Views:96 Author:Site Editor Publish Time: 2021-01-22 Origin:Site
With the development of trackless mining in underground mine, the specification of diesel equipment in underground mine is becoming larger and larger, which has become the main equipment and created conditions for improving mining intensity and labor productivity. But the pollution of diesel engine emissions is becoming more and more serious, especially the narrow space of underground mining roadway and stope makes the concentration of 4stroke 6cylinder diesel engine emissions increase. This not only damages the atmospheric environment of underground mines, but also directly endangers the health of underground workers.
1. Optimize combustion chamber structure to reduce tail gas pollutants
Improvement of the fuel combustion is used to reduce the exhaust emissions of diesel engine. A kind of 4stroke electric starting diesel engine is designed with the combustion chamber and auxiliary combustion chamber embedded in the cylinder as a vortex manifold. Its main combustion chamber is located at the top of the piston and there are two deep pits at the top of the piston. The fuel combustion is divided into two stages: when the piston moves upward, the gas enters the auxiliary combustion chamber along the tangential channel to generate strong eddy current, which results in a large amount of fuel in the mixture formed after the fuel injected is mixed with it. This part of fuel first ignites in the auxiliary combustion chamber and the combustion reaction generates less NOx due to lack of oxygen. The secondary combustion avoids the unfavorable factors of local anoxia in the main combustion chamber and reduces the CO, HC, soot and aldehydes emissions. This kind of low pollution diesel engine is widely used in Underground LHD and vehicle and other diesel trackless equipment.
2. Improve fuel supply system to reduce NOx emission
Adjusting the injection advance angle is not only effective for direct high speed 6cylinder diesel engine, but also for compound combustion chamber diesel engine. Reducing the injection advance angle and delaying the injection start time can reduce the combustion temperature in the cylinder to reduce the NOx content in the exhaust gas. A lot of experimental research work has been carried out in China. For example, after reducing the injection advance angle of swirl chamber diesel engine from 7 ° to 3 ° and the maximum power to 98.3%, NOx in exhaust gas is reduced by 31%. It is necessary to study the economy and power performance of diesel engine.
3. Using exhaust gas recycling technology to reduce NOx
Experimental studies at home and abroad show that EGR is one of the effective technologies to reduce NOx. When the exhaust gas of powerful 12cylinder diesel engine is introduced into the intake system and combusted together with the combustible mixture, the combustion speed and temperature will be significantly reduced. Therefore, the effect of EGR is mainly to suppress the amount of combustible mixture formed in the ignition delay period. As the engine speed decreases, NOx decreases more significantly. If the inlet of EGR is set at the inlet of compressor, EGR can be easily realized in the whole load range. However, necessary measures should also be taken to improve its power and economy so as to reduce the generation of CO and carbon smoke.
4. Optimize the combustion process of the mixture to achieve electronic control injection
Although there are many pollutants in high speed 6cylinder diesel engine generator, turbocharging and intercooling technology can prevent early combustion in recent years. In particular, the combination of shortening ignition delay time and delaying fuel injection time can reduce NOx emission and avoid black smoke during injection delay period. By improving the ignition performance of 4stroke turbocharger diesel engine and reducing the fuel consumption during deflagration, NOx can be effectively inhibited. It is necessary to improve the fuel injection system in order to obtain the ideal mixture and realize the overall control of fuel injection pressure, injection timing, injection duration, injection quantity and fuel injection form.