ĐỒ ÁN QUÁ TRÌNH THIẾT BỊ HẤP THỤ CO2

Huynh Lien HuongConsider input solvent is clean solvent Outlet data: Concentration of outlet CO2: = Molar of CO2: Molar of air mixture: Flow rate of inlet gas: Flow rate of inert gas:

CONTENT

LIST OF FIGURE

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LIST OF TABLE

LIST OF ACRONYMS

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ACKNOWLEDGE

A completed study would not be done without any assistance Therefore, theauthor who conducted this research gratefully gives acknowledgement to their supportand motivation during the time of doing this research

First of all, I would like to express my endless thanks and gratefulness to mysupervisor Assoc Prof Huynh Lien Huong Her kindly support and continuousadvices went through the process of completion of my project Her encouragement andcomments had significantly enriched and improved my work Without her motivationand instructions, the project would have been impossible to be done effectively

My special thanks approve to my parents for their endless love, care and havemost assistances and motivation me for the whole of my life I also would like toexplain my thanks to my siblings, brothers and sisters for their support and care me allthe time

As last, my deeply thanks come to all my friends during time I studied this

project Their kindly help, care, motivation gave me strength and lift me up all the trouble for the rest of my life

CHAPTER 1 INTRODUCTION

1.1 Introduction packed column

Packed columns are used for absorption, adsorption, distillation and other processes[1] The column is cylindrical; the inside is filled with cushion There are many types of cushions, the most common being the following:

- Ring packed, size from 10 ÷ 100mm.

- Grain packed Size is from 20 ÷ 100mm.

- Twisted packed, size from 0.3 ÷ 1mm, diameter of coil size 3 ÷ 8mm, length not more than 25mm

- Wooden mesh packed.

All of the above types of packed have common requirements:

- Large individual surfaces (symbol δ, dimension m2 / m3)

Large free volume (symbol Vfree, dimension m2 / m3)

- Small individual weight.

- Chemically stable.

In fact, there is no type of pack that meets all the above requirements,

so depending on the specific conditions, choose the appropriate type of cushion.

Packed column has the following advantages:

- Having large, high efficiency phase contact surface.

- Simple structure.

- The resistance in the column is not very large.

- The working limit is relatively wide.

However, the disadvantage of the packed column is that it is difficult

to evenly wet the mattress[2] Therefore, if the column is too tall, the liquid

is not evenly distributed Therefore, one had to split the floor and put a liquid dispenser on each floor.

1.2 Introduction carbon dioxide:

1.2.1. Properties of Carbon dioxide (CO 2 )

Carbon dioxide (chemical formula CO2) is a colorless gas with a density about 53% higher than that of dry air[3] Carbon dioxide

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oxygen atoms It occurs naturally in Earth's atmosphere as a trace gas The current concentration is about 0.04% (412 ppm) by volume, having risen from pre-industrial levels of 280 ppm Natural sources include volcanoes, hot springs and geysers, and it is freed from carbonate rocks by

dissolution in water and acids Because carbon dioxide is soluble in water,

it occurs naturally in groundwater, rivers and lakes, ice caps, glaciers and seawater It is present in deposits of petroleum and natural gas.

Table 1-1 Properties of CO 2 gas

Properties

and −78.5 °C)

• 1101 kg/m3 (liquid at saturation −37 °C)

- Carbon dioxide is soluble in water and react with base, base oxide and salt.

1.2.2. Production carbon dioxide (CO 2 )

- CO2 appear in the burned process organic material

•

•

- Carbon dioxide is a by-product of the fermentation of sugar in the

brewing of beer, whisky and other alcoholic beverages and in the

production of bioethanol

- Carbon dioxide is a byproduct of the industrial production of hydrogen

by steam reforming and the water gas shift reaction in ammonia

production.

