PROCESS CONTROL AND INSTRUMENTATION OF BOILERS

Project ReportSubmitted by

ADITYA KUMAR AGARWAL 121705

Under the guidance of

Mr. BIRBAL TANWAR

In partial fulfilment of the requirements for the award of the degree of

BACHELOR OF TECHNOLOGYINELECTRONICS ENGINEERING

DEPARTMENT OF ELECTRONICS ENGINEERING

DECLARATION

I hereby declare that the project work entitled Project Report on Boiler Process control and instrumentation is an authentic record of my own work carried out at Alstom India Limited, Sector-127, Noida as requirements of Five weeks internship for the award of degree of B.Tech, Electronics Engineering, Vishwakarma Institute of Technology,Pune, under the guidance of Mr. Birbal Tanwar during May26th to June 30th, 2014.

ADITYA KUMAR AGARWAL121705ELECTRONICS ENGINEERING

DATE: 30th June 2014

Certified that the above statement made by the student is correct to the best of our knowledge and belief.

Mr. BIRBAL TANWAR Head Electrical, C&IBoiler Department ALSTOM India Ltd, NoidaACKNOWLEDGEMENTIt gives me immense pleasure to take this opportunity to thank ALSTOM India Limited, Noida along with Mr. ABHISHESH SINGH (HR, Boiler Business) for giving me such a great opportunity to do project in their esteemed organization. I consider it my privilege to have carried out my project under this well-known quality conscious organization. Being a renowned company in India as well as abroad, I got a glimpse of corporate culture and ethics along with the hard work carried out by the employees here for successful completion of a project.

I would like to take this opportunity to express my sincere gratitude to my Project Head, Mr. BIRBAL SINGH TANWAR (HEAD ELECTRICAL,C&I DEPARTMENT) for his constant guidance, valuable suggestions and moral support.

I would like to express my sincere gratitude and indebtness to my mentor Mr. KUNAL KUMAR for his invaluable guidance and enormous help and encouragement, which helped me to complete my internship successfully. His way of working was a constant motivation throughout my internship term. I would like to thank him for answering my queries from time to time and for making me understand the various parts of Boiler.

I acknowledge gratefully the help and suggestion of ALSTOM employees and fellow trainees who were always help me with their warm attitude and technical knowledge, inspite of their busy schedule and huge workload.

Finally, no word will be enough to express my deepest reverence to family and friends without whose enthusiasm and support ,I wouldnt have been able to pursue my goals.

ADITYA KUMAR AGARWAL

Table of ContentsDECLARATION1ACKNOWLEDGEMENT2INTRODUCTION7OUR VALUES7MY VIEWS:8HISTORY8BUSINESSESS11RANKINE CYCLE16CARNOT CYCLE:18DIFFERENCE BETWEEN RANKINE CYCLE AND CARNOT CYCLE19BOILER SECTION:20ENGINEERING DEPARTMENT:20HR DEPARTMENT:21FINANCE DEPARTMENT:22ADMINISTRATION DEPARTMENT:23ONGOING PROJECTS:24CUSTOMERS:24ALSTOM IN INDIA24FACTS AND FIGURES25BOILERS26CLASSIFICATION OF BOILERS:27Fire tube boilers27Water tube boilers27COMPONENTS OF BOILERS:28Feedwater system291.Feedwater heater292.Deaerators303.Economisers30Steam system311.Steam and mud drums312.Boiler tubes313.Superheaters314.Attemperators325.Condensate systems33Fuel system341.Feed system for gaseous fuels342.Feed system for solid fuels35PIPING AND INSTRUMENTATION DIAGRAM (P&ID):36PROCESS LEGEND:38BASICS40ABBREVIATION TABLE:41EQUIPMENT TABLE:42KKS TAGING PROCEDURE:43Purpose43Requirements tobe metby theIdentification SystemKKS43Structure and Application of the Power Plant Identification System44INSTRUMENTATION IN BOILERS:44TEMPERATURE MEASUREMENT45Thermocouple45Resistance Temperature Detector (RTD)46Thermistor:47PRESSURE MEASUREMENT:47Bourdon tube-type detectors:48Diaphragm49Bellows491. Rectangular section bellow492.Round section bellow:503. Profile bellow504. Pipe joint bellow515. Industrial rectangular section bellow51FLOW MEASUREMENT52Turbine Meter52Magnetic Flow Meter52Orifice Plate53Venturi Meter53Dall tube:54Pitot tube:54LEVEL MEASUREMENT:55Open Tank Level Measurement:55Closed Tank Level Measurement:55PROCESS CONTROL IN BOILERS:56TYPES OF PROCESS CONTROL LOOPS56Feedback Control57Feedforward Control58Feedforward-plus-Feedback Control59Ratio Control60Cascade Control611.Why cascade control?612.Requirements for cascade control:61INSTRUMENT LIST62INPUT-OUTPUT LIST65PROJECT DETAILS67

INTRODUCTION Alstomis a French headquarteredmultinational companywhich holds interests in theelectricity generationandrail transportmarkets. Alstom is a global leader in the world of power generation, power transmission and rail infrastructure and sets the benchmark for innovative and environmentally friendly technologies It is also a major rail vehicle manufacturer, active in the fields of passenger transportation, signalling and locomotives, with products including the AGV, TGV, Eurostar, and Pendolino high speed trains, in addition to suburban, regional and metro trains, and Citadis trams. Alstom's headquarters are located in LEVALLOIS-PERRET, west of Paris. Its current CEO is PATRICK KRON.OUR VALUES TRUST: It is built on the responsibility given to each decision maker and the openness of each individual to his or her professional environment, ensuring transparency, which is vital in the management of risk. TEAM: Alstoms business is based on delivering projects whilst working in a team. This requires our collective discipline and efforts to execute them successfully, and networking to ensure we take full advantage of all the competencies available. ACTION: Alstom commits to delivering products and services to its customers which meet their expectations in terms of price, quality and delivery schedules. To meet our commitments to our customers, action is a priority for all of us. Action is built on strategic thinking, speed of execution to differentiate us from our competitors and the ability to report ensuring the achievement of our business objectivesMY VIEWS: TRUST: Every employee has faith on others and is committed to their work. The work environment is quite good and the work is completed within the specified time. TEAM: Team work is an essential part of any organisation and is thoroughly followed in Alstom. Every department works as a team and that helps in the overall growth of the Organisation. ACTION: Everyone is dedicated towards their work and action is given the highest priority. The action is also strategically thought so as to minimize the time and increase the efficiency and productivity of an individual so as to prosper the overall growth of the organisation.HISTORYYEARPOINTS OF NOTE

1928The beginning of Alsthom was from the merger of the French heavy engineering interests of the Thomson-Houston Electric Company (then General Electric), the Compagnie franaise pour l'exploitation des procds Thomson Houston, (or Compagnie Franaise Thomson Houston, CFTH) and Socit Alsacienne de Constructions Mcaniques (SACM), with its first factory in Belfort.

