WO2010078727A1 - Method for removing toxic components and greenhouse gases from flue gas - Google Patents

Abstract

A method for removing toxic components and greenhouse gases such as sulfur dioxide, nitrogen oxide and carbon dioxide, from flue gas, is provided. Said method includes: 1) flue gas counter-current contacts treated alkaline water, 2) the treated flue gas is collected or discharged, and 3) the used alkaline water is collected. Said treated alkaline water is prepared from seawater or other sources of water by electrolysis.

Description

 Description toxic components in flue gas and method for removing greenhouse gases

 [1] The present invention relates to a method for removing toxic components and greenhouse gases, and more particularly to a method for removing toxic components and greenhouse gases from flue gas by absorption.

 Background technique

 [2] With the rapid economic growth, the tight energy supply and serious environmental pollution have become the focus of the world and the problems that need to be solved urgently. In addition, due to the persistent high oil prices, oil production has been forced to move from focusing on conventional oil development to conventional oil and unconventional oil. The unconventional-oil referred to here, as defined by the International Energy Agency, is oil that is not extracted from underground reservoirs through production wells or that requires additional processing to produce synthetic oil. Unconventional petroleum includes: (1) oil shale; (2) oil sand-based synthetic crude oil and its derivatives; (3) hydrocarbon-based liquefaction products; (4) biomass liquefaction products; and (5) natural gas produced by chemical processing Liquid product. Generally, these unconventional petroleums have high levels of carbon, sulfur, and nitrogen and lack hydrogen. Therefore, in the flue gas produced by these unconventional petroleum as an energy source, the content of carbon dioxide, sulfur dioxide, and nitrogen oxides is high. If such smoke is directly discharged, it will pollute the environment. Therefore, in order to successfully develop these unconventional oils, the key is that such flue gas must be treated to meet emission standards before it can be discharged.

[3] To this end, many efforts have been made in this regard, for example, U.S. Patent No. 6,187,277 to U.S. Patent No. 3,520,649 to Toman et al. In US 6,187,277, S0 ₂ and C0 ₂ in the flue gas are removed as follows: First, 80 ₂ and are contained. 0 ₂ flue gas and pH dimethyl sulfoxide (D

MSO) aqueous solution is contacted to dissolve so^nco ₂ in the aqueous solution, and then the aqueous solution of dimethyl sulfoxide dissolved in so^nco ₂ is reacted with calcium ions to form solid calcium sulfate or calcium sulfite or a mixture thereof and Solid calcium carbonate. It is known from this method that dimethyl sulfoxide is an important component and its pH must be kept different during the treatment. Thus, this method is difficult to use widely in the industry. In addition, in US Pat. No. 3,520,649, the invention was developed solely for the purpose of removing sulfur dioxide from flue gases, wherein a solution containing calcium is used.

[4] As can be seen from the above two US patents, since both use only calcium-based alkaline solutions, the process is Limited. In addition, it has not been disclosed to use other metal alkaline solutions to remove these toxic components and greenhouse gases.

 [5] In addition, U.S. Patent No. 5,690,899 to the disclosure of U.S. Pat. In US 5,690,899, the principle of removing the toxic component sulfur dioxide is achieved by acid-base reaction using the acidity of sulfur dioxide and the basicity of seawater. However, after the acid-base reaction, the pH of the solution remaining is as high as 4.0 to 5.0. In order to meet the emission standards of pH 6.5~9.0, a large amount of fresh seawater needs to be added to dilute. This requires a lot of energy. In addition, this method essentially removes the toxic components and greenhouse gases from the gas into the water and reduces and acidifies the pH of the seawater, thereby jeopardizing the marine ecosystem. On the other hand, after the above diluted water is discharged into the sea, these toxic components and greenhouse gases will eventually be released from the seawater to the atmosphere. Obviously, the method of Makkinej ad et al. is not advisable.

[6] Moreover, the method of the present invention can remove toxic components in the flue gases and greenhouse inch with: S0 _2, NO _x

, C0 ₂ . This concept has not been mentioned and inferred in any prior art.

 Summary of the invention

[7] In view of the deficiencies in the prior art, it is an object of the present invention to provide a method for removing toxic components and greenhouse gases from the flue gas by absorption: S0 ₂ , NO _x , C0 ₂ .

