The seven stages of chemical engineering technology from concept to industrialization (Issue 34/100) -- Overview of the process package

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This post was last edited by xiouxingzhe on 2026-6-10 23:56. The seven stages of chemical technology from concept to industrialization (Issue 34/100) —— Technology stabilization: the process package, a strategic link between preceding and subsequent stages. Dear friends: Hello everyone! Starting from this issue, we enter the fourth stage of the seven-stage model, which is the most content-intensive and longest-phase stage: technology stabilization. The core task at this stage is one thing only: to transform the pilot-scale data package into a complete process package. As mentioned in the previous issue, the pilot plant data package is the “raw material,” while the process package is the “design plan.” In this issue, let’s first talk about the process package itself – what it is, why it is important, and the logic behind its preparation. I. The role of the process package in the entire project: In the seven-phase model, technical finalization occupies a strategic hub position that connects the preceding and subsequent stages. Upward, it takes in pilot-scale data packages – transforming what can be done in laboratories and pilot plants into something that can also be achieved in industrial facilities. Downward, it drives engineering translation—providing the unique and authoritative technical input for subsequent phase design, basic design, detailed design, procurement, and construction. This technical input is the process package. If the entire chemical plant project is compared to a person, the process package is its genetic blueprint – it determines all the fundamental characteristics of this facility in the future. Information on how tall and large the equipment can be, how the pipes should be laid, how the instruments should be controlled, and how safety can be ensured is all encoded in the documents of the process package. The subsequent engineering design is merely to express these genes. It is precisely because of this status that, once signed, the process package becomes the technical benchmark for all parties involved in the project. Design is based on it, procurement is based on it, and performance evaluation is also based on it. It is not a reference manual, but a “technical constitution” – all disputes and disagreements arising from subsequent work must ultimately be resolved in accordance with this document. II. The PFD is the sole data source for all subsequent documents. What is the most critical document in the process package? It is a process flow diagram, abbreviated as PFD. The PFD indicates all major equipment and their tag numbers, the temperature, pressure, and flow rates of all key streams, the specifications and consumption amounts of all utility systems, and all key control loops. These data are not for decoration; they are the sole and authoritative source of data for the entire process package. What is the thermal load of a certain heat exchanger listed in the equipment data sheet? It must be the same as that on the PFD. What is the operating temperature of a certain control valve on the instrument data sheet? It must be the same as that on the PFD. What is the diameter of a certain pipeline? It must be deduced from the flow data of the PFD. I set a strict rule for myself: data that is not available on the PFD must not appear in any subsequent documents. If someone asks me “Where does this temperature data come from?”, the answer must be only one—“It comes from page X of the PFD.” If it isn’t on the PFD, then this data is baseless and cannot be used. Behind this ironclad rule are lessons learned at great cost by many projects. During the design phase of a project, the process engineering team changed a parameter – for example, adjusting the temperature of a certain stream of material from 180 degrees to 190 degrees – but failed to update the PFD accordingly, nor did they inform the teams working on subsequent stages of the process. As a result, the equipment discipline selects materials based on a 180-degree approach, the instrumentation discipline sets the range using a 180-degree approach, and the piping discipline performs stress analysis using a 180-degree approach. Upon arriving at the site, it was discovered that the data from different departments did not match, and the cost of redoing the work was far more than just modifying one diagram. If all specialties strictly used the PFD as the sole data source, such problems would not occur. If the PFD is changed, all downstream files are updated accordingly. The PFD has not been changed; no one is allowed to adjust the parameters without permission. The rules are simple; enforcing them requires discipline. III. Overview of the sixteen core tasks: From the project definition stage to the official delivery of the process package, the technology finalization phase comprises sixteen core tasks. These sixteen tasks are what we will cover one by one in the next twenty-plus issues. First, project definition and scope. Clarify the technical source, plant scale, product specifications, boundary conditions, and delivery standards. This is the basis for preparing the process package; without a clear scope, further work cannot be carried out. Second, the collection of physical property data. Establish a complete database of material properties for all materials involved. Without