TW201021899A - Bromine chloride compositions for removing mercury from emissions produced during fuel combustion - Google Patents

Abstract

Compositions, and processes utilizing such compositions, are provided for reducing mercury emissions during flel combustion. Such compositions comprise a sorbent, a bromine source, and a chlorine source. Cuch compositions exhibit improved thermal stability as compared to that of the sorbent by itself.

Description

201021899 VI. Description of the Invention: [Technical Field to Which the Invention Is Ascribed] The present invention relates to a bromine chloride composition for removing mercury from emissions generated during combustion of a fuel. [Prior Art] In 2005, EPA issued the Ciean Air Mercury Rule to limit and reduce mercury emissions from coal-fired power plants. This regulation, combined with the EPA's Clean Air Interstate Regulations (cAIR) or other regulations, may require a significant reduction in mercury emissions from coal-fired power plants in the United States in 2010. There are a large number of coal resources around the world that have the potential to meet the world's energy needs for a long time. The United States has a large number of low-sulfur coal resources, such as coal in the Powder River Basin in Wyoming and Montana, but such coal mines contain a non-negligible amount of mercury, whether in elemental or oxidized form. Therefore, in order for coal-fired power plants to use such coal resources without causing a large amount of mercury emissions, there must be some form of mercury emission regulation technology. The US Department of Energy has provided information based on many studies and pointed out that treating coal fuel with low amounts of bromine can reduce mercury emissions during combustion of coal fuels. The brine produced in many parts of the world contains large amounts of bromine salts, such as sodium bromide. The bromine can be recovered from such brine by treatment with chlorine to oxidize the bromide to bromine. A method of electrolytically converting bromide to bromine is also known; however, electrolytic conversion is an expensive alternative to the above process. It has also been reported that oxygen or a mixture of air is used to catalyze the oxidation of bromide to bromine; however, there is currently no successful economical commercial operation of 201021899. It is known that the removal of harmful gas components from the gas effluent can be achieved by uniformly dispersing the sorbent particles in the effluent to contact and capture the target gas component in flight, followed by electrostatic precipitator (ESP), fabric filtration. The (FF) or wet scrubber mechanically removes the absorbent with adsorbate from the effluent gas. A very effective absorbent is powdered activated carbon (PAC). The PAC used may or may not have been modified. Modified PACs can improve the capture of target hazardous substances by improving the adsorption efficiency. PAC modification is exemplified in US 4,427,630, US w 5,1 79,05 8, US 6,5 1 4,907, US 6,953,494, US 200 1 /00023 87, US 2006/0051270, and US 2007/0234902. The thermal stability of PACs and other absorbents can be problematic; for example, 'When PAC is used to treat warm or hot gas effluents or when packaged or collected in large quantities, PAC may be due to unmitigated oxidation reactions. Causes spontaneous combustion' and can cause smoldering or burning. Cases in which a large number of PACs may be encountered φ include: when packaging a PAC, for example in an oversized package, or when being made into a filter cake in an FF unit or being collected in a storage bin or feed hopper combined with ESP Time. Spontaneous combustion may be exacerbated by the fact that the PAC becomes slightly hot or hot. It may occur when processing coal-fired boiler effluents. If oxygen (air) is not isolated at the oxidation site or if the location is not cooled, the heat from the initial oxidation reaction can be transferred until the PAC is smoldered or ignited. Such ignition can be quite tragic. Utility plants are very sensitive to spontaneous combustion (such as smoldering or burning) in the effluent line, and its 201021899 may cause plant downtime and have a wide-ranging impact on consumers. In view of the above, there will be a commercial advantage if there are new ways to minimize mercury emissions from coal and other fuel storage. In addition, it is advantageous to have improved thermal stability of PACs and other absorbents. [Invention] The present invention satisfies the above needs. It is provided for reducing combustion during combustion of coal and other combustible fuels. Composition and method of mercury emissions from airflow. The composition of the present invention comprises a bromine source, a chlorine source, and an adsorbent capable of adsorbing bromine and chlorine. The present invention also provides such compositions and methods wherein the composition has improved thermal stability compared to the absorbents contained therein. The term "reduce mercury emissions" as used herein and in the scope of the patent application refers to any amount of mercury removed from the effluent by any mechanism (eg, adsorption or absorption) that causes the fuel to be released into the atmosphere upon