Collection of information on the use of high-efficiency desulfurization agents in devices

Our dry gas desulfurization system is used internally by our plant; it handles the dry gas from our own plant separately! The desulfurizing agent used is produced by Jiangsu Hanguang, and its performance is quite good! ! Another issue is controlling the amount of solvent circulation and the concentration of the solvent

We have two sets of dry gas desulfurization units here. One set is located near the gas separation unit and shares a regeneration tower with the liquefied gas desulfurization process; the dry gas from the second catalytic stage goes into that set. The third catalytic unit has its own set of equipment, and it achieves very good desulfurization results, with the hydrogen sulfide content in the dry gas being zero. In terms of control, we adjust the circulation rate of the lean liquid based on the volume of dry gas and the amount of hydrogen sulfide present in it. We also regularly test the concentration of the solvent, and it’s important to ensure proper regeneration efficiency. The desulfurization process is quite simple.

We only have catalytic dry gas desulfurization units; all the dry gas in the plant is desulfurized there (two units, one for catalytic dry gas desulfurization and one for mixed dry gas desulfurization). N-methyldiethanolamine is used, and the desulfurization effect is good

We each have our own set for catalysis/coking: lol

The dry gas desulfurization capacity of the Storage and Transportation Plant at Daqing Refining & Chemical Company is 3600 Nm3·h-1, with a pressure of 0.3–0.7 MPa; the H2S content is approximately 1800 ppm, and the annual processing volume is 3.2×104 tons. The product is purified dry gas, with a hydrogen sulfide content of 20 ppm; it is supplied to the heating furnaces in various units within the plant as fuel. The alcohol amine method is used for desulfurization, with N-methyldiethanolamine (MDEA) being the desulfurizing agent used. The 1.5 Mt/a heavy oil catalytic products refining unit at Plant 2 of Fushun Petrochemical Branch is equipped with a dry gas desulfurization system, designed to treat 0.15 Mt/a of catalytic dry gas. Dry gas desulfurization employs the MDEA amine-based desulfurization process, with the alcohol amine solution being regenerated through a solvent regeneration system to enable reuse. The design requirement is that the H2S content in the purified catalytic dry gas should be ≤ 20 mg/Nm3.

We used to have small desulfurization units for each device; now the entire plant has three large desulfurization units, and the small ones have been shut down. Hydrogenation no longer involves dry gas desulfurization – only circulating hydrogen is desulfurized.

There are two desulfurization units: one is used for desulfurizing liquefied gas at a flow rate of 5000 Nm3·h-1 in catalytic dry gas, and the other is used for desulfurizing coking dry gas at a flow rate of 3000 Nm3·h-1; since the volume of liquefied gas is small, it is sent to the catalytic desulfurization unit. The desulfurization effect is excellent; the hydrogen sulfide content in the coking dry gas is zero, and that in the catalyzed gas is below 100PPM. Control the regeneration process to improve its efficiency; adjust the amount of lean liquid circulating based on the volume of dry gas and the hydrogen sulfide content in it, and regularly test the concentration of the solvent. The LH-98 desulfurizer from Zibo Kaimike Industry and Trade Company is used. The effect is pretty good, and the consumption is low – it’s under 15 tons per year.

Our factory has two catalytic units, both equipped with desulfurization systems; however, the dry gas is combined for desulfurization in one process, using N-methyldiethanolamine, which yields good results. This substance is supplied by a small factory affiliated with our own factory.

Principle of MDEA desulfurization: An amine molecule contains at least one hydrocarbon group and one amino group. Generally, it can be considered that hydrocarbon groups serve to reduce vapor pressure and increase water solubility, while amino groups help to achieve the necessary pH level in the aqueous solution, thereby facilitating the absorption of H2S. H2S is weakly acidic, while MDEA is a weak base; the reaction produces water-soluble salts. Since the reaction is reversible, MDEA can be regenerated and reused. The basicity of methyldiethanolamine decreases as the temperature rises; at low temperatures, the weakly basic methyldiethanolamine can combine with H2S to form amine salts, which can decompose into H2S and methyldiethanolamine at high temperatures. At lower temperatures (20°C–40°C), the reaction proceeds to the left (absorption), while at higher temperatures (>105°C), the reaction proceeds to the right (desorption). The alcohol amine desulfurization method is a typical absorption-regeneration reaction process. Its reaction mechanism is as follows: H2S and CO2, which are soluble in water and possess mild acidity, react with amines (which are weakly basic) to form salts that decompose at high temperatures. Taking methyl diethanolamine (MDEA) as an example, the main reactions it undergoes when absorbing H2S and CO2 are as follows: 2R3NH + H2S → (R3NH)2S; (R3NH)2S + H2S → 2R3NH2HS; R2NH + H2O + CO2 → (R3NH)2CO3; (R3NH)2CO3 + H2O + CO2 → 2R3NHHCO3. The reactions between alkanolamines and H2S and CO2 are reversible, and in the absorption tower the equilibrium of these reactions shifts to the right, allowing the acidic gases present in the feed gas to be removed ； In the regeneration tower, the equilibrium shifts to the left, and the solvent releases acidic gas components. Like all other absorption-regeneration reaction processes, our unit utilizes both gas separation and catalysis; the desulfurization of liquefied gas takes place in the same regeneration tower as that used for catalyzed dry gas processing. Our operational requirement is that the operating temperature at the top of the desulfurization tower should be ≤40℃ ； Operating temperature at the bottom of the desulfurization tower: ≯50℃ ； Temperature of lean liquid returning to desulfurization tower: ≯40℃ ； LPG feed temperature: 25～40℃ ； Regenerator top operating temperature: 105±5℃ ； Regeneration tower bottom operating temperature: 115±5℃ ； Temperature of rich liquid entering the regeneration tower: 85±3℃ ； Operating pressure at the top of the regeneration tower: 0.06±0.02 Mpa ； Desulfurizer concentration % (w): 20–35% ； Solvent load mol acidic gas/mol amine: ≯0.35 ；

Our company currently has two desulfurization units: one is located in the gas separation unit (for desulfurizing liquefied gas), and the other is in the coking unit (for coking liquefied gas, catalytic dry gas, and coking dry gas). The desulfurizing agent used in both units is N-methyldiethanolamine.