?China: ion desulfurizers - innovations and applications?? 

China: Ionic Desulfurizers - Innovations and Applications

When people talk about desulfurization in China, many people immediately think of traditional lime milk scrubbers. But in the last five to seven years, the theme has become increasingly louder:ionic desulfurizers. I won’t say that this is some kind of completely new magic - the principles are known, but it is in Chinese practice that their fine-tuning and adaptation to local, often very harsh, conditions is a separate story, full of both breakthroughs and dead ends.

Where does this interest in ion technologies come from?

It all comes down to environmental standards. China is no longer a country where you can endlessly build giant absorption towers. We need compactness, less water, less waste in the form of gypsum, which then still needs to be disposed of somewhere. Ionic methods, in theory, promise exactly this: high efficiency of SO2 removal, and selectively, and the possibility of sorbent regeneration. Sounds perfect, right? But in practice... In practice it often turns out that the declared “regeneration” on paper turns into a headache on site due to the difficulty of controlling the ionic composition of the solution.

I remember one of the first major projects at a thermal power plant in Shandong province. The installation was installed based on ion technology. Everything worked brilliantly in the laboratory, the efficiency was above 99%. But in real flue gases, with their dust, fluctuations in temperature and composition, problems began. The ionic solution quickly “tired” — was contaminated with chlorides and fluorides that came with coal. The regeneration circuit could not cope, so we had to urgently modify the pre-cleaning system and introduce additional stages of cleaning the solution itself. It was an expensive lesson.

It was after such cases that it became clear that succession desulfurizer— it’s not so much the reactor itself, but competent gas preparation and a smart system for monitoring and controlling the chemistry of the process. Without this, it quickly degrades to the level of an ordinary wet scrubber, but with a more capricious “filling”.

Key players and their approach: an inside look

There are several notable teams on the market right now. Some rely on ready-made, standardized modules - like “set it and forget it?”. Others, and in my opinion there are more of them, work as design institutes, adjusting the solution to a specific firebox, specific coal. Here, for example,Chengdu Yizhi Technology Co.(their website ishttps://www.yzkjhx.ru). This is exactly the case. They grew out of the chemical technology company Huaxi, and you can feel it. Their approach is not to sell hardware, but to sell a technological process.

Yizhi is a design institute established by Chengdu Huaxi Chemical Technology Co., Ltd. back in 2013. The authorized capital of 120 million yuan is a serious figure, this indicates intentions to play for the future, and not for quick projects. In their desulfurization solutions, I often see an emphasis on the chemical side: detailed customization of the composition of the ionic solution, in-depth analysis of ash and impurities in the customer’s fuel. They do not hesitate to combine methods: in some places the ionic process is the core, and in others they use it as a finishing step after traditional purification.

What is valuable is that they publish not only successes, but also analyzes of complex cases. On the same site you can find materials on working with high-sulfur coals or gases from waste incineration plants, where in addition to SO2 there are also a bunch of aggressive impurities. This gives the impression that you can speak the same technical language with them, and not just receive a commercial proposal.

Where does it really work, and where is it overkill?

Now the main testing ground for ion technologies in China is not so much giant coal blocks of 1000 MW, but medium and small sources: industrial boilers, boiler houses, chemical plants. Where there is no room for huge absorbers, but there are strict emission limits. Or where the resulting by-product is valuable - say, concentrated sulfuric acid or sulfur.

A successful example that I have seen personally is a cement plant in Sichuan. They put it thereion desulfurizerto the firing line. The advantage was that the temperature of the gases was already relatively stable, and dust collection was very effective. The installation was compact, the regeneration of the solution worked stably, and the plant was able to use the resulting sodium sulfite in its own technological cycle. The economic effect was positive not only due to fines, but also due to savings on the purchase of reagents for other processes.

But at a coal-fired thermal power plant with highly varying loads and fuel composition, such systems, in my opinion, still require very qualified maintenance. Not every personnel is ready to read data from ion-selective electrodes and promptly adjust the mode. Often the installation does not work at the optimal level, but at the “safe” level. mode, with excessive consumption of reagents, which negates its economic advantages.

Pitfalls and “non-obvious” ones details

Few people talk about this in brochures, but one of the main enemies of ionic systems is corrosion. It would seem that the solution is alkaline, but at certain potentials and the presence of activator ions (the same chlorides), it becomes very aggressive towards ordinary stainless steel. It is necessary to use more expensive alloys or special coatings in key components. This immediately impacts capital costs.

Another point is the disposal of waste solution. Yes, it regenerates, but not 100%. Over time, ballast salts and heavy metals accumulate in it. And this "tail" need to be neutralized or buried somehow. In some projects this became an unexpected cost item that was not taken into account at the start. Therefore, now competent engineers immediately include a crystallization or evaporation module in the circuit for processing this waste.

And the last thing is dependence on the reagent supplier. A high-quality, pure base reagent (sulfite or carbonate) is critically important. If there are impurities in it, they will quickly poison the entire cycle. This creates certain risks for the customer and ties him to reliable chemical companies. Not everyone is ready for this.

What's the result? A look into the near future

Ionic technologies in desulfurization are not a “silver bullet” that will replace everything. This is a powerful but specific tool in the environmental engineer's arsenal. Their niche will grow, especially as regulations become more stringent and the cost of water and land for dumps rises. But success will only be where there is a clear understanding of the entire chain: from the composition of the fuel to the final disposal of all flows.

Companies likeChengdu Yizhi Technology Co., with their deep chemical roots and project-based approach, are in a good position. Their strength lies in the ability to customize, in the ability not just to install equipment, but to adjust the technological mode to the “character” of the project. specific plant. This is exactly what is needed for such capricious processes.

Personally, I believe that the next revolution will be related to systems integrationion desulfurizationwith digital twins and predictive analytics. When sensors in real time will not just show concentrations, but with the help of models will predict the moment when it is necessary to adjust the regeneration mode or add an additive. Without this, it will be difficult to reach mass application in the most complex - energy - industry. But the movement is definitely going in this direction. Let's see what the next five years show.