EP1990097A2 - Fitre à paroi ayant une résistance de rupture en fluage illimitée - Google Patents

Fitre à paroi ayant une résistance de rupture en fluage illimitée Download PDF

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Publication number
EP1990097A2
EP1990097A2 EP20080450074 EP08450074A EP1990097A2 EP 1990097 A2 EP1990097 A2 EP 1990097A2 EP 20080450074 EP20080450074 EP 20080450074 EP 08450074 A EP08450074 A EP 08450074A EP 1990097 A2 EP1990097 A2 EP 1990097A2
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EP
European Patent Office
Prior art keywords
channels
ceramic body
exhaust gas
voltage pulses
flow
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP20080450074
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German (de)
English (en)
Inventor
Carl Maria Prof. Dr. Fleck
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Individual
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Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP1990097A2 publication Critical patent/EP1990097A2/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/34—Constructional details or accessories or operation thereof
    • B03C3/66—Applications of electricity supply techniques
    • B03C3/68—Control systems therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/34—Constructional details or accessories or operation thereof
    • B03C3/36—Controlling flow of gases or vapour
    • B03C3/368—Controlling flow of gases or vapour by other than static mechanical means, e.g. internal ventilator or recycler
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
    • B03C3/34—Constructional details or accessories or operation thereof
    • B03C3/40—Electrode constructions
    • B03C3/60—Use of special materials other than liquids
    • B03C3/62—Use of special materials other than liquids ceramics
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C2201/00—Details of magnetic or electrostatic separation
    • B03C2201/30—Details of magnetic or electrostatic separation for use in or with vehicles

