CA1128313A

CA1128313A - Long-cut fuel from light and heavy hydrocarbon of crude oil for i.c. injection engines

Info

Publication number: CA1128313A
Application number: CA306,942A
Authority: CA
Inventors: Jacques E. Lamy
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-07-07
Filing date: 1978-07-06
Publication date: 1982-07-27
Also published as: FR2396796A1; WO1979000029A1; JPS6219479B2; FR2396796B1; JPS5417904A

Abstract

D. 8904 Fuel for piston internal combustion injection engines Jacques Edouard LAMY Abstract of the Disclosure This invention is concerned with the use, in an internal combustion compression engine, of a fuel having the following features : a) in the standardized distillation testy distillation commences at about 30°C to terminate in the same range of temperature as conventional gas-oils for high-speed engines 9 b) in this same standardized distillation test about 90% of the volume passes into the eprouvette at a temperature lying between about 210 to 250°C and 360°C.

Description

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It is ~nown tha-t by distillation crude petroleum can be fractionated into a certain number of varied products which are distinguished fro,-n one another especially by their ~olatility.
In the feeding o~ internal combustion engines the fraction has been employed which i5 called in ~rance "essence"
and in the United ~tates "gasoline"~ in England "petrol", whioh thanks to its volatility enables carburetting of the air to be effected before its introductien into the engine cylinderS.
~ hen the Diesel cycle has enabled heavier frac-tions to be employed, such as gas-oil which is injected sepa-rately into the engine cylinders at the end of the phase of compression of the air and which ignites spontaneously tl~anks to the heat of compression.
; Hitherto ~ne has lived with this binary system of fuels and the corresponding two classes of engines.
~ or engines having carburettors where the air charged with fuel is compressed in the cylinders before igni-tion it is advisable for the fuel to have an-ti-detonating properties which have come to be characterized by the octane number.
~ he natural distillate from petroleum generally has a poor octane number which allows of only an equally poor degree of compression. In order to improve the performance of carburettor engines one is compelled to inorease this octane number by various artifices. One of them is the addition to the petrol of products such as tetra-ethyl lead which unfortunately is very poisonous and hence presents a serious disadvan-tage in relation to pollution. In addition i-t contri-butes to the fouling of engines by deposits of lead and to ;~ ~

corrosion of the valvesc ~nother arti~ice curren~tly applied in petroleum refineries consists in tal~ing fractions of~ tlle distillate wllich are heavier and ligh-ter -than petrol and in converting them by cracking or reforming operations in order to obtain hydrocarbons of aromatic or naphtene type having antidetonating properties~ which are mixed wi-th the petrol fraction in order to increase its octane number.
~ut this procedure, apart from -the fact that i-t necessitates complicated and costly apparatusg in-troduces losses resulting from -the fuel tha-t is burn-t for heating the apparatus and gives as residue gases which are generally burnt in a flare. r~hese losses may be evaluated at about 5~0 of the crude petroleum.
It is obvious that in the present economic situation these losses constitute a serious disadvan-tage.
On -the other hand Diesel engines have made consi-derable technical progress and today for the propulsion of motor vehicles even in -towns high-speed Diesel engines can be produced, having low weight, a certain flexibili-ty in running and being no-t very noisy.
~ he ~pplican~ has had the idea of replacing the two types of fuel by a single fue] called "long~cut" incor-porating light and hea,vy fra,ctions from crude petroleum, which is well suited to operation of modern Diesels a,nd par--ticularly ante-chamber Diesels so that this new fuel for piston engines should progressively replace the -two present fuels at the same time tha-t the Diesel engine would replace -the previous carburettor engine by making the disaavanta~es 3 called to mind above disappear7 since in particular for the Diesel engine there is no need of a high octane number.