1.2.3. Effect of carbon dioxide in environment and human.

- Environment: Carbon dioxide contributes to air pollution in its role in the greenhouse effect Carbon dioxide traps radiation at ground level, creating ground-level ozone[3] This atmospheric layer prevents the earth from cooling at night One result is a warming of ocean waters Oceans absorb carbon dioxide from the atmosphere However, higher water temperatures compromise the oceans' ability to absorb carbon dioxide Over time, the effects of carbon dioxide are compounded

- Human: The concentration of CO2 in the air is 0.004% If this concentration is higher than this value, Carbon dioxide emissions impact human health by

displacing oxygen in the atmosphere Breathing becomes more difficult as carbon dioxide levels rise In closed areas, high levels of carbon dioxide can lead to health complaints such as headaches Carbon dioxide levels may indicate high levels of other harmful air pollutants such as volatile organic compounds which contribute to indoor air pollution.

1.3 Methods of treatment of CO2

1.3.1. Absorbs CO 2 gas with water

Absorption of CO2 gas by water is one of the simplest methods applied earliest to remove CO2 in exhaust gas, especially in the exhaust fumes of

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The CO2 water treatment system consists of 2 phases:

- Absorbs CO2-containing flue gas by spraying water into the flue gas stream or passing the exhaust gas through a layer of watering buffer (hollow material) - scrub[5].

- Release CO2 gas from absorbent to reuse clean water and recover CO2 (if necessary)

Dissolved concentration of CO2 in water decreases as the water

temperature increases, so the temperature of the water supplied to the system used to absorb CO2 must be low enough In order to reuse water, to release CO2 gas from the water, the temperature of the water must be high Specifically, when at a temperature of 100 ° C, CO2 evaporates completely and in the escape gas stream there will be water vapor And by condensation method, CO2 gas with very high concentration will be obtained for use in sulfuric acid production purpose

A theoretical equal amount of water is required to absorb 1ton CO2 to saturation with different temperature and CO2 concentrations in the exhaust gas From the aforementioned disadvantages, this method of absorbing CO2 with water is only applicable when:

- Initial concentration of the exhaust gas has a relatively high concentration of CO2;

- When a cheap heat source (steam) is available;

- When cold water is available;

1.3.2. CO 2 gas treatment with limestone

The absorption and treatment method of CO2-containing exhaust gas is as follows: The exhaust gas passes through the bottom-up absorption column treatment system, in which pollutants such as CO2 and dirt are trapped, the clean air goes up and out Absorbent solution (usually Ca(OH)2) is pumped by the duct system, circulating pumped on the upper part of the cylinder body and sprayed

by a mist system, evenly irrigated with the absorbent in the column The gas flows from the bottom up, the liquid flows from the top down and they touch each other, then the absorption process takes place, CO2 is trapped in the

absorbing solution, the clean air escapes.

2CO2 + Ca(OH)2 → Ca(HCO3)2

Ca(HCO3)2 + Ca(OH)2 → 2CaCO3 + 2H2O

CaCO3 is a low solubility solid, so it is easily deposited to the bottom of the column and is treated by burial

Clean air at the top of the column is dehumidified, then released into the environment.

1.4 Process technology

Figure 1-1 Technology process

Select the source of raw material is the exhaust gas from thermal power plants The pre-treated gas reduces the temperature of the gas coming out of the tube and filters the dust before treating it with an absorption device

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Choose water as CO2 absorbent solvent, because it is cheap, easy to find, non-toxic and non-corrosive to the device

Choose the CO2 absorption column packed column, because the structure is quite simple, the resistance in the gas phase is low and suitable for low productivity.

CHAPTER 2 CALCULATION

2.1 Calculation mass balance

2.1.1. Choosing inlet data

− Volumetric flowrate of inlet vapor: 300

− Concentration of inlet CO2:

− Concentration of outlet CO2: (TCVN 5939: 2005)

− Operating pressure P = 1 atm = 760 mmHg = Pa

− Inlet air temperature T = 30°C

− Inlet water temperature 29oC

Consider the column operate at low temperature and pressure, choosing the idealcondition

2.1.2. Nomenclature

− Flow rate of inlet vapor ()

− Flow rate of inlet liquid ()

− Flow rate of inert gas ()

− Molar concentration of inlet CO2 gas ()

− Molar concentration of outlet CO2 gas ()

− Molar concentration of inlet CO2 liquid ()

