 what was the central issue with the mixed flow reactor in non-isothermal asking question is very bad think you know starting straight way is best I think ya Anupriya what was the problem why you are so much worried about this fellow mixed flow reactor so what happens feedback is always happy what happens what is the issue there are multiple study states ya I mean why should I worry if there are multiple study states because you will be either getting exceeding temperature or you will be getting lower conversion ya particularly unfortunately when you have calculated from energy balance a temperature which is in that middle point okay and also you have conditions corresponding to a line which goes through that three points and unfortunately what you have is only middle point without knowing so then you may be thinking that that is the temperature may be around 70 degrees 80 degrees but suddenly it may shoot up to 150 or 200 degrees where everything will be burnt okay so that is the reason why immediately after design is done for mixed flow reactor non-isothermal design then you have to check really whether these study states you know the particularly temperature whether it is correct temperature or not if it is not correct temperature and definitely when you are well you have to operate only at that point that middle point because if you go above some explosion may be occurring if you come below there may not be reaction at all so you have to operate only at that point what you have to do now you have to go for control and have an excellent control and if it is going away see earlier on its own if one temperature increase is there one degree centigrade so then it was coming back on its own you know under study state conditions and even if there is one point less and one degree less less than the operating temperature may be 199 again it will go back to that particular temperature but this unsteady state temperature is dangerous if it moves up then it goes to the next study state may be 200 kilometers 200 degrees away so then you will have a problem similarly when you come down then it may go to that that is called extinguishing point that means the entire reaction may get extinguished that means particularly in the case of combustion that is called extinguishing like you know when I told you when you put too much gas why it is switching off on its own was that the amount of gas is more and the heat that is available in the flame is not sufficient so that means all the gas should be heated to that temperature but when you suddenly increase the flow rate you have more amount of cold fluid cold feed where there is no there is no the temperature cannot sustain on its own right that is why it will get extinguished switched off so that is why if you have I think very low means anyway it may not catch fire so those are the two extremes so I also gave you some practical examples what you see everyday you know match stick so that will make some interest in you I mean the daily things what we see also we can see in the actual reactors and all that what we have discussed is only for simply irreversible reaction you are going to R so what kind of these graphs you get if I have for example reversible exothermic reaction of this type what kind of QG curve you get by the by you can just think you are not at all expanding your brain so I think you are interested in submitting assignments in the Moodle but all that is there but I think no mood in the class absolutely you do not have any mood in the class I think you are only working on Moodle Moodle Moodle can you expect I think the S shaped curve can justify now I cannot keep on telling the same thing grinding grinding finally you know like shrinking core model the particle may disappear you may disappear out sometime because of my grinding okay but I think nothing is happening no reaction absolute calm before storm okay I think absolutely no idea no okay can you justify why I think S shaped S shaped curve you get for A going to R I explained also this what is S shaped but I am asking what is the reason physics I say all the time I think now chemistry is about to be over I am talking about physics physics physics you are talking about chemistry chemistry chemistry okay your chemistry with other teachers and all that when the increases rate increases so the initially it increases the QG increases but at very high temperature initial increase means you should increase rate but see we have S shaped curve what is the justification for S shaped curve unfortunately if you apply to some college where you want to join for you know Phd and all that then if this kind of question is asked what do you do I say they won't ask you to derive they will simply ask you explain how I am sure he is telling very we will give you a chance initially temperature is low initially temperature is low concentration is high but rate of reaction is still low concentration and temperature shoots up so the heat generated you already gone to shooting up temperature I am talking about S shaped where it goes like this after the initial part initial part what happens temperature is low even though concentration is high rate of reaction is low heat generation is low temperature increase is low how many lows okay and then after sometime the concentration even though it is low temperature will pick up so now when it is started raising very steeply then you have the right combination of temperature as well as concentration even though concentration is low temperature is picking up but finally temperature is very high temperature is not picking up concentration that is why it has to get flatted again remember I say how many years I have to tell you same thing you know but I think all of you have a wonderful technique that the moment you cross the door I think you will forget everything whatever is discussed is it chapam or you know some kind of curse that no one should remember after class is over anyway it is unfair to