本文關(guān)鍵詞： 合成氨 余熱回收換熱器 改造設(shè)計 T型翅片管 強化傳熱　出處：《華東理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：合成氨尿素工業(yè)廢氣經(jīng)過一級余熱回收后仍然擁有很高的能量,將其直接排放會造成極大的浪費。本文針對某合成氨尿素二級廢熱鍋爐改造,結(jié)合T形翅片管換熱器的結(jié)構(gòu)特點,分析了其沸騰強化傳熱機理,對其進(jìn)行了深入的研究,主要包括以下幾方面的內(nèi)容：(1)對余熱回收技術(shù)及強化沸騰傳熱技術(shù)的研究現(xiàn)狀進(jìn)行了調(diào)研,結(jié)合沸騰傳熱機理,闡述了各種沸騰強化傳熱技術(shù)的優(yōu)缺點。(2)給出了合成氨尿素二級余熱回收鍋爐的熱力模型及工藝計算方法(包括改造前光滑管換熱器及改造后T型翅片管換熱器),并利用手算和HTRI軟件對改造前后兩種換熱器進(jìn)行了工藝分析與設(shè)計計算,發(fā)現(xiàn)現(xiàn)有設(shè)備已經(jīng)無法滿足換熱要求。從強化傳熱角度來看,T型翅片管的管內(nèi)傳熱系數(shù)約為光管的1.22倍,管外沸騰傳熱系數(shù)約為光管的1.24倍,總傳熱系數(shù)是光管的1.6倍。改造后的換熱器在滿足了設(shè)計要求的同時,所需換熱面積明顯低于改造前,大大節(jié)省了改造成本。(3)從換熱器流體誘導(dǎo)振動的機理及振動判定依據(jù)出發(fā),使用GB151附錄E流體誘導(dǎo)振動計算對改造前和改造后的余熱回收換熱器進(jìn)行了流體誘導(dǎo)振動分析。并對比了改造前后兩臺設(shè)備的流體誘導(dǎo)振動分析結(jié)果。計算結(jié)果表示,改造后的新型換熱器殼程不會產(chǎn)生因卡門漩渦或紊流抖振產(chǎn)生管束振動,也不會發(fā)生聲振動,與改造前相比具有更好的抗振性能。(4)利用大型計算流體力學(xué)軟件Fluent對T型翅片管和光滑管管外流動沸騰進(jìn)行了數(shù)值模擬研究,結(jié)合T型翅片管的結(jié)構(gòu)特點,進(jìn)一步說明了該換熱管的強化沸騰傳熱機理。在本文研究的范圍內(nèi),T型翅片管管外沸騰傳熱系數(shù)最大時高于光滑管23.2%,強化傳熱效果明顯。同時,綜合評價了T型翅片管強化傳熱和增加壓降的性能。結(jié)果表明,其強化傳熱綜合性能評價因子在不同流速下均大于1,說明T型翅片管有很好的強化傳熱效果。本文通過對該換熱器上述問題的研究,完成了合成氨二級余熱回收換熱器的設(shè)計改造工作,同時深入探討了改造后換熱器的強化傳熱機理,對于同類余熱回收熱交換器的改造設(shè)計有很強的參考價值。
[Abstract]:The waste gas of ammonia urea industry still has very high energy after the first stage waste heat recovery, and it will cause great waste when it is discharged directly. This paper aims at the revamping of the secondary waste heat boiler of a synthetic ammonia urea. Combined with the structural characteristics of T-shaped finned tube heat exchanger, the mechanism of boiling enhanced heat transfer is analyzed, and the mechanism of boiling enhancement heat transfer is studied deeply. The research status of waste heat recovery technology and enhanced boiling heat transfer technology has been investigated, combined with boiling heat transfer mechanism. The advantages and disadvantages of various boiling heat transfer enhancement techniques are described. (2) the thermodynamic model and process calculation method of the secondary waste heat recovery boiler for ammonia synthesis urea are given. It includes smooth tube heat exchanger before revamping and T finned tube heat exchanger after revamping. The process analysis and design calculation of the two kinds of heat exchangers before and after revamping have been carried out by using manual calculation and HTRI software. It is found that the existing equipment can no longer meet the requirements of heat transfer. From the point of view of enhanced heat transfer. The in-tube heat transfer coefficient of T-shaped finned tube is about 1.22 times of that of the smooth tube, and the boiling heat transfer coefficient outside the tube is about 1.24 times of that of the smooth tube. The total heat transfer coefficient is 1.6 times of that of the smooth tube. The heat transfer area of the modified heat exchanger is obviously lower than that of the former. The cost of revamping is greatly saved. (3) based on the mechanism of fluid-induced vibration of heat exchanger and the basis of vibration determination. The fluid-induced vibration analysis of waste heat recovery heat exchangers before and after revamping was carried out by using fluid-induced vibration calculation in appendix E of GB151, and the results of fluid-induced vibration analysis of two equipments before and after revamping were compared. The result of the calculation indicates. The shell side of the modified heat exchanger will not produce tube bundle vibration or acoustic vibration due to Carmen vortex or turbulent buffeting. Compared with before modification, it has better anti-vibration performance.) numerical simulation of flow boiling outside T-shaped finned tube and smooth tube was carried out by using large computational fluid dynamics software Fluent. The mechanism of enhanced boiling heat transfer of the tube is further explained by the structural characteristics of the T-shaped finned tube. The boiling heat transfer coefficient outside the T-shaped fin tube is higher than that of the smooth tube 23.2% when the maximum boiling heat transfer coefficient is obtained in this paper. The effect of heat transfer enhancement is obvious. At the same time, the performance of enhancing heat transfer and increasing pressure drop of T-shaped finned tube is comprehensively evaluated. The results show that the comprehensive evaluation factor of heat transfer enhancement performance is more than 1 at different flow rates. It shows that T-fin tube has a good heat transfer enhancement effect. Through the study of the above problems of the heat exchanger, the design and transformation of the two-stage waste heat recovery heat exchanger for synthetic ammonia have been completed. At the same time, the mechanism of enhanced heat transfer of heat exchangers after revamping is discussed, which has a strong reference value for the retrofit design of similar waste heat recovery heat exchangers.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ113.25;TQ051.5

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