DIRECT FIRED AXIAL FLOW CO-CURRENT HEATING SYSTEM FOR HOT-IN-PLACE ASPHALT RECYCLING
First Claim
Patent Images
1. A direct fired, axial flow, co-current primary heater for a hot in place asphalt recycling system, the heater comprising:
- (a) a heater container having front, rear, left, right and top sides for positioning over an asphalt road surface for travel over the asphalt in a first direction of travel, such that the bottom edges of the sides is positioned adjacent the asphalt to substantially prevent escape of gases from the interior of the container;
(b) a burner positioned at the front of the container for heating the gas in the container, the burner comprising;
(i) a combustion chamber;
(ii) a fuel injector for injecting fuel into the combustion chamber in a direction opposite to the first direction;
(iii) a first combustion gas inlet for inputting a first supply of combustion gas into the first chamber to mix with the fuel, configured to restrict the amount of gas input into the combustion chamber less than the stoichiometric amount required for complete combustion of the fuel;
(iv) a combustor for igniting the mixture of fuel and gas; and
(v) a second combustion gas inlet for inputting a second supply of combustion gas into mixture downstream of the combustor;
(c) a variable speed induced draft fan for drawing the flow of second combustion gas from the second combustion gas inlet; and
(d) a fan controller for controlling speed of the fan responsive to the amount of oxygen in the gas stream exiting the burner to maintain the oxygen above the stoiciometric amount to fully combust the fuel.
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Accused Products
Abstract
A direct fired, axial flow, co-current primary heater for use in a hot in place asphalt recycling system includes internally substoichiometric inspiriting burners operating at slightly greater than the stoichiometric amount by tertiary air flow controlled by a variable speed induced draft fan. A cool down box at the end of the burner box reduces emissions exiting at the back of the system. The sides of the burner box may pivot outwardly to increase the width of coverage.
34 Citations
29 Claims
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1. A direct fired, axial flow, co-current primary heater for a hot in place asphalt recycling system, the heater comprising:
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(a) a heater container having front, rear, left, right and top sides for positioning over an asphalt road surface for travel over the asphalt in a first direction of travel, such that the bottom edges of the sides is positioned adjacent the asphalt to substantially prevent escape of gases from the interior of the container; (b) a burner positioned at the front of the container for heating the gas in the container, the burner comprising; (i) a combustion chamber; (ii) a fuel injector for injecting fuel into the combustion chamber in a direction opposite to the first direction; (iii) a first combustion gas inlet for inputting a first supply of combustion gas into the first chamber to mix with the fuel, configured to restrict the amount of gas input into the combustion chamber less than the stoichiometric amount required for complete combustion of the fuel; (iv) a combustor for igniting the mixture of fuel and gas; and (v) a second combustion gas inlet for inputting a second supply of combustion gas into mixture downstream of the combustor; (c) a variable speed induced draft fan for drawing the flow of second combustion gas from the second combustion gas inlet; and (d) a fan controller for controlling speed of the fan responsive to the amount of oxygen in the gas stream exiting the burner to maintain the oxygen above the stoiciometric amount to fully combust the fuel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26)
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23. A burner for a primary heater of a hot in place asphalt recycling system positioned at the front of the container for directing heat axially co-current with the direction of travel of the asphalt recycling system, the burner comprising:
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(a) a combustion chamber; (b) a fuel injector for injecting fuel into the combustion chamber in the co-current direction; (c) a first combustion gas inlet for inputting a first supply of combustion gas into the first chamber to mix with the fuel, configured to restrict the amount of gas input into the combustion chamber less than the stoichiometric amount required for complete combustion of the fuel; (d) a combustor for igniting the mixture of fuel and gas; and (e) a second combustion gas inlet having a flow resistance less than that of the first combustion gas for inputting a second supply of combustion gas into mixture downstream of the combustor; (f) a fan for controlling the amount of combustion gas exiting the second combustion gas inlet; and (g) a controller, responsive to the amount of oxygen in the mixture downstream of the second combustion gas inlet, controlling the fan to maintain the amount of excess gas leaving the adjustable inlet at below about 15% above the stoichiometric amount.
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27. A process of hot in place asphalt recycling of an asphalt surface using a primary heater in a heater box, comprising the steps of:
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(a) by combustion of a fuel air mixture by a burner, creating heat and directing the heat in the heater box in an axial direction, in direction from the front to the rear of the box, co-current with the direction of movement over the asphalt, combustion by the burner comprising the steps of; (i) directing stream of fuel at high momentum in the axial co-current direction; (ii) directing a first stream of air into the stream of fuel so that first stream is entrained with the fuel, the amount of air in the first stream being insufficient to cause complete combustion of the fuel; (iii) partially combusting the fuel in the mixture of fuel and first stream of air; (iv) directing a second stream of air into the mixture, the amount of air in the second stream being sufficient, when combined with the amount of air in the first stream of air, to exceed the amount required for complete combustion of the fuel; and (v) combusting the remaining uncombusted fuel in the stream; (b) applying negative pressure in the axial co-current direction on the combustion gases and on the second stream of air; and (c) controlling the amount of excess air leaving the burner to an amount less than about 15% above the amount required for complete combustion of the fuel by controlling the amount of negative pressure applied on the second stream of air. - View Dependent Claims (28, 29)
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Specification