Method of operating a heat releasing reactor, a heat releasing reactor, and a computation system for a heat releasing reactor

Abstract

A method of operating a heat releasing reactor producing product gas. The method includes steps of (a) monitoring a current load of the reactor, (b) finding such a numerical value for a current computational maximum momentary load for which at least one product gas factor computed using currently monitored process data with a numerical model of the reactor fulfills an acceptance condition, and selecting the numerical value as the current computational maximum momentary load, (c) indicating the current computational maximum momentary load to the operator and/or, if the current load is (c1) less than the current computational maximum momentary load, (c1i) indicating the operator that the load may be increased, and/or (c1ii) automatically increasing the load, and/or (c2) greater than the current computational maximum momentary load, (c2i) indicating the operator that the load exceeds the current computational maximum boiler momentary load, and/or (c2ii) automatically reducing the boiler load.

1 . A method of operating a heat releasing reactor producing a product gas, the method comprising the steps of:
 (a) monitoring a current load (Q h ) of the reactor;   (b) finding such a numerical value (Q h, candidate ) for a current computational maximum momentary load (Q h, max ) for which at least one product gas factor (df i ) computed using currently monitored process data with a numerical model of the reactor fulfills an acceptance condition, and selecting the numerical value (Q h, candidate ) as the current computational maximum momentary load (Q h,max );   (c) indicating the current computational maximum momentary load (Q h,max ) to an operator and/or, if the current load (Q h ) is
 (c1) less than the current computational maximum momentary load (Q h,max ):
 (c1i) indicating the operator that the load (Q h ) may be increased, and/or 
 (c1ii) automatically increasing the load (Q h ), 
 
 and/or 
 (c2) greater than the current computational maximum momentary load (Q h,max ):
 (c2i) indicating the operator that the load (Q h ) exceeds the current computational maximum boiler momentary load, and/or 
 (c2ii) automatically reducing the boiler load (Q h ). 
 
   
     
     
         2 . The method according to  claim 1 , wherein:
 (i) the currently monitored process data of the reactor includes:
 (ia) current product gas exit temperature (T G,exit,current ) in a gas flow channel, and 
 (ib) heat duty (Q fluid,i ) for each heat transfer surface (i) in the product gas flow channel, 
   and, further, wherein:   (ii) monitored process data from both (ia) and (ib) is used in computation of the product gas factor and when finding the numerical value (Q h, candidate ) for the current computational maximum momentary load (Q h,max ).   
     
     
         3 . The method according to  claim 1 , wherein the finding is performed such that, if the at least one product gas factor (df i ) computed using currently monitored process data with a numerical model of the reactor fails to fulfill an acceptance condition, a next numerical value (Q h, candidate ) is automatically selected. 
     
     
         4 . The method according to  claim 3 , wherein the next numerical value (Q h, candidate ) is selected iteratively. 
     
     
         5 . The method according to  claim 1 , wherein the finding is carried out by performing the computational steps of:
 I: computing an estimate for product gas exit temperature (T G, exit ) that results in a computational model when the load of the reactor corresponds to the numerical value (Q h, candidate );   II: computing product gas mass flow (q m,productgas );   III: computing a heat duty (Q fluid, i, candidate ) for each heat transfer surface in the gas flow path using its current heat duty (Q fluid, i, current ) that is corrected by using a numerical reactor model (Q fluid, i, candidate =Q fluid,i,current +S a j,I (Q fluid,max ) j −S a j,i  (Q fluid,current ) j );   IV: using the computed heat duties (Q fluid, i, candidate ) for each heat transfer surface in the product gas flow channel to compute product gas temperatures at each heat transfer surface (T G,in,i , T G,out,i ; i=1, . . . , k) in the flue gas flow channel in the upstream direction of product gas flow, starting from the heat transfer surface  21   k  that is closest to the product gas exit using the estimate for the product gas exit temperature (T fluegas,out,k =T FG, exit ); and   V: computing the product gas factor (df i , i=1, . . . , k) for each heat transfer surface in the flue gas flow channel.   
     
     
         6 . The method according to  claim 5 , wherein the flue gas factor includes or is: 
       
         
           
             
               
                 df 
                 i 
               
               = 
               
                 
                   
                     k 
                     i 
                   
                   ( 
                   
                     
                       q 
                       
                         m 
                         , 
                         G 
                       
                     
                     
                       
                         ρ 
                         
                           productG 
                           , 
                           i 
                         
                       
                       * 
                       
                         A 
                         
                           cross 
                           , 
                           i 
                         
                       
                     
                   
                   ) 
                 
                 n 
               
             
           
         
         where k i  is a non-zero parameter that may be chosen reactor-specifically, being a positive number, 
         q m,productgas  is product gas mass flow, 
         n is a model parameter that may be chosen reactor-specifically, being a positive non-zero number, and 
         p G,i  is product gas density at i th  heat transfer surface and A is a cross-sectional area of flue gas channel at i th  heat transfer surface. 
       
     
     
         7 . The method according to  claim 6 , wherein n is selected to be at least one of the following:
 (i) in the range of 0.9 to 1.1, for using computed product gas velocity;   (ii) in the range of 2.9 to 3.5 for using computed product gas caused erosion; or   (iii) in the range 1.8 to 2.2, for using pressure loss of the product gas flow.   
     
