ADRIAN ABED OLIVARES
DESIGNING A DESTILLATION TOWER Universidad Politécnica de Madrid, España Industrial & Engineering Chemistry 21/05/2018
Author's data:
[email protected] Subject: Numerical Calculations for Engineering Tutor: Ricardo Albarracín and Sandra Castaño
Index List of figures and tables ..............................................................................................................2 Symbology ....................................................................................................................................2 Abstract ........................................................................................................................................4 Annexes ......................................................................................................................................22
1.
State of art ...........................................................................................................................4 1.1.
Introduction to the distillation .....................................................................................5
1.2.
Identify the main problem ............................................................................................8
1.3.
Choose a method to solve the problem .......................................................................9
2.
Construction liquid-vapor equilibrium diagrams ..................................................................9
3.
Design of the distillation tower by McCabe Thiele .............................................................12 3.1.
Calculating number of plates ......................................................................................12
3.2.
Calculating electrice power of condenser and boiler .................................................14
3.3.
Temperature of each plate .........................................................................................16
3.4.
Distillation performance .............................................................................................18
3.5.
Heat exchanger ..........................................................................................................19
4.
Results ................................................................................................................................19
5.
Conclusions ........................................................................................................................20
6.
References..........................................................................................................................21
List of figures and tables Figure 1. Rectification tower Figure 2. Equilibrium liquid-vapor of acetonitrile and p-xylene at 720 mmHg Figure 3. McCabe Thiele Method for obtaining the number of plates Figure 4. McCabe Thiele Method for obtaining condenser and boiler power Figure 5. Plates temperature allocation on T-XA diagram
Table1. Units of all variables Table 2. Parameters of Antoine Table 3. Parameters of vaporization energy
Symbology Next, the symbology and the terms used are presented. [A] = higher volatile component Acetonitrile. [B] = lower volatility component P-Xylene. [Cp]= heat capacity or thermal capacity is the necessary energy that must be supplied to a mole of substance to raise its temperature one degree. [Cp_mixture]= heat capacity of the dissolution of our two components. [D]= molar flow of column head of acetonitrile. [Enthalpy_sensible]= it is the energy that must be supplied to vary a temperature range for a mole of substance in liquid phase. [Enthalpy_vaporization]= it is the energy that must be supplied to evaporate a mole of substance in liquid phase. [F]= it is the molar fraction of A component in liquid phase, that is, it is the percentage in moles that there is of a substance feeding the distillation Colum. [F`]= molar flow of feeding.
2
[Omin]= geometric place where they cut all the straights of the plates of a tower rectification that represents the total enthalpy of the system. [Pressure]= continuous physical force exerted on or against an object by something in contact with it. In our case, the pressure refers to the atmospheric in Madrid. [Pv]= vapor pressure or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phase (liquid) at a given temperature in a closed system. We have one vapor pressure per component. [W] = molar flow of acetonitrile in the tail of the column. [T_boiling]= the boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. We have one temperature of boiling per substance and it deepens of the pressure, because of this there is one per vapor pressure. [Tdestillation]= is the set of boiling temperatures at different vapor pressures. [x, y] = it is the set of boiling temperatures at different vapor pressures. [X]= the molar fraction of each component in liquid phase, that is, it is the percentage in moles that there is of a substance in liquid phase. [Y]= is the molar fraction of each component in vapor phase, that is, it is the percentage in moles that there is of a substance in vapor phase.
Table1. Units of all variables
Magnitude
Units Main
Secondary
Atm
mmHg
Cp (heat capacity) Cp_mixture Enthalpy_sensible Enthalpy_vaporization Pressure
3
Pv (vapor pressure)
Atm
mmHg
T_boiling (boiling temperature)
°C
°K
Tdestillation
°C
°K
X (molar fraction liquid) Y(molar fraction vapor) -
Abstract The main of this project consists on designing a rectification tower. The parts of this tower are boiler, condenser, heat changer and column, which has got plates. The number of plates inside of the column has been calculated, the minimum electric power required for boiler, condenser and heat changer, the solution`s temperature of entrance to the column, the temperature of each plate and the performance of column. All for maximum recirculation. The design is carried out using the McCabe Thiele process through the construction of equilibrium vapor diagrams of acetonitrile and p-xylene.
