Could everyone help me check whether this storage tank I designed is reasonable?
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Yesterday I designed a storage tank for use in quoting; it is meant to store liquefied propane and butane. I had only designed air storage tanks before, and this time I approached the design in a manner similar to that of air storage tanks. Before going to bed last night, I felt a bit uneasy about it, so I decided to learn from others. Design parameters: Operating pressure 2.1 MPa; design pressure 2.5 MPa. Operating temperature 50°C; design temperature 60°C. Medium: Liquefied propylene butane; density under operating conditions 560 Kg/M3. The customer requires a storage capacity of over 500 Kg. Corrosion allowance: 2 mm. Material for pressure-bearing components: Q345R. The tank is of vertical type, with a cylinder diameter of DN800X10 and a length of 1000 mm. The head is of type EHA800X10. Manholes are of type HG20518 DN400-2.5, using supported brackets of type A1 according to JB/T4712.4-2007. Since this is a quotation, I have only taken into account these heavier components, which has resulted in an upward adjustment of the total cost. What worries me is that the design for storing air should be different from that for storing liquefied gas; we have never done this before. I hope all fellow sailors can offer me some guidance; thank you. This post was last edited by matinglude on 2009-3-13 09:01]
Since you have no experience with propylene-butane media, how were your design pressure and design temperature determined?
Is the DN400 manhole too small?
When determining the volume, the filling amount per unit volume must be taken into account.
Back to the 2nd floor: the weight of the safety valve is very small, and it is generally not taken into account in the weight calculation for quotations at our company. Back to floor 3: the operating temperature and operating pressure are provided by the customer. Back on the 4th floor: the diameter of the cylinder is only DN800; why is the manhole chosen as 400, making it too small?
In short, liquefied gas cylinders must be designed in accordance with the relevant regulations of capacity standards.
Selection shall be made in accordance with the provisions in Table 3-1 or Table 3-3 of the prison regulations
Should issues such as insulation design and filling factor also be considered?
1. With a filling coefficient of 0.9, the volume of the storage tank will not meet the user’s requirements. 2. The thickness of the head is set at 12 mm, taking into account the thinning due to molding. 3. The equipment should undergo overall heat treatment after welding. 4.100% non-destructive testing. 5. Conduct a airtightness test. 6. If the hydrogen sulfide content is greater than 100 mg/L, ultrasonic testing should also be carried out on the sheets. My personal views are for reference only.
When storing liquefied gases, considerations must be given to level gauges, thermometers, safety valves, the filling coefficient (maximum filling amount), flange types, and gaskets. Such containers should be classified as category three; they require heat treatment, and purging must be carried out prior to storage.
I think the manhole is actually too large; it exceeds the allowable opening size of 150. The pressure area method should be used for calculations. Could two handholes be installed instead? Regarding liquefied gas, I couldn’t find any relevant information – there are specific requirements regarding the pressure and temperature of liquefied gases
Thank you to those on floors 5, 6, 7, and 8 for helping me check the capacity regulations – it belongs to a fixed-pressure vessel, and a filling factor of 0.9 should be used; I hadn’t considered this before. Thanks also to the person on floor 9 regarding insulation: with a working temperature of 50°C and a design temperature of 60°C, is insulation necessary at these temperatures? I know little about this aspect. Could you introduce it to me? Or recommend some materials on this topic. Thank you. The filling coefficient is 0.9, and the density is 560 Kg/M3; it is required to be able to hold 500 Kg. Using the volume calculation formula, a volume of 1 M3 is needed. My original design had an insufficient volume. May I ask again, where in that standard are points 3, 4, and 6 mentioned? Thank you, I’ve learned it. Thank you, Floor 11. What is replacement processing? I haven’t heard of it; I’ve only been working for two years and lack experience. Regarding whether it belongs to category 3 containers, the relevant regulations state: 1. Medium-pressure containers (only for media with extremely high or high toxicity); 2. Medium-pressure storage containers. These containers do not meet the requirement that the PV value be greater than 10 MPa·m3. I am not sure whether propane and butane are considered media with extremely high or high toxicity. Thank you, Floor 12. Refer to Table 3-6 for the capacity calculation: for 500＜DN≤1000, use one manhole of diameter φ400, or an oblong hole with dimensions 400x250 or 380x280; or use two handholes, each with a diameter of φ100, or oblong holes with dimensions 100x50. For Di≤1500 and d≤1/2Di with d＜520, the requirements are indeed not met. The poster is right – use the pressure area method or install two handholes. What are the terms for liquefied gas pressure and temperature? I don’t know about the sea right now; I hope to be able to learn it*. Thank you to floors 13 and 14
The manhole in question uses the HG20518 standard, but HG20518 refers to the design principles for mechanical transportation in the chemical industry as specified in HG20518-1992 – the poster must have made a mistake.
Return to the 11th floor. According to the container regulations, this container should be classified as a Class II container; although it is used for storing medium-pressure flammable materials, its P.V. value is less than 10 MPa·m3； When designing this container, in addition to the suggestions from the aforementioned parties, it must also meet the requirements specified in Articles 34 to 37 of the \"Regulations on Safety Supervision of Pressure Vessels\".
Reply to the original poster: Point 3: Overall heat treatment after welding is specified in 10.4.1.2 of section 10.4 on page 124 of GB150; Point 4: Sub-clause 3 of Article 85 on page 43 of the ‘Acceptance Regulations’； Point 6: Sub-clause 2 of Article 14 on page 11 of the Compliance Regulations ；
Firstly, the designed volume is indeed too small; obviously, a filling coefficient of 1.0 requires 1 cubic meter, not to mention the filling coefficient for liquefied gas, for which a value of 0.9 can be used. Secondly, 100% flaw detection is definitely necessary. Thirdly, heat treatment is likely not required, as the medium in question is propane and butane in liquid form, rather than a mixed liquefied gas that contains hydrogen sulfide. However, given that modern liquefied gases are not always very pure, it might be advisable to require heat treatment as well. There don’t seem to be any other issues; this is just my personal opinion for reference
Is the medium clear? Propane and butane – they are propane and butane, right? Based on the composition, refer to the saturation vapor and saturation temperature table for the medium, select its saturation pressure at 50 degrees as the maximum operating pressure to determine the opening pressure of the safety valve, and then set the design pressure. However, in the case of a propylene and butane mixture, a design pressure of 1.77 MPa and a design temperature of 50 degrees will suffice. A corrosion margin of 2 mm is selected, and the design parameters are now set. The tank size should take into account a filling factor of 0.9. Based on a rough calculation, if the volume of the tank is underestimated, it would be better to increase the diameter to over 900 mm so that the opening coefficient does not exceed 0.5. Special manufacturing includes heat treatment and 100% radiographic inspection. Others upstairs have already said it, so I won’t repeat it.
I think what you designed is a horizontal tank, right?