18000Nm3h热管式余热回收系统的设计

18000Nm3/h热管式余热回收系统设计一、设计条件空气进口温度20℃烟气进口温度280℃空气出口温度200℃烟气出口温度150℃空气流量18000Nm3/h二、设计流程（1）热管原件的基本选择管壳选择：20号无缝钢管，钝化处理翅片选择：10号钢，高频焊翅片管内工质：水热管形式：重力热管热管的几何尺寸：光管外径d0=32㎜；壁厚0=3.5㎜；翅片型式：螺旋式翅片，冷热流体侧的翅片几何、结构相同翅片长度fl=15㎜；翅片外径fd=62㎜；翅片厚度f=1.4㎜；翅片间距Y=4㎜；翅片节距f=f+Y=5.4㎜；每米管长的翅片数fn=f1=10001585.4m片；热管换热器管子排列形式为等边三角形，如图：横向管子中心距81TSmm；81LTSSmm（2）计算传热量Q①烟气的定性温度hfthft=221hhtt=2501502152℃查得定性温度下烟气的参数为：定压比热容hpC=1.1008kJ/ckg；密度hf=0.7284kg/m3；导热系数hf=4.1345210W/(mC）；黏度hf=25.057610kg/(ms)；普朗特数Prh=0.667②空气侧定性温度及参数定压比热容cpC=1.009kJ/kgC；密度cf=0.922kg/m3；导热系数cf=3.275210W/(mC)；黏度cf=22.35610kg/(ms)；普朗特数Prc=0.687③冷空气侧实际获得的热量Qcc'21()cccccfpQVCtt180001.2931.009200203600=1174.2kW（）（假设标况下，cf取为1.293kg/m3。）考虑冷侧3%的热损，故：1174.213%1210.49cQ=（）kW④烟气放出热量hQ考虑冷侧3%的热损，故：hQ1210.49(13%)=1248kW⑤烟气的流量12()hhhhhhfpQVCtt31248360024246Nm/h1.2951.1008(280150)⑥对数平均温差tmtm=1212tttlnt1502028020015020ln280200=103℃（3）确定迎风面积exA及迎风面管排数B选取烟气侧和空气侧迎面风速为2.5m/s（在2-3m/s之间选取）。①烟气侧迎风面积1hexA以及空气侧迎风面积1cexA1hhexhNVAw2242462.694m2.536001ccexcNVAw2180002m2.53600②迎风面宽度E取热侧长lh=1.8m则hexhAEl2.6941.81.4966m可得冷侧长ccexAlE2/1.49661.33m迎风面管排数TEBS1.496618.470.081取B为19根实际迎风面宽度TEBS190.0811.539m③两侧实际迎风面积hhexAEl21.5391.82.77mccexAEl21.5391.332.067m④两侧实际迎面风速hhNhexVwA242462.43m/s2.773600ccNcexVwA180002.44m/s2.0673600中间隔板厚la=30mm，预留安装段ls=35mm热管元件总长度llh+lc+la+2ls=3.23m（4）求总传热系数HU①、管束最小流通截面积NFANFAh=h02TfffSdlnBl=20.080.03220.0150.0014185191.81.41mNFAc=c02TfffSdlnBl20.080.03220.0150.0014185191.331.042m②、流体最大质量流速Gmax热侧：maxhhffhhVGNFA2242461.29522267.4kg/mh1.41（）冷侧：ccfcfcNFAVGmax2180001.29322338.4kg/mh1.042（）③、求Ref热侧：max0RehhfhfGd622267.40.032789925.057103600冷侧：cfccfdG0maxRe622338.40.032888422.35103600④、求流体的换热系数fh由316338.0PrRe137.0ffNu计算换热系数热侧：1120.63380.63383304.1345100.137RePr0.13778990.6670.032hfhhhffhd=45.672W/mC（）冷侧：11c20.6338ccc0.6338f33ff03.27510h0.137RePr0.13788840.687d0.032=32.532W/(mC)⑤、求翅片效率f94.11615160rrf，故取20rrf热侧：fwhfhfhl2245.670.0150.55480.0014冷侧：fwcfcfhl2239.30.0150.50500.0014由图3—71查得，hf=083，cf=0.84⑥、求每米长热管管外总表面积hA每米长热管的翅片表面积fA为：22024fffffAdddn2222(0.0620.032)0.0620.00121850.8695m4；每米长翅片间管表面积rA为：01rffAdn3.140.032(11850.0014)20.0745m；每米热管管外总表面积hA为：hrfAAA20.86950.07450.944m单根热管两侧总面积热侧：hhhhAAl20.9441.81.699m冷侧：cchhAAl20.9441.331.255m中径传热面积热侧：hhwwAdl23.140.02851.80.161m冷侧：ccwwAdl23.140.02851.330.119m内径传热面积热侧：hhiiAdl23.140.0251.80.141m冷侧：cciiAdl23.140.0251.330.104m⑦、求管外有效换热系数fehhhhfhfhrhfhfeAAAhh)(热侧：45.670.07450.830.869538.50.9442W/(mC)；chcfcfcrcfcfeAAAhh)(冷侧：39.30.07450.840.869533.50.9442W/(mC)⑧、求污垢热阻ry及管壁热阻rw查《换热器原理与设计》附录D，取值0.00017hyr热侧：2mC/W0.000086cyr冷侧：2mC/W金属管壁热阻：hwwhwr0.00350.0000875482mC/Wcwwcwr0.00350.00007502mC/W⑨、求总传热系数hHU5810hcHPHPhh2W/mC,11hhhhhhhhwyhhhhhhHfewyHPiAAArrUhAAhA11.6991.6990.00008750.0001738.50.16158100.14111ccccchhhwyccccccHfewyHPiAAArrUhAAhA11.4161.4160.000070.00008633.50.13458100.118可得hHU234.34W/mC,cHU230.59W/mC,11111134.3430.59HhcHHUUU216.18mC/W（5）求放热侧总传热面积AHh1210.49100016.18103ccHHmQAUt2726.7m（6）求所需热管数n、726.75791.255cHchAnA根（7）求换热器纵深排数m57930.4m3219nmB排，取排排列方式：191819181918191819181918191819181918191819181918191819181918191819161816592n管子总数根（8)求通过热管换热管的压力降①NFV求换热器的净自由容积fffTLndddSSNFV2022044866.0ππ2222330.8660.0810.0320.0620.0320.00141854.310m/m44②evD求当量直径3444.310^(3)20.05100.944hevhNFVDA热侧：m0.0182ccevevDD冷侧：m③'Ref求max60.018222267.44Re'4502.925.057103600hhhevfhfDG热侧：max60.018222338.4Re'5064.320.35103600cccevfcfDG冷侧：④f求摩擦系数0.145hf1.92Re'0.567hf热侧：0.145cf1.92Re'0.557cf冷侧：⑤求平均管壁温度wt3124810215182.838.51.699592hhhwfhhfehQtthAn热侧：C31210.4910110158.533.51.255592cccwfccfehQtthAn冷侧：C⑥w求壁温下的流体黏度623.4810hw热侧：kg/ms624.6310cw冷侧：kg/ms⑦P求通过换热器的压降20.140.40.6max2hhhhfhevLhhhcevfwTTGLDSfPgDSS热侧：0.140.4270.55625384.90.0810.8663225.05650.0182997Pa21.3100.01820.728422.450.08120.140.40.6ccccmaxcevfLccccevfwTTGLDSfP2gDSS冷侧：0.140.4270.57118816.40.0810.8663220.350.0182797Pa21.3100.01820.92224.10.081(9)求热管的第一排的管内流体温度tv第一排烟气温度1ht=280℃密度1hf=0.6432kg/m3；导热系数1hf=4.674210W/(mC)；黏度1hf=27.468610kg/(ms)；普朗特数Prh1=0.654第一排空气温度c2t=160℃密度2cf=0.815kg/m3；导热系数2cf=3.64210W/(mC）；黏度2cf=24.5610kg/(ms)；普朗特数Prc2=0.682①fRe求max01-6122267.440.032Re720627.468103600hhfhfGd热侧：max02-6222338.40.032Re810424.5103600ccfcfGd冷侧：②fh求1120.6338110.6338331104.674100.137RePr0.13772060.6540.032hfhhhffhd热侧：250.2W/mC（）1120.6338220.6338332203.64100.137RePr0.13781040.6820.032cfc