Adca Training. Part 2

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1 Adca Training Part 2 This presentation is only a guideline, that can only be completed by a trained personnel. (This document s total or partial use and/or reproduction is only allowed if the reference to the source is kept)

2 Part 2 The Boiler Equipment Used on Boilers Water Treatment Bottom Blow down TDS Control Energy Recovery Deaerators Part 4 Pressure Reduction Safety Relief Valves and Other Steam Valves Part 5 Control Valves Components of Control Valves Humidification Part 3 Pipeline Sizing Water Hammer Steam Trapping Condensate Removal

3 Steam Feedwater Feedtank Process Condensate Boiler

4 One can simply define heat generator as an equipment design to energy production through fuel combustion. Heat generators are mainly built of two distinct elements: Combustion chamber where the fuel is burned, producing hot gases that will act as fluid heater. Metallic body or generator itself closes the fluid to be heated, that will be the means of transportation for produced energy. Combustion chamber and main generator s project may vary according with type of boiler and fuel. In compliance with legislation in force generators are supplied with several auxiliary equipments appropriate to monitoring and assure generator s good functioning, such as: temperature and pressure indicators, safety valves, pressostats, thermostats, pumps, valves, instrumentation, etc.

5 By virtue of the huge variety of factors, heat generators classification is a very complex task. Here follows some examples: According to Fuel Fluid Produced Possibilities Solid, Liquid or Gas Hot or Superheated water, Steam, Diathermic oil, Hot air, Number of passes of combustion gases 1 to 4 Heating chamber Burners Pipes Inversion chamber Furnace, Fire tubes, Pressure jet, Rotary Cup, Fire tube or Water tube Wet, Dry back,

6 Feed Water Steam Burner Fuel

7 The hot gases from fuel combustion cross the main chamber (1 st pass) and the smoke tubes (2 nd pass), transfer the heat to the surrounding water. As far as the water reaches saturation temperature, steam start to be produced, being accumulated in the space above, ready to be delivery to the system. Burner

As far as the water reaches saturation temperature, steam start to be

8 The hot gases from fuel combustion cross the main chamber (1 st pass) and the smoke tubes (2 nd and 3 rd pass), transfer the heat to the surrounding water. As far as the water reaches saturation temperature, steam start to be produced, being accumulated In the space above, ready to be delivery to the system.

9 Some typical control and safety equipment... Cocks and gauge glass for water level monitoring. The safety valve (s) function is to protect the boiler shell from overpressure and explosion.

Level control probes can be installed internally in the boiler shell or

10 For efficient and safe operation a steam boiler has also level controls and level alarms. Level control probes can be installed internally in the boiler shell or externally using appropriate level control chambers connected to the boiler shell. Alternatively, float control systems are still used by some manufacturers.

11 Water quality is extremely important on the exploration of a thermal power station. The use of hard water or poorly treated water may cause accidents or irreparable damages on the generator and piping, apart from decreased heat transmission. Water quality control must be done periodically. An effective treatment must keep it within the required parameters. Generally, water for a heat generator must be less hard as possible ( 1ºfH), be free of suspension solids, have alkaline Ph (8,5 minimum) and low in O2 ( 0,02mg/l) and CO2.

12 Most current process of reducing water hardness is through ion-exchange method: The raw water is guided through heavy-duty resin which has been enable by exchangeractive sets to exchange cations or anions. The calcium and magnesium ions are absorbed during the softening procedure while adequate amounts of sodium ions capable of exchange (Na+) are released into the water. The exchange resin has physically conditioned a limited capacity and is exhausted after a certain number of water throughputs. The regeneration of the water softening system is performed by means of a salt solution. Ph correction, which value is associated with CO2 content may be done through a controlled injection of chemicals for which is necessary adequate dosing instruments. O2 and CO2 can be eliminated by chemical or thermal process. The chemical process uses sometimes some products non-recommended in food industry,thus the thermal process offers more advantages as: O2 Elimination CO2 elimination And by consequence, Ph correction

operational use of steam boilers. The volumetric systems work in dependence on the flow volume.

