The equipment and materials shall be designed and constructed in accordance with the ASME code section I 2001 ED A02 and Chinese Standards.

Size: px

Start display at page:

Download "The equipment and materials shall be designed and constructed in accordance with the ASME code section I 2001 ED A02 and Chinese Standards."

Damian Simpson
5 years ago
Views:

Steam Boiler Type S50-3.82/450 Traveling grate stoker 50t/h x 3.82 pa x 450 Degree C 1.

1 Steam Boiler Type S /450 Traveling grate stoker 50t/h x 3.82 pa x 450 Degree C 1. Basic use of the boiler The boiler can be used for industrial power generation, or thermal power station for enterprises in chemical, paper making or springing and weaving industries. 2. Codes and Standards The equipment and materials shall be designed and constructed in accordance with the ASE code section I 2001 ED A02 and Chinese Standards. 3. Specification of the boiler Rated capacity Rated steam pressure Rated steam temperature ax design capacity ax allowable working pressure Feedwater temperature Preheated air temperature Outlet gas temperature Blowdown percentage Boiler design efficiency : 50 t/h : 3.82 pa (554 Psig) : 450 Degree C (842 F) : 44 t/h (97003 Lb/h) : 4.35 pa (631 Psig) : 150 Degree C (302 F) : 136 Degree C (277 F) : 180 Degree C (356 F) : 2% : 82 % 4. Applicable fuel : Coal & Waste Wood Design fuel: Car = 53% Har=3.1 % Oar = 8% Nar=1.2% Sar=2% Aar=8.6% ar=24.1% Vdaf=46.21% Qar,net = KJ/Kg 5. Briefing of the Boiler Structure This boiler is middle pressure, single drum and natural circulating, it adopts II type arrangement, with stratified coal feeder and traveling stoker. Around the 1

inner side of furnace wall arranges the water-cooling tubes, and at the outlet of furnace, the rarified slag screen, Superheater is of convection type, vertically located in the horizontal pass.

Water spray attemperator is adopted to control the steam temperature, arranged between the two stages of superheater.

2 inner side of furnace wall arranges the water-cooling tubes, and at the outlet of furnace, the rarified slag screen, Superheater is of convection type, vertically located in the horizontal pass. In the direction of steam flow, the superheater consists of two stages, the high temperature section and the lower temperature one. Water spray attemperator is adopted to control the steam temperature, arranged between the two stages of superheater. Steel economizer and castiron air preheater are located in the tail-vertical well with single stage arrangement. Bottom-ash is removed by artin machine. 5.1 Steam drum and its inner equipment The inside diameter of the steam drum is 1500 mm with wall thickness of 46mm, length of its cylinder is 7.5 m. The cylinder is made of SA515Gr60 steel, welding nozzles to connect with water cooling tubes and down comers. For the checking convenience, Dia.420 manhole is opened on the ellipsoidal STEA DRU head. The drum is supported on two free supports placed on the cross beam of top boiler structure. The drum can freely expand to the left and right in the horizontal direction. Tube-sockets are prepared for safety valve, emergency drain, monometer, water level gauge and automatic control, etc. And there is recycling tube socket to economizer inlet header, to ensure safe and reliable function of the economizer. In order to ensure steam purity, 16 sets of cyclone separators with diameter of dia.290mm, is installed in the drum. The average load of each cyclone seperator is about 2.5 t/h. Top corrugated plates are uniformally distributed along the length of the drum cylinder for fine separating. Continuous drainage nozzle and chemical dosing pipe are also installed in or on the drum shell. 2

S=110mm and 8 pieces of downcomers of Dia.83x4. Its flow area rate of downcomer to riser is 0.335.

3 5.2 Furnace Around the inner side of the furnace wall, the water-cooled wall tubes of dia.60.3x3.2 have been closely arranged. The whole water-cooled system is divided by 6 circulation circuits, the front water-cooled wall is a separated one, it is composed of 46 pieces of water-cooled wall tubes whose tube spacing is S=110mm and 8 pieces of downcomers of Dia.83x4. Its flow area rate of downcomer to riser is The rear water-cooled wall is composed of 63 pieces of water cooled wall tube whose tube spacing is S=80 mm and 10 pieces of downcomers of dia.83x4. Its flow area rate of downcomers to risers is Side water-cooled walls are divided by two circuits respectively, the front and the rear. The side front circuit is composed of 9 pieces of watercooled wall tubes whose tube spacing is 140mm and 2 pieces of downcomers dia.83x4. Its flow area rate of downcomers to risers is Side rear circuit is composed of 15 pieces of water-cooled wall tubes whose tube spacing is 140mm and 3 pieces of downcomers dia.83x4. its flow area rate of downcomers to risers is BOILER TUBE EX. JAPAN The characteristics of each circulation circuits are as follows: Items Front water Rear water Both side water Cooled wall Cooled wall Front circuit Tube spacing Of Water cooled wall tube Pieces of Water-cooled Wall tube Pieces of Downcomer Flow area Rate 3 Cooled wall Rear circuit

