THE BEST THING TO DO IS ALWAYS ASSUME THAT YOUR WASTE OIL HAS ALL

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1 Date: To: Cc: From: Astec Service Greg Renegar Mike Varner Subject: Waste Oil Pointers Despite the potential risks, waste oil and waste oil blends are used successfully in hot mix plants all over the world. Waste oils are used because of their low cost and high Btu content. The purpose of this memo of pointers is to clearly explain how to successfully run waste oil in a hot mix plant. What is Waste Oil? Waste oil comes from a number of sources from used crankcase oil to oils from industrial processes. Where the oil originates is important only in that it can affect the constituents in the oil and its consistency both of which can have a great impact on plant components such as the bag house. The key elements in successfully running waste oil may be stated in terms of the potential problems that it causes -- these problems have causes associated with a characteristic of the oil. THE BEST THING TO DO IS ALWAYS ASSUME THAT YOUR WASTE OIL HAS ALL OF THE PROBLEM CHARACTERISTICS. This may sound like overkill, but it is the only way to ensure that you are doing all you can to reduce the potential damage the oil can cause. In some cases, you will only be confirming that it does not have one or more of the problematic characteristics. The key is that you will be CONFIRMING rather than guessing. Problem Characteristics Characteristic Explanation Consistency No two loads of waste oil are the same all of the remaining characteristics listed below can change drastically on the next load you get. Just because your supplier has been consistent does not ENSURE that the supply will remain consistent. Contamination Waste oil is often heavily contaminated with cellulose fiber and other fibers from engine oil filters. Viscosity Viscosity is often much higher than that of No. 2 Fuel Oil. Given that it is more viscous, it must be heated so that it will be a consistency the burner will burn properly. Radiant Energy Waste oil contains more carbon than lighter fuels. The presence of carbon in a fuel causes the flame to give off more of its heat as radiant energy. The difference in radiant energy between a natural gas flame and a flame from No. 2 fuel oil shows by how radiant energy can vary. When burned properly, waste oil is more radiant than No. 2 Fuel Oil Sulfur Content The sulfur content of waste oil especially if it is in the form of sulfuric acid. Sulfuric acid is used to strip heavy metals from oils used in industrial processes. Page 1 of 9

2 Contamination What is it? Though anything is possible, there are basically three types of contamination typically in waste fuels. These are listed below in the order of importance to your operation. Contaminate Description Problems it Causes Cellulose Fiber Material used in the filter This material will clog Y- elements of engine oil filters. strainers and sock filters. This material will clog Y- If it makes it to the burner, it will strainers and sock filters. If it makes it to the burner, it will clog nozzle holes and other small apertures. clog nozzle holes and other Can change the flame shape. small apertures within the Can cause burner output to be burner. reduced at a given fuel valve Other Contaminates Contaminates range from metal shavings to rubber pellets. Water Water may be present in concentrations as high as 5%. What can you do about it? position due to constriction. Same as above Vapor locking. This becomes worse at higher temperature and when the size of the fuel pre-heater requires that fuel be returned back to the inlet of the pump rather than back to the tank. Contaminate Preventive Measures Cellulose Fiber Install a duplex strainer on the inlet and outlet of the fuel storage tank. Monitor differential pressure across the filter element. Remove, inspect and clean filter elements FREQUENTLY. Service the Y-strainer by removing the basket and cleaning it at the end of each day s run. Note: Contact Astec Engineering or Service Department for suggested Other Contaminates Duplex straining units. Same as above Water Install a water separation unit in the line to remove separated water. Viscosity What is viscosity? Viscosity refers to how resistant a fluid is to flowing. For example, if you filled two identical drinking glasses one with water and the other with molasses and then picked both up and poured them out at the same time, which do you think would pour out more quickly? Of course, the water would pour out more quickly than the molasses. The reason is because the water has a lower viscosity than the molasses it is less resistant to flowing so it pours out more quickly. When liquids that are very viscous are heated, the viscosity decreases. You can see this every day as hot AC runs and mixes very freely with aggregate yet becomes extremely viscous at ambient temperatures. There many different units for viscosity just as there are different units for length inches, millimeters, feet, miles, etc. For Page 2 of 9

