Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Including heat exchanger for reaction chamber or reactants...
Reexamination Certificate
1998-12-21
2001-02-27
Howard, Jacqueline V. (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Including heat exchanger for reaction chamber or reactants...
C110S185000, C431S008000, C431S351000
Reexamination Certificate
active
06193940
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a firing system for a thermal cracking furnace and, more particularly, a firing system for a thermal cracking furnace of the type having hearth burners for heating radiant walls of the furnace to thereby effect heating by radiation of radiant coils.
A thermal cracking furnace thermally cracks a hydrocarbon feedstock such as naphtha, ethane, and propane during circulation of the feedstock through radiant coils suspended within the furnace. Coke and tar products produced by pyrolysis of the hydrocarbon feedstock during the cracking process leads to eventual fouling of the radiant coils, necessitating cleaning (decoking) or replacement of the coils. The selectivity, yield, and run lengths between decoking cycles are typically closely related to the heat flux profile along the vertical extent of the radiant coils.
The thermal cracking process involves combustion of a fossil based fuel such as gas in a manner which unavoidably results in the creation of NO
X
. NO
X
emissions are recognized to be a significant source of air pollution. Thus, environmental emissions standards have been and continue to be imposed by various governmental authorities which limit the amount of NO
X
gases which can be emitted into the atmosphere. Several designs have been proposed to inhibit the production of NO
X
gases including designs which limit the production of NO
X
gases due to the mixing of fuel and furnace or flue gases for combustion in a combustion zone of a thermal cracking furnace. Although these designs may be advantageous, there still remains the need for burner designs for a thermal cracking furnace having improved NO
X
reduction characteristics.
SUMMARY OF THE INVENTION
The present invention provides, in one aspect thereof, a firing system for a thermal cracking furnace of the type having a furnace enclosure formed by a plurality of sidewalls and plurality of radiant coils disposed in a row in the furnace relative to a lengthwise extent thereof for passage therethrough of a material to be subjected to cracking. The firing system includes a plurality of air inlets for introducing air into the furnace interior, the air inlets being generally arrayed along a lengthwise row on the floor of the furnace at a predetermined proximity to one of the sidewalls as measured along a widthwise extent of the furnace perpendicular to its lengthwise extent, and a plurality of start up ports disposed intermediate the row of air inlets and the radiant coils relative to the widthwise extent of the furnace. The start up ports are generally arrayed along a lengthwise row on the floor of the furnace and being operable to introduce fuel into the furnace.
The firing system of the one aspect of the present invention also includes a plurality of normal operation ports disposed intermediate the row of start up ports and the radiant coils, the normal operation ports being generally arrayed along a lengthwise row on the floor of the furnace and being operable to introduce fuel into the furnace. The firing system further includes means for selectively controlling the overall supply of fuel to the start up ports and the normal operation ports to effect supply of fuel solely to the start up ports during a start up mode of operation of the firing system and supply of fuel solely to the normal operation ports during a normal mode of operation.
REFERENCES:
patent: 3706445 (1972-12-01), Gentry
patent: 5156098 (1992-10-01), Camp
patent: 5394837 (1995-03-01), Tsai et al.
Kang Shin G.
Richards Galen H.
Toqan Majed A.
Winkler Dieter
ABB Alstom Power Inc.
Doroshenk Alexa A.
Howard Jacqueline V.
Warnock Russell W.
LandOfFree
Firing system for the improved performance of ethylene... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Firing system for the improved performance of ethylene..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Firing system for the improved performance of ethylene... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2559154