Desuperheaters Fixed Nozzle, Minicooler Design and Variable Nozzle

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1 Desuperheaters Fixed Nozzle, Minicooler Design and Variable Nozzle Dynamic Temperature Control for your Entire System Energy Conservation Environment Process Efficiency Forbes Marshall Forbes Marshall Arca Forbes Marshall Codel J N Marshall Krohne Marshall Spirax Marshall Forbes Vyncke

2 For over six decades, Forbes Marshall has been building steam engineering and control instrumentation solutions that work for process industry. Today we have evolved into a leader in process efficiency and energy conservation through technology tie-ups and focused investments in manufacturing and research. Our joint ventures with the world s leading names enable us to deliver quality solutions in 1 countries. Forbes Marshall is probably the only company in the world to have extensive expertise in both steam and control instrumentation. The dual expertise has allowed us to engineer industry specific systems that focus on energy efficiency and utilities management for sectors as diverse as textiles, food processing, paper, power and chemicals. Our teams are peopled by some of the nest engineers in the land. These highly trained professionals have developed innovative solutions and saved millions of rupees in process costs for our clients. Our business practices and processes have combined into a singular philosophy of being trusted partners who provide innovative solutions. It s a philosophy we are proud to live up to. For decades, we have partnered with some of the best names in the control instrumentation industry such as Arca, Codel, Krohne and Shinkawa, to develop, design and supply innovative solutions for measurement and monitoring of process parameters. With a combination of specialist knowledge and the latest technology, we provide products and solutions to achieve optimum efficiency. Our products are a unique combination of hardware and software that make them reliable and accurate. Forbes Marshall ranks amongst the world's leading suppliers of steam desuperheaters. We specialize in designing and manufacturing such equipment for power, process and co-generation plants. Forbes Marshall has supplied more than 5000 desuperheaters since Steam Desuperheating The most practical way of reducing the superheat value of steam is by the direct addition of water. To achieve temperature stability of the conditioned steam and prevent thermal shock in downstream pipes, cooling water must be atomized. It is also necessary to have a correct mix of superheated steam and cooling water. Fixed Nozzle Desuperheater - FND Water in Water Flange Steam Flange Nozzles Typical FND Standard Nozzle Kv s Sr. Kv per Nozzle Features Single nozzle Kv as low as m³ / hr and as high as 1.6 m³ / hr Number of nozzles limited only by pipeline diameter For use on all pipe sizes 6" and above Ideal for use in conjunction with water control valve and control system Turndown ratio upto :1 (depending on water quality) Notes Minimum pipe size required for installation of FND is150mm 3 11 AIR SUPPLY AIR SUPPLY WATER Water pressure should be minimum 7 bar (100 psig) more than the steam pressure Maximum recommended pressure difference between steam and water is 5 bar (653 psig). If it exceeds 5 bar (653 psig) then install pressure control valve in waterline to reduce water pressure within limits 1 8 STUB WITH SORF FLANGES (LOOSE SUPPLY) Spray water should be very clean (equivalent to boiler feedwater) Turndown ratio upto :1 OUTLET Total Desuperheating system along with control loop

3 Bill of Materials Sr. DESCRIPTION Sr. DESCRIPTION 1 DIAL THERMOMETER 7 PID CONTROLLER 2 DIAL THERMOMETER 8 SPRAY NOZZLE INSERT 3 NON-RETURN VALVE 9 TEMPERATURE SENSOR STOP VALVE 10 I / P CONVERTOR 5 WATER FLOW CONTROL VALVE 11 PIPE WORK 6 STRAINER Typical Sizes Steam side flange: and water side flange 1 / 1 ½ OR Steam side flange: 6 and water side flange 2 Pressure rating: upto ANSI #2500 Advantages Custom made for any size, standard or range Simple installation Can be used for higher pipe sizes and low steam pressure No moving parts Minicooler Desuperheater (MCD) Standard Nozzle Kv s Sr. Kv per Nozzle This is a unique device for specific applications like the Ejector / Gland Sealing Steam where the cooling water injection quantity is too low. This simple design involves fixed nozzle and cools the Steam by injecting a little water in the zone where steam has highest turbulence AIR SUPPLY AIR SUPPLY WATER 7 2 OUTLET Bill of Materials Sr. DESCRIPTION 1 DIAL THERMOMETER 2 DIAL THERMOMETER 3 NON-RETURN VALVE STOP VALVE 5 WATER CONTROL VALVE 6 STRAINER 7 TEMPERATURE CONTROLLER 8 MINI COOLER DESUPERHEATER 9 PIPELINE 10 TEMPERATURE SENSOR Notes For use with pipe sizes 1 to Single nozzle Kv as low as and as high as 1.6 Ideal for use with Forbes Marshall make water control valve and control system Turndown ratio upto 1: 11 I / P CONVERTOR 12 PIPE WORK Spray water should be very clean (equivalent to boiler feedwater) Advantages Instantaneous water mixing Less straight length requirement Absence of moving parts avoids possibility of choking

