Method and apparatus for estimating the amount of reductant slip in a selective catalytic reduction device

A selective, equipment technology, applied in measurement devices, chemical instruments and methods, mechanical equipment, etc., which can solve problems such as loss of correlation, lack of ammonia detection, etc.

Inactive Publication Date: 2015-03-11
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Correlation between NOx output readings from feedstock and downstream NOx sensors would be lost, which could lead to missing ammonia detection

Method used

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  • Method and apparatus for estimating the amount of reductant slip in a selective catalytic reduction device
  • Method and apparatus for estimating the amount of reductant slip in a selective catalytic reduction device
  • Method and apparatus for estimating the amount of reductant slip in a selective catalytic reduction device

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Embodiment Construction

[0016] SCR devices can be used in a variety of different applications where reduction of NOx levels in a gas stream is required. Such applications may include, but are not limited to, boilers, gas turbines, and internal combustion engines, eg, diesel engines.

[0017] figure 1 An internal combustion engine 10 is shown with an SCR device 20 on the exhaust port of the internal combustion engine 10 . The SCR device 20 in this arrangement may be dosed by injecting urea into the exhaust upstream of the SCR device 20 via the injector 40, but any other suitable dosing agent may also be used, such as anhydrous or aqueous ammonia, and may Added to the SCR device 20 by using any suitable technique known to those skilled in the art.

[0018] A first (or upstream) NOx sensor 42 may be located upstream of the SCR device 20 to generate an indication of the NOx input to the SCR device 20 (NOx in )signal of. A second (or downstream) NOx sensor 44 may be located downstream of the SCR devic...

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Abstract

Disclosed is a method and apparatus for estimating the amount of ammonia output from a Selective Catalytic Reduction (SCR) device 20 located in the exhaust system of a vehicle powered by an internal combustion engine. A NOx sensor 44 is located downstream of the SCR to monitor the output of the SCR device and provide data for controlling the dosage of a reductant supplied to the SCR. The NOx sensor is sensitive to NOx which may be output from the SCR when it is under-dosed but is also sensitive to ammonia which may be present when the SCR is over-dosed. Consequently the signal from the NOx sensor is a combination of the NOx and / or ammonia levels in the exhaust. The method and apparatus for estimating the amount of ammonia output from the SCR determine a NOx conversion efficiency of the SCR using a variance of a NOx input measurement from a NOx sensor 42 located upstream of the SCR and a variance of a NOx output measurement from the NOx sensor 44 located downstream of the SCR. An estimate of the actual NOx output from the SCR is then determined using the measured NOx input value and the NOx conversion efficiency of the SCR. The resulting estimate of NOx output is used in conjunction with the measured NOx output to determine the ammonia output by subtracting the estimated NOx output from the measured NOx output to provide an estimate of the ammonia output.

Description

technical field [0001] The present invention relates to methods and devices for leak detection of selective catalytic reduction (SCR) equipment. Background technique [0002] Selective catalytic reduction (SCR) devices can be used to convert nitrogen oxides (NOx), for example, which may be produced by internal combustion engines, into less harmful emissions such as nitrogen and water. The SCR device may include a catalyst to promote a reaction between NOx that may be present in the gas stream passing through the SCR device, and a reductant for substantially removing the NOx from the gas stream. [0003] A reductant may be added to the gas stream and absorbed by the catalyst before reacting with NOx in the gas stream passing through the SCR device. When ammonia is used as a reducing agent, it can be thermally decomposed into ammonia in the SCR device and added to the gas stream, for example in the form of anhydrous ammonia, ammonia water or urea, before being absorbed by the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F01N3/20
CPCF01N9/00F01N2550/05Y02T10/24Y02T10/47F01N2900/1616F01N2900/1402F01N3/208F01N2560/026F01N2610/02Y10T436/175383G01N33/0004Y02A50/20Y02T10/12Y02T10/40F01N11/00B01D53/346B01D53/56B01D53/8625B01D2251/2062B01D2257/404
Inventor G·威廉姆斯M·尼乔尔森S·史密斯
Owner PERKINS ENGINES
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