No comments Raising a glass to measuring gas I indulged myself with a rare and geeky treat recently: half a day visiting a chloralkali plant by the Thames with BBC journalist friends. It was thrilling: a Mont Blanc of salt piled up beside a huge pool of brine; thick copper busbars delivering current to ranks of electrodes; and coloured pipes everywhere — yellow for chlorine, red for hydrogen and purple for the caustic soda. On one side of the lab was a small, gleaming gas chromatograph. But not far from it was a rather simpler wooden box with a handle.
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No comments Raising a glass to measuring gas I indulged myself with a rare and geeky treat recently: half a day visiting a chloralkali plant by the Thames with BBC journalist friends. It was thrilling: a Mont Blanc of salt piled up beside a huge pool of brine; thick copper busbars delivering current to ranks of electrodes; and coloured pipes everywhere — yellow for chlorine, red for hydrogen and purple for the caustic soda.
On one side of the lab was a small, gleaming gas chromatograph. But not far from it was a rather simpler wooden box with a handle. Louis Orsat was born in Paris on 14 August On the outbreak of the Franco—Prussian war, Orsat became an officer in the artillery. The war was a disaster for France. It was a terrible time — every circus, zoo and menagerie was pillaged in a desperate search for supplies. When the city finally surrendered, Bismarck ordered a savage bombardment of its centre before supplies were brought in.
As the city recovered, Orsat, who was awarded the Legion of Honour for his service, returned from combat to questions of combustion. The problem was fuel efficiency.
In the case of smelters, maintaining the optimum ratio of CO to CO2 is critical. So Orsat combed the literature. In , Henri Regnault and Jules Reiset had published a monumental paper, pages long, describing experiments to establish the precise mass balance of a living, breathing animal. Confining dogs, pigeons, rabbits, hens, even marmots to a bell jar, they used sequential selective absorption and then explosion with hydrogen to determine the quantity of each gas.
Modifications were quickly made to allow for every kind of gas analysis Orsat adapted this subtractive volumetric approach, shrunk down to fit in a robust wooden box. The apparatus consisted of three reagent tubes containing potash, alkaline pyrogallol and a solution of ammoniacal copper i chloride. These were connected on one side via a slender glass manifold to a squat, water-jacketed, gas burette that could be charged by raising a water-filled bottle linked to it by a rubber tube.
At the other end, the manifold received flue gases through a tube in which Orsat thoughtfully placed a wodge of cotton wool to keep the system clean. A small water aspirator allowed the manifold to be cleared of residual air. To operate, the bottle is raised, filling the burette with water.
On lowering the bottle, an aliquot of gas is drawn into the burette and the system is sealed. The tap to the potash tube is then opened and, by raising and lowering the water bottle several times, the gas is scrubbed of CO2. The tap is closed again and the volume of gas remaining is noted. Pyrogallol then accounts for the oxygen, and copper determines the CO. The remainder is assumed to be nitrogen.
On the km run from Paris to Tergnier he conducted 57 consistent analyses in succession. His point was that, although less rigorous than a formal lab analysis, his method allowed multiple determinations to be made quickly, which could be averaged. And you could do it anywhere. He patented his idea and it was immediately reported in the Chemical News and in Dinglers Polytechnisches Journal. Modifications were quickly made to allow for every kind of gas analysis. And to my delight, in , more than years after its invention, there it was still, being used to monitor the purity of chlorine by the Thames.
For me, it had, unquestionably, been a grand day out.
Construction[ edit ] The apparatus consists of an intake valve which feeds into a calibrated water or glycerin jacketed gas burette , this burette is then connected by tubing to two or more absorption pipettes containing chemical solutions that absorb the gases it is being used to measure. The intake and each of the absorption pipettes are valved with stopcocks to allow the movement of gas through the apparatus to be precisely controlled. For safety and portability, the apparatus is usually encased in a wooden box with a handle. The most common absorbents are: Potassium Hydroxide Caustic Potash for carbon dioxide Pyrogallol Pyrogallic Acid for oxygen Copper I chloride ammoniacal Cuprous chloride for carbon monoxide Any left over gas is assumed to be nitrogen, though other absorbents or vessels can be used to isolate additional gases. Platinum on asbestos for example can be used to determine the hydrogen content of a sample, and The Fischer type Orsat gas analyser for example uses a platinum electrode to explode the remaining gases with hydrogen. The base of the gas burette is connected to a leveling bottle which typically contains slightly acidulated water with a trace of chemical indicator typically methyl orange for colouration. The small amount of acid added to the water reduces the solubility of carbon dioxide.
FLUE GAS ANALYSIS BY ORSAT APPARATUS PDF
Aucune remarque pour cette diapositive Orsat appatarus 1. Introduction about Orsat Apparatus An Orsat gas apparatus is a piece of Laboratory Equipment used to analyze a gas sample Typically fossil fuel flue gas for its oxygen, carbon monoxide and carbon di oxide content. Although largely replaced by instrumental techniques, the Orsat remains a reliable method of measurement and is relatively simple to use. It was patented before by Mr. H Orsat. The apparatus consists essentially of a calibrated water-jacketed gas burette connected by glass capillary tubing to two or three absorption pipettes containing chemical solutions that absorb the gasses it is required to measure.
Orsat gas analyser