ask you because I think my time is going okay so for A going to R this kind of QG will be like this the down trend is not there for irreversible reaction irreversible reaction why should here be that down trend because of the back quote reaction okay because of the back quote reaction so now you know it reaches a maximum that means rate is reaching a maximum so that means heat release will be the maximum then rate decreases you have also seen you know that our graphs okay so that is why you get this kind of shape for A going to R you know irreversible reactions okay I mean even if it is second order A plus B going to R plus S also shape is same good and here temperature concentration of R is more concentration and temperature both are high concentration of R is more what is the relationship between concentration and R concentration and temperature both are high how concentration is more first of all it is minus R A okay how concentration is more irreversible reaction I am talking about irreversible reaction that is R CR is more so after reaching the maximum point what is the reversible but what rate minus R A okay the difference between forward reaction and my back quote reaction is minus R A okay minus R A equal to K 1 C A minus K 2 CR what is K 2 CR is the back quote reaction what is K 1 CR is the forward reaction so what is overall reaction again we are going to L K G yeah so R that R only we are talking it reaches maximum even though his doubt is that you know concentration of CR increasing where it should fall it will naturally fall but temperature is increasing heat release only decreasing temperature is increasing right temperature is increasing okay but only heat release will be less it reaches maximum and then from there it comes down right yeah so that is what so now we are going to draw QR lines here by the way where I have to operate on this line here okay right so when I start for example you know I may have a situation where I may have okay this this or maybe I think I have drawn it to okay this which one you choose because all of them T 0 is same this is T 0 is same so depending on the slope UA and also you have sigma of F i that that equation is same so because this is QR line this is Q G line this is QR line QR QR QR but different okay so normally we will try to choose this why because conversion will be maximum corresponding to this Q G QR okay so but you know why I am telling this one is that here it is invetable for you to have controller yeah that will give multiple study states but if I go here safe no problem but still the concentration is I mean the conversion is very very low so that is the reason if you have situation you try to go here but this is again very very low the other one is not I think so here somewhere otherwise what you can do is you can now draw a line like this so that means you are deliberately changing T T 0 right so and also the slope means you know F A sigma of F i C P i plus UA so all those variables you have to try to manipulate and T 0 also you have to push it right trying to push T 0 you know that is why so many beautiful things are there in reactor design so much brain is required for doing you know reactor design right so way I told this one is that when T 0 is moved we do not know whether it will be economical or not that means before entering the reactor you have to increase the temperature of the feet so you have to use a different heat exchanger so some other heating system so all these things overall picture is all these things you have to take into picture and then find out whether simply at a lower temperature T 0 is it economical operating here or drawing something like this may be economical because that slope is very very steep there okay slope is I mean so slope is very very steep when I want to change the slope what are the conditions I have feed rate sigma f i c p i is nothing but feed rate only f not so that means f not should be very large when you have f not very large what will happen to the overall reactor size volume should increase because residence time will be decreasing because again f not is nothing but volumetric flow rate into C A not no so that is why so many things so many connections particularly non isothermal design when you are doing all these problems will come those are the issues you have to appreciate atleast you should know what are the problems if you are able to find out what are the problems and solution you can find out later that is why all the time I have been telling what are the issues what are the problems do you know the problem in the design of mixed flow reactor or plug flow reactor plug flow reactor this problem will not come very happy why swami I told you I told in the class not only you everyone yesterday I told why this multiple study states will not exist in a p of r do you remember what is the reason there is not any back mixing any accumulation of heat in plug flow will be simply washed out okay there is no communication backward this that increase in temperature heat accumulation and all that will be simply washed away if there is a temperature rise it will just move away but the problem there is another problem is parametric density right that means at a particular point particularly that is very dangerous with temperature T not you know feed temperature when feed temperature is increased slowly at one point it shoots up you cannot control anything in the reactor this information I am not able to give you more except words only so I think by less and amundsum there is a paper by less and amundsum bi I think by less and amundsum under amundsum if you search lot of this information you will get so there actually they have varied various T nots feed temperatures and then shown at what temperature at what feed temperature it shoots up like you have shown that figure no Ram Krishna that kind of figures you can see okay and another my question the plug flow yesterday I think it skipped from my mind to ask you if I