Acid solution spray dry-process flue gas desulfurization and modulating intensification method

Abstract

The invention relates to a kind of acidic-solution spraying dry-way stack-gases desulfurization and tempering intensification method, which is applicable in the field of stack gases desulfurization or desamination and the field of stack gases tempering. Spraying the acidic solution whose PH<=5.5 in the form of vaporific into stack gases, which contains fly ash or granule of the desulfurization agent in the desulfurization reactor or the flue between the tail of coal burning boiler and dust remover. So it can make the fog drip catch fly ash or granule of the desulfurization agent in stack gases efficiently and then form the liquid film on it. With the moisture in fog drip evaporating rapidly, the PH of remaining liquid film tends to step down and the acidity tends to be higher so that it is favorable to digesting the alkaline metal ion and the transition state metal ion having catalysis and oxidization. Then the sweet effective constituent granule contained in granule can be activated and participate in desulfurization reaction. In the result of that described above, then invention can intensify to decline the stack gases tempering of dust to the resistance and the oxidative extent to the sweet by-product; it can decline the proportion of astable sulfite; it can reduce the consumption of Ca matrix desulfurization agent for carbon dioxide; and finally it can improve the use ratio and the sweet efficiency of the drying-way desulfurization agent.

Description

technical field [0001] The invention relates to the field of flue gas desulfurization or denitrification and dust removal, in particular to the technical field of flue gas conditioning and tempering treatment for dry desulfurization or denitrification of flue gas from coal-fired boilers and reduction of dust emissions from electric dust removal. Background technique [0002] Existing coal-fired boiler flue gas desulfurization technology can be roughly divided into wet method, semi-dry method, dry method and special method from the use of desulfurizer and the dry and wet form of desulfurized products. Among them, the wet method has become the mainstream desulfurization technology for medium-high sulfur-containing coal and large-scale coal-fired units of 300MW and above; while the semi-dry method and dry method, especially the dry desulfurization process, due to their low equipment cost, simple process, and low operating costs , small water consumption, low power consumption, ...

AI Technical Summary

Problems solved by technology

[0005] (1) The effective utilization rate of the desulfurizer is low, resulting in a large amount of desulfurizer

[0006] For the desulfurization process disclosed in ① and ② above, the apparent utilization rate of the desulfurization absorbent is only 26-30%. After the relative desulfurization efficiency produced by the fly ash itself is about 15% under certain conditions, the actual utilization rate of the desulfurizer is only 20-25%.

[0007] (2) The activation effect of the humidification and activation link is poor, and the relative desulfurization efficiency is low, generally only 30-50%

[0008] (3) In addition to the above dry desulfurization process, the calcium spraying catalytic desulfurization process in the furnace is due to the addition of a catalytic oxidant to the desulfurizer, so that the desulfurization product in the furnace is CaSO 4 Except for the main, the oxidation rate of desulfurization products in other processes is low, and the unstable CaSO 3 content is much greater than that of CaSO 4 , thus affecting the utilization of desulfurization products

[0009] (4) It is easy to cause the dust emission of the follow-up electrostatic precipitator to exceed the standard, and the application in some occasions is more and more restricted.

[0013] (1) Since the desulfurization agent or fly ash actually plays the role of desulfurization and catalytic oxidation in the form of oxides, and the spray humidification activation solution used in the existing spray dry desulfurization technology is generally PH ≥ 6 neutral or alkaline, and in this environment, the basic metal ion Ca contained in the desulfurization agent and fly ash is conducive to desulfurization 2+ , Mg 2+ 、Na + 、K + The dissolution rate of etc. is low, and the dissolution rate is slow; while for SO 2 Transition metal ion Fe with catalytic oxidation 3+ , Fe 2+ , Mn 2+ 、Ti 2+ , Zn 2+ etc. are more difficult to dissolve, and the higher the pH value of the humidifying and activating solution, the worse the dissolution characteristics. When the pH is greater than or equal to 5.5, it is almost difficult to dissolve, especially for the better catalytic effect and cheap, rich Fe 3+ , Fe 2+ , Mn 2+ , even with trace amounts of Fe 3+ , Fe 2+ , Mn 2+ The dissolution of the solution will also be due to the high pH of the solution, which will interact with the OH in the solution - The reaction produces an insoluble hydroxide precipitate

These reasons have resulted in a low real effective utilization rate of the active ingredients that are beneficial to desulfurization, and a large number of active ingredients are too late to dissolve or cannot be dissolved to participate in the desulfurization chemical reaction, thus resulting in the activation of desulfurization agents and fly ash in the humidification activation link The effect is very poor, and it is difficult to exert the desulfurization effect of the activation link

[0014] (2) CO in flue gas 2 recarbonation to CaCO 3 There is a very close relationship between the sediment and the pH value of the solution. The higher the pH, the more prominent the recarbonation phenomenon. In the humidification and activation environment with a higher pH value, the Ca in the desulfurizer 2+ CO dissolved in the humidification solution 2 Formed CO 3 2- Very easy to form insoluble CaCO 3 , resulting in Ca in Ca-based desulfurizer 2+ big waste

CO in the flue gas of coal combustion 2 The content of SO is generally about 13%, while SO 2 The content of CO is generally only 0.04 to 0.4%, CO 2 The concentration is about SO 2 The concentration is 32 to 325 times that of the existing technology, while the neutral or alkaline humidification and activation solution of the prior art can easily absorb a large amount of CO from the flue gas 2 Generate CO 3 2- , and then with the Ca dissolved in the desulfurizer 2+ The reaction produces CaCO 3 , under these conditions the CO in the flue gas 2 Plenty with SO 2 Competing for Ca in the desulfurizer to generate CaCO 3 Precipitation, resulting in a great waste of desulfurization active ingredients

For example, the more typical calcium spraying tail humidification and activation desulfurization process in the furnace, after analyzing the desulfurization products, it is found that the tail humidification activation link desulfurizer and SO 2 The Ca consumed by the reaction of newly generated desulfurization products only accounts for 2-3% of the total Ca, while the Ca consumed with CO 2 The reaction newly forms CaCO 3 The consumed Ca accounts for more than 30% of the total Ca, which shows that the effective desulfurization component Ca in the desulfurizer 2+ The waste is extremely serious, which is also one of the main reasons for the low utilization rate of desulfurization agent and low desulfurization efficiency in the humidification and activation link of this kind of process

[0015] (3) Under neutral or alkaline humidification and activation conditions, SO 3 2- The oxidation rate is very low, and because the transition state metal ions that play a catalytic oxidation role are not easy to dissolve, resulting in CaSO in the dry desulfurization product 3 mainly

while CaSO 3 The chemical properties are unstable. One is that it is easy to decompose and cause secondary pollution. The other is that if CaSO 3 If the content is too much, it will be gradually oxidized to CaSO in the atmospheric environment or under the condition of sufficient oxygen 4 And the volume expansion that is not conducive to use occurs, which in turn affects the use of desulfurization products or fly ash

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