Distillation Trays + Structured Packing Enable to Partition Bubbling Layer on Height and Increase Efficiency

Tray column and  packed column widespread use in chemical, petrochemical and other industries to separate liquid mixtures. Today, high efficiency of mass transfer is one of key factors influencing the choice of column type. Our company proposes additional increasing mass transfer efficiency by placement structured packing between distillation trays.

Most efficient using of the structured packing is achieved in a flooded her condition, in the mode of emulsification. In this case, increases the mass transfer area and the volumetric mass transfer coefficient is 2-3 times. Cyclic distillation technology is able to raise efficiency of mass transfer due to the location structured packing between the Maleta trays. For cyclic distillation there is no fluid motion at the tray, as result we have effect of partitioning the bubble layer by height.

Technological advantages: 

·        Possibility to set structured packing between the trays (including a fluidized  layer);

·        The increase in the volume mass transfer coefficient is 2-3 times;

·        Partition bubbling layer on height. 

Cyclic distillation technology gives opportunities to combine all the advantages of tray and  packed column.

Tray Divided Wall Distillation Column Your Effective Solution

Nowadays distillation process despite its high energy consumption is the main separation technique in ethanol, pharmaceutical, petrochemical and chemical factory. The divided wall distillation column (DWC) and is considered a very attractive solution for reduction of energy and investment in separation distillation.

Maleta cyclic distillation LLC in 2014 year build first tray divided wall distillation column DN 1500/1700 mm that operation in cyclic mode. The cyclic distillation technology has opportunity to combine the required number of columns for the separation of multicomponent mixtures in a one column and have advantages over usual parked DWC-columns:

• price of tray dividing-wall columns is much lower than common DWC-column;
• better process control
• simpler column design;
• the uniform arrangement of liquid on the tray;
• faster and more precise installation;
• mass transfer efficiency of cyclic distillation;
• faster and simpler revamping of existing column.

We propose next configurations of the tray dividing-wall columns: azeotropic dividing-wall columns; reactive dividing-wall columns; extractive dividing-wall columns; dividing-wall columns for four-component mixtures.

Our company supplies full engineering service for DWC technology - simulation, design, manufacturing, additional project equipment, chef installation, guaranty and post-guaranty service.

Demethanl column in production ethanol food grade

At the ethanol plant that production ethanol food grade, with capacity 30 000 liters per day was problem with methanol content in final product (high methanol levels). Maleta cyclic distillation LLC proposes to install addition high efficiency column in cyclic mode for concentration methanol less than 5 ppm in the final product. 

Column feed is unpasteurized ethanol from rectification column (ethanol distillation column) in the amount 7…10 % of plant capacity. Steam consumption of cyclic methanol column is about 0.5 kg / L of input ethanol. The bottom liquid from methanol distillation column goes as additional feed to rectification column (ethanol distillation column), and the concentrate in the amount of 0.2…0.3 % remove like waste.

The additional cyclic methanol column has next characteristic: column diameter 400mm, number of Maleta distillation trays 15psc. The stripping section of distillation column consists of 9 distillation trays - the concentration section of 6 distillation trays.

The final results of reconstruction are: the concentration methanol is less than 5 ppm in the final product; reduces of content of aldehydes in ethanol food grade; increases the oxidation of ethanol food grade; improves the organoleptic characteristics of ethanol food grade.

Catalytic Cyclic Distillation Column for production Isopropyl Alcohol (IPA) from Propylene

Catalytic Distillation Column

The conventional technology of production Isopropyl Alcohol (IPA) from Propylene is direct hydration and indirect hydration of propylene. Separation of IPA from the azeotropic mixture need list of distillation columns and high steam consumptions. In recent years, much research has been paid to by innovation, effective and simple method for production Isopropyl Alcohol (IPA) from Propylene – catalytic (reactive) distillation. The catalytic distillation column comprises the processes of heterogeneous catalytic reaction and multistage distillation is carried out simultaneously in one unit. In this case, we have reduced of capital and operation cost, because the number of process equipment is considerably reducing.

