CN1052034C - Method for reducing carbon deposits in low speed, high compression, self-ignition internal combustion engines - Google Patents

Abstract

The present invention relates to the use of ferrocene and/or ferrocene derivatives as additives for high quality internal combustion engine fuels for high compression auto-ignition engines.

Description

Method for reducing carbon deposits in low speed, high compression, self-ignition internal combustion engines

The present invention relates to a method of reducing carbon deposits, and more particularly to a method of reducing carbon deposits resulting from the combustion of heavy residual fuel oil in low speed, high compression, self-ignition internal combustion engines.

In a search of known literature on ferrocene and its derivatives, ferrocene and its production process were first described on page 1039 of "Nature" 168 (1951). Subsequently, ferrocene and its derivatives, as well as the corresponding manufacturing processes, have been the subject of numerous patents such as US 2 650 756, US 2 769 828, US 2 834 796, US 2 898 360, US 3 035 968, US 3238 158 and US 3437 634.

It is also known from the patent literature that ferrocene can favorably influence the combustion process. In German Patent 3418648, among many other compounds, ferrocene (dicyclopentadienyl iron) is mentioned as a possible additive to optimize fuel oil combustion and help fuel oil transport through the burner , and promote the complete combustion of fuel oil.

In US patent 4 389 220 a method of regulating a diesel engine is disclosed. 20 to 30 ppm ferrocene is added to diesel fuel to remove carbonaceous deposits in the combustion chamber and prevent their reformation. It was also found that, as a result of this measure, the fuel consumption per distance traveled could be reduced by 5%. The term diesel fuel in this example refers to the fuel known as "No. 2 Fuel Oil" according to ASTM. This type of fuel is a middle distillate from the petroleum refining process and is available at gas stations under the name "diesel". Four-stroke diesel engines in vehicles such as recreational vehicles, buses, and commercial vehicles often run on this fuel. The fuel complies with DIN 51601 and is similar in quality to EL fuel oil. Therefore, it is an intermediate fuel.

High-quality fuels are used in larger and slower engines, such as in ships or power plants. The problem that arises here is that the performance of downstream units can be adversely affected by carbonaceous deposits. Such units include, inter alia, turbochargers and heat exchangers. However, deposits on valves, piston rings and in fuel chambers are also undesirable as they may result in reduced engine performance and/or increased wear on the parts concerned.

It is an object of the present invention to provide a method of reducing carbon deposits in low speed, high compression, self-ignition internal combustion engines, minimizing said deposits, or facilitating their removal.

The above-mentioned object of the present invention is achieved by the following means: providing a ferrocene and/or a ferrocene derivative application, using it as an additive in high-quality internal combustion engine fuel of a high-compression self-ignition engine. The invention is applicable in particular to additives for fuels having a specific gravity of 0.9 to 1.01 kg/dm ³ .

The use of ferrocene as an additive has surprisingly proven to be particularly advantageous, especially for large engines of this type operating with heavy fuel, i.e. having a total drive power of 400 to 100,000 KW, preferably 15,000 to 50,000 KW KW, and especially engines exceeding 30,000KW.

Generally, the above-mentioned deposit problem increases with the increase of heavy fuel. In the case of this fuel, the use of ferrocene as additive has surprisingly proven to be particularly effective.

The following grades, commonly referred to as bunker fuel oils, "C" grade fuel oils, marine diesel fuels, or distillate marine diesel fuels, are particularly advantageous for use according to the invention. As the name of this fuel grade indicates, it is mainly used to run marine engines.

The fuel may be, for example, residues from atmospheric distillation of crude oil from vacuum distillation or from catalytic cracking plants. The specific gravity of the fuel is in particular in the range of 0.9 to 1.0 kg/dm ³ . This fuel can be classified more precisely with reference to ISO8217. According to this standard a distinction is made between two fuels, so-called distillate bunker fuels (marine distillate fuels) and so-called heavy residual fuels. The first gives DM-type names, the second gives RM-type names. Certain types are listed below by way of example, listing their important properties such as specific gravity, viscosity, sulfur content and carbon residue.

DMB DMC RMA RMG RMH

10 35 45 specific gravity kg/dm ³ 0.90 0.92 0.95 0.991 1.010 maximum kinematic viscosity cst at 40°C 11.0 14.0 -- -- --at 100°C -- -- 10 35 45 maximum residual carbon weight% 0.25 2.5 12 18 22 Maximum sulfur content wt% 2.0 2.0 3.5 5.0 5.0

All DM and RM types can be used as fuel within the scope of the present invention.

