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Yokogawa’s CENTUM CS 3000 system handles all of these sequences as well as the control of feed water, steam temperature and pressure, and drum level, and uses sensory inputs from a Yokogawa zirconia oxygen analyzer to optimize combustion of the fuel in the furnace, thereby assuring the stable year-round supply of electricity to the national grid. And when the power plant switches to island mode, the system adjusts the boiler firing rate to decrease the supply of steam to the plant’s steam turbine, thereby decreasing power production to a level that meets the plant’s own requirements. All of these sequences are also configured in the CENTUM CS 3000 system. Graphic displays at the control stations give operators a clear view of what is going on throughout this system at any given time, ensuring that they have all the information needed to take quick and decisive action whenever intervention is required.Central control room Burner management displayEmissions monitoringAfter combustion in the furnace, the heavier particles fall down to the inclined bottom of the furnace and are swept out through an ash port by a screw conveyer for removal. Lighter particles mixed with flue gases are carried out of the combustion chamber through a flue port. An induced draft fan draws these flue gases into groups of electrostatic precipitator (ESP) that trap the lighter fly ash particles before the flue gases pass up the stack for discharge into the atmosphere. This flue gas is monitored by the Yokogawa CEMS, which measures CO, CO2, O2, NOx, and SOx concentrations for reporting to the government on a weekly and monthly basis. All water used in the plant is analyzed by a pH meter and conductivity meter so that it can be kept within an allowable range. Continuous emission monitoring systemCustomer SatisfactionChanapai Sahudsa, A.T. Biopower’s Engineering Manager, had the following to say about Yokogawa’s solutions: “This is the first plant to be approved by the Thai government under the Clean Development Mechanism (CDM) defined in the Kyoto Protocol. We are very happy to be using Yokogawa’s system and products at this rice-husk-fuelled boiler plant, the world’s largest of its type. We are always looking for ways to improve its operation and make the combustion process more efficient. We always appreciate the solutions provided by Yokogawa Thailand.”Mr. SahudsaPlant dataGenerating capacity: 22.5 MW (internal 2.5 MW)Fuel: Rice husksDaily fuel requirement: 500 - 600 tons at maximum capacityBoiler: 91 t/h, 65 bar, MacburneySteam turbine: Shin NipponDaily water requirement: Approximately 2,200 m3Precipitator system: Electrostatic precipitator capable of detecting 99.5% of particulatesSuccess Story Collection18A.T. Biopower Co., Ltd / Thailand