It is preference in the Japanese patent application JP2004-26074 and the JP2004-35448 on February 2nd, 2004 and February 12 that the application requires with SEPARATE APPLICATION, and they in this combination as a reference.
Background technique
In recent years, because for example existence of the environmental pollution problem of acid rain and photochemical smog etc., for contained particulate matter (PM) and nitrogen oxide (NO in the waste gas of discharging by the internal-combustion engine of for example diesel engine
X), press for its removing.
Therefore, there is a kind of traditional technology, in the vent systems of internal-combustion engine, the reducing agent or the supply nozzle of reducing agent precursor by reducing agent etc. of urea water for example, be supplied to waste gas from the upstream of the SCR silencing apparatus of SCR (selective catalytic reduction effect) catalyzer through injection with selective reduction, thereby by contained nitrogen oxide (NO in reduction of SCR catalyst selectivity ground and the scavenging
X).For example, referring to Japanese Patent Application Publication 2001-20724.
In addition, also have a kind of system, wherein, for example the pore of punching hole is formed in the outlet pipe, disperses exhaust flow and makes it even.For example, referring to the open H02-115912 of Japanese utility model application.
Yet, adopt this conventional art, there is a problem, that is, because the exhaust flow outofkilter is removed nitrogen oxide (NO when short-term operation
X) efficient very low, and all very low to the gamut internal efficiency of high temperature at low temperature.
Particularly, with urea water as under the situation of reducing agent precursor, also have a problem, that is, because the exhaust flow outofkilter, urea is deposited in the outlet pipe that is arranged in SCR catalyzer upstream etc., removes nitrogen oxide (NO thereby reduce greatly
X) efficient.
In addition, with traditional technology, there is a problem, promptly, because the supply nozzle of reducing agent etc. is subjected to the influence of vibration of vehicle, waste gas and similar vibration member, be difficult to by spray with reducing agent or for example the reducing agent precursor of urea water be supplied to waste gas in homodisperse mode, SCR catalyzer removing nitrogen oxide (NO like this
X) efficient very low.
Also have a problem in addition, that is, owing to the vibration that the vibration by vehicle, waste gas and analog causes, it is very low that the supply nozzle of reducing agent etc. faces danger and the serviceability destroying and be out of shape.
Embodiment
Below with reference to the accompanying drawings the best mode that is used for implementing SCR silencing apparatus of the present invention is described.
First embodiment
Fig. 1 is the basic schematic representation according to the SCR silencing apparatus of first embodiment of the invention, it comprise be used for optionally reducing and scavenging in contained nitrogen oxide (NO
X) SCR catalyzer 1, the supplier 3 that allows waste gas to flow into the outlet pipe 2 of SCR catalyzer 1 and reducing agent or reducing agent precursor are supplied to the reducing agent etc. of waste gas, and it also has a plate 4 in the downstream of the supplier 3 of reducing agent etc. and the upstream of SCR catalyzer 1, and this plate 4 has the exhaust flow of dispersion and makes its uniform pore 5.Though Fig. 1 demonstrates the inside that outlet pipe 2 is inserted in silencing apparatus, this outlet pipe 2 and silencing apparatus also can form and replace outlet pipe 2 is inserted in the silencing apparatus.In addition, no matter no matter serial type or parallel connection type, shape are that circle or tube are all unimportant.
As shown in Figure 1, this embodiment describes the plate 4 that exhaust pipe 2 and silencing apparatus had pore 5 together and closes, but the present invention is not limited in this structure.That is to say that the plate 4 with pore 5 can be arranged on the lower exit end near the outlet pipe 2 of SCR catalyzer 1, perhaps can be arranged on a position in the outlet pipe 2, as long as this position is positioned at the downstream of supplier 3 of reducing agent etc. and the upstream of SCR catalyzer 1.Alternatively, it can be arranged in the silencing apparatus itself but not in the outlet pipe 2.
As shown in Figure 2, wherein outlet pipe 2 inside and its insertion position that are inserted in silencing apparatus has pore, and the present invention can have a kind of structure, wherein has only outlet pipe 2 to be closed by imperforate plate 4.
In having the SCR silencing apparatus of this structure, waste gas passes outlet pipe 2 and flows into SCR catalyzer 1. waste gas along the direction that is from upstream to the downstream and discharges from the internal-combustion engine of for example diesel engine and comprise the hydrocarbon (HC), carbon monoxide (CO) and for example nitrous oxide (NO) that do not fire and the nitrogen oxide (NO of nitrogen dioxide (NO2)
X) toxic substance that waits.
The time durations of this waste gas before flowing into SCR catalyzer 1, the supplier 3 of the reducing agent by having reducing agent or reducing agent precursor etc. is supplied to.This reducing agent or reducing agent precursor comprise the reducing agent precursor of the material that for example discharges reducing agent, and reducing agent itself, and can be hydrocarbon, cyanurate (cyanurate), ammoniacal liquor, ammonium carbonate, aminoquinoxaline, urea and their compound.In addition, reducing agent or reducing agent precursor can be any forms in solid, the liquids and gases.
