WATER-STEAM-CONDENSED CYCLE
BOILER WATER
A steam boiler requires softened, filtered water – crystal clear, and free of impurities.
If the available water comes from a well, it will be necessary to filter it through a silica sand filter and additionally, if it contains chlorine or odors, through an activated carbon filter, in order to eliminate all of the unwanted elements. It is also recommended to check the hardness of the available water and if greater than 0 parts per million (ppm), to run it through a water softener.
Note: If the water comes from the main water line and is already clean and clear with a hardness of 0 ppm, you may be able to avoid having to install a water softener and instead, treat the water with a chemical treatment and a system of scheduled blowdowns.
WATER SOFTENERS
If the available water is free of impurities and contains little chlorine, but has a hardness of greater than 0 ppm, running it through a water softener is recommended.
Water softeners require a minimum pressure of 15 PSI to operate effectively and, depending on the size, may require a pressure of up to 45 PSI.
FEEDWATER TANK
Water for the boiler, after treatment, gets fed to feedwater tank. The feedwater tank collects the condensate returns from the processes and makeup water is used to recover any losses.
Water is then fed to the boiler with a feedwater pump.
FEEDWATER PUMP
The boiler feedwater pump sucks the water from the feedwater tan and and injects it with pressure into the boiler.
STEAM BOILER
The heat transfer is carried out in a steam boiler. Fuel is put into a burner, which then generates a flame and combustion gases. The boiler water cools down the heat transfer surface area as its own temperature rises until it is converted into saturated steam upon reaching the operating pressure of the boiler.
(For example: If the boiler is working at a gauge pressure of 85 PSI, the boiler would be at an absolute pressure of approximately 99 PSI, producing steam with a temperature of approximately 327°F.)
DEFINITION OF BHP (BOILER HORSE POWER)
Boiler horse power is a theoretical term defined as “the production of 34.5 pounds of saturated steam per hour at atmospheric pressure and a temperature of 212°F, using boiler feedwater at the same temperature.” It is equivalent to a heat transmission of 8,436.56 Kcal/hour or 33,479 BTU/hour or 9.81 kW.
This calculation is entirely theoretical since boilers are normally fed water with a lower temperature and operate at a higher pressure which requires a higher temperature to evaporate.
Saturated steam, generated by the boiler, is sent to different end users. Normally, it passes through heat exchangers where it gives off its heat indirectly, and can as such achieve 100% condensate return.
*Note on Condensate Return: The amount of condensate that returns to the boiler is of utmost importance, requiring the installation of a good steam filter and a reliable steam trap in good working order. The boiler operator must continuously check that the trap is functioning correctly and that the condensates are successfully returning – uncontaminated – to the condensate tank.
A good rate of condensate return – free of any type of contamination – enables the boiler to achieve a higher level of operating efficiency, reducing the consumption of soft water, chemical treatments, energy (as the condensates return hot), and fuel, and improving the evaporation capacity of the boiler. If upon selecting the required boiler, you are aware that it will operate efficiently, with a high rate of condensate return, it is recommended that you order a larger condensate tank at the onset so as to avoid condensate spills in the future.
BOILER WATER QUALITY CONTROL
It is critical to carefully monitor boiler water. It should not contain even minimal amounts of acidity (corrosion), hardness (scale), contaminants, nor be subject to an ill-advised chemical treatment, as any of the above can lead to the formation of binding masses which prevent the internal surfaces of the boiler heat transfer area from cooling down. This, in turn, can cause serious damage to the boiler.
A good boiler water quality control system should include weekly, biweekly, and monthly reviews by a qualified chemical engineer, as well as the administering of a customized chemical treatment. Additionally, a scheduled system of blowdowns is required to rid the water of sludge and chemical products resulting from preexisting contamination.
BLOWDOWN SEPARATOR TANK
The blowdown separator tank is a pressure vessel that receives the sludge and residuals extracted during the blowdowns. The extracted elements leave the boiler at the boiler working pressure and as a result, are quite dangerous.
