Process For Heating A Hydrocarbon Stream Entering A Reaction Zone With A Heater Convection Section

Abstract

An exemplary process can include passing a hydrocarbon stream through a reforming unit. The reforming unit may include a heater, which in turn generally includes a convection section and a radiant section, and a plurality of reforming reaction zones. Generally, the hydrocarbon stream is heated in the convection section for reacting in one of the reforming reaction zones to which the hydrocarbon stream is sent and the hydrocarbon stream is heated in the radiant section of the heater for reacting in the other reforming reaction zone to which the hydrocarbon stream is sent.

Description

FIELD OF THE INVENTION[0001]The field of this invention is heating a hydrocarbon stream entering a reaction zone.BACKGROUND OF THE INVENTION[0002]Hydrocarbon conversion processes that are exothermic or endothermic can be employed in the petroleum refining or petrochemical production industry. An exemplary hydrocarbon conversion process for improving the octane quality of hydrocarbon feedstocks is catalytic reforming where the primary product of reforming being motor gasoline or a source of aromatics for petrochemicals. The art of catalytic reforming is well known and a brief detailed description is provided below.[0003]Generally, in catalytic reforming, a feedstock is admixed with a recycle stream comprising hydrogen to form what is commonly referred to as a combined feed stream, and the combined feed stream is contacted with a catalyst in a reaction zone. The usual feedstock for catalytic reforming is a petroleum fraction known as naphtha and having an initial boiling point of abou...

AI Technical Summary

Benefits of technology

[0023]Desirably, using the convection section of one or more heaters to heat the feed to one reactor and setting the inlet temperatures of the reactors, it is possible to replace a radiant section of a heater or furnace with a convection section. This can reduce the capital and catalyst cost, and fuel and flue gas flow at the same time, so the emissions from the unit (e.g., CO2, SOX, NOX) may also be reduced. Also, utilizing the convection sections and a skewed temperature profile can permit the shift of heat duties from the front end to the back end. Thus, the size of the furnaces can be standardized to reduce capital costs. Moreover, such an arrangement can obtain increases in yield, such as an increase of 0.1%. Moreover, the embodiments herein may allow a ratio of heater radiant sections to reaction zones of less than 1:1, such as 3:4 or 2:3.INFORMATION DISCLOSURE

Problems solved by technology

The heating of the combined feed stream that occurs in the combined feed heat exchanger is generally, however, insufficient to heat the combined feed stream to the desired inlet temperature of the first reactor.

Consequently, after exiting the combined feed heat exchanger and prior to entering the first reactor, the combined feed stream often requires additional heating.

A flat profile could result in imbalance of the operating duties of the heaters in the train, if some of the operating variables such as feedstock quality or throughput differ significantly from their design values, or if flow maldistribution or mechanical problems cause the performance of a reactor to fall significantly below its expected performance.

The relatively low temperature at the combined feed exchanger outlet can lead to a higher reaction temperature requirement for the subsequent reactors if overall catalyst loading is constant and the first heater duty is higher and unbalanced as compared to the other heaters.

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