Rotordynamics, Design Aspects, Field and Operational Experiences of a Novel, Large Compressor String Supported by Active Magnetic Bearings

LecturesThe giant Groningen onshore gas field in the Northeastern Netherlands started production in 1963. About 35 years later, the decreasing reservoir pressure required a first stage of compression to provide sufficient capacity at the required 65 bar (940 psi) grid pressure. Now, a first pilot plant for a second stage of compression is installed in the accelerated cluster Schaapbulten (SCB) and started production end of 2013. The novel compression string installed consists of a 23- MW synchronous, high-speed motor in a double-end-drive configuration, driving two gearless driven 7- and 8-stage compressors. The approximate 16m (52ft) long train, with about 14mm (0,55inch) axial thermal elongation, is supported by six radial active magnetic bearings (AMBs) and two axial AMBs at the train’s non-driven ends. This contribution deals with the axial, radial and torsional rotordynamics of the AMB-supported string focusing on the two compressors, as well as with string design aspects and latest field / operational experiences. The design aspects touch points like the trade-off in the coupling selection process and resonance frequency optimizations. Field experiences concerning experimental torsional string analysis and run-out effects in combination with the closed loop AMB controller design are presented. Derived and presented improvements hav

Rotordynamics, Design Aspects, Field and Operational Experiences of a Novel, Large Compressor String Supported by Active Magnetic Bearings

LecturesThe giant Groningen onshore gas field in the Northeastern Netherlands started production in 1963. About 35 years later, the decreasing reservoir pressure required a first stage of compression to provide sufficient capacity at the required 65 bar (940 psi) grid pressure. Now, a first pilot plant for a second stage of compression is installed in the accelerated cluster Schaapbulten (SCB) and started production end of 2013. The novel compression string installed consists of a 23- MW synchronous, high-speed motor in a double-end-drive configuration, driving two gearless driven 7- and 8-stage compressors. The approximate 16m (52ft) long train, with about 14mm (0,55inch) axial thermal elongation, is supported by six radial active magnetic bearings (AMBs) and two axial AMBs at the train’s non-driven ends. This contribution deals with the axial, radial and torsional rotordynamics of the AMB-supported string focusing on the two compressors, as well as with string design aspects and latest field / operational experiences. The design aspects touch points like the trade-off in the coupling selection process and resonance frequency optimizations. Field experiences concerning experimental torsional string analysis and run-out effects in combination with the closed loop AMB controller design are presented. Derived and presented improvements hav

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Gene expression signature predicts rate of type 1 diabetes progressionResearch in context

Summary: Background: Type 1 diabetes is a complex heterogenous autoimmune disease without therapeutic interventions available to prevent or reverse the disease. This study aimed to identify transcriptional changes associated with the disease progression in patients with recent-onset type 1 diabetes. Methods: Whole-blood samples were collected as part of the INNODIA study at baseline and 12 months after diagnosis of type 1 diabetes. We used linear mixed-effects modelling on RNA-seq data to identify genes associated with age, sex, or disease progression. Cell-type proportions were estimated from the RNA-seq data using computational deconvolution. Associations to clinical variables were estimated using Pearson's or point-biserial correlation for continuous and dichotomous variables, respectively, using only complete pairs of observations. Findings: We found that genes and pathways related to innate immunity were downregulated during the first year after diagnosis. Significant associations of the gene expression changes were found with ZnT8A autoantibody positivity. Rate of change in the expression of 16 genes between baseline and 12 months was found to predict the decline in C-peptide at 24 months. Interestingly and consistent with earlier reports, increased B cell levels and decreased neutrophil levels were associated with the rapid progression. Interpretation: There is considerable individual variation in the rate of progression from appearance of type 1 diabetes-specific autoantibodies to clinical disease. Patient stratification and prediction of disease progression can help in developing more personalised therapeutic strategies for different disease endotypes. Funding: A full list of funding bodies can be found under Acknowledgments