3/18/15 The Art of Steam Use in Bread and Roll Ovens Presented by Mike Day Agenda • 
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Types of Products BenefiMng from Applied Steam Steam and ProperMes Beneficial in Baking Process CondiMoning and ApplicaMon of Steam in Bakery Ovens InstallaMon and Use of Steam in High ProducMon Ovens –  Bread and Roll March 3, 2015 Chicago, IL Why use steam? ApplicaMon Benefits of Steam •  Promotes crust development and desirable characterisMcs •  Bread •  Rolls –  Hearty/Crispy top crust –  Strength and pliability –  Avoid crust cracking during “oven spring” of the bake •  Produce product characterisMcs desirable to Consumer Steam Defined as: “Water vapor at the boiling point temperature for a given corresponding pressure.” Steam ProperMes/Forms of water: 1.  Solid – Ice 2.  Liquid – Liquid water 3.  Vapor – Vapor phase of water 1 3/18/15 Steam •  At standard atmospheric condiMons (0 psig – Sea Level) –  Water boils @ 212° F •  At non-­‐standard atmospheric condiMons (pressures or elevaMons other than Sea Level) water has a different boiling temperature! Steam Steam For example: –  Miami, FL (@ Sea Level) water boils at 212° F –  Denver, CO (@ 5,280 FAS) water boils at 202° F –  Mexico City, MX (@ 7,382 FAS) water boils at 198° F Steam •  Every atmospheric pressure has a corresponding temperature at which water boils. Saturated Steam Table •  Referred to as “Satura,on Temperature” How is Steam Generated? How is Steam Generated? 1st Water heated to its SaturaMon Temperature •  Latent Heat of VaporizaMon is absorbed by water –  e.g. 212° F @ 0 psig or 240° F @ 10 psig) –  SMll in Liquid form! 2nd Water must absorb addiMonal energy to cause Phase Change –  970 BTU/Lb. of water –  AddiMonal heat known as “Latent Heat of Vaporiza,on” –  Progressively changes from Liquid phase to Vapor phase –  Once water has completely absorbed necessary Latent Heat phase change from liquid to vapor is fully complete –  During Latent Heat absorpMon and phase change temperature remains unchanged. •  Water in its Vapor phase is Steam! 2 3/18/15 How is Steam Generated? Steam Quality •  Defined as 100% less % mass of liquid water entrained e.g. 100% – 5% liquid water mass = 95% Steam Quality •  As water transiMons from liquid to steam, Steam Quality transiMons from 0% to 100% •  AbsorpMon of addiMonal heat results in “Super Heated” steam Steam Quality
Steam in the Bakery •  Common Baker vs. Engineer terms for Steam Baker Engineer Dry Steam Dry Saturated Steam Wet Steam Dry Saturated Steam with Entrained Water Hard Steam Super Heated Steam Sok Steam Dry Super Heated Steam with Entrained Water Gaseous Steam All Steam is Gaseous •  Typically generated by a boiler –  Located somewhere in the bakery –  Oken remote from the oven •  Boiler generates steam pressure range of: –  5 – 7 psig –  10 – 12 psig –  90 – 100 psig (and higher!) Steam in the Bakery Steam in the Bakery •  DistribuMon: •  Steam distribuMon to oven designed to supply an appropriate quanMty –  Boiler •  Steam Source –  Distributed via piping including: • 
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Headers Takeoffs Runs Drops –  General Rule of thumb: •  1 to 1¼ BHP per 100# of product •  1 BHP ≡ 34.5 pph (from and @ 212° F) •  e.g. 6000# per hr. product requires 60 to 75 BHP of boiler steam (Based on tradi;onal Rule of Thumb sizing) 3 3/18/15 Steam in the Bakery Steam in the Bakery •  DistribuMon piping needs to be sized and configured properly •  Steam CondiMoning –  Steam typically delivered above needed pressure •  5-­‐7 psig, 10-­‐12 psig (or higher!) •  Pressure & corresponding saturaMon temperature too high for baking •  Pressure reduced locally at the oven to 1-­‐3 psig. –  Minimize steam velociMes and noise (pipe sizing) –  Minimize entrained condensate (drip legs and steam traps) –  Filter any contaminants (strainers) – 
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Pressure Reducing Valve (PRV) Throrling process (AdiabaMc – constant heat) Reduced pressure steam contains Super Heat Steam Super Heat – Steam that has a BTU/Lb. content at a higher temperature than does saturated steam at the same pressure condiMon Steam in the Bakery Steam in the Bakery •  Steam CondiMoning •  Why CondiMon Steam? Example 1: –  Eliminate Super Heat •  10 psig sat. steam is 240° F and 1159 BTU/Lb. •  Reduced 3 psig sMll 240° F and contains 6 BTU/Lb. Super Heat •  Also stated as Degrees of Super Heat •  Retards moisture formaMon on top surface of dough •  Over heats top surface of the dough –  Returns steam to saturated condiMon prior to applicaMon to product –  CondiMon steam to saturated pressure / temperature @ 1-­‐3 psig –  Degrees of Super Heat = 240° F -­‐ 221 ° F or 19 ° F of Super Heat –  Example 2: •  Promotes applicaMon of moisture and heat to product top surface •  Allows steam to more easily give up its Latent Heat and phase change back to liquid water •  100 psig sat. steam is 338° F and 1190 BTU/Lb. •  Reduced 3 psig sMll 338° F and contains 37 BTU/Lb. Super Heat •  Also stated as Degrees of Super Heat –  Moisture (in the form of condensaMon) forms on top of dough –  Transfer Latent Heat to top of dough –  Degrees of Super Heat = 338° F -­‐ 221 ° F or 117 ° F of Super Heat Steam in the Bakery Steam in the Bakery Oven Steam CondiMoner 4 3/18/15 Steam Use at the Oven Steam Use at the Oven •  Steam Use at the Oven •  Steam used primarily for 2 reasons: 1.  