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高管式加熱爐熱效率、實現節能減排,而且能夠實現經濟效益與社會效益的共贏。 本設計的管式加熱爐應用于常減壓工藝,綜合給定的加熱爐設計條件、設計要求、加熱爐可能出現的運行情況及經濟效益等因素的限制,對所要設計的管式加熱爐的類型及設計方案進行優化篩選,最終選用兩臺輻射-對流型圓筒加熱爐聯合運行方案。本設計方案的核心部分是管式加熱爐的工藝計算,即:加熱爐總熱負荷計算、燃料燃燒的計算、燃料用量和煙氣流量計算、輻射段及對流段的熱力計算及校核計算、輻射室與對流室的結構尺寸計算、爐內壓力計算、煙氣阻力計算、煙囪理論最低高度計算等。查閱管式加熱爐節能方面的文獻,該設計采用了半預混式瓦斯噴嘴、聲波吹灰器、陶質纖維爐墻結構,并選擇螺桿膨脹機作為煙氣余熱再利用設備,這不僅提高了輻射-對流型圓筒加熱爐的綜合熱效率,還能夠很好的做到節能減排。
關鍵詞:常減壓工藝;輻射—對流型加熱爐;工藝計算;余熱再利用
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Abstract
Tube heating furnace is the main heating equipment in the refinery and one of the major energy-consuming equipment. Tube heating furnace is almost involved in various types of process of oil processing, and is the major equipment to achieve cleavage and conversion reaction, and determines the product quality and energy consumption of the entire refinery or device. In today's extremely tight energy supply-demand relationship, through rational design, and optimization of the structure of the tube heating furnace system, it can not only improve thermal efficiency of the tube heating furnace, achieve energy conservation, but also achieve win-win economic and social benefits. The tube heating furnace in this design is applied to the atmospheric-vacuum technology. In this paper, the given design conditions, design requirements and the possible operations that may arise and economic benefits and limiting factors are integrated to optimize and screen the type of the tube heating furnace to be designed and design proposals. The combined operation scheme of two sets of radiation-convection cylindrical heating furnaces is finally chosen. The core part of this design is the process calculation of the tube furnace, that is the calculation of the total heat load of heating furnace, fuel combustion, fuel consumption and flue gas flow, the thermodynamic calculation of the radiation section and convection section and check calculation, the calculation of the structural dimensions of the radiation chamber and convection room, the calculation of furnace pressure, the flue gas resistance, and of the theoretically minimum height of chimney and other calculations. After consulting the literature concerning the energy saving of tube furnaces, this design adopts the semi-pre-mixed gas nozzle, the
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sonic soot blower, the ceramic fiber furnace wall structure and selects the screw expander as the waste heat recycling equipment of flue gas, which not only improves the overall thermal efficiency of the radiation-convection cylindrical heating furnace, but also achieves energy conservation and emission reduction.
Key words : Atmospheric-vacuum process;Radiation-convection type heating furnace;Process calculation;Recyling of waste heat
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目 錄
1 引 言 ................................................................................................................................................. 1
1.1 選題的依據及意義 ............................................................................................................. 1
1.2 國內外煉化工藝加熱爐節能技術應用現狀及發展趨勢 ......................................... 1
1.2.1 國外煉化工藝加熱爐節能技術應用現狀 ....................................................... 1
1.2.2 國內煉化工藝加熱爐節能技術應用現狀 ....................................................... 2
1.2.3 煉化工藝加熱爐節能技術發展趨勢................................................................. 2
1.3 設計的創新點 ...................................................................................................................... 3
1.4 設計方案 ............................................................................................................................... 3
2管式加熱爐工藝計算 ...................................................................................................................... 4
2.1 計算設計熱負荷及加熱爐選型 ...................................................................................... 4
2.1.1 計算設計熱負荷 ..................................................................................................... 4
2.1.2 爐型選擇................................................................................................................... 6
2.2 燃燒過程計算 ...................................................................................................................... 6
2.2.1計算燃料的熱值 ...................................................................................................... 7
2.2.2 計算理論空氣量 ..................................................................................................... 8
2.2.3 選取過?諝庀禂导凹訜釥t排煙溫度 ............................................................ 8
2.2.4 計算加熱爐熱設計效率 ....................................................................................... 9
2.2.5 燃料氣用量 ........................................................................................................... 10
2.2.6 計算煙氣流量 ...................................................................................................... 10
2.3 輻射室熱力計算 .............................................................................................................. 11
2.3.1 估算輻射段熱負荷 ............................................................................................. 11
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2.3.2 選取輻射室爐管表面熱強度 ........................................................................... 12
2.3.3 估算輻射室爐管管壁溫度 ................................................................................ 13
2.3.4 計算輻射室爐管加熱表面積 ........................................................................... 14
2.3.5 確定輻射室爐管管程數、管徑及管心距 .................................................... 14
2.4 輻射室爐體尺寸 .............................................................................................................. 15
2.4.1 輻射爐管的節圓直徑、有效長度 .................................................................. 15
2.4.2 輻射爐管根數 ...................................................................................................... 16
2.4.3 輻射段爐膛直徑 .................................................................................................. 16
2.4.4 輻射段爐膛高度 .................................................................................................. 17
2.5對流室爐體尺寸................................................................................................................ 17
2.5.1 對流室爐管管徑、管心距 ................................................................................ 18
2.5.2 對流室爐管管長及對流室寬度 ....................................................................... 18
2.6 輻射段傳熱核算 .............................................................................................................. 21
2.6.1 當量冷平面 ........................................................................................................... 21
2.6.2 總輻射交換因數 .................................................................................................. 22
2.6.3 輻射段熱平衡 ...................................................................................................... 23
