Convert cubic inches to cubic feet: Cubic inches 1728 (12 x 12 x12 = 1728)

Transcription

1 Interior Volume of the Kiln: Sprung or Roman Arch: 12.5 CF = W x L x ( H Side wall + 2/3 of the arch rise) 37.5 Test kiln=? 31.5 Convert cubic inches to cubic feet: Cubic inches 1728 (12 x 12 x12 = 1728) 36

2 Interior volume of the kiln: Catenary arch : CF = L x arch area (4/3 H x ½ base width ) Convert cubic inches to cubic feet: Cubic inches 1728 (12 x 12 x12 = 1728)

3 Heat Input Calculations: Compare and review the following authors: 1. Lou. 2. Olsen. 3. Ward. 4. Dedell

4 Heat input calculations Nils Lou -page 40 Where: L x Ta x Pa=Q L = Load in pounds (1500lbs cubic foot kiln) Ta= Temp rise/hour in degree F (300 ) Pa= Efficiency Factor ( 80% = 1.2 ) Q = Btus Required 1500 x 300 x 1.2 = Assuming the kiln is insulated sufficiently Load includes all hard bricks, bag walls, shelves, post, etc. One 8lb Brick will take?? Btus???????? Cubic foot of gas/ hour / brick

5 Nils Lou Page cubic foot kiln requires 540,000 btus Exit flue requirement: 1 sq inch of exit flue / 25,000 to 30,000 btus of input. 540,000 30,000 = 18 sq inches so 4.5 x 5= 22.5 half brick flue?? More common is 9 x 9 flue 81sq inches 81x30,000= 2,430,000 btus!

6 Olsen Page 192 IFB kilns natural gas: cf of gas /per 1 cf of kiln lets say 10,000 btus per cf volume Hard brick kilns 16,000 btus per cf volume

7 Olsen Page Sq inches or Inlet ports equal to Sq inches exit port?? Burner ports Exit ports 4.5 x 5= 22.5 x 2= 45 sq inches 9 x 5 = 45? 4.5 x 5= 22.5 x 6= 135sq inches 9x9=81sq inches?

8 Ward burner systems Construciton Cone 06 btu/h Per cubic ft - Cone 6 btu/h Per cubic ft Cone 10 Btu/h Per cubic ft 9 hard brick 12,000-17,000 14,000-18,500 16,000-20,000 9 ifb 6,000-10,000 8,000-13,000 10,000, 16,000 6 fiber 4,000-6,000 6,000-8,000 7,000-10,000 The lowest figure will produce firings in the hour range. The highest figure in each range produces a 6-7 hour firing.

9 Dedell page 5 and 6 Brick Combinations Wall construction Wall construction Cone 10 Cone 10 Hot face (inside) Cold face (outside) Cold face (outside) Hot Face (inside) 9 HFB degrees F 44,600 btu/hour/cu ft 4.5 HFB 4.5 K degrees F 14,000 btu/hour/cu ft 4.5 G K degrees F 10,300 btu/hour/cu ft 9 inswool degrees F 5,800 btu/hour/cu ft

10 OUR KILN: -T.I.V. :30 CU FT -16,000 BTU / CU FT

11 OUR KILN: -T.I.V. :30 CU FT T.I.V. :30 CU FT -16,000 BTU / CU FT 16,000 * 30 = Energy needed- 480,000 BTU / Hour CU FT of N.G. / Hour??????

12 OUR KILN: -T.I.V. :30 CU FT T.I.V. :30 CU FT -16,000 BTU / CU FT 16,000 * 30 = Energy needed- 480,000 BTU / Hour Natural Gas = 1,000 BTU / CU FT 480,000 1,000 =

13 OUR KILN: -T.I.V. :30 CU FT T.I.V. :30 CU FT -16,000 BTU / CU FT Natural Gas = 1,000 BTU / CU FT 480,000 1,000 = 480 CU FT of N.G. / $ 1.30/ccf ( hundred cubic feet ) 480 = 4.80 ccf ,000 * 30 = Energy needed- 480,000 BTU / Hour

14 OUR KILN: -T.I.V. :30 CU FT T.I.V. :30 CU FT -16,000 BTU / CU FT 16,000 * 30 = Energy needed- 480,000 BTU / Hour Natural Gas = 1,000 BTU / CU FT 480,000 1,000 = 480 CU FT of N.G. / $ 1.30/ccf 4.8 * 1.30=$ 6.24/ Hour at full blast

