For process input streams the choices for identity are:
a) Regular Material Stream,
b) Heat Transfer Agent or
c) Withdrawn from a Supply Storage Unit
Let’s consider now the implications of choosing one of the above choices as the identity of a process input stream.
All input streams are by default assumed this identity of regular material streams. Furthermore, their scope is assumed to be ‘raw material’; in other words, it is assumed that the material on those streams will be consumed (or used up) by the process in order to produce a main product that will bring us revenue. Once a stream’s scope is set as ‘raw material’, then all that remains is to specify the stream’s composition (and process conditions like temperature and pressure) and the price to pay to purchase the material (purchasing price). The price cannot be set directly on the stream (from this or any other interface) but it’s automatically calculated from the purchase price of its ingredients weighted out by each ingredients mass fraction.
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If the weighted average of a stream’s ingredients does not result in a satisfactory value for its purchasing price, consider defining a new stock mixture with the same composition as the input stream and assign it the desired purchase price. Then, replace the composition of the input stream with just one ingredient: the newly defined stock mixture that features your chosen purchasing price. |
The purchasing price of each ingredient is set from the Economics tab of its properties interface (see Pure Component Properties Dialog: Economics Tab for pure components and Stock Mixture Properties Dialog: Economics Tab for stock mixtures). Please note that all input streams designated as ‘raw material’ will add to a special subcategory of the operating cost named appropriately as “Raw Material” (see Operating Cost and Materials Cost).
Note that an input stream identified as ‘Regular Material Stream’ does not necessarily need to be classified as raw material. It could also be classified as:
Cleaning Agent: (e.g. all materials used in a CIP step are automatically designated as ‘cleaning agent’); once a stream is classified as a cleaning agent there will be a special aggregate sum under the materials cost (part of the operating cost) that provides the total for materials used as cleaning agents
Revenue: In some rare cases, the flow of an input streams is dictating the direct revenue for the process. This is almost exclusively the case for waste treatment processes that charge by the rate of effluent stream that comes into the process and ultimately is cleaned up.
Unclassified: If this null designation is assigned, then the amount of this stream is economically neutral: it doesn’t add to operating cost and it is not reflecting process revenue.
Note that the stream’s classification (but NOT the stream’s identity) can also be changed from the Stream Classification Dialog.
Occasionally it is necessary to designate the identity of process input stream as ‘Heat Transfer Agent’ (see Heat Transfer Agents). The implication being that it is drawn from the same source as a heat transfer agent resource that is used for heating or cooling in an operation. For example, we may need to use an input stream that is used as live steam to be injected in a vessel for a fast heating of its contents. The implications of designating the identity of an input stream as ‘Heat Transfer Agent’ are dual:
a) The stream’s composition is locked and matched with the composition of the selected heat transfer agent, and
b) The total consumption amount is NOT added to the Raw Materials subcategory of the operating cost but it is added to the Utilities subcategory (see Operating Cost and Utilities Cost).
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When setting the identity of a process input stream to a ‘Heat Transfer Agent’ the list of choices for agent includes all agents known to the program (i.e. defined in the process file and the heat transfer agent databank) that have a specified material associated with them. Agents that do NOT have an assigned material will be excluded from the list. |
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If you designate the identity of a process input to a heat transfer agent and later proceed to change the material associated with the agent from the process list of registered heat transfer agents (NOT the User database), the change will be forwarded to all such input streams affecting their composition. |
The classification of an input stream as “Heat Transfer Agent” can also be viewed from a central listing of all streams in the Stream Classification Dialog but it cannot be changed there as it requires the changing of its identity and the Stream Classification Dialog does NOT allow for changing the identity of a stream (only its classification if it is NOT tied to its identity).
Storage units are resources defined in a process model that represent either the supply or collection of material without having to specify an actual stream (see Material Storage Units). They can be very convenient for keeping track of special subcategory of material as a source (raw material) since you can view a detail accounting of when and how much that subcategory of material is drawn and by what activity (see Material Supply & Receiving Inventory Charts). For example consider WFI. It may be convenient to define a supply storage unit for WFI and have all input streams that carry WFI to draw from that SU in order to be able to visualize at any time the WFI consumption. Since part of the definition of a supply storage unit is what type of material (pure component or stock mixture) it contains and a classification (e.g. raw material), once a stream’s identity is matched to a supply storage unit, its composition will be locked as well as its classification to match the composition and classification carried by the storage unit definition.
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If you designate the identity of a process input to a supply storage unit and later proceed to change the material associated with that storage unit or its classification, the change will be forwarded to all such input streams affecting their composition and classification. |
The classification of an input stream as “Withdrawn from a Storage Unit” can also be viewed from a central listing of all streams in the Stream Classification Dialog but it cannot be changed there as it requires the changing of its identity and the Stream Classification Dialog does NOT allow for changing the identity of a stream (only its classification if it is NOT tied to its identity).