The marine engines of many large seagoing vessels are two-stroke engines and the present invention is particularly applicable to such engines. Thus, the present invention can be extended to the use of ferrocene and/or ferrocene derivatives as additives in fuels for operating two-stroke engines. In particular when the engine is a low speed engine, the low speed engine has a speed of 900 to 50 revolutions per minute, preferably 200 to 50 revolutions per minute, especially a maximum speed of 100 revolutions per minute or less. However, good results can also be achieved by the addition according to the invention in engines with higher speeds and in four-stroke engines. However, the invention can be extended to the use of ferrocene and/or ferrocene derivatives as additives in fuels for four-stroke engines.

Good results were achieved with the addition of 1 to 100 ppm of ferrocene. When the addition is less than 1 ppm, the effect is so insignificant that it cannot be said that there is a substantial improvement in comparison with the fuel without the additive. In the case of additive additions of more than 100 ppm, a limit has been reached where any additional additive does not cause any additional effects worth mentioning. A range of 5 to 50 ppm is generally preferred. The optimum range is 10 to 30 ppm. This additive addition can be achieved by dissolving the additive in a portion of the fuel and then circulating this solution again into the main fuel main flow, eg via a metering pump.

Ferrocene can be at least partially used as a biological substitute for ferrocene. Ferrocene derivatives are compounds derived from the ferrocene parent in which additional substituents are placed on one or both of the cyclopentadienyl rings. Examples thereof are ethylferrocene, butylferrocene, acetylferrocene and 2,2-bis-ethylferrocenylpropane.

An advantage of the invention is that deposits from the high quality fuel used, as well as from lubricating oil, are effectively reduced.

The performance of downstream units such as turbochargers and heat exchangers, as well as engine parts such as valves and piston rings, can be adversely affected by deposits, some to a considerable degree. Considerable labor and expense are often required to remove the deposits. So, for example, often in large ocean-going vessels, crushed nut shells or even rice are blown into the exhaust stream to clean out downstream turbochargers. A larger part of the deposits is removed from the vane wheel and from the upstream nozzle ring by this so-called "soft jet action". The above procedures are often carried out daily, and if necessary, even twice daily, while maintaining full engine load. However, this cleaning method is often not sufficient. Therefore, additional washing with water is performed about once a month, or more frequently if necessary. Since such washing operations are carried out when the engine load is reduced, a delay of the vessel is always involved. During this washing operation, the water system is introduced into the exhaust gas flow by passing upstream of the nozzles of the nozzle ring and the vane wheel. The washing operation involved considerable stress on the turbocharger and other parts due to its thermal shock. Therefore, attempts are generally made to minimize such washing operations. The typical time required for such a washing operation is about 2 to 3 hours. The guiding factor on this point is simply the clarity of the water after this rinse step. As such, the wash water can typically be significantly polluted for 1 to 2 hours. As a result of the use of fuels according to the invention containing ferrocene as an additive, "soft injection" and this water washing are generally rendered superfluous. This protects the unit without any performance limitations and saves time and labor.

A number of problems can occur when the performance of a turbocharger is adversely affected by deposits. The efficiency of the turbocharger, as well as the efficiency of the machine as a whole, is reduced, so that higher fuel consumption occurs. This deposit can cause a speed reduction and, in extreme cases, stop one or more of the turbocharger's impeller wheels. In the case of a machine with several turbochargers, the exhaust from a common exhaust receptacle which brings together the exhaust from several cylinders is supplied from its vane wheel. If the gas system is not uniformly distributed, which is caused by changing flow resistance, which in turn is caused by deposits, a reduction in velocity, fluctuations in velocity, or appreciable differences in velocity between coupled turbochargers, Or even stop, can happen. The above must be attributed to deposit problems that can cause premature material fatigue or, in extreme cases, material fracture. In the case of particularly thick deposits, which can also occur in smaller machines not equipped with multiple turbochargers, irregular speeds, i.e. erratic running, can cause extremely strong vibrations, which can cause Material damage on bearings and other machine parts.

While uneven deposits on impeller wheels do not necessarily cause speed reduction or differences in speed, in the case of multiple turbochargers it does cause undesirable vibrations as a result of incorrect operation and this vibration may also is the reason for the increased wear rate.

