SPECIFICATIONS for STEAM AND WATER ANALYSIS SYSTEM (SWAS)
1.01.00 General Requirements
1.01.01 Steam and Water Analysis System (SWAS) shall be furnished for continuous monitoring and control of water and steam purity in the plant cycle and at other important points as specified in this specification.
1.01.02 The sampling system shall obtain samples from steam and water system, which shall be adequately conditioned and fed to analyzers for continuous analysis and provide parallel facility for grab sampling as specified.
The analyzer outputs shall be used for providing -
a) Continuous monitoring of various parameters using indicator with an isolated analog outputs of 4-20mA, DC for each parameter for monitoring in plant monitoring system.
b) RS-485 / Profibus output for diagnostics
c) Alarm for all significant parameters measurements, which exceed their permissible limits including those of sample conditioning system in the form of potential free contacts. The visual annunciation will be taken care of in main control room. The alarm outputs should be terminated on the terminal blocks provided in the junction box within the analyzer panel.
1.01.03 The offered system shall be complete with sample conditioning devices and monitoring instruments (for temperature, pressure, flow & sample) and analyzers as well as all required accessories to provide a complete and integrated sampling and analysis system as per the intent and requirements of this specification. Sample line diagrams shall be used to implement the design at system level. Vendor should be able to demonstrate the type test of sample conditioning system in his factory. As analyzer is the most important ingredient of SWAS, vendor should be able to provide proofs of collaboration with internationally recognized analyzer manufacturer from Europe or USA. Vendor to also furnish performance letters from reputed power companies like NTPC/BHEL. Non-compliance to any of these criteria automatically disqualifies the vendor.
1.01.04 All piping, tubing, fittings and other sample wetted parts in the sampling and analyzing system shall be of type 316 stainless steel, except for those within the analyzers, which will be as furnished by the manufacturer.
1.01.05 All SWAS system components and accessories shall be from the latest proven product range of qualified manufacturers. The SWAS package including analyzers should be supplied by one approved systems vendor, who can supply the complete equipment. The vendor should have in-house capabilities to manufacture the package, such as TIG welding, NDT procedures, Hydrostatic testing upto 600 Bar, facilities for assembly & testing etc. The welding inside the SWAS panels should be done by welders approved for high pressure welding. The welders should be IBR / ASTM approved.
1.01.06 Vendor to be able to provide proven track record in “Coal based thermal power stations”. For this, vendor must provide a list of SWAS supplies that are made under his own brand and also manufactured in his own manufacturing plant. These supplies should have been made to Thermal Power Stations, which should be good enough to qualify him as an experienced vendor for SWAS. Vendor should have supplied such SWAS packages to minimum 10 Thermal power plants OR 20 Combined Cycle power plants Non compliance to this criteria automatically disqualifies the vendor.
1.01.07 All sample piping from primary root valves on process fluid lines/equipment to bulk head of SWAS panel will be arranged by the buyer. The cooling water & necessary electrical supply upto the SWAS package will be arranged by the buyer.
1.02.00 Sample Conditioning System
1.02.01 General
1) Sample conditioning system shall be designed and constructed to receive and condition all samples (listed in the enclosed Sample Stream Specification) as required by the respective analyzers connected to the sample streams. This will include conditioning components as specified herein and shall cover the following:
a) Primary Sample cooling using Auxillary cooling water (with field mounted sample coolers)
b) Sample filtering
c) Final Secondary sample cooling, using individual secondary coolers for each stream
d) Pressure reduction and control as required. The pressure regulating device should be capable of regulating the output pressure, irrespective of the upstream fluctuations, even at low flow or low pressure conditions. Since pressure regulation is an important aspect of sample conditioning for the reliable & accurate results from analyzers, pressure reducing devices are not acceptable
e) Flow rate control with the help of glass tube purge rotameter with a built-in regulating valve. A back pressure regulator is essential to ensure stable, regulated & priority sample flow condition to the analyzers
f) Other equipment as required by individual analyzers or specified herein
2) Sample line to analyzer elements shall incorporate an anti-siphon design to prevent possibility of running dry because of a broken or plugged sample line.