Definitions

  • the invention relates to a method for operating a filter arrangement for separating soot particles from an exhaust gas flow, in which the exhaust gas flow is passed through passages of the ceramic body extending in the longitudinal direction of a porous ceramic body, according to the preamble of claim 1.
  • the exhaust gas flow passes through pores of the walls of the channels of the ceramic body, which are open only on one side, whereby the soot particles are retained.
  • the deposition of the soot particles thus takes place mechanically.
  • Different systems are known for the degradation of the deposited soot particles in the channels of the ceramic body, for example by means of a plasma generated in the channels of the ceramic body ("plasma-generated filter systems").
  • plasma-generated filter systems For this purpose, a voltage is applied to the ceramic body for generating an electric field in the channels of the ceramic body, which is oriented in each case normal to the axis of the channels on parallel to the channels extending electrodes. Electric field strengths of about 1 kV / cm in the channels of the honeycomb body are usually sufficient to generate a plasma in the channels, which converts deposited soot particles into gaseous substances.
  • Claim 1 relates to a method for operating a filter arrangement for separating soot particles from an exhaust gas flow, wherein the exhaust gas flow is passed through extending in the longitudinal direction of a porous ceramic body channels of the ceramic body, wherein the exhaust gas flow through pores of the walls of the only one-sided open channels Passing ceramic body, and applied to parallel to the channels extending electrodes, a voltage to the ceramic body for generating an electric field in the channels of the ceramic body, which is oriented substantially normal to the axis of the channels.
  • the soot particles are charged by means of a further electrode arrangement, and the voltage applied to the electrodes extending parallel to the channels is unipolar voltage pulses.
  • the unipolar voltage pulses are selected so that at a given channel height h in the field direction and given channel length L the Ratio of the generated by the voltage pulses drift velocity c of the charged soot particles in the field direction of the electric field generated in the channels to the flow velocity v of the gas flow in the channels greater than or equal to the ratio of twice the channel height h to the channel length L is.
  • the measures according to the invention therefore provide for the separation of the soot particles in the channels of the ceramic body not exclusively to be mechanical, but to use the electric field built up in the channels for the soot erosion also for the deposition of the soot particles, for which purpose a further electrode arrangement for previous charging of soot particles is provided.
  • this measure alone is not yet sufficient to solve the problem of reduced creep strength described above.
  • According to the invention is therefore also proposed to make the deposition of the soot particles in the wall-flow filter and the subsequent regeneration of the deposited soot through a unipolar plasma field on one wall side, while the second, opposite wall side always remains pure and therefore no clogging of pores, and so that no pressure build-up can take place.
  • the pressure that tends to be higher as a result of the long-term halving of the filter surface must be taken into account when designing the filter size and the channel dimensions.
  • the flow velocity v of the gas flow in the channels and the drift velocity c which depends on the diameter d of the soot particles, can easily be determined.
  • the flow velocity v is measured anyway in the course of the regulation of the filter in order to regulate the applied voltage.
  • the mobility ⁇ (d) and the charge number z (d) can be read for different diameters d from well-known tables.
  • the charge of the soot particles quantified by the charge number z (d) is due to the previous charge by means of the discharge electrode.
  • the field strength E is given in a known manner directly by the applied voltage pulses. On the basis of the features according to the invention, it is thus possible to derive the field strength E necessary in the respective application, and thus the voltage to be applied to the electrodes.
  • the setting according to the invention of the drift velocity c, the flow velocity v, the channel height h and the channel length L will be explained in more detail below.
  • Claim 2 gives a preferred choice for the duration of the unipolar voltage pulses and suggests that the unipolar voltage pulses have a duration below 20 ⁇ s. Particularly advantageous are according to claim 3 unipolar voltage pulses with a duration between 5 ⁇ s and 15 ⁇ s. According to claim 4, the time interval between two unipolar voltage pulses between 50 ⁇ s and 150 ⁇ s.
  • the soot distribution in the channel can be steered, and in particular also kept constant at different gas velocities, by at least temporarily reducing the field amplitude, preferably with short but very high amount of soot, while maintaining the field amplitude in FIG the remaining time directly proportional to the flow velocity in the channel controls.
  • the Fig. 1 and 2 each show a schematic representation of a cross section of a ceramic body 7, which is a honeycomb body.
  • a ceramic body 7 is shown with a convex, namely elliptical circumferential line, but it could also have other cross-sectional shapes, such as a trapezoidal shape.
  • the ceramic body 7 has channels 5, which extend in the longitudinal direction of the ceramic body 7, and are open at one end face of the ceramic body 7, and closed on the respective opposite side.
  • the exhaust gas flow enters through a channel 5 which is open at the inlet side but closed at the outlet side and must be open to leave the ceramic body 7 through the internal wall of the respective channel 5 to the adjacent channel 5 which is closed at the inlet side but open at the outlet side is, step through.
  • the electrodes 1, 2 are each formed by a group of electrode channels 4, in each of which an electrical coating 6 is introduced at least partially along its axial extent.
  • the groups of electrode channels 4 are each formed by adjacent electrode channels 4, so that a flat electrode surface 1,2 is defined by each group of electrode channels 4.
  • other embodiments of the electrodes 1,2 are also possible.
  • the flat electrode surfaces 1,2 each extend horizontally and parallel to each other.
  • the distance between two adjacent electrode surfaces 1 and 2 is preferably less than 40 mm, about 15-25 mm.
  • a homogeneous electric field can be ensured between the electrode surfaces 1 and 2, in particular in those regions of the room which are located within the each of two adjacent electrode surfaces 1,2 limited space region of the ceramic body 7 are located, which is referred to below as a homogeneous field region.
  • the region 3 of the ceramic body 7 lying outside the homogeneous field region has in the embodiment according to FIG Fig. 1 and 2 over a denser structure, in order to additionally increase their structural load capacity.
  • Two adjacent electrode surfaces 1 and 2 are each contacted opposite polarity, wherein in the Fig. 1 approximately the electrode surface 1 is grounded, and the electrode surface 2 is supplied with bipolar voltage pulses.
  • the drift velocity c (d) of the charged carbon particles with the diameter d in the field direction must be greater than or equal to the velocity component v x against the field direction, ie c d ⁇ v x
  • the soot particle practically does not move with respect to the distance to the channel walls. If, on the other hand, the particle is to reach the right wall, then the invention must apply c d ⁇ 2 ⁇ v x or c d / v ⁇ Second ⁇ H / L or ⁇ d , z d , e ⁇ 2 ⁇ H , v / L because in the worst case, the particle has to travel the double path in the gas when it flows in close to the non-soot-bearing wall.
  • exhaust gas quantities of 400 kg / h at 550 ° C with acceptable filter cross sections can fulfill these requirements.
  • This exhaust gas mass flow of 400 kg / h corresponds to a full load operation of a supercharged diesel engine of the lower middle class.
  • a deposition field E of 4 kV / cm can thus at a channel height h of 0.6 mm, even at full load all particles except for Size range around 100nm along a separation wall. Since particles with a diameter of 100 nm no longer contribute to the number of particles and still nothing to the particle mass, filtering with these parameters is perfectly acceptable, since regeneration under plasma proceeds continuously and rapidly at these temperatures.
  • the difficulty in operating a soot filter is always in the low load range and is particularly critical when the deposition of the filter must be designed for high engine performance.
  • the higher motorized mid-range cars differ between full load and city operation in the gas flow by about a factor of 10. If the filter is now designed so that all particles at full load over the filter length L (usually 20 cm to 25 cm) are deposited, so this deposition takes place in City operation at the first 20 mm to 25 mm instead. Thus, and especially at low engine temperatures, the regeneration of the filter can be locally overwhelmed. The situation becomes particularly critical when the N0x emission is exchanged for more soot emission.
  • the separation field can therefore be controlled proportionally to the gas volume flow, so that the soot deposition always extends approximately over the entire filter length L.
  • the diameter can be taken with the smallest product of ⁇ (d) .z (d), or those whose soot particles are to be deposited just within the filter length L.
  • the deposition field E with the gas volume flow V and the temperature correction V (T) / ⁇ (d, T) is controlled, there is the further difficulty that with decreasing Abscheidefeldschreib E, the plasma temperature and thus the regeneration rate is lower, and ultimately the conversion of the soot completely disappears.
  • the deposition field E must not be regulated below a predetermined limit. This problem is particularly serious in short Full load accelerations with a cold engine that is cold for longer partial load operation.
  • this problem can be solved by setting a correspondingly high deposition field E with a high amount of soot, but switching between high field and low field depending on the regeneration state of the filter with low sootfall, wherein the data "high sootfall” and “Low soot” and gas mass flow from the engine computer via a CAN bus to the processor of the filter to be transferred, or the change is controlled directly from the engine computer, which then calculates soot amount and soot distribution in the filter itself.
  • the processor of the soot filter can also perform this control itself.
  • the simplest reaction is obtained by measuring the differential pressure preferably occurring at the filter itself (p 1 -p 2 ), which in a good approximation is directly proportional to the mean flow velocity v in the channels 5 of the honeycomb body 7 and its increase or decrease is good Conclusion on the soot emission of the engine allowed.
  • Control value 1 Control value 2
  • Control value 2 Control value 1 for T ⁇ T 1
  • Control value 2 T 2 ⁇ T ⁇ T 1
  • Control value 3 for T 2 ⁇ T (p 1 -p 2 ) n T n E n1 E n2 E n3 (p 1 -p 2 ) n + 1 Tn + 1 E n1 + 1 E n2 + 1 E n3 + 1 , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
  • the filter processor itself can calculate and carry out the voltage control necessary for the optimum separation of the soot, if the motor processor has the necessary signals, preferably temperature, gas volume flow or mass flow, preferably also EGR rate and injection quantity, via a signal system, preferably via CANBUS. provides.
  • the smaller filter processor determines the necessary voltage changes more quickly, and thereby can adjust the deposition field E, which is only slowly controllable by capacitances on the high-voltage side, in time for the new soot accumulation.
  • this processor After the plasma in the filter anyway by a microprocessor as a function of temperature, residual oxygen and preferably humidity and soot amount is regulated, it is advantageous if this processor also calculates the amount and distribution of the deposited soot, and then controls its deposition field E and in particular the temporal distribution between deposition field strength and regeneration field strength.
  • the information can be determined by the filter's own filter as well as by the filter's own analysis of the current-voltage characteristics, it is particularly advantageous if from the engine control processor, preferably via a CANBUS, corresponding data such as exhaust gas mass flow, injection quantity, EGR rate, residual oxygen and Russemission be fed to the filter processor.
  • This inventive method for the operation of the filter in the low load range can be further modified according to the invention by the necessary for its implementation device consists in a two-flow design of the filter, wherein in the lower power range, only a partial filter is acted upon with the exhaust gas.
  • a cold engine so-called "housewife cycle”
  • housewife cycle can preferably be switched back and forth between the two sub-filters to regenerate the soot in the off system at higher field, and in the acted upon with the exhaust stream sub-filter at preferably lower field over the entire filter to collect.
  • the creep rupture strength of filter arrangements based on the use of a ceramic body with channels closed on one side can thus be decisively increased.

