Turbine-driven pumps

Subsequent taxonomy levels describing type of equipment, e.g., turbine driven pump... 

Gas and steam turbines rigid turbo-generator rotors rotors turbo-compressors machine-tool drives small electrical armatures turbine-driven pumps. 

A turbine-driven pump is said to be driver-limited when the governor speed-control valve is wide open. This speed-control valve, is usually called the Woodward governor. It is not that easy to see if the governor is really wide open. A few simple methods to make this determination are... 

It is quite important not to operate a turbine-driven pump by throttling the steam flow to the turbine. Let s assume that the operators have set the turbine speed at 3500 rpm, by adjusting the steam inlet gate valve upstream of a malfunctioning governor. Suddenly, the discharge flow-control valve cuts back, and the pump s flow decreases from 2000 to 1200 GPM. The pump speed will then increase, because fewer pounds of liquid are being pumped, and less horsepower is required to spin the pump. 

Turbine driven pumps blowers Mixers and agitators Simple Incinerators Flare stacks... 

Figure 11-3 shows a simplified event tree for the TLMB sequence of a PWR according to the Rasmussen report (loss of all the external power supplies for at least three hours and of auxiliary feed-water due to loss of the diesel generators and of the turbine-driven pump). ... 

T is the transient of main feed-water loss due to loss of electric power supply. M, B indicate the lack of recovery of the outside lines and the non-operation of the station diesels for at least three hours (in the Rasmussen report, the probability of non-recovery of the outside lines in one hour is assumed equal to 2x 10" and the probability, to be combined with the preceding one, of nonrecovery for the other two hours of the same lines, is assumed equal to 5 x 10 ). L indicates the malfunction of the auxiliary feed-water system and therefore also of the turbine-driven pump. 

The AFWS is a 2 division and 4 train system. The AFWS is designed to supply feedwater to the SGs for RCS heat removal in case of loss of main/startup feedwater systems. The reliability of the AFWS has been increased by use of two 100% motor-driven pumps, two 100% turbine-driven pumps and two independent safety-related auxiliary feedwater storage tanks as a water source instead of condensate storage tank. 

The main feedwater system has two turbine driven pumps and a motor driven pump. The feedwater heaters are similar to those of the existing LWRs. 

One turbine-driven emergency feedwater pump is included for each steam generator. (These are in addition to the two motor-driven emergency feedwater pumps.) In previous designs one turbine-driven pump was shared by both steam generators. 

Low-low level in 2/4 level channels in any two steam generators turbine-driven pumps... 

Also, try to avoid running a steam turbine-driven pump as a coker Iteater cliarge pump. If the pump s steam supply comes from the same steam header, fluctuations in the steam header pressure (such as when steam is cut into a full coke drum) can cause a brief but deadly slippage in feed flow to.lhelieater. 

Frequently, a major unit shuts down when a compressor trips off. The cause may be low lube- or seal-oil pressure. The pumps providing the lube- and seal-oil pressure are typically spared (backed up). A steam turbine-driven pump is normally backed up by a motor-driven spare. The motor-driven pump should come on when the lube-oil pressure drops below a preset point. 

Calculations have shown that once the ASG system and the turbine driven pump have come into action, in conjunction with the insertion of the regulating rods as a result of the increase in temperature (assumed to be available, since they are completely independent of the failed emergency shutdown systems), the significant parameters remain within admissible limits. 

On occasion, pumps are not directly connected to either a motor or a turbine. There is an intervening gear, which can increase the pump s speed by multiplying the driver s speed. The gear is another source of possible misalignment and vibration. I have always considered such reduction or speed increaser gears to represent poor design practice, and an unnecessary complication as they often require their own lubrication system. Most often the lube oil pump is driven indirectly by the main pump. Especially for a turbine-driven pump, this is a recipe for disaster. 

Many years ago, working as an outside operator during a strike (i.e., I was a scab), I noted that on some of my steam turbine-driven pumps, the level of oil in the oiler glasses rose perhaps Vito 1 inch every day. I actually thought that in some mysterious way, that lubrication oil was being produced inside the bearing housing. Of course, it was just water. 

Water Accumulation in the Bearing Housing of Turbine-Driven Pumps... 

For variable-speed pumps, such as steam turbine-driven pumps, control valves should not be used. The facility shown in Fig. 38.2 is a control scheme that is used not infrequently at older plants. It s a fine piece of technology, which has been lost with time. No control valve is used. The turbine speed is altered to directly maintain the vessel level. With the increasing use of variable-speed alternating-current motors, elimination of parasitic control valves should become more common. 

Even on a brand new imit, you should not be surprised if 30 to 50 jjercent of the amjjerage on a driver can be saved. Again, for turbine-driven pumps the goal is not to optimize the size of the control valve but to totally ehminate the control valve. 

The Reactor Safety Study found the AFWS to be important in preventing certain core damage scenarios, and, the loss of auxiliary feedwater at TMI-2 reinforced concerns regarding the reliability of the AFWS. Prior to the accident at TMI-2 there was wide variance in design philosophy for auxiliary feedwater systems. In particular the degree of diversity and redundancy varied widely. Some multiplant sites had only one auxiliary feedwater pump per plant with interconnections between units. Other plants had two motor driven and one turbine-driven pump. 

Failure of the cooling water pump is an important consideration, and the number of cooling water circulation pumps needs to be established carefully. The number of cooling water circulation pumps can be equal to the number of steam turbine-driven pumps that normally operate. 

Turbine-driven pumps, compressors, blowers, and generators... 

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