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Zusammenfassung

In diesem Beitrag wird ein Sensorkonzept zur simultanen Messung der Temperatur und der Dampffeuchte eines Dampf-Flüssigkeits-Gemisches, insbesondere Wasser, auf der Basis der Infrarot-Spektroskopie vorgestellt. Schwingungsspektren von Reinstoffen hängen neben der Temperatur auch von dem Aggregatzustand und damit dem Phasengehalt einer Probe ab. Es wird beschrieben, wie diese, aus der Literatur bekannten, physikalischen Phänomene in ein technisches Messverfahren übertragen werden können. Dazu werden unterschiedliche Algorithmen zur simultanen Temperatur- und Dampffeuchteauswertung vorgeschlagen.

atmosphere had a great influence on the corrosion behavior of the water wall tube [ 7 , 8 9 ]. In this study, the steam quality of the boiler cannot reach the requirement because of the higher ash content and lower received lower heating value of the process coal. The effective way to meet the steam parameter requirement for boiler thermal load is to increase the input of process coal. As a result, the furnace temperature and ash deposition at the heating surface of the water wall tube increased, leading to the deposition of low melting ash at the heat surface, especially

that concentrating mechanisms are avoided. Erosion in power station headers, where the steam quality is controlled, for protection of the turbines, remains as a maintenance problem. 219 Vol. 17, No. 3-4, 1999 Corrosion in Wairakei Steam Pipelines 1. INTRODUCTION The "discovery" of erosion corrosion in the Wairakei steam pipelines during an annual inspection in 1977 (Page, 1977, Braithwaite, 1977) was followed by efforts to characterise the extent of corrosion damage (Page and Marshall, 1978, Braithwaite, 1978, 1980, Stacey and Thain, 1983) and later to

by means of a mechanism regulating the load torque at the steam engine shaft. In this application, the steam engine replaces the throttling process in the pressure reduction station. Assuming there is liquid steam in the external system, the isobaric and isothermal lines coincide during phase transitions. As for higher steam quality, the following expression can be used to obtain approximate results: p2 · v2 = p20 · v20 = const, (15) p2 being pressure, v2 the specific volume of the external system, p20 the initial pressure and v20 the initial specific volume of the

was used to measure the quality of steam at a generator plant ( Jean 2007 ). The interferometer, shown in Figure 14 , works by measuring the differential path length between two transmission lines; this determines the change in permittivity as the quality of steam changes. The device was able to measure a frequency shift from 10.346 GHz for 100% dry steam to 10.275 GHz for a steam quality of 50%. Figure 14: Structure of the probe portion of the sensor ( Jean 2007 ). Reproduced with permission from Jean, 24 October 2017. In conclusion, when microwave probes are used

significance of the derived variables of the boiler was performed using statistical data from the real time plant for the modeling and prediction of thermal efficiency [ 12 ]. With the help of real time plant data, Lee et al. [ 13 ] developed a neural network combined model and validated the same with the actual plant data. Later the authors used modified predictive optimal strategies to control the steam quality. Reference [ 14 ] gives the concept of data driven modeling using intelligent techniques like neural network, fuzzy system, genetic algorithm and combination of all

the specially designed iron-based catalyst. In contrast, the slurry bed operation temperature for a cobalt-based catalyst is more stringently restricted to lower ranges, from 190°C to 240°C, above which significantly higher methane selectivity was observed. Consequently, for Synfuels China’s MTFT technology, the steam quality is upgraded from the conventional 8–10 kg/cm 2 pressure low-grade steam to a higher pressure of 25 kg/cm 2 , which significantly boosted the total system energy efficiency up to 40% even for the 160 kt/a plant of demonstration scale. Overall

), variations of temperature at the bottom of the col- umn (due to the changes in the steam quality), variations of the feed flow (clogging of the pipelines, ageing of the centrifugal pump), the outside pressure change (vari- able weather fronts). The permanent presence of disturbances imposes the automatic control of a process. 5.4 Stability and instability of controlled process and control systems From the point of view of stability, the process can be self-regulating or non-self- regulating. A process is self-regulated (or BIBO stable) if, at the occurrence of a bounded

composition at the top of the column is disturbed almost permanently by: changes of the composition of the feed flow (changed raw material, changes in the functioning conditions of the previous stages), variations of temperature at the bottom of the col- umn (due to the changes in the steam quality), variations of the feed flow (clogging of the pipelines, ageing of the centrifugal pump), the outside pressure change (vari- able weather fronts). The permanent presence of disturbances imposes the automatic control of a process. 126 | Part I: Introduction 5.4 Stability and

purpose steam turbines 5.2.3 Concluding remarks Because Dry Gas Seal (DGS) technology has demonstrated high effectiveness in low- ering maintenance costs for gas compressors, its successful adoption by other fluid machines and application in small and medium-sized steam turbines was foresee- able. Not only does the cartridge seal approach extend steam turbine life, but it will also reduce the amount of maintenance required. Equipment uptime is extended by the implementation of cartridge-style steam glands. However, the steam must be dry and clean. If steam quality is