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Wondering how you should go about selecting the right analyzer to measure the heating value Measuring the absolute temperature of heat can be extremely important when it concerns industrial activities. Heat is generated during all chemical reactions, and so it can be said that an immeasurable amount of heat is being produced the entire day across the world. So why do we need the perfect analyser for measuring heat?
You may want to control the emission of heat – for instance, to conserve energy to reduce the production of harmful gases.You could do with a pollution control device like a flare stack then.Various wastes collected from chemical plants and refineries are transported to a flare stack for proper disposal. To ensure that the destruction is done properly and efficiently, it is imperative that the waste stream run at a particular minimum temperature. This is what a good analyser helps you identify with minimum effort.
Types of Measuring: Selecting the Right Analyzer to Measure Heating Value Research and development have led to a number of ways of measuring heat in a flare stack or otherwise. Technology is evolving to create even newer methods. At present, these are the most popular measuring technologies available in the market:
Gas Chromatography
Residual Oxygen
Thermopile
Micro-Combustion Calorimeter
Gas Chromatographs: Selecting the Right Analyzer to Measure Heating Value Gas Chromatographs are a costly investment but definitely worth a try. You have to inject the sample through the column first. After that, all the gasses pass through with a carrier gas at different speeds because of their varying chemical compositions. As a result, the compounds get separated. The gases take different amounts of time for the process based on their retention time. This also helps in determining the composition of the gas.
Gas Chromatographs do not exactly measure the heating value but break down the sample for easy identification. The GC can be classified as a batch- type and its response time is slow. The passing of the gas through the column may take 20 minutes or more for all the samples individually. Gas Chromatographs also fail to measure heavy hydrocarbons.Thermopile Calorimeters: Selecting the Right Analyzer to Measure Heating Value
Thermopile calorimeters work in a completely different manner. They seek to mix and then burn the sample gas with air. Then this air flow is controlled and monitored so as to maintain the same exhaust temperature. The airflow variations help to give an output signal which is proportional what is called the Wobbe Index. If you are wondering what that is, let us tell you. The Wobbe Index represents a value which is calculated by dividing the heating value with square root of the specific gravity.
The correct heating value measurement can be provided only if the specific gravity meter is entered. However, the Wobbe Index has one limitation. It represents the measurement of fuel mixtures which are not just natural gas. If the gaseous stream you are passing through it has heavy hydrocarbons, then there can be some problems. Thermopile calorimeters are prone to flameouts. They are also large and bulky with a number of moving parts that only increase the burden of maintenance.
Residual oxygen combustion calorimeters: Selecting the Right Analyzer to Measure Heating Value
Residual oxygen combustion calorimeters work on a unique principle. Their job is to measure the excess amount of oxygen that is left over after combustion of the sample is completely over. For this, the sample gas is heated and mixed with the air first. This mixture is then introduced into a combustion chamber by force. You would then measure the residual oxygen with the help of a zirconium oxide. Sometimes, we use an echem cell as well.
This residual oxygen content is essential in providing a correct value of the Combustion Air Requirement Index (CARI. ) It also correlates to the Wobbe Index. If you want to obtain an exact heating value, then you will need to add the details of an optional specific gravity cell. So this is not a direct measure of the heating value, but it is still something. The entire system can be inconvenient for mobility because of its size and bulkiness. Residual oxygen combustion calorimeters are also subject to pressure variations.
Micro-combustion calorimeters: Selecting the Right Analyzer to Measure Heating Value
Micro-combustion calorimeters, unlike the other three options, can give you a direct measurement of the heating value you are looking for. The fuel is first mixed with the process sample. This pre-made mixture is then totally incinerated by a metered flame which is under constant monitoring.
A thermocouple is used to measure even the smallest changes that occur in the flame temperature. The heating value rises with any increase in this temperature and falls with its decreasing value. Hence, they are directly proportional. This analyser is unique as it gives you a continuous and direct measurement of the heating value. The response time is also quick so that you face no delays. Micro-combustion calorimeters have a universal response. In fact, they are not even prone to flameouts or pressurized systems.
How do you select the Right Analyzer to Measure Heating Value?
All of these come with their respective sets of pros and cons, so you can choose an analyser based on your individual requirements and nothing else. Selecting the right analyzer to measure heating value will not be tough if you know what you are looking for.