Scotch Marine Boiler Operation and Design, Exams of Engineering

Download Scotch Marine Boiler Operation and Design and more Exams Engineering in PDF only on Docsity! 3rd Stationary Engineer A B Test Exam With 100% Correct Answers 2024 AB 6. 3 types of heat transfer - Correct Answer-Radiant heat - Transmitted from hot body to a cold body by means of direct radiation Co A 7. What is a combustion chamber? - Correct Answer-The area of the boiler where the complete burning of fuel occurs. B 8. What is an internally fired boiler and 4 types - Correct Answer-Internally fired boilers have the grates and combustion chamber enclosed within the boiler shell. Scotch Marine Vertical Fire Tube Locomotive Cast Iron Package B 13. Name 2 ways to support and take care of expansion in a HRT boiler. Which way is best? - Correct Answer-It can be set on saddles equipped with rollers to permit movement of the boiler as it expands and contracts. It may also be suspended from hangers and supported by overhead beams. Hanging by beams is best, puts no hardship on furnace walls. B 14. What is a longitudinal Joint? What is a circumfermential joint? - Correct Answer-A longitudinal joint is a seam running the length of the shell and it is butt strapped or fusion welded. It is above the fire line to avoid overheating. Lap joint running the circumference of the drum. B 17.Describe a scotch marine boiler and how its fired - Correct Answer-It is an internally fired self contained horizontal return fire boiler. It is a cylindrical shell containing the combustion chamber and tubes that are surrounded by water. B 19. Describe the circulation of water within a Stirling boiler. - Correct Answer-feed water enters the top rear drum, passes down the rear tubes to the mud drum. steam and boiler water go up the front and center tubes to the front and center drums. CIRCULATING TUBES allow boiler water to pass between the drums. what does not go out as steam, goes back down the rear tubes. BUTT-STRAP JOINT = when two ends of the plate meet end to end and are joined by a plate. (one plate is a single butt strap joint / two plates are a double butt strap joint) B 39. What type of stays are used in the heads of water tub boilers and why? - Correct Answer-There are no stays. The head of the boiler drum is shaped with a die, which dishes and forms them into the shape they would take as a result of the pressure to which they will be subjected to. A 40. Why is a row of tubes sometimes left out of an HRT boiler? - Correct Answer-To improve carryover which will reduce carryover AB 41. In a fire tube boiler how are tubes secured in a tube sheet and why? In a water tube? In a water tube boiler why are only some tube ends beaded? - Correct Answer-Fire tube boiler tubes are rolled and beaded to prevent heat damage, and to keep them from pulling out. Water tube boilers are rolled then flared to keep them from pulling out. Also for drainage in the upper drum and prevent air pockets in the lower drum. B 42.Is it necessary to brace or stay a flat surface - Correct Answer-Yes to overcome the force on heads and flat surfaces. Where there are no tubes or braces, stays must be provided to prevent bulging of the boilerplate. Types: "T", "J", "Y" Stays B 43. Describe a through stay. Why are hollow stay bolts used on water legs? - Correct Answer-Through stay - Runs from one tube sheet to the other or from one flat surface to another. If a stay bolt fails a leak will develop and will be detected at once. B 44. Describe a diagonal and gusset stay. Where would each be used? - Correct Answer-Diagonal stay - Made of flat material similar to the boiler shell and is attached directly to the boiler shell and head or tube sheet. Gusset stay - Consists of a boiler plate riveted to the shell and head or tube sheet by means of angle iron. They are more rigid. Both are used to brace right angle surfaces A 46. What is thermal efficiency and what is considered a good percent? - Correct Answer-It is the ratio of heat supplied by the fuel to heat absorbed by the boiler.A good percentage is 85%, some boilers made today can reach 95%. A 47. How do you determine boiler capacity and what is boiler heating surfaces? - Correct Answer-Total heating surface determines the capacity of the boiler.Heating surface is any surface that has hot gases on one side and boiler water on the other and is measured from the fire side. B 49. What is superheated steam. Does its temperature rise"? - Correct Answer-Steam that has been heated to a higher temperature without raising pressure. Yes its temperature rises AB 53. Define primary air, secondary air and excess air. Is secondary air necessary in a boiler and why? - Correct Answer- Primary air - enters the furnace