MN Boiler Exam Latest Questions & Answers.

MN Boiler Exam Latest Questions & Answers. Cast Iron Sectional Boiler Like Bread, sections in between are intermediate. Held together with push nipples and stay bolts. No special foundation required Expandable (can add more centers to increase heating capacity) Boiler trim mounted on end sections Disadvantage: Always low pressure Advantage: corrosion resistant Firetube boiler used for heating and process Gas/heat of combustion on one side and water on outside. Horizontal Return Tubular Type of firetube Drum supported by Lugs and Slings Old construction, not efficient because of External furnace 2 pass construction Bridgewall Baffle inside HRT boiler furnace to direct flow of combusting gases for greatest efficiency Scotch Marine Most common, most efficient Firetube boiler. Comes in 2, 3, or 4 pass construction Round tube furnace usually corrugated like culvert under road. Completely internal furnace Dry Back Scotch Marine easy to clean and maintain, less costly, less efficient Wet Back Scotch Marine hard to clean and service due to limited access, more efficient, more costly Fire Box almost like Scotch Marine but fire box instead of corrugated. Can burn oil, gas, or solid materials Locomotive Type of firetube used in trains. Variation of HRT, partially enclosed furnace Vertical Fire Tube Burner on bottom, could be on top in case of Fultons Types of Water Tube Boilers Straight Tube, Bent Tube, Flex tube, and Membrane tube Water Tube Boiler package boilers made in factory, add water/electric and ready to go. Process and power generation. Advantage of Water Tubes over Fire Tubes WTB contains less water for same horsepower output of FTB. Most of energy is contained in water not steam. Recovery rate is greater than fire tube because of less water. (Less energy to heat smaller mass) 3 Types of Industrial Water Tubes A, O, and D (most efficient, most common) Electric Boiler Electrode (spark plug) electrical arc or fusion, Resistance coil 1 boiler Horsepower =746 watts = 33,478.8 Btu output / hr =10 square feet of heating surface for conventional boiler =5 square ft of heating surface for steam coil generator =10 KW electric Boiler trim Valves and components directly attached to boiler necessary for it to run. (ex. water column, gauge glass vent, bottom blowdown, relief valve, steam safety valve) Boiler Accessories components necessary for boiler to run but NOT attached to boiler (Feed pump, fuel pump, condensate tank and pump, surge tank, Deaerator) Stays Support boiler in areas not supported by tubes. can be vertical, horizontal, and diagonal Boiler Pass where heat of combustion travels length of furnace or boiler tubes Baffle used in all boilers (fireside and waterside) to direct flow for greatest efficiency How is piping measured vs. boiler tubes piping is measured based on inside diameter, while boiler tubes are measured by outside diameter Dry Pipe Pipe running along the top of steam space in which slots are cut in top or side for purpose of admitting only dry steam to line. One has blank ending, other is connected to steam outlet. Drain holes drilled on bottom. What is the point of a dry pipe to aid in removal of moisture from steam as it leaves the steam drum what kind of stamp must a company posses to to weld on boilers R stamp ASME American Society of Mechanical Engineers According to ASME, how many valves must be on the main steam line of a high pressure steam boiler? 2. Jurisdiction ends after second. Longitudinal joint Joint subject to greatest stress Bottom Blowdown Valve removes sludge and sediment, drains boiler for maintenance, located on bottom of mud drum in WTB or bottom of boiler on Firetube Breeching exhaust pipe between boiler and chimney Hot Water SUPPLY Boiler water heater for domestic use Safety Relief Valve Prevents overpressure of water boiler. Spring loaded pop type, discharge capacity rated in Btu/hr. Must be hand tested quarterly in all boilers. Minimum size 3/4. Can be T&P or Pressure only How often does a Safety Relief Valve need to be tested Quarterly Minimum size for safety relief valve 3/4 Superheater increases steam temp but not pressure. allows for use of steam longer. Increases efficiency. exposes steam to combustion gases so it won't condense after first stage of steam turbine. Located in radiant outlet area of boiler Dry firing flow of steam is necessary to keep superheater from overheating and getting damaged Reheater increases steam temp for latter sections of steam turbine Economizer preheats feed water pre heater pre heats combustion air. Important in solid fuel burners. Why does heat transfer from hot to cold? Due to difference in temperature or density Law of conservation of mass Cannot be created or destroyed, only altered PSIG Gauge pressure PSIA Absolute pressure= gauge + 1 atm 1 Atm. 14.73 psia Celsius to Fahrenheit C= (F-32) / 1.8 Fahrenheit to Celsius F= (C *1.8) +32 Pyrometer Can be thermal electric or optical. Measures stack gas temperatures in breeching British Thermal Unit amt. of energy required to increase 1 lb of water by 1 degree Fahrenheit Sensible heat Heat you can sense, feel, measure Latent heat causes physical change in state or phase but no change in temperature How many Btu of latent heat does it take to change 1 lb water to steam? 970.4 Btu of latent heat Specific heat amount of heat energy required to increase the temperature of 1 lb of substance by 1 degree fahrenheit 3 types of heat transfer Conduction, convection, radiation Conduction Direct contact, no mix Convection mixing of 2 or more fluids to become 1 radiation electrical energy waves. Heats objects not air What must a heat transfer surface have? must have heat of combustion on one side and water or steam on the other 1 Horsepower as related to evaporation evaporation of 34.5 lbs of water per hour Why would superheated steam be preferred to wet steam? used to provide dry steam to turbines sensitive to wet steam. Can be used when high temperatures are needed. Allows more work to be done. Desuperheating brings down to lower temp. Atomization Air, steam, mechanical/pressure, rotary cup (constant capacity used in heavy oil burners) Draft Difference between inside furnace and outside air. Causes air to move. measured in inWater. 4 Types of draft Forced, Induced, Balanced, Natural Forced Draft pushes air into combustion chamber. Located at inlet side of burner Induced draft pulls or sucks air through furnace. Located in breeching Balanced Draft combination of forced and induced Natural draft always present. Controlled by height of chimney and temp. differential #2 oil Most common heating fuel, does not require pre heating for pumping or burning How many Btu/G does #2 oil have 141,000 Btu/G Gas Propane, butane, natural Natural Gas (NAG) no ash, already aerosol, easy mix with air, cleanest burning 1 therm 100,000 Btu 1 cubic foot