Questions tagged [chemical-engineering]

Use this tag for questions within the problem domain of chemical engineering.

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Distillation modelling McCable Thiele, Chemical Engineering

I am using an extractive distillation column to seperate ethanol and ethylene glycol. I am trying to find Rmin however its proving difficult as the the top operating line, q-line and bottom operating ...
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16 views

What is the energy and capital cost of NH3 from Haber Bosch plant that takes in pure H2 and N2?

A question that becomes particularly relevant for "the hydrogen economy" or in the event that IGCC coal baseload electric generation seeks off-peak markets for hydrogen. I can't seem to ...
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1answer
45 views

Elution from an Ion Exchange Column

I am using concentrated NaCl(10%) to elute Cobalt (II) ions from a cationic exchange column. How would I determine the volumetric flowrate of regenerant needed to completely elute the cobalt ions from ...
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1answer
811 views

Entropy change in a throttling process

In an adiabatic throttling process of ideal gas: I understand that mathematically lost work is given by Tsurr * entropy generated. But intuitively I can't understand if there is not heat exchange ...
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1answer
131 views

Calculate the specific surface area of a mesoporous sample

I'm a nanoengineering student who's been stuck on the following problem for a few days. I've gone back over my professors slides, watched podcasts from an old professor, etc. etc., but don't ...
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1answer
47 views

Doubt regarding meta-stable and labile region of a supersaturated solution

I have read in a paper that the for formation of new crystals in a solution the energy released due to formation of solid from solution should be more than the energy needed to overcome solid-liquid ...
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0answers
23 views

Calculating estimated Overall Heat Transfer Coefficient

I have problem where I'm trying to determine the Overall Heat Transfer coefficient of a heat exchanger that uses the latent heat of vaporization of water in the process. I know the Q value I'm trying ...
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0answers
15 views

Determining length of interstage cooling coils for removal of heat

I'm currently trying to determine the length of cooling tube required to remove a specific amount of heat from my exothermic reactor in stages. I'm aware I need to use the equation $Q = UA \theta_{...
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1answer
30 views

How can I calculate the density of air?

I major in chemical engineering, and I'm solving a example of unit operations. The textbook is Warren L. McCabe, Unit Operations of Chemical Engineering 7th ed. Here is example 24.1. And this is its ...
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1answer
41 views

How to compute velocity distribution in the developing boundary layer on the cylinder

Air flows perpendicular to the axis of a cylinder $a=1$ cm in diameter. Air speed upstream of the cylinder is $U=6.72$ mm/s and its kinematic viscosity is $2.1×10^{-5}$ at 350 K. I want to obtain the ...
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2answers
87 views

Eulerian description of fluid flow

In Eulerian description of fluid flow, we observe how the properties of the fluid are changing at a point. Since a point has zero dimension hence a zero area, how can we make sense of the 'finite ...
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9answers
35k views

Why do glass windows still exist? (Why haven't they been replaced by plastics?)

Glass is fragile and impractical to transport, install and repair. Even worse, glass kills and hurts people when it breaks. Falling to the streets like guillotines during earthquakes and bomb raids. ...
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1answer
138 views

How to calculate initial concentration of first-order reaction in CSTR?

(This question comes from a Chemical Engineering background, but basic Math and Programming knowledge is also required. I hope it still falls in the scope of engineering.stackexchange.com If not, ...
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1answer
88 views

Is it possible to use direct air capture technology for CO2 on a non-commercial level?

CO2 is used as fertilizer in aquariums where it's brought into the water with diffusors from compressed form in cylinders. Direct Air Capture machines for CO2 have been presented for experimental geo-...
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2answers
159 views

Second Order Transfer Function Question regarding Overshoot Formula

If I have a closed loop second order transfer function such as: $$T(s) = \frac{10-s}{0.3s^2+3.1s+(1+24K_{c})}$$ Can I still use this formula for overshoot (when a step input is applied) ?: $$\frac{A}...
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1answer
57 views

What is the effect of different ways to adding liquid materials into a mixing tank?

I am working with body wash products and there is a problem happening with the mixing process. I use a 5000-liter tank to mix all the liquid materials including water, surfactant and preservatives. ...
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1answer
48 views

How to calculate a gas burner dimensions?