1969Compagnie Gnrale d'Electricit (CGE) becomes majority shareholder of Alsthom.

1977Alsthom constructs the first 1300MW generator set for the Paluel power station which set a world record with an output of 1500 MW.

1978The first TGV is delivered to SNCF. The TGV went on to break world rail speed records in 1981 (380 km/h) and 1990 (515.3 km/h), and achieved the world endurance record for high-speed train lines in 2001, travelling from Calais to Marseille (1067.2 km) in 3 hours and 29 mins.

1988-89Alsthom acquires 100% of the rail transport equipment division of ACEC as ACEC Transport.

1991Alstom's parent CGE is renamed Alcatel Alsthom Compagnie Gnrale d'Electricit, or Alcatel Alsthom

1994Rail vehicle manufacturer Linke-Hofmann-Busch (LHB), formerly part of Salzgitter AG group, is acquired by GEC Alsthom

1998GEC Alsthom acquired Cegelec (electrical contracting) as Alstom Power conversion.

1999Alstom andABBmerge their energy businesses in a 50-50 joint company known as ABB Alstom Power.Alstom sells its heavy duty gas turbine business to General electric.

2000Alstom acquires ABB's share in ABB Alstom Power. Alstom acquires a 51% stake inFiat Ferroviaria, the Italian rail manufacturer and world leader in tilting technology.

2003(April) Alstom sells its industrial turbine business (small to medium gas turbines 3-50MW, and steam turbines to 100MW) toSiemensfor 1.1 billion. In 2003 Alstom was undergoing a financial crisis due to poor sales and debt liabilities. Alstom's share price had dropped 90% over two years, and the company had over $5 billion of debt.Subsequently Alstom was required to sell several of its subsidiaries including its shipbuilding and electrical transmission assets as part of a 3.2 billion rescue plan involving the French state.

2004January: Alstom sells its T&D activities toAreva. Alstom sells Alstom Power Rentals to APR LLC later becoming APR Energy LLCAlstom sells the diesel locomotive manufacturerMeinfesa(Valencia, Spain) toVossloh AG.Alstom receives EU-approved French government bailout worth 2.5 billion.

2006Alstom sells its Marine Division to the Norwegian groupAKER YARDS. Alstom commits itself to keeping 25% of the shares until 2010.Alstom sells Alstom Power Conversion which becameConverteamGroup in a leveraged buy-out (LBO) deal funded byBarclays Private EquityFrance SAS.

2007Following a new Graphic Chart, the Group name is now written "alstom", with the exception of the legal entities which are written with Alstom in capitals, e.g., Alstom S.A.April: on a test run in France, TGV Est set theworld speed record for rail vehiclesof 574.8km/h.25 June: Acquired the Spanish wind turbine manufacturer Ecotcnia, and was namedAlstom Ecotcnia until April 2010, when the Ecotcnia name was dropped. The new entity legal name isAlstom Wind.

2009Alstom acquired 25% +1 share of Russian Transmashholding.

2010Alstom announces opening of a wind turbine assembly facility inAmarillo, Texas.Alstom re-acquires theElectric power transmissionDivision of Areva SA, which had previously been sold to Areva in 2004. A new division is created called Alstom Grid. Alstom inaugurates new hydropower manufacturing facility in China.

2011Alstom and the Iraqi government sign a memorandum of understanding regarding the construction of a new high-speed rail line between Baghdad and Basra.

2012Alstom begins construction of factories at:1.Sorel-Tracy, Quebec, Canada (passenger rail vehicles)2. Cherbourg (Turbine blades in association with LM Power, wind turbine towers) 3. Ufa, Russia, joint venture with RusHydro.

2013November Alstom announced it planned to raise 1 to 2 billion through sale of some non-core assets, plus the possible sale of a stake in Alstom Transport, and also cut 1300 jobs.

20141. (29 April)Reutersreports that the board of Alstom accepts a 10billion ($13.82billion) bid from GE for its energy operations, whilst remaining open to alternative unsolicited bids.2. (5 May) General Electric posts offers to buy 1/4 of the shares in Alstom's Indian power and distribution companies: Alstom T&D India Ltd. and Alstom India Ltd. at 261.25 and 382.20 rupees a share (value $278 million and $111 million respectively) subject to its bid for Alstom SA being successful.

BUSINESSESSPOWER:- RENEWABLE POWER Hydroelectric Power: #1 hydro motor generator installed base Leader of the pumped-storage equipment market Alstoms technology equips the worlds 5 highest capacity hydro installations in operation, amongst other record-breaking dams Leading R&D capabilities: a one-of-a-kind worldwide network of Global Technologies Centers.

Wind Power: Supply and installation of onshore wind turbines: reaching new heights of efficiency and reliability Supply and installation of offshore wind turbines: designed for the industrys most challenging environmental conditions Wind services: a full range of operation and maintenance services Technical assessment including wind farm design Project authorisation including permit applications Project financing

Solar Power:-Alstom developed CSP (concentrated solar power), because of its potential for large-scale, efficient power generation. Requiring clear skies and strong sunlight, at least 1900kWh/m2/y, CSP is the ideal fit for plants located on the Sun Belt. It is also ideal for centralized on grid or industrial applications with adequate tariff structures. Thanks to the option of storage capacity that it offers, CSP allows you to have power long after sunset or on days with some cloud coverage.

Geothermal Power:-Alstom pioneered the commercial exploitation of geothermal power in New Zealand in the 1950s. Today, were at the cutting edge of geothermal innovation, with an extensive portfolio of proven technologies, plus the ability to create custom-made solutions for the most challenging geothermal applications.

Biomass Power:-Alstoms wide range of experience includesburning all types of fuels in boilers, including biomass. We receive, handle, store and process biomass materials, ready for direct injection into boilers. Alstom has beenretrofitting biomass co-firing systems for nearly two decades. Youll benefit from greatlyreduced CO2emissionswith our biomass-fired steam power plants.

