Intermittent gasification of oxygen-enriched air to produce semi-water gas

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Currently, domestic manufacturers have succeeded in using 45%–55% oxygen-enriched air in fixed-bed gas generation furnaces to produce synthetic ammonia feed gas. Oxygen-enriched continuous gasification production was achieved, doubling the gas generation capacity and significantly reducing the cost of ammonia synthesis. However, 1. Oxygen-enriched continuous gasification requires oxygen production equipment (deep cryogenic air separation, pressure swing adsorption, or membrane separation) with a large capacity, resulting in very high initial investment costs ； 2. The synthesized ammonia feed gas produced contains too high a level of CO2, which increases the workload for removing CO2 in subsequent processing stages and raises energy consumption in the compression section. 3. The existing gas generation, desulfurization, and decarburization units need to be shut down for modification. 4. A stable type of raw coal is required, as frequent changes in coal quality are not acceptable. If we can make use of the existing UGI-type gas generators and the conventional batch gas production method, by introducing oxygen-enriched air intermittently at appropriate times, we can enhance the intensity and duration of the carbon oxidation reaction, thereby increasing the average temperature of the carbon layer. This facilitates the decomposition of steam, while also reducing the blowing time and increasing the gas production time. In this way, we can achieve the energy-saving and productivity-enhancing effects of oxygen-enriched continuous gasification, while reducing initial investment. It also helps to avoid excessive CO2 content in the synthesized ammonia feed gas; moreover, no major modifications to the existing production equipment are necessary during the technical upgrades. By adopting “oxygen-enriched batch gasification,” the conditions for the decomposition of steam within the hot carbon layer are optimized, allowing for more efficient use of available carbon and steam and reducing unnecessary losses of these materials during the cyclic gas production process. Long-term production practice at a certain nitrogen fertilizer plant has shown that it is possible to significantly increase the output of raw gas for ammonia synthesis, save raw coal and energy consumption, and reduce emissions of CO2, sulfides, and gas production wastewater. Overall, the oxygen consumption is only about one-tenth of that in the oxygen-enriched continuous gas production process; a small air separation unit or PSA oxygen generator is sufficient, and no major modifications to the piping system are required. This approach enables the production of semi-water gas from low-quality coal, which holds great significance for improving China’s traditional coal-based gas production technology. A 2600 gas generator was used, with oxygen-enriched air added during the upward gas generation process. This post was last edited by ch3ohnh3 on 2008-12-3 21:41]