have a recycle reactor study states see extending brain you should question me yes because there is feedback okay see how much beautiful information is there in your brain if you want to bring it out but Swami started laughing you know subject is laughable or okay good fine so this is one thing this is the same again to find out you know study states and all that writing energy balance material balance and then drawing the line or solving both the equations and then trying to find out okay good that is the one so I may also have a reaction something like this so that is why last year I have also not done I think after seeing you I thought I want to do more and more okay because you are silently absorbing I do not know how much you are absorbing because this A going to R R going to S so very nice funny graphs you will get okay QG and temperature right if both are exothermic reactions exo exo Swami guess they are irreversible reactions right they are irreversible are excellent otherwise like like this very bad snake like this it goes okay this is like snake you know if you put that okay so now in this case how many study states you have this also lowest one 1, 2, 3, 4 okay yeah I think this also 5 5 right and as usual this will be unsteady state intermediate this will be unsteady state okay anyway I think that is only just for information and I can also give you if this is exothermic and this is endothermic just for information only what you are different shapes you know how many beautiful things are there in reaction engineering I just want to show it to you okay this is r, r going to s but this is exo and this is endo very good beautiful so it goes like this also good so now next one you have qg and t but here I have a going to r r going to s but the first one is endo and this is exo yes that is why I have drawn this also it goes below this if you like snakes I think you will get lot of snakes in this multiple steady states okay good yeah there is another thing also which we have to just discuss about ignition and yeah extension extension and ignition points okay so those points we will discuss for a going to r normal okay so for normal x shaped curve qg versus t and of course also q r is there both are there let me draw like this curve okay so I may have a line like this that we know already or I may also have which is just touching here this is 1 this is 0.1 this is 0.2 and this one we know your experts in this now this is 3 this is 4 this is 5 okay now next logically it may be like this so this is sorry sorry so this point is put as 4 that I will this is 5 this is 6 this is 7 yeah so this is 8 then this of course we know this is 9 so meaning of this is if you keep t not changing what are the various stages you know the entire curve moves okay how the reactor move how the conditions inside the reactor moves that means we are starting here this one we know 0.1 and this is 2 3 4 5 6 7 8 9 okay good so now if I plot them again this is just yeah t versus t not for example this one is t not 1 t not 2 t not 3 t not 4 t not 5 like that t not 1 2 t not 5 so t not is the variable here that means I am just trying to find out what will be t t is in the reactor when I vary t not okay so you will get yeah so I mean when you travel here this point will be there this is 1 then it is moving slowly slowly increasing this is also temperature is increasing here we have another temperature so all that I can show simply as like this okay this is 0.1 this may be 0.2 0.3 and then it goes like this goes like this okay so this this point is 0.4 here you will have somewhere 0.5 this will be 0.6 this is too much this I turned it too much yeah so here this is 0.6 yeah this will be 0.6 then of course here you will have 0.7 0. slightly away 0.8 then here 0.9 okay so this point also slightly I have to draw okay so this is 0.1 0.2 this is third point so like that so what will happen is you know it is a kind of hysteresis when you are moving from 1 to 2 right so 1 to 2 1 is here and then suddenly it may go to 6 without travelling all that distance okay so that means like this right and then that means this is the one so this point is called ignition point that means suddenly I have a temperature here and next temperature is very high it is not next small temperature next small temperature that means it is not going through all you know that increment temperatures the way we are imagining right so suddenly when I have this two point this temperature for this is this okay so it may touch instead of going to 3 4 and 5 when I am increasing temperature t0 right so and from this temperature it may go like this good so that is one way so this this is called this corresponding state is called ignition that means suddenly it is catching fire see what will happen if I come down so that means from this side t0 5 to t0 5 to t0 5 sorry t0 1 to t0 5 so now when I am coming down here like this this is fine okay and at this point you can see I am coming here from here to 4 so that is what it straight falls it is not curve I mean it is not slightly slanted may be I think here this goes may be this also I have to remove so this is the point when I am coming from this side and this is the point when I am going this side so this point what do you think this is ignition point see here you are coming from this side and then you have 9 anyway high temperature then I have 8 and suddenly from here to 4 so the reaction can extinguished can get extinguished so this is extension point extension on this on this line so that is why normally it is shown that that is the kind of hysteresis what we have so it goes like this and when you are coming like this correct no when you are going you are going like this when you are increasing temperature feed but when you are decreasing feed then you are coming like this so you have this one overall so this is only just for your information and of course probably I will not give on this one the reason is it takes time you have to plot