Trips steam

Sticking of valve stems is common if solids are present in the steam. The steam mast be without sohds. (Note comments later under loss of power.) It is important that units operating on a steady load for long periods be checked for sticking stems at regular intervals. The records show that in several cases deposits have caused the stem of both the governor valve and the trip valve to stick when there was a loss of load. The effect of the loss of load was destructive overspeed. 

Leaky valves are also a cause of erosion. Most turbine erosion-corrosion problems come from damage that takes place when the unit is not running. A shght steam leak into the turbine will let the steam condense inside the turbine, and salt from the boiler water will settle on the inside surfaces and cause pitting, even of the stainless blading. There must be two valves with a drain between them, i.e., a block valve on the header and an open drain in the line before it reaches the closed trip-throttle valve. 

In contrast to steam turbines, in which runaway overspeediug is always a problem, pump-turbines operating at design head go to zero torque at about 130 to 140 percent of design speed. Thus, overspeed protection may not be necessary if the pump-turbine can withstand 140 to 150 percent of design speed and it is the sole driver. When a steam-turbine helper is used, it should be provided with the usual overspeed trip-out mechanism. 

The operational test of the lube system is, as the name implies, a functional test to check as many of the features as practical under running conditions. The first and last step is a demonstration of the cleanliness of the system. This is followed by a running test of a four-hour duration. The test should simulate the field operation with the compressor in every way practical. All equipment to be furnished with the lube system should be used in the test, including the standby pump start and trip switches. All other instruments should be used to demonstrate their operation. Prior to starting the four-hour run, the system should be thoroughly inspected for leaks and the leaks corrected. If no steam is available for a steam turbine (if one is used), the four-hour run can be made on the electric pump. However, every effort should be made to use an alternate source of energy such as compressed air, to operate the steam turbine. 

Steam turbine, 53, 146, 282-92, 179 back pressure, 282 blade deposits, 479 condensing, 282 efficiency, 288 extraction, 282 induction-type, 282 paitial admission, 288 rating, 290 reliability, 478 selecuon variable, 275, 285 speed, 278 stage losses, 286 steam temperatures, 284 steam velocity, 288 trip and throttle valve. 479 Step unloading system, 80 Stiffness coefficients, 385 Stodola slip, 153, 155 Stonewall, 186 Straight labyrinth. seal leakage, 532... 

Equipment may get washed with a steam jenny and allowed to air dry on plastic in a more remote area. We need to keep in mind that steam cleaners have the potential to cause substantial physical harm. The combination of high-pressure water and high temperatures can be dangerous. Wlien this is coupled with a worker standing on visquine or plastic, it becomes a slip, trip, and fall situation. Situations compounded with respiratory and whole-body protection, such as saranex or rubber suits and gloves, add in the potential for poor vision, heat stress, and the lack of physical dexterity. Keep these issues in mind prior to steam cleaner activity. 

Steam generator overheated and tripped its pressure relief,... 

At 0119 10, the operator began to increase the rate of feedwater return to reduce the recirculation flow to increase the water level in the steam drums. At 0119 45, the reduced inlet water. stopped water from boiling in the core. The absence of the steam voids reduced the reactivity, and control rods were withdrawn, such that only 6 to 8 rods were in the reactor, rather than the required 30. Then, to avoid reactor trip from steam drum or feedwater signals, their scram circuils v ere locked out (a safety regulation violation). 

Loet of primary coolant flow LOB8 of feed water ricw Loae of steam Flow Turbine trip... 

Core damage can result most likely from heat imbalance. Figure 6.3-3 is an example from the Indian Point PRA that uses heat imbalance to approach completeness. This diagram shows that cote damage may result from either a loss of cooling or excess power (or both). The direct causes of insufficient heat removal may be loss of flow, makeup water, steam flow, or heat extraction by the turbine. Indirect causes are reactor trip or steam line break inside or outside of containment. Cau.ses of excess power production are rod withdrawal, boron removal, and cold water injection. 

