Turb.sect8.Cond&Feed Heating 14Sept07

Medupi Power Station Employer’s Requirements Package No. 3 STG Contract No: 4600008582

Eskom

Employer’s Requirements

One Turbine Generator with auxiliary plant Section 8 – Condensate and Feed Heating System

8.1 SCOPE OF SUPPLY ....................................................................................................................2 8.2 CONDENSATE SYSTEM .............................................................................................................2 8.3 L.P. FEED SYSTEM...................................................................................................................3 8.4 H.P. FEED SYSTEM ..................................................................................................................3 8.5 GENERAL REQUIREMENTS FOR PRESSURE VESSELS ................................................................4 8.6 CONDENSATE AND FEEDHEATING SYSTEM ..............................................................................5

8.6.1 Safety and relief Valves ......................................................................................................7 8.6.2 Gland Steam Condenser .....................................................................................................7 8.6.3 Condensate Polishing Plant ...............................................................................................7 8.6.4 LP Heaters, Drain Heaters, Drain Coolers and Gland Steam Condenser .........................7

8.7 LP HEATER DRAINS TANK AND PUMP.......................................................................................8 8.8 DEAERATOR AND DEAERATOR STORAGE TANKS.....................................................................8

8.8.1 Deaerator ...........................................................................................................................8 8.8.2 Deaerator Storage Tank .....................................................................................................8 8.8.3 Fittings, Accessories and Connections ...............................................................................9

8.9 AUXILIARY STEAM SUPPLY .....................................................................................................9 8.9.1 Auxiliary Steam Manifold .................................................................................................10

8.10 DEAERATOR AND ACCCT CONTROL SYSTEM.......................................................................10 8.11 HIGH PRESSURE HEATERS .....................................................................................................11 8.12 NOT USED..............................................................................................................................12 8.13 AIR COOLED CONDENSER CONDENSATE TANK (ACCCT) ......................................................12 8.14 TURBINE CONDENSATE TANK (TCT)......................................................................................13 8.15 AIR EXTRACTION EQUIPMENT ................................................................................................14

8.15.1 Steam Jet Air Ejectors for Holding Vacuum ................................................................14 8.15.2 Steam Jet Air Ejectors for Quick Start .........................................................................15 8.15.3 Not Used.......................................................................................................................15 8.15.4 Air Flow Measurement.................................................................................................15 8.15.5 Noise Attenuation .........................................................................................................15 8.15.6 Air Ingress ....................................................................................................................15

8.16 CONDENSATE STORAGE TANK...............................................................................................15 8.17 CHEMICAL DOSING AND SAMPLING........................................................................................16

Turb.Sect8.Cond&Feed Heating 14Sept07.doc Page 1 of 16


8.1 Scope of Supply

The condensing and feed heating plant shall comprise, but is not limited to, the following:

• Condensate extraction pumps.

• Extraction pumps suction strainers.

• Gland steam condensers.

• Drain coolers.

• Low and high pressure feed water heaters.

• Air ejectors with inter and after condensers

• By-pass for feed water heaters.

• Deaerator.

• Feed water storage tanks.

• Drain and make-up pumps (deionised make-up water pumps excluded).

• Drain control vessels and flashboxes.

• Drain traps and orifices.

• Condensate storage tanks.

• All necessary steam, condensate, feed water, drain, circulating water, vent and air piping, valves and fittings.

All other equipment including controls and instrumentation required for the safe and efficient operation of the plant.

8.2 Condensate system

Condensate from the air cooled condenser (ACC) shall be collected in the air cooled condenser condensate tank (ACCCT). The level shall be maintained by means of a level controller in conjunction with two control valves which maintains a head on the two 100% extraction pumps sufficient to suppress cavitation. Low loss conical basket strainers shall be supplied to protect the CPP booster and extraction pumps against loose debris from the ACCCT. A 110 % polishing plant is provided in the pump suction line by others using its own booster pumps to maintain constant throughput.

