Limpet coil reactors

I Overview and categories

Limpet Coil Reactor is also called an External Coil Reactor or Spiral Half Pipe Reactor, which is generally used as a batch reactor. It can also be used as a continuous reaction unit with a material-conveying connection system.

Because the pressure inside the vessel is more than 0.1 MPa, sometimes subject to internal and external pressure, the limpet coil reactor is a pressure vessel.

II Working Principle:

The working principle of the limpet coil reactor is to put reaction solvent into the kettle for stirring reaction, and the external coil can be connected with different hot and cold sources (refrigerating liquid, hot water, or hot oil) for circulating heating or cooling reaction.

By injecting constant temperature (high or low temperature) hot solvent media or cooling media, the reaction mediums can be heated or cooled at constant temperature.

The stirred reaction runs under atmospheric pressure or negative pressure as per the requirements.

The materials are reacted in the reaction kettle, and the evaporation and reflux of the reaction solution can be controlled. 

After the reaction is finished, the materials can be released via the discharge port at the bottom of the kettle, which makes the operation easy.

III Structure:

The limpet coil reactor is mainly composed of a reactor body, external spiral coil, heat transfer medium, stirrer, inlet ports, outlet ports, drain port, thermometer, manometer, and so on.


The reactor body is usually made of high-temperature resistant materials such as carbon manganese steel, stainless steel, zirconium, nickel-based (Hastelloy, Monel) alloys, and other composite materials in general, which have good corrosion resistance and pressure resistance. The reaction kettle body and kettle head are generally connected by welding.


The external coil injects the heat transfer medium (such as hot oil), which exchanges heat with the reaction mediums in the kettle.


The stirrer is to stir the materials in the kettle evenly, to the uniformity of the reaction and the degree of adequacy.


There are corresponding process pipe ports on the lid of the reaction kettle, and the lower head of the reaction kettle is opened with a discharge port. There are process pipe holes on the lid for feeding, stirring and observing, temperature and pressure measurement, steam diversion, and safety venting.


The reactor external wall is welded with support, for suspension or support purposes.

IV Features of limpet coil reactor

4.1 Appearance characteristics:

photo of limpet coil reactor  Obvious features, the kettle body has an external spiral coil welded, and there is a gap between the circles of the coil.

4.2 Fabrication characteristics

The outer coil reactor needs to make the outer coil separately.
Fabrication steps:
4.2.1 Prepare a carbon steel plate of 5mm thickness, and design the width according to the radius of tube forming, take 89 tubes as an example, it can be prepared 140mm wide.
4.2.2 Put it into the semi-circular pipe forming machine, the mold is the core of the semi-circular pipe forming.
4.2.3 Press and mold the plate into half pipe, and roll it round. Weld it to the periphery of the reactor
picture shows the process of limpet coil producing

4.3 Performance characteristics

(1) Fast reaction speed:

the limpet coil reactor adopts high temperature and high-pressure reaction conditions, which can speed up the reaction speed.

(2) Uniform reaction:

the stirrer inside the external coiled reactor can stir the materials inside the reactor evenly.

(3) Easy operation:

the operation of an external coil reactor is relatively simple, only needs to operate according to the set temperature and pressure.

(4) Wide range of applications:

the external coil reactor can be used for various chemical reactions, with a wide range of applications.

V Advantages of Limpet Coil Reactor Compared with Ordinary Reactor

5.1. High bearing capacity

The external coiled reactor has the design of a spiral outer coil, and the structural characteristics of the external coiled reactor increase the overall bearing capacity of the reactor body.

Under the same temperature and pressure, the wall thickness of an ordinary reactor is higher than that of an external coil reactor, which is clumsy.

In the case of the same wall thickness, the outer coiled reactor has a stronger pressure-bearing capacity.

5.2. High heat transfer efficiency

Compared with the common reactor, an external coil reactor can also improve the heat transfer efficiency of the whole reaction. Since the structural design of external coil heating reduces the heat transfer efficiency of the equipment, it is more advantageous than ordinary reactors.

