成果報告書詳細
管理番号20110000001776
タイトル*平成22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2011/12/27
報告書年度2010 - 2010
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。
1-2. 平成22年度の課題
平成22年度は,開発4ヵ年(現在前半2年間を受託中)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,各々初年度の検討を実施した。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。
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-FY2011) FY2010 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 FY2010, the first of the whole 4 year period (the first half of 2 years is contracted), specific test planning of mills, burners, combustion systems and feasibility studies of boiler systems were conducted. Some of test facilities were set up and basic tests have been conducted. The results are shown below.
(1) Mill: Experimental studies on test items, methods, etc. using bench-scale devices for classification and grindability tests were made. A preliminary evaluation test of biomass pellet grindability was conducted using a grindability test device. The possibility of biomass pellet pulverization (disagglomeration to pellet original powder) using vertical roller mills was confirmed. Fundamental grindability tests for intended herbaceous biomass pellets, Miscanthus and Switchgrass, were conducted using the device. The results showed that particle sizes after milling depend strongly on pre-pelletization. However, the results also showed that contrary expectations, particle sizes after milling was finer than before milling. This means that not only disagglomeration but also size reduction were performed.
(2) Burner: We designed a pilot-scale single burner test facility, which makes it possible to evaluate dedicated burners at low oxygen concentrations (approximately 11vol%) mixing flue gas with primary air for safety. We use a heater for flue gas and a gas cooler for adjustment of temperature. As opposed to general types of bituminous coal, intended types of biomass were predicted to be less capable in performing ignition due to coarser particle sizes in higher volatile content while NOx emissions would be higher because of smaller calorific values in similar nitrogen content which means higher amount of nitrogen. For this, we see that better ignition and NOx reduction in the flame are vital.
(3) Combustion system: We have constructed a continuous, stable biomass feeding system for a large-scale combustion test facility with multiple burners in order to demonstrate co-combustion of biomass at 25cal%. This feeding system consists of silos, feeders and feeding pipes etc.
(4) Boiler system: As a pre-study, 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 10 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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