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in this guide we have described all details about rotary evaporator or Rotovap

A Rotary Evaporator, also popularly known as a Rotavapor or Rotovap, is a specialized and extremely versatile equipment for chemical processes.

In this Article, we would touch upon the following broad topics:

Rotary Evaporator Principle
Rotary Evaporator Construction
Rotary Evaporator Design Variations
Rotary Evaporator Applications
Other Evaporation Alternatives to Rotovap

What is a Rotary Evaporator or Rotovap?

As per name we can understand by seperating two terms one is rotary and second is evaporator

Rotary means rotating movement and Evaporator means evaporation process of some liquid or fluid

Rotary Evaporator Principle

The Evaporator is essentially working on the same principles as a distillation unit i.e. separation of components having different boiling points. However, few special design features make the functioning of the Rotovap unique and versatile.

Operation under high vacuum of 1 torr, thereby reducing the solvent boiling points under vacuum considerably as compared to the boiling point under atmospheric conditions.
Constant rotation of Rotary flask results in a thin layer of process media on the inner wall, thereby ensuring uniform heating across the entire mass, and less possibility of bumping.
The rotation of flask immersed in the bath increases the surface area of evaporation greatly, thereby increasing the speed of distillation.
The rotation mechanism also makes it suitable for volatile and heat-sensitive process media, wherein the properties can alter if direct high heat is applied for longer time. This is because due to rotation, the process feed is evenly mixed.
Plug and Play type of construction making it easy to switch the configuration for different applications.

The Rotary Evaporator is normally always operated under high vacuum. The Feed is charged inside the rotary flask from the feed tube made of PTFE.

Ideally, feed up to a maximum of 70–80% capacity of the rotary flask is desired for optimum results. Once the feed is charged, the rotation is started.

Also, the utility circulation in the condenser is started. This rotation action creates a thin film of process feed on the wall of the rotating flask.

Next the heating is started. The rotary evaporator procedure is very crucial for efficient performance. Once the oil in the bath starts heating, and this heat is indirectly passed to the process feed inside the flask.

As the process feed gets heated, the low boiler converts into vapours, and goes up the vapour tube and into the condenser, where the condensate is formed.

This condensate can either be refluxed back into the rotary flask for higher purity applications, or collected in the receiver.

Depending on the design features, a lot of different process possibilities are there, but the basic operating principle essentially remains as indicated above.

How does a vacuum evaporator work (Construction)?

The main components of a Standard Rotary Evaporator are enlisted below:

The water/oil bath is a heated bath which encloses the main rotary flask and is used to indirectly heat the contents of the process.

The bath is usually equipped with electric heaters which can be ATEX-compliant or weather-proof, depending on the application area’s Hazardous Zone Classification.

As a safety feature, the bath is appropriately insulated so that the outside surface is not too hot to touch.

The Rotary Flask is the main component where the process fluid is initially charged, and is made of Borosilicate Glass 3.3 raw material.

The Flask’s construction is of prime importance for the smooth rotation along the central axis.

Our advanced manufacturing techniques ensure that the evaporating flask is rotating perfectly along the central axis, thereby ensuring that the entire surface area comes in contact for the same time with the heating media in bath.

The Mechanical Seal, along with the motor unit connected to the flask is responsible for smooth and leak proof rotation of the flask at a constant speed.

An RTD is placed just above the vapour tube to measure the vapour temperature before it goes into condenser.

The RTD is inserted inside the vapour tube in a glass thermowell. This ensures that the contact parts are strictly Borosilicate Glass 3.3 and PTFE only and the metal tip of PT-100 sensor does not come in direct contact with the process vapour.

A Shell & Coil type condenser of suitable heat transfer area is chosen so that there is no pressure build-up due to excessive un-condensed vapours.

The condenser is preferably placed in vertical orientation for efficient condensation.

Different configurations with single and double condensers are available depending on the application. As a standard, a single condenser is provided.

Shell & Coil type condenser Ablaze Glass Works

A vent is provided at the top of the condenser. This can be used for venting in the case of excessive pressure build-up.

We can also connect the vacuum pump here. Alternatively, the vacuum pump connection can be made at the receiver vent nozzle.

All such vent outlets are equipped with suitable valves with leak-proof PTFE bellow to glass connections.

The vent valve is provided with GL18 thread at the end, where BOLA connectors can be placed and hose pipe connected.

This arrangement provides seamless connection without any leakages.

The Liquid feed is used to feed the process feed into the rotary flask without breaking the process vacuum.

Since the system is already under vacuum, the process feed easily flows into the system.

