NOX treatment apparatus employing reforming reactor with specialized structure and reforming conversion agent supply system

Abstract

The present invention relates to a NOx treatment apparatus employing a reforming reactor with a specialized structure and a reforming conversion agent supply system. More specifically, in order to remove NOx contained in exhaust gas with high efficiency, a high-efficiency NO reforming reactor is installed in an exhaust gas duct, and in order to increase the reactivity of a self-prepared reforming conversion agent-mixed solution, the reforming conversion agent-mixed solution is introduced in the form of an air jet type mist by using a reforming conversion agent supply system, so that poorly soluble NO in the exhaust gas is converted and reformed into soluble NO2, and residual NOx is removed by an absorption scrubber and discharged to the atmosphere.

Description

NOx treatment device applying a specialized structured reforming reactor and reforming agent supply system

[0001] The present invention relates to a NOx treatment device applying a reforming reactor of a specialized structure and a reforming agent supply system. More specifically, to remove NOx contained in exhaust gas with high efficiency, a high-efficiency NO reforming reactor is installed in an exhaust gas duct; to enhance the reactivity of a self-manufactured reforming agent mixed solution using a reforming agent supply system, the solution is injected in the form of an air jet type mist to convert and reform sparingly soluble NO in the exhaust gas into soluble NO2, and the remaining NOx is removed in an absorption scrubber and discharged into the atmosphere.

[0002] In general, NOx-containing exhaust gases are generated from incomplete combustion reactions and chemical reactions using nitric acid and nitrates in processes where combustion takes place, such as incinerators, furnaces, and heaters. For example, large amounts of nitrogen oxides are emitted from incineration facilities, cement plants, petrochemical plants, power generation boilers or gas turbines, industrial boilers, and diesel engines, becoming a major cause of pollution. The most significant harms of this concern photochemical smog, the greenhouse effect, and soil acidification caused by acid rain, which react with hydrocarbons in the presence of sunlight to produce photochemical oxides and oxidants.

[0003] NOx is a significant air pollutant emitted during the combustion of fuel and is a term that includes all nitrogen oxides such as N2O, NO, N2O3, NO2, N2O5, and NO3; however, in this specification, NO and NO2, which are the most problematic causes of air pollution among these nitrogen oxides, are referred to as NOx. Recently, as awareness of environmental preservation has increased, emission regulations for NOx are being introduced, while research and development to remove NOx from exhaust gases is actively underway.

[0004] The general denitrification process is the wet lime / limestone process (WLP) using limestone slurry, and dry processes using dry absorbents (SDS Semi-dry sorption) and activated carbon processes are partially commercialized.

[0005] Exhaust gas denitrification methods are classified into wet and dry methods, and a representative commercialized process is the dry method, Selective Catalytic Reduction (SCR). SCR is a method that selectively reduces nitrogen oxides in exhaust gas into nitrogen and water by simultaneously introducing exhaust gas and a reducing agent (NH3, CO, hydrocarbons, etc.) into a catalyst bed (metal oxide, zoelite).

[0006] Although ammonia is mainly used in the SCR process because it is a toxic substance that is difficult to handle and corrodes various equipment, and there is a possibility of groundwater contamination in the event of a leak, it must be stored in a double-walled storage tank or built on a protected ground, and there is a concern that a major accident could escalate because it is difficult to respond quickly due to the difficulty of accessing the accident site in the event of a leak.

[0007] In addition, Selective Non-Catalytic Reduction (SNCR), which involves injecting a reducing agent into the combustion chamber without using a separate process, is partially utilized. While it has the advantages of excellent applicability—such as not requiring the use of a catalyst, having lower initial installation costs compared to other NOx reduction technologies, and being simple to apply to existing facilities without requiring separate installation space—it has the disadvantages of a limited effective temperature range and requiring high gas temperatures. Although it exhibits a denitrification efficiency of 30–50% in the reaction temperature range of 850–1,100 ℃, NOx generation increases due to the oxidation reaction of the supplied reducing agent (urea solution, ammonia solution) in the temperature range above the reaction temperature range, and ammonia slip occurs in the lower temperature range because the reducing agent does not react efficiently.

[0008] In particular, the Selective Catalytic Reduction (SCR) method is a technology that uses ammonia as a reducing agent to convert it into harmless N2 and H2O for the removal of NOx. It is capable of achieving NOx reduction efficiency of over 90% and has several advantages such as ease of operation and maintenance. As such, it is the most representative technology for reducing NOx developed to date and has already been commercialized globally and is in operation in various plants.

