Question: Based on the following data, analyze the operation of the water-coal slurry gasification A/C furnace and determine how to make appropriate adjustments

1. Among the gas compositions of Furnace A and Furnace C, only the methane content differs significantly; the temperature of Furnace A should be higher than that of Furnace C； 2. The residual carbon levels in Furnace A and Furnace C differ significantly, which is related to the different furnace temperatures of these two furnaces, as well as factors such as the oxygen-to-coal ratio, gasification pressure, and the atomization effect of the burners on the water-coal slurry. This post was last edited by Wandering D Scorpion on 2009-2-5 21:35]

The temperature of Furnace C should be increased! The other data is good! It’s that C has a higher methane level than A!

Sorry, I mistook C for B just now!

Although the methane content in Furnace C and the carbon residue in the cinder are slightly high, the composition of the effective products is still good; it can be said that the operation of the furnace is satisfactory. It’s completely normal to have some differences between the two systems. I wonder if there has been any change in the burner pressure difference of Furnace C? If possible, it would be best to adjust the central oxygen level and give it a try.

The two burners are different; A is domestic, while C is imported. Thank you to floors 2, 3, and 5; your analyses are all reasonable.

1. The table below shows the gas composition and slag sample analysis data for two Texaco quench-process gasifiers in a certain plant on a particular day. Based on this data, analyze the operating conditions of these two gasifiers, determine the causes leading to such operating conditions, and propose appropriate corrective measures.

Gas analysis results for Furnace A:
H2 CO ∑CO2 CH4
137.15 43.18 0.25 18.91 0.14 237.65 42.67 80.32 18.87 0.15 337.62 42.59 80.21 18.97 0.13 437.44 42.67 80.07 18.89 0.22 537.09 42.92 80.01 19.3 0.28 637.39 42.44 79.83 19.41 0.19 736.87 43.07 79.94 19.36 0.19 837.84 42.42 80.26 18.91 0.25 936.86 43.12 79.98 19.09 0.19 1037.15 42.81 79.96 19.16 0.19 1136.44 43.68 80.12 19.24 0.18 1237.24 42.58 79.82 19.49 0.14 1337.82 42.32 80.14 19.17 0.16 1437.73 42.48 0.13 19.22 0.18 1537.23 42.82 80.05 19.11 0.17 1637.51 42.52 80.03 18.97 0.25 1737.63 42.69 80.32 18.86 0.27 1837.41 42.46 79.87 19.36 0.24 1937.84 42.24 80.04 18.97 0.25 2038.75 42.15 80.91 18.05 0.27 2137.74 42.39 80.09 19.01 0.24 2237.24 42.72 79.92 19.09 0.2

Average values: 37.43 42.67 80.1 19.06 0.20

Gas analysis results for Furnace C:
H2 CO ∑CO2 CH4
137.24 42.98 80.22 18.78 0.45 237.99 42.24 80.23 18.79 0.43 337.65 42.47 80.12 18.93 0.35 437.84 42.17 9.91 18.89 0.49 537.33 42.57 79.91 19.05 0.56 637.45 42.32 79.77 19.37 0.28 736.55 43.12 79.67 19.2 0.48 837.74 42.47 80.17 18.67 0.53 937.03 42.88 79.91 18.9 0.45 1037.17 42.76 79.93 18.96 0.48 1137.44 42.74 80.14 18.91 0.44 1237.76 42.09 79.85 19.21 0.41 1337.67 42.58 0.17 18.83 0.42 1437.87 42.06 79.93 19.06 0.51 1537.75 42.32 80.07 18.73 0.46 1637.61 42.43 80.04 18.63 0.63 1737.74 42.01 79.75 19.13 0.59 1837.66 41.68 79.34 19.59 0.54 1937.56 41.95 79.51 19.27 0.54 2037.67 42.52 80.19 18.48 0.59 2137.23 42.68 79.91 18.66 0.55 2237.36 42.55 79.91 18.81 0.56

Average values: 37.51 42.43 79.94 18.95 0.48

Residual carbon:
A: 25.36 15.74 13.46 19.46 27.34 24.64 19.36 35.13 11.93 1114.93 7.36 25.17 13.68 26.72
C: 23.95 5.42 49.12 25.14 41.22 22.88 14.78 37.63 2.8 22.44 57.44 50.35 58.44

Average values: 19.73 135.46 71

Furnace A is operating relatively stably, but the occurrence of \"high levels of two parameters\" is likely due to the type of coal used. Furnace C has a problem with poor atomization compared to Furnace A; it seems that the burners are not spraying properly, as can be inferred from the high levels of residual carbon and methane. Please point out any mistakes in what I’ve said; these are just my personal opinions.

Is the poster from Yanchang Petroleum? I copied this question from Comrade Li’s post to use it as an exercise for us; later I sent it to a captain at a team based in Shenmu, at Yanchang Petroleum, and not even the question was changed. Where did you get it from?

Moderator Old Li is going to be upset again. These days, his posts have been frequently reposted by others. But this question is indeed good. It has improved everyone’s ability to analyze and make judgments.

There is only one explanation for high CH4 levels: the gasification temperature is low; therefore, the oxygen-to-coal ratio should be increased appropriately to raise the furnace temperature. High residual carbon levels may be caused by a low gasification temperature, or they may result from poor atomization of the burner or uneven distribution of the fuel. It is advisable to observe the situation for some time after increasing the oxygen-to-coal ratio; if the residual carbon level remains high, then it will be necessary to check whether there is a problem with the burner.

