Problem in simulating Heterogeneous Reactor

Discusses use of COCO, the process simulation and modelling software suite from AmsterCHEM, downloadable from http://www.cocosimulator.org

Moderator: jasper

Problem in simulating Heterogeneous Reactor

Postby antoinetonee » 16 November 2021, 03:57

Hi all,

I'm currently facing a problem in simulating heterogeneous reactor with user-defined reaction kinetic expression. The reactor converts NO, CO, and H2O into NH3 and N2, hence it has two reactions (namely NTA_NH3 and NTA_N2, respectively). My intention is to parametrize the dimension and inlet flow rate of the reactor. Disclaimer: the pressure was expressed in kPa, hence it was divided by 1000.

As seen in the attached .fsd file, the simulation for the particular base case worked just fine. However, the parametrization didn't work at all. The main error is "NTA_N2: negative base in power", so I suppose there is something wrong with the rate expression of N2 formation, which I cannot find. What does this error message mean? And does anybody have an idea to solve this problem?

Thanks in advance.
Attachments
rx_NO_CO_H2O_PtRutile_adiab_T_F_dimPar1_rct010_a.fsd
(112.58 KiB) Downloaded 541 times
antoinetonee
 
Posts: 3
Joined: 14 October 2020, 13:49

Re: Problem in simulating Heterogeneous Reactor

Postby jasper » 16 November 2021, 07:32

If you apply the two conditions of the failed item to the actual case, 0.275 m diameter and 5.25 mol/s flow rate, you will see that the unit fails with the same message. At this point you can look at the profiles (appended), and you see that the Nitric oxide runs out. However your reaction rates do not appear to become zero at this point (there are additive terms in there, is that intended?); check your reaction. If this is as intended, you could perhaps attempt to continue using

Code: Select all
max(0,X("Nitric oxide"))


instead of

Code: Select all
X("Nitric oxide")




