Method for purifying flue gases

Abstract

The invention relates to methods for purifying gases and can be used in the energy industry during the combustion of fuel, and in the coking, coal and chemical industries. The present method for purifying flue gases consists in that the gas for purification is ozonized, then the ozonized gas for purification is successively treated with a catholyte and an anolyte, giving rise to catholyte and anolyte condensates, which are drained. The purified gas is enriched with oxygen by ozonization and is released into the atmosphere. The successive treatment of the ozonized gas for purification is carried out using a high-pressure cold mist of a catholyte and of an anolyte, respectively. In the case of the purification of large quantities of flue gas, the gas for purification is separated into two or more streams after ozonization, and the aforementioned successive treatment is carried out on each stream of the gas for purification. The invention makes it possible to increase the degree of purification of large quantities of flue gases.

Description

[0001] Method of cleaning flue gases

[0002] AREA OF TECHNOLOGY

[0003] The invention relates to methods of gas purification and can be used in power engineering during fuel combustion, coke-chemical, coal and chemical industries.

[0004] LEVEL OF TECHNOLOGY

[0005] A method for gas purification is known, which includes alternating washing with solutions of anolyte at pH=1-5 and catholyte at pH=9-14, obtained by electrochemical activation of water in an electrolyzer with a semipermeable membrane. The spent solutions after washing are mixed, ozonized and circulated at the activation stage (SU 1152631 A, 30.04.1985).

[0006] The disadvantage of this method is high water consumption and a very low degree of gas purification due to the fact that alternating washing with anolyte and catholyte solutions is carried out in a nozzle scrubber, which has a purification efficiency of 60-70%.

[0007] Elementary calculations show that for the above-described laboratory installation with a capacity of 1500 m 3 / hour of furnace gas requires at least 4500 liters per hour of electro-activated water obtained by electrochemical activation of water in an electrolyzer with a semi-permeable membrane. At the same time, at the moment, electrolyzers with such productivity as a result of scientific and technical research conducted by the authors, have not been found. In addition, the amount of water that must be purified becomes an order of magnitude more expensive than the gas purification itself.

[0008] The closest in technical essence to the invention is the method for cleaning flue gases selected as a prototype, which includes the effect of ultraviolet radiation on the gas being cleaned and the precipitation of solid impurities with the simultaneous effect of a catholyte or anolyte in the form of an aerosol, depending on the initial ingredients of the gas being cleaned, obtained during the electrochemical treatment of water in an electrolyzer, then ozonized and filtered with the simultaneous capture of condensate, wherein the latter is mixed with the spent solutions of the catholyte or anolyte, neutralized with ash and precipitation products, then circulated to the activation stage (RU 2058807 C1, published 27.04.1996).

[0009] The disadvantages of the prototype are the following practical inconsistencies: firstly, in the solid particle precipitation chamber, the gases to be purified are exposed to catholyte or anolyte, previously converted into steam, as a result of which the latter automatically lose their electrochemical properties due to the fact that steam is a distillate with a single electrochemical property - a liquid dielectric, with ORP = 0; secondly, the system contains blocks of beam activators mounted in the precipitation chamber and in the chimney, supposedly for the effect on gases passing through them with solid impurities of soot and ash with hard ultraviolet radiation for the photochemical excitation of oxides of harmful impurities present in the gases to be purified, which is practically impossible due to the zero transparency of the gases to be purified, precisely because of the soot and ash; thirdly, all of the above manipulations with the gas to be purified occur simultaneously in one chamber,in this case, the effect on the gas being purified is produced only by the vaporous anolyte or catholyte, as a result of which, when exposed to, for example, the vaporous anolyte, the polluting ingredients, which have a negative potential, pass by without coming into contact with the steam, which has the same potential; the same thing happens with the vaporous catholyte; fourthly, it is further stated: "... since the vapor particles are at a lower temperature level than the oxides of the impurities of the gas flow, a temperature drift of the impurities to the molecules (ions) of water is ensured with the formation of clusters and large complexes ...", that is, all manipulations to clean the flue flow are carried out at temperatures above 100 ° C, and since the solubility of gases with increasing temperature according to Le Chatelier's principle decreases, then in fact there is a process of exposure to a neutral gas (water vapor) on the flue gases, which minimally react to this effect. fifthly,after the above manipulations, the smoke flow from the sedimentation chamber enters the filter blocks of the neutralizer, where it undergoes alternating washing with catholyte (pH 12) and anolyte (pH 4), obtained during the electrochemical activation of tap water in the electrolyzer, that is, the manipulations with catholyte and anolyte are repeated again in one neutralizer, where real mutual neutralization of anolyte and catholyte occurs with the allegedly accompanying absorption of all oxidized oxides; sixthly, the prototype states: "... and the neutralized solutions enter the water storage tank through the pipeline and return again to the cycle for the electrochemical activation of water in the electrolyzer...", however, in the event of the actual implementation of the said manipulation, the electrolyzer will fail due to an interelectrode short circuit due to the fact that the supposedly neutralized solution is actually a colloidal suspension of rare earths,heavy and noble metals in quantities of more than 40 (forty) elements of the periodic table of D, I, Mendeleyev; seventhly, the basic schemes for cleaning flue gases of the above-mentioned known methods are practically inoperative when used on an industrial scale, which have the following average characteristics, namely:,

