1     General

The project will include two 600MW supercritical coal fired units.

The newly-built power house (main power building) will be of proven and prevail four-array type arrangement, covering Turbine Hall, Deaerator Bay, Bunker Bay and Boiler area in series. The mode and major size of proposed power house taking reference from several existing international and Chinese domestic power stations with 600MW class unit which have already been demonstrated successfully by actual reliable operation and rich experiences.

2      Boiler  

The boiler proposed is supercritical pressure, single reheat, once-through, balanced draft boiler, designed for firing specified pulverized coal as the main fuel. Its capacity and steam parameters are carefully matched with those of steam turbine generator set.

The boiler is be designed for SH/RH outlet conditions of �?/SPAN>/�?/SPAN> and capable of meeting the guaranteed performance.

The boiler BMCR capacity is 1947.86t/h and can able to operate a turbo-generator set of 600MW, complete with superheater, reheater, economizer, air heaters, two forced draft fans, two induced draft fans, two primary air fans and six(6) middle speed mills will be provided.

One Twin Flue Chimney will be provided for two boilers.

Supporting steel structure, soot blowing units, platform, galleries and stair ways and all boiler internal steam, vent and drains piping, blow down/drain vessels, valves, fittings, fuel gas ducts and air ducts, dampers, lagging and refractory, casing, foundation bolts, boiler elevator etc.

The furnace dimensions are designed to provide appropriate volume and plan area, especially considering the properties of design coal.

Light Diesel Oil (LDO) will be used for boiler startup and combustion supporting.

The tentative coal analysis is as follows:

Six middle speed mills per boiler shall be provided based on the coal analysis specified. The total capacity of five coal mills shall be capable of carrying 100% BMCR generation load.

Dry electrostatic precipitators shall be provided on flue gas path between the air heaters and ID fans of a design proven on existing plants operating with similar fuels. The primary function of the particulate extraction plant is to control dust emissions both to the atmosphere.

Two PAF, FAF, IDF will be sized based on the coal analysis and boiler requirement, each fan can meet the requirement of 60%BMCR when one set of fans is out of service.

3    Turbine

Type                                               Super-critical tandem compound three cylinders

four exhaust reheat condensing turbine

Main Steam Pressure:                  24.2MPa

at main stop valves  

Main Steam Temperature:              ï¿½?/SPAN>

at main stop valves  

Reheat Steam Temperature:       �?/SPAN>

at combined reheat valves

Design Exhaust Pressure:             10.13KPa

Steam Turbines have basic design philosophy summarized as follows.

High reliability with detailed design consideration

High efficiency based on advanced fluid dynamic technology

Simple and quick starting based on impulse design

Control system of good stability and high sensitivity

The condenser will be designed in the form of single shell, divided water boxes, single-pass in circulating water side and installed in transversal arrangement. The condenser mainly consists of neck, shell, water box, exhaust expansion joint and so on.

Oxygen in condensate at condenser outlet over the entire load range from zero to Valve Wide Open operating conditions will be controlled at the desired level.

The deaerator will be used to remove dissolved oxygen and other non-condensable gases such as oxygen, carbon dioxide, etc from feedwater by using steam in direct contact with feedwater, heating the feed water to saturation temperature at the deaerator operating pressure so as to raise the thermal efficiency of the unit. The storage tank can store a definite amount of saturated water at deaerator pressure and conform to the standard of oxygen content to meet the needs of the boiler and guarantee its safe operation.

For each turbine-generator set, two 50% duty turbine-driven boiler feed water pumps and one 30% duty motor-driven boiler startup feed water pump will be furnished.

Two-stages (HP&LP) turbine by-pass system will be furnished to reduce temperature mismatch on start-up of the turbine and protect the reheater from damage.

4      Electrical system

The generators proposed for the plant are of three phase, horizontal mounted, two-pole cylindrical rotor type, with the rated power of 600MW, power factor of 0.9 lagging, terminal voltage of 22kV, frequency of 60Hz. The turbine generator adopts the typical water-hydrogen-hydrogen cooling system.

