KR20070052389A - Nox reducing solution reagent using wastewater and sewage - Google Patents

Abstract

The present invention relates to a reducing solution preparation used in a selective non-catalytic reduction process, and more particularly, to a non-catalyst reducing solution preparation using inflow and effluent of wastewater and sewage or treated water from each unit process of a wastewater and sewage treatment plant. It is about manufacturing a. Increasing nitrogen oxide removal efficiency by adding a small amount of urea [(NH ₂ ) ₂ CO] to the influent and outflow of wastewater and sewage containing various organic materials and metals or from the wastewater and sewage treatment plant. Wastewater and sewage or wastewater and sewage treatment plants can effectively reduce the emission species of nitrogen oxide discharge facilities such as waste incinerators and power plants by inducing high removal efficiency even in areas where urea solution does not reduce nitrogen oxides such as 850 ℃. It relates to the production of nitrogen oxide reduction solution using the treated water from each unit process of.

Nitrogen oxides, selective non-catalyst reducing agents, wastewater, sewage, treated water, urea        

Description

NOx Reducing Solution Reagent using Wastewater and Sewage

1 is a result showing the nitrogen oxide reduction effect of the reducing solution material prepared by using the dewatering process water of the sewage treatment plant according to the reaction temperature.

The present invention relates to a reducing solution for reducing nitrogen oxides, and more particularly, as a solution used in a selective non-catalytic reduction method for nitrogen oxides, which is discarded as a waste or causes a problem of waste water. The present invention relates to a high-performance reducing solution material that can be easily applied to nitrogen oxide discharge facilities such as incinerators and power plants because it can be obtained at a lower price than conventional reducing solution materials in manure.

Nitrogen oxide (NOx) contained in exhaust gas is composed of more than 90% nitrogen monoxide, nitrogen dioxide and nitrous oxide and is a representative environmental pollutant that causes global warming and air pollution. Nitrous oxide is one of the main sources of global warming. Nitric oxide acts as a causative agent of acid rain, and it is a harmful substance that can cause urban smog and cause humans to be absorbed into the respiratory tract, resulting in bronchitis and death at high concentrations.

Nitrogen oxides are generated during high-temperature combustion of fossil fuels, and accordingly, the nitrogen oxide control technology is also divided into a method of controlling combustion conditions to reduce the emission concentration and a technique of effectively post-treatment before being discharged into the stack after combustion. The method of controlling the combustion conditions is not considered as an effective control method due to the limit of abatement concentration and the strengthened emission allowance standard, and the selective catalytic reduction method using catalyst which is a post-combustion treatment technique and the selective non-catalytic reduction method without catalyst are used. Eggplant is known as the most commonly used technique.

Selective non-catalytic reduction method is harmless nitrogen oxide via a radical reaction by direct injection of 950 ~ 1000 ^o ammonia in a high temperature region of the C [US Patent No. 3,900,554 Arc or element solution [U.S. Patent No. 4,119,702 No., U.S. Patent No. 4,208,386 No.] It is a technique to reduce by converting to nitrogen and water vapor. The selective catalytic reduction method using a catalyst induces a reaction between a reducing agent and a nitrogen oxide and converts it into harmless nitrogen and water vapor by inducing the reaction between the reducing agent and the nitrogen oxide at the active surface of the catalyst. The reduction method is excellent.

The problem with the selective non-catalytic reduction method is that the urea solution being injected has a very high and narrow operating temperature range between 900 and 1000 ^° C. with high nitrogen oxide removal efficiency. At low temperatures, radical formation is not induced, resulting in low removal efficiency, and at high temperatures, the combustion rate of the injected reducing agent is increased so that no reduction of nitrogen oxides is induced.

Therefore, the conventional method to solve the above problems, a method of using a gaseous additive with the injection of urea aqueous solution [WO 91/17814], a method of injecting alcohol, sugar, ketone with a liquid additive [WO 91/17814], A method of using ammonium carbamate containing ammonium ions as a reducing agent (US Pat. No. 4,997,631), a method using KOH, NaOH as an additive (US Pat. No. 5,543,123), and the like have been proposed. As a method of using an additive, an aqueous ammonia solution is used, and an aqueous solution of ammonium carbonate and ammonium oxalate is used as a liquid additive, and a gaseous additive is hydrogen, carbon monoxide, and a hydrocarbon [US Pat. No. 3,900,554]. There is a method using hydrogen peroxide [US Pat. No. 4,777,024].

