EP0689577B1 - Use of ferrocene - Google Patents

Abstract

Described is the use of ferrocene and/or ferrocene derivatives as an additive to heavy-grade fuels for high-compression, auto-ignition internal combustion engines. This measure reduces functional impairment resulting from sedimentation in downstream units.

Description

The invention relates to the use of ferrocene and / or ferrocene derivatives as an additive to heavy-duty internal combustion engine fuels for high-compression, self-igniting engines.

Ferrocene and its derivatives are known from the literature. Ferrocene and its production were first described in Nature 168 (1951), page 1039. Since then, ferrocene and its derivatives and corresponding manufacturing processes have been the subject of numerous patents, e.g. B. US 2,650,756, US 2,769,828, US 2,834,796, US 2,898,360, US 3,035,968, US 3,238,158 and US 3,437,634.

It is also known from the patent literature that ferrocene can promote combustion processes. DE 34 18 648 mentions, among many other compounds, ferrocene (dicyclopentadienyl iron) as a possible additive in order to optimize the combustion of heating oil, i. H. to facilitate the delivery of the heating oil by the burner and to promote the complete combustion of the heating oil.

No. 4,389,220 describes a method for conditioning a diesel engine. For this purpose, 20 to 30 ppm ferrocene are added to the diesel fuel. This is intended to remove carbon-containing deposits in the combustion chamber and to prevent them from forming again. At the same time, it was found that these measures reduce fuel consumption by up to 5% per route traveled. Diesel fuel is understood here to mean a fuel which is known as "No. 2 fuel oil" according to ASTM. Such a fuel is a middle distillate of the petroleum refining process and is available under the name "Diesel" at petrol stations. This means that the 4-stroke diesel engines of road vehicles are usually operated, eg cars, buses, trucks. The named fuel corresponds to DIN 51601 and is similar in quality to the heating oil EL. It is therefore a light to medium quality fuel.

For large engines with a low speed of 900 to 50 rpm, such as used in ships or power plants, heavier quality fuels are used. The problem here is that downstream units are impaired in their function by carbon-containing deposits. Such units are in particular turbochargers and heat exchangers. Deposits on valves, piston rings and in the combustion chamber are also undesirable, since they can lead to a reduction in engine performance and / or to increased wear on the affected parts.

The object of the invention is to minimize the deposits mentioned or to facilitate their removal.

According to the invention, this object has been achieved by using ferrocene and / or ferrocene derivatives as an additive in a concentration of 1-100 ppm to heavy-quality internal combustion engine fuels for high-compression, self-igniting engines.

Especially when operating such large engines with heavy fuels, a ferrocene additive has surprisingly proven to be particularly cheap. This applies above all to relatively large motors, that is to say those with a total output of 400 to 100,000, preferably 15,000 to 50,000, in particular more than 30,000 kW.

The heavier the fuel, the more likely there are problems with the deposits mentioned. With these fuels, an additivation with ferrocene has surprisingly been found to be particularly effective. This was all the less to be expected since it was known that ferrocene is very effective in improving the combustion of light heating oil but less effective in heavy heating oil.

Especially for qualities that are usually used as marine heating oil, "bunker C" quality, marine diesel fuel or dest. Are referred to marine diesel fuel, the use according to the invention is advantageous. As can easily be seen from the names of the fuel qualities, these are mainly used to operate .marine engines.

The fuels in question can, for example, be residues from atmospheric crude oil distillation, from vacuum distillation or from a catalytic cracker. The density of these fuels is in particular in the range between 0.9 and 1.0 kg / dm ³ . These fuels can be classified more precisely on the basis of ISO 82 17. The fuels are divided into two classes, so-called distilled marine fuels (marine distillate fuels) and so-called heavy residual fuels. The former are given a DM type designation and the latter an RM type designation. Some types are listed below with their most important properties such as density, viscosity, sulfur content and carbon residue. DMB DMC RMA 10 RMG 35 RMH 45 Density kg / dm3 0.90 0.92 0.95 0.991 1,010 Max. kinematic viscosity cSt at 40 ° C 11.0 14.0 - - - at 100 ° C - - 10th 35 45 Max. Carbon residue% by weight 0.25 2.5 12th 18th 22 Max. Sulfur content% by weight 2.0 2.0 3.5 5.0 5.0

All DM and RM types can be used as fuels in the sense of the present invention.