The excitation system offered is of static type. Excitation transformer and static rectifier would be assembly. Excitation transformers is tapped off from the generator busduct to supply the excitation current AC for the excitation system.

Each turbo generator unit would be connected by the isolated phase busduct to its own step-up transformer for feeding power to switchyard.

Station transformer will drawn power used for startup from switchyard.

5    Control and instrumentation

        Centralized control has been considered for the boiler, turbine generator and auxiliary systems of the unit. One Centralized control Room (CCR) shall be furnished for two units. Monitoring and Control for units shall be realized in CCR. The following functions can be achieved:

a.      start/stop units in CCR

b.      Monitoring and adjusting of normal condition in CCR.

c.      Treating with abnormal condition and urgency accident.

d.      Patrolling periodically on site

Automation systems of power plant  shall be composed of Distributed Control System(DCS) and control system of auxiliaries plants. Design principle of control function decentralization and information centralized management will be adopted.

        The entire unit operation and monitoring shall be possible through  color /LCD monitors, at the same time, back-up panel shall be setup, there will be some necessary monitoring equipment, for example ,main parameter large digital displaying meters�?/SPAN>industry TV�?/SPAN>Hardwired window annunciator i.e. There will be fire alarm panel in CCR.

Programmable logic controller(PLC) add MMI control mode will be used for water, ash and coal control point, other auxiliary workshop will be designed as unmanned mode. Water, coal and ash control points can be connected by auxiliary control network, and operator can supervise the process through LCD operator workstation. The centralized supervision of auxiliary control system will also be realized in CCR.

6    Ash handling

        The Ash Handling System (AHS) for each unit shall be designed to collect, transport, dispose of bottom ash, coarse ash, and fly ash and collection of pulverizer reject solid and transporting it to the silo bins for the units.  

       Mill rejects will be collected and transported by battery operated trolley then transported to ash dump area by truck. Bottom ash will be transported to silos by SCC, fly ash will be conveyed to silos by dense pneumatic positive conveying system, bottom ash and fly ash will be transported to ash dump area by truck.

7  Coal handling

There is a crusher house in coal handling system. Two (2) screens and two (2) ring-type crusher are installed in each crusher house. The rated capacity of screen is 1500t/h.

The CHP facility shall have two (2) coal streams, one (1) operating + one(1) as standby. The rated conveyor capacity for conveyors is 1500 t/h.

All conveyor belting is of the fire resistant plied construction type.

When one of the boiler silos send bin low level signal, the coal handling system start work and fill it in until it send bin high level signal.

The coal handling system is controlled by PLC. The interlock is installed between primary equipments.

The type of coal unloading equipment and coal stockpile will be determined based on the site condition.

8    Water treatment

The process of boiler make-up water treatment system will be determined after got the water analysis.

Control way for DM water plant is program controller.

The middle pressure condensate polishing system will be furnished and it includes two (2) set 50% pre-filter + three (3) set 50% capacity high flow rate mixed beds. Two sets beds are operating as the third is stand-by.

9     Environmental Protection

In order to reduce the emission of air pollutants and prevent the fuel gas emitted by the boiler from polluting the environment, the following measures will be taken in design phase:

·       Adopt ESP to reduce emission of smoke-dust and keep its density to meet the emission standard;

·       Adopt low-nitrogen combustion technology on the boiler to reduce the NO_X emission generation;

·       Emit the fuel gas from boiler through higher chimney to increase the ability of gas to dilute and diffuse.

It is required that the noise level of the main equipment and auxiliary not to exceed the level permitted by relevant standards. Certain equipment will be equipped with noise reducing device and noise insulating device.

The overall layout of the pant will be determined so that the layout is reasonable and the noise source is centrally arranged and far away from residential area as possible.

10   Ancillary facilities

Station Air and Instrument Air System,        Start-up Boiler, Fuel oil handing system       , Hydrogen generation system etc. will also be provided as necessary to meet the operation requirement.