A Quiz on Boilers and HRSGs
[The answers to all of these questions can be found in the book. However,
email me for the list of answers or clarifications if required. My email is:
If boiler efficiency for a typical natural gas fired boiler is 83% on higher
heating value basis, what is it approximately on lower heating value basis?
a. 73% b. 83% c. 92%
If NOx in a natural gas fired boiler is 50 ppmv (3% oxygen dry), what is it
in lb=MM Btu (HHV) basis?
a. 0.06 b. 0.10 c. 0.20
1 in. WC of additional gas pressure drop in a 100,000 lb=h packaged boiler
is worth about how many kW of fan power consumption?
a. 5 b. 20 c. 50
If boiler water concentration in a boiler drum is 1000 ppm and steam purity
is 1 ppm, what is the percent steam quality?
a. 99.9 b. 99 c. 99.99
5. Boilers of the same capacity are located at different sites, whose ambient
conditions and elevation are as follows. Which case requires the biggest
a. 80F and sea level
b. 100F and 3000 ft
c. 10F and 7000 ft
Copyright © 2003 Marcel Dekker, Inc.
In a boiler plant if the conductivity of the condensate, makeup, and
feedwater are 800, 40, and 150 mmho=cm, respectively, what is the percent
condensate returns in the feedwater?
a. 5 b. 50 c. 15
7. A 20F change in exit gas temperature of an oil-fired boiler changes boiler
efficiency by approximately what percent?
a. 1 b. 0.5
8. Approximate air flow (acfm) required in a packaged boiler firing 100MM
Btu=h (HHV) of natural gas is:
a. 19,000 b. 30,000 c.12,000
9. The steam pressure drop in a boiler superheater is 50 psi when generating
600 psig, 650F steam. What is it likely to be at 400 psig, 600F with the
a. 70 b. 30 c. 50
10. Which is the worst case scenario for an economizer from the viewpoint of
sulfuric acid condensation? Assume that the oil-fired boiler flue gas
contains 12% water vapor and 0.03% SO2.
a. Flue gas at 680F and feedwater at 200F b. Flue gas at 320F and
feedwater at 275F.
If vol% of oxygen (dry) in a natural gas f