3 waste oil as it applies to burners, the viscosity unit of choice is Saybolt Seconds Universal (SSU) because it is easily obtained with a simple, handheld viscometer. Why is Viscosity Important? MAINTAINING THE CORRECT VISCOSITY IS THE SINGLE MOST IMPORTANT FACTOR IN SUCCESSFULLY RUNNING WASTE OIL. If blending with lower viscosity oil is not employed or not sufficient, this is accomplished by maintaining the appropriate temperature of fuel being supplied to the burner. If viscosity is not maintained below its upper limit by keeping temperature of the fuel going to the burner above a target temperature, fuel will not atomize properly in the burner and can even pass to the bag house unburned. The problems associated with viscosities that are too high (fuel temperatures too low) are numerous and potentially catastrophic to a hot mix plant. The following table lists the problems resulting from running with fuel viscosities that are too high. Component Likely Damage From Running Fuel with Viscosity too High Combustion Flights Accelerated thermal distortion and damage. This can often occur very quickly over a short period of time. Mixing Chamber Increased shell temperatures can result in fires. Prolonged fires can damage the (double barrel) outer shell. Bag House Blinded bags due to unburned fuel accumulating on the bags high bag house differential pressure. Plant Operations Lower efficiency higher gallons per ton used. Emissions Carbon Monoxide and hydrocarbons greatly increase in exhaust stream. Figure 1. Typical viscosity curve. This curve will not be applicable to your fuel. A blank chart is provided with step-by-step instruction so that you can make a curve like this for your fuel. Viscosity Versus Temperature BAD B E T T E R Because the curve goes lower than 80SSU at this point, THIS oil must be run at a temperature GREATER than 186F Target: 70 SSU +/- 10 SSU CAUTION: This curve is actual waste oil viscosity vs. temperature for a specific oil. It DOES NOT represent your waste oil. It is an example only. 186 F B E S T Temperature (F) 204 F How to Check and Document Fuel Viscosity Ensuring that you are running the right viscosity can be accomplished with a quick and easy test. The primary reason for doing this is to protect your equipment from the damage that can be caused by running a viscosity that is too high. In addition to this, it also provides documentation that you can use if you suspect inconsistencies in your oil supply. Page 3 of 9

4 Tools for Checking Viscosity Tool Discussion Photo or Diagram Safety Face Shield Equipment Safety Glasses Protective Gloves Long-sleeve shirt or jacket. Viscosity Cup Astec Part # Astec Part # (Kit includes thermometer) The viscosity in SSU (Saybolt Seconds Universal) is the number of seconds it takes the fluid to run out of the cup. Thermometer or Thermocouple Refer to note above. When using a thermocouple wire, wind it around what you use to stir the sample. Metal can or Saucepan Deep enough to completely immerse viscosity cup when partially filled. Leave space at top for liquid expansion when heating. A one-gallon paint can is shown at right. Stopwatch, Pencil, Blank Chart Blank chart is provided. Make a few copies of the blank chart to have on hand. Electric Hotplate DO NOT use a hot plate which burns a fuel as a source of heat. THIS CAN ACT AS AN IGNITION SOURCE. Stirring Stick A welding rod will do fine. The thermometer may also be used to stir. Keep thermocouple immersed by attaching to the welding rod. Page 4 of 9

5 Make a Baseline Viscosity Curve It is very important to have a viscosity curve for the oil you are currently burning. This establishes what you are currently doing and whether or not the oil is at the appropriate temperature. The following table summarizes the steps in making a viscosity curve for your oil. BE SURE TO WEAR PROTECTIVE EQUIPMENT AND FOLLOW ALL SAFETY SUGGESTIONS ANYTIME YOU ARE HANDLING WASTE OIL. Steps for Making a Baseline Viscosity Curve STEP Instructions 1 Wearing a long-sleeve shirt, protective gloves, safety glasses and face shield, obtain an oil sample. The best place to obtain a sample is from a sample port while the system is operating or in recirculation. It is often helpful to install a flexible hose on the sample port so that the potential for spilling and splashing is reduced. With a flex line, crack the line and allow it to drain into the sample can be careful not to overflow the can. 2 In a well-ventilated area (but shielded from direct winds), heat the sample on low heat. Stir the sample occasionally monitoring its temperature. You will notice the change in viscosity as the sample heats up it will become much more fluid. DO NOT allow the thermometer to rest on the bottom of the can. You may wish to suspend the thermometer so that it remains immersed in the sample up to its immersion line. DO NOT, UNDER ANY CIRCUMSTANCE, LEAVE THE SAMPLE UNATTENDED. If you must leave the sample, remove it from the heat and turn the hot plate off. 3 Heat the sample until it reaches 200F (STOP HEATING IF THE SAMPLE BEGINS A ROLLING BOIL BEFORE REACHING 200F), turn off the hot plate. Fully immerse the viscosity cup in the sample (this allows the viscosity cup to heat up to the temperature of the sample. Stir the sample and obtain a temperature reading. Record it in the space provided. 4 With the stopwatch in one hand and the chain on the viscosity cup in the other, quickly raise the viscosity cup out of the sample while starting the stopwatch. Start the stopwatch just as the top rim of the cup clears the top of the oil. Stop the stopwatch when the stream coming out of the viscosity cup stops and becomes a drip. The viscosity in SSU (Saybolt Seconds Universal) is the number of seconds it takes the fluid to run out of the cup. 5 If the viscosity you measure is GREATER than 80 SSU, place the sample back on the heat. Take it up an additional 20 degrees (or until a rolling boil begins) and then repeat STEP 3 (two bullets) and STEP 4. If the viscosity you measure is 80 SSU or below, go to STEP 6. 6 Record the viscosity in the space provided. This viscosity reading is the number of seconds it takes for the viscosity cup to drain to a drip. Example: 1 minute 15 seconds will be recorded as 75 SSU (60 seconds + 15 seconds) 7 Allow the sample to cool down by about 10F, stir frequently to speed cooling. Repeat STEP 3 (two bullets), STEP 4, and STEP 6. 8 Repeat Step 7 until the viscosity reading is 120 SSU or greater. 9 Plot the viscosity and temperature readings on the blank chart (refer to Figure titled STEP 9, Plotting your Data ) Start by finding the temperature along the bottom. If your measurement is between two of the gridlines, estimate where it is between them. Go straight up on the chart from this point (a ruler or straight-edge might help) until you are directly across from the viscosity reading on the left of the chart. Make a little mark (a small plus sign or X is easiest to see) Repeat until you have plotted all the data. 10 Either freehand or with a straightedge, draw straight lines between the marks you have made. 11 Draw a vertical line down from the point that the curve crosses the horizontal 80SSU line. Extend this line down to the temperature scale at the bottom of the chart. This is the lower limit for temperature oil temperature must be kept above this level for viscosity to be below 80SSU. Figure 2. STEP 9: Plotting your Data Page 5 of 9

