Ignition of the oven with four nozzles

The four-nozzle water-coal slurry system has a furnace-heating burner, which is installed at the vault; there is a brick similar to a plug on the vault, and it can be removed. But some companies no longer use it; it can still be used for indirect heating of the furnace.

It’s just necessary to find a way to raise the temperature to over 8–900°C. No matter how many burners are used, or what type of burners they are. In essence, it involves gradually raising the temperature of the refractory bricks while preventing cracking due to thermal stress, ensuring that the temperature inside the furnace meets the requirements for ignition.

It’s better to follow the guidelines step by step; you can’t just go ahead recklessly

The four-nozzle drying mode is essentially the same as the single-nozzle mode; the original design called for drying from the top. Later, some manufacturers changed this to drying from the side to facilitate operation. Drying is still possible in this way, but it is necessary to strictly control the drying temperature to ensure that the slag on the furnace walls does not melt, thereby preventing blockages at the slag outlets.

The four burners must be replaced simultaneously to prevent uneven combustion and damage to the refractory bricks on the opposite side. I always feel that the design isn’t very reasonable; it’s probably just done to avoid patents

Avoiding patents is indeed one aspect; the flow field inside a four-nozzle furnace is complex, and it’s not easy to make adjustments when there are issues with the furnace wall temperature. However, the four-nozzle water circuit is more stable than the single-nozzle one, and it is easier to operate.

I think the operation must be complicated; adjusting the load, as well as the flow rate, requires coordinating all four burners simultaneously, with at least the two burners on the opposite side needing to be adjusted in unison. Additionally, it is possible that uneven wear of the four burners leads to misfiring and damage to the refractory bricks. I wonder if that’s the case?

It’s not merely a matter of avoiding patents; in actual operation, the utilization rate of coal, specific oxygen consumption, and specific coal consumption are all better than those of single-nozzle gasification furnaces, with the effective gas composition remaining above 82%. Moreover, the four-nozzle gasification furnace is suitable for large-scale applications; when operating with a single furnace, if one pair of burners fails, the other pair can operate independently. We have operated it for 23 hours without any impact on the gasification furnace. By taking advantage of this time difference, another gasification furnace can be brought online, thereby avoiding a shutdown of the entire system.

For a gasification furnace of 65 kilograms and 1,500 tons capacity, how much investment is required for the entire gasification facility? It’s estimated to be about one-third higher than that of GE

This post was last edited by gust111 on 2015-11-6 at 10:37. Personally, I find this furnace to be average. What is said about oxygen consumption versus coal consumption when going upstairs actually shows that there isn’t much difference compared to GE boilers. I heard from Huali’s promotions that it was only around 1%. But there seems to be a lack of empirical evidence: the fluctuations in coal quality used in the gasification furnaces exceed 1% by a large margin, and it’s unclear what basis such a comparison is based on. Similarly, the effective gas volume is related not only to the specific coal used and the oxygen-to-coal ratio, but also to the slurry concentration. Generally, the slurry concentration varies depending on the slurry viscosity, ranging from about 60% to 66.7%, with some fluctuations as well. Therefore, 82% of effective gas components should also be specific, rather than something that can be achieved under almost any operating condition. As for using the time difference between two burners to operate another gasifier, it’s not even worth mentioning: both GE furnaces and those with four nozzles require a backup furnace, which is meant to be used when a burner needs to be replaced or repaired; so why wait until both burners are affected before making the switch? However, the investment for four-nozzle systems is higher than that for GE furnaces; accordingly, having spare furnaces does not offer any advantage in terms of cost control. The key so-called advantages: 1) It’s a domestic brand. Satisfy the self-esteem of national technical personnel. It may not sound nice to say, but it’s the truth: if the roles were reversed, GE furnaces developed in China would have long since failed. 2) The technology transfer fee is low, but considering the overall investment, the advantage of the transfer fee is not significant. 3) The so-called advantage of larger size. This is a bit of an issue: although the investment in the four-coal and four-oxygen lines is higher and coordinated control poses more difficulties, the costs associated with maintenance and replacement are also greater. But the corresponding operational flexibility will be greater. After all, increasing the production capacity by 10% with one nozzle is much easier when distributed across four nozzles rather than having it borne by just one nozzle; it is indeed appropriate to promote this aspect more.