Code: Select all
Position   Nitric oxide flow   Carbon monoxide flow   Water flow   Ammonia flow   Nitrogen flow   Carbon dioxide flow   Temperature   Pressure   Total flow   Density   Viscosity   Superficial velocity   r[NTA_N2]   r[NTA_NH3]   Enthalpy
m   mol/s   mol/s   mol/s   mol/s   mol/s   mol/s   K   Pa   mol/s   mol/m³   Pa s   m/s   mol/s/kg.cat   mol/s/kg.cat   J/mol
0   0.0315   0.07875   0.04725   0   0   0   573   101300   5.24475   21.2597406681   3.72339279547e-05   4.1534746098   1.51923088213e-06   2.45798132647e-06   5797.19704863
0.02   0.0314684768101   0.0786857971077   0.0472173211454   2.17861856654e-05   4.86829018705e-06   6.42028923302e-05   572.901776744   101055.446875   5.24471245243   21.2120617904   3.72292681529e-05   4.16278067589   2.617402184e-06   7.27520565017e-06   5795.15384713
0.04   0.0313881438379   0.0785099185946   0.0471217762917   8.54829838651e-05   1.31862053698e-05   0.000240081405371   572.894717242   100810.340371   5.24460858932   21.1608811339   3.72288381636e-05   4.17276632742   4.47478777906e-06   2.1158920085e-05   5795.08651377
0.06   0.0311986690584   0.078076769068   0.0468781043813   0.000247931869683   2.6698443058e-05   0.000673230931961   573.092169908   100564.60791   5.24435140375   21.1020316055   3.72378930055e-05   4.18419817914   6.878840028e-06   4.94907340768e-05   5799.45521996
0.08   0.0308400639976   0.0772371625965   0.0463970995265   0.000568600624866   4.56674568847e-05   0.00151283740351   573.607194287   100318.13729   5.24385143161   21.031412762   3.72616656489e-05   4.19784755191   9.1920829151e-06   8.67062037532e-05   5810.71711766
0.1   0.0302958807129   0.075948319757   0.0456524338486   0.00106504236911   6.95397578678e-05   0.002801680243   574.470622449   100070.786667   5.24308289669   20.9480190231   3.73015648926e-05   4.21394143531   1.10759489055e-05   0.000122282799272   5829.54685824
0.12   0.0295879433172   0.0742624838546   0.0446745322721   0.00171697573015   9.7542542677e-05   0.00448751614536   575.640911827   99822.415836   5.24207699386   20.8535356336   3.73556363302e-05   4.23222187801   1.25592744632e-05   0.000151338321042   5855.04906161
0.14   0.0287504905347   0.0722628137134   0.0435123146288   0.00249178739753   0.000128863171341   0.00648718628664   577.053108422   99572.9072348   5.24088345573   20.7504928509   3.74208400779e-05   4.25226984724   1.37610137095e-05   0.000173562760882   5885.819923
0.16   0.0278156127511   0.0700275548623   0.0422119337681   0.00335870804027   0.000162841690052   0.00872244513774   578.646355922   99322.1663903   5.23954909625   20.6412345649   3.7494331265e-05   4.27368959986   1.47781260737e-05   0.000190064985064   5920.54347323
0.18   0.0268096890771   0.0676213614563   0.0408116640772   0.0042922211812   0.000199046946343   0.0111286385437   580.370598932   99070.1169411   5.23811262128   20.5276695066   3.75737725603e-05   4.29615474099   1.56737455969e-05   0.000202038085987   5958.13675703
0.2   0.0257517214182   0.06509111096   0.0393393812361   0.00527374307403   0.000237269830354   0.01365888904   582.189760014   98816.7057653   5.23660211556   20.411166972   3.76574801538e-05   4.31943031861   1.64882394969e-05   0.000210460155476   5997.8190792
0.22   0.0246570377025   0.0624746576195   0.0378176116082   0.00628825615825   0.000277355146798   0.0162753423805   584.074742402   98561.8906104   5.23504026062   20.2928138248   3.77440991706e-05   4.34332658233   1.72457814668e-05   0.000216048641368   6038.96023915
0.24   0.0235379583795   0.0598024563219   0.0362644896334   0.00732367080806   0.000319187483489   0.0189475436781   586.002170214   98305.6391981   5.2334453063   20.1734662138   3.78325444217e-05   4.36769089511   1.79609068385e-05   0.000219332522888   6081.05333586
0.26   0.0224047088757   0.0570997976593   0.034695080475   0.00836994358049   0.000362675849014   0.0216502023407   587.952657523   98047.9269293   5.23183240878   20.053816187   3.79219195981e-05   4.3923963787   1.86419683188e-05   0.000220708656823   6123.67728689
0.28   0.0212657956997   0.0543877214379   0.0331219174299   0.00941871894398   0.00040774475526   0.0243622785621   589.910098648   97788.7365681   5.23021417683   19.9344216926   3.80114836414e-05   4.41733730926   1.92933359895e-05   0.000220483900911   6166.48155348
0.3   0.0201283546141   0.0516838621046   0.031555499182   0.0104629977758   0.000454325882175   0.0270661378954   591.861006406   97528.0568094   5.22860117745   19.815733801   3.81006194418e-05   4.44242482988   1.99166402743e-05   0.000218902933749   6209.17189123
0.32   0.0189984016153   0.049003061902   0.0300046519777   0.0114968959119   0.000502353313636   0.029746938098   593.794035272   97265.8814402   5.22700230282   19.6981168429   3.8188811168e-05   4.46758385831   2.05115147887e-05   0.000216166913118   6251.5001042
0.34   0.0178812643764   0.0463584248601   0.0284771521743   0.012515229114   0.000551755332152   0.0323915751399   595.699162515   97002.208114   5.225425401   19.5818788747   3.82756061594e-05   4.49274762319   2.10758966699e-05   0.000212446766403   6293.24629168
0.36   0.0167812377642   0.043760470313   0.0269792242391   0.0135138477374   0.000602459326657   0.034989529687   597.568340623   96737.0388748   5.22387676907   19.467253053   3.83606440873e-05   4.51786219741   2.16065783226e-05   0.000207890360279   6334.23323177
