Compact Tractor Diesel Particulate Filters (DPF)

[CMV]

If I'm already at ~2k or higher RPM, it doesn't ramp up engine rpm to regen. Bush hogging at 540 PTO or tilling at a little less, tractor won't just run up to WOT to regen. It just does its thing and the smell or dash light is only way to know. I've never initiated a manual regen, but as far as the tractor doing them on its own, it doesn't increase engine rpm. Maybe if it decided to start one while the machine was sitting at a low idle or something it would?

I did notice that sometime after the 2nd regen, I get that "burning paint smell" in the exhaust all the time. Not as strong as when its actually doing a regen, but there all the time. Prior to that I only got that smell when it was in regen cycle. Is that normal? If I had to try to describe it, say on a scale of 1-10, 1 is normal exhaust smell with none of that "burning paint" (best I can describe what it smells like in regen), and 10 is in the middle of a regen with that smell very strong, for first ~80hrs or so exhaust smelled like "1" on that scale when not in regen. Since then, it's probably around a 3-4 on that scale when not in regen.

 

[RjCorazza]

My machine will not increase rpms during automatic regens. If the rpms are too low, an increase rpm light will come on requiring the operator to raise rpm. If regen requirements are not met, it gets increasingly complicated, and I believe at some point the computer takes over the throttle.
The regen stage chart from Kubota is very confusing (at least for me), and given that the last stage is auto shut down and call for service, I don’t push it.

 

[jeff9366]

Diesel Particulate Filter (DPF) captures exhaust particulates (soot) in a ceramic matrix. When tractor engine runs sufficiently hot, accumulated particulates burn off periodically without operator intervention. If engine is not run continuously hot long enough to burn off particulates, diesel soot accumulates in the matrix. Once heavy soot accumulates in DPF the tractor forces soot clearance with the tractor parked and throttle open to about 2,200 rpm for about sixteen minutes, which makes the DPF REALLY HOT to burn off all accumulated soot. Burning off accumulated soot, either during operation or parked is called REGENERATION.

Forty percent of my regenerations occur during normal operation, sixty percent parked.


Regeneration is an infrequent event for my Kubota three cylinder engine.
Generally, once every sixty engine hours. (Very consistent in Florida due to warm weather.)

60 hours X 60 minutes = 3,600 minutes.

16 regeneration minutes /3,600 = .00444 = 4/10s of 1% of engine time is consumed during parked regeneration.

Fuel cost for sixteen minute parked regeneration @ 2,200 rpm ~~$1.00.



Diesel Particulate Filter supersedes tractor muffler.
At some point in time DPF needs to be replaced.
At some point in time tractors with mufflers need the muffler replaced.

R E V I S I O N​

Diesel Particulate Filter (DPF) captures exhaust particulates (soot) in a ceramic matrix. If engine is not operated sufficiently hot to incinerate exhaust particulates continuously, diesel soot accumulates in the matrix. Burning off accumulated DPF soot during active operation or parked is called REGENERATION.

Once heavy soot accumulates in DPF the tractor forces soot incineration through static PARKED REGENERATION. During Parked Regeneration engine speed increases to about 2,200 rpm, which heats DPF sufficiently to burn accumulated soot. Soot incineration requires about sixteen minutes once DPF reaches incineration temperature.

Beginning about thirty-three horsepower most tractors have Diesel Particulate Filters.
If there is no DPF there is an alternative incendiary technology to burn off very fine particulates (soot). Sometimes exhaust heat is elevated all the time, sometimes periodically.

Diesel particulates must be burned. THERE IS NO FREE LUNCH.​

Forty percent of my Kubota regenerations occur during operation, sixty percent parked.



Regeneration is an infrequent event for my Kubota three cylinder engine.
Generally once every sixty engine hours. (Consistent in Florida due to warm weather.)

60 hours X 60 minutes = 3,600 minutes.

16 regeneration minutes /3,600 = .00444 = 4/10s of 1% of engine time is parked regeneration.

Fuel cost for sixteen minute parked regeneration @ 2,200 rpm ~~$1.00.



Diesel Particulate Filter supersedes tractor muffler.
At some point in time DPF needs to be replaced.
At some point in time tractors with mufflers need the muffler replaced.

 

[jeff9366]

A N O T H E R ~ R E V I S I O N​

Beginning about thirty-three horsepower most tractors have Diesel Particulate Filters.
If not DPF, the less used alternative emission technology is Diesel Oxidation Catalyst (DOC).
Both the DPF and the DOC are honeycomb ceramic filters.
The DOC forces engine exhaust over a honeycomb ceramic structure coated with platinum, palladium, and rhodium. These catalysts oxidize carbon monoxide and hydrocarbons into carbon dioxide and water at hot exhaust temperature.


Diesel Particulate Filter (DPF) captures exhaust particulates (soot) in a ceramic matrix. If engine is not operated sufficiently hot to incinerate exhaust particulates continuously, diesel soot accumulates in the matrix. Burning off accumulated DPF soot during active operation or parked is called REGENERATION.

Parked Regeneration is a process on diesel engines with diesel particulate filters (DPF) that temporarily changes the operating settings of the engine to generate extra-high temperatures in the DPF to combust and consume engine exhaust products (particulates/soot) that accumulate in the DPF during normal engine operation.

Soot conversion to ash requires about sixteen minutes once DPF reaches incineration temperature (500 deg F.) in warm Florida. Colder temperatures and higher altitude increase soot accumulation.

