Coil Lengths

After the minimum inside diameter and the required wall thickness, a coil diameter and wall thickness may be selected. Very often, the coil length downstream of the choke (L2) is of a different diameter and wall thickness than the length upstream of the choke (L,). 

With the known temperatures on each end of the coil, the heat duty for each coil can be calculated from the heat transfer theoiy in Chapter 2. Since the bath is at a constant temperature, LMTD can be calculated as  

Nominal Pipe Size in. Nominal Wall Thickness in. Maximum Working Pressure Grade B S = 20,000 P 9 Maximum Working Pressure Grade C S = 23,300 psig 

The overall film coefficient, U, for the coil can be calculated or read from the charts and tables in Chapter 2. Since U, LMTD, q, and the diameter of the pipe are known, the length of the coil can be solved from the following equation  

For a given shell length the number of pas.ses for each coil can be determined. Since the number of passes both upstream and downstream of the choke must be an even integer, actual Tj and T2 may differ slightly from that assumed in the calculation. The actual values of Tj and T2 can be calculated from actual coil lengths L, and L2. 

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The inductance variation measure with a defect long than the coil length permit to calculate the defect surface. 

We can then observe ( figure 2 ) the excitation coil length influence towards the range of the signal when the probe is moved in the tube, depending of the excitation source mode ( current I, tension U or power P constant) ... 

In order to choose the coil length and diameter, a temperature must first be chosen upstream of the choke the higher Tj, the longer the coil L and the shorter the coil L2. In Chapter 2 we showed that the greater the LMTD between the gas and the bath temperature, the greater the heat transfer per unit area, that is, the greater the LMTD, the smaller the coil surface area needed for the same heat transfer. The bath temperature is constant, and the gas will be coldest downstream of the choke. Therefore, the shortest total coil length (L[ -I- L2) will occur when L is as small as possible (that is, Tj is as low as possible). 

Although the total coil length is always smaller when there is no upstream coil (Lj = 0), the temperature could be so low at the outlet of the choke under these conditions that hydrates will form quickly and will partially plug the choke. In addition, the steel temperature in the choke body may become so cold that special steels are required. Therefore, some guidelines are necessary to choose Tj for an economical design. 

Fire uihe area required and heater size (shell diameter, shell length, fire luhe rating, coil length and number of passes). 

Minimum coil length Minimum fire tube area Shell size... 

Using a 1000 psi flow restrictor coil (length of 0.007" i.d. tubing), again pump the water at ImL/min. After the flow has stabilized, record the high and low pressure points for a period of time (typically, 1 min). The high and low points should vary by less than a specified amount (e.g., <30 psi). 

The viscometer assembly is placed in the constant temperature column compartment of the chromatograph between the column outlet and the refractometer. A combination of two Waters Associates M-45 hydraulic filters in series with a capillary tubing coil (length 10 ft., I.D. 0.01 in.) is used to dampen the line pressure fluctuations caused by the pump. With the above pressure damping modifications the overall system noise was reduced to less than 1 millibar at 1.0 ml/min flow rate in tetrahydrofuran (THF) for a set of six p-Styragel columns 10 ,... 

TABLE 10-36a Standard Dimensions and Weights, and Tolerances in Diameter and Wall Thickness for Coil Lengths (ASTM B280-2003 )... 

Figure 7.1. Flow diagram of the system for determination of manganese. P peristaltic pump S injection port R reaction coil (length 30 cm) M mixing coil (length 60 cm) and W waste. The numbers in the pump are the flow rates in ml/min of the carrier, reduction, reagent, neutralisation and masking streams, which correspond to (a), (b), (c), (d) and (e), respectively. The distances S-C and C-B are approximately 2 cm. From [29]...

At high temperature, the EDC decomposes into VCM and HC1 by a complex reaction mechanism discussed further in this section. The endothermic reaction takes place at temperatures between 480-550 °C and pressures from 3 to 30 bar. The reaction device consists of a long tubular coil placed in a furnace (Figure 7.4). The first part, hosted in the convection zone, preheats the reactant up to the temperature where the pyrolysis reaction rate becomes significant The second part, the reaction zone, is placed in the radiation chamber. The tube diameter is selected so as to give a superficial gas velocity between 10-20 m/s. The coil length should ensure a space-time of 5 to 30 s. 

The cylinders of cylindrite only grow on a macroscopic scale. Thus, one coil will contain millions of both sorts of unit cells. For all macroscopic cylinders the difference in coil length in two consecutive coils is practically equal to 2nAr, where Ar is the thickness of the increment in the Archimedean spiral. For a layer pair with the thickness Ar =... 

In another characterization of the main direction in a chain molecule according to Kuhn, vector h, joining two ends of the chain is chosen for this purpose In this evaluation of the degree of asymn try of a Gaussian coil, length h can be compared with transverse dimensions of the coil determined by distances hj and hj from vector h relative to the chain points situated at the greatest distance from h in two mutually perpendicular directions normal to It has... 

In a more systematic work on the influence of the coil length on phase behavior, the authors studied rod—coil molecules (10) with polypropylene oxide) having different degrees of polymerization but the identical rod segment (Chart 3).64 65 A dramatic... 

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