The seven stages of chemical engineering technology from concept to industrialization (Issue 62/100) -- Concept design

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This post was last edited by xiouxingzhe on 2026-7-14 14:12. The seven stages of chemical technology from concept to industrialization (Issue 62/100) — Engineering translation: Solution design and planning. Dear friends: Hello everyone! In the previous issue, we discussed the feasibility study report, and a conclusion was reached regarding whether the project should be carried out or not. Once the feasibility study is approved, many project managers rush to move on to the detailed design phase. But there is also an intermediate step that is easy to skip, and skipping it can cause a lot of trouble—the plan design. Feasibility study addresses the question of \"whether to build it\", determining whether it is economically viable and whether there is sufficient land available. The design phase addresses the question of “how to arrange it” – namely, where exactly the installations will be placed within the site, how the equipment will be arranged, how pedestrian and material flow will be organized, and what the appearance of the buildings will be. From feasibility studies to basic design, such a “positioning framework” is needed in between to establish the overall layout. If the scheme design is skipped and it is only during the basic design phase that it is discovered that the overall layout is unreasonable, the building setbacks are insufficient, or there is no enough space for fire lanes, the cost of redoing the work becomes much higher than it would have been during the scheme design stage. The scheme design also has another important purpose: it is a legal prerequisite for submission to the Natural Resources and Planning Bureau for approval. If the plan is not approved, all subsequent planning and permitting procedures cannot be carried out, and the project cannot start legally. So in this issue, we will mainly discuss two things: how to carry out scheme design and how to submit plans for approval. I. The role of scheme design: Scheme design is not a simple repetition of the feasibility study, nor is it an early preview of the basic design. It has its own independent positioning. Feasibility study assesses the viability of a project at a macro level – considering the market conditions, the maturity of the technology, and whether it is economically viable. Scheme design involves determining the \"overall framework\" of the facility at a meso-level – how the facility will be arranged within the designated area, how the functional zones will be defined, where the utility ducts will run, and what the architectural style will be. The basic design serves as a further elaboration—what models of equipment to use, how to calculate the structure, and how to lay out the piping. Three stages, from macro to meso to micro, progressing in layers. The core outputs of the design proposal are three things: the general layout plan, the architectural floor and elevation plans, and the main process plan. Once these three elements are determined, the subsequent basic design will have clear frameworks and boundary constraints. The general layout defines the boundaries of the plant and the relative positions of various functional areas; the architectural plan determines the span of the framework and the floor height; while the main process plan specifies the quantity and specification range of the core equipment. During the design phase, it was found that the overall layout was unreasonable – for example, a certain building was too close to the boundary line, or the turning radius of the fire access roads was insufficient – and it was sufficient to adjust their positions on the drawings. Applying the same adjustments at the detailed design stage may require modifications to the multi-disciplinary design documents that have already been completed, as changing one element can affect the entire system. II. General layout plan: from demonstration to implementation. A general layout is also prepared during the feasibility study phase, but it is intended for demonstration purposes – based on rough information about the plot, its aim is to determine whether the plot is sufficient and whether the investment is within acceptable limits. The general layout at the design phase is for implementation purposes – once the exact plot boundary maps and topographic maps are available, it is developed according to the actual dimensions and regulatory requirements. The precision of the two is not in the same order of magnitude. During the feasibility study phase, a schematic representation of the functional zones may simply be drawn on a topographic map at a scale of 1:5000 or 1:10000. During the scheme design phase, a general layout plan at a scale of 1:500 or 1:1000 is required; the coordinates of building backsets and road centerlines, as well as the vertical elevations and the routes of utility tunnels, must all be precise to within a meter. The master plan should first involve functional zoning. Reasonably divide the production area, auxiliary production area, storage and transportation area, and management area. The core principles of functional zoning are the shortest logistics routes and safe pedestrian flow. The production area is the core of the facility and should be located in the best part of the site – with favorable geological conditions and proximity to utility connections. Auxiliary production areas — circulating water