Segmented calcium and sodium double alkali method desulfurizing technology and device thereof

Abstract

The invention discloses a sectional type natrium-calcium double alkali desulfurization process, which integrates calcium group desulfurization and flue gas desulfurization of alkali-natrium method in one reactor to make the flue gas preliminary desulfurize using calcium group and then finish desulfurize using natrium group to meet the discharging require. The invention also discloses a device using the sectional type natrium-calcium double alkali desulfurization process. The calcium group desulfurization sectional absorber and alkali-natrium method desulfurization sectional absorber are mounted in the same reactor, to dually desulfurize to the flue gas, at the same time avoid taking the seriflux to the demister, and simplify the cleaning device of demister. The cleaning of the demister uses clear liquid of natrium group to reduce the use of water in the process.

Description

technical field [0001] The invention relates to a flue gas desulfurization process, in particular to a segmented sodium-calcium double-alkali desulfurization process and a device thereof. Background technique [0002] In the currently most commonly used wet calcium-based desulfurization process using lime or limestone as a desulfurizer, the circulating fluid is often in the form of slurry due to the poor solubility of the desulfurizer and desulfurization products. After desulfurization, part of the slurry droplets will be brought into the demister along with the flue gas to block the demister. It needs to be equipped with a complete set of complex cleaning system strictly controlled by procedures. On the other hand, under the same liquid-gas ratio, the desulfurization efficiency of calcium-based desulfurization is lower than that of sodium-based desulfurization, and the removal rate of low-concentration sulfur dioxide is lower. In order to meet the emission standards of fl...

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Problems solved by technology

On the other hand, under the same liquid-gas ratio, the desulfurization efficiency of calcium-based desulfurization is lower than that of sodium-based desulfurization, and the removal rate of low-concentration sulfur dioxide is lower

In order to meet the emission standards of flue gas, currently calcium-based desulfurization is often operated with a large liquid-to-gas ratio, resulting in high comprehensive energy consumption and complex systems for calcium-based desulfurization

[0003] In addition to the problem of increased ash formation resistance of the mist eliminator, the current common treatment method is to blindly configure a more complex and efficient cleaning system for the mist eliminator, and frequently perform intermittent cleaning of the mist eliminator with process water

However, due to the online intermittent cleaning, one will cause fluctuations in the resistance of the flue gas system and affect the negative pressure of the furnace, and a large amount of flushing water entering the desulfurization liquid system will also affect the stability of the concentration of the desulfurization liquid. During the flushing process, it will cause a short-term serious phenomenon of water in the flue gas and shorten the service life of the mist eliminator, which does not fundamentally solve the problem of ash clogging of the mist eliminator

[0004] Another kind of sodium-calcium double-alkali process commonly used in small and medium-sized boiler flue gas desulfurization projects uses clear liquid absorption, which solves the problem of ash clogging in the demister and avoids the complicated cleaning problem of the demister. However, due to the joint action of heavy metal ions (introduced in the flue gas) and oxygen (introduced in the flue gas) in the flue gas, the oxidation of the desulfurization liquid is obvious, especially for some flue gases with strong oxidation tendency (high oxygen content and / or the flue gas contains more iron, manganese, vanadium and other impurities), often resulting in large sodium and alkali consumption, easy fouling and blockage of the device, increased system resistance, and difficult operation

Since the price of sodium-alkali is much higher than that of calcium-alkali, when dealing with high-concentration sulfur dioxide-containing gas, the amount of sodium-alkali lost with the discharge and oxidation of desulfurization slag is very high, which restricts the application of sodium-based desulfurization technology

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