Risk analysis of WFI preparation system

1. High pressure operation may bring high steam speed steam friction, which will cause intergranular corrosion of austenitic stainless steel between inner cylinder and spiral plate, and crack phenomenon. Leakage of evaporator will lead to unqualified heat source in product injection water.

2. If the condensed water in the industrial steam intake pipe of the first effect evaporator of the distilled water machine is discharged in steps, it will corrode the first effect evaporator pipe. At the same time, the startup will be accompanied with water hammer phenomenon, which is easy to crack the welds of the evaporator and cause leakage.

3. The double tube plate design of evaporator, condenser and preheater is faced with leakage risk. If the expansion joint process is unreasonable, cracks will appear at the expansion joint, and the heat source will be unqualified due to the cross contamination of external medium and finished water; another situation is that the expansion joint is not considered due to the design reason, which makes the thermal stress between the cylinder and the tube row inconsistent, and the expansion joint part of the tube will exceed the tensile strength. If it breaks, it will be irreparable.

Installation risk:

If the condensed water of the first effect evaporator is discharged under the back pressure condition, it is easy to cause inaccurate pressure gauge, the actual steam pressure is not so high, and the pressure sensor can not detect it; the ineffective concentrated shrinkage discharge can not be connected with the water, once the distilled water machine vacuum will suck the sewage into the condenser, it will cause the pollution of the injection water system and it is very difficult to clean.

Operational risk:

Whether the diaphragm of the diaphragm valve is sealed; whether the check valve on the upper part of the raw water valve group can prevent the flow of high temperature water; whether the regulation of the valve group complies with the linear rule; whether the end steam trap is blocked and affects the operation, etc.

Risk of distortion of pressure gauge, regulating valve and flowmeter:

The pressure indication is inaccurate due to the vibration of the pressure gauge needle, and the calibration result is inaccurate; whether the regulating valve conforms to the regulation law; whether the flowmeter has accurate output and accurately matches the feed water quantity of the raw water with the regulating valve.

High level jump operation risk:

When the liquid level of primary and final effect evaporators of multi small distillers often jumps, which causes frequent regulation of water supply valves, the distillation process will be unstable, resulting in deterioration of water quality.

Risks caused by large fluctuation of industrial steam pressure

Large fluctuation of industrial steam pressure is the main factor that affects the operation of the distilled water machine. If the fluctuation is very small, the operation of the distilled water machine will be very stable, and the purity of the injection water will be kept continuously stable.

Material risk:

The material is very important for the distilled water machine. For example, the 304 material is used for the production of water for injection in high-temperature parts. After a period of use, its internal color is brown. After a period of shutdown, there will be rusty impurities falling off and small black spots in the water. This kind of impurity is not easy to clean, only the scale on the inner surface washed by continuous water will disappear, but the quality of drugs may be affected.

Risk of frost cracking:

After the delivery test in winter, the distilled water machine is delivered to the pharmaceutical factory. During the installation and commissioning, leakage may be found in some parts, which is caused by the residual water not completely drained and frozen crack. If the machine is shut down and discharged immediately after the delivery test, this kind of thing will be avoided. When the pharmaceutical factory stops production and maintenance in winter, it should also be noted that this kind of risk may exist if the indoor temperature is lower than 0 ℃.