1. State of art The document is organized as follows: first, there is an introduction about the more common process in chemical engineering explaining the importance they have in the industry. We are going to focus on the distillation based on one example and the main problem that we are going to attend. Then, we will decide which the best way to solve the problem is and which the faster, easier and cheapest method is. Ultimately, we are going to get results using the choosing method and we will reach some conclusions about the build of rectification column.
4
1.1. Introduction to the distillation All the plants of industrial chemical processes contain in their process equips. Normally, chemist manufactures are working with fluids like vapour, solvents, dissolutions, chemical components… The fluids used are continuously reused. Because of this, after used it we have purified. The purification processes are secondary to the main process and these are evaporation, crystallization, distillation, extraction or lixiviation. The main units of this purification processes usually are columns of plates and secondary’s units are heat changers, drums, boiler… in other words, equips that prepare the substance to go inside the main unit. For this reason, is so important to size all units at the same time. One Example of this equips are in the polymer manufacturing industry, the use of several solvents is very common. The manufacture of Nylon is a process of numerous stages where acetonitrile and p-xylene are used to make the process more efficient. These solvents are mixed with each other from stage to stage, favouring the reaction. After the nylon production is finished, the solvents are separated from the polymer with a filter press. Then the acetonitrile and p-xylene used are led to another filter to remove solid impurities. Finally, these two components must be separated so that they can be reused with high purity. This separation is made by rectification. In this project, we will proceed to the study the rectification process. Distillation and rectification are the process of separation the species that make up a liquid mixture through vaporization and selective condensation. Said substances, liquids components that can be, solids dissolved in liquids or liquefied gases, are separated taking advantage of the different boiling points of each nail of them, since the boiling point is an intensive property of each substance, that is, without it varies depending on the mass of the volume, although it depends on the pressure. The miscible dissolution goes inside to the column and it heats progressively. The more volatile component change to vapour phase and it goes up to the head column. The least volatile component goes down to the tail column in liquid phase. Therefore, we can collect one component (B) at bottom of the column and other component (A) on top of the column. The top of the column need a condenser to transform the vapour to liquid phase. The bottom columns need a boiler to reboil the liquid component (B) for improve the performance of the column.
What is the difference between distillation and rectification? In the rectification, part of the product obtained in the head of the column is returned to the interior of the column in liquid phase, as the boiler returned to the column 5
vapour of component B. This product that is greater purity in more volatile component passes through all the plates from the head to the tail of the column. This fact favours the liquid vapour equilibrium in each plate and thus greater performance. For this reason, in the rectification the number of the dishes in the column decreases. In the distillation, there is no volatile component recirculation and more plates are needed. The distillation is not usually used for this kind of separations, but there is another type of separation where if it is used called flash distillation. Why is it so important part of the process? On the one hand, the economic point of view is very important, since you cannot buy solvents every time you want to start the manufacture. The cost would be very high. Therefore, the solvents are purchased once and are separated by distillation repeatedly. On the other hand, the environmental point of view is of great importance since the solvents are highly toxic and polluting. Therefore, the purification, correct storage and disintegration of these solvents is mandatory under environmental law. There are many types of distillation, but they are based on two main: - Simple scaling: in simple distillation, the steam is immediately channelled into a condenser. Consequently, the distillate is not pure but its composition is identical to the composition of the vapours at the given temperature and pressure. That concentration follows Raoult's law. As a result, simple distillation is effective only when the boiling points of the liquid differ greatly (the general rule is 25 ° C) or when liquids are separated from solids or non-volatile oils. For these cases, the vapour pressures of the components are usually different enough so that the distillate can be pure enough for its intended purpose. - Fractional distillation: in many cases, the boiling points of the components in the mixture will be close enough to take into account Raoult's law. Therefore, fractional distillation should be used to separate the components by repeated cycles of vaporization-condensation within a packed fractionation column. This separation, by successive distillations, is also known as rectification. As the solution to be purified is heated, its vapours are raised to the fractionating column. As it rises, it cools, condensing on the walls of the condenser and the surfaces of the packaging material. Here, the condensate continues to be heated by the increase of hot vapours. It vaporizes once more. However, the composition of fresh vapours is determined once again by Raoult's law. Each vaporization-condensation cycle (called the theoretical plate) will produce a purer solution of the more volatile component. In reality, each cycle at a given temperature does not occur exactly in the 6
same position in the fractionation column. The theoretical plate is, therefore, a concept rather than a precise description. More theoretical plates lead to better separations. A rotating band distillation system uses a rotating Teflon or metal band to force rising vapours into close contact with the descending condensate, increasing the number of theoretical plates. The distillation column has the following parts:
Figure1. Rectification tower [“Chang Chemist”]
7
All variables are defined in the abstract. Liquid-vapour equilibrium describes the distribution of a chemical species between the vapour phase and a liquid phase, that is to say how much vapour and how much liquid of the different components of dissolution there are condensing and boiling at time at same pressure. Inside of the column, the base of the distillation is the equilibrium between liquid (L) and vapour (V), because of this we must build the diagrams of this equilibrium from tabulate dates for dimensioned the equip. Applying this equipment to our particular case, the feed will be 40% of molar fraction of acetonitrile. The liquid reflux will be assumed maximum to give the minimum number of theoretical plates possible. However, for an implementation of this project for a different liquid flux, the same calculation method must be applied, changing only the variables. In addition, a total condenser and reboiler will be assumed, that is, the condenser condenses all the vapour in liquid and the reboiler will boil all the vapour to liquid.
