High-pressure steam expansion

Hydroth nnal High pressure steaming Expansion Extrusion Pyrolysis... 

Addition of molybdenum to nickel-chromium alloys produces grades such as Inconel 625 and Hastelloy C276. These alloys are practically unaffected by caustic up to at least 320°C [135]. Their high costs limit their application. An exception is the use of Alloy 625 in high-pressure steam expansion joints. This avoids the caustic... 

To more fully exploit the key patent claim for the separate condenser, the firm avoided the use of high-pressure steam since it did not absolutely require a condenser. The patent claim for expansive use of steam without a condenser was used only as ammunition to restrict development in that field, although high-pressure steam replaced low-pressure steam during Watt s lifetime, and noncondensing systems... 

In this example, the high pressure steam service piping for the curved pipe bend B is 8-inches, schedule 80 carbon steel with a wall thickness of 0.50 inches, a moment of inertia, I for 105.7 inches and an OD of 8.625 inches. The service pressure is 680 psi. The steam temperature is 650° F. The pipe expansion rate at this temperature is 5.584 inches per 100 feet. A = 5.584(508)/100 = 28.4 in. The cold Modulus of Elasticity, E of 29,000,000 psi will be used. This puts the F and S values in the high stress range. 

A schematic of the experiment apparatus is shown in Figure 1. Major components of the facility include an explosion resistant containment cell, a 1.51 m expansion vessel (EV) and a high pressure steam boiler. The expansion vessel stands approximately 3.4 meters high and is 0.76 meters in diameter. The vessel is trace heated and insulated. It can accommodate a steam atmosphere. 

It has been proposed [616, 617] to recover heat, not by converting water to steam, but by evaporating liquid ammonia at high pressure. This could take place inside the ammonia converter, since it does not involve the safety risks involved in the evaporation of water in such equipment. The hot, high pressure ammonia would be used for power production by expansion in a turbine in a way similar to the production of power from high pressure steam. The proposed system has, however, not been used in industrial practice. 

Thermal expan sion. Equipment and pipehues which are liquid-full under normal operating conditions are subject to hydrauhc expansion if the temperature increases. Common sources of heat that can result in high pressures due to thermal expansion include solar radiation, steam or other heated tracing, heating coils, and heat transfer from other pieces of equipment. 

Low-temperature, high-pressure gases at moderate to low temperatures can be expanded by the use of an expansion turbine (very similar to a steam turbine or even by reciprocating or screw-type compressors) or by the use of a throt-... 

The product stream leaving the stripper goes through an expansion valve to the low-pressure section, the operating pressure there being 5 bar. In a steam-heated rectifier, further ammonia and carbon dioxide are removed and, with some water vapour, are condensed to give a weak carbamate solution. This is pumped back to the high-pressure condenser. 

Water enters the pump at state 1 as a low-pressure saturated liquid to avoid the cavitation problem and exits at state 2 as a high-pressure compressed liquid. The heat supplied in the boiler raises the water from the compressed liquid at state 2 to saturated liquid to saturated vapor and to a much higher temperature superheated vapor at state 3. The superheated vapor at state 3 enters the turbine where it expands to state 4. The superheating moves the isentropic expansion process to the right on the T-s diagram as shown in Fig. 2.5, thus preventing a high moisture content of the steam as it exits the turbine at state 4 as a saturated mixture. The exhaust steam from the turbine enters the condenser at state 4 and is condensed at constant pressure to state 1 as saturated liquid. 

Determine the effieieney and power output of a reheat Rankine eyele, using steam as the working fluid, in whieh the eondenser pressure is 80 kPa. The boiler pressure is 3 MPa. The steam leaves the boiler at 400°C. The mass flow rate of steam is 1 kg/see. The pump efficiency is 85% and the turbine efficiency is 88%. After expansion in the high-pressure turbine to 800 kPa, the steam is reheated to 400°C and then expanded in the low-pressure turbine to the condenser. 

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