Linas Technology - Distillation of 21 century

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Introduction in Linas distillation technology

For understanding of the Linas distillation technology we have to make the analysis of modern industrial distillation.
It will allow to reveal the basic falls and contradictions of existing industrial distillation and to show solutions of these problems in Linas technology.

1. Importance of distillation

Distillation consumes huge amounts of energy and it can generate more than 50% of plant operating cost.
Modern industrial rectification was established some 50 to 60 years ago. Significant efforts by thousands of researchers and developers around the world during the second half of the twentieth century did not bring a sufficient improvement in industrial rectification. Main efforts were concentrated on local improvements and the main principles of the modern distillation were not changed at all.
In general rectification is a very conservative process. Huge rectification towers of refinery, chemical and petrochemical plants are a symbol of modern industry. Very often height of rectification towers exceeds 50 meters. Costs of design, manufacturing, transport, operation and repairs become enormous. Rectification towers looks like dinosaurs and clash with the technological image of the 21st century.

2. Core fundamental problems of modern distillation

For more than 50 years of an existence of modern distillation the opinion was gradually created, that significant improvement of industrial distillation is impossible. However the careful and detailed analysis of principles and applications of modern industrial distillation shows several fundamental contradictions and disadvantages. These contradictions are concentrated in an arrangement of heat and mass exchange processes and reflux.

2.1. Arrangement of the heat and mass exchange processes in conventional distillation

Indeed the distillation is based on heat and mass exchange processes between two or more compounds.
In the modern industrial distillation the basic and actually the main attention is given to the mass exchange process. All efforts of technologists and engineers are directed on improvements of mass exchange processes between substances. Complex and expensive packing and trays of the most complex forms are created to improve the mass exchange processes. Thus to the heat exchange processes between substances it is not given due attention.

From our point of view the basic problem of modern distillation consists in absence of the control over the heat exchange processes and a particular to the energy of condensation of substances. Moreover, the control over the energy of evaporation and condensation is the primary process, and it can operate and rule the mass exchange process.

Let's consider the elementary case of water and alcohol distillation (Fig.1). After evaporation of both substances, there is their condensation on surface of packing or trays. Thus it generates the large amount of the heat of the condensation.

Fig.1.
Scheme of elementary step of a water-alcohol distillation

Modern distillation practically does not pay an attention to the heat of condensation and does not operate with him. It results to that a part of the condensed water can again evaporate and to rise above on a column. In an ideal step after the first act of the evaporation and condensation all amount of water should be removed at a bottom of the column (See the figure 1), and all amount of alcohol should be evaporated again and to be removed at the top of the column. It means, that the energy of the water condensation is necessary to remove from a distillation space or to make a heat transfer to a process of alcohol evaporation. However in modern columns there are no devices or technology which would supervise this process.

Thus, the energy of a condensation is not supervised and it results in an efficiency reduction of a separation, increase in height of columns and expenses of energy.
It is necessary to organize a certain device or technology which would supervise the energy of condensation of separated substances. Introduction of such mechanism would lead to sharp decrease in a height of a column and an efficiency of distillation. The modern conventional distillation is based on tray and packing rectification columns. From our point of view it is nearly impossible to introduce any energy operation device inside of modern column to control and supervise distribution of energy inside of distillation space above mentioned columns.

2.2. Arrangement of reflux

The second weak point of the modern industrial distillation is the arrangement of reflux and its distribution along a height of rectification towers.
As the reflux a pure distillate is usually used. The reflux is entered through a special device at a top of the column (Fig.2).
Simple analysis of the mass exchange processes in a conventional column shows, that a huge surplus of pure distillate on top of a column is not required. Moreover, the reflux at the top of a column is absolutely not necessary. The amount and structure of a reflux should be various along the height of the column. The bottom part of the column needs a plenty of reflux with a large amount of the higher boiling component. With increase in the height of the column a content of the higher boiling component in reflux should decrease and an amount of the reflux should decrease too (Fig.2. Desirable distribution of the reflux). This arrangement of the reflux reduces a total amount of the reflux and makes the reflux more effective.

Fig.2.
Scheme of reflux distributions for a conventional and Linas distillations (V is vapor).