For example, the supplier 3 of reducing agent etc. can be supplied with ammoniacal liquor itself as reducing agent, but the ammoniacal liquor smell is strong and toxicity is big under high relatively concentration.Therefore, hypotoxic urea water is more suitable for supplying with through spraying as the reducing agent precursor.In this case, the waste gas in the urea in the urea water and the outlet pipe mixes and contact, and discharges ammoniacal liquor--a kind of reducing agent through heating or hydrolysis decomposition.In the present embodiment, urea water by means of additional nozzle from the waste gas of outside in injection is supplied to outlet pipe of outlet pipe.
After this, waste gas continues along the downstream direction outlet pipe of flowing through, and arrives the plate with pore 54 of SCR catalyzer 1 upstream.
Fig. 3 is the sectional view according to the plate with pore 54 of first embodiment of the invention.Pore-free 5 is arranged on the central part of closing outlet pipe 2, and a plurality of circular pore 5 only is arranged on the exterior lateral area of diameter greater than the exhaust pipe mouth zone, is provided with in staggered mode, thereby forms concentric circle.
But pore 5 shapes of the present invention are in circle, ellipse, strip, fan-shaped and other polygonal any, but more preferably similar punching hole.Pore 5 can be the combination in these shape holes.The size of pore 5 and quantity can be arbitrarily.In addition, pore 5 preferably is provided with symmetrically, and preferably only is arranged in the zone of diameter greater than outlet pipe.
In addition, but plate of the present invention 4 shapes are in circle, ellipse, square, taper and other polygonal any, and can be plane, convex surface or other shape.In addition, the arbitrary shape of semicircle for example or triangular pyramid can be adopted in the protruding cross section of rased panel, and its direction direction towards downstream, but preferably towards party upstream to.Preferably, plate 4 has the size of the opening that can close outlet pipe 2 and silencing apparatus, and as mentioned above diameter greater than the diameter of outlet pipe 2.Can there be a plate 4 or polylith plate 4.
Like this, in the present embodiment, because outlet pipe 2 cuts out by the central part that the pore-free 5 of plate 4 is arranged on wherein fully, the waste gas of flowing through outlet pipe and arriving plate 4 can not directly pass plate 4 and be blocked on the plate surface.Therefore, waste gas passes outlet pipe 2 and is inserted in pore in the part in the silencing apparatus, and flows out outlet pipe, and the space between silencing apparatus and the outlet pipe 2 of flowing through then arrives plate 4 once more.
After this, the waste gas that has flowed out outlet pipe passes the pore 5 in plate 4 exterior lateral area, flows into the SCR catalyzer 1 in its downstream, wherein contained nitrogen oxide (NO in the waste gas
X) be absorbed in the SCR catalyzer 1.
This SCR (selective catalytic reduction effect) catalyzer 1 can be made by in titanium dioxide (TiO2), vanadic anhydride (V2O5), tungstic acid (WO3), molybdenum trioxide (MoO3), silica (SiO2), sulphate, zeolite etc. and the compound thereof any.In addition, SCR catalyzer 1 can be had the catalyst bracket splendid attire or the supporting of cellular structure.
This SCR catalyzer 1 optionally reduce and scavenging in contained nitrogen oxide (NO
X) and be translated into the nitrogen and the water of environmental sound.Remove nitrogen oxide (NO
X) efficient be subjected to flowing into the influence of the exhaust flow in the SCR catalyzer 1.
Fig. 4 has shown the exhaust flow in the SCR catalyzer 1 that flows into first embodiment.Fig. 4 (a) has shown the exhaust flow under the situation that is provided with the flat board 4 with pore 5, and Fig. 4 (b) has shown the exhaust flow under the situation that is provided with the rased panel 4 with pore 5.
As shown in Figure 4, outlet pipe 2 cuts out by the central part of the pore-free 5 of plate 4, and therefore, waste gas can not directly pass plate 4.Waste gas passes pore, the outflow outlet pipe in the outlet pipe 2, passes pore 5, inflow SCR catalyzer 1. in plate 4 exterior lateral area then
At this moment, the pore 5 in the plate 4 disperses and makes exhaust flow even, thereby makes the exhaust flow that flows into SCR catalyzer 1 be in good state.Notice that a bit under the situation of Fig. 4 (b), exhaust flow is because the resistance of convex surface and than more disperseing under the situation among Fig. 4 (a) and becoming more even.
Fig. 5 has shown the exhaust flow under the situation of having only outlet pipe 2 to be closed by pore-free plate 4 as shown in Figure 2.
In this case similarly, owing to stopping of the imperforate central part that is subjected to plate 4, the pore that waste gas passes in the exhaust port 2 flows out outlet pipe, but owing to the space between silencing apparatus and the outlet pipe 2 is not closed by plate 4, so waste gas does not have any SCR catalyzer 1 that flows into intrusively.Therefore, though exhaust flow is not disperseed and homogenization by the pore of as shown in Figure 4 plate, the exhaust flow that flows into SCR catalyzer 1 still is in good state with respect to the situation that does not have plate 4.
