First Dutch farm-scale gas-to-grid plant commissioned Bioenergy International No 83, 7-2015 43 Central control » For over a decade, Thöni has been working with Siemens to provide electrical components, automation and control for its biogas plants with many successful projects in Germany, Austria, Italy and now the UK. The paddle-mixers are driven by 11 kW planetary gearboxes with Profibus controlled frequency converters. Due to their regenerative capability, they use up to 50 Facts: AgriGen I & II Feedstock: Maize & triticale silage CHP power plants: MWM 500 kW GE Jenbacher 3 MW ORC unit: 2 x GE Clean Cycle 125 kW Storage pit/liquids: 1 x 100 m3 underground concrete vessel Feed pit/liquids, solids: 200 m3 Feed hopper/solids: 2 x 117 m3 1 x 60 m3 Digesters: 2 x 3.000 m3, 2 x 4.000 m3 Gas storage: Double membrane 4 x 1.500 m3 Paddle-mixers: 3 x digester 1 3 x digester 2 3 x digester 3 3 x secondary digester Gas cleaning: External biological scrubber BIOGAS percent less power, and their new cooling concept makes for reliable operation. The smaller propeller mixers use soft starters to avoid highcost performance peaks and protect the mechanical components. Siemens also developed and supplied a range of in-situ monitoring and detection meters and sensors such as temperature and gas pressure. A special feature is the use of radar for contact-free substrate measurement to enable limit detection and overfill protection. The radar sensor technology has been process adapted to overcome the effect of foam when measuring the fill level in the digester. – Siemens is a powerful partner for us, so we as a medium-sized company feel that we have the support we need. We met numerous times throughout the project in many coordination meetings to find the optimum solution for the engineering of interfaces and other components and ultimately found it, commented Urban Zell, Head of Electrical Engineering at Thöni. The technology container houses the central pumping station as well as the electronic control system under one roof. The pumping station especially developed for this application transports liquids and substrates economically and efficiently from one point to another. The pumping technology is so flexible in design that it supports all combinations of flow paths. This saves energy, time and costs, while permitting problem free operation of the plant. The operator can centrally monitor all factors important for operation of the plant via the controller and visualization software developed by Siemens, and intervene at any time. These automation components from Siemens, which have been tested in many plants set up in cooperation with Thöni, enable precise plant operation, exact monitoring of each individual component from input until output, and easy control of the plant. – Thöni and Siemens had built the original AgriGen I plant, which meant it was clear that they would also build the expansion. The challenge was the expansion during operation. The project execution time was also very short and had to take place without any problems. In the long term, the plan is to refine the biogas from the AD plant to use for drying the onions and invest in heat exchange systems to run the cooling systems required for the longer-term storage of onions, ended Graham Thorne. Text: Alan Sherrard Photos courtesy Thöni BI83/5045/AS Weltec break ground for projects in Australia and South Korea Germany-based biogas technology specialist, Weltec Biopower have together with its project partner Aquatec Maxcon begun construction of what is described as one of Australia’s most innovative biogas projects and the first to built by a German biogas technology provider. The 1 MW plant is being built in Aurora a suburb of Melbourne, New South Wales (NSW) for Yarra Valley Water, one of Australia’s largest water utilities and will be one of the first of its kind Down Under. The few biogas plants that are currently online in Australia mainly utilise sewage sludge and industrial wastewater. Mixed feedstock Two 3 573 m³ capacity stainlesssteel digesters will be fed with 100 tonnes of organic waste per day over half of which will come from cafeterias and restaurants. The rest will comprise of fats and oils, brewery and dairy leftovers, fruit and vegetable waste and sludge that will be pumped from the adjacent wastewater treatment plant. After the digestion process, the substrate will be sanitised and then buffered in a 4 531 m³ stainless-steel tank. A custom-tailored input process will be set up to ensure uninterrup- At a dairy farm in Den Bommel, the Netherlands, the gas meter recently passed the first 10 000 m3 of biomethane injected into the grid. Since October 2015, the plant is producing biomethane out of 100 percent cattle manure with direct injection into the Dutch national gas grid. Designed and supplied by Dutch biogas technology providers HoSt, the plant consists of a Microferm digestion tank, a gas tight after storage, a container with the biogas upgrading and control panel, and a skid on which the biogas treatment, manure heat exchanger and heat pump are mounted. The Microferm digestion unit has the capacity to treat 8 000 tonnes of cattle manure annually and is specifically designed to digest manure at farmscale, without the addition of cosubstrates. Unique to this project is the upgrading of the biogas into biomethane with direct grid injection. The plant is estimated to produce 180 000 – 200 000 m3 biomethane annually. It is the first plant in the Netherlands where 100 percent manure is digested, upgraded to biomethane and injected into the grid on this small scale. BI83/5126/AS ted supply of the biogas plant. At the delivery area, the feedstock will first be loaded into two 35 m³ solid hopper feeder. Some of the substrates, such as melon peels, will first be shredded and then further chopped up with other raw materials and mixed with recirculation fluid in the MULTIMix system. After this preliminary treatment, the mixture will be pumped into the largest of the five stainless-steel pre-storage tanks with a total volume of almost 700 m³. The process is fully automated except for the loading of the input systems. However the size design of the pre-storage tanks ensures that no loading and thus no manpower will be required at night or weekends. Second plant in South Korea Weltec has also announced that it has begun construction of a 450 kW biogas plant in Gyeonggi-do province about 80 km north of the capital Seoul. A 4 000 m3 stainlesssteel digester will use 100 tonnes of pig manure and organic waste a day as feedstock. The biogas will be used for heat and power, with the latter fed to the grid. The heat will be used for heating the company buildings and for internal processes and the digestate will be stored in two 5 590 m3 stainless-steel storage units before use as high-grade fertiliser. BI83/5115/AS
Bioenergy International no 7 December 2015
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