Prevent Cracking of the Crust –  “Steam Zone” •  Maintains pliable surface during Oven Spring •  IniMal stages of the “Bake” •  Up to first 15% of travel –  Helps prevent crust cracking –  Typically achieved with limited applicaMon of moisture and heat from steam –  EnMre steam zone may not be required! 2.  Heat dough surface to range of 165° F to 200° F •  Causes gelaMnous like paste to form •  Results in the desirable glossy finished product Steam Use at the Oven Steam Use at the Oven •  How does steam do this? •  How does steam do this? (ConMnued) –  Enters bake chamber through Steam Lances –  Distributed throughout selected zone of the bake chamber –  Injected steam condiMoned –  Heat from absorbed steam gives up its Latent Heat of VaporizaMon –  Steam Quality is reducing due to Steam Vapor changing phase back into liquid water form. –  Process known as “CondensaMon” •  To 1-­‐3 psig •  Saturated (215° F – 221° F) –  In contact with cool (95° F – 98° F) dough surface –  Temperature differenMal causes heat from steam to transfer to dough’s surface •  Source of moisture on dough surface Steam Use at the Oven The “Art” of Baking with Steam •  How does steam do this? (ConMnued) –  Condensing steam provides source of heat •  Absorbed Latent Heat of VaporizaMon •  Creates gelaMnizaMon of starches on dough surface •  Source of “varnish like” shinny gloss finish The “Baker” must control the amount and duraMon of steam applicaMon for desired results of final product! This is the “Art”! 5 3/18/15 Steam in the Oven Bake Chamber Steam in the Oven Bake Chamber •  CondiMoned steam supplied to side oven steam secMon –  Typically piped to a local steam lance header –  Dedicated takeoffs supply steam to each steam lance –  Typically 4 to 6 steam lances in oven steam zone •  Each fiBed with a manual metering valve –  Used to control steam distribuMon within the bake chamber –  Important to configure local steam piping properly •  Drips and traps •  Eliminate water droplets collecMng in the lances and dripping down onto product Typical Steam DistribuMon Side of Oven Steam in the Oven Bake Chamber Steam in the Oven Bake Chamber •  Burners within the steam secMon of the oven •  All burners On –  All On / All Off / Some On and Some Off? –  Maintain typical Zone 1 temperature of 380° – 400° F –  Retard steam from condensing by adding addiMonal heat within bake chamber’s steam secMon •  Purpose of adding steam into Bake Chamber –  Allow steam to condense causing moisture to collect at the surface of the dough –  Steam must give up its Latent Heat of VaporizaMon for this to occur •  All burners Off may delay Oven Spring creaMng –  PotenMal for crust cracking –  Possibly extend bake Mmes Steam in the Oven Bake Chamber Other Bake Chamber Factors •  A balance must be struck that allows steam to condense on cool dough surface while providing enough heat to induce oven spring while top surface of the dough is moist and pliable. •  Steam Baffle
This is the “Art”! –  At transiMon of product travel out of steam secMon –  Manages steam migraMon beyond steam zone into downstream bake chamber zones –  Fabricated from •  Hinged Stainless Steel •  Weighted Hanging Teflon Woven fabric curtain 6 3/18/15 Other Bake Chamber Factors Other Bake Chamber Factors •  Oven Exhaust When Using Steam –  Typically have an exhaust point just upstream of steam baffle –  970 or 960 ovens steam damper •  Similar in design to the rear damper or main exhaust damper –  Non-­‐steam baking condiMons •  PosiMon steam damper to closed minimum exhaust –  Steam baking condiMons •  Adjust to remove excess residual steam •  Reduce or eliminate migraMon of steam beyond steam baffle •  May necessitate adjustment of the main rear exhaust damper –  Ensure proper oven exhaust –  Desired final product moisture Front Exhaust / Steam Damper Summary • 
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Types of products to which team is applied Steam and its properMes beneficial in the baking process Steam condiMoning and applicaMon of steam to product InstallaMon and use of steam in bread and roll ovens Comments & QuesMons? Thank you! Mike Day mikeday@banner-­‐day.com info@banner-­‐day.com W (989) 755-­‐0584 www.banner-­‐day.com 7