Operating and Instruction Manual for

Electrode Steam Boilers

Technical Control Systems Limited

MODELS "ES"

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PRINCIPLE OF OPERATION An Electrode Steam Boiler operates basically by the passage of an alternating current through water, which, since it offers resistance, becomes hot and boils providing steam as the current flows. In practice, the water in Electrode boilers is usually heated by means of 3 – phase A.C., three electrodes or multiples thereof being placed in the water with the tank solidly earthed and connected to the neutral. (There is a similarity in many respects to a star-connected wire resistance with its neutral point earthed.) The electrodes are also surrounded by a neutral shield which serves to protect the boiler shell and many shells are still in use after decades of service. The heat generated in watts is directly proportional to the amount of current taken and the general formulae for 3 – phase power is: P = √3 VI where V and I are line values and 1 KW produces approximately 3.1lbs of steam per hour. The amount of current taken depends on the conductivity and temperature of the water and the area of electrodes immersed, and it is the latter variable which is controlled to meet the steam demand and so maintain a constant working pressure. This is achieved by pumping water into the boiler to increase the area of Electrode immersion, or discharging water from the boiler back into the feed tank to decrease the area of Electrode immersion. Pressure control is achieved by a similar system; the pump feeding water into the boiler is stopped when working pressure is reached and water is discharged back into the feed tank to reduce pressure. As this also reduces Electrode immersion, the boiler output is lowered to meet the steam demand. COLD START All H.V.E. electrode steam boilers have an automatic cold start feature to avoid excessive thermal shock to the boiler shell, gaskets and fittings. As the boiler fills the current also increases and when this reaches approximately 10% of the rated boiler output the start up relay (SUR) energises and switches off the feed pump. Heat produced due to the current flow will result in a rise in conductivity of the water, allowing the current to rise further still to approximately 15% - 20% of the rated boiler output. A thermostat located on top of the main flange of the boiler senses the shell temperature and when this reaches approximately 90 deg C disconnects the start up relay, allowing the boiler to be controlled by the current control relay (CCR). NOTE: If the start up current exceeds that set on the current control relay (due to a low

current setting on CCR) then the latter has priority and would take control of the boiler irrespective of the shell temperature.

LOAD CONTROL Load control is achieved by the current control relay (CCR). This microprocessor based controller monitors the current taken by the boiler and via it 2 set points maintains the boiler output within a pre-set band. The 2 set points can be programmed in, namely set point 1 (SP1) and set point 2 (SP2) to suit different processes and settings can be recorded for later use. When the current control relay is reprogrammed using recorded data, performance characteristics, accuracy and resolution are precisely the same as before. Any data entered by the user is retained by EEROM for up to 10 years without back up power. New data entered overwrites previous entries. The system permits at least 10,000 data changed before any degradation occurs but more typically this figure is 1000,000. Access to the programmable functions is achieved by single key selection which steps the display through each function in turn. The value or status appropriate to the function is displayed automatically, allowing the user to record the present data or to alter it if required.

