BRITISH ELECTRICITY AUTHORITY

 

North West, Merseyside and North

Wales Division

 

CONNAH'S QUAY POWER STATION

 

1954

Lord Citrine

 

THE RT. HON. LORD CITRINE, P.C., K.B.E., Comp. I.E.E

  Chairman, British Electricity Authority

 

CONNAH'S QUAY POWER STATION

 

Opened on Thursday, 16th September, 1954

by

The Rt. Hon. Lord Citrine, P.C., K.B.E., Comp.I.E.E

Chairman of the British Electricity Authority

 

 

Designed and constructed under the direction

of the

MERSEYSIDE AND NORTH WALES

DIVISION

BRITISH ELECTRICITY AUTHORITY

 

 

 

 

North West, Merseyside and

North Wales Division

A.R. COOPER,   Divisional Controller
                 M.Eng., M.I.E.E.. M.Inst.F.
   
P. BRIGGS,   Deputy Divisional Controller

                 M.Inst.F. 

   
J. L. ASHWORTH,   Chief Generation Engineer (Operation)
                 A.M.I.E.E., A.M.I. Mech.E.    
R. S. ATKINSON   Deputy Chief Generation Engineer (Operation)
               A.M.I.E.E., A.M.I.Mech.E.    
C. R. WATSON SMYTH,  
Chief Generation Engineer (Construction)
                M.Inst.F.    
W. H. C. PILLING,   Deputy Chief Generation Engineer (Construction)
                B. A. (Cantab.), M.I.E.E.    
P. H. FLATT,   Divisional Secretary
  B.Sc.(Econ), F.C.I.S.,                         A.M.I.E.E., F.C.W.A., A.M.I.I.A    
E. BUTTERWORTH,   Deputy Divisional Secretary
               A.S.A.A.    
A. H. CAMPBELL,   Divisional Accountant
               C.A    
A. McLELLAN,   Deputy Divisional Accountant
               C.A.    
 
 
 
CONNAH'S QUAY POWER STATION was engineered and completed before the merging of the Merseyside & North Wales Division with the North West Division on 1st April, 1954. In addition to Mr. Cooper, Mr Briggs, Mr. Atkinson and Mr. Pilling, the following engineers of the former, Merseyside & North Wales Division were actively engaged on the project:
 
F. H. S. BROWN   Chief Generation Engineer (Construction) until March 1951
                 B.Sc., A.M.I. Mech.E, A.M.I.E.E.
  and is now Generation Design Engineer, Headquarters
     
K. B. HARRISON,   Generation Engineer (Construction) who is the Engineer in

                 Assoc,M.C.T., A.M.I.Mech.E.

  charge of the project
R. L. BATLEY,   Chief Generation Engineer (Operation) before becoming
                 O.B.E., A.M.I.Mech.E.   Controller of the Midlands Division in March 1953
     
D. F. GRANT,   Generation Engineer (Operation)
               A.M.I.E.E.    
     
J.A. SPENCE,  
Transmission Engineer
                B.Sc., M.I.E.E., A.M.I.Mech.E.    
     
E.A. BURTON,   Technical Engineer
                A.M.I.E.E.    
     
J. EVANS,   Station Superintendent

 

 

 

 

 

 

 

 

A. R. COOPER,
M. Eng., M.I.E.E., M. Inst. F.  
  Divisional Controller

 

 

 

 

 

 

P. BRIGGS,
M. Inst. F.  
  Deputy Divisional Controller

 

C. R. WATSON SMYTH
Chief Generation Engineer
(Construction)

 

 

                                 

W. H. C. PILLING
Deputy Chief Generation Engineer (Construction)

 

 

J. L. ASHWORTH
Chief Generation Engineer
(Operation)
R. S. ATKINSON
Deputy Chief Generation Engineer
(Operation)

K. B. HARRISON
Generation Engineer
(Construction)

 

J. EVANS
Connah's Quay Power Station Superintendent

 

   

CONNAH’S QUAY

 

THE urban district of Connah's Quay has an area of 4,214 acre and is situated in the County of Flintshire, four miles from the ancient borough and county town of Flint, and eight miles from the City of Chester.

The town, which incorporates the port of Connah's Quay, lies on the estuary of the River Dee which separates the County of Flintshire from the Wirral Peninsula, Cheshire.

Connah's Quay has been, from time immemorial, a port of Flintshire and the port of the City of Chester. It is interesting to note that the name derives from an old resident of the town, a publican, whose name was Connah. His public house was situated alongside the quay where vessels loaded and unloaded and was known as Quay House, hence the hamlet formed around this locality became known as Connah's Quay.

Connah's Quay was a thriving little seaport (particularly famous for its salmon fishing) and today is frequented by ships of up to 500 tons. In view of the aim of various improvements now con­templated, it may be capable in the future of giving access to ships of 1,500 to 2,000 tons.

The River Authority is the Rivers Dee and Clwyd Catchment Board. The draft of water on the ordinary spring tides is I1 to 12feet, and on the high spring tides 12 to 14 feet. The tide is affected by direction and strength of wind.