13 The timing of regeneration can be selected manually or automatically. If the softener is electronically controlled by a timer, the regeneration has to be selected outside the operational use of steam boilers. The volumetric systems work in dependence on the flow volume. The duplex design is specially suitable for continuous operation, because the regeneration is performed alternatively without interruption of the soft water supply.

14 During the vaporisation process the suspended solids in the boiler water are collect in the bottom of the boiler in the form of sludge. Manual blowdown valves are specially designed for application on steam boilers removing the concentrations of solids (sludges) avoiding boiler damages, unstable water level control and other typical problems. VPA26S (Manual) The valves are provided with a manual handwheel. Valve aperture cycles depends from the boiler manufacturer specification or water treatment specialists.

15 During the vaporisation process the suspended solids in the boiler water are collect in the bottom of the boiler in the form of sludge. Automatic blowdown valve are specially designed for application on steam boilers removing the concentrations of solids (sludges) avoiding boiler damages, unstable water level control and other typical problems. VPA26S (Automatic) The valves are provided with a diaphragm actuator suitable for compressed air motive fluid. The opening signal is supplied by an automatic intermittent control unit but they can also have alternative manual operation. Valve aperture depends from the boiler manufacturer specification or water treatment specialists.

16 Some impurities remains in the boiler water in the form of dissolved solids and so they cannot be eliminated trough the bottom blowdown. The concentration of this dissolved solids naturally increase with steam production. When this concentration is high, and in order to restore the right levels, some of the boiler contents must be purged. Lost water will be replaced by lower TDS concentration feedwater, replacing the correct parameters. A typical problem of excess TDS concentration is water foaming which origins bad boiler performance and wet steam.

17 When the TDS concentration reaches the set point measured by the conductive probe, a controller gives an open signal to the blowdown valve. Conductivity probe Blowdown controller Adcatrol Blowdown control valve To BEX for expansion and drain or flash vessel for energy recovery. Sample Cooler Boiler manufacturer and water treatment specialists usually indicates the maximum permissible concentration.

The blowdown and cooling units are used in the modern boiler houses to cool hot waste water and steam boiler blowdown

The waste water is discharged into the unit which is at atmospheric pressure and the cooling water enters via a control

EH Exhaust Head If flash steam can not be recovered or discharged to atmosphere an additional condensing water spray system

18 The blowdown and cooling units are used in the modern boiler houses to cool hot waste water and steam boiler blowdown before to discharge into a pit or drain to prevent thermal pollution and pipe system damages. The waste water is discharged into the unit which is at atmospheric pressure and the cooling water enters via a control valve controlled by a thermostat, mixing with the hot water. EH Exhaust Head If flash steam can not be recovered or discharged to atmosphere an additional condensing water spray system (optional) can be supplied. This one is fitted in the top of the unit and can be controlled directly either by another thermostat or the same command used for the automatic blowdown valve control. BEX Blowdown Expansion Vessel

Sample coolers prevent steam flashing-off from hot

will result in an incorrect water sample.

Hot Sample IN Hot Sample IN Cooling Water OUT Cold

19 Sample coolers prevent steam flashing-off from hot pressurised liquid samples, which can be dangerous and will result in an incorrect water sample. Basically they operate as a small heat exchanger. Hot Sample IN Hot Sample IN Cooling Water OUT Cold Sample OUT Cooling Water IN Cooling Water IN SC32 Cold Sample OUT SC32/F Cooling Water OUT

20 For high pressure boilers and continuous analysing, special execution is necessary. Clean steam systems also require a specific design and finishing surfaces. SC332 SC432 SC532 Ts= 550ºC Ps=245 bar SC32P Clean Steam Internal Finished to 0,5 micronsra

Flash steam produced can be condensate inside the vessel by using injectors submerged in the water or

21 Flash steam One of typical applications for the use of flash vessel is precisely in recovering flash steam from the boiler blowdown. This energy recovery can be used for feedtank preheating, saving fuel. Flash steam produced can be condensate inside the vessel by using injectors submerged in the water or it can simply be used on the deaerator head. Blowdown from boiler Adca RV.../A Flash Vessel Contaminated water