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SET POINT

Set point 1 (SP1) – (HIGH CURRENT) is set at normal working current + 5%. If current taken exceeds that set on SP1 then solenoid valve (SV2) is energised and water is discharged from the boiler shell back into the feed tank. When the current taken falls back below SP1, then solenoid valve (SV2) will de-energise. Set point 2 (SP2) – (LOW CURRENT) is set at normal working current. If current taken falls below that set on SP2 then the feed pump will be started and run until current taken is above SP2, when it will stop I can be seen from the above that boiler output will be maintained within a present band, any excursion beyond set point activating either the feed pump or solenoid valve (SV2) Note: To prevent ‘hunting’ i.e. fast cycle times between pumping in and emptying shell timed delayed outputs are fitted in the current control relay CCR. These apply to SP1 and SP2 and initiate a delay before either set point can turn on or off. These are programmed at 3 seconds but may be altered by the user if the system permits. Feed Pump Control As stated under load control the pump is normally started and stopped for load modulation by means of the current control relay CCR. However the feed pump also has a hand control switch on the boiler command module and is also controlled by the Low Pressure switch LP.SW. The High water level controller WLC1, also stops the feed pump in the event of water level rising too high within the pressure vessel. This is a low voltage probe type and the probe length has been factory set to limit the water level to a point ¾ of the way up the level sight glass fitting of the boiler. Therefore it the water level rises to this point the pump will automatically stop until the level falls again. The reason fo a high water level as described above is usually that the feed water is too pure and therefore under these conditions a HVE patented conductivity controlled dosing system should be used. This option can be ordered with the boiler or a retro-fit kit can be supplied at a later date if required. Conductivity Controlled Blowdown The HVE Electrode Steam boiler also incorporates a patented conductivity controlled blow down system. This is designed to automatically discharge, to drain accumulated impurities in the feed system when these have increased after a period of steaming to an unacceptably high level. The result of this build up of impurities brings about an increase in conductivity resulting in the water level in the boiler getting lower and lower for the same output in terms of current. The HVE system senses this condition when the water level has fallen to a minimum low limit as detected by the water level controller WLC2. This level has been factory set and is approximately 50mm above the bottom of the electrodes. Therefore if below this level of immersion the current control relay (CCR) detects a current above that set on SP1 then the Blow down solenoid valve (SV1) is energised, discharging concentrated impurities from the bottom of the boiler shell to a suitable drain. The effect of this discharge of impurities from the boiler shell is to replace highly conductive water with clean water from the feed tank thereby reducing the conductivity to within acceptable limits as seen by the low water probe and the current control relay. Normal running condition will therefore be with a water level and hence depth of immersion of the electrodes, between the upper low conductivity level and the lower high conductivity level. A blow down test button is provided on the command module to test the controlled blow down solenoid valve, and this illuminates when the solenoid valve is energised either in service or test.

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The blow down solenoid valve is also energised whenever the boiler control switch is set to the ‘OFF’ position (with main MCCB switched ON). Conductivity Controlled Dosing As described in FEED PUMP CONTROL, high water levels are usually a result of a too pure feedwater and the HVE patented conductivity controlled dosing system adds a little sodium sulphite based solution to the feed system. When the High water level is sensed by WLC1, the dosing pump timer TD1 is energised and dosing solution is automatically injected into the feed tank until the time set on TD1 has expired. This will result in an increase in conductivity, causing current to increase and thereby causing the water level to be reduced away from the high water level probe. I.e. The current control relay detects its set point current with a lower water level and so stops the feed pump at the lower water level. Main Air Circuit Breaker This is hand operated and is fitted with thermal and magnetic overloads to protect against short circuits. ON/OFF indication is shown by the position of the breaker operating toggle. The toggle will take on intermediate position (i.e. between on and off) when tripped. Undervoltage Trip (where fitted) This will trip the main breaker if there is a loss in supply to the boiler, and prevents unattended start up on supply restoration. The breaker is reset by pushing toggle to the ‘OFF’ position. Breaker Indication Pilot Lights (where fitted) These pilot lights show when the breaker is in the ON or OFF position. Trip Indication Pilot Light (where fitted) This pilot light indicates when the breaker has tripped due to overload or short circuit. Trip Contacts (for remote indications) (where fitted) This consists of a volt free changeover contact wired to terminals. This can be used for remote indication that the breaker has tripped. NOTE: This option cannot be fitted if trip indication lights are fitted. Auxiliary Contacts (for remote indication) (where fitted)

This consists of a volt free changeover contact wired to terminals. This can be used for remote indication of breaker ON/OFF status. NOTE: This option can only be fitted when undervoltage trip is fitted. Feed Tank The integral feed tank has a high pressure ball valve into which the feed water supply should be connected. An overflow is also provided along with a drain valve and these would be connected to a suitable drain. A condensate return connection is also provided along with an exhaust connection to vent the vapour build up within the feed tank after a prolonged period of steaming. Water Supply Solenoid Valve (where fitted)

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The water level within the feed tank is controlled via water level controller WLC3. This is a low voltage probe type, and two probes (high-low) are fitted into the top of the feed tank. When the water level in the feed tank falls below the low level probe, solenoid valve (SV3) is energised filling the feed tank under mains pressure until the water level reaches the high level probe, when solenoid valve (SV3) will be de-energised. It is recommended that this form of feedwater supply is used in conjunction with Base Exchange water softeners, which often require a much greater flow to work satisfactorily. CCR SETTING UP PROCEDURES

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User controls and displays are provided by five segment LED digital readout, four flush mounted keys and three LED indicators. The arrangement is shown in figure 1 and summarised in table 1.

