RU1780549C - Internal combustion engine catalytic neutralizer - Google Patents

Abstract

Usage: car exhaust gas converters. The inventive exhaust gas enters the front end surface of the Converter in the direction indicated by arrows, flows through channels formed by cells 6 of the gratings, washes the outer surfaces of the tubes 4 and 5 in the transverse direction and leaves the opposite end of the converter. As a result of contact of the exhaust gas with a catalyst layer deposited on the surface of tubes 4 and 5, a neutralization reaction occurs. Simultaneously with the flow of exhaust gas, a working medium, for example gaseous, flows through the supply pipes 11 and 12. Then, the working medium enters the distributing manifolds 7 and 9, respectively, passes inside the tubes 4 and 5, enters the collecting manifolds 8 and 10, and exits through branch pipes 13 and 14 of the converter. When connecting the nozzle 13 to the nozzle 12 using the pipe 15, the working medium flows first through the tubes 4, and then through the tubes 5 and then leaves the neutralizer through the nozzle 14. The flow rate and the initial temperature of the working medium flowing through the tubes 4 and 5 were controlled by means of devices located outside a converter (not shown). To ensure a uniform flow rate of the working medium through the tubes, the supply pipes 11 and 12 may contain nets 17. 1 zp f-ly, 4 ill. СО С vi 00 о Ј h CA

Description

The invention relates to catalysts for purifying gas emissions from harmful impurities and can be used to neutralize exhaust gases from automobiles.

A catalytic converter is known in the form of a carrier unit in which through channels are formed which serve to pass the exhaust gas and the catalyst is deposited on the walls of the channels. Refractory oxides and mixtures thereof, silicon carbides and nitrides, boron carbides and other ceramics are used as carrier material.

A disadvantage of this catalyst is the low thermal conductivity of the carrier materials. As a result, the thermal stability of the catalyst is reduced, and cracking and destruction are possible. In addition, its warm-up time is extended when the engine is turned on.

Also known is a catalytic converter with a metal support made in the form of grids, profiled plates, wire gaskets, spirals, porous balls, etc., housed in a housing having an input and output device for passing exhaust gas.

The disadvantage of this catalytic converter is the low heat resistance of the metal carrier in the exhaust gases when their temperature rises to 900-1000 ° C and higher in forced operation of the engine. When the temperature of the exhaust gases drops to 200 ° C or lower at idle, when the catalytic reactions are sharply slowed down, the catalyst also becomes ineffective.

Closest to the invention is a catalytic converter for an internal combustion engine having a working medium source, comprising a housing with a carrier disposed therein, made in the form of a packet of gratings formed by longitudinal tubes and transverse jumpers forming exhaust gas channels, as well as an inlet and outlet exhaust gas nozzles.

A disadvantage of the known catalytic converter is the narrow operating temperature range due to the metal materials of the gratings.

The purpose of the invention is to expand the temperature range of operation of the catalytic converter.

This goal is achieved by the fact that in the known catalytic converter for an internal combustion engine having a source of the working medium, comprising a housing with a carrier placed therein, made in the form of a packet of gratings formed by longitudinal pipes and transverse jumpers forming channels for the exhaust gas, inlet and

0 outlet pipes, it additionally contains transverse and longitudinal fixing bridges with holes that form the side walls of the carrier, supply and return pipes installed pairwise one relative to another, the transverse bridges are made in the form of pipes, the ends of the longitudinal pipes are installed in the holes of the fixing bridges and supply nozzles communicated on one side with

0 source of the working environment, and on the other - with pipes.

In addition, adjacent inlet and outlet pipes are interconnected.

The implementation of the catalytic neutral5 block with additional transverse and longitudinal fixing bridges, which have holes and form the side walls of the carrier, allows the formation of a packet of gratings from mutually intersecting layers of pipes

accordingly, to ensure mutually cross flow of the working medium in the volume of the converter and thereby intensify the heat transfer between the layers. As a result

5, for example, the temperature of the gratings can be significantly reduced while increasing the temperature of the neutralized gases.

The installation of supply branch pipes and outlet water in pairs relative to one another makes it possible to fully use the side surface of the converter to supply the necessary flow rate of the working medium.

5 The implementation of transverse jumpers in the form of pipes creates additional channels in the volume of the converter for the passage of the working medium and makes it possible to obtain uniformly cooled or heated cells in

0 to the entire volume of the converter.

