【Weekly Topic】Discussion on the issue of wastewater pulping
Thread Content
Wastewater pulping is undoubtedly of great significance in reducing the pressure on wastewater treatment. For water-coal slurry gasification and water-coal slurry boilers, which wastewater types are involved in slurry preparation, and what problems arise during operation? There are big prizes for participation!
In water-coal slurry gasification, by design, the water used for preparing the slurry is raw water; in my opinion this is unnecessary, as it would be entirely possible to use the wastewater generated during gasification itself for this purpose. The wastewater from sedimentation tanks used to collect waste water from gutters, the low-pressure ash water pumped by low-pressure ash pumps, and the water filtered by fine slag filters can all be used as a substitute for raw water in pulp production, and all of them enable continuous water supply. Additionally, the wastewater from the slurry preparation tanks can also be used as pulp-making water; however, this type of wastewater can only provide intermittent water supply, it has a higher solid content, which increases the likelihood of pipe wear and blockages. The same is true for the wastewater from sedimentation tanks. In water-coal slurry gasification, it is best not to use the same type of wastewater for making the slurry over a long period of time, as all types of wastewater contain a certain amount of solids. The slurry preparation tanks, pumps, and pipelines are not designed with erosion resistance in mind; therefore, the wall thicknesses of these pipelines do not provide any compensation against erosion. Additionally, sedimentation at the bottom of the slurry preparation tanks has a significant impact on the performance of the slurry pumps. If it is not possible to clean the sediment at the bottom of the pulping tank online, then the pulping water can be periodically switched to raw water for a period of time, and backflow drainage at the bottom of the pulping tank can be activated.
Not all kinds of wastewater can be used to make pulp. If the wastewater has a high salt content, it can cause salt corrosion. It’s not feasible either if the ammonia nitrogen content in the wastewater is too high, or if the operating conditions for pulp production are too harsh.
In wastewater pulping, high hardness can cause scaling in the pipelines
Considering the quality of the gasified graywater, care should be taken when using water that is salty; in some cases, it may be necessary to replace the water. Anyway, each option has its advantages and disadvantages
Wastewater pulping is problematic mainly because water with high alkalinity and high hardness tends to form scale, and it also easily clogs pipes, resulting in insufficient amounts of water available for pulping.
When using gasified various types of wastewater to produce coal slurry, there is another issue that cannot be ignored: the ions and substances present in these wastewaters can interfere with the effectiveness of the additives used in the coal slurry. This situation is possible
The Shanghai Coking Plant uses wastewater generated by the coking plant, which is difficult to treat, for pulp production. Please ask someone who is familiar with this matter to explain it in detail.
Urea waste liquid, sludge tank waste liquid, and condensed liquid from purification processes can all be used
Wastewater pulping can reduce the pressure on wastewater treatment! ! However, mixing various types of wastewater can easily lead to severe scaling on the impellers and pipelines ； It is recommended to add it directly to the rod mill! !