Aeration in Wastewater Treatment

The Role of Aeration in Wastewater Treatment

Industrial wastewater treatment is the process used to treat wastewater that is produced as a by-product of industrial or commercial activities. After treatment, the treated industrial wastewater may be reused or released to surface water in the environment.
What is Aeration?
Wastewater aeration is the process of adding air into wastewater to allow aerobic bio-degradation of the pollutant components. It is an integral part of most biological wastewater treatment systems. Chemical treatments make use of chemicals to react and stabilize the contaminants in the wastewater stream whereas biological treatments use microorganisms that naturally occur in wastewater to degrade contaminants.
When is Aeration Used?
The activated sludge process is the most common option under the secondary treatment used in municipal and industrial wastewater treatment. Aeration is part of the secondary treatment process. Aeration in an activated sludge process is based on pumping air into a tank, which promotes the microbial growth in the wastewater. The microbes feed on the organic material, forming flocs that can easily settle out. After settling in a separate settling tank, bacteria forming the “activated sludge” flocs are continually circulated back to the aeration basin to increase the rate of decomposition.
How does Aeration Work?
The bacteria in the water require oxygen for the biodegradation process to occur. Aeration provides oxygen to bacteria for treating and stabilizing the wastewater. The bacteria in the wastewater break down the organic matter containing carbon to form carbon dioxide and water utilizing the supplied oxygen. Without sufficient oxygen, bacteria are unable to biodegrade the incoming organic matter in a reasonable time.
In the absence of dissolved oxygen, degradation must occur under septic conditions that are slow, odorous, and yield incomplete conversions of pollutants. Under septic conditions, some of the biological process converts hydrogen and sulphur to form hydrogen sulphide and transform carbon into methane. Other carbon will be converted to organic acids that create low pH conditions in the basin and make the water more difficult to treat and promote odour formation. Biodegradation of organic matter in the absence of oxygen is a very slow biological process.
There are two common types of water aeration: subsurface and surface.
What is Subsurface Aeration?
Subsurface is the most common type of aeration. Large wastewater treatment plants in urban areas commonly use it. Subsurface aeration uses porous devices that are placed below the liquid’s surface. These diffusers or submersible aerators are lowered into the water or fluid and compressed air is released, creating bubbles. This method delivers the most oxygen available into the water and ensures the water and oxygen are thoroughly mixed.
What is Surface Aeration?
Surface aerators push water from under the water’s surface up into the air, and then the droplets fall back into the water, mixing in oxygen. The jets of water break the surface with varying degrees of force.
Why is Aeration Important for Wastewater Treatment?
Aeration is the most critical component of a treatment system using the activated sludge process. When properly implemented, aeration also eliminates seasonal problems such as algae growth or stratification. When exposed to heat and sun, still bodies of water such as reservoirs become stratified. This causes problems, such as foul odors, weed and algae growth, and fish kills. By improving the nutrient-oxygen balance, aeration helps improve water quality. A well-designed aeration system has a direct impact on the level of wastewater treatment it achieves. An evenly distributed oxygen supply in an aeration system is the key to rapid, economically viable, and effective wastewater treatment.

Energy Audit

Energy Audit – An Overview

Energy Audit is the first step in Energy Conservation and Energy Efficiency Projects for Industrial Plants. Energy Audit is a periodic exercise undertaken by a plant to assess its energy consumption and identify opportunities for Energy Conservation and Energy Efficiency. It also helps plant personnel in modernizing the plant with new technological solutions. It benefits plants cut down production costs.

In India, Energy Audit is quite popular in an Industrial or Commercial Facility. Many companies have realized the potential of energy saving in their plant. However one must realize that Energy Audit is only the first step in the direction of energy efficiency and energy conservation. The recommendations made as part of the energy audit have to be implemented to achieve the energy saving targets.

The energy saving recommendations doesn’t require much investment. In some high cases, the investment may be higher. The plant then takes up the investments in a phase-wise manner, which result in delayed energy saving for the plant. In fact the plant may never take some of the recommendations up. This renders the entire energy audit exercise futile.

Energy Audit works for every single Plant or Commercial Facility, as there is always scope for Energy Optimization through Energy Conservation & Energy Efficiency. Every plant goes through some changes over a period of time. Moreover an external Energy Audit team works across departments and brings in rich experience gained from Energy Audit of several plants. This not only results in gaining fresh perspective of Energy saving possibility by an external team also results in bench-marking based on similar parameters.