 [8] It is well known that the flue gas produced by burning a fuel is a mixture of various gases, mainly C

0 ₂ , S0 ₂ NO _x . TABLE NO _x nitrogen oxide form of various naturally occurring, such as NO, N0 ₂ and N ₂ 0 ₅ and the like. The above-mentioned C0 ₂ and SO^NO _{x are} basically acid gases. Chemically, these acid gases can be neutralized with an alkaline solution to form salts and water. Since the chemical structures of these acid gases are different from each other, their acidity is also different. Taking the above three acid gases as an example, their acidity is ranked as follows:

[9] S0 ₂ >NO _x >C0 ₂

[10] As can be seen from the above, first, in order to absorb these gases, any solution having a pH ≥ 7 can be used. Second, based on the acidity of these gases, the order of the reactions can be arranged for efficient removal. Obviously, the flue gas ₈₀₂ is absorbed should be removed first, followed by the NO _x, and finally C0 _2.

 [11] The object of the invention is achieved by the following scheme:

[12] First option: a) applying treated alkaline water to the flue gas stream in a reverse direction with the flue gas stream; [13] b) collecting or discharging the flue gas treated in step a);

[14] c) Collect the liquid treated by step a).

 [15] In addition, the flue gas collected in step b) may be treated one or more times in the same manner as step a), in accordance with different standards for flue gas emissions.

[16] Second option: a) applying treated alkaline water to the flue gas stream in a reverse direction with the flue gas stream;

[17] b) applying treated alkaline water to the flue gas stream in a reverse manner with the flue gas stream treated in step a); [18] c) collecting or discharging the flue gas treated by steps a) and b) ; as well as

[19] d) Collect the liquids treated by steps a) and b).

[20] In addition, the flue gas collected by step c) can be treated one or more times in the same steps as steps _a ) and b), depending on the different standards for flue gas emissions.

[21] Third option: a) bringing the flue gas stream into contact with the treated alkaline water;

[22] b) Collect or discharge the flue gas treated in step a).

 [23] In addition, the flue gas collected by step b) may be treated one or more times in the same manner as step a), in accordance with different standards for flue gas emissions.

[24] The "treated alkaline water" mentioned above is prepared as follows:

 [25] It should first be noted that the treated alkaline water of the present invention is provided by an alkaline water preparation device, wherein the required water includes, but is not limited to, tap water, river water, well water, sea water, industrial wastewater, etc. No chemicals are used during the preparation process.

 Specifically, the alkaline water preparer of the present invention operates on the basis of electrolysis of water, i.e., placing two electrodes in a water tank, and then applying a direct current power source to the electrodes. The electrode connected to the positive electrode of the power source is called the anode, and the cathode connected to the negative electrode is called the cathode. When energized, the positive ions (H+) will migrate toward the cathode and the negative ions (OH-) will migrate toward the anode. In general, the rate of oxygen formed on the anode is the same as the rate of hydrogen formed on the cathode, so the pH of the water does not change.

 [27] In order to make water alkaline, the rate of hydrogen evolution must be faster than the rate of oxygen evolution during electrolysis. To this end, it can be achieved by changing the surface area of the electrode, changing the current density of the electrode, and using an ion barrier in the electrode.

[28] It is known that the surface area of an electrode is inversely proportional to the charge density of the electrode. In the alkaline water preparer of the present invention, the surface area of the cathode is reduced to increase the charge density of the cathode. Increasing the charge density of the cathode will make hydrogen Gas escapes faster than oxygen. Thus, the hydrogen ions (H+) in the water are reduced, so that the pH of the treated water is increased.

 [29] In order to impart a high pH to the treated water, a conductive substance such as activated carbon is also added to the alkaline water preparation device of the present invention. Since the conductive material is electrically conductive, when the conductive material surrounds the anode, the precipitation of oxygen on the anode is hindered. As a result, the treated water can reach a higher pH. By the same token, an ion barrier can be used to retard the migration of OH- to the anode, thereby increasing the pH of the water near the cathode.

According to the invention, the pH of the treated alkaline water is between 8.0 and 14.0, which takes advantage of the electrolysis process and does not involve any chemicals. Therefore, it has no impact on the environment. A unique feature of the treated alkaline water of the present invention is that the water alkalinity increases during the electrolysis process. Alkalinity is the ability of water to mitigate changes in pH, essentially the sum of hydroxyl ions (OH -), carbonate ions (CO -), and bicarbonate ions (HC0 ₃ -).

[31] It can be seen from the above that when the method of the present invention is used to remove toxic components in the flue gas and greenhouse gases such as S0 ₂ , NO _x , C0 ₂吋, carbonic acid is formed by absorption of C0 ₂ , treated alkaline water The pH will decrease. However, the concentration of bicarbonate ion (HC0 ₃ -) will increase, so the pH of the final discharged water will not change greatly, it is still alkaline, and it is close to the alkalinity of seawater itself, so it will not affect the ecology. The environment does not need to be diluted with fresh sea water before it is discharged.

