Feasibility of adding boiler water at the outlet of the first converter to control the inlet temperature of the second converter.
Thread Content
The company uses a 65-kilogram Texaco gasification process, with the subsequent stage being ammonia synthesis. The conversion system employs a two-stage wide-temperature sulfur-resistant conversion process, which is limited by the operating temperature of the gasifier. The relatively low water vapor in the conversion system results in an excessive carbon monoxide content in the conversion gas at the outlet of the ammonia scrubber. An increase in the gasification load and an elevation in production are both limiting factors. The shifted gas from the first shift converter must pass through a medium-pressure waste heat exchanger before entering the second shift converter, in order to control the inlet temperature of the second shift converter. However, in actual production, even when the waste boiler bypass valve is fully closed, the inlet temperature of the second converter remains high; this is also one of the factors contributing to the high carbon monoxide content at the outlet of the shift gas. Is it feasible to consider adding an inch-sized pipe in the pipeline from the first transformation furnace to the second transformation furnace to introduce boiler water for quenching, in order to control the inlet temperature of the second transformation furnace? Of course, considering the catalyst’s lifespan, this value will not be very large and is used merely as a regulatory mechanism. I hope marine enthusiasts will actively share their views and discuss together.
Adding boiler feed water is equivalent to promoting the reaction to proceed in the forward direction.
You can try increasing the pressure of the steam generated by the medium-pressure boiler in order to reduce the temperature of the shifted gas coming out of the medium-pressure boiler
A quencher can be installed, equipped with internal nozzles and packing, to ensure that all the high-pressure boiler feedwater discharged is completely vaporized.
It should be feasible, but the effect won’t be very significant. Some companies use quench water to control the inlet temperature of the secondary transformation furnace, but the amount used is relatively small. According to the original poster, it seems that the high inlet temperature of the second converter is the cause of the high temperature in that converter, which in turn leads to a high CO level (this is a bit confusing; higher temperature should indicate better conditions, or perhaps the water vapor ratio is indeed too low). Adding boiler water promotes the reaction to proceed in the forward direction, resulting in more heat being released by the reaction. This causes the bed temperature to rise, thereby reducing the CO content. Adding boiler water at a low temperature will cause the inlet temperature of the secondary transformer to drop, and a lower temperature is not conducive to the reaction. It comes down to which of these two factors has a greater impact; therefore, attention must be paid in practical applications. If too much boiler water is added relative to the water-vapor ratio reaction, it not only hinders the reaction but may also cause a drop in temperature, affecting the catalyst’s lifespan. What was said on the 3rd floor is correct: generate more steam for heat exchange to cool down, or add a small water cooler. The root cause of the high CO level is likely poor reaction due to a low water vapor ratio in the conversion gas; it is quite feasible for the poster to adjust both the temperature and the water vapor ratio by adding boiler water.
I’m sorry, OP; I was wrong. It should be to reduce the pressure of the by-product steam in order to produce more steam and lower the temperature of the conversion gas
Spray humidification can be added; since it is introduced into the gas phase, the issue of dew point corrosion in the waste boiler must be taken into consideration.
What is the inlet temperature control for your secondary converter? Has the water-vapor ratio been calculated?
There are two methods for cooling the shift gas: indirect and direct. The indirect method (steam generated from the waste heat boiler) is suitable for situations where the water content meets the requirements of the shift process, as it allows for efficient heat recovery; the direct method (water cooling) is appropriate when the water content is insufficient, as it simplifies the process. However, in general, water quenching does not involve directly introducing water into the pipeline; if the gas-liquid mixture is not uniform, water may end up in the converter, causing the catalyst to break down. Typically, a quencher is installed, filled with packing to ensure thorough mixing of gas and liquid before they enter the conversion furnace. It is recommended that the poster check the composition at the inlet and outlet of the shift converter, as well as the water vapor ratio at the inlet, to determine whether a low water vapor content is the cause of the high CO level. If water needs to be added, calculate how much is required to meet the needs of the shift conversion process. If the amount is not large, you can try adding some medium-pressure steam. Although it has higher energy consumption, the risk is low.
It’s feasible, but one must consider that the amount of water cannot be excessive and that the reaction heat from the converter needs to be removed; it would be better to simply replace it with a waste boiler.