Page 52 - ITA Journal 3-2018

Technical Papers
gas to be stored is transported from the gas transmission net to the storage facility. Compressors then condense the gas natural gas to a pressure of up to 200 bar before injecting it into the caverns. “Driven by pressure, the natural gas passes the cavern head, the heart of each natural gas storage facility,” explain EWE and Astora. After passing through the cavern head, the natural gas is then stored in the cavern, and can be withdrawn on demand.
Up to 150,000 m3 of natural gas can be withdrawn from a cavern per hour. Before withdrawal, the gas pressure needs to be reduced to the pipeline pressure level. “This cools the gas so much that it has to be pre-heated,” state the Jemgum operators. Gas can be stored up to several months in a cavern. During storage, the natural gas comes into contact with the cavern oor, which emits water vapour. The gas is subjected to a dehydration process, making sure no condensation occurs in the pipelines.
High ow rates
Gas storage plants pose a chal- lenge for components: high ow
rates occur when opening and closing shut-off valves. Contami- nations carried along in the media hit the seal area of the valve at extreme speeds. Soft-sealing systems are quickly damaged, and become leaky. “A pure metallic sealing system makes valves more robust, and as such more relia- ble and durable,” states Maurice Walter, head of sales and service at Hartmann Valves. The metallic seal between ball and seat ring is more resistant than soft-sealing systems – especially if media is contaminated.
Failure-free availability is impor- tant, and the seal needs to remain safe for several years. The valves therefore not only need to be gas-tight and reliable, but also low-maintenance and durable, adds Walter. These aspects need to be considered when selecting the proper combination of materi- als, in order to ensure a gas-tight- ness over a long period of time.
Stressful corrosion and throttling function
Hartmann Valves supplied the Jemgum gas plant with DN 200 and DN 600 ball valves. The brine pipeline line was supplied with
ball valves with nominal diame- ters DN 500 and DN 900. Deploy- ment in the Jemgum brine plant and pipeline placed particularly high demands on the valves, as the saturated salt solution causes a great degree of corrosive stress. To ensure a maximal service life, the Hartmann tailor-made valves received an internal plastic coating, in addition to the pure metallic sealing system.
The ball valves in the nominal diameters DN 200, 250, 300 and 400 for the gas plant have an innovative throttling function. The main gas line can thus be opened at full differential pres- sure. The ball valve is used for controlled pressurisation during throttling, afterwards the entire pipeline cross section is available. This simpli es operation, doing away with the need for complex bypass lines.
Adding capacities
The increasing use of renewables makes further storage capacities necessary. Ten years after being put into operation, the Haidach natural gas storage facility in Austria will receive a further con- nection line to increase the level of integration with the German energy market. The planned pipe- line in the region Burghausen/ Überackern will use the MONACO natural gas pipeline to connect the storage facility with the German pipeline network. “Since the capacities of the transport network that is already connected are at full capacity utilization, the additional connection line is an important investment in a needs-based natural gas supply in South Germany,” explains Astora GmbH & Co. KG, a subsidiary of the Wingas Group.
ITAtube Journal No3/October 2018
52