Calculation method for hydrogenation water injection volume

There is no fixed calculation formula; generally, the injection amount is adjusted so that the mass content of hydrogen sulfide and ammonia in the acidic water does not exceed 8%, based on high-quality standards.

Generally, it is injected at 5% of the feed rate, while monitoring the changes in the purity of the circulating hydrogen as well as the temperature rise in the reactor.

Why is water added during hydrogenation? I’ve never heard of it in class; could someone please give me an introduction?

In hydrogenation units used in the petroleum processing industry, the main purpose is to remove organic compounds such as sulfur and nitrogen from the feedstock in order to produce qualified products or intermediate materials. The sulfur and nitrogen removed exist in the form of hydrogen sulfide and ammonia. In equipment or pipelines at lower temperatures, hydrogen sulfide and ammonia can react to form ammonium hydrosulfide; when its concentration reaches a certain level, it will appear in crystalline form, which can easily cause blockages in the equipment or pipelines. It can also lead to severe corrosion of the equipment. The purpose of adding water to the hydrogenation units is to dissolve this ammonium salt.

In summary, the moderator’s post states that hydrogen sulfide and ammonia in the reaction products are dissolved and absorbed, thereby preventing the crystallization of ammonium salts from clogging the heat exchangers for those reaction products, as well as the high-pressure air coolers and their pipelines, and ensuring that the product meets the required corrosion resistance standards.

Hehe, the summary isn’t quite correct; it’s NH4Cl and NH4HS that are dissolved, not hydrogen sulfide and ammonia. Water is added before these substances appear, and this is related to the raw materials used in the process. Generally, water is added in the tube side after leaving the reactor and before entering the furnace for heat exchange, as well as before high-pressure air cooling

How was the current water injection rate of 14 m3/h determined? Since the nitrogen content in the feed is significantly lower than the design value, can the water injection volume be reduced? Answer: The amount of water to be added is calculated based on the sulfur and nitrogen content of the raw materials, but it is ultimately determined based on empirical values. Generally, the amount of water added is 5% of the feed volume; if the nitrogen content in the feed is high, then more water needs to be added. The amount of water that can be injected now can be reduced significantly, as it is also necessary to take into account the even distribution of the injected water among each set of air coolers. Additionally, since the temperature is currently low, the reaction heating furnace (BA-101) was shut down after hydrogen production was suspended. The wall temperature of the reactor has now dropped to 80–100°C. Once hydrogenation resumes and pressure is increased, the wall temperature is supposed to exceed 120°C once the pressure reaches 68 bar. To save time on increasing both pressure and temperature, it is desired that the heating furnace not be completely turned off; instead, about 1500 m3/h of ethylene can be used to maintain a low flow rate through the reaction system, thereby keeping the reactor’s wall temperature steady and allowing for rapid pressure increase once hydrogen is supplied. During vulcanization, it is necessary to monitor and record the amount of water generated by the reaction at all times; therefore, the glass level gauge in the high-pressure separator (FA-103) must be properly installed before vulcanization can begin.

Hehe... I’m referring to the national standards around the world for each hydrogenation station, which explain the purpose of water injection word for word. Bro, you’ve definitely never been involved in hydrogenation; I won’t say anything else