scholarly journals Investigation of the saturated steam sampling method influence on the sample representativeness in chemical control systems at thermal power plants

2021 ◽  
Vol 2088 (1) ◽  
pp. 012052
Author(s):  
O V Yegoshina ◽  
S K Zvonareva
Keyword(s):  
High Pressure ◽  
Chemical Control ◽  
Power Plants ◽  
Thermal Power ◽  
Steam Line ◽  
Saturated Steam ◽  
Thermal Power Plants ◽  
Sample Representativeness ◽  
Main Steam Line ◽  
Main Steam

Abstract The most important requirement for sampling is the sample representativeness, which is achieved by the design and location choice of sample nozzle, as well as the speed mode and the presence of sharp pressure drops in the saturated steam flow. The Ansys CFX software package simulates the sampling processes saturated steam in power units with low, medium and high pressure boilers which are used on operating thermal power plants. The saturated steam was sampled from low-pressure boiler by a single-strip probe with a Venturi nozzle, from the medium-pressure boiler was sampled by tapping a pipe at 90 to the main steam line, and the steam of the high – pressure boiler was sampled by a wellhead probe. In three sampling cases it is found that of saturated steam, the flow in the sample nozzle loses speed and decreases to values unacceptable for the selection of a representative sample-below tear rate of the moisture film from the surface. It is confirmed that in the industrial sampling conditions, the condition of speeds equality in the main steam line and in the sample nozzle is not met, which leads to a violation of the sample representativeness. The paper studies the change in the composition of the sampled saturated vapor sample after the film formation on the sample’s nozzle wall in relation to power units with ammonia dosing. It was found that the sample received by the chemical control analyzers is depleted due to the formation of a film and the ferrum and ammonia concentration in moisture droplets on the inner surface of the sampling line.

Main Steam Line Break Calculations Using a Coupled RELAP5/PARCS Model for the Ringhals-3 Pressurized Water Reactor

2008 ◽  
Author(s):  
Mathias Sta˚lek ◽  
Jo´zsef Ba´na´ti ◽  
Christophe Demazie`re
Keyword(s):  
Steady State ◽  
Fuel Assembly ◽  
Thermal Power ◽  
Steam Line ◽  
Pressurized Water ◽  
The Core ◽  
Different Types ◽  
Main Steam Line ◽  
Main Steam ◽  
Control Rods

A Main Steam Line Break (MSLB) is an important transient for Pressurized Water Reactors (PWR) due to the strong positive reactivity introduced by the over-cooling of the core. Since this effect is stronger when the Moderator Temperature Coefficient (MTC) has a large amplitude, a conservative result will be obtained for a high burnup of the fuel due to the more negative MTC late in the cycle. The calculations have been performed at a cycle burnup of 12.9742 GWd/tHM. The Swedish Ringhals-3 PWR is a three loop Westinghouse design, currently with a thermal power of 3000 MW. The PARCS model has 157 fuel assemblies of 8 different types. Four different types of reflector are used. The cross sections, and kinetic data were obtained from CASMO-4 calculations, using a cross section interface developed at the department. There are 24 axial nodes, and 2×2 radial nodes for each assembly. The transient option for calculating the effect of poisoning was used. The PARCS model has been validated against steady-state measurements from Ringhals-3 of the Relative Power Fraction (RPF) and of the core criticality. The RELAP5 model has 157 channels for the core which means that there is a one to one correspondence between the thermal hydraulics model and the neutronics model. There is eight axial nodes. Originally, the intention was to have 24 axial nodes but this proved not to work because of some limitation in RELAP5. There is currently no mixing between the different channels in the core. The feedwater, and turbines are modelled as boundary conditions. The stand-alone RELAP5 model has been validated against steady state measurements from Ringhals-3. A number of different cases were considered. In the first case, both the isolation of the feedwater for the broken loop, and all the control rods were assumed to work properly. For the second case one of the control rods was assumed to be stuck. The stuck rod was located in the fuel assembly with the highest power. This rod has also one of the highest rod worths. In the final case, the feedwater control valve for the broken loop was fully open. None of the cases led to any recriticality. The increase in power for each fuel assembly was also investigated. With the control rod located in the assembly with the highest power, the maximum power increase before scram turned out to be about 25% compared to the initial power.

