JPH0749062A - Nox reduction system for internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress deterioration in lubricating performance, corrosion of a cylinder liner by communicating exhaust air of a cooling tower with a burning air intake duct of an internal combustion engine, and taking in burning air through the cooling tower. CONSTITUTION:A cooling water dropping cooling tower 2 is connected to an intake duct 2 of a diesel engine 1, while air A is introduced into the cooling tower 2 through fins 4 provided on the side surface of the cooling tower 2. The air A cools the diesel engine 1 in the cooling tower 2, and is fed to a number of nozzles 7 through a pipe 6. The air A introduced into the cooling tower 2 is humidified and cooled by cooling water W dropping into the cooling tower 2, stored in a tank 8 on the bottom of the cooling tower 2, and fed back to the diesel engine 1 as the cooling water through a pipe 10 while being suctioned by a pump 9. A cooler may be provided on the way of the pipe 10 for further decreasing a temperature of cooling water to be fed back to the engine 1. Burning air is humidified by the cooling water dropped from the nozzle, and cooling by the burning air is enabled, so that a humidification ratio control device is dispensed with.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a NOx reduction system for an internal combustion engine, especially for a diesel engine.

[0002]

2. Description of the Related Art It is known that humidification of engine air supply is effective as one of the measures for reducing NOx in exhaust gas discharged from a diesel engine. Is being fired. However, in this method, water injected during air supply does not completely evaporate and is sucked into the engine in the form of water droplets. there were.

On the other hand, there is a method in which water vapor is mixed into the engine supply air as a method having no problem in terms of reliability, but it is difficult to say that it is practical because the cost of water vapor is higher than that of the water injection method. Further, there is a problem that the control device is indispensable for controlling the supply amount of water or water vapor according to the operating condition of the engine.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an NOx reduction system for an internal combustion engine which is inexpensive and does not require a control device, without promoting deterioration of lubricating performance and corrosion of a cylinder liner. It is in.

[0005]

That is, a NOx reduction system for an internal combustion engine according to the present invention comprises a cooling water flow-down type cooling tower connected to an intake duct of the internal combustion engine, through which the internal combustion engine is burned for combustion. In order to use the waste heat of the internal combustion engine in order to take in the air and effectively operate the present reduction system, the combustion air is humidified by the cooling water for cooling the internal combustion engine or for cooling the supercharged air. It is a feature.

Since the humidified combustion air is connected to the intake duct of the internal combustion engine in this manner, it does not promote deterioration of lubrication performance or corrosion of the cylinder liner, and is inexpensive.
Moreover, it is possible to humidify the combustion air according to the operating condition of the internal combustion engine without requiring a control device for controlling the humidity. Further, the cooling water can be cooled by the combustion air, and the cooling water cooling system can be downsized.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a cooling water flow-down type cooling tower is adopted as a supply / humidification device will be described in detail with reference to the drawings. In FIG. 1, reference numeral 1 is a diesel engine, 2 is a cooling water flow-down type cooling tower that is attached to the diesel engine 1, and the cooling tower 2 is connected to an intake duct 3 of the diesel engine 1. Cooling tower 3
Air A introduced into the cooling tower 2 through the spaces between the fins 4 provided on the side surface of the diesel engine 1 is taken into the diesel engine 1 via the intake duct 3 and the supercharger 5.

On the other hand, the cooling water W that has cooled the diesel engine 1 flows down through the pipes 6 from a large number of nozzles 7 provided in the cooling tower 2, and the cooling water W causes the inside of the cooling tower 2 to flow. The air A introduced into the air is humidified. The cooling water W flowing down from the nozzle 7 is cooled by the air A flowing into the cooling tower 2, stored in the tank 8 at the bottom of the cooling tower 2, and then pumped up by the pump 9 and passed through the pipe 10. Is returned to the diesel engine 1 as engine cooling water. The cooling water W overflowing from the tank 8 is discharged to the drain groove 12 through the pipe 11.

If it is desired to further lower the temperature of the cooling water W returned to the diesel engine 1, a cooler 13 may be provided in the middle of the pipe 10 as shown in FIG. It goes without saying that the cooling water sent to the cooling tower 4 may be the one guided from an independent cooling water system.

[0010]

As described above, according to the present invention, the combustion air is taken into the internal combustion engine through the cooling water flow-down type cooling tower connected to the intake duct of the internal combustion engine, and the combustion air is taken into the cooling tower. Since it is possible to humidify with cooling water for cooling the internal combustion engine that has flowed down from the nozzle provided inside and to cool the cooling water with the combustion air, deterioration of the lubricating performance of the engine and corrosion of the cylinder liner It has become possible to humidify the combustion air in accordance with the operating condition of the internal combustion engine, without promoting the operation of the internal combustion engine at low cost and without requiring a control device for controlling the humidity of the combustion air.

[0011]

[Brief description of drawings]

FIG. 1 is a schematic diagram of a NOx reduction system for an internal combustion engine according to the present invention.

FIG. 2 is a schematic view showing another embodiment of the NOx reduction system for the internal combustion engine according to the present invention.

[Explanation of symbols]

 1 Diesel Engine 2 Cooling Tower 3 Intake Duct 7 Nozzle A Combustion Air W Cooling Water

Claims (2)

[Claims] 1. An N of an internal combustion engine, wherein exhaust air of a cooling tower is connected to a combustion air intake duct of the internal combustion engine.
Ox reduction system. 2. The NOx reduction system for an internal combustion engine according to claim 1, wherein the medium to be cooled introduced to the cooling tower is engine cooling water or supercharged air cooling water for the internal combustion engine.