[0009] In addition, absorption scrubbers are a type of gas dust collector that processes gases in a wet manner, and although attempts have been made to remove NOx using them, their efficiency is very low at less than 30%, making it difficult to use them alone as a NOx reduction technology.

[0010] Therefore, there is a need to develop a new type of NOx treatment device capable of removing NOx from flue gas with high efficiency by improving or modifying existing treatment methods.

[0011] The present invention is developed to efficiently remove NOx contained in exhaust gas and aims to provide a NOx treatment device that applies a NO reforming reactor of a specialized structure and a reforming agent supply system.

[0012] In addition, the present invention aims to provide a low-cost NOx treatment device specialized for exhaust gas ducts that can resolve the high equipment and operating costs associated with replacing SCR or SNCR involved in removing NOx.

[0013] In order to solve the above technical problem, a treatment device for removing NOx contained in exhaust gas with high efficiency according to the present invention comprises: a NO reforming reactor (100) into which the discharged exhaust gas is introduced; four inlets (110) into which a reforming conversion agent mixed solution is introduced at the front end of the NO reforming reactor; an impeller-type mixed reaction outlet (130) installed at the rear end of the NO reforming reactor; and an absorption scrubber (200) that removes soluble NO2 from the exhaust gas passing through the NO reforming reactor (100) by absorbing it into water.

[0014] The front end of the NO reforming reactor (100) is configured as a double pipe and is designed so that 30% of the incoming exhaust gas is supplied to the inner pipe (121) and the remaining 70% is supplied to the outer pipe (122), and the rear end of the NO reforming reactor (100) is designed in an impeller-type shape that allows the exhaust gas to form a fluid flow in a dispersed and vortex state within the reactor, thereby increasing the reaction efficiency of the reforming agent mixed solution.

[0015] The above-mentioned reforming agent mixed solution is characterized by mixing ozone from an ozone supply unit (10) for oxidizing NOx, air from an air input unit (20), and a reforming agent from a reforming agent manufacturing unit (30), and injecting this mixed solution in the form of a mist through injection nozzles (not shown) of four input ports (110) to convert insoluble NO in the exhaust gas into soluble NO2.

[0016] The above-mentioned modifying agent is characterized by comprising at least one of the substances selected from the group consisting of ammonia, urea, hydrogen peroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, and sulfuric acid.

[0017] In addition, the present invention includes a high-efficiency NOx treatment device in the form of a hybrid device in which the NO reforming reactor (100) described above is additionally combined with a NOx treatment device using a selective catalytic reduction (SCR) or a non-selective catalytic reduction (SNCR).

[0018] According to the NOx treatment device of the present invention, by installing a NO reforming reactor of a new structure, the reactivity between the reforming agent mixed solution and the exhaust gas is increased, thereby converting and reforming sparingly soluble NO into soluble NO2, so that NO removal can be significantly improved.

[0019] In particular, by designing the above NO reforming reactor as a double pipe, the supply of exhaust gas can be dispersed and the reactivity with the reforming agent mixed solution can also be increased.

[0020] In addition, due to the reforming agent supply system of the present invention, uniform reactivity can be secured by mixing the air jet type air and the reforming agent together before introducing ozone into the NO reforming reactor (100) and then introducing them into the exhaust gas, and there is an advantage of obtaining a fast reaction and high diffusion by introducing them in the form of a mist to increase the contact area.

[0021] In addition, by installing four inlets for the reforming agent mixture solution, it can be sprayed uniformly and precisely into the reactor, allowing it to react effectively with the exhaust gas.

[0022] FIG. 1 is a schematic diagram illustrating a NOx treatment device that performs a high-efficiency denitrification process according to one embodiment of the present invention.

[0023] Figure 2 is a schematic diagram illustrating the process of exhaust gas passing through the NO reforming reactor included in the NOx treatment device of Figure 1.

[0024] The present invention will be described in detail below.

[0025] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0026] FIG. 1 schematically illustrates a NOx treatment device for performing a high-efficiency denitrification process according to an embodiment of the present invention. Referring thereto, the treatment device for removing NOx contained in exhaust gas with high efficiency according to the present invention comprises: a NO reforming reactor (100) into which the discharged exhaust gas is introduced; four inlets (110) into which a reforming conversion agent mixed solution is introduced to the front end of the NO reforming reactor; an impeller-type mixed reaction outlet (130) installed at the rear end of the NO reforming reactor; and an absorption scrubber (200) that removes soluble NO2 from the exhaust gas passing through the NO reforming reactor (100) by absorbing it into water.

