Wild stream

Ratio control is a special type of feedforward control where two disturbances (loads) are measured and held in a constant ratio to each other. It is mostly used to control the ratio of flow rates of two streams. Both flow rates are measured but only one can be controlled. The stream whose flow rate is not under control is usually referred to as wild stream. 

Figure 21.9a and b show two different ratio control configurations for two streams. Stream A is the wild stream. 

V.26 (a) Develop a ratio control system to regulate the temperature T of the resulting mixture of Figure PV.5. The following specifications are provided (1) Stream 1 is the wild stream. Its temperature remains constant but its flow rate changes in an unpredictable manner. (2) The temperature of stream 2 remains constant. 

Figure 9.41 shows the essentials of the process. Hydrogen and chlorine enter the burner separately. In most cases in the chlor-alkali industry, chlorine is the wild stream and the flow of hydrogen is controlled to give the desired ratio. The chlorine flow may be variable, as from the end of a process. When HCl production volume is large or... 

In the scheme shown in Figure 6.10, the flow of the wild stream y is measured and then multiplied by the desired ratio. The output from the multiplier is the set point for the controller, which compares it with the measured flow and adjusts the flow of y... 

Two sources of absorption oil are normally utilized in this tower. The first is the hydrocarbon liquid from the main fractionator overhead receiver. This stream, often called wild, or unstabilized, naphtha, enters the absorber a few trays below the top tray. The second absorbent is cooled debutanized gasoline, which generally enters on the top tray. It has a lower vapor pressure and can be considered a trim absorbent. The expression lean oil generally refers to the debutanized gasoline plus the unstabilized naphtha from the overhead receiver. 

Bjerregaard, L.B., Korsgaard, B., and Bjerregaard, P. (2006). Intersex in wild roach (Rutilus ruti-lus) from Danish sewage effluent-receiving streams. Ecotoxicology and Environmental Safety 64, 321-328. 

The danger to domestic animals, including pets, is an important hazard in the use of all newer economic poisons. Drift dusts or sprays from carelessly applied materials may set back the useful development of many valuable chemicals. Only recently have authorities finally decided that we should slow down on the use of DDT on cows until we know more about the occurrence of the chemical in rtiilk, butter, and steaks. Our sportsmen and, incidentally, a major economic factor in our pleasant way of life—the fish, game, and wildlife activities—are part and parcel of the problem of chemical usage in forests and streams. We need continued and expanded investigations of the effects of the newer pesticides on wild life. 

Pennants of silver waved and streamed, lazy banners unfurled Sudden splendors of sabres gleamed, lightning javelins were hurled. There in our awe we crouched and saw with our wild, uplifted eyes. Charge and retire the hosts of fire in the battlefield of the skies. 

As the name implies, ratio control involves keeping constant the ratio of two or more flow rates. The flow rate of the "wild or uncontrolled stream is measured and the flow rate of the manipulated stream is changed to keep the two streams at a constant ratio with each other. Common examples include (1) holding a constant reflux ratio on a distillation column, (2) keeping stoichiometric amounts... 

However, we can describe the basic structure of several feedforward control systems. Figure 8.7 shows a blending system with one stream which acts as a disturbance both its flow rate and its composition can change. In Fig. 8.7a the conventional feedback controller senses the controlled composition of the total blended stream and changes the flow rate of a manipulated flow. In Fig. %.lb the manipulated flow is simply ratjoed to the wild flow. This provides feedforward control for flow rate changes. Note that the disturbance must be measured to implement feedforward control. 

Halleraker JH, Saltveit SJ, Harby A, Amekleiv JV, FJeldstad HP, Kohler B (2003) Factors influencing stranding of wild juvenile brown trout (Salmo trutta) during rapid and frequent flow decreases in an artificial stream. River Res Appl 19 589... 

There are rumors that the seer s sage may grow wild on some of the less accessible plateaus in Oaxaca, but this is unconfirmed. Her people grow the plant beneath coffee trees, or along streams in ravines. They reportedly do not grow it next to their homes. 

Controlled stream is manipulated to maintain a constant ratio (R) of controlled flow (B) to wild flow (A). 

TUB-1880 — U.S. origin. Collected from population of six plants in West Virginia (Greenbrier County), in wild near stream, by G. Seiler and D. Skoric, in 1985. Available (accession PI 503263) from USDA, ARS, National Genetic Resources System, NCRPIS, Ames, IA 50011, U.S. Maintained by the Institute of Field and Vegetable Crops, Novi Sad, Serbia and Montenegro (Cat. 1320). 

---