For example: If the boiler is working at a gauge pressure of 99 PSI, then the blowdown materials leave the boiler at this pressure, the equivalent of a 230 foot column of water, which can cause serious damage to the boiler piping.
The blowdown separator tank is a high risk pressure vessel, necessary in the operation of a steam boiler and whose construction must be carried out in strict accordance with the guidelines stipulated in the ASME Code. In order to bear the force of the output of the blowdowns, it must be able to expand in small space, lowering the pressure to the drain. The hot flash steam rises and is expelled safely through the wide upper connection of the blowdown tank.
Important recommendations:
1.The design engineer of a steam generation system must take into account the points addressed here. Especially in terms of the requirements of the water quality (softener).
2.Your calculation of requirement of steam must be based on values practical and not theoretical (14 Kg/hr by C. C.).
3.If you are going to have a high percentage of return of condensate, a larger feedwater tank may be required.
4.The boiler room must consider the installation of a blowdown tank.
5.The user must be aware of the importance of steam traps and their proper operation at all times.
BOILER WATER
A steam boiler requires softened, filtered water – crystal clear, and free of impurities.
If the available water comes from a well, it will be necessary to filter it through a silica sand filter and additionally, if it contains chlorine or odors, through an activated carbon filter, in order to eliminate all of the unwanted elements. It is also recommended to check the hardness of the available water and if greater than 0 parts per million (ppm), to run it through a water softener.
Note: If the water comes from the main water line and is already clean and clear with a hardness of lower than 80 ppm, you may be able to avoid having to install a water softener and instead, treat the water with a chemical treatment and a system of scheduled blowdowns.
WATER SOFTENERS
If the available water is free of impurities and contains little chlorine, but has a hardness of greater than 80 ppm, running it through a water softener is recommended.
Water softeners require a minimum pressure of 15 PSI to operate effectively and, depending on the size, may require a pressure of up to 45 PSI.
FEEDWATER TANK
Once the otherwise pure water has been softened, it gets deposited via a control valve into the condensate
receiver tank, from which, with the help of a feedwater pump, it is injected into the boiler.
It is called a “condensate tank” because in addition to receiving the softened water, the tank collects condensates which result from the steam that the boiler supplies to the heat exchangers or processes, once the steam transfers its heat or energy and changes from vapor to liquid water condensate.
FEEDWATER PUMP
The boiler feedwater pump sucks the water from the feedwater tan and and injects it with pressure into the boiler.
STEAM BOILER
The heat transfer is carried out in a steam boiler. Fuel is put into a burner, which then generates a flame and combustion gases. The
boiler water cools down the heat transfer surface area as its own temperature rises until it is converted into saturated steam upon reaching the operating pressure of the boiler.
For example: If the boiler operates at a gauge pressure of 6 Kg/cm2, the boiler would be at an absolute pressure of approx. 7 Kg/cm2, taking steam with a temperature of approx. 164°C (327°F). Each Kg of evaporated water will have a heat available from approx. 493.8 Kcal/kg of latent heat to be able to give it in a heat exchanger to condense (= return to your liquid state, at the point of saturation). (You can assign a larger amount taking the heat or energy of the liquid phase and lowering its pressure by the pressure drop through the trailersbiador of heat).
DEFINITION OF BHP (BOILER HORSE POWER)
C. C. Horse Boiler is a theoretical definition and is defined as “the production of 15.64 Kg/hr (34.5 Lb/hr) of saturated steam from 100°C (212°F) and a pressure of one atmosphere, using water power (in the condensate tank) of the same temperature. This is equal to the transmission of heat from 8436.56 Kcal/hr or 33,479 BTU/hour. (=9.81 kW).
Esta figura o definición es totalmente teórica ya que las calderas normalmente son alimentadas con agua de aprox. 70°C (cuando hay un buen retorno de condensados al tanque de condensados) y operan a una presión mayor que requiere de una temperatura mayor.
