GB2509938A

GB2509938A - Biodiesel processor

Info

Publication number: GB2509938A
Application number: GB1300887.5A
Authority: GB
Inventors: Robert Graham Beardwell; Allan Grainger
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-01-17
Filing date: 2013-01-17
Publication date: 2014-07-23
Anticipated expiration: 2033-01-17
Also published as: GB201300887D0; GB2509938B

Abstract

An automated method and apparatus for generation of biodiesel from vegetable oil. The generator includes at least three tanks for containing: A. vegetable oil feedstock; B. methanol; and C. glycerol by-product, respectively, together with a dry wash for the product biodiesel. The respective tanks are preloaded with pre defined quantities of vegetable oil feedstock; methanol; and sodium hydroxide or potassium hydroxide. Dry sodium or potassium hydroxide is swept from a feeder compartment into the methanol tank B. Pre-programmed controllers automate every stage of the operating sequence without operator intervention.

Description

BIODIESEL PROCESSOR

Field of the Invention

This invention relates to an automated biodiesel generator and a method of operating such a generator. The process is particularly suitable for domestic and small scale operation, so that each user of biodiesel fuel can generate their own supply.

Background of the Invention

Biodiesel is a clean, safe, ready-to-use, alternative fuel which runs in any diesel engine without modification.

Biodiesel. is made from vegetable and animal oils and fats, or triglycerides. Biodiesel cannot be made from any other kinds of oil (such as used engine oil) Chemically, triglycerides consist of three long-chain fatty acid molecules joined by a glycerine molecule. The biodiesel process uses a sodium hydroxide or potassium hydroxide catalyst (lye) to break off the glycerine molecule and combine each of the three fatty-acid chains with a molecule of methanol, creating mono-alkyl esters, or Fatty Acid Methyl Esters (FAME) -biodiesel. The glycerol by-product sinks to the bottom and is removed. The process is called transesterification.

Most domestic biodiesel producers make biodiesel with used vegetable oil collected from restaurants and takeaway shops but the process for using used oil is somewhat more difficult and labour intensive than using virgin vegetable oil. Used vegetable oil must first be dc-watered by settling or heating to evaporate the water content and it must then be filtered or settled to remove particulate contaminants such as food. Used oil must be titrated to determine how much KOM is required to facilitate the transesterification process. All of this must be done before starting the biodiesel process. Virgin oil does not reguire dc-watering, filtering or titration. Commercial producers use virgin oil.

The process of making biodiesel can be carried out with anything from pots and pans to elaborate processors. Many manually operated processors are readily available on the open market and there are a few portable semi-automated processors available for purchase. The large commercial biodiesel producers use factory-sited refinery type installations.

The benefits of making fuel at home are often outweighed by the labour intensive process of firstly collecting and storing the used oil from restaurants and take away shops, besides which, due to the recent surge in popularity of home biodiesel production, many restaurants and take away shops have started charging for supplying the used oil.

The process itself is also labour intensive and requires a regular attendance to initiate the various stages of production until completion.

Manually operated processors require the producer to manually load all ingredients into the processor at the required stages of the process, which in itself can be messy and hazardous. Producer attendance and input is required throughout the entire process, such as turning the pump, heater and valves on and off at the required intervals. rater wash systems require the producer to connect and disconnect a garden hose to the processor and leave a volume of contaminated water to be disposed of.

Dry wash systems are readily available but the equipment and medium costs are to be considered by the small domestic producer as well as the oil collection and preparation process. The glycerol waste product must be manually separated and stored or ecologically disposed of. A whole weekend could easily be consumed in the whole process of collection, preparation and production of a small quantity of biodiesel. Many first time producers are often attracted to the apparent low cost of home brewing' but are soon deterred when the true cost of labour time, equipment and ingredients is considered.

There are several semi-automatic biodiesel processors on the market such as Green Fuel Ltd's fuelpod" (Registered Trade Mark) and the family of processors sold by Parksmith Limited t/a OnestopBioshop under the BioBuddy' brand.

These processors are automated in the sense that the heater, pumps and valves are operated electrically, but these processors require the frequent attendance and input of the producer by way of manually loading the necessary ingredients at the required stages of the process, connecting and disconnecting a water supply and disposing of contaminated water. The various stages of production also require initiation by the producer pushing a button or switch at the required moment in the cycle. The glycerol waste product must be manually extracted from the processor and stored or ecologically disposed of prior to the washing sequence.

