Gas-fired boiler afterheat recovering system and recovering method

Abstract

The invention discloses a gas-fired boiler afterheat recovering system and a gas-fired boiler afterheat recovering method. A bypass flue is parallelly connected onto a main flue, a bypass flue butterfly valve, a boiler coal economizer, an air preheater and a condensing type heat exchanger are sequentially and serially connected onto the bypass flue, the bypass flue is communicated with a bypass chimney, a water inlet of a heat exchange pipe of the boiler coal economizer is connected with a water tank through a water supply pipeline, a water outlet of the heat exchange pipe is communicated with a boiler through a pipeline, an air inlet of a heat exchange pipe of the air preheater is communicated with a fan through a pipeline, an air outlet is communicated with a boiler combustion-supporting air inlet pipe through a pipeline, a water inlet of a heat exchange pipe of the condensing type heat exchanger is communicated with the water tank through a descending pipe, and a water outlet is communicated with the water tank through an ascending pipe. The gas-fired boiler afterheat recovering system and the gas-fired boiler afterheat recovering method have the advantages that the structure is simple and compact, the size is small, the boiler smoke discharge temperature is lowered to 40 to 50 DEG C, in addition, all recovered heat is used for a boiler system, the boiler smoke discharge temperature is greatly lowered, the boiler heat efficiency is greatly improved up to more than 100 percent, and the goal of greatly improving the utilization rate of energy sources is reached.

Description

technical field [0001] The invention belongs to the field of boiler waste heat recovery, in particular to a gas boiler waste heat recovery system and recovery method. Background technique [0002] In order to improve the air quality in cities, the use of clean energy has become a trend. In recent years, with the commissioning of large-scale pipeline projects such as the West-East Gas Pipeline, the consumption of natural gas has increased day by day. From 2000 to 2010, China's natural gas consumption grew at an average annual rate of 16%, reaching 107 billion cubic meters in 2010. China has become the world's fourth largest natural gas consumer. The International Energy Agency predicts that China's natural gas consumption will reach about 331 billion cubic meters in 2030, becoming the world's second largest natural gas consumer, accounting for 7% of the world's total consumption. By the end of 2012, my country's natural gas consumption market has expanded to 30 provinces, ci...

AI Technical Summary

Problems solved by technology

At present, the exhaust gas temperature of natural gas hot water boilers for heating is generally 200°C, while the gas-fired steam boilers used by industrial enterprises are generally at 200-240°C. At this temperature, the high-temperature flue gas also takes away a lot of sensible heat. A large smoke exhaust loss is formed. At the same time, water vapor cannot be condensed to release heat, and the heat is wasted with the flue gas discharge. Generally, the thermal efficiency of the boiler can only reach 85% to 92% (calculated according to the low calorific value of natural gas)

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