本文選題：近零排放系統(tǒng)　切入點：煤加氫氣化　出處：《北京交通大學(xué)》2014年博士論文

【摘要】：依靠電力運(yùn)行的載運(yùn)工具,動力大多來自燃煤電站,對于以氣為動力源的載運(yùn)工具,若能利用煤制合成氣,也能夠充分適應(yīng)我國“富煤、貧油、少氣”的能源結(jié)構(gòu)特點。因此,研究開發(fā)新型高效潔凈煤利用與轉(zhuǎn)化技術(shù)對我國而言意義重大。本文以一種煤基近零排放發(fā)電系統(tǒng)(ZEC:Zero Emission Coal)為研究對象,首先分析了系統(tǒng)的整體運(yùn)行特性,然后對系統(tǒng)內(nèi)的煤加氫氣化模塊進(jìn)行了深入分析研究。 首先,根據(jù)ZEC系統(tǒng)的思想,本文建立了ZEC系統(tǒng)整體模型,并對系統(tǒng)的主要運(yùn)行單元進(jìn)行了驗證。分析了氫氣循環(huán)率風(fēng),鈣碳摩爾比Rctc以及燃料電池的燃料利用率Uf等主要參數(shù)對系統(tǒng)能量效率Een、(?)效率Eex、總能量效率Eten和總(?)效率Etex以及CO2捕集效率Rcs的影響,提出所建系統(tǒng)的最優(yōu)運(yùn)行參數(shù)為Rh=0.75,Rctc=1.5以及Uf=0.8。在該運(yùn)行參數(shù)下,系統(tǒng)的Een為36.2%,Etom為46.8%, Eex為35.7%,Etex為46.2%,Rc,為87.4%。隨后,計算分析了系統(tǒng)中各個單元的能量和(?)的平衡關(guān)系,對比了系統(tǒng)各單元能量和(?)損失的大小,發(fā)現(xiàn)汽輪機(jī)中的能量損失最大,而燃料電池中的(?)損失最大,由此指出為了進(jìn)一步提升系統(tǒng)的運(yùn)行效率需要降低燃料電池內(nèi)高品質(zhì)能量的過大損失。 在對ZEC系統(tǒng)整體性能進(jìn)行了全面研究后,本文著重對其中的煤加氫氣化模塊從零維熱力學(xué)平衡模型、零維化學(xué)反應(yīng)動力學(xué)模型、三維數(shù)值模擬以及試驗研究等方面進(jìn)行了深入探析。首先,考慮到熱力學(xué)平衡模型良好的通用性以及采用熱力學(xué)平衡模型對煤加氫氣化的研究仍不充分,本文建立了煤加氫氣化熱力學(xué)平衡模型,驗證了模型的可靠性,并利用該模型對煤的加氫氣化特性進(jìn)行了預(yù)測。若對氣化溫度進(jìn)行控制,則當(dāng)壓力pt為7MPa,反應(yīng)溫度T為1000K時,氫煤質(zhì)量比Rh/c為0.25左右可以使氣化產(chǎn)物中甲烷具有較高的摩爾分?jǐn)?shù)。若不控制氣化溫度,則當(dāng)pt為7MPa時,Rh/c為約0.5時,煤中的碳才能夠完全轉(zhuǎn)化。 其次,鑒于煤加氫氣化過程的動力學(xué)計算模型尚不完善,本文建立了煤加氫氣化動力學(xué)模型,驗證了模型的可靠性,并利用該模型對煤加氫氣化特性進(jìn)行了預(yù)測分析。當(dāng)pt為13MPa,反應(yīng)時間t為10s,其他運(yùn)行參數(shù)保持和基準(zhǔn)運(yùn)行參數(shù)一致時,煤粉整體轉(zhuǎn)化率CCR可達(dá)90%,合成氣中CH4的摩爾分?jǐn)?shù)MMF可達(dá)32%,H2摩爾分?jǐn)?shù)HMF約占60%。當(dāng)其他運(yùn)行參數(shù)保持和基準(zhǔn)運(yùn)行參數(shù)一致時,如果T不超過1273K,則增加T可以從整體上促進(jìn)煤加氫氣化反應(yīng)的進(jìn)行。如果T高于1273K,增加T會對煤的加氫氣化反應(yīng)起到抑制作用。 由于鮮見國內(nèi)外對煤的加氫氣化爐三維數(shù)值模擬結(jié)果的報道,本文完善了煤的加氫氣化動力學(xué)模型,提出了針對氣固異相反應(yīng)的“帶有壓力修正的聯(lián)合隨機(jī)孔隙-未反應(yīng)碳縮核模型(CRPSC-PC:Combined Random Pore and Shrinking Core Model with Pressure Correction)",在此基礎(chǔ)上針對氣流床煤加氫氣化爐建立了帶有化學(xué)反應(yīng)的氣固兩相流三維數(shù)學(xué)模型,并借助商業(yè)軟件Fluent對該模型進(jìn)行求解,在所用的模擬方法得到驗證后,利用該模型對某氣化爐的加氫氣化特性進(jìn)行了預(yù)測分析。經(jīng)過綜合分析發(fā)現(xiàn),該氣化爐的最佳運(yùn)行工況組合為pt=7MPa,Rh/c,＝0.4,氧氫質(zhì)量比Ro/h=1.5。在這一運(yùn)行條件組合下,Rchar為96.78%,MMF為17.42%,冷氣效率CGE為76.4%。 最后,考慮到煤加氫熱解和氣化的動力學(xué)基礎(chǔ)數(shù)據(jù)尚不完善,本文對一種褐煤、一種煙煤進(jìn)行了加壓熱重分析,研究了不同壓力下褐煤、煙煤的失重曲線、失重速率曲線,獲得了反應(yīng)動力學(xué)特性的典型參數(shù),確定了反映褐煤、煙煤加氫熱解和加氫氣化的動力學(xué)機(jī)理函數(shù)并計算了不同壓力下褐煤、煙煤的動力學(xué)參數(shù),分析了不同壓力下褐煤及煙煤加氫熱解和加氫氣化過程的動力學(xué)補(bǔ)償效應(yīng)。
[Abstract]:In this paper , a coal based near zero emission power generation system ( ZEC : Zero Emission Coal ) is used as the research object , and the overall operating characteristics of the system are analyzed firstly , and then the coal hydrogasification module in the system is deeply analyzed .

