Method and device for evaluating urea crystallization risk based on transient working condition

Abstract

The invention discloses a method for evaluating urea crystallization risk based on a transient working condition. The evaluation method uses two most important coefficients influencing urea crystallization, namely a quality risk coefficient and a temperature risk coefficient; the crystallization risk coefficient eta is calculated according to a quality coefficient eta m and a temperature coefficient eta t, and the average crystallization risk coefficient is obtained by integrating the crystallization risk coefficient eta in the transient working condition duration t and then averaging; the urea crystallization risk coefficient is calculated from the aspects of quality and temperature which have the maximum influence on crystallization; the urea crystallization risk is quantized by using a mathematical method; a threshold value of urea crystallization can be obtained through calibration; a urea decomposition detailed mechanism is fused into a model; a chemical reaction path is expressed in the form of a mathematical equation; the influence of exhaust pipeline arrangement on the urea crystallization risk under the transient working condition is considered; the urea crystallization risk coefficient is not a fixed formula and can be calibrated according to a bench transient test; the reliability is high; and the universality is wide.

Description

technical field [0001] The invention relates to the technical field of SCR crystallization, in particular to a method and a device for evaluating the risk of urea crystallization based on transient working conditions. Background technique [0002] Urea-SCR (Urea-Selective Catalytic Reduction) is the main technical means to reduce NOx emissions of national six diesel locomotives. The urea injection is realized through the control of the electronic control system. The urea is injected into the SCR mixer through the urea nozzle and reacts with the exhaust gas to decompose ammonia gas. [0003] However, at present, during the use of SCR, the risk of urea crystallization is relatively high, which causes problems such as increased fuel consumption of the vehicle and decreased conversion efficiency of post-treatment NOx; urea injection is mainly calibrated based on the relationship between original NOx and tail NOx There are relatively few methods for evaluating the risk of urea c...

AI Technical Summary

Problems solved by technology

[0003] However, at present, during the use of SCR, the risk of urea crystallization is relatively high, which causes problems such as increased fuel consumption of the vehicle and decreased conversion efficiency of post-treatment NOx; urea injection is mainly calibrated based on the relationship between original NOx and tail NOx There are relatively few methods to evaluate the risk of urea crystallization after completion, especially for transient conditions

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