(45j) High Efficiency Ethylene Cracking Furnaces

High Efficiency Ethylene Cracking Furnaces

Rajaram Ramesh[1], Marco W.M. van Goethem

TECHNIP Benelux B.V., P.O. Box 86, 2700 AB Zoetermeer, The Netherlands.

Abstract prepared for:
The 25^th Ethylene Producers’ Conference, April 28 – May 2, 2013, San Antonio, USA.
Ethylene Plant Environmental/Maintenance Joint Session

 
Abstract

The environmental and economic pressures generate in general a driving force to produce products more efficiently. A direct effect of more efficient processes is that the emission of green house gases, particularly carbon dioxide decreases. In households nowadays “high efficiency furnaces” are available which have an overall efficiency in the range of 94-97%. This paper describes the outcome of a feasibility study to the application of the high efficiency furnace concept to ethylene steam cracking furnaces. The high efficiency is achieved by enhanced heat recovery from the flue gases before they are released to the atmosphere at ca. 65°C.

Technip performed a study on the application of this concept for steam cracking furnaces based on gas and liquid feedstocks. This paper is a report on the outcome of the study. Natural gas was used as basis for the energy price. The evaluation was done for two locations: one for the US using US natural gas prices and the other for Europe using average EU price. The impact of CO₂ credits has been investigated as well.

Two alternative heat sinks have been considered: preheating of combustion air and preheating of cold hydrocarbon feed. Both are viable for liquid cracking furnaces. Feed preheating is not attractive for gas cracking furnaces as it results in a pinch and is hence not considered.

Capital costs are based on quotations from air preheater vendors. Special attention has been paid to the material selection of the affected convection section banks.

This study shows that high efficiency ethylene cracking furnaces are economically viable. For Europe the study, excluding CO₂ credit, indicates an attractive payback period. In the US the payback period is longer due to the lower energy prices. As energy prices are expected only to increase in the future, the concept’s viability will become better. With CO₂ credits the payback period is even more attractive.