Monitoring flow rate towards gas lights in municipal street lighting

Measuring gas flow rate in gas pressure throttling stations for gas lights

Background and history of gas lighting

As early as 1843 first steps for building a gas disribution system to supply gas lights illuminating Düsseldorf’s city were taken. Back then Sinzig & Cie delivered gas to the city – apparently of very bad quality which led the city to build their own gas distribution system. In 1866 the first municipal gas works was put into operation. The gas distribution system was about 6km long and supplied 753 gas lights. Two years later it provided gas for 1866 customers and 800 lights. Today the natural gas distribution system covers 1.462 km without, and 2.014 km with house connection pipes. It contains of 69,000 connection points, 118,000 gas meters and 14,000 street lights.

Preservation of the street lights in Düsseldorf with gas lights

On 14.05.2020 the city council decided to preserve a large part of the city’s historical gas lighting. Today Düsseldorf is the only german city alongside Berlin to still operate gas lights.

 

Controlling gas lights for street lighting

Düsseldorf’s gas distribution is operated with a low-pressure network with a pressure of 70 mbar. The maximum allowable pressure in the system is 100 mbar.


Each gas light has a continuously burning pilot light. To light the gas lights at night a pressure wave is sent out raising the pressure about 30 mbar operating as a ripple control signal. Pressure rise control is not trivial. It must be ensured that the pressure wave reaches every gas light. Pressure measurement as well as a combined measurement of pressure and duration of the pressure rise didn’t deliver the desired effect. Measuring actual flow rate in combination with pressure measurement gives us the required pressure surge. Thereby it can be ensured that the required volume for the rise in pressure is supplied and independent from further disturbances such as changes in tube geometry (changes in diameter).


For control purposes flow rate measurement was installed in every gas pressure control system in the area of the gas pressure control system.

 

Assembly in the station

The measuring instruments were installed behind the gas pressure control system at the plant’s outlet in the low pressure area.
For many years Höntzsch vane wheel sensors type ZS25 have been working succesfully in this application.