Predictive emissions monitoring system and method

• US 20070225836A1
• Filed: 03/17/2006
• Published: 09/27/2007
• Est. Priority Date: 03/18/2005
• Status: Active Grant

• Current Assignee: CMC Solutions, LLC
• Original Assignee: Brian Swanson
• Inventors: Swanson, Brian
• Granted Patent: US 7,421,348 B2
• Time in Patent Office: Days
• US Class Current: 700/45
• CPC Class Codes: G05B 17/02 electric

Abstract

A method for predicting emissions from an emissions source. Test values of process variables relating to operation of the emissions source are gathered, along with corresponding time-correlated test values of the emissions variable to be predicted. Using the test values of the process variables, test values of a plurality of first coefficients are calculated for each process variable and associated with the process variable, and test values of a plurality of second coefficients are calculated for each value of each process variable and associated with the value of the process variable. Comparison values of the process variables relating to operation of the emissions source are gathered, along with corresponding time-correlated comparison values of the emissions variable to be predicted. Using the comparison values of the process variables, comparison values of a plurality of first coefficients are calculated for each process variable and associated with the process variable, and comparison values of a plurality of second coefficients are calculated for each value of each process variable and associated with the value of the process variable. Predetermined combinations of the comparison values of the variables and their associated coefficients are then iteratively compared with the test values of the respective variables and associated coefficients. Where the comparison yields matches between the comparison values and test values of the variables and their associated coefficients, the test values of the emissions variable associated with the matched test values of the variables are averaged and assigned as a predicted value of the emissions variable.

Claims

1. A method for predicting a value of a first variable based on values of a plurality of additional variables, comprising the steps of:

acquiring a plurality of test values of the first variable, each test value of the plurality of first variable test values being measured at a corresponding point in time;

for each additional variable of the plurality of additional variables, acquiring a plurality of test values of the additional variable, each value of the plurality of additional variable values being associated with a value of the plurality of first variable values, each test value of the plurality of additional variable test values being measured at a point in time substantially simultaneous with a point in time at which one of the test values of the plurality of first variable test values is measured;

for each first coefficient of a plurality of first coefficients, providing a separate test value of the first coefficient associated with each additional variable of the plurality of variables, each separate test value of the first coefficient being a function of at least a portion of the test values of the plurality of test values of the associated additional variable;

for each second coefficient of a plurality of second coefficients, providing a separate test value of the second coefficient associated with each test value of each additional variable of the plurality of variables, each separate test value of the second coefficient being a function of at least a portion of the test values of the plurality of test values of the associated additional variable;

for each selected one of a plurality of selected ones of the additional variables of the plurality of additional variables, acquiring a plurality of comparison values of the additional variable;

for each first coefficient of the plurality of first coefficients, providing a separate comparison value of the first coefficient associated with the additional variable, each separate comparison value of the first coefficient being a function of at least a portion of the comparison values of the plurality of comparison values of the associated additional variable;

for each second coefficient of the plurality of second coefficients, providing a separate comparison value of the second coefficient associated with the comparison value of each additional variable, each separate comparison value of the second coefficient being a function of at least a portion of the comparison values of the plurality of comparison values of the associated additional variable;

for each additional variable in each predetermined combination of a plurality of predetermined combinations of the selected ones of the additional variables, iteratively comparing;

each comparison value of the additional variable with each test value of the additional variable; and

the comparison values of selected ones of the second coefficients associated with the comparison value of the variable with the test values of the selected ones of the second coefficients associated with the test value of the variable;

for each additional variable in each predetermined combination of a plurality of predetermined combinations of the selected ones of the additional variables, identifying all test values of the additional variable where the test value differs from a comparison value of the additional variable by an amount equal to or less than an associated predetermined amount, and where, for each of the selected ones of the second coefficients associated with each test value of the additional variable, all test values of the selected ones of the second coefficients differ from the comparison values of the selected ones of the second coefficients by an amount equal to or less than an associated predetermined amount; and

assigning, as the predicted value of the first variable, an average of all of the test values of the first variable that are associated with respective test values of each additional variable for which the test first variable values differ from the comparison additional variable values by the associated predetermined amount.

2. The method of claim 1 wherein the first variable describes a characteristic of a product of a process and each variable of the plurality of additional variables describes a parameter of the process.

