Flue-gas purification and reclamation system and method thereof

Abstract

A flue-gas purification system includes a flue-gas cycling system, a reactor, and an absorbent adding system having at least a catalytic absorbent, wherein the catalytic absorbent is being gasified for reacting with the flue-gas in the reactor in a homogenous gas-gas phase reacting manner. Therefore, the purification system has fast reaction rate between the pollutants of the flue-gas and the catalytic absorbent, which is preferably ammonia, to efficiently remove pollutants, so as to effectively purify the flue-gas.

Claims

1. A flue-gas purification system, comprising: a reacting means for receiving at least one exhaust flue-gas; and at least a catalytic absorbent added into said reacting means for reacting a plurality of pollutants of said flue-gas at a reacting temperature of 140 C. or below to form a series of reactions, wherein final products in solid state is formed from said pollutants of said flue-gas under UV environment, wherein said pollutants of said flue-gas comprises mercury, which is being removed via a process in said reacting means having chemical equations of said series reactions in said reacting means below:
Hg+NO.sub.2.fwdarw.HgO+NO
HgO+NH3.fwdarw.Hg(NH.sub.3)nO wherein n=3,4
Hg(NH3).sub.3O+4SO.sub.2+3H.sub.2O.fwdarw.HgSO.sub.3+3NH.sub.3HSO.sub.3
HgSO.sub.3+O.fwdarw.HgSO.sub.4
NH.sub.3HSO.sub.3+O.fwdarw.NH.sub.3HSO.sub.4.

2. A flue-gas purification system, comprising: a reacting means for receiving at least one exhaust flue-gas; and at least a catalytic absorbent added into said reacting means for reacting a plurality of pollutants of said flue-gas at a reacting temperature of 140 C. or below to form a series of reactions, wherein final products in solid state is formed from said pollutants of said flue-gas under UV environment, wherein said catalytic absorbent is delivered into said reacting means in a multiple stages manner, wherein each of said stages in said reacting means has a specific reactive conditions thereof for mainly reacting a targeted pollutant in said flue-gas while further reacting with other said non-mainly-targeted pollutants.

3. A method of purifying flue-gas, comprising the steps of: (a) conveying a flue-gas into a reacting means; (b) conveying a catalytic absorbent into said reacting means for reacting with two or more pollutants of said flue-gas to form a series of reactions, and providing a UV light to enhance a reaction rate of final products in solid state being formed from said pollutants of said flue-gas; and (c) discharging said purified flue-gas into air, wherein a reacting temperature of said catalytic absorbent reacting with said pollutants of said flue-gas is 140 C. or below, wherein said pollutants of said flue-gas comprises mercury, which is being removed via a process in said reacting means having chemical equations of said series reactions in said reacting means below:
Hg+NO.sub.2.fwdarw.HgO+NO
HgO+NH3.fwdarw.Hg(NH.sub.3)nO wherein n=3,4
Hg(NH3).sub.3O+4SO.sub.2+3H.sub.2O.fwdarw.HgSO.sub.3+3NH.sub.3HSO.sub.3
HgSO.sub.3+O.fwdarw.HgSO.sub.4
NH.sub.3HSO.sub.3+O.fwdarw.NH.sub.3HSO.sub.4.

4. A method of purifying flue-gas, comprising the steps of: (a) conveying a flue-gas into a reacting means; (b) conveying a catalytic absorbent into said reacting means for reacting with two or more pollutants of said flue-gas to form a series of reactions, and providing a UV light to enhance a reaction rate of final products in solid state being formed from said pollutants of said flue-gas; and (c) discharging said purified flue-gas into air, wherein a reacting temperature of said catalytic absorbent reacting with said pollutants of said flue-gas is 140 C. or below, wherein said catalytic absorbent is being delivered into said reacting means in a multiple stages manner, wherein each of said stages in said reacting means has a specific reactive conditions thereof for mainly reacting a targeted pollutant in said flue-gas while further reacting with other said non-mainly-targeted pollutants.

