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Method for increasing urea pyrolysis hydrolysis efficiency of diesel engine selective catalytic reduction (SCR) system

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

Active Publication Date: 2014-10-01
TONGJI UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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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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  • Method for increasing urea pyrolysis hydrolysis efficiency of diesel engine selective catalytic reduction (SCR) system
  • Method for increasing urea pyrolysis hydrolysis efficiency of diesel engine selective catalytic reduction (SCR) system
  • Method for increasing urea pyrolysis hydrolysis efficiency of diesel engine selective catalytic reduction (SCR) system

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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 3 The 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 dies...

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Abstract

The invention relates to a method for increasing the urea pyrolysis hydrolysis efficiency of a diesel engine selective catalytic reduction (SCR) system. The method includes that a urea solution in a urea solution box is pumped out and a Na2CO3 solution in a Na2CO3 solution box is pumped out to be filtered and conveyed to a urea solution meter respectively, the urea solution meter is controlled by an electronic control unit to meter a certain quantity of a mixed solution of urea and Na2CO3 according to the working condition of a diesel engine, the concentration of added Na2CO3 is controlled within 10-30ppm, and the mixed solution enters a vent pipe through a urea spray nozzle. The urea meets high temperature in a vent pipe mixing area to release NH3 which is above 80% in the urea under the assistant function of the Na2CO3, the released NH3 and NOx which is discharged by the diesel engine are fully mixed to enter an SCR device, and the NH3 and the NOx react to generate N2 and H2O which is then discharged to the atmosphere. According to the method for increasing the urea pyrolysis hydrolysis efficiency of the diesel engine SCR system, a small amount of Na2CO3 is added to the urea solution, the hydrolysis rate that an intermediate product HNCO of urea pyrolysis generates the NH3 is greatly increased, the NH3 in the urea can be rapidly and efficiently released, the NOx purification efficiency curve is remarkably extended towards a low-temperature direction, the NOx purification efficiency is remarkably improved, and the purifying effect of discharged diesel engine tail gas NOx is remarkably improved.

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 (Selective Catalytic Reduction) (referred to as NH 3 —SCR technolog...

Claims

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Application Information

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