I am trying to calculate the dimesnions of a natural gas burner for a hospital. The burner will be heating water. I have calculated the thermal duty that needs to be produced and the water mass flow, ...
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1answer
40 views

the volume in hydraulic retention time is of reactor/container or liquid

I have a tiny reactor, and the volume I need is 425ml. If there is no/few other reactants, then the volume in hydraulic retention time is clear: reactor/container's ...
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1answer
39 views

How can I confirm nL Volume Measurement for Pump and Sensor Calibration

I'm dispensing around 1uL of volume with 1% accuracy. Although I'm confident in my pump, I'd like to be able to routinely confirm that I'm getting the exact volume I'm requesting every time. How can ...
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1answer
246 views

Custom User Models in Aspen Plus

I'm trying to simulate a purifier in Aspen Plus in a cryogenic system. This purifier is just meant to change the pressure of the outlet stream based on the inlet flow and pressure (we are using the ...
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1answer
440 views

Fluid dynamics of non interacting tanks in series

I have a system like this: and I have to estimate the height of the lower tank. First of all, I'm considering that I have a non-viscous, incompressible fluid in steady flow. Base apertures The ...
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1answer
40 views

How can the air pressures exiting from a blower be adjusted?

During this covid-19, I was thinking about designing a low cost simple ventilator using a blower. There is a limit of the inspiratory and expiratory pressures, the inspiratory pressure being higher. ...
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0answers
25 views

P&ID questions on reports, connection, etc

Good day to all of you. I got some questions in my mind regarding on P&ID: In electrical, symbol will have their own default reference name for example "Motor" will use "M" , ...
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1answer
50 views

How to identify the time delay of manipulated variables which are important to the final quality of polymer product

In a polymer production process, there are a lot of manipulated variables(MV) such as temperature ,pressure , or level of reactor that affect the quality of my polymer product. However, it usually ...
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2answers
80 views

chemical reaction engineeing

What is the definition of rate $(−ra)=−\frac{dCa}{dt}$ or $(−ra)=−1/V\frac{dNa}{dt}$ ? I think the general one is the second one and first one is for constant volume reaction system. Is the above ...
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0answers
40 views

Navier-Stokes with non-newtonian fluids

So I've got a problem here in fluids. It's driving me insane but I know I'm missing something simple. Up until now we've worked with Newtonian fluids resulting in the "normal" NS equations ...
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1answer
46 views

Recommended books for process engineering? [closed]

I made a career change from machine design to CNG processing. What I’m looking for are some good books/handbooks that cover the following topics. Something similar to Machinery’s Handbook. Piping, ...
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1answer
65 views

How to derive phase equillibrium criteria for more than 2 phases mathematically?

I know the derivation of phase equilibrium criteria derivation for 2 phases. I am not getting how to extend the derivation to more than 2 phases. Please help me out on that. Thank you
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1answer
63 views

Theoretical maximum pressure from combusting LPG

I am curious how to find or estimate the theoretical maximum pressure that the combustion of a LP gas, such as propane, can produce inside of a constant volume, such as in a cylinder. I know what the ...
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1answer
33 views

Is molecular dynamics relevant for an undergraduate Mechanical Engineering degree? [closed]

I am completing my final year undergraduate study in Mechanical Engineering. I've had to have a scope change because my last project was not going to work with the pandemic. I've been given a project ...
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1answer
41 views

Gaps in derivation of thermodynamic property equations

If $h=h(T, P)$. Does $ dh = c_pdT + \left[v - T\left(\frac{\partial v}{\partial T}\right)_P \right]dP \Rightarrow h_2 - h_1 = \int_{T_1}^{T_2} c_pdT + \int_{P_1}^{P_2}\left[v - T\left(\frac{\partial v}...
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1answer
30 views

Determine in and out momentum in shell momentum balance [closed]

How to decide what is in momentum and what is out momentum in using shell momentum balance? My main motive is to understand why at 25:26 in the balance equation at https://www.youtube.com/watch?v=...
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1answer
221 views

Throttle vs Choke vs Damper vs Valve?