$the lower part of the furnace. Behind the coal gate, ignition arch which is formed by refractory concrete has been arranged.$

4 In order to promote the gas mixing in the furnace and organize the radiation and blazing gas flowing, so as to implement the necessity of fuel ignition in time, a mixed arch has been arranged under the lower part of the furnace. Behind the coal gate, ignition arch which is formed by refractory concrete has been arranged. The refractory concrete is poured outside of the lower parts of the front and rear wall tube forms rear arch. The front arch covers 30% of the grate length at the height of 3.55m with inclination 20 degree C, the rear covers 44% of the grate length at the height of 1.148m, inclination 12 Degree. At the exit of the furnace, the rear water-cooled tubes are rarefied to be a slag screen composed of three rows with transverse pitch 240mm, longitudinal pitch 220mm. The whole water-cooled wall is wholly connected with drum and header by welding. Being considered to the expansion of water-cooled wall tube while heating, the fixed guiding apparatus is installed. Hanging measure has been used for the fount and rear lower header of the water-cooled wall. While install both sides of the water-cooled wall, two iron blocks with thickness 35mm should be bolstered under the clinker header. After finishing erection, the blocks should be removed, so as to make both sides of clinker headers can be stopped at the supports of boiler setting upon operation and heating. The lower header and clinker header are to be arranged with periodic blowdown stub. 5.3 Firing equipments The coal feed system drops the coal semi-automatically from the coal hopper and adjusts the thickness of coal layer by means of coal gate. In additional to it, the quantity of coal supply can be adjusted by changing the speed of grate to suit the needs of boiler load and coal quality. The stoker is composed of the following seven components: the lower slideway, grate support, driving shaft, driven shaft, grate chain, front damper and slag retainer. HEAVY DUTY HEAT RESISTANCE CHAIN GRATE The distance between driving shaft and driven shaft is 8500mm, the width of 4

5 grate is 5284mm. There are 13 prices of parallel chains, five bars are in a group which is clamped and fixed to the china with a clamp. In the rear part of the grate, the slag damping irons are used as a slag retainer. The air comes into the grate from two sides of the grate. Each side of the grate has four air compartments with dimension 400x500, and another two, 300x450, connects to its separated air pipe. The butterfly door in air pipe can be adjusted to control air pressure in air compartment. Ash discharge apparatus in air compartment adopts butterfly ash door. A contact structure is adopted for side seal between both sides of chain and frame, it can prevent coal from leaking into both sides of grate. In the mean time, depend on the contact between coal layer of both sides and clinker header to avoid the external air leaking into the furnace. In order to ensure stable burning and make the output in accordance with the requirement, the air pressure under grate should be 1000 Pa. 5.4 Superheater and attemperator Superheater is a convection type, vertically located in the horizontal pass. In the direction of steam flow, the superheater consists of two stages, the HT superheater and the LT one. The former adopts continuous mixed flow, the latter adopts parallel mixed flow. The steam flow process of superheater is as follows: Steam drum --- steam cooled roof tube --- low temperature superheater --- water spray attemperator --- High temperature section of supereheater --outlet of outlet header of superheater Structure properties of superheater Items Tube diameter Transverse Pitch s Average Longitudinal Pitch Heating surface aterial Dia.38x4 Row Of Tube n 54 Low Temperatur e Section of Superheater High Temperatur e Section of Superheater SA210-A1 Dia.38x SA210-A1 SA213-T12 Water spray attemperator has been used for steam temperature control. The 5

6 attemperator is located between high temperature section and low temperature section of the superheater. The spray water is from the feedwater The scope of designed regulating temperature of superheater is 29.5 degree C, and the enthalpy drop is 72.5 KJ/Kg (17.3 kcal/kg) 6

5.5 Economizer Economizer is located in the tail-vertical well with single stage arrangement. It adopts steel tube, staggered and counter flow form. The tube is Dia.32x3.

7 5.5 Economizer Economizer is located in the tail-vertical well with single stage arrangement. It adopts steel tube, staggered and counter flow form. The tube is Dia.32x3.5mm, its steel grade is SA210-A1. The transverse pitch of tube is S1=80 mm, longitudinal pitch S2=60mm. The serpentine tube of economizer is parallel to rear wall of boiler in order to prevent tube from wearing, antiwear cover plates are installed. On outside surface of the first and second row tube of economizer. The economizer is divided by three tube groups. The distance between each tube group is 900mm. The height of first tube group is 1.14.\ The second and third are 1.14 respectively. A mixed header is located between the first tube group and second tube group, it can make the steam-water homogeneously mixed for each parallel tube. The boiling rate at the outlet of economizer is 10%. 5.6 Air preheater Air preheater is tubular type air preheater, two set, up and down arrangement. The cast-iron tube is inner threaded, with fin outside the surface. S1=148mm, S2=148mm. It is divided into left and right groups with double pass in air side. The air preheating temperature is136 Degree C, its exit gas temperature is 180 Degree C. CAST-IRON AIR PREHEATER In order to ensure the free expansion of the air preheating tube, expansion joint been installed at the upper tube plate. 5.7 The undergrate air and the overfire air The hot air from air preheater comes out from the middle air pass, flowing past the side passes and into the compartment under the grate, and then it crosses the coal layer and into the furnace. To make sure that the air pressure is uniformly distributed on the grate 7

