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II. Short Answer Questions 1. What is a catalyst? What is the role of a catalyst in chemical reactions? Answer: A catalyst is a substance that can increase the rate of chemical reactions without changing its own chemical properties. In chemical reactions, catalysts serve to speed up the reaction rate, reduce the reaction time, and enhance production capacity. What are the characteristics of the 2-transformation reaction? Answer: It is exothermic, a reversible reaction that requires a catalyst for the transformation to occur, and it must take place at an appropriate temperature. 3 What three aspects should be considered in the reduction reaction of medium-temperature catalysts? Answer: 1. Reduction must proceed according to the required reaction; that is, Fe2O3 should be reduced to Fe3O4, not to Fe (with steam). 2. The catalyst must not be overheated. 3 There must be no oxygen present in the reducing gas. 4 What is the transformation rate? What is a balanced transformation rate? Answer: The conversion rate is the ratio of the amount of CO that is converted through the shift reaction in the feed gas to the amount of CO already present in the reducing gas ； The conversion rate at which the CO conversion reaction reaches equilibrium under certain temperature and pressure is called the equilibrium conversion rate. 5 What is the equation for the reduction reaction of medium-temperature catalysts? Answer: 3 Fe2O3 + H2 = 2Fe3O4 + H2O + Q; 3Fe2O3 + CO = 2Fe3O4 + CO2 + Q. 6 What is the effect of wash water temperature on the intermediate transformation? Answer: Raising the temperature of the washing water causes the temperature of the vaporized gas to rise as well; at the same time, the amount of saturated steam in the vaporized gas increases, which leads to a decrease in the furnace temperature. What are the means of adjusting the furnace temperature in 7 161A? Answer: T2, T3 – line adjustment ； F1 plus steam adjustment ； The gasification system regulates the furnace temperature through the temperature of the gasified gas. 8 How to determine when the reduction of the medium-activity catalyst is complete? Answer: During the reduction process, when the concentration of carbon monoxide gradually rises above 12%, the temperature in the catalyst layer remains stable and the percentage of H2 at the outlet increases significantly; this indicates that the reduction is complete. 9 When is it considered that the deactivation of the medium-temperature catalyst has ended? Answer: When the oxygen concentration in the exhaust gas from Unit 2 is ≥8%, and no temperature rise occurs in the catalyst layer, the pressure can be increased to 0.4 Mpa. If there is no significant temperature rise after stabilizing with air for more than two hours, it can be considered that the passivation process is complete. 10 What are the advantages of a blower generating heat? Answer: Circulating heat generation to save nitrogen ； Operational safety ； It is easy to operate and the temperature is easy to control. 11 Selection of active components for low-temperature shift catalysts? Answer: Copper has a stronger activity toward CO than Fe4O3, but weaker than nickel. Compared to Fe4O3, copper can catalyze the CO reaction at lower temperatures. unlike nickel, it does not accelerate the methanation reaction. Therefore, copper exhibits good activity and selectivity for the CO conversion reaction. 12 What are the main factors that damage the activity of low-temperature shift catalysts? Answer: S poisoning ； Chlorine poisoning ； Water vapor condensation ； Thermal aging. 13 Why is reduction necessary before using a low-activity catalyst? Answer: The unreduced low-temperature catalyst, in which the active component Cu exists in the form of CuO. It is only active when reduced to elemental Cu, so reduction must be carried out before use. 14 What are the reasons for the natural oxidation of low-volatility catalysts? Answer: Nitrogen was not used to maintain pressure while parking, allowing air to enter and cause localized oxidation. What are the methods for adjusting the temperature of a 15 170A low-voltage transformer? Answer: T21 regulation ； F21 increment/decrement adjustment ； Adjustment of the low-temperature exchanger feed line. 16 T22/170B, what is the function of valves A and B? Answer: Valve A is the control valve for the steam heater. Turning it on raises the inlet temperature, while turning it off lowers it. Valve B is the branch valve for the low-temperature heat exchanger. Turning it on lowers the inlet temperature, while turning it off raises the inlet temperature. 