with fuel and determines rate of combustion Secondary air - creates turbulence around fuel to complete the burning process. It is necessary to combustion. B 73. What are some of the difficulties you may encounter when operating an oil fired plant?If firing #4 oil and you loose pressure, what is the first two things you would look for? When would you change a strainer? - Correct Answer- Difficulties may include: plugged strainer, improper venting of the tank, failure of the pumps, sludge, air in suction lines, vapor in the pump, oil to heavy to flow, insufficient heat, faulty atomization, low oil temperature, carbon formation worn burner tip, or low oil pressure.The first two things to look for are plugged strainer or pump failure.You would valve over to a clean strainer if the delta-P was excessive. B 74. Name three types of nozzles used in oil burners.Explain where secondary air is admitted. - Correct Answer-Rotary atomizing, steam atomizing, air atomizing, and pressure atomizing.Secondary air is admitted around the tip. B 75. Under what conditions must fuel oil be heated, how is it heated, and how hot is heated? - Correct Answer-#4, #5, #6 oils need to be heated.Heated using steam or electricity.oil should not be heated to more than 10°F below its flash point.#4 = 135° F, #5 = 185° F, #6 = 220° F A 80. Name five electrical devices used on a boiler. - Correct Answer-Low water alarm. Induced or forced draft fans, oil pumps. flame controls. damper motors. flow switch. water level control lights.CC TV cameras AB 81. What is natural draft? What causes natural draft? - Correct Answer-When the weight of the warm air in the stack is less than the cool air around the stack it causes an upward flow pulling air through the furnace.The heavier, cool air outside the stack gives a push to the warm lighter air in the stack causing air to flow through the furnace. B 82. How is the flow of natural draft controlled? - Correct Answer-By dampers mounted in the breeching and/or the burner operated by automatic controls either electric or pneumatic. A 84. How is draft measured? What is draft gauge used for and how is it installed? - Correct Answer-In inches of water with a manometer or a "U" gauge.A draft gauge is used to measure the pressure difference of the boiler room and inside the the setting or firebox.One tube is connected into the breeching and the other end is open to the boiler room (or atmosphere). Pressure moves the liquids in the tube. The difference is read in tenths of an inch. B 85. When would you employ forced draft? - Correct Answer- When you fail to have sufficient natural draft through the boiler. AB 86. What is mechanical draft? Name and describe three types. - Correct Answer-The adding of fans to make up for insufficient natural draft. Induced-is a fan in the breeching between the boiler and the stack pulling air through the furnace. The boiler operates below atmospheric pressure. Forced-is a fan at the point of air entry pushing air through the furnace. The boiler operates above atmospheric pressure. Balanced- is the addition of both forced and and induced fans, and the boiler operates slightly below atmospheric pressure at about .05 to .10 inches of water column. B 87. What is a pressurized furnace? And why is it not desirable on large boilers? - Correct Answer-A pressurized furnace has a fan the point of air entry to maintain the furnace above atmospheric pressure pushing the products of combustion through the furnace and out the stack.Flue gasses can leak into the operating areas and become a health hazard. A 88. How do you control the dampers on a large fan from a remote location? - Correct Answer-The control panel sends a manual reset.Side note: The City of Omaha requires one to be a manual reset even if you have two cutoffs. If there is repair work done on the boiler there must be a manual reset added. A 103. What is the purpose of a high fire limit control on a boiler? What is a modulating control? - Correct Answer-It proves that the forced fan damper has fully opened prior to starting the pre-purge period to insure adequate purge air flow.It adjusts the firing rate of the burner to maintain the boiler steam pressure. B 106. Name two types of fusible plugs. - Correct Answer- Waterside and fireside. The name refers to the side it is installed in the boiler. B 107. What is a Bourdon tube? - Correct Answer-A Bourdon tube consists of a curved tube with an oval cross section. One end is attached to the frame and to the pressure connection. The other end is attached to a pointer by the means of a linkage and gears. As pressure is increased to the pressure connection the tube will tend to straighten out and its motion is transmitted to the pointer. A 