[en] Short communication

[en] A feed pump conveys the cooling medium NH₄ via the vaporizer set in the storage pool to a thermal engine. The recooling is performed by a condenser. Necessary drive energies are provided by the system itself. (DG)

[en] The results of experimental investigation of heat exchange at the condensation of water vapor from vapor-air mixtures are presented. The experimental investigations are carried out on the models of surface and bubbling-type condensers. The results obtained are shown in the form generalizing relations. Devised methods can be recommended for calculation surface and bubbling-type condensers. (Author)

[en] Highlights: • Model calibration method for BEPU was developed with optimization method. • Nonparametric statistics method with Wilks was used for Sherwood uncertainties. • SCOPE test data was applied to calibrate condensation model. - Abstract: Quantification of model input uncertainties is very important to development of Best-estimate plus uncertainty (BEPU) accident analysis method. In particular, condensation model uncertainty on the Sherwood number should be quantified accurately in the development of containment response BEPU analysis method. In this paper, Sobol’s total indices were used to assess the parameter sensitivity, nonparametric statistics method with Wilks correlation was used to quantify the Sherwood number uncertainties, and calibration intervals of the condensation factor were obtained with an optimization method. The objective of the optimization was to ensure that the Sherwood number uncertainties quantified from test data were enveloped by those calculated from model prediction. The optimization process was automatically implemented with specified objective function and constraint condition. The results show that the developed method is able to reasonably determine the condensation model calibration interval. The method presents high accurateness, robustness and flexibility and could be conveniently applied to model uncertainty quantification based on separate effects tests and simple integral effect tests.

[en] Air and water in-leakage have been major problems in Power Generating Plants. Condenser plugging has often appeared to be an afterthought. A typical condenser may contain 40,000 tubes, with the propensity for a large number of leaks. Often the only consideration was finding the lowest cost option. Little regard was given to quality of seal, secondary damage to surrounding tubes or tubesheet, and service life. Over the course of time rubber plugs deteriorate and fail for a multitude of reasons. This paper will document three cases demonstrating significant cost savings and process improvements resulting in a proactive condenser plug change out program. (author)

[en] The COMMIX-PPC computer pregrain is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex Industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional equations of conservation of mass, momentum, and energy on the tube stile and the proper accounting for the thermal interaction between shell and tube side through the porous-medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient. Three-dimensional analysis of fluid flow with heat transfer tn a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification, it can be used to analyze processes in any heat exchanger or other single-phase engineering applications. Volume I (Equations and Numerics) of this report describes in detail the basic equations, formulation, solution procedures, and models for a phenomena. Volume II (User's Guide and Manual) contains the input instruction, flow charts, sample problems, and descriptions of available options and boundary conditions

[en] Till recently analysis of vibration signals was the only means available to predict the state of health of plant equipment. Motor current and leakage magnetic flux signature analysis is acquiring importance as a technique for detection of incipient damages in the electrical machines and as a supplementary technique for diagnostics of driven equipment such as centrifugal and reciprocating pumps. The state of health of the driven equipment is assessed by analysing time signal, frequency spectrum and trend analysis. For example, the pump vane frequency, piston stroke frequency, gear frequency and bearing frequencies are indicated in the current and flux spectra. By maintaining a periodic record of the amplitudes of various frequency lines in the frequency spectra, it is possible to understand the trend of deterioration of parts and components of the pump. All problems arising out of inappropriate mechanical alignment of vertical pumps are easily identified by a combined analysis of current, flux and vibration signals. It is found that current signature analysis technique is a sufficient method in itself for the analysis of state of health of reciprocating pumps and compressors. (author). 10 refs., 4 figs

[en] For many years, condenser biofouling has been difficult to prevent/control. The benefits of maintaining clean condenser tubes to the efficient operation of steam electric power plants include: (1) Prevention of Heat Rate Degradation (2) Extended Condenser Tube Life (3) Elimination of Outages to Clean the Condenser. TU Electric's Martin Lake Plant has been utilizing an innovative on-line mechanical tube cleaning system since April, 1992 to maintain condenser cleanliness while eliminating the use of chlorine to control biofouling. The system is operated as a tube cleaning service; therefore, no capital investment or plant retrofit was required. The system was installed while the units were operating at base load. The results of the on-line cleaning effectiveness were determined by the EPRI Plant Monitoring Workstation, installed test grade instrumentation, and on-line video borescope tube inspections

[en] Electricite de France is now operating or building fifty-six 900, 1300 or 1400 MW nuclear units and twenty-eight of them have wet cooling towers as the main heat sink. Nuclear power plant cooling systems definition has important consequences on investment and also output rate. Method and programs used by EDF for main heat sink optimization (condenser, cooling circuit, cooling towers) are described in this report. The main components definition process and other types of studies which can be made with these tools are also described

[en] The tube side intermittent flow in U-tube bundle of vertical condenser is numerically simulated using RELAP5 MOD3.4. The flow rate intermit between a maximum and minimum value. The results of the simulation shows that reverse flow is established inside a group of the tubes from the outlet to the inlet channel -head during the low flow rate period. The reverse flow is seized when the minimum flow rate exceeds certain value. A steady state numerical simulation predicts the minimum inlet flow rate to establish the reverse flow. The effect of temperature difference at the inlet of the tubes and the tube resistance on the limit of the reverse flow inception is also studied. The heat transfer from the condensing steam on the shell side is also taken into consideration. (author)