Summary of the Invention

We have now developed a fully automatic biodiesel processor for which no producer (user) input is required after the process start button has been pressed.

All ingredients are held in separate tanks and compartments until the process is initiated. No producer loading of ingredients is required as the ingredients can be loaded into the appropriate tanks and compartments by the time of delivery. The producer needs to provide only a suitable location for the processor, which can be operated from a domestic electricity supply :he automated process brings the ingredients together only at the correct stage of the process.

Separation of the glycerol waste by-product is effected automatically by drainage into a dedicated holding tank.

The processor is suitable for dry washing of the biodiesel product. Air that is bubbled through the unwashed biodiesel is firstly passed through a water desiccant to ensure that no water at all is introduced to the process.

Methanol recovery is achieved by an evaporation and condensation process and the resulting condensate is collected in a holding tank where it is stored until the processor is returned to the depot where it is removed and re-cycled.

According to one aspect of the present invention, we provide a transportable, automatic biodiesel generator including at least three tanks for containing: (i) vegetable oil feedstock; (ii) methanol; and (iii) glycerol by-product, respectively.

According to another aspect of the present invention, we provide a method of generating biodiesel which comprises delivering to a user's premises an automatic generator including at least three tanks for containing: (i) vegetable oil feedstock; (ii) methanol; and (iii) glycerol by-product, respectively, wherein the respective tanks have been preloaded with pre-defined guantities of vegetable oil feedstock; methanol; and sodium hydroxide or potassium hydroxide.

Preferably, the biodiesel generator includes dry wash means for the biodiesel product. In a preferred configuration, a user-activated dispensing nozzle draws the biodiesel product from the feedstock tank and the biodiesel product passes through dry wash means intermediate the feedstock tank and the dispensing nozzle.

Advantageously, the methanol tank is associated with a feeder compartment adapted to discharge dry sodium hydroxido or dry potassium hydroxido into tho liquid methanol during operation. Preferably, the feeder compartment is located above the methanol tank and a rotary drive urges the sodium hydroxide or potassium hydroxide to drop into the methanol. Typically, the rotary drive comprises at least one paddle or brush but may also be a rotating disc or an Archimedean screw.

The feeder compartment may include a baffle preventing discharge of the sodium hydroxide or potassium hydroxide into the methanol unless the rotary drive is activated.

By-product glycerol is separated from the biodiesel product by gravity drainage and stored in the holding tank.

Preferably, the biodiesel generator includes a condenser for methanol vapour discharging condensate into the methanol tank. In operation, (a) dry air is bubbled through heated biodiesel product to entrain residual methanol; and (b) exhaust air passes through the condenser to discharge methanol vapour condensate into the methanol tank.

The generator is particularly suited to include pre-programmed controllers automating every stage of the operating sequence. In particular, the generator may include a control panel in which the only user-operable controls are a start switch and a stop switch. Ihe stop switch may also include a reset function. Preferably, the generator includes valve-controlled flow connections between the tanks. Normally, the valves are activated in sequence by timed commands from the pre-programmed controllers.

A generator according to the invention is suitable to be hired, leased or lent to the end-user for them to generate their own biodiesel. The supplier preloads the separate tanks, including an hydroxide feeder compartment, with pre-defined quantities of the respective ingredients, either at the supplier's premises or as part of the delivery to the user. After use, the generator is made available to the supplier, either by the supplier collecting the generator or at the user's premises, for the purposes of the supplier's: (a) cleaning the generator and disposing of the by-product glycerol; and (b) recharging the respective tanks with vegetable oil and other ingredients in preparation for the next operating cycle.

Brief description of the Drawings

Figures 1 to 4 are overall views of a biodiesel generator according to the present invention, from the front, rear, left side and right side respectively; Figure 5 shows a mixing paddle for the methanol tank; and Figure 6 is a flow diagram of the automated stages of an example of biodiesel produotion, following aotivation of the process.

SDescription of an Embodiment

A biodiesel generator according to the invention (also referred to as a processor) comprises three interconnected closed tanks: A. Feedstock tank, which also serves as a reaction chamber for the transesterification reaction and as the storage tank for the biodiesel product; B. Methanol tank, in which potassium hydroxide is mixed with methanol to produce methoxide; and C. Glycerol storage tank.

