2 Find the best speed and time for chemical feed
Reducing the increase in chemical feeds and increasing the frequency and frequency of chemical feeds makes it easier to control the temperature of a section of the furnace, thus accelerating the overall progress of chemical feed. Moreover, due to the small increase in chemical feed, the impact on a section of the furnace is small. For the equipment, the operating environment is milder, which is conducive to the safety and protection of the equipment; It is also small, but it is easier to control.
Practice has proved that finding the best chemical feed rate and time, from constant velocity feeding to multi-gradient, multi-frequency feeding, can reduce the total progress time of chemical feeding from 5h to 2h.
3 low temperature furnace optimal heating time
Through repeated driving, we found that after adding air to the second stage furnace, as the temperature of the high variable hearth layer gradually increases, the CO content of the high pressure furnace outlet drops rapidly. When the outlet temperature of the second stage furnace rises to 900 °C, The CO content of the high-altitude furnace outlet is completely reduced to the normal range; in addition, with the increase of the amount of air added and the adjustment of the chemical feed amount of the furnace, the water-carbon ratio can be ensured to be no more than 315, which fully meets the requirements of the low-variety furnace driving, so We have adopted a flexible method, in the case where the high-altitude hearth layer falls to the normal range and the second-stage furnace air has not been normalized, the low-pressure charging is performed, so that the second-stage furnace is heated and heated for 2 hours. Change into the system. In addition, in order to prevent the steam from condensing and damage the catalyst during the stringing, the low energy can be normal as early as possible. Before the string is low, we will raise the low inlet temperature to 220 °C in time; when the temperature of the upper layer of the low pressure furnace also rises, it will be timely. The temperature of the low-variation population has dropped to normal. By this method, not only the low change is inserted into the system in advance, but also the low-change outlet CO is qualified early.
4 absorption tower, methanation furnace charging timing
For the charging of the absorption tower, the initial requirement is to carry out after the normal air supply, the process gas at the outlet of the second stage furnace are qualified, and the low-speed serialization is carried out.
The charging of the methanation furnace can be carried out after the CO 2 of the low-CO and absorption tower outlets is qualified and the decarbonization system is stable.
According to the different holding pressure of each absorption tower and methanation furnace, we broke the previous driving mode and made it flexible. For the absorption tower, regardless of whether the string is low or not, as long as the system pressure and the pressure in the absorption tower are close, the reverse stamping valve of the absorption tower can be opened in time to insert the absorption tower into the system. It should be noted that before the system pressure is less than 3 MPa, the amount of gas introduced into the absorption tower should not be excessive, otherwise the decarburization water balance is difficult to maintain. After the absorption tower is inserted into the system, the process gas can be vented to the methanation furnace in time. According to the different pressure of the methanation furnace after each stop, when the system pressure is close to the pressure in the methanation furnace, the liquid can be drained and the pressure valve is opened. Moreover, it was found that the CO 2 content (AE05009) at the outlet of the string absorption tower quickly dropped below 012%. Although the CO 2 content exceeded the standard, the gas volume was small and the process gas temperature was low, so the bed was not caused by the actual pressure. A large change in temperature.
Through practice, it is considered that the flexible absorption tower and methanation furnace driving timing can not only shorten the driving time, but also the effect is better than the original.
5 Syngas compressor before the rising speed of the synthesis gas is integrated into the synthesis circuit. The syngas is charged at 07 K001 and 09 K001 until the minimum speed of the regulator. After the balance, the synthesis gas is recombined into the synthesis loop. According to this method, since the pressure before charging is above 5 MPa, the charging time needs to be long, and in actual operation, due to problems such as reset parameter indication, it is necessary to reset by means of on-site pressure gauge and main control opening and venting, pressure fluctuation. Large, it is also unfavorable for the compressor; in addition, once the reset valve is in trouble, it is not conducive to handling.
In response to these problems, research has concluded that charging after reversal will not only have a negative impact on the system, but also has many benefits. Because the compressor must be rotated slowly for 30 minutes after the pumping, at this time, the pressure is low, the charging time is short, and the slow turning opportunity is used to make the charging no longer occupy the time alone. If there is a problem with the reset parameter, it is not easy to reset, so the pressure is low, and the effect of the compressor is small by the venting reset, and once the reset valve has a problem, the pressure is low and the processing is faster. Practice has proved that the synthesis gas is integrated into the synthesis circuit before the speed increase, which not only shortens the driving time, but also is extremely beneficial for solving the problem of driving.
6 Synthetic tower catalyst self-heating equilibrium heating The initial synthesis tower heating requires a point to start the heating furnace. According to the ignition requirements of the heating furnace, a certain flow rate must be established before ignition, and the synthesis gas temperature needs a certain time. This leads to the first decrease of the temperature of the synthesis tower catalyst within 2 hours before the temperature rise of the synthesis tower catalyst, which drops to about 200 °C. When it is left and right, the temperature rise starts under the action of the start heating furnace. This heating method not only prolongs the time required for the temperature of the synthesis tower catalyst, but also the frequent rise and fall of the catalyst will accelerate its aging, lose its activity, and affect the strength of the catalyst.
After the ammonia plant is stopped, the time interval from the re-driving is not long, and the heat storage of the catalyst of the synthesis tower is large, and the heat preservation is good. Under normal circumstances, when the vehicle is driven again, the bed temperature of the synthesis tower catalyst is about 400 °C. Because the synthesis tower catalyst has good low temperature activity, after research and exploration, we designed the self-heating equilibrium heating method of the synthesis tower catalyst. First, the initial stage of self-heating equilibrium heating, the reaction speed is slow due to the lower temperature of the catalyst bed. The amount of syngas entering the synthesis bed catalyst bed should be as small as possible. If the amount of syngas is too large, it is easy to destabilize the catalyst bed, resulting in failure of self-heating equilibrium heating.
The second is to control the hydrogen to nitrogen ratio as high as possible, so that the hydrogen to nitrogen ratio is close to 3, in order to speed up the reaction speed of H 2 and N 2 , which is conducive to the progress of self-heating equilibrium heating.
The synthesis tower catalyst is used for self-heating and equilibrium heating, which avoids the phenomenon that the synthesis tower catalyst firstly cools when the temperature of the heating furnace is started. Because the temperature rise condition is mild, the damage to the catalyst is reduced to a minimum, and at the same time, the driving time is shortened. .
7 compressor heating pipe problem
In the past, the main reason was that the natural gas compressor heater was unqualified and delayed for a certain period of time. The reason was not that the warming pipe time was short, but that the main control did not focus on the control of the medium pressure steam temperature, resulting in a low temperature. In order to shorten the driving time, we have summarized, in the establishment of the medium pressure pipe network, in time for the natural gas compressor heating pipe, in order to make the heating pipe as early as possible, by increasing the temperature of the high pressure steam to ensure the temperature of the medium pressure steam 422 ° C, Create conditions for the early reversal of natural gas compressors.
For air compressor small turbines, syngas compressors and ice turbine turbines, one hour advance heating pipe, so that the heating pipe is qualified early, so as not to allow the heating pipe time to occupy the driving time alone.
Practice has proved that the above rapid driving measures will not only have adverse effects on the device, but also achieve the purpose of saving driving time and reducing economic losses.
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