Many marine engines of large ships suitable for high seas are 2-stroke engines. The invention is particularly suitable for these. However, good results can also be achieved with 4-stroke engines by means of the additives according to the invention. In both cases, the motors are slow-running and have a speed of 900 to 50, preferably 200 to 50 revolutions / min, in particular a maximum speed of 100 revolutions / min. and have less.

Good results have been achieved with a ferrocene additive of 1 to 100 ppm. When the additives are below 1 ppm, the effects are not so clear that one could speak of a significant improvement over a non-additive fuel. With an additive content of over 100 ppm, a limit has been reached at which an additional additive does not produce any noteworthy additional effects. Typically a range of 5 to 50 ppm is preferred. An optimal range is between 10 to 30 ppm. The additives can e.g. B. done in that the additive is dissolved in part of the fuel and then this solution z. B. is fed back via a metering pump the main flow of fuel.

Instead of ferrocene, ferrocene derivatives can also be used, at least in part. Ferrocene derivatives are compounds in which, starting from the base of ferrocene, there are further substituents on one or both cyclopentadienyl rings. Examples include ethylferrocene, butylferrocene, acetylferrocene and 2,2-bis-ethylferrocenylpropane.

According to the invention, the heavy quality from the fuel used but also the deposits originating from the lubricating oil are effectively reduced.

Deposits of the downstream units such as turbochargers and heat exchangers as well as engine parts such as valves and piston rings are partially impaired in their functionality. In order to remove the deposits, considerable effort is often required. For example, in large ocean-going ships, it is customary to blow crushed nut shells or rice into the exhaust gas stream to clean the downstream turbocharger. This so-called "soft blasting" removes most of the deposits from the paddle wheels and the upstream nozzle ring. This procedure is usually carried out daily, and even twice a day if necessary, with full engine load. However, this type of cleaning is usually not sufficient. For this reason, a water wash is also carried out about once a month or more often if necessary. Since this washing is carried out with a reduced engine load, there is always a loss of time for the ship. When washing, water is introduced into the exhaust gas flow through a nozzle in front of the nozzle ring and the paddle wheels. This water wash means a high load for the turbocharger, among other things due to the thermal shock effect. That is why tries to keep this water wash to a minimum. The normal time required for such a wash is about 2 to 3 hours. You simply orient yourself on the cleanliness of the water after the rinsing processes. The wash water is usually clearly soiled for 1 to 2 hours. The use of ferrocene-additized fuel according to the invention generally makes both "soft blasting" and water washing superfluous. This protects the affected units without functional restrictions and saves time and work.

A number of problems can arise if the turbochargers are affected by deposits. The effectiveness of the turbocharger and ultimately also of the entire machine is reduced, so that higher fuel consumption results. The deposits can cause the speed to drop, in extreme cases, to the standstill of one or more blade wheels of the turbocharger. In machines with multi-turbochargers, the paddle wheels are supplied with exhaust gas from a common exhaust gas "receiver" which combines the exhaust gases from several cylinders. If the gas is distributed unevenly due to the different flow resistance, which in turn is due to the deposition, a drop in speed, a fluctuation in speed or a significant speed difference between the coupled turbochargers or even standstill can occur. The aforementioned problems due to deposits can lead to premature material fatigue or, in extreme cases, to material breakage. With particularly heavy deposits, this can also occur with smaller machines that are not equipped with multi-turbochargers. Irregularities in the speed, i.e. irregular running, can lead to very strong vibrations, which after a short time can lead to material damage to bearings and other machine parts.

