DE3541685A1 - Process for purifying exhaust gases of a combustion engine - Google Patents

Abstract

The soot-loaded exhaust gases of a diesel engine are passed through a filter of activated carbon which is composed of a loose packing of oven coke. The loaded oven coke is then burnt as an energy source in the boiler. The oven coke 14 is arranged in a vessel 6 within the exhaust gas system 2-4 of a diesel engine 1 and has an extension of the active packing 14 for which the exhaust gas requires a time interval between 0.01 and 1 second to flow through. The vessel 6 is composed of three tubes 8, 11 and 12, coaxially joined within each other, of which the two innermost tubes 8 and 11 have through-holes 15 and 16 for the exhaust gas 3. The packing 14 is arranged in the annular space 13 between the inner tube 8 and the intermediate tube 11. <IMAGE>

Description

The invention relates to a method for cleaning soot-laden exhaust gases from an internal combustion engine, in particular Diesel engine through a filter made of activated carbon, especially coke.

The emission of incompletely burned parts of the fuel in internal combustion engines, especially diesel engines, is a problem that requires special attention from the Combustion technology applies because the predominantly as soot in the Atmosphere released parts of the fuel the environment strain. A complete suppression of this kind of Pollutant emissions are not technically possible, however A well-set combustion in the engine ensures that pollutant emissions remain limited. A regular one and careful adjustment of the diesel engine is therefore A prerequisite for its proper and low-emission Business. This requirement is often lacking. The Combustion within the diesel engine is then incomplete. This is manifested by a visible dirty Soot cloud, which the engine emits. In addition to the required Care to adjust the combustion of the diesel engine  there is therefore no lack of attempts to exhaust the Clean diesel engine by filtering. In this context filter systems were probably already different Kind and including those suggested which are operated with activated carbon because of the absorbency the activated carbon is large for pollutants.

However, the production of activated carbon is complex. From that follows the task for the invention, an exhaust filter for To create diesel engines based on activated carbon, its filter-active carbon particles inexpensively procured and available in large quantities. At the same time should it be possible to filter the device like this to train them after a certain period of use can be easily filled with fresh filter material.

According to the invention, this object is achieved in that the exhaust of the diesel engine before the exhaust during a Time between 0.01 and 1 s due to a loose bed or leads a bed of hearth coke that is made of brown coal was won.  

The production of brown coal coke on the hearth furnace is known and described in detail in a number of publications been. The most important of these publications are:

1. H. B. Königs: "Fine coke production from brown coal", Daily energy issues, 27th year (1977), Issue 8/9, pp. 596-599,

2. E. Scherrer: "Production of brown coal coke in the Salem-Lurgi hearth furnace "brown coal, issue 7, July 1981, S 242-246

3. D. Boecker: "Noble Grains", Energy, Volume 35, Issue 3, 1983, pp. 35-37.

These publications all contain for the invention required information regarding stove coke.

The "hearth furnace coke" produced by the hearth furnace process from Rhenish brown coal has the surprising Property of a high adsorption capacity of pollutants, especially soot. It is useful to solve the problem underlying the invention and fulfills all conditions regarding the value for money, availability and ease of use.  

In addition, the one with the pollutants is suitable loaded oven coke still as an energy or carbon carrier in further processes, for example for Burning in the boiler. The special properties of the Herdofenkokses owe it to the fact that the combustion of the loaded coke protecting the environment Conditions can take place. This is almost a complete removal of contaminants possible incurred in the diesel process. The oven coke as more concentrated Carbon carrier enables combustion control in the boiler at relatively favorable flame temperatures, and so completely that the contaminants carried along, especially higher hydrocarbons are burned and therefore do not get into the environment.

In a device for implementation according to the invention of the method with a connection for passing the Exhaust gas through a filter made of activated carbon, which is in a substantially closed container in any Installation position at a suitable point within the exhaust system a diesel engine is located, the container or the the bed of hearth furnace coke contained therein an extension the flow of the exhaust gas given flow rate from the amount of exhaust gas and Flow cross-section a period between 0.01 and 1 s  needed. The bed of the hearth furnace coke is located loose in the container, which according to the invention within the Exhaust system, e.g. B. at the end of the exhaust pipe of the diesel engine, is arranged.