[0027] The above absorption scrubber (200) performs the role of further enhancing or supplementing denitrification performance by removing water-soluble NO2 in the exhaust gas through water absorption. If necessary, it can also remove fine dust or gaseous substances that may be contained in the exhaust gas. In particular, even if nitric acid (NO3) that can be formed by the reaction of NO2 with ozone is present, it can also be easily removed as it is soluble in water. At this time, the treated exhaust gas contains about 5 vol% NO and about 0 vol% NO2 and is discharged into the atmosphere. In addition, the above scrubber has the advantage of having low pressure loss, high fine dust capture efficiency, and stable absorption efficiency against flow rate fluctuations.

[0028] The main technical feature of the present invention is the specialized structure of a NO reforming reactor applying a novel type of reforming agent supply system.

[0029] That is, to remove approximately 90 vol% NO and approximately 10 vol% NO2 contained in the exhaust gas, a NO reforming reactor (100) specialized for the exhaust gas duct is installed, and a solution mixed with ozone and a self-manufactured reforming converter is injected into it in the form of a mist by an air jet, thereby converting the insoluble NO in the exhaust gas into soluble NO2 (this is called 'first reforming'), and finally removing the remaining NOx in an absorption scrubber (this is called 'second reforming').

[0030] The structure of the above NO reforming reactor (100) is as follows. The front section is composed of a double pipe, and is designed so that a portion of the exhaust gas being introduced is supplied to the inner pipe (121) and the remaining portion is supplied to the outer pipe (122). On the outer side of the inner pipe, four inlets are installed at 90° angle intervals to allow the reforming agent mixed solution to be introduced. Additionally, by installing four inlets, the solution can be sprayed uniformly and precisely into the reactor, thereby allowing it to react effectively with the exhaust gas.

[0031] It is preferable that the portion of exhaust gas supplied to the inner pipe be about 30% and the portion of exhaust gas supplied to the outer pipe be about 70%, but is not specifically limited thereto.

[0032] In addition, the reason for supplying the injected exhaust gas separately to the inner tube (30%) and the outer tube (70%) is to increase the reactivity of the reforming agent mixed solution of the present invention. In some cases, because a large amount of the solution is suddenly mixed into the exhaust gas, it may not mix evenly or slip may occur. This is a design idea to eliminate such issues, and the exhaust gas in the inner tube (30%) also serves as a dispersion promoter to increase reaction efficiency.

[0033] The above mixed solution is prepared by mixing ozone from an ozone supply unit (10) for oxidizing NOx, air from an air input unit (20), and a reforming agent from a reforming agent manufacturing unit (30), and then injecting this mixed solution in the form of a mist through injection nozzles (not shown) of four input ports (110) to convert insoluble NO in the exhaust gas into soluble NO2.

[0034] The above ozone supply unit (10) may use any product capable of generating and supplying ozone gas, and typically there are two types of structures, plate type and tube type. However, compressed air generated from a compressor is purified through a filter and then supplied along a discharge tube installed between cooling water passages, thereby generating ozone gas as oxygen in the cold, clean air passing through the discharge tube is decomposed and recombinated by collision with electrical energy.

[0035] As in the present invention, if ozone is mixed with air before being introduced into the NO reforming reactor (100) and then introduced into the exhaust gas, there is an advantage in that uniform reactivity can be secured.

[0036] Ozone (O3) is a powerful oxidizing agent that generates OH radicals and can be used to increase reaction efficiency by converting NO to NO2. As a mixing agent with it, it may include at least one of the substances selected from the group consisting of ammonia, urea, hydrogen peroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, and sulfuric acid.

[0037] Among these reforming agents, sodium hydroxide and sulfuric acid have a high mixing ratio with ozone and can generate a large amount of OH radicals, and are among the most adaptable reforming components when treating acidic gases, basic gases, or neutral gases, respectively.

[0038] It is preferable to use the above ingredients mixed at the lowest possible concentration.

[0039] In addition, if the above-mentioned mixed solution is introduced in the form of a mist through the spray nozzles (not shown) of the four inlets (110), the contact area is widened, which has the advantage of obtaining a fast reaction and high diffusion, and the natural decomposition or loss of ozone during the reaction process can be minimized.

[0040] The spray nozzle used for this purpose is preferably for high pressure, but is not limited thereto. However, any spray nozzle capable of controlling particle size by allowing for various pressure adjustments is sufficient.

[0041] Meanwhile, ozone (O3) can be harmful at high concentrations, so it is necessary to handle it within a closed system and comply with emission limits. Also, since it can corrode some metals and materials, it is desirable to use ozone-resistant materials (e.g., stainless steel, PTFE). In addition, hydrogen peroxide, which reacts with ozone to generate OH radicals, has high reactivity with other substances, so special care is required during handling, such as transportation and storage, as there are many risk factors.