 

 

 

 

THE building of a power station on the Dee Estuary was originally envisaged by the Chester City Council with a view to replacing their existing small station at Queensferry. It was proposed that this new station should be of some 60,000 kilowatts capacity and would be located on the existing site at Queensferry.

Following the establishment of the British Electricity Authority on 1st April, 1948, the project was taken over and it was decided that a larger station was required to meet the increasing electrical load in the North Wales area.

The ultimate capacity of the station will be 180,000 kilowatts and it is scheduled to be completed in three stages, 60,000 kilowatts in 1953, a further 60,000 kilowatts in 1955 and the final 60,000 kilowatts in 1957. The general design is on the unit principle and each stage is to comprise the installation of two 30,000 kilowatt turbo-alternator sets and two boilers each having an evaporation capacity of 300,000 lb. of steam per hour, the necessary switchgear, coal and ash plant, circulating water pumps, cooling tower and general auxiliary plant.

 

The Site

It was obvious that the Queensferry site would not accommodate the new power station and a comprehensive aerial and ground survey of the district was undertaken. From the data obtained and amenities offered at various sites, together with the rail and water borne facilities for coaling the station and water available for cooling purposes, the present site was chosen.

The selected site is located about one mile north-west of Connah's Quay and terminates on the Flint/Connah's Quay boundary line, the total area of land obtained being about 200 acres. It is bounded on the north side by the River Dee and on the south side by the main Chester—Holyhead railway. The area mainly consisted of tidal saltings at approximately 14 feet above Ordnance Datum level which was totally covered at Spring tides with the exception of a small rock outcrop at the entrance to the site at approximately 34 feet above Ordnance Datum level.

The main access to the site was by means of a cart track from the main Chester—Rhyl coast road, crossing the railway by means of a humped-back stone bridge 11 feet 9 inches wide which led to the rock outcrop. Other means of access to the site was by level cross­ings, the gates of which were normally locked.

Ground exploration by trial borings revealed rock formation dipping north-east from the rock outcrop to depths varying from 12 to 20 feet along the railway embankment to 50 feet along the riverside boundary of the site.

Site Reclamation

The first stage of the construction necessitated reclaiming an area of approximately 70 acres of salt marsh to accommodate the power station with its cooling towers, outdoor grid sub-station and coal storage area. 

ABOUT 800,000 TONS OF SAND WERE PUMPED ON TO THE SITE FOR ITS RECLAMATION

 

        The contract for site reclamation was commenced on the 22nd March, 1950, when a series of bunds were built around the site. Within the bunds, 4 inches of top soil were removed from the saltings and stored. The bunds adjacent to the river were armoured with willow mattressing and stone to protect them from erosion.

      Reclamation was undertaken by dredging and pumping sand from a suction dredger anchored in an inland lagoon on the opposite side of the river, about one mile from the station site. From the pumps on this dredger a sand and water mixture was discharged through a 26-inch bore pipe at a rate of 4,500 cubic yards an hour. The sand from the mixture settled and the water was drained away through pipes provided in the bunds for this purpose. A total of about 800,000 tons of sand were pumped in nine weeks. After the deposition of the sand the 4 inches of top soil were relaid, giving a general site level of 22 feet above Ordnance Datum, the depth of the pumped sand being approximately 8 feet. The whole of this work was completed by the 1st August, 1950.

 

BUILDING AND CIVIL ENGINEERING
WORK

Piling

The majority of the works are carried upon 14 inches square precast concrete piles, the lengths of which vary between 15 and 30 feet. Great difficulty was experienced in driving some of the piles the required minimum length, particularly under the turbo-alternator blocks and circulating water culverts. The maximum load on each pile is 60 tons and the spacing generally about 3 feet or 3 feet 6 inches. Approximately 5,100 piles were driven for the complete building and the Nos. 1 and 2 cooling towers.

 

SHUTTERING AND REINFORCEMENT FOR MAIN CIRCULATING WATER DUCTS

 

Foundations

In the case of the buildings, the floors are of beam and slab construction spanning the pile caps, but the cooling tower pond bottom is designed as a flat slab spanning the single piles, which are spaced in this area at 13 feet centres.

The turbo-alternator blocks are of reinforced concrete con­struction. They extend from the basement level to the operating floor level and are 26 feet in height. Each block contains 36 tons of reinforcing steel and 885 tons of concrete. They are completely isolated from the adjoining operating floor by an expansion joint to prevent transmission of vibration.

 

 

MAIN BUILDING

Steelwork

The building is of steel framed construction, the main stanchions and roof girders being in 28 feet bays. The steelwork is of orthodox riveted design, use being made of deep haunched girders to obviate diagonal bracing. The coal bunkers are of steel with a gunite lining and the bunker for each boiler has a capacity of about 500 tons of coal. The first portion of the building, sufficient to house four of the six 30,000 kilowatt generating sets and boilers, contains 3,700 tons of steelwork. It is estimated that the entire building, which is approximately 390 feet long by 236 feet wide by 130 feet high at the boiler house, will require 5,400 tons of steelwork.

