Online Security Detection Research On Pressure Vessels In Ammonia Refrigeration System Using Acoustic Emission Technology

With the development of economy, cold storage pressure vessel is growing quickly in our country. It belongs to special equipment. Its normal inspection requires stopping running, removing the insulating layer, and then replacing the ammonia liquid medium completely. This makes the enterprise face a series of problems during the production, such as not convenient parking, difficulty to thoroughly cleaning and replacement of ammonia even if in device downtime, the economic burden of removing the heat preservation layer, etc. All these lead to that most cold storage pressure vessel can not be inspected at predetermined time. So, cold pressure vessel’s safety problem has attracted great attention. In order to ensure the safe operation and better service to industrial production, it is urgent to develop an online detection method without dismantling insulation layer.Based on other researches, the paper developed a method of online defects and safety assessment technology of ammonia refrigeration system using acoustic emission detection technology. The cold storage pressure vessel should not be shut down for internal inspection. First, an acoustic emission testing of ammonia refrigeration pressure vessel were carried on online, Then, a conventional nondestructive testing methods were conducted in the stop running state. The compared results show that AE testing can give accurate location and correct judgment of all the serious defects of cold storage pressure vessel. This shows that the method of acoustic emission technology online detection is feasible and reliable. The paper summarized a working process of acoustic emission testing on cold storage pressure vessel based on it. According to the process another pressure vessel with heat insulation layer was implemented for further verification. The results of statistics and analysis of acoustic emission testing were carried for a number of cold storage pressure vessel. All these demonstrated the method is feasibility and integrity. Research results shows that by changing the equipment pressure, AE testing can detect main activities of defects and give accurate positioning, and can guarantee the safety of cold storage pressure vessel by removing the potential safety hazard quickly and accurately. So, we can conclude that AE testing can eliminate the blindness and low efficiency which the conventional nondestructive detection methods encountered, and can short testing time also. It can find defects and give warnings in the early operational phase, so we can prevent the equipment failure effectively by taking measures in advance.As a dynamic non-destructive testing method, AE testing technology of cold storage pressure vessel has high reliability and good integrity. It maximizes the use of device resource on the basis of ensuring the safe operation, improves the detection efficiency, and saves a lot of cost for enterprises. It has good social and environmental benefits with a broad and bright application prospect.