Study On Hydration Activation Of Semi-dry Flue Gas Desulphurization Ash

Now the Semi-dry FGD(Semi-dry flue gas desulphurization) had occupy enough quotient in the FGD market just for its easier operation,smaller size,lower invest and be close to the particular circumstance of our courtry. But it still has some defects contrast to the Wet-FGD, for example, the lower efficiency of desulphurization and desulfurant sorbents utilization(in general calcium-based sorbents) and so on.There are many ways to improve the desulfurant efficiency and sorbents utilization, which one is that to increase the utilization through out the hydration of calcium-based sorbents and fly ash, And there are also many researches in this part in and out of our courtry. But the rearch of reactivity which is influenced by the hydration prepared with calcium desulfurant sorbents, fly ash and calcium sulphite is very few. As the Calcium sulphite is the main produce of the semi-dry FGD, it is very important to make some rearch about the reactivation of hydration, which is affected to the desulphurization, to increase the desulfurant sorbents utilization.According to the theoretic ratio of desulphurization ash which is produced in Semi-dry FGD, Several works have been developed from hydrating the simulated desulphurization ash prepared with Ca(OH)₂/CaSO₃/fly ash in a self-build experimental platform, in order to investigate the hydration effect from CaSO₃, and take hydration ash beyond drying in a fixed bed reactor to test desulphurization capable through in simulated flue gas.This article established under the different hydration temperature,the different hydration time and the certain ratio(A)(the ratio between water and fly ash/Ca(OH)₂) condition carries on the hydration experiment, and obtains that the hydration temperature and the hydration time is the main effect parameter for the hydration product activation, and present the positive proportion relationship with the hydration ash surface area, but the hydration influence of A which is fixed in the experiment is not obviously observed; The BET-SSA had appears the maximum value for 24.81m²/g in accord to the condition when A is 10, the hydration temperature is 80℃, the hydration time is 12 hours; The influence of CaSO₃ which accumulates to the hydration ash SSA is not big, after also A general increase of the BET-SSA is simultaneously observed for hydration ash prepared with CaSO₃ compared with hydration ash without CaSO₃. The SSA of hydration ash would increase with ratio of Ca(OH)₂ which exist in the mixed ash. That is to say, with the increase of Ca(OH)₂, the hydration ash activation can be streagthened much, and the whole capability can be enhanced.This article has carried on the further experimental confirmation after the hydration, established Ca/S, the ash humidity, the relative humidity of simulation flue gase as well as the different desulphurization temperature, carried on the simulation desulphurization experiment in a U-molding sand bed reactor, and Obtains that, the desulphurization efficiency increase with the growth of hydration time and the elevation of hydration temperature, that is the higher hydration temperature and the longer hydration time may produce some more active hydration ash; when the A is 10, the hydration temperature is 80℃, the hydration time is the 12h, the desulphurization temperature arrived 80℃, it produce a desulphurization efficiency maximum value of 46.31%; The desulphurization temperature and the flue gas absolute humidity have obviously affect the desulphurization efficiency, the desulphurization efficiency value present the inverse ratio with the desulphurization temperature but present the positive ratio with the flue gas absolute humidity value.The experiment research of this article has some actual instruction significance to the desulphurization sorbent preparation and the system design of sorbent produce. The two conclusion of influence. The exist of CaSO₃ is good to the SSA of hydration ash, and the increase of Ca(OH)₂ ratio is also behave the right influence to the whole desulphurization capability of the desulphurization ash. The two conclusion have offered important gist to the improvement of semi-dry desulphurization ash activation, and also gave the theory foundation to improving desulphurization efficiency which is through out hydration in desulphurization project.