A recirculation line and control valve from the extraction pump discharge, before the ACCCT level control valve, back to the ACCCT shall maintain an adequate flow at low loads through the extraction pumps, vacuum raising plant and the gland steam condenser. Under



normal operation the flow from the extraction pumps is to the deaerator.

8.3 L.P. Feed System

The L.P. feed system shall comprise a single train of three surface heaters followed by a deaerator of the spray type. The condensate/feedwater systems shall be operated on the combined oxygen treatment method. This means that there will be no need to deaerate the condensate under normal running conditions. However, it will still be necessary to vent the incondensable gases from time to time. The direct contact heater will still be required as part of the feedheating system.

Motorised bypass valves shall be provided around each of the L.P. heaters with the heaters having individual motorised inlet and outlet condensate isolating valves.

A drain line stub and valve for a line from the deaerator to the boiler blow down condensate tank shall be provided for clean-up and drainage of the condensate system.

Separate suction connections from the deaerator storage tank to each of the three boiler feed pumps shall be provided.

8.4 H.P. Feed System

The H.P. feed system shall provide heated condensate from the deaerator via two banks of H.P. heaters, to the boiler. The boiler feed pumps and deaerator shall be situated at suitable levels to provide sufficient suction head from the deaerator storage tank to prevent cavitation. In order to prevent damage to the pumps at low flow, each pump shall have a recirculation connection back to the deaerator storage tank which is controlled automatically by flow measurement taken in the crossover line between booster and main pumps.

The feed flow to the boiler shall be controlled by the boiler feed regulating valve station situated immediately downstream of the pumps and by the speed of the boiler feedpumps. The control and isolating valves for the feed regulating station shall be supplied by others and are to be installed by the Contractor.

The H.P. heaters shall be arranged in two banks of 50%, with a two 50% bypass lines. The bypass valves are three and two way hydraulically operated valves .The pilot valves used to open or close the valves is a multistage pressure reducing valve. The valve must operate from the full feedwater pressure down to atmospheric pressure without the need for down stream orifices or valves. Blocking devices to



make the valves inoperable for maintenance are to be supplied and any other fitting needed for the operation or maintenance of the feed heating plant The valves are to be set to allow up to 65% of the total MCR flow through either heater bank which is not isolated. The heater drains shall be sized to accommodate this excess flow.

The heater drains shall be controlled by 3 level transmitters mounted on standpipes. Each heater shall have two drain connections a "normal" drain and an "alternative" drain controlled by the level transmitters. Both of these drains connect to the drains cooling zone of each heater, where applicable. The normal drain routes are from the highest pressure H.P. heater to the next lower pressure H.P. heater of the same bank and from the lowest pressure H.P. heater to the deaerator. The alternative drain routes are directly from each heater to either the air cooled condenser condensate tank or the turbine condensate tank depending on the orientation.

The high pressure feed heaters shall be suitable for operating on the delivery side of the boiler feed pumps. These pumps shall be arranged to deliver feed water from the deaerator storage tank via the feed regulating station through the high pressure feed heaters to the boiler.

The feed heating plant shall maintain the final feed water temperature at maximum continuous rating.

The shutoff head shall be at the maximum design speed of the boiler feed pump.

The design pressure for the water side of the HP heaters, which are downstream of the feed regulating station, shall be the same as the economiser design pressure.

The design pressure for the piping and valves upstream of the pump isolating valves shall be designed for the shutoff head of the boiler feed pumps according to the applicable code.

The design pressure for the piping and valves between pump isolating valves and regulation station shall be protected against over pressure by means of a safety function device (3 direct wired pressure switches (2 out of 3) which shut down the BFPs in case of abnormal high pressure detection). This protective safety device must be designed according to European rule reference EN 764-7.

8.5 General Requirements for Pressure Vessels

The heaters, deaerator, deaerator storage tank and similar pressure vessels shall comply with the requirement of the OHS Act No.85 of 1993 as amended.



8.6 Condensate and Feedheating System

Heating of condensate by passing it through oil coolers or through the generator cooling equipment is not acceptable.