The key benefits of cyclic distillation in comparison with the stationary process is control of the reaction time, and increase in performance of the distillation column by minimizing the flow resistance in the cross-flow of liquid from the tray on a tray (single-phase fluid flow). The catalyst can be placed between the trays in a boiling layer.

Maleta cyclic distillation LLC propose pilot plant and industry solution for getting high purity IPA (99.9 % vol.) as final product. Our solution is basis at innovation technology cyclic catalytic (reactive) distillation column. As result you will get a completely new, highly effective technology and your company can take a leading position in the IPA market. Our service included pilot plant testing, design, equipment, installation, construction service, start-up, post-guaranty service.

ANALYSIS AND DESIGN OF DISTILLATION TRAYS FOR CYCLIC MASS TRANSFER

DISTILLATION TRAYS

Conditions of realization cyclic mass transfer expressed two postulates: lack of outflow of liquids to the trays vapor admission; lack of mixing of liquids in adjacent trays upon outflow of liquid. This method of interaction phases increase in efficiency mass transfer as compared to the standard process.

The method interaction phases in the distillation column can be as follows: discrete feed of liquid and vapor; continuous supply of liquid and discrete steam; constant supply of fluid and continuous steam. These conditions can be achieved at both the distillation column and the level distillation trays.

First stage of development of column internals for cyclic mass transfer was by external mechanical drives that are associated with elements of thrust trays. Pilot scale development and research of this solution has led to the establishment of individual actuators on each tray. In this case we have alternately devastation (overflow) distillation trays from bottom to top of distillation column, by changing the free sectional trays. Unfortunately, this method has not received industrial implementation.

In the second stage of development for liquid overflow on the distillation tray began to use the kinetic energy of motion of vapor in the distillation column.

In case of cyclic steam flow, the steam flow acts as a control of liquid flows in the distillation column. The main element of such distillation trays are sluice chambers and valves. In this case, the liquid flow (feed, reflux, distillate and bottom product) moves in a continuous mode. Cyclic mass transfer operation consisting of two key parts: vapor flows goes through the distillation column and the stationary liquid stays on the trays, and this is called the vapor flow period, while the liquid flow period arises when vapor flow is stopped and the liquid holdup in sluice chambers, the vapor flow period starts and liquid from sluice chambers falls into the tray below. The design of Maleta distillation trays and two key parts of interactions you can see at the picture. Today, Maleta distillation trays works in stripping column, rectification column and tray dividing wall columns with a diameter ranging from 400 to 1700 mm.

All of the methods and design of a cyclic mass transfer operation has its advantages and disadvantages and can be used in industrial process, depending on the tasks for increasing mass transfer efficiency in distillation column.

The Maleta cyclic distillation LLC at the conference Distillation and Absorption 2014 showed Pilot Distillation Column in Cyclic Operation

From 14-th to 17-th of September 2014, Friedrichshafen, Germany held the 10th International Conference on Distillation & Absorption 2014. Maleta cyclic distillation LLC (Tallin/EST) participated as sponsor, exhibitor and poster presentation. At the conference Maleta cyclic distillation LLC presented scientific achievements in processes intensification of mass transfer in distillation column through cyclic distillation. The key benefit of cyclic distillation technology is lower investment cost of your project: less column height; smaller column diameter; smaller square of the heat exchanger; less steel construction; consumes less space; improvement of product quality.

More over at exhibition was introduced pilot cyclic distillation column (cold stand) that has 5 distillation trays: two maleta distillation trays and three combined trays (maleta distillation tray + structured packing; maleta distillation tray+ pall ring; maleta tray + catalytic).

We demonstrated advantages of cyclic distillation technology in three cases:

1. First demonstration of cyclic pilot column was for show flexibility of the liquid flow from 5.9 to 29.4 m3/m2hr when factor Fs was constant about 1.9. We can modify the liquid flow in five times. The liquid flow resistance of the column does not depend on the liquid load, because amount of liquid on the tray remains unchanged. In cyclic pilot column we completely control of the fluid amount on the tray and its residence time.