− Molar concentration of outlet CO2 liquid ()

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Consider input solvent is clean solvent

Outlet data:

Concentration of outlet CO2: =

Molar of CO2:

Molar of air mixture:

Flow rate of inlet gas:

Flow rate of inert gas:

Equilibrium line equation:

(Equation IX.4 page 140, Sổ tay quá trình và thiết bị công nghệ hóa chất ,2[6])

And:

(Henry’s constant at 30ºC – Table IX.1 page139 Sổ tay quá trình và thiết bị công

nghệ hóa chất ,2[6])

Operating line equation

(do )

(Equation IX.6 page 140 Quá trình và thiết bị công nghệ hóa học và thực phẩm,2[7])

Flow rate of minimize solvent:

Operating line equation:

(Table 1.5 page 14 Quá và thiết bị công nghệ hóa chất và thực phẩm3 [8])

Drawing the operating line and equilibrium line diagram.

Equilibrium line equation:

Operating line equation:

Table 2-2 Data of equilibrium and operating line

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Figure 2-2 Diagram of operating line and equilibrium line of CO2 – H2O

2.3 Viscosity and density of liquid phase and gas phase:

2.3.1. Gas phase

Density:

(Equation IX.102 page 183 Sổ tay quá trình và thiết bị công nghệ hóa chất,2 [6])

Viscosity:

(Equation I.18 page 85 Sổ tay quá trình và thiết bị công nghệ hóa chất, 1[9])

Where:

Molecular weight of gas phase, CO2, and air

Average viscosity of gas phase, CO2, and air at 29oC

(Calculating viscosity at 29 o C in table I.113; I.114 page 115 Sổ tay quá trình và thiết

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Where: a, average weight of CO2 in liquid phase,

và ,density of CO2 and water at 29oC

(Diagram I.1 page 6 Sổ tay quá trình và thiết bị công nghệ hóa chất, 1[9])

Average weight of CO2 in liquid phase:

Volumetric of air in column:

(Equation IX.101 page 183 Sổ tay quá trình và thiết bị công nghệ hóa chất,2[6])

Vd Volumetric of inlet air in operating condition

Vc Volumetric of outlet air in operating condition (m3/h)

(Page 183 Sổ tay quá trình và thiết bị công nghệ hóa chất, 2[6])

2.4 Reversional phase velocity

(Equation IX.115 page 187 Sổ tay quá trình và thiết bị công nghệ hóa chất tập 2 [6])

Where:

Gx , Gy: Flowrate of liquid and vapor

A = 0,022.

specific weight of vapor phase

specific weight of liquid phase

Viscosity of liquid phase at 29oC

viscosity of water at 20oC

Chose Ceramic Rasiga ring packed is put random packing

(Sổ tay quá trình và thiết bị Công nghệ hóa chất, 2 page 193[6])

flowrate of inlet and outlet liquid

flowrate of inlet and outlet gas

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Velocity of vapor in column

Prevent the reflux phenomenon

2.5 Calculation diameter and height column

: Heat tranfer of vapor phase

: Heat tranfer of liquid phase

Height of unit:

(Equation IX.75 page 177 Sổ tay quá trình và thiết bị công nghệ hóa chất, 2[6])

Trong đó :

: Slope of balance line

: Height of unit of vapor phase

: Height of unit of liquid phase

(Equation IX.76, p 177 Sổ tay quá trình và thiết bị công nghệ hóa chất ,2[6])

Where

: Coefficient of packed a = 0,123

: Wetting coefficient of packed

(Equation page 177 Sổ tay quá trình và thiết bị công nghệ hóa chất, 2[6])

Where :

Amount of liquid in column

: Section area of column

irrigation density

(Diagram IX.16 page 178 Sổ tay quá trình và thiết bị công nghệ hóa chất, 2[6])

Reynolds, Pry of vapor phase :

Dy diffusion coefficient of gas phase (

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(Equation VIII.5 page 127 Sổ tay quá trình và thiết bị công nghệ hóa chất , 2[6])