Ocean Energy:- Ocean energy is a major growth area in renewable power. Alstom is the only company that offers proven products for both the tidal and offshore wind markets. Tidal Energy: - Tidal power offers an inexhaustible supply of energy, free of greenhouse gas emissions once installed. It also has the advantage of being totally predictable, as tidal currents result from perfectly known astronomical phenomena. Alstom is at forefront of developing tidal stream turbine technology in order to take advantage of the significant energy potential in our tides, and in 2013 Alstom acquired the significant technology and expertise of Tidal Generation Ltd (TGL). Offshore Wind Power: - Alstom has installed the worlds largest offshore wind turbine off the Belgian coast, the Haliade 150-6MW.This is the largest offshore wind turbine ever installed in sea waters. Thanks to its 150-metre diameter rotor (with blades stretching 73.50 metre), the turbine is more efficient since its yield is 15% better than existing offshore turbines, enabling it to supply power to the equivalent of about 5,000 households.NON RENEWABLE POWER: Coal and Oil Power:-Alstom provides an extensive product portfolio with cutting edge technologies with reduces carbon emission by upto 35%. Coal and oil power plants: Improve fuel flexibility, plant efficiency and reduce emissions from fossil fuels with a coal and oil power plant from Alstom Steam turbines: leading the way in efficiency and reliability Turbogenerators:The highest standards of performance at a cost-effective price Boilers: Reliable, clean fossil fuel combustion Air quality control systems: Reducing emissions from combustion processes Carbon capture and storage(CCS): To provide optimum efficiency as well as environmental and commercial benefits to power plant operators worldwide, the next generation of Alstoms steam power plant will be available with technology capable of capturing up to 90% of the CO2 emissions.

Gas Power:-Alstom has been helping the operators of gas-fired power plants to balance fluctuating fuel prices and availability with environmental concerns for more than 75 years. Gas power plants Gas services Gas turbines HSRGs(Heat recovery steam generators)

Nuclear Power:-Alstom equips 30% of the worlds nuclear power plants with its reliable turbine generator sets. Our equipment is currently in 40% of todays nuclear plants. Teams at Alstom work at maximizing the power output delivered by all the reactors by increasing the efficiency of the power conversion systems. Turbine Islands Steam Turbines Services Turbogenerators

TRANSPORT:- Trains:- Metro Metropolis Tram way Citadis Tram way Citadis compact Tram trains Citadis Dualis and Regio Citadis Regional train Coradia Suburban train XTrapolis Locomotive prim a II Very high speed train duplex Very high speed AGV

Services:- Maintenance Modernization Parts and repair Support services Systems:- Infrastructures Integrated Solutions Signaling:- Urban control system Atlas signaling solution Iconis integrated control Centre Smart lock interlocking Passenger information and entertainment Security

GRID:- Smart solution:- Smart grid HVDC super grid Facts Renewable Network management:- Generation Transmission Distribution Demand response Telecommunication Oil and gas Consulting and system integration High voltage products :- Turnkey substation Gas in capsulated substation Air insulated switchgears Power transformers

RANKINE CYCLE The Rankine cycle is the fundamental operating cycle of all power plants where an operating fluid is continuously evaporated and condensed. The selection of operating fluid depends mainly on the available temperature range.Figure1 shows the idealized Rankine cycle.The pressure-enthalpy (p-h) and temperature-entropy (T-s) diagrams of this cycle are given inFigure2. The Rankine cycle operates in the following steps: 1-2-3Isobaric Heat Transfer. High pressure liquid enters the boiler from the feed pump (1) and is heated to the saturation temperature (2). Further addition of energy causes evaporation of the liquid until it is fully converted to saturated steam (3). 3-4Isentropic Expansion. The vapor is expanded in the turbine, thus producing work which may be converted to electricity. In practice, the expansion is limited by the temperature of the cooling medium and by the erosion of the turbine blades by liquid entrainment in the vapor stream as the process moves further into the two-phase region. Exit vapor qualities should be greater than 90%. 4-5Isobaric Heat Rejection. The vapor-liquid mixture leaving the turbine (4) is condensed at low pressure, usually in a surface condenser using cooling water. In well designed and maintained condensers, the pressure of the vapor is well below atmospheric pressure, approaching the saturation pressure of the operating fluid at the cooling water temperature. 5-1Isentropic Compression. The pressure of the condensate is raised in the feed pump. Because of the low specific volume of liquids, the pump work is relatively small and often neglected in thermodynamic calculations. Theefficiency of power cyclesis defined as

CARNOT CYCLE:The Carnot cycle is a theoretical thermodynamic cycle proposed by Nicolas Lonard Sadi Carnot in 1824 and expanded by Benoit Paul mile Clapeyron in the 1830s and 40s. It can be shown that it is the most efficient cycle for converting a given amount of thermal energy into work, or conversely, creating a temperature difference (e.g. refrigeration) by doing a given amount of work.

Stages of the Carnot Cycle

The Carnot cycle when acting as a heat engine consists of the following steps:1. Reversible isothermal expansion of the gas at the "hot" temperature, TH (isothermal heat addition or absorption). During this step the expanding gas makes the piston work on the surroundings. The gas expansion is propelled by absorption of quantity Q1 of heat from the high temperature reservoir.2. Isentropic (reversible adiabatic) expansion of the gas (isentropic work output). For this step the piston and cylinder are assumed to be thermally insulated, thus they neither gain nor lose heat. The gas continues to expand, working on the surroundings. The gas expansion causes it to cool to the "cold" temperature, TC.3. Reversible isothermal compression of the gas at the "cold" temperature, TC (Isothermal heat rejection). Now the surroundings do work on the gas, causing quantity Q2 of heat to flow out of the gas to the low temperature reservoir.4. Isentropic compression of the gas (isentropic work input) Once again the piston and cylinder are assumed to be thermally insulated. During this step, the surroundings do work on the gas, compressing it and causing the temperature to rise to TH. At this point the gas is in the same state as at the start of step 1.

DIFFERENCE BETWEEN RANKINE CYCLE AND CARNOT CYCLEThe main difference between that Rankine Cycle and the Carnot Cycle is that heat transfer across the system boundary of Carnot Cycle is isothermal (constant temperature), and heat transfer across the system boundary in a Rankine cycle is isobaric (constant pressure). The Rankine cycle is a better model for most real systems because a constant pressure heat exchanger is a better approximation for how heat transfer is accomplished in most real systems than heat transfer to/from constant temperature "heat reservoirs."

BOILER SECTION:ENGINEERING DEPARTMENT:1. ELECTRICAL, CONTROL AND INSTRUMENTATION ENGINEERING:-Role of C&I Department is to: Design P&I (PROCESS &INSTRUMENTATION) DIAGRAM Create I/O List Create Instrument list Create Electrical load list Create Technical Specification chart & Datasheet Create Single Line Diagram(SLDs) Create Lighting Scheme Create Lightning scheme(ILLUMINATION) Create Logics(OLCD,CLSC,BMD)

2. PRESSURE PART: Various pressure parts like SH, RH, Valves and pipes are designed.

3. GA(General Arrangement) Group:The 2d and 3D models and layouts of boilers are designed in this section.

4. STRUCTURE: Boiler specifications and structure are done in this section.

5. FIELD OPERATION: The field support i.e. erection and commissioning is done in this section.

6. SUPPLY CHAIN MANAGEMENT: Supply chain management is a cross-functional approach that includes managing the movement of raw materials into an organization, certain aspects of the internal processing of materials into finished goods, and the movement of finished goods out of the organization and toward the end consumer.The purpose of supply chain management is to improve trust and collaboration among supply chain partners, thus improving inventory visibility and the velocity of inventory movement. Main function of supply chain management is as follows:

