9 replies to this topic

[lanna_samsolbahri]

Dear Ladies & Gents,

Good day all! My name is Lanna, a Final Year Undergrad taking Chem Eng @Universiti Teknologi PETRONAS, Malaysia. I need to get some input from anybody to produce mechanical design of hydrocyclone.

Background of my Plant Design Project:

In a team of 5 people, we need to produce a detailed plant design of "Biodiesel Plant using Waste Cooking Oil as Main Feedstock, undergoing Homogenous Transestericiation Reaction".

Background of transesterification reaction:[/b]

Waste Cooking Oil will react with Methanol, in the presence of H2SO4 as homogenous catalyst producing Methyl Oleate (FAME) which is the Biodiesel.

[b]Background & purpose of hydrocyclone:

This hydrocyclone design is planned to separate CaSO4 precipitate in the main stream. CaSO4 formed by neutralization reaction of H2SO4 with CaO. H2SO4 is used previously as homogenous catalyst for transesterification reaction of WCO with methanol.

Below is the properties of the inlet stream of hydrocyclone as simulated using iCON PETRONAS software:

STREAM 16
PARAMETER UNITS
TEMPERATURE deg C 75.0
PRESSURE kPa 110.0
MASS FLOW kg/hr 8819
MOLAR FLOW kgmole/hr 64.99

MOLE FRACTION
Methyl Oleate 0.29249
Methanol 0.14845
Oleic Acid 0.00000
Sulfuric Acid 0.00000
Water 0.23988
Glycerol 0.09693
Di-olein 0.00000
CaO 0.00006
Calcium Sulphate* 0.22122
Triolein 0.00097

*CaSO4 = hypothetical compound

Background of problem that I'm facing:

(1) I'm not so sure whether at this temperature (75 degC) and this mole fraction (0.22122), CaSO4 exists as solid precipitate or still in aqueous solution? Because if I'm not mistaken, CaSO4 at certain temperature and at certain concentration only will be able to form precipitate or crystals.

(2) In our simulation, we specify our assumption that 100% separation of CaSO4 can be achieved and we proposed to used Hydrocyclone to accomplish this separation. However, I couldn't find any textbooks / technical papers presenting equations related to design hydrocyclone until today.

Appreciate if anybody can help to answer my inquiries here.

Thank you.

[Andree]

1. You must find out what the solubility of CaSO4 in your liquid phase. It can be impossible to dig out any reliable value when your liquid is multicomponent mixture - hence this data should probably be established experimentally. For your task (as this is a student project) try to assume something

2. The efficiency will depend on inlet velocity (or pressure) and on size of precipitated solids. Hence, the problem is very complex, because size of particles will depend on many parameters which affect precipitation process and you obtain a size distribution of CaSO4 particles.
For a given size you can calculate efficiency from commonly used relation of Leith and Licht, so for minimum size of your crystals should correspond to 100% efficiency.
Moreover, classic approach as proposed by Leith and Licht does not take into account shape of precipitated solid and this influences drag coefficient and is very important from the point of view of their motion within the cyclone body.

[Padmakar Katre]

Dear,
Here you could find some information.
http://www.krebs.com...ct_cyclones.pdf
http://www.onemine.o.....nes arterburn
or you can find some literature in the books by Chemical Process Equipment Selection and Design by Stanley M Walas and the other book by Nicolas Chemishrooff.

[lanna_samsolbahri]

Dear Padmaker,

Thank you very2 much..Ur link is very helpful.
I'll try to use those recommended literature for my hydrocyclone design 1st.
In case I got stuck again, I hope u don't mind to help me to resolve the probs.

Thank you, Padmaker~

Dear,
Here you could find some information.
http://www.krebs.com...ct_cyclones.pdf
http://www.onemine.o.....nes arterburn
or you can find some literature in the books by Chemical Process Equipment Selection and Design by Stanley M Walas and the other book by Nicolas Chemishrooff.

[Padmakar Katre]

Dear lanna_samsolbahri,
I am glad to know to know that my sussgedsted commnets helped you to saolve your issue. ANd yes you are always welcome with the new queries if you find in future.
All the best.