4 Variable Nozzle Desuperheater - VND Forbes Marshall has incorporated the latest technology in the spray nozzle design. The high quality surface finish minimises frictional losses, thereby ensuring that the total pressure difference between water and steam is available for atomisation of water. The nozzle assembly consists of three components: A) Spray head B) Nozzle C) Nozzle cap Each nozzle assembly is served by individual feed holes in the spray cylinder. Water enters the chamber through these openings. The relatively large volume of this chamber ensures that water is proportioned evenly through each orifice. The pressure drop across this spray cylinder head results in an increase in the fluid velocity. Water is subsequently rotated in the nozzle chamber before being emitted through the central hole. The combination of splitting the feed flow, increasing velocity and rotating effect ensures that water is injected into the system in a ne symmetrical hollow cone spray. The nozzles are finally assembled with the spray cylinder and are sealed. The Variable Nozzle Desuperheater may be equipped with a variety of spray heads. The uniform threading accepts spray cylinder heads with a wide range of Kv values. Standard configurations are with either 6 or 9 equally sized spray nozzles. Special combinations are available to suit customers requirements. This feature enables the VND to be customised for specific system requirement. A) Spray head B) Nozzle C) Nozzle cap Special Kv Values for Variable Nozzle Desuperheater SP3 Spray water must be injected in the direction of the Steam flow. To facilitate installation of the water supply line, one of the following four positions have to be indicated before ordering: SP3 - Along direction of flow SP6 - Transverse right to direction of flow SP9 - Opposite to direction of flow SP12 - Transverse left to direction of flow The commonly available Kv's are... VND Standard Capacity Range NOZZLE POSITIONS SP6 6A Kv = 0,065 9A Kv = 0,097 6B Kv = 0,137 9B Kv = 0,205 6C Kv = 0,263 9C Kv = 0,395 6D Kv = 0,505 9D Kv = 0,758 6Dx Kv = 1,000 9Dx Kv = 1,500 6E Kv = 1,60 9E Kv = 2,60 6F Kv = 2,50 9F Kv = 3,680 6G Kv = 5,200 9G Kv = 7,800 FLOW 6H Kv = 8,100 9H Kv = 12,150 6K Kv = 11,570 9K Kv = 17,0 SP9 SP12 A 0.03 B C D Dx D+2E+3G A+2C+1D+2E+3G A+3C+3DX A+2C+2DX C+1D+1DX+3F A+2C+1DX+2F+1H.895 1A+2B+2C+2D A+2B+1C+2D+1DX+2E B+3D+3E B+3D+1E+2F B+3DX+3G D+3F+3G.081 3DX+3F+3G.350 3D+3E+3G DX+3F+3H A+3B+3D A+2C+1DX+2F+3H B+2D+2E A+2B+3D+3F A+3D+3DX Other mixed nozzle combinations available on request

5 Features Available in 6 and 9 nozzle design Compatible with both pneumatic and electric actuators ACTUATOR AIR TO OPEN Highlights Design as per ANSI B 16.3 Graphite packing provided for optimal sealing with stem Suitable to fit a variety of yokes. (ideal with - Forbes Marshall make pneumatic diaphragm actuator) Fabricated body - available in Carbon Steel / Alloy Steel / Stainless Steel (other materials available on request) AIR FILTER AND REGULATOR 1/" NPT(F) POSITIONER 10 9 WATER Stem - ground, hardened and roller burnished to a fine finish for optimum performance 19 8 Ensures back-seat sealing due to fine machining and lapping of the seat after welding 7 High performance spray head assembly. Gives fine atomisation of spray water 6 X Typical Sizes For Model 38: Steam Side Flange: 3 Water Side Flange: 1, 1 ½ Typical VND Detail X For Model 8: Steam Side Flange: Water Side Flange: 1, 1 ½, 2 Pressure Rating: Upto ANSI #2500 Available Forbes Marshall Pneumatic Actuators For Mounting A. 'A' To 'Dx' Nozzles: UIII-60 n/v B. 'E' To 'K' Nozzles: UV-100 n/v Rangeability For 6 Nozzle Head: 1:18 For 9 Nozzle Head: 1:27 For Mixed Nozzle Head: More Than 1:27 (as Per Customer's Specifications). Sr. DESCRIPTION Sr. DESCRIPTION 01 SPRAY CYLINDER 11 NUT 02 NOZZLE ASSY. 12 PACKING SET 03 PISTON RING (3) 13 STUD 0 PISTON 1 GLAND 05 FASTENER RING 15 PLATE 06 SEAT 16 NAME PLATE 07 STEM 17 NUT 08 BODY 18 SECURING WASHER 09 WATER FLANGE 18 SECURING WASHER 10 SPACER Bill of Materials Sr. DESCRIPTION AIR SUPPLY 5 6 WATER Schematic Diagram 1 DIAL THERMOMETER 2 DIAL THERMOMETER 3 TEMPERATURE SENSOR PID CONTROLLER 5 I / P CONVERTOR 6 AIR FILTER and REGULATOR OUTLET Total Desuperheating system along with control loop

