China: food CO2 technologies? 

When you hear this combination - ?China? and ?food CO2? — the first thought is often about scale, about gigantic factories and tons of product. But behind this there is a much more interesting and less obvious story: the evolution of technologies that have gone from simple capture to complex, almost filigree purification. And there are nuances here that many miss when chasing cheapness.

Not just gas, but specification

The main misconception is that food CO2 is the same everywhere. Chinese standards GB 1886.228-2016 and GB 29203 are a serious document. But the problem is often not in the standard, but in its interpretation in a particular production. I have seen installations where everything is consistent on paper, but in practice the fluctuations in the total amount of hydrocarbons or hydrogen sulfide were on the verge of acceptable. Why? Because the raw materials - waste gases from the production of ammonia, ethyl alcohol or from natural sources - vary greatly. And the technological chain for each raw material must be its own.

For example, with ammonia lines it is simpler in terms of scale, but it has its own headache - possible traces of ammonia and difficulties with the adsorption of aromatic hydrocarbons. But with bioethanol plants - a fashionable trend now - they have their own set of impurities: higher alcohols, esters. The standard chain (compression, drying, distillation) may not cope; additional steps are needed, the same adsorption on modified zeolites or carbons. This makes the project more expensive, and not every customer is ready to invest in it, preferring to risk quality.

Worth mentioning hereChengdu Yizhi Technology Co.— their approach is often based on a deep analysis of raw materials. They don’t just sell the installation, but first study the raw gas. On their websiteyzkjhx.ruit is clear that they position themselves as an engineering institute, and not just a supplier of equipment. This is an important point. They were created by Huaxi Technology in 2013, and their registered capital of 120 million yuan shows serious intentions. In practice, this often means that they have their own R&D and can offer not a standard, but an adapted solution. Although, of course, they also have projects where corners were cut in pursuit of deadlines.

Key Knots: Where the Devil Lies

If we talk about the technological chain, then everyone knows about drying adsorbers and distillation columns. But the real battle for cleanliness takes place in less visible areas. Let's take preliminary purification of sulfur compounds. Many people use simple iron catalysts, but their resource, given the unstable composition of the raw material, can be catastrophically short. I came across a situation where the catalyst bed at a plant in Shandong had to be changed twice as often as planned because the raw material supplier (distillery) changed the fermentation technology. A solution was found by introducing an online H2S monitoring system in front of the catalyst, but this added complexity and cost.

Another critical point is oxygen removal. It would seem like a small thing. But if its content exceeds 30 ppm, this is already a risk for some applications, for example, in modified atmosphere packaging for sensitive products. Chinese manufacturers often use catalytic hydrogenation with a palladium catalyst. Effective, but expensive. And here there is a constant search for compromise. Some try to make do with deep distillation, but this is energy-consuming. I saw one installation in Fujian, where engineers tried to save on the catalyst by installing a cheaper analogue. As a result, the O2 content jumped, and the gas batch had to be downgraded to technical level, incurring losses.

And, of course, final filtration. After all the steps there is always a jar with an adsorber filter. Often with activated carbon. But coal and coal are different. Cheap, improperly activated carbon can produce dust or become a source of impurities itself. Not only its quality is important, but also the system for monitoring the dew point and oil at the outlet. Here, Chinese equipment suppliers have become much more attentive over the past 5-7 years.

Logistics and storage: invisible losses

Production is half the battle. Next are tanks, evaporators, pumps. The material of the inner surface of the tanks, the condition of the gaskets on the flanges - all this affects the final quality. China has switched mainly to 304L stainless steel for food tanks, which is a good practice. But I have also seen old tanks with epoxy coatings that micro-cracked over time. In such cases, the risk of gas contamination increases significantly.

Another practical point is filling and emptying tanks. Speed, pressure drops. Rapid filling can carry away droplets of moisture or oil particles from the compressor if there is a weak point somewhere in the line. Once we were dealing with a complaint from a brewery: traces of oil mist were found in the gas. The problem turned out not to be in the installation, but in the piston compressor at the discharge into the tank, whose seal had worn out. It was installed by locals to save money, and it was not designed for continuous operation with food gas.

Storing the liquid phase under pressure is always a balance between temperature and pressure. In the southern provinces of China, this is a special challenge in the summer. If the temperature in the tank rises above the critical temperature, the safety valve will trip, and you lose both product and create a risk. Therefore, modern installations are increasingly equipped with automatically controlled recirculation and cooling systems. But in many old factories this is done manually, which, of course, is a risk.

Market and trends: which way the wind blows

Demand for food-grade CO2 in China is growing not only from the food industry (soda, beer, packaging), but also from new sectors, such as growing plants in greenhouses. But greenhouses require gas with even stricter limits on ethylene and other phytotoxins. This is the next level of cleaning. Not all manufacturers are ready to invest there, as equipment is becoming more expensive.

An interesting trend is mini-installations. Not giant complexes at chemical giants, but relatively small modules at distilleries or biogas stations. Their advantage is locality and lower logistics costs. But the downside is that it is more difficult to maintain stable quality due to fluctuations in the volume and composition of raw materials. Companies likeChengdu Yizhi Technologythey are actively offering solutions for such decentralized sources. Their niche is designing for a specific, sometimes imperfect, raw material base.

Another driver is the environment. Capturing CO2 from industrial emissions is not only about producing a product, but also about carbon credits. This becomes a financial incentive for Chinese enterprises. But for gas from such a source to become food grade, the purification costs are an order of magnitude higher. So far, most of the captured CO2 is used for technical needs. But technology is advancing, and perhaps in a couple of years we will see breakthroughs in catalytic purification systems that will make the process cost-effective.

Personal experience and conclusions

Working with various Chinese suppliers and visiting factories, I came to the conclusion that the division is not based on the “expensive-cheap” principle, but on the principle of attitude to raw materials. The best results come from those who start with a thorough analysis and are not afraid to tell the customer: “This standard scheme will not work with your raw materials, you need this and this?” Companies like the aforementioned Yizhi Design Institute often go this route.

Failures usually happen when they try to copy a successful project one-to-one, but using different raw materials. I had experience setting up an installation in Henan province, which was copied from an installation in Sichuan. But the raw material was different - more humid and with a different profile of light hydrocarbons. As a result, the distillation column worked ineffectively and the dew point was not maintained. I had to redo the plates and adjust the temperature again, wasting time and money.

So, to answer the question in the title: yes, there are advancedfood CO2 technology, but they are not universal. Their strength is in adaptability. And the future, it seems to me, lies in flexible, modular systems with smart analytics of raw materials at the input and strict control at the output. And those who continue to sell “boxed solutions”? for any gas, sooner or later they will face complaints. There are no small things in this business—every little bit matters.