Water hammer, or the study of fluid transient behaviour, is one of the most common problems in the water engineering community. This accident is a result of very poor engineering design practices and operators performing mundane tedious jobs. Steam condensation induced water hammer phenomena, a. See the article below understanding condensation induced water hammer. Water hammer causes piping, valves, pipe fixtures, sup. Sep 04, 2017 water hammer has multiple adverse effects on steam systems. The effect of a noncondensable gas on the initiation of water hammer in a condensing water steam system has been investigated by extending bjorges work. Based on computational results, it is concluded that the pipe slope is the dominant. Water hammer is a shock wave, usually generated by the rapid closure of a valve, but occasionally caused by a pressure wave resonance within a pipe.
A surge or water hammer in pipe or tube is a pressure spike caused by sudden variation of flow rate. The test rig performs well and the data has good accuracy and repeatability. Eliminate steam hammer solutions to steam hammering. This, in turn, causes slightly improved combustion efficiency. In a steam system, a water hammer most often occurs when some of the steam condenses into water in a horizontal section of the piping. The water hammer will normally be worse during start up due to the cold condensate lying in the return piping. Condensate induced water hammer, commonly called a steam explosion by the media, can result in fatalities to workers or to the public and can. Water hammer in steam distribution lines usually occurs when first supplying the steam. In a factory, a pump starting up operation or shutting down, or an air vent suddenly closing are examples of when this might occur. Opportunities and issues varies directly in proportion to the boilers net stack temperature the difference between the flue gas temperature and combustion air temperature. It occurs when a steam pocket becomes totally entrapped in subcooled condensate. Water hammer occurs when water, accelerated by steam pressure or a lowpressure void, is suddenly stopped by impact on a valve or fitting, such as bend or tee, or on a pipe surface. The previously mentioned method of operating valves slowly may help if the water hammer is caused by highspeed condensate slamming into piping, etc.
Turbulence builds up until the water forms a solid mass, or slug, filling the pipe. Steam distribution systems may also be vulnerable to a situation similar to water hammer, known as steam hammer. Figure 910 shows how water hammer burst another steam mainthis time one operating at a gauge pressure of 20 psi 1. If they fail in the open position, or, with bucket traps, if they lose their prime water, steam will move into the dry return lines and cause water hammer. Condensation induced water hammer events in piping systems can cause catastrophic steam system failures which can result in equipment damage, personal injury, and even death. Steam condensation induced water hammer by wayne kirsner, p. Steam bubble collapse, water hammer and piping network. The number one problem in a steam system water hammer of steam and condensate systems. Condensationinduced water hammer events potential consequences of allowing steam and subcooled water or slurry to mix. Steam hammering condition exists in a steam system where condensate coexists with generated steam or flash steam. Steam and water cannot be safely mixed in a piping system without risking condensateinduced water hammer. Its initiating mechanism is much different than the image most engineers have of what.
Last month we talked about the damaging effects of water hammer, but theres another state of h2o equally if not more. Describe corrective actions that were taken to prevent previous steam generator. The return line from the trap discharge should be pitched into a vented condensate return unit. Dec 28, 2017 a few things that can go very wrong when you put steam in a pipe. The heat exchanger smoothens out the pressure transient and reduces the loads. The purpose of these tests is to generate data for validation of a relap5 model. Do not mix steam with water either by injecting water into a. Condensation driven water hammer studies for feed water. If a stream of high velocity water impinges on a surface, water hammer can quickly erode and destroy it. Jun 24, 2014 if they fail in the open position, or, with bucket traps, if they lose their prime water, steam will move into the dry return lines and cause water hammer. It is possible to have high pressure steam systems operating without water hammer, and a long operational life from the steam components.
Jan 27, 2018 in case the flowing water is suddenly stopped by some mechanical valve or restriction, the action is like a heavy piston is striking that restriction like a hammer. Heater flooding check all valve and control settings inlet flow piped incorrectly check all inlet flows and temperatures water hammer inlet flows mixing just prior to deaerator inlet mix flows farther upstream. Water hammer has multiple adverse effects on steam systems. Steam hammer occurs when uncondensed steam forms bubbles, and when these bubbles contact a pipe wall or the side of a tank, they collapse and the moving fluid produces a concussive sound. The number one problem in a steam systemwater hammer of steam and condensate systems. This is the sound of water hammer in the water piping system.