stations, refrigeration stations, air compression stations, and substations — should be located adjacent to the main production area to minimize the distance over which utility services need to be transported. The storage and transportation area – including the raw material tanks and the finished product warehouses – should be located near the logistics entrances and exits to facilitate access for tank trucks or freight vehicles, while maintaining a safe fire separation distance from the production area. The management area – office buildings, control rooms, and laboratories – should be located upwind or to the side of the facility, away from sources of danger. Then organize the flow of people and goods. The operators enter through which door and take which route to the workshop; raw materials enter from one side while products exit from another. The pathways for heavy trucks and operators must not intersect. The logistics routes need to be smooth – trucks carrying raw materials should arrive, unload their cargo, and then leave; trucks carrying finished products should load up and leave the facility, so that there are no dead ends. Fire lanes should be circular or equipped with turnaround areas, and their width and turning radius must meet the requirements of the regulations. Vertical design is also an important aspect at this stage. In chemical plants, many materials flow by gravity, and the elevation differences between equipment must meet the requirements for gravitational flow. The drainage for the entire plant also needs to be addressed through vertical design – whether to use gravity-based drainage or to install sump pits and lift pumps, and how to coordinate the design levels of the ground surfaces and roads to prevent backflow during heavy rain. If these are not resolved during the planning stage, they will cause major problems during the construction phase. The master plan also needs to take into account provisions for future development. If there is room for growth in the product, the planning for the land required for the second phase should be included in the overall layout during the design stage; even if construction doesn’t take place now, the land should at least be reserved, with the utility tunnels and connections for public utilities prepared in appropriate locations. III. Architectural design: From plan to elevation. The architectural design and the technical solutions must be developed simultaneously. The size of the equipment determines the height and span of the building, while the building’s column layout and floor heights limit the flexibility in arranging the equipment. An architectural floor plan should show the functional zoning of each floor, the approximate locations of equipment installations, the provision for operation and maintenance passages, as well as the locations of stairs and elevators. The architectural elevation shows the overall appearance of the building, the floor heights and total height, as well as the locations of the main doors and windows. Sufficient openings and support structures must be provided where the distillation tower passes through the floor. Sufficient space for operation and maintenance should be reserved around the reactor. The base location and loads of heavy equipment should be initially aligned with the structural plan. All of these need to be clarified during the scheme design phase. The architectural plan must also meet the requirements for planning approval. Does the building height meet the height restrictions specified in the planning regulations? Do the building spacing requirements meet fire safety codes? Is the building’s facade in harmony with the surrounding environment and the overall style of the complex? These are the key aspects that are carefully examined during planning approval; it’s not a matter of simply thinking something looks good. When necessary, renderings are required to visually demonstrate the appearance of the building. IV. Plan submission for approval: The step in plan approval. After the plan design is completed, a set of documents must be prepared and submitted to the Bureau of Natural Resources and Planning for approval. The documents submitted for approval usually include: the general layout plan, the floor and elevation plans of the main buildings, renderings, and design specifications. The key points examined by the Planning Bureau include: whether the land use type is in line with the plans, whether the building backset meets the requirements, whether the floor area ratio and building density are within acceptable limits, whether the building height falls within the permitted range, whether the fire safety distances comply with the regulations, whether the green space ratio meets the standards, and whether the architectural style is consistent with that of the surrounding areas. These are mandatory requirements at the regulatory level. Some requirements may not be very reasonable from a technical perspective – for example, a piece of equipment might need to be located right next to the property boundary to meet logistics needs, but building backset requirements dictate that it must be placed several meters further back – in such cases, the design plan must comply with the planning regulations, rather than the other way around. Another aspect that cannot be ignored in the project design phase is geological survey work. Once the general layout is basically finalized and the locations of the main equipment are determined, geological survey work can begin. The geological