F.xamples of initiating events considered in five PRAs are provided by Joksimovich et al. (lhS3) and presented as Table 6.3-5. The occurrence frequencies vary from a high of 3.7/yr for turbine and reactor trip at Zion to a low of lE-6/yr for a large steam line break outside of containment at Big Rock Point. Another low frequency is 2E-6/yr for ATWS from the loss of one feedwater pump, also at Big Rock Point. Surprisingly, these are less than a large LOCA (IE- 5/yr) at the same plant. Except for Big Rock Point, this table provides no information on externalities. 

Some licensees have a switch to bypass RCIC high steam tunnel temperature trips. Some licensees are evaluating improvements to prevent seal LOCAs from loss of seal cooling which are most important for W plants, but B W licensees identified improvements related to alternate seal flow capability under loss of power conditions. The use of high temperature seals is noted for some W plants. Many PWR IPEs identify AFWS improvements. These include additional backup water supplies such as the firewater system and redundant pump cooling capability. Other reliability... 

It is important to note safety differences between the SRS reactors and LWRs. Since the SRS reactors are not for power production they operate at a maximum temperature of 90° C and about 200 psi pressure. Thus, there are no concerns with steam blowdown, turbine trip, or other scenarios related to the high temperature and pressure aspects of an LWR. On the of nd, uranium-aluminum alloy fuel clad with aluminum for the SRS reactors melts at a m ver... 

A similar incident occurred in a steam drum in which steam was separated from hot condensate. On this occasion, the operator noticed that the pressure had risen above the set-point of the relief valve and tripped the plant [19]. 

Although the engine was not a success, Ericsson s trip to London allowed him to meet John Braithwaite, a machine manufacturer, who had the expertise to put Ericsson s ideas into practice. In 1828 Ericsson, with Braithwaite, patented the principle of artificial draft in steam boilers. The principle of forced draft was applied to a fire engine and a locomotive entered for the Rainhill locomotive trials of 1829. 

A subsequent trip was made to Washington, a round trip of some five hundred miles. Unfortunately, the ship sank in April in freak weather conditions and, although successfully salvaged, her engines were replaced with steam engines. Ericsson s detractors claimed the ship was underpowered and... 

Trip valve Shuts off steam on overspeed Steel, stainless, and nickel iron... 

A governor valve controls the flow of steam to the turbine. This valve is actuated by the governor, which is operated by the speed of the machine. When the speed exceeds the set value of the governor, a trip-valve is actuated to completely shut off the steam supply. The trip valve may... 

Steam Admission Volve(s) Governor Controlled Single, Emergency Trip Valve Combine d with Throttle Valve ... 

So much planning and preparation went into making that trip possible for me. We even found a rental car company that agreed to steam clean a car and wash the whole inside over and over with vinegar until it worked for me. We were in Hawaii for three weeks. We didn t go to public places but every day we went to a different beach. 

E.4.4 It may be useful to verify the overspeed trip setting for the HPRT at the manufactnrer s test facility. Determining the runaway speed during a water test may be considered, but this speed can be accurately calculated once performance with water is known. Rnnaway speed for gas rich-steams cannot be determined by water tests. 

An ordinary American-type turbine is designed to run at 3600 rpm. Its overspeed trip will cut off the motive steam flow at about 3750 rpm. But the turbine can be run at any lower speed. There is usually a small knob on the left side of the governor-valve assembly, that is used to... 

Question How does this affect the amp load on the motor driver Well, the feet of head has gone down by about 10 percent, and the specific gravity has gone up by about 10 percent. Therefore, the horsepower or work per barrel of liquid pumped, remains constant. But the number of barrels has increased by 6000 bbl/day, or 35 percent. Then, the amp load on the motor driver would also increase by 35 percent. If I had not remembered this, prior to cooling the hydrocracker feed, the motor would have tripped off. As it was, I had the steam to the turbine increased. So as to decrease the motor amps to 60 percent of maximum, before cooling the gas oil. Omission of this detail, would have had embarrassing and possibly negative contractual consequences. 

Compressors also have vibration trips. These trips measure the amplitude of the vibrations—which, if they become excessive, will shut off the fuel, steam, or electricity to the compressor s driver. 

Turbines, both gas and steam, also have overspeed trips. These consist of a little flywheel, constructed from three balls. The little balls are spread apart by centrifugal force. The greater the rpm, the greater the centrifugal force. If the balls spread apart too far, they activate the trip. We have James Watt to thank for this neat innovation, still used in its original form. 

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