The Feed gas and cold source of the crude argon tower come from the main tower and return to the main tower, so the crude argon Tower and the main tower are closely related and affect each other. The input of crude argon tower should have the following conditions:
1) the working condition of the main tower is stable;
2) the output and quality of oxygen and nitrogen products are close to or reach the normal value;
3) The argon content of argon fraction is close to normal;
4) the main cooling liquid level is relatively high with sufficient cooling capacity.
In the process of the crude argon tower being put into use, first lead out the argon distillation to precool the crude argon Tower, and then gradually send the liquid air to the crude argon condenser. With the chilling of the crude argon Tower, the rectifying working condition is gradually established in the crude argon tower. Its mark is that the resistance of the crude argon Tower, the purity of the crude argon and the extraction amount of the argon fraction increase continuously until the normal index is reached. At the beginning, the main cold liquid level may decline slightly, and with the establishment of crude argon column rectification, the main cold liquid level will recover.
Pay attention to the following problems when operating:
1) the enrichment of argon in the upper tower is not fixed. When the purity of oxygen and nitrogen products changes, the distribution of argon in the upper tower will change, and the composition of argon fraction will also change accordingly. The change of oxygen purity is sensitive to the influence of the composition of argon fraction. The change of oxygen purity is 0.1%, and the argon content of argon fraction will change 0.8% ~ 1%. With the increase of oxygen purity, the argon-rich area will move up and the argon content of the fraction will decrease. Therefore, appropriate oxygen purity and stability should be maintained to obtain distillation gas with high argon content;
2) the fluctuation of the main cold liquid level will also affect the composition and extraction quantity of the distillation. Experience shows that the fluctuation of main cold liquid level is 5 ~ 10 cm, the crude argon tower will have obvious reflection;
3) prevent argon freezing of crude argon condenser. Due to improper operation and adjustment, the liquid-air temperature is too low, and the temperature difference of the condenser increases, argon will solidify on the Condensation surface. At this time, the condensation decreases, and the composition of argon distillation and the reflux ratio of the distillation section of the main tower will change, which destroys the rectification of the main tower. When this happens, the work of the crude argon Tower should be stopped first, and the temperature of the crude argon condenser should be increased. Gradually put the crude argon Tower into it again after the freezing;
4) pay attention to the nitrogen content in the distillation. When the nitrogen content exceeds 0.1%, it will not only make the condensation of the distillation difficult, but also increase the nitrogen content of crude argon, which will affect the work of the refined argon tower. Therefore, the nitrogen content in the distillation should not be more than 0.01% generally.
In a word, the input operation of the crude argon tower should gradually increase the load of the crude argon condenser. If the operation is too fast, it will be the opposite and make the whole system fluctuate.
