Calculation of bed temperature rise

The usual estimation methods are also applicable to two-stage bed layers, and the estimated temperature rise should not be underestimated.

I calculated the temperature rise in the bed layer using the formula from \"Inorganic Chemical Engineering – Sulfuric Acid and Nitric Acid\": λ = n0*a*(-ΔHr) / (nt*Cpm). The initial SO2 concentration a is set at 0.89; n0 and nt are determined based on material balance data, and then Cpm is calculated. This method yields results that are certainly more accurate than estimates.

Which gentleman is interested in doing the calculation?

It has been calculated, confirming my inference.

I would like to ask whether this temperature refers to the temperature of the catalyst layer or the temperature of the pipeline Also, when we control the converter parameters, does the temperature parameter refer to the catalyst layer or the pipelines? These two temperatures should be consistent, but only one of them should be controlled during operation.

Generally, the temperature of the inlet and outlet pipes is controlled; the bed temperature point is often not representative due to uneven airflow distribution.

The temperatures at the inlet and outlet of the bed layer should be controlled! :o The temperature in the pipeline often differs significantly from the temperature of the bed layer, due to uneven airflow distribution (mainly at the inlet) and heat dissipation (mainly at the outlet). The temperature that truly affects the conversion rate is the temperature at the inlet and outlet of the catalyst bed. Imagine if the temperature displayed on the pipeline is 620 degrees, while the temperature at the outlet of the bed layer shows 660 degrees – would you still remain calm and uninterested? :lol

The problem is that in most cases, the temperature differences between various points in the bed are significant; this is generally attributed to the distribution of airflow, and the flue gas at the outlet of the bed, after mixing, is more representative. Of course, if the outlet temperature of the bed layer reaches 660 degrees, it definitely needs to be addressed.

If there is a large difference between the bed temperature points, and if the positions of the instruments and thermocouples are correct, then it’s obviously due to uneven airflow distribution (in terms of temperature, composition, flow rate, etc.). “The term \"mixed flue gas at the flue gas outlet pipe of the bed layer\" should refer to the apparent average value of the bed layer. Logically, the temperature value at this point should be intermediate – lower than the highest temperatures in the bed layer but higher than the lowest temperatures. However, in practice, due to heat loss, the temperature measured at the outlet pipe is often even lower than the lowest temperature in the bed layer; it is therefore only for reference purposes. As for the temperature on the inlet pipeline, it is often lower than that in the catalyst bed, mainly due to the effects of the control bypass lines in the heat exchanger (which cause uneven temperature distribution at the bed inlet); of course, the high-temperature gases exiting the upper layer of the bed also play a role in affecting the temperature at the bed inlet. As mentioned earlier, the temperature at the catalyst bed is the key factor affecting the conversion rate. If there is a large difference between the temperatures at various points in the bed, a compromise must be found in terms of control measures, and efforts should be made to identify the causes in order to reduce this difference.

It’s not that easy to calculate. I remember there were very detailed calculation examples in the sulfuric acid operation manual that can be used as a reference

2# txglyl I infer that the meaning of \"in an instant\" is that during the second conversion, since SO3 is absorbed, there is no need to heat this SO3, so the temperature rise during the second conversion must be higher, right? This might be correct for precise calculations, but it is a fallacy for estimating temperature rise! The premise of our estimation is that the average heat capacity of the gas remains constant before and after the reaction (and it is likely to vary little in reality); otherwise, an estimation is not possible.

For 12# boqing_zh, in the case of a \"3+1\" double-turn double-suction system, by the time the flue gas reaches the fourth stage, SO3 has already been removed by one absorption tower, and SO3 accounts for a significant proportion of its contents. Assuming a primary conversion efficiency of 95% for sulfur to sulfuric acid, the molar amount of flue gas by that point is already reduced by nearly 10%! The temperature rise is also calculated based on levels one to three – can there be no errors?

I would like to ask what each symbol in λ=n0*a*(-ΔHr)/((nt*Cpm) represents Thank you