Document Code: 1 (15) Issuing date: Status:

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1 Document Code: 1 (15) Project : MULTI FUEL CFB BOILER SIMULATOR Author: Approved: Language: HSK Document title: SYSTEM DESCRIPTION BOILER WATER SYSTEM Submitted for: Customer reference: Other information:

2 Document Code: 2 (15) TABLE OF CONTENTS 1 GENERAL DESIGN DATA General data Heating surfaces EQUIPMENT DATA Interconnection piping Furnace water walls Furnace headers Steam drum Other valves and equipments AUTOMATION AND INSTRUMENTATION OPERATION Start-up precheck Start-up Cold start Normal operation Shut down Operating Disturbances High or low steam drum water level Sudden loss of steam drum water Gradual loss of steam drum water level Emergency Shut Downs Steam drum water level cannot be maintained Sudden loss of steam drum water level Tube leakage Power failure CONNECTED SYSTEMS...15

3 Document Code: 3 (15) 1 GENERAL The boiler is a natural circulation boiler and the tubes are arranged so that as the water is evaporated to steam it is free to rise up into the drum. Unheated downcomer pipes take the water from the drum to the combustion chamber inlet headers. The combustion chamber wall tubes are heated by the flue gases and the water is partly evaporated to steam. In furnace is four peaces of evaporating wingwalls and the water is partly evaporated to steam. Water and steam rise through tubes and riser pipes back to the steam drum where the steam is separated from the water in cyclone separators and the water is returned to the circulating system. Note that feed water only replaces the evaporated steam and the amount of water circulating is much greater than the feed water flow. The steam drum is equipped with the following internals: feed water distribution pipe riser/downcomer tube baffle plates steam/water cyclone separators steam demisters continuous blow down pipe Feed water is distributed evenly throughout the steam drum via a perforated pipe. The downcomer tubes are separated from the riser tubes by baffle plates. Downcomer tubes transfer the feed water to the boiler circulation. The steam/water mixture, which is returned via the riser tubes to the drum, enters on the other side of the baffle plates. Water is separated from the steam in cyclone separators and water is thrown to the side and flows back into the circulation system. Before leaving the drum the steam passes through a final dryer, which is also a demister made of densely packed stainless steel wire mesh.

4 Document Code: 4 (15) 2 DESIGN DATA 2.1 General data Boiler type Water flow Foster Wheeler CFB Compact Boiler natural circulation High pressure side: Max. pressure (drum) bar(g) 202 Nominal pressure (main steam pipe) bar(g) 169 Steam generation (by peat) kg/s 113 Steam temperature (by peat) C 563 Low pressure / reheat side: Max. pressure (steam line cold) bar(g) 50 Nominal pressure (steam pipe cold) bar(g) 37 Nominal pressure (steam pipe hot) bar(g) 33 Steam generation (by peat) kg/s 98,5 Steam temperature (by peat) C Heating surfaces Width of the furnace m 17,11 Depth of the furnace m 5,50 Height of the furnace m 31,5 Evaporation surface in the furnace Furnace surfaces m Evaporative wing wall m 2 178

5 Document Code: 5 (15) 3 EQUIPMENT DATA 3.1 Interconnection piping Downcomers Material 15NiCuMoNb5 Size mm 323,9 x 22,2 Bottles Material 15NiCuMoNb5 Size mm 323,9 x 22,2 Distributors Material 15Mo3 Size mm 168,3 x 16,0 Riser pipes Material 15Mo3 Size mm 168,3 x 16,0 3.2 Furnace water walls The water circulation in the walls is designed to ensure that tubes exposed to the heat of the furnace are at all times adequately supplied with water and that steam pocketing is avoided. Material 15Mo3 / 16Mo3 Size mm 63,5 x 7,1 Spacing mm 88,0 Fins mm 24,5 x 6,0 All water walls are membranes welded with automatic machine so that the walls are forming a completely gas-tight structure. 3.3 Furnace headers Inlet headers Material 13CrMo44 Size mm 219,1 x 40,0 Outlet headers Material 13CrMo44 Size mm 219,1 x 40,0

