Chlorine Dispersion Research Articles

Risk analysis of the sodium hypochlorite production process: Focus on the chlorine line

Mainly in the first part of COVID-19 pandemics, sodium hypochlorite was used as disinfectant, surprisingly also to spray over people. Several hazards may be associated to the production of this compound, such as chlorine gas toxicity and explosive hazards, due to the presence of hydrogen and chlorine, and corrosive hazards. Thus, loss prevention strategies must be ad-hoc developed to mitigate the risks. In the present work, the risk assessment of the first block of the process was performed, focusing the attention on chlorine risks. To this end, HAZOP analysis was first performed to identify the most critical top event, noticing the major issues in the quality of the final product and in the release of chlorine from pipes. Then, the fault tree analysis was built to calculate its failure rate. CFD simulations were used instead of empirical model to assess with a rigorous approach the chlorine dispersion, taking into account all the boundary conditions. In particular, by setting a hazardous chlorine concentration of 180 ppm corresponding to 50% fatalities for chlorine exposition for an exposure of 60 min, results without aspiration demonstrate the possibility for the cloud to impact workers at ground level also very far from the source point, while the chlorine cloud is moved upwards with a maximum length of 6.5 m when an aspiration is used, although the air ventilation speed is kept low.

Dynamic characteristics of chlorine dispersion process and quantitative risk assessment of pollution hazard.

The aim of this study was to analyze dispersion behavior characteristics and pollution hazard risk after a release of liquid chlorine. A full-scale model of liquid chlorine tanks in an area with a radius range of 3 km was established using FLACS (Flame Acceleration Simulator) code, and the chlorine dispersion characteristics of six leakage scenarios were calculated according to the POOL model, and the individual risk and social risk under different conditions as calculated quantitatively. The results show that leakage occurs in three stages: dynamic dispersion, gravity dispersion, and atmospheric dispersion. Variations in dispersion processes were expressed as "outward expansion" and "inward contraction." At the same time, dispersion was accompanied by the phenomenon of "cloud separation." In the six leakage scenarios, the total distance of chlorine dispersion was 84-1000 m for a concentration of 225 ppm, and 27.5-401.3 m for a concentration of 900 ppm. The corresponding times (duration) to the farthest dispersion distance were 235-1345 s and 185-680 s, respectively. Chlorine concentration and dispersion distance are consistent in trend; however, the farthest dispersion distance shows a "delay effect" in time. At 225 ppm and 900 ppm, the delay time was 125-1145 s and 75-480 s indifferent leakage scenarios. The installation of a safety instrument system (SIS) can effectively reduce the risk of chlorine dispersion.

Influence of monsoon seasons on accidental chlorine leak and dispersion around Gebeng industrial area

This paper presents the prediction of hypothetical chlorine leak dispersion around Gebeng industrial area using Areal Location of Hazardous Atmosphere (ALOHA) software. The effect of the different wind speed and direction to chlorine dispersion in the meteorological microscale area was investigated. The wind speed ranging from 1.32 to 10.7 m/s obtained from a local weather station was considered. Heavy gas dispersion model was used to determine the concentration of chlorine plume within the area of concern. The leakage rate was set to correspond to a leakage from the chlorine tank at 792 kg/h. The result showed that the residential areas R1 and R2 are affected by the plume dispersed by southwest and northern winds, respectively. A greater hazard area was found when the wind speed is below 2.3 m/s. Meanwhile, the hazard zone reduced to nearly half when the wind speed is above 5.4 m/s. The appropriate evacuation routes were developed to reduce risk of exposure to toxic gas. Finding from this work is useful to understand the risk of noxious gas dispersion around Gebeng industrial area.

