

Steam Generators
and Waste Heat Boilers
For Process and Plant Engineers
Steam Generators
and Waste Heat Boilers
For Process and Plant Engineers
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Steam Generators
and Waste Heat Boilers
For Process and Plant Engineers
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Version Date: 20140331
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Contents
Preface........................................................................................................................................... |
xiii |
Author......................................................................................................................................... |
xxxi |
1. Combustion Calculations ..................................................................................................... |
1 |
Introduction.............................................................................................................................. |
1 |
Moisture in Air......................................................................................................................... |
1 |
Combustion Calculations ....................................................................................................... |
2 |
Excess Air from Flue Gas Analysis .................................................................................. |
8 |
Simplified Combustion Calculations ............................................................................. |
10 |
Estimation of Heating Values............................................................................................... |
12 |
Burner Selection..................................................................................................................... |
13 |
Combustion Temperatures ................................................................................................... |
14 |
Simplified Procedure for Estimating Combustion Temperatures.................................. |
15 |
Effect of FGR on Combustion Temperature.................................................................. |
15 |
Relating FGR and Oxygen in Windbox ......................................................................... |
16 |
Gas Turbine Exhaust Combustion Calculations ............................................................... |
17 |
Relating Oxygen and Energy Input in Turbine Exhaust Gases ................................. |
17 |
Evaluating Fuel Quantity Required to Raise Turbine Exhaust Gas Temperature ...... |
19 |
Firing Temperature versus Oxygen, Burner Duty, and Water Vapor........................ |
21 |
Boiler Efficiency ..................................................................................................................... |
21 |
Heat Loss Method............................................................................................................. |
22 |
Simplified Formulae for Boiler Efficiency ..................................................................... |
23 |
Simplified Procedure for Obtaining Major Boiler Parameters................................... |
26 |
Excess Air versus Efficiency............................................................................................ |
26 |
Firing Fuels with Low Heating Values............................................................................... |
27 |
Firing of Multiple Fuels......................................................................................................... |
29 |
Emission Conversion Calculations: Steam Generators .................................................... |
29 |
Converting ppmvd of NOx to mg/Nm3 .............................................................................. |
32 |
Converting Turbine Exhaust Emissions ............................................................................. |
34 |
Low-Temperature Corrosion in Boilers .............................................................................. |
35 |
Condensation of Acid Vapors in Low-Temperature Heat Sinks ..................................... |
38 |
Acid Dew Point Temperature Tdp.................................................................................... |
38 |
References ............................................................................................................................... |
40 |
2. Steam Generator Furnace Design...................................................................................... |
41 |
Advantages of Water-Cooled Furnaces .............................................................................. |
43 |
Ring Header Design ......................................................................................................... |
44 |
Heat Release Rates ................................................................................................................. |
46 |
Steam Pressure .................................................................................................................. |
47 |
Circulation Systems .......................................................................................................... |
52 |
Furnace Exit Gas Temperature Evaluation......................................................................... |
53 |
Empirical Formula for Furnace Duty Estimation ............................................................. |
57 |
vii
viii |
Contents |
Furnace Duty with Combination Firing............................................................................. |
60 |
Distribution of Heat Flux around Tubes and Fins ............................................................ |
61 |
Distribution of Radiation to Tube Banks............................................................................ |
61 |
Relating Heat Flux from Furnace to inside Tubes............................................................. |
64 |
External Radiation to Heat Transfer Surfaces at Furnace Exit ........................................ |
65 |
Direct Radiation to Superheater at Part Load............................................................... |
66 |
Terms Frequently Used in Furnace Performance.............................................................. |
67 |
Estimating Boiling Heat Transfer Coefficient.................................................................... |
67 |
Estimating Fin Tip Temperature.......................................................................................... |
68 |
Boiling Process ....................................................................................................................... |
69 |
Boiler Circulation................................................................................................................... |
70 |
Thom’s Method for Estimating Losses ............................................................................... |
75 |
Circulation Calculations ....................................................................................................... |
77 |