6 Document Code: 6 (15) 3.4 Steam drum Material 15NiCuMoNb5 Drum length mm Wall thickness mm 110 Inside diameter mm 1896 Outside diameter mm 1676 Weight kg Max. pressure bar(g) 202 Nominal pressure bar(g) 187 The steam drum is equipped with cyclone separators and demisters in order to reduce the moisture content of the steam leaving the drum with a consequent reduction of the solids carry over. 3.5 Other valves and equipments Drum level sight glasses S1 HAD10 CL Mechanical: Manufacturer Electrical: Manufacturer Drum overflow valve Manufacturer Size DN 80 Actuator Aumatic Drum over flow shut-off valve Manufacturer KSB Size DN 80 Actuator Aumatic Continuous blow down shut-off valves Manufacturer KSB GL Size DN 50 S1 HAD10 AA102 S1 HAD10 AA101 S1 LCQ10 AA001/002

7 Document Code: 7 (15) Continuous blow down control valve Manufacturer Size DN 65 Actuator Aumatic Economiser drain valves Manufacturer KSB GL Size DN 32 S1 LCQ10 AA101 S1 LAB40 AA810/811 S1 HAC10 AA830/831 Boiler drain valves S1 HAD10 AA850/851/855/856/860/861/865/866 Manufacturer KSB GL Size DN 50 Boiler preservation pump Manufacturer Capacity Shut off valve before the pump Manufacturer Naval Ball valve Size DN 100 Shut off valves after the pump Manufacturer Naval Ball valve Size DN 25 S1 LFJ10 AP701 S1 LFJ10 AA001/002 S1 LFJ10 AA010/011

8 Document Code: 8 (15) 4 AUTOMATION AND INSTRUMENTATION In this section automation is explaned only basic level and more detailed descriptions can be found in Automation Descriptions. Drum level, control principles Feed water evaporated in the boiler is fed into the drum by feed water pumps. The steam drum level is controlled by a control valve located between the pumps and eco to ensure reliable operation of the control valve under every condition, pressure over the feed water flow control valve has to be maintained appropriate (typically 4 8 bar). This pressure is controlled by controlling the speed of feed water pump(s). 5 OPERATION 5.1 Start-up precheck Action by Control Room Operator and Auxiliary Operator Verify that: Feed water tank is filled up to normal level and tank is in operation (heated > 105 C) Feed water system has been prepared to take in operation. All check valves direction drum has been opened (f.w. pump, hp preheaters, f.w. flow control group) and equipment and measurements are operative/in operation. Local boiler drum water sight glasses and drum level indicator shows the same Make-up water quality is adequate and make-up system is operative Chemical dosing and sampling systems are available Boiler drum vent valves are open Boiler drain and blow down valves are Continuous blow down valves are open Feed water system & economiser drain valves are Separator drain valves are Superheater vent valves are open Start up isolation valve are open Start up valve % open, if boiler is pressureless. If boiler has a pressure, set start up valve(s) to position of a minimum steam flow required to cool superheaters. Feed-, boiler water & steam sampling valves are open

9 Document Code: 9 (15) Action by Auxiliary Operator Walk down the boiler to verify that: Boiler drum access doors are Combustion chamber doors are Drop leg doors are Separator doors are Air heater doors are Economiser doors are Convection pass doors are Superheater doors are Windbox and air canal doors are All fan access doors are DeSOx system doors are Check for any leaks before proceeding 5.2 Start-up Cold start This chapter provides detailed instructions to start-up a cold, empty boiler and bring it to full load output, maximum continuous rating (MCR). This section defines basic steps and should be used with your plant-specific operating procedures as established by the owner/operator. Action by Control Room Operator and Auxiliary Operator Start boiler feed water pump (See Standard Operating Procedure by manufacturer) Open boiler feed water pump discharge slowly Check minimum flow (minimum flow and balance water lines has to be free direction f.w. tank) Set feed water motor block and regulator bypass (DN200) valve in sequence-mode Set drum overflow valve in sequence-mode Monitor feed water tank level Check, that local boiler drum water sight glasses and -level indicator shows the same During boiler warm up, the bottom blow down and continuous blow down systems must be in service in case the boiler drum level goes too high. Faster help for drum level control, if needed, is especially the bottom blow down, but it must be remembered that one blow is allowed to do only seconds at the time. During boiler warm up, the feed water system must be in service to supply make up water as required (otherwise control to drum level will be lost). Open boiler and separator drain valves for 0,5 1 minute each every 30 minutes until boiler pressure reaches 5 15 bar. After 35 bar it is forbidden to blow from boiler bottom. Monitor boiler water chemistry continuously. Increase continuous blow down, if needed.

