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The following information is excerpted from relevant articles by Mr. Zhang Ronglin, an expert in gasification from China Tianchen Chemical Engineering Company. (1) Differences in power consumption of the coal grinding system: Based on empirical data, dry coal grinding requires approximately 30 kW·H of electricity per ton of coal. For wet coal powder, only 20 kW·h of electricity is required per ton of coal; in other words, producing water coal slurry allows for a savings of 10 kW·h in electricity consumption for grinding per ton of raw coal compared to producing dry coal powder. Considering a coal grinding system that processes 2,000 tons of raw coal per day, 66×105 kW·h of electricity can be saved annually. At an electricity price of 0.45 yuan/kW·h, this results in annual savings of around 3 million yuan in electricity costs. (2) Differences in coal consumption in the raw coal drying system: Assuming a moisture content of 10% in the raw coal, approximately 10 kg of raw coal is needed to dry each ton of it. With 2000 tons of raw coal processed per day, the annual coal consumption for the drying system is around 6600 tons. At a cost of 450 yuan per ton, the annual expense for coal drying amounts to about 3 million yuan. (3) Differences in power consumption of the coal conveying system: For dry powder feeding, assuming a coal conveying system with a capacity of 1000 t/d, the volume flow rate is 8000 m3/h. If 2000 t of raw coal are processed per day, the consumption of high-pressure nitrogen (5.2 MPa) in the coal conveying system is 16000 m3/h, while the power consumption is 3200 kW. At an electricity price of 0.45 yuan/kW·h, the annual electricity cost amounts to approximately 11.4 million yuan. The consumption of low-pressure nitrogen (0.6 MPa) is 9,000 m3/h, with electrical power consumption of 733 kW. At a electricity price of 0.45 yuan/kW·h, the annual electricity cost is approximately 2.6 million yuan. Adding these two amounts together, the power consumption per hour is 3933 kW·h, resulting in annual electricity costs of around 14 million yuan. For the water-coal slurry system, with a daily processing capacity of 2000 tons of raw coal and an electricity consumption of 550 kW, and at an electricity price of 0.45 yuan/kW·h, the annual electricity cost is approximately 1.96 million yuan. The coal conveying system incurs an additional electricity cost of 12.04 million yuan for dry coal powder compared to slurry coal. (4) Differences in investment for coal preparation and transportation systems: Based on a daily processing capacity of 2,000 tons of raw coal, the investment in dry coal powder preparation and transportation systems is about 50 million yuan higher than that in slurry preparation and slurry transportation systems. Based on the summary of points (1) to (4) above, in terms of raw material preparation, assuming a daily processing capacity of 2,000 tons of coal as raw material, the dry coal powder feeding system requires an additional investment of 50 million yuan compared to the slurry coal feeding system. Assuming that these fixed costs can be recovered over a period of 5 years, there is an additional cost of 10 million yuan per year; this translates to an increase in fixed costs of approximately 22.73 yuan per ton of ammonia produced ； The annual operating cost increases by 18.04 million yuan, which translates to an additional operating cost of about 41 yuan per ton of ammonia. The combined cost per ton of ammonia is 63.73 yuan higher, resulting in an additional expense of around 28.04 million yuan per year. Therefore, coal water slurry feeding is superior to dry coal powder feeding; it not only requires less investment and results in lower production costs, but also features a simpler coal preparation system with fewer devices, facilitating production control while ensuring safe and reliable operation. This post was last edited by Coal Chemical Engineering Student on 2007-12-4 12:01.]