Figure 1 - Front Panel Layout

For simplicity, the front panel components shown on figure 1 are identified as follows; .LHD – ½ digit .PGM – Programme .D1 – Decade 1 .SP1 – Set point 1 .D2 – Decade 2 .SP2 – Set Point 2 .D3 – Decade 3 .D4 – Decade 4

Table 1 Front Panel Guide

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Component Function Operation

(Scroll)

Used to scroll through, and if required, change

ADP set up data.

Press to select required data (Table 3.2). First press displays function code. After 1 second data relating to code is displayed. After all functions have been scrolled, display reverts to input variable and updates ADP memory with new data.

(Digit select)

Select display digit to be changed

Selection indicated by flashing digit and flashing PGM.

First press selects LHD

Second press selects D1

Third press selects D2

Fourth press selects D3

Fifth press selects D4

Sixth press returns to LHD select.

(Digit

increment)

Increments selected display digit

Each press steps display through complete numerical range. When ADP is in monitor mode, this key freezes display and turn on PGM continuously.

(Reset)

Resets display to input variable and enters new data in to ADP

memory

Press once to restore display of input variable.

LHD (½ digit) Displays -, -1, 1, decimal point or blank

Display set by input variable or Digit Select and Increment keys.

D1 to D4 (decade 1 to

4)

Displays 0 to 9 or decimal point.

Display set by input variable or Digit Select and Increment keys.

PGM (program)

Flashing, indicates PGM mode selected to

change ADP data. When steady,

indicates display of input variable is on

hold.

When Digit Select is pressed, PGM flashes with selected digit.

When Digit Increment is pressed first, PGM stays on to show input display is frozen.

SP1 (Set Point 1)

Indicates SP1 status, O/P 1 relay energised

or Triac 1 on.

Turned on when O/P 1 relay is energised or triac 1 on.

SP2 (Set Point 2)

Indicates SP2 status, O/P 2 relay energised

or Triac 2 on.

Turned on when O/P 2 relay is energised or triac 2 on.

1. Preparation.

1.1. Switch on power

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1.2. If the keypad disable links have been removed, fit them in the enable positions as shown in figure 2.

Figure 2 - Keypad Enable Links

1.3. Refer to figure 1 and Table 1 throughout setting up procedure.

2. Setting Up

2.1. Press the scroll key until required set point codes is displayed i.e. SP1 or SP2; wait

until code disappears and is replaced by all zero’s or value of previous entry.

2.2. Press digit select to select display window and DIGIT INCREMENT to select required digit until desired value is displayed.

2.3. When the desired value is displayed, press R. This will set the data into memory and

revert to display of load current. 3. Set Point Valves

3.1. SP1 This should be set equal to SP2 = 5%.

3.2. SP1 This should be set to maximum current required. (Note under no circumstances should SP1 be set more than that indicated on CCR. This will cause an abnormally high water level and will result in the circuit breaker tripping out on overload.

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4. Keypad Disable

4.1. Unclip the CCR facia

4.2. Two keypad disable links are provided as shown in figure 2 and figure 3. LINK A is used to disable all four keys. LINK B disables the DIGIT select and increment keys which allows interrogation of programmed functions but prevents data changes.

4.3. To disable all CCR keys, fit LINK A vertically as shown in figure 3. To disable the

digit select and increment keys, fit link B vertically as shown.

NOTE: Never fit both links vertically in their disconnected positions at the same time.