110. Where is a steam gauge attached to the boiler? How do you properly mount a steam gauge to a boiler? - Correct Answer-It is mounted either on top of the water column or on the top of the steam drum. A gauge is mounted with a siphon tube, isolation valve and test connection. A 111. Name three types of feed water regulatory systems. - Correct Answer-1. On-off such as a float or a probe.2. Modulating such as a thermohydrolic or thermodynamic.3. Metering such as a two or three element. A 112. Why is boiler feed pump used on some boilers and not others? - Correct Answer-A pump is not needed if the operating pressure of the boiler is lower than city water pressure. AB 113. What is the most important valve on a boiler? - Correct Answer-The safety valve. AB 114.What is a safety valve and how does it operate? - Correct Answer-It is a device to expel all excess steam pressure from the boiler.The huddling chamber causes the valve to open full and quickly causing a definite drop in pressure before closing. A 121. How often is it recommended to test your safety valves manually and how often under pressure? - Correct Answer- Every 30 days manually and yearly under pressure. AB 125. What is a surface blow off, where is it employed and why is it used? - Correct Answer-A surface blow off is used to remove oil and contaminants from the surface of the boiler water.The take-off is located in the top 3-4" of boiler water.It controls the total dissolved solids (TDS). A 128. When is the best time to blow down a boiler? How long do you bottom blow down the boiler? What important safety procedure is observed when using a bottom blow down? - Correct Answer-During light loads because more sludge has settled to the bottom. For about 10 seconds depending on the size of the boiler. Once you have opened the valve do not take your hands of of it until you have closed it! A 129. Where is the blow-down pipe connected on an H.R.T. boiler? What type valves are used on the bottom blow down and in what order are they placed? How should you blow down a boiler using those valves? What size piping is used in the blow down line? - Correct Answer-• To the under side of the shell, at the rear of the boiler drum.• Two slow opening or AB 137. How can you tell if the soot blowing had any effect on the boiler? - Correct Answer-You will notice a decrease in stack temperature and draft. AB 138. Describe a globe valve and where is it most used most often. How do you pipe a globe valve? Name 6 places for a bypass. - Correct Answer-A globe valve consist of a plug or disc which is forced into a tapered hole called a seat. It can be plugged or damaged easily and has more resistance to flow there for it is not used as a steam trap valve. It is also used most for throttling such as in a bypass. So the supply comes in under the disk.Bypasses are common around strainers, pumps, PRVs, traps, header valves, check valves and control valves. AB 139. What is a gate valve and where is it used most often. - Correct Answer-A valve with a wedge shaped gate which is raised or lowered into a passageway. The wedge shape tightens against the sides of the slot when closed. It offers little resistance to flow when fully opened and should not be used to throttle. It is used most for isolating devices for repair or to shut off the flow to the boiler. A 141. Explain the letters SWP and WOG found on the side of the valve. - Correct Answer-Steam working pressure SWP is the maximum steam working pressure of the valve.Water, oil, or gas WOG is the maximum pressure under which the valve may be used with these fluids. B 144. What is a check valve? - Correct Answer-A valve that only allows flow in One Direction. A 146. What is a hydrostatic test and how often should be done on your boiler? - Correct Answer-It is a water pressure test used to check the boiler for leaks.Close, lock, and tag all valves and blank or remove all safeties. Fill the boiler completely with room temperature water, venting all the air. Inflate with water to 1 1/2 times the working pressure and call the inspector.This should be done on new boilers, after turbine cleaning the boiler tubes and anytime repairs are made to the pressure vessel. A 148. What are the Essential steps in putting a cold boiler online with other operating boilers? - Correct Answer-1) Blow down gauge, glass, and water column.2) check operation of the feed water valves and pumps.3) Open the vent on the boiler drum.4) Start the boiler on low manual fire.5) Test the flame scanner.6) Test the low water cut off.7) when the boiler pressure starts to build, close the vent.8) Open the equalizer line around the header valve to warn the header.9) Open header valve and non-return valve drains.10) when the