10 Document Code: 10 (15) When boiler pressure reaches bar, close the boiler drum vent valves. Superheater and main/reheat steam line vent valves should be gradually, and at the pressure of bar fully. Leave superheater drain valves partly open until boiler pressure reaches 8 12 bar, then close drains fully (when it can be ensured that steam is at least 20 C superheated). During pressure raising, the position of the start-up valve is kept open so much, that superheater temperatures will remain under max. See material temperature curve, temperature increase app. 70 ºC/h. After the start-up valves close, adjust main steam controller to match the turbine requirements, while increasing the boiler load Normal operation Monitor steam drum water level. Verify that remote and local steam drum water level indicators agrees the same. Adjust continuous blow down flow according to laboratory analyzes. According the sampling and laboratory analyses, check also chemical dosing (amounts). Check steam drum doors and external valves, fittings and connections for possible leaks Shut down Boiler load is reduced. The combustion with solid fuel is changed to oil combustion. Decrease the total firing load gradually so, that bed temperature curve of 100 C/h would not exceed. This means, that oil firing has be started easily straight after / same time, when solid fuel firing is stopped. If there is a risk that condition of a bed is not necessarily good, the oil firing should not start too hard, because otherwise it is possible to sinter the bed. When no more steam is needed, the burners are stopped. Close the main steam valve. Check the pressure of the boiler and open the start-up valve, if necessary. Close the start-up valve, when the pressure of the boiler does not rise. Do interlock tests, when you shut down the boiler. It is very good way to keep operators familiar with most important interlocks. Keep the drum water level at maximum, if you do not drain the boiler. If boiler is stopped for longer time, it is needed to remove the bed material from the grid. Boiler will maintain much longer the pressure, when bed exists (at the grid and Intrex ) and because of heat, it will be impossible to go inside of boiler. If boiler is stopped only for shorter period of time, the bed material is better to leave on boiler. In fact, if shut down will last less than 24 h, the fastest way to start up the boiler further on is to stop the boiler straight from solid fuel firing. When solid fuel is stopped, let fans run ~ 5 minutes to burn most of the rest solid fuel at the bed and stop all fans

11 Document Code: 11 (15) then. Bed temperature will remain over 700 C, and following start up of the boiler can be executed much faster using less oil. Procedures at the steam side as mentioned above.

12 Document Code: 12 (15) 5.3 Operating Disturbances High or low steam drum water level CAUTION! NEVER OPERATE (fire) BOILER WITHOUT A VISIBLE WATER LEVEL IN THE BOILER STEAM DRUM. Check for proper operation of all steam drum instruments. Check the proper valve positions of the gauge glass and blow once gauge glasses to ensure real water level. Verify proper level by comparing local and remote water level indications. Check for normal operation and line up of boiler feed pumps and associated piping. Check the drain valves from the feed water, HP Verify water level in feed water tank. Check for normal operation of all feed water control valves and line up of piping. Verify, that instrument air to all controllers is nominal pressure and free from moisture. Check normal operation of all steam flow and feed water flow transmitters. Verify valve line up. Check for evidence of a boiler tube failure during the boiler walk around. If a tube failure has occurred, follow procedures outlined in Foster Wheeler's "Emergency Operation" instructions supplied with your Operation and Maintenance Manual or your Operator Training Manual. Check blow down valves, particularly, if the boiler has been blown down recently. Verify, that drain piping after the last block valve is not hot indicating a leaking valve. Note, that high drum level can be a result from sudden pressure drop. This can be the case, when turbine by-pass, HP bypass or start up/safety valve opens accidentally and takes/let through suddenly more steam than boiler is producing Sudden loss of steam drum water When the cause is known and immediately correctable before the water level in the steam drum reaches the minimum allowable operating level, re-establish steam drum water level to it s normal operating value and continue boiler operation. When the cause is not known and the water level in the steam drum drops below the minimum allowable operating level (this situation could be the result of a tube failure), start an immediate shut down according to the emergency shut down section of this procedure (Chapter 5.4.).