Analysis of a series of urban-scale chlorine dispersion experiments and implications on indoor health consequences

In the United States, industrial compounds are routinely transported by rail in pressurized vessels, often near urban areas. A rupture of a vessel, for example due to a derailment, can result in the rapid release of a liquid-aerosol-gas mixture. The health consequences of such a release, especially close to population centers, are not well understood. To address this question, a series of controlled experimental releases of pressurized chlorine (Cl2) was conducted at the Dugway Proving Ground (Dugway, Utah). Each trial consisted of the sudden breach of a tank containing at least 4,500 kg (kg) of pressurized liquid Cl2. In this paper, we report on measured Cl2 concentrations in three test structures downwind of the release. Based on these data, we estimate the indoor-outdoor exchange, transport through a multi-room structure, and the first-order loss rate due to reaction or sorption. This loss rate is particularly important for consequence assessment. For example, in a mobile office with a ventilation rate of about three air changes per hour, the reaction loss rate was approximately 2.5 h−1. This accounts for a nearly 20 percent reduction in toxic load to indoor occupants. Finally, the paper discusses the modeling and analysis of a typical urban hazard assessment.

Modeling the Chlorine Gas Dispersion in the Water Treatment Plant

An issue rose for industrial safety and successful address of crisis involves quick and pragmatic decision that would reduce losses and accidents. This will become practical when in addition to studying of past accidents the industrial executives create the necessary readiness to face risks through precise estimation of the consequences of eventual accidents. The present research concerns modeling the consequences of chlorine gas dispersion in the wastewater installations. The transfer of knowledge and information in this study were gained from modeling the dispersion of chlorine in the water treatment plants, useful for managers and executives. Detection and specifying the risks of chlorine for the public and especially the staff and those residing near the water treatment plant, would result in the appropriate action against this lethal substance, which is the subject of this study. Identification of risks related to foreign agents and their negative impacts on water treatment plants containing chlorine tanks is among the objectives of this study. The modeling and accurate specification of the scope and level of danger created following the dispersion of chlorine was done using the PHAST software, which allowed a clear identification of danger zones created by the dispersion of Chlorine. This text reports the radius of areas affected by chlorine dispersion as well as the results of different conditions after running the model for variable physical and process conditions, and given their availability, these results can be compared with each other.

Assessment of chlorine leak dispersion around Gebeng industrial area and potential evacuation route

This paper evaluates the effect of topographical and wind condition on the dispersion of chlorine leaks around Gebeng industrial area Malaysia using a computational fluid dynamics (CFD). The actual data on wind speed and direction was obtained from a local weather station. The turbulent flow was resolved using a scale-adaptive simulation (SAS) model, whereas the chlorine dispersion was modelled using the species transport equation and compared with the area location of hazardous atmosphere (ALOHA) model. The simulation was compared with the laser doppler anemometry (LDA) measurement on a scaled-down terrain model. A good agreement between the CFD prediction and LDA measurement was obtained. The finding showed that the terrain surface, wind direction and wind speed have a combined effect on the dispersion of chlorine. Residential areas R1 and R2 are affected by the chlorine leak during June to September and November to January, respectively. The plume reached the residential area rapidly under the wind speed above 7.2 m/s but the hazard zone is reduced about 50%. CFD prediction agrees with that of ALOHA in the case of flat terrain, whereas CFD provide a better prediction for the case involving complex terrain. The finding in this work may provide a useful guide to estimate the risk zone from a hypothetical chlorine leak which can be used to plan the safety evacuation procedure.

