Questions about container operating temperature and design temperature
Thread Content
A pressure vessel produced by our unit had internal insulation. The drawings were sent to the Quality Inspection Bureau and they said there was a problem with the design temperature. The design temperature on the drawing is 300 degrees and the operating temperature is 350-450 degrees. The steel plate cannot reach the operating temperature. Is there a problem with the drawings designed by the design institute?
I think it is unreasonable. How can the operating temperature be higher than the design temperature? And you said that the steel plate cannot reach the operating temperature. Do you think that the material selection is wrong? Which design institute? Generally, design institutes will not have such a problem!
Personally, I think it's okay. Because the internal insulation of the equipment should actually be a heat insulation layer, that is, the temperature inside the cavity is relatively high, but after passing through the heat insulation layer, the temperature on the shell cannot reach such a high temperature. Pay attention to the definition of design temperature: The metal temperature of the component set under normal operation of the container (the average temperature along the metal section of the component). So the original poster’s value is still feasible.
The poster said that there is insulation inside. We have designed a piece of equipment before. The shell material is 16MnR and the inside is filled with refractory bricks. The operating temperature reaches about 550 to 600 degrees. This is also feasible, and the material is very economical, because the price of heat-resistant steel is much higher, and heat treatment is required. Of course, this must ensure that the metal temperature of the shell is within the allowed operating temperature range.
It should be said that the design of the design institute mainly depends on the effect of internal insulation, and the temperature must be controlled.
The design temperature cannot be lower than the operating temperature (for temperatures above zero), but according to the original poster, it seems that: The operating temperature inside the insulation material is 350 to 450 degrees, and the temperature of the outer shell should be lower than 300 degrees due to the insulation layer. I think it would be better to write it like this: There is a design temperature in the insulation material, which is higher than 450 degrees. This must be noted. ； There is a design temperature of 300 degrees in the shell, and a range of operating temperature, such as 0 to 300 degrees. In this way, there will be no problem of wording.
Internal insulation, the temperature drops when it reaches the shell, and it is reasonable for the design temperature to be lower than the operating temperature
There should be no problem with the design of this design institute. The problem is that the operating temperature of 350-450 degrees mentioned by the poster should be the temperature in the furnace and not the operating temperature of the container. Due to proper insulation, the metal temperature of the container may be lower than 300 degrees, so the design institute took the design temperature as 300 degrees. In fact this considers the definition of container metal temperature. This post was last edited by whsjy2002 on 2009-3-25 09:30 ]
Everyone feels that the maximum temperature reached by the external shell should be indicated in the technical characteristics table or technical requirements, so there should be no problem.
There is no problem with the design drawings. The problem is that the Quality Supervision Bureau personnel did not clearly understand the concepts of design temperature and operating temperature. The design temperature refers to the set metal temperature of the component (the average temperature along the metal section of the component), while the operating temperature (or working temperature) on the drawing refers to the working temperature of the medium. Since the equipment has internal insulation, the metal temperature of the cylinder wall is lower than the medium temperature.
The design temperature in the pressure vessel drawings should include the body design temperature and the jacket design temperature. Just check with the design institute. It is impossible for the operating temperature to be higher than the design temperature.
For equipment with internal insulation layers, the design temperature of the metal shell can be lower than the normal operating temperature. Just be aware: 1) Structurally ensure that there are no penetration gaps in the insulation layer, otherwise the metal shell must be considered based on the maximum operating temperature. (In the past, when the conversion furnace used aluminum silicate fiber insulation, there was a problem of overheating of the metal shell.) 2) The design temperature of the internal parts should refer to the maximum operating temperature. For operating temperatures of 350C to 450C, it is better to use chromium-molybdenum steel.