【正文】 目 錄電站鍋爐后屏過熱器壁溫計算畢業(yè)論文目 錄摘 要 ............................................................................................................................IABSTRACT.......................................................................................................................II目 錄 .........................................................................................................................III第 1 章 緒 論 ............................................................................................................1 課題的選題背景 ..................................................................................................1 國內外研究的現(xiàn)狀 ..............................................................................................1 壁溫計算 ..............................................................................................................3第 2 章 過熱器系統(tǒng)的熱偏差理論分析 ....................................................................5 熱力不均勻性 ......................................................................................................6 沿煙道寬度的熱力不均勻性 .......................................................................6 沿煙道高度( 或深度)的熱力不均勻性 .........................................................7 同屏(片)各管的熱力不均勻性 ....................................................................7 水力不均勻性 ......................................................................................................8 集箱效應引起的流量不均勻性 ....................................................................8 管子結構差異引起的流量分配不均勻性 ...................................................8 熱效流動引起的流量分配不均勻性 ...........................................................8第 3 章 受熱面超溫爆管原因及預防措施綜述 ........................................................9 設計原因造成受熱面超溫、爆管原因綜述 ......................................................9 熱力計算結果與實際不符 ...........................................................................9 爐膜選型不當 ...............................................................................................9 過熱器系統(tǒng)結構設計及受熱面布置不合理 ...............................................9 壁溫計算方法不完善，導致材質選用不當 ..............................................10 制造工藝、安裝及檢修質量對受熱面超溫、爆管的影響 ............................10 聯(lián)箱中間隔板焊接問題 ..............................................................................11 聯(lián)箱管座角焊縫問題 ..................................................................................11 異種鋼管的焊接問題 ..................................................................................11 普通焊口質量問題 .....................................................................................11 管子彎頭橢圓度和管壁減薄問題 .............................................................12 異物堵塞管路 .............................................................................................12 管材質量問題 .............................................................................................12 調溫裝置設計不合理或不能正常工作引起的受熱面超溫爆管的分析 ........12 減溫水系統(tǒng)設計不合理 .............................................................................13 噴水減溫器容量不合適 .............................................................................13 文氏管式噴水減溫器端部隔板漏流及局部渦流 .....................................13東北電力大學本科畢業(yè)論文 噴水減溫器調節(jié)閥調節(jié)性能問題 .............................................................14 再熱器調節(jié)受熱面 .....................................................................................14 擋板調溫裝置 .............................................................................................14 煙氣再循環(huán) .................................................................................................14 火焰中心的調節(jié) .........................................................................................15 鍋爐運行狀況影響受熱面超溫、爆管的幾種情況簡介 ................................15 爐內然燒工況 .............................................................................................16 高壓加熱器投入率低 .................................................................................16 煤種的差異 .................................................................................................16 負荷變化 .....................................................................................................17 汽機高壓缸排汽溫度降低 .........................................................................17 受熱面站污 .................................................................................................17 磨損與腐蝕 .................................................................................................17 運行管理 .....................................................................................................18 預防過熱器管壁超溫的方法 ............................................................................18 結構措施 ......................................................................................................18 運行措施 .....................................................................................................19第 4 章 熱偏差和壁溫計算 ........................................................................................24 熱偏差系數(shù)的計算 ............................................................................................24 結構偏差系數(shù)的計算 .................................................................................24 吸熱偏差的計算 .........................................................................................24 水力偏差系數(shù)的計算 ..................................................................................26 壁溫計算 ...........................................................................................................30第 5 章 屏式過熱器結果分析及應用 ........................................................................35 計算結果 ............................................................................................................35 計算結果應用 ....................................................................................................37 鍋爐安全工作的負荷及燃料限制 .............................................................37 預防超溫的技術方案 ..............