Of that delivered in different fractions Oven coke is the coarsest fraction, namely the fine coke with grain sizes between 1 and 4 mm, for the invention particularly well suited.

One according to the invention in any installation position, in particular horizontal position, usable container, has a first, inner manifold for the exhaust gas, a second one around the first tube concentrically arranged intermediate tube for Inclusion of the oven coke bed in the annular space between the first and the second tube and a third, the second Pipe concentrically surrounding collector pipe, in which the cleaned exhaust gas is collected before passing through the exhaust is expelled. Passages on the cylindrical walls the exhaust gas conducts between the inner tubes the filling of the hearth coke. The container points at least one external connection with which it is open simply connected to the exhaust system of the diesel engine can be. In addition to the cleaning effect of Oven coke on the flue gas exercises the bed at the same time also a sound absorbing effect, so that with the  Container according to the invention a simplification of the Exhaust system possible without an existing silencer is, this can possibly be completely eliminated.

Especially for use in a horizontal installation position the passages for the exhaust gas are each on the inside cylindrical walls of the type of pipes Sieve tubes provided. This way the exhaust gas forced each to the largest possible amount of the fill to flow through the oven coke before going outside is delivered.

The container that holds the fill of the Oven coke contains, or parts of the container within the exhaust system of a diesel engine arranged so that a easy interchangeability is possible. For example an arrangement at the end of the exhaust system of cars cheap, which are operated with diesel engines. These The arrangement makes it possible for the user of the vehicle the container according to the invention with its expiration Renewed period of use itself. For trucks and large or stationary diesel engines are appropriate modified arrangements provided a similar enable easy handling, as is the case with the Renewal of fuel or oil filters on internal combustion engines is common.  

To achieve an easy interchangeability of the Filter or parts of the container is designed so that it can be opened. In this way it becomes possible the bed of loaded hearth coke Remove the opening of the container from it and add fresh To replace stove coke. It is intended to be fresher Oven coke is prepared as a commercially available spare part.

A long service life with many renewal cycles of the Filters according to the invention can be achieved if this made of a corrosion-resistant metal such as Chrome steel or precious metal is produced.

The invention is illustrated by an embodiment described. They each show in schematic, not scale representation of the

Fig. 1, the exhaust system of a diesel engine,

Fig. 2 shows the longitudinal section through a container according to the invention and

Fig. 3 shows a cross section through the container of FIG. 2 along the line III-III.

A diesel engine 1 has a collector 2 for the exhaust gas 3 on the exhaust side, which usually flows through a silencer 4 before it leaves the exhaust system via the exhaust 5 . Between the muffler 4 and the exhaust 5 , a container 6 is arranged, which is provided according to the invention for cleaning the exhaust gas 3 , so that cleaned exhaust gas 7 can be released into the open. The container 6 consists of a first cylindrical tube 8 with a connection 9 , with which it is connected to the silencer 4 .

An intermediate tube 11 is arranged coaxially to the longitudinal axis 10 of the cylindrical container 6 and concentrically to the inner tube 8 , which in turn is concentrically surrounded on the outside by a header tube 12 . In the annular space 13 between the inner tube 8 and the intermediate tube 11 there is a loose bed 14 of hearth furnace coke which completely fills the annular space 13 . The average grain size of the bed of the hearth furnace coke is 1 to 4 mm. The oven coke itself has the following characteristics:

Brief analysis

Water content 1.0% by weight Ash content9.0% by weight volatile constituents 3.5% by weight fixed carbon86.5% by weight Calorific value (Hu) 29 700 kJ / kg

Physical indicators:

Density 1.90 g / cm ³ apparent density 0.95 g / cm ³ highest bulk density 0.735 g / cm ³ spec. Surface 250 m ³ / g ignition point 300 ° C

The inner tube 8 and the outer tube 12 are each closed on one of their end faces. The intermediate tube 11 is closed on both ends. In the area of their parts which are arranged concentrically to one another, the inner tube 8 and the intermediate tube 11 have openings 15 and 16 for the passage of the exhaust gas 3 .