2.6.4 輻射段煙氣出口溫度 ......................................................................................... 24
2.6.5 核算輻射段熱負荷 ............................................................................................. 25
2.6.6 核算輻射段表面熱強度 .................................................................................... 26
2.6.7 核算輻射段油料入口溫度及輻射段爐管壁溫 ........................................... 26
2.7 對流段的傳熱計算 .......................................................................................................... 27
2.7.1 對流段熱負荷 ...................................................................................................... 27
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2.7.2 對流段內的傳熱平均溫差 ................................................................................ 27
2.7.3 對流室爐管內膜傳熱系數 ................................................................................ 28
2.7.4 對流室爐管外膜傳熱系數 ................................................................................ 29
2.7.5 對流管的總傳熱系數 ......................................................................................... 32
2.7.6 對流室內爐管表面積及管排數 ....................................................................... 32
2.7.7 對流爐管的表面傳熱強度 ................................................................................ 33
2.8 過熱蒸汽段計算 .............................................................................................................. 33
2.8.1 過熱蒸汽段煙氣平均溫度 ................................................................................ 33
2.8.2 過熱蒸汽段兩種介質換熱的平均溫差 ......................................................... 34
2.8.3 管內介質的質量流速 ......................................................................................... 34
2.8.4 過熱蒸汽管的對流傳熱系數 ........................................................................... 35
2.8.5 過熱蒸汽段爐管表面積及管排數 .................................................................. 37
2.9 爐管壓降計算(有相變化) ........................................................................................ 38
2.9.1 汽化段壓力降 ...................................................................................................... 38
2.9.2 加熱段壓力降 ...................................................................................................... 44
2.9.3 加熱爐爐管總壓力降 ......................................................................................... 46
2.9.4 加熱爐爐管入口壓力 ......................................................................................... 46
2.10 煙囪計算 .......................................................................................................................... 46
2.10.1 煙氣通過對流段的阻力 .................................................................................. 46
2.10.2 煙氣由輻射段到對流段的阻力 .................................................................... 48
2.10.3 煙氣由過熱蒸汽段到煙囪的阻力 ................................................................ 49
2.10.4 煙氣在煙囪擋板處的阻力 ............................................................................. 49
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2.10.5 煙氣在煙囪內的摩擦損失 ............................................................................. 50
2.10.6 煙氣在煙囪內的動能損失 ............................................................................. 51
2.10.7 煙囪高度 ............................................................................................................. 51
3 輻射—對流型圓筒加熱爐爐管系統的選用......................................................................... 56
3.1 爐管材料的選擇 .............................................................................................................. 56
3.2 釘頭管 ................................................................................................................................ 56
3.3 爐管吊鉤 ............................................................................................................................ 57
3.4 爐管拉鉤 ............................................................................................................................ 57
3.5 看火門 ................................................................................................................................ 58
3.6人孔門 ................................................................................................................................. 58
3.7 防爆門 ................................................................................................................................ 60
3.8 清掃門 ................................................................................................................................ 61
4 輻射—對流型圓筒加熱爐結構的選用 .................................................................................. 62
4.1 加熱爐主體結構 .............................................................................................................. 62
4.1.1 輻射室結構 ........................................................................................................... 62
4.1.2 對流室結構 ........................................................................................................... 62
4.1.3 爐底結構................................................................................................................ 63
4.1.4 爐墻結構................................................................................................................ 63
4.2 加熱爐附件結構 .............................................................................................................. 64
4.2.1 噴嘴 ......................................................................................................................... 64
4.2.2 平臺、梯子 ........................................................................................................... 64
4.2.3 吹灰器 .................................................................................................................... 65
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5 優化煙氣余熱再利用方案 ........................................................................................................ 67
5.1 煙氣酸露點溫度 .............................................................................................................. 67
5.2 余熱再利用方案 .............................................................................................................. 67
5.2.1 國內外煙氣余熱再利用方案 ........................................................................... 67
5.2.2 設計采用的煙氣余熱再利用方案 .................................................................. 69
結 論 ................................................................................................................................................... 71
謝 辭 ................................................................................................................................................. 72
參考文獻 ............................................................................................................................................ 73
附 錄 ................................................................................................................................................. 76
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