header is hot, open the header valve and close the drain.11) when the boiler pressure is 80% of header pressure unscrew and wheel on the non-return valve and close the drain.12) When the boiler pressure equals header pressure control in automatic. B 150. What our bags, what causes them and can they be repaired?What are blisters, what causes them and can they be repaired? - Correct Answer-A bag is a bulge in a boiler tube, caused by overheating an area under the scale. Small bags can be heated and driven back into place.Blisters are separation of layers in the boiler steel, caused by a combination of imperfections in the boiler plate and overheating. Blisters must always be cut away and replaced. A 151. What is scale and what causes it? Why is it bad for the boiler? - Correct Answer-Scale is mineral solids in boiler water being deposited on heating surfaces. It is caused by high TDS (total dissolved solids) and improper treatment of boiler water.Scale forms an insulation layer the retards the flow of heat to the water and causes the metal to become over heated. A 165. Give three reasons to vent a boiler shell. What would happen if the boiler shell was not vented when it was drained? - Correct Answer-1) To let air out when filling the boiler with water.2) To break vacuum when draining the boiler.3) To evacuate air from the boiler on start up.The vacuum created in the boiler shell would cause leaks, a boiler implosion, siphon treatment chemicals into the boiler or cause someone to be scalded when they remove the manhole cover. B 168. How many ways are there to patch a boiler drum and shells? - Correct Answer-Bolting , riveting, and welding. A 169. Why are hot water systems more desirable than steam for heating buildings? Name two types of hot water boiler heating systems. - Correct Answer-Hot water heat is more consistent because water retains its heat as it circulates and steam looses its heat rapidly as it condenses.Natural circulation and forced circulation. A 170. What is a diverter fitting? - Correct Answer-A fitting that meters the water flow from the supply line to the individual heating units. B 171. Name four safety devices on a hot water boiler. - Correct Answer-1. Temperature pressure relief valve.2. Flow switches.3. High pressure cut off switch.4. High temperature aqua stat.5. Flame scanner.6. Low water cut off. A 172. In hot water heating systems, how often do you test the Temperature-pressure (safety) relief valve and how long is the valve held open? - Correct Answer-It is tested every 30 days of boiler operation or after any period of inactivity and once a year under pressure. The try lever is lifted wide open for a minimum of 5 to 10 seconds or until clean water comes out. B 173. What devices insure that a pump is running in a hot water system? - Correct Answer-A flow switch or differential switch. AB 174. What is an aqua stat? - Correct Answer-An aqua-stat is a temperature sensing device. On a heating system it is used to start and stop the burner, open a valve or start a fan. B 175.If you have an expansion tank on your system, where would it be located and where would the water level be in it? why don't all expansion tanks have sight glasses? - Correct Answer-It will usually be located near the top of the system with water level midway in the tank. The level will go up and down as the temperature and pressure changes.The tank may use a bladder or diaphragm eliminating the need for a sight glass. B 176. You have a water boiler and you discover the sight glass on the expansion (compression tank) was completely full and the system pressure was higher than normal. What will happen next and how will correct this? - Correct Answer-The relief valve will relieve excess pressure.I would isolate and drain the expansion (compression) tank. I would repair the leaks by tightening fittings and replacing the sight glass washers before refilling the tank. A 178. Explain how an injector works. - Correct Answer-It is a device designed to lift and force water into a boiler that is operating under pressure. It operates on the principle of steam expanding through a nozzle imparting its velocity energy to a mass of water. AB 179. How does a duplex pump work and what is lost motion? - Correct Answer-It is a steam driven, double acting, reciprocating pump with check valves on both sides of the pistons so liquid is is pumped no matter which way the piston A 188. Name two types of centrifugal pumps and describe their differences. - Correct Answer-Radial flow. A centrifugal pump in which pressure is developed by centrifugal force.Mixed flow. A centrifugal pump where the pressure is developed by both the centrifugal force and by the lift of the vanes of the impeller on the