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Seven stages of chemical engineering technology from concept to industrialization (Issue 68/100) —— Engineering transformation: Energy conservation assessment and soil and water conservation. Dear readers: Hello! In the previous issue, we discussed three special topics: fire safety, environmental protection, and occupational health. In this issue, we discuss two other specialized tasks that need to be carried out simultaneously during the engineering implementation phase: energy efficiency assessment and soil and water conservation. These two tasks are different from the previous four specialized articles. The four special sections focus on protective design in terms of safety, fire protection, environmental protection, and occupational health, with \"prevention\" as the core principle. Energy conservation assessment focuses on energy consumption indicators and energy-saving measures, with the core principle being “conservation”. Soil and water conservation focuses on preventing soil erosion during the construction period, with the core principle being \"protection\". Although the approval processes and review methods for these two tasks differ, they are both essential components in ensuring project compliance. The energy conservation review opinion is one of the prerequisites for starting a project, while the soil and water conservation plan is a legal document that must receive approval from the water resources authorities before work can begin. I. Energy efficiency assessment: In accordance with the Measures for Energy Efficiency Review of Fixed Asset Investment Projects, projects with an annual comprehensive energy consumption reaching a certain threshold are required to prepare an energy efficiency report and submit it to the competent authorities for review. For chemical projects, this \"specified standard\" generally refers to an annual comprehensive energy consumption that equates to a certain amount of standard coal; the specific figures may vary depending on local regulations, but most chemical projects of medium size or larger fall within the scope of evaluation. The energy-saving review opinions serve as an important basis for the commencement of project construction, completion acceptance, and operation management. If the energy assessment fails, it will affect subsequent construction permits and completion inspections (in some places, the energy assessment is considered a prerequisite for the environmental impact assessment). The core contents of a energy assessment report include: a comprehensive analysis of the project’s energy usage, precise calculations of energy efficiency indicators such as energy consumption per unit of product and energy consumption per 10,000 yuan of output value, an evaluation of the energy efficiency levels of the main energy-consuming equipment, and a feasibility study of energy-saving measures. An analysis of energy utilization is the basis for energy assessment. It is necessary to clarify all the energy consumptions of the project – electricity, steam, natural gas, coal, water – and list separately the annual consumption amounts, the equivalent coal coefficients, and the amount of equivalent coal. The data source is the utility consumption table of the process package and the heat balance calculations. It is important to note that the consumption of utility services should be listed separately for different operating conditions – the normal operating conditions differ significantly from those during startup, and the steam consumption also varies between winter and summer. During the energy-saving review, if calculations are done only under normal operating conditions, the authorities may ask whether the peak energy consumption under extreme operating conditions has also been taken into account in the analysis. Unit product energy consumption and energy consumption per 10,000 yuan of output value are the key indicators for measuring the energy efficiency level of a project. These two indicators need to be compared with industry benchmarks to determine whether they are above or below the industry average. If it is below the industry benchmark, the reasons must be explained along with proposed improvement measures. An evaluation report should not merely focus on calculations or fail to meet relevant standards. The source of benchmarking data should be authoritative sources – energy consumption data by industry published by the National Bureau of Statistics, energy efficiency benchmarking reports issued by industry associations, and operational data from similar advanced installations. The evaluation of the energy efficiency level of major energy-consuming equipment provides direct feedback from energy assessment on equipment selection. For general energy-consuming devices such as motors, transformers, fans, water pumps, and compressors, the state imposes mandatory energy efficiency standards. The energy assessment report needs to list in detail the main energy-consuming equipment used in the project, indicating whether their energy efficiency levels meet the energy conservation assessment criteria or the specified energy efficiency limits. It is necessary to determine at the energy assessment stage whether high-energy-consuming, outdated equipment falls under the category of equipment to be phased out or restricted, and whether it can be used in new projects – one cannot wait until equipment procurement time to discover that the selected model does not meet the requirements of the energy assessment. The justification of energy-saving measures is the value of the energy assessment report. Energy conservation is not something that can be accomplished by simply writing a few pages and submitting them; it must be truly implemented in engineering design. From the optimization of the heat exchange network in the process package, to the use of high-efficiency motors and variable frequency drives in equipment selection, to the recovery of steam condensate and the utilization of waste heat – these energy-saving measures should have been technically evaluated during the process package and preliminary design stages. The environmental impact assessment report needs to present them systematically and quantify the energy-saving effects achieved. The feedback from capability assessment on engineering design is multifaceted. The energy-saving measures and energy efficiency targets promised in the energy assessment must be implemented one by one during the subsequent detailed design and equipment procurement. For example, if the evaluation report states that \"heat pump distillation should be used instead of conventional distillation to reduce steam consumption,\" then