Flue gas waste heat recovery method and system for oil and gas boiler

Abstract

The invention discloses a recycling method and a system for the afterheat of the smoke gas of oil and natural gas boilers. The method comprises the steps as follows: the smoke gas with high temperature is pre-sprayed and cooled in the inlet pipe seat of the smoke gas with high temperature through a nozzle before entering the main cylinder of an afterheat recycling device; the smoke gas with high temperature after being pre-sprayed and cooled is led to enter into the main cylinder along the tangent direction of the main cylinder, rotate and float upwards in the main cylinder; the smoke gas with high temperature which rises in a rotating way is mainly sprayed and cooled in the middle upper part of the main cylinder through the nozzle; the smoke gas with high temperature flows out of the main cylinder from the upper part of the main cylinder after conversely contacting and changing heat with spraying water fog. In the invention, pre-spraying and cooling are adopted to lead the smoke gas with high temperature to be directly contacted and mixed and change heat with the spraying and cooling water fog when the smoke gas with high temperature passes through a smoke gas inlet; on one hand, the burden of a mist trap can be reduced; on the other hand, the burden of heat and mass exchange of the main cylinder can be reduced, thus leading the volume of the main cylinder to be smaller and the structure of the main cylinder to be more compact.

Description

technical field [0001] The invention relates to a waste heat recovery method and system, in particular to a flue gas waste heat recovery method and system for a fuel-fired gas boiler. Background technique [0002] The flue gas of conventional fuel gas contains a large amount of water vapor. The volume share of water vapor in the flue gas of an oil-fired boiler is about 13%, and that of water vapor in the flue gas of a gas-fired boiler reaches 19%. ℃, or even higher, so the water vapor in the flue gas is discharged with the flue gas in gaseous form, and the latent heat of condensation of the water vapor cannot be effectively utilized, so the heat carried by the water vapor in the flue gas is the main heat loss of the boiler exhaust. part. Taking a certain natural gas as an example, its high calorific value Q gw =39.08MJ / Nm 3 , low calorific value Q dw =35.16MJ / Nm 3 , the difference between the two is 3.92MJ / Nm 3 , that burns 1Nm 3 The water vapor produced by natural ga...

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Problems solved by technology

The atomizing nozzle can make the atomized particles of the fully atomized one-time hot water exchange directly contact with the high-temperature flue gas for heat exchange, fully recover the latent heat of condensation of water vapor in the high-temperature flue gas, and greatly improve the heat exchange efficiency. However, due to the high-temperature flue gas The sensible heat and latent heat in the air need to be absorbed by the atomized particles of the primary water exchange in the heat exchange space at the same time. Therefore, the work load of this device is relatively large, and the structure of the entire device needs to be made very large. Thermal efficiency is also difficult to fully improve

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