| abstract |
The present invention involves a process for the co-production of ammonia and urea in which two parallel gasifiers are utilized so as to optimize the H2/CO2 ratio in the combined syngas product, thereby maximizing the ammonia ad urea production. In a first gasifier, solid and/or liquid hydrocarbon materials are partially oxidized in the presence of an oxygen-rich gas in the presence of a temperature moderator, thereby generating a first synthesis gas mixture comprising carbon monoxide, hydrogen and carbon dioxide. In a second gasifier, natural gas is partially oxidized in the presence of an oxygen-rich gas, thereby generating a first synthesis gas mixture comprising carbon monoxide, hydrogen and carbon dioxide. Because natural gas has a lower C/H ratio than the solid and/or liquid hydrocarbon materials, insufficient CO2 is produced in the natural gas gasifier for urea production when only natural gas is used to produce syngas. Conversely, the high C/H ratio of the solid and/or liquid hydrocarbon materials produces an excess amount of CO2-much more than is needed for urea production-and thus a large portion of the CO2 is vented when only solid and/or liquid hydrocarbon materials are used to produce syngas. By running two gasifiers in parallel on the separate feeds, the feedrate to each gasifier can be adjusted to optimize to maximize the H2/CO2 ratio in the combined syngas product stream, resulting in an elimination or minimization of CO2 emissions from the integrated gasification, ammonia and urea production facility. |