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CG-4 H2S adsorbent, an iron oxide based solid, has high sulfur capacity (20-25% w/w) and thus finds favor in users eyes in North America. This product, imported from CLEAN Catalysis and Purification Technologies Development Company in Shanxi Province, China, is now being used in gas processing companies in Alberta, Canada and Texas, USA. However, due to the elemental sulfur deposition on the adsorbent, the recovered sulfur capacity by regeneration is only about 1/3 as that of fresh adsorbent. This limits the adsorbent use to be once, which results in higher operating cost due to the frequent changeover and cost for landfills. The problem of sulfur deposition is also the limitation to the utilization and regeneration of other desulfurization adsorbent or catalyst. <p>This study developed a process to recover the sulfur capacity of CG-4 adsorbent by ammonia leaching to remove elemental sulfur. The leaching was conducted in a stainless steel cylindrical reactor at room temperature and a pressure higher than the vapor pressure of liquid ammonia. The leaching process does not deleteriously change the physical strength, but improve the properties of surface area, pore volume and pore size distribution. The new regeneration process is able to recover over 90% sulfur capacity in the first adsorption-regeneration cycle. The sulfur capacity recovery declined when CG-4 had been leached for more than one time. Nonetheless, even after the third time leaching, the sulfur capacity was recovered by 60%. The conditions of leaching process were optimized in a laboratory-scale experiment. <p>Additionally, the elemental sulfur collected from leaching process has 91.5% w/w purity and can likely be used as an additive to asphalt or used as a soil amendment for agricultural applications. The separation of solid wash-offs and liquid ammonia was simply fulfilled by depressurizing the leaching vessel and vaporizing the ammonia. CG-4 adsorbent is verified capable of at least three times reuses, which results in 60% reduction in disposal amount per unit H2S being treated. This not only reduces the cost in disposal to landfills but also the cost in CG-4 adsorbent and brings the revenue from the recovered elemental sulfur. The vapor ammonia is recommended to be recycled and reused by compressing it back to liquid.

CG-4 H2S adsorbent, an iron oxide based solid, has high sulfur capacity (20-25% w/w) and thus finds favor in users eyes in North America. This product, imported from CLEAN Catalysis and Purification Technologies Development Company in Shanxi Province, China, is now being used in gas processing companies in Alberta, Canada and Texas, USA. However, due to the elemental sulfur deposition on the adsorbent, the recovered sulfur capacity by regeneration is only about 1/3 as that of fresh adsorbent. This limits the adsorbent use to be once, which results in higher operating cost due to the frequent changeover and cost for landfills. The problem of sulfur deposition is also the limitation to the utilization and regeneration of other desulfurization adsorbent or catalyst. <p>This study developed a process to recover the sulfur capacity of CG-4 adsorbent by ammonia leaching to remove elemental sulfur. The leaching was conducted in a stainless steel cylindrical reactor at room temperature and a pressure higher than the vapor pressure of liquid ammonia. The leaching process does not deleteriously change the physical strength, but improve the properties of surface area, pore volume and pore size distribution. The new regeneration process is able to recover over 90% sulfur capacity in the first adsorption-regeneration cycle. The sulfur capacity recovery declined when CG-4 had been leached for more than one time. Nonetheless, even after the third time leaching, the sulfur capacity was recovered by 60%. The conditions of leaching process were optimized in a laboratory-scale experiment. <p>Additionally, the elemental sulfur collected from leaching process has 91.5% w/w purity and can likely be used as an additive to asphalt or used as a soil amendment for agricultural applications. The separation of solid wash-offs and liquid ammonia was simply fulfilled by depressurizing the leaching vessel and vaporizing the ammonia. CG-4 adsorbent is verified capable of at least three times reuses, which results in 60% reduction in disposal amount per unit H2S being treated. This not only reduces the cost in disposal to landfills but also the cost in CG-4 adsorbent and brings the revenue from the recovered elemental sulfur. The vapor ammonia is recommended to be recycled and reused by compressing it back to liquid.

Ammonia refrigeration systems are widely used in industry. Demand of these systems is expected to increase due to the advantages of ammonia as refrigerant and because ammonia is considered a green refrigerant. Therefore, it is important to evaluate the risks in existing and future ammonia refrigeration systems to ensure their safety. LOPA (Layer of Protection Analysis) is one of the best ways to estimate the risk. It provides quantified risk results with less effort and time than other methods. LOPA analyses one cause-consequence scenario per time. It requires failure data and PFD (Probability of Failure on Demand) of the independent protection layers available to prevent the scenario. Complete application of LOPA requires the estimation of the severity of the consequences and the mitigated frequency of the initiating event for risk calculations. Especially in existing ammonia refrigeration systems, information to develop LOPA is sometimes scarce and uncertain. In these cases, the analysis relies on expert opinion to determine the values of the variables required for risk estimation. Fuzzy Logic has demonstrated to be useful in this situation allowing the construction of expert systems. Based on fuzzy logic, the LOPA method was adapted to represent the knowledge available in standards and good industry practices for ammonia refrigeration. Fuzzy inference systems were developed for severity and risk calculation. Severity fuzzy inference system uses the number of life threatening injuries or deaths, number of injuries and type of medical attention required to calculate the severity risk index. Frequency of the mitigated scenario is calculated using generic data for the initiating event frequency and PFD of the independent protection layers. Finally, the risk fuzzy inference system uses the frequency and severity values obtained to determine the risk of the scenario. The methodology was applied to four scenarios. Risk indexes were calculated and compared with the traditional approach and risk decisions were made. In conclusion, the fuzzy logic LOPA method provides good approximations of the risk for ammonia refrigeration systems. The technique can be useful for risk assessment of existing ammonia refrigeration systems.

The reuse of litter in broiler production can lead to litter pathogen buildup and high levels of ammonia in broiler housing, thus resulting in poor broiler performance. This study evaluated the effects of two microbial litter amendments on litter characteristics, ammonia production and broiler performance. Experiment one, consisting of three trials, utilized eight pens approximately 3 x 3.2 m (10 x 10.5 ft) to rear broilers to 49 d of age. Experiment two, consisting of one trial, utilized twelve 1.8 x 3.7 m (6 x 12 ft) pens to rear broilers to 42 d of age. Used litter was obtained from separate commercial broiler farms for each experiment and placed into the pens at an average depth of 11 cm (4.3 in). Feed consumption and mortality were recorded for each pen for each trial. Ammonia production was measured by placing an enclosed chamber over the litter and measuring the headspace ammonia concentration after 20 minutes for both experiments. Experiment one also utilized a two minute ammonia flux technique. Ammonia measurements were taken at the time of litter treatment, at chick placement, and once per week for the remainder of the grow-out. Litter samples were collected at the same time and location as ammonia measurements. At the end of all trials, caked litter was removed from each pen, weighed and sampled. Litter and cake samples were analyzed for total aerobic and anaerobic microbial counts in experiment 1. Experiment 2 analyzed aerobic litter samples only. Paw scores were also recorded at the end of each trial for all birds using a 3-point scale. Data was subjected to ANOVA using the GLM procedure with means deemed significantly different at P < 0.05. Statistical differences were seen sparingly in different parameters in both experiments; however these differences were random in their distribution and showed no trend. Final results indicated that the microbial litter amendments had no effect on broiler performance, litter characteristics or ammonia production.

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