JPS6046245B2 - Diesel engine exhaust gas purification method - Google Patents

Description

[Detailed Description of the Invention] The present invention disperses a harmless highly active adsorbent into a water scrubber installed in the exhaust system of a diesel engine, and adsorbs and removes harmful substances such as smoke from exhaust gas. It is about the method.

Diesel engines normally used underground for mining ores have a large displacement of 4,000cc to 15,000cc, and in environments such as underground mines where ventilation is relatively difficult to achieve, diesel engines are used to improve the working environment. It is desirable to convert the exhaust gases from the

As a countermeasure to this problem, current underground diesel vehicles are equipped with a water scrubber in the engine exhaust system to wash the exhaust gases with water, thereby minimizing the amount of harmful substances such as smoke. However, these large diesel vehicles usually operate their engines under high load, so the amount of gas emitted from the diesel engine is enormous.
Simply bringing the exhaust gas into contact with water for a short period of time in a water scrubber has very little water cleaning effect.

In addition, an attempt has been proposed to further install an oxidation catalyst in the exhaust system between the water scrubber and the diesel engine in a diesel engine equipped with a water scrubber, and to purify the exhaust gas using a combination of this oxidation catalyst and the water scrubber. ing.

However, the temperature of the oxidation catalyst layer is generally 300℃.
Before and after the exhaust gas purification effect of such an oxidation catalyst, although it is possible to remove some volatile harmful substances, it cannot be expected to effectively remove other harmful substances such as solid fine particles. be. As mentioned above, using a water scrubber to remove harmful substances in the exhaust gas that has passed through the oxidation catalyst layer, which contains most of the solid fine particulate harmful substances, is not sufficiently effective. In view of the above-mentioned current situation, the present invention aims to further improve the exhaust gas purification effect of large diesel engines used in working environments such as underground mines. This is a diesel engine exhaust gas purification method characterized by adding and dispersing an adsorbent into the exhaust gas, thereby adsorbing and removing harmful substances contained in the exhaust gas.

The adsorbent used in the present invention is not particularly limited as long as it is harmless and can be dispersed in the water scrubber to adsorb harmful substances in exhaust gas, but activated alumina, montmorillonite, which is inexpensive and has excellent adsorption performance, It is preferable to use one or more of activated carbon, activated clay, or zeolite.

The amount used is within a range that does not increase the exhaust pressure of the engine, and is usually preferably 5 to 10 y/e. If a surfactant is used together with an adsorbent in a water scrubber, the adsorption effect of fine particles will be improved, so the surfactant is used as necessary. By adding and dispersing the adsorbent in the water scrubber in this way, the exhaust gas from the diesel engine that has passed through the oxidation catalyst layer is introduced into the water scrubber, where the harmful substances in the exhaust gas are firmly adsorbed on the adsorbent surface. is collected and remains in the scrubber. At this time, if an adsorbent and a surfactant are used together, the adsorption layer will be enhanced. Furthermore, when an adsorbent adsorbs more than a certain amount of fine particles, its adsorption ability decreases, but since the water in a water scrubber is usually replaced about once a day, it is sufficient to replenish the adsorbent each time.

According to the present invention, existing water scrubbers can be used as they are, and exhaust gas from diesel engines used in underground working environments can be sufficiently purified. The present invention will be described below with reference to Examples.

EXAMPLE A diesel engine shovel car with a displacement of 5,600 cc was operated in a closed room, and carbon monoxide, hydrocarbons, and particulates discharged from the diesel car were measured.

The diesel car we used was equipped with a 66 x 95 x 3 water scrubber, and in the exhaust system between this water scrubber and the engine, there was about 50C77 in front of the water scrubber! 150φ x 30 at the position of
When one cylindrical honeycomb catalyst of 0em/TrL was installed and 150' of water was put in the water scrubber, and in addition to 150' of water, activated alumina alone, activated alumina and zeolite, montmorillonite alone, and activated alumina and surfactant were added. Carbon monoxide, hydrocarbons, and particulates in the exhaust gas were collected by driving a diesel vehicle at a high load of 60% or more of the maximum horsepower for both cases in which four types of adsorbents were added and dispersed. Carbon monoxide and hydrocarbons were collected directly from the exhaust gas outlet after cleaning the water scrubber, and carbon monoxide was analyzed using a non-dispersive infrared ray analyzer, and hydrocarbons were analyzed using a hydrogen flame ion analyzer. A high-volume air sampler installed at least 1rrt away from the exhaust port of a diesel vehicle sucks in the exhaust gas at a suction speed of 1d/min until the exhaust gas suction amount reaches 50mm or more. The inorganic carbon content and organic carbon content contained in the fine particles collected above were chemically analyzed.The results are shown in the table below. It was confirmed that emissions of carbon monoxide and hydrocarbons as well as inorganic and organic carbon were significantly reduced.

Claims (1)

[Claims] 1 In a method of purifying diesel engine exhaust gas by installing an oxidation catalyst in the exhaust system between the water scrubber and the diesel engine, an adsorbent is added and dispersed in the water scrubber to remove the oxidation catalyst from the exhaust gas. A diesel engine exhaust gas purification method characterized by adsorbing and removing harmful substances.