Regarding the identification of combined devices
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According to GB50160, the necessary condition for a combined unit is: 1. Two or more large independent units must be arranged in a compact manner together； 2. Direct feeding between devices ； 3. No intermediate raw material storage tanks provided for major overhauls ； 4. Startup/shutdown and maintenance are carried out simultaneously. Point 1 is easy to understand and unambiguous. Regarding Point 2: The output product of Device A serves as the raw material for Device B. If the materials produced by Device A are first fed into the intermediate tank array of Device A, and then pumped into Device B, does this count as direct feeding between devices? Regarding point 3: Since there is no intermediate raw material storage tank designated for major maintenance, is it permissible to have a raw material storage tank for use during startup and shutdown operations? Everyone is welcome to discuss!
It seems that it’s possible to set up raw material tanks
This post was last edited by WiseMind on 2021-8-30 at 15:56. Direct feeding between units: Normally, the material produced by Unit A is directly fed into Unit B. At the same time, there are bypass valves that allow the material to be directed to the intermediate tank farm. During normal operations, the material flows directly from Unit A to Unit B; however, when there are fluctuations in load, the raw materials are directed to the raw material storage area. If the material produced by Unit A goes into the intermediate tank array of Unit A, and then is pumped into Unit B, isn’t this completely unnecessary?
The integrated plant must have a raw material tank farm.
If the storage tank group of Unit A is located between the two, the control system becomes simpler and management easier; there’s no need for any extra measures :lol
From a practical production standpoint, it is essential to have tank farms (or tank areas) to ensure production balance and material circulation among various units. However, many designers at engineering firms currently lack any practical production experience; they focus solely on drawing preparation, constantly citing regulations and applying them rigidly, resulting in numerous illogical or nonsensical designs.
One of the design bases for design institutes is “specifications”; it’s not based on assumptions.
In combined systems, it is not prohibited to have intermediate material buffer tanks between the upstream and downstream unit modules; rather, there are certain restrictions on the residence time of the material in these buffers or on their appropriate volume – generally, this should not exceed a buffer cycle of one day and night, or a shorter cycle with a corresponding appropriate volume. This “reasonable volume” is determined by experts in safety, fire protection, and other relevant fields, based on their own experience as well as factors such as the size of the installation. For oil refining and petrochemical plants with an annual processing capacity of several million or tens of millions of tons, the volume of the intermediate material buffer tanks required to accommodate a few hours’ worth of buffer time is already quite large ； The volume of the intermediate buffer tank in the buffer cycle of small-scale fine chemical plants over a 24-hour period is relatively limited. Additionally, the installation of parking and material return chutes, etc., generally does not affect the status of the facility as an integrated plant, provided that the rationality of their volume is justified. Due to differences in the level of expertise among review experts in various regions, some of them are very pedantic; they become uncomfortable as soon as they see terms such as “intermediate storage tank” and “storage period”, and start looking for faults ； Terms such as “intermediate buffer tank” and “buffer cycle” or “residence time” are relatively easier to accept. Therefore, the equipment names for the material intermediate tank also need to be chosen carefully.
It’s only natural for design institutes to follow the specifications, but they should be applied correctly. There are many cases where the specifications are rigidly adhered to without any adaptation. Many of the points mentioned earlier aren’t exhaustive, by the way :lol
During a previous training session on GB50160, I asked a teacher from Luoyang Institute, and the teacher said, “Isn’t it up to the designer to decide whether it constitutes a combined unit?” If the designer says so, then it is so. ”It is estimated that people from Luoyang Institute might say such things, but it would be hard for others to accept them.
Standards and specifications are established by ** or industry associations; designers simply have to follow them. When there is room within the standards and specifications, designers can make adjustments; when these standards and specifications are rigid requirements, designers must comply with them as stipulated. There is no such thing as mechanical application.