NEW ENGINEERING SOLUTIONS FOR PRODUCING HIGH-PRESSURE CARBON DIOXIDE

The paper considers the issues of optimization of technological schemes of producing liquid carbon dioxide transferred to the carbamide synthesis plant.

The main disadvantage of traditional technology solutions is the high energy costs, caused mainly by the necessity to compress CO₂ before its transfer to the synthesis reactor.

To implement the optimization of the technological stage of producing high-pressure carbon dioxide by means of combined use of compression and pumping equipment, the authors used the multifactor methods of chemical and technological processes modeling and software. With regard to urea aggregates of various capacity, the authors considered several manufacturing schemes.

The conducted technological calculations proved the appropriateness of equipment configuration.

The essence of the proposed for implementing technical solution is the simultaneous application of a compressor-pumping carbon dioxide unit where the process of producing liquid CO₂ under the reduced pressure is effectively combined with the supply of compressed gas of the required pressure (15 MPa) into the carbamide synthesis unit using the low-temperature pump. As opposed to the traditional technology, the proposed technical solution allows compressing gaseous CO₂ from 0.1 MPa to a relatively low pressure of 3.0 MPa, and then cooling by means of gasification cold of liquid carbon dioxide compressed to 15 MPa. For condensation, the authors proposed to use the absorbing water-ammonia refrigerating machine.

The paper presents the variant of turbo-compressor unit modernization, by means of which it is possible to achieve the significant increase of the yield of the urea units’ final product in order to reduce CO₂ emissions to the atmosphere. The proposed compressor-pumping unit differs from the others not only by the optimal construction of its technological scheme but also by its using to reduce the specific energy consumption of internal sources of cold and heat in the form of a flow of cold carbon dioxide compressed to the pressure of 15 MPa, and the high-temperature part of gaseous CO₂ compressed in the centrifugal compressor as well.