Fuel operating modes

The H-Coal process could operate in one of two modes, depending on the desired product slate. In the "syn-cmde" mode, a fluid-bed coking unit was employed to maximize recovery of distillate from the Hquefaction product (Fig. 7a). When operated in the fuel oil mode (Fig. 7b), no coker was used and the primary product was a coal-derived low sulfur fuel oil. Total hydrogen demand on the process was also reduced in the latter mode of operation. 

Solvent-Refined Coal (SRC) This processing concept was initiated by the Pittsburgh Midway Coal Mining Co. in the early 1960s. The SRC-I process operating mode is designed to produce a solid fuel for utility applications. Typical operating conditions and product yields for SRC-I are shown in Table 27-14. 

Reliability of a plant depends on many parameters, sueh as the type of fuel, the preventive maintenanee programs, the operating mode, the eontrol systems, and the firing temperatures. 

The starting system can be manual, semiautomatic, or automatic, but in all cases should provide controlled acceleration to minimum governor speed and then, although not called for in the standards, to full speed. Units that do not have controlled acceleration to full speed have burned out first- and second-stage nozzles when combustion occurred in those areas instead of in the combustor. Purging the system of the fuel after a failed start is mandatory, even in the manual operation mode. Sufficient time for the purging of the system should be provided so that the volume of the entire exhaust system has been displaced at least five times. 

Exhaust system The engine operating mode controls the tailpipe emissions of hydrocarbons (HC) and carbon monoxide (CO). Over 80% of HC and CO emissions are generated during cold-start and warm-up due to incomplete combustion. Fuel vaporization and fuel/ air mixing are important factors in achieving thorough combustion of the hydrocarbons. 

The burner is operated on natural gas and air in a fuel-rich mode. Fluorine reacts with excess fuel to form HF and CF4. All of the air that goes through the containment cell (hood) is scrubbed with caustic before being released. (We considered destroying the fluorine by reaction with caustic, but our calculations suggested that this reaction was too slow.)... 

Fuel cells. In the fuel-cell mode of operation, reactants are fed into the cell (or battery) continuously while reaction products are removed continuously. Hence, fuel cells (the more appropriate term, e/ battery, is not commonly used) can deliver current continuously for a considerable length of time that depends primarily on external reactant storage. 

New applications and novel reactor configurations or operational modes for three-phase systems are continually being reported. These include the operation of a three-phase fluidized bed in a circulatory mode (Liang et al., 1995), similar to the commonly applied gas-solid circulating fluidized bed the application of a three-phase fluidized bed electrode that can be used as a fuel cell (Tanaka et al., 1990) magnetically stabilized three-phase fluidized beds centrifugal three-phase reactors and airlift reactors. 

PEFC) stacks, components and entire systems, in off-grid, and grid-connected configurations, with a capacity of up to 100 kW electrical power output. The facility consists of an automated and computerised fuel cell test station, gas analysers, a multi-axial vibration system which is housed in a walk-in environmental chamber (for controlling temperatures, humidity, shocks and vibrations) and ancillary equipment. The data obtained are complementary to and validate fuel cell simulations and models with reference to operation modes, components and system characteristics 1 ... 

Sensor Cell Operating Mode. The simplest method of sensor operation is as a galvanic cell, whereby the sensor acts as a fuel cell and generates a current proportional to the gas concentration to be detected (1 ). However, when detecting certain species in air, it is difficult to obtain a counter-reference electrode in an acid system that will maintain the sensing electrode at a predetermined potential of approximately 1.0 V, to minimize interference. Counter-reference electrodes such as Pt/air (Op) or noble metal/ noble metal oxide structures have rest potentials in the 1.0 to... 

On the other hand, when solar electricity is insufficient and needs to be supplemented, the RFC is switched into the fuel cell mode of operation where the oxidation of one mol of hydrogen will generate 237.1 kj/mol of electrical energy plus 48.7 kj/mol of thermal energy. This waste heat can also be used for heating buildings or for preheating boiler feedwater. 

The one area where oxyhydrogen combustion is desirable is where high flame temperatures are required, such as in welding. In all other applications the most efficient system is to use fuel cells and the least expensive configuration is to use my new reversible fuel cell design (Section 1.3.5.4), which can operate both in the electrolyzer and the fuel cell modes and uses free solar energy to drive the electrolyzer. 

The plan calls for processing Illinois No. 6 or comparable bituminous coal in both the synthetic crude and fuel oil modes and then a subbituminous coal in the syncrude mode only. Each run is expected to be about three months in length to allow ample time for lineout and collection of engineering and operating data. Yields in the syncrude mode will show a high percentage of naphtha and light gas oil while in the fuel oil mode there will be over 80 percent of 400 plus distillate and residuum. 

A variation on IGCC operation is to combine power generation with chemicals or fuels production, the so-called co-production option. In this operating mode, part of the syngas produced by the gasifier is used for power production and part is sent to a Fischer-Tropsch,25 methanol, or similar facility for fuels/... 

Proton exchange membranes, whether operating in electrolysis mode or fuel cell mode, have the property of higher efficiency at lower current density. There is a 1 1 relationship in electrolysis between the rate of hydrogen production and current applied to the system. 

Ammonia, produced due to the coexistence of H2 and N2 at high temperatures in the presence of catalyst, was estimated to be in the concentration range of 30 to 90 ppm [37, 38], Uribe et al. [39] examined the effects of ammonia trace on PEM fuel cell anode performance and reported that a trace in the order of tens of parts per million could lead to considerable performance loss. They also used EIS in their work. By measuring the high-frequency resistance (HFR, mainly contributed by membrane resistance) with an operation mode of H2 + NH3/air (feeding the anode with hydrogen and ammonia), they obtained some information related to membrane conductivity, and found that conductivity reduction due to ammonia contamination is the major cause of fuel cell degradation. 

---