Improvement of chemical control in the water-steam cycle of thermal power plants

2011 ◽  
Vol 31 (1) ◽  
pp. 119-128 ◽  
Author(s):  
Vladana N. Rajaković-Ognjanović ◽  
Dragana Z. Živojinovic ◽  
Branimir N. Grgur ◽  
Ljubinka V. Rajaković
Keyword(s):  
Chemical Control ◽  
Power Plants ◽  
Thermal Power ◽  
Thermal Power Plants ◽  
Water Steam ◽  
Steam Cycle

Research and Application of Intelligent Control Technology for Main Steam Temperature Regulation in Ultra-Supercritical Thermal Power Plants

2013 ◽  
Vol 448-453 ◽  
pp. 3240-3244
Author(s):  
Shan Shan Li ◽  
Zheng Yu Liang ◽  
He Ren
Keyword(s):  
Intelligent Control ◽  
Temperature Regulation ◽  
Power Plants ◽  
Thermal Power ◽  
Variable Load ◽  
Thermal Power Plants ◽  
Control Technology ◽  
Steam Temperature ◽  
Steady State Condition ◽  
Main Steam

Main steam temperature regulation is one of the most demanded control loop in modulating control system of thermal power plant. According to the characteristics of main steam temperature, an intelligent control technology has been proposed. To eliminate lag and inertia in main steam temperature regulation process, the intelligent control technology integrates several advanced algorithms. The application effects in several ultra-supercritical thermal power plants prove that the control technology has outstanding robustness and excellent adaptability in both variable load and steady state condition.

Comparative System Performance Analysis of Direct Steam Generation Central Receiver Solar Thermal Power Plants in Megawatt Range

2014 ◽  
Vol 136 (1) ◽  
Author(s):  
Javier Sanz-Bermejo ◽  
Víctor Gallardo-Natividad ◽  
José Gonzalez-Aguilar ◽  
Manuel Romero
Keyword(s):  
Power Plants ◽  
Superheated Steam ◽  
Thermal Power ◽  
Solar Thermal ◽  
Saturated Steam ◽  
Thermal Power Plants ◽  
Steam Generation ◽  
Optical Efficiency ◽  
Solar Thermal Power ◽  
Central Receiver

This work proposes and analyses several integration schemes specially conceived for direct steam generation (DSG) in megawatt (MW) range central receiver solar thermal power plants. It is focused on the optical performance related to the heliostat field and the arrangement of receiver absorbers, and the management of steam within a Rankine cycle in the range between 40–160 bar and 400–550 °C at design point. The solar receiver is composed of one single element for saturated steam systems or two vertically aligned separated units, which correspond to the boiler and the superheater (dual-receiver concept), for superheated steam solar thermal power plants. From a fixed heliostat field obtained after layout optimization for the saturated steam solar plant the heliostat field is divided in two concentric circular trapezoids where each of them independently supplies the solar energy required by the boiler and the superheater for the different steam conditions. It has been observed that the arrangement locating the boiler above the superheater provides a slightly higher optical efficiency of the collector system, formed by the solar field and the receiver, compared with the reverse option with superheater above boiler. Besides, two-zone solar fields provide lower performances than the entire heliostat layout aiming at one absorber (saturation systems). Optical efficiency of two-zone solar fields decreases almost linearly with the increment of superheater heat demand. Concerning the whole solar collector, heliostat field plus receiver, the performance decreases with temperature and almost linearly with the steam pressure. For the intervals of steam pressure and temperature under analysis, solar collector of saturated steam plant achieves an optical efficiency 3.2% points higher than the superheated steam system at 40 bar and 400 °C, and the difference increases up to 9.3% points when compared with superheated system at 160 bar and 550 °C. On the other hand, superheated steam systems at 550 °C and pressure between 60 and 80 bar provide the highest overall efficiency, and it is 2.3% points higher than performance of a saturated steam solar plant at 69 bar. However, if saturated steam cycle integrates an intermediate reheat process, both would provide similar performances. Finally, it has been observed that central receiver systems (CRS) producing saturated steam and superheated steam at 500 °C operating at 40 bar provide similar performances.

scholarly journals Combined electromachine generators for energy-efficient mini-power plants

2018 ◽  
Vol 251 ◽  
pp. 03038
Author(s):  
Igor Zabora
Keyword(s):  
High Pressure ◽  
Energy Efficient ◽  
Power Plants ◽  
Design Principle ◽  
Thermal Power ◽  
Electric Machines ◽  
Thermal Power Plants ◽  
High Pressure And Temperature ◽  
Moving Media ◽  
Extreme Parameters

The design, principle of operation and features of new combined electric machine – generator-transformer unit (GTU) are considered. The units are designed for generating units of mini thermal power plants with extreme parameters of moving media (steam-gas, gas-liquid, etc.) at high pressure and temperature. The possibility of reliable and efficient conversion of electric power by means of electric machines directly in sealed objects with extreme environmental conditions with help of new GTU is shown.

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