AddiseoÒ

On September 15th, four members of our Nanjing-China team went to the Blue Star ADISSEO Company which was located in the chemical park of Liuhe District in Nanjing. We went there with the purpose of carrying out on-site research on harmful gas safety. Three workers of the company's security departments was quite hospitable during the whole reception. As we can see, the company's security measures were very strict, visitors were required to register and use ID cards for access cards, change into the labor security clothing so before visiting the plant, wear helmets and goggles, turn off the phone and all other electronic equipment.
Firstly, we went to the office area for interviews. The main business of Blue Star ADISSEO covers the development and production of methionine. the process involves a large quantity of hydrogen sulfide gas, so the use of leak gas detectors is of great important. The whole plant has a total of more than 100 fixed hydrogen sulfide gas detector, each of which can detect a radius of 5 meters. The maximum allowable concentration of hydrogen sulfide in the air is 10 mg / m3, and when the concentration reaches 3 ppm (about 4.56 mg / m3), the fixed instrument will issue an alarm, while it will issue a high alarm with the concentration of 6 ppm.

The company's security department conducts an overall inspection of the 300 gas detectors, which usually takes about two weeks. Every year, the company has to accept the national compulsory security checks. Once the company meet the qualifications, it will obtain the relevant certificates.
The detectors is made up of two parts, the main body with a display panel and the sensor probe. The former one is of 6-7 thousand dollars, while the latter is of 3-4 thousand dollars. As the hydrogen sulfide gas and the electrolyte inside the sensor has an irreversible chemical reaction, so it needs regular replacement. Its life can reach up to 3 years of life if no special circumstances occurs. But the frequence of replacement might be high where the leakage of hydrogen sulfide is more frequent. In addition, the intelligent property of the instrument ensures that it will automatically issue an alarm to remind the staff of replacing the probe when the sensor’s life is less than 10%.
In addition to the hydrogen sulfide detector around the device, whenever a leak or a suspected leakage occurs, the relevant technical staff need to wear a respirator breathing mask, hold a hand-held portable detector into the field to find the leak point. At the moment of interview, there were several portable detectors charigng in the office. One of the worker volunteered to demonstrate the operation for us. (See video)

Because the sensor is affected by temperature, air pressure, gas flow rate and other factors, so the sudden change in the weather (such as summer thunderstorms) may cause zero drift, resulting in false positives. At this point, the staff will decide whether to evacuate based on the scene. If the alarm is true, workers will quickly evacuate all the people to the upper area, and then involve the security sector personnel in. If the leakage is serious, the device will automatically cut off all the reaction, so that the root source of the generation of hydrogen sulfide is cut off. If the device is due to the aging of the tiny holes, the company will immediately invite the department of maintenance to conduct the  emergency plugging. And they will replace the whole pipe during the shutdown inpection period annually.
Under the guidance of the workers, we participated a simple safety training. We put on a full set of labor security clothing, wore reflective vests, helmets and goggles and visited the control room and the device around the fixed sensor. It was really hot under the sun, we were all sweaty wearing the clothes. Once thinking about the factory workers who wears the clothes every day, we were really touched by their dedication to their job.