Inconel tubes

Over 30 minutes, 1,3,5-trichloro-2,4.6-trifiuorobenzene or 1,3-dichloro-2.4,5.6-tetrafiuoro-benzene (between 10.0 and 10.5 g) is fed with different flow rates of nitrogen (10 to 50mL min t) into a platinum-lined inconel tube (91-cm length and 12.7-cm i.d.) with or without an additive at various temperatures (Tables 7 and 8).40,41... 

Tlte control element assembly, shown in Fig. 15. consists of 0.8-inch (2-ceiuimeler) outside diameter Inconel tubes containing boron carbide pellets as the neutron absorbing material. A gas plenum is provided in order to limit the maximum stress due to generation of internal gas pressure. 

The desulfurization experiments were run in a batch reactor designed and constructed at the Ames Laboratory. The reaction crucible (8 in. x 3.5 in. o.d.) was constructed from Inconel tubing. A basket to hold the coal was fashioned from -20 mesh stainless steel screen. The chromel-alumel thermocouple was sheathed in stainless steel. 

At temperatures close to 20 20°, water is a suitable liquid for a thermostat. At higher temperatures it is more convenient to use a fluid such as silicone oil, or above 200°, molten metals. A typical furnace is shown in Fig. 5. A silica former is wound with nichrome wire such that the pitch decreases from one end to the centre and then increases again to the other end. Since heat losses are greatest at the ends this provides a rough correction. An inconel tube also evens out the tempera-... 

Excess quantities of oxidizers in Reactions 2.6 and 2.7 resulted in complete consumption of CO. In a fuel-rich case, a high NO concentration was almost completely eliminated by sampling through a hot inconel tube. However, the NO started increasing after the inconel tube temperature was lowered by pulling the tube out of the furnace. This temperature dependence is shown in Figure 2.13. 

There are numerous ways to prepare VDF (CF2=CH2, CAS number 75-38-7). Two methods, including the popular commercial technique for VDF production, are described. Conversion of 1,1,1-trifluoroethane begins by passing this gas through a platinum-lined Inconel tube, which is heated to 1200°C. Contact time is about 0.01 sec. The exit gases are passed through a sodium fluoride bed to remove the hydrofluoric... 

Figure 7.3. Main features of the apparatus used for transpiration experiments. 1 - thermocouple, 2 - gas entrance, 3 - graphite tube, 4 - furnace, 5 - capillary openings, 6 - graphite shields, 7 - Kanthal heating, 8 - graphite boat, 9 - cold-finger, 10 - Inconel tube, 11 - gas exit.

The boat with a fresh sample was placed in the graphite tube between the two capillaries. The steel-graphite-tube assembly was positioned such that the boat came as close as possible to the entrance end of the Inconel tube, while the furnace was located at the opposite end of the Inconel tube. Carrier gas was then passed through the tube to remove all air. After ten to fifteen minutes the gas flow was stopped, and the steel-graphite-tube assembly and the furnace were pushed towards each other into their correct positions. When the sample reached the selected temperature, the experiment was started by passing carrier gas over the sample at constant flow rate. This temperature, being lower than the desired temperature, was found from accurately determined temperature-time curves. 

It may be seen from Table 7.6 that a reproducible difference in the NO and O2 readings was detected for the Inconel and quartz tubes. The Inconel tube always showed lower NO and O2 readings. The NO readings with the CEMS were not made for these transitional measurements because of the time limitation. 

Caution. Crimp welds cannot dependably withstand the necessary pressures. A steel or Inconel tube furnace liner is recommended as partial protection against possible explosion hazard. It also serves to smooth out temperature gradients. 

A resistance furnace (11) with sufficient mechanical stability and chemical resistance is machined from stainless steel 150 mm in height, 70 mm in outside diameter, and 2 mm in wall thickness by cutting it lengthwise into 24 elements. The clearance between elements is 2 mm. A power supply with 30 V and 200 A is sufficient. The lifetime of the furnace is about 80 hr in the presence of molten Li3N. A graphite heater cannot be used because of the formation of C02, which reacts with the Li3N crystals. The temperature is controlled by a Pt/Pt 10% Rh thermocouple which is encapsulated in an Inconel tube with 1 mm outside diameter. The thermocouple is mounted on the outside of the furnace. The heat loss and material loss by convection are reduced by several heat shields made of molybdenum (12). 

Pyrolysis furnace. This unit also performs two operations It preheats the vapor to its reaction temperature, 500°C, and it carries out the pyrolysis reaction. The unit is constructed of refractory brick, with natural gas-fired heaters, and a large bundle of Nickel, Monel, or Inconel tubes, within which the reaction occurs. The tube bundle enters the coolest part of the furnace, the so-called economizer at the top, where the preheating occurs. 

TEST SECTION. The test section used was a 0.375 in. OD, 0.031 in. wall Inconel tube. The heated portion was approximately 12 in, long and 5 in. of un-heafed test section preceded the heated portion. A larger-diameter (0.625 in. OD) stainless steel test section was used in some preliminary runs. 

The test sections were instrumented with copper-constantan thermocouples silver-soldered to the outside wall. Additional thermocouples were placed on the copper flanges to check heat leakage into or out of the test section. All thermocouples employed a boiling nitrogen cold junction. Pressure taps were located upstream and downstream of the test sections and along the heated portion of the 0.375 in. OD Inconel tube only. 

Inconel tube. The inside wall temperature was computed from the experimental values of the outside wall using the conduction relation for a cylindrical element with uniform power generation. 

Fig. 4. Typical local values of heat transfer coefficient along length of test section, 3/8 in. OD. Inconel tube.

In the first series of experiments, the uranium, as UO2, was enriched to 3.95% inThe fuel-bearing region of each rod was 1.27 cm in diameter and 138.7 cni long, clad in 0.046-cm-thick Inconel tubing. Because of the limited number of rods, it was possible to make only a few lattices critical in water. However, it was established that the minimum number of these rods that can be made critical, when moderated and reflected by water, is 149, in a square pattern at a jpitch of 2.64 cm this was a 12 X 13 lattice with seven rods removed from one face and contained 9.5 kg of °U. 

Fig. 16-1. Top view of the reactor core of the ARE. Hexagonal beryllium oxide blocks serve as the moderator. Inconel tubes pass through the moderator blocks to carry the molten-salt fuel.

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