Abfaelle aus polyolefinischen Materialien fallen einerseits in grossen Mengen in Form von Verpackungsmaterial oder Ein-Weg-Gebrauchsgegenstaenden beim Endverbraucher an. Andererseits werden auch bei der Herstellung von Polyolefinen, je nach Herstellungsverfahren und -bedingungen niedermolekulare und wachsartige Nebenprodukte erhalten, die nur zum geringen Teil Verwendung finden. Diese Abfaelle - sowohl die Nebenprodukte aus der Produktion als auch die Abfaelle aus dem Endverbrauch - werden zum groessten Teil verworfen und finden nur zum geringen Teil Anwendung, z.B. bei der Dampferzeugung in Kraftwerken oder Muellverbrennungsanlagen. Mit dem Forschungsprojekt soll daher geprueft werden, wie weit aus diesen Polyolefinabfaellen die Rohstoffe - Aethylen oder Propylen - oder andere Komponenten der chemischen Grundstoffproduktion - z.B. Acetylen - gewonnen werden koennen.Bei den entwickelten Verfahren wurden, im Gegensatz zu den mechanisch-thermischen Aufbereitungsverfahren, die Polyolefine einer partiellen Oxidation unterworfen. Bei dem Forschungsprojekt wurde zunaechst von ataktischem Polypropylen ausgegangen. Dies wurde aufgeschmolzen und in einem Injektionsbrenner zerstaeubt und anschliessend in einer Brennkammer mit Sauerstoff partiell oxidiert. Der Oxidationsvorgang wird dabei durch die Eigenschaften des Brennstoffnebels - Troepfchengroesse, Relativgeschwindigkeit Troepfchen/Gas- und durch die Menge des im Unterschuss eingesetzten Sauerstoffs beeinflusst. Hierdurch laesst sich die Produktverteilung bei der partiellen Oxidation, insbesondere die Konzentration an Olefinen und Acetylen, in relativ weiten Grenzen steuern.
Die Bohrdatenbank ist in wesentlichen Teilen aus der Verschlüsselung analoger Bohrungsbeschreibungen des Landesbohrarchives in digitale Daten hervorgegangen. Sie bildete den Grundbestandteil des Bodeninformations-Systems Sachsen-Anhalt (SABIS). In der Bohrdatenbank werden lokalisierende, technische, organisatorische, Schicht- und Probendaten geologischer Aufschlüsse beschrieben. Die Struktur der Datenbank orientiert sich am im LBEG entwickelten Aufschlusstyp SEP3 als Schnittstelle für den digitalen Austausch von Bohrdaten. Beschreibungen der Schichten und Dokumentation der Bohrungen werden entsprechend "Symbolschlüssel Geologie" (LBEG, 2017) verschlüsselt in der Datenbank abgelegt.
technologyComment of methanol production (GLO):
For normal methanol synthesis, reforming is performed in one step in a tubular reactor at 850 – 900 °C in order to leave as little methane as possible in the synthesis gas. For large methanol synthesis plants, Lurgi has introduced a two-step combination (combined reforming process) that gives better results. In the primary tubular reformer, lower temperature (ca. 800 °C) but higher pressure (2.5-4.0 MPa instead of 1.5-2.5 MPa) are applied.
More recently, Lurgi developed another two-step gas production scheme. It is based on catalytic autothermal reforming with an adiabatic performer and has economical advantages for very large methanol plants. At locations where no carbon dioxide is available most of the methanol plants are based on the following gas production technologies, depending on their capacities: steam reforming for capacities up to 2000 t d-1 or combined reforming from 1800 to 2500 t d-1 (Ullmann 2001). For the energy and resource flows in this inventory a modern steam reforming process was taken as average technology. To estimate best and worst case values, also values from combined reforming and autothermal reforming were investigated.
Methanol produced using a low pressure steam reforming process (ICI LPM) accounts for approximately 60% of the world capacity (Synetix 2000a). Besides steam reforming, combined reforming has gained importance due to the production of methanol in large plants at remote locations.