 [32] Compared with the prior art, the advantages of the present invention are:

[33] (1) The treated alkaline water can be used to remove S0 ₂ , NO _x and C0 ₂ ;

 [34] (2) The treated alkaline water can be directly prepared from the tap water, river water, well water, sea water and industrial wastewater by electrolysis. Therefore, it is not necessary to use any chemicals to prepare alkaline water, which will not affect the environment;

[35] (3) The flue gas is treated by reverse spray or direct contact, and the absorption rate is improved;

[36] (4) The pH of the treated alkaline water is controlled to be greater than or equal to 7, so that the present invention can be widely used industrially, and the pH of the discharged water does not change much;

[37] (5) The treated alkaline water can be recycled compared to other methods;

[38] (6) Compared with the method for increasing the pH before discharge, the present invention has significant water saving.

The concept, the specific structure, and the technical effects produced by the present invention will be further described in conjunction with the accompanying drawings in order to fully understand the objects, features and effects of the invention. However, these drawings are only for illustrative purposes, not It can be understood that the limitations of the invention.

 DRAWINGS

 [40] FIG. 1 is a schematic view showing the implementation of the first aspect of the present invention;

Figure 2 is a schematic view showing the implementation of the second aspect of the present invention;

Figure 3 is a schematic view showing the implementation of the third aspect of the present invention.

 detailed description

[43] Generally, flue gas is a product of fuel combustion. Commonly used combustion devices use gas or fuel, such as gas burners/gas boilers and oil burners/oil boilers. In this case, the content of S0 ₂ and NO _x C0 ₂ in the flue gas is as follows:

[44] For S0 ₂ , general flue gas content: 180~250 ppm (fuel)

[45] If the coal is burned, the content of the flue gas will be >2000 ppm.

[46] For NO _x, the general content of the flue gas: 50 ~ 70 ppm (gas), 50 ~ 110 ppm (fuel)

[47] For C0 ₂ , the content of general flue gas: 10~12% (gas), 12~14% (fuel)

[48] Example 1

 Referring to Figure 1, the apparatus 10 shown in Figure 1 is designed to implement Embodiment 1 of the present invention. The device 10 includes a casing 11, a flue gas inlet pipe 12 connected from the bottom wall of the casing 11, a flue gas output pipe 13 connected from the top of the casing, and at least one set of warp pipes disposed at the top of the casing. The alkaline water spray tube 14 is treated, and the treated alkaline water is supplied from the alkaline water preparation unit 15 through a pipe and a liquid collection tank 16 at the bottom of the casing. The liquid collected in the collection tank 16 is discharged through the discharge pipe 17, and is repeatedly used by the pump 18 through the inlet pipe 19.

[50] In the device 10, toxic components and greenhouse gases in the flue gas: S0 ₂ , NO _x , . 0 ₂ is removed by the following steps:

[51] a) collecting flue gas generated by combustion of gas, fuel or unconventional oil through a combustion device and inputting the flue gas into the device 10 through the flue gas input pipe 12. Here, the flue gas flows from the bottom to the top in the casing 11. At the same time, the treated alkaline water is sprayed downward through the spray tube 14 into a mist. Since the flue gas flow is opposite to the direction of the spray stream, the two have sufficient inter-turn and area contact to mainly absorb S0 ₂ , NO _x 3⁄4C0 ₂ in the flue gas.

[52] b) Collect the flue gas treated in step a). If the treated flue gas meets emission standards, it can be released into the atmosphere. If it has not reached the standard, it can be collected and then processed through the flue gas inlet pipe for the second time until the standard is reached. Emissions.

 [53] c) Collect the liquid treated by step a). In general, the pH of the collected liquid does not change much and can be recycled.

[54] In step a), the treated alkaline water comprises sodium ions, magnesium ions and calcium ions, but is not limited thereto, and may also include other metal ions or non-metal ions, such as NH ₄₊ . The treated alkaline water has a pi^ ≥ 8.5. Generally, the treated alkaline water is prepared from seawater, but is not limited thereto, and may be prepared by the above-described electrolytic method using, for example, ground water, river water, rain water, industrial treated water, deionized water or the like.

