Posts Tagged ‘steam boiler’
I have been asked over the years “What is a boiler horsepower” and what is the design criterion of square feet of heating surface per boiler horsepower.
We have written many articles about flame safe guard controls on Control Trends but we have not really given an explanation on the basic principles of these controls.
Stromquist and Company does not sell fire tube boilers but we do sell a vast amount of controls for these boilers from manufactures such as Conbraco, Honeywell, Asco, McDonnell & Miller, Maxitrol, and numerous other control manufacturers. The understanding of these boilers is a major concern in our continuing efforts to keep our readers informed.
FIRE TUBE BOILERS:
In a fire tube steam boiler, heat and gases of combustion pass through the tube surrounded by water. Fire tube boilers steam boilers maybe either high or low pressure boilers. The three types of fire tube steam boilers are horizontal return tubular boiler, scotch marine boiler, and vertical fire tube boiler.
Proper boiler blowdown is an essential part of firetube boiler operating proceedures. It is necessary to control the amount of TDS (total dissolved solids) in the boiler water.The total TDS should not exceed 3500 parts per million in a scotch marine boiler. If the blowdown is not controlled, excessive dissolved solids will have a tendency to increase and concentrate to a point that will cause a foaming or a carry over condition which will contaminate the steam.
The following is a list of what causes a LWCO switch to malfunction taken from the McDonnell & Miller Service Guide.
Honeywell Burner Boiler Flame Safeguard Training Classes
Need to replace the older M series Fireye controls? Honeywell has introduced the Honeywell ECHO retrofit solution for replacing the Fireye TFM and UVM FSG controls. The ECHO (R7210M series) controls are a Smart Fit series of controls which allow the contractor to replace the older Fireye M series controls without the extensive wiring required in the past.
The Honeywell ECHO system is based on the standard Honeywell 7800 series controls and all of the standard 7800 series components will work with this control. With the Honeywell ECHO you can now expand the functions that were limited on the Fireye M Series controls to include displays that improve diagnostics and troubleshooting and including the addition of Modbus to connect the equipment to a building automation system.
How easy is the Honeywell ECHO system to install? Simply remove the old Fireye M series control, attach the Echo’s metal conversion frame, and plug in the ECHO control… Add the required purge timing card (if needed), the flame amplifier , and the Flame detector for UV systems…It’s that easy…
While your at it sign up for the Stromquist & Company Boiler Vision Program and save even more !!
So when you need to replace an older Fireye M series control give us a call here at Stromquist and Company and listen to the ECHO….
Over the years I have been asked how to properly pipe a steam heat exchanger. I developed the drawing below to help answer this question. There are other piping additions that can be added according to your needs, and this drawing does not cover all the additions but should serve as a good workable starting point. A few points to remember…1. A vacuum breaker and/or vent should be installed…. 2. The steam trap should be properly sized for the amount of the pounds per hour steam capacity of the heat exchanger, and the trap should be sized for the pressure at the trap not for the inlet pressure of the control valve…3. A properly sized relief valve must be installed on the hot water outlet side to protect the heat exchanger from possible damage due to volumetric expansion.
I hope this answers some questions you may have. If you need more answers please call Stromquist and Company at 1-800-241-9471, and we would be happy to finalize an answer for you.
Honeywell has added a new Delphi video presentation to its Environmental and Combustion Controls website.
Go to: http://customer.honeywell.com/Business/Cultures/en-US/Default.htm and look to the left of the page under the “What’s New” section, then click on the Delphi Combustion Efficiency Panel Video Presentation (in red) and follow instructions to the video.
Other Delphi and related Information:
http://www.controltrends.org/2010/02/on-site-training-for-honeywell-delphi-2/
http://www.controltrends.org/2009/11/first-commercial-installation-of-delphi/
http://www.controltrends.org/2009/08/honeywell-announces-delphi/
http://www.controltrends.org/2009/08/simply-amazing-product/
http://www.controltrends.org/2009/08/honeywell-abc900-advanced-burner-control/
http://www.controltrends.org/2009/08/honeywell-mf020-oxygen-sensors/
Boiler contractors see these valves all the time when working on equipment. Generally the steam relief valve is often little understood, often incorrectly installed, and usually neglected. A little refresher on these valves might be in order.
How Relief Valves Work
As the pressure of the steam within a boiler approaches the set pressure of the valve, the steam pressure on the underside of the actuating disc approaches the pressure of a spring applied to the outer side of the disc. When equilibrium is passed, the disc starts to lift off its seat. The moment this happens, steam is suddenly released all around the disc to what is called the “huddling chamber.” This chamber increases the area of the disc that sees steam pressure, thus increasing force. This increased area under steam pressure makes the pressure much more unbalanced in the direction of the valve discharge opening and therefore pops the valve into a wide open position. When the valve opens with a “pop” the valve seat is preserved from wiredraw caused by slow opening.
Closure of the valve occurs only after the boiler pressure is dropped several pounds below the set point. The reduction of the area of the disc seeing steam causes the disc to firmly close against the valve seat.
Relief Valve Installation
Proper installation of a steam relief valve seems somewhat simple and is, as long as two areas of concern are followed.
The first area of concern is valve distortion. Valve distortion occurs when the valve is improperly wrenched in, using the valve body instead of supplied wrench flats. Distortion also occurs when the discharge side of the safety relief valve is made to bear the weight of the discharge piping. To prevent this distortion use a short nipple from the valve to an independently supported bell reducer or drip pan elbow. These valves are precision devices and any distortion will affect accuracy and calibration.
The second area of concern is discharge piping. For a safety valve to do its job it must be sized properly to adequately relieve all the steam the boiler is capable of producing while operating at its maximum. All piping to or from a safety relief valve must be at least as large as the valve’s connections. Also, the restrictive effect of elbows and the friction losses in pipe must be taken into account. For this reason, piping runs should be as short as possible and pipe sizes should be generous.
If you need help in replacing or sizing a steam relief valve please contact Stromquist and Company at 1-800-241-9471. All others can order this product from one of our affiliates at CGNA.
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