Energy Audit gives a positive orientation to Preventive Maintenance, Safety and Quality Control programs thereby improving the overall efficiency and output of existing system.

Nearly all the Industrial Units and Commercial Complexes have a potential to save 10-15% on Energy Bills and additional savings in Thermal Energy.

The evident reason why a plant goes for an Energy Audit is the saving of energy. This saving translates into monetary saving and hence can have a direct impact on profitability of a Company. It is also a step towards sustainability.

However, Energy Audits should look at a more comprehensive approach than just reducing cost. Industries should focus more on reducing their carbon footprint as necessitated by Governing Environmental Laws. Energy Audits must go beyond the conventional approach and adopt newer technologies for Green Power Generation.

With increased environmental awareness the pressure on Industries is mounting to reduce their Carbon footprint by adopting Greener Methods wherever possible. In such as scenario Energy Audit would play a crucial role in offering Industries a comprehensive approach towards a Greener Plant.

There is no specific answer as to how much energy a plant could save post an Energy Audit. An estimate could certainly be provided and in all cases Energy Audit could prove to be useful and economically viable. This is especially true in the present day scenario when Energy costs are ever rising and are expected to rise further.

Each Industrial Plant must carry out Energy Audits for reducing their energy usage by adopting energy conservation and energy efficiency measures.

Temperature Mapping for Pharmaceutical Industry

Temperature mapping is important for verifying the efficacy of temperature controlled storage systems such as cool rooms, fridges and warehouses. It is vital for businesses that work with temperature sensitive products such as pharmaceuticals or warehouses.

The process of mapping outlines the differences and changes in temperature that occur within a single temperature controlled system. This is due to influences like opening doors, proximity to cooling fans, personnel movement, and the quantity of products being stored at any given time. Temperature mapping locates the points of greatest temperature fluctuation and difference then analyses the causes of these. Conditions are created to verify that a system maintains the correct temperature in all situations when influenced by external factors such as weather and internal factors such as airflow restrictions and the operation of the Heating, Ventilation and Air Conditioning systems. The effects in difference of temperature are calculated to ensure the systems meet industry standards.

The temperature of different spaces within cooling rooms, industrial fridges and other controlled temperature environments can vary by up to 10°C. Generally, the central space within a chamber maintains constant temperature, however the corners and areas surrounding the fans will fluctuate. External seasonal weather must also be taken into account especially for warehouses.

Temperature mapping is important for businesses and organisations dealing with temperature sensitive products, like biochemical products such as medications and vaccines. Verifying that the refrigeration systems maintain an acceptable temperature level for each specific product at all times is what temperature mapping is all about, and this is supported using ongoing monitoring systems.

Once mapping has established where temperature variation points lie within the control system then monitoring can be installed. It is important to re check any back up systems to be sure that the chambers will work in other circumstances.

Different mapping equipment gives different results. It is important to ensure that the equipment being used has sufficient accuracy ratings to give reliable data. For example, better equipment will provide readings that are accurate within plus or minus 0.3°C, whereas budget equipment may only have accuracy ratings of within 2.0°C. For products that must be stored within a limited temperature range, this budget equipment cannot provide sufficiently specific temperature data.

Warehouses must have information regarding the building’s external conditions, as it is vital for effective mapping and monitoring. Warehouses are generally mapped for a full year to ensure all external conditions are accounted for in the data. This also helps to determine placement of monitoring systems due to influence of external conditions.

Temperature-controlled rooms such as fridges or cold rooms can be mapped once as their external environment is controlled. However, it is advisable to make sure that other external forces that could change their temperatures significantly do not heavily influence the HVAC systems of these buildings or environments. The mapping in warehouses should take into account the fluctuation in the warehouse temperatures and conduct the tests during its most extreme levels.

Load testing is important aspect of the temperature mapping process. It investigates how expected product levels interact with individual temperature controlled chambers. This testing takes into account whether the product will arrive in the required condition or if cooling is necessary. Testing should verify whether the chamber could cope with the maximum specified load arriving all at once to then be cooled. If it can operate properly in this situation, as well as operating effectively at full capacity, the chamber can be considered sufficiently load tested. It is also advisable to test the system’s performance by simulating failures, to ascertain whether the system could be used even while experiencing some equipment failures.

Once the mapping process has been completed, sensors should be installed to allow for continued surveillance of the areas that have been identified as being most influenced by temperature change. The stable areas should be monitored to help with any troubleshooting.

