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SAMPLE 4 Plant Operation Consulting Reports April 14, Gentlemen; Please review the following adjustments, changes, observations and assessments I have made on your equipment and operations.
Production increase Three things are of immediate concern; low drying capability, long batch cycle time and long asphalt oil batch weigh up time .
Low drying capability The burner fuel pressure regulator ($307.68) has been replaced and now the pressure adjusts up like it is supposed to. The return line valve ($262.15) has been replaced and so now it is safer to operate burner and run plant. A combustion analyzer and manometer was hooked up to the plant. Air flow was adjusted to max plant capability and fuel pressure adjusted to 46 psi to allow for highest combustion output and efficient fuel usage. With the conditions of April 15, the exhaust gases were adjusted to 6.5% Oxygen, 400 ppm Carbon Monoxide. These readings and low dryer exhaust gas temperatures indicate the dryer flighting is doing a good job. Before yesterday but under the same conditions as yesterday, Mike feels the plant could only produce 225 tph of B Insoluble and 280 tph of A Base mix. Yesterday the plant produced 282 tph of B Insoluble and 325 tph of A Base mix. This is an average production increase of 20%. The burner is now capable of delivering much more combustion but the exhaust fan is not capable of keeping up. Recommended action is advised further on.
Long batching cycle time Now that drying capacity increased, the batching process was not keeping up. Four things slowed up the weigh-up process.
Future improved drying capacity considerations. Any further drying capacity is possible but major capital expenditures may have to be made. Several years ago, your company had the scrubber modified to clean up the stack emissions. The increased emission efficiency increased exhaust gas flow resistance which in turn reduces the amount of air being pulled through the front of the burner. This reduction in air causes our flame to be smaller. The plant capacity prior to adding the scrubber modification several years ago will not be possible unless the air flow rate is increased back to the flow rate it used to be. In order to do this, the diesel motor and/or the fan may need to be re-sheaved or the diesel motor and/or the fan may need to bee replaced. 1) Diesel fan motor is maxed out rpm wise. I asked Detroit Diesel ( Steve, 580-256-6014) how we can tell how much horsepower the engine is producing under load. I did not get a good answer. It may be difficult if at all possible to determine this. If you direct me to research this further, I will. This information is important because the fan may improve flow rate by increasing speed. Increasing speed may exceed motor horse power capacity. Horse power requirements can be calculated at increased speed. Pressure readings across the fan will need to be taken.
I recommend that further research into the possibilities of increasing the flow rate by replacing sheaves on the existing motor/fan the diesel horse power is your next step. Should research show that is not possible, the research will show whether the fan and/or motor needs replacement. A pollution concern exists when flow rate is increased. More dust is carried into the scrubber at higher velocities making the scrubber less efficient. A modulating control to vary motor speed can slow down air flow with the dustier materials.
For your information, both trips add up to 40 hours being spent at the plant. I’ll wait any further instructions before proceeding further at that plant. The last trip focused only on production problems. April 20 From : Clarence Richard RE: Plant Gentlemen; Please review the following observations and assessments I have made on your equipment and operations. I have included pricing on some items only to give you an idea costs versus the benefits. I have no problem providing information for others to provide. Superintendent was interested in installing a damper and control on the plant. When it is all said and done, the equipment, startup and installation would run about $5,000. I noticed the fan was diesel generator driven. The significance to this is that the fan can probably be operated on variable speed by throttling the engine from inside. An actuator can be adapted to manually or automatically control the speed from within. In lieu of the damper, I recommend the variable throttle at about $2500 installed with installation help. The Exhaust Fan has no working interlock. The pressure switch fails on a regular basis. Replacing with a digital speed sensor/set-point/indicator control is recommended. This is is good for several reasons.
$500 installed Viscometer cup should be utilized. The burner fuel pressure regulator does not adjust up to the pressure like it used to. It appears to be failing. The return line valve has to be manually turned up and down to accommodate the necessary pressure requirements. This can be ordered through Hauck and I can probably offer you a 5% discount when ordered through CR Co. Maxing out production on a day like today is difficult because the material moisture is fluctuating drastically. If you decide to throttle the exhaust fan, that capability would add to better control. Combustion flighting was not checked because rain last night would have caused wet, cold material to plug up the hot bins and bucket elevator When all the above has been satisfied, a combustion analyzer should be used to tune up the burner and all the settings documented. The analyzer is a $4000 unit and it consumes it’s oxygen cells and carbon cells when used. Rental is $350/day plus my expenses.
A normally open vent valve in the burner fuel manifold does not seem to be working and in my opinion should be located between the blocking valves and not afterward. This is a safety issue. About $300.00 A Fuel Sampling valve should be placed where the vent valve is located. For safety purposes, a Low Fire position indicator light should be installed. The wires are probably available so the cost is about $150 installed When production reaches 300 tph, production becomes limited in cases where the product has high oil content (6% or so). The asphalt pump feeding the batch plant slows down the process. A bigger pump, motor and possibly starter, circuit breaker, cable and plug. ….. Batch computer manufacturer has been contacted to see if an asphalt weigh bucket safety overflow contact is supplied in the batch control. They will let us know if it is available. The problem has not occurred at this plant. My experience shows that it will happen someday. Most all batch plants not protected by this feature will experience the problem several times. It becomes quite a mess and a safety problem when the operator does not catch it in time. It is not practical to expect the operator to be able to catch it at all times. If the contact has been supplied in batcher, a couple of wires run to the Pump switch is all that is required. The burner interlock has a safety interlock bypassed because the pressure switch is bad. $75 The blower interlock was never hooked up. That requires a couple of wires from the control panel to the motor control center. Lightning was in the area when we wanted to work on the plant last night. I asked that we power down and instructed Mike how to isolate from lightning some of the sensitive components. A silo is probably justifiable to improve production and fuel efficiency. Dryer motor starter overloads are kicking out at higher productions. Overload is sized right. Voltage at the load side of the starter are proper and all the legs are balanced. Motor bearings, gear box bearings, trunnion bearings, motor may be suspect. I would like to talk to your Safety Director person about implementing Lockout/Tagout procedures, confined space procedure and oil handling procedures. If material blending control ever becomes an issue, the cold feed could be improved to the tune of about $7500 for five bins to include speed controllers and digital tachometers. Assuming I understand the system correctly, this change would make calibration significantly easier and bin speed significantly more accurate. |