5. A method of purifying flue-gas, comprising the steps of: (a) conveying a flue-gas into a reacting means; (b) conveying a catalytic absorbent into said reacting means for reacting with two or more pollutants of said flue-gas to form a series of reactions, and providing a UV light to enhance a reaction rate of final products in solid state being formed from said pollutants of said flue-gas; and (c) discharging said purified flue-gas into air, wherein a reacting temperature of said catalytic absorbent reacting with said pollutants of said flue-gas is 140 C. or below, wherein said pollutants of said flue-gas comprises carbon dioxide CO.sub.2, which is being removed via a process in said reacting means having chemical equations of said series reactions in said reacting means below:
CO.sub.2+NH.sub.3H.sub.2O.fwdarw.NH.sub.4HCO.sub.3
NH.sub.4HCO.sub.3+NH.sub.3.fwdarw.(NH.sub.4).sub.2CO.sub.3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a block diagram of a flue-gas purification system according to a preferred embodiment of the present invention.

(2) FIG. 2 is a table of the comparisons of removal rate and efficiency of pollutants between the traditional technologies and the present purification system.

(3) FIG. 3 is a flow chart of a flue-gas purification method according to the preferred embodiment of the present invention.

(4) FIG. 4 is a block diagram of a flue-gas purification system according to the preferred embodiment of the present invention, showing the channel configuration of the flue-gas purification system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(5) Referring to FIG. 1 of the drawing, a flue-gas purification system according to a preferred embodiment of the present invention is illustrated, wherein the flue-gas purification system comprises at least a reactor 10, a flue-gas cycling system 20, and an absorbent adding system 30. In particular, the flue-gas purification system is incorporated with a fossil fuel power plant to efficiently remove the contaminations in the flue-gas generated from the fossil fuel power plant.

(6) The flue-gas cycling system 20 has at least a channel having a delivering opening for conveying exhaust flue-gas from the flue-gas cycling system 20 into the reactor 10.

(7) The absorbent adding system 30 operatively communicating with the reactor 10, wherein the absorbent adding system 30 contains at least a catalytic absorbent and arranged for delivering the catalytic absorbent from the absorbent adding system 30 into the reactor 10. Before the catalytic absorbent being delivered into the reactor 10, the catalytic absorbent is preferably being gasified to the gas phase, so that the absorbent is able to react with the flue-gas in a homogenous gas-gas phase manner, so as to dramatically increase the reaction rate thereof.

(8) The catalytic absorbent is preferably ammonia, wherein the ammonia being gasified to the gas phase is able to react with the contaminations within the flue-gas in a reaction rate, which is able to apply to the chemical process for industrial applications.

(9) The gas phase ammonia is able to quickly react with the pollutants of the flue-gas to form variety of non-toxic compounds. For examples, the gasified ammonia is able to react with the sulfur dioxide SO.sub.2 to form ammonium sulfate ((NH.sub.4).sub.2SO.sub.4); the gasified ammonia is able to react with the nitrogen oxides NO.sub.x to form ammonium nitrate (NH.sub.4NO.sub.3); and the gasified ammonia is able to react with the carbon dioxide CO.sub.2 to form ammonium carbonate ((NH.sub.4).sub.2CO.sub.3). Other compounds may be also formed by the series reactions of the catalytic absorbent and flue-gas, such as the fly ash. More details of each of the reactions within the reactor 10 will be described later.

(10) As will be readily appreciated that using the ammonia as the catalytic absorbent not only can remove the harmful pollutants, such as SOx, NOx, CO.sub.2, HF, HCl, HNO.sub.3, H.sub.2S, H.sub.2SO.sub.4, Hg.sup.0, and Hg.sup.2+, but also can form the non-toxic final products from the reactants of ammonia and the pollutants in the flue-gas. The final products, such as the above mentioned ammonium salts, can be used as fertilizers, so that the flue-gas purification system is able to purify and recycle the pollutants of the flue-gas, so as to achieve the reclamation purpose. Therefore, the final products can be recycled to form the useful chemical raw material for recycling use.

(11) It should be noted that the reactions of the gas phase flue-gas and the gas phase of the catalytic absorbent are fast chemical reactions that are able to efficiently consume the pollutants within the flue-gas via the absorption processes of catalytic oxidation reactions, photolysis, complex chin reactions, and/or the dust removal process. There are no extra other natural sources are needed or involved in the purification system of the present invention. There is no wastewater or other secondary pollutions of the side products of the reactions are generated. Thereby, the purification system is able to high efficiently remove the pollutants within the flue-gas.

(12) In the preferred embodiment of the present invention, the reactor 10 is preferably a Venturi homogenous gas-gas phase reactor 10, which has the Venturi type design for the gas phase ammonia being able to fully mix and contact with the gas phase flue-gas to maximize the efficiency of the reactions therebetween.

