Verification of network simulators

26 January 2021

In gas transmission networks, network simulators are frequently used to determine gas parameters such as calorific value and density. The application of low-maintenance, correlative measuring instruments such as the gasQS flonic (see figure 1) from Mems AG helps to compensate for the disadvantages of such programs.

Figure 1: gasQS flonic

Intensive maintenance of the network simulator

Input data for network simulators are data from gas chromatographs, flow rates, pressures and temperatures. For the calculation, the entire gas network must be modelled in detail. This includes diameter, length, radius of curvature, surface roughness of the pipes and the shape of the valves. If changes occur in the network, such as opening or closing an unsupervised valve, the corresponding parameter must be changed manually by the operator of the network simulator. This procedure is prone to errors and manual changes may be forgotten.

Cooperation with Gasverbund Mittelland AG (GVM)

GVM - one of Switzerland's four high-pressure gas network operators - has installed our ATEX-certified gasQS flonic V2 six months ago to monitor its network simulator (SIMONE). This enables GVM to continuously record the difference between the output values of SIMONE and the gasQS flonic and to intervene if necessary.

Figure 2: Density measured by gasQS flonic and simulated with SIMONE

The difference between the values of SIMONE and the gasQS flonic is in the range of 0 to 0.4 % (with a few exceptions where the difference is just under 1 %). This very small difference is in the range of accuracy of both systems. Thanks to our instrument, GVM was able to detect a failure of SIMONE in mid-March (see Figure 2 and 3). Very satisfied with the experience of the last six months, GVM has decided to install four additional instruments in their natural gas network. Furthermore, we were able to gain Erdgas Ostschweiz AG as a new customer because of the success GVM experienced with our instrument.

Application also useful for medium and distribution networks

Network simulators are usually used for transmission networks. However, large-scale consumers such as cement works and glass manufacturers increasingly demand measurement directly at the extraction points. This is particularly the case where biogas is fed into the grid, which causes significant fluctuations in the gas parameters, especially calorific value and Wobbe index. Our ATEX certified measuring instruments gasQS flonic and gasQS static offer the solutions here.