Renovation of a plant with an annual production capacity of 300,000 tons of synthetic ammonia
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Our plant uses a fixed-bed batch atmospheric gasification furnace, and we are looking to modify the feedstock route. We have considered many technologies from both domestic and international sources; we would appreciate some guidance
The poster needs to provide information on the coal quality and region; only by taking these factors into account can a reasonable technical solution be proposed
At present, there are not many units with a capacity of 300,000 tons using fixed-bed gasification under normal pressure. If switching to coal as the feedstock, it is recommended to use the wet-flow bed gasification technology; however, this requires a longer time for installation, around two years, and it is necessary to select the right type of coal. Additionally, the shift system must be modified as well. (The CO content in the semi-water gas produced by fixed-bed gasification is around 30%, while it is around 45% in wet-flow bed gasification.) If copper washing is used for subsequent purification, it is advisable to opt for low-temperature methanol washing, and an air separation unit also needs to be installed as part of the infrastructure. If it is changed to a fluidized bed, the pressure level cannot be increased, so it doesn’t make much sense. Currently, many manufacturers in China are replacing the original oil or gas burners with coal burners. It should be noted that the cost of converting to a gas flow bed is higher than that of a fluidized bed, and moreover, the plant has to be shut down during the modification of the subsequent systems.
Coal quality analysis: Moisture 7.70%, Ash 3.82%, Volatile matter 34.50%, Fixed carbon 54.00%, Sulfur 0.10%, Ash fusion point 1250, Calorific value 26.24
It is recommended to use a water-coal slurry gasifier. The operation of Shandong Gun Mining Group has now exceeded 160 days.
Based on the coal quality, it is recommended to use water-coal slurry
The analysis data you provided is inaccurate; it’s not clear whether the moisture content refers to internal moisture or moisture on a basis weight basis. The ash content is very low, while the volatile matter and fixed carbon levels are high. To determine whether this coal is suitable for use in slurry form, a slurry performance analysis is necessary. Additionally, it’s not clear whether the ash fusion point is T3 or T1
Water-coal slurry? I’ve heard that it generates a large amount of wastewater; options that are not environmentally friendly will not be considered at all.
In both actual water-coal slurry gasification and multi-component slurry gasification, the amount of wastewater generated is not large. For a plant producing 300,000 tons of ammonia per year, the circulation volume is around 240 tons per year, while the amount of wastewater discharged is about 30 tons per hour; this is mainly to maintain the balance of soluble salts in the water
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Why change it? In my opinion, the current atmospheric-pressure fixed-bed process has many advantages over other fluidized-bed and pneumatic-bed processes. It features low investment costs, low coal consumption, simple water treatment; moreover, it addresses environmental issues related to flue gas recovery and treatment. If another method is used, corresponding modifications to the subsequent purification systems will be necessary, which will incur additional expenses. Just burn your fixed-bed instead