(13) Accordingly, a heat exchanger unit 40 is further provided for efficiently supplying the predetermined heat energy to gasify liquid phase ammonia into gas phase thereof before the ammonia entering the reactor 10.

(14) The heat exchanger unit 40 is preferably arranged that the flue-gas is entering the heat exchanger unit 40 for being conveyed into the reactor 10, wherein the flue-gas, which is normally has a temperature around 120 to 160 C. at the delivering opening of the channel of the flue-gas cycling system 10, is arranged to flow within the heat exchanger unit 40 as a heat transfer medium, in such a manner that the heat exchanger unit 40 is able to efficiently employ the heat energy from the flue-gas itself to gasify the ammonia substantially without significant extra energy or power for gasifying the ammonia, so as to cool down the flue-gas to a desired temperature.

(15) In other words, the heat exchanger unit 40 basically has at least two sets of pipes and defines a plurality of channels, wherein the first set of pipes allow the flue-gas to enter an input end of the first set of pipes and exit an output end of the first set of pipes to enter into the reactor 10, while the second set of pipes convey the liquid phase of the ammonia entering an input end of the second set of pipes and exit an output end of the second set of pipes with the gas phase ammonia. Thereby, the flue-gas with higher temperature within the first set of the pipes is arranged as a heat exchange medium for heating the liquid phase of the ammonia within the second set of pips to heat exchange therewith, so as to gasify the ammonia from liquid phase to the gas phase. Therefore, the flue-gas is able to quickly react with the gas phase ammonia of the catalytic absorbent for being purified.

(16) Referring to FIG. 4 of the drawings, in particularly, the first set of pipes defines a first channel 1, wherein an input end of the first channel 1 is connected to the flue gas cycling system 20 in order to communicate with the heat exchanger unit 40, such that the flue gas is guided to enter into the heat exchanger unit 40. An output end of the first channel 1 is connected to an input end of a fifth channel 5, wherein an output end of the fifth channel 5 is connected to the reactor 10. Therefore, when the temperature of the flue gas is reduced via the heat exchanger unit 40, the flue gas will be guided to enter into the reactor 10.

(17) Moreover, the input end of the second channel pipes 2 is connected to the absorbent adding system 30 in order to communicate with the heat exchanger unit 40, such that the liquid phase ammonia is guided to enter into the heat exchanger unit 40 from the absorbent adding system 30 via the second channel pipe. In particular, after the liquid phase ammonia is gasified to form the gas phase ammonia, the gas phase ammonia is guided to enter into the heat exchanger unit 40. A fifth channel 5 is connected between the heat exchanger unit 40 and the reactor 10. Accordingly, an input end of the fifth channel 5 is connected to the heat exchanger unit 40 and an output end of the fifth channel 5 is connected to the reactor 10. Therefore, the gas phase ammonia is further guided to enter into the reactor 10 through the fifth channel 5. It is worth mentioning that the first and second channels 1, 2 are thermally conducted with each other. When the flue gas, having a relatively high temperature, is guided to pass through the first channel 1, the first channel 1 will heat-exchange with the second channel 2. The liquid phase ammonia, having a relatively low temperature is gasified at the second channel 2 due to the heat change of the flue gas. As a result, the flue-gas is able to quickly react with the gas phase ammonia of the catalytic absorbent for being purified.

(18) Furthermore, a fourth channel 4 is connected between the absorbent adding system 30 and the reactor 10. An input end of the fourth channel 4 is connected to the output end of the second channel 2. Accordingly, a portion of the gas phase ammonia can directly enter into the reactor 10 through the fifth set of pipes 5, and a portion of the gas phase ammonia can enter into reactor 10 the fourth channel 4.

(19) It is worth to mention that through the heat exchanger unit 40, the ammonia is able to absorb the heat from the higher temperature of the flue-gas, so as to efficiently utilize the internal energy of the purification system to gasify the liquid phase ammonia. The heat exchanger unit 40 is also able to convey the gasified ammonia and the cooled flue-gas into the reactor 10 for reacting with each other in the gas-gas phase reacting manner.

(20) As will be readily appreciated that the catalytic absorbent, which is embodied as gasified ammonia, is preferably being delivered into the reactor 10 in a three stages manner. In other words, each of the stages has a specific reactive conditions, such as a predetermined temperature, concentration, and/or pressure, for mainly purifying a targeted contamination of the flue-gas, so that the variety reactive conditions of each of the reacting stages are able to further enhance the reaction rate, so as to purify multiple contaminations substantially at the same time via the single purification system of the present invention.

