Revamping of a process furnace in a chemical plant in Brazil

By AITESA

Introduction

In 2016 AITESA executed the expansion project of furnaces H-1201 and H-1451 at a chemical plant in Bahia (Brazil). The main objective of the project was to replace the existing convection section of both furnaces with a new convection section of larger dimensions to improve the draft of the furnaces.

Solution

Validation of the thermal and hydraulic design of the furnace.
Validation of the heat recovery system for the new operating conditions.
Isometrics of process lines to furnace H-1451, including flow meters.
Design, manufacture and transport to the plant of the new convection sections.
Design, manufacture and transport of the H1201 ducting, which directs the hot fumes from the H-1201 furnace to the H-1451 furnace chimney.
Structural calculation of the furnace.
Design of the necessary modifications to the radiant zone for the installation of the new convective systems.
Mechanical design of the draft control damper of furnaces H-1201 and H-1451.
Development of assembly and disassembly procedures
Assembly supervision

Results

Unit H-1201 is a vertical cylindrical furnace with a capacity of 8.36 Gcal/h and a fuel efficiency of 92%. It operates with fuel gas or process gas. It serves the PACOL process (radiant zone tubes) and thermal oil (convective zone). The H-1451 furnace is also a vertical cylindrical type, with a capacity of 26.77 Gcal/h and a fuel efficiency of 92%. It operates with natural gas or process gas. It serves the thermal oil system in both the radiant and convective zones. It is verified that the existing burners are valid for the new operating conditions, since the required release is below the design release of these burners. Furnaces H-1201 and H-1451 have partially shared heat recovery. The fumes from both furnaces are routed jointly to the common heat recovery system. However, the heat recovery system has two independent air circuits for each furnace. The air preheater, forced draft fans and induced draft fans of the heat recovery system were analysed in detail. Also the operation of the associated dampers, actuators, limit switches and solenoid valves were checked with satisfactory results.