Circulation Flow versus Load ......................................................................................... |
81 |
Flow Stratification in Horizontal Tubes.............................................................................. |
82 |
Correlations for CHF (Critical Heat Flux) and Allowable Steam Quality..................... |
82 |
Circulation Problems............................................................................................................. |
85 |
Guidelines for Good Circulation System Design.............................................................. |
85 |
References ............................................................................................................................... |
86 |
3. Steam Generators.................................................................................................................. |
87 |
Introduction............................................................................................................................ |
87 |
Large Package Boilers............................................................................................................ |
87 |
Water-Cooled Furnaces......................................................................................................... |
90 |
Major Changes in Boiler Design.......................................................................................... |
90 |
Absence of Air Heater........................................................................................................... |
90 |
Emissions Affect Steam Generator Designs ...................................................................... |
92 |
Custom-Designed Boilers ..................................................................................................... |
97 |
Novel Ideas ............................................................................................................................. |
97 |
O-Type Package Boiler...................................................................................................... |
98 |
Dual-Pressure Design....................................................................................................... |
99 |
Small Changes, Big Benefits ............................................................................................ |
99 |
Boiler Classification ............................................................................................................. |
103 |
Improving Boiler Efficiency ............................................................................................... |
108 |
Adding Condensate Heater to Improve Boiler Plant Efficiency............................... |
109 |
Understanding Boiler Performance.............................................................................. |
111 |
Why Economizer Does Not Steam in Steam Generators .......................................... |
112 |
Understanding Boiler Surface Areas............................................................................ |
113 |
Steam Generators for Oil Sands Application................................................................... |
115 |
Superheaters ......................................................................................................................... |
118 |
Radiant versus Convective Superheaters .................................................................... |
121 |
How Emissions Impact Radiant and Convective Superheaters............................... |
124 |
Arrangement of Superheaters ....................................................................................... |
124 |
Steam Temperature Control .......................................................................................... |
125 |
Steam Generators with Import and Export Steam.......................................................... |
129 |
Flow in Parallel Paths.......................................................................................................... |
129 |
Steam Inlet and Exit Nozzle Location............................................................................... |
130 |
Off-Design Performance of Superheater........................................................................... |
131 |
Contents |
ix |
Case Study of a Superheater with Tube Failure Problems............................................. |
135 |
Problem at Low Loads with Inverted-Loop Superheaters ........................................ |
137 |
Steam Generator Design and Performance...................................................................... |
138 |
Data Required for Performing Steam Generator Analysis ....................................... |
139 |
Checking Boiler Performance ....................................................................................... |
142 |
Evaluating Part Load Performance .............................................................................. |
146 |
Performance without Economizer..................................................................................... |
149 |
Tube Wall Temperature Estimation at Economizer Inlet............................................... |
149 |
Methods to Minimize Low-Temperature Corrosion Problems..................................... |
151 |
Precautions to Minimize Corrosion in Operation .......................................................... |
154 |
Water Chemistry, Carryover, Steam Purity ..................................................................... |
155 |
Fire Tube Boilers................................................................................................................... |
157 |
Boiler Horse Power ......................................................................................................... |
160 |
Sizing and Performance Calculations.......................................................................... |
160 |
References ............................................................................................................................. |
163 |
4. Waste Heat Boilers.............................................................................................................. |
165 |
Introduction.......................................................................................................................... |
165 |
Gas Inlet Temperature and Analysis............................................................................ |
168 |
Flue Gas Composition and Gas Pressure .................................................................... |
170 |
Water Tube versus Fire Tube Boilers ............................................................................ |
173 |
Circulation Systems ........................................................................................................ |
174 |
Heat Recovery in Sulfur Plants..................................................................................... |
178 |
Heat Recovery in Sulfuric Acid Plant .......................................................................... |
181 |