(21) Referring to FIG. 4 of the drawings, a plurality of sixth channels 6, such as three sixth channels, are connected to the fourth channel 4 for creating a multiple delivering stages of the gasified catalytic absorbent to the reactor 10. As shown in FIG. 4, three sixth channels are provided to create three delivering stages of the gasified catalytic absorbent to the reactor 10. For instance, the sulfur dioxide is being delivered into the first stage for essentially fully reacting with the ammonia, wherein the sulfur dioxide may further being conveyed into the second stages in the reactor 10 for further reacting with the ammonia while the second stage is designed with the predetermined reactive conditions for mainly reacting with nitrogen dioxide, in such a manner that the purification system of the present invention is able to efficiently and simultaneously purify two or more contaminations. Therefore, the gas-gas phase reactions between contaminations of the flue-gas and the ammonia in the reactor 10 is preferably arranged to form the two levels and three stages fully contacting arrangement to have more efficient purification system.

(22) Accordingly, a dust remover unit 50 is preferably provided for collecting and removing the dust from the flue-gas or the products generated from the reactions within the reactor 10. The dust, which may include the fly ash within the flue-gas and the ammonium salts, which is formed via the reactions of the gas-gas phase reactants of the flue-gas and the catalytic absorbent. Therefore, the pollutants of the flue-gas are reacted with the gas phase ammonia in the reactor 10 for removing the pollutants and purifying the flue-gas. After the reactions are substantially finished, the dust remover unit 50 is able to remove the fly ash and the ammonium salts of the dust from the flue-gas before the flue-gas being discharged into the air ambient.

(23) The dust remover unit 50 may further comprise a dust removing device 51 for removing the dust and a solid product collector 52 mainly for the compounds of ammonium salts generated from the reactions between the pollutants and the catalytic absorbent. Therefore, the flue-gas being purified by the reactor 10 and filtered by the dust removing device 51 of the dust remover unit 50 is able to discharge into the atmosphere with relatively cleaner gas. The ammonium salts are able to be further separated and collected via the solid product collector 52 for reclamation, such as reuse the collected ammonium salts for using as the fertilizer. Accordingly, the incomplete reaction substance at the dust removing device 51 will be sent back the fifth channel 5 in order to send the incomplete reaction substance back to the reactor 10.

(24) After separating the dust and the purified flue-gas, the purified flue-gas is further conveyed to pass through a fog separator 53 for separating the gas ammonia and the purified flue-gas. The gas ammonia is then being redirected to enter into the flue-gas cycling system for recycling the ammonia, and the purified flue-gas is being delivered into the heat exchanger unit 40 for being further cooled down to a predetermined temperature before being discharged into the air ambient. The purified flue-gas is further being cooled via the heat exchanger unit 40 and then being exhausted into the atmosphere therefrom.

(25) In particular, the gas ammonia from the fog separator 53 is redirected to enter into the fourth channel 4 of flue-gas cycling system for recycling the ammonia. Moreover, the heat exchanger unit 40 further comprises a third channel 3 communicatively coupled to the fog separator 53 for discharging the purified flue-gas into the air ambient, wherein the purified flue-gas is further cooled down to a predetermined temperature before it is discharged into the air ambient via the third channel 3. In other words, the incomplete reaction gas ammonia will be guided to flow back to the fourth channel 4 from the fog separator 53 and enter back to the reactor 10. The purified flue-gas is discharged from the fog separator 53 and is exhausted into the atmosphere through the third channel 3.

(26) Accordingly, the dust within the reactor 10, which is from the ash and the solid ammonium salt compounds of the products of the reactions, is preferably entering a Venturi tube of the Venturi type reactor 10 for being gradually concentrated, and then through the collisions and aggregation processes, the sizes of the particles of the dust are increased to the predetermined sizes, so that the dust removing device 51 is able to remove and separate the dust from the flue-gas. The dust removing device 51 may be an electrostatic precipitator or a bag type dust remover for collecting and/or removing the dust from the flue-gas.

(27) Referring to FIG. 4 of the drawings, a flue-gas purification system according to a preferred embodiment of the present invention further comprises a resource system which is connected to the solid products collector 52, wherein the solid phase compounds are able to deliver to the resource system for purifying and reclaiming the solid phase compounds collected by the solid products collector 52 to form useful materials, such as purify the collected ammonium salts for using as the chemical materials and fertilizers.