The installation of the ends of the longitudinal pipes in the holes of the fixing jumpers allows you to accurately distance the lattice layers relative to each other and to obtain

5 cells of channels for passing neutralized gas with calculated thermohydraulic characteristics.

The connection of the supply pipes on the one hand with the source of the working medium, and on the other with the pipes makes it possible to direct two flows of the working medium into the corresponding pipes so that each cell of the channel serving to pass the neutralized gas is washed around the perimeter by the working medium flowing in the pipes and providing optimal thermal conditions (cooling or heating) in each individual channel and in the package as a whole.

The communication of adjacent supply and exhaust nozzles with each other allows one to organize effective heat transfer between the layers of the tube sheets due to heat and mass transfer, and not only due to the thermal conductivity of the pipe materials. At the same time, regenerative heating of the layers provides an increase in temperature uniformity in the volume of the converter and a decrease in thermal stresses in it.

Figure 1 shows the design of the converter, a view from the front end; in Fig. 2, enlarged view shows place I in Fig. 1; Fig. 3 is a view A in Fig. 2; figure 4 shows a diagram of a converter with series-connected adjacent inlet and outlet pipes.

The neutralizer contains a box-shaped body 1 with a carrier placed in it, the side walls of which are made in the form of jumpers 2 and 3, in the holes of which pipes 4 and 5 are fixed by their ends, which form the lattice structure of the carrier, Cells 6 of the gratings form through channels for the passage of neutralized gas . On the side walls of the housing 1, collectors 7,8,9 and 10 are formed, having inlet pipes 11,12 and outlet 13,14 installed in pairs relative to one another. The supply pipes 11 and 12 are communicated on one side (external) with a source of the working medium (not shown), and on the other side (internal) with pipes 4 and 5.

The serial connection of adjacent pipes 13 and 12 with each other using the pipe 15 is shown in Fig.4.

The movement of the working medium through the nozzles, collectors and pipes in the drawings is indicated by solid arrows, and the movement of neutralized gas in the channels between the pipes is indicated by dashed arrows.

The catalytic converter operates as follows.

The exhaust gas enters the front end surface of the converter in the direction indicated by arrows 16 (FIGS. 2 and 3), flows through the channels formed by the cells 6 of the gratings, washes the outer surfaces of the tubes 4 and 5 in the transverse direction and leaves the opposite end of the converter. As a result of the contact of the exhaust gas with a catalyst layer deposited on the surface of the tubes 4 and 5, a neutralization reaction 5 takes place. Simultaneously with the flow of exhaust gas, a working fluid, for example gaseous, flows through the supply pipes 11 and 12. Next, the working environment enters respectively

0 distributing collectors 7 and 9, passes inside the tubes 4 and 5, enters the collecting manifolds 8 and 10 and exits through the branch pipes 13 and 14 of the outlet from the converter. When connecting the nozzle 13 to the nozzle 12 using the pipe 15, the working medium flows first through the tubes 4, and then through the tubes 5 and then leaves the neutralizer through the nozzle 14. The flow rate and the initial temperature of the working medium flowing through the tubes 4 and 5 are regulated. carried out using devices located outside the converter (not shown).

To ensure a uniform flow rate of the working medium through the pipes of the pipe 11

5 and 12 of the supply may contain mesh 17.

Liquids and gases, including water and air, can be used as the working medium.

Tubes 4 and 5 can be made from

0 non-ferrous metals and alloys, structural and stainless steels, titanium, nickel, ceramic, glass and other materials (diameter 1-2 mm, wall thickness 0.05-0.1 mm).

5 Catalytically active substances can be dispersed in the form of additives in the material of the tubes, the surface of which is made with developed porosity, or deposited on an intermediate porous

0 substrate-sublayer, specially formed on the surface of each tube. In this case, technological methods for obtaining developed porosity on catalyst supports can be used, such as

5 for example, annealing in air, etching in a gas or liquid medium, spraying, etc. Example 1. A catalytic converter for treating exhaust gases of gasoline engines contains tubes 4 and 5

0 from an aluminum alloy (type AL.AD.AMg) with a diameter of 2 mm and a wall thickness of 0.1 mm. The ends of the tubes are soldered into the holes of the aluminum jumpers 2 and 3 with a wall thickness of 1 mm. The cell size between the tubes is 2x2 mm. Dimensions of the neutralizer: 200 x 150 x 150 mm. The inlet and outlet pipes for passing the working medium - air are also made of aluminum alloy, and for exhaust gases - stainless steel type

12X18H10T and with screws are attached to the corresponding end collectors of 7.8.9 and 10 of the converter. A catalyst layer (platinum, palladium, ruthenium, etc.) is chemically deposited on the surface layer of the tubes formed by porous alumina.

