Simulation of Condensation in Biogas containing Ammonia

Condensation in raw biogas during compression is a problem because the CO2 and water in the liquid phase is very corrosive. Raw biogas typically contains 60 mol-% methane, 40 mol-% CO2, is saturated with water and may contain contaminants as ammonia (NH3). In case of NH3, it is of interest whether it has influence on the dew point (condensation) temperature. The aim of this work is to calculate the dew point under different conditions using different equilibrium models. Phase envelopes showing the two-phase area are also calculated. For dry mixtures of methane and CO2 with up to 1 mol-% NH3 (a high value for biogas), the different models gave similar results. When the NH3 increased from 0 to 1 mol-%, the dew point temperature increased with approximately 3 K. When water was included, the amount of calculated NH3 dissolved in water varied considerably with the model. The electrolyte based models Sour PR, Sour SRK and Electrolyte NRTL did not calculate reasonable dew point temperatures, but the dissolved amounts of NH3 and CO2 were more reasonable using the electrolyte models compared to using PR or SRK. For biogas simulation including NH3, a simple equation of state as PR or SRK can be recommended to determine the dew point. If accurate composition of the condensed liquid is to be calculated, an electrolyte based model like Sour PR, Sour SRK or the Electrolyte NRTL is recommended.publishedVersio

Detoxifying CO2 Capture Reclaimer Waste by Anaerobic Digestion

The decrease in toxicity of carbon capture reclaimer monoethanolamine (MEA) waste (MEAw) during anaerobic degradation of such waste together with easily degradable organics was investigated. Samples were collected from a bioreactor at steady state with 86 % organic chemical oxygen demand removal at room temperature, which had been running on MEAw for 2 years. The toxicity of the digester effluents were 126, 42 and 10 times lower than that of the MEAw to the tested freshwater trophic groups of Pseudokirchneriella subcapitata, Daphnia magna and embryos of Danio rerio, respectively. The toxicity of the tested taxonomic groups after anaerobic digestion was mainly attributed to the ammonia generated by the degradation of MEAw

Forvaltningsskikk og byråkratisk håndverk i krisehåndtering. Offentlige virksomheter i vekslingen mellom kontroll og strategi

For offentlige virksomheter innebar krisen som inntraff med Covid-19 i mars 2020 en akutt, ikke-planlagt og inngripende virksomhetsomlegging uten kjent tidshorisont. I denne artikkelen spør vi hva som skjer med statlig, administrativ styring når en hendelse som Covid-19 inntreffer. Datamaterialet består av deltakerbasert loggføring om temaer i ledergruppens diskusjoner, beslutninger og intern kommunikasjon i fire statlige virksomheter. En sentral del av analysen er ledernes retrospektive fortolkning av egen loggføring. Vi finner at krisen utløste et parallelt produktivitetsproblem, ved at virksomhetenes evner til å levere ble usikre, samtidig som oppdragets grunnlag gjennom behovet i samfunnet, ble uforutsigbart. Vi introduserer begrepsparet god forvaltningsskikk og godt byråkratisk håndverk for å beskrive et skifte i meningsskaping i administrativ ledelse underveis i krisen, et skifte fra kontroll og sikring mot feil, til strategiske diskusjoner om kjerneoppgaver og verdi. Funnene kan ha betydning både for teorier om institusjonell endring og kriser og praktisk kunnskap om hvordan forvaltningsvirksomheter kan håndtere store og kriselignende utfordringer.For public sector organisations, the crisis that occurred with Covid-19 in March 2020 implied an acute, unplanned, and intrusive business transformation without a known time horizon. In this article, we ask what happens to governmental, administrative control when an incident like Covid-19 occurs. The data consists of participant-based logging on topics of the management group’s discussions, including decisions and internal communication in four state agencies. A core part of the analysis is the managers’ retrospective interpretation of their own logging. We find that the crisis triggered a parallel productivity problem, in that the organisations’ ability to deliver became uncertain, at the same time as the societal need that the agencies’ role and activities was related to, became unpredictable. We introduce the concepts of administrative practice and bureaucratic craftsmanship, to describe a shift in sensemaking in administrative management during the crisis. This is described as a shift from control and safeguarding against mistakes, to strategic discussions about core tasks and value. The findings may have impact through both nuances of theories of institutional change and crises, and practical knowledge of how public administration can handle major and crisis-like challenges.publishedVersio

