Experimental Procedure and Materials

The tests of hydrogen-rich gas production through steam gasification of coal were conducted in the laboratory-scale fixed bed reactor (Smolinski, 2007). The installation (see Fig. 17.1) consists of gases inlets (valves, flow regulators) (1), a water pump with a steam generator (2,3), a fixed bed reactor with a resistance furnace (4,5), a water trap (9), a flowmeter (10), and a gas chromatograph - GC(12). The fixed bed reactor is located inside the resistance furnace (see Fig. 17.2). The furnace operation is controlled by a computer (11) and the temperature and the pressure inside the reactor are controlled by a thermocouple (6) and a manometer (7), respectively.

Laboratory Scale Fixed Bed Reactor

Fig. 17.1 The laboratory-scale fixed bed reactor installation for coal gasification tests: 1 -gases inlets (valves, flow regulators), 2 - steam generator, 3 - pump, 4 - resistance furnace, 5 - fixed bed reactor, 6 - thermocouple, 7 - manometer, 8 - pressure regulator, 9 - water trap, 10 - flowmeter, 11 - furnace temperature control, 12 - gas chromatograph.

Fig. 17.1 The laboratory-scale fixed bed reactor installation for coal gasification tests: 1 -gases inlets (valves, flow regulators), 2 - steam generator, 3 - pump, 4 - resistance furnace, 5 - fixed bed reactor, 6 - thermocouple, 7 - manometer, 8 - pressure regulator, 9 - water trap, 10 - flowmeter, 11 - furnace temperature control, 12 - gas chromatograph.

The tests of steam gasification of coal were conducted in three series (see Fig. 17.3). In the first one (see Fig. 17.3a) the 3 g of hard coal, with grain diameter below 0.2 mm, was put between the quartz wool and placed at the bottom of the reactor. The quartz wool was used in order to ensure a better temperature distribution and to provide a protection against an entrainment of coal and additives grains by the gaseous media passing through the reactor. In the second and third series of experiments 10 g of Fe2O3 and 50 g of CaO were put in layers on a coal sample (see Fig. 17.3b) or mixed with a coal sample (see Fig. 17.3c), respectively.

Then the reactor was heated in an inert gas atmosphere to the set temperatures of 923 K, 973 K, 1023 K, 1073 K, 1123 K, and 1173 K. After the temperature had stabilized, steam was injected upward to the gasifier with a flow rate of 5.33- 10-2 ml/s. The gaseous products of the process passed through a water-cooled tar trap, where the condensed liquid products were retained. The amount of cool, dry, and clean gaseous product was measured with a mass-flowmeter. The composition of the outlet gas mixture was analyzed every 192 s with a gas chromatograph Agilent 3000A.

Hydrogenation Fixed Bed Reactor

Fig. 17.2 The fixed bed reactor with the resistance furnace.

Based on the results of gaseous products mixture flow rates and percentage compositions, the amounts of the main components of the synthesis gas produced (H2, CO, CO2, and CH4) were computed for each of the nineteen, 192 s long time intervals, in 1 h test duration as follows:

where Qc denotes the flow rate of the particular component of the gaseous products mixture (H2, CO2, CO, or CH4), Cci denotes the concentration of the given component in the gaseous products mixture measured with GC, and Q; denotes the flow rate of the gaseous products mixture recorded at the moment of gas sampling by the GC in the i-th time interval. The time interval length resulted from the chromatographic method settings. The volumes of components generated in the time intervals were also computed as follows:

where Vci denotes the volume of the particular component (H2, CO2, CO, or CH4) of the gaseous products mixture generated in the i-th time interval and ti denotes the time interval length.

The coal samples used in the experiments were provided by the Piast coal mine. They were collected from the coal seams planned to be exploited in 5-10 years when a large-scale coal gasification plant is expected to be operated in Poland. The characteristic of the tested coal is presented in Table 17.2.

Experimental Materials

Inert gas + Steam

Inert gas + Steam

Inert gas + Steam

Fig. 17.3 The samples in the series of experiments: (a) sample of coal, (b) coal sample with Fe2O3 and CaO layered, and (c) coal sample mixed with Fe2O3 and CaO.

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