[Q&A Question 168] 2017.06.17
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This post was last edited by 955559 on 2017-7-21 23:10. [Q&A Question 168] June 17, 2017: What are the factors that limit the heat intensity on the surface of furnace tubes? The reference answers can be seen after replying; points will be awarded for identifying the key points. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) (1). As the heat intensity on the surface of the furnace tubes increases, the temperature of the tube walls also rises. The extent to which the tube wall temperature increases is determined by the lifespan of the tubing. Additionally, as the tube wall temperature rises, more heat is transferred into the tubes, increasing the likelihood that the oil inside them will reach its coking threshold. (2) Uneven heat transfer within the furnace chamber is another factor that prevents the heat intensity on the surface of the furnace tubes from being too high. Scoring criteria: 2 Wealth points for incorrect attempts; 3–8 points for *incomplete* answers. 10 Wealth points for correct answers, provided along with a detailed explanation; 15–20 Wealth points if the answer is correct but lacks sufficient details. Please score according to these criteria. Note: If there are editing records after answering, only points will be awarded to those who participated. For continuous malicious spamming, 2 points will be deducted each time, with no upper limit. Pure numbers, pure emojis, or random letters that have nothing to do with the answer are all considered malicious spamming; points will start to be deducted after three warnings. 2017 Q&A Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html
As the heat intensity on the surface of the furnace tube increases, the wall temperature of the tube also rises. The extent to which the wall temperature increases is determined by the lifespan of the tube material. Additionally, as the wall temperature rises, the amount of heat that enters the tube increases accordingly, and there is a possibility that the oil inside the tube may exceed its coking threshold
(1). As the heat intensity on the surface of the furnace tube increases, the wall temperature of the tube also rises. The extent to which the wall temperature increases is determined by the lifespan of the tube material. Additionally, as the wall temperature rises, the amount of heat that enters the tube increases accordingly, and there is a possibility that the oil inside the tube may exceed its coking limit. (2) The uneven heat transfer within the furnace chamber is also a factor that prevents the heat intensity on the surface of the furnace tubes from being high.
1. An increase in the thermal intensity on the surface of the furnace tubes leads to a corresponding rise in the temperature of the furnace walls. As a result, the oil inside the tube walls tends to coking and decomposing, causing localized overheating that can damage the furnace tubes； 2. The uneven heating caused by factors such as the distance between the furnace tube and the burner inevitably leads to varying heat intensities on the surface of different parts of the furnace tube.
It is restricted by the following factors: a. As the heat intensity on the surface of the furnace tubes increases, the temperature of the furnace walls also rises, causing the oil inside the tube walls to coking and decompose, which leads to local overheating and damage of the furnace tubes； b. The uneven heating caused by factors such as the distance between the furnace tube and the burner also inevitably leads to varying heat intensities on the surface of different parts of the furnace tube. Therefore, when increasing the average surface heat intensity of the furnace tubes, it is necessary to take into account the risk of extremely high local surface heat intensities. Based on the above, attention must be paid to the uniformity of the surface heat intensity of the furnace tubes in order to enhance the furnace’s processing capacity. The following measures can be adopted during design and operation: a. Increase the number of furnace tubes that are exposed to radiation on both sides ； b. Add radiation walls ； c. Add auxiliary burners, such as burners installed in the middle of the furnace body ； d. In operation, strive for as many burners as possible, with short flames and uniform flame heights.
(1) As the heat intensity on the surface of the furnace tube increases, the wall temperature of the tube also rises. The extent to which the wall temperature increases is determined by the lifespan of the tube material. Additionally, an increase in wall temperature leads to an increase in the heat transferred into the tube, raising the possibility that the oil inside the tube will exceed its coking threshold； (2) The uneven heat transfer within the furnace chamber is also a factor that prevents an increase in the heat intensity on the surface of the furnace tubes
(1) As the heat intensity on the surface of the furnace tube increases, the wall temperature of the tube also rises. The extent to which the wall temperature increases is determined by the lifespan of the tube material. Additionally, as the wall temperature rises, more heat is transferred into the tube, increasing the likelihood that the oil inside the tube will exceed its coking threshold. (2) The uneven heat distribution within the furnace chamber is another factor that prevents the heat intensity on the surface of the furnace tube from being too high.
(1) An increase in the heat intensity on the surface of the furnace tubes leads to an increase in the wall temperature of these tubes. The extent of this temperature increase is determined by the service life of the tube material. Additionally, as the wall temperature rises, more heat is transferred into the tubes, increasing the likelihood that the oil inside them will reach its coking threshold. (2) Uneven heat transfer within the furnace chamber is another factor that prevents an increase in the heat intensity on the surface of the furnace tubes.
Furnace tube material, feed medium and recycled hydrogen, hydrogen-to-oil ratio
(1) Heat load (2) Furnace temperature (3) Furnace heat intensity (4) Surface heat intensity of the furnace tubes (5) Thermal efficiency of the heating furnace (6) Flow rate and pressure of the medium inside the furnace tubes