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PROCESS APPLICATION AND MAINTENANCE MANAGEMENT

CHAPTER-1Process Applications using Instrumentation

PROCESS:Process is defined as series of operations that produce desired product/output.TYPES OF PROCESS

(1)Based on Period of operation:

1. Batch Process2. Continuous process

G.P.GANDHINAGAR, I.C. DEPARTMENT


Batch Process:

Batch production is a technique used in manufacturing, in which the object in question is created stage by stage over a series of workstations, and different batches of products are made.

Batch production occurs when many similar items are produced together. Each batch goes through one stage of the production process before moving onto next stage. Good examples include:

1. Cricket bat manufacture2. Baking / meal preparation3. Clothing production4. Furniture5. Electrical goods6. Clothing7. Newspapers8. Books9. Sample products

CHARACTERISTICS

1. A production line is set up.2. Each worker completes one task and passing down the production line to the next worker.3. The workers are semi skilled or unskilled.4. The workers must be able to switch from one part of the production line to another.

They are a flexible workforce;5. The production line can be changed quickly, so that different products can be made.6. Often individual parts of the product are bought from other companies and assemble on the

production line.7. The production lines runs for a certain amount of time and then the product is changed



The benefits and drawbacks of batch production include:

Advantages Disadvantages

Making in batches reduces unit costs Time lost switching between batches – machinery may need to be reset

Can still address specific customer needs (e.g. size, weight, style)

Need to keep stocks of raw materials. Cash also investment in work-in-progress

Use of specialist machinery & skills can increase output and productivity

Potentially de-motivating for staff

Continuous process:1. Continuous production is a flow production method used to manufacture,

produce, or process materials without interruption. Continuous production is called a continuous process or a continuous flow process because the materials, either dry bulk or fluids that are being processed are continuously in motion, undergoing chemical reactions or subject to mechanical or heat treatment.

2. Continuous usually means operating 24 hours per day, seven days per week with infrequent maintenance shutdowns, such as semi-annual or annual.

3. Some chemical plants can operate for more than one or two years without a shutdown. Blast furnaces can run eight to ten years without stopping.

Some common continuous processes are the following:

1. Oil refining2. Chemicals3. Synthetic fibers4. Fertilizers5. Pulp and paper6. Blast furnace (iron)7. Metal smelting



8. Power stations9. Natural gas processing10. Sanitary waste water treatment11. Continuous casting of steel12. Rotary kilns for calcininglime or cement13. Float glass

1. Production workers in continuous production commonly work in rotating shifts.

2. Processes are operated continuously for practical as well as economic reasons. Most of these industries are very capital intensive and the management is therefore very concerned about lost operating time.

3. Shutting down and starting up many continuous processes typically results in off quality product that must be reprocessed or disposed of. Many tanks, vessels and pipes cannot be left full of materials because of unwanted chemical reactions, settling of suspended materials or crystallization or hardening of materials. Also, cycling temperatures and pressures from starting up and shutting down certain processes (line kilns, blast furnaces, pressure vessels, etc.) may cause metal fatigue or other wear from pressure or thermal cycling.

4. In the more complex operations there are sequential shut down and start up procedures that must be carefully followed in order to protect personnel and equipment. Typically a start up or shut down will take several hours.

5. Continuous processes use process control to automate and control operational variables such as flow rates, tank levels, pressures, temperatures and machine speeds.

CHARACTERISTICS



1. An semi-automated production line is normally set up. Relying on computer control as well as human labour.

2. Workforce comprised of skilled and unskilled workers. Workers less flexible than those working in batch production as the product rarely changes.

3. Production line runs 24 hours a day, 365 days a year.4. A high level of investment in machinery, equipment.5. Limited training of staff as the product and equipment changes slowly.

Training only needed when up-dated equipment is introduced or new staff start.

6. Quality control at every stage of production. Sampling takes place at different stages of production

Semi-continuous processes:

Many processes such as assembly lines and light manufacturing that can be easily shut down and restarted are today considered semi-continuous. These can be operated for one or two shifts if necessary.

Continuous Processors are used in the following processes:

1. Compounding2. Mixing3. Kneading4. Shearing5. Crystallizing6. Encapsulating

The Continuous Processor has an unlimited material mixing capabilities but, it has proven its ability to mix:

1. Plastics2. Adhesives3. Pigments4. Composites5. Candy



6. Gum7. Paste8. Toners9. Peanut Butter10. Waste Products

Factor Continuous Batch

Cost of factory equipment High Low

Rate of production High Low

Shut-down times Rare Often

Workforce Few people neededMany people needed

Ease of automation Relatively easy Relatively difficult

Unit operation:1. In chemical engineering and related fields, a unit operation is a basic step

in a process. Unit operations involve bringing a physical change such as separation, crystallization, evaporation, filtration etc.

2. For example, in milk processing, homogenization, pasteurization, chilling, and packaging are each unit operations which are connected to create the overall process. A process may have many unit operations to obtain the desired product.