Monitoring systems should be planned and documented according to the scientific rationales shown by the temperature mapping procedure. This development strategy should then be reviewed and approved by the system owners as well as by an independent quality unit before being installed. Sensors should be placed around the products, around major potential temperature influences such as doors and cooling fans, and at different heights, especially in larger chambers.

Sensor equipment can be split into zones according to the area affected by similar influences. For example, in a square or rectangular chamber, the zones in corners away from doors will behave much the same as each other, as will the zones adjacent to doors or fans. If the monitoring devices are zoned, data can be compared to provide overall information on how the system usually functions.

To summarize, temperature mapping provides information on warmer and colder areas within temperature-controlled environments. They supply details on the overall operation of the systems. After temperature mapping a system, monitoring equipment can be installed to provide real-time feedback on system operations and its stability for product protection.

Fire Protection and Safety

Irrespective of its occupancy status, a fire can happen at any time and any place.
Fire has the potential to cause harm to its occupants and severe damage to property. Fire doesn’t only interrupt the whole process of manufacturing and production but also can cause major damage to the building and plant. Much work will be required in order to restore the entire production process.

Successful prevention of fire depends solely on the management who must survey the operation of the business and determine where the loss potential lies.

Inadequately maintained machines can be fire prone. The overheating of bearing, due to insufficient lubrication or the presence of dust, and heat caused by friction are common causes of fire. Frequent inspection and regular maintenance will reduce risk and make the general tidiness of premises easier to achieve.

Major fires start in storage area and warehouses than production areas. Poorly stored goods, even though they are not flammable, may help to spread fire and hinder fire fighters gaining access to the seat of the fire or reduce the effectiveness of sprinkler systems. Goods tidily stored with gangways may help to inhibit the spread of fire.

Fire Safety Audit

Fire has been rated as the 5th largest risk in the Indian Industry. Electrical defaults are the major causes of fire in India. Fire Safety Audit is found to be an effective tool for assessing fire Safety standards of an organization. In other words, it is aimed to assess the building for compliance with the National Building Code of India, relevant Indian Standards and the legislations enacted by State Governments and Local Bodies, on fire prevention, fire protection and life safety measures.

Though fire safety audit is found to be an effective tool for assessing fire safety standards of an occupancy, there is no clear cut provisions in any of the safety legislations in India, regarding the scope, objective, methodology and periodicity of a fire safety audit. Therefore, Fire Safety Audit should be made mandatory for all over India and the work should be entrusted to independent agencies, which have expertise in it. It is reasonable to have a fire safety audit in every year.

Clean agent suppression systems

Clean agent fire suppression systems make the use of inert gases and chemicals in extinguishing a fire.They are also known as gaseous fire suppression. In these systems, fire is suppressed manually or automatically by reducing heat rather than reducing oxygen, reducing fuel or preventing the chain reaction effect of fire. These systems work on a total flooding principle where the agent is applied in a three dimensional method within the enclosed space to deliver a concentrated, highly focused dose of fire suppression.

Clean agent systems are able to suppress fires without causing additional damage unlike water. This drastically reduces the costs incurred for repairs and replacements. This makes these systems the fire suppression systems of choice for commercial and public enterprises that want fast, effective fire suppression that minimizes damage to structures, electronics and other assets.

The agents are non-toxic, they cause no breathing problems for people and won’t obscure vision in an emergency situation.

Automatic Sprinkler Systems

Sprinkler systems are among the most useful tools in firefighting. Automatic sprinklers often are one of the most important fire protection options. The successful application of sprinklers is dependent upon careful design and installation of high quality components by capable engineers and contractors.

A sprinkler system must be installed in compliance with the building’s need. Wet pipe systems offer the greatest degree of reliability and are the most appropriate system type for most heritage fire risks. With the exception of spaces subject to freezing conditions, dry pipe systems do not offer advantages over wet pipe systems in heritage buildings. Preaction sprinkler systems are beneficial in areas of highest water sensitivity. Their success is dependent upon selection of proper suppression and detection components and management’s commitment to properly maintain systems. Water mist represents a very promising alternative to gaseous agent systems.

In India, although there are many rules and regulations, codes and standards related to fire safety they are seldom followed. Laxity in following fire safety measures causes major fires in many buildings. Proper attention must be paid to minimize fire loss because ultimately the community at large has to bear all the losses. There exists large number of different types of firefighting equipment and suppression systems to suit specific requirements. The use of smoke detectors, fire alarms, automatic sprinklers, water mist systems, clean agent suppression system should be encouraged. Above all the success of fire prevention and fire protection mainly depend upon the active co-operation from all personnel.