6 Notes Maximum recommended steam pipe size is 1200mm Minimum pipe size required for installation of VND is 150mm VND can be fitted in 100mm pipe size for nozzle upto Dx Water pressure should be minimum 5 bar more than the steam pressure Maximum recommended pressure difference between steam and water is 5 bar. If it exceeds 5 bar then install pressure control valve in waterline to reduce water pressure within limit Spray water should be very clean (equivalent to boiler feedwater) Required Sizing Parameters Steam Data Inlet Pressure Bar(g) Water Data Inlet Pressure Bar(g) Inlet Temperature C Inlet Temperature C Outlet Temperature C Steam flow (Inlet) kg/hr (Min/Nor/Max) General Pipe Size mm Pipe Schedule Turndown Ratio Water Flange Orientation: SP3 / SP6 / SP9 / SP12 (for detail refer to figure below) Model 38 with a maximum water flow capacity of 25 m³ / hr in continuous service Model 8 with a maximum water flow capacity of 50 m³ / hr in continuous service Governing Formula for Desuperheater Mw = Mst x (h1 -h2 ) (h2- hw) Advantages Custom designed for any size, standard or range Simple installation VND ensures a fine conical spray that evaporates almost instantaneously, avoiding pipe impingement Eliminates need of a separate coolant valve More turndown ratio possible Large desuperheating range because of number of available nozzles where Mw = Water Injection mass in kg/hr Mst = Inlet Steam Mass in kg/hr h1 = Enthalpy of Inlet Steam in Kcal/kg h2 = Enthalpy of outlet steam in Kcal/kg hw = Enthalpy of injection Water in Kcal/kg Good engineering practices for efficient Desuperheating Minimum inlet velocity should be 15 meters / sec for FND and 7 meters / sec for VND Applications Turbine Bypass Turbine Exhaust Turbine Bleed Steam Auxillary Steam Process Steam Attemperator Pressure Reducing Valve Outlet Steam Boiler Superheaters Boiler Re-heaters Minimum straight length downstream beyond the Desuperheater should be meters Optimum distance between water injection point to the temperature sensor mounted downstream should be 10 meters It is necessary to keep the steam flow rates (for max. and min conditions) as practical as possible. Else the turndown ratio increases unnecessarily which necessitates the selection and use of a combination of nozzles in the same spray cylinder Installation of a strainer with a mesh size of approximately 100 ì in the water supply line to prevent the nozzles from clogging is essential

7 System Comparison Conventional FND Conventional injection water systems consist of: Fixed size spray nozzle Control valve Steam pipe section The water injection quantity is regulated by the control valve. As a consequence of this ow, regulating the downstream water pressure P2 varies as a function of the valve plug position. At reduced capacity, the control valve starts to throttle reducing P2 and hence the available water to steam pressure difference resulting in larger droplet size and poor atomisation. The water evaporation Variable Nozzle Desuperheater valve regulates the amount of injection water by varying the number of injection nozzles. This enables the water pressure to remain constant, independently of the number of injection nozzles in operation. This results in an excellent and near uniform spray quality over the entire operating range. Control of nozzle opening is achieved by the positioning of a piston which is operated directly by an actuator mounted onto the valve. Through this simple design no separate water control valve is necessary. rate slows down and temperature control becomes troublesome. This typical system problem becomes compounded as nozzles and valves are usually sized for the design capacity but normally operate significantly below these design conditions. This oversizing results in a partially open control valve even at normal operating conditions. With reducing load, downstream water pressure P2 decays rapidly resulting in larger droplet size. Conventional systems therefore will work satisfactorily only at relatively steady load conditions.

8 Forbes Marshall Pvt. Ltd. A-3/35, MIDC, Industrial Estate, H Block, Pimpri, Pune India. Tel.: 91(0) Fax: 91(0) vmktg@forbesmarshall.com Domestic: Ahmedabad, Alibag, Bangalore, Bhopal / Indore, Chandigarh, Chennai, Coimbatore, Delhi, Hyderabad, Jamshedpur, Kolkata, Mumbai, Nagpur, Navi Mumbai, Surat, Trichy, Vadodara, Visakhapatanam International Operations: exp@forbesmarshall.com Bangladesh, Canada, Egypt, Indonesia, Iran, Kenya, Malaysia, Nepal, Sri Lanka, Thailand, U.A.E. (Instrumentation) (Boilers & Boiler Accessories)USA,