A king valve is ✔ A liquid line stop valve at the outlet of the high pressure liquid receiver Which compressor type is not a positive displacement compressor? ✔ Centrifugal A low temperature ammonia booster compressor normally operates with a discharge temperature at 120 F. The temperature discharge vapour suddenly drops to 80 F what is indicated? ✔ There is possibly liquid in the suction line What causes liquid slugging ✔ The compressor drawing in lubricating oil from the suction line, the compressor drawing in liquid ammonia from the suction line, a rapid lowering of suction pressure at the compressor, drawing in lubrication oil or ammonia What must the operating engineer do in the event of liquid slugging ✔ Shut of the compressor Where should you manually purge the non condensables from you system ✔ From the highest point of the condenser with the compressor shut off or the condenser isolated What is the principle advantage and disadvantage of ammonia as a refrigerant ✔ It is readily available but toxic What is the difference between a unit cooler and a blast freezer ✔ Unit coolers are not installed in freezers, air velocity, more tonnage of equipment per square foot During a hot gas defrost cycle ✔ High pressure gas from the compressor discharge is piped through the evaporator What is the tax gas/flash gas in operating an ammonia refrigeration system ✔ 15% Compressors are sized based on what requirement ✔ CFM requirement What is fluid friction or vapour resistance ✔ The loss of pressure as the fluid/vapour interacts with the inner walls of the pipe In a DX or dry expansion coil evaporator the refrigerant should leave ______ ✔ In a superheated vapour state In a recirculation system where is it important to keep a constant pump pressure? ✔ At the metering valve evaporation inlet Which evaporator has the least amount of fins spaced per inch for the operational duties it performs? ✔ A blast freezer evaporator What does the compressor do? ✔ Moves refrigerant from the low side to the high side and controls temperatures What does the expansion device do? ✔ Controls flow What does the condenser do? ✔ Rejects heat from the system What does the evaporator do? ✔ Absorbs heat into the system.