Who is familiar with the NHD desulfurization technology?

We have only used NHD to remove carbon dioxide; we haven’t used desulfurization yet, and we hope for guidance from those with more experience.

I have also seen the NHD decarbonization technology; I’ve only heard of NHD desulfurization recently and haven’t seen it yet

Principle of NHD desulfurization and decarbonization: Based on the generalized acid-base theory, in the molecular structure of polyethylene glycol dimethyl ether, the oxygen atom in the ether group acts as a hard basic center, while the CH3- and -CH2-CH2- groups function as soft acidic components. Therefore, the NHD solvent has a strong ability to dissolve and absorb both hard acidic gases (such as H2S and CO2) and soft basic gases (such as COS), thereby achieving the removal of acidic gases.

Reply to the person above: It is said that NHD does not absorb organic sulfur COS very well; therefore, an organic sulfur conversion furnace may be necessary in the processes prior to the purification stage! In other words, NHD cannot effectively remove organic sulfur.

I am also learning about the NHD desulfurization process

This method was developed successfully by the American company Allied Chemicals in 1965; it is called Selexol, and it involves the use of a mixed solvent made up of multiple components of polyethylene glycol dimethyl ether. Currently, Selexol is a patented technology of the UOP company in the United States; the Nanhua Group’s research institute in China has also developed a related process, with the solvent being marketed under the name NHD solvent. The freezing point of polyethylene glycol dimethyl ether is -22 to -29°C, and its vapor pressure at 25°C is <1.33 Pa. The higher the absorption pressure, the more effective it is in enhancing the absorption capacity and purity of the physical solvent. The absorption pressure in the NHD process is generally between 1.6 and 7.0 MPa, while the absorption temperature is usually around 0°C. The main component of NHD is polyethylene glycol dimethyl ether; it is a multi-component formula solvent. China’s Nanhua Company began researching the Selexol process in 1980, and on this basis developed the NHD process; in 1984, its gas purification process passed a ministerial appraisal. Its advantages include low energy consumption, high purification efficiency, stable operation, and a relatively simple equipment setup. It represents a typical physical absorption process; the solvent has a low vapor pressure and is low in volatility, so there is no need to install devices for washing and recovering the solvent in the process, nor does it cause any damage to subsequent steps. Long-term operation data also show that the loss of solution is very low, equivalent to 1/15 of that in hot potassium alkali solutions. Its technology is suitable for the purification of coal gas with high levels of sulfides and CO2; therefore, the NHD process holds great promise for application in the fertilizer industry, coal chemical industry, and carbon-1 chemistry sector.