15 OUR KILN: -T.I.V. :30 CU FT -16,000 BTU / CU FT T.I.V. :30 CU FT Energy needed- 16,000 * 30 = 480,000 BTU / Hour Natural Gas = 1,000 BTU / CU FT 480,000 1,000 = 480 CU FT of N.G. / $ 1.30/ccf = $ 6.24/ Hour at full Blast 12 hour firing to cone 10 : 6 full 6 half 9 hours *6.24 = $56.16 / firing

16 Propane: btu / cu ft is good for T.I.V =30 * 16,000btu / cu ft = 480,000 btu / hour 80, = 192 cu ft 480,000 btu/gallon 92,000= 5.22 gallons / 2.00/gallon *9hours = $ 93.96

17 For next week, Clean-up your drawings: -Ideas -Measurements -Etc Also: -T.I.V. -Btu s required -Cubic feet of gas required / hour - cost per hours to fire

18 Volume to insulation ratio Cube interior ft Inside volume Area of Wall Insulation Volume to Wall Insulation ratio 1 x 1 x 1 1cf 6 sq ft 1:6 3 x 3 x 3 27cf 54 sq ft 1:2 10 x 10 x cf 600 sq ft 1: 0.6

19 Olsen Chimney height (natural draft kilns) 3 feet of chimney for every foot of downward pull (+) one foot of chimney for 3 feet of horizontal pull

20 Bottom line- chimney height Power burner- exhaust over any possible breathing area. Venturi burners- depending on your gas pressure, a rule of thumb is to double the height of you kiln???. Make chimney adjustable Wood kiln- Olsen's guide will draft

21 Gas company 1. Give them Btu s and cubic ft required per hour. 2. Ask what is the available gas pressure. 3. Ask size pipe is required form meter to burners ( what the pressure drop?). Find burners on Wards sheet.. Lets say I need 600,000 btus per hour w/ 2 power burners = 300,000 btu s/ h for each burner. Lets say I have - 11 wc propane Could I use 2 venturi burners with this pressure? What pressure is required to do so?

22 Gas flow equation do : 11 wc and 1psi LP Q=1326 A H/G Q= Discharge in cubic feet per hour A= Area of orifice in square inches H= Pressure in inches of water column G= Specific Gravity of Natural Gas (NG= 0.65) (LP = 1.50)

23 Alfred Steel frames: 9 thick brick wall construction frame can be built congruently with brick construction 4.5 brick wall with board Hinged fiber doors frame and shell is built first. - Hinges are made in our machine shop - Frame is fabricated on welding table - Forklift is used to hold door in place while hinges are welded to kiln frame.

24 Steel Fames (Required for your drawings)

25 Alfred steel kiln frames are built with: Mild Steel- 2 x 2 x 1/4 angle iron $45/20 $55/20 3 x 3 x ¼ angle iron $55/20 4 x ¼ flat stock Steel prices fluctuate We buy full pieces from I.D. Booth (Elmira NY) Bradley Supply Hornell NY - cut to length

26 2600 ceramic fiber blanket 1 thick $.50 sq ft. box $100 8lb density- 1 thick X24 wide X 300 long

27 Inspirator burner ( Venturi / Atmospheric)

28 Image form: Hal Frenzel

29 Inspirator/natural draft High gas pressure No moving parts Quite Btu rating dependent on gas volume Orifice size some what fussy Reduction is no problem Limited turn down ratio Cheaper in initial cost Relies on chimney for draft

30 Aspirator Burner (Forced Air)

31 Image form: Hal Frenzel

32 Aspirator/Forced air Low gas pressure Dependent on electricity Btu rating generally determined by the blower Orifice size not that critical May oxidize better May not have wide turn down ratio More versatile Pressurizes kiln No need for tall chimney

33 Premix Burners 34

34 The Burner or Flame Holder Shapes the Flame Generic Flame Types 35

35 Chemical Potential Energy Combustion Chemistry Relevant Reaction Energies and Times (10,000 x's longer to mix then react) Key Ideas - Energies Initial energy of reactants Activation energy Final energy of products Net change in chemical potential energy same as heat released Key Ideas Times Mixing time (10-2 seconds) Ignition time (10-3 seconds) Reaction time (10-6 seconds) Time, Reaction Progress Note: Time axis is NOT to scale

