Fluidized pressurized melting combined system for ammonia synthesis

Abstract

A fluidized pressurized melting combined system for ammonia synthesis is disclosed. The system includes a circulating fluidized bed gasification furnace comprising a flue gas inlet in the middle portion and a flue gas exhaust port in the upper portion; at least two stages of cyclone separators, with each cyclone separator including a flue gas inlet and a fly ash outlet, the flue gas inlet being connected to a coal gas outlet, and the fly ash outlet being used for discharging fly ash after cyclone separation of coal gas; a pressurized melting furnace into which the fly ash in fed and which generates high-temperature high-pressure (0.5-1.5 MPa, 1300-1600 DEG C) flue gas after oxygen-rich combustion; a turbine into which the high-temperature high-pressure flue gas is fed and which outputs cooled depressurized flue gas after work to the flue gas inlet at the middle portion of the circulating fluidized bed gasification furnace. According to the system, the circulating fluidized bed coal gasification technology has low requirements on coal quality, and coal with high water and volatile component contents can be adopted for gasification.

Description

technical field [0001] The invention belongs to the field of coal chemical industry, and further relates to a combined fluidized pressurized melting ammonia synthesis system. Background technique [0002] Small and medium-sized nitrogen fertilizer enterprises mainly use fixed-bed batch gasification to produce semi-water gas. The fixed bed batch gasification method is highly dependent on raw materials. In order to ensure a good gasification effect, the gasification raw materials must meet the requirements of low moisture, low ash, low volatile matter and high fixed carbon. In the past, the raw materials were mainly anthracite and coke. The cost of raw materials is high. [0003] Fluidized bed coal gasification technology has good heat and mass transfer conditions in the furnace and high gasification intensity. The characteristic of using fluidized bed gasification technology to produce raw material gas for ammonia synthesis is that low-quality coal can be used, and the coal...

AI Technical Summary

Problems solved by technology

However, the flue gas temperature at the outlet of the melting furnace is generally around 1500°C, while the temperature at the upper part of the gasifier is generally 850-900°C, and the two parts of the flue gas are directly mixed to form reduction, lowering the system's efficiency

[0006] The main technical defects of the fluidized bed coal gasification technology to produce synthetic ammonia raw material gas are: (1) The gasification process is an endothermic reaction, and the temperature in the upper part of the gasifier decreases, which makes the gasification speed of the gasifier low and reduces the carbon conversion. (2) Due to the low gasification temperature, the carbon content in the gasification fine powder ash produced is about 30%-60%, which on the one hand causes the carbon conversion rate of the fuel to be low; on the other hand, the carbon content is 30%-60% gasification fine powder ash cannot be used by cement and construction industries. At the same time, gasification fine powder ash is also enriched in heavy metals, organic matter and other pollutants, which is likely to cause environmental pollution

Images