Fired heater and flue gas tunnel therefor

Abstract

An improved fired heater having one or more flue gas tunnels installed in the firebox floor such that at least most of the lateral cross section of the flue gas tunnel is below the firebox floor.

Description

BACKGROUND OF THE INVENTION [0001] Hydrogen reformer units are commonly used in the petrochemical industry to produce hydrogen gas from methane and steam. One common hydrogen reformer process employs a prior art reformer heater 2 of the type depicted in FIGS. 1 and 2. The prior art heater 2 comprises: a square or rectangular radiant firebox 4; a plurality of rows 6 of process tubes 8 which extend through the radiant firebox 4 and are filled with a catalyst; a collection manifold system 10 which receives the hot process product from the lower ends of the process tubes 8; a plurality of rows of downwardly firing burners 12 installed in the top of the radiant firebox 4 between the rows 6 of tubes 8; a plurality of flue gas tunnels 14 which are constructed within the firebox 4 and extend along the floor 16 of the firebox 4 between each adjacent pair of tube rows 8 and between the outermost tube rows 8 and the side walls of the firebox 4; a plurality of inlet openings 18 through the vert...

AI Technical Summary

Benefits of technology

[0008] The present invention provides several benefits and advantages over the flue gas tunnels heretofore used in the art. Examples of the benefits and advantages provided by the present invention include: eliminating the presence of and the need to construct the vertical brick side walls of the prior art tunnels within the radiant firebox; the ability to construct the flue gas tunnels offsite and install refractory linings therein prior to shipment; significantly reducing the weight of the flue gas tunnels; allowing the addition of convenient man way doors to the firebox for workers and materials; reducing the time required to erect scaffolding within the firebox for inspection and repairs; greatly increasing the available work space and maneuverability within the firebox; significantly reducing the structural support requirements and costs of the heater; and significantly improving the distribution and uniformity of the flue gas flow within the firebox and the flue gas tunnels.

Problems solved by technology

Unfortunately, the flue gas tunnel systems heretofore used in the art have significant shortcomings and are costly and time-consuming to install, maintain, and repair.

In addition, the construction process is very time consuming and difficult due to the extremely limited space and maneuverability within the firebox 4 between the tube rows 6.

In addition, the flat lintel or tile covers 28 of the prior art tunnels 14 undergo significant fatigue when exposed to the extreme temperature conditions within the firebox over time and tend to break.

This results in the formation of cracks and holes in the covers 28 which further degrade the flue gas flow distribution and uniformity within the firebox 4 and within the tunnels 14.

Images