(28) In addition, the pollutants of the flue gas are converted into the solid compounds of the final products, wherein UV (ultraviolet) light is provided to enhance the reaction rate of the process to form the solid compounds of the final products from the pollutants of the flue gas. In other words, the pollutants of the flue gas are reacted with the catalytic absorbent under the UV light environment to speed up the reaction rate.

(29) The purification system may further comprises a monitoring system 60, wherein the monitoring system 60 is able to monitor variety of temperatures, concentrations, pressures, and other parameters at variety of check points of the purification system, so as to control the purification system. Therefore, the flue-gas of the flue-gas cycling system normally has a temperature around 120 to 160 C. before entering into the heat exchanger unit 40, a temperature around 50 to 100 C. after exiting the heat exchanger unit and before entering the reactor 10, and a temperature around 25 to 100 C. after final exiting the heat exchanger 10 after reacted with the catalytic absorbent in the reactor 10. In other words, the purified flue-gas is about 25 to 100 C. when exiting the purification system and being discharged into the air.

(30) The monitoring system 60 may be further electrically linked to the catalytic absorbent adding system 30, wherein the absorbent adding system 30 is able to automatically add a predetermined amount of the catalytic absorbent into the heat exchanger 40 in responsive to the concentrations of each of pollutants or contaminations of the flue gas before entering and/or after entering the reactor 10, the temperatures, pressures, and other parameters measured via the monitoring system 60, so as to form a automatic self-absorbent-flow-rate control system. Therefore, the monitoring system 60 is able to collect the parameters at any measuring points of the purification system, such as temperature and pressure of flue-gas before entering the reactor 10; or concentration of gas ammonia in the first stage within the reactor 10.

(31) Accordingly, the gasified ammonia of the catalytic absorbent is able to react with the steam or water vapor (H.sub.2O.sub.(g)) within the flue-gas to form the ammonium water complex (NH.sub.3.H.sub.2O), so that the SOx, NOx, and COx, such as SO.sub.2, NO.sub.2, and CO.sub.2, are able to quickly react with the ammonium water complex to occur gas-phase homogeneous nucleation reactions, so as to achieve the removal of the SO.sub.2, NO.sub.2, and CO.sub.2 of pollutants of the flue-gas. The volume ratio of the water vapor and ammonium gas (gasified ammonia) is about 1:100. The volume ratio of the gasified ammonia and the oxygen contained matter is 0 to 100.

(32) In addition, the volume ratio of the water vapor and ammonium gas (gasified ammonia) is selectively to change the molar ratio thereof. In other words, the molar ration of water vapor and ammonium gas (gasified ammonia) is about 1 to 100, and the molar ratio of the gasified ammonia and the oxygen container matter is 0 to 100.

(33) It is worth mentioning that a reacting temperature of the catalytic absorbent reacting with the pollutants of the flue-gas is preferred at 30 C. to 140 C., wherein the catalytic absorbent can be a mixture of gasified ammonia and an oxygen contained matter which can be selected from a group consisting of oxygen, air, oxidized air, gasified hydrogen peroxide, and ozone.

(34) It will be readily appreciated that normally the flue-gas contains 50% of N.sub.2, 8% of O.sub.2, 30% of CO.sub.2, 9% of H.sub.2O, and other gases of pollutants in the flue-gas, such as sulfur dioxides, nitrogen oxides, and fly ash. Theoretically, the H.sub.2O.sub.(g) is able to react with the SO.sub.2, NO.sub.2, and CO.sub.2, the reactions between SO.sub.2, NO.sub.2, and CO.sub.2 and the steam water is extremely slow that it is impossible to directly utilize to the industrial applications. Under the added catalytic absorbent, embodied as gas phase ammonia, the water molecular H.sub.2O and ammonia molecular NH.sub.3 are able to form the ammonium water complex (NH.sub.3.H.sub.2O) through the hydrogen-bond therebetween, so as to quickly further react with the contaminations of flue-gas to remove the SOx, NOx, and CO.sub.2.