0.38   0.015702075606   0.0412183304362   0.0255162465204   0.0144891662165   0.000654381166224   0.0375316695638   599.394562457   96470.3782909   5.22236186951   19.3544308808   3.84436137203e-05   4.5428802328   2.20991172587e-05   0.000202628734205   6374.30606826
0.4   0.0146470715759   0.0387399455438   0.0240928656581   0.0154380867913   0.000707422893861   0.0400100544562   601.171708509   96202.2334044   5.22088544692   19.2435690496   3.85242455596e-05   4.56775995425   2.25479058412e-05   0.000196780142551   6413.32905451
0.42   0.0136189500854   0.0363317929989   0.0227128346037   0.0163581074943   0.00076147328758   0.0424182070011   602.894753129   95932.6137362   5.21945136547   19.1347845608   3.86023208136e-05   4.59246662976   2.29462751577e-05   0.000190451471988   6451.19015672
0.44   0.0126200260521   0.0339992737812   0.0213792394194   0.0172471709505   0.000816403576127   0.0447507262188   604.559461032   95661.5306954   5.21806284   19.0281660158   3.86776572389e-05   4.61697054578   2.32863969803e-05   0.000183740029014   6487.7944909
0.46   0.0116522405212   0.0317467916307   0.0200945427998   0.0181036353636   0.000872064135037   0.0470032083693   606.16231954   95388.9972914   5.21672248282   18.9237770178   3.87501057655e-05   4.6412465861   2.35592227711e-05   0.000176734157751   6523.06290981
0.48   0.010717170734   0.0295777705141   0.0188605914704   0.0189262695831   0.00092828191885   0.0491722294859   607.700519322   95115.027893   5.21543231371   18.8216578866   3.88195493563e-05   4.66527414488   2.37544024312e-05   0.000169513185637   6556.93164676
0.5   0.00981605743301   0.0274947213524   0.0176786556096   0.0197142268237   0.000984859949092   0.0512552786476   609.171902923   94839.6382271   5.21419379982   18.721828296   3.88859004441e-05   4.68903680854   2.38601577969e-05   0.000162147230426   6589.35124261
0.52   0.0089499074383   0.0254994759882   0.0165495602402   0.02046695707   0.0010415698233   0.0532505240118   610.574770324   94562.8447539   5.21300799457   18.6242939899   3.89490919499e-05   4.71252105266   2.3863135467e-05   0.00015469725383   6620.28233259
0.54   0.0081195322822   0.0235932747906   0.0154737341986   0.021184174431   0.00109814872083   0.0551567252094   611.907806966   94284.6646648   5.21187558963   18.5290495734   3.90090738953e-05   4.73571576061   2.37482932105e-05   0.000147214630014   6649.6941035
0.56   0.00732561304993   0.0217769145945   0.0144512932348   0.0218658017402   0.00115429468236   0.0569730854055   613.169962303   94005.1157878   5.21079700271   18.4360826234   3.90658078212e-05   4.75861139013   2.34988328668e-05   0.000139740749388   6677.56165719
0.58   0.00656874427211   0.0200508489794   0.0134820963975   0.0225119329651   0.00120966345884   0.0586991510206   614.360367059   93724.2164127   5.20977243709   18.3453764325   3.91192629885e-05   4.78119940826   2.30962396452e-05   0.000132306290056   6703.86421478
0.6   0.00584931371831   0.018414916384   0.012565594356   0.0231229343261   0.00126387805522   0.060335083616   615.478559082   93441.9856816   5.20880172046   18.2569035771   3.91694264878e-05   4.8034738952   2.25203620363e-05   0.000124928702357   6728.5900945
0.62   0.00516820921815   0.0168699747502   0.0117017572223   0.0236988257485   0.00131648459408   0.0618800252498   616.523157229   93158.4426111   5.20788527678   18.1706652094   3.92162435683e-05   4.8254221448   2.1750441811e-05   0.000117617390573   6751.70756753
0.64   0.00452576905797   0.0154154740868   0.0108896967192   0.0242401994173   0.00136701783978   0.0633345259132   617.493830594   92873.607542   5.20702268303   18.0866327792   3.92597062031e-05   4.84703861326   2.07653674647e-05   0.000110361213126   6773.20815448
0.66   0.00392284501885   0.0140519743174   0.0101291209888   0.0247472499042   0.0014149546159   0.0646980256826   618.389298753   92587.5011852   5.20621417053   18.0048070489   3.92997632021e-05   4.86831071988   1.95463486142e-05   0.000103137470509   6793.06262545
0.68   0.00336064455676   0.0127807808621   0.00942012799558   0.0252199118997   0.0014597238492   0.0659692191379   619.207627948   92300.1448726   5.2054604083   17.9252087387   3.93363336181e-05   4.88922086949   1.80805386845e-05   9.59084280872e-05   6811.22749081
0.7   0.00284019980721   0.011602670682   0.00876246256504   0.0256583555201   0.00150072441379   0.067147329318   619.947231536   92011.5609087   5.20476174231   17.8478493037   3.93693516207e-05   4.90975356558   1.63649407241e-05   8.86118955829e-05   6827.66704471
0.72   0.00236324005086   0.0105204994389   0.00815725107828   0.0260618298446   0.00153746712971   0.0682295005611   620.605165088   91721.7734968   5.2041197881   17.7727803066   3.93986903307e-05   4.92988334743   1.4414872374e-05   8.11821141466e-05   6842.31551733
0.74   0.00193163330714   0.00953716419448   0.00760552257762   0.026429648845   0.00156936100136   0.0692128358055   621.178262369   91430.8072561   5.20353616573   17.7000598433   3.94242124035e-05   4.94958256915   1.22736126207e-05   7.35374391946e-05   6855.1024682
