NZ200454A - Proportional blending of high and low grades of fuel oils for i.c.engines - Google Patents

Description

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S.9.4, Reg.^WI) NEW ZEALAND 2 004 54 Fee: $55.00 Prioyity Date(s): Complete Specification Filed: <59 Class: Publication Date: ... ? P.O. Journal, No: .. J Insert number of Provisional Specification(s) (if any) and date(s) of filing; otherwise leave blank.

PATENTS ACT 195 3 Number: Date: COMPLETE SPECIFICATION t * 29 4*ceitS Insert Title kr Invention.

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FUEL BLENDING INSTALLATION X/WE STAR ENGINEERING APPLICATIONS LIMITED, a British company of Albion House, 30 James Street, Liverpool, England. hereby declare the invention for which I/we pray that a patent may be granted to me/us and the method by which it is to be performed, to be particularly described in and by the following statement:- Indicate if following — 1 — page is numbered '1(a)' ■•<1.5.80 200454 The present invention relates to a fuel blending installation.

It is known that the combustion efficiency of certain engines, in particular diesel engines, varies in dependence upon the load conditions. When operating- at a high load, the efficiency of burning in a diesel engine such as a marine diesel is 1 sufficiently high to enable the engine to operate satisfactorily from a lower grade fuel having a higher viscosity, herein termed "heavy oil". On the other hand, when operating under low load conditions, the combustion efficiency is considerably lower necessitating, the use of higher grade and more expensive fuel such as diesel oil.

In order to minimise running costs, it is known to change between heavy oil and diesel oil, depending on the load conditions. It is also known to provide a third tank containing an intermediate grade produced by mixing these .two grades of fuel. For example, the heavy oil may have a viscosity of 3»500 seconds, the diesel oil 30 seconds and the intermediate grade 300 seconds. However, this creates a problem of.requiring a further storage area for a third grade of fuel and there is an additional risk of the 300 second blend 200454 not producing a perfect mixture and separating out within the storage tank.

The invention is therefore concerned with blending installations which enable two grades of fuel to be blended to provide a grade of intermediate viscosity.

In accordance with the invention, there is provided a s fuel blending installation comprising a circulation pump; a circuit in which fuel is constantly recirculated by the circulation pump; means for introducing into the circuit controlled quantities of two fuels of different grades arid comprising two separate inputs each supplying an independent grade of fuel; and means, for connecting the circuit to a fuel consuming device such as an internal combustion engine; the circuit having a throttle device incorporated therein with a feed line to the fuel consuming device connected upstream of the throttle device and a return line from the fuel consuming device connected downstream of the throttle device.

By virtue of the fact that the fuel is being constantly recirculated in the closed circuit it is possible to ensure that the different grades do not separate out.

Advantageously, a heater is incorporated in the circuit to ensure that the fuel is at the correct temperature for the internal combustion engine. 200454 iv— Whenever high grade and low grade fuels are \ blended and applied to an engine there is. a risk that in the event of a failure .in various parts of the blending installation, a fuel of too high a viscosity will be fed to the engine.

With a view to mitigating the above disadvantage, there is also preferably provided a bypass line containing a valve which is arranged to open automatically in response to a failure within the blending installation to provide pure high grade fuel to the internal combustion engine. 2004|i *v The invention will now "be described further, by way of'example, with reference to the accompanying drawing, which is a block schematic diagram of a blending installation.

Although the invention will herein be described with reference to a marine installation, it will be appreciated that it is equally applicable to other installations, for example to generating sets and diesel powered locomotives.

•In a marine installation, it is common to utilise low grade fuel having a viscosity of, say, 3,000 seconds to operate the large slow speed diesels used for propelling. ' a ship. Such engines are designed to be able to cope with the slow burning heavy oil. A ship will often also include diesel engines to drive generators and these are traditionally run on high grade diesel oil from a separate tank. The installation in the accompanying drawings allows the engines to operate on pure diesel oil when the low load conditions so dictate, but also enables the engines to operate with a lower grade.blend under high load conditions to allow the running costs to be reduced without the provision 200454 # of a still further reservoir with- fuel of an intermediate grade.

In the accompanying drawing there is shown a diesel engine 10 which may for example-be part of a 5 generating set. The fuel for the diesel engine is contained in two reservoirs 12 and 14 which contain diesel oil and heavy oil, respectively. The diesel oil 12 is fed by way of a line 16 containing a metering pump 18 into a recirculation loop generally 10 ' designated 20. The loop comprises a recirculation pump 22, a static mixer,24, a heater 26, a. filter 28, a choke 30 and a second filter 32. A gravity feedline 34- connects the heavy oil reservoir 14- to the recirculation loop 20 in between the choke 30 and the filter 32. 15 A pressure relief valve 36 is connected in parallel with the metering pump 18 and a pressure relief valve 38 is connected in parallel .with the circulation pump 22. A supply line 40 for the engine pump is connected upstream of the choke 30 and a return 20 line 42 is connected downstream of the choke 30 in the direction of circulation.

