Design of Pasteurization System in Purified Water Equipment

1. Requirements for pharmaceutical water

Pharmaceutical water usually refers to water of various quality standards used in the pharmaceutical process, which is divided into purified water, water for injection, and sterilized water for injection according to the scope of application. The main difference between purified water, water for injection and sterile water for injection is the index of conductivity, bacterial endotoxin and microbial limit.

In pharmaceutical production, the water quality of water is directly related to the quality of products. Therefore, pharmaceutical companies attach great importance to all aspects of water system design, installation, verification, operation and maintenance. In order to produce water that meets quality standards, continuous water quality monitoring is required. In previous drug GMP inspections, the water system is often the focus of the inspection.

Purified water quality assurance In addition to the design and production of pharmaceutical purified water systems that must strictly follow GMP requirements, it is also necessary to design a reasonable disinfection system. Pasteurization often uses hot water circulation above 80°C for 1-2 hours to achieve pasteurization of the system, which can effectively control the microbial contamination level in the purified water system to 50CFU/ml, and can control the internal temperature of the purified water equipment system. The toxin was at the level of 5 EU/ml.

2. Design of pasteurization system

1）. Structure and selection

Since the purified water system is a closed water system, in order to heat the purified water in the system to above 80°C, a steam heat exchanger can be installed outside the circulating water pump, and a temperature probe can be installed before and after the heat exchanger. Taking the temperature before the heat exchanger as the input of the control system, and the steam valve of the heat exchanger as the output, the materials needed for the pasteurization system are: controller, electronic valve, temperature probe and heat exchanger.

2）. Selection and installation of temperature probe

In order to reduce the sanitary dead angle as much as possible, the temperature probe of the hygienic quick-opening link is specially customized. The requirement is that the sensor is welded to the center point of the stainless steel blind plate, and the insertion depth is the quick-opening link. After the probe just reaches the central axis of the purified water pipeline . The transmission line of the temperature probe adopts a shielded three-core signal cable to reduce electromagnetic interference generated by surrounding water pumps and power lines.

The front pipe near the heat exchanger should be the coldest point of the entire purified water delivery system. Considering the influence of uniform and stable water flow on temperature measurement, the installation position of the temperature probe is selected on the straight pipe of the heat exchanger.

3）. Selection of heat exchanger

The heat exchanger is the core equipment of the pasteurization system, so the selection of the heat exchanger is particularly important for the disinfection effect.

There are many types of heat exchangers, each of which has a specific application area. According to its structural characteristics, there are tube heat exchangers, plate heat exchangers, extended surface heat exchangers, and heat storage heat exchangers. In the specific application of pharmaceutical purified water system, it is necessary to consider the actual needs and choose flexibly. When Kerui provided Zhuhai Jianfan with a complete set of purified water and water for injection system solutions, it used plate heat exchangers.

Kerui technicians summed up several aspects that should be paid attention to when choosing a heat exchanger:

（1）. Heat load and flow rate

（2）. The nature of the fluid

（3）. Temperature, pressure and allowable pressure drop range

（4）. Requirements for cleaning and maintenance

（5）. The structure, material, size and weight of the equipment

（6）. Price, use safety and lifespan