Facility monitoring method

• US 6,993,403 B1
• Filed: 03/22/2005
• Issued: 01/31/2006
• Est. Priority Date: 03/22/2005
• Status: Active Grant

• Current Assignee: Praxair Technology Incorporated (Linde Plc)
• Original Assignee: Praxair Technology Incorporated (Linde Plc)
• Inventors: Klein, Frank J. III, Dadebo, Solomon A., Katende, Edward
• Primary Examiner(s): CABRERA, ZOILA E
• Application Number:
  US11/085,554
• Time in Patent Office: 315 Days
• Field of Search: 700108-110, 700/266, 700/270, 700271-273, 702182-186, 702/83, 702/84
• US Class Current: 700/108
• CPC Class Codes: G05B 23/0294 Optimizing process, e.g. process efficiency, product quality

Abstract

A method of monitoring plant performance within a facility in which having averages of cost contributing items such as raw material usage, product recovery, unit production efficiency, power usage and controller error performance are evaluated, statistically weighted to determine an overall performance factor. The overall performance factor applies an instantaneous indication of plant operation. Excursions of individual performance factors diagnose plant problems.

Claims

1. A method of monitoring performance of a facility having at least one plant producing at least one product and consuming at least one commodity in at least one unit operation, said method comprising:

periodically monitoring current values including a rate of usage of the at least one commodity, a production rate of the at least one product and a unit production cost computed by dividing at least a cost value referable to the rate of usage of at least one of the at least one commodity by the production rate of the at least one product;

computing and storing running averages over a predetermined time interval of the rate of usage of the at least one commodity and the unit production cost;

determining base values related to steady state operation of the facility for the each of the running averages;

periodically computing performance factors that include a commodity performance factor related to the usage of the at least one commodity and a production efficiency performance factor related to the unit production cost by mathematical functions utilizing the running averages and the base values and defined such that as the usage of the at least one commodity increases, the commodity performance factor and the production efficiency performance factor decrease and as product recovery increases, the production efficiency performance factor increases;

computing an overall performance factor by weighting the performance factors in at least approximate proportions to cost contribution of each of the performance factors to the production of the at least one product to produce weighted performance factors and adding the weighted performance factors; and

displaying the overall performance factor to a user monitoring the performance of the facility.

2. The method of claim 1, wherein:

the at least one commodity is a raw material and electrical power;

the rate of usage of the raw material is used to compute the commodity performance factor and the production efficiency performance factor;

the running averages computed and stored are also of the rate of usage of the electrical power; and

the performance factors also include an electrical power consumption performance factor and the mathematical functions are also selected such that as the consumption of electrical power increases, the electrical power consumption performance factor decreases.

3. The method of claim 2, wherein:

the product recovery of the at least one product is a fraction of the at least one product produced in the at least one plant;

the current values also include at least one percentile recovery of the at least one product based upon the fraction of the at least one product produced in the at least one plant;

the running averages computed and stored are also of the percentile recovery of the at least one product; and

the performance factors also include a percentile recovery performance factor and the mathematical functions are also selected such that as the percentile recovery of the at least one product increases, the percentile recovery performance factor also increases.

4. The method of claim 3, wherein:

the current values also include automated controller performance related to automated controllers utilized in controlling the at least one unit operation, the automated controller performance computed by summing integral square errors between measured values of process variables to be controlled in the at least one unit process by the automated controllers and target values for said process variables;

the running averages computed and stored are also of the automated controller performance; and

the performance factors also include a controller performance factor and the mathematical functions are also selected such that as integral square errors are reduced, the controller performance factor increases.

5. The method of claim 4, further comprising displaying each of the performance factors.

6. The method of claim 5, wherein an indication is conveyed to the user when at least one of the overall performance factor and at least one of the performance factors deviates from related base values by predetermined amounts.

7. The method of claim 5 or claim 6, wherein the mathematical functions used in determining the performance factors are ratios of the base values to the running averages for the electrical power consumption performance factor, the commodity performance factor and the controller performance factor, a percentage production running average to percentage production base value ratio for the percentage production performance factor and a difference between a constant and a unit cost running average to a unit cost base value ratio for the production efficiency performance factor.

8. The method of claim 7, wherein

the at least one plant comprises a hydrogen and carbon monoxide plant having a series of unit operations that produce a hydrogen product stream, a carbon monoxide stream, an export steam stream, and a methanol purge stream;

the hydrogen and carbon monoxide plant imports hydrogen as an imported hydrogen stream from another hydrogen and carbon monoxide plant and consumes a natural gas stream both as feed and fuel to a steam methane reformer;

the raw material is natural gas of the natural gas stream;

the at least one product is hydrogen of the hydrogen product stream;

the production rate of the at least one product is a hydrogen flow rate of the hydrogen product stream;

the current values include flow rates of the natural gas stream, the methanol purge stream, the imported hydrogen stream, a methanol feed stream consumed within a methanol reactor, the carbon monoxide stream, and the export steam stream;

a heat content of the export steam stream is computed;

the cost value is high heating value and related high heating values are computed for the natural gas stream, the methanol purge stream, the imported hydrogen stream, the methanol feed stream and the carbon monoxide stream; and

the unit production cost is determined by performing an energy balance of the hydrogen and carbon monoxide plant and dividing said energy balance by the hydrogen flow rate of the hydrogen product stream, the energy balance computed by deriving a first sum by adding products of the flow rates and the related high heating values of the natural gas stream, the methanol purge stream and the imported hydrogen stream, deriving a second sum by multiplying the flow rates and the related high heating values methanol feed stream and the carbon monoxide stream and then, subtracting from the first sum, the heat content of the export steam stream and the second sum.