The sample conditioning system shall provide samples at 25 Deg.C within tolerance of + 1 Deg.C, at a pressure of about 2 kg/cm2 and at flow rates as required by individual analyzers/streams. Vendor should consider chiller package to achieve the same. The chiller should be manufactured by the vendor. Non compliance to this criterion automatically disqualifies the vendor. The chiller should meet the specifications given below :
1.02.01.01 Two Stage Sample Cooling using individual primary and secondary coolers:
a. Primary Sample Cooling: The sample temperature of approx.45oC can be achieved in first stage of cooling in the sampling system by using cooling water provided by the Employer from his plant. Primary cooling will be carried out in a field using primary sample coolers design to withstand High pressure and high temperature sample at supercritical conditions. (Refer 1.02.03 for Sample cooler specifications)
b. Secondary Sample Cooling: The use of chilled water will be for cooling each sample stream with the required flow rate shall from 45 DegC to 25DegC ± 1DegC. The chiller flow capacity shall be calculated assuming fouling factor of 0.2 on both sides of the coils. Capacity shall be approved by the Employer.The water used for re-circulation in the chilled water circuit will be condensate quality water. This water will be supplied by the Employer. The make-up water also will be provided by the Employer. The temperature of chilled water shall be 20DegC. Refrigeration unit (chillers) to be furnished by the bidder. Coolers used in the chilled water circuit shall be submerged helical coil type and tube design with removable shell as per GDCD standard 163 (Refer 1.02.03 for Sample cooler specifications) Non compliance to this criterion automatically disqualifies the vendor. Sample tube shall be seamless type. Sample cooler of coil shape (tube-in-tube) design is not acceptable for the problems associated with maintenance of such coolers. Secondary cooler must be provided with relief valve in addition to relief valve at cooling water headers. This is important to take care of safety of personnel with respect to issues associated with coil rupture or failure.
The chiller system details are given below :
c. Chiller System
i) Chiller system shall have 2 x 100% of capacity (redundancy applicable for moving parts only). Water cooled chillers will be used for each unit and shall be sized to ensure sample steam temperature of 25oC ± 1oC, when all relevant streams are running at maximum flow rate and maximum temperature. It shall have 25% spare capacity for future samples.
ii) The compressor shall be readily accessible for service and shall include low noise hermetically sealed motors. Compressor assembly shall also include crank case heaters, suction and discharge valves, forced feed lubrication system and an integrated motor protection system along with the necessary instruments.
iii) The condenser shall be water-cooled, designed and constructed in accordance with the ASME code for unfired pressure vessels. A condenser water regulating valve shall be included. The cooling water shall be supplied from Employer’s cooling water system at a maximum temperature of 40oC and maximum flow rate as required by the chiller system. All the pipes, fittings & valves required between chiller package & SWAS shall be in Vendor’s scope. All other piping / tubing / electricals etc. will be in Employer’s scope
iv) Chiller shall be of the direct expansion type.
v) Chiller package being one of the important & valuable element of SWAS package, it should be manufactured by the SWAS system supplier only. This is mandatory as the Chiller packages outsourced are susceptible to failures due to lesser control on quality. Non compliance to this criterion automatically disqualifies the vendor.
vi) The SWAS manufacturer should have sufficient experience in manufacturing the chiller packages suitable for Thermal power plant conditions & should have supplied these chiller packages along with SWAS to minimum 3 Thermal power plants
vii) Refrigerant circuit shall be complete with a thermostatic expansion valve, liquid line solenoid valve, sight glasses, filter – dryer, refrigerant shut-off and charging valves.
viii) The flow system shall be designed to provide the required flow to secondary sample coolers.
ix) The chiller water pump shall be of the centrifugal type, close coupled, bronze fitted construction, complete with motor. Pump and motor shall be designed for continuous operation.
x) Vibration dampeners shall be provided matched for the packaged chiller and shall be mounted between the packaged chiller and the channel base.
xi) Cooling water and chilled water piping shall be provided with isolation valves.
xii) Necessary eye bolts should be provided for lifting purpose.
xiii) The Bidder shall provide detailed calculation for chiller capacity and other technical particulars like foundation details/mounting etc. with the proposal. These shall be subject to Employer’s approval.
xiv) A mimic showing chiller operation pictorially shall be provided on the front face of the chiller for easy understanding of operation
xv) The chiller system shall be provided with following items, in addition to any other instruments / equipments required for smooth, convenient operation of the system, which shall also be furnished by the Vendor.
a) Compressor
b) Chilled water pumps with suction and discharge pressure gauges.