This valve too is provided with GL thread and BOLA connector. This valve is connected with a PTFE tube which travels throughout the vapour tube, directly into the rotary Flask.

This ensures that the feed does not get carried to the receiver directly along with the vapour or condensate flowing in the vapour tube.

A Product Cooler is essential to cool down the condensate, before moving it to the receiver.

The product cooler is essentially a Shell & Coil type heat exchanger with the process fluid in the coil side and utility in the shell side.

This arrangement ensures rapid cooling in a short time.

The receivers are spherical vessels with multiple nozzles of a suitable size. The units usually have either one or two receivers, connected in parallel.

The receiving vessel has a short drip tube to ensure that the solvent drops down directly into the vessel and not flow along the walls.

A Control Panel is an integral part of the Rotary Evaporator. This is a highly customized part and Ablaze can offer partial to full automation of the process through the control panel, depending on the client’s process requirement.

As a standard, the basic model has provision for digital display of Bath temperature, Vapour Temperature and RPM of the Rotary Flask. It also has controls to set the desired RPM and the desired Oil Bath Temperature.

In a little advanced models, Vacuum control and monitoring is also provided, wherein the vacuum pump is connected via the panel and the required process vacuum can be set, monitored and controlled directly through the panel.

Further customization and control can be provided, since we have a highly advanced in-house automation team.

The Panel and all the electric components are housed in an ATEX-Compliant Enclosure for operation in hazardous areas.

The Entire Rotary Evaporator System is mounted on a Compact Skid of Stainless Steel where all the components rest and all provided appropriate support to ensure vibration free operation.

This skid itself is mounted on heavy duty Castor Wheels, which can be locked, to provide easy movement of the unit in the plant or lab.

A Safety Lid is placed on the rotary flask as a precaution in case of spillage risk. It is transparent and hence it provides safety without compromising on the reaction visibility.

3. Rotary Evaporator Design Variations

Multiple Design Variations are available in Our Standard Rotary Film Evaporator to suit different process needs. Some of the standard design variations are:

Dual Receivers

This configuration allows continuous drain without breaking the process vacuum. The two receivers are connected in parallel so that at any given point of time, the condensate is being collected in one of them.

Once this receiver is full and needs to be drained out, the valve above it is closed, and the condensate is taken in the second receiver.

This way, the system vacuum is not disturbed during draining.

Dual Condensers

This design is used when immediate condensation of the vapours is required. Two condensers are placed in parallel, and the condensate is directly collected in the receivers.

This ensures 100% solvent recovery. This design can also be modified for continuous operation.

ATEX-Compliant

The Rotavap contains a lot of electric components — two sets of drive (one for rotation and other for bath lifting) and a control panel.

We do understand that a lot of applications require the Rotovap to be used in Zone 0 / 1 / 2 hazardous classified area and hence we have a model with all electrical components and connection which comply to these stringent requirements.

Multiple MOCs

The contact parts with process media are strictly Borosilicate Glass 3.3 and PTFE. However, the couplings, skid etc do not come in contact with the process media and can be offered in various MOCs (Material of Construction) such as Stainless Steel grade 316 or 304, Mild Steel, etc.

The couplings can also be made of Bakelite to provide good resistance to corrosion in case the environment has exposure to corrosive gases. The fasteners can be PTFE coated to improve their life.

4. Rotary Evaporator Applications

The wide array of applications where a rotovap can be used shows how versatile the equipment is. It finds application in the following processes:

Distillation (Continuous and Discontinuous)
Concentration
Solvent Recycling
Solvent Evaporation and Recycling
Reflux Process Reactions
Component Drying
Component Purification
Fine Chemical Synthesis
Crystallization
Molecular Cooking

5. Other Evaporation Alternatives to Rotovap

There are few other Process Equipments which have similar functionality as Rotary Evaporator and are used specially for Evaporation.

1)Falling Film Evaporator

A Falling Film Evaporator is essentially similar to a Vertical Shell & Tube Heat Exchanger in construction. The process fluid enters the evaporator from top and flows in a thin film along the walls of tubes. The same is instantly converted into vapour by the hot utility flowing in the shell. This Evaporator is completely custom designed as per the process requirement.

2)Wiped Film Evaporator

A wiped Film Evaporator is essentially a thin film Evaporator (TFE) just like a rotovap. It works on the principle of the thermal separation of products in a mechanically generated, thin and highly turbulent liquid film along the outer surface of the evaporator.

Having worked on Rotary Evaporators for over 20 years, we have various case studies of their application in non-traditional applications as well. So if you require a rotary evaporator or have any process with which you need assistance, do reach out at marketing@ablazeglassworks.com

In this article, we are going to discuss a Scientific Glass Equipment known as Jacketed Glass Reactor.