A heater 10 is mounted within Tank A. The conical bottom 11 of Tank A drains directly by gravity into Tank C. Tank A is also connected to a static mixer 12 and a dry wash tower 13.

A compressor 30 can blow air through a desiccant 31 and then as a bubbling airflow through Tank A. Exhaust from Tank A is fed through a cooling fan and radiator assembly 32 to condense out methanol vapour from the exhaust air stream. The condensate is discharged into Tank B. A user-activated dispensing nozzle 14 draws biodiesel product from the outlet of dry wash tower 13. A filter 15 is incorporated in the flow line between dry wash tower 13 and dispensing nozzle 14.

:ank B has a detachable lid 20, which is also a feeder compartment for granular potassium hydroxide. Part of the base of lid 20 is a grating. A mixer 21 is mounted on lid 20. As shown in more detail in Figure 5, mixer 21 comprises a rotating shaft 22 on which are mounted an upper set of paddles 23 and a lower mixer paddle 24. The upper paddles 23 bear brush strips 23A. Shaft 22 passes through lid 20 and is supported by bearings 25 at appropriate locations along its length.

The interconnecting pipework and tank vents are associated with various valves and circulating pumps. The valves and pumps are activated by a processor and control panel (not shown.

The processor may be mounted on a stand and enclosed within an outer casing (not shown) In detail:

Processor description

Tank A Dimensions: 950mm diameter 900mm high (excl. conical bottom) Volume: 720 litres Construction: 6mm HDPE with welded joints.

Features: Closed top, conical bottom.

is Holes: 50mm filling hole (oil in) in closed top with screw cap.

25mm vent hole in closed top.

70mm reinforced hole in side for flange fitted immersion heater (10) 12 inch BSP threaded reinforced collar hole in conical bottom.

1 inch BSP threaded reinforced collar hole in top side.

Functions: Main holding tank, heating tank, circulation tank, settling tank and evaporation chamber.

Tank B Dimensions: 450mm diameter 750mm high (md. lid compartment 50mm) Volume: 120 litres Construction: 6mm HDPE with welded joints.

Features: Detachable compartmented lid (20) with partially grated base, attached potassium hydroxide filling tube (26), sealing flanges to lid and top of tank with nitrile vapour sealing ring between flanges of lid and bin and 3mm steel clamping rings to top and underside of lid and tank flanges secured with bolts, nuts and washers to eliminate vapour escape.

Holes: 12mm hole in centre top of lid for mixer shaft (22) 25mm hole in top of lid for loading methanol and condensate.

25mm hole in top of lid for venting.

25mm hole in side (u/s lid flange) for extraction of methoxide and condensate.

Functions: The lid (20) is a holding chamber for the potassium hydroxide, which is prevented from mixing with the methanol by the un-grated portion of the lid base being located directly beneath the potassium hydroxide loading tube (26) . The potassium hydroxide is retained in this location by the upper mixer paddle arms (23) until the mixer (21) is started. The tank is the holding tank for the methanol and then later the condensate methanol. When the mixer (21) is started the potassium hydroxide is brushed through the partially grated lid base into the tank by the upper mixer paddle (23) and mixed with the methanol by the lower mixer paddle (24) to produce methoxide. ank C

Dimensions: 400mm wide 400mm deep 750mm high Volume: 120 litres Construction: 6mm HDPE with welded joints.

Features: Closed top.

Holes: 25mm hole in closed top for venting.

25mm hole in side (top) for filling.

25mm hole in side (bottom) for draining.

Functions: Glycerol holding tank. Glycerol enters the tank at the top filling hole by gravity upon the opening of valve #3. The glycerol is later drained from the tank by attaching an auxiliary pump to the bottom drain hole with the manually operated valve.

The Stand (not shown) The stand is constructed from 3mm x 40 mm steel box section with welded joints and is designed to support tank A above tanks B and C. Tanks B and C both fit under tank A to give an overall standard pallet sized foot print of 1200mm x 1200mm.

The cooling assembly support frame is constructed from 40mm x 40mm x 3mm steel angle section and is welded to the box section stand body as is the valve and circulating pump support frame.

The Control Panel (not shown) The control panel is a detachable sealed metal box measuring 600mm x 600mm x 200mm and is connected to the processor via a 5 meter umbilical cable which plugs into an on-board terminal block where all electrical components are wirod.

The control panel consists of a control relay unit and extension relay unit, 24v power supply, contactors and control switches to the processor eguipment, 12v power supply for the cooling fan, two thermocouples and signal conditioners for the thermostatically triggered operations and a fuse board.

-10 -The integral timer relays are used to control the on/off functions of the on-board equipment as described below and shown in Figure 6.

The external components of the control panel are: A green start button A red reset/stop button (recessed) A green process running light A red process complete light.

The Heater (not shown) The heater is a 27" stainless steel 240v single phase 3kw immersion heater with integral dual safety thermostat set at 65°C, side mounted 1/3 of the way up the side of tank A at the designated reinforced 70mm hole, fixed by means of a flange ring fitting.

The first heat cycle is controlled by the relay unit via a 24v switch in the control panel and is firstly initiated by the green start button on the control panel. Thermocouple #1 detects when the oil temperature of 55°C is reached and the designated signal conditioner instructs the relay unit to switch off the heater.

The second heat cycle is controlled by the relay unit via a 24v switch in the control panel and is initiated by the relay unit's integral timer. The set oil temperature of 65°C is maintained by thermocouple #2 connected to a designated signal conditioner within the control panel and switches the heater on and off as required. This second heat cycle end is also controlled by the relay unit's integral timer.

The Mixer The mixer (21) is a 240v single phase 1050 watt variable speed paddle mixer and is mounted directly on top of tank B lid, held in situ by the upper paddle (23) resting on the base of the tank B lid (20) and restrained against reinforcing pads on the side of tank A by a cargo retaining -11 -strap secured around the girth of tank A. Activation of the mixer is triggered by the start button and is switched off by the relay unit's integral timer.

The mixer shaft (22) is 12mm stainless steel which passes through the centre of tank B lid (20) with two sealed bearings (25) at the entry and exit points of the lid (20); the shaft extends to within 20mm of the bottom of tank B. The upper paddle (23) is attached to the mixer shaft (22) by way of a four winged collar with locking grub screw.

The four upper paddle blades (23) are 6mm HDPE 40mm wide and extend from the mixer shaft collar to within 10mm of the sides of tank B lid (20) forming four quarter section compartments within the lid (20) . Brush strips (23A) are fixed to top, bottom and ends of each paddle blade to prevent premature mixing of the potassium hydroxide with the methanol and to facilitate thorough dispersion of the potassium hydroxide around the grilled base of tank B lid (20) . The lower mixing paddle (24) is a 4" HDPE, 4 blade propeller attached to the end of the mixer shaft by way of a 12mm threaded bolt.

As the mixer shaft (22) rotates the potassium hydroxide is swept across the grated surface of the lid bottom (20) where it falls into the swirling methanol and is mixed together by the lower mixing paddle (24) Ihe Circulation Pump The circulation pump is a 240v single phase 401pm vane pump, its function is to circulate the contents of tank A and also pump the biodiesel from tank A to the dry wash tower (13), through the final filter (15) and out of the dispensing nozzle (14) . The on/off activation of the circulation pump is controlled by the start button, the relay unit's integral timers and the dispensing nozzle's trigger switch accordingly.

Ihe Compressor Ihe compressor (30) is a 240v single phase 251pm unit which serves to introduce a small bubbling airflow through -12 -tank A during the methanol evaporation prooess. The air is directed through a water desiccant (31) prior to entering tank A to ensure that no water content is introduced to the process. The activation and dc-activation of the compressor is achieved by the relay unit's integral timers.

The Methanol Pump The methanol pump is a 240v single phase compressor operated AlEX approved diaphragm pump suitable for use with combustible liquids.

The pump is activated and dc-activated by the relay unit's integral timers. The pump draws the prepared methoxide from tank B and into circulation of tank 7k.

The Dry Wash Tower The dry wash tower (13) is a 9" diameter, 1.6m tall stainless steel oylinder. The internal oomponents are two grated steel retaining plates, one top and one bottom plate held apart by a l.3m threaded steel rod. Each retaining plate is covered by a tight fitting 5 micron filter sheet.

The lower retaining plate sits on an internal flange on the inside of the steel cylinder. The void between the two retaining plates is filled with hardwood sawdust which removes moisture and particulate contaminants from the unwashed biodiesel. The biodiesel is pumped into the cylinder via the bottom 25mm entry hole and is forced up through the filter sheet and retained sawdust and out through the top 25mm outlet to the final filter (15) The cylinder lid is screw clamped to the cylinder body to withstand the pump pressure and for easy dismantling and servicing, and to renew the contaminated sawdust at given intervals.

The Final Filter -13 -The final filter (15) is a 1 micron cylindrical cotton reel ceramic-based filter housed in a HDPE cylindrical housing secured to the stand frame support.

The washed fuel is passed through this final filter as it is directed to the dispensing nozzle (14) The Cooling Fan and Radiator Assembly (32) The cooling fan is a 12v twin fan assembly attached to a 600mm x 400mm radiator. The cooling fan is activated and dc-activated by the relay unit's integral timers.

Evaporated methanol enters the top inlet of the radiator, cooled by the twin fans and then exits the lower outlet of the radiator and directed to the condensate collection tank (tank B) . All pipe work along the evaporation and condensing system is 22mm copper with soldered joints.

The Valves The valves are all 24v do actuated steel ball valves and are activated by the start button and the relay unit's integral timers accordingly.

Each valve is powered for 12 seconds at each designated signal which allows the steel ball valve to rotate of a turn. Thus, opening and closing is achieved by repetition of signals from the relay control unit.

The outer casing (not shown) The outer casing is aluminium sheet construction with all joints sealed to facilitate the necessary bunding reguirements. All sides are vented above 900mm (bund line) The base is thickened aluminium and is shaped to accommodate a standard pallet truck. The front panel is completely removable to allow the processor to be withdrawn from the casing for servicing. The processor stand is placed and secured on a roller tray within the base of the outer casing. The casing is recessed to house the detachable control panel and the dispensing nozzle (14) -14 -

Process description (see Figure 6)

The processor is transported from a delivery vehicle to the designated location by means of a pallet truck inserted into the specifically designed base of the outer casing.

The processor is safely sited level and plumb by way of screw jack legs attached to the outer casing 500 litres of virgin vegetable oil is loaded into tank A. litres of methanol is loaded into tank B. 2.75 kg of potassium hydroxide is loaded into tank B lid compartment (20) The power cable is plugged in to a 240v single phase domestic socket.

The start button on the control panel is then pushed.

From this point no further user intervention is reguired.

The heater (10) is switched on.

The circulation pump (pump #1) is switched on.

Valve #1 is opened to circulation.

The mixer (21) is switched on.

The circulating oil is heated to 55CC (approx 3hours) The mixer (21) in tank B is timed to run for 2 hours. As the upper paddle (23) on the mixer shaft (22) rotates it brushes the potassium hydroxide through the dispensing grill in the base of tank B lid (20) and into tank B where the lower paddle (24) of the mixing shaft (22) mixes the potassium hydroxide with the methanol to produce methoxide.

After 2 hours the mixer is switched off.

Once the oil has reached 55°C The heater (10) is switched off.

The methoxide pump (pump #2) is switched on.

Valve #2 tank B to A is opened.

The circulation pump (pump #1) remains on.

-15 -Valve #1 to circulation remains open.

The heater (10) is switched off by thermocouple #1 to avoid further heating beyond 55°C and to allow safe

introduction of the methoxide to the heated oil.

The methoxide pump draws the methoxide from tank B to the circulating heated oil in tank A via valve #2. The methoxide pump is timed to run for 5 minutes until the methoxide is completely drawn from tank B. The methanol pump is then switched off and valve #2 is then closed.

The oil and the methoxide are left to circulate tank A for 2 hours. The circulating oil and methoxide is drawn from the conical bottom (11) of tank A, through 1172 inch pipe work by the circulation pump via valve #1, and pumped through a set of reduced bore vertical static mixer pipes (12) to a top entry into tank A where it is reintroduced to circulation. This circulation process ensures thorough mixing of the oil and methoxide at the optimum temperature.

After the timed 2 hours of circulation the circulation pump is switched off and the oil and methoxide mixture is left to settle for a timed 6 hours for the transesterification process to take place.

