11
votes
Accepted
Block diagram vs flow chart?
Use Google's define:<item to look up> feature.
block diagram
noun: block diagram; plural noun: block diagrams
a diagram showing in schematic form the ...
- 10k
10
votes
Do I need a pressure relief/safety valve if my pump can't exceed the rated system pressure?
Not a plumbing engineer, but:
What about thermal expansion?
You reach a dead end, pump stops. Pumps often have a checkvalve that prevents backflow, so you have now created a pressurized container.
...
- 109
9
votes
What is the correct pipe size for a 2inch pipe?
As of the 2013 edition of ASME B16.5, the scope section explains:
This Standard states values in both SI (Metric) and
U.S. Customary units. As an exception, diameter of bolts
and flange bolt ...
- 4,531
7
votes
Accepted
Does every engineering design needs to have a complete theoretical backing or may experimental data suffice?
Are any designs based solely on data from trial and error used in critical mainstream engineering?
Usually not. And the reason is that trial and error is expensive and time consuming. As engineers, ...
- 2,646
6
votes
Accepted
What is the correct pipe size for a 2inch pipe?
I would guess that the discrepancy is down to rounding fractional inch sizes to decimal inches ie 2.38 is not exactly 2 3/8"
Note that 2.375 (two and three quarter eighth inches) is 60.325mm
- 15.1k
5
votes
Accepted
How do temperature and pressure influence the rate of evaporation of water in a closed vessel?
$\frac{1}{22.4}\frac{\mathrm{mol}}{\mathrm{L}}$ is only valid for standard conditions. Use the ideal gas law to calculate the concentration for your conditions.
$s \equiv$ standard conditions
$2 \...
- 1,734
5
votes
Accepted
How to prevent static buildup in an electric burr mill coffee grinder?
What is the cause of this static charge in the grinding process?
My thought is that the coffee grinder is essentially acting like a Van de Graaff generator. Since the coffee maker likely has a ...
- 3,587
4
votes
Accepted
Real world applications where one would use a force function in PLC programming?
A "force" in a PLC is the act of forcing a memory bit on or off from the PLC programming software. It is used exclusively for testing. Forcing a bit on or off over-rides all other PLC logic. You can ...
- 7,794
4
votes
Do I need a pressure relief/safety valve if my pump can't exceed the rated system pressure?
Certainly not all piping systems need relief valves. The specifics of the application matter. Relief valves typically protect vessels that can store significant energy and release it violently at ...
- 6,248
3
votes
How do you get a closed vessel to >90,000 psi internal pressure
Contact an engineering firm with experience designing and building such systems and vessels to code. Otherwise, you're just building a bomb.
- 2,135
3
votes
Boiling Point, Pressure and Distillation
In ambient pressure, ethane boiling point is -89 °C; ethylene boiling point is -103.7 °C. Water, to act as efficient coolant needs to be liquid, so above 0 °C. You're not going to condense ethane ...
- 6,125
3
votes
Valve first,then heat exchanger OR heat exchanger first then valve
I think the key information is that the liquid is saturated. This means any reduction in pressure will lead to partial vaporization and two phase flow.
For heat tranfer best overall heat transfer ...
- 121
3
votes
Accepted
Mass Transfer from an Oxygen Bubble
Your approach is wrong because the left hand side represents the derivative of the composition of two time dependent functions. You completely ignored that fact and started cancelling terms. I try to ...
- 1,734
3
votes
Accepted
Modelling gas desorption from a still solution (e.g. a beer)
In perfectly stagnate gas systems, transport of a component through a gas collapses to diffusion of the component through the gas. In this case, $k_L a \propto (D / \delta)^n$ where $D$ is diffusion ...
- 2,878
3
votes
What is the fouling effect (in rate, foulant thickness) of sand inside tube side of a shell and tube heat exchanger?
There is quite a bit to unpack here, so I may need to deconstruct your question a bit. Your question is surrounding the fouling rate of a Shell & Tube (S&T) heat exchanger which I will get to, ...