Modern industrial distillation uses a different arrangement of reflux. There is no the arrangement of the reflux composition and an amount of the reflux along the height of a column. It results in a sharp increase in expenses of energy and increase in height of columns.

Thus, from our point of view the basic lacks of modern industrial rectification are the following:

1. Modern design of rectification towers does not pay attention to real microbalance of heat and mass exchange processes.
2. Mass and heat exchange processes in every point of conventional columns are not correlated to each others.
3. Modern arrangement of a composition and an amount of reflux does not correlated to real distribution of low and high boiling compounds along rectification towers.

This results in columns being very tall and requires more energy for the distillation process. Finally this results in a high cost of an operation.

2.3. Linas distillation technology

A small group of enthusiastic and highly professional researchers and engineers made an attempt to develop a new breakthrough distillation technology. This attempt was successful. They have developed a totally new solution for industrial distillation and have developed the new industrial distillation technology called Linas technology.

Linas technology is based on the modified very much film distillation.
Indeed, the conventional film distillation has several attractive advantages such as simple construction, the very low flow resistance and good separation ability. The film distillation has the lowest height of the theoretical tray (equal 5 mm) among all distillation technologies, but only if vapor velocity is around 1 cm/s. Therefore applications of the film distillation are very limited and not really applicable in a large scale industrial distillation. At high velocity of vapor along vertical surfaces a film ceases to be uniform and heat and mass exchange processes become unstable and all advantages of film rectification are not realized.

This main problem of the conventional film distillation was solved by Linas technology.

Linas technology is based on vertical tubes with a length from 0.5 m till 3 m and a diameter 6-25 mm.

Linas technology concentrates the main attention on the energy of a condensation of separated compounds.

Temperature of Linas tube's wall (Fig.3, temperature T_W) is fixed on certain level along a height of tube between T_A and T_B. Under distillation conditions the compound B with higher boiling point (T_B) condenses always on the walls of tubes and removed down in a liquid film form. The compound A with lower boiling point (T_A) is evaporated always from a surface of the film and leave tube's space as the final distillate. Indeed the energy and the energy barrier are the moving force of Linas technology. Special device outside of Linas tubes is responsible on the arrangement of the temperature T_W on the certain level. In many cases T_W is varied along the height of the tubes from the temperature close to T_A to the temperature close to T_B. Access of energy of the B component's condensation is removed outside of the rectification space by the additional condenser (Fig.5).

Fig.3.
Moving force of Linas technology (T_A and T_B are boiling temperatures of compounds A and B).

Linas technology is based on so called internal reflux. The temperature different of T_W along the height of the tubes manages the reflux. Indeed the A and B from moving up vapor phase are condensed on the moving down film. This condensed mixture of A and B is the Linas reflux. The composition of the reflux is very much different. At low level of the tubes the composition of the reflux is close to evaporated mixture of A and B and with large concentration of B. Amount of the reflux is relative large. At high level of the tubes the composition of the reflux contains mainly the component A. The amount of the reflux becomes small (Fig. 4). Principles of Linas reflux arrangement is presented on Figure 4.

Industrial applications of Linas technology give:

1. Stable distillation film under a velocity of a vapor stream inside of Linas's column up to 1.5-2.0 m/s.
2. Adaptation of a heat and mass exchange processes inside the Linas column to the physical properties of separated compounds.
3. New arrangement of the reflux process. All evaporated distillate is a final product according to the scheme below. Linas reflux process takes place inside the Linas distillation towers.
4. Three to ten fold reduction of the height of rectification towers and 50 to 100 time reduction in the amount of separated compounds inside the Linas column compared with conventional rectification towers.

Fig.4.
Relative distribution of an amount of the reflux and ratio of components A and B in the reflux. (The total amount of reflux is presented as the square inside of red line)

Technologic scheme of Linas rectification tower is little bit different from the conventional one (Fig.5). There is no a reflux line back to the tower from the distillate drum. The Linas tower contains an additional device (the condenser) compare to the conventional tower. The condenser does not connected directly to internal compounds. From technical point of view the external different between technologic scheme of Linas rectification tower and the conventional tower is relative small.

Fig.5.
Technologic scheme of Linas and conventional rectification towers.

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