Scientific Glass Equipment is widely used in laboratories and industrial research labs, chemical labs, and process plants, where pilot plants are used for capturing process data.

It is a crucial stage in scale-up from laboratory to full-scale production plants. A reactor is an essential part of almost all chemical process units.

It is rightly termed as the ‘heart’ of the system since it is the most critical component.

A Borosilicate glass reactor offers a distinctive advantage of reaction visibility, which is impossible in other construction materials.

However, traditional eating methods the contents of the glass reactor forced the users to compromise on the visibility advantage.

This triggered the development of Glass Jacketed Reactor Vessels.

Other advantages of borosilicate glass as a process media include its non-reactive nature with practically most chemicals.

Also, it is highly corrosion resistant and hence lends itself for use with a varied range of chemical reactions with different reactants and solvents.

What is a Jacketed Glass Reactor

A Jacketed Glass Reactor vessel is used to control the temperature of its contents, with the help of an additional glass jacket that surrounds the inner container in which the reactants are placed.

By design, a Glass Jacketed Reactor is a vessel that is enclosed by a jacket of glass where the heating/cooling fluid circulates to control the reaction temperature within the vessel.

Heat transfer takes place through the borosilicate glass wall. The jacket is an isolated compartment around the inner vessel, and the contents of the vessel and the jacket do not come in direct contact.

The reaction media is being stirred continuously during the process of heating.

This improves the homogeneity of the reaction mass, avoids localized heating along the walls of the reactor, and ensures uniform heat throughout the reaction mass.

The jacket is provided with a separate inlet and outlet for the heating/cooling media circulation.

Depending on the requirement, a nozzle for venting may also be provided in the jacket part.

At times, an additional jacket is required for insulation purposes over the jacket used for heating/cooling fluid circulation.

In such cases, the double jacketed reactors (also known as triple wall reactors).

This new jacket is vacuum sealed, and hence eliminates heat loss to the atmosphere.

This allows for the process to be monitored without any frost formation on the jacket’s outer surface, thus ensuring visibility even in cryogenic reactions.

These reactors are provided with the usual accessories of a reaction unit such as stirrer assembly with drive, valves and supporting structure.

The further reaction assembly to be connected to a vapor nozzle can also be additionally provided, if required.

Types of Jacketed Glass Reactor

These are highly customized reaction units and are designed as per customer’s requirements.

There are different capacities of Jacketed Glass reactors that are available.

The different sizes can be chosen depending on the process’s requirement, the batch size, and the solvent requirements in the batch.

Standard units are available for general reactions up to a capacity of 50 liters and are designed to fulfill the chemical and pharma industry’s actual needs.

Ablaze glass reactors are built for batch and semi-batch operation mode, with perfectly matched components and quality materials.

They conform to GMP / FDA Guidelines, and Explosion-proof installations can also be done if required.

Ablaze is a global Scientific Borosilicate glass equipment manufacturer located at Vadodara, Gujarat, India.

These Jacketed Glass Reactors are widely used in various industries like chemical, food, pharmaceuticals, agrochemicals, APIs, dyes, aromatics, etc.

Jacketed Glass Reactors Features and usage

Do you know what a jacketed glass reactor and its features and usages are? We will enlist the key elements in this section.

A jacketed glass reactor is essentially a reactor where a glass jacket has replaced the traditional heating oil bath.

This new, improved design offers distinctive advantages during operation.

The heating media flow can be controlled and monitored with the help of vales placed at the inlet.

A valve is not placed at the outlet of the jacket to avoid accidents.

If a valve was placed at the outlet, and it was closed by mistake, the pressure may build-up in the reactor jacket.

These design considerations from an operational point of view make Ablaze units sturdy and easy to operate.

Heat transfer takes place across the glass wall between the inner vessel and the jacket, and the vessel is so manufactured that the jacket area always covers the nominal volume of the reactor.

The nozzles are provided with universal M16/M30 connections so that the reactor can be connected to any International reputed Temperature Control Unit (TCU).

The jacketed reactor’s jacket also acts as a cooling jacket.

A cooling jacket has the ability to stop the upward spiral of hotter temperatures increasing the rate of reaction that produces even more heat;

and cooling liquids flow through the jacket resulting in collecting heat energy from the outer surface of the reactor.

Salient Features:

Complete visibility of reaction
Minimized heat loss to the atmosphere
Ease of cleaning
Reduced frost formation in cryogenic reactions
Higher heat transfer efficiency
Compact construction

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Rotary Evaporator – All you need to know