liquid.Axial flow. A centrifugal pump where the pressure is developed by the lifting action of the vanes of the impeller on the liquid. A 190. Name the parts of double suction centrifugal pump. - Correct Answer-Double inlet impeller, impeller rings, volute casing, casing rings, shaft, shaft sleeves, shaft bearings, grease seals, thrust bearing, bearing end covers, packing with stuffing boxes, or mechanical seals and "O" rings. A 191. What are the merits of a centrifugal pump? - Correct Answer-1) Few moving parts.2) Uniform flow.3) Easy to control.4) High capacities.5) Dependable long life. AB 193. What kind of packing is used on centrifugal pumps? Name three advantages of mechanical seals over packing. - Correct Answer-Soft metallic packing.Longer life.Easier to replace, no leakage, less energy used because of less friction, high temperature usage, high pressure usage. B 194. When operating a pump under 200 degrees F, what kind of seals do you use and will there be any leakage and why? - Correct Answer-Soft metallic packing or mechanical seals. Mechanical seals should not leak, but with soft packing there will be minimal leakage to cool and lubricate the packing and shaft. A 195. What problem do you look for when paralleling two centrifugal pumps? - Correct Answer-Make sure the pump capacities remain the same so one pump does not hog the load. B 196. What would you do if your B.F.W.P (boiler feed water pump) becomes steam bound? - Correct Answer-Cool the pump with a garden hose or maybe install a city water tap to the suction of the pump. Then find the cause. B 197. Is a check valve placed after a pump and why? - Correct Answer-YES, a check valve relieves the pump of start up pressure and prevents back pressure from injuring the pump by causing it to run backwards. B 201. How is a pump primed? Why is a pump primed? - Correct Answer-It can be primed with water from another source if the foot valve is tight by using an injector or with a vacuum pump. Always with the pump off. The air must be evacuated from the pump suction before the water will fill the pump. B 208. What are the advantages of a feed water heater? - Correct Answer-It will lessen the thermal shock damage to the boiler, it will save BTUs, and it can remove free oxygen. B 209. What is a closed feedwater heater? What are the advantages and disadvantages? - Correct Answer-It is a heater in which feed-water and steam are in separate compartments or spaces. The heat is transferred through a metal wall from the steam too the water. Advantages- It heats feed-water to within a few degrees of the steam temperature. Disadvantages- It does not remove air from feed-water and is easily fouled. fill the system and water hammer will occur. If open, steam will fill the condensate lines and pressurize the condensate receiver. It will waste steam. A 224. List six places where steam traps should be installed. - Correct Answer-After steam radiators, after heat exchangers, on drip legs along steam lines, low points in steam lines, before pressure reduction valves (PRVs), before automatic valves, on steam headers, etc.Anywhere there is large amount of condensate. A 225. How often should steam traps be tested for proper operation and list five ways of testing them? - Correct Answer- Once per year using thermometers, listening devices, temperature crayons, flow indicators and test valves. B 227. List three things a vacuum return pump on a condensate system does. - Correct Answer-It pulls standing condensate back to the receiver, it vents air from the system, and it pushes condensate to the boiler or the boiler feed tank. A 228. What is a steam separator? - Correct Answer-In a cyclone steam separator, water and solids are thrown aside by centrifugal force and drain back to the boiler.A live steam separator uses corrugated baffles to collect moisture, which is drained off with a steam trap, complete reversal of the steam flow at the lower edge of the baffle separates the moisture from the steam. A 233. What is a boiler horsepower? - Correct Answer-It is 34.5 pounds of evaporation per hour from and at 212°F to dry and saturated steam at the same temperature. AB 234. How much does one cubic foot of water weigh and how much does one gallon of water weigh? - Correct Answer- Cubic foot = 62.5 lbs. at 62°FGallon = 8.3 lbs. at 62°F B 236. Define BTU. - Correct Answer-The quantity of heat required to raise the temperature of one pound of water one degree F. B 238. What is heat? What is latent heat? What is the latent heat of steam and ice? - Correct Answer-Heat is a form of energy. Latent heat causes a change of state but not a change of temperature. Latent heat of steam is 970 BTUs per lb. Latent heat of ice is 144 BTUs per