Compressor control

Source John Hampel, Basic Turhocompressor Control and Protection, Turbomachinery International, July/August 1995, Compressor Controls Corporation, Des Moines, Iowa. 

Compressor Controls Corporation 11359 Aurora Avenue Des Moines, lA 50322, USA Tel 515-270-0857 Fax 515-270-1331... 

Figure 6-6. An axial compressor controlled diffusion airfoil. Courtesy of Elliott Compan]/)...

Some consideration of surge characteristics should be made, and unless your own plant design includes antisurge controls, it should definitely be mentioned in the specification. Possibly, the vendor can quote antisurge equipment with his offering. At a later date, the specification will serve as a good reminder to both the vendor and purchaser if some mention of compressor control is made. The details may be worked out at any convenient point, such as at the bid review or possibly later in a coordination meeting. 

More Flow Failure of compressor controls High rate of reaction, high reactor temperature high-temperature alarms (TA1)... 

II. Chemostat In a chemostat, the medium is delivered at a constant rate, to keep constant growth rate. The nutrient medium is supplied to the culture vessel at a constant rate by a peristaltic pump used to control the washout rate. The rate of media flow is often set at approximately 20% of culture volume per day. Air is pumped into the algal culture vessel through an air compressor controlled by a flow meter and carried in two flasks of sterile water. This bubbling air has three effects (i) it supplies C02 and 02 to the culture, (ii) allows circulation and agitation of the cultures and (iii)... 

Failure of intercooler during startup of gas compressor, control room destroyed... 

Assuming a theoretical efficiency of the fuel-cell system of around 60% and an electric-drive-train efficiency of 90%, the overall fuel-cell system efficiency is about 55%. The theoretical efficiencies for a fuel cell cannot be realised in practice. The efficiency of the system (including fuel treatment, air supply and others) is already lower than that of the pure fuel-cell stack on its own the overall efficiency of the FC drive train falls to less than 40% as a result of additional components, such as compressors, control electronics and others, see Fig. 13.6. 

Master unit Ozone generator, compressor, controller, power snpply for in-well pnmps 10,500... 

In the PCU and primary system, however, there is only one compressor to manage mass flow rate while there are several different circuits. To achieve the desired control of helium mass flow rate compressor control provides little flexibility. Rather inventory control is used to obtain a flow rate proportional to heat exchanger power. Because density is proportional to pressure for fixed temperature, by varying pressure and maintaining constant speed turbo-machinery, gas velocity remains constant and mass flow rate (proportional to the product of density and velocity) is linear with pressure. Thus, pressure is manipulated through coolant mass inventory so that it is proportional to heat exchanger power so that in turn mass flow rate is proportional to heat exchanger power. Results obtained for this control scheme are described below. 

Compressor controls play an important role in the optimization of renewable energy processes. Their applications are discussed in detail in connection with hydrogen processing (see Chapter 1, Section 1.5.5), geothermal power plants (see Section 1.3.4), and heat pumps (see Section 2.4). 

Figure 7.2 Compressor controls.

An important design tool is the use of "Dynamic Simulation". This computer modeling technique was used to verify that the control systems were adequate for the purchased equipment (such as pumps, compressors, control valves, heat exchangers and pipe sizing) and were in fact going to meet our stated control objective. 

Composition sensors, 249, 252 Compressor control, 37 selective control, 403-4 Computer, digital, 552-57 Computer control, 30-33, 561-66, 634-55... 

The other principal cause of low pressure is a malfunction of the hydrogen compressor control, which could allow the header pressure to drop very quickly below atmospheric. Section 11.4.2.4 covers the relevant protective systems. 

This scheme should prove more robust as gas composition and other operating conditions vary. It is thus often used in proprietary compressor control systems. 

Compressor control packages are often supplied as black boxes and many compressor manufacturers insist on them being installed in special control systems on the basis that DCS-based schemes would be too slow. Chapter 11 describes how these schemes work and, using the tuning method in Chapter 3, how they might be implemented in the DCS. 

The wind can influence the location of such equipment as furnaces, compressors, control houses, cooling towers, and stacks. Furnaces or other fired equipment should be located so as not to allow flammable vapors to constantly drift. Smoke from stacks or vapors... 

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