during the detailed design phase, the distillation tower and compressor configurations must be designed according to the heat pump distillation scheme; it is not acceptable to switch back to conventional distillation at the time of procurement. The energy assessment report states that “a motor with Class 1 energy efficiency should be selected”; therefore, the procurement specification should clearly specify that the energy efficiency class of the motor must be no lower than Class 1. After commissioning, the energy conservation supervision department will conduct inspections and evaluations by comparing the energy assessment report with the actual operational data; what has been promised must be fulfilled. Furthermore, the calculation and reference of energy consumption data in the evaluation report should be consistent with the relevant data in the feasibility study report. If there is a significant difference between the energy consumption data from the feasibility study phase and those from the energy assessment phase, it is necessary to explain the reasons for this difference and the basis for making corrections. The same set of data appears in different versions across various approval documents, which may be questioned during subsequent reviews. II. Soil and Water Conservation: A soil and water conservation plan is a specialized plan submitted to the water resources authorities in order to address potential soil erosion that may occur during the project construction phase. If a project involves significant earthwork and activities that disturb the surface such as excavation and filling, it is necessary to prepare a soil and water conservation plan and submit it for approval. Many people think that soil and water conservation is something to worry about only during the construction phase, and not during the design phase. This understanding is incorrect. The soil and water conservation plan must be prepared and approved before the project begins; otherwise, a construction permit cannot be obtained (this requirement varies from place to place). Moreover, many elements of the soil and water conservation plan—such as earthwork balance, design of drainage ditches, and location of sedimentation tanks—affect the general layout design and vertical arrangement directly. If the requirements of soil and water conservation measures are not taken into account during the detailed design phase, it becomes difficult to make any changes later on during construction, when it turns out that there are conflicts between water diversion ditches and underground utility networks, or that the location of sediment traps is obstructed by utility tunnels. The core elements of the soil and water conservation plan include: an investigation into the current status of soil erosion in the location of the project, a prediction of the amount of soil erosion that may occur as a result of construction, an analysis of soil and rock volume balance, plans for the removal and storage of topsoil, and detailed designs for temporary or permanent protective measures such as drainage ditches, sediment traps, and retaining walls. The prediction of soil and water loss is the basis for formulating soil and water conservation plans. Based on factors such as topography and landforms, soil types, rainfall intensity, and the area affected by construction activities, the amount of soil erosion that may occur during construction is predicted. This forecast serves as the basis for determining the scale and investment required for protective measures—the greater the amount of loss, the more robust these measures must be ； With low loss, the protection scheme can be appropriately simplified. Soil and rock mass balance analysis is a component of soil and water conservation plans that is directly related to the general layout design. During construction, determine how much soil and rock will need to be excavated and filled, where the excess soil and rock should be taken, and whether it is necessary to establish a waste disposal site. Earthwork balance requires calculating not only the total volume, but also its temporal distribution—which phases involve more excavation and which involve more backfilling, as well as whether the location and capacity of temporary stockpiles align with the construction schedule. Projects where cut-and-fill balance is well managed can significantly reduce the costs associated with transporting excess soil away and sourcing soil for backfilling, while also minimizing the sources of soil erosion. The vertical design of the general layout and the earthwork balance in the soil and water conservation plan should be considered together; proper optimization of the vertical elevations can reduce the amount of earthwork required, thereby lowering the risk of soil erosion and the costs associated with soil and water conservation measures. Topsoil stripping is an important environmental measure prior to construction. The surface soil in the construction area is rich in organic matter and a local seed bank; burying or discarding it directly represents a waste of land resources. The topsoil, after being removed, should be stored separately for land reclamation or greening after the construction is completed. The location, capacity, and protective measures for the topsoil storage area—such as covering it with protective nets and installing temporary drainage ditches—must all be specified in the soil conservation plan. Cut-off drains and sedimentation basins are the core of soil and water conservation measures. During construction, the exposed soil generates large amounts of sediment when washed by heavy rains. Without a drainage and sediment control system, this sediment flows directly into nearby rivers or farmlands, potentially affecting areas far beyond the construction boundary. The alignment of the drainage ditches, their cross-sectional dimensions, and the calculation of the catchment area; as well as the volume of the sedimentation tanks and their cleaning cycle – these parameters need to be determined based on the local intensity of rainfall and the catchment area. The relationship between temporary water diversion facilities and permanent drainage systems also needs to be carefully considered during the design phase – it must be decided whether the temporary water conservation facilities will be removed after construction is completed or transformed into permanent facilities, as these two options involve different investment requirements and construction schedules. It is recommended to initiate the coordination between the soil and water conservation plan and the general layout design at the planning stage. The layout plane in the vertical design of the general plan and