External heat extraction and internal leakage in catalytic cracking: phenomena and treatment methods
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This post was last edited by jbcyf on 2011-12-25 08:03. External heat removal and internal leakage in catalytic cracking: symptoms and treatment methods. I would like to thank that fellow user for the good suggestions; thanks in advance
1. The water supply volume and steam production are significantly mismatched; the steam output is markedly insufficient. 2. The temperature distribution (radial temperature) in the regenerator is uneven, with large fluctuations in temperature; in severe cases, the temperature drops. 3. The radial temperature distribution in the external heat exchanger is uneven, resulting in a drop in temperature. 4. There is significant loss of catalyst, an increase in fine powder, and the fine powder develops sharp edges. Solution: Eliminate each tube one by one and cut out the leaking tubes
Phenomenon: (1) The water supply flow rate is greater than the steam generation rate, or the difference increases； (2) The water level in Tank 501 shows a sudden downward trend, or it is difficult to maintain it even by increasing the water supply volume ； (3) There is a tendency for the steam pressure to drop suddenly ； (4) There is a sudden and significant increase in regenerator pressure, along with a significant drop in the temperature of the external heat exchanger ； (5) The flue gas from the regenerator chimney appears as a white, thick mist. Reason: (1) Uneven heating of the heat exchange tubes, resulting in local stress concentration in the tubes ； (2) The operating temperature varies greatly, resulting in intense thermal expansion and contraction. (3) Certain areas become significantly thinner due to severe erosion by the catalyst ； (4) Poor water quality, scaling inside the pipes, and blockages caused by debris lead to too low flow rates or interruptions in water flow, as well as localized overheating of the pipes ； Treatment: (1) Quickly close the upper and lower slide valves of the external heat exchanger, especially the upper slide valve, and open the flue gas back-dilution valve. (2) Quickly inspect the broken pipe using the cut-off method (by closing the inlet and outlet valves of the sleeve) ； When the temperature rises while the regeneration pressure decreases, it indicates tube cracking and removal. (3) Maintain the proper water level, contact the power boiler in a timely manner, and work closely together to make every effort to keep it at 3. 05Mpa and 1. 0Mpa steam pressure and temperature ； (4) Reduce the steam load for the medium-pressure turbines in the four units as necessary ； (5) After tube rupture resection, adjust the operations promptly to strictly prevent overheating.
Let me add more details on how to do it specifically – which one is leaking. It is said that a stethoscope can be used to remove it, but this is something that ordinary people cannot do. Another method is to test each one one by one; internal and external operations need to be carried out in coordination! Close the pipeline valve; if the pressure gauge continues to rise, there is no problem. The operator inside should check whether there is any change in the pressure of the regenerator! No change, no leaks; open it in time to prevent pressure buildup! If the pressure gauge drops, it indicates a problem with this pipe; the operator should check whether the regeneration pressure has decreased as well!
The pressure in the regenerator rises sharply, the bed temperature drops drastically, there is severe catalyst loss, and the amount of steam delivered by the heat exchanger decreases... The solution is to promptly and accurately determine the cause of the accident, immediately remove the leaking heat exchanger, adjust the ratio of raw material to slag, and reduce the feed to the reactor……