Turbines, steam nozzles

Material of constmction of all the critical parts, e.g., steam nozzles, turbine blades, shaft shall be informed by the vendor. They shall be suitable for the maximum temperature of the superheated steam. 

Steam jet thermocompressors or steam boosters are used to boost or raise the pressure of low pressure steam to a pressure intermediate bettveen this and the pressure of the motive high pressure steam. These are useful and economical when the steam balance allows the use of the necessary pressure levels. The reuse of exhaust steam from turbines is frequently encountered. The principle of operation is the same as for other ejectors. The position of the nozzle with respect to the diffuser is critical, and care must be used to properly posidon all gaskets, etc. The thermal efficiency is high as the only heat loss is due to radiation [5]. 

The 300-psig steam next passes through the steam nozzle. This is an ordinary nozzle. It screws into a hole in the wall, which separates the steam chest from the turbine case. The nozzle is shaped to efficiently convert the pressure of the 300 psig to steam velocity. The pressure of the steam, as soon as it escapes from the steam nozzle, is already the same as the exhaust steam pressure (100 psig). 

It is the velocity of the steam, impacting on the turbine wheel buckets, that causes the turbine to spin. If that is so, then the way to extract more work from each pound of steam is to increase the velocity of the steam as it escapes from the steam nozzle, shown in Fig. 17.1. 

What I wish to achieve is to maintain the same horsepower output from the turbine. But at the same time, I want to force open the governor speed-control valve, raise the pressure in the steam chest, but decrease the steam flow through the steam nozzle. The only way this can be done is to make the nozzle smaller. 

Many steam turbines do not have full-ported steam nozzles (see Chap. 17). The existing steam nozzles may then be exchanged for larger nozzles. An increase of nozzle diameter of 10 percent would increase the turbine horsepower by 20 percent. 

Expanding high-pressure steam to a low pressure through a steam nozzle used in turbines and vacuum ejectors (see Fig. 20.3) is my favorite example of an isoentropic process. 

Steam rack Device that automatically opens and closes steam nozzles into a turbine case. 

When testing to estabhsh the thermodynamic performance of a steam turbine, the ASME Performance Test Code 6 should be followed as closely as possible. The effec t of deviations from code procedure should be carefully evaluated. The flow measurement is particularly critical, and Performance Test Code 19 gives details of flow nozzles and orifices. The test requirements should be carefully studied when the piping is designed to ensure that a meaningful test can be conducted. 

In a turbine that is running, erosion-corrosion is pretty much confined to units that are operating on saturated steam with inadequate boiler-water treatment. This type of erosion takes place behind the nozzle ring and around the diaphragms where they fit in the casing. 

Injection of Steam in the Combustor of the Gas Turbines Utilizing Present Dual Fuel Nozzles. Steam injection in the combustor has been commonly used for NO control as seen in Figure 2-43. The amount of steam, which can be added, is limited due to combustion concerns. This is limited to about 2-3% of the airflow. This would provide an additional 3-5% of the rated power. The dual fuel nozzles on many of the industrial turbines could easily be retrofitted to achieve the goal of steam injection. The steam would be produced using an HRSG. Multiple turbines could also be tied into one HRSG. 

Nozzle Area of the First Turbine Stage Expander Stage). This is a very eritieal parameter and limits the total airflow into the turbine seetion, thus this limits the amount of steam injeetion or the amount of the heated and humidified eompressed air injeetion. 

Steam is passed through a number of tubes embedded in the nozzle or blades of the turbine. In many cases, the steam is bled from after the HP Steam Turbine of a combined cycle power plant and returned after cooling the gas turbine blades, where the steam gets heated in the process to the IP steam turbine. This is a very effective cooling scheme and keeps the blade metal temperature below 1250 °F (649 °C). 

Liner eraeks ean be eaused by liquids in the fuel or bloeked nozzles, whieh ean ereate hot seetions in the liner as seen in Figure 21-18. In many turbines, the injeetion of steam or water in the eombustor ean has been used to meet... 

Turbine blades can be excited by steam flowing through the intermediate nozzles, which can cause premature blade failure. 

Steam Turbine Nozzle Pa Ming No of Blades RPM Steady... 

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