Combined cycle power plants in the power generation industry

Combined cycle power plants use a combination of a Gas Turbine Generator (Brayton cycle) with an exhaust gas Heat Recovery Steam Generator (HRSG) and a Steam Turbine Generator (Rankine cycle) for the production of power. If the steam from the Heat Recovery Steam Generator is used for process or space heating, the plant is operating as a combined heat and power plant (CHP). Today, when gas plants are cyclically operated because of the large feed of renewable energy to the grid, a controlled operation limiting the boiler stress is extremely important in order to maintain availability and preserve boiler lifetime. Without accurate measurements and confidence in these measurements, routine start-up and cycling operation with performance improvement is difficult. The Combined Cycle Main Components are: Gas Turbine Generator (GTG), HRSG with Selective Catalytic Reactor (SCR), Duct Burner (supplementary firing), Steam Turbine Generator (STG) and Balance of Plant (BOP).

KROHNE Power Generation is specialised on instrumentation suited to state-of-art requirements. For example, feedwater flowmeters are of high importance for process control and safety, need to cope with the high temperatures and pressures on power plants, while satisfying their high accuracy and redundancy requirements. Typically, Venturi tubes or flow nozzles installed in meter runs with redundant DP-transmitters according to ISO 5167 or ASME MFC-3M are used. The KROHNE engineered primary DP flow elements and meter runs are hot water factory calibrated at high Reynolds numbers. The OPTIBAR DP 7060 C pressure transmitters are 100% 3D-calibrated over the entire temperature and static pressure range and available with measurement capsules operating up to 700 bar line pressure.

KROHNE supplies the complete flow solution, comprising DP-flow element, DP-transmitter, separate pressure and temperature transmitters, process valves, with full engineering, calibration and documentation. A further option here are the OPTISONIC 3400/ 4400 ultrasonic flowmeter series suitable for these requirements in terms of temperature, pressure, materials redundancy etc. KROHNE OPTISONIC meters are drift and maintenance free, have no pressure drop and an extremely wide turndown ratio - which enables a very good low-end accuracy. Also for Steam, reheat, injection/attemperation water, condensate and other typical flow applications KROHNE OPTIBAR DP and OPTISONIC Ultrasonic flowmeters are available.