Inventory Management Distribution Management Channel Management Payment Management Financial Management Supplier Management

7. PROCESS/EQUIPMENT: Under this section Boiler processes and Equipment like fan, pump and APH are designed. HR DEPARTMENT:This department manages the companys most valuable resource i.e. its employees. It performs various functions like Recruitment, safety, employee relations, training and development etc. Following are its some of the most important functionalities:-

MANPOWER PLANNING: It involves the planning for the future and finding out how many employees will be needed in the future by thebusiness and what types of skills should they possess. JOB ANALYSIS AND JOB DESCRIPTION: It involves process to collect correct information about the duties, responsibilities, necessary skills and work environment of a particular job. RECRUITMENT WAGES AND SALARIES: It involves recruitment of best people in an organisation as organisations success depends on quality of workforce. PERFORMANCE APPRAISAL: It includes reviewing of the performance of the employees recruited on a regular basis. The main focus is to measure and improve the actual performance of the employee. LABOUR MANAGEMENT RELATIONS: It ensures that the labour management relations are cordial and in case of any conflict, it will play an important role in resolving the issue by bringing them to negotiation table. DISMISSAL AND REDUNDANCY: It takes firm actions against employees who are not following organizational code of conduct, rules and regulations. This can result in the dismissal of the employee.

FINANCE DEPARTMENT:The finance department is responsible for management of the organizations cash flow. It prepares the companies cash account, pays the salary etc. Following are its some of the most important functionalities:-

BOOK KEEPING PROCEDURES: Keeping records of the purchases and sales made by a business as well as capital spending.

PREPARING FINAL ACCOUNTS: Profit and loss account and Balance Sheets

PROVIDING MANAGEMENT INFORMATION: Managers require ongoing financial information to enable them to make better decisions.

MANAGEMENT OF WAGES: The wages section of the finance department will be responsible for calculating the wages and salaries of employees and organising the collection of income tax and national insurance for the Inland Revenue.

RAISING FINANCE: The finance department will also be responsible for the technical details of how a business raises finance e.g. through loans, and the repayment of interest on that finance. In addition it will supervise the payment of dividends to shareholders.

ADMINISTRATION DEPARTMENT:The administrative department covers a wide range of functions such as departmental support in HR, finance, IT support and general running of an organisation. The main functions of an administration department of an organization are:

To process paperwork for external suppliers.

To process paperwork and information for internal people. This could be anything from looking after the basic bills to the internal post.

Looking after the internal communications so that all members of the organization are aware of what is going on within the organization.

Organizing any deliveries or suppliers coming into the offices for the day for any reason.

Arranging company extras such as company cars and any hotels for business trips that may be needed.

Sending out any mail on behalf of the company. This could be for different stakeholders, customers or even for staff.

ONGOING PROJECTS NTPC Barh II Supercritical Boilers 2 x 660 MW - under execution* APGENCO Krishnapatnam - Supercritical Boilers 2 x 800 MW - under execution* Jay Pee - Bara - Supercritical Boilers 3 x 660 MW - under execution* NTPC Mouda - Supercritical Boilers 2 x 660 MW - under execution* NTPC Nabinagar Supercritical Steam Turbine Islands and Boilers* 3 X 660 MW - under execution BHEL Gadarwara Super Thermal Power Plant* - 2 X 800 MW under executionCUSTOMERS National Thermal Power Corporation (NTPC). Neyveli Lignite Corporation Limited. Rajasthan Rajya Vidyut Utpadan Nigam Ltd. NSL Orissa Power and Infratech Private Ltd. Bharat Heavy Electrical Limited.ALSTOM IN INDIA Alstom has been associated with Indias progress for a century and has a long-standing reputation for providing highly innovative and sustainable solutions for meeting the countrys energy and transport requirements. Since its inception in the year 1911, the company has been at the forefront of leading-edge technology at every level. The company works with a number of strategic partners in India to offer a wide range of solutions for every sector Power, Transport & Grid. ALSTOM India statistics:Around 9,000 employees in India .Three R&D Centers in Bengaluru (Power and Transport), Vadodara (Power) and Hosur (Grid). Two engineering centers at Noida and Kolkata.

FACTS AND FIGURES 93002 employees at end of March 2014 21.5 billion orders in 2013-14 20.3 billion sales in 2013-14 Present in more than 100 countries Sales 2013-2014 : 20.3 billionBOILERS A Boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications. Instrumentation and controls in a boiler plant encompass an enormous range of equipment from simple industrial plant to the complex in the large utility station. The boiler control system is the means by which the balance of energy & mass into and out of the boiler are achieved. Inputs are fuel, combustion air, atomizing air or steam &feed water. Of these, fuel is the major energy input. Combustion air is the major mass input. Outputs are steam, flue gas, blow down, radiation & soot blowing.

CLASSIFICATION OF BOILERS: Fire tube boilers :In fire tube boilers hot gases are passed through the tubes and water surrounds these tubes. These are simple, compact and rugged in construction. Depending on whether the tubes are vertical or horizontal these are further classified as vertical and horizontal tube boilers. Due to large quantity of water in the drain it requires more time for steam raising. The steam attained is generally wet, economical for low pressures .The output of the boiler is also limited.

Water tube boilers: In these boilers water is inside the tubes and hot gases are outside the tubes. Feed water enters the boiler to one drum. This water circulates through the tubes connected external to drums. Hot gases which surround these tubes will convert the water in tubes in to steam. This steam is passed through tubes and collected at the top of the drum since it is of light weight. The entire steam is collected in one drum and it is taken out from there. As the movement of water in the water tubes is high, so rate of heat transfer also becomes high resulting in greater efficiency. They produce high pressure, easily accessible and can respond. COMPONENTS OF BOILERS:The main components in a boiler system are Economiser, Evaporator, Superheater, Reheator, Attemperator . In addition, there are sets of controls to monitor water and steam flow, fuel flow, airflow and chemical treatment additions.More broadly speaking, the boiler system comprises of a feedwater system, steam system and fuels system. The feedwater system provides water to the boiler and regulates it automatically to meet the steam demand. Various valves provide access for maintenance and repair.The stem system collects and controls the steam produced in the boiler. Steam is directed through a piping system to the point of use. Throughout the system, steam pressure is regulated using valves and checked with steam pressure gauges.The fuel system includes all equipment used to provide fuel to generate the necessary heat. The equipment required in the fuel system depends on the type of fuel used in the system.

