Pre-combustion

Installing a pre-combustion chamber (PCC) in the engine design solves this problem. In this design, a normal A/F ratio fuel is introduced into a PCC at the time of ignition. This creates ignition torch-... 

Current C02 capture technology (first generation) is adapted from gas separation processes already in industrial use. There are several technologies and strategies to capture C02 from stationary sources pre-combustion, post-combustion and oxy-fuel (Figure 2). 

In pre-combustion C02 capture, C02 separation occurs prior to fuel combustion and power generation (Figure 5). The fuel reacts at high temperature and pressure with either oxygen or/ and steam under sub-stoichiometric conditions, and thereby a gas stream primarily composed of CO and H2 is obtained. This CO/H2 gas mixture is commonly known as synthesis gas or syngas. 

Figure 5. Simplified scheme of an integrated gasification combined cycle (IGCC) coupled with a pre-combustion C02 capture and storage unit using a physical absorption process [5].

For practical purposes, the distinction between dissolved organic carbon and particulate organic carbon is that the latter is retained on filters of known porosity. Membrane filters with 0.25-1. Oum pore size and glass fibre Whatman G F/C filters are commonly used. By using the particulate fraction of a sample retained on pre-combusted Whatman G F/C filters for... 

In the field of electricity generation, in particular, intensive research is carried out on capture processes, as this industrial sector contributes heavily to worldwide greenhouse-gas emissions. Basically, three concepts for C02 capture in electricity generation can be distinguished post-combustion capture, pre-combustion capture and oxyfuel (see Fig. 6.1 for a detailed description of the various capture processes, see, for example, BMW A (2003) IPCC (2005)). 

Carbon dioxide capture and storage is especially studied in connection with electricity generation, where different technology routes - post-combustion capture, pre-combustion capture and oxyfuel combustion - are under research and development. Carbon dioxide capture is also crucial in connection with hydrogen production... 

ATR is used widely, although costs are relatively high due to the high capital and energy costs related to the cryogenic air separation plant (approx. 40% of the total capital costs). For large-scale plants, however, such as gas-to-liquid plants, but also possibly natural gas based power stations with pre-combustion C02 capture, ATR becomes more economic than SMR [7]. 

For combined hydrogen production and C02 capture several novel technologies are in development, most of them for the application in a pre-combustion C02 capture combined cycle. The main focus is to reduce the efficiency penalties and other associated costs of CO2 capture. The most important technologies in the R D phase, membrane reactors and sorption-enhanced reactors, are described below, with special attention paid to the catalytic aspects. 

To improve the efficiency of combined hydrogen production and C02 capture, several technologies are in development that combine catalytic reactions and the separation of either hydrogen or C02. Major targeted areas of application are the production of bulk hydrogen as a transport fuel and electricity production with pre-combustion C02 capture. 

J.W. Dijkstra, Y.C. van Delft, D. Jansen, P.P.A.C. Pex, Development of a hydrogen membrane reactor for power production with pre-combustion decarbonisation, Proceedings of the 8th International... 

J.W. Dijkstra, D. Jansen, R.W. van den Brink, Sorption-enhanced hydrogen production for pre-combustion C02 capture thermodynamic analysis and experimental results, Int. J. Greenhouse Gas Control. Vol. 1 (2007) 170-179. 

Air-sampling detector Actively and continuously samples the air from a protected space and is able to sense the pre-combustion stages of incipient fire. 

Treated flue gas contains C02, N2, 02. Since N2 and 02 form hydrate crystals at approximately the same conditions the treated flue gas is considered a C02/N2 mixture. Thus in post-combustion capture from power plants the task is to separate C02 from a C02/N2 mixture in which the C02 molar content is approximately 15-20 %. Pre-combustion capture involves separation of C02 from a mixture with H2 in which the C02 molar concentration is approximately 40 % (Klara and Srivastava, 2002 Kang and Lee, 2000 Englezos and Lee,... 

Linga, P. Kumar, R. Englezos P. (2007b). The clathrate hydrate process for post and pre combustion capture of carbon dioxide. J Hazardous Materials, revised submitted May 10, 2007... 

Combined Cycles with coal gasification, pre-combustion capture of COj. 

Computation of the thermodynamic efficiency in a steam cycle (1) inlet, (2) pre-combustion, (3) post-combustion, pre-compressor, (4) post-turbine to exhaust, (5) gas inlet. 

Growing concern over environmental effects of acid rain has resulted in increased Interest in development of pre-combustion removal of sulfur from coal. Physical coal cleaning processes are effective for pyritic sulfur removal but do little to reduce the organic sulfur content of coal This paper reports the removal of organic sulfur from coal, employing ethyl or methyl alcohols as the solvent/ reactant. The process is based on the observation that, under supercritical conditions, reactions occur that selectively remove organic sulfur from the coal matrix. 

Pre-combustion. C02 is captured when producing hydrogen through any of the processes discussed above. 

The lower curve in Graph 4 is for a pre-combustion chamber Diesel (Engine A). The upper curve is for a turbulent cell Diesel (Engine B). The lowest fuel/air ratio always corresponds approximately to idle and a no-load condition. At idle, neither of these types of Diesels could produce enough carbon monoxide to even give a headache after half an hour of continuous exposure. 

In the carbon capture world there are two approaches to capturing the carbon dioxide 1. post-combustion and 2. pre-combustion.The post-combustion approach is to take the COz from the combustion process, purify it, and then inject it. In the pre-combustion approach, the carbon is removed from the fuel before combustion. These two approaches are discussed in the following sections. 

Bolland, O. Options for oxy-fuels pre-combustion decarbonisation cycles. Presentation for Alstom Cross Segment C02 Mitigation Group. October II, 2002. Available at http //folk.ntnu.no/ obolland/pdf/Alstom Power Oct 2002 Bolland.pdf. 

Toshiba, in collaboration with Tokyo Electric Power Company, has developed a hybrid catalytic combustion. Here only a part of the fuel is converted heterogeneously on the catalyst. The system consists of a pre-combustion mixing zone, a low-temperature catalyst zone, and a gas-phase combustion zone. The fuel-air mixture is controlled to maintain the temperature of the catalyst below 800 C, because the catalyst is not stable above the temperature. More fuel is added downstream to attain the final combustion temperature. The function of the catalyst is to be a source of additional "pre-heat" to support the lean, homogeneous down-stream combustion. 

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