17 T22/170B, what are the types of control valves A and B? Answer: T22A pneumatic opening ； T22B air lock. 18 What determines the control criteria for the low-variation inlet temperature? Why? Answer: It depends on the dew point temperature at the operating pressure. Prevent steam condensate from entering the furnace and damaging the catalyst. How to connect the 19 170AB system? Answer 1: Connection from in front of the 169A single outlet valve → behind the 170 S-removal inlet valve ； 2﹚From in front of the 170BZnO desulfurization outlet valve → Connection at the point where the primary gas from 170B enters the low-temperature converter ； 3﹚ Connection from in front of the 170B low-temperature variable outlet valve to in front of the inlet flange of the 169A low-temperature variable boiler. How to handle 20 H10/169A with liquid? Answer: Treat it urgently and promptly. Turn on P6 for pressure holding and venting, close the inlet and outlet manual valves, and open the desulfurization tank furnace for venting and pressure relief. Once depressurization is complete, turn on the steam heater and introduce nitrogen for purging using hot nitrogen. How to handle 21 H10/169B with liquid? Answer: Treat it urgently and promptly. Open P6 for pressure holding and venting, close the manual valve at the low-pressure outlet, and after starting the furnace, vent it to relieve pressure. Once depressurization is complete, close the outlet valve once, open the low-pressure transformer inlet valve, turn on the steam heater to introduce nitrogen, and use nitrogen for purging. 22 How to deal with severe over-temperature under low variation? Answer: Perform an emergency stop. Turn on P6 for pressure holding and venting, close the inlet and outlet manual valves, then turn on the furnace venting system to carry out pressure relief. Once the pressure relief is complete, cold nitrogen is introduced for purging and cooling. 23 How to determine internal leakage in the low-temperature heat exchanger without stopping the machine? Answer: Sample and analyze the CO content in the low-temperature converter inlet gas. If the CO content at the outlet is higher than that at the inlet, it can be considered that there is a leak in the low-temperature converter. What are the control methods available for the 24 3# low-voltage transformer? Answer: (1) Adjust the valve of the steam heater T22A ； ⑵Adjustment of valve T22B for low-temperature heat exchanger feed line ； ⑶F21 steam addition/subtraction control ； ⑷Oil level ； ⑸Temperature and pressure reduction. 25 How is the temperature of the methanation reactor adjusted? Answer: (1) Adjusted by the T24 manual valve. Increase the furnace temperature when it is closed, and decrease it when it is open. ⑵When the furnace temperature rises sharply, open the cold nitrogen valve before starting the furnace to introduce cold nitrogen for cooling. 26 Why is it strictly prohibited to allow gas flow below 200°C in the methanation system? Answer: To prevent the formation of nickel carbonyl, which would poison the methanation catalyst. 28 What are the reasons for the low temperature in the methanation reactor? Answer: (1) The furnace temperature in Unit 2 is low ； ⑵The opening degree of the T24 manual valve is too large ； ⑶The catalyst has poor activity. 27 What are the reasons for the excessive levels of trace CO and CO2 in the refined gas? Answer: (1) Low transformation rate; poor effect of secondary alkali washing ； ⑵Internal leakage in the methanation heat exchanger ； ⑶Poor catalyst activity ； ⑷Oil leakage amount in the intermediate heat exchanger. 28 What are the reasons for high precision gas temperature? Answer: (1) Poor cooling effect, scaling ； ⑵The circulating water is not flowing properly ； ⑶The circulating water pressure is low. 30 Why are the cooling water inlet and outlet valves shut off during a long-term shutdown of the methanation cut-off unit? Answer: To prevent leaks in the methanation water cooler, so that circulating water does not enter the methanation reactor and damage the catalyst. 31 Why is a secondary separator placed before nitrogen supply to the methanation reactor? Answer: The main purpose is to remove oil contaminants from N2 in order to protect the methanation catalyst. 32 Write the methanation reaction equation? Answer: CO + 3H2 ↔ CH4 + H2O + Q; CO2 + 4H2 ↔ CH4 + H2O + Q. What are the vent and drain collection points for the main vent pipes of Vaporizers #2 and #3? Answer: (1) P6/161B venting ； ⑵P24/170B venting ； ⑶De-Sulfurization tank venting ； ⑷Vent behind low-temperature exchanger ； ⑸B liquid droplet separator drain. What are the vent and drain collection points for the 1# and 4# gasifier vent main lines in transformation 34? Answer: (1) P6/161A vent ； ⑵P24/170A vent ； ⑶A droplet separator drain. Why should the vent valve of the 35 N2 distribution pipe be kept in the fully open position under normal conditions? Answer: To prevent internal leakage in the manual valve and accidents caused by gas mixing. 36 What are the reasons for high resistance in the methanation system? Answer ⑴ Catalyst crushing ； ⑵Some valves in the system are opened too slightly ； ⑶There is more oil in N2, resulting in the formation of C. 37 What is the reaction equation for the excessive reduction of medium-activity catalyst to Fe? Answer: Fe3O4 + 4H2 = 3Fe + 4H2O + Q; Fe3O4 + 4CO = 3Fe + 4CO2 + Q. 38. Write the equations for the side reactions that occur under intermediate conditions Answer: 2CO = C + CO2 + Q; 2CO + 2H2 = CH4 + CO2 + Q; CO + 3H2 = CH4 + H2O + Q; CO2 + 4H2 = CH4 + 2H2O + Q. What are the possible side reaction equations resulting from the reduction of catalysts in process 39? Answer: Fe3O4 + H2 = 3Fe + 4H2O + Q; Fe3O4 + 4CO = 3Fe + 4CO2 + Q; 4Fe3O4 + O2 = 6Fe2O3 + Q; 2CrO3 + 3CO = Cr2O3 + 3CO2 + Q