6 Viscosity Versus Temperature Temp (F) SSU Follow horizontal line from "83" on the vertical scale at left. This is where you will mark an "X" for this data point. Viscosity (SSU) X Follow vertical line from "184" on the horizontal scale below Temperature (F) Figure 3. STEP 10: Drawing a Curve with your Data Viscosity Versus Temperature 120 Temp (F) SSU Viscosity (SSU) Draw lines in between points once all your data is plotted Maintain Temp. above 186F. 186F Temperature (F) Monitoring and Documenting Your Waste Oil Supply Page 6 of 9

7 Now that you have established a baseline viscosity curve, keeping track of your viscosity is a much simpler task. The inconsistency of waste oil is a certainty. From differing levels of contamination to changes in the viscosity, almost every supply changes over time sometimes overnight. Just because you order oil to a given specification doesn t meant that it remains at that specification. Likewise, just because a supplier has been consistent for many years does not mean that the supply will remain consistent. The key to monitoring and documenting something that has a tendency to be inconsistent is to be consistent with the monitoring and documentation. The following table gives you the steps to follow. Refer to the Figure 4 titled Monitoring and Documenting Waste Oil Supply. This shows how you can save time by anticipating a problem and catching it before it does damage to your plant. Steps for Monitoring and Documenting Oil Supply STEP Instructions 1 Wearing a long-sleeve shirt, protective gloves, safety glasses and face shield, obtain an oil sample. The best place to obtain a sample is as it arrives as it has not mixed with any of the oil currently in the tank. It is important to obtain a sample that is not mixed with oil you already have. 2 In a well-ventilated area (but shielded from direct winds), heat the sample on low heat. Stir the sample occasionally monitoring its temperature. You will notice the change in viscosity as the sample heats up it will become much more fluid. DO NOT allow the thermometer to rest on the bottom of the can. You may wish to suspend the thermometer so that it remains immersed in the sample up to its immersion line. DO NOT, UNDER ANY CIRCUMSTANCE, LEAVE THE SAMPLE UNATTENDED. If you must leave the sample, remove it from the heat and turn the hot plate off. 3 Heat the sample until it reaches 20F hotter than the temperature you are currently running your waste oil. (STOP HEATING IF THE SAMPLE BEGINS A ROLLING BOIL BEFORE REACHING 200F), turn off the hot plate. Fully immerse the viscosity cup in the sample (this allows the viscosity cup to heat up to the temperature of the sample. Stir the sample and obtain a temperature reading. Write it down. 4 With the stopwatch in one hand and the chain on the viscosity cup in the other, quickly raise the viscosity cup out of the sample while starting the stopwatch. Start the stopwatch just as the top rim of the cup clears the top of the oil. Stop the stopwatch when the stream coming out of the viscosity cup stops and becomes a drip. The viscosity in SSU (Saybolt Seconds Universal) is the number of seconds it takes the fluid to run out of the cup. 5 If the viscosity you measure is GREATER than 80 SSU, place the sample back on the heat. Take it up an additional 20 degrees (or until a rolling boil begins) and then repeat STEP 3 (two bullets) and STEP 4. If the viscosity you measure is 80 SSU or below, go to STEP 6. 6 Write down the viscosity. This viscosity reading is the number of seconds it takes for the viscosity cup to drain to a drip. Example: 1 minute 15 seconds will be recorded as 75 SSU (60 seconds + 15 seconds) 7 Allow the sample to cool down by about 10F, stir frequently to speed cooling. Repeat STEP 3 (two bullets), STEP 4, and STEP 6. 8 Repeat Step 7 until the viscosity reading is 90 SSU or greater. 9 Plot the viscosity and temperature readings on your Baseline Viscosity Curve (refer to Figure titled STEP 9, Plotting your Data ) Start by finding the temperature along the bottom. If your measurement is between two of the gridlines, estimate where it is between them. Go straight up on the chart from this point (a ruler or straight-edge might help) until you are directly across from the viscosity reading on the left of the chart. Make a little mark (a small plus sign or X is easiest to see) Repeat until you have plotted all the data. (Table continued on the next page) 10 Either freehand or with a straightedge, draw straight lines between the marks you have made. Page 7 of 9