Heat Recovery in Hydrogen Plants .............................................................................. |
182 |
Combining Solar Energy with Heat Recovery Systems ............................................ |
184 |
Gas Turbine HRSGs ........................................................................................................ |
184 |
Natural, Forced Circulation, Once-Through Designs, and Special Applications ..... |
188 |
Natural versus Forced Circulation HRSGs ................................................................. |
191 |
Emission Control in HRSGs .......................................................................................... |
194 |
Flow-Accelerated Corrosion .......................................................................................... |
195 |
Water Tube Waste Heat Boilers: Sizing and Performance.............................................. |
197 |
Optimizing Pinch and Approach Points in HRSGs .................................................. |
197 |
HRSG Performance and Evaluating Field Data.......................................................... |
199 |
Efficiency of Waste Heat Boiler, HRSG ........................................................................ |
204 |
Advantages of Supplementary Firing in HRSGs................................................... |
204 |
HRSG and Steam Generator Performance .................................................................. |
205 |
Optimum Utilization of Boilers .................................................................................... |
205 |
Combined Cycle Plants and Fired HRSGs .................................................................. |
206 |
HRSGs with Split Superheaters .................................................................................... |
208 |
Performance with and without Export Steam ............................................................ |
208 |
Providing Margins on Heating Surfaces..................................................................... |
217 |
Cement Plant Waste Heat Recovery ............................................................................. |
217 |
Kalina Cycle.......................................................................................................................... |
223 |
Advantages of Kalina Cycle .......................................................................................... |
224 |
Fluid Heaters and Film Temperature................................................................................ |
227 |
Design of Fire Tube Boilers................................................................................................. |
230 |
Boiling Heat Transfer Coefficient ho............................................................................. |
231 |
x |
Contents |
Effect of Scale Formation........................................................................................... |
234 |
Estimation of Loss in Performance Due to Fouling .............................................. |
236 |
Tube Wall Thickness Calculations........................................................................... |
236 |
Off-Design Performance with Addition of Economizer............................................ |
238 |
Simulation of Fire Tube Boiler Performance ............................................................... |
239 |
Effect of Gas Analysis on Performance........................................................................ |
241 |
Critical Heat Flux qc........................................................................................................ |
242 |
Effect of Tube Size on Boiler Design ............................................................................ |
244 |
Estimating Tube Bundle Diameter ............................................................................... |
245 |
Simplified Approach to Evaluating Performance of Fire Tube Boilers ................... |
245 |
Estimating Tube Sheet Thickness................................................................................. |
248 |
Estimating Tube Sheet Temperature with Refractory and Ferrules........................ |
248 |
Calculation of Tube Sheet Temperature without Refractory on Tube Sheet .......... |
249 |
Air Heaters............................................................................................................................ |
250 |
Heat Pipes ............................................................................................................................. |
251 |
Design of Tubular Air Heaters........................................................................................... |
252 |
Heat Transfer Inside and Outside Tubes ..................................................................... |
253 |
Part Load Performance................................................................................................... |
257 |
Specifying Waste Heat Boilers ...................................................................................... |
258 |
Waste Heat Boiler Data (Thermal Design) ....................................................................... |
259 |
References ............................................................................................................................. |
261 |
5. HRSG Simulation............................................................................................................... |
263 |
Introduction.......................................................................................................................... |
263 |
What Is HRSG Simulation? ................................................................................................ |
263 |
Applications of HRSG Simulation..................................................................................... |
265 |
Understanding Pinch and Approach Points.................................................................... |
266 |
Estimating Steam Generation and Gas–Steam Temperature Profiles.......................... |
267 |
Why Cannot We Arbitrarily Select the Pinch and Approach Points?.......................... |
270 |
Why Should Pinch and Approach Points Be Selected in Unfired Mode? ................... |
271 |
Simulation of HRSG Evaporator........................................................................................ |
272 |
Supplementary Firing ......................................................................................................... |
273 |
Off-Design Performance Evaluation ................................................................................. |
274 |
How Accurate Is Simulation?............................................................................................. |
279 |
Steaming in Economizer..................................................................................................... |
281 |
Methods to Minimize Steaming in Economizer ........................................................ |
283 |
Field Data Evaluation .......................................................................................................... |