0.76   0.00154716947767   0.00865603605974   0.00710885827235   0.0267607583819   0.00159603814766   0.0700939639403   621.663423037   91138.6887127   5.20301282428   17.6297446985   3.94457833308e-05   4.96882388695   1.0018692477e-05   6.56090221323e-05   6865.95864938
0.78   0.00121113295842   0.00788022956115   0.00666908829302   0.0270539383681   0.00161746641418   0.0708697704388   622.0583777   90845.4464726   5.20255162603   17.5618690166   3.9463305729e-05   4.98758598292   7.76314640423e-06   5.73676160518e-05   6874.83274997
0.8   0.000925589991255   0.00721467411381   0.00628907581284   0.0273072800216   0.00163356707104   0.0715353258862   622.359399782   90551.1105098   5.2021555129   17.4965092013   3.94766163648e-05   5.00583640333   5.65935217979e-06   4.89000132029e-05   6881.64145369
0.82   0.000690308979803   0.00666023628956   0.00596991900004   0.0275200512301   0.0016448219725   0.0720897637104   622.566889422   90255.7115708   5.20182510118   17.4336267302   3.94857366069e-05   5.02357318762   3.85147744007e-06   4.04209443833e-05   6886.3919098
0.84   0.000503297079945   0.00621455050737   0.00571124511771   0.027692500485   0.00165210329498   0.0725354494926   622.684423706   89959.2808026   5.20155914598   17.3730969606   3.94908295453e-05   5.04081812943   2.43934325066e-06   3.22942560181e-05   6889.16106507
0.86   0.000359558615509   0.00586816985622   0.00550860293099   0.0278275952761   0.00165642513163   0.0728818301438   622.721187082   89661.8461383   5.20135218195   17.3146422683   3.94923082152e-05   5.05763481991   1.4393439073e-06   2.49067249006e-05   6890.14980247
0.88   0.000252742528597   0.00560842272533   0.00535567188701   0.0279295493054   0.00165885616042   0.0731415772747   622.688890884   89363.4320648   5.20119681988   17.2579195868   3.94906979417e-05   5.07410649812   7.97190993156e-07   1.85888652247e-05   6889.61498061
0.9   0.000175351430273   0.00541895675136   0.00524359701136   0.0280042658892   0.0016601934177   0.0733310432486   622.601494519   89064.056642   5.20108340775   17.2025279848   3.94866236361e-05   5.09033396513   4.18196292266e-07   1.34767170306e-05   6887.86374126
0.92   0.000120639940945   0.00528454889435   0.00516390064368   0.028057396801   0.00166098370648   0.0734654511056   622.471613023   88763.7323427   5.20100292109   17.148108098   3.94806495465e-05   5.10640922575   2.10608582623e-07   9.55350356707e-06   6885.17400582
0.94   8.2152894123e-05   0.00518979793091   0.00510763672706   0.0280949060787   0.00166147259101   0.0735602020691   622.311406116   88462.4650651   5.20094616829   17.0943164177   3.94733190962e-05   5.1224219649   1.0202557342e-07   6.62965996503e-06   6881.81416201
0.96   5.53671967321e-05   0.00512371849235   0.00506834298589   0.0281211019062   0.00166176752598   0.0736262815077   622.129420561   88160.2564086   5.20090657961   17.0409117003   3.94650141027e-05   5.1384360713   4.77440938119e-08   4.51438942546e-06   6877.97297063
0.98   3.60638669888e-05   0.00507599974409   0.00503992756738   0.0281400455185   0.00166194738468   0.0736740002559   621.93362793   87857.1047005   5.20087798434   16.9876705547   3.94560907517e-05   5.15451212987   2.06800629962e-08   2.95398366088e-06   6873.82652725
1   2.22318354157e-05   0.00504157369388   0.00501933354874   0.0281537748643   0.00166199872759   0.0737084263061   621.72785169   87553.0050186   5.20085733898   16.9344844651   3.94467197573e-05   5.1706803666   7.96901659589e-09   1.8213534967e-06   6869.45937848
1.02   1.36502415702e-05   0.0050200693742   0.00500641082292   0.0281623900149   0.00166198194924   0.0737299306258   621.512501087   87247.9518165   5.20084443303   16.8813387302   3.94369193295e-05   5.18694580178   3.02603823101e-09   1.11372643643e-06   6864.88048775
1.04   9.45759380735e-06   0.00500954138055   0.00500007547702   0.0281666135788   0.00166196649116   0.0737404586195   621.289190955   86941.9388815   5.20083811314   16.8281859809   3.94267616213e-05   5.20332273196   1.45483504129e-09   7.65725593975e-07   6860.12545208
1.06   7.18865260163e-06   0.00500389178023   0.00499669481791   0.0281688673515   0.00166197407539   0.0737461082198   621.062583404   86634.9592123   5.2008347249   16.7748968537   3.94164550833e-05   5.21984882354   8.39655764934e-10   5.76627521023e-07   6855.29728619
1.08   4.82368635672e-06   0.00499802405663   0.00499319206056   0.0281712025231   0.00166198897273   0.0737519759434   620.836506143   86327.0036938   5.20083120724   16.7213654639   3.94061708994e-05   5.23655598413   3.77712610848e-10   3.83340811111e-07   6850.48061158
1.1   2.46436356138e-06   0.00499214662135   0.00498967394807   0.0281735479314   0.00166199592996   0.0737578533786   620.610771184   86018.0613332   5.20082768217   16.6675946035   3.9395900643e-05   5.25344593006   9.84920562686e-11   1.94012748174e-07   6845.67129855
1.12   6.42342336405e-07   0.00498759441132   0.00498694375927   0.0281753680573   0.00166199687764   0.0737624055887   620.384371261   85708.1209691   5.20082495104   16.6136089171   3.93855992363e-05   5.27051416033   6.68039482845e-12   5.00711903698e-08   6840.84708742
1.14   -1.71808006266e-08   0.0049859498191   0.00498595869019   0.02817602477   0.00166199828285   0.0737640501809   620.156124375   85397.1722204   0   0   0   0   0   0   0

