I have a 15 years positive experience with co-burning with H2 during turndown and, in case it was necessary during hot stand-by (up to two months). Control was easy also using the H2 analyzers of the SCOT section. Do damages.
Thank you for great video! It's good opportunity to learn sulfur plant. I have a question about amount of h2s in molten sulfur. I know the amount of h2s in molten sulfur is 300~400ppmw regardless of 1,2,3 sultrap when capacity is max. However, when the capacity is so low, Is the amount of h2s in 2,3 sultrap so lower than before because of lower partial pressue of h2s?? For example, the amount of h2s in 2 sultrap is 50~100ppmw, that in 3 sultrap is 5~10ppmw. In summary, regardless of the amount of sulfur produced, is the h2s content in the sulfur generated in the thermal reactor and 1st, 2nd catalyst reactor the same or differenet?
Hi Bryce! If you are temporarily operating at very high (10:1+) turndown rates and the plant wasn’t designed for these levels, then cofiring is really the best and maybe only way to make the plant operable under these conditions. From the standpoint of sulphur recovery efficiency, the cofiring does create more COS and CS2 in the furnace and also dilutes the process gas streams, which may have an adverse impact on sulphur recovery efficiency. However, the low throughputs also give more residence time in the reaction furnace and catalyst beds which may actually improve sulphur recovery efficiency. If the overall impact on the recovery efficiency is negative, then there are changes to the catalyst bed or condenser temperatures which could overcome these efficiency declines. These modified optimum operating conditions during cofiring would be specific to each plant and would require some simulations or study to determine them. If you expect to operate at very high turndown rates permanently or for very long periods (i.e. purchasing low sulphur crudes for many years), then cofiring for these lengthy periods becomes less attractive and you would usually make mechanical modifications to the plant at the next opportunity (i.e. during the next scheduled turnaround) so that it can operate properly without cofiring. These modifications may include such items as a new / modified reaction furnace burner, new control valves, new flow meters, plugged condenser tubes (to increase mass velocity through the remaining tubes), changes to the catalyst bead size or catalyst bed volume, control system tuning, etc.
Please let us know if you need further assistance, thank you!
Please let us know about that 1) why ammonia is destroyed in Reaction furnace and what is the effects of ammonia salts on SRU and salts names . 2) how degassing works in simple words 3) why 1st stage titanium based Alumina catalyst haveing different temperature as compared to 2nd stage catalyst which is Alumina ?
This is a difficult question to answer since nitrogen can be used in many different ways during a shutdown. Some plants use it for the entire shutdown, including the sulphur removal step (often called a “sweep”), the bulk equipment cooldown steps (i.e. cooling down the reaction furnace from 1200+C at 50C to 80C per hour), and the final cooldown step (cooling all equipment to 40C before vessel entry can occur). Other plants use combusted natural gas for the “sweep” and bulk cooldown steps and only use nitrogen for the final cooldown. Other plants never use any nitrogen at all during a shutdown - the entire shutdown is done using only air and natural gas. As a general answer, all steps should be done at 25-30% of the design process gas throughput where possible; this ensures that the steps are done at a reasonable speed and are effective (i.e. this level of flow ensures that gas does not “channel” through parts of the catalyst beds and miss other parts of the catalyst beds). So for the recommended nitrogen volume for any of the steps, you can use 25-30% of the design material balance flow for the plant. Regarding hours, if you are at the recommended volumes then the “sweep” usually takes around 8-12 hours (but can take 24-48+ hours at lower volumes), the bulk cooldown around 16-24 hours (governed by the recommendation that you don’t cool down the reaction furnace faster that 80C per hour), and the final cooldown usually another 4-6 hours. As a note, it is almost impossible to remove all traces of SO2 and S from the plant during a shutdown; the small pores of the refractory and the catalyst will still continue to hold and release some SO2 even after the best shutdown procedures. But the timelines above will remove the large majority of the sulphur species, which is the goal of a good shutdown.
during turndown with low H2S concentration, the SO2 keeps breaking in causing upset. Would you recommend to just manually operate with total air requirement based on the feed forward factor 2.38 and break the cascade on the trim controller (which keeps dancing on low throughputs due to controller tuning based on higher load) and operate with excess h2s/so2 ratio 6:1 . 8:1 along with fuel gas cofiring to ensure sufficient H2 production to prevent SO2 breakthrough ? 😃😆
The H2S in the acid gas keeps changing from 30 to 38% during a shift, how to stabilize the air requirement as we never arrive at a steady tail gas ratio of 2
For constant large acid gas H2S changes, like your frequent 30-38% fluctuations, it is recommended to install an acid gas H2S analyzer. The analyzer would constantly adjust the required feed-forward air:acid gas ratio based on the H2S content. The feedback H2S:SO2 analyzer would then have a lot less work to do, and would be better able to keep the tail gas ratio at 2:1.
Awesome Video Gerald! I love these videos ! 😊
Thank you!
useful information! I subscribed this channel
김민성 thank you!
I have a 15 years positive experience with co-burning with H2 during turndown and, in case it was necessary during hot stand-by (up to two months). Control was easy also using the H2 analyzers of the SCOT section. Do damages.
