Circulation desulfurization technology by ammonia-soda process

Abstract

The invention relates to a circulation desulfurization process by ammonia-soda method, comprising: absorbing sulfur dioxide in industrial exhaust gas by ammonia water to give ammonia sulfate by oxidation, and carrying out the reaction between obtained ammonia sulfate and calcium hydroxide to give dehydrate calcium sulfate and ammonia water which can be reused. By using the above process, a plurality of harmful gas can be removed simultaneously without poisoning of desulfurizer, and the end product is dehydrate calcium sulfate which is provided with low cost and high denitrogenation efficiency.

Description

(1) Technical field [0001] The invention relates to an ammonia-alkali circulation desulfurization process. (2) Background technology [0002] my country's clean resources are scarce, and coal is the main energy resource, accounting for 75% of the total primary energy consumption. The sulfur dioxide emitted by coal burning has exceeded 20 million tons for many years, ranking first in the world. my country has become the third largest acid rain area in the world and one of the countries with the most serious air pollution. There are hundreds of desulfurization processes such as wet method, dry method and semi-dry method, among which the sodium-alkali method in the double-alkali method is more popular in the wet method. Ammonia-soda method is the latest desulfurization method developed. [0003] (1) The working principle of the sodium-alkali method: [0004] Soluble sodium compounds (NaOH, Na 2 CO 3 、Na 2 SO 3 etc.) Alkaline solution absorbs SO 2 , to generate sodium sa...

AI Technical Summary

Problems solved by technology

If the above measures fail slightly, fouling will occur

[0018] 2) Sodium sulfate is not easy to remove: the side reaction in the absorption reaction is an oxidation reaction to generate stable sodium sulfate

To remove sodium sulfate from the desulfurizer, it is necessary to invest in a complex set of equipment and increase operating costs

[0019] 3) High equipment cost: It can be seen from the process flow that the chemical reaction is a gas-liquid reaction, that is, SO 2 The gas has to pass through the water film layer of the absorbing liquid before undergoing a chemical reaction

Due to the long chemical reaction time, not only the absorption equipment is bulky or the two-stage reaction tower is used, which increases the equipment cost, but also the corrosion protection of the equipment has become a difficult problem

[0020] 4) High operating cost: Only calcium sulfite hemihydrate can be produced in this replacement process, and its application range is limited. Only after the calcium sulfite hemihydrate is oxidized to calcium sulfate dihydrate (gypsum) can it be widely used

The operating cost of the process is much higher

[0022] 5) Secondary pollution and high cost of pollution treatment: Due to the narrow utilization range of calcium sulfite hemihydrate, reuse has become a problem

[0032] The disadvantage of this method is: due to the thermal decomposition of ammonium bicarbonate, the ammonia loss is serious, and the overflowing ammonia gas is easy to cause corrosion to the black iron flue at the rear of the dust collector

[0040] Disadvantages: The ammonium sulfate obtained by the simple ammonia method is used as nitrogen fertilizer, but the nitrogen content of ammonium sulfate is low, and the sulfate ion is easy to make the soil harden, etc., so its actual utilization efficiency is low

Moreover, ammonia water needs to be continuously added during the absorption process, and the cost of ammonia water is relatively high, so the overall operating cost is still relatively high

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