[0010] - the speed of smoke flows in flues from 10 to 20 meters per second, in order to avoid clogging of the flue section due to the settling and precipitation of smog and dust;

[0011] - the cross-sections of industrial flues range on average from 1.5 to 3.5 meters;

[0012] - the amount of flue gases to be cleaned, emitted by a medium-capacity thermal power plant operating on coal, averages from 100 to 150 m 3 / s or 360000 -^540000 m 3 / hour.

[0013] "When burning coal with ash and exhaust gases, more elements enter the environment than are extracted from the earth's interior: magnesium - 1.5 times, molybdenum - 3 times, arsenic - 7 times, uranium, titanium - 10 times, aluminum, iodine, cobalt - 15 times, mercury - 50 times, lithium, vanadium, strontium, beryllium, zirconium - hundreds of times, gallium, germanium - thousands of times, yttrium - tens of thousands of times" (ECOLOGY, G. V. Stadnitsky, A. I. Rodionov p. 117, Moscow, "Higher School").

[0014] ESSENCE OF THE INVENTION

[0015] The technical problem solved by the invention consists in eliminating the above-mentioned disadvantages of the prototype, increasing the efficiency of cleaning flue gases from multi-component pollutants, namely, in ensuring a high degree of cleaning of industrial gases from solid impurities, nitrogen oxides, carbon monoxide, sulfur dioxide, hydrogen sulfide, etc., for subsequent processing of condensate for the purpose of extracting rare earth elements.

[0016] The technical result of the invention consists in increasing the degree of purification of large quantities of flue gases by providing alternate exposure to a high-pressure cold fog of catholyte and anolyte, which is a finely dispersed fog of oppositely charged electrolytes with a high ORP (oxidation-reduction potential).

[0017] The technical result is achieved in that in the method for cleaning flue gases, which consists in the fact that the gas being cleaned is ozonized, then the ozonized cleaned gas is alternately acted upon by catholyte and anolyte with the formation of condensates of catholyte and anolyte, which are drained, and the cleaned gas is enriched with oxygen by ozonization and removed into the environment, according to the invention, for the alternate action on the ozonized cleaned gas, a cold fog of high-pressure catholyte and a cold fog of high-pressure anolyte are used.

[0018] For even more effective purification, it is advisable to alternately affect the ozonized purified gas at least twice with cold fog of catholyte and at least twice with cold fog of anolyte.

[0019] When cleaning large quantities of flue gas, it is advisable to divide the gas being cleaned after ozonation into two or more streams, and the said alternate action is carried out on the gas being cleaned in each stream.

[0020] LIST OF DRAWINGS

[0021] The invention is illustrated by drawings.

[0022] Fig. 1 shows an example of the implementation of an installation for implementing the proposed method for cleaning flue gases.

[0023] Fig. 2 shows a variant of the implementation of one of the cascades of anolyte cold fog chambers with an anolyte supply system and a condensate drainage system.

[0024] EXAMPLES OF CARRYING OUT THE INVENTION The installation shown in Fig. 1 contains a source gas duct 1, a separating manifold 2 connected to it, to which preliminary ozonation chambers 3 are connected, each of which is connected to its own ozonizer (not shown in the drawing) and is connected by means of a separating manifold 4 to parallel purification lines 5, each of which includes sequentially connected alternating chambers 6 and 7 of cold fog of catholyte and anolyte, respectively. The said chambers 6 and 7 form cascades of chambers 6 of cold fog of catholyte and cascades of chambers 7 of cold fog of anolyte. Chambers 6 and 7 are connected to high-pressure generators of cold fog of catholyte and anolyte. It is known from the prior art that a high-pressure cold fog generator includes a high-pressure pump connected to the nozzles via a high-pressure pipeline (see, for example, the Internet page “The operating principle of cold fog generators”, https: / / ecofog.ru / generatory-holodnogo-tumana / ). Fig. 2 shows one of the cascades of chambers 7 of cold fog of anolyte. In the said chambers 6 (7) of each cascade, nozzles 8 are installed for spraying catholyte and anolyte with the formation of cold fog with an average droplet size of 1-45 μm. The nozzles 8 of each cascade of chambers are connected in parallel with the corresponding supply pipeline 9 of catholyte or supply pipeline 10 of anolyte. Supply pipelines 9 of catholyte are connected by means of pipeline 11 to pump 12 of high-pressure catholyte, and supply pipelines 10 of anolyte are connected by means of pipeline 13 to pump 14 of high-pressure catholyte. The said pumps 12 and 14 are connected to supply tanks 15 and 16 of catholyte and anolyte, respectively.