(35) According to the above mentioned flue-gas purification system, the ammonium water complex (NH.sub.3.H.sub.2O), defined as a catalytic absorbent, is utilized to react with the flue-gas, wherein the acid gasified pollutants of the flue gas, such as SO.sub.x, NO.sub.x, CO.sub.2, HF, HCL, HNO.sub.3, H.sub.2S, and H.sub.2SO.sub.4, are transformed to the solid phase compounds via the ammonium water complex (NH.sub.3.H.sub.2O). Then, the solid phase compounds and the dust from the flue-gas are able to remove and separate by the dust removing device 51, so as to purify the flue-gas. Moreover, the solid phase compounds are purified for using as the chemical materials and fertilizers such that the flue-gas purification system according to the preferred embodiment of the present invention has the efficiency of purifying the pollutants of the flue-gas and the reclamation of the solid phase compounds. Thus, the solid phase compounds, such as ammonium carbonate (NH4)2CO3, ammonium hydrogen carbonate (NH4)2HCO3, ammonium nitrate (NH4NO3), ammonium sulphate (NH.sub.4).sub.2SO.sub.4, and ammonium hydrogen sulfate (NH.sub.3HSO.sub.4), are purified to form the high value chemical materials and chemical fertilizers, wherein the solid phase compounds of NH.sub.4HCO.sub.3 and the ammonium carbonate (NH.sub.4).sub.2CO.sub.3 are generated via the decarbonization process of the flue-gas purification system so as to remove the carbon oxides of the flue gas.

(36) Accordingly, the reactions of each of the pollutants and the catalytic absorbent are described as followings. The nitrogen oxides of the pollutant of the flue-gas are being removed via a series of denitrification processes. The NO in the flue-gas is first being oxidized to form the NO.sub.2. The NO.sub.2 is reacting with the water molecular within the NH.sub.3.H.sub.2O via the reduction-oxidation reaction to form the nucleation reaction to form the solid phase ammonium nitrate and gas phase nitrite, wherein partial of the nitrite further reacts with the ammonia to form the nitrate. The reaction of the nitrogen oxides and the water molecular of the ammonium water complex via the ammonia catalyst is shown below:
2NO+O.sub.2.fwdarw.2NO.sub.2
2NO.sub.2+NH.sub.3H.sub.2O.fwdarw.NH.sub.4NO.sub.3+HNO.sub.2
HNO.sub.2+NH.sub.3.fwdarw.NH.sub.4NO.sub.2

(37) The sulfur oxides removal is through a series of multi-chemical processes, which involves acid-base reactions, oxidation reactions, radical reactions, and chain reactions.

(38) The acid-base reactions of the sulfur dioxides is through nucleation reaction of the sulfur dioxides reacting with NH.sub.3.H.sub.2O, which is endothermic reaction, to form the solid NH.sub.4HSO.sub.3 and ammonium sulfite (NH.sub.4).sub.2SO.sub.3. The reaction equations are shown in the following:
NH.sub.3H.sub.2Og.sub.(Gas)+SO.sub.2g.sub.(Gas).fwdarw.NH.sub.4HSO.sub.3s
2NH.sub.3H.sub.2Og.sub.(Gas)+SO.sub.2g.sub.(Gas).fwdarw.(NH.sub.4).sub.2SO.sub.3

(39) The oxidation reaction: the NH.sub.4HSO.sub.3 and the (NH.sub.4).sub.2SO.sub.3 are oxidized via the oxygen, carbon dioxides, and ammonium nitrate to form the NH.sub.4HSO.sub.3 and ammonium sulfite (NH.sub.4).sub.2SO.sub.3. The reaction equations are shown in the following:
NH.sub.4HSO.sub.3s+O.sub.2g.fwdarw.NH.sub.4HSO.sub.4s
NH.sub.4HSO.sub.4s+NH.sub.3.fwdarw.(NH.sub.4).sub.2SO.sub.4
NH.sub.4HSO.sub.3s+NO.sub.2g.fwdarw.NH.sub.4HSO.sub.4s+NO
NH.sub.4NO.sub.3+NH.sub.4HSO.sub.3.fwdarw.(NH.sub.4).sub.2SO.sub.4+HNO.sub.2g

(40) The chain reaction equations of the sulfur oxides are also shown in the following:
HONOg+hv.fwdarw.OH+NO
OH+SO.sub.2.fwdarw.H.sub.2SO.sub.4
NH.sub.3+H.sub.2SO.sub.4.fwdarw.NH.sub.4HSO.sub.4
NH.sub.3+NH.sub.4HSO.sub.4.fwdarw.(NH.sub.4).sub.2SO.sub.4

(41) Therefore, through the processes of acid-base reactions, oxidation reactions, radical reactions, and chain reactions, the sulfur oxides of the pollutants in the flue-gas are able to be removed after the series desulfurization reactions within the reactor 10.