 

THE FIRST SECTION OF THE STATION CONTAINS 3,700 TONS OF STEELWORK

 

Cladding

      The main building will house the six turbo-alternator sets and six boilers, together with their ancillary plant and other auxiliary equipment. The walls of the building are generally of 14 inch brick­work, the door and window surrounds and parapets being of reconstructed stone. The majority of the windows are of "Lenscrete " glass concrete construction, whilst the large continuous lantern light to the turbine bay is also of in situ " Lenscrete." The lantern lights to the boiler house and turbine house are louvred for ventila­tion purposes. The roofs are of hollow precast reinforced concrete units with one inch cork insulation and felt and asphalt waterproofing.

Internal Finish

      The operating floor slab of reinforced concrete is finished with cream Terrazzo tiles in the turbine house and Heather Brown Quarry tiles in the boiler and mill bays. The basement throughout has a granolithic finish.

At the operating floor level the turbine house walls have a blue faience tile dado.

ANCILLARY CIVIL ENGINEERING
WORKS

 

South Block

      This consists of a centre block which contains the control room, cable rooms, battery rooms, laboratory and administration offices. The west wing contains the medical treatment rooms, time offices and clocks, lockers, showers, washing rooms and lavatories, and the workmen's and staff canteens and kitchen. The east wing contains the workshop and stores.

 

Ancillary Buildings

      These include circulating water pump house, river pump house chlorination house, water treatment house, coal wagon tippler house coal sampling house, locomotive and bulldozer house, station garage cycle store and gatehouse. The construction is a conventional on of brick walls and concrete roofs with the exception of the tipple house which is clad in corrugated sheeting.

 

Chimneys

     The two chimneys are each 300 feet high and 16 feet cleaj diameter and sit on 58 feet high reinforced concrete stools which are cased in brickwork. The sixteen-sided shafts of the chimney are of reinforced concrete lined with 41 inch " Nori " acid resisting bricks. The total dead load upon each chimney base is 2,700 tons

 

INTERIOR OF COOLING TOWER

 

Cooling Towers

There will be three reinforced concrete cooling towers each capable of cooling 21/2 million gallons of water from 87.5 degrees Fahrenheit to 70 degrees Fahrenheit.

These towers are constructed upon a common pond which can be divided to enable operation of one half of any tower.

The towers are 250 feet high, 238 feet in diameter at the bottom and 110 feet diameter at the rim. The towers and ponds are of sulphate resisting Portland cement concrete as there is a possibility of high concentrations of sulphates in the pond after it has been concentrated several times.

The cooling tower pond, 6 feet 3 inches in depth, holds about 81 million gallons of water. The towers are fitted with spray eliminators and de-icing equipment. Each tower weighs approximately 4,150 tons.

                                PLANT

Turbo-Alternator Plant

      The turbine plant consists of six 30,000 kilowatt turbo-generators with an economic rating of 24,000 kilowatts. The turbines are twin-cylinder machines with a duplex exhaust and are of the reaction type running at 3,000 revolutions per minute. The operating steam conditions are 600 lb. per square inch gauge and 850 degrees Fahrenheit at the stop valve.

Each high pressure rotor has 48 rows of blades and each low pressure rotor has twelve rows of blades (six rows of

TURBINE ROOM, SHOWING Nos. 1 & 2 TURBO ALTERNATORS

 

of moving blades in each section). From the last stages of the low pressure cylinder the steam is exhausted to a three pass surface type condenser capable of maintaining a vacuum of 28.7 inches of mercury when the turbine is operating at its economic continuous rating, the cooling water inlet temperature being 65 degrees Fahrenheit and the outlet temperature being 87.5 degrees Fahrenheit.

There are two electrically driven extraction pumps each capable of handling the full quantity of condensate. Two 100 per cent duty steam operated multi-stage air ejectors are provided for maintaining vacuum in the condenser, together with one single-stage quick start ejector which will create a vacuum of 20 inches of mercury in the condenser in four minutes.

     Four feed water heaters are provided and utilise bled steam from the turbine at pressures of 154, 58.2, 15 and 5.1 lb. per square inch absolute—these being the conditions for a maximum load of 30,000 kilowatts on the turbo-alternators. The final feed water temperature leaving the No. 2 high pressure heater is 345 degrees Fahrenheit.

     The boiler feed pumps are positioned between the second and third feed heaters. A shunt deaerator is fitted into the feed system to ensure a supply of deaerated water for make-up. The instruments provided with the turbo-alternator are mounted on a unit control panel which is supplied under the boiler contract.

      The alternator is of the three-phase totally enclosed ventilated type and is connected directly to the rotor of the turbine through a multi-claw semi-flexible coupling. It is excited by its own exciter directly driven from the alternator shaft. The alternator cooling is by means of a closed air system, the air being circulated by two motor driven fans each capable of providing the quantity of air necessary when the machine is operating at 60 per cent of its maximum con­tinuous rating.

 

 

Boilers

Ultimately there will be installed in the station six Lopulco water tube type boilers each with a steaming capacity of 300,000 lb. of steam per hour at a pressure of 625 lb. per square inch and 865 degrees Fahrenheit.

The complete steam raising unit including the economiser and air-heater is supported on structural steelwork which is carried from the basement level completely independent of the building structure.