Process Engineering: An Overview

Process Engineering focuses on design processes, operation, process control, and process optimization. This discipline of engineering may focus on physical, chemical, or biological processes. Process engineering encompasses a large array of different industries and sectors. It has a wide range of applications, considerable potential value, and diverse methods.

Process engineering, as a discipline, can be traced back to the era of the 60s, when the term was first coined. However today, this engineering field has gained popularity across the globe. Numerous companies offer Process Engineering services. It is an active area for research, study and application. Process engineering has effected positive change on a global scale.

Since Process Engineering has a broad range of applications in various industries and sectors, the specifications in analysis varies with each sector. Process engineering have various sub-disciplines. Experts usually specialize in one or two of these sub- disciplines.

Process Design – Process design looks at the way the process in question has been designed and set up. It looks for ways to improve this design and structure, and may utilize hierarchical decomposition flow sheets, attempt superstructure optimization, or study plants with multi-product batches. Poor, inefficient design and structure elements can then be removed and substituted with design components that optimize the system better.

Process Operations – Process operations looks at the way the process in question is being executed. It may incorporate real-time optimization or fault diagnosis in an effort to improve operations efficiency. It may also study the operation’s schedule and examine multi-period planning, and other relevant data.

Process Control – Process control concentrates on the reliability of the process. It often employs tools such as controllability measures, robust control, model predictive control, statistical process control, and process monitoring to name just a few. By improving control over the process more consistent, dependable results are gained.

Supporting Tools – Supporting tools in process engineering focuses on the ancillary tools and systems that help support the primary process. These tools may include things such as equation based process simulation, AI or expert systems, sequential modular simulation, global optimization, large-scale nonlinear programming (NLP), optimization of differential algebraic equations (DAEs), and mixed-integer nonlinear programming (MINLP). These supporting tools enhance the overall productivity and quality of the process.

Process engineering is beneficial to industries in various ways. They include everything from debottlenecking certain key problem areas, improving production speed, eliminating unneeded steps from a process, making the process or system safer, and increasing the quality, consistency, and/or volume of output. By and large process engineering provides a way for industries to reduce their costs while increasing the overall efficiency of their processes.

Process engineering has an incredibly far-reaching impact and potentially holds promise for nearly any industrial or commercial business. It is also at the forefront of expanding what is possible in the sciences and technology sectors. Some particular industries served by process engineering include:

  • Chemical
  • Petrochemical
  • Refining
  • Food and food processing
  • Manufacturing
  • Mineral processing
  • Medical
  • Pharmaceutical
  • Bio-techs
  • Biomedical
  • Textiles
  • Transportation

Process engineering is a fast-paced, dynamic discipline that is continually evolving and pushing the envelope of what is possible. Panorama provides a thorough professional service that covers each step of process engineering. With roots in Chemical and Pharmaceutical industry, Panorama provides the best service.

HAZOP Analysis For Chemical Process Industries

“An ounce of prevention is worth a pound of cure.” As this old saying goes, safety should be an important element in every industry. Safety covers hazard identification, risk assessment and accident prevention. Safety should always come first and remain so despite of costs. Good design and forethought can often bring increased safety at less cost.

Operators of volatile plants must implement measures to ensure that their plants are operated and maintained in a safe manner. In the chemical process industry there are chances of a number of potential hazards. A hazard has the potential of causing an injury or damage to the plant as well as the working members. Raw material and intermediate toxicity and reactivity, energy release from chemical reactions, hightemperatures, high pressures, quantity of material used etc. are some of the hazards that can cause damage in a chemical industry plant.

HAZOP refers to Hazard and Operability studies. HAZOP is a systematic technique for examining potential hazards in the system. With HAZOP, the process is broken down into steps where every parameter is considered to see what could go wrong and where. This is the most common hazard analysis method for complex systems. It can be used to identify problems even during the early stages of project development, as well as identifying potential hazards in existing systems.