All heaters including the deaerator storage tank shall have independent vents directly to the air cooled condenser condensate tank for start up and periodic venting purposes.

Each low and high pressure heater, except the deaerator, shall be capable of automatic and complete isolation on both steam and water sides and bypassed to enable it to be taken out of service without shutting down the turbine generator.

However it is not possible to dismantle the HP heaters without shutting down the turbine generator ( No double isolation provided ).

Furthermore, the HP heaters will be bypassed two by two.

Bled steam valves shall have the ability to be automatically stepped open to be able to contain the temperature rise to that specified by the heater manufacturer when bringing the heaters into service.

The heater bled steam isolation and non-return valves shall have the ability to be stroke tested on load, the actuators to be sized to suit these requirements.

The level control and turbine protection system shall be a two out of three voting system and in accordance with “Recommended practices for the Prevention of Water damage to Steam Turbines Used for Electric Power Generation” ASME TDP 1-1998 and IEC60045 requirements.

The Contractor shall describe in full his proposal for a system to accomplish this including any extra recommendations that he considers necessary.

Heater shell and tube nests shall be adequately protected against steam and flashing drains impingement. Baffles and target plates for this purpose shall be of stainless steel and shall be renewable, The shell (bundle) shall be removed to renew these plates. The tubes shall be supported by grids and not baffle plates. The baffle plates and all internal parts other than the tubes are to be made from a suitable corrosion and erosion resistant stainless steel.

Where necessary, heaters shall be provided with sub cooling sections, to prevent erosion due to flashing of cascading heater drains. Drains cooler shrouds shall be manufactured from pressure vessel quality materials and all welds shall be full penetration. Heater level controls shall be designed to prevent steam ingress into the drains cooler under all modes of operation.



Desuperheating sections are to be fitted to heaters were the heater bled steam is sufficiently superheated. Desuperheating shrouds shall be manufactured from pressure vessel quality materials and all welds shall be full penetration. The Contractor shall ensure that tube vibration is prevented and that dry wall conditions are maintained under all modes of operation (including bypass of lower heaters).

Heaters are to have 5 % excess surface area to allow the performance of the heater to be maintained even with 5 % of the tubes plugged. Also the maximum feedwater velocity and pressure drop limits shall not be exceeded.

The design of the heaters including the deaerator storage tank shall take into account the changes in bled steam velocities due to changes in ambient temperature and operating scenarios (including the bypassing of lower pressure heaters).

The Contractor shall supply details of the precautions taken.

All necessary steam, water and vent piping, valves, drains with controls, siphon pipes, traps and orifices shall be provided on each heater.

All heater shells shall be provided with a minimum of two inspection ports of at least 150 mm diameter. If shell inspection manholes are provided then they must be a minimum inside diameter of 400 mm.

All steelwork necessary for supporting the feed heating equipment and accessories together with all platforms, ladders, stairways and handrailing for gaining access shall be supplied by the Contractor.

Heaters shall not be provided in a stacked configuration where it would be necessary to remove a heater in order to access the affected one.

Safety valve blow-off piping shall be clad in thermal insulation and shall be led to suitable expansion vessels, which shall be regarded as coded items and shall be designed, and manufactured accordingly.

Drain piping from these vessels, leading to the nearest drain trenches, shall be provided and the points of discharge into the trenches shall be so designed as to avoid any danger to personnel from scalding.

Safety valve blow-off piping, expansion vessels and all connections likely to be sources of noise generation shall be suitably attenuated to limit the noise level in accordance with Section 2.

Heater tubes shall be transported in robust containers. The tubes shall be well packed to prevent movement during transit and adequately protected against wet and dirty conditions. The outside surfaces of the containers shall be clearly marked to indicate the points for lifting slings or ropes. Feedwater heater tubes shall be protected from physical



damage and corrosion at all stages of manufacture, delivery and storage at site.

All heaters are to be supplied with lifting trunnions suitable for the total weight of the heater. A procedure for lifting shall be supplied.