3. The Principles of Chemical Engineering and the variety of chemical industries have processes which follow the same physical laws. They



summed-up these similar processes into unit operations. Each unit operation follows the same physical laws and may be used in all chemical industries. The unit operations form the fundamental principles of chemical engineering.

4. The basic physical operations of chemical engineering in a chemical process plant, that is, distillation, fluid transport, heat and mass transfer, evaporation, extraction, drying, crystallization, filtration, mixing, size separation, crushing and grinding, and conveying.

Chemical engineering unit operations consist of five classes:

1. Fluid flow processes, including fluids transportation, filtration, solids fluidization

2. Heat transfer processes, including evaporation, condensation3. Mass transfer processes, including gas absorption, distillation, extraction,

adsorption, drying4. Thermodynamic processes, including gas liquefaction, refrigeration5. Mechanical processes, including solids transportation, crushing and

pulverization, screening and sieving

Chemical engineering unit operations also fall in the following categories:

1. Combination (mixing)2. Separation (distillation) and Reaction (chemical reaction)

1. Chemical engineering unit operations and chemical engineering unit processing form the main principles of all kinds of chemical industries and are the foundation of designs of chemical plants, factories, and equipment used.



2. Most unit operations are based mechanistically upon the fundamental transport processes of mass transfer, heat transfer, and fluid flow (momentum transfer).

3. Unit operations based on fluid mechanics include fluid transport (such as pumping), mixing/ agitation, filtration, clarification, thickening or sedimentation, classification, and centrifugation. Operations based on heat transfer include heat exchange, condensation, evaporation, furnaces or kilns, drying, cooling towers, and freezing or thawing.

4. Operations that are based on mass transfer include distillation, solvent extraction, leaching, absorption or desorption, adsorption, ion exchange, humidification or dehumidification, gaseous diffusion, crystallization, and thermal diffusion.

Examples of Unit Operations are listed in Table 1.

Table 1: List of some unit operations

Heat flow Mixing

Drying Absorption

Evaporation Adsorption

Distillation Condensation

Crystallization Vaporization

Leaching Separation

Extraction Sedimentation



Unit processes:

1. A Unit Process is a step in manufacturing in which chemical reaction takes place, e.g, the oxidation of paraxylene to terephthalic acid is a unit process, the hydrogenation of vegetable oil to ghee is a unit process.

2. In 1930 P.H. Grog- gins introduced Unit processes in order to classify and standardize chemical reactions.

3. Chemical process Unit process means that a chemical change occurs (i.e., nitration, halogenations , sulphonation).

4. Processes that involve making chemical changes to materials, as a result of chemical reaction taking place. For instance, in the combustion of coal, the entering and leaving materials differ from each other chemically: coal and air enter, and flue gases and residues leave the combustion chamber. Combustion is therefore a unit process. Unit processes are also referred to as chemical conversions.

Hybrid processes:

1. Hybrid processes are more than the sum of two unit operations.

1. Hybrid processes in separation operations are characterized by the combination of two unit operations.

2. Each unit operation itself is considered to be a separation process, but the combination generates special advantages.

3. In the case of combining rectification and membrane technology these advantages are mainly increased product purity and process simplification.

4. This leads to a noticeable reduction in investment costs, discharge costs and energy costs.

5. The benefits of a hybrid process: combining vapor permeation with rectification are illustrated by a comparison with a distillation process.



Vapor-Liquid-Equilibrium causes the need of many theoretical stages until reaching an isotropic mixture, where further distillation is not possible. This leads to loss of product, high energy consumption and makes further separation steps necessary. The driving force for the vapor permeation process is a partial pressure gradient from feed to permeate.

6. The essential advantage is the independency from Vapor-Liquid-Equilibrium. So, both separation operations, distillation and vapor permeation operate within their optimum range of concentrations and enable their efficient operation

Composites Manufacturing Processes:

1. Composite production techniques utilize various types of composite raw materials, including resins, fibers, mats, fabrics, prepregs (prepreg is a resin-impregnated fiber, fabric, or mat in flat form, which is stored for later use in hand lay-up or molding operations), and molding compounds, for the fabrication of composite parts.

2. Each manufacturing technique requires different types of material systems, different processing conditions, and different tools for part fabrication.

3. Composites manufacturing processes can be subdivided into two main manufacturing categories: manufacturing processes for thermostat composites and manufacturing processes for thermoplastic composites. In terms of commercial applications, thermo set composite parts dominate the composite market.



Maintenance requirement For Food and Beverages industries:-Hazards and preventive Maintenance:-

1. The food manufacturing industry employs many different types of workers and the hazards in food manufacturing vary between the different food and beverage industries. But some hazards are common for the whole industry.

Hazardous substances:-

2. During the cleaning or maintenance of production machinery, workers may be exposed to hazardous substances such as disinfectants and lubricants (hot and cold fluids), and ammonia in refrigeration systems.

3. Lubricants, greases, oils and hydraulic fluids are needed to protect machinery and moving parts against wear and corrosion and to prevent high temperatures caused by friction .Lubricants may pose a health risk to workers involved in maintenance tasks. They can provoke allergic reactions such as dermatitis or breathing problems.