c) Chilled water circulation pump suitable for continuous operation
d) Storage tank automatic water makeup with manual bypass facility.
e) Tank temperature indicator.
f) Storage tank level gauge & level guard.
g) Drain and overflow connection for tank.
h) Condenser unit
i) Chilling unit (Evaporator)
j) Expansion valve
k) Antifreeze circuit
l) HP/LP cut out with disconnection facility
m) Electrical control panel & Mimic
n) Necessary nameplates
xvi) Redundancy (2x100%) capacity is required for all moving parts mentioned below :
a) Compressor
b) Chilled water pumps with suction & discharge pressure gauges
c) Chilled water recirculation pumps
Specifications for Sample Handling System Components:
1.02.02 Sample Isolation valves & Blowdown valves :
A) For High pressure & High Temperature Lines before primary sample cooling:
All sample isolation valves & blowdown valves for sample pressures of 40 Kg/Cm2 &/or above 200 Deg.C. above must be “Globe type with back seat arrangement”, integral stellited seat and welded body/bonnet design. These Valves must be IBR approved & selected as per Valves Pressure Class- ANSI B16.34-1996, Material must be suitable to withstand this high pressure and high temperature. Preformed pure graphite rings should be used as gland packing material (graphoil ropes are not acceptable). The plug & spindle should be single piece & of non-rotating type. The plug should be guided throughout its travel. The spindle should be roller burnished to ensure leakage free performance. For blow down service, valve should be provided with control cone such that the throttling area gets separated from seating area, thus enhancing the life of the seat. Needle valves / Instrument valves are not acceptable. Dilution of these specifications will disqualify the vendor.
B) For Low pressure & Low Temperature Lines before secondary cooling:
For Low Pressure (i.e. below 40 Kg/Cm2) and temperature application. Needle valves are acceptable suitable for these application. Material for these valve must be SS316.
1.02.03 Sample Cooler (Both Primary and secondary Sample coolers)
All samples having a temperature in excess of 45°C shall be cooled by use of sample cooler. The design of all sample coolers that handle live steam shall be validated by external authority in manufacturer’s country
The sample cooler shall use general service water (softened water) as cooling water. This cooling water is tapped from general service water whose temperature may vary from 20 DegC to 36 DegC. Cooling water pressure differential available for SWAS will be minimum 1.5 bars. The chloride content in cooling water will be less than 35ppm. A maximum cooling water temperature of 36°C shall be considered for design of sample cooling system. Capacity of cooler shall be adequate to cool the sample within 5 deg.C of cooling water inlet temperature considering the combined flow of each analyzer connected to sample cooler and one manual grab sample at flow rate of 20 Liters/Hour. Cooler capacity calculations shall be submitted by the bidder.
Each sample cooler must be protected by a built-in shell relief valve. The sample coil should not be welded to any part of the cooler. There should be a drain plug provided at the bottom of each cooler. Each cooler should be protected with a check valve on the coolant outlet of the cooler and a common relief valve on the cooling water header.
Sample cooler shall be of submerged helical coil type of shell and tube design with removable shell. The sample tube shall be of seamless with no welds and other joint inside the cooling jacket. Unions shall be provided to facilitate removal of coils. All tubing and fittings & other components wetted by the sample shall be constructed of type 316 stainless steel. Cooler design shall conform to requirements of GDCD codes. The cooler design should confirm to ASTM Secion VIII, Division 1 for Unfired Pressure Vessels
The design and thermodynamic performance of the coolers should be certified by a reputed external authority in manufacturer’s country to ensure performance to design specifications. Non compliance to this criterion automatically disqualifies the vendor.
Sample cooler model number & catalogue should be submitted & certified by the corporate office of the manufacturer. Sample coolers sub-contracted from third parties are not acceptable. Supplier should be able to prove that the sample coolers are indeed manufactured in-house. Sample coolers must be designed to withstand Supercritical temperature and pressure (300 Kg/Cm2 @ 600 DegC). Sample cooler manufacturing facility should be ISO 9001 approved and should have a registered R&D facility. The manufacturing facility should be IBR approved for making such components. The finish of sample cooler should be uniform matt finish. The weld should be uniform all over. Weld quality is extremely important & coolers where weld is not uniform are liable for rejection. Non-compliance to any of these criteria automatically disqualifies the vendor.