An important benefit of the HAZOP study is resulting knowledge that can be of great assistance in determining appropriate remedial measures. There are four steps to the HAZOP process:

  • Forming a HAZOP team:
    A multidisciplinary team is formed under the guidance of a leader. The team includes a variety of expertise such as operations, maintenance, instrumentation, engineering/process design, and other specialists as needed. The fundamental requirement is an understanding of the system and willingness to consider various parameters at each step of the process.
  • Identifying the elements of the system:
    The team must create a strategic plan for the entire process identifying individual steps and elements. This typically involves using a plant model as a guide for examining every section and component of the process. For each element, the team will identify the planned operating parameters of the system at that point: flow rate, pressure, temperature, vibration, and so on.
  • Considering possible variations in operating parameters:
    The team must be open to the idea of considering every possible variation to the parameters identified. Every deviation should be studied and potential hazards to be identified for each scenario.
  • Identifying any hazards or failure points:
    Once the team has identified potential hazards, they must estimate the impact of that failure. Existing systems should be evaluated and their ability to handle deviations in the future must be taken into consideration.

The overall aims to which any HAZOP Study should be addressed are:

  • To identify all deviations from the way the design intended to work, their causes and all the hazards and operability problems associated with these deviations.
  • To decide whether action is required to control the hazard or the operability problem, and if so, to identify the ways in which the problems can be solved.
  • To identify cases where a decision cannot be taken immediately and to decide on what information or action is required.
  • To ensure actions decided are followed through.

HAZOP studies can be implemented for new facilities or existing facilities or processes. When a HAZOP study is performed in the planning stage of a new process, completing the study means that all potential causes of failure will be identified.Whereas in existing facilities,instead of one assessment, the results will be released as each problem is identified and solutions are created.

Distillation column design & optimization

Distillation is a process that separates two or more components into an overhead distillate and bottoms. The bottom product is almost exclusively liquid, while the distillate may be liquid or a vapor or both.

The separation process requires three things.

  • First, a second phase must be formed so that both liquid and vapor phases are present and can contact each other on each stage within a separation column.
  • Secondly, the components have different volatilities so that they will partition between the two phases to different extent.
  • Lastly, the two phases can be separated by gravity or other mechanical means.

Distillation differs from absorption and stripping in that the second phase is created by thermal means

Distillation Flow:

3

 

The distillation column consists of:

  • 1 feed stream – which consistsof a mole percent of the light component, Zf.
  • 2 product streams – exiting the topwhich has a composition of Xd of the light component. The product stream leaving the bottomcontains a composition of Xb of the light component.

The column is broken in two sections:

  • The top section referred to as the rectifying section – which passes through a total condenser to condense all of the vapor distillate to liquid.
  • The bottom section isknown as the stripping section – which uses a partial reboiler to allow for the input of energy into our column.

Applications of Distillation:

  • Distillation is the least expensive means of separating mixtures of liquids.
  • If relative volatilities of components is less than 1.1, distillation becomes very expensive & extraction or reactive distillation should be considered.

What do successful distillation scale-up projects have in common? Project managers

Distillation column designmust understand and determine five key design elements for project success. Cost, chemical interactions and equipment needs change in a non-linear fashion as increased output is required.

STEPS INVOLVED IN COLUMN DESIGN:

  • SECTION 1:Graphical Determination of a Distillation Column Design

    Step 1. Determine Process Operation Variables
    Step 2. Determine the Minimum Reflux Ratio
    Step 3. Choose Actual Reflux Ratio
    Step 4. Determine the Minimum Number of Trays
    Step 5. Determine Actual Number of Trays
    Step 6. Principal Dimensions of the Column (Diameter/Height)

  • SECTION 2:Analytically determining the specifications for a distillation column

    Step 1. Determine Process Operation Variables
    Step 2. Determine the Minimum Reflux Ratio
    Step 3. Choose Theoretical Reflux Ratio
    Step 4. Determine Theoretical Number of Trays
    Step 5. Determine Actual Number of Trays
    Step 6. Principal Dimensions of the Column (Diameter/Height)

  • Section 3:Determining the Cost of Column and Components

    Step 1. Cost of Column
    Step 2. Cost of the Reboiler
    Step 3. Cost of Condenser
    Step 4. Total Cost of Column

Qualified engineers should consider the following critical steps for distillation column design:

  • Vapor-Liquid Equilibrium
  • Column Operating Objectives
  • Operating Pressure
  • R/Dmin and Nminand Feed stage estimation
  • Diameter and Height of the Column

Vapor-Liquid Equilibrium:

The starting point upon of all column design is on the basis of accurately determining the relative volatility of the key components to be separated. Using a mass and energy balance simulation program, the user must set up the basis of the simulation by selecting an appropriate fluid package and the components present in the feed.

Activity coefficients, estimated by the program or provided by the user, are used to relate non-ideal component interactions.