The unpurified exhaust gas 3 enters the inner tube 8 at the end 9 and the annular space 13 at the openings 15 . It flows through the bed 14 at a temperature of about 100-300 ° C. and enters through openings 16 as cleaned exhaust gas 7 into the annular space 17 of the collecting pipe 12 , which it finally leaves at the exhaust 5 .

The end walls 18 and 19 can be designed to be removable, so that the container 6 can be taken apart after the connection 9 has been released . The bed 14 is exposed. The used stove coke can be removed from the annular space 13 by pouring it out and replaced by fresh stove coke. The end walls 18 and 19 are then closed again after the pipe system has been joined together. The container 6 is ready for a new use. Since the bed 14 of the oven coke also has a sound-absorbing effect, it is possible to dispense with at least parts of the silencer 4 of the exhaust system. A container 6 with a bed 14 of hearth furnace coke then takes its place, which, if the container can be opened and is made of corrosion-resistant material, can be used again after the bed 14 has been renewed. According to the invention, the container 6 is arranged in an area of the exhaust system behind the diesel engine 1 in which the temperatures of the exhaust gas 3 are above 100 ° C. Filtering and purification of the exhaust gas are presumably carried out by the large number of macropores in the oven coke 14 . The oven coke is not consumed by the soot. If necessary, it can be recovered after thermal treatment. Burning the used stove coke in the boiler is even simpler, whereby it also serves as an energy source. Since there is no significant consumption of the substance of the hearth coke during the cleaning of the exhaust gas 3 , the entire annular space 13 is always almost completely filled by the bed 14 of the hearth coke.

An embodiment of a container for use in a diesel engine in a motor vehicle had the following dimensions: The axial length of the container was 30 cm with a diameter of 15 cm. The amount of the bed 14 was 1 kg. Corresponding to the nominal power of the diesel engine 1 of 60 hp, 200 operating hours were achieved in full load operation with properly set combustion with a single filling of the bed. A quantity of soot of between 100 and 400 g was retained before the bed had to be replaced. The exhaust gas temperatures averaged 120 ° C. The amount of exhaust gas flowing through was about 40 m ³ / h, which corresponded to a residence time of the exhaust gas in the bed of about 0.1 s.

Claims (7)

1. A method for cleaning soot-laden exhaust gases of an internal combustion engine, in particular diesel engine, which are passed through a filter made of activated carbon, in particular coke, characterized in that the exhaust gas before the exhaust for a period between 0.01 and 1 s over a loose Bulk or a bed of stove coke, which is made of brown coal. 2. The method according to claim 1, characterized in that one with soot and possibly other impurities loaded oven coke as an energy and / or carbon carrier used in further proceedings. 3. Device for performing the method according to claim 1 with at least one connection for passing the exhaust gas through a filter made of activated carbon, essentially closed container in any installation position within the exhaust system of a diesel engine, characterized in that the container ( 6 ) or a bed or bed ( 14 ) of hearth furnace coke located therein has an extension for the flow of which the exhaust gas ( 3 ) requires a time period between 0.01 and 1 s at a given flow rate. 4. Apparatus according to claim 3, characterized in that the container (6) comprises a first, inner manifold (8) for the exhaust gas (3), a second to the first tube (8) concentrically arranged intermediate pipe (11) for the bed ( 14 ) and a third manifold ( 12 ) concentrically arranged around the second pipe ( 11 ) for the cleaned exhaust gas ( 7 ), passages ( 15, 16 ) for the exhaust gas ( 3, 7 ) on the inner cylindrical walls of the pipes ( 8 and 11 ) and at least one outer connection ( 9 ) to the exhaust system ( 2, 4 ) on the first pipe ( 8 ) are provided. 5. Device according to one of claims 3 or 4, characterized in that the container ( 6 ) or parts thereof within the exhaust system ( 2, 4 ) are arranged interchangeably. 6. The device according to claim 5, characterized in that the container ( 6 ) or parts ( 18, 19 ) thereof can be opened. 7. The device according to claim 6, characterized in that the container ( 6 ) or parts thereof are made of a corrosion-resistant metal.