that and then carefully look at those points anyway if you correctly calculate and then draw it definitely you will get all those points so that is why it may take time so only may be 1 problem or 5 problems I have to give you either do 1 problem or 5 problems so this is what I just want to tell you about this some more things about multiple steady state mixture flow reactor so as I told you there is a lot of information available actually there is a book called control of chemical reactor by J M Douglas remember correctly J M Douglas no not Douglas anyway I think sorry I have forgotten now so that is also another book only on control of reactors in fact you know in M Tech we had earlier some kind of history M Tech we had earlier 6 streams 6 streams were there we had biochemical engineering environmental engineering polymer engineering chemical reaction engineering transport phenomena and control 6 covered so I think at that time again may be 30 for the M Tech input so in every branch every stream only 5 5 5 5 but some streams I think we used to get only 2 like that so at that time in chemical reaction engineering stream all these courses were there we had a separate reactor theory course chemical and catalytic reaction engineering course and then non catalytic reaction engineering course separately and then stability of chemical reactors that was another course and one more word I think only these 5 courses and the remaining things anyway you have to take transport phenomena and reactor theory was common to everyone but those who were there in the reaction engineering stream they have to take the remaining 4 extra that is chemical and catalytic reaction engineering non catalytic reaction engineering stability of reactors and one more course I told I think all these courses good so at that time we used to teach all that now we have also forgotten because I think streams are removed and now I think our brain also is becoming blend it is not sharp because when you teach also we also remember in fact the most beneficiary of teaching is the teacher not the student unfortunately okay good so I think with this I have covered all these I think anything else is only one or two things now just left out that is our normal multiple reactors how do you get the maximum this we postponed at that time we discussed if you have activation energy for one reactor is more than the activation energy of the other reactor how do you do how do you operate the reactor so that information I told you that when you are discussing non isothermal reactors we will just discuss that quickly I will go through that is multiple reactions temperature effects okay yeah so if I have A going to and A going to S this is desired our symbol so here this is one and two reactions I have a case where E1 greater than E2 and other case is E1 less than E2 how do you operate this how do you operate this you have the rule already with you yeah when E1 is greater than E2 use high temperature in the so that this will be forming more and more and that is what you wanted you know that is the desired product so that is what so here I have high T high temperature and here low T good very simple so this only just remind you all this again so now I have here this is desired product and I have one and two reaction again you have case here E1 greater than E2 and E1 less than E2 what is the no condition if I use high temperature okay so this will be yeah so this will be forming more when you go to temperature scheme after some time you have to go to low temperature but straight away if I have this one more definitely I have to use low temperatures so that is why here simply here also high T and also low T but when I ask the temperature scheme then you have to say that okay sorry initially use high temperature and then later you go to low temperatures okay good okay so that is the one and yeah when I have this one A going to R R going to all three I have R, S and T this is the desired product yeah this one I will just nicely leave it for you this is one two three this is the desired product I will give you some kind of equation 1 by T opt equal to optimum temperature here you cannot use only one temperature somehow optimum temperature sorry you can use one temperature but that has to depend on E1 and E2 and E3 if this one is less and these two are more okay activation energies or this may be low this may be high this may be low all combinations are there okay but even then with all these combinations you will get one nice equation you please derive this equation I do not want to derive that it is very simple only thing is you have to write equation for maximum what is that it is rate there maximum yield not conversion not rate both do not have any meaning here it is yield you write an equation for yield and differentiate with respect to temperature then you will get this T opt so that equation is R by E3 minus E1 ln of E3 minus E1 E1 K30 this 30 is frequency factor for the third reaction okay good so divided by E1 minus E2 K20 so that is the equation R is R is not product there oh sorry yeah logical logical doubt that R is you know gas constant okay good so that is the one and the last one which I want to tell you is our famous reaction what is that denby reaction okay good so now when I go to denby reaction it may be you can write here A plus B going to okay R going to S this is going to T this is going to U okay so now we call this one as 1 2 3 4 okay I mean various combinations are possible the first combination is E1 greater than E2 and E3 greater than E3 greater than E4 what is the temperature scheme Pooja this is the desired product oh desired product very good question this one is desired very good question not R here we have SC is the one I will ask you here I will tell here yes and I will ask in the examination R okay in between yes so that means uniformly we have high temperature that is right okay good so then you have E1 less than E2 reverse of this and E3 less than