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A method for improving the efficiency of urea pyrolysis and hydrolysis in scr system of diesel engine

A diesel engine and urea technology, applied in mechanical equipment, engine components, combustion engines, etc., can solve problems such as unfavorable NOx purification and shortening time, and achieve the effect of improving purification effect and good urea pyrolysis and hydrolysis efficiency.

Active Publication Date: 2016-04-06
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Then, this part of NH released by HNCO 3 , in order to carry out the reduction reaction with NOx, resulting in this part of NH 3 The time that NOx can be used for chemical reaction is shortened, which is not conducive to the purification of NOx

Method used

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  • A method for improving the efficiency of urea pyrolysis and hydrolysis in scr system of diesel engine
  • A method for improving the efficiency of urea pyrolysis and hydrolysis in scr system of diesel engine
  • A method for improving the efficiency of urea pyrolysis and hydrolysis in scr system of diesel engine

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Experimental program
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Effect test

Embodiment 1

[0027] Embodiment 1: urea solution adds a small amount of Na 2 CO 3 solution, to improve the efficiency of urea pyrolysis and hydrolysis

[0028] Press the following parts to figure 1 Connect as shown. Such as figure 1 The shown device consists of urea solution tank 1, urea pump 2, urea solution meter 3, electronic control unit 4, diesel engine 5, exhaust pipe 6, urea nozzle 7, SCR selective catalytic reduction device 8, Na 2 CO 3 The solution tank 9, the solution pump 10 and related pipelines are composed.

[0029] The NH 3 —When the SCR technology device is working, the urea solution in the urea solution tank 1 is pumped out, filtered under the pressure of 150kPa~300kPa and sent to the urea solution meter 3, Na 2 CO 3 Na in solution box 9 2 CO 3The solution is pumped out, filtered under the pressure of 150kPa~300kPa and sent to the urea solution meter 3, the electronic control unit 4 controls the urea solution meter 3 to measure a certain amount of urea a...

Embodiment 2

[0030] Embodiment 2: urea solution adds a small amount of Na 2 CO 3 Evaluation of NOx purification efficiency after solution

[0031] An electronically controlled high-pressure common rail direct injection diesel engine was used as a prototype, and Na 2 CO 3 Auxiliary NH 3 ——SCR method to evaluate the purification efficiency of NOx, using Na-free 2 CO 3 Auxiliary NH 3 -SCR method as a comparison. The diesel engine was bench mounted for steady state operation to provide reproducible and stable NOx emissions. The rotational speed of the engine is controlled to be 2000r / min, and the load ratios are respectively 25%, 50%, 75%, and 100%, so as to provide a series of SCR selective catalytic reduction device 8 inlet temperatures (the temperatures are respectively 255 o C. 318 oC 、372 oC 、451 oC ) and NOx concentrations (concentrations are 226ppm, 498ppm, 856ppm, 989ppm, respectively). Use a special AVL exhaust gas analyzer to measure the NOx emissions of diesel ...

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Abstract

The invention relates to a method for improving the efficiency of pyrolysis and hydrolysis of urea in an SCR system of a diesel engine. Specifically: the urea solution in the urea solution tank is pumped out, the Na2CO3 solution in the Na2CO3 solution tank is pumped out, filtered and sent to the urea solution meter respectively, and the electronic control unit controls the urea solution meter to measure a certain amount according to the working conditions of the diesel engine. The mixed solution of urea and Na2CO3, the concentration of Na2CO3 added is controlled to be 10~30ppm, and the mixed solution enters the exhaust pipe through the urea nozzle. When urea encounters high temperature in the mixing area of ​​the exhaust pipe, with the assistance of Na2CO3, more than 80% of NH3 in urea is released, which is fully mixed with NOx discharged from the diesel engine and then enters the SCR selective catalytic reduction device, where NH3 and NOx react to form N2 and H2O, vented into the atmosphere. In the present invention, a small amount of Na2CO3 is added to the urea solution, which greatly increases the hydrolysis rate of NH3 generated from HNCO, an intermediate product of pyrolysis of urea, which is conducive to the rapid and efficient release of NH3 in urea, so that the NOx purification efficiency curve is significantly extended to the low temperature direction, and the NOx purification efficiency Can be obviously improved, significantly improved the purification effect of diesel engine tail gas NOx emission.

Description

technical field [0001] The invention belongs to the technical field of post-treatment of diesel engine exhaust, in particular to a 2 CO 3 ) to assist in improving the efficiency of urea pyrolysis and hydrolysis in a diesel engine SCR system. 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 emission of nitrogen oxides (NOx) from diesel engines is relatively high, which is very harmful to the environment and human body. In addition to adopting advanced internal measures to reduce NOx emissions, it is necessary to take out-of-machine post-treatment and purification measures for the NOx emitted by diesel engines. technology in order to meet the more stringent emission regulations in the future. [0003] Ammonia (NH 3 ) Selective catalytic reduction technology SCR (SelectiveCatalyticReduction) (referred to as NH 3 —SCR technology)...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): F01N3/20F01N3/28F01N9/00
CPCY02T10/12Y02T10/40
Inventor 谭丕强胡志远楼狄明
Owner TONGJI UNIV