4.4. Refit the facia.

Figure 3 - Keypad Disable Links

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INSTALLATION The boiler should be sited on a level floor of adequate strength to support the whole unit weight (as given in our data sheet). The mild steel channel chassis of the boiler provides for uniform weight distribution and no special foundation or concrete plinth is required. Adequate space should be left round the unit for easy access and maintenance of the boiler switchgear and ancillary fittings. Headroom over the boiler pressure vessel should be sufficient to allow removal of the electrode assembly interior as indicated in data sheet (V). The main three phase supply and neutral cables (or bus bars), fed from a suitably fused or switched supply, should be connected on to the circuit-breaker copper bus bar terminations and the appropriate neutral/earth bar connection provided. The removable cable entry plate can be removed and drilled to accept cable glands or replaced with a suitable spreader box for top cable entry. (This box is not normally supplied but is available as an optional extra). Steam line, feed water, drain and blow down connections should be made up to the appropriate fitting as shown on General Arrangement Drawing attached. Blow down connections should be taken to a suitable blow down tank or pit where live steam can be discharged automatically with complete safety. (We can advise and supply a suitable unit as an optional extra). Tighten electrode bushnuts. On completion of connection of these site services the boiler is ready for commissioning. COMMISSIONING It is strongly recommended that our own service engineers carry out the commissioning. This service is available at a minimal cost plus all expenses. Commissioning Procedures 1. Check that main steam and blow down valves are closed and that the feed tank is filled and the water supply is on. Check that the boiler is empty. 2. Check that boiler ON/OFF and pump ON/OFF switches are off. 3. Make the main incoming supply alive to the boiler air circuit breaker. 4. Check feed pump rotation, by closing main ACB, closing boiler ON/OFF switch,

momentarily close feed pump ON/OFF switch at the same time observing rotation of feed pump. If incorrect rotation, switch all above switches to OFF position and reverse any two of the 3 phase leads on the feed pump motor.

5. When the pump rotation is correct close the boiler ON/OFF switch but leave the pump

ON/OFF switch in the OFF position. Now set the current control relay CCR to the required setting (see CCR setting up procedures). When this is done, turn the pump ON/OFF switch to the ON position. The feed pump will now inject water into the boiler and after 30/40 seconds, water will appear in the bottom of the sight glass fitting, continuing to rise. The bottom tips of the electrodes are level with the centre of the bottom gauge glass fitting, so that when water can be seen in the gauge glass the electrodes as indicated on the current control relay CCR. As soon as this current level has risen to approximately

10% of the full load value, the pump should stop. 6. This will take approximately 10/15 minutes after which time the shell thermostat will sense

adequate heat saturation of the vessel, gaskets and fittings and so change over the load control from SUR to CCR.

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The main steam valve may now be gradually opened allowing steam to pass to the equipment or steam distribution system. This will result in the boiler having to pick up load to meet the demand.

NOTE: Great care must be exercised when opening the main steam valve on to a cold system, ensure that this is done very slowly (just cracking the valve at first). Thereby ensuring that there is not appreciable pressure drop in the boiler shell. As the equipment gradually heats up, the main valve can be opened further until it is fully open, but at all times ensuring that it is not opened so quickly as to drop the pressure in the boiler vessel. AUTOMATIC CONDUCTIVITY CONTROLLED BLOW DOWN The rate at which this automatic blow down discharges water can be adjusted with the bleed valve set to a position that allows automatic blow down without appreciably dropping the boiler shell pressure. This adjustment to the bleed valve can be carried out and checked when the boiler is on full load by operating the blow down test button and observing the change of pressure on the pressure gauge. AUTOMATIC CONDUCTIVITY CONTROLLED CHEMICAL DOSING ((WHERE FITTED) The only adjustment necessary to this system is to select the highest delivery rate on the dosing pump regulator. The unit will automatically inject a chemical solutio9n into the feed water only when the conductivity level of the system has fallen to a low level (system water too pure), as indicated by a high water level in the gauge glass. In areas where the water supply is very soft (i.e. with a low conductivity level), initially, on commissioning, it may be necessary to add a little of the chemical solution to the feed tank to get the boiler started (approximately ¼ litre should be adequate). After the initial start, no further chemicals should be added. We strongly recommend that the services of a water treatment specialist are obtained and their advice and recommendations for water treatment is followed. We can offer and provide this service via an internationally reputable company is requested to do so.

