Reducing agent injection device, exhaust gas treatment device and exhaust gas treatment method

Patent metadata

Field	Value
Publication number	US-2016017777-A1
Application number	US-201514856659-A
Country	US
Kind code	A1
Filing date	Sep 17, 2015
Priority date	Mar 22, 2013
Publication date	Jan 21, 2016
Grant date	—

Abstract

A reducing agent injection device includes a honeycomb structure having a honeycomb structure body and a pair of electrode members arranged in a side surface of the honeycomb structure body and a urea spraying device spraying a urea water solution in mist form. The urea water solution sprayed from the urea spraying device is supplied inside cells from a first end face of the honeycomb structure body, and urea in the urea water solution supplied in the cells is heated and hydrolyzed inside the electrically heated honeycomb structure body to generate ammonia. The ammonia is discharged outside the honeycomb structure body from a second end face and injected outside. There is provided a reducing agent injection device that can generate and inject ammonia from a urea solution with less energy.

First claim

1 . A reducing agent injection device, comprising:
a honeycomb structure that has a honeycomb structure body with a pillar shape having partition walls defining and forming a plurality of cells which are through channels of a fluid and extend from a first end face being an end face on an inflow side of the fluid to a second end face being an end face on an outflow side of the fluid, and that has a pair of electrode members arranged in a side surface of the honeycomb structure body; and a urea spraying device that sprays a urea water solution in mist form, wherein each of the pair of electrode members is formed in a band shape extending to a cell extending direction of the honeycomb structure body, and one electrode member of the pair of electrode members is arranged on an opposite side of the other electrode member of the pair of electrode members with respect to a center of the honeycomb structure body sandwiched by the pair of electrode members, in a cross section perpendicular to the cell extending direction, and the urea water solution sprayed from the urea spraying device is supplied inside the cells from the first end face of the honeycomb structure body, and urea in the urea water solution supplied in the cells is heated and hydrolyzed inside the electrically heated honeycomb structure body to generate ammonia, and the ammonia is discharged outside the honeycomb structure body from the second end face and is injected outside.

2 . The reducing agent injection device according to claim 1 , wherein a urea spraying space is formed between the first end face of the honeycomb structure body and the urea spraying device.

3 . The reducing agent injection device according to claim 1 , wherein an electrical resistivity of the honeycomb structure body is 0.01 Ωcm to 500 Ωcm.

4 . The reducing agent injection device according to claim 1 , wherein the honeycomb structure body contains a silicon-silicon carbide composite material or silicon carbide as a main component.

5 . The reducing agent injection device according to claim 1 , wherein a urea hydrolysis catalyst is loaded onto the honeycomb structure.

6 . The reducing agent injection device according to claim 1 , wherein
the urea water solution is sprayed toward the first end face of the honeycomb structure body from the urea spraying device and an angle between a spraying direction of the urea water solution from the urea spraying device and a direction parallel to the cell extending direction of the honeycomb structure body and heading to the first end face of the honeycomb structure body from the urea spraying device is from 5° to 60°.

7 . The reducing agent injection device according to claim 1 , wherein a surface area per unit volume of the honeycomb structure body is equal to or more than 5 cm 2 /cm 3 .

8 . The reducing agent injection device according to claim 1 , wherein the honeycomb structure body has a plugging portion at an end portion of the first end face side in a part of the cells thereof.

9 . The reducing agent injection device according to claim 1 , wherein the urea spraying is a solenoid type, a piezoelectric actuator type, an ultrasonic type, or an atomizer type.

10 . An exhaust gas treatment device, comprising:
an exhaust pipe that flows an exhaust gas containing NO R ; the reducing agent injection device according to claim 1 that injects ammonia inside the exhaust pipe; and an SCR catalyst arranged on a downstream side of the exhaust pipe with respect to a position where the ammonia is injected.

11 . An exhaust gas treatment method comprising flowing the exhaust gas containing NO x in the exhaust pipe, injecting ammonia in the exhaust gas, and performing a reduction treatment to the exhaust gas mixed with the ammonia by the SCR catalyst, by using the exhaust gas treatment device according to claim 10 .

12 . The exhaust gas treatment method according to claim 11 , wherein temperature of the honeycomb structure is equal to or more than 160° C.

13 . The exhaust gas treatment method according to claim 11 , comprising intermittently performing, under temperature of the honeycomb structure equal to or more than 360° C., a reducing agent injection device cleaning operation which removes a sulfur compound adhered to the reducing agent injection device.

14 . The exhaust gas treatment method according to claim 11 , calculating temperature of the honeycomb structure body from a resistance value of the honeycomb structure body, and controlling the temperature of the honeycomb structure body such that the calculated temperature becomes desired temperature.

15 . The reducing agent injection device according to claim 2 , wherein an electrical resistivity of the honeycomb structure body is 0.01 Ωcm to 500 Ωcm.

16 . The reducing agent injection device according to claim 15 , wherein the honeycomb structure body contains a silicon-silicon carbide composite material or silicon carbide as a main component.

17 . The reducing agent injection device according to claim 16 , wherein a urea hydrolysis catalyst is loaded onto the honeycomb structure.

18 . The reducing agent injection device according to claim 17 , wherein
the urea water solution is sprayed toward the first end face of the honeycomb structure from the urea spraying device and an angle between a spraying direction of the urea water solution from the urea spraying device and a direction parallel to the cell extending direction of the honeycomb structure body and heading to the first end face of the honeycomb structure from the urea spraying device is from 5° to 60°.

19 . The reducing agent injection device according to claim 18 , wherein a surface area per unit volume of the honeycomb structure body is equal to or more than 5 cm 2 /cm 3 .

Assignees

• Ngk Insulators Ltd

Inventors

• Kasai Yoshiyuki
• Mase Kazumi
• Katsumi saiki

Classifications

• B01J35/57

  Honeycombs · CPC title

• F01N2330/30

  Honeycomb supports characterised by their structural details · CPC title

• F01N3/0222 Primary

  the structure being monolithic, e.g. honeycombs · CPC title

• F01N3/208 Primary

  Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent · CPC title

• F01N2610/02

  the substance being ammonia or urea · CPC title