[en] If the part of the HTS magnet is exposed to the outside of the cryogenic coolant due to the fluctuation of the height of the cooling liquid or the vapor generation, the uncooled part becomes very unstable. In this paper, the unstable equilibrium temperature distribution of the uncooled part of a superconductor is obtained, and the maximum temperature and energy are calculated as a function of the uncooled length. Similar to the superconductor stability problem, the current sharing model was applied to derive the theoretical formula and calculated by numerical integration. We also applied a jump model, which assumes that joule heat is generated in all of the uncooled segment, and compares it with the current sharing model results. As a result of the analysis, the stable equilibrium state and the critical uncooled length in the jump model are not shown in the current sharing model. The stability of the conductors to external disturbances was discussed based on the obtained temperature distribution, maximum temperature, and energy

No abstract available

[en] A steam generator comprising a tubular plate with holes to which are connected the extremities of the U-tubes of a bundle, said tubes being dipped in a secondary fluid and containing a circulating primary fluid, is described. This generator is characterized in that the extremities of the U-tubes of said bundle are distributed in the tubular plate with a non-constant pitch, the tube portions in which flows the hot primary fluid being arranged with a pitch greater than that of those tube portions in which flows the cold primary fluid. Such an arrangement permits to improve the circulation of the secondary fluid in that portion of the bundle in which flows the hot primary fluid, in particular in that portion which is farthest from the secondary-fluid admission peripheral zone

[en] In the construction of heat exchangers, particularly the steam generators of pressurized water nuclear power stations, it is necessary to make large perforated plates for securing and holding the tubes through which flows the exchange fluid carrying the heat for vaporizing the water forming the secondary fluid of the reactor. The invention concerns a device for trimming and bevelling the holes of a perforated plate which comprises a series of holes of various shapes machined during an operation leaving a raised metal edge and sharp angles around the edges of the holes, on at least one of the sides of the plate, by means of a rotating metal brush

No abstract available

[en] Highlights: • Standard efficiency of boilers in terms of higher heating value is renamed. • Experimental investigation of a 25 kW condensing boiler system is performed. • Maximum fuel savings are 17.5% if replace a traditional with a condensing boiler. • Condensing boilers are not a financially attractive alternative in typical cases. Implementation of Energy-related Products Directive issued in September 2015 raised throughout Europe the interest concerning real performance of the condensing boilers, which currently are mostly assumed as stated by manufacturer’s data sheets. In this regard, an experimental study on an advanced condensing boiler system (representative for current condensing technology level) was performed under specifications of the currently in-force European standard on boilers performance and testing. Efficiency in terms of the fuel’s higher heating value was renamed in order to avoid any potential misunderstanding due to values of this parameter exceeding 100% versus the classic notion of efficiency. The study concludes that annual fuel savings up to 17.5% in real operating conditions are possible. By evaluating the real fuel savings in three typical cases, the payback period for the transition from traditional to condensing boiler is close to the average lifespan of a boiler or longer. Hence, household upgrade from a traditional to a condensing boiler is economically unattractive as long as no convenient financial measures, like subsidies is in place. This may significantly delay the targeted achievement of the directive objective – reduction of the pollutant emissions throughout the entire supply chain, from the design stage to the exploitation.

No abstract available

[en] A programme at Westinghouse aimed at improving the efficiency and reliability of steam generators has led to the development of the model F generator. Its design features are described and the performance in model boiler and field tests, and in operating plants is summarised. (U.K.)

[en] About 80 per cent of all plant outages involving steam generators can be traced back to corrosion problems. Such problems arise from the continuous ingress of non-volatile contaminants, ie corrosion products and salt impurities. These have their origin in the balance of plant systems, and the corrosion products generally accumulate in the steam generators - forming both deposits in the flow restricted areas (such as on the tube sheet and tube support plate), and scales on the steam generator heating tubes. For many years, the industry has been involved in developing various types of cleaning techniques. Among these, chemical cleaning especially has been found to be very effective for removing corrosion products. The KWU chemical cleaning process described here consists of two different single-step methods for sludge removal: a high temperature iron process; and a copper process with ambient application temperature. The iron and copper process can be applied either in combination or separately, and uses separate solvents. (author)

[en] A description is given of a support intended for a bundle of tubes arranged in a helical winding comprising a plurality of coaxial cylindrical layers. Said support used in a generator is so much supple as it makes it possible to maintain a constant tightening force whatever expansion may be, while supporting the vibrations that occur in course of operation