【正文】 iable operation of the superheater and reheater that are the key ponents of the largecapacity power station boiler is very significant for the whole units without doubt. With the enlargement of the installed capacity,the overheating and tube rupture of the boiler superheat system frequently happen because of thermal deviation, which seriously affects the safe and economy operation of generating plant. On account of the related fact above, research into the causes of the thermal deviation, the calculation method of the thermal deviation and the wall temperature are greatly important. But most researches into the causes of the thermal deviation often are thrown into some a side, few carry out an allround and systematic theoretical analysis, and many manufactures calculate the wall temperature popularly according to the old standard method about the heat calculation of the Soviet Union, this method is suitable for the last boiler unit of small capacity and low parameter, but as to largecapacity and high parameter power station boilers today, it will bring some problems inescapably. At the same time,according to the causes of the thermal deviation, the measures or schemes to decrease the thermal deviation have been put forward. This dissertation puts the calculation patterns established into practical use, taking the thermal condition of the 330MW subcritical pressure concurrent boiler of the Jilin Jiangnan Power Plant as an example, and gives a profound analysis on the main causes of the thermal deviation. The calculation results of the thermal deviation prove it appropriate that the calculation method is taken, for the results can accord with the factual thermal deviation condition. So this dissertation can provide a certain reference value and practical direction for the optimum design of the heatexchanger surface and the accident analysis. Key words: Boiler； Superheater； Thermal deviation； Wall temperature；Overheating and tube rupture 目 錄 III 目 錄 摘 要 ........................................................................................................................... I ABSTRACT ................................................................................................................ II 目 錄 ......................................................................................................................... III 第 1 章 緒 論 ...........................................................................................................1 課題背景 .........................................................................................................1 國內(nèi)外研究成果和發(fā)展動態(tài) .........................................................................2 課題研究的內(nèi)容與方法 .................................................................................3 第 2 章 過熱器系統(tǒng)的熱偏差理論分析 ..................................................................1 概述 .................................................................................................................4 過熱器熱偏差概念敘述 .................................................................................4 煙氣側(cè)熱偏差 的 原因 .....................................................................................5 蒸汽側(cè)流量偏差原因 .....................................................................................8 第 3 章 過熱器熱偏差基本計算方法 ....................................................................11 概述 ............................................................................................................... 11 熱負(fù)荷不均系數(shù)計算 ................................................................................... 11 熱偏差計算相關(guān)參數(shù)的確定 ........................................................................14 并聯(lián)管組流量偏差計算 ...............................................................................17 熱偏差系數(shù)計算 ...........................................................................................22 金屬壁溫計算 ...............................................................................................23 實(shí)例鍋爐介紹 ...............................................................................................25 實(shí)例應(yīng)用計算結(jié)果 .......................................................................................26 第 4 章 減小熱偏差的措施 ....................................................................................29 減小煙溫偏差的措施 ....................................................................................29 減少蒸汽側(cè)偏差的措施 ...............................................................................32 結(jié) 論 .........................................................................................................................32 致 謝 .........................................................................................................................33 參考文獻(xiàn) .....................................................................................................................36 第 1 章 緒 論 1 第 1 章 緒 論 課題背景 隨著我國電力工業(yè)的發(fā)展，火力發(fā)電機(jī)組的裝機(jī)容量不斷增大， 300MW、600MW 機(jī)組已成為電網(wǎng)中的主力機(jī)組，這部分機(jī)組運(yùn)行質(zhì)量的優(yōu)劣對整個電網(wǎng)運(yùn)行的可靠性、經(jīng)濟(jì)性有著非常重要的影響。因此，論文在關(guān)于熱偏差成因的綜合理論分析基礎(chǔ)之上，建立受熱面合理的蒸汽流量分配計算模型、熱偏差計算模型和壁溫計算模型，摒棄原有計算方法中的不足，采取適于工程應(yīng)用的計算方法，以實(shí)現(xiàn)準(zhǔn)確地反映受熱 面出口汽溫和管子壁溫分布情況。過熱器和再熱器作為鍋爐機(jī)組重要的部件，其可靠運(yùn)行無疑對整個機(jī)組的安全運(yùn)行有著非常重要的意義。隨著機(jī)組容量的增大，鍋爐過熱系統(tǒng)因熱偏差引起的超溫爆管事故頻頻發(fā)生，嚴(yán)重影響了發(fā)電廠的安全、經(jīng)濟(jì)運(yùn)行。同時，依據(jù)熱偏差的成因提出相應(yīng)的減小措施或預(yù)防對策。過熱器和再熱器作為鍋爐機(jī)組的重要部件，其可靠運(yùn)行對整個機(jī)組的安全運(yùn)行無疑有著非常重要的意義。我國制造的某些機(jī)組高檔合金鋼的使用量往往大于從國外引進(jìn)的同類機(jī)組，這對于我國的機(jī)組在國際電力 市場中的競爭也是一個極為不利的因素。大量運(yùn)行實(shí)踐表明，采用以往計算方法設(shè)計的受熱 面最大允許壁溫往往偏低，而且壁溫變化規(guī)律不合理，甚至同國外先進(jìn)設(shè)計結(jié)果相反。 多年來，國內(nèi)鍋爐技術(shù)人員對切向燃燒鍋爐的熱偏差問題進(jìn)行了不斷的探討和研究，取得了不少的成果。對于大量采用的異徑三通引起的渦流問題和過熱系統(tǒng)的優(yōu)化設(shè)計問題，沒有進(jìn)行全面的科研攻關(guān)。 引起鍋爐過熱器受熱面熱偏差、造成超溫爆管事故的原因復(fù)雜多樣，為系統(tǒng)分析與研究熱偏差的成因和因素的影響規(guī)律，課題布置了以下內(nèi)容： 第 1 章 緒 論 3 課題研究內(nèi)容與方法 課題研究內(nèi)容 引起鍋爐過熱器受熱面熱偏差、造成超溫爆管事故的原因復(fù)雜多樣，為系統(tǒng)分析與研究熱偏差的成因和因素的影響規(guī)律，課題布置了以下 內(nèi)容： （ 1）典型燃燒方式下的煙氣側(cè)熱偏差分析，以四角切向燃燒方式為重點(diǎn)，具體分析造成煙速、煙溫偏差的爐內(nèi)燃燒過程特點(diǎn)，涉及爐膛結(jié)構(gòu)特點(diǎn)及尺寸，燃燒器結(jié)構(gòu)、系統(tǒng)布置及層數(shù)投停方