JP2007187078A - Exhaust gas treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas treatment device for removing nitrogen oxide in low-temperature exhaust gas from a large diesel engine at a high NOx removal efficiency. <P>SOLUTION: A blow-in pipe 4 is inserted into an exhaust gas pipe 3 for exhaust gas 2 from the large diesel engine 1 in the radial direction so that its end is protruded therefrom, and a heater 5 is installed in a portion of the blow-in pipe 4 outside the exhaust gas pipe 3. A hydrocarbon compound 6 and a nitrogen compound 7 heated in the blow-in pipe 4 by the heater 5 are supplied through a blow-out portion 11 formed at the end of the blow-in pipe 4 into the exhaust gas pipe 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust gas treatment device for an engine, and more particularly to an exhaust gas treatment device that removes nitrogen oxides contained in exhaust gas discharged from a large diesel engine or the like used for ships or power generation.

  In recent years, the reduction of nitrogen oxides and particulate matter contained in exhaust gas discharged from automobile diesel engines such as buses and trucks has become a problem. About large diesel engines used for ships and power generation There are similar problems.

  However, unlike automobile diesel engines, large diesel engines, etc. use fuels with a high sulfur content, such as A heavy oil and C heavy oil, so the exhaust gas contains a lot of sulfur oxides, nitrogen oxides and It was an obstacle in the removal process of particulate matter.

  Here, it is known that a denitration method for removing nitrogen oxides from exhaust gas generally includes a selective reduction catalyst method (SCR method) and a non-catalytic denitration method. Of these, the SCR method has the disadvantages that the equipment and operating costs are high, and the catalyst is poisoned by the sulfur content in the exhaust gas, resulting in a decrease in activity. It is said that it is unsuitable to apply to.

  However, when the non-catalytic denitration method is applied to a large diesel engine or the like, the temperature of the exhaust gas is as low as 250 to 450 ° C., and amine radicals are not easily generated.

In order to solve such a problem, Patent Document 1 discloses that a heating region by a burner is formed in a room communicating with an exhaust gas pipe through which exhaust gas passes, and hydrocarbons and nitrogen compounds are separately blown into the heating region. Describes a technique for denitrating exhaust gas by generating amine radicals.
JP 2005-254093 A

  However, in the technique described in Patent Document 1, since normal temperature hydrocarbons and nitrogen compounds are separately blown into the flame tip of the burner, it is difficult to maintain the reaction temperature at a high temperature, and the generation of amine radicals is insufficient. Therefore, there is a problem that it is difficult to improve the denitration rate.

  The present invention has been made in view of such problems, and provides an exhaust gas treatment apparatus capable of removing nitrogen oxides in low-temperature exhaust gas discharged from a large diesel engine or the like with a high denitration rate. It is for the purpose.

  In order to achieve the above object, the present invention according to claim 1 is directed to a blow pipe inserted from a radial direction so that an end protrudes into an exhaust gas pipe of exhaust gas, and a portion of the blow pipe outside the exhaust pipe. The exhaust gas by supplying a hydrocarbon compound and a nitrogen compound heated in the blowing pipe by the heater into the exhaust pipe through a blowing portion formed at an end of the blowing pipe. The exhaust gas treatment apparatus is characterized by reductively removing nitrogen oxides therein.

  According to the invention configured as described above, since the hydrocarbon compound and the nitrogen compound can be reacted with the exhaust gas at a high temperature, the nitrogen oxide in the low temperature exhaust gas can be removed with a high denitration rate.

  Further, the present invention according to claim 2 is a temperature measuring means installed in the vicinity of the blowing portion, a flow rate controlling means for adjusting flow rates of the hydrocarbon compound and the nitrogen compound to the blowing pipe, and the temperature Control means for forming a signal for operating the flow rate control means with the detection signal of the measurement means as an input, and the control means detects the flow rate when the temperature measurement means detects a temperature below a predetermined value. The exhaust gas treatment apparatus according to claim 1, wherein the flow rate of the hydrocarbon compound is increased and the flow rate of the nitrogen compound is decreased by operating a control means.

  According to the invention thus configured, the hydrocarbon compound supplied into the exhaust gas pipe can be prevented from disappearing due to spontaneous ignition in contact with oxygen in the exhaust gas. Can continue.

  Moreover, about this invention which concerns on Claim 2, an ignition means may be provided in the vicinity of the said blowing part, and you may make it operate | move simultaneously by the said control apparatus.

  In addition, it is desirable that the blow-out portion is composed of a plurality of through holes formed in the side surface of the blow-in pipe upstream of the exhaust gas pipe.

  The hydrocarbon compound blown into the exhaust gas pipe is desirably at least one of n-hexane, cyclohexane, n-butane, propane, ethane, and methane aliphatic hydrocarbons.