Column operating objectives:

Column operating objectives are defined by a primary product composition and an optimal recovery of the product from the waste, recycle or less important by-product stream. These specifications should be in terms of the heavy key impurity in the top stream and the light key impurity in the bottom stream.

Operating Pressure:

Once the top and bottom stream compositions are specified, the dew point of the top stream and the boiling point of the bottom stream may be determined at various pressures. An operating pressure should be selected that allows acceptable temperature differences between available utilities because the overhead vapor must be condensed and the bottom liquid reboiled.

If possible, atmospheric or pressure operation of the column is preferred to avoid requiring a vacuum system. Another consideration is also to use component heat sensitivity, which may require lower pressure operation to avoid fouling, product discoloration or decomposition. Often, the relative volatility is also improved at lower pressures.

R/Dmin&Nmin and Feed Stage Estimation:

Using the simulation program, shortcut procedures based upon total reflux operation allow the minimum reflux ratio (R/Dmin) and minimum number of ideal separation stages (Nmin) to be determined.

Using an actual reflux ratio of 1.2 times the minimum reflux ratio will allow an optimal number of stages to be estimated as well as an appropriate feed stage.

Diameter & Height of the column:

At this point, the distillation process is well defined, leaving the column diameter and height to be determined.

The column diameter is chosen to provide an acceptable superficial vapor velocity, or “Fs factor”. This is defined as vapor velocity (ft/sec) times square root of vapor density (lb/ft3), and liquid loading defined as volumetric flow rate (gal/min), divided by the cross sectional area of the column (ft2).

The column internals can be chosen as either trays or packing. Trayed columns must avoid flooding, weeping and down comer backup. Packed columns must avoid flooding, minimum surface wetting and mal-distribution. Table 1 provides a range of typical parameter values for various types of trays.

2

Looking for the best distillation column Design Company, distillation design & Optimization Company? Learn more about Panorama Consulting Engineers whose wide spectrum of services & a highly experienced technical team help you achieve your business objectives.

 

HAZOP

HAZOP Training

As discussed in our previous article – HAZOP study in India | HAZOP consulting services India | Process safety design; The HAZOP methodology is a well established technique used throughout industry for hazard identification and risk assessment. HAZOP was originally conceptualized in the 1960’s by ICI and training/guidance on its use was initially published in the 1970’s following the Flixborough disaster where an inadequately designed modification led to a large vapour cloud explosion killing 28 people.

We, at Panorama Consulting with our highly experienced team of HAZOP leaders have conducted thousands of HAZOP studies for many clients across many industrial sectors.

It is a universally recognized fact that for any Company to succeed it must take a rigorously proactive approach to risk management. Over the last few years Companies and a number of Countries legislators have been focusing on Process Safety as a method to reduce the risks posed by hazardous industries.

Process Hazard Analysis (PHA) is recognized as being a critical tool in the implementation of a successful risk management system.

HAZOP Training:
It is important that HAZOP training for top leaders in companies to cover following aspects of process safety management:

  • How to apply advanced risk assessment techniques
  • Mechanics of dispersion, fire, explosion and toxic releases
  • The concept of Quantified Risk Assessment “QRA”
  • Hazard and Operability (HAZOP) study methodology
  • HAZOP team leadership

HAZOP Training Techniques & HAZOP Objectives:

  • Understand the concepts of Risk Assessment and Risk Management
  • Understand the estimation and evaluation of risks – Qualitative, Semi-Quantitative and Quantified Risks
  • Techniques for Hazard Identification and Analysis – Check-Lists, Risk Profiling, HAZOP, FMEA and Task-Based Risk Assessment
  • Cause-Consequences Analysis – The Role of Fault Trees and Event Trees in Accident Prevention
  • Understand HAZOP studies their benefits and their short comings
  • Understand the requirements of a Team Leader or Facilitator, scribe and team members during HAZOP studies
  • Be able to facilitate a HAZOP study

Introduction to Risk Assessment

  • The concepts of hazards, risk and risk assessment
  • Methods for risk evaluation
  • Integrating risk assessment within Risk Management
  • Qualitative, Semi-Quantitative and Quantitative Risk Assessment methodologies

Risk Assessment Techniques: HAZOP

  • Introduction to hazards identification and analysis techniques
  • Techniques for hazard identification and analysis – HAZOP
  • Where and when to use HAZOP and the requirements for a successful HAZOP study
  • Team composition for HAZOP studies
  • Guide words and process variables used for HAZOP studies
  • Syndicate exercise – application of HAZOP to relevant processes