3. The method of claim 1 wherein the first variable describes a parameter of a process, at least one of the variables of the plurality of additional variables describes a characteristic of a product of the process, and the remaining ones of the variables of the plurality of additional variables describe a parameter of the process.

4. The method of claim 1 wherein a coefficient of the plurality of first coefficients comprises a correlation factor providing a quantitative indication of a correlation between the first variable and the additional variable associated with the first coefficient.

5. The method of claim 4 wherein each additional variable of each predetermined combination of the plurality of predetermined combinations of ones of the additional variables has a correlation with the first variable indicated by a correlation factor that exceeds a predetermined threshold value.

6. The method of claim 5 wherein the predetermined threshold value of the correlation factor is equal to about 0.50.

7. The method of claim 1 wherein a coefficient of the plurality of first coefficients comprises an initial tolerance value describing a range of values within which the value of the additional variable resides.

8. The method of claim 7 wherein a coefficient of the plurality of second coefficients comprises a delta value equal to a difference between a first value and a second value of a pair of time-successive values of the plurality of values of the additional variable.

9. The method of claim 8 wherein a coefficient of the plurality of second coefficients comprises an indicator variable indicating a result of a comparison between a predetermined one of the first coefficients and a predetermined one of the second coefficients.

10. The method of claim 9 further comprising the steps of:

for each value of the plurality of values of each additional variable of the plurality of additional variables, where a delta value associated with the variable value is greater than a tolerance value associated with the variable, specifying a value of the indicator variable indicating that the delta value associated with the variable value is greater than the tolerance value for the variable;

for each value of the plurality of values of each variable of the plurality of additional variables, where a delta value associated with the variable value is less than or equal to a tolerance value associated with the variable, specifying a value of the indicator variable indicating that the delta value for the variable value is less than or equal to the tolerance value for the variable.

11. The method of claim 10 further comprising the steps of:

where a delta value associated with the variable value is greater than a tolerance value associated with the variable, for each value of the plurality of values of each additional variable of the plurality of additional variables, specifying a value of the indicator variable equal to a time elapsed between the point in time of measurement of the variable value and a point in time of measurement of a closest time-sequential prior value of the variable.

12. The method of claim 10 further comprising the steps of:

for each value of the plurality of values of each additional variable of the plurality of additional variables, where a delta value associated with the variable value is less than or equal to a tolerance value associated with the variable, incrementing a value of the indicator variable associated with a closest time-sequential prior value of the variable value by an amount equal to a time elapsed between the point in time of measurement of the variable value and a point in time of measurement of the closest time-sequential prior variable value.

13. The method of claim 7 wherein each of the additional variables describes a characteristic of a process, and wherein the step of providing a separate test value of a first coefficient associated with each additional variable of the plurality of variables comprises the steps of:

for each additional variable of the plurality of additional variables, determining if the test values of the plurality of test values of the additional variable were measured over a period of operation of the process including startup and shutdown of the process;

where the test values of the plurality of test values of the additional variable were measured over a period of operation of the process including startup and shutdown of the process, calculating a standard deviation of the test values of the plurality of test values of the additional variable and setting the initial tolerance value associated with the additional variable to one half the standard deviation;

where the test values of the plurality of test values of the additional variable were not measured over a period of operation of the process including startup and shutdown of the process, calculating a range of measured values of the additional variable equal to a difference between a maximum measured value of the plurality of test values of the additional variable and a minimum measured value of the plurality of test values of the additional variable, and setting the initial tolerance value associated with the additional variable to 2.5% of the range of measured values of the additional variable.

14. The method of claim 1 wherein a coefficient of the plurality of second coefficients comprises a delta value equal to a difference between a first value and a second value of a pair of time-successive values of the plurality of values of the additional variable.

15. The method of claim 1 wherein a coefficient of the plurality of second coefficients comprises an indicator variable indicating a result of a comparison between a predetermined one of the first coefficients and a predetermined one of the second coefficients.

16. The method of claim 15 wherein the predetermined one of the first coefficients is an initial tolerance value specifying a range of values within which the value of the additional variable resides, and the predetermined one of the second coefficients is a delta value equal to a difference between a first value and a second value of a pair of time-successive values of the plurality of values of the additional variable.

