Sutro weir

Sutro weir dividers. A device often used for separating gravity reflux and distillate in continuous distillation systems is a Sutro weir divider. There are several variations, two of which (68) are shown in Fig. 19.4. It is suitable for small-scale systems and can eliminate the need for flow metering. Unlike the reflux splitter (below), it decouples... 

Figure 19.4 Common examples of Sutro weir reflux dividers. (Concept based on P. S. Buckley, W. L. Luyben, and J. P. Shunta, Design of Distillation Column Control Systems, Instrument Society of America, 1985.)...

A reflux splitter is difficult to incorporate in continuous distillation MB control schemes because it couples variations of the material balance stream (i.e., the distillate) with reflux rate changes. This is especially troublesome when reflux ratio is high, and a rise in distillate rate will effect a severalfold increase in reflux rate. The author experienced one case of poor continuous distillation control which was attributed to the above shortcoming. The author recommends restricting application of reflux splitters to batch distillation, where they work well. In continuous distillation, Sutro weir dividers are far more suitable. 

Mavis, F.T. (1949). Submerged thin-plate weirs. Engineering News-Record 143(Jul.7) 65-69. Soucek, E., Howe, H.E., Mavis, F.T. (1936). Sutro weir investigations furnish discharge coefficients. Engineering News-Record 117(Nov.l2) 679-680. 

Anonymous (1948). Pratt, Edmund A. Who s who in engineering 6 1582. Lewis New York. Anonymous (1952). E.A. Pratt, consulting engineer. Civil Engineering 22(7) 502. P Pratt, E.A. (1914). Another proportional-flow weir Sutro weir. Engineering News 72(14) 462-463 74(6) 277. 

Pratt, E.A. (1936). Sutro weir formula. Engineering News-Record 117(26) 904. 

Soucek, E., Howe, H.E., Mavis, F.T. (1936). Sutro weir investigations furnish discharge coefficients. Engineering News-Record 117(Nov.l2) 679-680 117(Dec.24) 904. Soucek, E. (1944). Meter measurements of discharge. Trans. ASCE 109 86-99 109 185-191. Soucek, E., Zelnick, E.W. (1945). Lock manifold experiments. Trans. ASCE 110 1357-1400. Soucek, E., Gau, J.N. (1967). Spillways and closures for the large earth dams on the Missouri River. 9 ICOLD Congress Istanbul Q33(R3) 29-55. 

Capen, C.H. (1943). History of Sutro weirs. Engineering News-Record 131(17) 585. 

Pratt, E.A. (1914). Another proportional-flow weir Sutro weir. Engineering News 72(14) 462-463. 

Select the flow-metering orifice to hold liquid head in the reflux line at Qn ax at the bottom of the pot with the Sutro weir. 

Control of gravity reflux flow rate by overflowing through Sutro weir and by throttling distillate flow... 

Gravity-flow reflux, surge tank with Sutro weir, tt > 3-5 minutes. Make sure the reflux line has a sufficiendy high hydraulic resistance. Note that tt is the hydraulic time constant of the surge tank with Sutro weir ... 

GravHy-flow reflux, surge tank with Sutro weir, tt > 3-5 minutes... 

A more positive approach is to measure internal reflux, not only to the column base, but also to each feed tray, and fi-om each tray where there is a side draw. A possible way to accomplish this is to design the downcomer bottom reservoir so that its outlet weir is a Sutro weir. The outflow from such... 

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