Where

T = 273+30 = 303 K

P = 1 atm = 1,03 at diffusion pressure

(Tab VIII.2 page 127 Sổ tay quá trình và thiết bị công nghệ hóa chất , 2[6])

(Equation IX.77 page 177 Sổ tay quá trình và thiết bị công nghệ hóa chất, 2[6])

diffusion coefficient in water at 29oC

Where

: Molar volumn of diffusion

(Equation IX.70 page 175 Sổ tay quá trình và thiết bị công nghệ hóa chất , 2[6])

Y operating component of liquid phase

Ycb operating component of vapor phase

Determine the number of mass transfer units according to graph analysismethod

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He

packed layer: , Devided the packed layer into 3 part A height of part

Total height of column:

• Height of bottom = Height of lid:

• Height of between 2 packed layers: (m)

• Height of packed-lid: m

• Height of packed-bottom: m

Vậy chiều cao tổng của tháp là

Choose the height of column is 8m ( except the height of lug support)

Table 2-4 Diameter and height of column

2.6 Resistance force

Loss presure of wet packing layer:

(Equation IX.121 page 189 Sổ tay quá trình và thiết bị công nghệ hóa chất tập 2[6])

(Table IX page 189 Sổ tay quá trình và thiết bị công nghệ hóa chất, 2[6])

Total resistance force:

2.7 Mechanic calculation

2.7.1. Body of column

Prevent to corrosive phenomenon, chosing the vapor pipe with X18H10T stainlesssteel, heat resistant, acid resistant

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Selecting machining technology is manual welding by electric arc, by welding sided joints

two-Correction factor:

Towing safety factor:

Flow safety coefficiency:

Durability joint coeficiency :

Relative elongation:

(Table XIII.2 và XIII.3 page 356 Sổ tay quá trình và thiết bị công nghệ hóa chất ,2[6])

Because the working environment is a mixture of steam - liquid, the workingpressure is equal to the total steam pressure and the hydrostatic pressure of the liquidcolumn so we have equation:

(Equation XIII.10 page 361 Sổ tay quá trình và thiết bị công nghệ hóa chất ,2[6])

The minimum thickness of column:

(Equation XIII.8 page 360 Sổ tay quá trình và thiết bị công nghệ hóa chất ,2[6])

Where:

: Coefficient of addition due to chemical wear over time of use Assuming theequipment is used for 20 years with the corrosion rate of 0.1mm / year

: Coefficient of addition due to mechanical

: Additional coefficient due to tolerance (table XIII.9 page 364, sổ tay QTTB 2[6])

: Dimension round coefficient

The real thickness of absorption column:

Check the durable condition:

Satisfied the conditions

Check the pressure of column:

Satisfied the conditions

Dt h

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2.7.2 2.7.2 2.7.2 2.7.2 2.7.2 2.7.2 2.7.2 2.7.2 2.7.2 2.7.2.

The bottom and lid of column

Figure 2-3 Data of column

Choose X18H10T steel for lid and bottom column

Internal pressure = 1,013 atm >> 7,104 Ellipse lid and ellipse bottom

0,2Dt < ht = 0,25Dt

The thickness of lid and bottom column:

p: work pressure N/mm2

[σ]: allowable tensile stress of material

: the inner curvature radius at the top of the bottom (mm)

Similar to the body of column :

Check the work condition

Check the pressure condition

Satified the condition

2.8 Calculate the diameter of vapor pipe and liquid pipe

2.8.1. Diameter of inlet and outlet vapor pipe

Where

: average velocity (m/s) Pressure 0.5 at < P < 1 at  20 < < 40 m/s

(Table II.2 page 370 Sổ tay quá trình và thiết bị công nghệ hóa chất,1[9])

Choose the inlet and outlet velocity of vapor (m/s)

(Equation II.36 page 369 Sổ tay quá trình và thiết bị công nghệ hóa chất ,1[9])

: Diameter of inlet and outlet vapor pipe

Check the value

dk = 80 (mm)

Diameter of inlet vapor pipe = Diameter of outlet vapor pipe = 80 (mm)

Using flange connect the pipe (D > 10 mm)