GB2143846A - A diesel fuel based on methanol and/or ethanol - Google Patents

Abstract

A diesel fuel comprising at least 85% v of methanol and/or ethanol, a small proportion of an ignition improver and as lubricity improver less than 0.05% w of a polyglycol fluid having the formula RO-(CH2-CHR'-O)xR'' wherein R and R'' are hydrogen or C1 to C4 alkyl groups, R' is hydrogen or a C1 to C4 alkyl group and x is 35 to 480.

Description

SPECIFICATION A Diesel Fuel Based on Methanol and/or Ethanol This invention relates to a diesel fuel, based on methanol and/or ethanol and containing an ignition improver and a lubricity improver and to a method of operating a diesel engine using such a fuel.

It has been found that the use of methanol and/or ethanol containing an ignition improver as a fuel in diesel engines as described in e.g.

European patent application 30429 suffers from the drawback that it has insufficient lubricity properties, resulting in serious wear in the high pressure fuel injection pump and in the injector nozzles, in particular in the needle guides, needle seats and spring plate seats of the diesel engine.

In these areas the fuel normally acts as a lubricant, however, the light alcohols have insufficient lubricity for this purpose.

Therefore there is a need for lubricity improving additives for such fuels.

It has now been found that very small proportions of certain polyglycol fluids are effective as lubricity improver in these fuels. In, these small proportions the polyglycol fluid does not function as ignition improver.

This invention therefore relates to a diesel fuel comprising at least 85% v of methanol and/or ethanol, a small proportion of an ignition improver and as lubricity improver less than 0.05% w of a polyglycol fluid having the formula RO(CH2CHR' )xR" wherein R and R" are hydrogen or C1 to C4 alkyl groups, R' is hydrogen or a C1 to C4 alkyl group, preferably hydrogen, and x is 35 to 480.

From British patent specification 1 591,398 the use of 2 to 40 parts by weight of polyglycol fluids per 100 parts by weight of methanol as cetane number or ignition improver for diesel engines is known. The present small proportions of polyglycol fluid are not disclosed in this literature.

The fuel according to the present invention may wholly consist of the alcohol. Other additives may be present such as corrosion inhibitors, antioxidants etc.

Suitable ignition improvers are e.g. nitrogencontaining compounds as described in European patent application 30429, such as polyethylenglycol dinitrates. Excluded as ignition improvers are the present polyglycol fluids.

The proportion of the lubricity improver is preferably 0.005-0.05 %w.

In the above formula of the polyglycol x is preferably 100--250.

The polyglycol preferably is a copolymer of ethylene oxide and propylene oxide. Suitable molecular weights are between 1,000 and 7,000, preferably between 2,000 and 4,000 and suitable viscosities are between 100 and 2,000 cS at 380C, preferably between 200 and 500 cS at 380C.

Example A polyglycol fluid being a copolymer of 25 %w propylene oxide and 75 %w ethylene oxide, wherein x is 204 and having a viscosity of 375 cS at 380C (Oxylube 25/375) was added in proportions of 0.005 and 0.01 %w to methanol and compared with methanol containing 1 %w castor oil as lubricity improver and with a medium gas oil as diesel fuel according to the following method.

The principle of the method was to rub together two cylindrical steel specimens, one rotating the other stationary. The coefficeint of friction and scuffing characteristics were monitored as the load was increased in stages.

The specimens were fully immersed in fuel which was continually replenished. A test was terminated on the occurence of gross seizure, detected by an increase in coefficient of friction and noise. The wear scars were examined after test to determine the load at which scuffing first occured.

Results for the fuels were obtained as scuffing failure load in kg and are summarized below: Scuffing failure load Fuel (kg) Medium Gas Oil 125 Methanol 100 Methanol+ 1 % Castor Oil 125 Methanol+0.005 %w Oxylube25/375 100 Methanol+0.01 %w Oxylube 25/375 150

CLAIMS 1. A diesel fuel comprising at least 85 %v of methanol and/or ethanol, a small proportion of an ignition improver and as lubricity improver less than 0.05 %w of a polyglycol fluid having the formula RO(CH2CHR'Q)xR" wherein R and R" are hydrogen or C1 to C4 alkyl groups, R' is hydrogen or a C1 to C4 alkyl group and x is 35 to 480.