Tallenes klare tale: Målinger og systematisert styring i kommunal administrasjon

The thesis inquire the meaning of governing technologies based on measuring, and discuss this in relation to New Public Management. The findings are based case-studies of three Norwegian municipality adminsitrations, but also theory exploration. To use numbers, is to employ power, and the use of numbers in organizations is taking sides in dilemmas relating to standardization, quantification, modelling, and accountable communication. This is why it is difficult to criticize the use of numbers on a systematic level, but it is possible when related to one of the dilemmas these four categories represent. Also, a main argument is that numbers can colonize communicative system. Still, the meaning of measurement is ambiguous, and the study finds that translation between different understandings of numbers in organizational governance, is decisive to whether the numbers represent hidden or open governing. Further, through the third article, it is emphasized that numbers are negotiated, and that the one that is measured can, if he has power to do so, negotiate through activating other memberships or cognitive systems. The thesis shows what kinds of power are represented by the use of numbers, and that use of numbers can provide forms of transparency, but this depends on organizational context. This is further developed, by showing that other actors do have power to challenge the meaning of numbers, even when the measurement system is untouchable. The thesis is both a study of practices in measurement and systemized governing in Norwegian municipal administration in 2006, but also a study of what it means, and what we create, when we measure

Kjøretøyrelaterte avgifter : Avgiftspolitikkens innvirkning på drivstofforbruk og sammensetningen av bensin- og dieselbiler i bilparken

Den siste tiårsperioden har det vært en dramatisk overgang fra bruk av bensin til bruk av autodiesel som energikilde i veitrafikken. I denne oppgaven studeres drivkreftene bak denne overgangen ved å estimere etterspørselsfunksjoner for bensin og autodiesel og det relative forholdet mellom beholdningen av bensin- og dieselbiler i bilparken. Resultatene viser at de langsiktige substitusjonseffektene mellom bensin og autodiesel er betydelige, og at denne substitusjonen foregår gjennom endringer i bilparken. Dette tilsier at forbrukerne i stor grad responderer på avgiftspolitikken ved kjøp av drivstoff og når de skal velge mellom bensin- og dieseldrevne biler

Organizational information security culture in critical infrastructure: Developing and testing a scale and its relationships to other measures of information security

The aims of the present study are to 1) develop and test a scale measuring organizational information security culture, and 2) examine its relationships to other aspects of information security. The study focuses on an organization providing critical infrastructure. We developed the scale by conducting qualitative interviews (N = 22) and three focus groups (N = 15) in an organization providing critical infrastructure, and by reviewing previous research on culture in organisations. Based on our literature review and the interviews, we chose to measure organizational information security culture by reformulating one of the few existing general organizational safety culture questionnaires. We first tested the questionnaire in a small pilot survey, and then conducted a questionnaire survey (N = 323) including all departments in the organization. Our examination of the factor structure of the scale indicated two factors. Regression analyses indicate that our adapted GAIN-scale, measuring organizational information security culture is the most important variable influencing information security behavior in the model.publishedVersio

Simulation of Condensation in Compressed Raw Biogas Using Aspen HYSYS

Raw biogas typically contains 60 % methane, 40 % CO2, small amounts of other components and is saturated with water. It is a question whether raw biogas can be compressed to high pressures without condensation. The aim of this work is to calculate the condensation limit under different conditions with varied temperature, pressure and gas composition using different equilibrium models. Traditionally, gas mixtures of methane, CO2 and water are calculated in a process simulation program with standard models like Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK). PR and SRK with the a-function replaced with a Twu a-function were also evaluated. For mixtures with only methane and CO2 (dry biogas) all the models gave similar results. Under normal ambient temperatures (above 0 °C), a dry mixture with more than 40 % methane will not give any condensation. For biogas saturated with water, the different models gave similar results up to about 70 bar when binary coefficients were included, but above this pressure there were significant deviations between the models. The PR and SRK with standard or Twu a-function gave reasonable results for the dew-point predictions, but above about 70 bar the uncertainty increases

Simulation of Condensation in Compressed Raw Biogas Using Aspen HYSYS

Raw biogas typically contains 60 % methane, 40 % CO2, small amounts of other components and is saturated with water. It is a question whether raw biogas can be compressed to high pressures without condensation. The aim of this work is to calculate the condensation limit under different conditions with varied temperature, pressure and gas composition using different equilibrium models. Traditionally, gas mixtures of methane, CO2 and water are calculated in a process simulation program with standard models like Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK). PR and SRK with the a-function replaced with a Twu a-function were also evaluated. For mixtures with only methane and CO2 (dry biogas) all the models gave similar results. Under normal ambient temperatures (above 0 °C), a dry mixture with more than 40 % methane will not give any condensation. For biogas saturated with water, the different models gave similar results up to about 70 bar when binary coefficients were included, but above this pressure there were significant deviations between the models. The PR and SRK with standard or Twu a-function gave reasonable results for the dew-point predictions, but above about 70 bar the uncertainty increases