GTL PLANT OPTIMIZATION

The aim of transforming natural gas (or Coal when it comes to CTL) into longer hydrocarbon molecules is primarily to add value to this gas, which is still nowadays too often flared and not sufficiently valorised. The process industry commonly needs to flare this natural gas, especially when it is a by-product of oil extraction, due to the impossibility of implementing viable gas transportation networks. Converting natural gas into usable fuel (Kerozene, Petrol, Diesel, etc...) has therefore a high added value to it, both economically, and ecologically. Some may say that this process is an energy hungry process, and therefore very polluting. However, as technology evolves and newer processes appear, energy consumption is rapidly reduced. These fuels have the big advantage of containing no sulphurs, and are therefore far less polluting than fuel originating from crude oil. One of the key aspects in reducing the energy consumption of the GTL and CTL processes lie within the way the energy is used, recovered, and thereby not wasted, along with the reduction of flaring of natural gas.

The Gas To Liquids (GTL) and Coal To Liquid (CTL) process plants are therefore;with their complex processes, the ideal sector for CPC Engineering to show its expertise in plant optimization through process controls, systems integration and compressor controls and protection.

Mainstream GTL plants use the "Fischer-Tropsch process". Multiple highly interrelated processes are operated in series:

• Natural Gas is separated from its heavier components to provide Methane through by cryogenic distillation (cold separation)
• Methane is then mixed with Oxygen and steam to be reformed in a exothermic process, the result of the reaction of the CH4+O2+H2O <--->CO/CO2/H2 and H2O within Gas reforming Unit.
• Produced syngas is then sent inside a reactor to produce longer molecules of hydrocarbon, alcohol, etc..., while tail gas is recirculated to recover lighter ends such as C, C2, C3 and C4..., which in turn are goes through another cryogenic process, methane is recycled or the gas is recovered in the fuel gas system

Each of these processes on their own are highly sensitive processes. Interconnection between each other makes the overall process a very sensitive process to run. Load variations, upsets, varying natural gas composition and many other factors influence the process, which cannot handle fast load variations.

The multivariable controls aspects of GTL plants, as well as its high temperature and high pressure requirements make these processes highly sensitive to varying load. Upset management in GTL plants is that much more crucial and is therefore critical for long term sustainability and profitability.

The major GTL key players have trusted CPC Engineering for the last 3 decades when it comes to optimizing their plants through enhanced optimal stability, flexibility and safety. These 3 key elements are the secret to a sustainable, clean and profitable GTL/CTL plant.

Our achievements in the GTL Industry:

• The start-up and optimisation of the Sasol synthetic oil from coal refinery (Sasol Two and Three, South Africa)
• The start-up and optimisation of the PetroSA-Mossgas synthetic oil from gas refinery (South Africa)
• The rectification of design deficiencies of control systems for the Sasol and Mossgas projects (South Africa)
• The design and optimisation of Advanced Control Systems for the Utilities and the Gas Processing Chain of Units at the SSF Factories (South Africa)
• The Sasol One instrument revamp project (South Africa)
• The design and optimisation of the control systems for the PetroSA/Mossgas Platform Extension Projects (South Africa)
• The design and optimisation of a Condensate and MEG Slug Management at PetroSA FA Platform Offshore plant.
• The design and optimisation of Advanced Control Systems for the steam systems at the PetroSA (South Africa)
• The Optimisation of the new PetroSA GTL Low temperature Semi-commercial plant.
• Site survey and plant optimization pre-feasibility for Oryx-GTL Plant in Qatar.
• Amongst others, Fast dynamics gas loop controls, Oxygen plant controls, water treatment plant controls,...