How to calculate the combustion efficiency of a steam boiler?

Calculate the flue gas composition (both dry and wet basis) leaving a boiler. Calculate the combustion efficiency of a steam boiler Construct a Sankey diagram showing the heat balance analysis as a percent of heat input. 1. Combustion Air 2. Theoretical/Stoichiometric Air Requirement 3. Excess Air 4. Mole method of calculation

What should the air ratio of a boiler be?

Thus the higher the air ratio, the higher the flue gas losses. The flue gases should leave the boiler at a temperature as low as possible to minimize the flue gas losses. Usually either economics, equipment, or corrosion issues limit the flue gas to 150–200°C.

How much inert gas is needed for vacuum cycle purging?

The quantity of inert gas required for each cycle is 1-P vessel volumes. Let say, you want to purge from 21%-mole oxygen to 1%-mole oxygen. You use vacuum-cycle purging to 0.5 atm.

How to calculate the inert gas purging ratio?

The dilution ratio is (1/P) n. Where P is in atm and n is number of cycle. The quantity of inert gas required for each cycle is P-1 vessel volumes. Let say, you want to purge a vessel from 21%-mole oxygen to 1%-mole oxygen. You use inert gas to pressure to 5 atm. Guess number of cycle. We guess 2 cycles for started. (1-P) n = (1/5) 2 = 0.04

When is purging airflow before combustion is required?

It is required by the NFPA86 and should be done before each furnace heating system start-up. The purge of airflow removes gaseous combustibles in a furnace and replaces it with air. As mentioned in our previous post about the NFPA86, any residue can lead to a fire or explosion, so this is an important process.

What is the purpose of purging air in a furnace?

Purging airflow as outlined in the NFPA86 is a best practice for the operation and maintenance of a furnace. Purging airflow ensures that any flammable vapors or gases that might have entered the furnace during shutdown are cleared.

How long does it take to purge air from boiler?

Doing this resulted in a small amount air air being purged but no real heat gain. This heating season the same problem and I followed the previous instructions with no real change. I have spent about 4 days trying to purge the system with no real heat gain. One full afternoon was spent bleeding the air from the check valve at the boiler.

How is the total combustion air flow in a boiler controlled?

The total combustion air flow to a balanced draft boiler is generally controlled by adjusting the quantity of air from the forced draft fan and controlling the furnace draft with the induced draft fan in relation to the fuel flow.