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OPERATION TO START UP THE BOILER (STANDARD MANUAL START UP/SHUT DOWN) 1. Check that main steam valve is closed. 2. Close main blow down valve. 3. Open feed water valve between feed tank and feed pump. 4. Close main circuit-breaker. 5. Close boiler ON/OFF switch. 6. Close pump switch. The boiler feed pump will now run and when water reaches the electrodes current will begin to flow between them and will be indicated on the current control relay VCCR. When the current reaches a value equal to the setting of the low load start up relay (SUR) the pump will stop. No further action is required by the operator at this time as the boiler will gradually produce heat and subsequently steam at this low level controlled rate until operating temperature of the shell is reached and working pressure is indicated on the pressure gauge. At this point, approximately 10/15 minutes after switch on, the main steam valve can be slowly opened. As this valve is gradually cracked open, ensure that the steam pressure within the boiler is not allowed to fall below 50 p.s.i.g. (3.5 bar). As the steam distribution system and equipment requiring steam gradually heat up, the main valve can be opened progressively and slowly until fully open. The boiler can now be left to operate automatically modulating its output to meet the load demand of the system. If the boiler rating and output is much greater that the steam demand at any time, (indicated by the boiler pressure exceeding the set point of the high pressure switch and resulting in excessive operation of the solenoid valve dumping boiler water back into the feed tank), then the setting of CCR can be reduced to a value where the boiler output is approximately equal to the demand of the system. This will avoid excessive discharge of boiler water and steam back into the feed tank. NOTE: 1. During periods of steaming occasionally: 2. Check that the chemical dosing container is adequately filled with chemical solution. 3. Check the water level in the gauge glass; this should ideally be approximately half full to

the top of the gauge tube for full load output.

4. Check the load level as indicated on CCR is within the normal limits for the output rating of the boiler.

5. Open the main blow down valve for a few seconds when the boiler is at normal working

pressure to discharge any accumulated sediment at the bottom of the boiler. This should be done as frequently as recommended by your water treatment specialist and will vary according to the quality of water supply in any area.

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TO SHUT DOWN THE BOILER 1. Switch off the pump switch. 2. Partially close main steam valve and wait for pressure to build up. 3. At maximum pressure the solenoid valve will open discharging boiler water back to feed

tank, thereby shedding all load to zero. 4. When zero load is indicated on CCR trip main air circuit breaker. 5. Open main steam valve until pressure falls to 50 p.s.i.g. (3.5bar), or less. 6. Open main blow down valve, (gradually) and when fully open, leave open. 7. Switch off boiler ON/OFF switch. 8. Close water valve between feed pump and feed tank. NOTE: It is important to leave the blow down valve fully open when the boiler is not required. This allows the hot boiler shell to cool down without creating a vacuum which would otherwise suck water from the feed tank, fully flooding the boiler shell. MAINTENANCE When ordering spares, the boiler serial number, model number, rating and part number as shown on enclosed drawings must be stated. Before attempting any maintenance isolate the electrical supply. Routine Maintenance Ensure that the plant is kept in a clean condition, free of all steam and water leaks. Weekly 1. Blow down the water level sight glass once a week and if badly discoloured and dirty,

dismantle the gauge glass assembly (when the boiler is off load and at zero pressure and isolated), and pull through a clean soft cloth or renew the glass tube.

2. Check the feed pump gland and if necessary tighten the gland packing collar tightly and

evenly. (Do not over tighten). 3. Do not permit leaks from gauge glass – replace sealing washers. 4. Do not permit leaks from gauge cocks – retighten or repack. 5. Do not permit leaks from main steam valve – tighten or repack. 6. Check level of chemical solution in dosing tank. 7. Test automatic blow down solenoid valve by pushing blow down test button for 2

seconds. 8. Check level of water in gauge glass at normal full load, this should be approximately half

way up the gauge glass.

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9. Check over flow connections to feed tank, if losing water, check internal ball valve for correct seating.

