{"id":622,"date":"2018-03-29T14:44:54","date_gmt":"2018-03-29T14:44:54","guid":{"rendered":"http:\/\/www.preferred-mfg.com\/blog\/?p=622"},"modified":"2018-03-29T14:45:29","modified_gmt":"2018-03-29T14:45:29","slug":"622-2","status":"publish","type":"post","link":"https:\/\/www.thepyroscope.com\/blog\/622-2\/","title":{"rendered":"The Three T’s of Combustion"},"content":{"rendered":"

\"\"<\/a>Most of us benefit from some sort of combustion every day.\u00a0Whether for the release of heat or the expansion of gas to perform work, this special category of oxidation is probably the most widely-used chemical reaction in our daily lives.\u00a0Like most chemical reactions, there are parameters that need to be present not only for the reaction to take place, but to be the most efficient.<\/p>\n

For combustion, we follow the Three T\u2019s\u2026time, temperature, and turbulence.<\/em><\/p>\n

The\u00a0time<\/em>\u00a0of combustion refers to the rate of the reaction.\u00a0The fuel (natural gas for example), is introduced to the furnace through injectors or pokers.\u00a0These are usually pipes with a plate at the end with several holes (some call this a poker \u201cshoe\u201d).\u00a0The volumetric rate, the size and the quantity of holes will result in a design gas velocity at each hole in the poker shoe.\u00a0Remember also, most burners modulate, so as the firing rate changes so will the gas velocity.\u00a0This range of gas velocities need to coincide with the rate of the combustion.\u00a0Gas velocities too high result in the flame \u201cleaving the zone\u201d of combustion which can cause unburned fuel or flame outs.\u00a0Gas velocities too low can result in \u201cpuffs\u201d or a \u201cpunky\u201d flame similar to when you shut the gas off to your grill (okay for barbecues, but not for your boiler).<\/p>\n

The\u00a0temperature<\/em>\u00a0of combustion is more intuitive.\u00a0We all know we need to \u201cignite\u201d the flame to start the reaction, but what does that mean?\u00a0Simply, we are introducing heat with a spark or pilot flame at the point where air and fuel are mixed to start the reaction.\u00a0Once the reaction is started, it provides the heat to maintain the temperature to keep the reaction going. Those familiar with gas pilots know adjusting the pilot gas pressure is key to making the pilot flame reliable.\u00a0Make sure there is a separate pilot gas regulator to accomplish this.<\/p>\n

The\u00a0turbulence<\/em>\u00a0of combustion is the \u201cmixing\u201d of the ingredients\u2026fuel and air.\u00a0Those who have seen the heads of burners know the multitudes of designs to create turbulence at the combustion zone.\u00a0This creates good mixing and efficient combustion.\u00a0Poor mixing can allow unburned fuel to create unwanted compounds in the flue gas like carbon monoxide.\u00a0Burner designers also consider the size and shape of the furnace.\u00a0A turbulence pattern that makes the flame too wide or too long can result in flame impingement.<\/p>\n

Burner technicians use a stack gas analyzer and a sight glass at the back of the boiler to make their final adjustments for the most efficient combustion.\u00a0They also do this when the furnace is at normal operating temperature as a \u201chot\u201d furnace has different combustion characteristics than a \u201ccold\u201d furnace.<\/p>\n

So next time you\u2019re in the boiler room, take a peek at the flame and look for the Three T\u2019s.<\/p>\n

 <\/p>\n

– Robert Frohock, PE<\/p>\n","protected":false},"excerpt":{"rendered":"

Most of us benefit from some sort of combustion every day.\u00a0Whether for the release of heat or the expansion of gas to perform work, this special category of oxidation is probably the most widely-used chemical reaction in our daily lives.\u00a0Like most chemical reactions, there are parameters that need to be present not only for the reaction to take […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"content-type":"","footnotes":""},"categories":[32,12],"tags":[],"_links":{"self":[{"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/posts\/622"}],"collection":[{"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/comments?post=622"}],"version-history":[{"count":3,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/posts\/622\/revisions"}],"predecessor-version":[{"id":626,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/posts\/622\/revisions\/626"}],"wp:attachment":[{"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/media?parent=622"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/categories?post=622"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.thepyroscope.com\/blog\/wp-json\/wp\/v2\/tags?post=622"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}