the drainage system in the soil conservation plan share the same design logic: both are aimed at ensuring the orderly drainage of rainwater and preventing erosion. If the general layout and soil and water conservation work are carried out by separate teams with no communication between them, the resulting drawings are likely to be inconsistent. A better approach is to, after the overall layout plan is finalized, provide this layout to the unit responsible for soil and water conservation planning as input data; the soil and water conservation plan will then develop protection measures based on that layout, ensuring that the design data and boundary conditions on both sides are consistent. III. Commonalities between the two tasks: Energy conservation assessment and soil and water conservation may seem to be two entirely different fields, but they share many commonalities in terms of project management logic. They are all prerequisites that must be met before the project begins. If the evaluation fails, a construction permit cannot be obtained ； Without approval of the soil and water conservation plan, it’s also impossible to obtain a construction permit. In the project schedule, the preparation and approval cycles for these two tasks must be considered as separate critical path milestones, and cannot be overshadowed by the simplistic assumption that work can begin once it has been designed. The preparation and evaluation cycle for energy assessment usually takes 1 to 3 months, depending on the project’s energy consumption level and the local approval process efficiency. The preparation and review of soil and water conservation plans also take approximately 1 to 3 months. All must be advanced in tandem with the main project design, with mutual feedback between them. The energy-saving measures proposed in the evaluation process need to be reflected in the equipment selection – such as using high-efficiency motors, variable frequency speed control, and waste heat recovery. The water retention measures proposed in the soil and water conservation plan need to be incorporated into the overall vertical design – namely, the route of the drainage ditches and the location of the grit chambers. Coordinating efforts during the engineering transition phase is much more efficient than assigning tasks separately and working in isolation. They are all dynamically updated tasks. The energy assessment report is prepared during the scheme design phase based on preliminary equipment selections; once the equipment models are finalized in the detailed design phase, the energy consumption data needs to be verified and updated. The soil and water conservation plan is prepared during the planning stage based on the preliminary layout and earthwork estimates; once the layout and vertical design are finalized in the detailed design stage, it still needs to be reviewed. If there are significant discrepancies between the data from the detailed design phase and those during the preparation phase, it is necessary to promptly communicate with the preparing party to assess whether a supplementary report is required or if the design needs to be adjusted. IV. Some insights: First, the value of energy conservation assessments does not lie in “passing the review”, but in “forcing optimizations”. The core output of a energy assessment report is not just the approval document, but also a list of energy-saving measures. Each energy-saving measure on this list must be implemented one by one during the subsequent detailed design and equipment procurement. The process of energy efficiency assessment is essentially a systematic review of a project’s energy utilization efficiency – to determine whether there are any unnecessary losses of energy, whether there is waste heat that can be recovered, and whether pumps and fans of oversized sizes are being used. It is much more cost-effective to address the issues identified during the detailed design phase than to make modifications after the construction is complete. Second, soil and water conservation plans cannot be prepared until after the construction bidding process is completed. In many projects, it is common to start preparing the soil and water conservation plan only after the detailed design is completed and the construction team arrives on site – by that time, the general layout has already been determined as well as the vertical design, so the soil and water conservation plan merely adapts passively to the existing designs. If the preparation of soil and water conservation plans is initiated at the design stage, and soil and water conservation experts are involved in the review of the general layout and vertical design, they can offer optimization suggestions from a soil and water conservation perspective – such as adjusting vertical elevations to reduce the amount of earthwork required, or optimizing drainage systems to minimize the workload associated with constructing drainage ditches. It costs almost nothing to adopt these suggestions during the design phase; it’s too late to make changes once construction begins. Third, both specialized tasks require the basic principle of \"clear data sources.\" The energy consumption data used in the evaluation come from the utility consumption tables and heat balance calculations in the process package, while the earthwork data in the soil conservation plan are derived from the vertical design and earthwork calculations of the general layout. If the source data is inaccurate or the data across multiple files is inconsistent, it will raise doubts during approval. Therefore, before submitting the energy assessment report and the soil and water conservation plan, it is necessary to conduct a self-check for data consistency – to ensure that the steam consumption figures stated in the energy assessment are consistent with those in the process package, and that the quantities of earthwork and the results of the site layout calculations in the soil and water conservation plan are consistent – in order to avoid rejection during the approval process. Preview for the next issue: Issue 69 – Design review systems: HAZOP analysis and SIL classification. The topics on energy efficiency assessment and soil and water conservation have been covered. Starting from the next issue, we will discuss the design review system in the engineering transition phase over three issues. Let’s first discuss the application of HAZOP analysis and SIL grading in the detailed design phase – what are the differences from HAZOP during the process package stage, what is reviewed in the HAZOP process at the detailed design stage, and how are 3D model reviews and constructability reviews organized. To be continued in the next issue.