Reading
- 1. 1. What elementsof the flue gas from a steam boiler are actually determined by an ORSAT apparatus? Carbon Dioxide, CO2 Carbon Monoxide, CO Oxygen, O2 Nitrogen, N2 2. Define Pumped Storage Hydro-Electric Plant Pumped Storage Hydro-Electric Plant is a supplementary hydroelectric plant in which water is pumped into an elevated storage during off-peak period, and this stored water will be used to run hydraulic turbine during peak period to be able to meet the peak load demand. 3. Coal is burned under boilers on strokers and in pulverized form: a. Name three (3) basic types of arrangement for burning pulverized coal in boiler furnaces. • Long-flame burner for vertical firing • Short-flame or turbulent burner for horizontal firing • Tangential burner for corner or tangential firing b. Make a simple sketch of each type to show flame direction in the furnace. c. Which of these basic types is used in Philippine coal thermal plants? The tangential burner is used in Philippine coal thermal plants d. What is the name of the apparatus for determining grindability of coal? Hardgrove apparatus is used for determining grindability of coal 4. Define the following: a. Dendro thermal power plant A steam power plant which uses wood, such as ipil-ipil, for fuel in boilers. b. Mini Hydro power plant A small hydro-electric plant operating under a head of 3 to 30 meters and over capacities of 100 to 5,000 KW.
- 2. 5. Define thefollowing terms relating to steam turbines a. Nominal rating The declared power capacity expected to the maximum load; the capacity indicated in the nameplate. b. Turbine capability The manufacturer’s guaranteed maximum continuous output for a clean turbine, operating under specific throttle and exhaust conditions, with full extraction at any openings, if provided. c. Willians line A straight line which indicates the relation between steam consumption and load of a steam turbine-generator unit. d. State-line or condition line A line in the Mollier diagram representing the steam condition at each stage of turbine and the final end point. e. Regenerative cycle A steam power cycle in which steam is extracted from the turbine and used for feedwater heating. 6. Name five possible causes for the failure of a newly installed centrifugal pump to start pumping. • Suction line not completely primed or impeller not completely submerged • Line leakage in pipe connections or pump gaskets • Insufficient pressure to reach the head because gate valve is opened too wide • Suction valve or discharge valve closed • Prime mover cannot develop full power due to low voltage or other causes 7. Make a sketch of a ratameter, give its function and explain its principle of operation. A rotameter is an instrument consisting of a vertical passage with variable cross-sectional area, a float and calibrated scale, used to measure the flow rate of fluids. The fluid is allowed to flow through the vertical passage with variable cross-sectional area and the force of the fluid will cause the float to rise. The height which the float will rise depends on the force of the fluid and therefore on the quantity of the flow.
- 3. 8. State seven(7) major causes of heat losses in steam generators and explain briefly how you could minimize these losses. • Loss due to moisture in coal. This can be minimized by properly drying the coal before firing or using only coal with low moisture content. • Loss due to moisture formed by combustion of hydrogen. This is an unavoidable loss, but being part of the exhaust loss, this can be utilized in heating economizers or air preheaters. • Loss due to heat carried away in dry chimney gas. This can be minimized by using right amount of excess air, using larger gas passages to avoid high velocity, and proper design of heat transfer surfaces so that most of the heat of the gases absorbed by the water. • Loss due to incomplete combustion. This can be minimized by using sufficient air supply by effective design of furnace and burning equipment. • Loss from radiation and convection from boiler and furnace. This can be minimized by using good quality of refractories and right thickness of furnace and also applying insulation to boiler piping and drums. • Loss due to moisture in the air. This can be minimized by avoiding the use of high excess air and avoiding possible water contamination of air used for combustion. 9. State the five (5) principal objectives for the design of central station steam generators and explain briefly as to how you could accomplish each basic objectives. • High efficiency. This can be accomplished by the use of auxiliary heat transfer devices like economizers, air preheaters, well insulated pipes and drums and well designed furnace and combustion equipment. • High availability of service. This can be attained by building the steam generator with sufficient capacity to meet the demand continuously. • Ability to deliver clean steam. The use of treated feed water and the use of steam purifiers can accomplish this objective. • Uniformity of superheat. This can be achieved by the use of efficient control devices such as temperature and pressure and fuel feed governors so as to deliver the superheated steam at the required temperature at any load. • Ability to accommodate variations in rate of steaming. Again, the use of control devices like water level control, fuel feed control can accomplish this objectively. 10.What is the National Pollution Control Commission and what power does it have over industrial plants? National Pollution Control Commission is a government agency whose basic policy is to maintain a reasonable standard of quality of both air and water resources for their legitimate use. It has the power to issue orders to industrial plants to stop discharging atmospheric effluents into neighboring streams, to summon factories to a public hearing and investigate factories for actual pollution cases.