4. Chemical food safety can also be affected by poor maintenance: e.g. contamination of food products with cleaner or sanitizer residue, contamination by maintenance tools, rusted metal containers, equipment or utensils or by foreign objects like glass or metal.

Preventive Maintenance:-

1. Dangerous substances should be replaced with less dangerous substances if possible. Maintenance workers must be trained and informed about the



chemicals they are working with. Appropriate protective equipment must be available.

2. Use of e.g. disinfectants and lubricants(cooling fluids) or cleaning agents (e.g. caustic soda, nitric acid) may cause eye injuries and requires eye protection. Emergency procedures should be in place.

Dust:-

1. In the food and beverage manufacturing explosions and fires can arise because of flammable dust and can have devastating and irreversible effects. Dust from flour, grain, custard powder, instant coffee, sugar, dried milk, potato powder and soup powder are examples of highly combustible dusts.

2. A suitable ignition source, e.g. an electrical spark which may occur when pulling a plug out of a socket or a hot surface (e.g. 300°C to 600°C) may cause an explosion

Exposure to dust can be controlled through:-

1. appropriate equipment design 2. keeping production equipment in effective and efficient working order 3. installation of exhaust ventilation at the source to reduce dust 4. regular checking, testing and maintenance of extraction systems 5. appropriate respiratory protective equipment when cleaning and maintaining

extraction systems



Maintenance requirements in Bottle filling plant:-

Elements describe the essential outcomes of a unit of competency.

Performance criteria describe the performance needed to demonstrate achievement of the element. Where bold italic text is used, further information is detailed in the required skills and knowledge section and the range statement. Assessment of performance is to be consistent with the evidence guide.

Prepare to operate bottle filling equipment

Product and materials are confirmed and available to meet bottling requirements Product and materials are prepared to meet bottling requirements Services are confirmed as available and ready for operation Bottle filling equipment is prepared and checked to confirm readiness for use Filling equipment is set to meet bottling requirements

Operate and monitor the bottle filling process

Bottle filling equipment is started up according to workplace procedures Control points are monitored to confirm performance is maintained within specification Bottles are filled according to specification



Bottle filling equipment is monitored to confirm operating condition Out-of-specification end product, process and equipment performance is identified, rectified and/or reported

Shut down the bottle filling process Bottle filling equipment is shut down according to workplace procedures Bottle filling equipment is prepared for cleaning Waste generated by both the process and cleaning procedures is collected, treated and disposed of, or recycled according to workplace procedures Work is conducted in accordance with workplace environmental guidelines

Record information Workplace information is recorded in appropriate format

Maintenance requirements in Bottle filling Plant:-Power plant preventive maintenance refers to set of planned activities -- which include nondestructive testing and periodic inspection as well as maintenance -- designed to prolong the life of equipment and facilities. It may include adjustment, cleaning, lubrication and replacement of minor components.

Benefits



Preventive maintenance activities can be classified as periodic, or time-based, planned or predictive. Their aim is to reduce the amount of unplanned maintenance work -- which consumes a large proportion of the cost of generating electricity -- needed in a power station.

It involves inspection, servicing, repairing or replacing physical components of machineries, plant and equipment by following the prescribed schedule.

Boilers

There are various conventional preventive maintenance techniques associated with boilers and boiler materials in power plants. These include liquid penetrant, magnetic particle and ultrasonic testing inspection techniques.

Involved in checking field Boiler and TG water report analysis and instruct the DM plant operator to fulfill the desired requirement of water.Involved in Cold & Hot Light-up of Boiler and specially watch its all parameters.

Turbines

Gas turbines, which use high temperature combustion gases as a working fluid, place severe thermal stresses on their components, so they need to be inspected and repaired or replaced on a regular basis. Even low temperature steam turbines can suffer from fatigue cracking or stress corrosion cracking and need to be repaired or reconditioned in similar fashion.

Involved in Hot & Cold start-up for turbine and watch for its all parameters. Efficient operation of the unit.

Give necessary instruction / direction to field technicians. To check and ensure the assigned field jobs are completed and recorded timely.

Co-ordinate with Maintenance departments for day-to-day operations and during preparation of equipment for handing over and taking back.

Operate / take on-line necessary equipment for smooth running of the plant. Co-ordinate the start ups and shutdown activities of the unit.



Perform activities as per the operating manual in case of any emergency situations.

Links: http://www.youtube.com/watch?v=kPV93HBUjew

http://www.youtube.com/watch?v=ac3lAl5P_yM

http://www.youtube.com/watch?v=is5wdVgPOkI

http://www.youtube.com/watch?v=0Wcn0M0Xx6Y

http://www.slideshare.net/mastersheel007/thermal-power-plant-s


http://www.slideshare.net/mastersheel007/thermal-power-plant-s

http://www.youtube.com/watch?v=0Wcn0M0Xx6Y

http://www.youtube.com/watch?v=is5wdVgPOkI

http://www.youtube.com/watch?v=ac3lAl5P_yM

http://www.youtube.com/watch?v=kPV93HBUjew

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