Initiation of water hammer in a steamwater pipe with a noncondensable gas jiannlin chen1, tzuchen hung1 s. Water velocities can be much higher than the normal steam velocity in the pipe, especially when the water hammer is occurring at startup. A condensation induced steam hammer is sometimes called a condensation induced water hammer or a steam bubble collapse and is a rapid condensation event. A steamflowdriven water hammer is an impact event, where a slug of rapidly moving water strikes. This book covers the many causes and solutions in a practical way and is an essential reference for all those concerned with the flow of liquids, not just water, in pipe systems. Heat loss from the steam transport piping causes condensate to form and the velocity of the steam flowing over the condensate causes ripples in the water. In addition to water transport piping systems, water hammer also occurs in steam and condensate recovery i. In a few cases, water hammer has resulted into catastrophic hazards. We initially had loud water hammer around 6am when the building heating turned on, but following a wall excavation where they repitched a condensate return, we know experience water hammer noises every 1. These states, operations, and geometries are identified. Condensate induced water in a steam distribution results. Also find there other magazine and journal articles which describe water hammer in steam and condensate systems and boiler rooms. In replacing the boiler, someone tuned a wet return into a dry return.
Metallic, repetitive bang or loud noise heard when steam is first supplied. It occurs when you shut off the water suddenly and the fastmoving water rushing through the pipe is brought to a quick halt, creating a sort of shock wave and a hammering noise. It can also cause the heat exchanger and trap gaskets to blow out. The latter term suitably reflects the harmful effects that the hammerlike blows accompanying the pressure surges can have on pipes and system components. The latter term suitably reflects the harmful effects that the hammer like blows accompanying the pressure surges can have on pipes and system components.
Water hammer also can occur in a multiphase fluid, which is a liquid media that also has entrained solids. As an industry, we have learned to become accustomed to the banging that we often hear in our steam piping systems, and complacent in our actions to prevent it. General defination the earliest application of the onedimensional wave equation to explain observed water hammer effects was made by joukowsky in 1898 4 8. Incorrect steam water ratio check heat and mass balances spray valves or internals malfunctioning check spray valves, trays, etc. Incorrect steamwater ratio check heat and mass balances spray valves or internals malfunctioning check spray valves, trays, etc. The most basic explanation is that water hammer occurs when a fluid in motion is suddenly forced to stop moving. Watersteam flow situations in pipes can lead to locally entrapped steam pockets sur. Description of condensation induced steam hammer and diagram. Review of twophase water hammer international nuclear. Water begins to back up in the return riser because flow causes pressure drop in piping. A few things that can go very wrong when you put steam in a pipe. Does your process heating experience a repetitive knocking sound or a loud bang.
Actually the main difference between steam hammering and water hammering is, in a steam pipe if there is some water accumulation it is carried over by the high pressure and high temperature steam and it creates hammering this is known as water hammering in steam pipes similarly in a water pipe is steam enters it will create. If the system is properly designed and correctly operated, water hammer in any form will not occur. The rest of the steam picks up the water, forming a slug, and hurls this at high velocity into a pipe fitting, creating a loud hammering noise and greatly stressing the pipe. Initiation of water hammer in a steamwater pipe with a. Condensationinduced water hammer events and potential. Typical examples include heat exchangers, tracer lines, steam mains, condensate return lines and sometimes, pump discharge lines.
Pressure pushes air out through main and radiator vents. Since the water flow is restricted inside a pipe, a shock wave. In this section, the fundamental equations for 1d water hammer are derived. Design and maintenance crucial to avoiding water hammer in. Steam water hammer accidents and chilled water design. Water hammer can cause the pipe to break if the pressure. A steam flowdriven water hammer is an impact event, where a slug of rapidly moving water strikes. Subsequently, steam picks up the water, forms a slug and hurls it at. Pdf experimental investigation on the phenomenon of steam. In a steam system, water hammer most often occurs when some of the steam condenses into water in a horizontal section of the steam piping. The influence of a heat exchanger on a water hammer. A common example of steam hammer occurs during startup or energizing of a steam system.
In the case of an isolated occurrence, it produces a violent slamming that physically moves the pipe and causes a loud banging noise. As these steam bubbles are pushed into colder condensate in the return piping, they implode and cause water hammer. Water hammer can damage equipments like flow meters which are installed on the steam network. Screening reactor steamwater piping systems for water hammer. If further heat continues to be added, it then changes phase to saturated steam and continues to. Investigation of water hammer effect through pipeline system. The resulting water hammer can damage the steam trap, the steam regulating valve, and the heat exchanger tubes. An introduction to steam generation and distribution. Water hammer in steam distribution lines tlv a steam. It is possible to have highpressure steam systems operat ing without water hammer and enjoy a long operational life from the steam components. Pdf the condensation induced water hammer ciwh phenomenon may cause serious damage to the pipes and related system, which often. Steam condensation induced water hammer in a vertical upfill. Water hammer safety principle the workshop focused on the following condensateinduced water hammer safety principle.
