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Robert L. Fischer, P.E., is a physicist and electrical engineer who spent 25 years in chemical vegetation and refineries. Fischer can be a part-time faculty professor. He is the principal reliability advisor for Fischer Technical Services. He may be reached at bobfischer@fischertechnical.com.
One of Dirty Harry’s famous quotes was: “A man’s received to know his limitations.” This story illustrates why you have to know your management valve’s limitations.
A client recently known as for help downsizing burners on a thermal oxidizer. Changes within the manufacturing process had resulted in an extreme amount of heat from the present burners. All attempts to decrease temperatures had resulted in unstable flames, flameouts and shutdowns. The larger temperatures didn’t hurt the product but the burners were guzzling one hundred ten gallons of propane every hour. Given the high price of propane at that plant, there have been, literally, millions of incentives to preserve vitality and reduce prices.
Figure 1. Operation of a cross related air/gas ratio regulator supplying a nozzle combine burner system. The North American Combustion Practical Pointers e-book could be discovered online at https://online.flippingbook.com/view/852569. Fives North American Combustion, Inc. 4455 East 71st Street, Cleveland, OH 44015. Image courtesy of Fives North American Combustion, Inc.
A capital challenge to retrofit smaller burners was being written. One of the plant’s engineers known as for a value estimate to change burner controls. As we discussed their efforts to reduce fuel utilization, we realized smaller burners won’t be required to unravel the problem.
Oxidizer temperature is mainly determined by the position of a “combustion air” management valve. Figure 1 reveals how opening that valve increases stress within the combustion air piping. Higher pressure forces more air through the burners. An “impulse line” transmits the air strain to 1 facet of a diaphragm within the “gas management valve” actuator. As air pressure on the diaphragm increases, the diaphragm strikes to open the valve.
The gas valve is routinely “slaved” to the combustion air being provided to the burner. เกจวัดแรงดัน is adjusted to ship the 10-to-1 air-to-gas ratio required for stable flame.
pressure gauge was unable to hold up flame stability at considerably decrease gasoline flows as a result of there is a restricted vary over which any given diaphragm spring actuator can present accurate control of valve place. This usable control vary is called the “turndown ratio” of the valve.
In this case, the plant operators no longer wanted to totally open the fuel valve. They wanted finer resolution of valve place with a lot decrease combustion air flows. The diaphragm actuator needed to have the flexibility to crack open and then control the valve utilizing considerably decrease pressures being delivered by the impulse line. Fortunately, changing the spring was all that was required to permit recalibration of the gasoline valve actuator — using the present burners.
Dirty Harry would undoubtedly approve of this cost-effective change to the valve’s low-flow “limitations.” No capital challenge. No burner replacements. No important downtime. Only a couple of cheap parts and minor rewiring have been required to keep away from wasting “a fistful of dollars.”

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