A thermal device and method for increasing the temperature of boiler wet desulfurization net flue gas

Abstract

The invention relates to a thermal device and method for increasing the temperature of boiler wet desulfurization net flue gas. The thermal device includes: a boiler body, a tail flue gas treatment device and a net flue gas heating device. The tail flue gas treatment device includes a dust collector and a wet process Desulfurization device, the boiler flue gas passes through the wet desulfurization device to obtain net flue gas, and the net flue gas is heated by the net flue gas heating device and then discharged into the chimney; the method includes: adjusting the bypass flue into the bypass flue Use the hot flue gas in the bypass flue to heat the cold air in the air heater, send the obtained high-temperature hot air to the clean flue gas channel after the wet desulfurization device, and use the mixer to mix the high-temperature The hot air is mixed with the clean flue gas, the temperature of the mixed flue gas is heated above the acid dew point, and it is discharged through the chimney. The invention uses hot air as a heat transfer medium, transfers the energy of hot flue gas to clean flue gas, reduces chimney corrosion, expands the diffusion range of flue gas, and prevents gypsum rain from forming around the power plant.

Description

technical field [0001] The invention relates to a thermal device and method for increasing the temperature of boiler wet desulfurization net flue gas. Background technique [0002] Installing wet desulfurization devices on coal-fired boilers to purify acid gases in flue gas is a relatively mature technology, which has been widely promoted and applied in thermal power plants. After wet desulfurization, the clean flue gas carries a little water droplets and is in a saturated state , SO3 gas that is not captured by the desulfurization system is easily dissolved in saturated wet flue gas to form sulfuric acid, which corrodes the flue and chimney behind the desulfurization. In order to solve this problem, conventional methods use steam to heat the clean flue gas, set up a small oil gun for heating and a flue gas-flue gas heat exchanger (GGH). , leading to corrosion of the heat exchanger and failure; heating with a small oil gun requires the oil gun to be arranged in the clean fl...

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Problems solved by technology

In order to solve this problem, conventional methods use steam to heat the clean flue gas, set up a small oil gun for heating and a flue gas-flue gas heat exchanger (GGH). , leading to corrosion of the heat exchanger and failure; heating with a small oil gun requires the oil gun to be arranged in the clean flue, which not only consumes high-quality fuel, but also corrodes the small oil gun and ignition system with wet flue gas, and the reliability is not high; adopting GGH , using the original flue gas to heat the clean flue gas, due to the small heat transfer temperature difference, the area of ​​the rotary heating surface is large, and the flue gas after desulfurization carries a certain amount of powder such as gypsum, which leads to the blockage of the corrugated plate of the heat exchanger, GGH The running resistance is too large, affecting the normal operation of the unit

[0003] In order to improve the reliability of unit operation, GGH is canceled when designing the desulfurization system of most power plants, and the wet flue gas after desulfurization is directly discharged into the wet chimney. Necessary anti-corrosion measures are taken during design to prevent corrosion of the flue and chimney after desulfurization; In the power plant where GGH has been installed, in order to improve reliability, the GGH was removed, resulting in low-temperature corrosion of the subsequent flue and chimney

At present, the clean flue gas after desulfurization is discharged directly without heating. Regardless of whether the flue and chimney have taken anti-corrosion measures, the acid gas in the wet flue gas will be absorbed when passing through the condensate droplets on the inner wall of the flue and chimney, forming strong acidity. The liquid corrodes and damages the wear-resistant materials on the inner wall of the flue and chimney, causing irreparable damage to the flue and chimney, greatly reducing the operating reliability of the unit, shortening the maintenance cycle of the boiler, anti-corrosion and maintenance costs of the flue and chimney Increase

[0004] In addition, the clean flue gas is discharged directly without heating, resulting in a decrease in the airflow velocity at the chimney outlet, weakening the lifting effect of the wet flue gas through the chimney, and insufficient power for the airflow to rise into the atmosphere, which can easily form gypsum rain and acid droplet settlement around the power plant. The environment around the power plant has suffered a major blow, making it difficult to meet the post-evaluation requirements of the power plant environment

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