combustion. The amount is less than that of the composition and/or method without the use of the present invention. The absorbent composition of the present invention can be added to the combustion gas stream produced by the combustion of combustible fuel. In addition to this, the absorbent composition of the present invention may be added (combined) to the fuel before and/or during combustion. In addition to this, the present invention is intended to add the absorbent composition of the present invention to fuel and combustion gases prior to and/or during combustion. Such an absorbent composition comprises a bromine source, a chlorine source, and an absorbent capable of adsorbing bromine and chlorine. The method of the present invention may comprise: adding a composition comprising a bromine source, a chlorine source, and an adsorbent capable of adsorbing bromine and chlorine to a combustion gas stream produced by one or more combustible fuels during a combustion period of 201021899; thereby reducing combustion from Mercury emissions from airflow. In this method, the bromine source may comprise bromine or HBr, the gas source may comprise chlorine or an HC1 'bromo source and/or the chlorine source may comprise bromine chloride. Also in this method, the absorbent may include a carbonaceous substrate, activated carbon, wood derived activated carbon or coconut shell derived activated carbon. At the same time, the combustion gas stream can be derived from the combustion of coal or another matrix. In the process of the present invention, the composition has a PIO that is at least about 10 degrees C higher than the PIO of only the absorbent. The method of the present invention may comprise: adding a composition comprising a bromine source, a chlorine source, and an adsorbent capable of adsorbing bromine and chlorine to the combustible fuel before and/or during combustion of the combustible fuel; combusting the combustible fuel; generating a combustion gas stream; This reduces mercury emissions from the combustion gas stream. In this method, the combustible fuel may comprise coal or another substrate. Similarly, the absorbent may include a carbonaceous substrate, activated carbon, wood derived activated carbon, or coconut shell derived activated carbon. In this method, the composition has a PIO that is at least about 10 degrees C higher than the PIO of only the absorbent. Φ The method of the present invention may comprise: adding a composition comprising bromine chloride and an adsorbent capable of adsorbing bromine and chlorine to the combustible fuel before and/or during combustion of the combustible fuel; burning the combustible fuel; generating a combustion gas stream; This reduces mercury emissions from the combustion gas stream. The present invention also provides a composition capable of reducing mercury emissions from a combustion gas stream comprising a bromine source, a chlorine source, and an adsorbent capable of adsorbing bromine. In this composition, the bromine source may include bromine or HBr'. The chlorine source may include gas or HCl, or the bromine source and/or the chlorine source may include bromine chloride. This composition may also include 201021899 bromine chloride. In the composition of the present invention, the absorbent may include a carbonaceous substrate, activated carbon, wood derived activated carbon or coconut shell derived activated carbon. The composition of the present invention has a PIO which is at least about 10 degrees higher than the PIO of the absorbent only. The present invention can be better understood by referring to the figure (Fig. 1), and the absorbent composition of the present invention can be solid. The form (eg, in the form of a powder or granules) or a liquid form is added or combined with the combustible fuel and/or combustion gas stream. The absorbent composition can be added to a combustion gas stream having a temperature of from about 150 degrees C to about 400 degrees ❹ c. For example, on the cold side of ESPs (electrostatic precipitators), the absorbent composition can be injected into a combustion gas stream from about 150 degrees C to about 200 degrees C. Alternatively, the absorbent composition can be injected into the combustion gas stream from about 300 degrees C to about 400 degrees C on the hot side of the ESPs (electrostatic precipitator). [Embodiment] Absorbent Suitable bromine-absorbing absorbents of the present invention include, for example, activated carbon, activated carbon, activated coke, carbon black, pulverized coal, activated coke, unburned or partially burned from a combustion process. Carbon, kaolin or other clays, zeolites, aluminas and other carbonaceous substrates. Wood derived PACs are particularly suitable for use in the present invention, including those derived from wood materials such as sawdust, wood chips or other particulate wood products. Coconut shell derived PACs are also well suited for use in the present invention. Other suitable absorbents will also be known or may be known to those skilled in the art and have the advantages as taught by the present patent application. 