 [55] Example 2

 Referring to Figure 2, the apparatus 20 shown in Figure 2 is designed to implement Embodiment 2 of the present invention. The device 20 includes a casing 11a and a casing 11b in fluid communication with the casing 11a, a flue gas inlet pipe 12a connected from the bottom wall of the casing 11a, and a bottom wall from the bottom of the casing l ib The flue gas input pipe 12b is connected, a flue gas output pipe 13a connected from the top of the casing 11a, and a flue gas output pipe 13b connected from the top of the casing l ib, wherein the output pipe 13a is connected to the input pipe 12b. And at least one set of treated alkaline water spray tubes 14a disposed on top of the casing l id, said treated alkaline water being supplied by the alkaline water preparation unit 15 through the pipeline and at least one set being disposed in the casing 1 The treated alkaline water spray tube 14b at the top of the lb and the liquid collection tank 16a at the bottom of the housing 11a and the liquid collection tank 16b at the bottom of the housing 1 ib. The collection pools 16a and 16b may be connected to each other or may be independent of each other. If they are connected, the liquid collected in the collection tank 16a is discharged through the discharge pipe, passes through the collection tank 16b, is discharged through the discharge pipe 17b, and is repeatedly used by the pump 18a through the input pipe. If they are independent, they are each cycled through their respective pumps.

[57] In the device 20, toxic components and greenhouse gases in the flue gas: S0 ₂ , NO _x , . 0 ₂ is removed by the following steps:

[58] a) Collecting the flue gas generated by the combustion of the gas, fuel or unconventional oil through the combustion device and inputting the flue gas into the casing 11a of the device 20 through the flue gas input pipe 12a. Here, the flue gas flows from the bottom to the top in the casing 11a. At the same time, the treated alkaline water is sprayed downward through the spray tube 14a into a mist. Since the flue gas flow in the opposite direction of the spray stream, two inches and there is sufficient contact area, which mainly inch flue gas S 0 _2, NO _x and C0 ₂ absorption.

[59] b) collecting the flue gas treated by the step a) and inputting the shell of the device through the input pipe 12b connected to the output pipe 13a Body l ib. Here, the flue gas flows from the bottom to the top in the casing 1 ib. At the same time, the treated alkaline water is sprayed downward through the spray tube 14b into a mist. Since the flue gas flow in the opposite direction of the spray stream, two inches and there is sufficient contact area, which mainly inch flue gas S0 _2, NO _x, and then absorbed C0 _2.

 [60] c) Collect the flue gas treated by steps a) and b). If the treated flue gas meets emission standards, it can be released into the atmosphere. If it has not reached the standard, it can be collected and then processed through the flue gas inlet pipe 12a for a second time until it reaches the standard discharge.

 [61] d) Collect the liquid treated by steps a) and / or b). If the collection tanks 16a and 16b are in communication, the liquid collected in the collection tank 16a is discharged through the discharge pipe, passes through the collection tank 16b, is discharged through the discharge pipe 17b, and is repeatedly used by the pump 18a through the input pipe. If they are independent, they are each cycled through their respective pumps.

[62] In step a), the treated alkaline water comprises sodium ions, magnesium ions and calcium ions, but is not limited thereto, and may also include other metal ions or non-metal ions, such as NH ₄₊ . The treated alkaline water has a pi^ ≥ 8.5. Generally, the treated alkaline water is prepared from seawater, but is not limited thereto, and may be prepared by the above-described electrolytic method using, for example, ground water, river water, rain water, industrial treated water, deionized water or the like.

 [63] Example 3

 Referring to Figure 3, the apparatus 30 shown in Figure 3 is designed to implement Embodiment 3 of the present invention. The apparatus 30 includes a casing 311 and a liquid pool 316 formed at the bottom of the casing 311 (the liquid in the liquid pool 316 is treated alkaline water supplied through a pipe by an alkaline water conditioner (not shown). a flue gas inlet pipe 312 that is inserted from the side wall of the casing and that opens into the liquid pool 316, a flue gas outlet pipe 313 that is inserted from the top of the casing, and an aerosol layer formed in the space above the liquid pool in the casing. 314. The liquid in the liquid pool 316 is input through the inlet pipe 319 and discharged through the outlet pipe 317. The liquid pump in the pool (not shown) is used for recycling.

[65] In the device 30, the toxic components of the flue gas and the greenhouse gases: S0 ₂ , NO _x , CCgi are removed by the following steps:

[66] a) collecting flue gas generated by combustion of gas, fuel or unconventional oil through a combustion device and inputting the flue gas into the pool 316 of the device 30 via the flue gas input pipe 312. This inch, the flue gas in the form of bubbles with the pool 316 in contact with alkaline water treated, the flue gas mainly S0 _2, NO _x C0 ₂ absorption.