22 Condensate Flash Steam Make up Water Flash Vessel ADG Atmospheric Thermal Deaerator with Dome Flash Steam Inlet Hot Water Heat Recover from Residual Blowdown Cold Water

23 Since many years ago it is common to recover condensate from steam systems to the boiler feed tank, saving water and energy, reducing water treatment chemicals, costs and consequently reducing CO2 emissions. In some systems, the amount of recovered condensate and correspondent temperature is so high that the water feed tank temperature rise to the boiling point. Thus, most of the recoverable energy is lost in the form of flash steam through the vessel vent pipe. Besides, boiler feed pumps can cavitate (see NPSH) and be damaged. FRECO Flash Steam Heat RECOvery, consider the energy recovery downstream of boiler feed pump. High pressure avoids the water boiling. (FRECO can be supplied as a skid mounting system for easy installation and commissioning). A raised of 6ºC in feed water temperature, corresponds to a saving of approximately 1% fuel.

24 Flash Steam Steam Condensate Hot Water Cold Water

25 A thermal deaerator is actually a deaerating feed water heater, which combines water heating, storage and deaeration capabilities. Water is stored in a under pressure vessel typically about 3 bar g in order to aloud it to be kept at a temperature above 100ºC. Thermal deaeration takes place in equipments especially designed for the job. There are existing two main kinds: Tray type deaerators Spray nozzle type deaerators Tray type is by far the most used doing to is simplicity, versatility and performance. Atmospheric deaerators also called partial deaeration systems or semi-deaerators are most times the economic choice for boiler capacities up to approximately 2000 Kg/h.

Atmospheric semi-deaerators are designed to heat boiler feed water and to reduce oxygen and carbon dioxide (oxygen values in the feed water of less than 1,6 mg/l, can be achieved).

26 Atmospheric semi-deaerators are designed to heat boiler feed water and to reduce oxygen and carbon dioxide (oxygen values in the feed water of less than 1,6 mg/l, can be achieved). Remaining oxygen can be completely removed using oxygen scavenging chemicals. Basically the complete system consists of a storage vessel, a deaeration head section and a vent. Hot return condensate is injected in the bottom of the storage vessel using an adequate sparger pipe and softened make-up water is introduced in the deaerator head to be heated by a contact cascade flash steam heating system (counter-current flow) coming from the vessel. Part of dissolved gases are liberated from the water at this point and they are liberated to atmosphere trough the flash steam vent line. Condensate Recirculation Condensate Vent Make up Water Flash steam ADG Atmospheric Semi-Deaerator Dome The semi-deaerated water then falls to the storage vessel below, where a steam injection system will provide an additional deaeration.

27 Make up Water Complete unit supplied including all the necessary instrumentation for temperature and level control. ADG/V Complete unit

Thermal deaerators are designed to heat boiler feed water and to reduce oxygen and carbon dioxide (oxygen values in the feed water of less than 0,02 mg/l - 0,02 ppm, can be achieved).

Return condensate and softened make-up water are introduced in the deaerator dome to be heated by a contact cascade steam heating system (counter-current flow).

28 Thermal deaerators are designed to heat boiler feed water and to reduce oxygen and carbon dioxide (oxygen values in the feed water of less than 0,02 mg/l - 0,02 ppm, can be achieved). Remaining oxygen can be completely removed using oxygen scavenging chemicals. Basically the complete system consists of a storage vessel, a deaeration section and a vent. Return condensate and softened make-up water are introduced in the deaerator dome to be heated by a contact cascade steam heating system (counter-current flow). The majority of dissolved gases are liberated from the water at this point and they are liberated to atmosphere trough the flash steam vent line. The deaerated water then falls to the storage vessel below, where a steam blanket ensure that no gases are reabsorbed. A sparger pipe is installed inside the tank at the bottom level providing the necessary heating energy. A second low pressure steam supply can also be necessary (double stage). Condensate Steam Make up Water TDG Thermal Deaerator Dome Double Stage

29 Complete unit supplied including all the necessary instrumentation for temperature, pressure and level control. Condensate Make up Water TDG/V Complete unit

V = 18000Kg of Water T1=5ºC T2=65ºC Cp of Water=1 Kcal/Kg ºC ΔT = 65º-5º=60ºC Steam = 3bar g Steam is supplied at 3 bar.

