Key points
Syngas production – increasingly used to produce diverse synthetic products such as clothes, solvents and fuels – needs fully optimised process analytics functionality to drive production objectives and deliver an operationally efficient and safe manufacturing environment.
Synthesis gas – more commonly referred to as syngas – is a renewable fuel source that is increasingly being used across a number of process industries, including ammonia and hydrogen manufacture, ammonium nitrate/nitric acid, urea and methanol plants, refineries and coking plants.
Synthetic gas is a mixture comprising carbon monoxide, carbon dioxide and hydrogen and is produced via the conversion of a carbon containing fuel to a gaseous product that has some heating value. Typical examples of syngas production include the gasification of coal products and the gasification of industrial and municipal waste.
Syngas has 50% of the energy density of natural gas and though it cannot be burnt directly, it can be used as a valuable fuel source. It can be produced from any carbon bearing fuel, gas, liquid or solid, and its general raw material basis includes coal and petroleum-based materials, as well as other materials that would otherwise be considered as waste products.
Fuelling energy from waste
To assist the generation of syngas, waste material from municipal, industrial or other sources is being used as a feed/fuel stock for the gasification process. The feed stock is heated in a
reducing atmosphere (with very limited or no oxygen content) and the resulting gases can be used for combustion purposes immediately, or thermally treated to improve their properties.
This latter stage is referred to as advanced gasification or pyrolysis.As a renewable energy source, the conventional and advanced gasification processes are eligible for support under the Government’s Renewable Obligation Certificate (ROCs) programme, based upon a minimum calorific fuel value production. This is part of the multi-billion pound UK renewable electricity subsidy platform.
Likewise, the advent of a strong waste product stream to supply the growing gasification industry is in part driven by the wish of suppliers to avoid the financial penalties associated with landfill taxation. It is also fair to say that a number of competing technologies, processes and options are available for syngas manufacture.
Creating syngas – a challenge
The gasification process for the production of syngas whatever its original origins is not without its challenges and is driving the need for accurate, reliable and safe process analysis functionality.
Some of the measurement requirements include the need to assess the minimum calorific value of the syngas, a desire to optimise the collection of compositional data throughout the syngas production process, awareness of safety issues around the oxygen content, potential emissions monitoring and ongoing support as research or new start-up syngas production phases require enhancement.
As operational requirements drive the need for accurate and reliable process analytics, this need is further reinforced by some of the production operating conditions associated with Syngas.
Production typically takes place at extreme temperatures of up to 1200°C and pressures up to 6 bar, as well as having to deal with highly variable composition that is heavily affected by the original feedstock. This could, for instance, contain quantities of tars, solids, salts, moisture and other impurities.
The challenges of syngas production can be addressed by a number of processes that can include reforming, filtration, cooling and catalytic conversion. Most of these methods aim to improve the hydrogen, CO and CO2 content of the gasification process, and, in turn, remove
the tars, sulphurs and other impurities. At the advanced gasification or pyrolysis stage, efforts can be made to reduce the formation of undesirable compounds to lessen additional cost and resource requirements at later downstream treatment phases.
Process analytics for syngas production
– safe and reliable technology solutions to hand
With the importance of process analytics recognised across syngas production, both simple and more complex measurement applications exist within gasification plants.
Challenging measurement applications are often linked to the raw syngas stage; these involve significant sample preparation and, by association, high initial costs and substantial plant maintenance resourcing.
However:, if sample conditioning is handled correctly, utilising the latest flexible process analytic technologies now found within refinery and coke oven applications, such systems can become standard applications.
​Typical examples include hydrogen, nitrogen, water, methane, ethane, carbon monoxide, carbon dioxide, hydrogen sulphide and benzene measurement capability.
Low risk downstream analytic technology solutions are also contributing to operational efficiency objectives, using technology such as the Siemens Calomat 62 for hydrogen, Ultramat 23 for carbon monoxide, carbon dioxide and methane, and MicroSAM GC for H2, CO, CO2 and CH4 measurement.
Safety is of paramount importance on all applications where a combustible gas is present. In-situ, fast acting oxygen safety standard solutions ,such as the Siemens Sitrans SL Single Channel Oxygen Laser and the LDS6 Multi-Channel Oxygen Laser, can offer protection at the hot, dirty end of the process.
The future
In the not-too-distant future, up-scaled syngas production in large quantities will not require burning within an engine or turbine to produce electricity. It will be increasingly common for syngas to be further upgraded for use as a liquid fuel, within a fuel cell, as a chemical feedstock, or for use within the gas grid.
Syngas production is here to stay as a renewable and sustainable fuel source that is helping to alleviate significant volumes of waste going to landfill.
Its production can be truly optimised through essential process analytic technology to provide the correct level of accurate measurement to ensure syngas production takes place within a highly efficient and safe operating environment.
