I would like some help understanding a passage in English
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The following text is an excerpt from a patent: it describes the use of activated carbon to adsorb PCBs. But when it comes to the manufacturing process, my knowledge is limited, and I don’t understand the next sentence! Please ask an expert to help explain it! For a vessel made of 16-inch Schedule 40 steel pipes, 10 feet in length, filled with 322 pounds of dry adsorbent (activated carbon). Impure diphenyldichlorosilane (Ph2SiCl2), containing 2060 PPM of biphenyls, was pumped at a mass flow rate of 175 pounds per hour per square foot of the vessel’s cross-sectional area. The concentration of biphenyls in the stream as it left the vessel was monitored, with the following results: The image was extracted from the patent
This post was last edited by zhdw0906 on 2018-3-6 at 10:25. “In a 10-feet long, 16-inch diameter Schedule 40 steel container filled with 322 llbs of dry adsorbent (activated carbon), PH2SiCl12 containing 2060 ppm of biphenyl impurities was pumped in at a mass flow rate of 175 lbs/(hr·ft2); the concentration of biphenyl impurities is shown in the table below.” “The problem is that you haven’t understood the unit of traffic. The technical terms may not be entirely accurate.
I would like to ask an expert: What does 175 lbs/(hr·ft2) mean? Flow rate per hour*per square inch? Is flow rate related to cross-sectional area? And how should we interpret the data in the table at the back? Is it cumulative? If biphenyl is adsorbed, then the content of biphenyl in Ph2SiCl2 should decrease! I would appreciate your guidance!
This post was last edited by zhdw0906 on 2018-3-6 at 17:45. I’m not very familiar with this adsorption system; it seems to involve the use of activated carbon to adsorb certain impurities； Issue with flow unit: The unit of flow mentioned in the text is lbs/(h*ft2), which represents the flow rate per square foot of cross-sectional area; from a dimensional perspective, this corresponds to the unit of velocity. Thank you to @kid_ptd for correcting the term “lbs”. Regarding the unit of flow rate: it should be stated as “The unit of flow rate in the text is lbs/(h*ft2), which represents the mass in pounds that passes through each square foot of cross-section per hour”.
lbs is a unit of weight, not volume; therefore, lbs/(h*ft2) cannot be converted to m/s. The term in the original text should be understood as \"mass flow rate\", that is, mass flow divided by cross-sectional area. One can refer to the heat Q and heat flux q in the heat exchange process, with units of kW and kW/m2 respectively
After carefully reviewing the original text, I’d like to share some personal insights for the original poster’s reference. First of all, Φ2SiCl2 in the main text and O2SiCl2 in the table appear to be errors; it is likely that both refer to diphenyldichlorosilane, i.e., Ph2SiCl2. The left column in the table indicates the total pounds of Ph2SiCl2 in the emissions processed per pound of adsorbent used. An increase in this value means a higher processing volume; with constant flow rate and pipe diameter, this results in an extended residence time. The right column shows the PCB concentration (in ppm) of Ph2SiCl2 in all the emissions after treatment. An increase in this value as well. Overall, it can be said that when the amount of adsorbent remains constant, increasing the volume of pollutants to be treated causes the adsorbent to become gradually saturated, leading to an increase in the pollutant concentration in the final product. From another perspective, if the final product does not need to meet such a high standard of 2 ppm, it is possible to use a limited amount of adsorbent to process more pollutants