E4 this is low temperature right so now I have here another case E1 less than E2 and E3 greater than E4 initially low temperature and then slowly increase the temperature I am happy I say I think at least I think you are experts of this temperature schemes okay activation energies somehow I think you like activation energy all of you are able to answer this okay this is increasing temperature how do I write okay correct no arrow good so then the other one is of course reverse of this is E1 greater than E2 and E3 less than E4 this is decreasing temperature maybe I think here I have to put increasing temperature is increasing temperature okay good actually those are good symbols of when you are doing PHD work or MS work it is better always if you have 4 5 variables okay and the dependent variable you have to see how it is getting increasing or decreasing so write like this okay if delta P as an example because we easily understand delta P so delta P is increasing with velocity okay so write delta P increasing with velocity delta P increasing u right so like that with viscosity what happens with density density of fluid diameter of the pipe what happens that will give you very clear picture for your either equation development or correlation development if you write like this all the parameters because all of you have to do some project definitely okay good so with this I think very happy non exothermal I have covered this here much more than earlier that is why always Rahul is scolding me sir you are partial to this you are all very very lenient to this batch okay plus you are also telling them more okay maybe I think this is my last thing so that is why I have to tell more because otherwise I do not know where I have to tell later okay good so this is the one but I tell you everything will be happy in the class but the moment you cross the door nothing will be happy for you next class is much worse next class you come all looking this is fresh CD okay with I think you can put any memory there but what is the use fresh CD nothing is there inside so that is what is happening every time in every class so now I think this is closed now and now we have what is left is residence time distributions right without writing there I will introduce you for residence time distribution then we will write in the next class residence time distribution we discussed about ideal reactors we also discussed about ideal reactors residence time distribution okay merit what is the residence time distribution for plug 0 why it is 0 because it does not have any accumulation what do you mean by accumulation what is the question of accumulation we are talking about study state reactors use correct words another thing always you will lose marks the moment you use wrong words without knowing or without thinking in the interviews if you do not know you keep quiet that is much better but if you are trying to say something which you have not understood or you do not have any meaning for that and simply say some word people will definitely catch you not only merit everyone so that is why where is accumulation in PFR we are talking that you tell residence time distribution equal to 0 because every particle will spend exactly same time what kind of stupid question you are asking because where is the distribution there because each and every particle will exactly spend 10 seconds means 10 seconds if it is 11 seconds or 9 seconds only distribution comes okay Swami just behind him what is the residence time distribution for mixed flow infinity infinity is a point it is not distribution you see again catching points see if you say only distribution means it will start from somewhere and end somewhere I said 0 0 to infinity ideal reactor we are talking about only ideal reactor okay if you ideal okay ya it is 0 to infinity right now I think who I think we will go to puja residence time distribution for batch reactor what is that same as PFR I have to go to PFR and search it why 0 here it is by definition but there by force because you are not allowing anything to go out anything to enter in batch reactor you are closing all the doors like you know batch system whether you like the class or not 50 minutes you cannot go out so all of you have exactly the same residence time here what is residence time distribution 50 minutes for this class residence time distribution 0 mentally I am not talking physically you are there mentally you may not listen to me even one word also okay throughout the class you may be sitting here you may be in your own matrix correct no I think how can I check unfortunately I am not new to check and then cross out of the matrix in batch reactor also it is 0 but batch reactor normally we do not take into picture when you are talking about RTD particularly when it is flow only because when it is flow it has got its own choice to go out or coming okay for the particles whereas in batch system where is the choice you are closing all the doors that is why all residence time distribution is focused only on flow systems okay and why it is 0 for mixing flow sorry for plug flow why it is 0 to infinity for mixing flow why because you just gave the value but now I am asking why by definition of we define our PFR such that there is no distribution of particles and each and every particle has to spend exactly same time what is the best example please remember that I think other than conveyor belt any reactor only conveyor belt will take all the particles exactly because again once they enter they cannot walk they will be there that particle it does not have legs no so that is why I think it will be taken and then at the end whatever you fix 10 minutes 20 minutes like that it will come out example of one conveyor belt reactor coal combustion mainly it is coal combustion okay because coal has always plug flow coal particle if I have uniform size of the particle and at the end of 10 minutes each and every particle would have burnt same exact same way