1.2. Identify the main problem To maintain environmental and economic sustainability, the substances used in the polymerization of plastic materials have been reused as much as possible. In the case of chemical engineering, the reuse of solvents is very common. These solvents need to be of a high purity, of less than 95%, in order to be used in a chemical process. Because of this, a big part of the production plant is saved for the secondary processes. Therefore, this project develops the first pre-design steps of a recirculation distillation column for the acetonitrile and p-xylene compounds. Objective The main idea of this project is to design a distillation tower from the liquid-vapour equilibrium diagrams of two substances. These diagrams have made in Matlab from theory values.
8
1.3. Choose a method to solve the problem The calculation for rectification towers is a very common in chemical engineering. There are many programs of design but they are very expensive. One of the oldest and most effective methods is the McCabe-Thiele Method. It is characterized by its simplicity when it comes to obtaining results, as it is a graphic method. This method is based on the liquid-vapour equilibrium and using diagrams, we can obtain results. The disadvantages of this method are the advanced knowledge of chemistry and physics for the construction of the diagrams and the analysis of the results obtained. As we do not have the luxurious and expensive design programs, it will be realized by this McCabe-Thiele method.
2. Construction liquid-vapor equilibrium diagrams The calculation is based on a binary mixture of Acetonitrile and p-Xylene, being respectively A and B with different molecular weights and miscible to each other. Three diagrams will be represented: • Boiling points versus composition of A (T-XA) • Liquid-vapour equilibrium (YA-XA) • Enthalpy versus composition (E-XA) Compound A is more volatile than B, thus having different boiling points, which depend on the external pressure. This example of calculation is based on pressure in Madrid. It is 720 mmHg.
1º The calculation of the boiling temperatures of both compounds at a pressure of 720 mm Hg is made through the education of Antoine and the respective parameters A, B and C.
9
For compound A:
Clearing T_boliling_A = 79.40 ℃of the volatile compound and T_boling_B = 136.34 ℃ of non-volatile. Thus the temperatures at the extremes are determined and the temperature difference is divided by twenty to take temperature values at different compositions.
2º The vapour pressure at the corresponding temperatures is calculated with the Antoine equation:
For 133.49 ℃, your vapour pressure for each compound will be
3º The law of Raoult is applied to calculate the composition of the mixture at different temperatures previously calculated
For the most volatile component:
10
4º For the composition of the vapour phase, we are going to use Dalton equation:
To calculate YB can be done by subtraction:
5 º Calculation of the Cp of the volatile and non-volatile compound with respect to data tabulated in tables:
For each component there is a Cp that depends only on the temperatures, that the values A, B, C and D are tabulated. Calculated for a temperature equal to 133.49 ℃: Table 2. Parameters of Antoine
A Acetonitrilo p-Xileno
B 4,8920 -5,9930
C 2,857E-02 1,443E-01
D -1,073E-05 -8,058E-05
7,650E-10 1,629E-08
=14,787 (Kcal/Kmol) = 40,456 (Kcal/Kmol)
6º The enthalpies of vaporization of both compounds tabulated in tables:
Table 3. Parameters of vaporization energy
Acetonitrilo p-Xileno
AHVap (cal/g) 173,68 95,4
AHVap (kcal/kmol) 7120,88 10112,4
11
7º Calculation of enthalpy of liquid for a temperature of 133.49 ℃:
El
= T-T` (Volatile component)
Kcal/Kmol
8º Calculation of the enthalpy of the vapor phase:
=11987,10 Kcal/Kmol
This process is repeated for each temperature located at the extremes of the boiling temperatures of each compound, each parameter calculated and finally represented graphically.