The boiler is of tri-drum type, each drum being of hollow forged steel construction. All boiler and furnace tubes are 31 inches outside diameter. The finned tube construction consists of two one-inch wide fins welded diametrically opposite each other.

The furnace chamber is completely water cooled. The front, sides and lower rear walls are of fin tube construction thus presenting a total metallic heating surface in the chamber and therefore reducing the amount of refractory brickwork exposed to the absolute minimum.

The superheater is of the welded type and will automatically maintain a final temperature of 865 degrees Fahrenheit within plus or minus 15 degrees Fahrenheit by means of tilting burners over a load range of 80 to 100 per cent rating of the boiler.

Automatic boiler control equipment is provided to control the supply of fuel, steam pressure, air for combustion and furnace pressure.

Each boiler is provided with an all-welded economiser which is arranged in one bank. The heating surface of the economiser is built up of a number of horizontal elements. The elements are arranged in such a way that the gases flow in vertical paths between them.

The air heaters are of the plate type arranged for contra-flow heat transfer and the assembly comprises a mild steel casing, housing the plate elements which are 12 gauge thick.

All the main dampers on the boiler are remote controlled by Lockheed hydraulic mechanism operated from the unit control panel from which also starting and stopping of  the boiler auxiliary motors is controlled.

 
TOPS OF THE FIRST TWO BOILERS

 

Each boiler will be provided with two forced and two induced draught fans, the former drawing air from above the boiler inside the boiler house in order to provide a measure of reclaimed heat.

 

FORCED DRAUGHT FAN AND MOTOR

 

Electrostatic Precipitator

From the boiler the flue gases pass to an electrostatic precipitator arranged in two independent sections thus enabling one half of the plant to be shut down for maintenance. Each precipitator is equipped with its own high tension house and rectifying equipment. From the precipitator the gases pass to the induced draught fans and are then discharged to the main flue and chimney.

Coal Handling Plant

Some 10,000 tons of coal a week will be consumed at the power station when it is completed. Sidings have been provided to deal with supplies brought in by rail wagons and in addition road borne coal can be accommodated.

Two sidings for the reception of coal wagons from the British Railways main lines are each 1,100 yards long. These reception sidings feed a system of exchange sidings which link up with two major tracks leading to the two coal wagon tippler plants. Each of these wagon tipplers will discharge at an average rate of 250 tons per hour when handling 20 tons capacity trucks. The wagons discharge into a common hopper which is part of the tippler structure, this hopper having a capacity of 50 tons of coal.

Each tippler platform is designed so that it is integral with the weighbridge and weighs the wagons prior to tipping and after tipping ; the consequent readings are recorded on a ticket stamping mechanism to record the gross and tare weight of each wagon discharged.

The coal from the hopper is discharged upon a short feeder conveyor which in turn feeds a main belt conveyor which is designed to deliver coal at the rate of 250 tons per hour to the coal junction house where coal can be fed either to the boiler house bunkers or to the coal storage area.

From the junction house coal can be conveyed by means of two belts into the boiler house. These belts are each capable of handling coal at the rate of 125 tons per hour as a continuous normal

 

COAL HANDLING PLANT

 

operation. Each of these belts is capable of working entirely independent of each other if it should be necessary to close one down for repair.

Inside the boiler house, coal is discharged into small hoppers which feed two shuttle conveyers which are capable of serving the three hoppers of each boiler bunker. From the bunker outlets coal is fed through chutes down to the Lopulco coal grinding mills of which there are three for each boiler. During the course of grinding, the raw coal is dried by means of hot air which is also used as primary air to the burners. Each mill is operating under suction and consequently whilst it is working there is little likelihood of any dust being expelled from the mill into the mill bay. Each mill is provided with its own exhauster fan which is designed to deliver the coal laden air to each of the burners via a system of fuel piping.

 

PULVERISED FUEL MILL

There are four pulverised fuel burner boxes provided—one in each corner of the combustion chamber. Each is complete with three burners so that, by means of tangential firing, high turbulence is obtained in the furnace.

Coal discharged from the junction house to stock is distributed over the storage area by bulldozers. When coal has to be reclaimed from stock, the coal is bulldozed to either of two hoppers which discharge on to a belt conveyer system which returns the coal to the junction tower and the system proceeds as previously described.

 

 

Feed Pumps

Each boiler turbine unit has an electrically driven feed pump capable of pumping 330,000 lb. of water per hour against a pressure of 880 lb. per square inch. A steam driven feed pump capable of the same duty is installed with each unit as standby in case of failure of the electrically driven pump and is arranged to start automatically at a predetermined reduction in the feed pressure delivered to the boilers.

The exhaust steam from the turbine is normally passed into the No. 2 low pressure heater of the associated main turbine. Relief valves are fitted, however, to exhaust to atmosphere.

 

Feed Pipework

The feed pipework is of 6 inches diameter all joints, including pipe to valve joints, are welded with the exception that flanges are provided at terminal points.

 

Steam Pipework

The main steam pipework is of hot drawn seamless carbon steel tube of 12 inches bore. Certain terminal points are flanged, but all intermediate joints including valve joints are welded. Although the power station is of unit design, a 10 inch "hospital" main is supplied which is connected to all units.