right but in reality that is not there that reality we will see in the next semester okay good so this is the one now this ideal resolution distribution will be spoiled by non-ideality parameter what is the statement ideal distribution that is 0 distribution for PFR 0 to infinite distribution for for mixed flow CSTR will be spoiled by non-ideal parameters like axial mixing dead zones yeah re-circulations bypassing these are most of the time these are only 4 5 okay so that is why we have to now find out the residence term distribution for normal reactor real reactor not ideal reactor and then to find out which non-ideality would have created this kind of distribution it is like many people are going to hospital nowadays everyone is sick right yeah so they go there you go there and then they give you a test maybe blood test because they cannot find out what is wrong with your body so by taking blood test they will know okay this parameter is not well so probably this is the cause that is what exactly what we are going to also do right otherwise you have not come to that stage maybe you will come very quickly you know this diabetes stage because now it seems in India diabetes comes around 2025 earlier it was 60 okay because the kind of food what you take is wonderful food so that is the reason why I think diabetes is pre-pwn okay I think really I think in Andhra it seems the diabetic capital of the world because those are the people they take this much rice and that rice has only sugar nothing else okay yeah so that is the reason why Andhra I am not joking correct Andhra is the capital of the world for diabetes 3 times of 4th time also okay 4th time they take snacks again made of rice only okay that is why that is very bad that is why North India it is slightly less because wheat is slightly better than rice as far as diabetes is concerned they will also get a little bit later and also their problem is early morning breakfast is 100 sweets correct no for example Bengal 99 99 then how many breakfast no sweets lunch lunch time everyday then what do you take for breakfast paratha route everyday okay but I think which state I think Rajasthan all sweets only morning or Gujarat we are great in that somewhere some non-ideality will be there always so that is why particularly when sugar patients go there they will give glucose into your mouth early what is that empty stomach you have to go and then they take the blood test and afterwards they will pour you 5 ml or 10 ml into your mouth and then after 1 hour or half an hour may be half an hour and also may be 1 hour 2 hours 1.5 hours 2 hours 2.5 hours they take the samples what they are doing they are exactly doing tracer test that is what we also inject tracer and at the outlet we try to we try to collect samples then depending on that tracer concentration sugar concentration glucose concentration then they will find out for healthy body there is a curve ideal reactor correct no for healthy body how the sugar will be absorbed by the body there is a curve so now for non-healthy body it can go anywhere for healthy body there is only one curve for non-healthy body there are thousands of curves you may have some kind of problem I may have some kind of problem so that is why they try to check and then try to find out whether they have healthy body or wrong body so if they have that one sugar then they will correct you and all that that is different that is what exactly we are going to find out here because we know the ideal reactor you know response the graphs but only thing is now we have to develop some equations also for experimental reactors and then compare always with that curve what is the experimental curve so that is what is the overall picture and unfortunately I have to take I think you know more time I have to spend maybe next class and this residence time distribution normally we talk only for one phase what we have talked till now is only for homogeneous reactors two phases like coal combustion I have coal particles solid and also air entering for combustion now I have to find out how coal is entering and leaving and how air is entering and leaving same thing for example catalytic reactions catalyst is in the packet bed and air is the reactants are entering getting converted and products are coming out now find out what is happening to catalyst but fortunately here catalyst is batch it is not moving so RTD for catalyst will not come correct but if I take moving bed I can use moving bed catalytic reactor so the particles also are moving may be co-current going up or may be counter current solids coming gas going up now I have to find out gas is moving in plug flow particles are coming down in plug flow or gas is moving in mixing flow only two flows ideally or solids are coming in mixing flow you have to find out a little bit extension slurry reactors so when you have slurry reactor you have three phases what are the phases gas liquid and solid solid is the I mean if you take example of hydrogenation of vegetable oils what is the catalyst what is the gas hydrogen and what is the liquid unsaturated oil now you have many possibilities I can take for example oil as batch solids also as batch and gas only bubbly so when these two are batch I do not have to worry much about okay but I have to worry about bubbles whether they are going in plug flow or whether they are going in mixing flow all the bubbles are spending exactly same time or some bubbles are coming very quickly some bubbles are coming very late then you have zero to infinite residence time distribution like a story I am trying to tell you so now what will happen if I have liquid also moving liquid also continuously coming continuously going out now that will be in mixing flow or whether it is really in mixing flow or not we have to check so that is why for multiple reactions for every phase you have to check whether it is in mixing flow so these are the techniques we are trying to develop in the next few classes