5.3. Cost saving

As the external coil reactor has a good heat transfer rate, it can save energy and reduce consumption.
The wall thickness of the stainless steel reactor body and lower cylinder cover is 37.5% to 50% thinner than ordinary stainless steel reactor.
The outer coil reactor can strengthen the heat transfer efficiency of the equipment, which can not only be used as a heat source but also reduce the air thermal resistance of the jacketed reactor without worrying about energy consumption.
The outer coil reactor can make the raw material production achieve very ideal results.

5.4. Space saving

Under the same working volume, the diameter of the outer coil reactor is smaller than that of the common reactor, which is more delicate and conducive to the layout of the production workshop.

5.5. Energy saving

Generally speaking, the heating method of an external coil reactor is different from that of a common reactor. The external coiled reactor is heated by the heat-conducting oil delivered by the heat carrier furnace, which is characterized by low energy consumption, while most of the ordinary reactors are heated by electric heating, which consumes a lot of energy.

5.6. Environmental protection

Traditional reactor often produces a large amount of waste gas, wastewater, and other pollutants during the production process, while the external coil reactor adopts a closed design, which can effectively reduce the emission of harmful gases, reduce environmental pollution, and provide sustainable development for the enterprise.

VI Advantages of external coil reactor compared with ordinary jacketed reactor:

6.1 Low manufacturing cost

Cylinder jacketed reactor can achieve heat transfer efficiency without interruption or loss, but the whole inner cylinder becomes a pressurized space, which will make the inner cylinder plate thicker, increasing the equipment manufacturing cost.
As the outer coil greatly improves the inner cylinder force state, the inner cylinder wall thickness is relatively thin.
The ratio of jacket volume to half-pipe volume is 8:1, saving investment.

6.2 Energy input cost is small

Since the outer coiler is welded and processed with a gap, when the required heat transfer is the same, the heat transfer area of the outer coiler reactor is correspondingly smaller, which saves energy consumption and reduces the cost investment;

6.3 Low requirement for heat transfer medium

Take steam heat transfer as an example, the use of a cylinder jacketed kettle, often controls the steam pressure at 0.4 MPa, while for the external coil jacketed kettle, steam pressure can be 0.7 ~ 1.3 MPa, no need to depressurize.

VII External Coil Reactor Specifications

7.1 Overview of specifications

Volume: 2000 liters to 30,000 liters
Temperature: -196°C to 350°C.
Pressure: -0.1 to 3Mpa
Pressure on outer coil: 0.6 to 2.5MPa
Heating medium: steam, thermal oil, cooling water, etc.
Motor power: 2.2-4KW
Inner diameter: over 900mm
Stirring speed: more than 160 rpm. Adopts  constantly variable motor, speed 0-1250 rpm
Jacket heating type:
Electric heating rod heating, steam heating, thermal oil circulation heating.
Shaft sealing device: packing seal, mechanical seal, and magnetic seal.
Stirrer type: anchor type, paddle type, turbine type, propulsion type, or frame type.
The number of openings, specifications, or other requirements can be designed and produced according to user requirements.

7.2 Table of volume, coils heat exchange area of external coil reactor:

 Specification  Full volume(L)  Vessel inner diameter(mm)  Outer coil heat transfer area (M^2)  Inner coil heat transfer area(M^2)  Motor power(kw)
 500L  550  900  2.438  2  2.2
 1000L  1100  1100  2.867  2.6  4
 1500L  1650  1200  3.537  3.1  4
 2000L  2200  1300  4.165  3.8  5.5
 3000L  3300  1500  5.569  5.4  7.5
 6000L  6600  1800  10.323  8.7  15
 10000L  11000  2200  50.345  10.9  22
 20000L  22000  2400  101.679  13.8  55

VIII External Coil Application Field:

The external coiled tube reactor is widely used in petrochemical, pharmaceutical, food, cosmetic, and other fields, such as the preparation of polymer materials, the preparation of fine chemicals, the preparation of drugs, and so on.

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