Throttles, chokes, dampers, and valves all restrict fluid flow. Aside from specific terminology/usage in internal combustion engines, are these really interchangeable terms, or do they have some ...
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1answer
44 views

Crossflow HX tube and fin, derive Tout hot side as a function of mdot hot side in

Apparatus: Crossflow Tube and fin HX. (liquid-to-air Intercooler), Hot Side: Tube side, gas flowing internally Cold Side: fin side, water flowing in crossflow Goal: Generate an environment in "...
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1answer
719 views

Safe temperature thresholds for #2 HDPE and #5 PP plastic

It would be convenient to use a temperature adjustable heat plate (element)/mug warmer for the massive amount of blender bottles accumulated over the years. What are safe thresholds to safely warm the ...
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2answers
484 views

head coefficient and volume coefficient for centrifugal pump

If I need to calculate the head coefficient using $c_h=\dfrac{gH}{N^2D^2}$ and the volume coefficient using $c_q= \dfrac{v}{ND^3}$ while keeping $N$ (impeller rotational speed in rpm), how can I make ...
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1answer
55 views

Ash size particle dependency of initial coal particle size in fluidized bed combustors

I'm looking for information on coal ash size in fluidized beds. How dependent is it on the initial coal particle size? Would I expect ash from 5mm coal particles to be significantly larger than ash ...
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1answer
38 views

Can I calculate the amount (mol or mass) of water in a gas, in a heat exchanger, if I know the partial pressure of the water?

Is it possible to calculate the amount of water (mol, mass...) in a gas, in a heat exchanger, if I know the partial pressure of the water? The stream through the tubes is mainly benzene and ...
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1answer
54 views

sinking speed of particle in water

For a Newtonian fluid the sinking final speed of a metal particle is given by this equation : while g is Gravitational acceleration , $\rho_P$ = is particle density , $\rho_F $ = is fluid density ,...
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1answer
54 views

How do I calculate the density of a lined pipe?

I'm having some trouble figuring out how to calculate the density of a lined pipe given the diameter measurements and the specific gravity of the materials. The Problem Calculate the density of an ...
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1answer
75 views

Help with Mass Flow Rate

I'm a beginner in chemical engineering so apologies in advance if this question is very basic! The Problem You are required to measure the mass and volumetric flow rate of a slurry stream. The slurry ...
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1answer
50 views

Need help with an essay question related to chemical engineering (High School)

I have to do an essay question related to an area of my choice (Chemical Engineering). Could anyone suggest an area of research that is accessible to a High Schooler within ChemEng? Thank You
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1answer
45 views

Advantages of hydrogen gas turbine over fuel cell

In the setting of large-scale electricity generation, I was wondering why one would want to burn hydrogen in a gas turbine instead of using it to power a fuel cell. Aren't fuel cells more efficient ...
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3answers
352 views

P&ID Symbol identification, unknown meaning

I'm aware that answers may vary and it really does depend on the company/country where the PID was drawn but I have checked back for the last 30 years and found no drawing legend that describes what ...
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1answer
519 views

How to calculate kinetic energy of gas flow in pipe given tempearture, pressure, pipe diameter and velocity

Ive been given a question and asked to calculate the kinetic energy of a gas given the temperature, pressure, diameter of pipe and velocity. I've been looking and have been unable to find any ...
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0answers
16 views

Macro to atomic scale software

Is there a software that exists that takes a macro object for example a MacBook casing and its composition (Aluminum) and allow you to zoom between the macro scale (a fully rendered MacBook) and the ...
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3answers
82 views

How do you determine how many pumps you need in a pipeline?

I am working on a pipeline design scenario and I am trying to determine how many pumps I need. In addition to this diagram, I'm given a flow rate range and an acceptable velocity to also determine the ...
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0answers
11 views

How is EPD different / related to anodising?

What is the process of applying dye to anodized surfaces (specifically aluminum)? Is electrophoretic deposition (EPD) just the process used to apply the dye to anodised surfaces? Or is it a ...
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2answers
188 views

Increasing Kd in PID control loop

Why does increasing derivative gain $K_d$ in a PID controller loop lead to a reduction in overshoot and an increase in rise time? This is not a homework question, it is a question to improve my ...
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0answers
35 views

Considerations for switching from Conc. Sulphuric acid to Oleum

First off - this project is still in the early planning stages. The basic scope is that a plant want's to switch from using conc. sulphuric acid (~98%) in its process (nitration) to oleum. I ...

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