改進(jìn)精餾塔模型用于空分塔模擬計算

第18卷第2期計算機與應用化學(xué)Vol. 182001年3月28日d Applied ChemistryMarck改進(jìn)精餾塔模型用于空分塔模擬計算李翠清任曉光殷國蓉陳茂偉北京石油化工學(xué)院化學(xué)工程系,北京102600)摘要∶在傳統的機理模型(三對角矩陣法中的泡點(diǎn)法)基礎上,將體系壓力(P),平衡液相組成(x,x2,x3)為輸入節點(diǎn);體系溫度(T),平衡汽相氮組成(y)及氬、氧的相平衡常數(k2,k3)為輸岀節點(diǎn)的神經(jīng)網(wǎng)絡(luò )液體空氣汽液平衡計算模型,取代三對角矩陣法中泡點(diǎn)計箅,從而建立改進(jìn)的精餾塔模型。改進(jìn)模型用于空分塔的模擬計算,不僅計算速度快,計算結果與機理模型結果非常接近,且符合設計要求,對實(shí)現產(chǎn)品質(zhì)量的在線(xiàn)監控具有一定的指導意義。關(guān)鍵詞∶改進(jìn)模型;精餾塔;模擬計箅中圖法分類(lèi)號:TQ015.9,TQ018,TP183文獻標識碼:A文章編號:1001-4160(201)02-147-15The Simulation of Air Distillation Tower by UsingImproved Model of Distillation TowerLI Cui-qIngRENXⅰ ao-guauang YIN Guo-rong CHEN Mao-WeiDepartment of Chemical Engineering, Beijing Institute of Petroleum Chemical Technology, Beijing 102600)Abstract: Based on the traditional mechanical model( the buble point method of three diagonal matrix ) an neural network modelof gas-liquid equilibrium computation for liquid air, which makes system presure( P)and equilibrium component of liquidphrase( xi,x2,x3) as input nodes makes system temperature( T), equilibrium component of gas nitrogen( yi), equilibriumonstant of argon and oxygen k?, k3 )as output nodes, insteads of the buble point computation of the three diagonal matrix thusa improved distillation model is built. The improved model is applied to simulation of the liquid air distillation tower it not onlyhas rapid compulation speed but computation result is approximate to the mechanical model and meets the demand of the designto the realization of line control of product qu:Key words: improving model distillate1引言將空氣進(jìn)行低溫精餾是獲取高純度氧氣和氮氣的主要途徑,為此,人們進(jìn)行了許多研究1-4。為了調節生產(chǎn)、控制產(chǎn)品質(zhì)量,對空分塔進(jìn)行模擬計算是非常必要的。傳統旳杋理模型法必然涉及液體空氣汽液平衡的計算問(wèn)題5,但由于計算復雜,花費時(shí)間長(cháng),計算結果滯后于實(shí)際生產(chǎn),不利于實(shí)現產(chǎn)品質(zhì)量的在線(xiàn)監控。尋找一個(gè)更為有效的液體空氣汽液平衡模型并用于空分塔的模擬計算顯得十分重要。近年來(lái)迅速發(fā)展起來(lái)的人工神經(jīng)網(wǎng)絡(luò ),以其特有的自適應能力強、反映速度快的特點(diǎn),在石油化工過(guò)程模擬、化工數據處理、化工過(guò)程控制等方面發(fā)揮了優(yōu)勢δ-]本文將神經(jīng)網(wǎng)絡(luò )汽液平衡計算模型與精餾塔機理模型相結合,對液體空氣精餾塔進(jìn)行模擬計算。2神經(jīng)網(wǎng)絡(luò )汽液平衡計算模型1利用BP神經(jīng)網(wǎng)絡(luò )建立液體空氣汽液平衡計算模型。經(jīng)過(guò)計算確定輸入層節點(diǎn)為壓力(P)各組分液相組成(x1、x2、x3);輸出層節點(diǎn)為平衡溫度(T)汽相氮組成(y1)及氬、氧平衡常數(k2、k3)采000-08-04日期:2000-02-12148計算機與應用化學(xué)18卷用帶一個(gè)隱含層的三層B網(wǎng)絡(luò ),隱節點(diǎn)數取10。神經(jīng)網(wǎng)絡(luò )汽液平衡計算模型不僅具有較強的記憶能力,對未參加訓練的樣本也能給岀滿(mǎn)意的預測結果,可用于精餾塔旳模擬計算。3改進(jìn)的液體空氣精餾塔模型傳統的杋理模型法對精餾塔進(jìn)行模擬計算,通常采用三對角矩陣法中的泡點(diǎn)法5。它以平衡級為基本模型,建立MEHS方程。機理模型法存在雙層迭代nitr。gn過(guò)程,內層迭代對每塊板進(jìn)行泡點(diǎn)計算以求解各板的塔板溫度和塔板上各組分的汽相組成;外層迭代用于精餾塔全塔物料平衡和熱量平衡計算。精餾塔expanded air模擬計算時(shí)間主要消耗在汽液平衡的計算上,當理論板數較多時(shí),這一問(wèn)題顯得尤為突出,使計算結ifi.dquid nitro果嚴重滯后于實(shí)際生產(chǎn)過(guò)程,不利于產(chǎn)品質(zhì)量在線(xiàn)監控。本文以某化工廠(chǎng)空分塔下塔為背景(流程簡(jiǎn)圖見(jiàn)圖1),嘗試用神經(jīng)網(wǎng)絡(luò )汽液平衡計算模型代替機理模型中用于泡點(diǎn)計算的模塊,將神經(jīng)網(wǎng)絡(luò )模型與機理模型相結合,建立改進(jìn)的液體空氣精餾塔模seE liquidriching oxycen4計算結果圖1空分塔流程簡(jiǎn)圖將改進(jìn)的液體空氣精餾塔模型用于空分塔模擬計算,其計算結果與機理模型的比較分別見(jiàn)圖2-圖7及表1、表2。101mechanic modelprayer meot1015dthe plate number圖2溫度隨塔板變化曲線(xiàn)板變化曲線(xiàn)Fig 2 Temperature curve changing with plateg 3 Fluid curve of gas and liquid chang期李翠清等:改進(jìn)精餾塔模型用于空分塔模擬計算1492.50E016.11圖6液氧組成隨塔板變化曲線(xiàn)圖7塔板壓力隨塔板變化曲線(xiàn)Fig. 6 The compoent curve of liquid oxygen changing with plateig. 