【Question 047】Boiler basic questions

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This post was last edited by zgj2405 on 2010-1-8 at 13:46. Please hide your replies; think carefully before posting, as edits are invalid! Those with different views on the provided answer keys can post discussions the next day. For multiple accounts under the same IP, only the first response indicating participation is valid. All participants receive 2 points as a reward. This round consists of multiple-choice questions, with 2 points for each question; an additional 5 points are given for getting all answers correct. For specific hiding methods, see: http://bbs.hcbbs.com/viewthread.php?tid=492556&highlight=%D2%FE%B2% 1. The reciprocal of the cycle multiplier is ( ). A. Circulating flow velocity B. Dryness degree of the steam-water mixture C. Limiting circulation ratio D. Fluidization velocity 2. If a free surface appears in vertically arranged water-cooled wall tubes, then ( ) occurs. A. Circulation stagnation B. Circulation backflow C. Vapor-liquid separation D. Steam in the downcomer 3. At a constant pressure increase rate, the mechanical stress generated in the drum during the early stage of pressure increase compared to the later stage is ( ). A. Larger in the early stage B. Larger in the later stage C. The same size D. None of A, B, or C 4. For ordinary coal-fired boilers that use coal with a high volatility content, it is necessary to reduce the temperature of the primary air and increase its flow rate; the purpose of this is to protect ( ). A. Economizer B. Superheater C. Burner D. Evaporation screen 5. As the equivalent diameter of the bed material increases, the critical flow rate ( ). A. Increase B. Decrease C. Remain unchanged D. Not necessarily