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As -the Diesel engine has generally specific consumptions lo~er than -the petrol en~i~e one would acld -t~io sources of economyo one during the course o~ refining and the other in the operation of t~e engine. As the Diesel engine also enables easier fitting of an exhaust twrbo-compressor, progress along the pa-th of economy n~,ight bc made general thanks to a more universal fuel than gas-oil.
Since tllis new fuel will take part of the market for petrol in addition to tha-t for gas-oil it mus-t be widely available ~rom crude petroleum.
It will consist in its wiclest definition of the whole of the distillation fractions comprising gas-oil for high speed engines and lighter fractions the designa-tion of which varies bu-t in a conventional way comprises the kerosenes and the distillates sometimes called heavy and light naphtas, Hence it will comprise conventional gas-oil and -the sections available by distillation which dis-till at temperatures lower than those o~ the gas-oil cut.
~he new long-cut fuel which will be designated below by ~C for convenience of speech and which forms the object of the inventlonS is characterized mainly by the fol-lowing points D
a) in the standardized clistillation test, distilla-tion commences at about 30C -to terminate in the same range o~ temperature as that of conventional gas-oils for high~
speed engines 9 b) in -this same standardized distillation test about 90 of the volume passes in-to -the receiving vessel at a temperature lying be-t~een about 210 to 250C and 360C~
Such a, ~uel which represents about 50 to 60~o by volume of the crude petroleum ins-tead of 10 to 20~, as ., .

~ ~ _ --` 112~3 is the case for light gas-oil for motor vehicles, presents no-t only the advan-tages ~Jhich have been indicated but again, thanks to the presence of products heavier -t~an petrol, has a lubricating power sufficicnt for th.e proper operation of pumps 5 injectors and accesrsories~ whils-t containing vola-tile proclucts which facilita.te cold starting of Diesel engines.
It goes without saying that -this fuel is more available in crude petroleum than the present petrol for motor vehicles since the la-tter above all becau.se of the demand for an octane index9 re~luires special operations in prepara-tion and is not generally available by simple clis-tillation from the crucle excep-t in some special cases.
It is in adclition important to avoid -the possibi-lity of the fuel falling within the zone of ground-level explosivity which is characterized by the presence of suffi-; cient volatile hydrocarbons to result in an ambient saturated atmosphere which lies above the liquid fuel in a tank entering the zone of inflammability~ at least at ordinary temperature in normal geographical loca-tions~
~hus i-t is known that if on~ considers a -tank containing liquid pe-trol, even only in small amount 9 its atmosphere is generally too rich in vapour to ignite~ ~t least in temperate climates, that is to say9 those where ' the win-ter temperat~re is 'nigher than -20 a .
- 25 On -the other hand for kerosene and a fortiori gas-oil, the saturated atmosphere is too poor to ignite.
~ut if one is dealing with mixtures of lamp oil ?.
and petrol the saturated atmosphere in tanks may arrive at conditions for ignition, hence for deflagration ~nd for ' ~0 explosion.

In order not to complicate excessively -the com-., ~ ~ '' .

8 ~ ~ 3 mercial distribution o~ -the fuel in accordance with the in-vention it is advisable to make it comparable with petrol in its effect on ambient atmosphere~ consiaered.
To this end the fuel should contain a minimum of light hy~lrocarbons, this minimum bein~ c~laracterized by a minimum of Reid vapour ?res,ure or a minimurn of the ~ercentage distilling at low temperatures in the standardized distillation test.
This proportion of light hydrocarbons corresponds with a ~eid vapour tension higher than 50 piezes or 500 g/cm2 or possibly only higher than 35 to 40 piezes depending upon the local conditions of use.
A8 far as t!le minimum percentage dis-tilling at low temperatures is concerned the composition may be adapted so that 10~ of the volume dlstils below 70 or 75C, this limit depending upon the minimum atnlospheric -temperature in the geographical terri-tor~ of use.
~ rom another poi~t of view it is known that in order to avoid vapour locks in the :Eeed circuit to an engine and depriming of the feed pump9 it is advantageous for the `'t~eid vapour tension not -to exceed a certain value, for example 9 i in ~rance ancl o-ther temperate countries, 65 piezes in summer ! and 80 piezes in winter.
~he attached drawing shows by way of example the standardized distillation curve of a long-cu-t fuel in accor-dance with the inven-tion. Temperatures in degrees centigrade are plo-tted as ordina-tes and the percentages of product passing into the eprouvet-te a~re plotted as abscissae.
'~he point A represents the upper limit of tempera-tures corresponding with the condi-tion b above 9 whilst the points B and Bl corre~pond with the range of lower limit.
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~hc ~oin-t C corresponds wi.-th -the preserce of a minimum of volatile hyclrocarbons according to what has been said above.
Such a curve enables one sk-llled in -the art, -that is to say 9 specialists in the refining of petroleum, -to produce a fuel in accordance with the invention, starting with a crude of any origin.
'~hus it i9 possible to start9 in conventional manner~ by fr~ctiona-ting the crude, I or example 9 in a plate distillation colu~-n, then to recombine suitable proportions of the frac-tions thus separated in order to con.stitute the fuel in accordance with -the invention. The specialist in distillation will have no difiiculty in determining the sui-table proportions of -the various fractions. If the occasion arises, the gaseous hydrocarbons such as butane or -the pentanes may be dissolved in -the mixture.
The production yield by direc-t distil'La-tion of the new fuel results from -the f`ollowing tables in which the percen-tages of gas-oil and of -the new ~C fuel have been given, which may be obtained Wi-t}l crudes of different origins~ Petrol ~or motor vehicles are not set forth because it re~uires reprocessing of certain fractions and its availability depends both on the nature of the crude and the refining e~uipment available.
Amongst the problems posed by the refining of available crude petroleums, it may be :necessary to thermally break down (for example, by catalytic cracking) fractions of pe-troleums stocks heavier than gas-oils in order to avoid having too much of the heavy f'ractions~ In fact the market for these fractions might tend to diminish because of -the part , 30 -taken by the increasing emplo~men-t of atomic or e~en coal power s-tations and the use of -their residual hea-t. In these `~;