  In the present invention, it comprises a blow pipe inserted from the radial direction so that the end protrudes into the exhaust gas pipe of the exhaust gas, and a heater installed in a portion outside the exhaust pipe of the blow pipe, Removing nitrogen oxides in the exhaust gas reductively by supplying the hydrocarbon compound and nitrogen compound heated in the injection tube into the exhaust gas pipe through a blow-off portion formed at an end of the injection tube; An exhaust gas treatment apparatus characterized by the above was constructed.

  With such a configuration, nitrogen oxides in low-temperature exhaust gas discharged from a large diesel engine or the like can be removed with a high denitration rate.

  In addition, the exhaust gas treatment apparatus is provided with a control device that can adjust the flow rates of the hydrocarbon compound and the nitrogen compound based on the temperature of the blow-out unit and operate the ignition source installed near the blow-out unit.

  With such a configuration, the denitration reaction can be continued stably, and the denitration rate can be further improved.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a first embodiment of an exhaust gas treatment apparatus according to the present invention.

  The exhaust gas apparatus includes a blow pipe 4 inserted from a radial direction so that an end portion protrudes into an exhaust pipe 3 through which exhaust gas 2 from a large diesel engine 1 flows, and a portion of the blow pipe 4 outside the exhaust pipe 3. It is mainly comprised from the heater 5 installed so that it might enclose.

  The blow-in pipe 4 is for supplying the hydrocarbon compound 6 and the nitrogen compound 7 into the exhaust gas 2 flowing in the exhaust gas pipe 3, and the blow-out for blowing out the hydrocarbon compound 6 and the nitrogen compound 7 at the end thereof. A part 8 is provided. From the viewpoint of promoting the reaction with the exhaust gas 2, it is desirable that the blowout portion 8 includes a plurality of through holes formed in the side surface on the upstream side of the exhaust gas pipe 3.

  In addition, there is no restriction | limiting in particular about the magnitude | size and arrangement | positioning of these through-holes, as long as the objective of this invention is achieved.

  Further, it is preferable that the insertion depth X of the blowing pipe 4 can be arbitrarily adjusted within a range of 0 to 70% with respect to the inner diameter of the exhaust gas pipe 3 from the viewpoint of efficiently treating the exhaust gas 2 in the exhaust gas pipe 3.

  Here, the insertion depth X is defined by the distance between the radial center line of the exhaust gas pipe 3 and the center position in the length direction of the insertion part of the blowing pipe 4.

  The hydrocarbon compound 6 needs to be a compound having 5 or more carbon atoms, such as pentane or hexane. Further, the ignition point is preferably in the range of 300 to 700 ° C, more preferably 400 to 500 ° C. Here, the ignition point means that specified in DIN-51794.

  In order to adjust the concentration of the hydrocarbon compound 6, nitrogen 9 or water vapor 10 may flow through the blowing pipe 4.

  The nitrogen compound 7 needs to generate an amine radical. For example, urea, cyanuric acid, amines, nitriles and the like can be used in addition to ammonia shown in the figure.

  The heater 5 is for heating the hydrocarbon compound 6 and the nitrogen compound 7 flowing in the blowing pipe 4 to raise the temperature, and is installed so as to surround the vicinity of the outside of the insertion portion of the blowing pipe 4. The heater 5 can be an electric heater or a heat exchanger.

  Of course, a plurality of such exhaust gas treatment apparatuses may be installed for one exhaust gas pipe 3.

Next, the effect | action in 1st Embodiment of an waste gas processing apparatus is demonstrated below.
When the hydrocarbon compound 6 and the nitrogen compound 7 brought to a high temperature state (for example, 700 ° C. or higher) by the heater 5 are supplied into the exhaust gas 2 from the blowing portion 8 of the blowing pipe 4, the hydrocarbon compound 6 is first in the exhaust gas 2 In contact with the oxygen, it spontaneously ignites to produce a flame (hereinafter referred to as “radical flame”) 11, so that a hydroxy radical is generated at a high temperature. Then, this hydroxy radical acts on the nitrogen compound 7 to generate an amine radical which is a reducing gas. By this amine radical, nitrogen oxides (NOx: a mixture of nitrogen monoxide and nitrogen dioxide) in the exhaust gas 3 are reduced and decomposed into nitrogen 12, whereby the exhaust gas 2 is denitrated.

  The concentration of the hydrocarbon compound 6 at this time is 0.01 to 5.0% by volume, preferably 0.05 to 1.0% by volume with respect to the exhaust gas 2. Further, the concentration of the nitrogen compound 7 is 0.01 to 5.0% by volume, preferably 0.05 to 1.0% by volume with respect to the exhaust gas 2.

  FIG. 2 shows a second embodiment of the exhaust gas treatment apparatus according to the present invention. In FIG. 2, the same parts as those in FIG.

  In the first embodiment, when the flow rate of the exhaust gas 2 in the exhaust gas pipe 3 fluctuates, the radicalization flame 11 may disappear and the denitration reaction may stop.

