Reactor helical coil

The maximum rate of polymerization has been confirmed to occur at the laminar-turbulent flow transition. The rate of polymerization was observed to be maximum at the transition for both straight reactors as well as for the helically-coiled reactor for which the transition is at a Reynolds number higher than that of the straight tube. The helically coiled tubular reactor is of industrial interest since it is much more compact and, consequently, the cost and the temperature control problems are more tractable. 

It is noted that the maximum value of rp in the helically coiled reactor is larger than the maximum observed in the straight tube reactor. The rp increases with increasing Reynolds number while the molecular weight (at a given conversion) decreases. 

Serpentine geometry enhances the radial mixing better than the helically coiled reactors even at low flow rates... 

Sensitivity Analysis of Length-to-Diameter Ratio for the Helical Coil Reactor... 

Sawyers, D.R., Sen, M., and Chang, H.C. (1996) Effect of chaotic interfacial stretching on bimolecular chemical reaction in helical-coil reactors. Chem. Eng.J., 64, 129-139. 

A stirred reactor contains a batch of 700 kg reactants of specific heat 3.8 kJ/kg K initially at 290 K, which is heated by dry saturated steam at 170 kN/m2 fed to a helical coil. During the heating period the steam supply rate is constant at 0.1 kg/s and condensate leaves at the temperature of the steam. If heat losses arc neglected, calculate the true temperature of the reactants when a thermometer immersed in the material reads 360 K. The bulb of the thermometer is approximately cylindrical and is 100 mm long by 10 mm diameter with a water equivalent of 15 g, and the overall heat transfer coefficient to the thermometer is 300 W/m2 K. What would a thermometer with a similar bulb of half the length and half the heat capacity indicate under these conditions ... 

Figure 11. Hypothetical conversion as a function of Reynolds number in helically coiled tubular reactors...

It was found that the maximum rate of polymerization occurred at (NRe)e 5000. This shift in (NRe) corresponds to the shift of the laminar turbulent transition in a helically coiled tube as reported by White ( ). Further, no plugging of this reactor, under any conditions of operation, was noticed. The reaction mechanism appears to be very close to the Smith-Ewart model, although conversions were not always a3 complete as expected. 

Here in Chapter 1 we make the additional assumptions that the fluid has constant density, that the cross-sectional area of the tube is constant, and that the walls of the tube are impenetrable (i.e., no transpiration through the walls), but these assumptions are not required in the general definition of piston flow. In the general case, it is possible for u, temperature, and pressure to vary as a function of z. The axis of the tube need not be straight. Helically coiled tubes sometimes approximate piston flow more closely than straight tubes. Reactors with square or triangular cross sections are occasionally used. However, in most of this book, we will assume that PFRs are circular tubes of length L and constant radius R. 

For very long, helically coiled steam generator tubes, and for conditions typical of liquid-metal fast breeder reactors (LMFBRs), where steam is generated on the tube side, an overall heat transfer correlation for the whole boiling length (from X = 0 to X = 1.0) has been deduced experimentally (Campolunghi et al., 1977b) ... 

Tijssen, R. Axial dispersion and flow phenomena in helically coiled tubular reactors for flow analysis and chromatography. Anal. Chim. Acta 1980, 114, 71. 

The geometrical form of the tubing from which the FIA reactor is made has a distinct influence on the solute dispersion, as seen in Fig. 2.10. The reason is that helical coiling, or irregular knitting of the tubular conduit. 

R. Tijssen, Axial Dispersion and Flow Phenomena in Helically Coiled Tubular Reactors for Flow Analysis and Chromatography. Anal. Chim. Acta, 114 (1980) 71. 

The reactor cooling system is composed of the MCS, ACS and VCS as schematically shown in Fig. 1. The MCS is operated in normal operation condition to remove heat from the core and send it into the environment. The ACS and VCS have incorporated safety features. The ACS is initiated to operate in case of a reactor scram. Besides one out of two components of VCS has sufficient capacity to remove residual heat, the ACS is provided to cool down the core and core support structure. A helically coiled intermediate heat exchanger (IHX) whose heat-resistant material is Hastelloy-XR developed by the JAERI has been installed in S tember 1994. Nuclear heat application tests using the HTTR, are planned to be carried out, and accordingly a heat utilizaticxi system will be connected to the IHX. The fuel fabricaticm started in June 1995 and will complete in 1997. 

Solano, J.P., Herrero, R., Espin, S. et al. (2012) Numerical study of the flow pattern and heat transfer enhancement in oscillatory baffled reactors with helical coil inserts. Chemical Engineering Research and Design, 90,732-742. 

There is absolutely no information in the literature on the critical speed for complete dispersion of the gas phase, N, in stirred tank reactors fitted with helical coils. The only work reported so far is that of Nikhade (2006) in the 0.57 m diameter stirred tank reactor referred to earlier. The correlations obtained for the inCTease in and AN were (Nikhade and Pangarkar 2006)... 

The nuclear heat supply system generates heat in the reactor core and produces steam in the IHTS. The IHTS SG is composed of a helical coil counterflow heat exchanger, startup recirculation tank and pump, leak detection system, and isolation valves. Intermediate sodium flows on the shell side of the helical coil tubes, through which water flows to produce superheated steam. Two reactor SGs feed one turbine island to form a power block. 

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