High-Pressure Homogenizer 101: Principles, Parameters and Applications

High-pressure homogenization is a technology that uses high pressure to emulsify, disperse and disrupt materials. The high-pressure homogenizer is suitable for fluids, but not for solids and gases. It typically works by forcing a fluid through a homogenizing valve at high pressure, creating a high-energy impact that can disperse or disrupt particles or droplets in the fluid. High-pressure homogenizers are versatile and efficient machines that can be used to improve the quality and stability of a variety of products across a wide range of industries. High-pressure homogenizers are widely used in biopharmaceuticals, nanomaterials, food and cosmetics industry.

The main components of a high-pressure homogenizer include:

i.       Transmission system - used to provide a power source, convert electrical energy into mechanical energy, and drive the plunger pump to work;

ii.       Plunger pump - uses the reciprocating motion of the plunger to generate high-pressure fluid to transport materials to the homogeneous chamber;

iii.       Homogenization chamber – that is, the part where the material is homogenized. The high-pressure fluid produces shear, cavitation, impact effect on the material to disperse the material into a uniform state;

iv.       Homogenization valve – the key component for homogenization process, which is composed of valve seat, valve core and impact ring. It is made of high-pressure resistant and corrosion-resistant materials, usually ceramics, stellite alloy, diamond, etc. The interior of the valve body has a specific geometric shape to produce strong shearing, cavitation, impact and other effects. The homogenizer can be configured with one homogenization valve (single stage) or two homogenization valves (two stages). For most projects, single stage homogenization is sufficient. Two stage homogenization is mainly used in emulsification systems. The pressure of the secondary stage is usually 6-12% of the total pressure. The main purpose of this design is to disperse the emulsified particle size and make the particle size distribution narrower.

v.       Pressure regulating device – used to adjust the distance between the valve core and the valve seat to adjust the homogeneous pressure and control the homogeneity of the material. For laboratory equipment, handle adjustment method is usually used. For pilot and production equipment, the “air-push oil” method is will be used, which can be controlled by knobs or PLC programs.

High pressure homogenizers from ATS Engineering Limited , A Duoning Company

The working process of the high-pressure homogenizer generally includes: the material is transported to the homogenization chamber by the pump, and under high pressure, the material passes through the homogenization valve. In the homogenization valve, the material is subjected to high-speed shearing, cavitation, impact effect, and the large molecules and particles in the material are broken into smaller molecules and particles. Then, the homogenized material is discharged from the homogenization valve. The high-pressure homogenization process is mainly affected by three effects, namely impact force, shear force and cavitation. Among them, the impact force refers to when the material flows through the impact ring under high pressure and collides with the impact ring wall or other materials. It is an important homogenizing force in a high-pressure homogenizer. The shear force is generated through narrow channel in the homogenization valve. In the narrow channel of the homogenization valve, the flow rate of the material will increase sharply, resulting in high shear force. Cavitation means that when the material flows through the homogenization valve at high pressure, in its narrow channel, the flow rate of the material will increase sharply, resulting in a decrease in pressure. When the pressure decreases to a critical value, the dissolved gas in the material will vaporize and form cavities. The cavities will expand rapidly under the impact of high-pressure fluid and generate strong impact and shear forces, thereby disrupting the particles in the material and achieving homogeneity. The shear force, impact force and cavitation in the high-pressure homogenizer have a synergistic effect and can promote each other to improve the homogenization result.

Key operating parameters of high-pressure homogenizers include:

i.       Pressure - Pressure is one of the most important parameters of a high-pressure homogenizer, which determines the homogenization effect. Generally speaking, the higher the pressure, the better the homogenization effect;

ii.       Number of passes – the number of times the material passes through the homogenizer. Generally speaking, the more passes, the better the homogenization effect.

iii.       Homogeneous valve group structure – Different materials require different process capacity. For emulsification systems, it is necessary to provide strong enough shear force to achieve the effect of reducing particle size and uniform distribution. Emulsification systems and disruption systems require different energy. ATS provides different types of homogenization valves to meet different application systems.

