Catalytic burners

Catalytic burner C Adsorb the contaminant 1. Activated carbon... 

In a catalytic burner, the combustion is ignited and stabilized under ultra-lean conditions, which results in adiabatic temperatures close to those allowed for delivering the hot compressed gas to the turbine. Hence the need for by-pass air is minimized and the formation of thermal NOj, is almost prevented due to the absence of a hot combustion zone. Reduction of N emission has been reported to be even larger than expected from the lower combustion temperature if a significant fraction of the fuel is oxidized on the catalyst surface [3]. This effect has been attributed either to the reduction in the formation of prompt NO in view of the... 

Two configurations of the RCL burn technology have been designed a catalytic pilot burner, which replaces the existing diffusion flame or partially premixed pilot of the DLN combustor [26], and a full catalytic burner [25]. 

In the full catalytic burner, all the fuel is processed within an RCL bum module which replaces a conventional premixer-swirler arrangement in the DLN combustor. 

This section will provide information about micro structured reformer reactors, gas purification devices and catalytic burners, the last also in combination with an evaporator, for fuel processors. However, the specific problems related to the peripheral equipment will not be discussed in depth. 

For reformate flow rates up to 400 Ndm3 min-1, the CO output was determined as < 12 ppm for simulated methanol. The reactors were operated at full load (20 kW equivalent power output) for -100 h without deactivation. In connection with the 20 kW methanol reformer, the CO output of the two final reactors was < 10 ppm for more than 2 h at a feed concentration of 1.6% carbon monoxide. Because the reformer was realized as a combination of steam reformer and catalytic burner in the plate and fin design as well, this may be regarded as an impressive demonstration of the capabilities of the integrated heat exchanger design for fuel processors in the kilowatt range. 

R 20] The fuel processing system consists of a fuel evaporator, a reformer, a reactor for the preferential oxidation of carbon monoxide and a catalytic burner (Figure 4.48) [95],... 

Further research was performed on alkaline fuel-cell concepts (e.g. characterisation of gas diffusion electrodes) as well as on catalytic burners (reaction kinetics of H2/air mixtures). Experimental investigation of dymanic combustion phenomena was performed. Practical tests were carried out on internal combustion engines, including compression ignition engines (Altman el al., 1997 Schucan, 2000)... 

Similar techniques have been used by different researchers for the manufacture of catalytically active porous barriers for use as catalytic filters [125-127] (see Chapter 15 of the present book) and as catalytic burners [128,129]. 

Fast reactions, in general, are conducive to obtain a large output from a relatively small volume of chemical processing equipment. For example, the ammonia oxidation reaction, which is the first stage of production of nitric acid from ammonia, is essentially complete in 3 x 10 " seconds at 750°C. This is sufficiently rapid so that the catalytic burner required to do this occupies only about the volume of a file cabinet drawer for the production of some 250 tonnes of nitric acid daily. Except for the cost of the catalyst inventory (which is platinum), the fabrication cost of the ammonia burner itself is relatively low. Follow-up reactions for the process are much slower than this so that the volume of equipment required to contain these parts of the process are much larger and more costly (Chap. 11). 

Advances in chemical reaction engineering and catalytic materials have allowed catalytic combustion for thermal energy generation to be commercialized in consumer and industrial applications. The development of catalysts coated on one side of a metal substrate, coupled with the use of diffusion barriers, has allowed controlling the combustion temperature to suit diverse applications. Catalytic materials have been developed to remain active for thousands of hours under conditions deemed too severe just a few years ago. We may expect that the need for clean distributed power increases the demand for gas turbines fitted with catalytic combustors and promotes the development of catalytic burners to be used in fuel processors for fuel cell power systems. 

Combustion or burning is one of the oldest chemical processes known to humanity. During the last 30 years, two powerful pressures have combined and forced us to pay more and more attention to this grand old process. The first of these was the increased awareness of the problems caused by air pollution. This forced us to look up and develop combustion techniques which reduce pollutant emissions from anything we bum. The second pressure was the energy crisis fi om 1973 onwards, compelling us to increase continuously the combustion efficiency of any fuel we burn. These two pressures led to the development of catalytic combustion. Catalytic burners have two main objectives ... 

Reformate Loop PrOx unit Air control solenoid Catalytic burner Condenser N/A... 

Obtained Precision Combustion, Inc. dual-fuel catalytic burner. 

Under normal operating conditions, in which the combustor is sufficiently warm and operated under fuel rich conditions, virtually no NOx is formed, although the formation of ammonia is possible. Most hydrocarbons are converted to carbon dioxide (or methane if the reaction is incomplete) however, trace levels of hydrocarbons can pass through the fuel processor and fuel cell. The shift reactors and the preferential oxidation (PrOx) reactor reduce CO in the product gas, with further reduction in the fuel cell. Thus, of the criteria pollutants (NOx, CO, and non-methane hydrocarbons [NMHC]), NOx CO levels are generally well below the most aggressive standards. NMOG concentrations, however, can exceed emission goals if these are not efficiently eliminated in the catalytic burner. 

P.W. Pillsburry, Update of full scale catalytic burner testing for combustion turbines, ASME 84GT54, 1984. 

A serious candidate for transportation application is also the direct methanol fuel cell (DMFC) which has been realized already on a laboratory scale. A catalytic burner is requited to evaporate the methanol/water mixture and to bum the exhaust gas at the anode [43]. Considering the complete energy chain, a PEFC is by 50 % more efficient than a diesel engine which consumes 4 1 per 100 km this is also valid for a natural gas driven engine [37]. Fig. 7-6 presents the processing schematics of both IMFC and DMFC. The DMFC offers a much simpler system than the PEFC. The DMFC is currently at an early development stage. It is perceived to offer improved solutions to the need for a small-scale power supply. A program for the construction of a 30 kW stack has recently started [29]. 

A 10 kW(th) catalytic burner to be fueled with either natural gas or its mixture with up to 50 % hydrogen has been developed at the Research Center Julich. The fuel gas is routed through a porous ceramic body, whose surfaces are covered with Pd and R as catalysts. NOX emissions were measured to be less than 20 mg/kWh. 

Catalytic combustor with heat conductor that transfer heat from downstream part to upstream end The combustor consists of pre-mixed burners and catalytic burners which allow very lean operation... 

These calculations show that the heat transfer characteristics of the reactor will sigitificantly change as the catalyst deactivates. This will effect the design and control of the heating mechanism (i.e. catalytic burner) that provides the heat to the reactor. 

Figure 9-6 describes a fuel cell system including all parts of a process the fuel cell catalysis itself, gas processing (e.g., reforming of hydrocarbons like methane or methanol) and the catalytic burner for the off-gases [3]. 

Traces of solvents in gas vented to atmosphere from closed-cycle dryers are usually removed by incineration in gas or catalytic burners. This method may also be used for... 

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