Impact of Changing Natural Gas Qualities on Industrial Combustion Processes

摘要

The markets for natural gas in Europe are in a state of transition due to a number of reasons. Some traditional domestic sources, e.g. the L-gas fields in the Netherlands, are in decline while imports from sources outside Europe will play a bigger role for Europe's gas supply in the future. The continuing integration of gases from sustainable sources into the gas infrastructure as well as political developments, such as the intent of the European Union to harmonize European gas quality standards, will also lead to profound changes in the European gas market. While this evolution offers a number of benefits, like stable gas prices, increased flexibility and security of supply as well as a reduced CO2 footprint, it also means that gas consumers will be confronted with greater fluctuations of gas quality at any given location in the grid. For some, especially in regions which have traditionally enjoyed rather constant gas qualities in the past - for example many parts of Germany - this will be a new experience. The combustion of natural gas plays an important role in many industrial production processes. In a multitude of applications, natural gas is used to provide heat for melting or heat treatment processes, for example in the glass, ceramics or metal industry. In the chemical industry on the other hand, natural gas serves both as fuel and feedstock for a variety of production processes. In general, these manufacturing processes are operated in a very narrow window of optimum performance with regards to fuel efficiency, product quality and pollutant emissions. Therefore, there is significant concern about the impact of fluctuating gas qualities on such sensitive processes. This is not a hypothetical scenario: for example, a 2011 poll among German glass manufacturers shows that many of them have already experienced problems due to gas quality changes, the main issues being reduced product quality and decreased process stability. Other industries have reported similar problems. A group of three German gas-related research institutes investigated the potential impact of changing natural gas qualities on industrial combustion processes in a research project funded by DVGW (the German Technical and Scientific Association of Gas and Water). Using literature reviews, experiments on a laboratory scale as well as measurements at semi-industrial test rigs and numerical simulations, various industrial combustion processes were analyzed and consequences of gas quality changes assessed. Also, compensation strategies were discussed. The consensus was that advanced measurement and control technologies will be required to compensate for gas quality fluctuations if the production process in question is known to be sensitive. Also, improved communication between gas suppliers and industrial gas consumers as well as a greater awareness of industrial operators concerning the issue of changing gas qualities will help mitigate their impact on industrial production processes.