function xprime=cola_rr(t,X) % sample usage:   [t,x]=ode15s('cola_Rv',[0 5000],0.5*ones(1,82));%% cola_rr - Subroutine for simulation with L/D-V/B-configuration.%%           There are many ways to implement the double ratio configuration.%           In this case we set the ratios L/D and V/B externally, and let%           the levels be controlled using D and B (controlling the levels%           like this may not be the best solution; but for tight level%           control it makes no difference)%%            Inputs are reflux (LT) and boilup (VB). Disturbances%            are feedrate and feed composition. These are set by directly%            altering 'cola_dv.m'. Outputs are liquid composition and%            liquid hold up for stages 1 through NT, given in x. % Number of stages in the columnNT=41;% Inputs and disturbancesRT=2.70629/0.5;                      % L/DRB=3.20629/0.5;                      % V/BF=1.0 + 0.00;                        % FeedratezF=0.5;                              % Feed compositionqF=1.0;                              % Feed liquid fraction% P-Controllers for control of reboiler and condenser hold up.KcB=10;  KcD=10;         % controller gainsMDs=0.5; MBs=0.5;        % Nominal holdups - these are rather small  Ds=0.5; Bs=0.5;          % Nominal flowsMB=X(NT+1);  MD=X(2*NT); % Actual reboiler and condenser holdupD=Ds+(MD-MDs)*KcD;       % RefluxB=Bs+(MB-MBs)*KcB;       % Bottoms flow     % Resulting reflux and boilupLT = RT*D;VB = RB*B;% Store all inputs and disturbancesU(1)=LT; U(2)=VB; U(3)=D; U(4)=B; U(5)=F; U(6)=zF; U(7)=qF;xprime=colamod(t,X,U);