HAZOP Leadership Techniques

  • HAZOP team leader/facilitator requirements
  • HAZOP scribe requirements
  • Facilitating HAZOP studies, do’s and don’ts
  • Information required to allow successful HAZOP studies
  • Case study where each delegate has the opportunity to facilitate a HAZOP meeting
  • Review of commercial software used for HAZOP and Management of Change ‘MOC’

Consequence Analysis

  • Theory behind fire, explosion and toxic dispersion modeling utilized in Quantitative Risk Assessments
  • Types of fires and their effects on people and equipment
  • Types of explosions and their effects on people and equipment
  • Review of software available for consequence calculations

The Role of QRA

  • Introduction to Quantified Risk Assessment “QRA”
  • The role of Event Tree Analysis in scenario development
  • The role of Fault Tree Analysis for multi-causation analysis
  • Applications for ETA and FTA
  • Failure data for use in QRA’s
  • Societal Risk and Individual Risk
  • Review of software available for Quantitative Risk Assessments

The entire HAZOP process typically starts with the engineering drawing(s) at the BEGINNING of the process, the feeds being the raw materials. Often as many as 3 or 4 P&ID’s may be tabled at one session to enable the HAZOP team to identify where streams are coming from on one or more P&ID’s and where they are going to on the next one or two P&ID’s.
Companies should consider the following activities to help them make the most effective use of the products of a study:

  1. Prioritize the analysis results
  2. Document the hazard evaluation study
  3. Develop a management response to the study
  4. Resolve the actions resulting from the risk management decision making process in a timely manner.

Sometimes, it is difficult to rank the safety improvement suggestions from Hazard Analysis studies because the techniques generally do not provide a definitive, quantitative characteristic which is useful for ranking utility & purposes.

A frequent problem faced by the users of the HAZOP study results is that the HAZOP company – study team creates a long list of items for management to consider implementing in order to improve safety. In cases where this occurs, decision makers can rightfully wonder whether these results are of any practical use to them. They may ask, “Where do we start?” or “Which are the most important suggestions?”

To help management make these decisions, an efficient HAZOP consulting company & its team should give them as much information as possible. One way to do this is to rank the results of the HAZOP study. Ranking the safety improvement recommendations from the study allows management to prioritize the immediate efforts for resolution and follow-up.

The two most common criteria for ranking the safety improvement recommendations of HAZOP study are:

  • The analysts’ understanding of the risk posed
  • The analysts’ perception of the risk reduction

The first criterion ranks items based on their associated level of risk – it makes sense to resolve the most important problems first. The second criterion ranks proposed improvements by how much they will benefit the facility, not necessarily on how serious the problem is.

“Hazops are only as good as the knowledge and experience of the people present. If they do not know what goes on, the hazop cannot bring out the hazards.”

Looking for a HAZOP training company specialized in HAZOP analysis & HAZOP processes? If you’re looking for a HAZOP consulting company who can help you manage all your process safety services & risk management, get in touch with the HAZOP experts now & receive a free consultation.

HAZOP Procedure

A HAZOP procedure is an examination of an existing or planned operation (work) procedure to identify hazards and causes for operational problems, quality problems, and delays.

  • Can be applied to all sequences of operations
  • Focus on both human errors and failures of technical systems
  • Best suited for detailed assessments, but can also be used for coarse preliminary assessments
  • Flexible approach with respect to use of guide-words

HAZOP Procedure

Breakdown of operation (work) procedure to suitable steps

  • Define intention of each step
  • Establish boundary conditions else as conventional Process HAZOP
  • Apply guide-words to intention and boundary conditions for each step.

HAZOP Guidewords:

Guideword Meaning
No (not, none) None of the design intent is achieved
More (more of, higher) Quantitative increase in a parameter
Less (lessof, lower) Quantitative decrease in a parameter
As well as (more than) An additional activity occurs
Part of Only some of the design intention is achieved
Reverse Logical opposite of the design intention occurs
Other than (other) Complete substitution – another activity takes place

 

Alternative Guidewords:

Guideword Meaning
Unclear Procedure written in confusing and ambiguous fashion
Step in wrong place Procedure will lead to actions out of correct sequence or recovery failure
Wrong action Procedure action specified is incorrect
Incorrect information Information being checked prior to action is incorrectly specified
Step omitted Missing step, or steps too large, requiring too much of the operator
Step unsuccessful Step likely to be unsuccessful due to demands on operator
Interference effects from others Procedure-following performance likely to be affected by other personnel carrying out simultaneous tasks (usually when co-located)