Ash and Dust Handling Plant

The ash and dust discharges from the respective hoppers at the bottom of each boiler and precipitator into sluiceways which run

lengthways throughout the station under the hoppers—each sluice-way accommodating three boilers. These sluiceways join into a common sluiceway on the centre line of the station from which discharge is made into a swirl pit 15 feet below ground level. The sluiceways are lined with semi-circular cast iron liners.

 

ASH LAUNDER DISPOSAL POINT

 

The water for sluicing the ash and dust into the swirl pit is obtained from the return circulating water culverts at a height of 17 feet above the sluice pumps. There are two 115 horse power sluice pumps each capable of pumping 3,300 gallons per minute, one pump being sufficient to sluice the ash and dust discharged from the station boilers if ashing and dusting is done intermittently.

The swirl pit is of concrete construction with a chrome alloy cast steel liner fitted with three suitable outlets. From this chamber three separate fittings are fixed for the suction pipes to each of the three ash slurry pumps.

The 150 horse power ash slurry pumps are each capable of discharging the slurry at a rate of 3,000 gallons per minute through their respective 12 inch bore pipelines to the top and commencing point of an open culvert 36 feet above general ground level. This culvert, called the ash launder, falls at a slope of 1 foot in 65 feet to the nearest corner of the initial ashing area. The slurry proceeds down the launder and is discharged on to this ashing area where it settles out and the water is returned through a controlled outlet to the river. It is estimated that this initial ashing area will suffice for approximately two years.

The present design of this plant is such that the finishing point of the launder can extend to the second asking area, but it is anticipated that a further swirl pit and booster pump will have to be installed to convey ash to the boundary of the saltings which have been acquired for ash disposal purposes.

      One of the features of the Connah's Quay power station is that sufficient low lying land has been obtained to accommodate the disposal of ash and dust by pumping for an estimated period of 20 years. This will recover tidal saltings for development.

 

Circulating Water System

      To condense the exhaust steam from the turbines each turbo-alternator requires 19,500 gallons of water per minute to pass through its condenser. The minimum flow of the River Dee is insufficient to meet the requirements of six machines, and it is therefore necessary to utilise a cooling tower system.

      Water is drawn from the cooling tower ponds via twin open rectangular culverts, which connect to the circulating water pump house. Six pumps will be installed in the pump house, each having a capacity of 21,000 gallons per minute, and these discharge to twin ducts which run underneath the whole length of the turbine house. Each condenser has an inlet connection from each of the ducts and an outlet connection into each of the two discharge ducts which return the water to the cooling towers.

Make-Up Water Pump House

      Supplies of make-up water for the cooling towers and for the ash and dust sluice water are drawn from the River Dee. A piled dolphin 35 feet from the bank of the river carries two 20 inch pipes through which water is drawn to the make-up water pumps situated in the pump house upon the river bank. The make-up water is drawn from the River Dee at periods of low ebb tides (i.e. when the salt content of the main channel is at a minimum) in order to compen­sate for losses from the system and to replace water drawn from the ponds for sluicing purposes, and then returned to the river. The pump house contains three vertical pumps each having a capacity of 4,000 gallons per minute. The level of the pumps is below the mini­mum water level in the river, so that the suction branches of the pumps are always submerged.

Chlorination Plant

      To eliminate slime forming growths in the condenser tubes and the growth of marine organisms in the circulating water system, a chlorination plant is installed. The chlorinator incorporated in the scheme has a maximum capacity of 3,000 lb. of chlorine for each 24 hours continuous rating, and is designed to operate intermittently under the control of a central programme clock. The chlorine injector is operated by water under pressure delivered from a booster pump, the water being drawn from the circulating water return ducts. From theinjector of the chlorinator, where the chlorine is intermittently mixed with the operating water, rubber-lined piping conveys the solu­tion to the points of application immediately on the inlets to each condenser. To govern the application of chlorine to each set a hydraulically operated valve is installed on the connection to each condenser, the valves being controlled from the main central electrical programme clock.

Water Treatment Plant

 

      The water to feed the boilers must be of a high degree of purity in order to prevent corrosion and the formation of scale, etc., and a complete water treatment plant incorporating the latest methods is being installed, which will receive water from the Connah's Quay Urban District Council town main. The treatment is carried out in a mixed bed " Deminrolit " plant.

      Water from the Connah's Quay supply is received in the power station through a single 6 inch pipe which discharges into a small storage tank from which it is pumped to a header tank on the turbine house roof. Water from this tank is supplied to the water treatment plant which is housed in a separate building on the east side of the main power station buildings. The untreated water first passes through hydrogen ion units in which a Cation exchange takes place converting the salts present in the raw water to their corresponding acids. Thus chlorides, sulphates, nitrates and carbonates are con­verted to hydrochloric, sulphuric, nitric and carbonic acid gas respectively. From the hydrogen ion units the water passes to the " De-acidite " units where an acid absorption enables acids to be removed except for the weak carbonic acid gas which passes through unchanged. The water then passes through a de-gassing tower, the de-carbonised water being collected in a small sump underneath the tower. In this tower the water falling downwards is freed from the carbonic acid gas by means of air which is blown upwards through the tower.

