External combustion air preheat
AssigneeLummus Technology Inc.
InventorsBaozhong Zhao, Xueping Li, Alejandro Carrillo
Life of this patent
Estimating the term…
Abstract
Systems and processes for external combustion air preheating for providing preheated combustion air to a furnace. The furnace systems convective heating section includes multiple heating coils for waste heat recovery. The heating coils may be used for preheating a feed (feed preheat coils), heating a boiler feed water, superheating steam, or heating or superheating a feed stream prior to the feed being fed to the radiant coil. The waste heat in the combustion gas is also used to heat a heat transfer fluid, which may be used to pre-heat combustion air or for other purposes within the plant.
Claims20
A furnace system for cracking hydrocarbons, comprising:
- a furnace having a radiant heating section and a convective heating section, wherein the radiant heating section includes one or more burners configured for combusting a fuel with a pre-heated air stream to produce a flue gas fed to the convective heating section;
- one or more heat transfer fluid heating coils disposed within the convective heating section of the furnace;
- one or more feed preheat coils configured for receiving and pre-heating a hydrocarbon feed to produce a pre-heated hydrocarbon feed;
- a radiant process coil disposed within the radiant heating section, configured for receiving the pre-heated hydrocarbon feed and producing a cracked hydrocarbon product;
- an air preheater having an air inlet, a preheated air outlet, a heat transfer fluid inlet, a heat transfer fluid outlet, and one or more heat exchange surfaces for indirectly heating air received via the air inlet by indirect heat exchange with a hot heat transfer fluid received via the heat transfer fluid inlet to produce the pre-heated air stream, recovered via the preheated air outlet, and a cooled heat transfer fluid, recovered via the heat transfer fluid outlet;
- one or more flow lines fluidly connecting the preheated air outlet with the one or more burners, for supplying the pre-heated air stream to the one or more burners;
- and
- a heat transfer fluid circulation system including a flow line for circulating the cooled heat transfer fluid from the heat transfer fluid outlet to an inlet of the one or more heat transfer fluid heating coils disposed within the convective heating section of the furnace, and a flow line for circulating the hot heat transfer fluid from an outlet of the one or more heat transfer fluid heating coils to the heat transfer fluid inlet.
A method of retrofitting a cracking furnace having a steam superheating coil, a boiler feedwater heating coil, and a feed preheat coil, each coil comprising multiple tubes connected to a feed header and an effluent header, the method comprising:
- disconnecting one or more tubes of the boiler feedwater heating coil from a boiler feedwater circulation system;
- fluidly connecting the one or more tubes to a heat transfer fluid circulation system;
- and
- fluidly connecting an air preheater to the heat transfer fluid circulation system and to burners of the cracking furnace.
A heater system, comprising:
- a furnace having a radiant heating section and a convective heating section, wherein the radiant heating section includes one or more burners configured for combusting a fuel with a pre-heated air stream;
- one or more heat transfer fluid heating coils disposed within the convective heating section of the furnace;
- an air preheater having an air inlet, a preheated air outlet, a heat transfer fluid inlet, a heat transfer fluid outlet, and one or more heat exchange surfaces for indirectly heating air received via the air inlet, via indirect heat exchange with a hot heat transfer fluid received via the heat transfer fluid inlet, to produce the pre-heated air stream, recovered via the preheated air outlet, and a cooled heat transfer fluid, recovered via the heat transfer fluid outlet;
- one or more flow lines fluidly connecting the preheated air outlet with the one or more burners, for supplying the pre-heated air stream to the one or more burners;
- and
- a heat transfer fluid circulation system including a flow line for circulating the cooled heat transfer fluid from the heat transfer fluid outlet to an inlet of the one or more heat transfer fluid heating coils disposed within the convective heating section of the furnace, and a flow line for circulating the hot heat transfer fluid from an outlet of the one or more heat transfer fluid heating coils to the heat transfer fluid inlet.
Dependencies are inferred from the claim text.