17. The method of claim 1 wherein the first variable describes a characteristic of a product resulting from implementation of a process, and wherein each variable of the plurality of additional variables describes a characteristic of the process which results in the product.

18. The method of claim 1 wherein the first variable describes a first characteristic of a process, and wherein the plurality of additional variables describe additional characteristics of the process and a characteristic of a product resulting from implementation of the process.

19. The method of claim 1 further comprising the step of storing each test value of the plurality of test values of the first variable, each test value of the plurality of test values of each additional variable of the plurality of additional variables, each test value of each first coefficient of the plurality of first coefficients, and each test value of each second coefficient of the plurality of second coefficients in a relational database.

20. The method of claim 19 further comprising the step of storing each comparison value of each additional variable of the plurality of additional variables in a relational database.

41. A power generation system comprising:

an emissions source; and

a predictive emissions monitoring system for predicting a characteristic of an emission of the emissions source, the predictive emissions monitoring system including a computer system adapted to implement a method in accordance with claim 1.

42. A predictive emissions monitoring system adapted to perform a method in accordance with claim 1.

21. A method for generating a model representative of a process, the process including a result variable representing a product of the process, and a plurality of process variables representing characteristics of the process other than the product of the process, the method comprising the steps of:

acquiring a plurality of test values of the result variable, each test value of the plurality of result variable test values being measured at a corresponding point in time;

for each process variable of the plurality of process variables, acquiring a plurality of test values of the process variable, each test value of the plurality of process variable test values being associated with a result variable value of the plurality of result variable values, each test value of the plurality of process variable test values being measured at a point in time substantially simultaneous with a point in time at which one of the test values of the plurality of result variable test values is measured;

for each first coefficient of a plurality of first coefficients, providing a separate test value of the first coefficient associated with each process variable of the plurality of process variables, each separate test value of the first coefficient being a function of at least a portion of the test values of the plurality of test values of the associated process variable; and

for each second coefficient of a plurality of second coefficients, providing a separate test value of the second coefficient associated with each test value of each process variable of the plurality of process variables, each separate test value of the second coefficient being a function of at least a portion of the test values of the plurality of test values of the associated process variable.

22. A computer system adapted to implement a method in accordance with claim 21.

23. A predictive emissions monitoring system adapted to perform a method in accordance with claim 21.

24. An article of manufacture comprising a computer-usable medium having computer-readable program code means embodied therein, the computer-readable program code means comprising:

computer readable program code means for causing a computer to receive into memory a plurality of test values of a first variable, each test value of the plurality of first variable test values being measured at a corresponding point in time;

computer readable program code means for causing a computer to, for each additional variable of a plurality of additional variables, receive into memory a plurality of test values of the additional variable, each value of the plurality of additional variable values being associated with a value of the plurality of first variable values, each test value of the plurality of additional variable test values being measured at a point in time substantially simultaneous with a point in time at which one of the test values of the plurality of first variable test values is measured;

computer readable program code means for causing a computer to, for each first coefficient of a plurality of first coefficients, associate a separate test value of the first coefficient with each additional variable of the plurality of additional variables, each separate test value of the first coefficient being a function of at least a portion of the test values of the plurality of test values of the associated additional variable; and

computer readable program code means for causing a computer to, for each second coefficient of a plurality of second coefficients, associate a separate test value of the second coefficient with each test value of each additional variable of the plurality of additional variables, each separate test value of the second coefficient being a function of at least a portion of the test values of the plurality of test values of the associated additional variable.

25. The article of claim 24 further comprising computer readable program code means for causing a computer to compute each separate test value for each first coefficient of the plurality of first coefficients.

26. The article of claim 24 further comprising computer readable program code means for causing a computer to compute each separate test value for each second coefficient of the plurality of second coefficients.

27. The article of claim 24 further comprising:

computer readable program code means for causing a computer to, for selected ones of the additional variables of the plurality of additional variables, acquire a plurality of comparison values of each of the selected ones of the additional variables;

computer readable program code means for causing a computer to, for each first coefficient of the plurality of first coefficients, provide a separate comparison value of the first coefficient associated with each variable of the selected ones of the additional variables, each separate comparison value of the first coefficient being a function of at least a portion of the comparison values of the plurality of comparison values of the associated additional variable; and

computer readable program code means for causing a computer to, for each second coefficient of a plurality of second coefficients, associate a separate comparison value of the second coefficient with each comparison value of each selected one of the additional variables of the plurality of additional variables, each separate comparison value of the second coefficient being a function of at least a portion of the comparison values of the plurality of comparison values of the associated additional variable.

