Gas-fired boiler waste heat energy-saving recovery method

Abstract

The invention discloses a gas-fired boiler waste heat energy-saving recovery method. According to the gas-fired boiler waste heat energy-saving recovery method, low-temperature circulating water absorbs heat in a gas-water heat exchanger to increase the temperature and then to serve as the low-temperature heat source of an absorbing type heat pump unit evaporator; cooling water inside an absorbingtype heat pump unit condenser is depressurized by a throttle valve and enters the evaporator for evaporation into vapor; the vapor enters an absorber and is absorbed by lithium bromide concentrated solution from a generator; in the generator, the lithium bromide concentrated solution absorbing the vapor from the evaporator is diluted into dilute solution to release heat to primarily heat returnedheating water; a solution pump lifts the dilute solution into the generator from the absorber; in the absorber, the dilute solution is concentrated into concentrated solution, released vapor enters the condenser, and the concentrated solution returns to the absorber; the vapor from the generator heats the returned heating water again. The gas-fired boiler waste heat energy-saving recovery methodcan recover waste heat of discharged smoke of a gas-fired boiler to the maximum degree, improve the heat efficiency of the boiler and reduce gas consumption.

Description

technical field [0001] The invention belongs to the technical field of waste heat recovery, and in particular relates to an energy-saving recovery method for waste heat of a gas boiler. Background technique [0002] With the continuous seriousness of air pollution in my country and the increasing pressure of energy conservation and emission reduction, coal-fired boilers, which are the main source of heat supply, are gradually restricted, and the application of gas-fired boilers is developing rapidly. Although the design thermal efficiency of gas-fired boilers is relatively high, the actual measurement results show that the operating thermal efficiency of gas-fired boilers is generally in the range of 80-85%, which is far lower than the design thermal efficiency and the national standard value. Among them, the heat loss of exhaust gas is the largest item among the various losses of gas-fired boilers, generally more than 10%, which is the focus of energy saving. [0003] At p...

AI Technical Summary

Problems solved by technology

For steam boilers, the boiler feed water can be heated to reduce the exhaust gas temperature, and the recovery effect is better; for hot water boilers, due to the high heating return water temperature (generally above 60°C), the air coefficient of boiler combustion is generally between 1.1 and 1.3 The corresponding dew point temperature of water vapor in the flue gas is between 55-60°C. Therefore, the common exhaust heat recovery device can only recover the sensible heat in the exhaust gas of the gas-fired hot water boiler, but cannot recover the water in it. The heat of condensation of steam has a limited effect on improving the thermal efficiency of gas-fired boilers