Feedwater system The water supplied to the boiler, which is converted into steam, is called feedwater. The two sources of feedwater are condensate or condensed steam returned from the process and makeup water (treated raw water) which must come from outside the boiler room and plant processes. 1. Feedwater heater Boiler efficiency is improved by the extraction of waste heat from spent steam to preheat the boiler feedwater. Heaters are shell and tube heat exchangers with the feedwater on the tube side (inside) and steam on the shell side (outside). The heater closest to the boiler receives the hottest steam. The condensed steam is recovered in the heater drains and pumped forward to the heater immediately upstream, where its heat value is combined with that of the steam for that heater. Ultimately the condensate is returned to the condensate storage tank or condenser hot well. 2. Deaerators Feedwater often has oxygen dissolved in it at objectionable levels, which comes from air in-leakage from the condenser, pump seals, or from the condensate itself. The oxygen is mechanically removed in a deaerator. Deaerators function on the principle that oxygen is decreasingly soluble as the temperature is raised. This is done by passing a stream of steam through the feedwater. Deaerators are generally a combination of spray and tray type. One problem with the control of deaerators is ensuring sufficient temperature difference between the incoming water temperature and the stripping steam. If the temperature is too close, not enough steam will be available to strip the oxygen from the make-up water. 3. Economisers Economisers are the last stage of the feedwater system. They are designed to extract heat value from exhaust gases to heat the steam still further and improve the efficiency of the boiler. They are simple finned tube heat exchangers. Not all boilers have economizers. Usually they are found only on water tube boilers using fossil fuel as an energy conservation measure. A feedwater economiser reduces steam boiler fuel requirements by transferring heat from the flue gas to incoming feedwater. By recovering waste heat, an economiser can often reduce fuel requirements by 5 per cent to 10 per cent and pay for itself in less than two years. A feedwater economiser is appropriate when insufficient heat transfer surface exists within the boiler to remove combustion heat. Boilers that exceed 100 boiler hp, operating at pressures exceeding 75 psi or above, and those that are significantly loaded all year long are excellent candidates for economiser retrofit.

Steam system 1. Steam and mud drums A boiler system consists of a steam drum and a mud drum. The steam drum is the upper drum of a water tube boiler where the separation of water and steam occurs. Feedwater enters the boiler steam drum from the economizers or from the feedwater heater train if there is no economiser. The colder feedwater helps create the circulation in the boiler.

The steam outlet line normally takes off from this drum to a lower drum by a set of riser and downcomer tubes. The lower drum, called the mud drum, is a tank at the bottom of the boiler that equalizes distribution of water to the generating tubes and collects solids such as salts formed from hardness and silica or corrosion products carried into the boiler. In the circulation process, the colder water, which is outside the heat transfer area, sinks and enters the mud drum. The water is heated in the heat transfer tubes to form steam. The steam-water mixture is less dense than water and rises in the riser tubes to the steam drum. The steam drum contains internal elements for feedwater entry, chemical injection, blowdown removal, level control, and steam-water separation. The steam bubbles disengage from the boiler water in the riser tubes and steam flows out from the top of the drum through steam separators. 2. Boiler tubes Boiler tubes are usually fabricated from high-strength carbon steel. The tubes are welded to form a continuous sheet or wall of tubes. Often more than one bank of tubes is used, with the bank closest to the heat sources providing the greatest share of heat transfer. They will also tend to be the most susceptible to failure due to flow problems or corrosion/ deposition problems. 3. Superheaters The purpose of the superheater is to remove all moisture content from the steam by raising the temperature of the steam above its saturation point. The steam leaving the boiler is saturated, that is, it is in equilibrium with liquid water at the boiler pressure (temperature). The superheater adds energy to the exit steam of the boiler. It can be a single bank or multiple banks or tubes either in a horizontal or vertical arrangement that is suspended in the convective or radiation zone of the boiler. The added energy raises the temperature and heat content of the steam above saturation point. In the case of turbines, excessive moisture in the steam above saturation point. In the case of turbines, excessive moisture in the steam can adversely affect the efficiency and integrity of the turbine. Superheated steam has a larger specific volume as the amount of superheat increases. This necessitates larger diameter pipelines to carry the same amount of steam. Due to temperatures, higher alloy steel is used. It is important that the steam is of high purity and low moisture content so that non-volatile substances do not build up in the superheater. 4. Attemperators Attemperation is the primary means for controlling the degree of superheat in a superheated boiler. Attemperation is the process of partially de-superheating steam by the controlled injection of water into the superheated steam flow. The degree of superheat will depend on the steam load and the heat available, given the design of the superheater. The degree of superheat of the final exiting steam is generally not subject to wide variation because of the design of the downstream processes. In order to achieve the proper control of superheat temperature an attemperator is used. A direct contact attemperator injects a stream of high purity water into the superheated steam. It is usually located at the exit of the superheater, but may be placed in an intermediate position. Usually, boiler feedwater is sued for attemperation. The water must be free of non-volatile solids to prevent objectionable buildup of solids in the main steam tubes and on turbine blades. Since in attemperator water comes from the boiler feedwater, provision for it has to be made in calculating flows. The calculation is based on heat balance. The total enthalpy (heat content) of the final superheat steam must be the mass weighted sum of the enthalpies of the initial superheat steam and the attemperation water. 5. Condensate systems Although not a part of the boiler, condensate is usually returned to the boiler as part of the feedwater. Accordingly, one must take into account the amount and quality of the condensate when calculating boiler treatment parameters. In a complex steam distribution system there will be several components. These will include heat exchangers, process equipment, flash tanks, and storage tanks. Heat exchangers are the places in the system where steam is used to heat a process or air by indirect contact. Shell and tube exchangers are the usual design, with steam usually on the shell side. The steam enters as superheated or saturated and may leave as superheated, saturated, or as liquid water, depending on the initial steam conditions and the design load of the exchanger. Process equipment includes turbines whether used for HVAC equipment, air compressors, or turbine pumps. Condensate tanks and pumps are major points for oxygen to enter the condensate system and cause corrosion. These points should be monitored closely for pH and oxygen ingress and proper condensate treatment applied.