      All the carbonic acid gas is not, however, removed by the de­gassing process and the remaining gas with the silica from the raw water is removed by a third stage of treatment. This stage consists of a mixed bed unit containing Cation and highly basic Anion material through which the degassed water from the sump underneath the degassing tower is pumped. This unit in addition to removing the weak acids still present in the water also removes the silica and any small amount of salts which may remain after the initial hydrogen ion and de-acidite exchange processes. The water leaving the treatment units is then returned to the main building and is added to the system through a connection into each condenser clean drains tank. The connection is made at this point since the treated water is highly aerated and can thus be deaerated in the condenser.

      The hydrogen ion material in the first stage requires periodical regeneration using sulphuric acid. The de-acidite material in the second stage requires regeneration with soda ash and the Cation and Anion materials in the mixed bed unit require regeneration with sulphuric acid and caustic soda respectively. In order to maintain supplies of water while regeneration is taking place duplicate units are provided. The effluents resulting from regeneration are collected in an open sump outside the building, in which they are allowed to mix and neutralise each other. They are then pumped to the ash launder and mixed with the ash and water mixture from the boilers in the ash disposal grounds.

      The capacity of the plant is 144,000 gallons of treated water each twenty-four hour day, the normal treatment rate being 9,000 gallons per hour and the reduced treatment rate, with one section out of service, 5,700 gallons per hour.

A complete set of instruments is provided with the plant and mounted on a panel in the water treatment house.

 

Water Storage Tanks

These water tanks are positioned on the turbine house roof and are in the open air.

The tanks are of sectional pressed steel construction, the seams being seal welded. There are two tanks for each turbo-alternator set, one bearing cooling water tank, one town's water tank and one tank supplying water to the automatic fire fighting system, each tank having a capacity of 10,000 gallons.

The tanks are 16 feet square and 8 feet high, and are constructed of four feet square pressed steel plate. A level alarm and indicator panel is located at operating floor level in the turbine house.

In order to supply cooling water to the boiler steam and water sampling devices, an additional tank of 800 gallons capacity is mounted on the boiler house roof and contains water pumped from the town's water tank. This is necessary because the steam and water sampling arrangements are above the level of the main tanks.

 

Turbine House Crane

This Crane is of 80 feet span designed to lift 65 tons with the major hook and 12 tons with the auxiliary hook and is capable of lifting loads from the ground level (plus 24 feet) to the operating level (plus 50 feet) and to a maximum height of 52 feet above the ground level.

 

Vacuum Cleaning Plant

The station is cleaned by a piping system with various cleaning points located at convenient levels to all floors and areas for remov­ing dust to a common bagging plant. The plant is capable of accom­modating four operators working simultaneously on heavy duty

cleaning. This plant also will be used for collecting dust from the boiler interior during periodic maintenance and overhaul and it will be capable of collecting this dust at a rate of 30 to 35 cwts. per hour. The system is also used for the extraction of dust from the base of the chimney hopper.

The dust collected in the filter receiver is discharged by gravity into. the ash sluiceways and disposed of, with the ash from the boilers.

Station Compressor

      One compressor and air receiver is installed, the compressor being capable of discharging air at 80/125 lb. per square inch with a capacity of 400 cubic feet per minute.

      In addition to the network of vacuum cleaning pipework a com­pressed air pipe system is installed throughout the station for general service. A specific use for this compressed air is in the bunker house where it is used to operate vibrating lances to trim the coal in the bunkers.

Fire Fighting Equipment

      The auxiliary transformers for the power station are situated in a bay at the front of the main buildings and are protected by a fixed equipment of the emulsion forming type.

      The water supply for this system is drawn from a header tank on the turbine house roof as stated previously.

      The equipment installed comprises automatic heat actuated equipment so arranged that water is only discharged on to the area involved in a fire. Each transformer is in a separate bay so that the possibility of the spreading of a fire is minimised. The installation operates automatically and is independent of the human element dur­ing fire emergency conditions.

      Elsewhere in the station, fire hydrant mains have been installed on all floors in all buildings with hose connections supplied at convenient places. The main is pressurised by the operation of a fire pump located in a section of the chlorination house and fed from the circulating water suction culverts.

The system is supplemented by portable fire fighting equipment of the CO, and foam types of hand extinguisher.

 

Workshop

      The workshop is laid out with machine tools capable of carrying out general repairs, the shop being equipped with one 6 inch centre lathe, one pillar drilling machine, one screwing machine (up to 4 1/2 inches), one small shaper, one power saw and associated grindstones etc. and benches. A smithy and welding shop, electricians' shop and various minor stores adjoin the main workshop. The works office is also located in the workshop building and a pneumatic tube system has been installed for the co-ordination of maintenance work between this shop and the various stores and administration office.

Laboratory

The laboratory is installed on the ground floor of the administra­tion building.

ELECTRICAL EQUIPMENT

 

Generator Transformers

     The Generators are connected to the 132 kV system through 36 MVA 11.8/132 kV generator transformers, which are situated in the 132 kV switchgear compound. The transformers are of the forced oil/air blast type, there being two 100 per cent coolers for each transformer.