The reaction of the steam-reforming route can be formulated for methane, the major constituent of natural gas, as follows:
Synthesis gas preparation:
CH4 + H2O → CO + 3 H2; ΔH = 206 kJ mol-1
CO + H2O → CO2 + H2; ΔH = - 41 kJ mol-1
Methanol synthesis:
CO + 2 H2 → CH3OH; ΔH = -98 kJ mol-1
CO2 + 3 H2 → CH3OH + H2O; ΔH = -58 kJ mol-1
For an average plant the total carbon efficiency is around 75%, 81% for the synthesis gas preparation and 93% for the methanol synthesis (Le Blanc et al. 1994, p. 114). For steam reformers usually a steam to carbon ratio of 3:1 to 3.5:1 is used.
As methanol production is a highly integrated process with a complicated steam system, heat recovery and often also internal electricity production (out of excess steam), there were only data of the efficiency and energy consumption of the total process available. Therefore the process was not divided into a reforming process, a synthesis process and a purification process for estimating the energy and resource flows. Also the energy and resource flows in the methanol production plants are site specific (dependent on the local availability of resources such as CO2, O2, or electricity). In this inventory typical values for a methanol plant using steam-reforming technology were used.
The main resource for methanol production is natural gas, which acts as feedstock and fuel. A natural gas based methanol plant consumes typically 29-37 MJ (LHV) of natural gas per kg of methanol. This gas is needed as feedstock for the produced methanol (20 MJ kg-1 LHV) and also used as fuel for the utilities of the plant.
From the converted feed, 1 kg methanol and 0.06 kg hydrogen is yielded. It was assumed that the purged hydrogen was also burned in the furnace. The only emission to air considered from burning hydrogen is NOX. The energy amount generated is not considered, because the process of the furnace is specified for natural gas as fuel. The NOX emissions of the hydrogen burning were therefore calculated separately.
References:
Althaus H.-J., Chudacoff M., Hischier R., Jungbluth N., Osses M. and Primas A. (2007) Life Cycle Inventories of Chemicals. ecoinvent report No. 8, v2.0. EMPA Dübendorf, Swiss Centre for Life Cycle Inventories, Dübendorf, CH.
technologyComment of synthetic fuel production, from coal, high temperature Fisher-Tropsch operations (ZA):
SECUNDA SYNFUEL OPERATIONS: Secunda Synfuels Operations operates the world’s only commercial coal-based synthetic fuels manufacturing facility of its kind, producing synthesis gas (syngas) through coal gasification and natural gas reforming. They make use of their proprietary technology to convert syngas into synthetic fuel components, pipeline gas and chemical feedstock for the downstream production of solvents, polymers, comonomers and other chemicals. Primary internal customers are Sasol Chemicals Operations, Sasol Exploration and Production International and other chemical companies. Carbon is produced for the recarburiser, aluminium, electrode and cathodic production markets.
Secunda Synfuels Operations receives coal from five mines in Mpumalanga (see figure attached). After being crushed, the coal is blended to obtain an even quality distribution. Electricity is generated by both steam and gas and used to gasify the coal at a temperature of 1300°C. This produces syngas from which two types of reactor - circulating fluidised bed and Sasol Advanced SynthoTM reactors – produce components for making synthetic fuels as well as a number of downstream chemicals. Gas water and tar oil streams emanating from the gasification process are refined to produce ammonia and various grades of coke respectively.
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SECUNDA CHEMICAL OPERATIONS: The Secunda Chemicals Operations hub forms part of the Southern African Operations and is the consolidation of all the chemical operating facilities in Secunda, along with Site Services activities. The Secunda Chemicals hub produces a diverse range of products that include industrial explosives, fertilisers; polypropylene, ethylene and propylene; solvents (acetone, methyl ethyl ketone (MEK), ethanol, n-Propanol, iso-propanol, SABUTOL-TM, PROPYLOL-TM, mixed C3 and C4 alcohols, mixed C5 and C6 alcohols, High Purity Ethanol, and Ethyl Acetate) as well as the co-monomers, 1-hexene, 1-pentene and 1-octene and detergent alcohol (SafolTM).