COMPASS
The compass of the work is to carry out the Quantitative Risk Assessment study for nitric acid plant of Deepak Chem Tech Limited.
PURPOSE OF THE STUDY
This study’s primary goal is to methodically and quantitatively assess the possible hazards connected to a given circumstance, course of action, or choice.
The following are QRA’s objectives:
- Involves assessing and quantifying pitfalls in colourful scripts through the use of numerical data and analysis.
- Facilitates educated decision-making by furnishing options.
- Offer stakeholders a clear and unprejudiced means of entering information about risks.
- Gives risks numerical values so that they can be compared and prioritized.
- Quantification of societal risk and calculation of potential loss of life.
RISK ASSESSMENT PROCEDURE
A methodical approach to assessing the risks connected to industrial systems and processes is called Quantitative Risk Assessment, or QRA. The first step in the process is to determine which pertinent processes, units, and activities need to be examined. It entails creating hypothetical Loss of Containment (LoC) situations in which dangerous materials could break free from their containment. The ramifications, including repercussions and possible harm, are evaluated for every LoC situation. The failure probability and frequencies are then ascertained using probabilistic methods and historical data. After that, the risks are measured and displayed using metrics like society risk f-N curves and individual risk contours. In order to decide if these risks are acceptable and what risk-reduction strategies are required, these risks are finally assessed and examined.
- Establish contingency plans for loss of containment (LoCs).
- Analyse each LoC’s repercussions, including damages and effects.
- Ascertain the likelihoods and frequencies of failure for each LOC.
- Determine and display risk measures, such as societal risk f-N curves, individual risk contours, and so on.
- Assess and examine the risk.
IDENTIFICATION OF HAZARD
Depending on taking into account variables including the fluids’ physical and chemical characteristics, equipment configuration, maintenance and operation guidelines, process conditions, external risks like outside influence, and harsh environmental circumstances,
CONSEQUENCE ANALYSIS
The next stage after identifying the scenarios is to evaluate the possible outcomes of each one. There are several kinds of effects that can have consequences, including:
- Employee safety involves evaluating the risk of harm or death to employees.
- Assessing the degree of harm to machinery, buildings, or the environment is known as asset damage.
- Examining the consequences for soil, water, air, and ecosystems is known as environmental impact.
- Impact on business: evaluating the monetary and operational ramifications, such as production loss, downtime, and reputational harm.
RISK ANALYSIS
Estimating the frequency or possibility of each possible scenario happening comes next after they have been recognized as potential scenarios. In order to determine the likelihood of occurrences occurring within a specified time frame, this entails taking into account several aspects, including expert judgement, probabilistic modelling, historical data, and analysis of pertinent data.
To calculate the overall risk, a risk estimate combines the likelihood and effects of each event. Techniques like risk matrices, risk curves, and probabilistic risk assessment (PRA) procedures are frequently used for this. As a consequence, there is a numerical representation of risk that is frequently described as estimated annual loss (EAL), individual risk (IR), or society risk (SR).
After risks are measured, they are compared to predefined risk or tolerance standards to see if they can be tolerated or if additional mitigation is needed. This entails contrasting the determined risk levels with established risk acceptability standards, legal mandates, and social norms.
RISK COMMUNICATION
The public, regulators, and decision-makers are among the stakeholders to whom the risk analysis’s findings are finally conveyed. To make sure that the implications of the analysis are fully understood and that the necessary risk management measures are put in place, clear and open communication is crucial.
PROCESS OVERVIEW
Liquid ammonia from storage tanks is processed by the Nitric Acid Plant (DCTL) by feeding it into an ammonia feed vessel and pumping it to the necessary pressure. Using cold and cooling water, ammonia is vaporized in two phases. Any leftover ammonia and water mixture is then treated in an ammonia stripper. After being superheated and filtered, the ammonia gas is combined with air. In the air mixer, ammonia and compressed air are mixed together by a steam turbine and tail gas. Oxidation on catalyst gauzes produces high-pressure steam. After cooling the process gas, the water that was created during combustion condenses into weak nitric acid, which is subsequently concentrated using secondary air in an absorption tower. After more heating and processing, the resultant nitric acid is stored, along with tail gas.
OVERVIEW OF THIS CASE STUDY:
The nitric acid plant had been divided into nine isolatable sections. Using DNV PHAST, the major plausible end events of the following scenarios have been identified: jet fire, pool fire, flash fire, overpressure explosion, and toxic dispersion. Their impacts and consequences have been calculated for each scenario. DNV SAFETI was used for the risk analysis, yielding risk results in the form of F-N curves and LSIR contours. The analysis concludes that the societal risk for the entire population under consideration is within the ALARP zone.