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jasper
 
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Re: Problem in simulating Heterogeneous Reactor

Postby jasper » 16 November 2021, 08:00

Re-checking your expression, it does go to zero in case X[nitric oxide] goes to zero - it is the only term in the numerator.

The negative rate of nitric oxide however is within integration tolerance. Perhaps try the solution with max(0, ... ) to avoid the negative value.
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Re: Problem in simulating Heterogeneous Reactor

Postby antoinetonee » 17 November 2021, 04:30

jasper wrote:Re-checking your expression, it does go to zero in case X[nitric oxide] goes to zero - it is the only term in the numerator.

The negative rate of nitric oxide however is within integration tolerance. Perhaps try the solution with max(0, ... ) to avoid the negative value.


Thank you for the reply, Jasper. I tried with max(0, X[nitric oxide]) and max(0, X[carbon monoxide]), both being the terms in the numerator, it didn't work (the same negative rate error message). Heck I tried as far as making the entire rate equations with max(0, ...) and it still failed the same way, which is really strange and doesn't make sense.

I checked the NO value for D = 0.3 m, flow rate 6 mol/s, the value of NO does turn negative and hence the simulation failed to continue (see attached Excel spreadsheet). This is one hell of a weird code bug.
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antoinetonee
 
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Re: Problem in simulating Heterogeneous Reactor

Postby jasper » 17 November 2021, 07:52

Works for me if I just change X("Nitric oxide") into max(0,X("Nitric oxide")) in both reaction terms (2x each).
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Re: Problem in simulating Heterogeneous Reactor

Postby jasper » 17 November 2021, 07:54

that in fact makes all runs work:

Screenshot 2021-11-17 091411.png
Screenshot 2021-11-17 091411.png (166.89 KiB) Viewed 8671 times
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Re: Problem in simulating Heterogeneous Reactor

Postby antoinetonee » 18 November 2021, 03:18

jasper wrote:that in fact makes all runs work:

Screenshot 2021-11-17 091411.png


Yeah now it's working. Thanks a lot!
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Re: Problem in simulating Heterogeneous Reactor

Postby jasper » 18 November 2021, 06:45

Glad to hear it.
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