Great information, Gerald.
Yonghee Kang Thank you!
Thank you very much
No problem, glad you enjoyed it!
great video
thank a lot for sharing the video
Thank you for great video!
It's good opportunity to learn sulfur plant.
I have a question about amount of h2s in molten sulfur. I know the amount of h2s in molten sulfur is 300~400ppmw regardless of 1,2,3 sultrap when capacity is max. However, when the capacity is so low, Is the amount of h2s in 2,3 sultrap so lower than before because of lower partial pressue of h2s?? For example, the amount of h2s in 2 sultrap is 50~100ppmw, that in 3 sultrap is 5~10ppmw. In summary, regardless of the amount of sulfur produced, is the h2s content in the sulfur generated in the thermal reactor and 1st, 2nd catalyst reactor the same or differenet?
These videos are great! Are there any options or modifications out there to improve sulfur recovery efficiency at very high (10:1+) turndown?
Hi Bryce! If you are temporarily operating at very high (10:1+) turndown rates and the plant wasn’t designed for these levels, then cofiring is really the best and maybe only way to make the plant operable under these conditions. From the standpoint of sulphur recovery efficiency, the cofiring does create more COS and CS2 in the furnace and also dilutes the process gas streams, which may have an adverse impact on sulphur recovery efficiency. However, the low throughputs also give more residence time in the reaction furnace and catalyst beds which may actually improve sulphur recovery efficiency. If the overall impact on the recovery efficiency is negative, then there are changes to the catalyst bed or condenser temperatures which could overcome these efficiency declines. These modified optimum operating conditions during cofiring would be specific to each plant and would require some simulations or study to determine them.
If you expect to operate at very high turndown rates permanently or for very long periods (i.e. purchasing low sulphur crudes for many years), then cofiring for these lengthy periods becomes less attractive and you would usually make mechanical modifications to the plant at the next opportunity (i.e. during the next scheduled turnaround) so that it can operate properly without cofiring. These modifications may include such items as a new / modified reaction furnace burner, new control valves, new flow meters, plugged condenser tubes (to increase mass velocity through the remaining tubes), changes to the catalyst bead size or catalyst bed volume, control system tuning, etc.
Please let us know if you need further assistance, thank you!
Please let us know about that
1) why ammonia is destroyed in Reaction furnace and what is the effects of ammonia salts on SRU and salts names .
2) how degassing works in simple words
3) why 1st stage titanium based Alumina catalyst haveing different temperature as compared to 2nd stage catalyst which is Alumina ?
Is there any thumbrule related to hours (including volume) of nitrogen sweep required during shutdown to remove traces of Sulphur & SO2 in the system.
This is a difficult question to answer since nitrogen can be used in many different ways during a shutdown. Some plants use it for the entire shutdown, including the sulphur removal step (often called a “sweep”), the bulk equipment cooldown steps (i.e. cooling down the reaction furnace from 1200+C at 50C to 80C per hour), and the final cooldown step (cooling all equipment to 40C before vessel entry can occur). Other plants use combusted natural gas for the “sweep” and bulk cooldown steps and only use nitrogen for the final cooldown. Other plants never use any nitrogen at all during a shutdown - the entire shutdown is done using only air and natural gas.
As a general answer, all steps should be done at 25-30% of the design process gas throughput where possible; this ensures that the steps are done at a reasonable speed and are effective (i.e. this level of flow ensures that gas does not “channel” through parts of the catalyst beds and miss other parts of the catalyst beds). So for the recommended nitrogen volume for any of the steps, you can use 25-30% of the design material balance flow for the plant.
Regarding hours, if you are at the recommended volumes then the “sweep” usually takes around 8-12 hours (but can take 24-48+ hours at lower volumes), the bulk cooldown around 16-24 hours (governed by the recommendation that you don’t cool down the reaction furnace faster that 80C per hour), and the final cooldown usually another 4-6 hours.
As a note, it is almost impossible to remove all traces of SO2 and S from the plant during a shutdown; the small pores of the refractory and the catalyst will still continue to hold and release some SO2 even after the best shutdown procedures. But the timelines above will remove the large majority of the sulphur species, which is the goal of a good shutdown.
during turndown with low H2S concentration, the SO2 keeps breaking in causing upset. Would you recommend to just manually operate with total air requirement based on the feed forward factor 2.38 and break the cascade on the trim controller (which keeps dancing on low throughputs due to controller tuning based on higher load) and operate with excess h2s/so2 ratio 6:1 . 8:1 along with fuel gas cofiring to ensure sufficient H2 production to prevent SO2 breakthrough ? 😃😆
The H2S in the acid gas keeps changing from 30 to 38% during a shift, how to stabilize the air requirement as we never arrive at a steady tail gas ratio of 2
For constant large acid gas H2S changes, like your frequent 30-38% fluctuations, it is recommended to install an acid gas H2S analyzer. The analyzer would constantly adjust the required feed-forward air:acid gas ratio based on the H2S content. The feedback H2S:SO2 analyzer would then have a lot less work to do, and would be better able to keep the tail gas ratio at 2:1.