High pressure ammonia and carbamate pumps are, together with CO2 compressor, the most critical rotating equipment installed in urea plants.
In the past, reciprocating type pumps were usually selected for these services. In the recent years, with plant capacity increasing, centrifugal pumps have become the new standard; nevertheless, reciprocating pumps still find their place in the field of small capacity units or plant revamping.
High pressure ammonia and carbamate pumps are fully integrated into the process; therefore, the selection, purchase and engineering follow-up are multidisciplinary activities that require a deep and extended expertise.
In the last decade, Casale has specified and supplied a remarkable quantity of high-pressure ammonia and carbamate pumps for new and revamped plants dealing with different equipment suppliers and facing a large variety of Customer needs and constraints.
In these projects Casale provided services of engineering, procurement, quality control, plant construction or construction management, depending on Customer request.
For those plants where HP ammonia and carbamate reciprocating pumps are installed, it is becoming more and more attractive the possibility to install centrifugal pumps as new main operating items, keeping the existing reciprocating pumps as spare. This change can assure a considerable benefit from maintenance point of view, since centrifugal pumps are designed for longer uninterrupted operation than reciprocating ones, without wear parts to be replaced periodically. Also, involved plant areas will not be subject anymore to troubles related to pulsations and pipeline vibrations. The all with just few modifications of the plant itself.
In these revamping projects Casale can become the focal point for the Customer, handling all the activities of different disciplines:
- Process (e.g. capacity, head, NPSH recalculation, definition of new control philosophy, verification of the new requirements for the utilities, issue of new set of P&IDs, Hazop);
- Machinery (e.g. assessment of existing booster pumps, issue of all technical specifications necessary for inquiry and purchase, selection of preferred supplier, review of technical documentation, technical coordination of all the other involved disciplines, site assistance);
- Piping & Layout (e.g. revision of plot plan, new pipe routing, line modelling, stress analysis);
- Instrument & Electrical (e.g. specication of new control valve and recycle valve, integration of new system with existing DCS and ESD, denition of minimum requirements for critical and special instruments, electrical engineering);
- Civil & Structural (e.g. design of foundations and steel structures);
- …and much more!
Casale is therefore able to re-design the plant with the guarantee of the perfect balance among investment cost, service life and process flexibility.
The scope of engineering services covered by Casale can be tailored on Customer requests, involving also local construction contractors.
With its wide experience and references Casale will assist Customer to tune all details and to avoid mistakes along all the road towards a successful project.
For the same urea plant Casale was awarded of two different contracts for the detail engineering activities related to the installation of new high-pressure ammonia and carbamate pumps. In these two contracts Casale scope of work was different: in one case it included the procurement of the equipment while in the second case Casale followed all technical activities except purchase order to pump manufacturer that was issued directly by Customer.
For both high pressure ammonia and carbamate services new centrifugal pumps were foreseen in addition to the existing reciprocating pumps, kept as spare.
That was conceived with an outlook on future plant capacity increase, but also with the intent to modernize the plant.
Following Casale vision of “one source for all Customer needs”, Casale took cares of all aspects of the project, involving all the disciplines of plant engineering department.
Services provided by Casale included:
- Process and material balance study including verification of existing and design of new main process lines, bypass and recirculation lines. Verification of NPSH and possible need of booster pumps;
- Dynamic simulations;
- Issue of data sheets for equipment (pumps, control valves, etc.) and new control philosophy;
- Issue of material requisition and other inquiry documents for the new pump units;
- Technical Bid Evaluation (TBE) for the new pumps and technical follow-up (e.g. approval of vendor documents);
- Review and approval of Quality Control Plans (QCPs) issued by vendor, quality procedures, witnessing of inspections and tests, with local inspectors and/or from remote (e.g. pump performance test);
- Verification of the existing electrical network;
- Site survey;
- Laser scanning;
- Definition of tie-ins;
- Revision of plot plan;
- Modelling of the new lines and issue of ISOs using existing and/or new piping classes, as necessary;
- Piping stress analysis;
- Design and calculation of new foundations and/or steel structures;
- Preparation of the new control and shutdown logics for the implementation in the existing DCS and ESD systems;
- Supervision and assistance to installation, commissioning and start-up.
At the time of writing this document, the first project was successfully completed with the high-pressure ammonia pump put in operation; while the second project was still ongoing, with the carbamate pump being shipped to site.
It is worth to mention that the activities relevant to high pressure carbamate pump fell in the period of Covid-19 pandemic, forcing Casale to re-invent the typical approach to the project, and to conduct in remote session via web most of the critical activities (e.g. kick-off meeting, pre-inspection meeting, pump performance test).
Nevertheless, full support was always given to Customer, and negative impacts on the project were minimized.