13 Document Code: 13 (15) Gradual loss of steam drum water level Boiler steam drum water level indicator no longer shows water level: Initiate a boiler emergency shutdown When fire out is secured, put boiler feed water drum level control in Manual mode Reduce feed water flow to zero Do not feed water to boiler Allow the boiler to cool down and make a walk down before feeding water to the boiler Boiler steam drum water level indicator still shows water level NEVER OPERATE A BOILER WITHOUT A VISIBLE WATER LEVEL IN THE BOILER STEAM DRUM Put boiler feed water drum level control in Manual mode Reduce load gradually, while manually increasing feed water flow If the cause is known and can be rectified before the water level drops out of range of the drum level indicator, restore boiler drum water level to normal and continue operation Check for proper operation of all boiler steam drum instruments Check the trend in feed water flow, steam flow and boiler steam drum water level Blow down gage glasses Compare local and remote boiler steam drum water level indicators Check for evidence of a tube leak - if a tube leak is suspected, follow the EOP for boiler tube leak Check boiler feed water pumps for normal operation Verify adequate level in feed water tank Check blow down valve positions particularly, if boiler has been blown down recently If unable to maintain boiler steam drum water level, shut down the boiler 5.4 Emergency Shut Downs Steam drum water level cannot be maintained Remove the boiler from service immediately by following Normal Shut Down or Emergency Shut Down Procedures, as the situation dictates. All firing (of solid fuel or oil) must be immediately stopped. Remove bed material during this shut down as quickly as possible from the boiler.

14 Document Code: 14 (15) Sudden loss of steam drum water level NOTE: This procedure should also be followed on a loss of feed water supply. An automatic main fuel trip (MFT) will occur on low low steam drum water level. The primary air, secondary air and HP pressure air fans will stop. ID-fan will remain running at minimum speed. Cool the boiler to allow bed material removal and boiler inspection. Remove bed material as fast as possible by monitoring the bed ash and ash cooling water temperatures. CAUTION Wet bed material can solidify and could cause metal corrosion in the boiler and should be removed as quickly as possible Tube leakage If a major leak occurs - burst of a tube - during operation, the combustion chamber pressure may rise due to the increase in flow caused by the sudden evaporation to steam. Should such a burst occur the ID fan flow should be increased and fuel flow stopped. At the same time steps should be taken to reduce the boiler pressure immediately with the start-up (or turbine by-pass) valve. Feed water should be brought to the boiler so, that the boiler parts do not overheat and only stopped when the flue gas temperatures have dropped below 400 ºC. Keep the drum level at minimum. If the water level has been completely lost, do not bring cold feed water to a hot drum max. allowed difference ~ 50 ºC. Check the feed water temperature after economiser and compare it to drum temperatures (drum material temperatures remains long time, because of thickness, ~110 mm, of the drum casing). Secondary air flow can be reduced but not completely stopped, while there is still combustible material (particle and gas) in the flue gases. Primary air for fluidising should be stopped, if the leakage is big. This will stop the burning at once in the bed. Otherwise primary air for fluidising can be kept at minimum flow until all the remaining fuel in the bed has burnt completely, and it helps also to get the rest of the bed ash away from the grid. Remove bed material via the ash cooler, if the leakage is entering the bed. Check, that (small amounts of) unburned fuel will not start to burn at the ash conveyors causing a fire.

15 Document Code: 15 (15) For smaller leakages follow normal shut down procedures. Secondary air flow can be reduced but not completely stopped, while there is still combustible material in the gases. Primary air for fluidising can be kept at minimum flow until all the remaining fuel in the bed has burnt completely. Remove bed material via the ash cooler, if the leakage is entering the bed. Try to determine the approximate location of the leakage by walking round the boiler. An economiser leak may be detectable by sound or by an increase in make-up water requirements. Note, that water leaks can lead to erosion of adjacent tubes and may cause plugging of ash hoppers and air heaters. Steam leaks in superheaters can cause considerable damage to adjacent tubes due to steam cutting. Operator judgement must be used to assess the seriousness of the failure and to decide whether an emergency or normal shut down should be performed. Monitor the leakage rate and cooling down rate Power failure When a power failure occurs, the boiler shuts down. Most important devices to control the boiler to secured situation are secured by the emergency electricity supply. 6 CONNECTED SYSTEMS Feed water system S1 LA -MFB1001 HP preheater system S1 LAD_-MFB1001 Superheaters S1 HAH_-MFB0001 Reheaters S1 HAJ_-MFB0001 Blow down system S1 HAN_-MFB0001 Drains and vents S1 HAN_-MFB0002 / 0003 Sootblowing system S1 HCB_-MFB0001 HP-steam system S1 LB -MFB1001 Sampling S1 QU -MFB1001 Chemical dosing S1 QC -MFB1001 Flue gas (side temperatures) S1 HN -MFB0001

Document Code: 1 (13) Issuing date: Status:

Document Code: 1 (13) Issuing date: Status: Document Code: 1 (13) Project : MULTI FUEL CFB BOILER SIMULATOR Author: Approved: Language: JJA Document title: SYSTEM DESCRIPTION REHEAT STEAM SYSTEM Submitted for: Customer reference: Other information: