How to determine the tank volume and power requirement?

In summary: Roughly speaking, water at a given temperature and pressure is more dense than water at a different temperature and pressure.
  • #1
t0mm02
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0
Homework Statement
A conventional stirred tank is used for rapid mixing in a water treatment plant with a flow of 100 x 106 L/day. The water temperature is 10°C. Determine the tank volume and power requirement?
Relevant Equations
V = Q (flow rate) x θ (times the hydraulic detention time)
Hello everyone. I have to determine the tank volume and power requirement of a tank. The teacher has done it the following way, however, I don't understand the process.
 

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  • #2
The 69 m3 tank is filled and emptied every 60 seconds. This gives you 1.15 m3/s. Now, if you multiply 1.15 m3/s by 86400 s (one day) you get 99360 m3, very close to 100x106 liters. As for the power, you haven't given any data.
 
  • #3
Gordianus said:
The 69 m3 tank is filled and emptied every 60 seconds. This gives you 1.15 m3/s. Now, if you multiply 1.15 m3/s by 86400 s (one day) you get 99360 m3, very close to 100x106 liters. As for the power, you haven't given any data.
How do you calculate the Volume though? I don't understand what he did on that picture to work it out.
 
  • #4
What is the volume of a tank that, filled and emptied every 60 seconds, amounts to 100x106 liters in a day?
 
  • #5
Poster has been reminded to show more effort in their schoolwork posts
Gordianus said:
What is the volume of a tank that, filled and emptied every 60 seconds, amounts to 100x106 liters in a day?
I have no idea, that is what I am asking you
 
  • #6
Let's say the tank has volume ##V## and that every ##T= 60## seconds it is filled and emptied. You repeat this cycle 1440 times (the number of minutes in one day) and the total exchanged volume is 100x106 liters. Can you figure out the volume of the tank?
 
  • #7
t0mm02 said:
How do you calculate the Volume though? I don't understand what he did on that picture to work it out.
Do you understand the concept of hydraulic detention time?
Imagine a river flowing into a lake and then continuing on downstream that lake.
The HDT in that case would be the time that it would take for that upstream river flow to completely fill that empty lake.

Copied from
https://baywork.org/wp-content/uploads/2016/05/Warm-Up-Ticket-Napa-Great-Shake.pdf

"Hydraulic detention time (HDT) also known as hydraulic retention time (HRT) is a measure of the average length of time that a compound (in this case wastewater) remains in a treatment tank or unit. Simply stated if you started to fill a tank with wastewater the detention time is the average amount of a time that a drop of that water will remain in the treatment tank before the tank fills and that drop of water flows out of it. This is important because as wastewater passes through a treatment tank it must stay in the tank for the necessary period of time in order to be adequately treated."

What your teacher did was converting liters to cubic meters and days to seconds, then calculating how much volume of water would flow into a container during 60 seconds at that given rate of flow.

Now, regarding power, they will need to tell you the pressure loss inside that tank, if they are referring to pump power.

Please, see:
https://www.engineeringtoolbox.com/pumps-power-d_505.html

As they give you the temperature of the water, you can estimate its density.
 

1. How do I calculate the volume of a tank?

The volume of a tank can be calculated by multiplying the area of the base of the tank by its height. For a cylindrical tank, the formula would be V = πr^2h, where r is the radius and h is the height. For a rectangular tank, the formula would be V = lwh, where l is the length, w is the width, and h is the height.

2. How do I determine the power requirement for a tank?

The power requirement for a tank depends on several factors, including the volume of the tank, the type of fluid being stored, and the desired temperature change. To determine the power requirement, you would need to calculate the heat transfer rate using the formula Q = mcΔT, where Q is the heat transfer rate, m is the mass of the fluid, c is the specific heat capacity of the fluid, and ΔT is the desired temperature change. You would also need to consider the efficiency of the heating or cooling system being used.

3. What units should I use to measure tank volume and power requirement?

The units used to measure tank volume and power requirement will depend on the specific situation and the units used in the calculations. However, common units for tank volume include cubic meters, liters, and gallons. Power requirement is typically measured in watts or kilowatts.

4. How do I account for insulation when calculating tank volume and power requirement?

If the tank is insulated, you will need to take into account the thermal resistance of the insulation material. This can be done by using the formula R = L/k, where R is the thermal resistance, L is the thickness of the insulation, and k is the thermal conductivity of the insulation material. You would then need to adjust the heat transfer rate calculation accordingly.

5. Are there any online calculators or tools available for determining tank volume and power requirement?

Yes, there are many online calculators and tools available for determining tank volume and power requirement. These tools can be helpful in quickly calculating the required values based on the specific inputs provided. However, it is important to double-check the results and ensure that the correct units are being used.

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