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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 school professor. He is the principal reliability consultant for Fischer Technical Services. He could additionally be reached at bobfischer@fischertechnical.com.
One of Dirty Harry’s well-known quotes was: “A man’s got to know his limitations.” This story illustrates why you should know your management valve’s limitations.
A client just lately known as for assist downsizing burners on a thermal oxidizer. Changes within the manufacturing course of had resulted in too much heat from the present burners. All makes an attempt to decrease temperatures had led to unstable flames, flameouts and shutdowns. pressure gauge วัด แรง ดัน น้ำ didn’t harm the product however the burners had been guzzling one hundred ten gallons of propane each hour. Given the excessive price of propane at that plant, there were, literally, hundreds of thousands of incentives to preserve power and cut back costs.
Figure 1. Operation of a cross connected air/gas ratio regulator supplying a nozzle mix burner system. The North American Combustion Practical Pointers e-book could be found 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 referred to as for a worth estimate to change burner controls. As we discussed their efforts to reduce fuel utilization, we realized smaller burners might not be required to solve the problem.
Oxidizer temperature is mainly decided by the place of a “combustion air” control valve. Figure 1 exhibits how opening that valve increases stress within the combustion air piping. Higher pressure forces extra air through the burners. An “impulse line” transmits the air pressure to at least one aspect of a diaphragm in the “gas management valve” actuator. As air pressure on the diaphragm increases, the diaphragm moves to open the valve.
The fuel valve is automatically “slaved” to the combustion air being equipped to the burner. Diaphragm spring tension is adjusted to deliver the 10-to-1 air-to-gas ratio required for secure flame.
The plant was unable to take care of flame stability at significantly lower gas flows because there’s a restricted vary over which any given diaphragm spring actuator can present accurate control of valve place. This usable management range is called the “turndown ratio” of the valve.
In this case, the plant operators not needed to fully open the gasoline valve. They wanted finer resolution of valve place with much decrease combustion air flows. The diaphragm actuator wanted to have the ability to crack open and then control the valve using considerably decrease pressures being delivered by the impulse line. Fortunately, altering the spring was all that was required to permit recalibration of the gasoline valve actuator — utilizing the existing burners.
Dirty Harry would undoubtedly approve of this cost-effective change to the valve’s low-flow “limitations.” No capital project. No burner replacements. No vital downtime. Only a quantity of cheap components and minor rewiring had been required to save heaps of “a fistful of dollars.”
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