ASME PTC 19.11:1997 pdf download Steam and Water Sampling, Conditioning, and Analysis in the Power Cycle
2.1 INTRODUCTION Sample point and analysis selection depend upon the purpose of testing. Each cycle component has a particular function. An agreement between the buyer and seller defines the specification.
The sam- pling and analysis are designed to determine that the component is functioning as specified and that it is functioning properly in operation. Proper func- tion is determined completely in a performance test by analyzing the sample to ascertain that all specifications are met. In operation the proper func- tion is assessed by less complete testing that concen- trates on the most important impurities and on the most likely fai lures.
This Section focuses on the selection of sample point locations and the analyses that are commonly conducted for those locations. Most of the sample points are concerned with water quality assurance and equipment performance evaluation. For these points, continuous analysis i s preferred. A few points are present largely to provide special data for analysis of problems. Grab samples will usually suffice at these points. Section 6 focuses on the analyses, their meaning, and the methods.
The following discussion reviews components of a thermal power cycle that can affect the chemistry of the water and steam. Figure 2.1 shows these components and sampling points schematically for a generalized fossil cycle. The steam cycle of nuclear power plants is similar to the fossil plants except that many nuclear plants do not have a deaerating feedwater heater and most nuclear plants have a moisture separator reheater that extracts moisture from the steam and superheats the vapor. Not all these components will necessarily be present in a particular application. Their presence in Fig. 2.1 does not imply that they are always needed.
Table 2.1 summarizes the sample points and the analyses. The text and Table 2.1 suggest more analyses than most plants would use. They should be used as a guide for consideration of analyses at each location. For proper testing, a sample must be provided at each cycle point for which there is a specification. Figures for other fossil cycles and for the BWR cycle can be found in Chapter 1 7 of the ASME Handbook on Water Technology for Thermal Power Systems (1 ).
Diagrams of PWR secondary cycles can be found in PWR Secondary Water Chemistry Guidelines – Revision 3 (2). Boiling water reactor systems are discussed, but the special problems associated with the radioactivity and gas concentrations in the water are not addressed here. In BWR systems, no pH control additives are present, therefore, specific conductivity is the only conductivity measurement used. Oxygen, chloride, and sulfate are the only other common analyses. When zinc i s added to the reactor to control radia- tion, a zinc analysis will be performed.
In systems with copper alloys in the condenser or feedwater heaters, the analysis of copper will commonly be appropriate. In all-ferrous systems, the analysis of copper will usually not be appropriate, but occasional analysis may be desired to be sure that no copper is entering the system from unsuspected sources.