Process for production of ammonia and derivatives, in particular urea

A plant for producing ammonia and a derivative of ammonia, particularly urea, from a natural gas feed (NG), said plant comprising:

• a front-end section for generation of ammonia make-up synthesis gas;
• a synthesis loop for synthesis of ammonia from said make-up synthesis gas;
• a section for the conversion of at least part of the synthesized ammonia into said derivative;
• power users requiring a mechanical power for operation, and at least one thermal user requiring a heat input for operation;
• wherein said plant further comprises:
• at least one reciprocating gas engine, the power produced by said gas engine being transferred to at least one of said power users,
• heat recovery means for recovering heat from exhaust of said gas engine, and in that said plant further comprises:
• heat recovery means for recovery of low-grade heat from exhaust of said gas engine via a heat exchange medium,
• said heat recovery means comprising indirect heat exchange means arranged to heat said medium to a temperature not greater than 200° C., and
• said plant comprises means arranged to transfer said low-grade heat to at least one of said thermal users.

A method of modernizing a plant for producing ammonia and a derivative of ammonia, particularly urea, wherein:

• said plant comprises a front-end section for generation of ammonia make-up synthesis gas;
• a synthesis loop for synthesis of ammonia from said make-up synthesis gas;
• a section for the conversion of at least part of the synthesized ammonia into said derivative;
• the plant also comprising power users and thermal users;
• wherein:
• the provision of at least one reciprocating gas engine, and the provision of suitable power transfer means to transfer the power produced by said engine to at least one of said power users, the provision of heat recovery means for recovering a heat from exhaust gas of said gas engine, and the provision of heat recovery means for recovering a low-grade heat from exhaust gas of said gas engine, by indirect heat exchange with a medium, said medium being heated by the exhaust gas to a temperature not greater than 200° C.,
• the provision of the so recovered low-grade heat to at least one of said thermal users of the plant, or to at least one newly-installed thermal user.