Problems with the exhaust gas incineration process flow
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Our company has built a new 3.5t/a sulfur recovery unit. While reviewing the drawings, I am unsure about the process that occurs after hydrogenation and heat exchange of the exhaust gases; I would appreciate everyone’s advice. After heat exchange in the steam generator, the exhaust gas undergoes hydrogenation; it then enters the exhaust gas quenching tower, followed by the exhaust gas absorption tower, and finally the incinerator. This process is easy to understand. However, before the exhaust gas reaches the exhaust gas absorption tower, there is a DN500 branch pipeline that leads directly to the incinerator. What is the purpose of designing this pipeline? Is it used by directly feeding exhaust gas into the incinerator during maintenance of the exhaust gas absorption tower or exhaust gas quenching tower, or for some other purpose? What is the normal operating procedure? Please share your insights.
3.5t/a or 35,000t/a? Does the DN500 branch pipeline leading directly into the incinerator go before the quench tower or before the absorption tower? It is usually located before the quench tower and is used to handle fluctuations in the Claus unit as well as for exhaust gas removal.
Thank you! Wrong, it’s 35,000 t/a. The DN500 branch pipeline leading directly into the incinerator is located in front of the quench tower. But one thing remains unclear: when the Klaus unit fluctuates, the exhaust gases can go directly from the exhaust gas heater outlet to the incinerator; there is no need for them to enter the hydrogenation reactor. Is this done to protect the catalysts inside the hydrogenation reactor? Please give me some advice.
This post was last edited by river-king on 2010-12-24 at 19:15. The purpose of this pipeline is to discharge the recycle gas from the hydrogenation unit into the chimney during the heating up of the hydrogenation furnace and the sulfidization of hydrogenation catalysts; if this gas enters the solvent system, it will cause the solvents to oxidize and deteriorate. At this stage, the Klaus flue gas bypass is also discharged into the chimney, and the two units are in isolation.
Reply to 4# river-king: Thank you to the person above for sharing their insights.
If it is 3.5 wt/a, it seems that a DN500 pipeline shouldn’t be necessary; presumably a DN300 pipeline will suffice, as this line is used for pressure control in the startup cycle. Personally, I think it shouldn’t go directly into the incinerator, as if each section of the exhaust gas were sent to the incinerator separately, it could lead to uneven combustion; this pipeline should be located near the outlet of the absorption tower.
It is indeed a DN500 pipeline, running from the emergency cooling tower to the incinerator; there are safety valves and control valves before it reaches the incinerator
Hydrogenation of exhaust gases is not 100% effective; inevitably, some elemental sulfur remains unhydrogenated. Over time, this can accumulate inside the scrubber tower, increasing the pressure difference within it, which requires the tower to be shut down for maintenance
Reply to 1# Drunk in the Setting Sun: This line is likely the pressure control line for the startup cycle; it is used primarily for controlling pressure during processes such as furnace heating, pre-vulcanization, and temperature raising before startup. To prevent the process gases from contaminating the absorbent solvents, these gases are sent through this line to the tail furnace. Once the Claus off-gases are introduced, the flow is directed to the quench tower to enable normal operation, after which this line is disabled.
The answer above is correct; for example, when the temperature in a hydrogenation reactor rises during circulation, if the system pressure becomes too high, pressure can be released through this interlock mechanism for safety purposes