However, such conventional methods have room for improvement due to the disadvantage that most additives are expensive or do not exhibit high reduction efficiency over a wide temperature range.

Therefore, the present inventors have solved the above problems, and as a result of research to develop a reducing agent for reducing nitrogen oxides at a low price, a small amount of elements using wastewater and sewage or treated water from each unit process of the wastewater and sewage treatment plant A method for preparing the added reducing solution was developed. Various organic substances and metals contained in wastewater and sewage or treated water from each unit process of wastewater and sewage treatment plant are OH generated by decomposition of urea. The formation of radicals enables the formation of radicals at a lower temperature, so that the nitrogen oxide removal efficiency is rapidly improved even at low temperatures, and thus it can be utilized as a reducing solution for removing nitrogen oxides.

Accordingly, an object of the present invention is to provide an improved catalyst-free reducing agent having an excellent effect of reducing nitrogen oxide at high temperature as well as at low temperature in order to increase the reduction efficiency of nitrogen oxide, unlike the related art.

The present invention provides a selective non-catalytic reducing agent for reducing nitrogen oxides containing mainly treated water from wastewater and sewage or wastewater and sewage treatment plants and adding insufficient urea components. It is characterized by a selective non-catalyst reducing agent having a treated water content of 1-99% from each unit process of wastewater and sewage treatment plants.

Referring to the present invention in more detail as follows.

The present invention is to reduce the nitrogen oxides generated in the combustion apparatus by adding a small amount of urea to the wastewater and sewage or the treated water from each unit process of the wastewater and sewage treatment plant in a 850 ^o To apply a conventional reducing solution, such as C relates to a selective non-catalyst reducing agent for reducing nitrogen oxides can obtain a high nitrogen oxide removal efficiency even in a low reaction temperature range.

The selective non-catalytic reducing agent for reducing nitrogen oxides according to the present invention will be described in more detail according to the preparation method as follows.

In order to make the reducing solution material, 1 ~ 50% by weight of urea is adjusted to the treated water from each unit process of wastewater and sewage or wastewater and sewage treatment plant to complete the final solution solution.

Therefore, the selective non-catalytic reducing agent for reducing nitrogen oxides according to the present invention is effective in the temperature range of 800 to 1050 ^° C. using an active ingredient and a small amount of the treated water from each unit process of wastewater and sewage or wastewater and sewage treatment plant. Since it is possible to reduce the nitrogen oxides, it is possible to reduce the water consumption cost required to control the environmental pollution, so that it can cope with the environmental pollution prevention very effectively.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by Examples.

Example 1

The treated water and urea from the sludge dewatering process of the sewage treatment plant were mixed in a mass ratio of 95: 5 to prepare a final nitrogen oxide reducing solution, and the effects of the present invention were tested in a reactor simulating a combustion furnace.

The configuration of the apparatus used is as follows. The reactor was made of 0.2m in diameter, 6m in length, high temperature refractory (Castable) and SS304 conduit, and LPG burner was used to control the temperature inside the reactor. Flue gas and nitrogen oxide were supplied from inside the reactor, and a nozzle was installed at the side of the reactor to spray nitrogen oxide reduction solution. After completing the reaction, the flue gas was sucked through the sampling tube, and the change in concentration was measured using a gas analyzer.

Here, the concentration of nitrogen oxide was adjusted to 500 ppm and the reaction temperature was changed to 800 ~ 1000 ^o C by spraying a reducing agent prepared and shown in Figure 1 by measuring the reduction rate.

Comparative Example 1

The result obtained by spraying the reducing solution material using the same conditions as in Example 1 by preparing a reducing solution material using 95 g of water and 5 g of urea is shown in FIG. 1.

As described above, the reducing solution for reducing nitrogen oxides is manufactured by adding a certain amount of urea to wastewater and sewage or treated water from each unit process of wastewater and sewage treatment plants. By chemically promoting radical reaction at low temperature such as 850 ^o C, high efficiency nitrogen oxide reduction effect can be obtained. By extracting active ingredient using waste, it is economical environment to reduce the cost of water use and the load of treatment plant. a nitrogen oxide reduction materials in solution to prevent contamination, and can be widely used as a reducing agent for purifying NO _X in the automotive and other industrial facilities.

Claims (1)

Reducing agent for reducing nitrogen oxides, additives for reducing nitrogen oxides using treated water from each unit process of wastewater and sewage or wastewater and sewage treatment plants.

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