Switching steam-to-coal ratio control between dry powder furnaces and water-coal slurry furnaces?
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What is the typical value for adjusting the steam-to-coal ratio in dry powder furnaces and water-coal slurry furnaces? What ratio do people usually use?
There are processes with low water vapor ratios as well as those with high water vapor ratios, and the water vapor ratio can be adjusted using steam; the specific value depends on the conversion catalyst. For Lianxin, the low water vapor ratio is around 0.25
The control of the water-gas ratio is determined by both the sulfur content of the coal type and the catalyst used for the shift reaction, as sulfur-resistant shift catalysts require a certain level of sulfur content and water-gas ratio to meet their functional requirements.
The gasification process technology essentially determines the water vapor ratio; gasifiers using the waste boiler process and dry ash removal methods have a very low water vapor ratio, generally less than 0.8. The water vapor ratio in the quenching process is relatively high, generally exceeding 1.0. Of course, the water vapor ratio in coal gasification furnaces can be adjusted appropriately, but the range cannot be very large.
Is this water vapor ratio of 1.9 a bit high? Is such a high water vapor ratio necessary?
We have also encountered such a high water vapor ratio; the main issue is the level of sulfur content. Too low a sulfur content often leads to sulfidation and desulfidation of the catalyst, causing it to become inactive rapidly. The solution is to use a compressor to compress the concentrated hydrogen sulfide and send it to the inlet of the shift reactor, thereby controlling the sulfur content in the feed gas to that reactor.