201802_Renewable Energy

combustion process, a Yokogawa zirconia oxygen analyzer measures the oxygen content at thefurnace outlet. Based on this data, an oxygen trim control system makes continual adjustments to maintain a constant air/fuelratio.Poultry litter normally contains alkali elements such as sodium and potassium that have a lower melting point and whichare likely to adhere to the furnace’s inner walls and the boiler tubes if the temperature is allowed to go too high, whichreduces combustion efficiency and necessitates frequent maintenance. To keep the temperature within allowable limits, thetemperature of the exhaust gases exiting the furnace must be measured and monitored. To help prevent melted soot fromadhering to surfaces in the furnace and boiler tubes, many blowers have also been installed.The Yokogawa CENTUM CS 3000 system controls all of these processes so that this plant can operate safely and efficiently24/7 and ensure the stable generation of electricity.Smooth startupThis plant is shut down for maintenance approximately 35 days a year. For the cold startup of the boiler system, the furnaceis initially heated up using burning A-type heavy oil. When the furnace reaches the desired temperature, the operators switchover to poultry litter fuel. Each step of the startup sequence is automated by the CENTUM CS 3000 system and graphics onthe system’s human interface stations (HIS) clearly indicate the status of each process. The CENTUM CS 3000 system alsoexecutes an automatic turbine startup (ATS) function. The automation and display of information on the boiler and turbinestartup procedures reduces operator workload and helps to ensure a smooth and safe startup.Odor controlOdor is a significant issue at this biomass waste-to-energy plant. Countermeasures include the use of a forced draft fanto draw air from the poultry litter receiving area and storage silo into the furnace, where it is thermally cracked. Also, theair pressure inside the furnace is maintained at slightly less than atmospheric pressure by means of an induced draft fan,ensuring that no offensive odors are released from the furnace.In summary, the CENTUM CS 3000 production control system and other solutions provided by Yokogawa ensure the safe,efficient, and stable generation of electricity at the MBR facility. Complex feedback control strategies and sequence functionsare all configured in the CENTUM CS 3000 system. With the information provided on the system’s graphic displays, operatorscan stay on top of the entire process and thus are able to see clearly, know in advance, and act with agility.Customer SatisfactionComments from our customer on this solution:“Each day, we incinerate 400 tons of poultry litter, which works out to130,000 tons a year, and generate enough electricity for 17,000 homes.The ash is rich in phosphorus and potassium, and we sell it for use asfertilizer. We have collaborated with local farmers to solve the problemscaused by poultry waste and are contributing to a sustainable society byconverting this poultry litter into electricity and fertilizer. This is a trueeco-recycling system.”“Yokogawa’s system excels in controllability, ensures the early detectionof abnormal conditions in the combustion process, and automaticallytracks each actuator. With this system, we are able to run the plantwith fewer operators while still being able to take quick action in anyemergency. The plant has achieved uptime comparable to that ofconventional fossil fuel power generation plants.”Central control roomOverview graphicPlant dataGenerating capacity: 11,350 kWFuel: Broiler poultry litter (A-type heavy oil at boiler startup)Boiler type: Stoker boiler, 55 t/hSteam turbine type: Condensing extraction turbineStorage silo capacity: 2,500 m3, 2 unitsSuccess Story Collection20Miyazaki Biomass Recycle / Japan

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