2. Second demonstration of cyclic pilot column was for show flexibility of the vapor flow factor Fs from 1.6 to 3.6 when the liquid flow was constant 9 m3/m2hr. We can modify the vapor load in two times. The upper limit of vapor speed is limited by carryover.

3. Third demonstration was devoted to additional technological capabilities of cyclic distillation technology. It is possible to raise the efficiency of mass transfer due to the location of any type of packing between the trays and, as a result, we get the effect of bubble layer partitioning by height. The most efficient use of structured packing is achieved in a flooded condition and in emulsification mode. In this case, mass transfer area and volumetric mass transfer coefficient are increase up to 1.5…3 times. For cyclic distillation there is no fluid motion from tray to tray during vapor period. The increase in performance of the distillation column by minimizing the flow resistance in the cross-flow of liquid from the tray on a tray (single-phase fluid flow. Also we can place catalytic between maleta distillation trays. It has next technological advantages comparing to classical reactive distillation column: placement catalyst on trays in a boiling layer; ability to control the reaction time; high mass transfer efficiency.

During the exhibition Maleta cyclic distillation LLC informed about company service: pilot plant testing of separation process; basic and detail design; industrial automation and control solution; supplier of mass transfer equipment; reconstruction of the existing column; installation and commissioning work; staff training; project management.

In a poster presentation Maleta cyclic distillation LLC informed about industry implementation of tray dividing-wall columns (DN 1500/1700mm) in cyclic mode.

Increase Efficiency of Distillation Columns through Maleta Distillation Trays

The distillation columns are widely used in chemical, petrochemical, oil refining, gas processing, organic synthesis, pharmaceutical, and other industries for separation of inhomogeneous liquid mixtures. The dominant of the separation processes are the distillation processes, covering about 90%. Energy consumption for distillation can reach up 50% of total energy expenditure total production.

Distillation column sets a cylindrical shell with special internals. The purpose of column internals is to create maximum contact surface phase (mass transfer) and maintain the set of hydrodynamic conditions of their interaction. Implementation of these conditions is possible due to the constructive design of the column internals. All distillation columns we can divide for two types: tray columns design and packed columns design. Examples of tray columns design: sieve distillation tray; tunnel cap tray; bubble cap tray; floating valve tray with rectangular-shaped valves and others; Examples of packed columns design: structured packings; common random packings; pall ring; berl saddle; raschig ring; raschig super-ring and others.

The efficiency of distillation column depends from type internals, diffusion potential factor, viscosity, surface tension of the liquid, and other physical values. High efficiency of mass transfer can provide reducing of capital costs for construction of new and reconstruction of existing facilities; energy saving; improving the quality and increasing the yield of final products.

One of the ways of increase mass transfer efficiency of interaction phase is the use of non-stationary modes. This method is called - cyclic distillation technology and implemented as follows: lack of outflow of liquids to the trays vapor admission; lack of mixing of liquids in adjacent trays upon outflow of liquid. This result is related to the organizational structure of the flow in the distillation column that provides real conditions - the perfect displacement in liquid and vapor. Today, cyclic distillation technology works in stripping column, rectification column and tray dividing wall columns with a diameter ranging from 400 to 1700 mm.

High mass transfer efficiency: a decrease of the column height by half... two thirds and reducing energy consumption by one third through increasing of mass transfer efficiency;

Additional possibilities of columns: tray dividing-wall columns, any geometric shape whatsoever of the trays, combination trays: packing between trays, tray reactive distillation columns;

Self-similar process: the mass transfer efficiency doesn’t depend on the column diameter and simplification of the transfer of the results of physical modeling for industrial columns;

Flexibility of the liquid flow: we can modify the liquid load by one third... two thirds. The liquid flow resistance of the column does not depend on the liquid load. Full control of the amount of fluid on the tray and its residence time in the column;

Flexibility of the vapor flow: we can modify the vapor load by one third ... half. The upper limit of vapor speed is limited by carryover;

Economic benefits: lowering of investment; reduction of operating costs; improvement in product quality; increase in product yield; reduction in the burden on the environment.