Dear Haihao friends, there is a problem related to alkali matching that requires everyone’s help
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This post was last edited by zhaopeng02 on 2018-12-16 at 19:48. As an example: we have a tank containing 32% liquid caustic with a density of 1.35 and a capacity of 50 m3; there are two water tanks with a density of 1.0, each also with a capacity of 50 m3. There is also a tank containing 16% liquid caustic with a capacity of 80 m3. The company requires that the 32% concentrated caustic be diluted to 16% concentration. Both the pump used to draw out the concentrated caustic and the pump used to draw out water are equipped with glass tube flow meters, but the flow units are different – one is in m3/h while the other is in L/h. I’m not sure how to convert these units. I hope someone can help me with the formula for diluting the caustic (it would be great if you could also explain what each character represents... my education level isn’t high). I also need to know how to uniformly convert and calculate the units. What should be the flow rates of the concentrated caustic and water during the dilution process? Thank you everyone. (The flow rate of the concentrated caustic is in m3/h, while that of water is in L/h.)
It isn’t clear which flow unit is m3/h and which is L/h, so it’s difficult to know where to start.
The raw material alkali solution is in m3/h, and water is in L/h
If 32% of the flow rate is in m3/h. Calculating at 1 m3 per hour: 32%*1000*1.35=16%; therefore (1000*1.35+x) – x=1350 kg. In other words, 1350 kg of water is required per hour. Since 1 L of water equals 1 kg, this amount is equivalent to 1350 L/h.
So how is the flow rate of the raw material alkali per hour calculated?
The calculation assumes 1 m3/h.
The recommended procedure for actual preparation is as follows: Pump all the concentrated alkali (32%) that needs to be prepared into the 80 m3 liquid alkali tank (for example, 30 m3, as most liquid alkali tank trucks have a capacity of 30 m3). Check the level in the dilute alkali tank using a gauge or level meter, and take a sample to analyze its concentration (since the alkali tank may contain water or dilute alkali with an uncertain concentration; this step is not necessary if it is confirmed that there is no material present)； Calculate the pump shutdown time after adding water to the desired level using the method shown in the figure below. Both the alkali pump flow meter and the water pump flow meter serve only as auxiliary measurement devices for the amount of alkali pumped in and water added. The image was taken from Baidu Wenku and can be downloaded by yourself. It is also recommended to create a preparation sheet based on this image that suits the actual conditions of your workshop, and to post it at the location where the preparation is carried out; this way, operators can follow the sheet to avoid mistakes in their operations.
The calculations for the 4th floor are correct; when liquid is introduced simultaneously, with 32% alkali at a flow rate of 1 m3/h, 1350 L/h of clean water is required. The suggestions given for the 8th floor are insightful – there can be variations in the pump’s operating time, errors in the flow meter readings, and thus deviations in the final concentration. Using the liquid level as a criterion is also inaccurate; there are deviations in the level gauge, and the liquid already present in the tank also has an impact
I’d like to bother you again – could you check whether my understanding is correct? Using the formula ω1ρ1V1 = ω2ρ2V2, if I want to fill a tank containing 16% concentration of alkali solution to a volume of 80 m3, then 16% * 1.175 (the density of 16% alkaline solution) * 80 m3 = 32% * 1.35 (the density of the resulting solution) * V2. Thus, V2 is approximately 34.815 m3. Multiplying V2 by the density of 1.35 gives 47 tons; 80 m3 of 16% alkaline solution weighs 94 tons. Therefore, the amount of water that needs to be added is 94 – 47 = 47 tons. In other words, to fill an 80 m3 tank with 16% alkaline solution by adding 32% alkaline solution, 47 tons of each substance are required. If the filling process is to be completed in 2 hours, then dividing these amounts by 2 gives the hourly flow rate for both the alkaline solution and water. Is there any error in this calculation? ? ?