7 The pressure curve of plate changing with plat表1改進(jìn)模型模擬計算結果及其與機理模型相對誤差Table 1 The computation result of improved model and the relative error with the mechanic modelfluid rate offluid rate ofumberpressure,[ atm] temperature, [ K] enthalpy of liquidlative eor,% relative error, phrase, [J/Nm] phrase J/Nm] gas,[ Nm/h] liquid, Nm/hIrelative error, %o relative error, %o Relative error, %o relative error,%6.110054.4139112.684542,03975,89850,00000.01900.02110.18780.10036.113554.4086l12.67865.87140.00160.01330.06130.01240.10196.l17096.8378112.673275.84450.0000.03620.00420.07860.1033345696.8410-54.3953l12.668375.81760.00000.01360.07950.1046.123996.8449-54.3871112.664175.79060.00000.00110.0060.01090.08040.105296.8497-54.377998,43660.00000,00450,01760,08100.10556.1309l12.658498,409575.73590.00000.00720.03570,02340.08130.15596.86254.3570112.657798.381975.70720.00000.08126.1378112.659298.353275.67630.00000.00930.04660.08ll0.10486.141396.8831112.66498.32235.64120.08070.104112.674198.28725,59820,0065917354.3502l12.692998.24475,54150.00000.00350.02680.08180.11006.151754.3883112.724398.18750.01720.086.155254.474112.776375.34230.00000.132054.6474112.85775.16390.00000.00700.21930.01800.09850.13394.89190.00000.03080.1211l13.136497.537874.45070.00000.00580,0180.01710,09310.095373.68580.00000.02100,0725113.925196.331772.49580.00000.00790.07490.00880.09300.16816.176198.582860.4915114.780995.141650.54970.0.172099,5176-63,8563115,967493.507149.03500.00160,00560,01320.01770.0930.1053100,4270-66.7870l17,020491.992447,692150計算機與應用化學(xué)18卷表2改進(jìn)模型模擬計算結果及其與機理模型絕對誤差Table 2 The computation result of improved model and the absolute error with the mechanic modelthe equilibriumthe equilibriumthe equilibriumumbercomponent ofcomponent ofcomponent of gascomponent of gascomponent of gasliquid nitrogenliquid argonliquid oxygenargon0,000010.000010.9330.000000.000000.000000.000000.000000.0000012340.000010.000010.000010.000000.000000.000000.999960.000020,999980.000010.000000.000000,000000,000000.000030.00002000020.000000000.000040.000040.000020.000000.000000.000000.000000.000000.000060.000.000000.000000.000000.000000.999800.000090.000110.999900.000050.000050.0000.000010.000010.000010.999680.999850.000080.000010.000010.000010.00000.000000.99940.000330.999760.000100.000140.000010.00000.0000l00000000.000570.9996I0.000140.000250.000010,0000l0,000020.0000l0.000010.000390.0000430.0000l0.0000.000020.000010.001770.000300.000030.000010.000010.000020.000010.996060,0008200.000430.00135130.000020.993250.001190,996990.000620.000010.988370.001730.00090.004250.000040.000010,000050,000010,0000l0.000020.991100,001320.007570.000.000010.000030.000030.000040.965120.003630.984580.001920,013500.000070.000010.000060.000020.000000.000030.940230.005180.054600.973330.023900.00020.000010.000250.000050.000000.00000.899710.007230.093060.954370.041680.837570.152690.923700.00500.000060.000010.000050.000250.000000.00020.749850.012420.237730.000350.000020.000370.000010.0000l0.670600.014030.315380.83070.008760.16020.00010000000.0001L0.000230.000240.607960.014700.790420.200020.00006改進(jìn)模型模擬計算結果與機理模型模擬計算結果及設計值的比較見(jiàn)表3。表3計算結果比較Table 3 The comparison of computation resultof modelgas nitrogen iniquid oxygen ingas nitrogerexpandedched liquid aiImproved model0.790420.377340.837570.99999Mechanic model0.790360,377190.83763李翠清等∶改進(jìn)精餾塔模型用于空分塔模擬計算5結論將神經(jīng)網(wǎng)絡(luò )液體空氣汽液平衡計算模型與空氣精餾塔杋理模型相結合,建立了改進(jìn)旳精餾塔模型。該模型用于空分塔模擬計算,不僅使模擬計算時(shí)間縮短,而且計算結果與杋理模型計算結果非常接近,符合工藝設計要求,對實(shí)現空分塔產(chǎn)品質(zhì)量的在線(xiàn)監控具有一定的指導意義。此外,建立精餾塔混合模型的方法對其他精餾塔的模擬計算具有一定的借鑒作用。1張占柱,傅舉孚,等,空分裝置精餾系統的計算機設計.深冷技術(shù),1983,41-52 Billingham J F, Olszewski W J, Ricotta JP. 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