     
         8 . The method according to  claim 7 , wherein the value for n is changed over time. 
     
     
         9 . The method according to  claim 7 , wherein the value for n is determined from a group of reactors comprising at least two separate reactors using operational data monitored for each of the reactors. 
     
     
         10 . The method according to  claim 5 , wherein, in the computation in step (I), the flue gas exit temperature is substantially estimated by an equation: 
       
         
           
             
               
                 T 
                 
                   G 
                   , 
                   exit 
                 
               
               = 
               
                 
                   a 
                   0 
                 
                 + 
                 
                   
                     
                       Sa 
                       j 
                     
                     ( 
                     
                       Q 
                       
                         h 
                         , 
                         candidate 
                       
                     
                     ) 
                   
                   j 
                 
               
             
           
         
       
       or its first, second, third, or higher degree approximation, and wherein the respective coefficients (a 0 , a 1 , a 2 , . . . ) have been obtained beforehand by fitting after measuring product gas exit temperature (T G, exit ) values for a number of discrete reactor load (Qh) values. 
     
     
         11 . The method according to  claim 5 , wherein, in step (II), computation of product gas mass flow utilizes mass flow (q m,G,m ) of product gas components m. 
     
     
         12 . The method according to  claim 5 , wherein, in step (II), the computation of product gas mass flow includes using reactant parameters. 
     
     
         13 . The method according to  claim 1 , wherein the step (b) is performed remotely to the reactor. 
     
     
         14 . The method according to  claim 1 , wherein the step (b) is performed locally at the reactor site. 
     
     
         15 . The method according to  claim 1 , wherein any of the currently monitored process data and/or current load is obtained from real-time measurements, treated by filtering, treated by averaging, computing trends, or any combination of these. 
     
     
         16 . The method according to  claim 1 , wherein the acceptance condition includes a hysteresis condition, requiring a predefined minimum change before changing the current computational maximum momentary load (Q h,max ). 
     
     
         17 . The method according to  claim 1 , wherein the acceptance condition includes comparing the computed at least one product gas factor (df i ) against a respective design value, and wherein, in the method, the numerical value (Q h, candidate ) is rejected if the design value is exceeded. 
     
     
         18 . The method according to  claim 1 , wherein the reactor is a circulating fluidized bed (CFB) or a bubbling fluidized bed (BFB) reactor, and the step (b) is carried out for the heat transfer surfaces in at least one of the reactor, and the product gas channel. 
     
     
         19 . A heat releasing reactor comprising:
 a reactor chamber and associated passes defining a product gas flow path and having a number of heat transfer surfaces;   measurement instrumentation to monitor current load (Q h ) of the heat releasing reactor;   further measurement instrumentation, such as sensors, to currently monitor process data; and   a control system configured to carry out the method of operating the heat releasing reactor according to  claim 1 .   
     
     
         20 . The heat releasing reactor ( 10 ) according to  claim 19 , wherein the control system comprises (CS) an edge server ( 203 ) that is configured to process real-time measurement results for at least one of currently monitored process data and current load, by filtering, averaging, and/or computing trends. 
     
     
         21 . The heat releasing reactor according to  claim 19 , wherein the control system is configured to carry out the method step (b) to determine the current computational maximum momentary load (Q h,max ) locally. 
     
     
         22 . The heat releasing reactor according to  claim 19 , wherein the control system is configured to send data to a remote computing system that is configured to carry out the method step (b) and to return the current computational maximum momentary load (Q h,max ) to the control system. 
     
     
         23 . The heat releasing reactor according to  claim 22 , wherein the edge server is configured to reduce an amount of measurement data that is passed to the remote computing system. 
     
     
         24 . A reactor computation system comprising:
 a group of reactors, according to  claim 19 , each reactor comprising a control system (DCS), comprising an edge server system that is configured to process the real-time measurement results for at least one of currently monitored process data and current load, by performing at least one of filtering, averaging, and computing trends, and to send the processed real-time measurement results to a remote computing system;   a remote computing system that is configured to receive data processed from real-time measurement results and to compute data using a numerical model for each of the reactors, and to return computation results for each of the reactors; and,   further, wherein the control system is configured to adapt its function based on the computation results.   
     
     
         25 . The reactor computation system according to  claim 24 , wherein the computing system is configured to find such a numerical value (Q h, candidate ) for a current computational maximum momentary load (Q h,max ) for which at least one product gas factor (df i ) computed using currently monitored process data with a numerical model of the reactor that fulfills an acceptance condition, and selecting the numerical value (Q h, candidate ) as the current computational maximum momentary load (Q h,max ). 
     
     
         26 . The reactor computation system according to  claim 24 , wherein the reactor computation system is configured to calibrate a numerical model for a heat releasing reactor using processed measurement data for the heat releasing reactor. 
     
     
         27 . The reactor computation system according to  claim 24 , wherein the reactor computation system is configured to calibrate a numerical model for a heat releasing reactor using processed measurement data also collected from other heat releasing reactors.