Fuel system Fuel feed systems play a critical role in the performance of boilers. Their primary functions include transferring the fuel into the boiler and distributing the fuel within the boiler to promote uniform and complete combustion. The type of fuel influences the operational features of a fuel system The fuel feed system forms the most significant component of the boiler system. 1. Feed system for gaseous fuels Gaseous fuels are relatively easy to transport and handle. Any pressure difference will cause gas to flow, and most gaseous fuels mix easily with air. Because on-site storage of gaseous fuel is typically not feasible, boilers must be connected to a fuel source such as a natural gas pipeline. Flow of gaseous fuels to a boiler can be precisely controlled using a variety of control systems. These systems generally include automatic valves that meter gas flow through a burner and into the boiler based on steam or hot water demand. The purpose of the burner is to increase the stability of the flame over a wide range of flow rates by creating a favourable condition for fuel ignition and establishing aerodynamic conditions that ensure good mixing between the primary combustion air and the fuel. Burners are the central elements of an effective combustion system. Other elements of their design and application include equipment for fuel preparation and air-fuel distribution as well as a comprehensive system of combustion controls. Like gaseous fuels, liquid fuels are also relatively easy to transport and handle by using pumps and piping networks that link the boiler to a fuel supply such as a fuel oil storage tank. To promote complete combustion, liquid fuels must be atomized to allow through mixing with combustion air. Atomisation by air, steam, or pressure produces tiny droplets that burn more like gas than liquid. Control of boilers that burns liquid fuels can also be accomplished using a variety of control systems that meter fuel flow. 2. Feed system for solid fuels Solid fuels are much more difficult to handle than gaseous and liquid fuels. Preparing the fuel for combustion is generally necessary and may involve techniques such as crushing or shredding. Before combustion can occur, the individual fuels particles must be transported from a storage area to the boiler. Mechanical devices such as conveyors, augers, hoppers, slide gates, vibrators, and blowers are often used for this purpose. The method selected depends primarily on the size of the individual fuels particles and the properties and characteristics of the fuel. Stokers are commonly used to feed solid fuel particles such as crushed coal, TDF, MSW, wood chips, and other forms of biomass into boilers. Mechanical stokers evolved from the hand-fired boiler era and now include sophisticated electromechanical components that respond rapidly to changes in steam demand. The design of these components provides good turndown and fuel-handling capability. In this context, turndown is defined as the ratio of maximum fuel flow to minimum fuel flow. In the case of pulverized coal boilers, which burn very fine particles of coal, the stoker is not used. Coal in this form can be transported along with the primary combustion air through pipes that are connected to specially designed burners. A burner is defined as a devices or group of devices for the introduction of fuel and air into a furnace at the required velocities, turbulence, and concentration to maintain ignition and combustion of fuel with in the furnace. Burners for gaseous fuels are less complex than those for liquid or solid fuels because mixing of gas and combustion air is relatively simple compared to atomizing liquid fuels or dispersing solid fuel particles. The ability of a burner to mix combustion air with fuel is a measure of its performance. A good burner mixes well and liberates a maximum amount of heat from the fuel. The best burners are engineered to liberate the maximum amount of heat from the fuel and limit the amount of pollutants such as CO, NOx, and PM that are released. Burners with these capabilities are now used routinely in boilers that must comply with mandated emission limitations.PIPING AND INSTRUMENTATION DIAGRAM (P&ID):A piping and instrumentation diagram/drawing (P&ID) is a diagram in the process industry which shows the piping of the process flow together with the installed equipment and instrumentation.The purpose of P&IDs is to provide an initial design basis for the boiler. The P&IDs provides the engineering requirements to identify the measurements and functions that are to be controlled. It may be used to define the number of inputs, outputs and list of all the instruments and functions.SAMPLE P&ID OF LOW PRESSURE STARTUP SYSTEMS (For reference only)

PROCESS LEGEND:The process legend provides the information needed to interpret and read the P&ID. Process legends are found at the front of the P&ID. The legend includes information about piping, instrument and equipment symbols, abbreviations, unit name, drawing number, revision number, approvals, and company prefixes. Because symbol and diagram standardization is not complete, many companies use their own symbols in unit drawings. Unique and unusual equipment will also requires a modified symbol value.

BASICS

ABBREVIATION TABLE: FCFlow ControllerLCVLevel Control Valve FIFlow IndicatorLRCLevel Recording ControllerFS Flow SwitchLGLevel GaugeFICFlow Indicating ControllerLRLevel RecorderFCVFlow Control Valve LTLevel TransmitterFRCFlow Recording ControllerLSLevel Switch LICLevel Indicating ControllerPCPressure ControllerPGPressure GaugeTCTemperature ControllerPIPressure IndicatorTTTemperature TransmitterPRPressure Recorder TETemperature Element PSPressure SwitchTITemperature IndicatorPICPressure Indicating ControllerTRTemperature RecorderPCVPressure Control ValveTSTemperature SwitchPRCPressure Recording ControllerPDIPressure Differential IndicatorPDRPressure Differential RecorderPDSPressure Differential SwitchPDTPressure Differential Transmitter PTPressure TransmitterPTDPressure TransducerEQUIPMENT TABLE:

KKS TAGING PROCEDURE:To planning, setting-up and operating power plants it is absolutely necessary to use astandardized identification system.The KRAFTWERK-KENNZEICHEN-SYSTEM(KKS) is such a system.The engineering of power plants with modern human-engine-communication needs a common language in all sectors of engineering today, like applications in civil, mechanical, electrical and control and instrumentation engineering. Reliability and operational efficiency make more and more higher conditions to the planning, setting-up and operating of power plants.Increasing plant-power and a higher degree of automation presuppose a powerful increase of technical data and information. IDENTIFICATION SYSTEM FOR POWER PLANTS PurposeThe power plant identification system is applied to clearly identify plants, systems, parts and components to their purpose, type and location. The contents are based on the Identification Systems for Power Plant (KKS) published by VGB- Technical Association of Large Power Plant Operators. Requirements tobe metby theIdentification SystemKKSIn order to perform the set tasks the identification system must be capable of satisfying the following requirements: Determination of all installations and sub-systems, An adequate number of reserve codes must be available for future developments in power plant engineering. The classification of installations and sub-systems must be generally applicable to alltypes of power plant; all individual circuits and arrangements must, however, be clearly identifiable. Clear identification of all sub-systems. An identification used in a power plant must be non-recurring, Subdivision with graded details and a fixed meaning for the data characters. various areas of application, Independent identification of various systems must be possible Ease of recognition ensured by clarity and an acceptable length for the identification. Plausibility check facility, especially for data processing, Existing standards, guidelines and recommendations must be takeninto account

Structure and Application of the Power Plant Identification System The KKS consists of three types ofidentification: The process-related identification identifies installations and equipment according to their assigned task in the power plant process, The point of installation identification identifies the points of installation within an installation unit (e.g. cubicles, consoles, panels), The location identification identifies the rooms and floors, or other installation sites, for installations and equipment in buildingstructures.INSTRUMENTATION IN BOILERS:A device, such as a photoelectric cell, that receives and responds to a signal or stimulus. A device which detects a variable quantity ,measures and converts the measurement into a signal to be recorded elsewhere. Asensoris a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, amercury thermometerconverts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube. Athermocoupleconverts temperature to an output voltage which can be read by avoltmeter. For accuracy, all sensors need to becalibratedagainst knownstandards.TEMPERATURE MEASUREMENTAttempts of standardized temperature measurement have been reported as early as 170 AD by Claudius Galenus. The modern scientific field has its origins in the works by Florentine scientists in the 17th century. Early devices to measure temperature were called thermo scopes. The first sealed thermometer was constructed in 1641 by the Grand Duke of Toscani, Ferdinand II. The development of today's thermometers and temperature scales began in the early 18th century, when Gabriel Fahrenheit adapted a thermometer using mercury and a scale both developed by Ole Christensen Rmer. Fahrenheit's scale is still in use, alongside the Celsius scale and the Kelvin scale.