A Bypass line 44 containing a solenoid valve 46 connects the line 16 from the diesel oil reservoir 12 via . loop, 20 to the supply pipe 40 of the engine 10. -i1 ■ (In 17 JAN 1986; 2 00454 The solenoid valve 46 is normally closed and only opens in the event of failure in one of the active elements of the recirculation loop 20.

In operation, fuel is supplied from the diesel oil reservoir 12 into the recirculation loop 20 by the metering pump 18 which meters a predetermined amount of fuel into the loop. In the loop, the fuel is constantly recirculated by the circulation pump 22 and reheated by the heater 26 to the correct viscosity. The static mixer 24 ensures proper mixing of the fuels by agitation.

Fuel is taken from the recirculation loop 20 by the supply line 40 of the engine and the fuel not consumed by the engine isr returned to the line 42. The purpose of the choke 30 is to ensure a drop in pressure to enable the fuel from the return line 4-2 to be reintroduced into the recirculation loop 20.

If the amount of fuel taken by the engine from the loop does not exceed the amount metered by the metering pump 18 then only diesel oil enters the recirculation loop and the pressure within the recirculation loop will not drop. Consequently, the neat diesel oil will be supplied to the engine.

As the engine loads increases so does the quantity of fuel consumed by the engine. .When 200454 the amount of fuel consumed exceeds the amount metered by the metering pump 18 the balance is . automatically introduced into the recirculation loop 20 from the heavy oil reservoir 14 through 5 the line 34 by gravity feed assisted by the pressure drop developed by the recirculation pump 22. Consequently, with increasing loads the quantity of fuel taken from the heavy oil reservoir 14 increases, so that as the efficiency 10 of the engine increases with increasing loads so is the viscosity increased to take advantage of the increased efficiency to burn cheaper gra'de fuel.

In -the event of a failure in the electric heater 26, the metering pump 18 or the pump 22, 15 the solenoid valve 46 is activated to bypass the blending unit and feed neat diesel oil to the engine 10. This ensures that fuel of too high a viscosity or too low a temperature is never supplied to the engine by the recirculation loop 20. 20 .In addition to the elements so far described, the installation includes a diesel oil counter 48 collected downstream of the metering pump to measure the total amount of diesel oil consumed. 200454 The pressure relief valves 36 and"38'serve to prevent a pressure "build-up in the recirculation loop 20.

A further advantage of the installation^ described is that without the use of a third reservoir an 5 intermediate grade of fuel is available. Furthermore, because the viscosity is constantly changed with engine loads it is possible always to make use of * the cheapest grade of oil appropriate for a given set of operating conditions.

• "When an engine has been running on cheap grade fuel it is preferable to run the engine on high grade fuel before shutting down in order to flush the system.. The described installation.. facilitates flushing in as much as when the ship enters port its 15 engines will have been reduced from full load and as a result will automatically be operating on higher grade fuel by the time it is desired to shut off the engines.

Claims (6)

200454 WHAT X/WE CLAIM IS:

1. A fuel blending installation comprising a circulation pump; a circuit in which fuel is constantly recirculated by the circulation pump; means for introducing into the circuit controlled quantities of two fuels of different grades and comprising two separate inputs each supplying an independent grade of fuel; and means for connecting the circuit to a fuel consuming device such as an internal combustion engine; the circuit having a throttle device incorporated therein with a feed line to the fuel consuming device connected upstream of the throttle device and a return line from the fuel consuming device connected downstream of the throttle device.

2. A fuel blending installation as claimed in claim 1 in which the circuit incorporates a heater.

3. A fuel blending installation as claimed in claim 1 in which the circuit additionally includes a static mixer. - 10 - 200454 t %

4. A fuel blending installation as claimed in any preceding claim, characterised in that the separate inputs are connected on different sides of the circulation pump with respect to the fuel consuming device which is in the form of an internal combustion engine and that means for introducing a higher grade fuel comprises a metering unit and supplies fuel to the input upstream of the pump, a lower grade fuel being supplied to the other input, whereby higher grade fuel alone is supplied to the engine under operating loads up to a predetermined threshold and above the threshold lower grade fuel is blended with the higher grade fuel to increase the proportion of lower grade fuel as a function of increasing load.

5. A fuel blending installation as claimed in any preceding claim having a bypass line connected in parallel with the blending means and incorporating a valve which is arranged to open automatically in response to a failure within the blending means to provide pure high grade fuel to the fuel consuming device.

6. A fuel blending installation constructed substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing. -11- J. D. HARDIE & CO. Patent Attorneys for the Applicant(s).