8 11 Draw a vertical line down from the point that the curve crosses the horizontal 80SSU line. Extend this line down to the temperature scale at the bottom of the chart. This is the lower limit for temperature oil temperature must be kept above this level for viscosity to be below 80SSU. Figure 4. Monitoring and Documenting Waste Oil Supply Viscosity Versus Temperature 120 Temp (F) SSU Baseline Viscosity Curve 90 New Sample Viscosity (SSU) Run above 186F for baseline oil. Run Above 193F for the new sample Temperature (F) It is possible to anticipate problems with your waste oil supply by following the 11 steps and confirming that the viscosity is below the maximum limit. However, you can anticipate problems by running with the temperature marginally hotter than the temperature needed to attain 80SSU. For example, if the oil temperature had been set to 195F for the baseline sample, the temperature set-point would be still be adequate for the new sample. Note that the new sample has a viscosity that is higher at the same temperature than the baseline sample. Over time, you can anticipate the typical variations in the viscosity of the oil and add enough margin to the temperature set-point to account for changes in the viscosity characteristic of the oil. Once you do this, you merely need to confirm that the viscosity is below 80SSU at the set temperature. This may be accomplished with a single point test (Step 7 may be omitted). Remember, the UPPER limit for the target range for viscosity is an ABSOLUTE limit. Running with viscosity above this upper limit may cause catastrophic damage to both the drum and the bag house. Page 8 of 9

9 Radiant Energy of the Flame Waste oil contains more carbon than lighter fuels. The presence of carbon in a fuel causes the flame to give off more of its heat as radiant energy. The difference in radiant energy between a natural gas flame and a flame from No. 2 fuel oil shows by how radiant energy can vary. A more radiant flame is a natural characteristic of waste oil it is one of the benefits of running waste oil. However, high radiant energy increases the temperature of exposed surfaces and can cause damage to combustion flights. Running waste oil requires that the combustion flights be inspected frequently every other week is a good rule of thumb. When inspecting combustion flights, look for changes in color, scaling or flight shape. Especially look for rattlers combustion flights that have become loose. Rattlers soon become tumblers and can cause catastrophic damage in equipment downstream of the dryer. Sulfur Content of Waste Oil Sulfur may exist in oils as elemental sulfur or as dissolved gaseous sulfur compounds, and as sulfur based acids, including sulfuric acid. Of all these various forms, the sulfur-based acids have the greatest corrosive potential It is important that equipment downstream of the combustion process not be exposed to sulfuric acid or hydrochloric acid. The epoxy coating inside the bag house will provide some degree of protection, but high enough concentrations can still result in corrosion problems. It is important to limit the amount of sulfur in the fuel to 0.5%, but it is even more important what sulfur compound comprises the sulfur. This provides an exaggerated concentration of sulfur oxides that raises the acid dew point above that which would normally be encountered with a fuel bearing 0.5% sulfur. This, of course, means that saying that the fuel containing 0.5% sulfur is not the same thing as saying it contains 0.5% sulfur with part of the sulfur existing as sulfuric acid. Crankcase waste oils are generally not a problem. Industrial waste oils that have been treated with sulfuric acid for removal of heavy metals can be very problematic. If high sulfur fuels are to be used, acid resistant bags should be considered. Also, plant start-up procedures become more important. If a low sulfur crank case oil is filtered, heated to the proper viscosity, the burner adjusted, cleaned regularly, the bag house preheated and the stack temperature maintained above the acid dew point, the waste fuel will probably not cause problems. If industrial waste oil containing corrosive compounds such as sulfuric acid is used, there is probably no way to prevent this fuel from damaging the bag house. I hope that this information helps. Certainly, this document does not include all of the information necessary. But as you have ideas and make suggestions regarding what we should add, we will make updates. Page 9 of 9