成果報告書詳細
管理番号20110000000752
タイトル*平成22年度中間年報 国際連携クリーンコール技術開発プロジェクト クリーンコール技術に関する基盤的国際共同研究 CCS向け高効率酸素燃焼石炭ボイラ実用化のための研究開発(H22~23)
公開日2011/6/23
報告書年度2010 - 2010
委託先名株式会社IHI
プロジェクト番号P10017
部署名環境部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等 (1)酸素燃焼時の腐食環境の評価 ア.雰囲気ガス性状、湿度環境の評価 微粉炭焚きボイラにおいて酸素燃焼を行う場合、ボイラ内雰囲気ガス中のCO2濃度は、空気燃焼時の11~14%と比べて最高で90%超と高くなるため、ボイラチューブ強度を低下させる浸炭発生の恐れがある。浸炭には高温燃焼排ガス中のCO2による直接浸炭と灰中の炭酸塩等による固体浸炭が考えられる。
英文要約Title: Research and Development to Promote Commercialization of High Efficiency Oxyfuel Combustion Boiler for Pulverized Coal with Carbon Capture and Storage (FY2010-FY2011) FY2010 Annual Report.
In oxyfuel combustion boiler for pulverized coal, CO2 concentration in the flue gas is more than 90%, while it is 11 to 14% in conventional air combustion boiler. High CO2 concentration could accelerate carburization of the boiler tube material and could accelerate the formation of alkaline carbonate in ash. And high SOx concentration according to the flue gas recycling could accelerate the formation of sulfide that could accelerate high temperature corrosion. High temperature corrosion test using test coupons was performed under 5 sets of test gas composition as below: Case1; conventional combustion by air without SO2, Case2; conventional combustion by air with SO2, Case3; oxyfuel combustion without SO2, Case4; oxyfuel combustion with SO2, Case5; oxyfuel combustion with SO2 and 15% of CO2 equivalent to in conventional combustion by air. Test temperature was set to 500C, 600C, 700C and 800C. Materials tested were 10 alloys as below: carbon steel; STB410, 3 low Cr alloys; STBA20, STBA22 and STBA24, 9Cr alloy; Ka-STBA28, 3 austenitic stainless steels; Ka-SUS304J1HTB, Ka-SUSTP347HTB and Ka-SUS310J1TB, 2 Ni-based alloys; Alloy617, Alloy263. As the results of gas corrosion test, carbon steel and low Cr alloys showed significant corrosion rates over 600C and these corrosion rates were comparable. Corrosion rate of 9Cr alloy was lower than that of low Cr alloys. Austenitic stainless steels and Ni-based alloys showed low corrosion rates, and Ka-SUS304J1HTB and Ka-SUSTP347HTB showed small increase of corrosion rates at 800C. There was little change in corrosion rates according to the differences between gas conditions at 500C, 600C, and 700C. As the results of synthetic coal ash corrosion test, Austenitic stainless steels and Ni-based alloys showed low corrosion rates at 700C under case1 and case3 gas condition. Corrosion rates under Case2 and Case4, both of which contain SO2, were higher than that under Case1 and Case3. CO2 concentration in gas did not affect the gas corrosion rates of alloys. While the spread of corrosion rates at 700C was observed, Ka-SUS310J1TB which contains more Cr showed lower corrosion rate than other alloys. And Ni-based alloys under Case2 showed higher corrosion rates. Through the observations of cross sections and chemical analysis, conclusion of the test obtained as below: 1. Sulfide can be formed easier at 650C rather than 700C and the increase of sulfide accelerates corrosion rates. 2. Higher Cr content in material inhibits sulfide formation. 3. In high Cr alloy, Sulfide formed locally is observed at the boundary between inner layer and base steel layer. 4. In Ka-SUS310J1TB which contains 25% of Cr, Cr2O3 is formed in skin layer and inhibits the formation of sulfide. 5. Higher CO2 concentration in gas does not affect corrosion rates and sulfide formation. 6. Distribution profile of S in material is same as that of Mo, Nb and Cr. 7. Cu and Ni in the scale condense locally. But the influence is not identified.
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