3. Design of the distillation tower by McCabe Thiele This graphic method is based on liquid-vapour equilibrium. We are going to calculated; the number of plates of the column, the electric power of the condenser and the reboiler (secondary equip), the temperature of each plate, the entrance temperature of the solution in the column, the plate by which you have to feed the solution and the performance of the column. These parameters design the rectification tower.
3.1. Calculating number of plates We are going to fix the values of the concentration of the compound A. It has to be high purities, because of this we will choose an XD of 98% with 2% of the component B that cannot be separated. Therefore, the bottom of the column will leave the 0.2% XW as a residue with 0.98% of the component B. This is going to be represented in diagram L-V at first. In this diagram is represented Y (percentage molar of A vapour) vs. X (percentage molar of A liquid). 12
Figure 2. Equilibrium liquid-vapor of acetonitrile and p-xylene at 720 mmHg
The theoretical number of plates will be calculated graphically for an almost complete reflux. Then, from these calculations, it can be implemented for any type of reflux chosen depending on the flow of acetonitrile we want. If we increase the reflux, we will need less plates and vice versa. We will suppose the feed (F) has a value of 40% in molar fraction. That means, 40% is acetonitrile and 60% is p-xylene. There are values very close to those obtained in the nylon polymerization. Even so, this project could be interpolated to any other value of feed obtained or desired. A number represents each plate.
13
Figure 3. McCabe Thiele Method for obtaining the number of plates
In this process, there are two results: 1. The number of plates of the column = 4.3 = 5 (complete plates) 2. The plate where it should be allocated the feed = 3rd
3.2. Calculating electric power of condenser and boiler Now, we are going to calculate the power needed for the complete rectification in the boiler and in the condenser, assuming that these are both total. For this, we are going to use the same method of graphic calculation but this time in the diagram EnthalpyComposition (H-X). In this diagram we represent liquid`s enthalpy ( versus liquid`s composition XA and vapour`s enthalpy (
) (blue line)
) (red line) versus
vapour`s composition YA. We are going to transfer the data from the X-Y diagram to the H-X diagram graphically.
14
At first, we are going to situate feed`s composition in H-X diagram and XD and XW. Then, we will calculate the minimum power needed for our condenser and reboiler. The Omin situated on the diagram represent the minimum power and
for condenser
for reboiler.
Figure 4. McCabe Thiele Method for obtaining condenser and boiler power
15
In this process, there are two results:
Boiler power = 5500
Condenser power= 10000
Assuming a feed flow (F) of 1
Boiler power = 5,5
Condenser power= 10
, the power of these equips is: = 22,88 kW = 41,60 kW
3.3. Temperature of each plate There are many types of plates that can be chosen in order to design a distillation column. Thus, it is very important to know the temperature of each plate to select the appropriate kind of plate. In order to accomplish this matter, we need TemperatureComposition (A) diagram (T-XA). It is also essential to determine at what temperature the column has to be fed. If it were fed at an inadequate one the performance would decrease.
16
Figure 5. Plates temperature allocation on T-XA diagram
17
In this process, two results are obtained: Temperature of 1º plate: 84 °C Temperature of 2º plate: 97 °C Temperature of 3º plate: 120 °C Temperature of 4º plate: 131 °C Temperature of 5º plate: is the maximum temperature on the column 136 °C Feeding temperature: 120°C because we feed from 3º plate.
3.4. Distillation performance It is going to be calculated by the use of the next formula, which represents the relation between the distilled mole flux and the fed one.
