เกจวัดแรงดันน้ำ4หุน . Fischer, P.E., is a physicist and electrical engineer who spent 25 years in chemical crops and refineries. Fischer can be a part-time school professor. He is the principal reliability advisor for Fischer Technical Services. He may be reached at bobfischer@fischertechnical.com.
One of Dirty Harry’s well-known quotes was: “A man’s received to know his limitations.” This story illustrates why you should know your management valve’s limitations.
A consumer recently called for assist downsizing burners on a thermal oxidizer. Changes in the manufacturing course of had resulted in an extreme quantity of heat from the prevailing burners. All makes an attempt to lower temperatures had ended in unstable flames, flameouts and shutdowns. The larger temperatures didn’t hurt the product however the burners were guzzling one hundred ten gallons of propane every hour. Given the excessive value of propane at that plant, there were, actually, hundreds of thousands of incentives to preserve energy and reduce prices.
Figure 1. Operation of a cross linked 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 project to retrofit smaller burners was being written. One of the plant’s engineers referred to as for a value estimate to change burner controls. As we discussed their efforts to reduce back fuel usage, we realized smaller burners won’t be required to unravel the issue.
Oxidizer temperature is basically decided by the place of a “combustion air” control valve. Figure 1 reveals how opening that valve increases strain in the combustion air piping. Higher pressure forces more air through the burners. An “impulse line” transmits the air strain to 1 aspect of a diaphragm within the “gas management valve” actuator. As air strain on the diaphragm increases, the diaphragm strikes to open the valve.
The gas valve is automatically “slaved” to the combustion air being supplied to the burner. Diaphragm spring rigidity is adjusted to deliver the 10-to-1 air-to-gas ratio required for steady flame.
The plant was unable to maintain flame stability at considerably lower fuel flows because there’s a restricted vary over which any given diaphragm spring actuator can provide accurate management of valve place. This usable management vary is called the “turndown ratio” of the valve.
In this case, the plant operators no longer wanted to fully open the gasoline valve. They needed finer resolution of valve place with much lower combustion air flows. The diaphragm actuator needed to find a way to crack open after which management the valve utilizing considerably lower pressures being delivered by the impulse line. Fortunately, changing the spring was all that was required to permit recalibration of the fuel valve actuator — utilizing the prevailing burners.
Dirty Harry would definitely approve of this cost-effective change to the valve’s low-flow “limitations.” No capital challenge. No burner replacements. No significant downtime. Only a quantity of cheap parts and minor rewiring have been required to save “a fistful of dollars.”
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