Convection zone of a cracking furnace
AssigneeLinde Aktiengesellschaft
InventorsStefan GLOMB, Robert STEGEMANN, Gunther SCHMIDT
Life of this patent
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Abstract
The invention relates to a process for cracking a hydrocarbon-containing feed in a cracking furnace. A plurality of heat exchangers are arranged in the convection zone of the cracking furnace to utilize the heat of flue gas formed in the radiation zone by combustion. Depending on the type and state of matter of the hydrocarbon-containing feed, flow occurs through the heat exchangers to achieve, independently of the type and state of matter of the hydrocarbon-containing feed, an exit temperature of the flue gas in the range from 80° C. to 150° C.
Claims21
A process for preparing hydrocarbons by thermally cracking a hydrocarbon-containing feed in a cracking furnace having a radiation zone and a convection zone, said process comprising:
- the thermally cracking said hydrocarbon-containing feed in said radiation zone wherein flue gas is generated,
- introducing the flue gas from the radiation zone into the convection zone as a heat transfer medium,
- preheating and/or vaporizing the hydrocarbon-containing feed in at least one heat exchanger arranged in the convection zone wherein the hydrocarbon-containing feed undergoes heat exchange with the flue gas, and
- heating and/or vaporizing boiler feed water in at least one heat exchanger arranged in the convection zone wherein the boiler feed water undergoes heat exchange with the flue gas,
- wherein the temperature of the flue gas on exiting the convection zone varies, independently of the state of matter of the hydrocarbon-containing feed, in a range of 30° C. and is less than 150° C. and
- wherein the streams in the heat exchangers of the convection zone are regulated in the process in such a way that, depending on the state of matter of the hydrocarbon-containing feed,
- for a given state of matter of the hydrocarbon-containing feed, virtually 100% of the heat transfer area of all heat exchangers in the convection zone participates in heat exchange with the flue gas,
- during operation when the hydrocarbon-containing feed in the other state of matter only a prescribed fraction of the heat transfer area of all heat exchangers in the convection zone participates in heat exchange with the flue gas or
- the feed stream to at least one heat exchanger in the convection zone is regulated so that the efficiency of heat exchange in this at least one heat exchanger(s) decreases.
An apparatus for thermally cracking a hydrocarbon-containing feed, said apparatus comprising:
- a cracking furnace having a radiation zone and a convection zone,
- said radiation zone comprising at least one cracking tube for cracking hydrocarbon-containing feed,
- said radiation zone being heated by firing thereby forming a flue gas,
- said radiation zone having a flow connection whereby flue gas can flow from said radiation zone to said convection zone,
- said convection zone having at least one heat exchanger for preheating and/or vaporizing hydrocarbon-containing feed having a feed line for introducing hydrocarbon-containing feed and wherein said at least one heat exchanger for preheating and/or vaporizing hydrocarbon-containing feed having a flow connection to at least one cracking tube in said radiation zone,
- said convection zone having at least one heat exchanger for preheating and/or vaporizing boiler eater feed, said at least one heat exchanger for preheating and/or vaporizing boiler eater feed having a feed line for introducing boiler feed water,
- wherein at least one feed line to at least one heat exchanger in said convection zone having a regulating valve or shutoff valve, and
- wherein a feed line (9, 19, 11) of at least one heat exchanger (5) in said convection zone for heating boiler feed water has a shutoff valve (19) and the feed or discharge line (9, 10) of at least one other heat exchanger (4) for heating boiler feed water in said convection zone has a shutoff valve or a pressure drop element (20), where the shutoff valve (19) of the feed line (9, 19, 11) to the at least one heat exchanger (5) connects a boiler feed water feed line (11) of the at least one heat exchanger (5) to a boiler feed water feed line (9) of the at least one other heat exchanger (4).
Dependencies are inferred from the claim text.