Heater shells shall be of all welded construction and provided with a cut point for shell removal. The cut point shall be provided with a flame protection band to prevent damage to the tube bundle during cutting.

8.6.1 Safety and relief Valves

Safety valves shall be provided on the steam and water sides of all heaters and steam side of the deaerator storage tank. These shall be sized and rated in accordance with the OHS Act No.85 of 1993 as amended.

Safety valves shall be robust in design and seat faces shall be selected to withstand repeated operation. The set pressures shall be so determined that valves do not operate needlessly, that is, the set pressures of the safety valves shall be the same as the design pressures of the corresponding sections of the heaters. On the water side there shall be two relief valves with a cross over switch allowing for maintenance to be performed on one valve while the other is in service. The relief valves shall be suitably sized to allow for any trapped expansion in the tube side of the heater when it is isolated on the water side and the bled steam is still supplied

8.6.2 Gland Steam Condenser

The standards or codes of practice applicable to the gland steam condenser, shall comply with the requirements specified in Section 2.

8.6.3 Condensate Polishing Plant

A condensate polishing plant shall be provided by others. It shall be complete with its own circulating pumps and provision shall be made for it to operate in a bypass system up-stream of the condensate extraction pumps. The Contractor shall supply all necessary isolating valves for normal or bypass operation.

8.6.4 LP Heaters, Drain Heaters, Drain Coolers and Gland Steam Condenser

The Codes and Standards of practice applicable to the low pressure heaters, the associated drain control vessels or flashboxes and the drain coolers shall comply with the requirements specified in Section 2.



The tubes for low pressure heaters, drain coolers and gland steam condensers shall be of a suitable corrosion and erosion resistant stainless steel.

The material of the tube plates for the low pressure heaters, drain coolers and gland steam condenser shall be compatible with the tube material.

LP Heaters, drains coolers and gland steam condenser(s) shall be designed to the latest edition of the HEI Standards for Closed Feedwater Heaters and Power Plant Heat Exchangers as applicable. Other recognised standards may be applied subject to acceptance by the Engineer.

8.7 LP Heater drains tank and pump

LP heater 2 shall be provided with a drains pump to return the condensate back into the condensate feed line. The suction of the pump shall be taken from a drains receiver which shall be supplied with a suitable level control system.

8.8 Deaerator and Deaerator Storage Tanks

8.8.1 Deaerator

Deaeration shall be in the form of sprayers installed in the top of the storage tank to achieve the condensate deaeration required during startup.

8.8.2 Deaerator Storage Tank

A single deaerator storage tank shall be provided. The deaerator shall operate with bled steam extracted from the turbine and the cold reheat line of the unit.

The latter extraction shall be used during low load and bypass operation to ensure adequate NPSH to the feedwater pumps under these conditions.

The deaerator can be heated during start-up by steam from the auxiliary steam range.

The capacity of the tank at trip level shall be sufficient to ensure that flashing does not occur in the main feed pump suction piping or the



booster pump suction piping under transient conditions caused by a unit trip from maximum load.

The capacity of the storage tank between normal upper level and minimum safe working level shall provide approximately 8 minutes feed flow at MCR of the turbo-generator. A vortex breaker in the tank and booster pump suction pipework shall be provided.

Wave breaking baffle plates shall be provided in the storage tank to ensure that wave formations do not occur under any operating condition.

The deaerator and storage tank shall be arranged in the turbine house in the position and at the level determined by the Contractor to meet the NPSH requirements of the boiler feed booster pump under all operating conditions.

The bled steam lines to the deaerator shall have two quick acting non-return valves in series, one of which shall be of the flap type to prevent steam reflux into the turbine. Suitable drainage of the bled steam piping shall be provided.

Normal HP heater drains and the feed pump leak off valves flow shall be introduced into the storage tank at a point where these shall not influence the operation of the level controllers. The method of introducing the drains shall not cause erosion of the tank.

8.8.3 Fittings, Accessories and Connections

The deaerator/tank unit shall be supplied complete with all necessary pipes, valves and accessories including access galleries, handrailing, stairways and lifting tackle (see Section 2).

