- increased hydroprocessing, which places increased demands on refinery hydrogen supply systems;
- a reduction in the aromatics content of fuels, which constrains catalytic reformer operations and removes some of the traditional sources of hydrogen available to refineries;
- There is also a worldwide trend towards processing heavier crude oils. To obtain the best value from these heavy crude oils, refiners must be able to convert heavy-end compounds to lighter fractions that can be blended with gasoline or diesel.
All of these trends point in the same direction: placing increasing demands on refinery hydrogen systems.
How can refiners address these challenges via more efficient refinery hydrogen systems?
Meeting increased demand for hydrogen can require significant investment in, for example, steam reformers and compression equipment. Yet most refinery hydrogen systems have significant room for improvement. By modifying the hydrogen network, perhaps with recovery of hydrogen from tail gas, refiners can often satisfy increased demand with relatively modest investment. In addition to minimising necessary new capital outlay, better hydrogen management can also lead to considerable savings from lower operating costs.
Such savings can arise from lower natural gas consumption, a reduction in the amount of fuel gas consumed or from reduced compression costs. Improvements in process performance and yield improvements are also possible via improvements to the hydrogen system. For example, increasing the partial pressure of the hydrogen feed to a hydrocracker can bring about yield improvements. Increasing the partial pressure of the hydrogen feed to a hydrotreater can improve sulphur removal.
To analyse the hydrogen system it is sensible first to establish a hydrogen balance. Conflicting and incomplete data streams are a common problem that can be overcome by the use of data reconciliation techniques. Once a hydrogen balance has been established, an assessment of hydrogen resources can be presented in a simple, graphical manner, which provides valuable insights into process design, sensitivity analysis and operations planning.
Targets can be set for hydrogen recovery and hydrogen plant production. Targets also give insights into the effective use of hydrogen purification units. These graphical targeting methods have been complemented by more detailed design methods for hydrogen distribution networks. The detailed design methods take account of distribution costs associated with different pipework and compressor layouts, and also take account of varying levels of gas impurity inherent to different stages of the hydrogen network.
PIL provides refiners not only with consultancy services but also with software and training to help address the growing challenges inherent to refinery hydrogen management - challenges that result from changes in environmental legislation, changes to the quality of crude oil supply and changes to the market for refinery products.