This essential book explains the principles of steam engineering and heat transfer, covering all aspects of steam and condensate systems from the boiler house, through the steam distribution system to the point of use, and recovering, and returning condensate back to the boiler.
Spirax Sarco Steam And Condensate Loop Book Pdf
A steam trap is a valve that opens to permit condensate to return to the steam boiler while keeping steam and closes when the condensate has passed and only steam is present, thus keeping steam inside of the radiator - preventing the loss (and waste) of live steam.
On a building steam heating system the steam trap dischages condensate while retaining steam in the system. This ensures that the steam system operates efficiently, without the harmful effects of unwanted condensate that can otherwise block steam from entering a steam radiator or may interfere with proper return of condensate to the steam boiler, leading to steam boiler flooding. (Adapted from Spirax 2018)
Steam traps such as the Hoffman-style thermostatic-type steam trap shown at the top of this page are installed on residential steam heating systems (usually at the bottom of the radiator at the opposite end from the steam input side) in order to allow air and condensate out of the radiator while at the same time, stopping the escape of steam (or slowing it) until the steam can condense to water (thus transferring its heat to the radiator itself).
Steam traps may be found on steam heating systems both on radiators (at the radiator bottom opposite end from the entering inlet valve), and on older steam heating systems a steam trap may also be found on some steam piping where the trap handles condensate produced inside the steam riser piping.
In this thermostatic steam trap design, used at radiators and steam rising in the two pipe steam heating system piping enters the radiators, usually through a Hoffman-type supply valve near the top of the radiator, and a mixture of steam and condensate is separated by the steam trap at the radiator outlet.
The steam trap stays closed until sufficient condensate has been produced inside the steam radiator to enter and cool the steam trap. The condensate then causes the bellows to cool, shrink, open the steam trap.
Condensate escapes: As the incoming steam cools inside the radiator, returning to its water state as condensate, condensate falls to the bottom of the radiator and also needs to exit through the steam trap. Exiting condensate follows return piping back to the boiler.
A ball float type trap sense the difference in density between steam and condensate. This type of steam trap is very responsive to conditions in the steam system and provided the ball float trap includes an automatic air vent, the trap will discharge condensate quickly "as soon as it is formed" independent of changes in steam pressure within the system.
Condensate that enters the trap will cause a ball float to rise inside the trap, lifting the valve off its seat and releasing condensate. In this design the ball float steam trap valve is always flooded so neither steam nor air will pass through it.
Although they are generally larger and more robust, ball float steam trap mechanical operation is not unlike that of some radiator STEAM VENTS except that the latter are operated by temperature rather than the level of condensate within the trap.
Inverted bucket type steam traps, also called "mechanical steam traps", use an inverted or "upside-down" bucket float inside the trap to open or close a plug and seat that allows condensate to be discharged.
Inverted bucket traps work well on systems where there is a concern with larger amounts of scale and debris in the condensate as they're more-resistant to debris clogging than other steam trap types. These traps are used where air venting is handled separately or is not a concern.
Watch out: although inverted bucket steam traps are great at avoiding debris clogging, because the trap contains water, if it's in a location subject to freezing and because it's not self-draining of condensate in the lower part of the trap, it can be damaged in freeze-prone locations. Also because inverted bucket traps are not good at venting air, if air venting isn't handled ahead of the inverted bucket trap the trap can lose its prime and stop working properly Finally, because individual inverted bucket steam traps have a narrow operating pressure range, be sure that you select the proper trap for your application
The name of this steam trap describes the bucket steam trap operation. Inside of this steam trap an inverted bucket-container - formed like an upside-down bucket - is attached to a mechanical lever that is in turn connected to a valve controlling condensate outlet from the device.
As steam enters the bucket trap at its bottom the bucket floats "up" in the condensate-filled trap, lifting the lever that closes the condensate outlet valve on the trap. Condensate inside the trap flows down (and air moves up) inside the trap.