8.9 Auxiliary Steam Supply

The auxiliary steam system supplies steam to the following turbine consumers:

• steam air ejectors

• turbine glands

• deaerator preheating

• turbine pre-warming system if applicable to the Contractor’s design

Only the holding steam air ejectors demand steam during continuous running. The auxiliary steam manifolds of each unit shall be



interconnected via a steam main. Thus each unit shall have an auxiliary steam supply independent of its main boiler for start-up purposes. The Contractor shall connect to the auxiliary steam supply from the stub on the auxiliary steam main and provide piping and connections to the above consumers.

The cold reheat of each unit shall be connected to the auxiliary steam main to provide a link to all units. The main is to be charged with the highest pressure cold reheat steam of any unit running. This steam shall be available to the auxiliary consumers of any other unit for start up purposes through the unit auxiliary steam manifold. No more than one unit may be started up at any one time. The system shall be designed such that any unit may be used to start any one other unit. Boiler consumers shall be supplied directly from the main and the turbine and deaerator consumers from the manifold.

Until two units are commissioned, from when it is assumed that at least one unit shall always be running, an auxiliary boiler shall be provided by others with an operating condition of 3.0 MPa(a) and 350°C. All auxiliary steam users must be designed to accommodate these conditions.

For the purpose of sizing the auxiliary boiler supplying the manifold, the steam quantities and conditions required for preheating and by other simultaneous consumers, are stated in schedule D.

8.9.1 Auxiliary Steam Manifold

The Contractor shall supply the auxiliary steam manifold which receives steam via one motorised and one manual isolating valve from the auxiliary steam main (by others). The valve configuration shall ensure double isolation. The manifold shall be drained via a steam trap to the boiler blowdown vessel.

8.10 Deaerator and ACCCT Control System

The Contractor shall provide a system of controlling the levels of condensate in the deaerator feed storage tank, ACCCT and the condensate storage tank. Excess condensate from the condenser/deaerator system shall be rejected to the condensate storage tank. The complete system shall be designed to avoid sudden variations in the discharge head of condensate extraction pumps with changes of load on the set.



8.11 High Pressure Heaters

The heaters shall be of the header type in two banks of 50% with bank bypasses.

The configuration of and features of access to the headers shall be such that all tube ends are readily accessible for plugging or repair and shall have a minimum inside diameter of 400 mm.

Tubes shall be of solid drawn seamless carbon steel of feedwater heater quality and shall be selected to suit the design temperatures and pressures and the quality of feed water and distillate to which they shall be subjected when in service. Each tube shall be formed from a continuous section of tubing and bends shall be stress-relieved after forming.

If the tubes cannot be supplied in a continuous section for the header type heater it shall be stated in the Schedule D.

Regardless of heater type, the feedwater velocity in the heater tubes shall be no greater than the maximum velocity limits contained in the HEI Standard for Closed Feedwater Heaters.

An emergency drain in conjunction with the normal drain shall be provided leading to the ACCCT or TCT on each HP heater and shall be arranged to open on a water level rising signal from the alarmed heater. An independent high level alarm on each heater shall be arranged to automatically isolate the bled steam supply to the alarmed heater bank and close the feed water bank isolating valves should the water level in a heater rise to an unacceptable level. The isolating valves shall be of the parallel slide type and in addition to automatic isolation shall be arranged for local manual and remote control operation from the control room.

A two 50% bank by-passes shall be provided capable of accepting the full MCR feed flow for indefinite periods. The by-pass valve shall be of the 3 way hydraulically operated type.

The drains of the heaters shall be automatically diverted or bypassed, as required for the safety of the plant, under this or other disturbances. The complete by-pass system shall function smoothly and efficiently under all conditions of operation.

Heaters may be of vertical or horizontal orientation. The Contractor shall ensure that the level control arrangement is suitable for the orientation selected.

Each heater shell shall be provided with a manually operated drain valve, with drain piping led to the nearest drain trench for draining during outages.



