Mechanical Circulation

Mechanical circulation can be accomplished internally by plug fans (usually in the roof) with the driving motor outside the furnace and a drive shaft extending through the roof to an axial set of blades within the furnace. Materials limitations restrict this method to rather low temperature furnaces. 

External means of mechanical circulation are induced draft fans and forced draft fans. Neither can do as thorough a job of in-furnace circulation as well-planned and strategically placed burner jets, but these draft fans or blowers do assist in overall transport or movement of gases out of and into a furnace. Induced draft fans have their inlet connected to the furnace, and fherefore create a suction or negative pressure forced draft fans and blowers have their outlet connected to the furnace, and therefore create a positive pressure. Large power boilers often have both induced and forced 

Draft can refer to a chilling breeze on grandma, a pulling force as with a team of draft horses, the depth of a ship, a weather pattern involved with local atmospheric pressure, and (in this book) the difference in pressure that moves air and poc through a furnace. These all seem slightly related. . . except, draft beer  

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In dipping generally, but particularly with the anode process, it is desirable to use tanks that circulate the coagulant and latex compound, particularly the latter. Use of circulation keeps the Hquid surface clean and free from lumps, scum, or bubbles. Mechanical circulation can cause mbber particle instabihty, however, and eventually coagulate the compound. Therefore, tanks should be designed to minimize friction or shear action, and the compound stabilized to maintain mechanical stabiUty. 

Figtree G, Webb C, Collins P (1999) Raloxifene acutely relaxes rabbit coronary arteries in vitro by an estrogen receptor-dependent and nitric oxide-dependent mechanism. Circulation 100 1095-1101... 

D., Kilby, J.A., Will, M.L., Tester, D.J., Gong, Q., Zhou, Z., Ackerman, M.J. and January, C.T. (2006) Most LQT2 mutations reduce Kvll.l (hERG) current by a class 2 (trafficking-deficient) mechanism. Circulation, 113, 365—373. 

Kinnaird T, Stabile E, Burnett MS, Shou M, Lee CW, Barr S, Fuchs S, Epstein SE. Local delivery of marrow-derived stromal cells augments collateral perfusion through paracrine mechanisms. Circulation 2004 109 1543-1549. 

Task Force of the Working Group on Arrhythmias of the European Society of Cardiology. The Sicilian gambit. A new approach to the classification of antiarrhythmic drugs based on their actions on arrhythmogenic mechanisms. Circulation 1991 84 1831-51. 

Dhein S, Tudyka T, Schott M, Gottwald E, Miiller A, Klaus W A new antiarrhythmic peptide improves cellular coupling A possible new antiarrhythmic mechanism. Circulation 1995b 92(suppll) 641. 

Hydrofluoric acid settles very rapidly, and, therefore, small settlers are used only with those reactors which have mechanical circulation. Those units without circulation in the reactor require little or no settling. 

Young, M. E., McNulty, P., and Taegtmeyer, H. 2002. Adaptation and maladaptation of the heart in diabetes Part II potential mechanisms. Circulation 105 1861-1870. 

Fluidity of the massecuite An ammeter is used to measure the current used by the motor of a mechanical circulator changes in current indicate changes in the fluidity of the massecuite. 

Mechanical circulators are probably not usable as they require inter-coolers/heaters to achieve isothermal performance, and have a very limited pressure ratio. 

Freedman, J. E., Farhat, J. H., Loscalzo, J., and Keaney, J. F., Jr. (1996) alpha-tocopherol inhibits aggregation of human platelets by a protein kinase C-dependent mechanism. Circulation 94,2434-40. 

Clancy CE, Rudy Y. 2002. Na+ channel mutation that causes both brugada and long-QT syndrome phenotypes a simulation study of mechanism. Circulation 105 1208-13... 

Draft-Tube-Baffle (DTB) Evaporator-Crystallizer Because mechanical circulation greatly influences the level of nucleation within the crystallizer, a number of designs have been developed that... 

M. J. Kern, S. Puri, R. G. Bach, T. J. Donohue, P. Dupouy, E. A. Caracciolo, R. Craig, F. Aguirre, E. Aptecar, T. L. Wolford, C. J. Mechem and J.-L. Dubois-Rande, Abnormal coronary flow velocity reserve after coronary artery stenting in patients. Role of relative coronary reserve to assess potential mechanisms, Circulation 100, 2491-2498 (1999). 

These acid-catalyzed changes are brought about by passing hot gas oil vapors either through a mechanically circulated bed of the larger pellets or upward through a fluidized bed of more finely divided catalyst particles. The upflow of vapors provides the fluidizing action of the catalyst, hence the units are referred to as fluidized cat crackers or FCC units. To avoid loss of... 

Vyavahare N, Hirsch D, Lemer E, Baskin JZ, Schoen FJ, Bianco R, Kmth HS, Zand R, Levy RJ. Prevention of bioprosthetic heart valve calcification by ethanol preincubation efficacy and mechanisms. Circulation 1997 95 479-88. 

Bubbles in the reactor should be controlled properly because the high rate of the bubble formation results in the impediment of the contact between the electrode and electrolyte, which results in the effective area of the electrode being reduced and the resistances in electrol)des being increased. Mechanically circulating the electrolyte solution at a proper flow rate provides a possible means to reduce the resistance due to gas bubbles. 

In the high-pressure mode, the isolation cell is closed and the reactants are admitted to the reaction loop. The reactants are continuously pumped by a mechanical circulation pump, and flow through the reaction loop and repeatedly over the sample. The gas mixture is sampled and analyzed by the gas chromatograph. The sample can be heated resistively by a high-current ac power supply and its temperature monitored by a chromel-alumcl thermocouple. 

Weisz and Miale compared the activity for hexane cracking of a number of zeolites (Table 4.25) with a highly active silica — alumina (10% alumina). The zeolites are at least 10 times as active as amorphous silica —alumina. The catalytic process, however, cannot utilize the activity from a pure zeolite catalyst. The catalyst must be modified to decrease the acid-strength to avoid excessive formation of coke and low molecular weight gases, at the expense of gasoline. Moreover, the catalyst must be able to withstand the thermal and hydrothermal conditions experienced in regeneration. It must also withstand breakup in the mechanical circulation systems. A detailed description of the preparation of industrial catalysts is found in the literature. 

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