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Filtering Of Dispersed Particles In Gases (AREA)
  • Processes For Solid Components From Exhaust (AREA)
EP20080450074 2007-05-10 2008-05-09 Fitre à paroi ayant une résistance de rupture en fluage illimitée Withdrawn EP1990097A2 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT7312007A AT505129A1 (de) 2007-05-10 2007-05-10 Wall-flow-filter mit unbegrenzter zeitstandsfestigkeit

Publications (1)

Publication Number Publication Date
EP1990097A2 true EP1990097A2 (fr) 2008-11-12

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EP20080450074 Withdrawn EP1990097A2 (fr) 2007-05-10 2008-05-09 Fitre à paroi ayant une résistance de rupture en fluage illimitée

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AT (1) AT505129A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015159539A3 (fr) * 2014-04-15 2016-01-21 Toyota Jidosha Kabushiki Kaisha Appareil de déshuilage
CN108426806A (zh) * 2017-02-15 2018-08-21 帕拉贡股份公司 颗粒物测量设备及其操作方法

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015159539A3 (fr) * 2014-04-15 2016-01-21 Toyota Jidosha Kabushiki Kaisha Appareil de déshuilage
US10245594B2 (en) 2014-04-15 2019-04-02 Toyota Jidosha Kabushiki Kaisha Oil removal apparatus
CN108426806A (zh) * 2017-02-15 2018-08-21 帕拉贡股份公司 颗粒物测量设备及其操作方法

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Publication number Publication date
AT505129A1 (de) 2008-11-15

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