284 |
Singleor Multiple-Pressure HRSG .................................................................................. |
286 |
Split Superheater Design..................................................................................................... |
295 |
Fresh Air Firing.................................................................................................................... |
299 |
Efficiency of HRSG .............................................................................................................. |
300 |
Cogeneration Plant Application......................................................................................... |
301 |
Optimizing HRSG Arrangement ...................................................................................... |
303 |
Application of Simulation to Understand the Effect of Ambient Conditions............. |
305 |
Applying Margins on Exhaust Gas Flow and Temperature ......................................... |
306 |
Conclusion ............................................................................................................................ |
308 |
References ............................................................................................................................. |
308 |
Contents |
xi |
6. Miscellaneous Boiler Calculations ................................................................................. |
309 |
Condensing Economizers................................................................................................... |
309 |
Water Dew Point of Flue Gases..................................................................................... |
310 |
Energy Recoverable through Condensation ............................................................... |
311 |
Condensation Heat Transfer Calculations................................................................... |
312 |
Condensation over Finned Tubes ................................................................................. |
315 |
Wall Temperature of Uninsulated Duct, Stack................................................................ |
317 |
Insulation Calculations....................................................................................................... |
320 |
Hot Casing Design.......................................................................................................... |
322 |
Drum Coil Heater: Bath Heater Sizing ............................................................................. |
323 |
Checking Heat Transfer Equipment for Noise and Vibration Problems ..................... |
327 |
Determining Natural Frequency of Vibration of Tubes ............................................ |
327 |
Acoustic Frequency fa ..................................................................................................... |
328 |
Vortex Shedding Frequency fe....................................................................................... |
328 |
Damping Criterion.......................................................................................................... |
331 |
Fluid Elastic Instability .................................................................................................. |
332 |
Steam Drum Calculations .................................................................................................. |
333 |
Steam Velocity in Drum................................................................................................. |
333 |
Blowdown Calculations ................................................................................................. |
335 |
Drum Holdup Calculations........................................................................................... |
339 |
Estimating Flow in Blowdown Lines................................................................................ |
340 |
Theory............................................................................................................................... |
340 |
Flow Instability in Two-Phase Circuits ............................................................................ |
343 |
Transient Calculations......................................................................................................... |
346 |
Analysis of an Evaporator.............................................................................................. |
348 |
Drum-Level Fluctuations............................................................................................... |
350 |
Fan Calculations................................................................................................................... |
351 |
Density of Flue Gas, Air................................................................................................. |
351 |
Pressure Drop in Ducts.................................................................................................. |
352 |
Fan Selection.................................................................................................................... |
353 |
Why Should the Fan Capacity Be Reviewed at the Lowest Density |
|
Condition? ................................................................................................................ |
354 |
Head Developed by Fan................................................................................................. |
355 |
Fan Power Consumption................................................................................................ |
355 |
Estimating Stack Effect .................................................................................................. |
355 |
References ............................................................................................................................. |
356 |
Appendix A: Boiler Design and Performance Calculations ............................................. |
357 |
Appendix B: Tube-Side Heat Transfer Coefficients and Pressure Drop ........................ |
377 |
Appendix C: Heat Transfer Coefficients Outside Plain Tubes......................................... |
393 |
Appendix D: Nonluminous Heat Transfer Calculations................................................... |
407 |
Appendix E: Calculations with Finned Tubes..................................................................... |
413 |
Appendix F: Properties of Gases ............................................................................................ |
447 |
Appendix G: Quiz on Boilers and HRSGs with Answers ................................................ |
477 |
xii |
Contents |
Conversion Factors |
.....................................................................................................................485 |
Glossary ....................................................................................................................................... |
491 |
Nomenclature ............................................................................................................................. |
493 |