Discussion on the heating method for Claus off-gases in sulfur recovery units
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This post was last edited by adsl121 on 2009-12-24 00:41. Since the hydrolysis degree of COS and CS2 decreases as temperature drops, in order to achieve a high sulfur recovery rate, catalysts of conventional type are currently used in most sulfur recovery hydrogenation reactors, with a few exceptions; this requires the temperature of the exhaust gas entering the hydrogenation reactor to be between 280 and 320°C. The exhaust gas temperature from Claus is generally between 120 and 130°C, and the methods used for heating the exhaust gas vary. The commonly used methods in China can be divided into five categories: exhaust gas heaters, on-line reduction furnaces, process gas heat exchange combined with electric heating, flue gas heat exchange, and steam heat exchange. The exhaust composition, raw material consumption, energy consumption, pollutant emissions, and equipment costs vary depending on the different methods of exhaust heating. Please discuss which method of exhaust heating is more suitable
This post was last edited by adsl121 on 2009-12-18 01:30. We use exhaust gas heating; different processes have their own advantages, as well as their disadvantages.
The last edit to this post was made by adsl121 on 2009-12-18 at 01:31. We also use exhaust gas for heating; the amount of off-gas generated in methanol synthesis is large. Our plant can either vent this gas directly into a flare or use it as fuel in sulfur recovery processes, so there is no increase in energy consumption. What about equipment costs? We once burned the gas at a slightly higher temperature in order to recover more sulfur
This post was last edited by adsl121 on 2009-12-18 01:30. I have come across quite a number of devices that use exhaust gas heating furnaces, and these devices make use of the vent gas from such furnaces. This device is not large and the pressure is not high, so there should be no major issues with costs. The device does produce plenty of steam, but the temperature of the low-pressure steam may not be sufficient. Could a fellow in the industry explain flue gas heat exchange?
This post was last edited by adsl121 on 2009-12-24 00:41. We use the SSR process, with the exhaust gas being heated using flue gas from an exhaust furnace; the heating method may vary depending on the process used in the facility. Please let us know what process you are using
This post was last edited by adsl121 on 2009-12-24 00:40. Our previous small sulfur treatment units used electric heaters, while the current units employ the SSR process, utilizing the flue gas from the exhaust gas incinerator as the heat medium
This post was last edited by adsl121 on 2009-12-24 00:38. On the one hand, exhaust gas heating furnaces take up a lot of space; on the other hand, they require a large amount of fuel gas. Therefore, it is unsuitable from both the perspective of layout and energy conservation. The online furnace approach tends to cause carbon deposition on the catalysts in hydrogenation reactors, and it is also unsuitable when the composition of gases in petrochemical plants varies significantly. The heat exchange using process gas combined with electric heating requires a large amount of electrical energy. Steam heating is generally not very practical, unless a low-temperature catalyst is used for the hydrogenation catalyst. Overall, using exhaust gas heating is the most ideal option.
This post was last edited by adsl121 on 2009-12-24 00:38. Our company uses flue gas heating; to achieve a temperature of 280°C in the hydrogenation reactor, the temperature after the exhaust gas incinerator must also be above 370°C.
This post was last edited by adsl121 on 2009-12-24 00:38. Our system uses the hot flue gas generated by the exhaust gas incinerator as a heat medium; this gas enters the exhaust gas heater where it exchanges heat with the exhaust gas coming out of the collector, thereby raising the temperature of the exhaust gas.
This post was last edited by adsl121 on 2009-12-24 00:39. The online reduction furnace we use features a cross-limit control system, and basically no H2 supply from the system is required.
This post was last edited by adsl121 on 2009-12-24 00:39. The manufacturing process in Zhenhai basically follows foreign technologies, using an online furnace process. Based on the current development status, I recommend using a combination of medium-pressure steam and exhaust gas heating. It should be quite suitable. Excess medium-pressure steam can be utilized; since the final step in the sulfur processing unit is inevitably combustion, the incinerator is one of the essential equipment. The temperature for stable combustion must be maintained above 550 degrees, so it is appropriate to use flue gas heating without resulting in excessive energy consumption. At the same time, steam heating is also a good option for the layout of the equipment; if the space is limited, steam heating can be used as well.