30 Find the energy required to heat up the tank content, from 5ºC to 65ºC in 1,5 hours 90. m x Cp x T x 60' Q 90' Kg x 1Kcal/Kg ºC x 60º x 60' Q 90' Q Kcal/h How much Steam? V = 18000Kg of Water T1=5ºC T2=65ºC Cp of Water=1 Kcal/Kg ºC ΔT = 65º-5º=60ºC Steam = 3bar g Steam is supplied at 3 bar. From steam tables we can see that at this pressure the total enthalpy of steam (hg) at this pressure is 654,6 Kcal/Kg. SI-115 Q MKg/h hg (T2 x Cp) M Kg/h ,6 (65ºC x 1Kcal/Kg ºC) M Kg/h 1221,2Kg/h SI-125

Using the same formulas it is possible to find the steam flow rate necessary to heat the tank material and depending from insulation, ambient temperature, vessel design, etc, it is also possible to

31 Using the same formulas it is possible to find the steam flow rate necessary to heat the tank material and depending from insulation, ambient temperature, vessel design, etc, it is also possible to determine the steam flow rate necessary to make up for the heat losses from radiation and water surface. Practical calculation may accept an allowance based in a percentage of around 10%. So, for our example we will consider 1221,2 Kg x 1,1 = 1343,4 Kg/h of steam. NOTE: The tank must have enough free volume for the mass of steam added during the heating process, 1343,4 Kg x 1,5 hr = 2015,10Kg. The final water volume will be than 18000Kg ,10Kg = 20015,10Kg. At 3 bar the SI 140 has a capacity of 800 Kg/h, so, for the application we need 1343, ,4 1,68 2 Steam Injectors SI 140 or 4,98 5 Steam Injectors SI The vessel design, dimensions and the particular application may recommend the use of one single big injector or more small units, with the equivalent total capacity.

Hot water (or other fluids) storage vessels for industrial purposes can be divided in two types: Accumulators Semi-instantaneous Any of these can be equipped with

ADCATHERM WAVE with external STSV Heat Exchanger In the first case there s a pre determined lack of time for heating a quantity of fluid that is ready to be used.

32 Hot water (or other fluids) storage vessels for industrial purposes can be divided in two types: Accumulators Semi-instantaneous Any of these can be equipped with internal coils or external heat exchanger. ADCATHERM WAVE with external STSV Heat Exchanger In the first case there s a pre determined lack of time for heating a quantity of fluid that is ready to be used. In this case, coil or heat exchanger s regeneration capacity during consumption process is not particularly relevant. On the second case there s a combination between accumulated volume and capacity of instantaneous heating. These two parameters combined must assure the maximum consumption calculated.

So, temperature control and correct condensate drainage can be crucial. Heating Coils can also be used to heat water in closed or open vessels.

33 Heavy fuel oils and other viscous fluids are stored in tanks heated by pipe coils or other alternative systems. This is necessary to provide the necessary temperature (viscosity) for pumping. Too high temperature can represent less viscosity and pump cavitation problems. So, temperature control and correct condensate drainage can be crucial. Heating Coils can also be used to heat water in closed or open vessels. Mainly on fuel oil systems and semiinstantaneous heaters the coil is frequently supplied with a sleeve, heating the oil locally as it is pumped out of the tank. BM20 The use of extruded low fin tube, has the advantage that it can improve the external surface and thermal performance (Adcatherm R- Coils).

Plate heat exchangers can also be used on steam applications under certain conditions, however, maintenance is more expensive doing to the high cost of gaskets.

34 Heat exchangers are equipments designed to transfer primary heat from one fluid to another. Shell and tube heat exchangers are very popular for steam to water heating since they can be designed for any temperature and has relatively low cost maintenance. Plate heat exchangers can also be used on steam applications under certain conditions, however, maintenance is more expensive doing to the high cost of gaskets. Ready to install packaged units including heat exchanger, control valve, steam trapping system and all the necessary accessories, are recommended since as a rule they save time installation, while guaranty the correct assembly of all critical components.

