The right biodiesel pump will save money by mixing efficiently.
The Biodiesel pump on a processor circulates and mixes the oil and chemicals in the reaction vessel. It also sucks the oil and methoxide into the processor and pumps the finished biodiesel into the wash tank.
It should ideally have the following characteristics.
- The pump housing should be 304 stainless steel or better, cast iron is ok, plastic is a poor choice.
- The impeller should be stainless steel, cast iron is ok, plastic is a bad choice.
- The seals should be viton or equivalent. A solid mechanical seal like carbon or ceramic is acceptable. Nitrile rubber should be avoided.
- As long as the plant is designed properly the head will be small, less than a meter. This means that the pump will operate at close to it's maximum flow rate.
- Size the pump so that it circulates the contents of the processor at least every 5 minutes. For example, if the tank is 100 liters then the pump should be rated at 20 liters a minute. If you use a bigger pump so much the better.
- The pump should be flameproof, if you can't find a flameproof pump there are companies who will flameproof existing pumps.
- Direct displacement or centrifugal pumps are good choicesl.
- The maximum operating temperature is about 60 deg C.
There is a typically a lot of compromise when it comes to selecting a pump for small systems. The most commonly used pump for the appleseed processor is a small water pump from Harbor Freight. This is cast iron, not flameproof, has a brass or cast iron impeller and is cheap. There are a lot of people who use this pump without problem.
However, if you are designing a processor which will be used day in and day out, select the proper pump. You will have to find a pump supplier close to you and ask them to recommend something with the above specs. Duda Biodiesel has some excellent pumps that are rated for methanol and biodiesel.
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