Use of methanol off-gas

The off-gases from our polyol production are sent to the fuel gas pipeline network and then used as fuel in boilers; similarly, the off-gases from ammonia synthesis are also used as fuel for the first stage of the furnace. Therefore, it seems that they don’t have many uses.

Our factory mainly uses it as fuel for heating furnaces, and a portion of it is sent to power plants for combustion: handshake

Our unit’s gas is sent to the hydrogen production unit along with the off-gases from ammonia synthesis, and then sent to boilers for combustion.

Our plant is connected to the fuel gas network and is used as fuel for heaters and other equipment in the sulfur recovery unit.

The off-gas synthesized by our unit is sent to the hydrogen production unit, where it is used as fuel gas for heating furnaces and as domestic gas.

The off-gas generated after methanol synthesis in our company is first washed in a scrubber tower; after a small amount of methanol is absorbed from it, the off-gas is sent to pressure swing adsorption for hydrogen extraction. The gas obtained after hydrogen extraction is fed into a gas storage tank, and the extracted hydrogen is then sent back to the inlet of the compressor where it merges with the feed gas, thereby replenishing the hydrogen content in the system and sending it back to the synthesis process.

A hydrogen extraction unit can be installed, and then added to the feed gas for recycling

You can get in touch with Dalian Tianbang Membrane Technology Co., Ltd. Add a set of hydrogen recovery equipment. Recycle to save costs. Our company uses their membrane recovery process. Reuse of hydrogen. Used for the exhaust gas to fuel gas pipeline network.

Methanol is produced using natural gas as a raw material; the off-gases are used as fuel in methane conversion furnaces, or after PSA pressure swing adsorption to recover H2, the waste gases are sent to the methane conversion furnaces again! In new methanol production projects being built today, PSA pressure swing adsorption technology is often used. Moreover, as the scale of methanol production increases, the amount of off-gas generated also rises, making this gas an energy source that must be utilized. With stricter environmental regulations in place, and in order to improve efficiency and reduce energy consumption and emissions, it is not acceptable to simply discard or burn this off-gas, as that would represent a waste of resources – what a shame! Of course, there won’t be just one or a few ways to utilize the released gas; depending on the production process, the type of product, and other factors, these methods should be considered comprehensively to achieve the best results!

The purified gas can be returned as the feed gas, while some CO2 is added to adjust the hydrogen-to-carbon ratio and increase methanol production.

I was wondering if anyone could tell me how much off-gas is generated per ton of methanol produced?

In our facility, the methanol off-gas, due to its high hydrogen content, is sent directly to the ammonia synthesis plant for ammonia production. It can also be used as a fuel for methanol conversion systems.

It’s a bit different in our case: the off-gas is sent to pressure swing adsorption, and the hydrogen obtained from this process is used for diesel hydrogenation. The remaining CO, CO2, and CH4 are used as carbon sources and fed into the conversion furnace to adjust the hydrogen-to-carbon ratio of the conversion gas.

The information I have is that the plant in question has a capacity of 200,000 tons per year; it produces 25 tons of methanol per hour, which corresponds to 13,541.2 Nm3 of off-gas. The lower heating value of this off-gas, as I found, is 2,380 kcal/Nm3. I’m not sure whether this value is accurate, so I’d like to hear everyone’s opinions on it.

Serial Number Name Value 1 H2 77.0 2 CO 3.50 3 CO2 3.31 4 CH4 3.56 5 N2 12.59

Most of the off-gases from our plant are sent to the coking unit as fuel gas, while a small portion is used as fuel gas in the preheating furnaces of that unit; sometimes they are also sent to the boilers in power plants.

The amount of methanol off-gas is closely related to the components of the fresh gas entering the synthesis system as well as the content of inert gases in the off-gas; it varies from one manufacturer to another. This value can be calculated using the formula: Q_off = Q_fresh × b/a, where a represents the percentage of inert gases in the fresh gas； b is the content of inert gases in the recycle gas, %.

The off-gas from our unit is used for hydrogen production