Heat Exchanger TUBE SIDE SHELL SIDE FLUID SATURATED STEAM WATER OPERATING PRESSURE bar bar INLET TEMPERATURE º C * º C OUTLET TEMPERATURE º C * º C FLOW RATE Kg/h * Kg/h or m3/h HEAT EXCHANGED

35 Heat Exchanger TUBE SIDE SHELL SIDE FLUID SATURATED STEAM WATER OPERATING PRESSURE bar bar INLET TEMPERATURE º C * º C OUTLET TEMPERATURE º C * º C FLOW RATE Kg/h * Kg/h or m3/h HEAT EXCHANGED (Option) KW or Kcal/h MODEL REQUIRED (Please select) STH (Horizontal) STV(Vertical) Remarks : * Not necessary in case of saturated steam. STH Horizontal installation ; STV Vertical installation. Before installing an instantaneous heat exchanger, one must certify that there s a sufficient steam flow or primary energy available for the effect. Storage vessels and semi-instantaneous systems can be inconvenient since they need more installation space. However, by balancing with initial heating time and the accumulation capacity it s possible to avoid undesired highs of energetic consumption. Storage Hot Water Vessels Closed Type TUBE SIDE VESSEL SIDE FLUID SATURATED STEAM WATER OPERATING PRESSURE bar bar INITIAL TEMPERATURE º C FINAL TEMPERATURE º C VESSEL CAPACITY Kg or m3 INITIAL HEATING TIME (In minutes) RECOVERY PERIOD (In minutes) HEAT EXCHANGED (Option) KW or Kcal/h VESSEL TYPE (Please select) HORIZONTAL VERTICAL AVAILABLE DIMENSIONS (Send a sketch) Straight length mm Diameter mm Remarks : A coil in a cylindrical vertical vessel should be as close to but not exceeding the diameter of the vessel as possible. A coil in a horizontal vessel is typically approximately 2/3 the length of the vessel Semi Instantaneous Hot Water Heater If the vessel is also operating as semi-instantaneous hot water heater, please confirm : HOT WATER CONSUMPTION m3 INCOMING COLD WATER TEMPERATURE º C DESIRED HOT WATER TEMPERATURE º C LENGTH OF TIME (IN MINUTES)

The mixer incorporates a safety device to ensure that live steam cannot accidentally be ejected, even if

36 The steam/water Adcamix mixers provide cheap, instant source of low pressure hot water by utilising existing steam and cold water supplies. The mixer incorporates a safety device to ensure that live steam cannot accidentally be ejected, even if for some reason the cold water supply fail. The temperature of water at the outlet of the Adcamix is easily controlled by using water and steam valves fitted to the inlets.

Condensate Air heating of large industrial spaces can be made through multiples systems available nowadays (gas, electricity, hot water, steam, etc).

37 Condensate Air heating of large industrial spaces can be made through multiples systems available nowadays (gas, electricity, hot water, steam, etc). High pressure Live steam A steam to air unit heater is composed by a coil and a fan, which forces air passage through the coil in order to heat it. Steam air heating batteries can also be used in central air conditioning units combined with filtration modules, direct steam humidification, etc. Steam to Air Unit Heater

38 From higher pressure plants where the condensate enters into the vessel, the flash steam is separated from the condensate. Through the top main connection of the flash vessel the flash steam is then supplied to the lower pressure steam network. The remaining condensate is discharged by an automatic float steam trap. (See Adca Training I). Flash Steam Installation of a flash vessel is particularly convenient when both high and low pressure steam equipments are present in the same plant since high pressure condensate can generate low pressure steam. To maximize the use of flash vessels, it is convenient to design them for the lowest possible pressure. Blowdown from boiler Model RV.../A ADCA Flash Vessel Remaining condensate Model RV.../L

39 Flash steam High pressure Live steam Low pressure Steam application Flash vessel RV /L Condensate

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