survey report serves as the key input for pile foundation design, ground treatment plans, and equipment foundation design in subsequent preliminary design stages. If the geological survey is not initiated in advance, there will be no geological data available at the stage of basic design, forcing the structural engineering team to carry out a preliminary design based on assumptions. Only after obtaining the geological report can a reevaluation be done; if the actual conditions differ significantly from the assumptions, the entire structural design may need to be redone from scratch. After obtaining the geological survey report, it is also necessary to compare it with the geological predictions made during the preliminary design phase. If there is a significant difference – for example, if it was predicted that the rock layer would be moderately weathered, but actual exploration reveals deep sediment – it means that the original foundation plan can no longer be used, and adjustments need to be made promptly. During the scheme design phase, adjusting the basic scheme merely involves changing a few pages of the report; it is only after the basic design is completed that it becomes clear the structural drawings already prepared were done in vain. V. Handling of permits after scheme design: Once the scheme design is finalized and approved by the planning bureau, the process of obtaining the construction land use plan permit and the construction project plan permit begins. The processing time for these two permits is usually long, and it needs to proceed in parallel with the subsequent basic design work. The approval order must not be mistaken. Only after the plan design has been approved by the Bureau of Natural Resources and Planning and an approval response is obtained can a construction project planning permit be issued. The construction project planning permit is one of the legal prerequisites for obtaining the construction permit later on. The construction land planning permit is issued at an earlier stage, in parallel with the preliminary land use review. The three stages — land use planning approval, plan review, and construction planning approval — are sequential in time and logically interconnected. A considerable portion of the materials required for obtaining permits can be directly obtained from the results of the design phase – such as the general layout plan, the plans and elevations of the main buildings, and descriptions of the functional zones. The plan design is solid, so the documents required for obtaining the permit are already ready. The plan design is merely a formality; it is only when it comes to applying for the permits that it becomes clear that many additional drawings and analyses are needed, which significantly prolongs the permit issuance process. Many projects are delayed, not because of slow construction, but due to delays in the approval process. VI. Some Insights There are a few insights that can be shared from the project design phase. First, the plan design cannot be a mere formality. For some projects, once the feasibility study has been completed, the design process seems like a mere formality; as a result, the overall layout is unreasonable, the buildings are not positioned far enough from boundaries, and there isn’t enough space for fire lanes. When these designs are submitted to the planning authority for approval, they are rejected and require revisions, with those revisions taking several months to complete. Spending a few extra days during the planning stage to finalize the layout is much faster than having to make changes after the planning authority rejects it. Second, the process and construction must be advanced simultaneously. The design plans for some projects were presented as \"building exterior designs\"; the facades of the plants looked beautiful, but the internal layout of the equipment was completely incorrect – there wasn’t enough space to lift the reactors, the manholes on the towers faced the walls, and the access passages for maintaining pumps were blocked by columns. During the scheme design phase, while it is not necessary to determine the exact location of each pump, the spatial requirements and relative positions of the main equipment must be essentially correct; otherwise, the architectural scheme will be nothing but a fantasy. Third, the plan should be reviewed from the perspective of planning approval. Process engineers tend to view the overall layout from the perspective of operational convenience, but the planning department focuses on the regulatory requirements – whether there is sufficient distance from boundaries, adequate fire safety distances, and a sufficient proportion of green space. Before submitting the plan for approval, conduct a \"role-reversal review\" by examining it from the perspective of the approval officers; address any issues identified in advance, which will significantly improve the smoothness of the approval process. Preview for the next issue: Issue 63 – Basic design: Determining the “genes” of the device. The conceptual design has been approved, and the overall framework of the device has been established. Next is the basic design – drawing out every muscle and every blood vessel on the skeleton in detail. What are the key tasks that need to be completed in basic design? How can process system design be deepened? What are the changes in equipment layout from the proposed layout to the final layout? How to compile the four special articles? To be continued in the next issue.