Be in as above kilter if flow into the exhaust flow of SCR catalyzer 1, then contained nitrogen oxide (NO in the waste gas
X) be absorbed into the speed increase in the SCR catalyzer 1, remove nitrogen oxide (NO thereby improve
X) efficient.
Second embodiment
Next second embodiment of the present invention will be described, wherein identical reference character represent with first embodiment in same or analogous parts, and different or newly-increased parts are represented by new reference character.
Fig. 6 is the basic schematic representation according to the SCR silencing apparatus of second embodiment of the invention.This SCR silencing apparatus comprises and is used for optionally reducing and the contained nitrogen oxide (NO of scavenging
X) SCR catalyzer 1, the supply nozzle 30 that allows waste gas to flow into the outlet pipe 2 of SCR catalyzer 1 and reducing agent or reducing agent precursor are supplied to the reducing agent etc. of waste gas, the supply nozzle 30 of this reducing agent etc. interts by remaining on the plate with pore 5 40 in the outlet pipe 2.
Fig. 6 (a) has shown a kind of SCR silencing apparatus, wherein the supply nozzle 30 of reducing agent etc. interts in its end that (shape is as R or lug boss by having curved part, or plane) plate 40, and plate 40 remains in the outlet pipe 2 by the inside that curved part is fixed to outlet pipe 2.Simultaneously, Fig. 6 (b) has shown a kind of SCR silencing apparatus, and wherein the supply nozzle 30 of reducing agent etc. interts by conical plate 40 in its end, and by being clipped in the curved part on the bottom between the flange and being fixed, plate 40 remains in the outlet pipe 2.
In having the SCR silencing apparatus of this structure, waste gas passes outlet pipe 2 and flows into SCR catalyzer 1 along the direction that is from upstream to the downstream.The flow through time durations of waste gas before flowing into SCR catalyzer 1 of SCR silencing apparatus, the supplier 30 of the reducing agent by having reducing agent or reducing agent precursor etc. is supplied to.
In the present invention, the plate 40 that the supply nozzle 30 of reducing agent etc. interts by having pore 5, and this plate 40 remains in the outlet pipe 2.Therefore, the vibration that causes owing to the vibration that is subjected to by vehicle, waste gas and analog of the supply nozzle 30 of reducing agent etc. is inhibited or reduces.Consequently, reducing agent or for example the reducing agent precursor of urea water so that its homodisperse mode is supplied to waste gas through injection.In addition, the supply nozzle 30 of reducing agent etc. has improved serviceability owing to being reinforced by plate 40.
Fig. 7 is the projection drawing of outlet pipe inside when observing along the direction that is from upstream to the downstream of SCR silencing apparatus according to a second embodiment of the present invention.The pore 5 that waste gas passes plate 40 flows along the direction that is from upstream to the downstream.In addition, the supply nozzle of reducing agent etc. 30 interts by the central parts of plate 40, and reducing agent or for example the reducing agent precursor of urea water be supplied to by spraying along the direction that is from upstream to the downstream, and so that its homodisperse mode with the waste gas mixing with contact.
Plate 40 of the present invention can form any in circle, ellipse, square, taper and other polygonal, and can be plane, convex surface or other shape.Plate 40 preferably has the size of the mouth that can close outlet pipe 2.Can there be a plate 40 or polylith plate 40.
Intert modes by plate 40 for the supply nozzle 30 of reducing agent etc., intert in its end by plate 40 end of the supply nozzle 30 of reducing agent etc., and this plate 40 preferably is fixed in the supply nozzle 30 of reducing agent etc. and is in the outstanding a little state in end of this nozzle.
For the mode that plate 40 is remained in the outlet pipe 2, except other method, this plate 40 can be fixed in the inside of outlet pipe 2, perhaps clamping and being fixed between the outward flange of outlet pipe 2.
Waste gas further flows and flows into SCR catalyzer 1 along downstream direction, wherein contained nitrogen oxide (NO in the waste gas
X) be absorbed in the SCR catalyzer 1 and optionally reduced and remove.Consequently, nitrogen oxide (NO
X) be converted into the nitrogen and the water of environmental sound.
In the present invention, the waste gas that flows into SCR catalyzer 1 and reducing agent or for example the reducing agent precursor of urea water fully mix and contact, thereby contained nitrogen oxide (NO in the waste gas
X) speed that is absorbed in the SCR catalyzer 1 becomes very high.Therefore, SCR catalyzer 1 is removed nitrogen oxide (NO
X) efficient improve.
The present invention can be used as first and second embodiments' combination and implements.In this case, the exhaust flow of the SCR silencing apparatus of flowing through becomes well, and the vibration that causes of the suffered vibration by vehicle, waste gas and analog of supply nozzle of reducing agent etc. is inhibited or reduces.Consequently, the SCR catalyzer is removed nitrogen oxide (NO
X) efficient improve, and the serviceability of the supply nozzle of reducing agent etc. improves.