10. Blow down the water level probe chamber to discharge any sediment, open blow down valve for approximately 5 seconds.

11. Check chemical dosing pump and delivery connections. 12. Checks feed pump for leaks and lubricate as recommended in pump manufacturers

instructions attached. Once a Year The boiler pressure vessel will have to be opened once every year for Insurance Company internal inspection. To facilitate this: 1. Isolate all electrical supplies. 2. Isolate all inter-connected steam supplies. 3. Valve off water supply. 4. Dismantle boiler electrode top cowl and bus bar covers. 5. Disconnect bus bar connections to electrodes. 6. Remove all top flange holding down nuts. 7. Lift out the complete electrode interior assembly with suitable block and tackle. 8. Clean and remove scale from boiler shell interior, electrodes and neutral shield. 9. Check electrode insulator bushings, do not disturb these and their seals unless

necessary. Check for tightness on clamping nuts. 10. Remove safety valve and dismantle for insurance company inspector to examine valve

seating. Re-assemble and adjust setting after re-commissioning boiler. Raise boiler pressure after re-commissioning to approximately 10% above working pressure of boiler and adjust safety valve to blow off at this setting – lock setting nuts at this pressure.

11. Replace main top flange gasket with a new gasket, first carefully cleaning both flange

faces and apply a good jointing compound to both faces. 12. Re-connect electrode busbars and replace electrode cowl and bus bar covers. 13. Check all control panel components for cleanliness, tightness of connections and signs of

burnt contacts on relays and pump starter, replace as necessary. Do not alter timer settings.

14. Fit new gauge tube with new sealing washers (do not over tighten). 15. Dismantle and clean both solenoid valves, examining the valve seatings for scale and

wear, replace if necessary. Remove and clean strainers from feed pump suction line and solenoid valve line to feed tank. After re-assembly, restart the boiler and test for steam leaks etc. If after reaching full temperature and working pressure, a slight leak occurs at the top flange gasket, switch off, shut down boiler to zero pressure and re-tighten top holding down nuts while the vessel is at almost operating temperature.

16. Feed pump, follow manufacturer’s instructions for lubrication etc.

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17. Replace any faulty indicator lamps in the control panel. FAULT FINDING Excess Current Excess current will normally occur only under fault conditions, and will result in the circuit-breaker automatically switching itself off. ON NO ACCOUNT MUST THE CIRCUIT BREAKER BE RE-CLOSED UNTIL THE FAULT HAS BEEN INVESTIGATED, AND THE FAULT CLEARED. Always empty the boiler and follow starting procedure if the circuit breaker trips. Excess current can be brought about by setting the current control relay CCR at too high a value when first switching on, or by failing to empty the boiler the nights before, or by re-closing the blow down valve after emptying the boiler. WHEN NOT IN USE, THE BLOW DOWN MUST BE LEFT OPEN TO PREVENT THE COOLING BOILER FROM CREATING A VACUUM. Possible Cause of Excess Current Apart from the reasons given above, excess current may, after considerable use, depending on the water supply, be caused by the presence of scale in the boiler. If caused by scale, it will probably have been observed in previous weeks that the water level had been getting abnormally high. The only remedy is to remove the boiler interior, and remove all the scale from the electrodes, the shield surrounding them, the boiler walls and the base of the boiler. Ensure that the blow down valve is clear. Scale may be removed by chipping, scraping, filing, or by a cleaning acid, carefully observing the maker’s recommendations. A new joint ring must be used for the boiler top cover. When descaling, check the distance from the ends of the electrodes to the underside of the top cover. This distance should be equal to the distance from the top of the boiler flange to the centre line of the lower gauge glass fitting. If a shorter length for the electrodes is recorded, they must also be replaced. Similarly, if the electrodes are found to be of unequal length they must be renewed. An alternative is to carry a spare boiler interior complete with top cover plate, assembled ready for use. The scaled interior may then be quickly exchanged, then cleaned as time permits. It is a sound plan to remove scale from the water level fittings, from the magnetic valve, and from its seating, to avoid possible future trouble. A magnetic valve partially blocked by scale will also cause the circuit breaker to trip.