η= To calculate the fluxes of D and F` we are going to make a mass balance
So:
D=0, 396 W= 0,604
η=
%
18
3.5. Heat exchanger After the process of polymerization, the mixture of solvents is at ambient temperature, 25°C. We have to increase the temperature to 120 °C for feed the column, as we have calculated before. For this, we use a heat exchanger allocate before the column. The electric power of this heat exchanger is:
°C
°C
4. Results For our design of the rectification equipment, the following parameters have been obtained: We have obtained a theoretical 5-dish tower feeding on dish number 3 at a temperature of 120 °C. A total boiler in the bottom of the column of 41, 60 kW and a total condenser of 22, 88 kW. Each plate must maintain its respective temperature of: 1º plate: 84 °C 2º plate: 97 °C 3º plate: 120°C 4º plate: 131 °C 5º plate: 136 °C The performance of the process of separation= 97 % Power heat exchanger= 5,4 kW 19
Fluxes D =0, 396
W = 0,604
;F=1
5. Conclusions Based on the results obtained, the company to make our rectification column would need the results. We would order three plates inside the column and not five. It is because the condenser and the boiler are total and these can be considered as a plate of the column because in its interior there is a liquid equilibrium vapour of the dissolution. In the case that they were not total, five plates would be considered. The company, that we select, would choose the diameter and the height of the column as a function of the feed flow and D, in this case 1
and 0, 396
.
Also, the electric power of the condenser and the boiler should be 1.5 times more than the one obtained in our results, that is, 62,4 kW and 34,32 kW. This is done in order to change the reflux of the operation. Normally reflux is increased up to 1.5 times more than the minimum. Therefore, a margin is taken for the condenser and the boiler. The feed of the column has to enter at 120°C. Therefore, it will be necessary to incorporate a heat exchanger at the input of a power equal or greater than 5,7 kW. Once you reach this point, we will see the space that we use for all equips. If it is a very small space, we should analyze the type of plates used in the column. That is, we can choose fill plates and thus increase the height of the distiller, reducing it in diameter. This topic is for another project based on the process and product engineering to calculate the optimal point of size and price. The code and process to build the diagrams can be applied to two other components as long as they are miscible with each other with different boiling points. The only condition is that you have to change the experimental values of the compounds used such as heat capacities, Antoine values, enthalpy’s vaporization ... If easily known compounds will come tabulated in the Perry or Chang (described in the references). If they are complicated compounds, they should be studied in the laboratory for the deduction of the diagrams equilibrium liquid vapor.
20
This project cannot be used on the separation of multi- components. At the time of the separation of several compounds at the same time, the design is different and complicated. This project can be extended to electronic disciplines. Nowadays, these columns are automated with electro valves and electronic elements. In the continuation of the design of the distillation tower, the design of automation of valves and electrical circuit is essential.
6. References “Chang, Raymond (2000): Chang Chemist, 7º edition, MCGRAW-HILL, Spain” “L.McCabe, Warren (2001): Unit Operations of Chemical Engineering, 4º edition, pages 445521 and 550-618, MCGRAW-HILL, Spain” “E.Treybal, Robert (2000): Mass Transfer, 2º edition, pages 378-510, MCGRAW-HILL, Spain”. YEAR “H.Perry, Robert (2004): Perry's Chemical Engineers' Handbook, 8º Edition, tome 1, chapter of capacity heat, solubility, vaporization heat, MCGRAW-HILL, Spain” YEAR.
Instituto Nacional de Seguridad e Higiene en el Trabajo (INSHT) www.insht.es. Estudio de seguridad y planes de actuación. (Visited on 13/4/2018) Universidad Politécnica de Madrid (UPM) www.upm.es. Prevención riesgos laborales. Estudio de seguridad y planes de actuación. (Visited on 13/4/2018)
21
Annexes The code made in Matlab to make the diagrams of liquid-vapor equilibrium: This Matlab code is used to build the diagrams of acetonitrile and p-xylene equilibrium liquid-vapour at 720 mmHg. This pressure can be changed to any other different pressure.
