JPS61287427A - Denitrating apparatus - Google Patents

Abstract

PURPOSE:To perform the high-efficiency denitration even if during the temperature change by arranging the denitrating catalyst which is highly efficient respectively at the exhaust gas temperature during a steady operation and at the exhaust gas temperature during the temperature change at the rear position of an optional heat-transfer surface. CONSTITUTION:The denitrating catalyst 4, 5 is made upon the basis of titanium oxide having a selected blending ratio so as to exhibit the maximum denitrating ratio respectively at the exhaust gas temperature T1 during the steady operation at the exhaust gas temperature during the temperature change T2. During the steady operation, the exhaust gas 2 is cooled up to T1 by the heat-transfer surface 3a and is effectively nitrated by the denitrating catalyst 4. On the other hand, when the temperature of the inlet part of a waste heat boiler is changed, the exhaust gas is cooled up to T2 by the heat-transfer surface 3a and is efficiently denitrated by the denitrating catalyst 5.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a denitrification device.

[Prior Art] Conventionally, a denitrification device using a catalyst has been employed to denitrify exhaust gas from a boiler such as an exhaust heat boiler.

[Problems to be Solved by the Invention] However, the performance of a catalyst for a denitrification device varies depending on the gas temperature, and has the property that the highest efficiency can be obtained at a certain temperature. On the other hand, the gas temperature in each part of a boiler, such as an exhaust heat boiler, varies depending on the operating condition, and for this reason, conventionally, the catalyst in the denitrification equipment is not used at an efficient temperature, which reduces the denitrification effect. I had a problem with it. Possible causes of the difference in the gas temperature include a change in the boiler load, a case where reheating is performed in front of the exhaust heat boiler, and a case where the type of fuel differs and the boiler inlet gas temperature changes.

The present invention has focused on the above-mentioned conventional problems, and aims to provide a denitrification device that can perform denitrification with high efficiency even when the exhaust gas temperature changes.

[Means for solving the problems] The present invention attempts to solve the above technical problems, and
In a denitrification equipment installed in a place where the gas temperature at the rear of multiple heat transfer surfaces changes depending on the operating conditions, such as a waste heat boiler, the gas temperature during steady operation can be adjusted at any rear position of the heat transfer surface. and a denitrification device characterized in that denitrification catalysts each having different characteristics capable of performing highly efficient denitration with respect to gas temperature when the temperature changes are arranged side by side.

[Function] Therefore, in the present invention, a denitrification catalyst having different characteristics that can perform highly efficient denitration with respect to the exhaust gas humidity during steady operation and the exhaust gas temperature when the temperature changes is placed at an arbitrary rear position of the heat transfer surface. Since they are arranged in parallel, highly efficient denitrification can be performed on the exhaust gas during steady operation and during temperature changes.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a waste heat boiler to which the present invention is applied. Inside the waste heat boiler main body 1, there are a plurality of evaporation sections and preheating sections that exchange heat with the exhaust gas 2, and a superheating section, etc. A large number of heat transfer surfaces 3a consisting of.

3b, 3c, and 3d are provided.

Denitration catalysts 4 and 5, which are configured to have different characteristics, are arranged in parallel at arbitrary positions on the heat transfer surfaces 3a, 3b, 3c, and 3d, for example, at the rear of 3a.

That is, as shown in FIG. 2, the exhaust gas temperature is lowered each time it passes through the heat transfer surfaces 3a, 3b, 3c, and 3d in FIG. Therefore, the temperature curve (solid line) A in the normal operating state,
In the temperature curve (broken line) A' when the exhaust gas temperature of the denitration equipment changes due to reheating or the like, which is predicted or obtained by actual measurement, the temperature at the exit side of the heat transfer surface 3a is about 1.
It is as different as Ding 2. Therefore, at the rear position of the heat transfer surface 3a,
As shown in FIG. 3, denitrification contacts RS4 and RS5, which do not show the highest denitrification effect at temperatures T1 and T2 and have different characteristics, are arranged side by side. Furthermore, the denitrification catalysts 4 and 5 can achieve the highest denitrification effect at exhaust gas temperatures of T1 and T2 by selecting active ingredients based on titanium oxide, etc., and selecting their mixing ratios. Manufactured to be used.

In the figure, To z To ' indicates the exhaust heat boiler inlet temperature.

In the above, during steady operation, the temperature of the exhaust gas 2 at the inlet of the waste heat boiler is To by being cooled by the heat transfer surface 3a, and is lowered to T1, and at this temperature T1, the denitrification effect is the highest. Nitrification is effectively carried out by contact ts4. Also, the temperature at the exhaust heat boiler inlet changes and To
', the temperature is lowered to T2 by the heat transfer surface 3a, and the denitrification catalyst 5, which exhibits the highest denitrification effect at this temperature T2, effectively denitrates.

At this time, the installation positions of the denitration catalysts 4 and 5 are
Considering the performance of item 5, etc., it should be installed at the exhaust gas temperature position where the denitrification effect is the best.

In this way, any heat transfer surface 3a, 3b, 3c, 3
By arranging the denitrification catalysts 4 and 5, which have different characteristics corresponding to changes in the exhaust gas temperature in that portion, in parallel at the rear position of d, the denitrification device can be made compact.

Incidentally, the arrangement position, number, etc. of the denitrification device are not limited to the illustrated embodiment.

[Effects of the Invention] As described above, the denitrification device of the present invention uses a denitrification catalyst that has separate characteristics that can perform highly efficient denitration for each of the exhaust gas temperature during steady operation and the exhaust gas temperature when the temperature changes. Since they are placed side by side at any rear position of the heat transfer surface, highly efficient denitrification can be performed on exhaust gas during steady operation and during temperature changes.Moreover, the denitrification catalyst is placed side by side. It is possible to achieve excellent effects such as the ability to make the denitrification device more compact, and also the ability to perform highly efficient denitrification even in response to large changes in exhaust gas temperature.

[Brief explanation of drawings]

Fig. 1 is a cutaway side view schematically showing an example of a waste heat boiler to which the present invention is applied, Fig. 2 is a diagram showing temperature changes inside the waste heat boiler, and Fig. 3 is a diagram showing the temperature of the denitrification catalyst and the denitrification rate. It is a line diagram showing a relationship. 1 is the exhaust heat boiler main body, 2 is the exhaust gas, 3a, 3b. 3c and 3d are heat transfer surfaces, and 4 and 5 do not show denitrification catalysts.

Claims (1)

[Claims] 1) In a denitrification equipment installed in a place where the gas temperature at the rear of multiple heat transfer surfaces changes depending on the operating conditions, such as a waste heat boiler, the gas temperature during steady operation can be A denitrification device characterized by juxtaposing denitrification catalysts each having separate characteristics capable of performing highly efficient denitration with respect to temperature and gas temperature when the temperature changes.