(91f) A Successful Approach to Improve Energy Utilization in Ethylene Crackers

Energy can represent 40 - 45% of the cost to produce ethylene in an olefins plant. With the recent increases in energy costs and corporate commitment to reducing CO2 emissions, Shell Chemical has embarked on a program to identify and implement quick payback energy reduction opportunities in its ethylene plants. The Energize program has successfully reduced energy and reduced variable costs by 3 to 5 % at the ethylene plants with short implementation time, quick payback projects. Energize projects identified and implemented at the ethylene plants include operational changes, and expense and low capital cost projects which have resulted in energy reduction, reliability improvement, yield improvement, and capacity creep (debottleneck).

Shell has found that the plant engineers and specialist are very busy operating the units and do not have the time to work on energy improvement projects. Many good ideas that staff and operators have that require further evaluation and development never get worked on. The Energize team brings additional process engineer resources into the plant to work with the staff to scope and implement the projects. Working closely with plant insures staff ownership of the projects to insure the savings are sustained after Energize team leaves. The paper will discuss makeup of an Energize team, methodology of study, and the timeline for implementing a plant program.

In the chemical plants and in the ethylene crackers, projects have been found in range of areas from simple equipment improvements (turbine efficiency, furnaces, steam trap maintenance) to more complex projects like adjusting fractionation conditions, optimizing steam headers, and process heat integration. Examples of projects implemented at the Moerdijk, Norco and Deer Park ethylene plants will be discussed. Several projects from the following examples will be discussed in the paper: o Optimizing pump-around on pyrofractionator o Innovative balancing of low pressure steam header supply/demand between two crackers to reduce venting of steam o Installation of liquid pumping trap to permit lowering of process gas compressor suction pressure o Troubleshooting and improving vacuum on surface condensers o Analysis of unit equipment and column flooding constraints to allow operation with colder cooling water during winter months o Adjusting levels in refrigerant condensers o Improved insulation in furnace penthouses to reduce excess air leakage into firebox.