成果報告書詳細
管理番号20120000000949
タイトル*平成23年度中間年報 バイオマスエネルギー技術研究開発 戦略的次世代バイオマスエネルギー利用技術開発事業(実用化技術開発) バイオマス専用粉砕方式による既設微粉炭焚きボイラでの混焼技術の実用化開発
公開日2012/12/21
報告書年度2011-2011
委託先名バブコック日立株式会社
プロジェクト番号P10010
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:1. 共同研究の内容及び成果等
1-1. 研究開発の概要
既設の石炭焚き火力発電所においてバイオマス混焼率を増大する場合,専用のミルを新たに別置する必要があり,所内動力の増加や設置スペースの確保等の課題が生じる。これらに対応するため,追加設備と改造コストを抑制し高い混焼率を確保できる方式を開発条件として設定する。達成手段として,石炭用ミルをバイオマス専用ミルに転用したシステムを構築する。火力発電におけるCO2排出の程度と国内でのCO2排出量削減目標25%を鑑み目標混焼率を25cal%とする。本開発の目的は,既設ミルを活用し混焼率25cal%を達成する燃焼システムを実用化することである。対象とするボイラ・排煙処理設備はシステムとして構成されるので,構成要素毎に,(1)バイオマス粉砕ミルの開発,(2)バイオマス専用バーナの開発,(3) バイオマス燃焼システムの開発,(4) 排ガス処理システムの評価,(5) 実機ボイラ性能予測とシステムの成立性検討を行なう。
平成22年度は,開発4ヵ年の中で実施する項目の(1)各構成要素の中核的装置であるミル及びバーナの開発,(2)燃焼システムの開発,(3)ボイラシステムの構築,に関して,各々主として,試験あるいは検討の計画の具体化,それに基づく装置の設計,製作を行い,平成23年度の試験に備えた。また,供試用のバイオマスの収集を行い,ミルに関してはその要素試験に着手し基礎特性を把握した。
1-2. 平成23年度の課題
平成23年度は,受託2年目の検討として各開発項目について以下を実施する。ミルに関しては,複数種のバイオマスの要素試験評価を完了するとともに,目標の混焼率を達成するための専用粉砕ミル及び混合粉砕ミルの要素試験による構造提案などを行う。バーナに関しては,シングルバーナ試験による燃焼性評価を行う。燃焼システムに関しては,マルチバーナ試験装置によるバイオマス混焼時の燃焼性の総合評価を行う。排ガス処理システムに関しては,システム評価試験の計画を行う。ボイラシステムに関しては,データ収集を行い排ガスを再循環させるシステムの検討を継続する。
英文要約Title: Strategic Future Generation Technology Development Project of Biomass Energy Utilization (Technology Development for Practical Application) / Technology Development for Practical Application of Co-combustion of Biomass in Existing Coal Fired Boilers by means of Biomass Pulverizing Using Dedicated Mills for Biomass (FY2010-FY2013) FY2011 Annual Report
We are developing boiler system technologies to achieve biomass co-combustion ratios of approximately 25cal% at low costs by means of utilizing existing mills. We hope to develop combustion systems including mills and burners by using each test facility, and to construct actual boiler systems using data garnered from these developments. In FY2011, the second of the whole 4 year period, evaluations of grinding performance using a bench-scale device and improved structures for actual mills, evaluations of burners and combustion system using pilot/large-scale test facilities, specific test planning of AQCS(Air Quality Control System) and feasibility studies of boiler systems were conducted. The results are shown below.
(1) Mill: New mills were made in the aim of reliably grinding biomass and coal/biomass mixtures without problems of choking, dust explosion or corrosivity from flue gas. Tests followed in which biomass pellet grindability was confirmed using a special grindability test device. From this, it was newly evidenced that coarser particle occurrence than raw pellet powder in the pulverization process was likely with exception of pulverizing Bark (biomass). From these studies, it was found that the new mill structures accelerated biomass discharge through greater control in classifying performances and that the structures themselves were vastly improved.
(2) Burner: Switchgrass (biomass) combustion tests in a pilot-scale, single burner test facility were conducted. In the facility, a Hitachi NR-LE burner with a flame stabilizer was adopted. A stable rate of combustion was confirmed in primary air with low oxygen concentrations through mixing flue gas to prevent dust explosion. Compared to the combustion of bituminous coal, an equal or lower NOx and CO concentration was confirmed while higher combustion efficiency proved characteristic of biomass combustion.
(3) Combustion system: Co-combustion of biomass at 25cal% was conducted using a large-scale combustion test facility with multiple burners. The fuels evaluated in these tests were Switchgrass (powder of pellets), Cedar (powder of chips) and bituminous coal. In these operations, no problems occurred regarding combustion. Both a stable combustion and NOx reduction were confirmed. Furthermore, under co-combustion conditions, no increase in unburned carbon in ash was seen. All tests were carried out within the biomass range at 20 to 33%.
(4) Air quality control system (AQCS): The plans for a test facility combining a combustion system with an AQCS, a furnace, a NOx removal equipment, a gas-gas heater, an electrostatic precipitator and a SOx removal equipment, were completed.
(5) Boiler system: We looked into a system in which flue gas was partially re-circulated to a biomass mill. The investigation based on co-combustion cases in references mainly in Europe. Balance evaluations of fuel, air, flue gas and flue gas recirculation gas were carried out in the ranges of up to 25 % of biomass co-combustion ratios. From the results, we confirmed (a) Maximum air heater outlet gas temperatures increased, (b) Flue gas flow increased, (c) Required capacity of gas recirculation boost-up fan, and (d) Negligible effects to downstream equipments caused by small changes in flue gas compositions.
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