Steam injection temperature

High temperature steam (qv) is also used for recovery of viscous cmde oils (28). Heat from the steam thins the oil, reducing viscosity and increasing mobihty. The mobilized oil is produced at offset production wells. In heavy oil fields, water flooding is often omitted and steam injection begun immediately after primary production. Steam injection temperature is typically 175—230°C in California oil fields. Injection temperature can reach 300°C in Canadian and Venezuelan EOR projects. 

Other Continuous Processes. Various pasteurization heat treatments ate identified by names such as quick time, vacuum treatment (vacreator), modified tubular (Roswell), small-diameter tube (MaHotizer), and steam injection. The last three methods are ultrahigh temperature (UHT) processes (see Fig. 3). Higher treatment temperatures with shorter times, approaching two seconds, are preferred because the product has to be cooled quickly to prevent deleterious heat effects. 

For NO control only, steam is injected into the combustor directly to help reduce the primary zone temperature in the combustor. The amount of steam injected is in a ratio of 1 1 with the fuel. In this cycle, the steam is injected upstream of the combustor and can be as much as 5-8 percent by weight of the air flow. This cycle leads to an increase in output work and a shght increase in over l efficiency. Corrosion problems due to steam injection have been for the most part over-... 

FIG. 29-38 Performance map showing the effect of pressure ratio and turbine inlet temperature on a fixed steam rate in a steam injection cycle. 

Afterburn Control. Afterburn is the term for carbon monoxide burning downstream of the regenerator this causes an increase in temperature upstream of the expander. Temperature sensors in the gas stream cause the brake to energize. This provides sufficient resisting torque to prevent acceleration until the afterburn is brought under control by water or steam injection. 

Figure 2-21 show the effect of 5% by weight of steam injection at a turbine inlet temperature of 2400 °F (1316 °C) on the system. With about 5% injection at 2400°F (1316 °C) and a pressure ratio of 17 1, an 8.3% increase in work output is noted with an increase of about 19% in cycle efficiency over that experienced in the simple cycle. The assumption here is that steam is injected at a pressure of about 60 psi (4 Bar) above the air from the compressor discharge and that all the steam is created by heat from the turbine exhaust. Calculations indicate that there is more than enough waste heat to achieve these goals. 

This design has a number of tubes embedded inside the turbine biade to provide ehanneis for steam. In most cases these tubes are constructed from copper for good heat-transfer conditions. Steam injection is becoming the prime source of cooiing for gas turbines in a combined cycie appiication. The steam, which is extracted from the exit of the HP Turbine, is sent through the nozzie biades, where the steam is heated, and the biade metai temperature decreased. The steam is then injected into the flow stream entering the IP steam turbine. This increases the overaii efficiency of the combined cycie. 

The turbine temperature, flow, and speed increases in a very short time of about three to five minutes to the full rated parameters. There is usually a short period of time where the temperature may overshoot. If supplementary firing or steam injection for power augmentation is part of the plant system, these should be turned on only after the gas turbine has reached full flow. The injection of steam for power augmentation, if done before full load, could cause the gas turbine compressor to surge. 

Optimization of the pressing process, e.g. by increasing the effect of the steam shock by (1) increased press temperatures, (2) additional steam injection, or (3) an increased gradient in the moisture content difference between surface and core layer. 

Water or steam injection reduces flame temperatures and thus thermal NO,. Water injection is especially effective for gas turbines, reducing NO, emissions by about... 

The drum is usually equipped with steam injection if required for winterizing or cold releases. Refer to Figure 7 for some of the details. If winterizing is necessary, then the steam should be temperature-controlled in order to maintain the seal water temperature at 4 to 10 C. It is important to note that the drum should be located at a minimum safe distance from the flare. 

Flare systems must be protected against any possibility of partial or complete blockage by ice, hydrates, solidification, etc. Seal Drums and Y-seals requiring winterizing should be provided with temperature-controlled steam injection to maintain the seal water temperature at 4 to 10 C. This limits the quantity of water vapor entering the flare stack. 

Fig. 6.2 shows a simplified diagram of the basic STIG plant with steam injection S per unit air flow into the combustion chamber the state points are numbered. Lloyd 2 presented a simple analysis for such a STIG plant based on heat input, work output and heat rejected (as though it were a closed cycle air and water/steam plant, with external heat supplied instead of combustion and the exhaust steam and air restored to their entry conditions by heat rejection). His analysis is adapted here to deal with an open cycle plant with a fuel input/to the combustion chamber per unit air flow, at ambient temperature To, i.e. a fuel enthalpy flux of/7i,o. For the combustion chamber, we may write... 

Where it is available the source can be a separate boiler plant, but common practice is to employ purpose-made electrode boilers within or adjacent to the plant. The latter reduces sensible gains to the plant but, being essentially saturated steam, condensate return pipes are required. In addition to the rise in moisture content of the air (kg/kg) being dependent on airflow and steam-injection rates, there is a very small increase in dry bulb temperature by the cooling of the vapor to the air temperature. The rise in total heat is total heat of steam (kJ/kg) x quantity supplied per kg air. 

This can he done in several ways, depending on the method of adding the moisture and final dry hulh control (see Figure 24.12). If hy steam injection, the air can he pre-heated to just helow 30°C and the steam blown in (line ABC). To give better control of the final temperature, the steam may be blown in at a lower condition, with final re-heat to get to the right point (line ADEC). 

Raise the FW temperature to as high a level as practically possible using returned condensate, live steam injection, or FW heaters. 

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