(42) The decarbonization process is further involved in the series reactions of contaminations removal in the reactor 10, wherein the carbon dioxide, which may be hard to react with gas or liquid phase water molecular, are able to collide with the NH.sub.3.H.sub.2O to start the homogeneous nucleation reactions to form the solid phase compounds of NH.sub.4HCO.sub.3 and the ammonium carbonate (NH.sub.4).sub.2CO.sub.3, so as to remove the carbon oxides and to form the products of ammonium salts, which is able to be recycled for being reused as fertilizer. The reaction equations are shown in the following:
CO.sub.2+NH.sub.3H.sub.2O.fwdarw.NH.sub.4HCO.sub.3
NH.sub.4HCO.sub.3+NH.sub.3.fwdarw.(NH.sub.4).sub.2CO.sub.3

(43) The process is involved in the series reactions of contaminations removal in the reactor 10, wherein the pollutants of the flue-gas comprises mercury, which is being removed through a series of multi-chemical processes comprising acid-base reactions, oxidation reactions, and chain reactions, in mercury reactor having the chemical equation below:
Hg+NO.sub.2.fwdarw.HgO+NO
HgO+NH.sub.3.fwdarw.Hg(NH.sub.3)nO n=3,4
Hg(NH.sub.3).sub.3O+4SO.sub.2+3H.sub.2O.fwdarw.HgSO.sub.3+3NH.sub.3HSO.sub.3
HgSO.sub.3+O.fwdarw.HgSO.sub.4
NH.sub.3HSO.sub.3+O.fwdarw.NH.sub.3HSO.sub.4

(44) Referring to FIG. 3 of the drawings, a method of purifying flue-gas according to the preferred embodiment of the present invention is illustrated, wherein the method comprises the following steps.

(45) (A) Convey the flue-gas from the delivering opening of the channel of the flue-gas cycling system 20 into the reactor 10.

(46) (B) Gasify the catalytic absorbent of the absorbent adding system 30 to the gas phase thereof and convey the gasified catalytic absorbent into the reactor 10. Therefore, the catalytic absorbent, preferably the gas phase ammonia, is able to react with the pollutants in the flue-gas for removing the pollutants, so as to purify the flue-gas when the flue-gas exits the reactor.

(47) (C) Discharge the purified flue-gas into the air ambient.

(48) Before the step (C), the method may further comprises a step of removing dust in the reactor via the dust remover unit 50, so that the dust, including the fly ash and the yield solid phase products from the series reactions within the reactor 10, is able to be removed to further purify the flue-gas, so as to prevent the dust clogging the system. The dust may be separated from the purified flue-gas via the dust removing device 51 as mentioned above.

(49) After the step of removing the dust, a step of collecting the solid ammonium salt compounds and other solid particles via the solid product collector 52 may further provided, so that the solid products generated in the reactor 10 is able to be further utilized as another usage, such as ammonium fertilizer.

(50) According to the preferred embodiment of the present invention, before the step (A), a step of providing the heat exchanger unit 40 may further provided. Therefore, the step (A) may further comprises a step of delivering the flue-gas into the first set of pipes 1 of the heat exchanger unit 40 as the heat exchanging medium thereof, and conveying the flue-gas to exit the heat exchanger unit 40 and enter into the reactor 10.

(51) The step (B) may further comprises a step of delivering the liquid ammonia of the catalytic absorbent into the second set of pipes 2 of the heat exchanger unit 40, so that the liquid ammonia is able to absorb the predetermine amount of heat energy from the heat exchanging medium of the flue-gas in the first set of pipes 1 for being gasified. The step (B) further comprises a step of conveying the catalytic absorbent to exit the heat exchanger unit 40 and to enter into the reactor 10.

(52) The step (B) further comprises a step of providing a UV (ultraviolet) light to enhance a reaction rate of the final products in solid state being formed the pollutants of the flue-gas under UV environment. Accordingly, the pollutants of the flue gas are converted into the solid compounds of the final products, wherein UV (ultraviolet) light is provided to enhance the reaction rate of the process to form the solid compounds of the final products from the pollutants of the flue gas. In other words, the pollutants of the flue gas are reacted with the catalytic absorbent under the UV light environment to speed up the reaction rate.

(53) It is worth to mention that the ammonia of the catalytic absorbent is preferably to be delivered into the reactor in the above mentioned three stages manner, so as to maximize the reaction rate between the absorbent and each of the pollutants of the flue-gas. Therefore, the purification system is able to obtain a relatively higher removal rate of the contaminations of the flue-gas.

