Do you have any numbers for the fuel savings from using an agitation boat vs. multiple agitators on a larger manure storage?
Answer:
Yes, what we find is significant fuel savings, and a much better clean-out for the time available to pump-out the lagoon.
In Detail:
Let's define "larger manure storage" as a 15 million gallon site or larger where it is common for 3 lagoon agitation pumps to be used (the long-reach models that are backed in, and then moved around during the pump out).
We'll do a comparison with the PCE Agitation Boat, model 2067-C. This unit has a 275 horsepower, Tier 3 emission engine direct coupled to a Cornell 6NHTB-17 Pump (17 inch impeller with cutter blades). This is the most popular, commonly sold boat right now. It is a 75% efficient pump where it's designed to run it in it's pump curve, and can move up to 4,000 gallons per minute at that efficiency. We will average the constant flow through the pump at 3,500 gpm. See Pump Curve at the bottom.
So most of the fuel savings is found in operating 1 engine instead of 3, but we can estimate further when we examine the models of lagoon pumps. These pumps are open-faced impeller pumps allowing them to deal very well with trash, but only allows their efficiency to be about 20%. I haven't found online data on this, but a verbal quote from a dealer was 17-19% efficient. If you look at various models of lagoon pumps and choose the best and biggest out there for the large pits (which is what you'll need), we find a large range of horsepower requirements to be 160-240 hp.
How long will we run these pumps? We can estimate the time required for agitation by taking the total gallons available and dividing by the flow rate of the pump to find total hours of agitation needed to turn the pit once. We estimate "turning it" 3 times for good agitation. During most of this time we are pumping to the field, so we won't be agitating the full amount 3 times, but we will use 3 for the ease of math. The quality of agitation should be tested with samples to see what is really happening, but we have found a multiple of 3 to be sufficient for planning purposes. Of course, you have to use good practice not to pump all the water off the top before agitation, so starting agitation before pump-out is still important.
15,000,000 gallons / 3,500 GPM / 60 minutes = 71.4 hours x 3 turns = 214.3 hours / 12 hrs per day = 17.9 days
The limiting time factor will often be in relation to the system pumping to the field. As an example, a line running at 2,000 gallons per minute for 7 hours a day (understanding that sets have to change and there is down-time on the pump-out system while the agitators are still running).
15,000,000 gallons / 2,000 GPM (to the field) / 60 min = 125 hours / 7 hrs per day = 17.9 days
FUEL:
PCE Boats are set up to run between 1600-1770 RPM. The JD engine we use, says it consumes 0.35 lb/hp-hr at 1600 -1800 RPM, and creates the necessary horsepower at this RPM. See Engine Spec
With a PCE Agitation Boat, to move on average 3,500 gallons per minute, the 6NHTB-17 pump requires 220 hp. There are about 7 pounds of diesel fuel in a gallon, so 220 hp x .34 lb/hp-hr / 7 lbs = 10.7 gallons per hour.
To generalize fuel consumption across all engines, a field guideline is: 1 gallon of diesel fuel produces about 22 horsepower. ( 220 / 22 = 10 gallons per hour. ) We'll use this rule to allow for differences in tractors and engines running lagoon pumps for our comparison purposes.
Lagoon Pumps ask for 1,000 RPM and 160 hp - 240 hp.
160 / 22 = 7.3 gallons per hour
240 / 22 = 10.9 gallons per hour
With 3 Units running:
7.3 x 3 = 21.9 gallons per hour
10.9 x 3 =32.7 gallons per hour
TIME Allowed: 214.3 hours
21.9 x 214.3 = 4,693 gallons for three 160 hp engines
32.7 x 214.3 = 7,008 gallons for three 240 hp engines
10.7 x 214.3 = 2,293 gallons for a PCE 2067-C Boat
COST @ $3.50 per gallon:
4,693 gallons = $16,425.50
7,008 gallons = $24,528.00
2,293 gallons = $8,025.50
In our custom pumping operation, we find a range of 10-16 gallons per hour for each lagoon pump. The fuel consumption depends on the tractor you are using to run the pump. We also find the boat needing only 5-8 gallons per hour, but averaging closer to 6 to produce the results we want.
3 Tractors running pumps:
13 gallons per hour x 3 engines x 214.3 hours x $3.50 = $29,252
PCE 2067-C Agitation Boat:
6 gallons per hour x 1 engine x 214.3 hours x $3.50 = $4,500
Conclusion:
In theory, at a large site of 15 million gallons or more, in comparison to running 3 lagoon pumps with 160 hp engines, the PCE Agitation Boat is twice as fuel efficient.
In our operation, at large sites of 15 million gallons or more the boat can be up to 6.5 times more fuel efficient than running lagoon pumps.
Pumps are all designed uniquely to achieve different results. This comparison is for agitation purposes at a large outdoor lagoon site. The pumps compared do not have all the same features or fill all the same needs.
In Detail:
Let's define "larger manure storage" as a 15 million gallon site or larger where it is common for 3 lagoon agitation pumps to be used (the long-reach models that are backed in, and then moved around during the pump out).