 

AUXILIARY SWITCHGEAR HOUSE

 

Each transformer is fitted with "On Load" tap changing equipment. The oil in some transformers will have inhibitors added, and the effect of the different inhibitors on the life of the oil and the transformers is to be the subject of research.

 

Station Auxiliary Supplies

      Electrically, each turbo-alternator and boiler is operated on the unit principle, and essential supplies for auxiliaries are drawn from unit transformers directly connected to the alternators.

The auxiliary transformers are mounted in a compound situated under the turbine house annexe.

      Other station supplies and supplies to non-essential auxiliaries are obtained through 5 MVA 132/3.3 kV station transformers of the naturally cooled type. These transformers are mounted in the 132 kV compound.

      The 3.3 kV and 415 V auxiliary switchgear is of the air-break and switchfuse type, and is situated in annexes adjoining the turbine house and boiler house.

 

Cable Work

The station is connected to the 132 kV switchgear compound by a cable tunnel, which conveys all main and multicore cables running between the station and the compound.

 

SWITCHING STATION

 

Cables are, in general, of the paper insulated, lead covered type, but a considerable amount of mineral insulated copper clad cable has been used in the vicinity of the boiler.

 

Control and Relay Rooms

Separate rooms have been provided for the control panels, and for the panels mounting the station protective relays. The rooms are adjacent, and are situated in the centre of the administration block.

A laylight with roof lights provides normal lighting for the control room. Cold Cathode type lighting mounted above the lay-light provides illumination during the hours of darkness.

The walls and ceiling of the control room have been treated in pastel shades to tone with the control panels, the whole effect being pleasing and fresh.

 

CONTROL ROOM

 

ACKNOWLEDGEMENTS

 

 

The development of the project and ultimate design and detailing of the Connah's Quay power station was carried out by engineers of the former Merseyside and North Wales Division which is now amalgamated with the North West Division. Messrs. Mouchel & Partners are civil engineering consultants for the station and the river intake works.

The Authority wishes to acknowledge the help and advice which they have received from many bodies on those matters which naturally arise over the construction of a modem power station in a rural area and among those whose co-operation has materially assisted in the development of the station are the Connah's Quay Urban District Council, the Flintshire County Council, the Dee and Clwyd Catchment Board, British Railways (North Western Region, Bangor), John Summers and Co., Ltd., and neighbouring farmers and societies who relinquished part of their land and privileges for the station's needs as the project grew.

 

 

 

 

MAIN CONTRACTORS AND

PRINCIPAL SUB-CONTRACTORS

 

 

CIVIL ENGINEERING WORKS

 

RECLAMATION Westminster Dredging Co., Ltd.
Sub- Contractor:
   Drainage Culverts The Dredging and Construction Co., Ltd.
   
PILE FOUNDATIONS The Yorkshire Hennibique Contracting Co., Ltd.
MAIN AND ANCILLARY FOUNDATIONS, PERMANENT ROADS, ETC. The Yorkshire Hennibique Contracting Co., Ltd.
  Sub- Contractor:
  Ames Crosta Mills
   
SUPERSTRUCTURE, SOUTH BLOCK AND ANCILLARY BUILDINGS J. Gerrard & Sons, Ltd.
Sub- Contractors:
   Precast roof units Concrete, Ltd.
   Roof lights Lenscrete, Ltd.
   Artificial stone Empire Stone Co., Ltd
   Metal Windows The Crittall Manufacturing Co., Ltd.
   Lifts Aldous Campbell Ltd.
   Guniting Cement Gun Co., Ltd.
  Granolithic flooring Johnson Floor Co., Ltd.
   Terrazzo Diespeker & Co., Ltd
   Water heating Norris Warming & Co., Ltd.
   Staircases, balustrades and ladders F. A. Norris & Co. Ltd.
   Wall and floor tiling Wiggins-Sankey, Ltd.
   
STRUCTURAL STEELWORK Francis Morton & Co. Ltd.
   Sub- Contractor:
   Open Tread Steel Flooring Lionweld, Ltd.
   
   
FERRO-CONCRETE CHIMNEYS Tileman & Co., Ltd.
  Sub- Contractor:
    Climbing equipment, lightning conductors and aircraft warning lights J. W. Gray & Sons, Ltd.
   
COOLING TOWERS CIRCULATING WATER CONDUITS The Yorkshire Hennibique Contracting Co., Ltd.
   Precast vibrated internal stack The Croft Granite Brick & Concrete Co., Ltd
   
RAILWAY SIDINGS T. Summerson & Co.,, Ltd.
   
FENCING Bayliss, Jones & Bayliss, Ltd.

 

MECHANICAL ENGINEERING PLANT

 

65-TON OVERHEAD ELECTRIC TRAVELLING CRANE Clyde Crane & Engineering Co., Ltd
   
TWO DIESEL SHUNTING LOCOMOTIVES John Fowler & Co. (Leeds), Ltd.
   
CIRCULATING WATER MAKE-UP PUMPS, VALVES AND PIPEWORK Gwynnes Pumps, Ltd.
   
HYDRANT FIRE FIGHTING INSTALLATION Matthew Hall & Co., Ltd.
   