accurate physical property data, subsequent material balance calculations and equipment selection become unreliable. Third, material balance calculation. Full-process simulation to determine the flow rate, composition, and state of all process streams. Fourth, heat balance calculation. Foundation for utility selection and heat exchanger network optimization. Fifth, momentum balance calculation. Determine the key parameters of pressure-boosting equipment such as pumps and compressors. Sixth, PFD preparation and review. The results of the three balance calculations are all concentrated in the PFD. The completion of the review and freeze for the PFD represents the first and most important milestone in the process package development process. Seventh, equipment selection and data sheet. Reactors, towers, heat exchangers, vessels, pumps, compressors – design calculations and preparation of data sheets for all process equipment. Eighth, PID preparation and review. Refine the pipelines, valves, instruments, and control schemes based on the PFD. PID freezing is the second milestone. Ninth, auxiliary pipeline design. Start-up and shutdown, accidental emissions, purging and replacement, handling of defective products – design of auxiliary pipelines outside normal operation pipelines. Tenth, pipeline material grade. Determine the pipe material and specifications based on the medium, temperature, and pressure. Eleventh, instrument and interlock design. Instrument data sheets, interlock logic diagrams – the interlock logic must be developed under the leadership of the process engineering team. Twelfth, equipment layout and boundary conditions. Suggested equipment layout diagram and boundary condition table. Thirteenth, HSE and analysis and testing. Safety and environmental protection specifications, waste discharge list, sampling system design. Item fourteen: Process flow description. Convert technical information into a systematic written description. Items 15 and 16: Integration and delivery of the overall specification document. Complete document assembly, data consistency verification, final review, document signing, and handover. Each of these sixteen tasks has clear inputs and outputs, and each one serves as an essential foundation for the subsequent stages. Starting from the next issue, we will go through them one by one. IV. Some experience in preparing process packages Here, I would like to share my own insights: when preparing a process package, the most cost-effective approach is to do thorough calculations in the early stages and include everything that needs to be specified. Many project managers urge, \"The PFD is almost ready; let’s move forward quickly,\" but by taking an extra week during the PFD phase to complete the data, the progress on the PID and equipment data sheets will actually be faster—because you provide a clear and complete input for those who work downstream, allowing them to use it right away without the need for repeated discussions and adjustments. Conversely, if the data on the PFD is incomplete or inaccurate, the downstream teams receive a vague input, and they can only fill in the gaps based on their own understanding. By the time it’s discovered that there’s a mismatch between the various specialties, it takes time to identify the reasons, revise the PFD, and update it for each specialty – this back-and-forth process takes well over a week. The same principle applies to PID as well. If auxiliary pipelines, instrument interlocks, and sampling points are all taken into account during the PID stage, there will be much less rework by the piping team during the subsequent detailed design. The root cause of many on-site changes is not mistakes in construction, but rather the fact that the drawings were not clear to begin with. V. Schedule for the fourth phase: From issue 35 to issue 59, the fourth phase consists of a total of 26 issues. The general outline is as follows: project definition and scope (Issue 35), collection of physical property data (Issue 36), material balance calculations (Issue 37), heat balance calculations (Issue 38), momentum balance calculations (Issue 39), preparation and review of the PFD (Issues 40–41), equipment selection and data sheets (Issues 42–44), preparation and review of the PID (Issues 45–47), design of auxiliary pipelines (Issue 48), pipe material specifications (Issue 49), instrument and interlock design (Issue 50), HAZOP analysis and SIL classification (Issues 51–52), calculation of safety valve discharge capacities (Issue 53), equipment layout and boundary conditions (Issue 54), HSE and analytical testing (Issue 55), integration of process flow descriptions and the general specification document (Issue 56), final review and delivery of the process package (Issue 57), and finally, two project cases are used to conclude the series (Issues 58–59). Each issue includes practical methods and lessons learned from real projects, allowing marine professionals to see how a complete process package is developed. Preview for the next issue: Issue 35: Project Definition and Scope — Technical Sources, Plant Scale, and Boundary Conditions. The first task in preparing a process package is to define the boundaries clearly. Whose is the technology? How big should the device be? What are the specifications of the product? Where is the boundary line? What are the delivery standards? If these fundamental issues are not clarified, all subsequent work may go off track. To be continued in the next issue.