(569h) Testing and Evaluation of Environmental Enclosures for Controlling Worker Exposure to Airborne Contaminants By Adsorption : Scale up Issue for Standardization

Considering the existing risk of exposition to high concentrations of ammonia in occupational health and safety [1], the French National Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS) has decided to study the vehicle cab air cleaning systems against this pollutant. The first step of this study was to improve the knowledge of the performances of the purifying carbon beds equipping the cabins of machines [2]. The experimental evaluation of eight commercially available carbon beds used in vehicle cab air cleaning is performed using ammonia at various relative humidities and various constant flows on an experimental bench (inlet NH₃ 1000 ppmv, 40 m³.h^-1 to 120 m³.h^-1, 30 to 70% HR, 23°C) presented in Figure 1. Figure 2 shows some typical results for commercial adsorption beds equipping the cabins.

The results show a big discrepancy between the different carbon beds tested on the partial breakthrough curves. These results pointed out the importance of the quality of the filter activated carbon packing. It also pointed out the health and safety possible issues of these full-scale tests and the necessity to propose a scale off solution for future certification with operative process and design considerations. To solve these attendees and have a better testing of the materials, a new experimental bench was developed with a smaller carbon bed. An experimental protocol was applied successfully to the eight commercially available purifying carbon beds to predict their effective performances and service life. To achieve this goal, the geometry of the complete system was taken into account. By applying identical residence time and face velocity to the standardized activated carbon bed [3], a good agreement was found between complete system evaluation and the reduced scale one. A preliminary verification of the representativeness of the standardized activated carbon bed is included in the protocol to ensure correct assessment of the complete system.

Reference

[1] DIRRENBERGER P., GROSJEAN J., MONTA N., NICOT T., KUNZ-IFFLI J., COULAIS C., KOEHLER V., PEDROS A., FACON B. - Occupational exposure to bioaerosols and ammonia in anaerobic digestion units. 17th International Waste Management and Landfill Symposium, Sardaigne (Italy), 30 sept - 04 oct 2019, 8 p. [2] MARSTEAU S., GALLAND B., MARCHAL M. - Ammonia removal using activated carbons: Vehicle cab air cleaning systems performances. 13th International Conference on the Fundamentals of Adsorption - FOA 2019, 26-31 may 2019, Cairns (Australia).

[3] ISO 10121-1 - Test method for assessing the performance of gas-phase air cleaning media and devices for general ventilation — Part 1: Gas-phase air cleaning media, 2014