Firstly , according to the idea of ZEC system , the whole model of ZEC system is established , and the main operating units of the system are verified . The system energy efficiency Een is analyzed by analyzing the main parameters such as hydrogen circulation rate wind , calcium carbon molar ratio Rctc and fuel utilization rate Uf of fuel cell . The effects of efficiency Eex , total energy efficiency Eten and total ( ? ) efficiency Etex and CO2 capture efficiency Rcs show that the optimal operating parameters of the proposed system are Rh = 0.75 , Rctc = 1.5 and Uf = 0.8 . In this operating parameter , the Een of the system is 46.8 % , Eex is 38.7 % , Etex is 46.2 % , Rc is 87.4 % . Then , the maximum energy loss is found in the steam turbine , and the loss of ( ? ) in the fuel cell is maximum . Therefore , it is pointed out that in order to further improve the operating efficiency of the system , it is necessary to reduce the excessive loss of high - quality energy in the fuel cell .

After a comprehensive study on the overall performance of the ZEC system , this paper focuses on the deep analysis of the coal hydrogasification module from zero - dimensional thermodynamic equilibrium model , zero - dimensional chemical reaction kinetic model , three - dimensional numerical simulation and experimental research .

Secondly , because the dynamic calculation model of coal hydrogasification process is not perfect , this paper establishes a coal hydrogasification kinetic model , verifies the reliability of the model , and utilizes the model to predict the coal hydrogasification characteristics . When the pt is 13MPa , the reaction time t is 10 s , the other operating parameters are kept consistent with the reference operating parameters , the total conversion of the coal is up to 90 % . If T is not more than 1273K , the increase of T can promote the coal hydrogasification reaction from the whole . If T is higher than 1273K , the increase of T will inhibit the hydrogasification reaction of coal .

In this paper , a three - dimensional mathematical model of gas - solid two - phase flow with pressure correction for gas - solid heterogeneous reaction is established , and the simulation method is used to predict the hydro - gasification characteristics of a gasification furnace . After the simulation method is verified , the optimal operating conditions of the gasification furnace are as follows : pt = 7MPa , Rh / c , = 0.4 , mass ratio Ro / h = 1.5 . Under the condition of operation , Rchar is 96.78 % , the MMF is 17.42 % , and the cold air efficiency is 76.4 % . In the end , considering that the dynamic basic data of coal hydropyrolysis and gasification is not perfect , this paper studied a kind of lignite , a kind of bituminous coal , and studied the dynamic mechanism functions of lignite and bituminous coal under different pressures . The kinetic parameters of lignite and bituminous coal were determined and the dynamic compensation effects of lignite and bituminous coal under different pressures were calculated .

【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TM611

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本文編號：1725818