There’s a problem with burner C; it needs to be repaired. Another issue is that the particle size of the coal slurry is not very good, with a higher proportion of large particles.

Viewpoint 1: As can be observed from the data in the table, Furnace A is operating normally. Furnace C has a high level of CH4 in its syngas, as well as a high amount of residual carbon in the slag. The reasons for the high CH4 content include a low temperature in the gasification furnace, blockage at the slag outlet, and improper spraying by the burners, resulting in poor atomization. The high residual carbon level is due to improper spraying by the burners, poor atomization, excessive load, and a high pressure difference across the burners, which leads to a lower oxygen-to-coal ratio and a shift of the combustion zone downward. Additionally, the temperature in the furnace is low. By observing the changes in CO, CO2, and CH4 levels in Furnace C, it can be ruled out that there is a blockage at the slag outlet. By comparing the effective gas data for Furnace A and Furnace C, it can be ruled out that the low temperature is the cause. Since an excessive load does not cause significant changes in the CH4 level, it can be concluded that there is damage to the burners in Furnace C. As can be seen from the changes in CH4 and residual carbon levels in the table, in the initial stage the operators managed to maintain the furnace’s operation by reducing the load multiple times, which had a certain effect on reducing the residual carbon level. However, after further adjustments to the load, this effect became less significant; the subsequent data clearly show that the situation deteriorated and it became difficult to maintain the furnace’s operation.

Viewpoint 2: The gas composition of Furnace A is normal; compared to Furnace A, Furnace C has a higher methane content and a higher residual carbon content. It can be inferred that this is caused by a lower furnace temperature in Furnace C. Since furnaces A and C are operating simultaneously, it can be ruled out that the issue is caused by the slurry concentration and oxygen purity. The control room checks the pressure difference of the gasification furnace and the pressure difference of the burners. On-site, check the differential pressure gauge and compare it with the control system to make an accurate judgment, and also observe whether slag stringing occurs. If it is determined that the slag port is blocked, gradually increase the temperature to clear it. If it is determined that there is uneven combustion from the burner (an increase in burner pressure difference and abnormal wall temperature of the on-site gasifier), the operation shall be stopped for maintenance. In addition, it is also possible that it is due to a problem with the meter of the methane analyzer, so a check of the meter has been requested.

Viewpoint 3: Based on the analysis of the data, the most significant difference between Furnace C and Furnace A is that Furnace C has higher levels of methane and residual carbon. The amounts of effective gases and carbon dioxide in Furnace C remain relatively stable, while Furnace A appears to be operating normally according to the data. According to relevant principles, high methane levels are caused by a blocked slag outlet, a low operating temperature of the gasification furnace, as well as improper nozzle operation and poor atomization effects. High residual carbon levels are due to a low operating temperature of the gasification furnace, improper nozzle operation, damaged nozzles, and insufficient oxygen at the center of the nozzles, resulting in poor atomization effects. It can therefore be concluded that low operating temperatures, improper nozzle operation, and poor atomization effects in Furnace C are the main reasons for the high levels of methane and residual carbon. However, upon further comparison of the data in the table, it was found that in three time periods—3, 6, and 9—the levels of methane and residual carbon in Furnace C decreased significantly compared to the previous period, indicating that the operator adjusted the operating temperature of the gasification furnace. Yet, high levels of methane and residual carbon reappeared later on. This proves that the high levels of methane and residual carbon in Furnace C are indeed caused by improper nozzle operation and poor atomization effects. Even after making multiple adjustments to the burner pressure difference or load, it still cannot operate properly; there is only one solution: shut it down for maintenance!!!

Viewpoint 4: The data shown in the graph indicates that furnace C has a higher CH4 content and a higher residue carbon content compared to furnace A. The main reasons for this phenomenon are as follows: Reasons for the high CH4 content: (1) Low temperature in the gasification furnace； (2) Blockage at the slag outlet. (3) The burner sprays unevenly, resulting in poor atomization; reasons for high carbon residue: (1) Improper adjustment of the oxygen supply at the center of the burner ； (2) The operating furnace temperature is too low ； (3) The oxygen gap or slurry gap of the burner increases, resulting in poor atomization ； (4) Poor quality of coal slurry. The phenomena indicating a clogged slag outlet include the following: (1) an increase in the pressure difference PDI1214; (2) large fluctuations in the liquid level of the gasification furnace; (3) significant variations in the CH4 levels as indicated by the syngas analysis results; (4) when examining the slag sample at the bottom of the decanting tank, the slag shows stringy properties. To further determine whether the slag outlet is clogged, if increasing the oxygen-to-coal ratio leads to an increase in CO levels and a decrease in CO2 levels, it can be concluded that the slag outlet is clogged. This is due to the prolonged residence time of gases in the combustion chamber, which causes abnormal changes in the gas composition. If the above phenomena are ruled out, and the operating conditions of the burner are assessed further, it can be seen that as the burner operates for an extended period, the nozzle tip deforms, resulting in poor atomization. At this point, the composition of the gas changes significantly, and the amount of effective gas decreases. In particular, when uneven spraying occurs, it leads to excessively high local temperatures, which can damage the thermocouples; in severe cases, gas leakage can occur, causing the furnace walls to overheat. Based on the data in the graph, the decrease in the effective gas components is not very significant; further judgment should be made by considering the furnace wall temperature as well. Solution: Increase the oxygen-to-coal ratio and appropriately raise the central oxygen flow rate; then make further judgments by considering changes in gas composition, furnace wall temperature, and slag shape