ThermocoupleAthermocoupleis a junction between two different metals that produces a voltage related to a temperature difference. Thermocouples are a widely used type oftemperature sensor and can also be used to convert heat into electric power.

Resistance Temperature Detector (RTD)Resistance Temperature Detectors (RTD), as the name implies, are sensors used to measure temperature by correlating the resistance of the RTD element with temperature. Most RTD elements consist of a length of fine coiled wire wrapped around a ceramic or glass core. The element is usually quite fragile, so it is often placed inside a sheathed probe to protect it. The RTD element is made from a pure material whose resistance at various temperatures has been documented. The material has a predictable change in resistance as the temperature changes; it is this predictable change that is used to determine temperature. Thermistor:A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors. The word is a portmanteau of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self-resetting overcurrent protectors, and self-regulating heating elements.Thermistors differ from resistance temperature detectors (RTD) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature response is also different; RTDs are useful over larger temperature ranges, while thermistors typically achieve a higher precision within a limited temperature range, typically 90 C to 130 C.

PRESSURE MEASUREMENT:Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure pressure are called pressure gauges or vacuum gauges. Pressure gauge was discovered by Otto Von Guericke.A pressure gauge is used to measure the pressure in a vacuumwhich is further divided into two subcategories, high and low vacuum (and sometimes ultra-high vacuum). The applicable pressure range of many of the techniques used to measure vacuums has an overlap. Hence, by combining several different types of gauge, it is possible to measure system pressure continuously from 10 mbar down to 1011 mbar.The SI unit for pressure is the Pascal (Pa), equal to one newton per square meter. This special name for the unit was added in 1971; before that, pressure in SI was expressed in units such as N/m2. Bourdon tube-type detectors:The majority of pressure gauges in use have a Bourdon-tube as a measuring element. (The gauge is named for its inventor, Eugene Bourdon, a French engineer.) The Bourdon tube is a device that senses pressure and converts the pressure to displacement. Since the Bourdon-tube displacement is a function of the pressure applied, it may be mechanically amplified and indicated by a pointer. Thus, the pointer position indirectly indicates pressure. The Bourdon-tube gauge is available in various tube shapes: curved or C-shaped, helical, and spiral. The size, shape, and material of the tube depend on the pressure range and the type of gauge desired. Low-pressure Bourdon tubes (pressures up to 2000 psi) are often made of phosphor bronze. High-pressure Bourdon tubes (pressures above 2000 psi) are made of stainless steel or other high-strength materials. High- pressure Bourdon tubes tend to have more circular cross sections than their lower-range counterparts, which tend to have oval cross sections. The Bourdon tube most commonly used is the C-shaped metal tube that is sealed at one end and open at the other.

DiaphragmDiaphragm valves are used on shut-off and throttling service for liquids, slurries and vacuum/gas. The seal is achieved by a flexible membrane, usually elastomer, and possibly reinforced with a metal part. The membrane is tensed by the effect of a stem/compressor with linear movement until contact is made against the seal of the body. The operating parts of the diaphragm valve are isolated from the flow. This makes this valve suitable for viscous flows and also hazardous, abrasive and corrosive flows as its sealing system avoids any contamination towards or from the environment. Diaphragm valves are available in a wide variety of metals, solid plastics, plastic, rubber and glass linings. They are well suited to the handling of multiple chemical applications both clear fluids as well as slurries. The diaphragm valve has an extended use for applications at low pressures and slurry fluid where most other kinds of valves corrode or become obstructed. It is a quick opening valve.There are two types of diaphragm valves: Straightway: named also Straight-Thru is only used for on/off services .Weir: The Weir Diaphragm valve can be used for either off/on or throttling services.

Bellows

A bellows is a device for delivering pressurized air in a controlled quantity to a controlled location.Types of industrial bellows:1. Rectangular section bellow: They are utilized specifically in the electrical and automobile industry.

2.Round section bellow: The round section bellow are used for covering heavily stressed and movable round machine parts such as shafts, spindles and lead screws pistons.

3. Profile bellow: Profile bellow is lightweight, accurate and durable that can be used in a wide range of electrical industries.

4. Pipe joint bellow: The pipeline bellow is used in numerous industries that require movement of water at high pressure in a controlled manner.

5. Industrial rectangular section bellow: Industrial bellows find use in the protection of gear rods from dirt and dust in all kinds of automobiles. They are normally used as covers on parts which are critical and need protection from dust.

FLOW MEASUREMENTFlow measurement is the quantification of bulk fluid movement. Flow can be measured in a variety of ways. Positive-displacement flow meters accumulate a fixed volume of fluid and then count the number of times the volume is filled to measure flow. Other flow measurement methods rely on forces produced by the flowing stream as it overcomes a known constriction, to indirectly calculate flow. Flow may be measured by measuring the velocity of fluid over a known area. Both gas and liquid flow can be measured in volumetric or mass flow rates, such as liters per second or kilograms per second.

Turbine MeterIn a turbine, the basic concept is that a meter is manufactured with a known cross sectional area. A rotor is then installed inside the meter with its blades axial to the product flow. When the product passes the rotor blades, they impart an angular velocity to the blades and therefore to the rotor. This angular velocity is directly proportional to the total volumetric flow rate.Turbine meters are best suited to large, sustained flows as they are susceptible to start/stop errors as well as errors caused by unsteady flow states. Magnetic Flow MeterMeasurement of slurries and of corrosive or abrasive or other difficult fluids is easily made. There is no obstruction to fluid flow and pressure drop is minimal. The meters are unaffected by viscosity, density, temperature, pressure and fluid turbulence. Magnetic flow meters utilize the principle of Faradays Law of Induction; similar principle of an electrical generator. When an electrical conductor moves at right angle to a magnetic field, a voltage is induced.

Orifice Plate An orifice plate is a plate with a hole through it, placed in the flow; it constricts the flow and measuring the pressure differential across the constriction gives the flow rate. It is basically a crude form of Venturi meter, but with higher energy losses. There are three type of orifice: concentric, eccentric, and segmental.

Venturi MeterA Venturi meter constricts the flow in some fashion, and pressure sensors measure the differential pressure before and within the constriction. This method is widely used to measure flow rate in the transmission of gas through pipelines, and has been used since Roman Empire times. The coefficient of discharge of Venturi meter ranges from 0.93 to 0.97.

Dall tube: The Dall tube is a shortened version of a Venturi meter, with a lower pressure drop than an orifice plate. As with these flow meters the flow rate in a Dall tube is determined by measuring the pressure drop caused by restriction in the conduit. The pressure differential is typically measured using diaphragm pressure transducers with digital readout. Since these meters have significantly lower permanent pressure losses than orifice meters, Dall tubes are widely used for measuring the flow rate of large pipeworks.