When the engine is running, exhaust gas flows in the channels between the tubes

4 and 5 by blowing them in the transverse direction. At the same time, air is supplied through the nozzles 11 and 12, which cools from the inside of the tubes 4 and 5. It is heated and can be mixed with the exhaust gas stream at the inlet of the neutralizer or ejected outward or passed through a cooling system in a closed loop with constant circulation through these tubes. The air supply system can be structurally implemented according to compressor or weight-compressor schemes. The supply of cold air to the tubes in the formed engine operating modes when the temperature of the exhaust gas reaches 700-800 ° C. Allows you to maintain the temperature of the inner surface of the walls at the level of 300 ° C at a surface temperature of the catalyst 550-600 ° C. This prevents overheating of the aluminum structure of the converter. Preheating the highly conductive aluminum tubes to 250-300 ° C with hot air from the engine cooling system or a special heater allows the catalyst to idle efficiently when the exhaust gas temperature is 120 ° C and is insufficient for catalytic reactions to proceed actively.

Example 2. The catalytic converter for diesel engines is made similarly to that described in example 1 but the nozzles 13 and 12 are connected to each other by a heat-insulated pipe 15. Since the temperature of the exhaust gases of diesel engines is significant (200-250 ° C ) lower than that of gasoline engines, the heating of the tubes 4 and

5 allows to increase the efficiency of the catalyst. To do this, air is first passed through the pipe 11 into the tubes 4, the passage of which it is heated to the temperature of the incoming gases (150-200 ° C), then hot air through the pipe 15 enters the pipe 13, the collector 9 and then into the tubes 5, where it additionally heated by increasing the temperature of the gases during the catalytic reaction developing in the volume of the tubular package. Then, hot air can again be directed into the pipe 11.

As a result, in steady state

the average temperature on the outer catalytic layer of the tubes is 500 ° C, which ensures the effective operation of the converter. The regenerative heating of the bag and the high thermal conductivity of the tube material help to equalize the temperature in the bag and. consequently, a more uniform course of catalytic reactions, as well as a decrease in thermal stresses in the packet.

Regulation of the temperature and flow rate of air supplied to the tubes allows the proposed converter to be made of lightweight highly conductive aluminum alloys.

The installation of several neutralizers, sections with individual air supply paths through the tubes of each section, one after another, by maintaining a predetermined temperature level of the catalysts in each section, it is possible to selectively carry out not only the main reactions (oxidation of carbon monoxide and hydrocarbons, reduction of nitric oxide), but also capture, for example, sulfur, lead, phosphorus and other components of the exhaust gases of engines.

The proposed catalyst design can also be used in industrial plants for the catalytic purification of gases, in the air-oxygen conversion of methane, gas-phase catalytic reactions, etc.

The use of the invention provides the following advantages.

The catalyst allows operation at an exhaust gas temperature several hundred degrees higher than the permissible temperature of the carrier material. In the case of lowering the gas temperature to 100-200 ° C, additional heating of the tubular package ensures the maintenance of effective catalytic reaction modes.

The neutralizer can also act as a heat exchanger-heater or cooler for working fluids passing through tubes. This makes it possible to use it, for example, in a heating system for a passenger compartment.

The design of the converter allows the use of a wide assortment of tubes made of various materials, as well as with various geometric cross-sections and finning, to enhance heat transfer. The production of perforated plates made of non-ferrous metals, steels, glass, plastics, and other materials, mastered in various industries, makes it possible to widely use them as end faces

socks of neutralizers. Fixing the tubes in the openings of the hems using welding, soldering, gluing, galvanic and gas-phase deposition, pastes, etc., allows the mass production of neutralizers for various operating conditions in the transport, chemical and energy industries, especially with large sizes of neutralizers which are extremely difficult to produce in the form of sintered ceramic blocks and where there are technological difficulties in connecting ceramics with metal structures.

The advantages of the catalyst also include the possibility of regeneration of its materials after the exhaustion of the catalyst resource.

Claims (1)

1. The neutralizer pop. 1.different from the fact that the adjacent nozzles of the supply and then are communicated with each other. (tfow / tM0) Fig 2 Buff a