Water hammer is a shock wave transmitted through fluid contained in a piping system. Pdf this is the type of waterhammer that kills people. Work on steam bubble collapse, water hammer and piping network response was carried out in two closely related but distinct sections. The basic definition of a water hammer is an impact load created by the sudden starting or. Typically, condensation induced water hammer occurs when steam is introduced into a pipe that is partially filled with condensate. Marshall long, in architectural acoustics second edition, 2014. During the accident, the rotor was seen flying through the air, still spinning, about 3 meters above the floor. Pdf this paper we study the condition where the water hammer effect is occurs in pipe line.
The momentum of the fluid abruptly stopping creates a pressure wave that travels through the media within the pipe system, subjecting everything in that closed system to significant forces. Hydraulic shock is a pressure surge or wave caused when a fluid, usually a liquid but. An example would be sand slurry or liquid pulp which is basically water transporting the pulp fibers. The earliest reports tend to concentrate on steam generator water hammer 810. The effect of a noncondensable gas on the initiation of water hammer in a condensing watersteam system has been investigated by extending bjorges work. Good piping practice prevents water hammer in steam systems.
Pdf initiation of water hammer in a steamwater pipe. A procedure that can be used for identifying whether an unbuilt reactor system is prone to water hammer is proposed. In a sense it constitutes a user manual for the program. Pdf investigation of water hammer effect through pipeline.
When boiler pressure is lowered, a lower stack temperature results. Condensation induced water hammer safety technical report. It was concluded that the water hammering is provoked when steam bubbles in the partially flooded fwd pipe are condensated into the cold feed water. Volume i of,is report details the experiments and analyses carried out in conjunction with the steam bubble collapse and water hammer project. This may be by setting a manual trigger in the simulation or by defining. Surface level rises slightly because the steam bubbles displace water. Flooding of a manhole or culvert containing a live steam line is more dangerous than people imagine. Pdf initiation of water hammer in a steamwater pipe with a. The condensation induced water hammer ciwh phenomenon may cause serious damage to the pipes and related system, which often occurs during the steam water direct contact condensation process.
Steam system bureau of energy efficiency 57 as water is heated from 0c to its saturation temperature, its condition follows the saturated liquid line until it has received all of its liquid enthalpy, h f, a b. Flooding of a manhole or culvert containing a live steam line is. Special attention is given to the assumptions and restrictions involved in various. Steam pressure bar steam temperature k pipe length l m pipe diameter d m flooding velocity ms water hammer yesno 1 58 546 5. Water hammer is a specific plumbing noise, not a generic name for pipe clatter. Deaerator troubleshooting symptom possible causes comments or. We live on the 18th floor of a 30 floor building, 400 units. A steamwater system possessing a certain combination of thermal, hydraulic and operational states, can, in certain geometries, lead to a steam bubble collapse induced water hammer. The number one problem in a steam systemwater hammer. The key factor is that water is the main transport medium in the piping system, and water can transmit shock waves very effectively. In case the flowing water is suddenly stopped by some mechanical valve or restriction, the action is like a heavy piston is striking that restriction like a hammer. Water hammer, also known as steam hammer, is a pressure or momentum transient in a closed system caused by a rapid change in fluid velocity. Investigations of the effect of a heat exchanger on the water hammer. In the 2009 sayanoshushenskaya power station accident, the lid to a 640 mw turbine was ejected upwards, hitting the ceiling above.
Pdf steam condensation induced waterhammer researchgate. The normal sound of water moving through pipes is a steady, even sound. Although it might seem to be a smooth flow, the water inside the pipe actually churns and tumbles as it moves through. The condensation induced water hammer ciwh phenomenon may cause serious damage to the pipes and related system, which often occurs during the steamwater direct contact condensation process. Condensate induced water in a steam distribution results in. Water hammer is usually recognized by a banging or thumping in water lines. Instances of rupture and disruption of piping on account of water hammer are also quite common.
268 630 687 880 369 704 791 777 624 1387 1322 809 69 551 1201 937 756 1068 792 519 853 1301 118 1178 476 456 500 217 1615 1046 843 274 685 1588 573 984 580 1384 1099 464 866 407 424 1355 211