(54) Accordingly, the method may further comprises a step of delivering said catalytic absorbent into said reactor in a multiple stages manner, such as above mentioned three stages manner, and preferably at least two or more stages, so that each stages is able to target specific pollutants of the flue-gas to maximize the purification rate of each of the pollutants. Therefore, the method is able to achieve purifying multiple pollutants in the flue-gas at the same time via the same reactor 10 and the purification system. There is no need for building and purchasing another equipment or system for removing variety of pollutants of flue-gas. Thereby, the equipment cost of the facility or manufacture is minimized, and meanwhile, the required area for building the purification system is minimized.

(55) Before the step of discharging the purified flue-gas and after the step of removing dust, a step of separating the gas ammonia and the purified flue-gas may further provided, wherein the ammonia is able to be redirected into the flue-gas cycling system 10 for being reused and the purified flue-gas is able to be directed to the heat exchanger 40 for being further cooled to the predetermined temperature to be discharged into the air therefrom.

(56) In the preferred embodiment of the present invention, a step of providing the monitoring system 60 may further provided, wherein the monitoring system 60 is able to detect the temperatures, pressures, concentrations of each of the pollutants of the flue-gas at variety of check points of the purification system, so as to further monitor the system for enhancing efficiency and safety thereof. The monitoring system 60 is able to electrically link with the absorbent adding system 30 for controllably, automatically, and continuously adding the predetermined amount of the catalytic absorbent into heat exchanger unit 40 as described above.

(57) Therefore, the purification system of the present invention has at least the following advantages.

(58) 1. There is substantially no significant external energy is required. The heat exchanger is able to utilize the internal heat energy of the flue-gas of the purification system to gasify the ammonia, so as to save the energy.

(59) 2. The gas-gas phase homogenous reactions between the gasified ammonia and the flue-gas has fast reaction rate and high yield rate of the products of ammonium salt compounds of the reactions, so that the purification system is able to high efficiently remove the pollutants in the flue-gas. The SO.sub.2, NO.sub.2 of the pollutants removal rate are higher than 98%, and the CO.sub.2 is higher than 30%. The removal rate, compare to the existing methods as shown in FIG. 2, is significantly improved and enhanced.

(60) 3. The main consumed chemical compound is the ammonia of the absorbent, which is cheap and has highly reusable rate, so as to minimize the cost of the purification operation.

(61) 4. The entirely equipments, such as the reactor 10, the absorbent adding system 30, the heat exchanger unit 40, and the dust remover unit 50, occupied relatively smaller spaces, and are simple in structure, so that the installation and the equipments costs are minimized.

(62) Furthermore, the signal purification system has multi-functions of desulfurization, denitrification, reduction of carbon, and removal of dust, so that the purification system not only enhance the efficiency of purifying the pollutants of the flue-gas, but also minimize the spaces required for building the purification system of present invention.

(63) 5. The purification system has high flexibility for incorporating with variety of applications or facilities, so that the purification system is able to be widely applied in variety industrial fields. For examples, the purification system is able to apply to the treatment of acid harmful gases, such as hydrogen fluoride and hydrogen chloride; and the purification system is able to be used for the treatment of waste gas from the car.

(64) 6. No water is required for purifying the flue-gas, so that the purification system is able to conserve the natural source of water. No waste water or any other types of secondary wastes are formed via the purifying process of the purification system, so that the flue-gas purification system is able to eliminate the process of secondary waste treatment.

(65) 7. No strong corrosive chemical compounds added into or generated from the reactions, so that the equipments of the purification system has relatively longer usage life. The dust remover unit is able to collect and remove the dust, such as fly ash and any other solid particles, so that the clogging issue is minimized, so as to enhance the stability during the operation of the purification system and to cost down the maintenance fee thereof.

(66) 8. The ammonium salt compounds generated from the reactions of the purifying process are able to be further reused, so that the flue-gas not only can be purified but also be reclaimed.

(67) 9. The solid phase compounds of NH.sub.4HCO.sub.3 and the ammonium carbonate (NH.sub.4).sub.2CO.sub.3 are generated via the decarbonization process of the flue-gas purification system so as to remove the carbon oxides of the flue gas.

(68) One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.

(69) It will thus be seen that the objects of the present invention have been fully and effectively accomplished. It embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.