8 surface, dampers be installed for the three middle air compartment. To strengthen the burning of the floating coal particle, overfire air conduct is designed on front and back arch of the furnace wall. The overfire air has been got from the undergrate air conduct, with a pressure of 8000 pa, occupying 20% of the total air flow. 5.8 Steel structure, platform, ladder and kinds of door. This boiler adopts top-supported structure composed of steel columns and beams. The steel structure is designed in accordance with outdoor arrangement, seismic area with 7 Degree C scale and second sort of erection field. Boiler proper and its setting are supported on the steel structure and the steel columns are seated on the foundation of operation floor. Platforms, ladders, inspection doors and explosion vents are located around the whole boiler adequately, so as to operate and maintain boiler convently. LIFTING DRU 5.9 Ash removal equipment Bottom ash is removed by the artin machine, with the ability of disposing of ash, 3000 kg each hour Furnace The two sides are heavy-walled type, supported by the backstay, which transfers the strength to the foundation. The front and back furnace wall, as well as the tail-vertical well is a light type, supported by the bracked and transfers the load to the beam Setting, casing and soot blowing equipment The boiler adopts light weight boiler setting with frame type outer casing, it has good tightness, Before and behind each tube group of economizer, the parts used for installing stationary rotary soot blower are arranged. Steam is used as blowing medium Valves and pipes 8

9 All piping, valves and fittings required for complete operation of steam boiler shall be furnished with necessary hangers and supports. All piping shall be designed to permit free expansion for steam boiler moving. For safety from the corrosion, all pipes shall be insulated with cylindrically moulded insulation material and jacketing, except for the exhaust pipe of safety valve. The exhaust pipe of safety valve and sampling piping shall be insulated with mat cloth. Silencers shall be provided for boiler safety valves. 6. Outside dimension of boiler Elevation of steam drum center line Elevation of boiler s operation floor Elevation of boiler s highest point Width of boiler - Center distance between left and right side columns - aximum width (including platform) Depth of boiler - Center distance between front and rear column (Z to Z) - aximum width (including platform) p a p a Steam and water pressure drop Pressure drop of superheater Water pressure drop of economizer

10 8. Structure properties of heating surface Item Water-cooled wall In furnace Slag screen High temperature Section superheater Low temperature Section superheater Economizer Air preheater Tube diameter Dia.60.3x3.2 Pitch (mm) S2 Side wall 140 Heating surface m Dia.60.3x3.2 Dia.38x4 S1 Front wall 110, Rear wall Dia.38x Dia.32x3.5 Inner diameter Gas and a flow and their pressure drop Flue gas pressure drop of boiler Pa 1656 Air pressure drop of boiler Pa 3268 Flue gas quantity of boiler 3/h Air quantity of boiler 3/h Summary of temperature calculation of superheater tube surface: A point: The highest temperature of gas, (SA213-T12) strength permitte3d metal temperature =494 degree C <=649 Degree C (1200 F) B point: The highest temperatur4e of steam, (SA213-T12) strength permitted metal temperature = degree C <=649 Degree C (1200 F) C point: Bottom of the carbon steel, (SA210-A1) strength permitted metal temperature = <=538 degree C (1000 F) 10

11 Q K (kcal/m3hc) W/m2C (kcal/kg) KJ/kg 668 c t C T /s C T Wn C n /s 2 H High temperature Superheater Furnace Screen Slag Superheater Low temperature Economizer Preheater Air Wr Unit Symbol 10. Summarizing of thermal performance data:

12 12 Heating surface Of flue gas Outlet temperature Heating medium Inlet temperature of Flue gas Average velocity of Heating medium Average velocity of difference Average of temperature transfer Coefficient of heat Heat absorption Heating medium Outlet temperature of Nomenclature No Adiabatic combustion temperature = 1596 degree C, enthalpy drop=72.5 kj/kg Fuel consumption rate = 3826 kg/h (coal) & 8624 kg/h (waste wood); eff = 82%

Boiler Basics. Design and operation

Boiler Basics. Design and operation Boiler Basics Design and operation A boiler is an enclosed vessel that provides a means for combustion heat to be transferred into water until it becomes heated water or steam. The hot water or steam under