After 6 hours of settling time; Valve #3 from tank A to tank C is opened.

Valve #1 to circulation remains open.

The transesterification process has completed and the contents of tank A have separated leaving unwashed biodiesel on top of the settled glycerol by-product. Valve #3 is opened to allow the glycerol to gravity drain from the conical bottom (11) of tank A into tank C. A fluid density sensor within the pipe work to tank C detects the difference of density between the glycerol by-product and the unwashed biodiesel and closes valve #3 leaving only the unwashed biodiesel in tank A. After the glycerol is drained; The heater (10) is switched on.

The circulation pump (pump #1) is switched on.

-16 -Valve #1 to circulation remains open.

The unwashed biodiesel in tank A is then heated to 65°C to enable the evaporation process of the remaining methanol content within the unwashed biodiesel.

Once the unwashed bi.odiesel reaches 65°C The cooling fan (32) is switched on.

The compressor (30) is switched on.

The heater (10) remains on (to 65°C) The circulation pump remains on.

Valve #1 to circulation remains open.

The temperature of the unwashed biodiesel is maintained at 65°C by thermocouple #2 for a timed 5 hours. At 65°C the remaining methanol content is evaporated through the vent at the top of tank A, through 22mm copper pipe work, into the radiator and cooling fan assembly (32) where the methanol vapour is condensed and run through further 22mm pipe work to the empty tank B (now serving as a condensate collection tank.) Tanks B and C are both vented via a separate dedicated vent pipe of 22mm copper venting out of the top of the outer casing.

The compressor (30) is activated to introduce gently bubbling air into the bottom of tank A during the evaporation process. As the air is bubbled up through the heated unwashed bicdiesel the air is in turn heated and thus facilitates the methanol vapour release from the unwashed biodiesel. The air is vented to outside via tank B vent pipe.

After 5 hours of the evaporation and condensing process The cooling fan (32) is switched off.

The compressor (30) is switched off.

The heater (10) is switched off.

The circulation pump is switched off.

Valve #1 to circulation is closed.

-17 -Valve #4 tank A to wash and dispense is opened.

The dispensing nozzle trigger switch is activated.

Once the evaporation and condensing process is completed the process complete light is displayed on the control panel and the unwashed de-methed biodiesel is ready to dispense by the user via the dispensing nozzle (14) When the dispensing nozzle trigger is sgueezed by the user the circulation pump is switched on and off with each trigger sgueeze or release and draws the unwashed de-methed biodiesel from the conical bottom (11) of tank A. It is pumped through the dry wash tower (13) via valve #4 and then through the 1 micron final filters (15) to the dispensing nozzle (14) Once the finished biodiesel is fully dispensed, the processor can be collected and delivered to the collection depot. The reset button is pressed which closes valve #4 tank A and the nozzle trigger switch is dc-activated.

The condensate methanol is then extracted from tank B and the glycerol by-product is extracted from tank C at the depot.

The processor is now ready for re-use.

Claims

-18 -CLAIMS1. A transportable, automatic biodiesel generator including at least three tanks for containing: (i) vegetable oil feedstock; (ii) methanol; and (iii) glycerol by-product, respectively.
2. A biodiesel generator as claimed in Claim 1 including dry wash means for the biodiesel product.
3. A biodiesel generator as claimed in Claims 1 or 2 wherein the methanol tank is associated with a feeder compartment adapted to discharge dry sodium hydroxide or dry potassium hydroxide into liquid methanol.
4. A biodiesel generator as claimed in Claim 3 wherein the feeder compartment is located above the methanol tank and a rotary drive urges the sodium hydroxide or potassium hydroxide to drop into the methanol.
5. A biodiesel generator as claimed in Claim 4 wherein the rotary drive comprises at least one paddle or brush.
6. A biodiesel generator as claimed in Claims 4 or 5 wherein the feeder compartment includes a baffle preventing discharge of the sodium hydroxide or potassium hydroxide into the methanol unless the rotary drive is activated.
7. A biodiesel generator as claimed in any one of the preceding claims, wherein by-product glycerol is separated from the biodiesel product by gravity drainage.
8. A biodiesel generator as claimed in any one of the preceding claims including a user-activated dispensing nozzle drawing the biodiesel product from the feedstock tank.
9. A biodiesel generator as claimed in Claim 8, wherein the biodiesel product passes through dry wash means intermediate the feedstock tank and the dispensing nozzle.
10. A biodiesel generator as claimed in any one of the preceding claims including a condenser for methanol vapour discharging condensate into the methanol tank.

