Page 51 - ITA Journal 3-2018

twin ball valve system was highly bene cial.
Two seals in ow direction
A further custom valve was made for the suction lines. Even the shortest TBVs were too long. Hartmann solved this problem by using a double piston system, providing two barriers in one valve. The system incorporates two seals in ow direction: one on the upstream, the other one on the downstream side. As such, it ful ls a two-barrier requirement, including a bleed-off in between.
Today, a total of 800 ball valves made by Hartmann Valves are installed, in the plant’s various facilities. Ten wells are oper- ated here, as well as natural gas compression, pressure reduction, drying and temperature control facilities. With a depth of 2,900 to 3,000 meters, the depleted gas reservoir is the deepest gas storage facility in the whole of Europe.
15 caverns in Jemgum
The Wolfersberg plant is one of the older, yet still well-functioning gas stores. Growing demand for gas, however, means more storage plants are needed. Jemgum serves
as a recent example, in 2013 gas lling of the storage facility commenced. In the next couple of years, EWE and Astora plan to construct 33 caverns in the Jemgum salt dome. EWE plans to build 15 caverns with a volume of up to 700,000 cubic meters each, Astora will realise 18 caverns with a geometric volume of up to 750,000 cubic meters.
“The marketable working gas volume is approximately 4,1 TWh. The injection rate is 2.3 GW (= 55 GWh/day), and the withdrawal rate is 2.875 GW (= 69 GWh/day),” reports Ralf Riekenberg, above- ground project manager and department head at the Jemgum gas storage plant. The natural gas stored in Jemgum is to be pro- vided mainly to the German and North-West European market.
High pressures, high differences
Jemgum was chosen thanks to its subterranean salt domes, which are especially well suited to store natural gas. The caverns being constructed are giant cavities in the salt domes, which are formed by leaching, using water. Deep under the surface the gas is safely
stored in the salt formations. Salt walls have an advantage: they seal-off especially well. “Caverns are especially suited for the fast injection and withdrawal of natural gas. Demand uctuations due to the time of day can be compensated optimally,” declare project partners EWE and Astora.
Valves make sure everything runs smoothly at the Jemgum storage plant. “They are used for pres- sure control, pressure protec- tion and transmission control,” explains project manager Rieken- berg. Valves are mainly made from steel, and “in most cases exposed to high pressures and pressure dif- ferentials”. The pressure range lies between 40 and 170 bar, the tem- perature range between -20 and 150 °C, and the ow rate between 20,000 m3/h and 250,000 m3/h. Valves installed in the gas storage plant are exposed to glycole, which is used to dry the gas, and water, which, in turn, is used to pre-heat the gas. These create challenges the safety, control and shut-off valves have to overcome.
Gas is compressed
And this is how the Jemgum gas storage plant works: the natural
Technical Papers
ITAtube Journal No3/October 2018
51