Orsat apparatus

Orsat Gas appratus

1. ORSAT’s APPARATUS Submitted to: Dr. (Mrs.) Poonam Syal Submitted by: Mr. Dhruv Upadhaya 162510 ME [I&C] Regular

2. CONTENTS Introduction Orsat’s Apparatus Construction Working Precautions

3. INTRODUCTION To have proper control on combustion process, an idea about complete combustion of fuel is made by the analysis of flue gas. CH 4 + 2O 2 CO 2 + 2H 2 O 2CH 4 + 3O 2 2CO + 4H 2 O If complete combustion of fuel takes place then Carbon Dioxide is released. If incomplete combustion of fuel takes place then Carbon Monoxide if released.

4. Thus, if the gases contain considerable amount of carbon monoxide, it indicates that incomplete combustion is occurring (i.e. considerable wastage of fuel is taking) Also indicates the short supply of oxygen for combustion if the flue gases contain a considerable amount of oxygen, it indicates the oxygen supply is in excess, though the combustion may be complete. The analysis of flue gases made with the help of ORSAT’S APPARATUS.

5. ORSAT APPARATUS

6. CONSTRUCTION Consists of a water-jacketed measuring burette, connected in series to a set of three absorption bulbs, each through a stop-cock. The other end is provided with a three-way stop-cock, the free end of which is further connected to a U-tube packed with glass wool (for avoiding the incoming of any smoke particles, etc.) The graduated burette is surrounded by a water-jacket to keep the temperature of the gas constant during the experiment. The lower end of the burette is connected to a water reservoir by means of a long rubber tubing. The absorption bulbs are usually filled with glass tubes, so that the surface area of contact between the gas and the solution is increased.

7. The absorption bulbs have solutions for the absorption of CO 2 , O 2 and CO respectively. First bulb has ‘potassium hydroxide’ solution (250g KOH in 500mL of boiled distilled water), and it absorbs only CO 2 . Second bulb has a solution of ‘alkaline pyrogallic acid’ (25g pyrogallic acid+200g KOH in 500 mL of distilled water) and it can absorb CO 2 and O 2 . Third bulb contains ‘ ammonical cuprous chloride’ (100g cuprous chloride + 125 mL liquor ammonia+375 mL of water) and it can absorb CO 2 , O 2 and CO. Hence, it is necessary that the flue gas is passed first through potassium hydroxide bulb, where CO 2 is absorbed, then through alkaline pyrogallic acid bulb, when only O 2 will be absorbed (because CO 2 has already been removed) and finally through ammonical cuprous chloride bulb, where only CO will be absorbed.

8. Flue gas KOH(CO 2 ) Water reservoir Rubber tube Water tube Fused Calcium Chloride Three way stopcock alkaline pyrogallic acid (O 2) ammonical cuprous chloride (CO) ORSAT APPARATUS graduated burette

9. WORKING Flue gas is passed through fused Calcium Chloride which absorbs the water vapor present due to its hygroscopic properties. Three way stopcock is opened and the flue gas is filled in the graduated burette. The whole set up is water jacketed to maintain a constant temperature. The stopcock of the KOH reservoir is opened and the water reservoir is moved up. Water inflows in the graduated burette and pushes the gas to flow in the KOH reservoir.

10. In that reservoir carbon dioxide is absorbed. The whole CO 2 in the sample is absorbed. The water reservoir is brought down so that the air again can rush to the burette. Again the stopcock of the alkaline pyrogallic acid reservoir is opened and the water reservoir is moved up. Water inflows in the graduated burette and pushes the gas to flow in the alkaline pyrogallic acid reservoir where the absorption of Oxygen takes place. The same process is repeated with the ammonical cuprous chloride reservoir. The Volume increase of all the reservoir is measured and the amount of Carbon Dioxide, Carbon Monoxide and Oxygen are determined.

11. PRECAUTIONS The reagents in the absorption bulb 1, 2 and 3 are brought to the etched mark levels one-by-one by operating the reservoir bottle and the valve of each bulb. Then their respective valves are closed. All the air in the reservoir bottle is expelled to atmosphere by lifting the reservoir bottle and opening the three-way to atmosphere. It is quite necessary to follow the order of absorbing gases: CO 2 first, O 2 second and CO last. This is because the absorbent used for O 2 (i.e., alkaline pyrogallic acid) can absorb only some CO 2 and the percentage CO 2 left would be less; while the percentage of O 2 thus-detected would be more. The absorbent used for CO 2 , however, does not absorb O 2 or CO 2 . The percentage of CO in the flue gas is very small and this should be measured quite carefully.