-19 -
11. A biodiesel generator as claimed in any one of the preceding claims including pre-programmed controllers automating every stage of the operating seguence.
12. A biodiesel generator as claimed in Claim 11 including a control panel in which the only user-operable controls are a start switch and a stop switch.
13. A biodiesel generator as claimed in Claims 11 or 12 including valve-controlled flow connections between the tanks.
14. A biodiesel generator as claimed in Claim 13 wherein the valves are activated in seguence by timed commands from the pre-programmed controllers.
15. A biodiesel generator as claimed in Claims 13 or 14 wherein at least some of the valves are ball valves.
16. A method of generating biodiesel which comprises delivering to a user's premises an automatic generator including at least three tanks for containing: (i) vegetable oil feedstock; (ii) methanol; and (iii) glycerol by-product, respectively, wherein the respective tanks have been preloaded with pre-defined quantities of vegetable oil feedstock; methanol; and sodium hydroxide or potassium hydroxide.
17. A method as claimed in Claim 16 wherein the generator includes dry wash means for the biodiesel product.
18. A method as claimed in Claims 16 or 17 wherein the methanol tank is associated with a feeder compartment adapted to discharge dry sodium hydroxide or dry potassium hydroxide into liquid methanol.
19. A method as claimed in Claim 18 wherein the feeder compartment is located above the methanol tank and a rotary drive urges the sodium hydroxide or potassium hydroxide to drop into the methanol.
20. A method as claimed in Claim 19 wherein the rotary drive comprises at least one paddle or brush.
21. A method as claimed in Claims 19 or 20 wherein the feeder compartment includes a baffle preventing discharge -20 -of the sodium hydroxide or potassium hydroxide into the methanol unless the rotary drive is activated.
22. A method as claimed in any one of Claims 16 to 21, wherein by-product glycerol is separated from the biodiesel product by gravity drainage.
23. A method as claimed in any one of Claims 16 to 22 wherein the generator includes a user-activated dispensing nozzle drawing the biodiesel product from the feedstock tank.
24. A method as claimed in Claim 23, wherein the biodiesel product passes through dry wash means intermediate the feedstock tank and the dispensing nozzle.
25. A method as claimed in any one of Claims 16 to 24 wherein: (a) dry air is bubbled through heated biodiesel product to entrain residual methanol; and (b) exhaust air passes through a condenser discharging methanol vapour condensate into the methanol tank.
26. A method as claimed in any one of Claims 16 to 25 wherein the generator includes pre-programmed controllers automating every stage of the operating sequence.
27. A method as claimed in Claim 26 wherein the generator includes a control panel in which the only user-operable controls are a start switch and a stop switch.
28. A method as claimed in Claims 26 or 27 wherein the generator includes valve-controlled flow connections between the tanks.
29. A method as claimed in Claim 28 wherein the valves are activated in sequence by timed commands from the pre-programmed controllers.
30. A method as claimed in any one of Claims 16 to 29 wherein, after use, the generator is made available to the supplier for the purposes of the supplier's: cleaning the generator and disposing of the by-product glycerol; and recharging the respective tanks with vegetable oil and other ingredients in preparation for the next operating cycle.
31. A biodiesel generator substantially as described and with reference to the accompanying drawings.
32. A method of generating biodiesel substantially as described and with reference to the accompanying drawings.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS1. A method of generating batches of biodiesel by transesterification of vegetable oil feedstock with methanol using a potassium hydroxide or sodium hydroxide catalyst, comprising the following seguence of steps: (a) mixing a predetermined proportion of granular potassium hydroxide or sodium hydroxide into the methanol in a methanol holding tank while concurrently heating the vegetable oil feedstock to an elevated temperature in a separate feedstock tank; wherein the methanol holding tank is associated with a feeder compartment located above the methanol tank and adapted to discharge dry potassium hydroxide or dry sodium hydroxide into liquid methanol by means of a rotary drive urging the potassium hydroxide or sodium hydroxide to drop into the methanol; (b) transferring the resultant methanol/hydroxide mixture to the vegetable oil feedstock in the feedstock tank; (c) stirring the feedstock/methanol mixture for a predetermined time and then shutting off the stirring circulation while