28. The article of claim 27 further comprising computer readable program code means for causing a computer to compute each separate comparison value for each first coefficient of the plurality of first coefficients.

29. The article of claim 27 further comprising computer readable program code means for causing a computer to compute each separate comparison value for each second coefficient of the plurality of second coefficients.

30. The article of claim 27 further comprising:

computer readable program code means for causing a computer to,

for each additional variable in each predetermined combination of a plurality of predetermined combinations of the selected ones of the additional variables, iteratively compare;

each comparison value of the variable with each test value of the variable; and

the comparison values of selected ones of the second coefficients associated with the comparison value of the variable with the test values of the selected ones of the second coefficients associated with the test value of the variable;

computer readable program code means for causing a computer to, for each additional variable in each predetermined combination of a plurality of predetermined combinations of the selected ones of the additional variables, identify all test values of the additional variable where the test value differs from a comparison value of the additional variable by an amount equal to or less than an associated predetermined amount, and where, for each of the selected ones of the second coefficients associated with each test value of the additional variable, all test values of the selected ones of the second coefficients differ from the comparison values of the selected ones of the second coefficients by an amount equal to or less than an associated predetermined amount; and

computer readable program code means for causing a computer to assign, as the predicted value of the first variable, an average of all of the test values of the first variable that are associated with respective test values of each additional variable for which the test first variable values differ from the comparison additional variable values by the associated predetermined amount.

31. The article of 30 further comprising computer readable program code means for causing a computer to determine each predetermined combination of the plurality of predetermined combinations of ones of the additional variables.

32. A memory for storing data for access by an application program being executed on a computer system, comprising:

a data structure stored in the memory, the data structure including information resident in a database used by the application program and including;

a plurality of values of a first variable, each value of the plurality of first variable values being measured at a corresponding point in time;

a plurality of values of each variable of a plurality of additional variables, each value of the plurality of additional variable values being associated with a value of the plurality of first variable values, each value of the plurality of additional variable values being measured at a point in time substantially simultaneous with a point in time at which one of the test values of the plurality of first variable values is measured;

a plurality of test values of each first coefficient of a plurality of first coefficients, each test value of each first coefficient being associated with an additional variable of the plurality of additional variables, each test value of each first coefficient being a function of at least a portion of the test values of the plurality of test values of the associated additional variable;

a plurality of values of each second coefficient of a plurality of second coefficients, each value of each second coefficient being associated with an additional variable of the plurality of additional variables, each value of each second coefficient being a function of at least a portion of the values of the plurality of values of the associated additional variable.

33. The memory of claim 32 wherein the first variable represents a characteristic of a product of a process, and each additional variable of the plurality of additional variables represents a parameter of the process.

34. The memory of claim 32 wherein a coefficient of the plurality of first coefficients comprises a correlation factor providing a quantitative indication of a strength of correlation between the first variable and the additional variable associated with the first coefficient.

35. The memory of claim 32 wherein a coefficient of the plurality of first coefficients comprises a tolerance value specifying a range of values within which the value of the additional variable is located.

36. The memory of claim 32 wherein a coefficient of the plurality of second coefficients comprises a delta value equal to a difference between a first value and a second value of a pair of time-successive values of the plurality of values of the additional variable.

37. The memory of claim 32 wherein a coefficient of the plurality of second coefficients comprises an indicator variable indicating a result of a comparison between a predetermined one of the first coefficients and a predetermined one of the second coefficients.