In the downstream heat exchanger without the addition of the additives used according to the invention, deposits can also be found to form on the heat exchanger surfaces, which deposits, depending on their thickness, impede the heat exchange. Predominantly carbonaceous deposits must also be frequently removed by washing with water, optionally using cleaning additives such as CuCl ₂ solution. Owing to the use of fuels containing ferrocene as additive according to the invention, the formation of deposits is greatly reduced. When, after a period of time, longer than is the case in the current state of the art, washing operations do become necessary (for example in dry docks), it has been found that after the use of fuels containing additives according to the invention, Its deposits can be removed more easily. The reason for this is to change the composition of the deposit. It was found that the deposit had a higher ash content, lower heating value and lower carbon content when compared to the deposit when using the fuel with the additive. The deposit appears to be less hydrophobic as it contains less oily or oil-like components.

Normally, such water washing of heat exchangers or boilers is carried out at the latest every two years when the ship is stationed in dry dock for prescribed maintenance and inspection work. However, under normal circumstances, between two dry docks, five or six additional wash operations are required. If the present invention is applied, this additional washing operation can be dispensed with.

The invention is further illustrated below by non-limiting examples and with reference to the accompanying drawings. Accompanying drawing 1, is to illustrate the exhaust path of the ship engine of above-mentioned class with diagram. This figure illustrates an engine (1) with all 10 cylinders (2). The exhaust gases from 3 or 4 cylinders, respectively, are combined in so-called exhaust gas "receptacles" ( 3 , 4 , 5 ) and fed to turbochargers ( 6 , 7 , 8 ). The exhaust gas streams leaving the turbocharger are brought together in the exhaust duct (9) and then passed through a so-called exhaust "boiler" (10) in which heat exchangers (11, 12, 13) are arranged, High, medium and low pressure steam can be generated from it. Exhaust leaves the system through a funnel (14).

The present invention has been successfully tested on a container ship, and the results are as follows:

Technical data of this ship:

60,000 registered tons

The technical data of its engine:

Output: 33,000kw

Cubic volume: 10 cylinders@1.6m ³

Speed: Max 90rpm

Turbocharger speed: about 10,000rpm

Consumption: about 6t/h under full load

In the initial state, the turbocharger of the marine engine was thoroughly cleaned by "soft jetting" and water washing. After about 3 months without any intermediate cleaning operation, the water washing operation was carried out. Although this water washing operation is not necessary from a technical point of view, since the vortex feeder works satisfactorily, it is performed to provide information on the degree of contamination (sediment). Although the current state of the technology requires "soft jetting" operations on a daily basis and water washing operations once a month, the wash water used during its operation is still heavily polluted 1 to 2 Hours, but in the present case, all cleaning operations have been dispensed with for about 3 months (85 days), but nonetheless, the wash water has remained transparent since the beginning. This leads to the conclusion that practically no deposits were formed during the period indicated. Even locations that cannot be reached with conventional cleaning methods show no or significantly reduced dirt deposition.

In the case of the heat exchanger, few deposits could be seen to be formed visually. Deposits that have formed can be removed more easily and quickly than was hitherto possible with water washing operations.

Furthermore, no deposits were visible visually on the piston rings and valves.

Claims (5)

1. A method of reducing carbon deposits resulting from the combustion of heavy residual fuel oil in a low-speed, high-compression, self-igniting internal combustion engine, which comprises heating the residual fuel oil with a density of 0.9 to 1.01 kg/dm prior to combustion of ^the residual fuel oil At least one additive selected from ferrocene, ethyl ferrocene, butyl ferrocene and 2,2-bis-ethyl ferrocene propane in an amount of 1 to 100 ppm added to the heavy residual fuel oil, Combustion of residual fuel oil containing at least one additive in a low speed, high compression, self-igniting internal combustion engine. 2. The method as claimed in claim 1, wherein the fuel oil containing at least one additive is combusted in a low-speed, high-compression, self-ignition internal combustion engine, and the exhaust gas produced by the combustion passes through a treatment unit arranged downstream of the engine; in the downstream treatment unit The carbon deposits produced in the 3. The method of claim 1, wherein the residual fuel oil containing at least one additive is combusted in an engine having a total power of 400 to 100,000 kW. 4. The method of claim 1, wherein the at least one additive is present in the fuel oil in an amount of 5 to 50 ppm. 5. The method of claim 1, wherein the speed of the internal combustion engine is 900 to 50 rpm.