201021899 Bromine/Chlorine Sources Bromine sources suitable for use in the present invention include Br2 and bromine precursors such as HBr. NaBr and KBr are not suitable for use in the present invention. In one aspect, the bromine source of the present invention does not include NaBr and KBr and can be considered a non-sodium or potassium derived bromine source. Herein, when NaBr and KBr and/or a so-called non-sodium or potassium-derived bromine source are excluded, it means that no NaBr, KBr, sodium or potassium is intentionally added. Suitable chlorine sources include Cl2 and chlorine precursors such as HCl. In addition, sources suitable for use in Br2 and/or Cl2 include compounds containing both bromine and chlorine precursors, such as bromine chloride or chlorine bromide. Other suitable sources of bromine and/or chlorine will also be known or may be known to those skilled in the art and have the advantages taught by the present application. The composition used in the present invention may include a bromine chloride, a bromine source, and a chlorine source. The composition used in the present invention may include bromine chloride, bromine and chlorine. Absorbent Compositions There are several procedures for the incorporation of bromine and chlorine into an absorbent such as activated carbon. In one of such procedures, referring to Fig. 1, the desired important activated carbon 8 is placed in the column 10, which is located in the heating/cooling jacket 11. The coarse sintered glass (not shown) supports the activated carbon 8 in the column 1 . The stopcock 12 is opened and the stopcock 14 is closed so that the entire system 7 is evacuated to a pressure of 5 mm Hg. The column 10 was heated to 95 ° C via a heating mantle 11 and maintained at 95 ° C for one hour to remove moisture. The column 10 is then allowed to cool to room temperature and the stopcock 12 is closed. At this time, the activated carbon 8 is moderately dried and degassed. Place the required amount of bromine chloride 19 in a round bottom burnt 201021899 bottle 20. The boiling point of the bromine chloride is 4 degrees C, so the flask 20 is cooled to 4 degrees C or less. The cooling is stopped and the stopcock 14 is opened to introduce bromine chloride 19 onto the activated carbon 8 in the column 10. Cooling water is allowed to flow into the cooling jacket 11' to remove the heat of adsorption generated in the process. Adsorption usually reaches full within a few hours, depending on the amount of batch produced. Excess bromine chloride is removed by opening the stopcock 12 and passing a stream of air or nitrogen through the column 1 at room temperature and/or optionally heating to 150 degrees C via the heating jacket 11. The bromine chloride treated activated carbon 8 is now transferred to a suitable helium vessel (not shown) and mixed for later use. Other procedures suitable for the incorporation of bromine and chlorine into absorbents such as activated carbon will also be known or may be known to those skilled in the art and have the advantages taught by the present patent application. Thermal stability The thermal stability of a substance can be assessed by the temperature at which the initial energy is released, also known as the initial oxidation point (P10) of the substance. In the present patent application (including the scope of the patent application), the PIO system of the composition and/or absorbent of the present invention is defined as the temperature at which the heat flow measured by DSC is 10 W/g, and the reference line has been Corrected to be zero at 100 degrees C. The composition of the present invention has improved thermal stability compared to the absorbent used in this composition, and the composition has a PIO of at least about 10 degrees C higher than that of the absorbent only. The composition of the present invention has a PIO that is at least about 10 degrees C to about 94 degrees C higher than the PIO of the absorbent, or from about 10 degrees C to about 90 degrees C, or from about 10 degrees C to about 50 degrees C. Or about 20 degrees C to about 80 degrees C. 201021899 Flammable Fuel The process and absorbent composition of the present invention are suitable for use in reducing mercury emissions from combustion gases resulting from the combustion of any combustible fuel containing mercury. Such combustible fuels include coal, natural gas, solid or fluid waste and other materials. 0 EXAMPLES The following examples are illustrative of the principles of the invention. It is to be understood that the invention is not limited to any specific embodiment exemplified herein, either in the embodiments or the remainder of the application. In the following examples, we treated wood-derived activated carbon (heat activated wood) samples with bromine chloride. The performance of this sample is compared to a similar activated carbon sample treated with only elemental bromine, elemental chlorine, sodium bromide or potassium bromide. The sodium bromide or potassium bromide used can be taken from commercial products. Performance tests include DSC (which measures the thermal properties of activated carbon) and, in some cases, laboratory tests for mercury capture. φ Example 1 Comparative Example Wood-derived PAC (powdered activated carbon) used in these examples (prepared by a heat activation method) was analyzed by DSC-TGA. The point at which the initial amount of g release (PIO) is 267 degrees C.

