A method of operating a microchannel reactor, in which a reaction channel is formed, includes generating a reaction product by causing a chemical reaction in a raw material fluid while causing the same to flow through a reaction channel. If the flow rate of the raw material fluid and/or the reaction product fluid flowing through a reaction channel decreases, a fluid which is inert to the raw material fluid and the reaction product is mixed into the fluid flowing through the reaction channel, in a flow rate corresponding to the decreased flow rate and at a position downstream of the introduction position of the raw material fluid into the reaction channel.

This invention relates to a process for operating a gas phase phosgenation plant (100) to form an isocyanate (4) by reacting an amine (2) with phosgene (1), in which the gas phase phosgenation plant is shut down by first stopping the amine stream and still maintaining the phosgene stream. After a period of time which corresponds to at least 10 times the residence time of phosgene (1) in the main parts of the gas phase phosgenation plant (100) in regular operation, calculated from the time at which the amine inflow has been completely stopped, the feed of phosgene is also stopped. An inert gas stream (3) is maintained through the amine and phosgene feeding devices and through all the other essential parts of the gas phase phosgenation plant (100) during the shutdown.

A method for shutting down a gas treatment plant to minimize flaring and allow for continued production during the shutdown procedure. The method includes reducing a sour gas feed flow rate and monitoring pressures in headers for various process units to identify when pressure equalization occurs. The method includes sampling the rich solvent in the system to verify a setpoint concentration of hydrogen sulfide has been reached to initiate a final system shutdown.