Introducing the eVAP Bioprocessor. At the heart of the processor is the reactor vessel, which is moulded from High Density PolyEthylene (HDPE) and is translucent to allow visual inspection for filling, reacting, settling and draining of waste products. It comes with level markings showing 50, 100, 150 and 180 litre markings for quick and easy filling.
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Features:
- HDPE for safe processing using aggressive chemicals
- 55° bottom cone for maximum draining and minimum waste
- Bottom 1” BSP thread moulded into the plastic
- Top 1” BSP thread moulded into the plastic
- Manufactured in the South West
- Wide access hatch for easy cleaning
- Synthetic seal for safer working conditions
- Sturdy, coated steel stand with stable base
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On the front is a 2¼” standard brass fitting for an immersion heater. It is moulded in, so it will not leak, and is mounted low down so that smaller batches can be processed if preferred. The supplied immersion heater is made from stainless steel for a long life operating within aggressive chemicals and has a thermostatic control, designed to hold the waste oil at the correct temperature for the reaction.¹
The reactor is mounted on a sturdy steel frame which has been coated for long, durable life. It offers maximum stability, and also holds the reactor at the optimum height for working.²
The HDPE cone bottom has a 55° slope for optimum draining, which minimises waste. The drain is internally threaded in 1” BSP and again is moulded into the plastic.³ The top fitting is again in 1” BSP threaded and moulded inlet, designed to thoroughly swirl the mixture as it re-enters the reactor.
On top is a wide access hatch with a synthetic rubber seal and a plastic threaded cap. To minimise fumes and maximise safety, the reaction phase would normally take place with the cap closed. This also reduces heat losses ensuring a more complete reaction. Some people like to circulate the raw biodiesel before washing as this agitation will cause some of the remaining methanol to evaporate, leaving cleaner biodiesel and less work in the wash stage.
Periodically the reactor should be cleaned and the wide top hatch gives good easy access. For thorough cleaning, a soap mixture can be circulated using the pump. On completion, the reactor must be fully dried as water in the reaction encourages the production of soap.
The bottom fitting leads into a 1” steel 'T' fitting, with one branch, controlled by a lever operated ball valve, being opened only for draining waste products, and the other, again controlled by a lever operated ball valve, connecting the reactor to the circulation pump. |
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| The top hatch in the open position. |
110LPM Circulating Pump
The most important component in the biodiesel processor system is the pump.
The pump is used to:-
- input the waste vegetable oil
- input the chemicals
- circulate and agitate the mixture during the reaction
- remove excess methanol
- input fresh water on systems employing water wash
- output the raw biodiesel to the dry wash tower
- output the finished, washed biodiesel
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| The circulating pump. |
The size and quality of the pump is critical in making good quality biodiesel.
If the pump is too small the reaction will not achieve sufficient agitation. The processor will need to be left on for excessively long periods of time (4 or 6 hours is not uncommon with an undersized pump) and the result, even after all that time, is only partial conversion of the waste vegetable oil into biodiesel. It will also leave unreacted chemicals, specifically sodium or potassium hydroxide, dissolved in the raw biodiesel. This remaining hydroxide will make washing impossible.
If you water wash, you will most likely end up with a huge creamy emulsion of biodiesel, soap, glycerine and methanol,which will prove almost impossible to separate. If you dry wash, the resin will absorb huge quantities of oil, soap, glycerine and methanol which can exhaust it in as little as one single batch, still leaving you with unusable biodiesel.
The key to good biodiesel is a decent sized pump, ensuring short reaction times (under an hour), complete reaction and good, clean raw biodiesel, which washes quickly and easily. We will not supply a pump with a minimum circulation rate of less than 50 lpm (litres per minute) in any size system, and our normal system comes complete with an 80 lpm pump. On larger size systems, we will only supply 100 lpm, and will even double these up to achieve optimum flow rates.
Besides a good flow rate, a self priming feature can be useful. Many pumps require them to be full of fluid before they can operate, so you must start with manually pouring in some oil and/or chemicals before switching on the pump. Others are self priming, meaning you just switch them on and they will will pump out any air in the system before sucking up the oil and/or chemicals. We offer both standard and self priming pumps (price usually decides which to choose).
Quality is vital. Cheaper pumps may contain a plastic impellor, which will be attacked by the harsh chemicals they are required to circulate. Others may contain rubber seals, which again can be destroyed in a very short period of time. A good pump is not cheap, but is vital to making good biodiesel and will last a long time.
3KW Stainless Steel Immersion Heater
Before oil can be reacted with the methoxide, it needs to be heated. The ideal temperature is a matter of discussion but most agree that at least 50°C is needed for a good clean reaction. The amount of oil being processed is usually around 100 or 200 litres, so a good size element is essential. Most smaller systems offer an integral immersion heater in the reactor vessel.
The HDPE cone has a standard 2 ¼” brass screw housing to take standard elements, however, the aggressive nature of the chemicals used during reacting means that a standard copper element will not last.
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| Aerial view of the immersion heater. |
We supply a stainless steel heater element of approx 27” length, offering a good surface area, ensuring quicker heat up times. The heater is rated at 3kw and comes complete with an adjustable thermostat control.
Because the element heats only the oil above itself (heat rises) the normal practise is to fill the reactor with WVO, turn the heater on and leave it until the top layer is hot. At this point, the circulating pump would be switched on and left on for the remainder of the heating session, sometimes another 15 or 20 minutes.
The element is always submerged and so offers safe heating. Some people leave it on during the reaction. However, we do not. We believe the element should not be used during the reaction itself. We recommend you heat the oil to around 55°C, turn off the heater, add the methoxide, and then react for around an hour. The reaction is exothermic and the temperature in the cone normally stays around or just above 50°C for the duration.
Once the reaction is completed, the heater and pump are turned off and the contents left to settle. Glycerine will drop to the bottom, being much denser, taking with it almost all of the excess methanol, sodium or potassium hydroxide, soap, water and any waste that was present in the oil (tiny particles of chips, batter, burnt charcoal may be present unless the oil is well filtered prior to reacting). Once settled, the glycerine mixture is drained off, leaving raw biodiesel.
Some people recommend heating the raw biodiesel to 85°C at this stage to boil off excess methanol. Do not do this under any circumstances!!! The HDPE cone is only rated at 60°C, the plastic tubing is rated at 60°C, and the hot fumes released as the methanol boils at 64°C are lethal if inhaled and, with a flashpoint of just 12°C, are about the most flammable thing you could ever hope to create. Do not do this!!!
And finally...
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| A fully assembed bioprocessor setup. |
¹ For safety reasons, the heater should be used only as a pre-heater and must not be used during the reaction phase itself.
² It is vital that the frame is mounted on a strong and stable floor since when full, the weight will be in excess of 250 Kg, around ¼ of a ton.
³ Fully moulded in threaded fittings allow for complete draining, leaving no small pools of waste products. |
