The agitator is one of the core components of the reaction kettle. Selecting the appropriate agitator based on the physical characteristics, volume, and stirring destination of different substances inside the kettle can greatly promote the rate of chemical change and improve productivity.

Mastering the classification and available locations of mixers is beneficial for selecting suitable mixers and achieving stronger reflection of actual effects. Learn from online editors!

Application of reaction kettle

A reaction kettle is a high-pressure vessel widely used in crude oil, chemical plants, vulcanized rubber, fertilizers, dyes, pharmaceuticals, and food industries for the entire processing of vulcanized rubber, nitration reactions, esterification, alkylation, polymers, condensation reactions, and other processing technologies.

Composition of reaction kettle

The reaction kettle consists of a kettle body, kettle cover, cylinder clamp, stirrer, gear transmission, water pump sealing equipment, support plate, etc.

Electric heating reactor

1. Cover shell of reaction kettle

The casing consists of a circular head, a top cover, and a lower stainless steel head. There are two ways to connect the top cover and the head. One is to immediately weld the outer cover and the head together to form a whole; Another way is to consider the convenience of disassembly and assembly, which can be connected with flanges. There are many manholes on the top cover, as well as connections between manholes and processing techniques.

Mixing equipment for 2 reaction vessels

In a reaction vessel, stirring equipment is generally equipped to accelerate reaction time, improve mixing, and enhance convective heat transfer or heat conduction efficiency. It consists of a stirrer and a stirring shaft, which are connected to a gear drive through a coupling.

Sealing equipment for 3 reaction vessels

The sealing equipment used in the reaction vessel is a dynamic sealing structure, which includes two key types: packing seal and machine seal.

Classification and Model Selection of Reactor Agitators

The efficacy of the reactor agitator

Mix raw materials evenly, enhance heat conduction and convective heat transfer, including homogeneous liquid mixing; Liquid-liquid dispersion; Gas-liquid dispersion; Solid-liquid dispersion; Crystalline body; Solid-state melting; Strengthen heat conduction, etc.

Construction of Reactor Agitator

Basic principle of stirring in electric heating reactor

The mixer is a key component for maintaining the actual operation of mixing, and its key component is the centrifugal impeller, which releases mechanical kinetic energy to the liquid during the circular motion and promotes the liquid's fitness movement.

When the agitator rotates, it transfers mechanical kinetic energy to the fluid, creating a highly turbulent and sufficient mixing zone around the agitator, and creating a high-speed water jet to promote the circulation of the liquid inside the agitator truck.

Factors affecting reactor stirring

The way in which a liquid flows in a circulating system within the scope of machinery and equipment is called the "flow entity model" of the liquid, commonly known as the "flow pattern".

The flow pattern is closely related to the actual mixing effect and mixing output power. The flow pattern is determined by the method of the mixer, the geometric characteristics of the mixing vessel and internal prefabricated components, as well as the fluid characteristics, mixer speed ratio, and other factors.

Radial flow

The direction of fluid flow is parallel to the stirring shaft, and the fluid is promoted by the blades, causing the fluid to flow downwards, hit the bottom edge of the vessel, and then flip upwards, generating a left and right circulation system flow.

Axial

The fluid flow direction is perpendicular to the stirring shaft, flowing along the axial direction. When encountering the boundary layer of the vessel, it is divided into two streams of fluid, each flowing upward and downward, and then returning to the blade end without crossing the blade, creating two circulation systems of flow, upper and lower.

Radial flow

In a vessel without partitions, the fluid rotates around the axis for fitness exercise. When the water flow rate is high, vortices will be generated on the surface of the liquid. The total flow rate of the fluid sucked from the periphery of the blade to the blade area is not large, and the actual mixing effect is poor.

The three flow patterns generally exist separately; The mixing of radial flow and axial flow plays a crucial role; Radial flow should be suppressed in multiple ways - using baffles can weaken radial flow and improve both radial and axial flow.

Classification and applicable locations of reactor stirrers

Paddle type, push type, pressurized type, and anchor type agitators are commonly used in stirred reaction equipment, accounting for about 75-80% of the total number of agitators according to surveys.

1 paddle mixer

Composed of blades, keys, collars, and vertical shafts. Paddles are generally made of galvanized flat steel, stainless steel plates, or rare metals. The rotational speed of a paddle mixer is relatively low, generally ranging from 20 to 80r/min. The diameter of the paddle stirrer is taken as the nominal diameter of the reaction vessel Di/3~2/3. The paddle blades are not suitable for being too long. When the diameter of the reaction vessel is quite large, two or more paddle blades should be selected.

Key applications:

The paddle mixer is suitable for liquid raw materials with high fluidity and low viscosity, as well as fiber and crystalline melt liquids. When the raw material layer is deep, several rows of paddle blades can be installed on the shaft. The folded blade propeller has less power and lower actual operating costs compared to the vertical blade propeller, so it is widely used.

Paddle agitator cannot be used to maintain gas-liquid dispersion with the aim of miniaturization in practical operations.

2 Push type mixer

A push type mixer is used to circulate the raw materials inside the reactor truck during mixing, with the capacity circulation system playing a dominant role. The cutting effect is relatively small, and the actual effect of rolling left and right is excellent. When a larger water flow rate is necessary, a drainage tube is installed inside the reaction vessel.

The standard push type mixer has three leaves with a tooth pitch equal to the propeller diameter d. The diameter of the push type stirrer is taken as 1/4~1/3300~600r/min of the nominal diameter Di of the reaction kettle. The raw materials of the stirrer are commonly pig iron and cast steel parts.

Characteristics of a push mixer:

Radial flow agitator; The circulation system has a large volume, but the stirring output power is small; Simple construction and convenient production and manufacturing; Commonly found in low viscosity fluids.

3 pressurized agitator

The speed of the booster mixer is very high, ranging from 300 to 600 r/min. The straight and curved blade boosting agitators are critical in causing axial flow, while the folded blade boosting agitator is critical in causing radial flow.

The key advantage of a pressurized mixer is that it has high mixing efficiency when calorie consumption is not high, resulting in strong axial flow. Therefore, it is suitable for emulsions, mixtures, etc.

4 Anchor mixer

Suitable for stirring fluids with viscosity below 100Pa · s. When the viscosity of the fluid is between 10-100Pa · s, a transverse blade can be added in the middle of the anchor blade, which is a bar stirrer, to enhance the mixing in the middle of the vessel.

Characteristics of anchor mixer:

Simple construction and convenient production and manufacturing; Suitable for raw materials with high viscosity and large output; Easy to obtain large surface thermal conductivity; Can reduce the risk of wall hanging.