It turns out that space furnace water-coal slurry is everywhere; are there no fixed-bed systems left?

There are still some old small nitrogen fertilizer plants, right? With the current focus on energy conservation and emission reduction, fixed-bed reactors are on the verge of being phased out

In fact, the overall energy consumption of the fixed-bed process is not high. We can achieve tons of ammonia per ton of coal. Have we fallen behind?

It is said that there are still around 3,000 fixed-bed units in operation, and many companies are performing fairly well.

To exist is to be reasonable. The advantages of a fixed-bed system are its low investment cost and short construction period. However, in terms of consumption, there is no such thing as an advantage; it comes down to tons of ammonia per ton of coal. First and foremost, these are raw materials such as white coal or coke, and at the very least, lump coal. Director Lao Bai from Shanxi even emphasized that the term refers to refined \"lump\" coal, which is used in the Lurgi furnaces at Tianji. However, UGI’s requirements aren’t that low either. In terms of unit price, it is not in the same category as the bituminous coal most commonly used in fluidized bed systems. Moreover, steam is needed, which means thermal coal ； The compressors used for atmospheric pressure gasification, purification, and synthesis are all energy-hungry devices. In older facilities, turbines were rarely used to drive these compressors; the original machines were small and of the reciprocating type, so turbines weren’t suitable for use with them. All of these can be converted into coal consumption. Therefore, from the perspective of large enterprises, it is impossible to build a fixed-bed reactor at atmospheric pressure, and the policies do not allow it either. A single facility might require 100 UGI units to achieve the performance of seven or eight high-pressure fluidized bed units; it would have no advantages in terms of space usage, operational efficiency, management, energy consumption, environmental protection, or safety. Moreover, it would need to include a whole range of additional components such as low-pressure desulfurization systems, compressor buildings, medium-pressure conversion units, and carbon removal systems, leading to the same problems once again. So aside from areas rich in white coal, where limited development is possible, there is definitely no prospect for growth in other places.

The process is chosen based on the raw materials used; in the anthracite-producing areas of Shanxi, fixed-bed reactors are still in use. These reactors have low energy consumption once they are operational, and environmental impact can also be controlled.

Now, there are indeed many so-called continuous oxygen production processes at normal pressure, and no relevant policies prohibit them.

The targets of tons of ammonia per ton of coal and per kilowatt-hour of electricity have indeed been achieved (and in this case, two tons of coal are used to produce one ton of ammonia, so basically no thermal coal is consumed in the process of ammonia synthesis); however, there is no advantage associated with scale effects. The coal consumption required to power large-scale installations, as well as the oxygen consumption, are also quite high. Different manufacturing processes have their own advantages, so it’s not right to dismiss such processes outright.

The main reason is that the fixed-bed system suffers from severe contamination, and wastewater treatment remains a persistent challenge. Currently, environmental approval processes for coal chemical projects are extremely strict; it’s almost impossible to implement fixed-bed technologies for new projects – water-coal slurry and pulverized coal are the only options available. Moreover, pulverized coal has an inherent advantage when using lower-quality coal.

Increasing the steam decomposition rate effectively reduces the amount of gas generation wastewater, thereby achieving a balance in wastewater levels. The fixed-bed process has been continuously improving.