EXAMPLE 2 Comparative Example Treatment of PAC with bromine The Pac of Example 1 was brominated according to the method disclosed in US 6,95 3 494. Elemental analysis indicated that the PAC had a bromine content of 5% by weight. The DSC analysis indicated that P10 was 3 64 degrees C. -10- 201021899

Example 3 Comparative Example Treatment of PAC with Chlorine The PAC of Example 1 (9.5 g) was treated with a known amount of gaseous elemental chlorine (0.53 g). Elemental analysis indicated that the chlorine content of PAC was 6% by weight. The DSC analysis indicated that the PIO was 356 degrees C.

Example 4 Treatment of PAC with bromine chloride The PAC of Example 1 (9.6 g) was treated with a known amount of bromine chloride, which was produced by combining bromine (0.36 g) with chlorine (0.15 g). . Elemental analysis indicated that the chlorinated bromine content of PAC was 6% by weight. The DSC analysis indicated that the PIO was 361 degrees C.

Example 5 Comparative Example Treatment of PAC with Sodium Bromate The PAC of Example 1 was treated with a known amount of potassium bromide. The results of the experimental analysis indicated that the bromide content of PAC was 5% by weight. The DSC analysis indicated that the PIO was 27 5 degrees C.

Example 6 Comparative Example Treatment of PAC with Potassium Bromide The PAC of Example 1 was treated with a known amount of potassium bromide. The experimental results of φ analysis indicated that the bromide content of PAC was 5% by weight. The DSC analysis indicated that the PIO was 270 degrees C. Mercury Capture Data for Examples 1-4 The following data indicates that chlorinated bromine treated PAC provides very good mercury capture capacity compared to untreated PAC and only chlorine treated PAC. These data were obtained using the mercury capture device described in US 6,953,494. 201021899 PAC _ Mercury capture amount, (%, average 値) Example 1 (for comparison) 46 Example 2 (for comparison) 72 Example 3 (for comparison) 41 Example 4 65 As shown in these examples 1 &gt Surprisingly, it has been found that a composition of the invention comprising a bromine source, a chlorine source and an absorbent capable of adsorbing bromine and chlorine has a w PIO which is not only higher than the PIO of the absorbent itself, but even with the absorbent and The PIO of the composition of the bromine source (ie, no measurable amount of chlorine) is high. At the same time, the mercury emission reduction ability of the compositions and methods of the present invention is very good, although it is not as good as a composition consisting essentially of an absorbent and bromine (i.e., no measurable chlorine or other halogen). This is quite a surprising result, as chlorine itself reduces the mercury emission reduction capacity of the absorbent. In view of the fact that the chlorine ratio is significantly lower than that of bromine, the present invention is commercially advantageous. The invention is particularly advantageous in that it permits the use of chlorine which is less expensive than bromine and the use of wood-derived activated carbon for mercury capture. It should be understood that the reactants and ingredients, whether singular or plural, in any one of the scope of the present patent application and the scope of the patent application, whether in the singular or plural, are considered to have a chemical name or a chemical form (eg another The presence of another substance, such as a reactant, solvent, etc., in combination with or prior to contact. It is irrelevant, if any, to the chemical, -12-201021899 change, conversion, and/or reaction that occurs in the resulting mixture or solution, as such changes, transformations, and/or reactions are performed in accordance with the specified components. The natural consequences of putting together the conditions disclosed herein. Thus, the reactants and components are considered to be components that are brought together to carry out the desired chemical reaction, or components that are used to form a combination for performing the desired reaction. Therefore, even though the substance, ingredients and/or components may be referred to in the present formula ("include", "is", etc.) in the scope of the claims below, the so-called substance, ingredient and/or component refers to it. The point in time prior to the first contact, binding, blending or mixing with one or more other e-substance, ingredients and/or components in accordance with the present invention. Regardless of the conversion, if any, the reaction occurring in situ is carried out in the manner contemplated by the scope of the patent application. Thus, in fact, a substance, component or component may be in the process of contacting, bonding, blending or mixing, if carried out in accordance with the disclosure of the present invention and the application of the general knowledge of the chemist of the art. It loses its original properties via chemical reaction or conversion, but this is not important for the correct understanding of the φ content and the scope of its patent application and its correct evaluation of the true meaning and substance. As is well known to those skilled in the art, the term "incorporated" as used herein means that the components "combined" are placed in a container, such as a combustion chamber, a pipeline, or the like. Similarly, a "combination" of ingredients refers to ingredients that have been placed together in such a container. Although the present invention has been described in terms of one or more preferred embodiments, it should be understood that other modifications may be made without departing from the scope of the invention as set forth in the appended claims. -13- 201021899 [Simple description of the diagram] Figure 1 illustrates the procedure that can be used to decompose bromine and chlorine into an absorbent such as activated carbon. [Main component symbol description] 7 System 8 Activated carbon 10 Pipe column 11 Heating/cooling casing

