Fischer: Know your valve’s limitations 

Robert L. Fischer, P.E., is a physicist and electrical engineer who spent 25 years in chemical crops and refineries. Fischer can be a part-time college professor. He is the principal reliability marketing consultant 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 want to know your management valve’s limitations.
A consumer recently called for assist downsizing burners on a thermal oxidizer. Changes within the manufacturing process had resulted in too much heat from the existing burners. All makes an attempt to decrease temperatures had resulted in unstable flames, flameouts and shutdowns. The higher temperatures didn’t harm the product but the burners were guzzling a hundred and ten gallons of propane every hour. Given the high value of propane at that plant, there have been, literally, millions of incentives to conserve power and scale back prices.
Figure 1. Operation of a cross connected air/gas ratio regulator supplying a nozzle combine burner system. The North American Combustion Practical Pointers book could be discovered on-line 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 venture to retrofit smaller burners was being written. One of the plant’s engineers known as for a value estimate to alter burner controls. As we discussed their efforts to minimize back gas usage, we realized smaller burners may not be required to unravel the issue.
Oxidizer temperature is mainly decided by the place of a “combustion air” control valve. Figure 1 shows how opening that valve increases strain in the combustion air piping. Higher pressure forces more air via the burners. An “impulse line” transmits the air strain to 1 aspect of a diaphragm in the “gas control valve” actuator. As air pressure on the diaphragm will increase, the diaphragm moves to open the valve.
The gas valve is mechanically “slaved” to the combustion air being supplied to the burner. เกวัดแรงดัน is adjusted to ship 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 fuel flows as a end result of there is a restricted range over which any given diaphragm spring actuator can present accurate control of valve position. This usable management range is known as the “turndown ratio” of the valve.
In ราคาเกจวัดแรงดันน้ำ , the plant operators no longer needed to fully open the gas valve. They needed finer decision of valve place with much lower combustion air flows. The diaphragm actuator needed to have the ability to crack open after which control the valve utilizing significantly decrease pressures being delivered by the impulse line. Fortunately, altering the spring was all that was required to allow recalibration of the gasoline 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 vital downtime. Only a couple of inexpensive parts and minor rewiring had been required to avoid wasting “a fistful of dollars.”
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