Uneven deposits on the bucket wheels do not necessarily lead to a drop in the speed or speed differences in multi-turbochargers, but also to undesired vibrations due to non-circular running, which can also be the cause of increased wear.

Even in the downstream heat exchangers it can be determined without the additives according to the invention that deposits form on the heat exchanger surfaces form, which, depending on their strength, hinder the heat exchange. These deposits, which mainly contain soot, must be washed from time to time with water, if necessary with cleaning additives, e.g. B. CuCl ₂ solution are removed. The use of ferrocene-additized fuels according to the invention greatly reduces the formation of deposits. If, in contrast to the prior art, a considerably longer period of time does require water washing (e.g. in a dry dock), it has surprisingly been found that the deposits can be removed much more easily after operation with fuel which has been additized according to the invention. This may be due to a change in the composition of the deposits. It was found that these have higher ash contents, lower calorific values and a lower carbon content in contrast to operation with non-additive fuel. It can be assumed that these deposits are less hydrophobic because they contain less oily or oil-like components.

Such water washes of the heat exchanger or the boiler are usually carried out every two years at the latest when the ship is in the dry dock for prescribed maintenance and inspection work. Between two dry dock stays, however, five to six additional washes are usually necessary. These can be dispensed with when using the present invention.

Description of Figure 1

Figure 1 shows schematically the exhaust gas path of a ship's engine of the size mentioned. You can see the engine block (1) with its total of 10 cylinders (2). The exhaust gases from 3 or 4 cylinders are brought together in a so-called exhaust gas receiver (3, 4, 5) and fed to the turbochargers (6, 7, 8). The exhaust gas flows emerging from the turbochargers are brought together in an exhaust pipe (9) and then flow through a so-called exhaust gas "boiler" (10), in which heat exchangers (11, 12, 13) are generated by means of their high, medium and low pressure steam can be. The exhaust gases leave the system via the chimney (14).

The invention was successfully tested on a container ship with the results reported below.

Technical data of the ship:

60,000 GRT Technical data of the machine Power: 33,000 kW Displacement: 10 cylinders of 1.6m ³ each Rotational speed: Max. 90 rpm. Turbocharger speed: approx. 10,000 rpm. Consumption: approx. 6 t / h at full load

After a successful start-up phase, the turbochargers of the machine of this ship were thoroughly cleaned by "softblasting" and water washing. About 3 months later, water was washed without any intermediate cleaning. This water washing was not technically necessary because the turbochargers worked satisfactorily, but was carried out to gain information about the degree of contamination (deposits). Whereas, according to the prior art, "softblasting" and water washing had to be carried out daily and about once a month and the used washing water was heavily soiled for 1 to 2 hours, any cleaning measure was dispensed with here for almost 3 months (85 days) and yet the wash water was clear from the start. This suggests that practically no deposits have formed in the period mentioned. Even areas that cannot be reached with the usual cleaning methods showed no or significantly reduced dirt deposits.

With the heat exchangers it was already possible to visually determine that significantly fewer deposits had formed. The deposits formed could be removed much more easily and quickly than before by water washing.

There were also no visible deposits on the piston rings and valves.

Claims (4)

1. Use of internal combustion engine fuels having a density of 0.9 to 1.01 kg/dm³ which contain ferrocene and/or ferrocene derivatives in amounts of 1 to 100 ppm, in particular 5 to 50 ppm, preferably 10 to 30 ppm, to operate high-compression, self-igniting engines having a rotary speed of 900 to 50, preferably 200 to 50, rev/min.
2. Use according to Claim 1, characterized in that the engines have a total output of 400 to 100,000, preferably 15,000 to 50,000, kW.
3. Use according to Claim 1 or 2, characterized in that the engines are 2-stroke engines.
4. Use according to Claim 1 or 2, characterized in that the engines are 4-stroke engines.

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