 

Alternative Guidewords/Deviation:

Guideword Meaning
Time Too early, too late
Sequence Wrong sequence, omissions, wrong action
Procedure Not available, not applicable, not followed
Measurement Instrument failure, observation error
Organization Unclear responsibilities, not fitted for purpos
Communication Failed equipment, insufficient/incorrect information
Personnel Lack of competence, too few, too many
Position Wrong position, movement exceeding tolerences
Power Complete loss, partly lost
Weather Above limitations – causing delayed operation

 

HAZOP Reporting:

A typical HAZOP report consists of:

Summary

  1. Introduction
  2. System definition and delimitation
  3. Documents (on which the analysis is based)
  4. Methodology
  5. Team members
  6. HAZOP results

– Reporting principles

– Classification of recordings

– Main results

HAZOP Review:

Review meetings should be arranged to monitor completion of agreed actions that have been recorded. The review meeting should involve the whole HAZOP team. A summary of actions should be noted and classified as:

  • Action is complete
  • Action is in progress
  • Action is incomplete, awaiting further information

HAZOP Results:

What results to expect?

  • Improvement of system or operations
  • Reduced risk and better contingency
  • More efficient operations
  • Improvement of procedures
  • Logical order
  • Completeness
  • General awareness among involved parties
  • Team building

The purpose of this is to investigate how the system or plant deviates from the design intent and create risks for personnel and equipment and operability problems. HAZOP studies have been used with great success within chemical and the petroleum industry to obtain safer, more efficient and more reliable plants.

 

HAZOP Guidelines

HAZOP uses a brainstorming approach around a series of guide words designed to qualitatively identify possible deviations from normal operation and their possible impacts. Responsibilities are assigned to investigate possible solutions for each problem found.

Guidance is given on study procedure and prerequisites for an effective HAZOP, including team selection, information requirements and record keeping.

To be effective, a HAZOP study must be systematic, detailed and conducted by a balanced team with an experienced leadership.

Effective HAZOP strategy:

The effectiveness of a HAZOP will depend on:

  • the accuracy of information (including P&IDs) available to the team — information should be complete and up-to-date
  • the skills and insights of the team members
  • how well the team is able to use the systematic method as an aid to identifying deviations
  • the maintaining of a sense of proportion in assessing the seriousness of a hazard and the expenditure of resources in reducing its likelihood
  •  the competence of the chairperson in ensuring the study team rigorously follows sound procedures.

Key elements of a HAZOP are:

  • HAZOP team
  • full description of process
  • relevant guide words
  • conditions conducive to brainstorming
  • recording of meeting
  • follow up plan

HAZOP Worksheets:
The HAZOP work-sheets may be different depending on the scope of the study.
Generally the following entries (columns) are included:

  • Ref. no.
  • Guide-word
  • Deviation
  • Possible causes
  • Consequences
  • Safeguards
  • Actions required (or, recommendations)
  • Actions allocated to (follow-up responsibility)

HAZOP Pre-requisites:

As a basis for the HAZOP study the following information should be available:

  • Process flow diagrams
  • Piping and instrumentation diagrams (P&IDs)
  • Layout diagrams
  • Material safety data sheets
  • Provisional operating instructions
  • Heat and material balances
  • Equipment data sheets Start-up and emergency shut-down procedures

HAZOP Procedure:

Though there are no fixed approaches, following is a typical HAZOP procedure:

  1. Divide the system into sections (i.e., reactor, storage)
  2. Choose a study node (i.e., line, vessel, pump, operating instruction)
  3. Describe the design intent
  4. Select a process parameter
  5. Apply a guide-word
  6. Determine cause(s)
  7. Evaluate consequences/problems
  8. Recommend action: What? When? Who?
  9. Record information
  10. Repeat procedure (from step 2)

1

HAZOP Modes of Operation:

The following modes of plant operation should be considered for each node:

  • Normal operation
  • Reduced throughput operation
  • Routine start-up
  • Routine shutdown
  • Emergency shutdown
  • Commissioning
  • Special operating modes

A sample HAZOP process worksheet is illustrated in the below figure:

2

 

HAZOP Outline:

3

The key point here is that a HAZOP study must promote freethinking by the team members around each issue so that most possible problems can be identified. At the same time, the HAZOP company must impose enough discipline to keep the study moving along without wasting time on issues that are of no consequence.