The hydraulic test of the HP heaters is to be done after manufacture with the acceptance of the AIA (Authorised Inspection Authority). If after the hydraulic test has been completed there are tube leaks then the number of tube leaks allowable shall be no greater than the number agreed by the Engineer. In no event shall the number be greater than that allowed by the Standards of the Tubular Exchanger Manufactures Association.

8.12 Not Used

8.13 Air Cooled condenser condensate tank (ACCCT)

The ACCCT shall be designed and manufactured to the latest revision of EN equivalent to BS 5500 with materials to BS 1501 Part 1 or DIN Standards/AD Merkblaetter.

The net capacity of the ACCCT shall be a minimum of 100 m3. The final sizing and working levels of the receiver shall be determined by the Contractor.

Construction shall be of the all welded type, and the receiver shall be air tight under all conditions of operation. No severe thrusts or moments shall be experienced by the receiver or the piping connected to the condensing plant elements, and suitable renewable carbon steel baffling or permanent stainless steel baffling shall be provided to prevent impingement onto the receiver walls.

It shall be at all times ensured, that the receiver condensate level is sufficient to supply the extraction pumps allowing for time lag of level controlling devices.

The operating level in the ACCT shall be maintained by the extraction pumps level control valves. The Works makes provision for Two 100% ACCCT level control valves, one in service and the other on standby (Control valves to be supplied by Employer as per C&I LOSS diagrams). Minimum flow valves and piping shall be provided from each pump discharge line before the control valves back to the ACCCT.

The Contractor shall supply the following:

• Manholes to provide access to all internal compartments of the receiver.

• Connections incorporating an automatically operated valve, to admit make-up water when required, from the condensate reserve tank in the event of a low water level in the deaerator storage tank.



• A device to shut off the manual make-up and recirculation from the

condensate reserve tank in the event of high condensate level in the ACCCT.

• A transmitter for the high condensate level alarm.

• Flanged connections to receive drains and normal make-up via the TCT.

• One suitably sized flange on the shell complete with isolating valve and pipes, for filling the ACCCT with make-up water for pressure testing. A small bore telltale flow connection and valve shall also be provided at the highest permissible level for use in connection with this filling valve to indicate when the water has reached the required level for the high level water test.

• A balancing line between the Turbine exhaust duct and the ACCCT

Details of the corrosion prevention design measures envisaged for the condensate contact surfaces of the ACCCT and associated equipment and fittings shall be submitted to the Engineer for approval.

8.14 Turbine condensate tank (TCT)

The turbine condensate tank (TCT) shall collect the turbine HP and IP drains and the HP and LP bled steam drains. In addition it shall receive drains from the gland steam atmospheric drains tank, the HP heater vents drains from the ACCCT inlet ducts and the vacuum raising equipment. The drains shall be admitted to the TCT via a drains flash tank which is an integral part of the TCT.

The TCT is to be supplied with 3 drains pumps returning the drains to the ACCCT.

For full load normal drains: two 100% normal duty drain pumps are provided.

For start up: one pump sized to be sufficient for all the drains during start up is provided.

The Works shall make provision for a minimum of two TCT level control valves (Control valves to be supplied by Employer as per C&I LOSS diagrams). The valves are to be selected to suit the pump flows. The collected drains are pumped to either the ACCCT or the water treatment plant (WTP) depending on the water quality which shall be measured continually at the TCT. The operating level in the TCT shall be maintained by the pumps level control valves. Minimum flow valves and piping shall be provided from each pump discharge line before the control valves back to the TCT.



The TCT shall be designed and manufactured as per clause 8.13 above. The TCT is to have a minimum net capacity of 15 m3. The final sizing and working levels of the receiver shall be determined by the Contractor.

Construction shall be all welded. Suitable renewable carbon steel baffling or permanent stainless steel baffling shall be provided to prevent impingement onto the shell.

It shall be at all times ensured, that the TCT operating level is sufficient to supply the TCT pumps allowing for time lag of level controlling devices.

