Orsat apparatus

The analysis of flue gas provides a measure of the efficiency of the combustion process and is given in percentages by volume. Traditionally, flue gas measurements have been taken using an Orsat apparatus, although in many industrialized countries this device has long been superseded by a wide variety of very accurate, portable, and precalibrated electronic equipment. 

Some examples of the type of results expected when using an Orsat apparatus are shown below. 

In some Orsat apparatus models, water vapor may also be determined hydrogen may also be determined by its oxidation to water vapor. 

Modem electronic replacements for the Orsat apparatus include equipment manufactured in the United States by Bacharach, Inc. (www.bacharach-inc.com). This company produces handheld and boxed instruments that can be employed as comprehensive combustion and environmental analyzers, gas burner combustion testers, single gas analyzers, draft gauges, smoke test sets, sling psychrometers, and the like. 

The gaseous products were analyzed by means of an Orsat apparatus and then entered upon special form, under "Analysis.of Oases (Volume per cent). An example of ealen is given in Ref 1, p 94... 

Analysis of gas. — The sample of gas thus obtd is then analyzed for carbon dioxide, oxygen, carbon monoxide, hydrogen, and methane oh a BurMines Orsat apparatus. Oxides of nitrogen are tested for in a seoarate sample. The nitrogen is detd by difference. If the volume of the entire apparatus, the temp and pressure of the gas, and its compn as given by analysis are known, die amounts of the different constituents produced by the explosive can be computed... 

The rate of formation of the dehydration product isobutene was analysed in an Orsat apparatus and the percentage conversion of t-BuOH was calculated. 

The apparatus to do these separations is called the Orsat apparatus. The sole supplier is Burrell Scientific Inc., 2223 5th Ave., Pittsburgh, PA 15219 (412-471-2527). They have everything needed, including replacement parts, reagents, and directions. 

Figure 42-3, p.495, shows a portable Orsat apparatus. Its use in step-by-step detail is fully described in the accompanying experiment. In general, all absorption bottles are filled to their zero mark, the gas buret (extreme right) is zeroed, and the sample collection bottle is connected by a rubber tube at point A. 100 mL of sample is drawn into the gas buret and then passed successively into each absorption bulb. 

Figure 42-3. A portable Orsat apparatus. (Courtesy - Burrell Scientific, Inc., Pittsburgh, PA)...

Why is the water in the Orsat apparatus made slightly acidic ... 

Read the Techniques section on the Portable Orsat apparatus, p. 494. 

Analyses. The analytical methods used were described earlier (9). Gas analyses were performed with a modified Orsat apparatus—a method which can be considered satisfactory only if the gases are to be used as fuel, which was the intention for the first generation of AST recovery systems. No analytical differentiation of the unsaturated hydrocarbons can be obtained with the concentrated sulfuric acid used to absorb the so-called illuminants. Subsequent semiquantitative infrared analyses of gas samples indicated that approximately half of the illuminants are ethylene, and more than one-third are acetylene, with some other unsaturated compounds also present. A gas chromatograph is now being calibrated to determine individual unsaturated hydrocarbons quantitatively and to identify various trace gas components. 

Exit flue gas composition can indicate excess or low feed of fuel oil (or combustible reactants such as sulphur, ammonia). Provide online analyser for C02 %, free oxygen %, etc. or check gas analysis by Orsat apparatus. Test exit gases for sooty particles by clean filter paper for any excess oil feed. 

Orsat apparatus (for gas composition analysis) for detecting malfunctions of scmbbers/process reactors etc. 

Gaseous impurities. A known amount of chlorine gas is passed through a solution of potassium iodide or phenol to absorb the chlorine. The residual gases (O2, N2, H2, CO, CO2) are collected in a gas burette, measured, and analyzed by gas chromatography or with an Orsat apparatus. 

Name a few modern instrumental methods of gas analysis and compare the usefulness of the Orsat apparatus against them. 

These gases are not absorbed by any of the three absorbents used. Unless special modifications are made in the Orsat apparatus to measure their amounts, they will be reported as N2. Hence the results of N2 will be higher. 

Analysis by Orsat apparatus is also known as constant pressure volumetric analysis or chemical absorption analysis. 

Scope is limited to the analysis of CO2,02, CO and N2 (H2 a few hydrocarbons with specially equipped laboratory Orsat apparatus) yet the information available is quite useful for regulating combustion. 

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