Sectioned exhaust filter system
In accordance with at least one embodiment of an exhaust treatment system whereby parallel sections of exhaust filters such as Diesel particulate filters (DPF's) and a catalyst such as a selective catalytic reduction (SCR) system are integrated together while efficiently maintaining the temperature requirements of both. The parallel exhaust filter sections that may be heated and/or regenerated individually thereby facilitating catalyst temperature control and modulation of pressure drop across the exhaust filters.
1. A sectioned exhaust treatment system comprising:
a) an enclosure with an inlet and an outlet, whereas said inlet receives exhaust gas from an exhaust gas source, wherein said exhaust gas source is at least one item selected from the group consisting of diesel engines and boilers and internal combustion engines and turbine engines and sources of combustion;
b) said inlet in fluid communication with at least four parallel exhaust filter sections wherein each exhaust filter section includes an exhaust filter section inlet, a variable heat source, a filter element, and an exhaust filter section outlet;
c) all said exhaust filter section outlets being combined to form a recombined flow in fluid communication with a catalyst;
d) said catalyst in fluid communication with said outlet;
e) a temperature sensor positioned in said recombined flow, wherein said temperature sensor measures an exhaust gas temperature;
f) said temperature sensor in communication with a controller;
g) said controller in communication with each said heat source;
whereby, said controller modulates at least one said heat source as required to periodically regenerate said exhaust filter sections and modulate said exhaust gas temperature.
2. The system of claim 1 , wherein said catalyst is a selective catalytic reduction (SCR) system.
3. The system of claim 1 , wherein each exhaust filter section further comprises a normally open exhaust gas flow modulating valve, whereas said valve is at least partially closed during a regeneration cycle to reduce exhaust gas flow through said exhaust filter section whereby reducing the amount of heat required to achieve a regeneration temperature during said regeneration cycle.
4. The system of claim 1 , wherein a sensor in communication with said controller measures the pressure drop across said exhaust filter sections, wherein said controller modulates the number and duration of exhaust filter regeneration cycles to optimize said pressure drop.
5. The system of claim 1 , further comprising a reductant injector located downstream of said exhaust filter sections and upstream of said catalyst.
6. The system of claim 1 , further comprising an exhaust gas mixer located downstream of said reductant injector and upstream of said catalyst.
7. The system of claim 1 , wherein said exhaust filters occupy a single enclosure.
8. The system of claim 1 , wherein said heat source is selected from the group consisting of electric heaters and gas-fired heaters and oxidation catalysts and conductive filter elements.
9. The system of claim 3 , wherein said exhaust gas flow modulating valve is selected from the group consisting of normally open butterfly valves and plunger valves and slide valves and blocking flaps and blocking members and expanding diaphragms and expanding bladders.
10. A method comprising;
a) an exhaust gas stream is split into parallel streams through at least four parallel exhaust filter sections;
b) said parallel streams are recombined into a single recombined stream;
c) said recombined stream is urged through a catalyst;
d) an adjustable amount of heat is selectively added to said parallel exhaust filter sections;
e) a single temperature sensor placed in said recombined stream transmits a temperature measurement to a controller;
f) said controller sequentially modulates said heat to regenerate said exhaust filter sections while concurrently controlling said temperature of said recombined stream;
whereby predetermined regeneration temperatures are achieved in said exhaust filter sections while concurrently maintaining a predetermined temperature in said recombined stream as required for optimized function of said catalyst.
11. The method of claim 10 , wherein said catalyst is a selective catalytic reduction (SCR) system.
12. The method of claim 10 , wherein said parallel stream is individually modulated by a normally open valve to reduce gas flow during an exhaust filter regeneration cycle whereby reducing the amount of heat required to achieve regeneration temperature.
13. The method of claim 10 , wherein a sensor in communication with said controller measures a pressure drop across said exhaust filter sections, whereby said controller modulates frequency and duration of said exhaust filter regeneration cycle to optimize said pressure drop while said controller concurrently maintaining said temperature of said recombined stream.
14. The system of claim 10 wherein said exhaust filters occupy a single enclosure.
15. The system of claim 10 wherein said heat source is selected from the group consisting of electric heaters and gas-fired heaters and oxidation catalysts and conductive filter elements.
16. The system of claim 12 wherein said valve is selected from the group consisting of normally open butterfly valves and plunger valves and slide valves and blocking flaps and blocking members and expanding diaphragms and expanding bladders.