  In the present embodiment, for the purpose of maintaining the radicalization flame 11, a thermocouple 20 as a temperature measuring means and an ignition source 21 as an ignition means are provided in the vicinity of the blowing portion 8 of the blowing pipe 4 in the first embodiment. In addition to the arrangement, a flow rate controller 22 as a flow rate control means is provided in a flow path connected to the blowing pipe 4, and a control device 23 for operating or operating them according to a signal from the thermocouple 20 is added.

The ignition source 21 can be omitted.
The flow rate control means 22 includes a plurality of flow rate adjustment valves 24 provided in the respective flow paths of the hydrocarbon compound 6 and the nitrogen compound 7 and adjusts the flow rate of each substance in accordance with a signal from the control device 23. Be able to.

  As the ignition source 21, an electric heating coil, a spark plug, a piezoelectric element type igniter, or the like can be used.

  The operation of the second embodiment will be described below with reference to FIGS. FIG. 3 shows an example of a sequence of the control device. In addition, description about the same part as 1st Embodiment is abbreviate | omitted.

  When the flow rate of the exhaust gas 2 in the exhaust gas pipe 3 fluctuates and the radicalization flame 11 is likely to disappear, and the temperature around the blowing part 8 becomes lower than a predetermined temperature (for example, 500 ° C.), the thermocouple The control device 23 that receives the signal 25 from 20 generates a signal 26 for operating each flow rate adjusting valve 24 in the flow rate controller 22. Thereby, the flow rate of hydrocarbon compound 6 is increased to promote the occurrence of spontaneous ignition, and the flow rate of nitrogen compound 7 is decreased or stopped to prevent consumption. Further, when nitrogen 9 and water vapor 10 are flowed for adjusting the concentration of the hydrocarbon compound 6, the respective flow rates are reduced or stopped in order to increase the concentration of the hydrocarbon compound 6.

In this way, the denitration reaction can be continued stably.
Further, by operating the ignition source 21 together with the above temperature decrease, the radicalization flame 11 can be forcibly generated when the radicalization flame 11 has disappeared, so that the denitration reaction is reliably continued. Can be made.

  In addition, you may provide separately the preset temperature for operating this ignition source 21 in the value below 300 degreeC which is the spontaneous ignition temperature of the hydrocarbon compound 6, for example.

1 is a configuration diagram of a first embodiment of an exhaust gas treatment apparatus according to the present invention. It is a block diagram of 2nd Embodiment of the waste gas processing apparatus which concerns on this invention. It is an example of the sequence which shows operation | movement of a control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diesel engine 2 Exhaust gas 3 Exhaust gas pipe 4 Blowing pipe 5 Heater 6 Hydrocarbon compound 7 Nitrogen compound 8 Blowing part 9 Nitrogen 10 Steam 11 Radicalization flame 12 Gas after denitration 20 Thermocouple 21 Ignition source 22 Flow rate regulator 23 Control device 24 Flow control valve 25 Thermocouple detection signal 26 Flow controller operation signal 27 Ignition source operation signal

Claims (5)

A blow pipe inserted from the radial direction so that the end protrudes into the exhaust gas pipe of the exhaust gas;
It consists of a heater installed in a portion outside the exhaust pipe of the blowing pipe,
By supplying hydrocarbon compounds and nitrogen compounds heated in the blowing pipe by the heater into the exhaust pipe through a blowing portion formed at an end of the blowing pipe, nitrogen oxides in the exhaust gas are reductively reduced. An exhaust gas treatment device characterized by being removed. Temperature measuring means installed in the vicinity of the blowing section;
Flow rate control means for adjusting the flow rate of the hydrocarbon compound and the nitrogen compound into the blowing pipe;
A control means for forming a signal for operating the flow rate control means with the detection signal of the temperature measurement means as an input;
When the temperature measuring means detects a temperature below a predetermined value, the control means operates the flow rate control means to increase the flow rate of the hydrocarbon compound and decrease the flow rate of the nitrogen compound. The exhaust gas treatment apparatus according to claim 1. A temperature measuring means and an ignition means installed in the vicinity of the blowing section;
Flow rate control means for adjusting the flow rate of the hydrocarbon compound and the nitrogen compound into the blowing pipe;
A control means for forming a signal for operating the flow rate control means and the ignition means with the detection signal of the temperature measurement means as an input;
When the temperature measuring means detects a temperature below a predetermined value, the control means operates the flow rate control means to increase the flow rate of the hydrocarbon compound and decrease the flow rate of the nitrogen compound, and to ignite the ignition. The exhaust gas treatment apparatus according to claim 1, wherein the means is operated. The exhaust gas treatment apparatus according to any one of claims 1 to 3, wherein the blow-out portion includes a plurality of through holes formed in a side surface of the blow-in pipe upstream of the exhaust gas pipe. The exhaust gas treatment according to any one of claims 1 to 4, wherein the hydrocarbon compound is at least one of n-hexane, cyclohexane, n-butane, propane, ethane, and methane aliphatic hydrocarbons. apparatus.

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