Calculation of catalytic cracking catalyst circulation rate
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The carbon balance method: Since the carbon content in the regenerated catalyst and the catalyst to be regenerated differs by not much, it is essential that the carbon analysis be accurate. Even minor errors or poor sampling representation can lead to significant fluctuations in the calculation results. The calculation method is as follows: Catalyst circulation rate = Carbon burning rate (kg/h) / {Carbon content in the catalyst to be regenerated (kg)/1 kg of catalyst} – Carbon content in the regenerated catalyst (kg)/1 kg of catalyst} (kg/h). The method for calculating the carbon burning rate is as follows: ① Calculate the carbon burning rate using the nitrogen balance principle: Volume of regenerated air × 79% = Volume of flue gas × (1 – CO2% – CO% – O2%) in cubic meters per hour. Thus, the volume of flue gas = (Volume of regenerated air × 79%) / (1 – CO2% – CO% – O2%) in cubic meters per hour. The carbon burning rate = 12/22.4 × Volume of flue gas × (CO2% + CO%) (kg/h), where 12 is the atomic weight of carbon, and 22.4 (cubic meters) is the volume of 1 mol of flue gas under standard conditions. Since the combustion of coke produces CO and CO2, the total number of CO and CO2 molecules in the flue gas is equal to the number of combustible carbon molecules in the coke (assuming no burning oil is used). ②It can be estimated from the total main air volume entering the regenerator. Based on the total main air volume A (in m3/h) entering the regenerator, the coke production rate (in kg/h) can be calculated directly; according to empirical data, 10 m3 of main air is required to burn 1 kilogram of coke. ∴ Coke production = A/10. A = total main air flow rate (in m3/h), determined from the reading of the flow meter at the exit of the main fan, after correction for the exit temperature and pressure relative to the design values. A = (Q_meter × Design × P_actual) / (T_actual × P_design) (in m3/h). Q_meter refers to the reading from the flow meter at the inlet or outlet of the main fan. T_set is the design temperature in K ； T_real, the actual temperature in K ； P_real represents the actual pressure ； Let P be the design pressure. The H/C ratio is calculated as follows: H/C = (100 – O2 – CO2 – CO) – 33.3×(O2 + 0.5 CO + CO2) / (CO + CO2). The carbonization rate is given by: carbon coke production / (1 + H/C), in kg/h. 2. The slide valve pressure drop method: The circulation rate G (in tons per hour) can be calculated using the formula ΔP = 7.65×10–7×G² / (ρA²). In the formula, P represents the pressure drop across the slide valve in kg/cm2; ρ is the density of the material in the inclined tube above the slide valve, in kg/m3; A is the flow area of the slide valve, in m2
I really need this thing! ! But I have a question, OP: In the formula for calculating the carbon content based on the volume of gas, cubic meters are used. Does this cubic meter refer to the volume at standard atmospheric pressure? If so, the volume of air entering the regenerator certainly isn’t at standard atmospheric pressure, as the regenerator is a high-pressure device; therefore, isn’t it necessary to perform some conversion on the measured volume of air? Thank you! ! Waiting for a reply! ! This post was last edited by Yunzhong Gong on 2009-3-18 15:14.]
I have a question for the original poster: 2. The slide valve pressure drop method – is ΔP equal to 7.65×10-7×G²/(ρA²)? Does G2 refer to the square of G, and does A2 refer to the square of A?
What do the two 2s in ΔP valve = 7.65×10-7×G 2/(ρA 2) mean?
The formula for calculating the pressure drop across the supplementary slide valve is ΔP_valve = 7.65×10^-7×G^2/((ρA^2)). The ^ symbol represents exponentiation. This formula can be found on page 365, equation (9-47), in the third edition of Petroleum Refining Engineering
Learning*, thank you to the original poster for posting such a meaningful topic, which has helped me, a beginner, understand
ΔP valve = 7.65×10^-7×G^2/(\rho A^2). Is the flow area of the slide valve the area of its valve plate? It’s difficult to measure the area of the valve plate since it’s located inside
What does 7.65×10-7 mean in ΔP valve = 7.65×10-7×G 2/(ρA 2 )? What is the unit? Thank you! ! !
7.65×10-7 is the result obtained from the inclusion flow coefficient and other unit conversions; by reverse calculation, the flow coefficient is around 0.8, but for a spool valve it should generally be between 0.85 and 0.9. This formula originates from petroleum refining engineering, and no further source could be found. It is recommended to use G=C0A0(2*ρ*δP)^0.5 for calculation. This one is more reliable.