2. A fuel according to claim 1 , wherein the proportion of polyglycol is 0.005-0.05 %w.

3. A fuel according to claim 1 or 2, wherein x of the polyglycol is between 100 and 250.

4. A fuel according to any one of claims 1-3, wherein the polyglycol is a copolymer of ethylene oxide and propylene oxide.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A Diesel Fuel Based on Methanol and/or Ethanol This invention relates to a diesel fuel, based on methanol and/or ethanol and containing an ignition improver and a lubricity improver and to a method of operating a diesel engine using such a fuel. It has been found that the use of methanol and/or ethanol containing an ignition improver as a fuel in diesel engines as described in e.g. European patent application 30429 suffers from the drawback that it has insufficient lubricity properties, resulting in serious wear in the high pressure fuel injection pump and in the injector nozzles, in particular in the needle guides, needle seats and spring plate seats of the diesel engine. In these areas the fuel normally acts as a lubricant, however, the light alcohols have insufficient lubricity for this purpose. Therefore there is a need for lubricity improving additives for such fuels. It has now been found that very small proportions of certain polyglycol fluids are effective as lubricity improver in these fuels. In, these small proportions the polyglycol fluid does not function as ignition improver. This invention therefore relates to a diesel fuel comprising at least 85% v of methanol and/or ethanol, a small proportion of an ignition improver and as lubricity improver less than 0.05% w of a polyglycol fluid having the formula RO(CH2CHR' )xR" wherein R and R" are hydrogen or C1 to C4 alkyl groups, R' is hydrogen or a C1 to C4 alkyl group, preferably hydrogen, and x is 35 to 480. From British patent specification 1 591,398 the use of 2 to 40 parts by weight of polyglycol fluids per 100 parts by weight of methanol as cetane number or ignition improver for diesel engines is known. The present small proportions of polyglycol fluid are not disclosed in this literature. The fuel according to the present invention may wholly consist of the alcohol. Other additives may be present such as corrosion inhibitors, antioxidants etc. Suitable ignition improvers are e.g. nitrogencontaining compounds as described in European patent application 30429, such as polyethylenglycol dinitrates. Excluded as ignition improvers are the present polyglycol fluids. The proportion of the lubricity improver is preferably 0.005-0.05 %w. In the above formula of the polyglycol x is preferably 100--250. The polyglycol preferably is a copolymer of ethylene oxide and propylene oxide. Suitable molecular weights are between 1,000 and 7,000, preferably between 2,000 and 4,000 and suitable viscosities are between 100 and 2,000 cS at 380C, preferably between 200 and 500 cS at 380C. Example A polyglycol fluid being a copolymer of 25 %w propylene oxide and 75 %w ethylene oxide, wherein x is 204 and having a viscosity of 375 cS at 380C (Oxylube 25/375) was added in proportions of 0.005 and 0.01 %w to methanol and compared with methanol containing 1 %w castor oil as lubricity improver and with a medium gas oil as diesel fuel according to the following method. The principle of the method was to rub together two cylindrical steel specimens, one rotating the other stationary. The coefficeint of friction and scuffing characteristics were monitored as the load was increased in stages. The specimens were fully immersed in fuel which was continually replenished. A test was terminated on the occurence of gross seizure, detected by an increase in coefficient of friction and noise. The wear scars were examined after test to determine the load at which scuffing first occured. Results for the fuels were obtained as scuffing failure load in kg and are summarized below: Scuffing failure load Fuel (kg) Medium Gas Oil 125 Methanol 100 Methanol+ 1 % Castor Oil 125 Methanol+0.005 %w Oxylube25/375 100 Methanol+0.01 %w Oxylube 25/375 150 CLAIMS

1. A diesel fuel comprising at least 85 %v of methanol and/or ethanol, a small proportion of an ignition improver and as lubricity improver less than 0.05 %w of a polyglycol fluid having the formula RO(CH2CHR'Q)xR" wherein R and R" are hydrogen or C1 to C4 alkyl groups, R' is hydrogen or a C1 to C4 alkyl group and x is 35 to 480.

2. A fuel according to claim 1 , wherein the proportion of polyglycol is 0.005-0.05 %w.

3. A fuel according to claim 1 or 2, wherein x of the polyglycol is between 100 and 250.

4. A fuel according to any one of claims 1-3, wherein the polyglycol is a copolymer of ethylene oxide and propylene oxide.

5. A fuel according to claim';1, substantiallt as hereinbefore described.

6. A method of operating diesel engine using a fuel as claimed in any one of claims 1--5;