We'll do a comparison with the PCE Agitation Boat, model 2067-C. This unit has a 275 horsepower, Tier 3 emission engine direct coupled to a Cornell 6NHTB-17 Pump (17 inch impeller with cutter blades). This is the most popular, commonly sold boat right now. It is a 75% efficient pump where it's designed to run it in it's pump curve, and can move up to 4,000 gallons per minute at that efficiency. We will average the constant flow through the pump at 3,500 gpm. See Pump Curve at the bottom.
So most of the fuel savings is found in operating 1 engine instead of 3, but we can estimate further when we examine the models of lagoon pumps. These pumps are open-faced impeller pumps allowing them to deal very well with trash, but only allows their efficiency to be about 20%. I haven't found online data on this, but a verbal quote from a dealer was 17-19% efficient. If you look at various models of lagoon pumps and choose the best and biggest out there for the large pits (which is what you'll need), we find a large range of horsepower requirements to be 160-240 hp.
How long will we run these pumps? We can estimate the time required for agitation by taking the total gallons available and dividing by the flow rate of the pump to find total hours of agitation needed to turn the pit once. We estimate "turning it" 3 times for good agitation. During most of this time we are pumping to the field, so we won't be agitating the full amount 3 times, but we will use 3 for the ease of math. The quality of agitation should be tested with samples to see what is really happening, but we have found a multiple of 3 to be sufficient for planning purposes. Of course, you have to use good practice not to pump all the water off the top before agitation, so starting agitation before pump-out is still important.
15,000,000 gallons / 3,500 GPM / 60 minutes = 71.4 hours x 3 turns = 214.3 hours / 12 hrs per day = 17.9 days
The limiting time factor will often be in relation to the system pumping to the field. As an example, a line running at 2,000 gallons per minute for 7 hours a day (understanding that sets have to change and there is down-time on the pump-out system while the agitators are still running).
15,000,000 gallons / 2,000 GPM (to the field) / 60 min = 125 hours / 7 hrs per day = 17.9 days
FUEL:
PCE Boats are set up to run between 1600-1770 RPM. The JD engine we use, says it consumes 0.35 lb/hp-hr at 1600 -1800 RPM, and creates the necessary horsepower at this RPM. See Engine Spec
With a PCE Agitation Boat, to move on average 3,500 gallons per minute, the 6NHTB-17 pump requires 220 hp. There are about 7 pounds of diesel fuel in a gallon, so 220 hp x .34 lb/hp-hr / 7 lbs = 10.7 gallons per hour.
To generalize fuel consumption across all engines, a field guideline is: 1 gallon of diesel fuel produces about 22 horsepower. ( 220 / 22 = 10 gallons per hour. ) We'll use this rule to allow for differences in tractors and engines running lagoon pumps for our comparison purposes.
Lagoon Pumps ask for 1,000 RPM and 160 hp - 240 hp.
160 / 22 = 7.3 gallons per hour
240 / 22 = 10.9 gallons per hour
With 3 Units running:
7.3 x 3 = 21.9 gallons per hour
10.9 x 3 =32.7 gallons per hour
TIME Allowed: 214.3 hours
21.9 x 214.3 = 4,693 gallons for three 160 hp engines
32.7 x 214.3 = 7,008 gallons for three 240 hp engines
10.7 x 214.3 = 2,293 gallons for a PCE 2067-C Boat
COST @ $3.50 per gallon:
4,693 gallons = $16,425.50
7,008 gallons = $24,528.00
2,293 gallons = $8,025.50
In our custom pumping operation, we find a range of 10-16 gallons per hour for each lagoon pump. The fuel consumption depends on the tractor you are using to run the pump. We also find the boat needing only 5-8 gallons per hour, but averaging closer to 6 to produce the results we want.
3 Tractors running pumps:
13 gallons per hour x 3 engines x 214.3 hours x $3.50 = $29,252
PCE 2067-C Agitation Boat:
6 gallons per hour x 1 engine x 214.3 hours x $3.50 = $4,500
- These fuel comparisons also do not take into consideration the effectiveness of the clean out. With a 20% efficient pump next to a 75% efficient pump we could make the conclusion it will take 3.75 times more energy for a less efficient pump to do the same work. However, we would need a pump curve from a lagoon pump to fully draw this conclusion.
- Cost of transport for 3 tractors and lagoon pumps can also be considered in time and fuel VS transport of the agitation boat on a trailer behind a pickup. The fuel storage of the tractors will also require re-fueling the units about 3 times more often.
- Cost of ownership can be considered with average lagoon pumps selling for about $30,000 plus tractor or engine unit ($15,000 min), and the agitation boat selling at about $125,000. The boat just about pays for itself in fuel savings for some operators.
Conclusion:
In theory, at a large site of 15 million gallons or more, in comparison to running 3 lagoon pumps with 160 hp engines, the PCE Agitation Boat is twice as fuel efficient.
In our operation, at large sites of 15 million gallons or more the boat can be up to 6.5 times more fuel efficient than running lagoon pumps.
Pumps are all designed uniquely to achieve different results. This comparison is for agitation purposes at a large outdoor lagoon site. The pumps compared do not have all the same features or fill all the same needs.
