★Specialized Examination for Chemical Engineering ★ — One question per day (2015-12-7) — Points are awarded for participation
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This post was last edited by zshiwei2008 on 2015-12-8 08:39. Points system for the daily question: Participation – 1~3 points; Correct answer – 5 points; In-depth analysis – 5~10 points. The answer is provided the next day. Due to limited capabilities, I am unable to provide more in-depth explanations for each question; therefore, on the second day, in addition to offering reference options, I will also remove the restriction on reading replies. I hope that all candidates can learn from one another and improve together! Daily Question (2015-12-7): 1. To control the flow rate of the absorbent entering the absorption tower using a control valve and ensure efficient and stable operation, it is advisable to choose ( ). A. Closed centrifugal pump B. Reciprocating pump C. Vortex pump D. Open centrifugal pump 2. Use a standard cyclone separator to separate solid particles from dusty gas. As the processing volume increases, the size of the cyclone separator must be enlarged; if the inlet gas velocity remains unchanged, the critical particle size of the cyclone separator will ( ). A. Unchanged B. Increased C. Decreased D. Uncertain Answer: Question 1: A Question 2: B
A. Closed-loop centrifugal pumps use valves to regulate flow; therefore, positive displacement pumps are excluded first； Secondly, although the vortex pump is of the centrifugal type, it belongs to high-pressure pumps, so it is also excluded ； Pumps with open impellers have low efficiency and are suitable for transporting slurries or materials containing impurities; therefore, they are also excluded ； B. Increase
1. To control the flow rate of the absorbent entering the absorption tower using a control valve and ensure efficient and stable operation, it is advisable to choose (A). A. Closed centrifugal pump B. Reciprocating pump C. Vortex pump D. Open centrifugal pump 2. Use a standard cyclone separator to separate solid particles from dusty gas. As the processing volume increases, the size of the cyclone separator must be enlarged; if the inlet gas velocity remains unchanged, the critical particle size of the cyclone separator will (B). A. Unchanged B. Increase C. Decrease D. Uncertain
To control the flow rate of the absorbent entering the absorption tower using a control valve and ensure efficient and stable operation, it is advisable to choose (A). Solid particles in dust-laden gas are separated using a standard cyclone separator. As the processing volume increases, the size of the cyclone separator must be enlarged; if the inlet gas velocity remains unchanged, the critical particle size of the cyclone separator will (B).
1. Selection: A. Closed-loop centrifugal pump 2. Selection: C. Reduce
D and B. Reciprocating pumps are positive-displacement pumps; their flow is unstable, and they are generally not regulated using control valves but rather through bypass systems, changes in stroke, or adjustments to speed. Vortex pumps also do not use outlet valves for regulation – bypass systems are used instead – and they are suitable for applications requiring high pressure, low flow rates, and high viscosity ； Open-type centrifugal pumps are generally used for materials containing particles, right? ； Definition of critical particle size: d is proportional to the square root of B/u; therefore, as the size increases, the critical particle size also increases
1. To control the flow rate of the absorbent entering the absorption tower using a control valve and ensure efficient and stable operation, it is advisable to choose (A). A. Closed centrifugal pump B. Reciprocating pump C. Vortex pump D. Open centrifugal pump 2. Use a standard cyclone separator to separate solid particles from dusty gas. As the processing volume increases, the size of the cyclone separator must be enlarged; if the inlet gas velocity remains unchanged, the critical particle size of the cyclone separator will (C). A. Unchanged B. Increase C. Decrease D. Uncertain
To control the flow rate of the absorbent entering the absorption tower using a control valve and ensure efficient and stable operation, it is advisable to choose (A) for separating solid particles from dusty gases with a standard cyclone separator. As the processing volume increases, the size of the cyclone separator must be enlarged; if the inlet gas velocity remains unchanged, the critical particle size of the cyclone separator will ( B )