1454 Stack Gas Analysis

As explained in Section 14.2.1, proper maintenance of boilers depends heavily on knowledge of stack-gas composition. If there is too much molecular oxygen, the boiler is operating inefficiently; if there is too much carbon monoxide or too much smoke, the boiler is operating inefficiently and creating an operating hazard. Thus it is important to keep track of O2, CO, and smoke. Three types of monitoring equipment meet these needs: Orsat kits, permanently mounted meters, and smoke detectors.

Orsat Apparatus

The Orsat analysis kit consists of three tubes filled with potassium hydroxide, potassium pyrogallate, and cuprous chloride, respectively. Flue gas is introduced into all three tubes, and the amount of carbon dioxide, oxygen, and carbon monoxide removed in the first, second, and third tubes, respectively, indicates the proportion of those gases in the flue gas. Any gas remaining is assumed to be nitrogen. This apparatus is capable of accurate readings when representative samples of flue gas have been taken from different points in the flue stream, when the apparatus does not leak, and when the operator is well trained in its use.14

Smoke Detectors

Smoke detectors work by comparing the amount of light going through a sample of smoke with some standard shades. If a Ringlemann scale is used, the smoke number is between 1 and 4, if the Bacharach scale, between 1 and 9. Smoke detectors can be either portable or permanently mounted.

0 0

Post a comment