What is the impact of the water-to-carbon ratio in hydrogen production on operations, and how should it be managed?

Effect of water-to-carbon ratio: The water-to-carbon ratio is the most sensitive process parameter in the conversion of light oil. Increasing the water-to-carbon ratio can reduce catalyst coking and lower the content of higher hydrocarbons such as C2 and above at the outlet of the bed, which is highly beneficial for the conversion reaction. When heavy naphtha is used as the feedstock for conversion, the water-to-carbon ratio should also be increased appropriately to reduce carbon deposition. However, an increase in the water-to-carbon ratio correspondingly increases the consumption of desalinated water and converter gas, as well as the load on the downstream cooling system. Therefore, the appropriate water-carbon ratio can only be determined based on the specific process equipment.

Effect of water-to-carbon ratio: The water-to-carbon ratio is the most sensitive process parameter in the conversion of light oil. Increasing the water-to-carbon ratio can reduce catalyst coking and lower the content of higher hydrocarbons such as C2 and above at the outlet of the bed, which is highly beneficial for the conversion reaction. When heavy naphtha is used as the feedstock for conversion, the water-to-carbon ratio should also be increased appropriately to reduce carbon deposition. However, an increase in the water-to-carbon ratio correspondingly increases the consumption of desalinated water and converter gas, as well as the load on the downstream cooling system. Therefore, the appropriate water-carbon ratio can only be determined based on the specific process equipment.

Our plant uses dry gas for hydrogen production; the designed water-to-carbon ratio is 3.7–5.0, with the methane content at the conversion outlet kept at no more than 7%. While ensuring that the methane content at the conversion outlet remains within acceptable levels, as well as maintaining stable feed rates and temperatures at both the inlet and outlet of the conversion process, the water-to-carbon ratio can be reduced appropriately. In such cases, the methane content will gradually increase. The water-to-carbon ratio at which the methane content at the conversion outlet approaches the specified limit represents the minimum value that can be used in actual production; it is absolutely essential to maintain a water-to-carbon ratio higher than this value to ensure proper operation. At the same time, attention must also be paid to changes in the properties of the raw materials; when the raw gas becomes heavier, it is advisable to increase the water-to-carbon ratio. The hazards associated with high or low water-to-carbon ratios have been explained in great detail by the person above; I will simply share my own practical experience, in the hope that it will be helpful to the original poster.

What the two people upstairs said is already very clear, and I’ve also learned from it; I’d like to add that the actual water-to-carbon ratio is largely determined by the properties of the raw materials and catalysts. Currently, the water-to-carbon ratio in newly designed hydrogen production facilities in China is generally 3.2, with adjustments made during operation based on what was mentioned upstairs.

Advantages of a high water-to-carbon ratio in hydrogen production: 1. High hydrogen conversion rate； ⒉Reduce carbon deposition on the conversion catalyst during raw material reaction ； ⒊Reduce or eliminate carbon deposition on the conversion catalyst ； ⒋Improving the distribution of the raw material in the conversion catalyst ensures even distribution of heat within the furnace tube. The disadvantages are: an excessive water-to-carbon ratio; 1. high fuel waste ； ⒉High steam waste ； ⒊Operating costs are high. The specific procedures depend on the job requirements and the operating condition of the device.

The water-to-carbon ratio is generally calculated based on the average number of carbon atoms in the raw materials used by this device; when there are significant changes in the raw materials, failure to make corrections leads to inaccurate results. In practice, the value for the lighter components can be smaller, as the actual water-to-carbon ratio remains unchanged; for the heavier components, this value is larger – the principle is the same. The water-to-carbon ratio is related to the catalyst and the design of the device itself; it is not advisable to blindly pursue a low water-to-carbon ratio. In operation, adjustments can be made by referring to the methane content at the outlet.

Our water-carbon ratio is designed to be 3.5, but we keep it between 4.0 and 4.5; although energy consumption is higher, it gives us peace of mind. This is better than damaging the catalyst.

I say, where do some guys get this information from? Such a professional level of language – it seems like making money this easily is way too good to be true. Copied verbatim. Not only was it copied, but more importantly, it didn’t address the question at all.

We produce hydrogen from coking dry gas; in my opinion, a water-to-carbon ratio of 3.5–4.5 is sufficient. This approach not only helps to prevent carbon buildup on the catalysts and ensures high methane conversion rates, but also avoids overloading the conversion system.

An excessively high water-to-carbon ratio can lead to the deactivation of the conversion catalyst, while an excessively low ratio can cause carbon deposition on the catalyst. We keep this ratio between 3.5 and 5.5; raising the upper limit can increase the conversion rate but also increases energy consumption. The water-to-carbon ratio can be chosen based on the actual operating conditions