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circumstances the refiners woul~ be led to employ catalytic crackers for heavy products which can be adap~ted for -the production either of petrol of high octane number or of products in the ran~e known as gas-oils. Acloptio^n o~ the ~C
fuel will make these adaptations more flexible ~y enabling the use of prcducts of any ~ature. ~he use ar.cl the opera-tion of catalytic craci~ers~ hydrogenating or not, may be simplified by it and corresponding investments reduced.
Crude Arabian Heav~l~rabian Medium ~rabian ~i~ht % gas-oil 16% 18 20 ~a 430~0 50 60 ~ an ~assan % gas-oil 14 20 % ~C 55 55 Al~eria ~'lessaoud o,b gas-oil 2 '~ ~C 7~
Kuwait % gas-oil 14 20 r~o LC 42 Irak Qatar Zakum ~O gas-oil 10 18 20 19 /o ~C 50 50 '70 63 It is known tha-t the combustion of gas-oils in Diesel engines leads to -the use of minimum cetane index in order to avoid knocking in these engines. r~'his resul-ts from a property which is the reverse of lack of explosiveness o~
petrols for controlled igni-tion engines. 'i~here will be no reason to change it in the developmen-t of -the use of ~C.
It is possible in order -to expedite ref'ining, to specify a maximum con-tent of aromatic carbons 9 for example, 20 or 25,~" in order -to obtain a product giving less knocking and a minimum of smoke in the exhaust.
~ 'he maximurl ternperature point A (350) ~or the 90% point on -the distill~tion curve corresponds likewise ensures that the hyclrocarbons are not too heavy9 so as to cavse deposits and smoke on combustion. '~'he temperature 360C
corresponds to a sligh-t increase in gravity in comparison with conventional gas-oils. It might be raised by the use of light fractions in the "long-cut" fuels.
The requiremen-ts regarding sulphur content ~J-ill be preserved as for conventional gas-oils intended ~or use in motor vehicles, ~hey will generally be more easy to meet for refining because the na-tural sulphur content often increases with -the density of the distilla~tion cuts. It follows that it is possible -to minimize the maximum sulphur con-ten-t of -the "long-cut" f'uel relative to -that of` conven-tional gas-oils.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fuel designed for injection into a reciprocating internal combustion engine, said fuel consisting essentially of a stock containing light and heavy hydrocarbons present in crude oil, characterized by the following A.S.T.M. distillation specifications:
(a) the light-hydrocarbon content is such that 10% of the volume distills at a temperature lower than about 75°C., and the Reid vapor pressure is higher than 35 piezes;
(b) about 90% of the volume is collected at a temperature ranging between a lower limit of about 210°C. and an upper limit of about 360°C.;
and (c) the final distillation is in the same temperature range as conventional gas-oil for current automotive engines.

2. The fuel of claim 1, characterized in that said light-hydrocarbon content is such that the Reid vapor pressure is higher than 50 piezes.

3. The fuel of claim 1, characterized in that said light-hydrocarbon content is such that the Reid vapor pressure is less than about 80 piezes.

4. The fuel according to claim 1, 2 or 3, characterized in that the maximum aromatic hydrocarbon content is of the order of 20 - 25%.

5. The fuel of claim 1, characterized in that (a) the light-hydrocarbon content is such that 10% of the volume distills at a temperature lower than about 70°C., and (b) about 90% of the volume is collected at a temperature ranging between about 250°C and about 360°C.