Ammonia selective catalytic reduction method for diesel injected by assistance of compressed natural gas

Abstract

The invention belongs to the technical field of diesel tail gas aftertreatment, and in particular relates to an ammonia selective catalytic reduction method for a diesel injected by assistance of compressed natural gas. The method comprises the following steps: pumping urea out of a urea aqueous solution tank; filtering the urea, and delivering the urea to a urea gauger; introducing the compressed natural gas in a compressed natural gas tank into the urea gauger through a primary valve, mixing the compressed natural gas and urea solution, ensuring that the volume ratio of the compressed natural gas to the urea solution is 1:100-20 : 100, and primarily atomizing the urea solution; before the urea solution which is primarily atomized enters an exhaust pipe through a urea nozzle, mixing the compressed natural gas and urea solution which is primarily atomized, ensuing that the volumetric mixture ratio of the compressed natural gas to urea solution which is primarily atomized is 1:100-20:100 so as to improve the mixing uniformity and the atomization degree; decomposing the urea into NH3 and water at a high temperature in an exhaust pipe mixing zone, fully mixing the NH3 and the water and exhaust gas, introducing the mixture into an SCR selective catalytic reduction device; and in the SCR selective catalytic reduction device, reacting NH3 with NOx to generate ammonia gas and H2O, and then discharging the two into the atmosphere. The method realizes efficient atomization of the urea, also reduces the emission of the NOx by reduction through natural gas CH4, and improves the purifying effect on the diesel tail gas NOx.

Description

technical field [0001] The invention belongs to the technical field of post-treatment of diesel engine tail gas, and in particular relates to an ammonia selective catalytic reduction (SCR) method for diesel engines using compressed natural gas to assist injection. Background technique [0002] Due to its good economy and power, diesel engines are widely used in transportation, agricultural machinery and construction machinery and other fields. However, the nitrogen oxide emissions of diesel engines are high, which is very harmful to the environment and human body. In addition to adopting advanced internal measures to reduce nitrogen oxide emissions, it is necessary to take out-of-machine post-treatment measures for the nitrogen oxides discharged from diesel engines. technology in order to meet the more stringent emission regulations in the future. [0003] Ammonia selective catalytic reduction technology is a main technical route for post-treatment of nitrogen oxides (NOx) ...

AI Technical Summary

Problems solved by technology

However, the emission of nitrogen oxides from diesel engines is relatively high, which is very harmful to the environment and the human body. In addition to adopting advanced internal measures to reduce the emission of nitrogen oxides, it is necessary to take out-of-machine post-treatment measures for the nitrogen oxides discharged from diesel engines. technology to meet the stricter emission regulations in the future

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