Forty percent of my Kubota regenerations occur during operation at high-throttle, sixty percent parked. Your tractor operation probably varies from mine.

DPF or DOC, your Tier IV engine has a ceramic-matrix, particulate-eliminator in the exhaust stream.
THERE IS NO FREE LUNCH.​

Regeneration is an infrequent event for my Kubota three cylinder engine.
Generally once every sixty engine hours. (Consistent in Florida due to warm weather.)

60 hours X 60 minutes = 3,600 minutes.

16 regeneration minutes /3,600 = .00444 = 4/10s of 1% of engine time is parked regeneration.

Fuel cost for sixteen minute parked regeneration @ 2,200 rpm ~~$1.00.



Diesel Particulate Filter supersedes tractor muffler.
At some point in time DPF needs to be replaced.
At some point in time tractors with mufflers need the muffler replaced.

Tire wear and tire replacement will cause as many headaches and more expense than DPF for most long term compact tractor owners who read and comprehend their Operator's Manual.

 

[jeff9366]

Beginning about thirty-three horsepower most tractors have Diesel Particulate Filters (DPF).
If not DPF, the less used alternative emission technology is Diesel Oxidation Catalyst (DOC).
Both the DPF and the DOC are honeycomb ceramic filters.
The DOC forces engine exhaust over a honeycomb ceramic structure coated with platinum, palladium, and rhodium catalysts. These catalysts oxidize carbon monoxide and hydrocarbons into carbon dioxide and water at hot exhaust temperature.


There is no catalyst associated with a Diesel Particulate Filter. A DPF is a ceramic matrix which accumulates particulates/soot at temperatures below soot ignition temperature. During regeneration, when DPF achieves and maintains at least 500 degrees Fahrenheit, the temperature of a hot kitchen oven, accumulated soot incinerates during a few minutes.


Operator Manuals for DPF equipped compact tractors do a poor job of explaining DPFs and a poor job of explaining regeneration cycles. For instance, two manuals i have viewed do not inform that soot accumulates faster during low weather temperatures, none inform time required for DPF to attain 500 degrees fahrenheit, the ignition temperature for diesel soot and none address faster soot accumulation at higher altitudes. It seems to me a DPF temperature readout on electronic instrument panels would address many DPF complaints, as would more descriptive technical writing.


As off-road diesel engines increase in displacement and horsepower emission treatment becomes increasingly complex. DPFs as a final particulate treatment are primarily associated with diesel engines <75-horespower.


Keep in mind emission standards for over-the-road diesel engined vehicles are much tighter than emission standards for off-road engines AT THIS TIME.

 

[finn1]

Work we did several years ago at an engine rom shows that biodiesel will increase passive regeneration, increasing the run time between active or forced regenerations.

There were several papers generated at the time supporting this. I’m not sure why the bio industry never picked op on this.

The dyno and field test results at the time were quite consistent.

 

[ning]

During regeneration, when DPF achieves and maintains at least 500 degrees Fahrenheit, the temperature of a hot kitchen oven, accumulated soot incinerates during a few minutes.

My reading indicates that the incineration temperature is more like 600 degrees C - centigrade/Celsius - not Fahrenheit. This puts it more like 1100F, which is far outside your typical kitchen oven's range.

Under heavy load diesel truck EGT's will reach this temperature, which allows for passive regeneration; the regen cycle is required because typically engines aren't run that hot so soot does accumulate.

 

[finn1]

My reading indicates that the incineration temperature is more like 600 degrees C - centigrade/Celsius - not Fahrenheit. This puts it more like 1100F, which is far outside your typical kitchen oven's range.

Under heavy load diesel truck EGT's will reach this temperature, which allows for passive regeneration; the regen cycle is required because typically engines aren't run that hot so soot does accumulate.

High temperatures certainly are an element of active regeneration, but much of the passive regeneration is a chemical, rather than thermal, reaction, involving NO2 to NO ratios, if I remember correctly.

It’s been a long time, so the details are fuzzy.

 

[ning]

High temperatures certainly are an element of active regeneration, but much of the passive regeneration is a chemical, rather than thermal, reaction, involving NO2 to NO ratios, if I remember correctly.

It’s been a long time, so the details are fuzzy.

I didn't mean to say that this is how passively regenerating DPF's work, but there is soot cook-off which occurs when the EGT is high enough, but typically exhaust isn't hot enough, which causes the soot to accumulate.

 

[jeff9366]

Tier IV emission controls and DPFs began to phase in ten years ago. Old news in 2019.

Consensus is DPF problems are 90% caused by operators who do not carefully read regeneration procedures in Operator's Manual or refuse to follow the procedures. Many small property users regenerate just once per year. This creates regeneration procedure uncertainty in itself. (Regeneraton occurs every ~~60 engine hours. Non-commercial users average 80 engine hours per year.)

Operator Manuals for DPF equipped compact tractors do a poor job of explaining DPFs and a poor job of explaining regeneration cycles. Most manuals do not inform that filter soot accumulates faster during low weather temperatures, none inform time required for DPF to attain 1,100 degrees Fahrenheit, the ignition temperature for diesel soot and none address faster soot accumulation at higher altitudes. It seems to me a DPF temperature readout on electronic instrument panels would address many DPF complaints, as would more descriptive technical writing.



Diesel Particulate Filter supersedes tractor muffler.
At some point in time DPF needs to be replaced.
At some point in time tractors with mufflers need the muffler replaced.

Tire wear and tire replacement will cause as many headaches and more expense than DPF for most long term compact tractor owners who read and comprehend their Operator's Manual.