For example:
En una caldera que opera a 6.0 Kg/cm2 de presión manométrica y es alimentada con agua a 70°C, tendremos una producción de vapor de 14.31 Kg/hr por cada Caballo Caldera.
Si es alimentada con agua a 60°C y opera a una presión manométrica de 7.0 Kg/cm2, tendremos una producción de vapor de 14.04 Kg/hr por cada Caballo Caldera.
Para fines prácticos, para hacer una primera aproximación, es recomendable calcular con una producción de vapor de 14.0 Kg/hr por Caballo Caldera. (Y no con los 15.64 Kg/hr teóricos).
El vapor saturado generado por la caldera, se manda a los diferentes tipos de usuarios: Normalmente pasa a través de intercambiadores de calor, donde cede su calor en forma indirecta y de donde podemos obtener hasta el 100% de retorno de condensados.
Retorno de condensados:La cantidad de retorno de condensados hacia la caldera es de SUMA IMPORTANCIA. Requiere de la instalación de un buen filtro de vapor y de una trampa de vapor confiable y operando siempre en buen estado. El operador de la caldera debe estar siempre atento y checar continuamente el buen funcionamiento de la trampa y el retorno completo de los condensados (sin contaminación) al tanque de condensados.
Un buen retorno de condensados (siempre libres de cualquier tipo de contaminaciones) nos permite trabajar en forma eficiente, con un menor consumo de agua suavizada, menor uso de tratamientos químicos, menor necesidad de energía (ya que los condensados regresan calientes), menor cantidad de combustible y mayor capacidad de evaporación por parte de la caldera.
If selecting the boiler required we are aware that we will be able to operate very efficiently with a return of condensate is very high, it is advisable to notify the manufacturer
the boiler of the need for a condensate tank for increased capacity to prevent leakage of condensate in the future.
DEFINITION OF BHP (BOILER HORSE POWER)
The water in the boiler must always be under strict control. You may not submit figures of acidity = corrosion, hardness = embedding or contaminants from a process in the
users or heat exchangers. Nor of any bad chemical treatment has been applied and form masses binders that do not allow the cooling of the surface inter-
nas transfer of heat from the boiler, being able to damage it seriously.
Requires control of quality in weekly, fortnightly or monthly by a chemical engineer, as well as the dosage of a chemical treatment-specific depending on the water quality of each user.
A good boiler water quality control system should include weekly, biweekly, and monthly reviews by a qualified chemical engineer, as well as the administering of a customized chemical treatment. Additionally, a scheduled system of blowdowns is required to rid the water of sludge and chemical products resulting from preexisting contamination.
BLOWDOWN SEPARATOR TANK
The tank purges is a pressure vessel that receives the purges that are extracted from the boiler, sludge and wastewater. They come out of the boiler to the working pressure of the boiler, therefore, are in danger.
Ejemplo: If the boiler works at 7.0 Kg/cm2 of pressure gauge = the purges come out with this pressure equivalent to a columna water of 70 metres in height. This harms pipes so that the Official Mexican Standards require the use of a tank purges or pit to relieve this pressure.
The tank purges is a pressure vessel, high-risk necessary in the operation of steam boilers. This tank requires strict adherence to manufacturing standards code. Receive the purges of the boiler at high pressure, and must achieve its expansion in the short space. Low pressure in order to eject mud and sediment to the strainer without pressure. Because of its wide top output, expanding the hot steam which must be guided and expelled to the atmosphere in a high place and secure where there is no danger of contact with living beings or toxic chemicals or hazardous by heating (high temperature steam).
Important recommendations
1.The design engineer of a steam generation system must take into account the points addressed here. Especially in terms of the requirements of the water quality (softener).
2.Your calculation of requirement of steam must be based on values practical and not theoretical (14 Kg/hr by C. C.).
3.If you are going to have a high percentage of return of condensate, a larger feedwater tank may be required.
4.The boiler room must consider the installation of a blowdown tank.
5.The user must be aware of the importance of steam traps and their proper operation at all times.