Thermodynamic (TD, Disc) steam traps use a simple design with a single moving part (a disc or valve) that opens do discharge condensate and closes to retain steam. Thermodynamic steam traps are used on high-pressure drip steam systems and in critical designs where condensate backup would cause serious operating problems.
Thermodynamic traps have only one moving part, the valve disc, which allows condensate to be discharged when present and closes tightly upon the arrival of steam. These traps have an inherently rugged design and are commonly used as drip traps on steam mains and supply lines.
Mechanical steam traps rely on the difference in density between steam and condensate in order to operate. They can continuously pass large volumes of condensate and are suitable for a wide range of process applications. Types include ball float and inverted bucket steam traps. - Spirax-Sarco (2014)
At the start of a heating cycle the trap is open to discharge into the condensate line. As hot condensate "flashes to steam" as it passes through the trap body the valve closes and stays closed until the flash steam condenses.
Figuring out if a steam trap is working properly - that is, opening and closing at the proper temperatures - has been described as complicated enough that books have been written on the problem. But ITT recommends a simple practical approach that can make a rough test. [2]
Our sketch (left, adapted from ITT's Steam Book [2]) illustrates a float and steam trap. That round ball is the float ball. You can see the red thermostat at the top of the image, and the green color indicates where condensate can flow out of the trap.
You can see that condensate can exit the trap either through the thermostat port or through the interior of the trap body, depending on the float position. A common float and thermostat steam trap found on residential buildings is the Hoffman 53-FT.
The F&T trap as these devices are called in the trade, achieve the same function as the traditional steam trap, but the float switch will open to permit condensate to drain regardless of the (presumably high) temperature inside the trap.
A new condensing steam turbine K-65-12.8 is considered, which is the continuation of the development of the steam turbine family of 50-70 MW and the fresh steam pressure of 12.8 MPa, such as twocylinder T-50-12.8 and T-60/65-12.8 turbines. The turbine was developed using the modular design. The design and the main distinctive features of the turbine are described, such as a single two-housing cylinder with the steam flow loop; the extraction from the blading section for the regeneration, the inner needs, and heating; and the unification of some assemblies of serial turbines with shorter time of manufacture. The turbine uses the throttling steam distribution; steam from a boiler is supplied to a turbine through a separate valve block consisting of a central shut-off valve and two side control valves. The blading section of a turbine consists of 23 stages: the left flow contains ten stages installed in the inner housing and the right flow contains 13 stages with diaphragm placed in holders installed in the outer housing. The disks of the first 16 stages are forged together with a rotor, and the disks of the rest stages are mounted. Before the two last stages, the uncontrolled steam extraction is performed for the heating of a plant with the heat output of 38-75 GJ/h. Also, a turbine has five regenerative extraction points for feed water heating and the additional steam extraction to a collector for the inner needs with the consumption of up to 10 t/h. The feasibility parameters of a turbine plant are given. The main solutions for the heat flow diagram and the layout of a turbine plant are presented. The main principles and features of the microprocessor electro hydraulic control and protection system are formulated.
A refined procedure for estimating the effect the flashing of condensate in a steam turbine's regenerative and delivery-water heaters on the increase of rotor rotation frequency during rejection of electric load is presented. The results of calculations carried out according to the proposed procedure as applied to the delivery-water and regenerative heaters of a T-110/120-12.8 turbine are given.
An investigation of one and half axial turbine stage configuration was carried out in a closed-loop wind tunnel. The investigation was addressed to that impact how the previous stage outlet flow field influences the flow structures in the next stator in steam multistage turbines. The stage - stator interaction has been studied in this work. The detailed measurement with a pneumatic probes and fast response pressure probes behind the rotor and the second stator were performed to gain the useful data to analyze the impact. The detailed flow field measurement was carried out in the nominal stage regime (given by the stage isentropic Mach number 0.3 and velocity ratio u/c 0.68). The clocking effect of the stators is discussed and detailed unsteady flow analysis is shown. 2ff7e9595c
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