Plant Performance Testing

Completion Operatorstraining Pre-startup safety review Commissioning procedures and checks Plant performance test Documentation on project highlights, lessons learnt and retrofit/revamp opportunities in the future... 

Plant performance testing normally takes place soon after reaching full load and when operation of the entire plant is stable. The performance test is carried out to establish that... 

A plant performance test will normally be carried out over a defined period (usually 48 hr or longer) during which the cell room will be operated steadily near the design load. To enable this, it must be established before the test that all peripheral systems are capable of steady operation at the required throughput. 

Section 13.9 on plant performance testing discussed measurement of the caustic current efficiency by collecting the product of the entire cell room and determining the amount of caustic produced in a measured period of time. This is time-consuming and requires special equipinent or the dedication of a tank from which no product is withdrawn during the test period. It is well suited to startup periods, however, and frequently it is the basis for performance guarantee runs. 

Provision for plant performance testing requires careful liaison between the appropriate personnel of both parties. Broad requirements of such tests will usually have been stipulated in contract documents but it remains for site teams to schedule the test arrangements in detail. These ate likely to include the selection and calibration of measuring devices together with the application of correction factors and tolerances, sampling and analyses, datalogging and effects of interruptions. It is important that procedures are drawn up and agreed upon well in advance of proposed test periods. 

Rectification accounts for systematic measurement error. During rectification, measurements that are systematically in error are identified and discarded. Rectification can be done either cyclically or simultaneously with reconciliation, and either intuitively or algorithmically. Simple methods such as data validation and complicated methods using various statistical tests can be used to identify the presence of large systematic (gross) errors in the measurements. Coupled with successive elimination and addition, the measurements with the errors can be identified and discarded. No method is completely reliable. Plant-performance analysts must recognize that rectification is approximate, at best. Frequently, systematic errors go unnoticed, and some bias is likely in the adjusted measurements. 

Confidence The accuracy of the conclusions drawn from any unit test depends upon the accuracy of the laboratory analyses. Plant-performance analysts must have confidence in these analyses including understanding the methodology and the limitations. This confidence is established through discussion, analyses of known mixtures, and analysis of past laboratory results. This confidence is established during the preparation stage. 

These potential sampling problems must be solved in advance of the unit test. The conclusions drawn from any unit test are strongly affected by the accuracy of the sampling methods and the resultant analyses. Methods should be discussed and practiced before the actual unit test. Analysts should use the trial measurements in prehm-inary plant-performance analysis to ensure that the results will be use-bil during the actual unit test. 

Therefore, the identification of appropriate tests and measurements most important to understanding the unit operation is a critical step in the successful analysis of plant performance. 

The methodology of identifying the optimum test and number of measurements has received httle attention in analysis of plant performance and design literature. 

ASME, Performance Test Code on Overall Plant Performance,... 

ASME, Performance Test Code on Overall Plant Performance, ASME PTC 46 1996, American Society of Mechanical Engineers 1996... 

The ASME, Performance Test Code on Overall Plant Performance, ASME PTC 46, was designed to determine the performance of the entire heat cycle as an integrated system. This code provides explicit procedures to determination of power plant thermal performance and electrical output. 

Many large petrochemical projects involve considerable investment. Plant output value can be measured in staggering amounts of money if value of lost production is calculated. An incorrect pressure switch installed on a compressor may have very little direct financial impact to a compressor manufacturer, but it can cause a loss to the user far in excess of the total value of the compressor package itself. Extra care must therefore be taken in compressor performance tests. In the planning of a pro- ject, testing has to be reviewed to ... 

Zeta potentials of floe produeed in the plant may also be measured as a means of eontrol. The zeta potential value for optimum eoagulation must be determined for a given wastewater by aetual correlation with jar tests or with plant performance. The control point is generally in the range of 0 to 10 millivolts. If good correlations can be obtained between some zeta potential values and optimum plant performance, then it is possible to make rapid measurements of particle charge to compensate for major variations in wastewater composition due to storm flows or other causes. 

Most recently, development testwork was performed on a large perovskite deposit (Powderhom) located in the USA. An effective beneficiation process was developed, where a concentrate assaying >50% Ti02 was achieved in the pilot plant confirmation tests [7]. During this development testwork, a number of different collectors were examined at different pH values. Figure 25.5 shows the effect of the different collectors on perovsikte flotation. The most effective collector was phosphoric acid ester modified with either fatty alcohol sulphate or petroleum sulphonate. 

Cotton dust sampling is a plant site test, normally involving unsophisticated field equipment, ever-changing plant conditions, and technician-level labor in performing many functions. However, with adequate equipment and attention to technique, we have found that good quality data can be obtained for each survey. The purpose of this paper is to share with you some of the instrumentation, equipment modifications and techniques we have studied and employed to obtain vertical elutriator (VE) data with average coefficients of variation less than 10%. 

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