Five Ways Your Asphalt Mixing Plant Can Prepare for Spring
During the winter months, your company should optimize plant downtime by completing numerous preventive maintenance tasks. A winter maintenance plan for an asphalt mixing plant involves checking those "problem spots" that have accumulated during the paving season that you know will need to be addressed when business slows down.
Here are 5 key areas you should focus on during a planned outage of your asphalt mixing plant.
1. Check the Drum of the Asphalt Mixing Plant
The drum is the heart of the asphalt mixing plant and this part should be inspected regularly during the paving season. However, during planned shutdowns, asphalt plant owners should ensure these service checks are completed on the drum:
Check drum shell thickness for wear.
Clean, inspect and adjust burners.
Replace the oil in the drive reducer.
Inspect the baghouse to make sure the bags are intact. Also, make sure the cleaning and fines recovery systems are working properly.
Check the trunnions for excessive or uneven wear and check the bearings for excessive play.
If there is excessive wear or loss of thickness along the threads or housing, the material should be replaced. Repairing and replacing these parts will help minimize fuel consumption and maximize the life of your dryer casing. Specifically, combustion flights can have a significant impact on fuel burn efficiency and emissions.
If there is excessive wear or loss of thickness along the threads or housing, the material should be replaced. Repairing and replacing these parts will help minimize fuel consumption and maximize the life of your dryer casing. Specifically, combustion flights can have a significant impact on fuel burn efficiency and emissions.
2. Monitor the Batcher/silo System of the Asphalt Mixing Plant
Batchers and silo systems are two of the most important pieces of air conditioning equipment when it comes to dealing with mixture separation and safe storage of mixtures.
Silo cones should be thickness surveyed at least annually and possibly more depending on the number of tonnages. Thickness gauge readings should be taken along the entire length and circumference of the conical section and up the sidewall of the silo, depending on how the silo is operated, how much it is filled per day, and how much is below the level of the cone. This measurement and mapping should be carried out on a regular basis for each silo to closely monitor the degree of wear occurring.
Typically, when a batch unit has a problem, its doors are opened to keep work going. HMA quality suffers, but as long as the mixture is accepted, the price of downtime to repair the batching machine is considered prohibitive. With a little foresight, you can avoid the whole scene by following these tips:
Check the sides and cone of the dispenser for fine spots. Mark any plating that may be required. Take a close look at the gate and its pivot. Are they losing? Do they need lubrication? Flag any abnormalities you find for service.
Check the pneumatic system. Failure here is the main cause of problems with batch programs.
Check the cylinder for excessive wear. Substandard air hoses should be replaced.
Storage silos use the same inspection protocol as batch machines. Check the structure thickness, especially the cone area. Mark any thin areas for repair or replacement.
3. Dryer and Mixer for Fine Asphalt Mixing Plant
A/C, shower, and combustion dampers need to be inspected for wear or damage. Replace or repair as necessary. Inspect each fly and mixing tip for the following problems:
Excessive wear and tear
Hot crimping
Impact bending
Cracked or missing
Flag any flight with these issues for replacement. Obviously, anything cracked can be welded on, while anything worn or missing must be replaced. Mix headwear needs to be assessed periodically or when the asphalt mix quality is insufficient. These mixing heads are reversible for extended life. The buildup on the drum should be removed in conjunction with a rotating agitator head (paddle).
4. Adjust the Combustion System of the Asphalt Mixing Plant
The main burner and thermal oil heater complete your combustion system. Burner maintenance/cleaning and regular tuning are important for every BT utilizing the fuel available. Test, evaluate and adjust your burners as needed to optimize performance.
Check all fuel lines. Arrange to replace anything that raises a question in your mind.
Check fuel pump and drive mechanism.
Mark any worn belts, worn couplers or leaking seals.
Schedule replacement of fuel filters no matter how long they have been installed.
Inspect supply tank piping and valves.
Verify that the shutdown actually works. Don't take them for granted and it may come back to haunt you.
Check the filling device of the fuel tank. Watch out for any leaks or unsafe conditions.
Maintenance of these burners will depend on your fuel type. If you are burning oil or gas, you need to check and clean the fuel delivery system. This is also the time to inspect and clean the pilot assembly and burner nozzles. If you have an electric heater for your thermal oil, you will need to verify that your electrical connections and controls are working properly.
5. Screening System for Solidified Asphalt Mixing Plant
Coarse screening is essential for the removal (rejection) of oversized aggregates in batch and continuous asphalt mixing plants. To verify that your screening system is compliant, follow these steps:
A. Start with an external inspection. Look for missing parts, such as the lid retainer, and for signs of dust leaks. Look at the baseboard seals under the unit. Are they there or long gone? Check the top cover. Are they worn where they rest on the frame or other covers? All of these situations should be addressed.
B. Check whether the screen can move freely. If they don't, look for aggregates under the drive end.
C. Check the size of the material. If it's the size available that normally goes into the hot bin, the buildup could indicate a leak of oversized emissions, exacerbated by screen overflow and residue.
D. Remove all covers and side covers. It is best to hose off any accumulated fines on the screen frame and springs to make it easier to find damaged and cracked parts. Note: Remember to open all doors below and provide a way for water to escape from under the plants. After your unit is cleaned, you should inspect it for broken springs and cracks in the frame.
E. Check each screen carefully. Look for excessive wear and broken threads.
F. Check the screen tray, is it tight? Is the mesh cloth firm? Stocking up on a full set of screens is good insurance. Don't forget to have the proper bolts on hand.
Proper plant maintenance can be helpful for next season's plant performance, but it's also important to employ experienced plant personnel who are trained to spot warning signs of potential problems with plant components during the production season. Faulty parts in a plant can be costly if not addressed when first discovered, and can lead to difficult-to-repair failures, even in the off-season.
Remember that all maintenance operations should be performed according to the manufacturer's recommended procedures and intervals.