12 Stopcock 14 Stopcock 19 Bromine chloride 20 Round bottom flask Reference -14-

Claims (1)

.201021899 VII. Scope of Application: 1. A method comprising: - adding a composition comprising a bromine source, a chlorine source and an absorbent capable of adsorbing bromine and chlorine to the combustion of one or more combustible fuels during combustion In the gas stream; - thereby reducing mercury emissions from the combustion gas stream. 2. The method of claim 1, wherein the bromine source comprises bromine or HBr e 3. The method of claim 1 wherein the chlorine source comprises chlorine or HCl 〇 4. as claimed in claim 1 A method wherein the bromine source and/or chlorine source comprises bromine chloride. 5. The method of claim 1, wherein the composition also includes bromine chloride. 6. The method of claim 1, wherein the absorbent comprises a carbon-containing ruthenium. 7. The method of claim 1, wherein the absorbent comprises activated carbon. 8. The method of claim 1, wherein the absorbent comprises wood-derived activated carbon or coconut shell-derived activated carbon. 9. The method of claim 1, wherein the combustion gas stream is derived from combustion of coal. 〃 10. The method of claim 1, wherein the composition has a PIO -15-201021899 that is at least about 10 degrees C higher than the PIO of the absorbent only. 11. A method comprising: adding a composition comprising a bromine source, a chlorine source, and an adsorbent capable of adsorbing bromine and chlorine to a combustible fuel before and/or during combustion of the combustible fuel; - burning a combustible fuel; Combustion gas flow; - thereby reducing mercury emissions from the combustion gas stream. The method of claim 11, wherein the combustible fuel comprises coal hydrazine. 13. The method of claim 11, wherein the absorbent comprises a carbonaceous substrate. 14. The method of claim 2, wherein the absorbent comprises activated carbon. 15. The method of claim 2, wherein the absorbent comprises wood © derived activated carbon or coconut shell derived activated carbon. 16. The method of claim 11, wherein the composition has a pio of at least about 10 degrees C»1 than the PI0 of the absorbent only. 7. The method of claim 11, wherein the bromine source comprises Bromine or HBr 〇18. The method of claim 11, wherein the chlorine source comprises chlorine or HC1 〇 19. The method of claim IA, wherein the bromine source and/or the chlorine source-16-201021899 comprises chlorine Bromine. 20. The method of claim 11, wherein the composition also includes bromine chloride. 21. A method comprising: - adding a composition comprising bromine chloride and an adsorbent capable of adsorbing bromine and chlorine to a combustible fuel before and/or during combustion of the combustible fuel; - burning a combustible fuel; - producing Combustion gas flow; - thereby reducing mercury emissions from the combustion gas stream. 22. A composition that reduces mercury emissions from a combustion gas stream comprising a source of bromine, a source of chlorine, and an adsorbent capable of adsorbing bromine. 23. The composition of claim 22, wherein the bromine source comprises bromine or HBr. 24. The composition of claim 22, wherein the chlorine source comprises chlorine or HCl. 0 25. The composition of claim 22, wherein the bromine source and/or chlorine source comprises bromine chloride. 2 6. The composition of claim 22, wherein the composition also includes bromine chloride. 27. The composition of claim 22, wherein the absorbent comprises a carbonaceous substrate. 2 8. The composition of claim 22, wherein the absorbent comprises activated carbon. -17- 201021899 2 9. The composition of claim 22, wherein the absorbent comprises wood-derived activated carbon or coconut shell-derived activated carbon. 30. The composition of claim 22, wherein the composition has a PIO that is at least about 10 degrees C higher than the PIO of the absorbent only. -18-