Find out how correct sampling, sample coolers and the entire SWAS (Steam and Water Analysis System) improve the analysis of boiler water, condensate and steam. Tips on sizing and sample conditioning.
Safe and representative steam sampling – the basis for reliable analyses
Thorough analysis of boiler water, condensate and steam begins long before the sample reaches the instrument. A well-designed SWAS system (Steam & Water Analysis System) is essential for reliable and representative steam sampling in power stations and the process industry. With the correct sample conditioning, parameters such as conductivity, pH, sodium, silica and dissolved oxygen can be analysed with a high degree of accuracy.
A common mistake is to focus solely on the analytical instrument. In practice, the sampling process is at least as important. If the sample changes on its way from the process to the analyser, the measurement result will not be reliable.
Representative samples ensure safer operation
International guidelines from organisations such as ASME, ASTM and EPRI recommend that samples be cooled to around 25 °C prior to analysis. Correct sample conditioning reduces the risk of temperature, pressure or phase changes affecting the measurement results, whilst also contributing to a safer working environment.
A complete sampling system normally consists of several components which, together, ensure the correct flow, pressure and temperature, for example:
- sampling point
- Sample Cooler
- pressure reduction
- thermal shut down valve
- flow indicator
- back pressure relief valve
All components must work together to ensure that a representative sample is taken from the process.
Sample Coolers – the heart of a SWAS system
Sample coolers are used to lower the temperature of hot water and steam samples quickly and in a controlled manner. The aim is both to protect operators and analytical instruments and to ensure that the chemical composition of the sample does not change prior to analysis.
Choosing the right size for a test chiller involves much more than simply selecting the correct size. Factors such as test flow rate, cooling water flow rate, counter-current cooling, choice of materials and the desired outlet temperature all affect both performance and service life.
Many facilities use a two-stage cooling system, in which the first cooler reduces the temperature significantly, whilst a second cooler fine-tunes the temperature to the level required by the analytical instruments.
Sentry’s sample coolers are designed to provide fast, safe and efficient cooling of steam and water samples, and are used in power stations and process plants around the world.
The right temperature provides better analysis results
Many analyses are directly affected by the temperature of the sample. Excessively high temperatures can lead to measurement errors, reduced repeatability and, in the worst case, damage to sensitive analytical instruments.
A correctly sized sample cooler should therefore maintain a stable sample temperature even when process conditions vary. At the same time, it is important to avoid unnecessarily low temperatures, as this can increase cooling water consumption without improving the analysis.
Oleinitec provides support throughout the entire sampling process
Oleinitec is the distributor in Sweden for Sentry Equipment and offers complete SWAS solutions, sample coolers and components for steam sampling and water analysis in the power generation and process industries. We assist with sizing, design and the selection of the right equipment to ensure a safe and reliable sampling process.
If you’d like to find out more, Sentry’s technical articles on steam sampling, sample coolers and optimising sample temperatures include practical examples and design advice.
Do you want to know more? Please feel free to contact Oleinitec if you would like to discuss SWAS systems, sample coolers or water chemistry analysis solutions. You can also read the in-depth articles from Sentry Equipment via the links below.
https://www.sentry-equip.com/the-shield/power-generation/cool-it-down-with-sample-coolers
Please feel free to contact us today and we’ll be happy to help you!