[0025] The lines 5 of the chambers are connected by means of collecting collectors 17 and 18 of purified gas to the chamber 19 of final ozonization, which is connected to another ozonizer (not shown in the drawing) and to which the exhaust fan-smoke exhauster 20 is connected.

[0026] Cascades of chambers 6 and 7 are connected by means of separate drain pipelines 21 to corresponding cascade storage tanks 22 for catholyte and anolyte condensate, which in turn are connected to corresponding main pipelines 23 for separate transportation of catholyte and anolyte condensate to the processing site.

[0027] The proposed method is implemented as follows.

[0028] Flue gases after the combustion process, containing oxides of nitrogen, sulfur, carbon and solid impurities (soot, ash), are pre-cooled to 80 °C by one of the well-known methods currently used, which is determined by the conditions of the technological process, the cleaning method used, the quantity and chemical composition of the gases, the quantity and properties of dust contained in the gases.Then the flue gases, moving along the initial flue duct 1 by means of the separating collectors 2, are divided into equal flows, pass through the chambers 3 of preliminary ozonation and through the separating collectors 4 enter the cleaning lines 5, which include alternating chambers 6 and 7 of cold fog of catholyte or anolyte, created by high-pressure nozzles 8, located inside the chambers 6 and 7, fed in parallel from pipelines 9, 11 and 10, 13, connected respectively to pumps 12 and 14 of high-pressure cold fog of catholyte and anolyte, fed from the supply tank 16 of anolyte with pH = 1.5 + 4.0 and the supply tank 15 of catholyte with pH = 10.0 + 14.0, both with a high ORP of at least 350 mV (for catholyte with a + sign, for anolyte with a - sign).

[0029] The flue gases purified in this manner, moving along parallel lines 5 of chambers, are alternately exposed to the action of a cold fog of catholyte or anolyte with an average droplet size of 1-15 μm in the corresponding chambers 6 and 7, as a result of which the nitrogen, sulfur and carbon oxides contained therein with solid impurities in the form of soot and ash are almost completely condensed due to the contact of the hot gas with the cold fog and are drained into pipelines 21 for separate discharge of catholyte and anolyte and then enter cascade storage tanks 22 for condensates of catholyte and anolyte, and are then sent along main pipelines 23 for separate transportation of condensates of catholyte and anolyte to the processing site. In this case, the purified gas, having passed through the entire cascade of chambers 6 and 7 of cold fog of catholyte and anolyte, reaches the collecting collectors 17 and 18 of purified gas, through which it is brought into a single chamber 19 of final ozonation, where it is enriched with oxygen to 20.9 vol.% and then enters the smoke exhaust fan 20, which releases it into the atmosphere (environment).

[0030] In the case of small quantities of flue gas, in the most extreme case, one line of chambers may be used, containing one chamber of cold fog of catholyte and one chamber of cold fog of anolyte. In this case, the technical result will already be achieved due to the use of high-pressure cold fog, since its effect is more effective than the use of vapor or liquid catholyte and anolyte, due to the fact that finely dispersed particles of cold fog of catholyte and high-pressure anolyte provide a large surface of interaction with the gas being purified and effectively interact with it due to high ORP.

[0031] It is also possible to use one line with alternating at least two chambers of cold fog of catholyte and at least two chambers of cold fog of anolyte, while repeated alternating treatment of the purified gas with cold fogs of catholyte and anolyte will additionally increase the degree of gas purification.

[0032] Dividing the flow of purified gas into two or more flows, and multiple successive treatment of each flow with cold fogs of catholyte and anolyte, as shown in the drawings, will make it possible to carry out the purification of large flows of flue gases on an industrial scale.

[0033] The invention can be used in power engineering during fuel combustion, in the coke industry and in the extraction of rare earth chemical elements, ensuring the maximum possible purification of flue gases at minimum costs with the possibility of further processing of the condensate for the purpose of extracting rare earth elements.

Claims

Invention formula 1. A method for cleaning flue gases, which consists in the gas being cleaned being ozonized, then the ozonized cleaned gas is alternately exposed to catholyte and anolyte to form condensates of catholyte and anolyte, which are drained, and the cleaned gas is enriched with oxygen by ozonization and removed into the environment, characterized in that a high-pressure cold fog of catholyte and a high-pressure cold fog of anolyte are used for the alternate exposure of the ozonized cleaned gas.

2. The method according to paragraph 1, characterized in that the alternate action on the ozonized purified gas is carried out at least twice with cold fog of catholyte and at least twice with cold fog of anolyte.

3. The method according to paragraph 2, characterized in that the gas to be purified after ozonation is divided into two or more streams, and the said alternate action is carried out on the gas to be purified in each stream.

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