Esterification unit for producing crude methyl methacrylate, esterification process using said unit and plant comprising said unit

Esterification unit for producing crude methyl methacrylate (MMA) from methacrylamide (MAM), and at least methanol and water, comprising several reactors (1, . . . n, n+1, . . . , . . . , N), each reactor having an upper part and a lower part, characterized in that the reactors are set up in a serial way so that there is a counter current flow between gaseous phase and liquid phase, the liquid phase flowing from first reactor (1) of the series to last reactor (N or (N+1)), and the gaseous phase flowing from last reactor to first reactor,

• the first reactor of the series comprising:
• methacrylamide, methanol and water lateral inlets,
• at least a liquid phase outlet located at the bottom of the lower part of the reactor,
• the last reactor comprising a lateral steam inlet located at the lower part,
• and each reactor also comprising:
• at least a gaseous phase outlet, at the top of the upper part,
• at least a gaseous phase inlet at the lower part, the reactors being connected in such a manner that the gaseous phase outlet of reactor n+1 is linked to the gaseous phase inlet of reactor n,
• at least a lateral liquid phase inlet located at the lower part, the reactors being connected in such a manner that the liquid phase outlet of reactor n is linked to the lateral liquid phase inlet of reactor n+1,
• at least another lateral liquid phase inlet located at the lower part, the liquid phase outlet of reactor n being linked to said another lateral liquid phase inlet of said reactor n.