[Dr.Process]

Dear Padmaker,

Do you have an excel spreadsheet for sizing multi liners hydrocyclone in produced water treatment including calculation to determine no. of liner? And do you have any reference on what type of booster pump should be used upstream of HC? Do I need to install another pump for oil reject line that goes back to separator inlet?

The produced water feed = 20MBWPD, 1.04 SG
Production separator design P =125psig @100 F
Produced water outlet from separator = 12" class B

Thank you

Dear lanna_samsolbahri,
I am glad to know to know that my sussgedsted commnets helped you to saolve your issue. ANd yes you are always welcome with the new queries if you find in future.
All the best.

[kkala]

Probably helpful additional notes on the query (precisely presented) are as below.
1. "Hydrocyclones" by L. Svarovsky (1984) was considered as rather classical book on hydrocyclones. You may be lucky enough to trace it in some local library. Searching in http://www.bookfinder.com also reveals another book of same author (I was not aware of it), reporting a 1992 conference.
2. I used published data from hydrocyclone suppliers in ~1980, when I had to estimate their performance. Their leaflets (or their web sites nowadays) gave adequate data, though I also contacted local representative for the arrangement.
3. Light & Licht presented a model for aerocyclones, see http://www.progepi.f...ion-cyclone.pdf. I believe that hydrocyclone efficiency cannot be calculated same way as aerocyclone's, but there may be different opinions on this matter. Advice from others welcomed.
4. CaSO4 solubility in water can be found in http://www.sciencedi...378381206001695, but it is not free. Limited solubility data at http://en.wikipedia....Calcium_sulfate. The data indicates precipitation of CaSO4 in the form of gypsum (CaSO4*2H2O), since temperature is below 80 oC. This under the assumption that CaSO4 is not soluble (or is sparingly soluble) in organics of stream 16. The limit of ~80 oC for gypsum is from some knowledge on phosphoric production plants (1980), where gypsum precipitates.
5. The smaller hydrocyclone diameter the higher its efficiency, so these are often used in groups (multi cyclones). Problems in multicyclones are scales and uneven flow distribution of incoming liquid. At any case hydroclones require a rather high pressure drop to be effective. Reported pressure of 110 kPa (1.1 Bar) is not expected to be enough, even if it is gauge pressure (1.1 Barg). You may need a pump to increase pressure to the level estimated by the design of hydro cyclones.
6. Using filters for separation of gypsum, may be a another option, worthy of investigation. Rotary disk filters (one by Krebs) were used for gypsum separation in phosphoric acid production (1980). Pulp was thrown onto first sector, gypsum was repeately washed in next sectors, then rejected. Problems of specifying crystal size and shape would be less serious compared to hydrocyclones.

Edited by kkala, 14 July 2011 - 12:43 AM.

[Profe]

Hi Lanna

In Perry, Chemical Enginering Handbook you find the solubility for Calcium sulfate, that I put next:

Solubility is in Grams per 100 mililiters of saturated solution.
0 °C: 0.1759
10 °C: 0.1928
30 °C: 0.2090
40 °C: 0.2097
60 °C: 0.2047
70 °C: 0.1966
100 °C:0.1619

The calcium sulfate is an inorganic compound and its not soluble in organic solutions. I think that its ok separate by filtration.

Good Luck.

Fausto

[murrali2002]

The hydrocyclone design equations and articles presented in this forum was very useful. It helped me to do a basic design calculation of hydrocylone for my process (solid separation from miscella).

Thank you.

[Winston P. Ekpotu]

Hello everyone,

I am a final year student of Chemical Engineering in the University of Nottingham UK. I am currently doing my final year design project which involves the design of a hydrocyclone for separation of solids from slurry.
The total flow is about 5000 L/min, and the density difference is about 0.6g/cubic cm. Based on the Bradley Design equations, I got a diameter of about 55 cm, and a pressure drop of about 65 psi. Since I have not had any hands on experience with this equipment, I don't know how realistic this value is.
The efficiency of separation I hope to achieve is 99%
Can you offer any advice?

Regards
Winston