ELECTRICALLY DRIVEN BOILER FEED PUMPS AND MOTORS The Harland Engineering Co., Ltd.
   
TANKS Horseley Bridge & Thomas Piggot, Ltd.
   
STATION AIR COMPRESSOR Ingersoll-Rand Co., Ltd.
   
ASH AND DUST HANDLING PLANT International Combustion, Ltd.
  Sub- Contractor:
    Motors Lawrence Scott & Electro Motors, Ltd.
    Pumps Gwynnes Pumps, Ltd.
   
BOILER UNITS, PULVERISED FUEL EQUIPMENT AND AUXILIARY PLANT International Combustion, Ltd.
Sub- Contractors:
   Motors Laurence Scott & Electro Motors, Ltd.
   Boiler valves and mountings Hopkinson, Ltd.
   Boiler drums English Steel, Ltd.
   Superheaters The Superheater Co., Ltd.
   Economisers Senior Economisers, Ltd.
   Pipework Aiton & Co., Ltd.
   I.D. and F.D. Fans Davidson & Co., Ltd.
   Fuel fans Keith Blackman, Ltd.
   Oil fuel equipment Wallsend Slipway & Engineering Co., Ltd.
   Coal weighing machines R. Simon & Sons, Ltd.
   Sootblowing equipment Ivor Power Speciality Co., Ltd.
   Instrument and control panels Bailey Meters & Controls, Ltd.
   Boiler Automatic Control Equipment Bailey Meters & Controls, Ltd.
   Superheater control equipment George Kent, Ltd.
   Dust extracting plant Sturtevant Engineering Co., Ltd.
   
COAL HANDLING PLANT International Combustion, Ltd.
Sub- Contractors:
   Coal wagon tipplers Strachan & Henshaw (London)
   Tippler motors English Electric Co., Ltd.
   Motors Laurence Scott & Electro Motors, Ltd.
   Tippler weighing machine W. & T. Avery, Ltd.
   
WORKSHOP EQUIPMENT Robert Kelly & Sons, Ltd.
   
TURBO-ALTERNATOR SETS, CONDENSING AND FEED HEATING PLANTS C. A. Parsons & Co., Ltd.
Sub- Contractors:
   Alternator ventilating fans Davidson & Co., Ltd.
   Foundation block steelwork Redpath Brown & Co.
   Shunt de-aerators Hick Hargreaves & Co., Ltd.
   Motors Lancashire Dynamo & Crypto, Ltd.
   Circulating water valves Guest & Chrime, Ltd.
   Condenser tubes and tube plates
I. C. I. Metals, Birmingham
Yorkshire Copper Co., Ltd.
   
WATER TREATMENT PLANT Permutit Co., Ltd.
   
LOW PRESSURE PIPEWORK AND VALVES Shaw Petrie, Ltd.
  Sub- Contractor:
   Valves J. Blakeborough & Sons
   
CIRCULATING WATER PUMPING EQUIPMENT Sigmund Pumps, Ltd.
  Sub- Contractors:
   Valves J. Blakeborough & Sons
   Motors Laurence Scott, Ltd.
   
 TURBINE DRIVEN BOILER FEED PUMP SETS Sigmund Pumps, Ltd.
Sub- Contractors:
    Turbines The Mirrlees Watson Co., Ltd.
   
VACUUM CLEANING PLANT Sturtevant Engineering Co., Ltd.
   
 HIGH PRESSURE PIPEWORK AND VALVES John Thompson (Wolverhampton), Ltd.
Sub- Contractors:
   Valves Hopkinsons, Ltd.
   
CHLORINATING PLANT Wallace & Tiernan, Ltd.
   
MOBILE COAL HANDLING PLANT Thos. W. Ward, Ltd
   
AUXILIARY CRANES Wharton Crane & Hoist Co., Ltd
   
AUXILIARY PUMPS Worthington Simpson, Ltd.
   
 

ELECTRICAL PLANT

 

   
MAIN SWITCHGEAR Ferguson Pailin., Ltd.
   
GENERATOR TRANSFORMERS C. A. Parsons & Co., Ltd
   
STATION TRANSFORMERS C. A. Parsons & Co., Ltd
   
AUXILIARY SWITCHGEAR A. Reyrolle & Co., Ltd.
Sub- Contractor:
Brookhirst Switchgear, Ltd.
   
AUXILIARY TRANSFORMERS
English Electric Co., Ltd.
Bonar Long & Co., Ltd.
   
CABLING British Insulated Callender Cables, Ltd.
   
BATTERIES & RECTIFIERS
Tudor Accumulator Co., Ltd.
Hackbridge & Hewittic Electric Co., Ltd
   
FIRE FIGHTING EQUIPMENT Mather & Platt, Ltd.
   
LIGHTING AND HEATING Geo. E. Taylor & Co. (London), Ltd.
   
TELEPHONES Standard Telephone Co., Ltd.
   

 


Original Printing by the British Electricity Authority

British Electricity House, Trafalgar Buildings,

1, Charing Cross, London, S.W. 1.

by The Haydock Press Ltd., London S.E.5.

 
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