Transfer line insulated

Some applications of cryogenic-fluid transfer require optimization of many aspects of transfer-system design. This study examines methods of transfer-line insulation, the problems of metal degassing, and line storage life. 

For hydrogen reformer transfer lines, materials used are Incoloy 800, HK, and HT cast stainless steels. Wrought 300 series stainless steels and internally insulated carbon, carbon-V2, Mo. and IV4 Cr- /2 Mo steels. Reported failures of transfer lines indicate that failures are associated with... 

Substitution means the replacement of a hazardous material or process with an alternative which reduces or eliminates the hazard. Process designers, line managers, and plant technical staff should continually ask if less hazardous alternatives can be effectively substituted for all hazardous materials used in a manufacturing process. Examples of substitution in two categories are discussed—reaction chemistry and solvent usage. There are many other areas where opportunities for substitution of less hazardous materials can be found, for example, materials of construction, heat transfer media, insulation, and shipping containers. 

Minimize heat losses from the reactor plenum and the transfer line. Heat loss will cause condensation of heavy components of the reaction products. Insulate as much of the system as possible when insulating flanges, verify that the studs are adequate for the higher temperature. 

Figure 7.2.2 Schematic diagram of the flow probe developed by Dorn and co-workers and used for the direct coupling of SFC to NMR (a) insulated glass transfer line (b) glass insert (c) Cu/constantin thermocouple (d) stainless steel equilibrium coil (e) brass shield (f) Helmholtz coil (g) ceramic flow cell (h) brass Swagelok fitting. Reprinted with permission from Allen, L. A., Glass, T. E. and Dorn, H. C., Anal. Chem., 60, 390-394 (1988). Copyright (1988) American Chemical Society...

At cold spots the analytes can adsorb to the surface material and only a fraction will reach the detector. Subsequently, the adsorbed compounds can result in ghost peaks in later analyses. Transfer lines from for example, a TD instrument to the GC must be insulated and heated to avoid cold spots . The optimal temperature of the surfaces depends on the stability of the component, pressure, vacuum, etc. Some GC instruments have ceramic insulators at the inlet of the transfer line from for example, TD instruments and this material may act as a cold spot if the line is not heated at the inlet... 

Cryogenic fluid transfer lines are generally classified as one of three types uninsulated, foam-insulated lines, and vacuum-insulated lines. The latter may entail vacuum insulation alone, evacuated powder insulation, or multilayer insulation. A vapor barrier must be applied to the outer surface of foam-insulated transfer lines to minimize the degradation of the insulation that occurs when water vapor and other condensables are permitted to diffuse through the insulation to the cold surface of the lines. 

This cylindrical, low-pressure, horizontal tank had a design rating of about 5 psig (0.3 bar). A steam coil heated this tank. The transfer line to the tank was steam traced and insulated to keep it clear, but the heat tracing and insulation system on the inlet transfer piping was less than ideal. The inlet piping had to be dismantled on several occasions to clear it because of solidification in the fine. (See Figure 6—18.) [7]... 

Storage tanks and transfer lines of liquid oxygen systems must be well insulated to prevent the condensation of moisture or air with subsequent ice formation on the outside. Vacuum jackets, formed plastics, and alternate layers of aluminum foil and glass-fiber mats have been used successfully. 

As with liquid oxygen, storage tanks and transfer lines of liquid hydrogen systems must be well insulated, to prevent the evaporation of hydrogen or condensation of moisture or... 

The transfer lines and heated zone are well-insulated to ensure uniformity in texiqperature during saxxqpling. 

The DieMate manifold is insulated to improve thermal uniformity and to prevent exposure of the DieMate socket to excess temperature. (The DieMate socket maximum temperature specihcation is 150 °C.) Figure 12.4 shows the insulated DieMate manifold before attachment of the 1 /16-inch transfer lines. The insulation consists of a ceramic hber strip that has a maximum operating temperature of 2300 °F (1260° C). 

A Small Scale Slush Hydrogen Facility has been constructed by NASA to study ways of optimizing the SLH2 production process and provide a test bed for advanced instrumentation. The tank with a total volume of 0.76 is vacuum jacketed and wrapped in several inches multilayer insulation plus a liquid nitrogen shield in the upper tank part. A 1 kW heater is used to simulate a heat leak or a warming up. The tank also offers the option to install a liquid helium slush auger for research on this method of production. In a 17 m long and 0.05 m diameter vacuum jacketed transfer line, studies on flow characteristics and instrumentation can be conducted [40]. 

With analyzer controllers, it is essential to minimize the sample transfer lags. Vapor samples are preferred, since they can travel faster. A liquid sample is often vaporized upon withdrawal if sample lines are long. Heat tracing and insulation are usually required to keep the sample vaporized. To maintain high velocities, and at the same time avoid miniscule sample transfer lines that tend to break, the sample drawn is often much larger than the analyzer requires, with its unused portion returned to the process. This is considered an absolute must for unvaporized liquid samples (362). 

Figure 3.50. A cryogenic probe installation. The cryogenic bay (A) contains the cold expansion head that generates cold helium gas that passes along the insulated transfer line (B) to the probe. The vacuum line (C) maintains the cryogenic probe vacuum and the base of the probe (D) houses the cold preamplifier stages. At the rear can be seen the high pressure lines (E) that carry helium gas to/from the remote compressor.

The vacuum chamber (Fig. 2) is a 20 x 39-in. stainless steel cylinder of all heliarc-welded construction. The chamber is suspended in an insulated aluminum tank. The chamber volume after correction for the pump lines and cryosphere was calculated to be 202 liters. This chamber size makes possible the use of commercially available standard leaks, without introducing significant errors in the time measurement when calibrating the gas analyzer by the rate of pressure rise method. The 7-in.-diameter cryosphere has a calculated surface area of 995 cm . The coolant transfer lines to the cryosurface are vacuum-jacketed to prevent possible condensation. 

---