lb. B 240. What are the three states of matter? Describe three conditions of steam. - Correct Answer-Solid, Liquid and Gas wet steam - contains droplets of water that have not yet been evaporated. Saturated steam - is saturated with heat. It contains no moisture. If heat were added it would raise its temperature. Super-heated steam - has a higher temperature than the boiling temperature corresponding to the boiler pressure. B 241. Explain the theory of electricity. - Correct Answer-The theory of electricity is the flowing of free electrons when electromotive force is applied across a conductor. A 242. What is current? What is electromotive force? - Correct Answer-Electric current is the flow of electrons. Electromotive force is an electric pressure that frees the electrons and causes them to move along a conductor. AB 245. Define volt. Define Ampere. - Correct Answer-A force of pressure which causes an electron flow of one ampere through a resistance of one ohm. One ampere of current is said to flow when one coulomb of electricity passes a given point in a conductor in one second. A 259. List four ways to safeguard electrical equipment. What is single phasing and give three reasons why a motor would single phase. - Correct Answer-With fuses, circuit breakers, verify electricity levels, confirm that supply circuits are grounded properly, and use a UPS/surge protector. For proper working of any 3 phase induction motor it must be connected to a 3 phase alternating current (ac) power supply of rated voltage and load. Once these three phase motors are started they will continue to run even if one of the three phase supply lines gets disconnected. The loss of current through one of these phase supply is described as single phasing. Single Phasing is usually caused when:-1) One of the three back up fuses blows (or fuse wire melts).2) One of the contactor for motor is open circuited.3) Single phasing might also be caused due to wrong setting of the protection devices provided on the motor.4) Contactors are coated due to oxidation hence not conducting.5) Relay contacts may be damage or broken. A 261. What is an alternator? What is a generator? What is the most common way to generate electricity? How do you protect a generator when shorted to ground? - Correct Answer-a. It is a synchronous generator that delivers alternating current of a frequency directly proportional to its rotating speed. b. A generator changes mechanical energy into electrical energy. c. Steam power plants using fossil fuels and steam turbines. d. Fuses, circuit breakers, and overloads. B 262. How are ball bearing motors lubricated? - Correct Answer-Remove the plugs and pump grease through the bearing until clean grease comes out. Run the motor for one hour, wipe excess grease and replace the plugs. A 264. What is the EPA? - Correct Answer-Environmental Protection Agency - is a federal agency set up to control and abate pollution in the areas of air, water, solid waste, pesticides, radiation, and toxic substances. A 265. Explain the NFPA hazard system. - Correct Answer- National Fire Protection Agency The colors and numbers indicate the hazard the degree of severity.1) Blue is health.2) Red is fire.3) Yellow is reactivity.4) White is properties and hazards of particular materials. A number indicates the degree of severity: 4 being severe hazard down to zero being no hazard. note: learn all of them B 268. Name three types of extinguishers and list what they are used for, how often do fire extinguishes need to be inspected and who inspects them? - Correct Answer-A type = paper and wood B type = oil and electrical ABC type = paper, wood, oil, and electrical Halon = electrical and computersC02 = oil and electrical Must be inspected once a year if not used, by a licensed inspector. B 271. If an electrical panel caught on fire in a boiler room, what are the first two things you would do? - Correct Answer- Cut power to the area, call 911 even if the fire is out. AB 273. What is a confined space? Name three. - Correct Answer-It is a space large enough to physically enter but has limited or restricted entry and exit and is not designed for continuous occupancy. Examples of confined spaces include silos, vats, hoppers, utility vaults, tanks, sewers, pipes, access shafts, truck or rail tank cars, aircraft wings, boilers, manholes, manure pits and storage bins. Ditches and trenches may also be a confined space when access or egress is limited. AB 274. What is on a right to know label? - Correct Answer- Physical and Health Hazards (MSDS)1) First aid procedures for exposures or contact.2) Personal protection required.3) Flammability.4) No smoking.5) Handling and storage instructions.6) The chemical or common name.