iv.       In addition, the feeding flow rate must be considered, and the flow rate determines the production efficiency of the homogenizer. The greater the flow rate, the higher the production efficiency;

v.       Temperature – The homogenization process is a way of converting mechanical energy into kinetic energy and thermal energy. The emulsification and disruption process will be accompanied by the generation of heat. At the same time, long-term work will also accumulate heat, which will affect the performance and use of the homogenizer. life. The ATS homogenizer has a built-in temperature control module, which can control the temperature at the homogenization point to effectively ensure the activity of the material. The ATS production-type homogenizer has an oil pump air cooling system, a plunger cooling system, and a material heat exchange system. From the power end to the working end, the stable operation of the equipment can be guaranteed.

High-pressure homogenizers are widely used in biopharmaceuticals. The most common application is the disruption of various cells to release the products expressed within the cells. For example, when E. coli is used to express recombinant proteins, the products often exist in the cell in the form of inclusion bodies, such as insulin. It is necessary to use a high-pressure homogenizer to lyse the cells to release the inclusion bodies for subsequent purification. In the production process of virus-based vaccines, since many virus particles cannot be effectively released into the extracellular medium during the culture process, a high-pressure homogenizer is also required for cell lysis to release virus particles. In the production of vaccines based on virus-like particle technology using E. coli or yeast, it is also necessary to use a high-pressure homogenizer for cell lysis to release the produced virus-like particles.

Secondly, it can be used in some complex formulations, such as liposomes, albumin nanoparticles, microspheres, emulsions and suspensions. The homogenizer is mainly used to control particle size and achieve uniform distribution of particle size.

High-pressure homogenizers also have many applications in cosmetics, from cosmetic raw materials to finished cosmetics, such as:

i.       Emulsification - cosmetics such as lotions, creams are all emulsification systems. During the emulsification process, the high-pressure homogenizer can evenly disperse the oil phase and water phase through high shear force and cavitation, thereby preparing an emulsified system with good stability;

ii.       Dispersion - Substances such as pigments, flavors, and active ingredients play an important role in cosmetics, but these substances need to be evenly dispersed to achieve their desired effects. The high-pressure homogenizer can evenly disperse pigments, flavors, active ingredients and other substances, thereby improving the effectiveness of cosmetics.

iii.       Cell wall disruption – generally used to make cosmetic raw materials. Many active ingredients in cosmetics are produced on a large scale through biological fermentation. Some of these active ingredients exist in cells and need disruption process to be released. The high-pressure homogenizer can disrupt the cells and release the active ingredients inside the cells.

iv.       Encapsulation – Some cosmetic active ingredients are prone to oxidation and light instability, and need to be encapsulated in liposomes or other materials. The high-pressure homogenizer can achieve the effect of encapsulating liposomes and controlling particle size uniformity.

High-pressure homogenization is also a commonly used technology in food. For example, it is used to evenly disperse the fat globules in milk, thereby improving the stability and taste of milk; it is used to evenly disperse the pulp particles in juice, thereby improving the taste and nutritional value; as well as some enteral nutrition milk, microcapsule encapsulation and other applications

Another application area of high-pressure homogenizer is material science, such as the preparation of nanomaterials, including the preparation of nanocellulose and nanocarbon materials, such as carbon black for conductive slurries, carbon nanotubes and graphene dispersion, and Pt/C catalyst for electrocatalysis, and prepare polishing liquid such as some nano-alumina slurry.

To summarize, the main advantages of high-pressure homogenizers in various applications include:

Ÿ   Good homogenization result - the high-pressure homogenizer can generate strong shearing force, impact force and cavitation effect, thereby effectively reducing the size of the material or uniformly dispersing it;

Ÿ   Simple operation - the operation of the high-pressure homogenizer is relatively simple, easy to realize automation, and improves production efficiency;

Ÿ   High cost-effectiveness – Compared with technologies such as ultrasound, the cost of high-pressure homogenizers is relatively low, which improves the economy of the production process.

In the future, the achievable pressure and flow rate of the high-pressure homogenizers may be further increased, and the structure and control system of the homogenization chamber may be further improved, so that it can be used in a wider range of fields.