Unsourced material may be challenged and removed. The general objective of a chemical plant is to create new material wealth via the chemical or biological plant engineer’s handbook pdf and or separation of materials. Chemical plants use specialized equipment, units, and technology in the manufacturing process. Tools have been developed for converting a base project cost from one geographic location to another.
The same chemical process can be used at more than one chemical plant, with possibly differently scaled capacities at each plant. Also, a chemical plant at a site may be constructed to utilize more than one chemical process, for instance to produce multiple products. In addition to feedstocks for the plant as a whole, an input stream of material to be processed in a particular unit can similarly be considered feed for that unit. Output streams from the plant as a whole are final products and sometimes output streams from individual units may be considered intermediate products for their units. However, final products from one plant may be intermediate chemicals used as feedstock in another plant for further processing. For example, some products from an oil refinery may used as feedstock in petrochemical plants, which may in turn produce feedstocks for pharmaceutical plants. Such batch production may be repeated over again and again with new batches of feedstock.
Batch operation is commonly used in smaller scale plants such as pharmaceutical or specialty chemicals production, for purposes of improved traceability as well as flexibility. During usual continuous operation, the feeding and product removal are ongoing streams of moving material, which together with the process itself, all take place simultaneously and continuously. Steady state means that quantities related to the process do not change as time passes during operation. Continuous operation is more efficient in many large scale operations like petroleum refineries. Although some units may operate at ambient temperature or pressure, many units operate at higher or lower temperatures or pressures. For example, chemical reactors often have stirring for mixing and heating or cooling to maintain temperature. Storage tanks commonly have level indicators to show how full they are.
There may be structures holding or supporting sometimes massive units and their associated equipment. There are often stairs, ladders, or other steps for personnel to reach points in the units for sampling, inspection, or maintenance. In plant design, typically less than 1 per cent of ideas for new designs ever become commercialized. During this solution process, typically, cost studies are used as an initial screening to eliminate unprofitable designs. If a process appears profitable, then other factors are considered, such as safety, environmental constraints, controllability, etc. Chemistry information obtained is then used by chemical engineers, along with expertise of their own, to convert to a chemical process and scale up the batch size or capacity.
From data and operating experience obtained from the pilot plant, a scaled-up plant can be designed for higher or full capacity. The streams and other piping are shown as lines with arrow heads showing usual direction of material flow. In block diagrams, units are often simply shown as blocks. Process flow diagrams may use more detailed symbols and show pumps, compressors, and major valves.
Likely values or ranges of material flow rates for the various streams are determined based on desired plant capacity using material balance calculations. In the plant design, the units are sized for the maximum capacity each may have to handle. Similarly, sizes for pipes, pumps, compressors, and associated equipment are chosen for the flow capacity they have to handle. Additional piping lines for non-routine or alternate operating procedures, such as plant or unit startups and shutdowns, may have to be included. If pneumatically or hydraulically actuated valves are used, a system of pressurizing lines to the actuators is needed.
Any points where process samples may have to be taken should have sampling lines, valves, and access to them included in the detailed design. For flexibility, a plant may be designed to operate in a range around some optimal design parameters in case feedstock or economic conditions change and re-optimization is desirable. In addition, operators in the control room can control various aspects of the plant operation, often including overriding automatic control. Process control with a computer represents more modern technology. Based on possible changing feedstock composition, changing products requirements or economics, or other changes in constraints, operating conditions may be re-optimized to maximize profit.
As in any industrial setting, there are a variety of workers working throughout a chemical plant facility, often organized into departments, sections, or other work groups. For example, petroleum commonly comes to a refinery by pipeline. Pipelines can also carry petrochemical feedstock from a refinery to a nearby petrochemical plant. Large quantities of liquid feedstock are typically pumped into process units. Smaller batches of feedstock may be added from drums or other containers to process units by workers. In addition to feeding and operating the plant, and packaging or preparing the product for shipping, plant workers are needed for taking samples for routine and troubleshooting analysis and for performing routine and non-routine maintenance.
Non-routine maintenance can include investigating problems and then fixing them, such as leaks, failure to meet feed or product specifications, mechanical failures of valves, pumps, compressors, sensors, etc. An MSDS for a certain chemical is prepared and provided by the supplier to whoever buys the chemical. The actual production or process part of a plant may be indoors, outdoors, or a combination of the two. Large modular skids are especially impressive feats of engineering. A modular skid is built including all of the modular equipment needed to do the same job a traditional stick-build plant may perform. A modular skid build results in a higher functioning end product, as less hands are required in the onsite setup of the modular skid process unit, resulting in minimized risk for mishaps.