%%”pressures.m” % This part of the code is used to calculate the temperature interval and the vapour pressures for each temperature using Antoine’s law Pressure_mmHg= 720 %pressure on mmHg that you are going to make the boiling (for example 720 on Embajadores in our university Pressure_atm= Pressure_mmHg./760 %pressure on atm T_boiling_B=136.33787683 % Theoretical temperature of boiling of P-xylene (B) T_boiling_A=79.40181886 %% Theoretical temperature of boiling of acetonitrile (A) Tdestillation=(T_boiling_B:-2.8468:T_boiling_A) %Range of temperatures Pv_B=exp(16.0963-(3346.65./ (Tdestillation+273.15-57.84))) %vapor pressure of substance B on mmHg with values of P-Xylene of Antoine Pv_A=exp(16.2874-(2945.47./ (Tdestillation+273.15-49.15))) %vapor pressure of substance A on mmHg with values of acetonitrile of Antoine Pv_B_atm=Pv_B./760 %vapor pressure of substance p-xylene on atm Pv_A_atm=Pv_A./760 %vapor pressure of substance acetonitrile on atm
%%”composition.m” % This part of the code is used to calculate the composition for each temperature of phase liquid and vapour using Rault`s law.
XA= (Pressure_atm-Pv_B_atm)./(Pv_A_atm-Pv_B_atm) XB= (Pressure_atm-Pv_A_atm)./(Pv_B_atm-Pv_A_atm) %molar composition of LIQUID of A and B at diferentes vapor pressures that it depends on temperatures. %The composition of A stars on minimun value XA = 0 becouse at this tmperature (136.34) all of it is vapor becouse his temperature of ebullition is 79.40 %However, when the temperature is 136.34 all of the liquid is B. 22
YA= (Pv_A_atm ./ Pressure_atm).*XA YB= (Pv_B_atm ./ Pressure_atm).*XB %molar composition of VAPOR of A and B pressures that it depends on temperatures.
at
diferentes
vapor
%%”cp.m” % This part of the code is used to calculate the specific heat for each substance and the dissolution between both.
Cp_A=4.8920+(0.02857.*(Tdestillation+273.15))+((-1.073.*10.^5).*((Tdestillation+273.15).^2))+((7.650.*10.^10).*((Tdestillation+273.15).^3)) Cp_B=-5.9930+(0.1443.*(Tdestillation+273.15))+((-8.058.*10.^5).*((Tdestillation+273.15).^2))+((1.629.*10.^8).*((Tdestillation+273.15).^3)) % Both of them Cp (Kcal/Kmol·K) depens of the temperature, so we calculate cp(Tdestillation). Cp_mixture=(Cp_A.*XA)+(Cp_B.*XB) %This Cp_mixture when bot of substances are on disolution
%%”Enthalpys.m” % This part of the code is used to calculate the enthalpies of liquid and vapour phase per temperature. Enthalpy_sensible=Cp_mixture.*(Tdestillation-T_boiling_A) %This entalpy is the energy (Kcal/Kmol A+B) that need to heat the disolution from miimun temperature to our tmperature of destillation %It is the enthalpy of the liquid. Enthalpy_vaporizatio_A=7120.88 Enthalpy_vaporizatio_B=10112.4 %Enthalpy of vaporization is the energy that we need per mol of subtance for transfor the liquid in gas fase. These are theoretical value Enthalpy_total=(Enthalpy_sensible)+ (Enthalpy_vaporizatio_A.*YA)+(Enthalpy_vaporizatio_B.*YB) %The Ethalpy_total (Kcal/Kmol) is the energy need to traformate el liquid to gas at this temperature an this pressure. %It is the enthalpy of the liquid and the gas 23
%% “Graph.m” % Representing diagrams y=[0 1]; %reference line x=[0 1]; %Figure. Temperature composition figure(); hold on plot(XA,Tdestillation,'b') plot(YA,Tdestillation,'r') title('Temperature-Composition') xlabel('XA') ylabel('T (°C)') legend('liquid phase','vapor phase') grid %Figure. Equilibrium liquid-vapor figure(); hold on plot(XA,YA,'b') plot(x,y,'k') plot(x,y) title('Equilibrium liquid-vapor') xlabel('XA') ylabel('YA') legend('Equilibrium line','reference') grid %Figure 3. ENTHALPY-COMPOSITION figure(); hold on plot(XA,Enthalpy_sensible,'b') plot(YA,Enthalpy_total,'r') axis([0 1 -14000 20000]) title('Enthalpy-Composition') ylabel('Enthalpys') xlabel('XA,YA') legend('Enthalpy liquid','Enthalpy vapor') grid
24
