Diesel Particulate Filters

DPF Particulate matter filters--also referred to as Diesel Particulate Filters (or DPFs) are one of the aftertreatment products available from Empire Emissions Solutions to lower emissions from the in-use population of diesel engines. PM Filters are used primarily to reduce PM, CO, and HC from diesel engine exhaust through catalytic oxidation and filtration. These filters are self-regenerating, which means they do not need to be replaced, but instead, will "burn off" the accumulated soot periodically. For proper regeneration, the exhaust temperature must exceed 260 degrees C at least 40% to 50% of the time and the sulfur content of the diesel fuel must not exceed 50 ppm. PM Filters can reduce PM, CO and HC by 80% to 90%.

CleanAir Permit Filter Brochure

How it works:

Diesel particulate filters physically trap emission particles in the exhaust. The diesel particulate filter is a porous filter material that combusts particulate matter through a combination of filtration and chemical reactions, similar to an oxidation catalyst. Diesel particulate filters can reduce hydrocarbons (HC), carbon monoxide (CO) and particulate matter (PM) by 90 percent.

Filters can be a costly solution and they must be used in conjunction with ultra low sulfur diesel fuel (ULSD). Before making the choice to use diesel particulate filters, certain requirements (such as fuel availability) will need to be discussed with your customer.

Requirements:

For a particulate filter to be used effectively, the engine must be run with ULSD – Ultra Low Sulfur Diesel fuel. The low sulfur content of this fuel, 15 parts per million (ppm) sulfur content or less, will help lessen some of the emissions output as well as enable the filter to work to its full potential. The availability of this fuel will be a deciding factor for your customer in the implementation of this solution.

As with any emissions retrofit solution, if your customer is investing in particulate filter technology, make sure the filter is designed for their application and duty cycle. An improperly applied filter can cause catastrophic failure – to the filter or possibly to the entire engine.

Passive Filter
Active Filters
DPF Components

Passive Particulate Filter
A passive particulate filter is a standard, ceramic honeycomb structure with alternate plugged channels. A catalyst is typically upstream of the filter but may be integrated into it. In certain cases, a washcoat layer of catalytic material may be placed on the filter in addition to the catalyst.

Passive particulate filter systems rely exclusively on chemistry to regenerate. As carbon moves through the exhaust, it is trapped by the particulate filter. That filter begins to build up with carbon and other residual exhaust species, which have also become trapped. This will continue until conditions become favorable for the elements to internally combust off the filter surface. The heat for this regeneration comes from the thermal energy that occurs naturally with exhaust temperatures of typical diesel engines.

Active Particulate Filters
Active particulate filters are generally used in instances where passive particulate filters will not work because there aren’t sufficient natural activation energy levels to achieve regeneration.

Active particulate filters rely on outside energy sources. In an active particulate filter the particulate matter is trapped as it works its way through the exhaust. The control system then activates the regeneration process by auxiliary means, which raises the temperature enough to activate the chemical reaction. Active regeneration is technically possible in several ways.

FilterComponents Diesel Particulate Filters
Diesel particulate filters consist of a filter medium, a “regeneration” system and a monitoring system.