The thermal efficiency of medium and small gas-fired boilers can be calculated by the following formula:
η=96.646-0.043θ+0.248D
θ is the exhaust temperature, ℃
D is rated evaporation t/h
(1) The estimation formula contains only two parameters, exhaust gas temperature and rated evaporation. It is very convenient to calculate and analyze. The influence of exhaust gas temperature on thermal efficiency is quantitatively given. For every 10 degree reduction of exhaust gas temperature, the thermal efficiency is increased by 0.43%. The dew point temperature of gas boiler is very low. Reducing exhaust gas temperature and recovering sensible heat of flue gas can increase thermal efficiency by 2%-3%. The energy-saving potential is huge.
(2) On the basis of WNS gas boiler, the estimation formula synthesizes the technical data of gas boiler manufacturer in industry, carries on data fitting, and obtains the approximate formula by linear processing, which has high accuracy.
(3) Based on the characteristics of fuel combustion and heat dissipation of small and medium-sized gas-fired boilers, the estimation formula is further analyzed and simplified by heat balance, which is more suitable for small and medium-sized gas-fired boilers below 10t/h.
(4) When the estimation formula is applied to gas-fired hot water boilers, the rated thermal power of hot water boilers can be converted into the corresponding rated evaporation of steam boilers.
(5) The estimation formula can also be used as a reference for testing and evaluating the thermal efficiency of gas-fired boilers in rated load operation. Considering the influence of heat dissipation loss, it should be noted that some modifications should be made in use under non-rated conditions.