Pitot tube: A Pitot tube is a pressure measuring instrument used to measure fluid flow velocity by determining the stagnation pressure. Bernoulli's equation is used to calculate the dynamic pressure and hence fluid velocity. Also see Air flow meter.

LEVEL MEASUREMENT: Open Tank Level Measurement:The simplest application is the fluid level in an open tank. If the tank is open atmosphere, the high-pressure side of the level side will be vented to atmosphere. In this manner, the level transmitter acts as a simple pressure transmitter .The level transmitter can be calibrated to output 4 mA when the tank is at 0% level and 20 mA when the tank is at 100% level.

Closed Tank Level Measurement:Should the tank be closed and a gas or vapour exists on top of the liquid, the gas pressure must be compensated for. A change in the gas pressure will cause a change in transmitter output. Moreover, the pressure exerted by the gas phase may be so high that the hydrostatic pressure of the liquid column becomes insignificant. For example, the measured hydrostatic head in a CANDU boiler may be only three meters (30 kPa) or so, whereas the steam pressure is typically 5 MPa. Compensation can be achieved by applying the gas pressure to both the high and low-pressure sides of the level transmitter. This cover gas pressure is thus used as a back pressure or reference pressure on the LP side of the DP cell. One can also immediately see the need for the three-valve manifold to protect the DP cell against these pressures. The different arrangement of the sensing lines to the DP cell is indicated a typical closed tank application. The effect of the gas pressure is cancelled and only the pressure due to the hydrostatic head of the liquid is sensed. When the low-pressure impulse line is connected directly to the gas phase above the liquid level, it is called a dry leg.

PROCESS CONTROL IN BOILERS:Instrumentation and controls in a boiler plant encompass an enormous range of equipment from simple industrial plant to the complex in the large utility station.The boiler control system is the means by which the balance of energy & mass into and out of the boiler are achieved. Inputs are fuel, combustion air, atomizing air or steam &feed water. Of these, fuel is the major energy input. Combustion air is the major mass input, outputs are steam, flue gas, blow down, radiation & soot blowing.TYPES OF PROCESS CONTROL LOOPS Feedback Control Feed forward Control Feed forward-plus-Feedback Control Ratio Control Split Range Control Cascade Control

Feedback Control One of the simplest process control schemes. A feedback loop measures a process variable and sends the measurement to a controller for comparison to set point. If the process variable is not at set point, control action is taken to return the process variable to set point. The advantage of this control scheme is that it is simple using single transmitter. NOTE: This control scheme does not take into consideration any of the other variables in the process.

Feedback loop are commonly used in the process control industry. The advantage of a feedback loop is that directly controls the desired process variable. The disadvantage of feedback loops is that the process variable must leave set point for action to be taken.

Feedforward Control Feedforward loop is a control system that anticipates load disturbances and controls them before they can impact the process variable. For feedforward control to work, the user must have a mathematical understanding of how the manipulated variables will impact the process variable.

An advantage of feedforward control is that error is prevented, rather than corrected. However, it is difficult to account for all possible load disturbances in a system through feedforward control.In general, feedforward system should be used in case where the controlled variable has the potential of being a major load disturbance on the process variable ultimately being controlled.

Feedforward-plus-Feedback Control

Because of the difficulty of accounting for every possible load disturbance in a feed forward system, this system are often combined with feedback systems.Controller with summing functions are used in these combined systems to total the input from both the feed forward loop and the feedback loop, and send a unified signal to the final control element

Ratio ControlRatio control is used to ensure that two or more flows are kept at the same ratio even if the flows are changing Application: Blending two or more flows to produce a mixture with specified composition. Blending two or more flows to produce a mixture with specified physical properties Maintaining correct air and fuel mixture to combustion

Cascade ControlCascade Control uses the output of the primary controller to manipulate the set point of the secondary controller as if it were the final control element.

1. Why cascade control?

Allow faster secondary controller to handle disturbances in the secondary loop. Allow secondary controller to handle non-linear valve and other final control element problems. Allow operator to directly control secondary loop during certain modes of operation (such as startup).

2. Requirements for cascade control: Secondary loop process dynamics must be at least four times as fast as primary loop process dynamics. Secondary loop must have influence over the primary loop. Secondary loop must be measured and controllable. INSTRUMENT LISTIt is theoretically possible to operate a boiler with manual control. Time is needed for the boiler to respond to a correction and this lead to over correction with further upset to the boiler. An automatic controller once properly tuned will make the proper adjustment quickly to minimise upsets and will control the system more accurately and reliably. Instrumentation systems are provided for the boiler to achieve the following: 1. To measure the actual values of different parameters for which the boiler is designed. 2. Safe working range of the different parameters are maintained.3. To monitor one or more variables at a time and provide input for automatic control. 4. In case of operator failure to take remedial action for an upset condition, it protects the boiler by alarms and trippings. 5. To provide data on operating conditions before failure of the equipment for analysing the failure. WATER AND STEAM LEVEL INDICATOR PRESSURE TRANSMITTERS6. Instrument list consists of all the instruments like Transmitters, Switches, Gauges/Indicators used at power plant site. 7. This list contains the various information of instruments i.e. Tag no., service, type, set points, ranges, make, model no., scope etc. of all instruments.8. An instrument is device/sensor which is used for measurement.

TYPICAL FORMAT USED FOR INSTRUMENT LIST

INSTRUMENT LIST (For reference only):

INPUT-OUTPUT LIST1. The input-output list of boiler contains the list of instruments and equipments which are interfaced/ controlled from DCS.2. This list is used for DCS sizing.3. Two type of signals- Digital and Analog.4. Isolation valves are on-off valves and two command signals from DCS and two feedback signals to DCS.5. Control valves are analog valves and one command signal and one Position feedback signal.6. Switches send one digital signal to DCS.7. Transmitters send one analog signal.

INPUT/OUTPUT LIST (For reference only):

PROJECT DETAILS

Student Details

Student Name ADITYA KUMAR AGARWAL

Registration Number121705Section / Roll NoELEX/ I-04

Email Addressadiagrawal1994@gmail.comPhone No (M)+91-8796024891

Project Details

Project TitleBOILER PROCESS CONTROL AND INSTRUMENTATION

Project Duration5 WEEKSDate of reporting26/05/2014

Organisation Details

Organisation NameALSTOM INDIA LIMITED

Full postal address with pin codeEngineering Department, 3rd Floor, IHDP Building, Plot#7, Sector 127, Noida 201301, Uttar Pradesh, India.

Website addresshttp://www.alstom.com/india

Supervisor Details

Supervisor NameMr. KUNAL KUMAR

DesignationLead Engineer

Full contact address with pin codeEngineering Department, 3rd Floor, IHDP Building, Plot#7, Sector 127, Noida 201301, Uttar Pradesh, India.

Email addresskunal.kumar@power.alstom.comPhone No (M)+91-9990237510

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