MN Boiler Exam Study Guide: Questions & Answers: Updated Solution

What does a low Pressure gas system do? (Ans- Reduce gas pressure to 0 psi or atmospheric pressure What is the advantage of having a duplex strainer? (Ans- allows you to continue to operate while servicing off line basket What should you do if carbon deposits appear on rear wall of fire box? (Ans- Try wider angle burner Flue gas analyzer (Ans- Measures % CO2 and CO Orsat apparatus (Ans- analyzes combustion gases What is the effect of CO2 in flue gases? (Ans- if CO2 in flue gases goes up, the stack gas temp will also go up When is the explosion hazard greatest? (Ans- when operating at low load and start up What is the best indication of efficiency? (Ans- Temp of exhaust gases Electrostatic Precipitators (ESP) (Ans- remove dust particles in exhause Globe valve (Ans- Fluid flows through globe valve changes direction several times causing resistance to fluid flow and pressure drop Pressure Reducing Valve (PRV) (Ans- converts high or fluctuating inlet pressure to a lower and constant outlet pressure Relief Valves (Ans- Relieve T and P or P only. T and P on water heaters, P relief on hot water boilers. 4 subsystems necessary for plant to run (Ans- steam, feed, fuel, and draft Open Feed water heater (Ans- vented to atmosphere. Steam and condensate in direct contact, located on suction side of feed pump. Provides positive suction head for feed pump. Air and non condensable gases leave through atm. vent. Deaerator is an open feed water heater Closed feed water heater (Ans- usually a shell and tube heat exchanger operates at feed line pressure. located on discharge side of feed pump Centrifugal (Ans- Most common type of pump in plant What is the most common cause of boiler failure (Ans- low water