The dependence of chlorine decay and DBP formation kinetics on pipe flow properties in drinking water distribution

Simultaneous chlorine decay and disinfection byproduct (DBP) formation have been discussed extensively because of their regulatory and operational significance. This study further examines chemical reaction variability in the water quality changes under various hydrodynamic conditions in drinking water distribution. The variations of kinetic constant for overall chlorine decay (kE) and trihalomethane (THM) formation were determined under stagnant to turbulent flows using three devices of different wall demand and two types of natural organic matters (NOM) in water. The results from the comparative experiments and modeling analyses show the relative importance of wall demand (kw), DBP-forming chlorine decay (kD), and other bulk demand (kb') for pipe flows of Re = 0–52500. It is found that chlorine reactivity of virgin NOM is the overriding factor. Secondly, for tap water NOM of lower reactivity, pipe flow properties (Re or u) can significantly affect kE, the THM yield (T), formation potential (Y), and the time to reach the maximum THM concentration (tmax) through their influence on kinetic ratio kD(kb'+kw). These observations, corroborating with turbidity variations during experiments, cannot be explained alone by chlorine dispersion to and from the pipe wall. Mass exchanges through deposition and scale detachment, most likely being flow-dependent, may have contributed to the overall chlorine decay and DBP formation rates. Thus for the simultaneous occurrence of chlorine decay and DBP formation, model considerations of NOM reactivity, pipe types (wall demand), flow hydraulics, and their interactions are essential.

Downwind chlorine hazard estimates for the 2015-2016 Jack Rabbit II campaign

We present estimates of the downwind inhalation health hazard to humans arising from large-scale releases of pressurised liquefied chlorine based on data from the Jack Rabbit II chlorine dispersion field campaign. For chlorine releases in the range of 7 to 9 metric tons, lethal, severe, and mild health effects are expected up to 1 km, between 2 and 5 km, and more than 11 km downwind from the release, respectively. The AEGL-3, AEGL-2, and AEGL-1 acute inhalation hazard thresholds are expected to be exceeded between 2 and 5 km, up to 11 km, and beyond 11 km downwind from the release, respectively. Since these hazard distance estimates are based on chlorine concentrations that were directly measured (i.e., not modelled), their accuracy depends only on the quality of the health effects models, and not on the quality of any atmospheric transport and dispersion model or container release (chemical source term) model.

Computational modeling of gas mixture dispersion in a dynamic setup – 2d and 3d numerical approach

The aim of the study was to prepare a mathematical model of gas mixture dispersion with the use of Computational Fluid Dynamic (CFD) technique. Three dimensional chlorine dispersion in a dynamic setup with the use of Volume of Fluid model (VOD) model was applied. The area of investigation was equal to 0.1km2and the high of the mathematical domain was equal to 50m. Atmosphere was considered in two stages: as one direction of wind flow and no wind. Comparison of constant and dynamic conditions indicated high impact of wind. For the windless case circular profile of chlorine concentration around dispersion source was observed. While, for the wind application the main chlorine concentration moved ahead the source of dispersion.

Improving chlorine disinfection of wastewater by ultrasound application

The presence of soluble organic material as well as high concentrations of suspended matter in waters and wastewaters affect the efficiency when chlorine is used as disinfection agent. The objective of our work is to explore to which extend ultrasonic treatment can facilitate wastewater disinfection with chlorine in order to bring down doses of ecologically questionable chlorine and to shorten contact times. Sewage treatment plant (STP) effluents with different concentrations of suspended solids are exposed to sonication in combination with chlorine dosage. We observed that enhancement of chlorine efficiency is better for samples with higher concentrations of suspended matter. For samples with a TSS concentration of 50 mg/L chlorination efficiency (2 mg/L) can be doubled from 0.7 to 1.4 log when treated simultaneously with 20 kHz ultrasound for 5 minutes, i.e. levels of indicator organisms can be brought down to numbers that conventionally require far higher doses of chemical disinfectants. As subsequent sonication/chlorination does not have the same significant effect as simultaneous application of these two means, ultrasound does not just have a declumping effect; it seems that ultrasound application provokes a better chlorine dispersion in the aqueous media which improves the fast chemical and bactericidal reaction.

Small scale field experiments of chlorine dispersion

Abstract The objective of this paper is to increase current knowledge on the dispersion of a small plume of chlorine using medium scale field experiments. An experiment using a peacock tail spray was undertaken to study the mitigation of the chlorine cloud.