|
|
||
|
LESSON 6 Preparing the waste oil to use as fuel Addendum: In order to determine if you have a good source of oil, you need to test the quality of the waste oil from each potential source. Read our new article on Performing the "Crackle Test" to determine how much water is in each oil source before continuing. Now that you have good sources for your vegetable oil you are at one of the most important steps in the process of using veggie oil as fuel: filtration and dewatering. Often greasers only concentrate on filtering particles from the oil before burning it in their engine. They think that by sucking the oil from the middle of the barrel, they avoid any water that might be emulsified in the oil. Unfortunately, chances are that the oil has not had enough time to settle since the last batch was dumped in the barrel. Water, when introduced into an injection pump, will rust out the internals of the pump including the cam rollers, cam plate and the rest of the internals. Anyone who has had their injection pump rebuilt knows that this is a very expensive project! (my injection pump is at the rebuilder right now and I had to pre-pay over $500 just for the rebuild... not including removal and installation) How Clean is Your Oil?
Now that you have a basic understanding of how
to prepare pure, virgin Straight Vegetable Oil (SVO) for burning in
a diesel engine, we need to look at how you can prepare Waste
Vegetable Oil (WVO) as a fuel. (since using WVO is the goal of
this project!) There are two additional issues that must be
resolved before WVO will burn in a diesel engine: Sediment and Food Particles - Waste vegetable oil, when first acquired is usually contaminated with food particles from use as a cooking oil. In order for the oil to pass through filters and through the fuel injectors, particulate must be removed from the oil. This prevents the particulate from collecting in the fuel filters or injectors and clogging the fuel system. Most experts recommend that WVO be pre-filtered to a level of at least 5 microns. (2 microns is even better) So, before WVO is placed in the fuel tank, it should be filtered several times with the last filtering step using at least a 5 micron filter sock. This will remove particulate that would potentially clog the fuel filter, injection pump or the injectors themselves. Water - One of the quickest ways to trash a diesel engine no matter what fuel you use is to introduce fuel contaminated with water into the fuel system. It will corrode the inside of the injection pump and injectors. If sprayed into the cylinder, it can cause imcomplete combustion or other more severe problems. Waste Vegetable Oil (WVO) can be dewatered by heating it before use. Water boils at 212 degrees Fahrenheit... a much lower boiling point than oil. By heating the WVO to 250 degrees for at least 15-20 minutes, all water will turn to steam and be released from the WVO. Some other processors prefer to heat the oil to 212 degrees and let it hold steady until all water is boiled off. Once the temperate starts approaching 230 degrees F. the oil will be free of water. Most diesel engines also have a fuel/water separator installed inline between the injectors and the fuel tank to help prevent introduction of water into the injection pump and combustion chamber. If your vehicle has a separator, make sure you drain the water from the device periodically.
Settling and Pre-filtering the Oil Proper oil preparation is more than a one step process. In order to prevent the injection pump from rusting out, water must be removed from the oil before use. Greasers must also be certain that particles in the oil don't enter the injection pump and/or injectors or clog up the injection pump screen. Filtering out any particles that are larger than 10 microns is critical. In order to be safe, most greasers will use filters of 7 microns or less to make sure that nothing slips by that could clog the injection system. Before filtering the oil, it is a good idea to let the oil settle for 1-2 weeks before running it through a bag filter. If the oil is not settled properly, the filter bag will clog much faster than you would like. I let the oil settle for two weeks in 5 gallon plastic containers. These are the containers inside cardboard boxes that new vegetable oil comes in. I remove the cardboard from the plastic container so I can monitor the settling process. If your oil is not returned to the "cubies" when you pick it up, you can also settle the oil in a large drum. Your best bet is to settle for two weeks before filtering to be safe. If your oil source is dumping it into your drum, you can fit a "drum strainer" on top of the oil drum so that when oil is poured, sediment will be caught in the strainer on top. I have seen strainers in 100 and 200 micron and larger sizes. Make sure that you have a way to cover the top of the drum over the strainer to keep out rainwater and debris. Once the oil is settled, it is now ready for filtering and dewatering. Filtering and Dewatering the oil Once the oil is settled, I pour it from the 5 gallon jugs or "cubies" through a 100 micron bag filter inserted in a hole at the top of a 55 gallon drum. Once I get to the sediment layer, I stop pouring. Bag filters can be purchased through Mcmaster-Carr in several sizes. I have found that getting long filters with a metal ring sewn in the top work the best for this step of filtering. I cut a hole in the top of the drum, smooth the edges and insert the bag filter in the hole. Once you have dumped all of the settled oil into the drum, you are ready for the dewatering process. I use a hot water heater element inserted in the drum and plugged in to heat the oil. I heat the oil for 6-8 hours and then let it cool. This makes any additional particles and most of the water fall to the bottom of the drum. I have a drain in the bottom of the drum with a section of clear hose attached to it with the other end in a trash barrel. I drain the liquid at the bottom of the drum until clean oil starts to come out. You have now dewatered the oil and it is ready for final filtering and use! Final Filtering, Storage and Filling I use a second drum with a bag filter in the top that is dual layer. The first layer is 5 microns and the outer layer is 1 micron. I use a manual barrel pump with hose to pump the dewatered oil through the 5-1 bag filter and into the new drum. Once all of the oil is pumped into the storage drum, I remove the lid with the bag filter and put a solid lid on it for storage. If I plan to use this drum for dispensing immediately, I install a lid with the barrel pump attached with a Goldenrod filter fuel/water separator attached and hose with an optional fuel handle. The Goldenrod filter is known as a "polishing" filter to remove any sediment introduced from the new drum. You can purchase drum liners that some people use to prevent paint or crud peeling from the inside of the drum and flaking into your oil. I am purposely vague in the description here since there are many ways to filter and dewater oil. You can purchase specific plans from Dana Linscott, a pioneer in the SVO biofuels industry on his website at http://vegoilconversions.netfirms.com/ DRAFT
|
||
