b'Process Industries | Engineer InnovationMany plant design engineers think thereof hazardous substances, design of are no pressure surge problems in processmitigation measures.plants, since pipes are short and thin compared to cross-country pipelines. ButPressure surge in process pipingthis is not true! Although incidents caused by pressure surge are not as frequentlyIf a liquid flows through a pipe with an reportedthey do occur. About 5initial flow velocity v0, and a valve closes, incidents are known within 10 years atthe flow velocity drops and pressure Frankfurt-Hchst Industrial Parksignals are initiated in both directions due (damages,partly with release ofto the liquids inertia (figure 2). In substances). One such incident occurredupstream direction with positive sign, in on a system as depicted in figure 1 wheredownstream direction with negative sign. the pipe partially left the rack bridge. The low pressure is limited by the vapor pressure of the liquid. If this is reached, a The 24, 65 m long pipe was beingvapor bubble will locally form (this is pumped with waste water via a pipecalled "cavitation). The maximum bridge. The high flow rate of nearly 3000pressure increase that can be reached by m/h resulted in a high flow velocity of 2.8a spontaneous flow velocity drop v can m/s. When the valve 1 downstream of thebe calculated from the momentum (I) pump was closed, a negative pressuregradient as:surge occurred causing a pressure __1__ v( __m )affecteddI_ d _p =__ = _________________ = vaimpulse. The instrumentation measured aJouk.dtpeak value of 8 bargthe real peak valuedt A pipe A pipeprobably was not detected, due to theJoukowski-Shockslow scanning rate or placement of the sensor. The resulting forces on the pipeExample (Figure 3): Liquid is pumped supports were strong enough to damagefrom one tank to another via a 3 km long these and to push the line partially off thepipe at 1.3 m/s. The valve at the target rack! tank is closed within 3 seconds. The diagram in figure 3 shows the pressure Experts at consilab GmbH have relied ontime history directly upstream of the SimcenterTM FlomasterTM for more than aclosing valve. It was obtained by decade to address this challenge. In thissimulation with Simcenter Flomaster.text, we will discuss the methodology utilized to screen the appropriate pipingIt can be observed that the pressure rise for surge analyses and assess appropriatedoesn\'t occur instantaneously, but builds techniques that can be convenientlyup during the valve is closing. A first deployed by customers to mitigatemaximum is reached when closure has undesired pressure pulses in theircompleted. It is followed by a flatter rise systems.(the so-called "line packing effect), which is caused by the decreasing friction losses consilab GmbH is a renowned consultingalong the pipe length. After 9 s the and laboratory company based inreflection of the pressure wave arrives. It Frankfurt, Germany and working withreversed its sign and direction at the other multiple process companies in Europe on(open) end of the pipe. Therefore, it the following themes: wipes out the initial pressure impulse. Since the pressure signal propagates withProcess safety: Obtaining safetyabout 1 km/s, it takes a return time of 6 relevant parameters for substances andseconds to travel forth and back the 3 km chemical reactions long line. If the return time is shorter thanConsulting: Expertise on safetythe valve closing time, the reflected wave concepts and safety assessment,will cease the Joukowski shock before it incident investigations has fully developed. Safety relevant calculations: Pressure relief devices and general pipingThis attributes to the quality of physics networks, consequences of releaseimplemented in Simcenter Flomaster. As 51'