completing the transesterification LCD reaction in the feedstock tank; 0 (d) separating glycerol by-product by gravity drainage into a separate glycerol storage tank; 0 (e) evaporating off excess methanol from the biodiesel product and collecting the methanol vapour by condensation for return to the methanol holding tank; and (f) dispensing biodiesel product by means of a user-activated dispensing nozzle, wherein the biodiesel product passes through a dry wash intermediate the feedstock tank and the dispensing nozzle.2. A method as claimed in Claim 1 wherein the rotary drive comprises at least one paddle or brush.3. A method as claimed in Claims 1 or 2 wherein the feeder compartment includes a baffle preventing discharge of the potassium hydroxide or sodium hydroxide into the methanol unless the rotary drive is activated.4. A method as claimed in any one of the preceding claims wherein the feedstock/methanol mixture is circulated through a static mixer for a predetermined time at the start of the transesterification reaction.5. A method as claimed in any one of the preceding claims wherein: (a) dry air is bubbled through heated biodiesel product to entrain residual methanol; and (b) exhaust air passes through a condenser discharging methanol vapour condensate into the methanol tank.6. A method of operating a biodiesel generator as claimed s in any one of the preceding claims wherein the generator includes valve-controlled flow connections between the tanks, which valves are activated in sequence by timed commands from at least one pre-prograrnmed controller.7. A method of operating a biodiesel generator as claimed 13 in any one of the preceding claims wherein the generator includes a control panel in which the only user-operable controls are a start switch and a stop switch.8. A method of generating biodiesel as claimed in any one of the preceding claims which comprises delivering to a user's premises an automatic generator including: (a) at least three tanks for containing: vegetable oil feedstock; methanol; and glycerol by-product, respectively; and (b) a dispenser for granular potassium hydroxide or sodium hydroxide, 23 wherein the respective containers have been preloaded with U, pre-defined guantities of vegetable oil feedstock; methanol; and potassium hydroxide or sodium hydroxide.O 9. A method of operating a biodiesel generator as claimed in Claim 8 wherein, after use, the generator is made available to the supplier for the purposes of the supplier's acts of: cleaning the generator and disposing of the by-product glycerol; and recharging the respective containers with vegetable oil and other ingredients in 33 preparation for the next operating cycle.10. A transportable, automatic generator of biodiesel by way of a transesterification reaction including: (a) at least three tanks which, when in use, contain: vegetable oil feedstock; methanol; and glycerol by-product, respectively; (b) a feeder compartment associated with the methanol tank and adapted to discharge dry potassium hydroxide or dry sodium hydroxide into liquid methanol, wherein the feeder compartment is located above the methanol tank and a rotary 43 drive urges the potassium hydroxide or sodium hydroxide to drop into the methanol; and (c) a user-activated nozzle dispensing biodiesel product drawn from the feedstock tank and associated with a dry wash intermediate the feedstock tank and the dispensing no z z 1 e, wherein the transesterification reaotion ocours in the feedstcck tank.11. A biodiesel generator as claimed in Claim 10 including a static mixer through which a feedstook/methanol mixture is circulated during the transesterification reaction.12. A biodiesel generator as claimed in Claims 10 or 11 13 wherein the rotary drive comprises at least one paddle or brush.13. A biodiesel generator as claimed in any one of Claims to 12 wherein the feeder compartment includes a baffle preventing discharge of the sodium hydroxide or potassium hydroxide into the methanol unless the rotary drive is activated.14. A biodiesel generator as claimed in any one of Claims to 13 including valve-controlled flow connections between the tanks, which valves are activated in sequence 23 by timed commands from at least one pre-programmed 0 controller.15. A biodiesel generator as claimed in Claim 14 wherein at o least some of the valves are ball valves.16. A biodiesel generator as claimed in any one of Claims 10 to 15 including a control panel in which the only user-operable controls are a start switch and a stop switch.17. A biodiesel generator adapted to operate in accordance with the method of any one of Claims 1 to 9.18. A biodiesel generator substantially as described and 33 with reference to the accompanying drawings.19. A method of generating biodiesel substantially as dcscribcd and with rofcrcnco to tho accompanying drawings.