[67] b) The flue gas treated by step a) escapes from the pool 316 and rises. [68] c) collecting or discharging the flue gas treated by the steps a) and b) via the outlet pipe 313. If the treated flue gas meets emission standards, it can be released into the atmosphere. If it has not reached the standard, it can be collected and then processed through the input pipe 312 for a second time until the discharge is reached.

[69] In step a), the treated alkaline water comprises sodium ions, magnesium ions and calcium ions, but is not limited thereto, and may also include other metal ions or non-metal ions, such as NH ₄₊ . The treated alkaline water has a pi^ ≥ 8.5. Generally, the treated alkaline water is prepared from seawater, but is not limited thereto, and may be prepared by the above-described electrolytic method using, for example, ground water, river water, rain water, industrial treated water, deionized water or the like.

Analysis of the flue gas treated by the methods of Examples 1 to 3 shows that the method of the present invention can remove toxic components and greenhouse gases in the flue gas: _S o ₂ , NO _x , . 0 _{2 is} about 90%.

 While the present invention has been described in detail, the preferred embodiments of the present invention may be variously modified or modified without departing from the spirit and scope of the invention. It should be noted that such variations or modifications are within the scope of the invention.

Claims

Claim [1] A method for removing toxic components in a flue gas and a greenhouse gas: S0 ₂ , NO _x , C0 ₂ , wherein the method comprises the following steps:  a) applying treated alkaline water to the flue gas stream in a reverse direction with the flue gas stream; b) collecting or discharging the flue gas treated in step a);  c) Collect the liquid treated by step a).  [2] The method according to claim 1, wherein the treated alkaline water is applied in a spray manner.  [3] The method according to claim 1 or 2, wherein the treated alkaline water is supplied via a pipe by an alkali water preparation device. [4] The method according to claim 1, wherein the treated alkaline water comprises sodium ions, magnesium ions, and calcium ions, and may also include other metal ions or non-metal ions. [5] The method according to claim 1 or 4, wherein the treated alkaline water is prepared from seawater, and may also be composed of ground water, river water, rain water, industrial treated water, deionized water, etc. Prepared by electrolysis.  [6] The method according to claim 1, wherein the treated alkaline water has a pi^ ≥  8.5.  [7] The method according to claim 1, wherein the method further comprises the step of: treating the flue gas collected by the step b) one or more times in the same step as the step a). [8] A method for removing toxic components and greenhouse gases in a flue gas: S0 ₂ , NO _x , C0 ₂ , wherein the method comprises the following steps:  a) applying treated alkaline water to the flue gas stream in a manner opposite to the flue gas stream; b) applying treated alkaline water to the flue gas stream in a reverse manner with the flue gas stream treated in step a) Collecting or discharging the flue gas treated by steps a) and b);  d) Collect the liquids treated by steps a) and b). [9] The method according to claim 8, wherein the treated alkaline water is applied by spraying. [10] The method of claim 8, wherein the treated alkaline water comprises sodium ions, magnesium ions, and calcium ions, and may also include other metal ions or non-metal ions.  [11] The method according to claim 8 or 10, wherein the treated alkaline water is prepared from seawater, and may also be composed of ground water, river water, rain water, industrial treated water, deionized water, etc. Prepared by electrolysis.  [12] The method according to claim 8, wherein the treated alkaline water has a pi^ ≥  8.5.  [13] The method according to claim 8, wherein the method further comprises the step of: causing the flue gas collected by the step c) to be the same as the steps a) and b) one or more times. Step processing. [14] A method for removing toxic components in a flue gas and a greenhouse gas: S0 ₂ , NO _x , C0 ₂ , wherein the method comprises the following steps:  a) contacting the flue gas stream with the treated alkaline water;  b) Collect or discharge the flue gas treated in step a).  [15] The method according to claim 14, wherein the neutral liquid is selected from the group consisting of reverse osmosis water, distilled water, and electrodialysis water. [16] The method according to claim 14 or 15, wherein the pH of the neutral liquid is  7 or so.  [17] The method of claim 14, wherein the treated alkaline water comprises sodium ions, magnesium ions, and calcium ions, and may also include other metal ions or non-metal ions.  [18] The method according to claim 14 or 17, wherein the treated alkaline water is prepared from seawater, and may also be composed of ground water, river water, rain water, industrial treated water, deionized water, etc. Prepared by electrolysis.  [19] The method according to claim 14, wherein the pH of the treated alkaline water is ≥8·5.  [20] The method according to claim 14, wherein the method further comprises subjecting the flue gas collected by the step b) to the same step as the a) step one or more times.