Crossover piping

There is one point to watch in regard to the crossover temperature. The fluid temperature determined as previously described corresponds to the transition from true convection tubes to shield tubes. In many heaters the shield tubes are part of the convection section, and the crossover piping is actually between the shield and radiant tubes. The temperature in the crossover piping is then higher than that calculated in the rating by an amount corresponding to heat absorption in the shield rubes. 

This Porton Down test report also provided details of earlier Porton Down testing that were not known when the NRC International Technologies report was prepared (NRC, 2006 DiBerardo et al., 2007). In September 2004, an operator observed that one of the expansion joints in the crossover pipes between the detonation chamber and the expansion tank had cracked. Subsequently, several of the expansion joints upstream and downstream of the expansion chamber were replaced, using a modified design. No further expansion joint failures were experienced during the testing at Porton Down. 

New crossover pipes and tail pipes were installed on all test cars. The test vehicles had an average of 80,000 kilometres before the start of the lead emission trial. Prior to the commencement of the trial, each automobile was given a tune-up by an authorized Chevrolet dealer to meet manufacturer s specifications. 

Cooling-water heat losses must be tallied, especially from bottom-fired zones, that is (a) skidrails pipes—insulated -I- uninsulated, (b) crossovers pipes—insulated -I- uninsulated, (c) riser pipes—insulated -f uninsulated. 

The water-cooled skid rail pipe supporting the skid wear bar is insulated with one or two different insulating materials to reduce heat gain (as these are subject to the same hot furnace gas heat transfer as are the loads). A group of crosswise water-cooled support pipes (crossovers) support the skid rail pipes from below and are attached to the furnace sidewalls. Vertical pipes (risers) support the crossover pipes. The outer surfaces of all the skid and supporting pipe stmcture must be capable of withstanding physical and thermal shock as well as chemical attack from the bottom-zone furnace gases. 

Figure 5.7 shows a horizontal slot as in the sidewall of a furnace, but for this case, with radiation shining up through one of the grids of slots formed by the skid rails and their crossover pipes, X is vertical and D is horizontal. 

The two coolant lines are joined at one end of the reactor by means of a simple crossover pipe at the other end of the reactor, a vertical conduit leading down to a slurry cubicle in the basement is indicated. The intention... 

It should be understood that there are many variables to this desCTipiion. Burners may be located In the side walls or roof of the radiant section. Insulation may be reftactory brick, ceramic fibers, or a mineral wool blanket. The produa may flow into the convection section tubes, exit that seaion through crossover piping, and flow through the radiant seaion. Multiple furnaces may be tied to one common sack by breeching. 

A direct pipe connection to the trapout boot is much preferred (Figure 7-77a). Liquid can be heated in an internal crossover (Figure 7-77b) and the downcomer might have some vapor content. With even a small amount of evaporation, the liquid density rapidly decreases and the calculated positive liquid head will not be entirely available. 

One design feature of the EFW system which improves its reliability is its component and piping separation and diversity. For example, each subtrain is separated from the other and therefore has its own discharge line through the steam generator isolation valve and check valve. In addition, the pump crossover lines contain redundant, locked closed, isolation valves. The subtrain design reduces the potential for single failure and improves system reliability. 

It is a countercurrent flow unit. TempcraEuie crossover is not a problem. 2) suitable for high pressure service, since both she] 1 and tubes are pipes, 3] applicable to fluids with large temperature diffnence withour expansion joint, 4] easy to install, and add on additional units, standant design, usually nor cusiom made. Its delivery time is short, 6) u is easy to maintain - clear, ir.[Pg.74]

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