Steam Utilization Report Outline
Example 2
I. Abstract
A. Recover energy from a pulp mill steam purge using an available heat exchanger
B. High-level methods
1. Double-pipe heat exchanger run in counter and co-current configurations at flow rates between 6 and 22 GPH
2. Thermocouples used to measure temperature at each inlet and outlet
C. Report on deliverables
1. Report on efficiency of prototype system with evidence (describe how this was assessed)
2. Report on scaled-up design configuration, dimensions [L m] and [d m], and flow rate [F GPH]
3. Estimate annual savings of [$S/yr] and state recommendation WRT implementation
II. Background
A. System characteristics and operating conditions
1. 40 lb/hr steam at 1 atm ~100 degrees C
B. Basics of heat exchanger calculations
1. Sensible heat + latent heat
2. Define equation and the variables mass flow rate, heat capacity at constant pressure, and difference in temperature
3. Efficiency = heat to steam/heat from water
C. Discuss overall heat exchanger coefficient
1. Define equation and the variables including surface area and log mean temperature
III. Materials and Methods (cite SOP in this section)
A. Apparatus for heat exchanger
1. Used prototype double-pipe heat exchanger configured for counter-current and co-current flow
i. Show schematic of apparatus (e.g., pressure cooker, pressure gauge, heat exchanger, rotameter, condensate trap, condensate, cold water source, locations of thermocouples) with all components labeled and concise descriptive caption
ii. Describe in text and refer to schematic
2. Used flow rates of 6, 12, and 22 GPH for each configuration
3. Measured inlet and outlet temperatures every two min over 10 min and calculated a representative average value
4. Measured condensate volume produced over a period of 10 min to estimate steam mass flow rate
B. Calibration of rotameter
1. Checked the flow rates at rotameter settings of 6, 12 and 22 GPH by measuring the volume of water collected over a period of 10 min
2. Ran three replicates
IV. Results and Discussion
A. Prototype capability compared to existing preheaters
1. Cite preheater specs, compare to efficiency (heat gained by water/heat lost by steam)
2. Report on heat transfer rate as a function of flow rate and configuration
i. Graph of water flow rate (GPH) vs. heat transfer rate (kW) for both water and steam for each configuration (show average of three replicates with error bars representing 90% confidence intervals)
ii. Observed trend with flow rate for each configuration
3. Report on efficiency as a function of flow rate and configuration
i. Discussion of % efficiency as heat transfer rate of the water divided by the heat transfer rate of the steam (X100)
ii. Graph of water flow rate (GPH) vs. efficiency (%) (show average of three replicates with error bars representing 90% confidence intervals)
iii. Counter-current flow is more efficient than co-current flow
B. Consideration of error
1. Rotameter error was significant, estimated to be 0.5 GPH
2. Other error due to lack of insulation on the tubing would be smaller than this
3. Explain effects of error on deliverables
4. Overall heat transfer coefficients
i. Higher for counter-current flow vs. co-current flow, so former preferred
ii. Ballpark comparison of values to literature on published system (cite source)
C. Scaled-up design
1. Strategy to calculate a scale-up factor based on the ratio of the project specified steam mass flow rate of 40 lb/hr and the steam mass flow rate in the prototype
2. Use this to calculate a scaled-up area [A m2], choose reasonable diameter [d m], and calculate required length [L m]
3. Consider safety factor of 1.5X and state assumptions, including constant heat exchanger coefficient and log mean temperature difference
4. Scaled-up system flow rate of [F GPH]
D. Conclusions and Recommendations
1. Estimate of net annual savings
i. Estimate heat transfer rate for scaled-up system [R kW]
ii. Assume $0.07/kWhr
iii. Report [$S/yr] of net savings and criteria for recommending scaling up
2. Recommend/do not recommend installing heat exchangers
V. Acknowledgements
A. Jane Doe and John Smith for their assistance in collecting and analyzing the data
B. Shujie Li for useful discussions
C. Corey Downs for feedback on technical report writing
VI. Appendices
A. Sample calculations
1. Heat transfer rate for water
2. Heat transfer rate for steam
3. Overall heat transfer coefficient
4. Scaled-up system calculations
5. Estimate of savings per year
B. Tabulated raw data including for rotameter calibration
C. Supporting figures
a. Comparisons of system configurations
b. Error analysis estimates and calcs