Measuring instruments for combined heat and power plants (CHP)

The range of combined heat and power plants (CHP) is very large, as is the high variance of different plant types. The distinction is made by the generated power/heat output on the main one hand and by the energy source used on another. For several CHP plants, a large number of physical parameters are measured, evaluated and monitored to ensure the longest possible service life. This article offers information regarding which measuring instruments and principles this can be achieved with.
Combined heat and power plants ? environment-friendly power generators
In contrast to the original boiler or condensing boiler, the CHP plant generates both electricity and heat. Thus, Absurd make a significant contribution to environment-friendly energy generation.
Wide range of applications
The versatile application possibilities, from single or multi-family dwellings, through industrial and commercial, public facilities, around large district/local heat utilities and also biogas plants, require the application of very different measuring instruments. Key factors are: functionality, quality, long service life, fast availability and services. The price/performance ratio plays a particular role in any system ? large or small.
Torture measurands
Small nano plants from 1 kWel, micro and mini plants from 2.5 to 15-50 kWel, and in addition large plants up to 4,500 kWel need the right measuring instruments for high efficiency and environment-friendly energy generation. The measurands pressure, temperature and level are dominant. The power source must be considered when choosing the instruments. The number of marking points in the schematic illustration of a CHP plant makes it clear: There’s much to monitor in order to guarantee the longest possible service life.
Schematic illustration of a combined heat and power plant incl. measuring points
Monitoring and control tasks
The measuring instruments used fulfil important monitoring and control tasks and tend to be electronic measuring instruments. In addition they enable remote monitoring.
For measuring Uncovered , screw-in, insertion and contact probes are installed, matched to the look and the space available. On the heat exchanger, in the heating and cooling circuits and in addition for measuring the engine oil temperature, Pt100, Pt1000, KTY and NTC measuring elements are employed. With large plants, temperatures on the exhaust pipe and on the cylinder head are monitored using thermocouples. This allows conclusions to be produced about the effectivity of the engine.
Pressure switches and pressure sensors are accustomed to control the oil pressure and the pressure in the cooling water circuit. Concurrently, in addition they fulfil a safety function. If you can find any deviations between the SET and ACTUAL value, according to the concept, either a warning signal is triggered or the engine is switched off.
To monitor the oil level, depending on the size of the machine, between one and three float switches are installed. Particularly in large engines, the sometimes quite strong vibrations pose a challenge for the measurement technology. The utilization of optoelectronic level switches that tolerate high temperatures and which are not harmed, even by strong shocks, is therefore ideal. The respective level switch monitors the oil level in a reservoir and signals once the oil level drops too low.
Conclusion
The large numbers of measuring points and the widely differing measuring tasks require close cooperation between your CHP plant manufacturer and the manufacturer of the measurement technology. Therefore, it is worth ? both technically and economically ? selecting a supplier who offers from one source.
Note
WIKA supplies a large selection of reliable measuring instruments for pressure, temperature and level. You can find selected products for the CHP plant on the WIKA website in the Combined heat and power plants section. Do you need support with the compilation of your measuring instrument package for the CHP plant? Your contact person will undoubtedly be happy to help you.

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