Production of alchohol

What is alcohol ?

1. It's a colorless liquid.
2. It's something used as a fuel.
3. It's something used as an industrial solvent.
4. It can be poisonous.
5. It catches on fire easily.
6. Many people drink it.

Production -

Fermented beverages -

The production of  alcohol is caused by the chemical phenomena fermented beverages. The fermented beverages are produced through fermentation. Fermentation in the case of alcoholic beverages refers to a metabolic process by which yeast convert sugar to ethanol .yeast is a type of fungus used in the fermentation of alcohol . In order for fermentation to take place, you begin with some type of carbohydrate that is needed to feed the yeast . The type of  carbohydrate used determines what the final product will be .

Ex. -
Beer is produced by fermenting grain .
Wine or hard cider is produced by fermenting fruit .
Mead is produced by fermenting honey.
Milk and tree or plant sap can be used to produce fermented beverages.

Distilled beverages -
  
In order to produce beverages above the concentration of ethanol achieved through fermentation, a distillation process is used.
Distillation of alcoholic beverages is the process by which water is removed from the mixture of ethanol and water.
During distillation, the difference in the boiling points of water and alcohol is used to separate the two liquid.

Dynamic bed measurements of CO adsorption on microporous adsorbents at high pressures for hydrogen purification processes

Dynamic bed measurements of CO adsorption on microporous adsorbents at high pressures for hydrogen purification processes

                                                                                    Regarding the importance of adsorptive removal of carbon monoxide from hydrogen-rich mixtures for novel applications (e.g. fuel cells), this work provides a series of experimental data on adsorption isotherms and breakthrough curves of carbon monoxide. Three recently developed 5A zeolites and one commercial activated carbon were used as adsorbents. Isotherms were measured gravimetrically at temperatures of 278–313 K and pressures up to 0.85 MPa. Breakthrough curves of CO were obtained from dynamic column measurements at temperatures of 298–301 K, pressures ranging from 0.1 MPa to ca. 6 MPa and concentrations of CO in H₂/CO mixtures of 5–17.5 mol%. A simple mathematical model was developed to simulate breakthrough curves on adsorbent beds using measured and calculated data as inputs. The number of parameters and the use of correlations to evaluate them were restricted in order to focus the importance of measured values. For the given assumptions and simplifications, the results show that the model predictions agree satisfactorily with the experimental data at the different operating conditions applied.

In spite of not being a primary energy source hydrogen needs to be produced and consequently purified. The current main source of hydrogen is the processing of fossil derivates like methane, coal and heavy hydrocarbons. Other sources include electrolysis and biological processes [1], [2] and [3].

 

 

 

The most common and economical way to produce hydrogen is through steam reforming of natural gas combined with a water–gas shift reaction, from which a hydrogen-rich stream (70–80%) containing impurities, namely hydrogen sulfide (traces), water vapor (<1%), nitrogen (<1%), methane (3–6%), carbon monoxide (1–3%) and carbon dioxide (15–25%), is produced [4], [5] and [6]. In order to obtain hydrogen with the desired purity these contaminants must be removed. The removal process is industrially carried out by pressure swing adsorption (PSA), which is usually designed to obtain a hydrogen stream containing 98–99.999 mol% H₂[6] and [7].

In practice, PSA units for hydrogen purification use up to three different adsorbent layers. The first layer reached by the feed mixture, usually a guard bed, is composed of alumina or silica gel to essentially adsorb H₂O; the second is composed of activated carbon, which adsorbs CH₄, CO, CO₂ and traces of sulfur components; and as a third layer, zeolites are used for improved adsorption of CO, N₂ and other trace components[8] and [9]. Therefore, factors like the choice of material, the relative length (ratio) of the layers, composition of the feed gas and interactions gas–solid can significantly influence the yield and efficiency of the process [5], [8], [9] and [10].

Despite the remarkable growth in practical applications of adsorptive gas separation, the commercial design and optimization of these processes still largely remain an experimental effort. This is primarily due to the inherent complex nature of the practical adsorption systems [11].

The most important challenges in this area today are (i) a deeper understanding of the equilibrium, the dynamics and thermal effects involved in the separation of mixtures; and (ii) the development of less expensive and less time-consuming models to describe the influence of the equilibrium, kinetics and heat effects on such processes. Today's models frequently cannot predict data with the accuracy and reliability required by industry [11],[12] and [13]. A more detailed covering of the contemporary research needs with interesting examples of the current industrial design requirements can be found elsewhere [11].

To achieve the desired reliability of the model it is necessary to have a considerable amount of experimental data, including mainly adsorption isotherms and breakthrough curves, which can provide a direct and realistic interpretation of the adsorption process. By measuring breakthrough curves, one can evaluate the amount adsorbed, the influence of other species and the interval required by each step (adsorption–desorption).

Most of the available data on breakthrough curves of CH₄, CO, CO₂ and N₂ in hydrogen are results of simulations, mainly those at high pressures (above 2.0 MPa), providing few experimental data. The current literature lacks measured data at different pressure and temperature conditions, especially in newly developed materials [12] and [13].

Carbon monoxide was chosen as a component to be removed from H₂-rich mixtures for this study, since only few experimental data are available from the literature and the importance of its concentration on H₂ for fuel cells applications. CO tends to act as a severe poison towards the platinum catalyst in a PEM fuel cell and for this reason its concentration must be generally reduced to levels as low as 10 ppm [14].

The main goal of this study was to provide a series of experimental data for breakthrough curves and adsorption isotherms of CO on different materials, including an activated carbon and new commercial zeolites, with different feed compositions and pressures ranging from 0.1 to 6 MPa. Then, a simple model was applied using measured parameters (obtained from adsorption isotherms, bed geometry, etc.) and properties evaluated according to corresponding literature data, for instance heat capacity and conductivity, as input values. After that, this model was validated by comparing simulations with experiments.

With the modeling and experimental investigation, this study also aimed a deeper insight into the adsorptive separation of carbon monoxide from hydrogen on fixed beds, by analyzing the influence of the adsorption equilibrium and operational variables such as the feed flow rate, pressure and composition on the performance of a separation unit.

2. Model

In this section we provide a simple approach to the calculation of fixed bed adsorption. A comprehensive summary of models developed to analyze data and predict results for a variety of adsorption systems has been reported in the literature [15].

In order to describe the dynamic behavior of separation processes in fixed beds a general mathematical model was used, which consists of the coupled mass and energy balances with suitable boundary and initial conditions. The set of differential equations was solved by numerical integration using the Euler method, written in Borland Delphi 3.0. The model was designed based on the system schematically illustrated in Fig. 1 with assumptions commonly found in the literature [4], [16], [17], [18] and [19] and simplified for reasons to be discussed below.

 

2.1. Model assumptions

 

1.

Ideal gas behavior of the adsorptive throughout the column.

2.

No mass, heat or velocity gradients in the radial direction.

3.

Plug flow with axial mass dispersion.

4.

Negligible external mass transfer effect (i.e. film mass transfer and macropore diffusion).

5.

Mass transfer into the particle described according to the linear driving force (LDF) model [7], [16] and [19].

6.

No temperature gradient inside the particles and thermal equilibrium between the gas and the adsorbent.

7.

The system is assumed to operate adiabatically.

8.

Constant heat transfer coefficients.

9.

Constant and homogeneous bed porosity along the bed length.

10.

No pressure drop was considered.