38. A computer data signal embodied in a transmission medium, the data signal comprising:

a computer-readable source code segment for causing a computer to receive into memory a plurality of values of a first variable, each value of the plurality of first variable values being measured at a corresponding point in time;

a computer-readable source code segment for causing a computer to, for each additional variable of a plurality of additional variables, receive into memory a plurality of values of an additional variable, each value of the plurality of additional variable values being associated with a value of the plurality of first variable values, each value of the plurality of additional variable values being measured at a point in time substantially simultaneous with a point in time at which one of the values of the plurality of first variable values is measured;

a computer-readable source code segment for causing a computer to, for each first coefficient of a plurality of first coefficients, associate a separate value of the first coefficient with each additional variable of the plurality of variables, each separate value of the first coefficient being a function of at least a portion of the values of the plurality of values of the associated additional variable; and

a computer-readable source code segment for causing a computer to, for each second coefficient of a plurality of second coefficients, associate a separate value of the second coefficient with each value of each additional variable of the plurality of variables, each separate value of the second coefficient being a function of at least a portion of the values of the plurality of values of the associated additional variable.

39. The computer data signal of claim 38 wherein the data signal resides on a carrier wave.

40. A method for predicting a quantitative measure of a characteristic of an emission from an emissions source, comprising the steps of:

acquiring a plurality of test values of the characteristic, each test value of the plurality of characteristic test values being measured at a corresponding point in time;

for each process variable of a plurality of process variables, acquiring a plurality of test values of the process variable, each test value of the plurality of process variable test values being associated with a test value of the plurality of first variable test values, each test value of the plurality of process variable test values being measured at a point in time substantially simultaneous with a point in time at which one of the test values of the plurality of first variable test values is measured;

for each process variable of the plurality of process variables, and using the plurality of test values of the process variable, calculating an associated test correlation coefficient indicating a correlation between the process variable and the characteristic;

for each process variable of the plurality of process variables, and using the plurality of test values of the process variable, calculating an associated test tolerance value specifying a range of values within which the test value of the process variable is located;

for each test value of the plurality of test values of each process variable of the plurality of process variables, calculating an associated test delta value equal to a difference between the test value and a most-recent prior time-successive test value of the plurality of test values of the process variable;

for each test value of the plurality of test values of each process variable of the plurality of process variables, calculating an associated test indicator variable value indicating a result of a comparison between the tolerance value associated with the process variable value and the delta value associated with the process variable value;

for each process variable of selected ones of the plurality of process variables, acquiring a plurality of comparison values of the process variable;

for each process variable of the selected ones of the plurality of process variables and using the plurality of comparison values of the process variable, calculating an associated comparison correlation coefficient indicating a correlation between the process variable and the characteristic,

for each process variable of the selected ones of the plurality of process variables and using the plurality of comparison values of the process variable, calculating an associated comparison tolerance value describing a range of values within which the comparison value of the process variable is located;

for each comparison value of the plurality of comparison values of each selected one of the plurality of process variables, calculating an associated comparison delta value equal to a difference between the comparison value and a most-recent prior time-successive comparison value of the plurality of comparison values of the process variable;

for each comparison value of the plurality of comparison values of each selected one of the plurality of process variables, calculating an associated comparison indicator value indicating a result of a comparison between the tolerance value associated with the process variable value and the delta value associated with the process variable value;

for each process variable in each predetermined combination of a plurality of predetermined combinations of the selected ones of the process variables,

iteratively comparing each comparison value of the variable with each test value of the variable, the comparison value of the tolerance associated with the process variable with the test value of the tolerance associated with the process variable, the comparison value of the indicator associated with the process variable with the test value of the indicator associated with the process variable, the comparison value of the delta associated with the process variable with the test value of the delta associated with the process variable, and the comparison value of the correlation coefficient associated with the process variable with the test value of the correlation coefficient associated with the process variable;

for each process variable in each predetermined combination of a plurality of predetermined combinations of the selected ones of the process variables,

identifying all test values of the additional variable where the test value of the additional variable differs from a comparison value of the additional variable by an amount equal to or less than a first predetermined amount,

where the test value of the delta associated with the test value of the additional variable differs from the comparison value of the delta associated with the comparison value of the additional variable by an amount equal to or less than a second predetermined amount,

and where the test value of the indicator associated with the test value of the additional variable differs from the comparison value of the indicator associated with the comparison value of the additional variable by an amount equal to or less than a third predetermined amount; and

assigning, as the predicted value of the emissions variable, an average of all of the test values of the emissions variable that are associated with respective test values of each process variable for which the test process variable values differ from the comparison process variable values by the associated predetermined amount.