- 605
2
votes
Accepted
Steam sterilization of whey in a bioreactor
It all depends on the sterilization level you want to achieve. As you say, you would need to know the death kinetics parameters, or equivalently the log-decimal reduction time (D) and how it changes ...
- 335
2
votes
Sizing a pressure safety valve for two-phase flow
While designing a relief the valve flow rate is the deciding variable. To calculate its value in two phase flow different models can be used like HEM, drift flux, separated flow, etc. For this ...
2
votes
Baffle vs Bottom Temperature Measurement/Control
When there is a change of temperature of the reactor contents, which sensor detects the change first?
The quicker the effects of a change can be detected, the more responsive the control system and (...
- 533
2
votes
Recommended models for mineral liberation in crushers
You might want to look up the the "Bond Work Index". It's an empirical method for understanding the energy required to achieve certain amounts of comminution (think P80) for a given method and mineral....
- 131
2
votes
Gas cleaning in activated carbon filters - How much moisture is needed and why?
In terms of bed capacity, dry gas—0% moisture, or as close as you can get—is generally optimal. Section 12.4 of Air Pollution Control (Cooper & Alley, 4th ed.) characterizes the impact of several ...
- 3,211
2
votes
Accepted
Problem with process controls/simulink?
Time Constant and systems
A second order LTI system in Laplace domain:
$\hspace{2.5em}$ $H(s) = \frac{{\omega_{n}}^{2}}{s^{2}+\zeta\omega s+{\omega_{n}}^{2}}$
The solution is:
$\hspace{2.5em}$ $h(t) = ...
- 122
2
votes
Accepted
Derivation of Overall Mass Transfer Coefficient
Regarding $k_p$:
So, you've got $N_1$ a flux in $mol/ s \cdot m^2 $ and a partial pressures $p_i$ in $Pa$. $k_p$ has got to connect those, and make the units work out.
Exactly what $k_p$ is depends ...
- 1,976
2
votes
How do you calculate the required power of a disk turbine (Rushton turbine) to rotate a fluid at a given speed?
We have a fair share of questions about how to calculate maximum speed, but the fact remains that this is extremely hard calculation to make. See a mass will continue to accelerate until the losses ...
- 3,561
2
votes
Entrainers to distill MTBE from Methanol? - Chemical Engineering Question
Few points:
First off, see if you can figure out a way to NOT use MTBE in the first place since it is not an environmentally friendly chemical.
That being said, in dealing with separating azeotropic ...
- 131
2
votes
Modelling reactor jacket with or without insulation, how to proceed?
Full Analysis
Perfectly Insulated System
The best case is to analyze this system in both the time and position domains. The time domain considers the variation of the reactor temperature $T_r(t)$ ...
- 2,878
2
votes
Accepted
How exactly do noise canceling headphones work?
Briefly they take the waveform of the ambient noise then produce the inverse waveform which is then generated. The two waveforms effectively cancel out leaving a much quieter ambient sound level.
The ...
- 15.3k
2
votes
Block diagram vs flow chart?
The ISO EN 10628-1 has this example for a basic flow chart (which block diagram may also refer to):
The blocks can be unit operations, processes, or parts of a plant, the lines can be material or ...
- 4,705
2
votes
How to add a controlled amount of a nutrient solution to a water line
Our water purification system uses an injection pump, in this case a diaphragm style pump. It has a control for volume dispensed during operation. The operation is limited to when water is flowing by ...
- 6,860
2
votes
Identification a Symbol for P&ID's Standards
I would guess it's a non-standard symbol for a check valve. @NMech is correct that it looks like a diode, but that would not appear on a P&ID. A check valve is a fluid flow equivalent of a diode ...
- 1,022
2
votes
Accepted
What type of electrical machine component for counting time?
Omron makes a wide variety of industrial timer modules which can count down a preset number of tenths of a second all the way to hundreds of hours and then close or open a set of switch contacts and ...
- 14.1k
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