JPH06280546A - Denitration device for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce nitrogen oxides NOX in exhaust gas on a catalyst layer on a catalyst support by reducer without generating ammonium sulfate acid in the case where sulfur content is included in fuel by utilizing a position and a timing in which an exhaust temperature is high sufficiently. CONSTITUTION:The denitration device for an internal combustion engine is formed in such constitution that a denitration device 40 is arranged per exhaust passage of each cylinder, and also reducer for reducing NOX in exhaust gas is added in the exhaust pipe simultaneously with opening of an exhaust valve 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a denitration device applied to a reciprocating internal combustion engine, especially a diesel engine.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional denitration catalyst carrier layer 4 is installed in an exhaust collecting pipe section 3, and a reducing agent supply device 7 is also installed upstream of the exhaust gas collecting tube section 3 for substantially continuous reduction. Agent is being supplied. In addition, 1 is the exhaust valve of the cylinder, 2
Is an exhaust port, 5 is a reducing agent tank, 6 is a reducing agent charging pump, 8 is an exhaust collecting pipe, 9 is a scavenging tank, 10 is a fuel injection valve, and 12 is a cylinder.

[0003]

However, in a two-cycle engine or the like, a large amount of fresh air is blown through during scavenging, and the exhaust gas temperature in the exhaust collecting pipe portion 3 is low. Therefore, the reducing agent supply device 7 is installed in the exhaust collecting pipe portion. However, there is a drawback that the effect of introducing the reducing agent by the apparatus cannot be sufficiently obtained. That is, ammonia NH ₃
Alternatively, when an ammonia derivative (for example, urea) is used as the reducing agent, when the sulfur (S) content in the fuel is contained and the exhaust gas temperature is low, SO ₃ and NH _{3 in the} exhaust gas
Etc. to form acidic ammonium sulfate, which is adsorbed on the catalyst layer on the catalyst carrier, deteriorating the catalytic performance.

An object of the present invention is to solve the above-mentioned problems and to utilize a portion having a sufficiently high exhaust temperature and a sufficiently high time,
Nitrogen oxides (NOx) in exhaust gas do not generate acidic ammonium sulfate even when the fuel contains sulfur (S).
The to provide an NO _X reduction means in diesel engine exhaust gas can be reduced on the catalyst layer on the catalyst support with a reducing agent.

[0005]

In the denitration device for an internal combustion engine according to the present invention, a denitration catalyst device is installed in each exhaust passage of each cylinder, and a reducing agent for reducing NO _x in exhaust gas is opened in the exhaust valve. At the same time, the feature is that means for adding to the exhaust pipe is provided for each cylinder.

[0006]

By installing the catalyst device 40 at a high temperature portion near the exhaust valve of the exhaust manifold at the outlet of each cylinder of the internal combustion engine, and further causing the reducing agent to act on the hot exhaust gas immediately after the exhaust valve is opened, It is possible to maintain a sufficient temperature, avoid a troublesome reaction that causes acidic ammonium sulfate on the catalyst layer on the denitration catalyst carrier, and provide an extremely effective NO _x reduction device in exhaust gas.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a case where the present invention is applied to a four-cylinder uniflow two-cycle engine. In the figure, 12 is a cylinder, 1 is an exhaust valve, 2 is an exhaust port, 8 is an exhaust collecting pipe, 9 is a scavenging tank, and 40. Is a catalyst layer on the denitration catalyst carrier provided at the exhaust port outlet of each cylinder, 70
Is a reducing agent injection valve provided in front of the catalyst carrier layer at the outlet of each cylinder exhaust port, 5 is a reducing agent tank, 6 is a reducing agent injection pump, 50 is an exhaust valve open valve sensor, and 60 is a reducing agent injection valve. The valve opening controller 10 indicates the fuel injection valve of each cylinder.

Next, the operation of the above embodiment will be described.
When the exhaust valve 1 of each cylinder opens, the exhaust valve opening sensor 50 detects this and opens the reducing agent injection valve 70 to inject a set amount of reducing agent. At this time, immediately after the valve is opened, the position of the reducing agent injection valve is that the exhaust port 2 near the exhaust valve 3
Therefore, the exhaust gas is kept at a sufficiently high temperature, and in that state, the reducing agent is directly mixed with the exhaust gas to maintain a sufficient temperature on the catalyst layer on the catalyst carrier installed at the outlet of each cylinder port 2. It is sent as it is, and NO _x is sufficiently reduced because it comes into contact with the catalyst layer.

[0009]

The present invention is configured as described above, and the high temperature gas discharged from each cylinder is mixed with the reducing agent added in synchronization with the high temperature gas and sent in a sufficiently high temperature state.
Therefore, even if low-temperature gas is exhausted by blow-by of scavenging gas in the latter half of exhaust, problems such as generation of acidic ammonium sulfate on the catalyst layer on the catalyst carrier are eliminated, and sufficient NO _X reduction action is obtained, and exhaust gas can be purified. Become.

[Brief description of drawings]

FIG. 1 is a diagram in which the present invention is applied to a 4-cylinder 2-cycle engine.

FIG. 2 FIG. 1 corresponding diagram of a conventional example

[Explanation of symbols]

1 ... Exhaust valve, 2 ... Exhaust port, 12 ... Cylinder, 40 ...
Denitration catalyst carrier layer (Denitration catalyst device), 70 ... Reductant injection valve, 5 ... Reductant tank, 50 ... Exhaust valve open valve sensor, 6
0 ... Opening controller for reducing agent injection valve.

Claims (1)

[Claims] 1. In an internal combustion engine, a denitration catalyst device (40) is installed in each exhaust passage of each cylinder, and a reducing agent for reducing NO _x in exhaust gas is added into the exhaust pipe at the same time when the exhaust valve is opened. A denitration device for an internal combustion engine, characterized in that each cylinder is provided with a means for performing.