[0042] In addition, the rear section is designed in an impeller-type shape that allows the exhaust gas to form a fluid flow in a dispersed and vortex state within the reactor, thereby increasing the reaction efficiency of the reforming agent mixed solution. The exhaust gas reacted here is further dispersed by the exhaust gas in the inner tube (121), and the exhaust gas passing through this is a primary reformed exhaust gas in which most of the sparingly soluble NO is converted into soluble NO2, and contains about 5 vol% NO and about 95 vol% NO2. That is, the 30% of exhaust gas supplied to the inner tube (121) reacts by further dispersing the exhaust gas that comes out of the outer tube (122) in a dispersed and vortex state, thereby having the characteristic of inducing a high-efficiency reaction.

[0043] In the rear section having the shape of the impeller type described above, exhaust gas is discharged by centrifugal force generated by the rotation of fixed rotating blades called vanes; for optimal discharge efficiency, the diameter of the impeller and the number of vanes are important. In particular, the number of vanes may vary depending on the exhaust gas flow rate, and preferably, an impeller with 24 vanes is sufficient.

[0044] In addition, each component disclosed in the present invention can be controlled by an ICT-based control system (not shown). In particular, an ICT sensor-based automation system can be constructed to control in real time, including ozone concentration, ozone flow rate, degree of mixing with the modification agent, and injection amount of the mixed solution to be injected, as well as NOx sensors.

[0045] Accordingly, the NOx treatment device including a reforming reactor to which the reforming agent supply system according to the present invention is applied demonstrates a high NO2 treatment efficiency equal to or greater than that of existing NOx treatment technology by using a self-manufactured reforming agent mixed solution using a NO reforming reactor (100) of a new structure.

[0046] A NOx treatment device according to another embodiment of the present invention may further comprise a cooling unit, a circulation pump, a chemical supply pump, etc. Additionally, a Selective Catalytic Reduction (SCR) device or a Non-Selective Catalytic Reduction (SNCR) device may be used in combination.

[0047] The present invention will be described in more detail below through examples, provided that the following examples are intended only to aid in understanding the invention and do not limit the scope of the invention.

[0048] The present invention is implemented as a NOx treatment device applying a specialized structure of a reforming reactor and a reforming agent supply system, which can significantly improve NO removal by increasing the reactivity between the reforming agent mixed solution and the exhaust gas by installing a NO reforming reactor of a new structure, thereby converting sparingly soluble NO into soluble NO2. However, it is applicable to various industrial fields within the scope of adopting the same configuration as in the present invention.

Claims

1. A treatment device for removing NOx contained in exhaust gas with high efficiency, NO reforming reactor (100) into which exhaust gas is introduced; Four inputs into the upstream section of the above NO reforming reactor to which the reforming agent mixed solution is introduced Gudeul (110); An impeller-type mixed reaction outlet (130) installed at the rear end of the above NO reforming reactor; and The apparatus includes an absorption scrubber (200) that removes soluble NO2 from the exhaust gas passing through the above NO reforming reactor (100) by absorbing it into water, wherein The front section of the above NO reforming reactor (100) is configured as a double pipe and is designed so that 30% of the input exhaust gas is supplied to the inner pipe (121) and the remaining 70% is supplied to the outer pipe (122), and A high-efficiency NOx treatment device characterized in that the rear end of the above NO reforming reactor (100) is designed in an impeller-type shape that allows the exhaust gas to form a fluid flow in a dispersed and vortex state within the reactor, thereby increasing the reaction efficiency of the reforming agent mixed solution.

2. In Claim 1, The above-described reforming agent mixed solution is characterized by mixing ozone from an ozone supply unit (10) for oxidizing NOx, air from an air input unit (20), and a reforming agent from a reforming agent manufacturing unit (30), and injecting this mixed solution in the form of a mist through injection nozzles (not shown) of four input ports (110) to convert insoluble NO in the exhaust gas into soluble NO2.

3. In claim 1 or claim 2, A high-efficiency NOx treatment device characterized by comprising at least one of the substances selected from the group consisting of ammonia, urea, hydrogen peroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, and sulfuric acid as the above-mentioned reforming agent.

4. A high-efficiency NOx treatment device of the hybrid type, in which the NO reforming reactor (100) described in claim 1 is additionally combined with a NOx treatment device using selective catalytic reduction (SCR) or non-selective catalytic reduction (SNCR).

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