The vent from the TCT to the ACCCT shall be of sufficient diameter so that over pressurisation of the TCT is not possible when the maximum number and flow of drains are dumped into the TCT.

8.15 Air extraction equipment

The Contractor shall provide suitable air extraction equipment necessary to provide the required vacuum for the steam cycle. The ejectors shall be steam jet holding air ejectors and steam driven quick start air ejectors.

The air ejectors shall be operated both by remote control from the control room and by local manual control. The air connections from the ejectors to the condensing plant shall include efficient non-return valves.

Tubes for the inter-and after-condensers of the steam jet air ejectors shall be of a suitable corrosion and erosion resistant stainless steel. The material of the tube plates shall be compatible with the tube material.

The Contractor, shall supply and install the piping necessary to supply condensate to the inter and after-condensers and shall pipe this condensate back to the main condensate piping.

8.15.1 Steam Jet Air Ejectors for Holding Vacuum

The holding ejectors are two 100 % duty steam air ejection units for the extraction of air and non-condensable gases for the maintenance of vacuum in the steam condensing system. This equipment shall be well proven, reliable and acceptable to the Engineer.

The design air leakage rate for maintaining the required vacuum under maximum continuous rating conditions of the turbine shall be designed to the HEI standard and stated in Schedule D. The 100 % duty ejector



unit shall be capable of dealing continuously with this air quantity under all operating condenser back pressures.

8.15.2 Steam Jet Air Ejectors for Quick Start

The quick start ejectors are two 100 % duty steam hogging ejectors capable of attaining an absolute back pressure of 35 kPa within thirty minutes of sealing steam being applied to the turbine glands.

Such ejectors shall be well proven, reliable and acceptable to the Engineer. The accessories shall include an efficient non-return valve in the connection to the condensing system and suitable exhaust piping leading to the outside of the turbine house. The steam is to be supplied from the auxiliary steam manifold.

8.15.3 Not Used

8.15.4 Air Flow Measurement

The ejectors shall include means for measuring air flow, particularly to indicate abnormal air ingress.

8.15.5 Noise Attenuation

The plant shall meet all statutory regulations and the Employer’s Requirements. See Section 2

8.15.6 Air Ingress

When air leaks occur, then it shall be possible to locate and repair such leaks, and to this end the Contractor shall submit details of the equipment which he shall provide for these operations, and the procedures for its use.

8.16 Condensate Storage Tank

The Contractor shall provide each unit with a condensate storage tank (CST) of not less than 600m3 net capacity, which shall be installed outside the turbine house and shall operate in conjunction with the make-up system. The normal demineralised make-up supply to the system directly shall be not less than 5% of the MCR flow to the boiler and shall be supplied directly into the ACCCT from a demineralised water main. In addition an emergency demineralised water connection



to the ACCCT shall be provided capable of 12% of the MCR flow to the boiler from the CST.

The condensate storage tank shall have the following:

• A nitrogen blanket to eliminate oxygen ingress into the tank contents. The supply of nitrogen is provided by others.

• An overflow pipe fitted with a seal arrangement to eliminate oxygen ingress leading to the nearest drain trench.

• A drain connection, flush with the bottom of the tank complete with a lockable valve and piping leading to the nearest drain trench.

• Roof edge railing.

• Caged ladder leading to the roof.

• Lightning arrestor system.

• Roof gutter and downcomer to the ground level and drains system.

• Shell and roof manholes

• Roof vent holes.

• Contents level gauge

• Earthing boss The sections of the tank in contact with condensate shall be manufactured from stainless steel.

Internal stainless steel surfaces must be cleaned and left untreated.

The Contractor shall be responsible for the design of the foundations in accordance with the relevant information in Sections 2 and 14 of the Employers Requirements

8.17 Chemical dosing and sampling

See Section 1 and 2 for the terminal points and details of the chemical dosing and sampling system.


Date post:	07-Nov-2014
Category:	Documents
Upload:	prashant-sharma
View:	9 times
Download:	0 times

Turb.sect8.Cond&Feed Heating 14Sept07

Documents