36 38

37 Flame Holder (Burner) Functions Shape/Direct the Flame. Balance Mixture Speed vs. Flame Speed. Stay Within the Flammability Limits. May also mix fuel/oxidant. Gas Air 39

38 Nozzle Mix Burner (generic)

39 In our drawings: Due Oct 7 th Wed Cover sheet- what type of kiln, what your expectations are for the kiln. Top, side, and front view of kiln Foundation (Blocks), Floors, Walls, Chimney and Arch materials/brick count and cost Steel frame drawing, material list and cost Cubic feet of interior space Btu s required to heat kiln to your temp. Cubic feet of gas required to meet temp. Estimated cost/ firing Total cost of project -including kiln furniture ( posts and shelves)

40 Measuring temperature

41 Thermocouples A thermocouple is a device consisting of two different conductors (usually metal alloys) that produce a voltage Any junction of dissimilar metals will produce an electric potential Type K chromel & alumell Type S (+) 90% platinum 10% rhodium (-)100% platinum Voltage temperature relationship Cold junction compensation T.C. extension wire

42

43

44

45 Reading Cones 022,018,010,06, 0,6,7,8,9,10 Cooler Hotter 0 cooler hotter

46 Combustion Air 79% Nitrogen 21% Oxygen 3.76 Nitrogen 1 Oxygen Oxidation / Neutral Atmosphere for Natural Gas = 10:1 CH4 + 2O2 + (8N2) -} CO2 + 2H2O + (8N2) Extreme Reduction Atmosphere for Natural Gas = 8:1 5CH4 + 8O2 + (32N2) -} CO2 + 4CO + 10H2O + (32N2)

47 Air as Oxidant C 1 C 1 O 1 O 2 H 1 H 2 H 3 H 4 H 1 H 2 O 3 O 1 O 2 O 3 O 4 IGNITION H 3 H 4 O 4 N 1 N 2 N 3 N 4 N 1 N 2 N 3 N 4 N 5 N 6 N 7 N 8 N 9 N 10 N 11 N 12 N 13 N 14 N 15 N 16 N 5 N 6 N 7 N 8 N 9 N 10 N 11 N 12 N 13 N 14 N 15 N 16 Sept The North American Manufacturing Company All rights reserved. 49

48 Air / Fuel Ratio & XS Air Natural Gas 1000 BTU / cubic ft. Air (@ 60 O F) 100 BTU / cubic ft. If you have this volume of natural gas to burn, this volume of air is required to burn all the fuel (10:1ratio) :1 - Stoichiometric Ideal - 0% excess air 50

49 Reduction firing? Reduction is the incomplete combustion of fuel, caused by a shortage of oxygen, which produces carbon monoxide. At high temperatures, carbon monoxide gas will steal loosely bonded oxygen from other materials, mainly iron and copper. This changes the molecular form of the material and produces color changes. Extreme Reduction Atmosphere for Natural Gas = 8:1 5CH4 + 8O2 + (32N2) -} CO2 + 4CO + 10H2O + (32N2) 8-7: 1 -- good reduction

50 Reduction atmosphere iron give celadon glazes: greens, blues, olive, or grey green Small amounts of copper in the appropriate base (Tin) produces copper reds Oxidation atmosphere iron generally produces: -tan, brown, or rust colors Copper produces greens Excess copper produces black.

51 Efficiency

52 1 opening 1.5 x 8 (96 ) = 144 sq. $tingers $ $ $ Infiltration Copyright by The North American Manufacturing Company All Rights Reserved

53 Stacking and Furniture

54 Recuperators Your biggest heat loss is out the chimney Recuperators transfer heat from outgoing gas to incoming combustion air without allowing streams to mix. The Streams are separated by a heat conducting wall. Three types are generally used: cross-flow, parallel-flow, and counter flow

55 Flue Gas Temp Combustion Air Temp F % Fuel Saved

56 Ways to improve efficiency

57 Ways to improve efficiency Faster firing cycles No candling wet work Omit reduction firing Oxygen sensor :1 Improving insulation Less thermal mass- lighter furniture Adding a recuperatorpreheating combustion air Monitoring temp. pyrometer Lower glaze temp Lower temp clays Single firing Use alterative fuels