In order to develop efficient control and to predict a steam turbine’s power output precisely, it is desirable to have a linear relationship between controller output, RA, and steam mass flow. Unfortunately, steam mass flow through a turbine is not only determined by the control valve stroke but also by the pressure in front of these valves. Even at constant pressure the relation between valve stroke and steam flow through the turbine is extremely non linear. The complexity is increased by the fact that a turbine is generally operated by two or four control valves which do not necessarily work parallel over the complete operational range. Additionally, the pressure in front of the control valve changes with the admitted steam mass flow. A counterbalancing method was developed that allows to include individual process data, such as pressure in front of the valves and at the turbine inlet in dependence of steam mass flow and valve throttle characteristics, as well as process engineering constraints, like valve staggering, for example. The developed method is applicable to new steam power plants as well as to retrofits. With the developed method it is also possible to predict individual valve strokes at valve testing or at deviating exterior conditions. The later feature is extremely useful for retrofit applications. Firstly, the correctness of the implementation with respect to the ‘old’ set-up can be verified, and then, secondly, the characteristics of the retrofitted components and thermodynamic conditions, respectively, can be substituted. The developed method was successfully applied for several power plants. A comparison of predicted data and commissioning data will be provided.

The Babcock & Wilcox Company (B&W) has developed a rule-driven design (RDD) computer application to speed the design of its wet flue gas desulfurization (WFGD) slurry spray header system including support steel. The application, written using the RuleStream RDD system, captures the talents of the many people involved in the spray system’s design, including those involved in process engineering, design engineering technology, structural mechanics, and technical design. B&W’s design standards and best practices are blended with fabricator capabilities and industry standards to form the application rules. Third-party software (for example CAESAR II) and proprietary computer programs are leveraged by the application courtesy of the RuleStream RDD architecture. The application seeks to automate the routine first 80% of the design, while providing interfaces to complete the design or explore “what-if” situations. Interfaces allow the evaluation of spray coverage, pipe velocities, pressure drop, physical clearances, weights, and stresses. The application generates drawings, a solid model, and a bill of material for fabrication. Using the application, repeatable, consistent results are achieved. There is a higher confidence in the generated design and a reduction in design cycle time. This saved time may be allocated to exploring alternative designs, pursuing fabricator quotes, performing contract level analysis in the proposal phase, or may be applied to other areas of the WFGD design.