Helicoil and Shell-Tube Heat Exchanger Abdullah AlThomairi, Ahmed Sajjad, and Faris AlShuaibi October 25, 2014 Submitted to: NORTHEASTERN UNIVERSITY Department of Chemical Engineering CHME 3313 Transport 2 Laboratory Dr. Roy
Table of Contents Table of Contents... 2 Table of Figures.. 3 Table of Tables... 3 Executive Summary... 4 1. Introduction 5 2. Background 5 3. Experimental Method.. 6 4. Results and Analysis... 7 5. Conclusions.. 9 6. Recommendations.. 9 7. References.. 10 2
8. Appendix A: Operating Procedure Safety Analysis 10 11 14 Table of Figures Figure 1: Flow sheet diagram of the experiment 7 Table of Tables Table 1 : The efficiencies concerning the TS hot and SS cold for cocurrent flow 8 Table 2 : The efficiencies concerning the TS cold and SS hot for co-current flow 8 Table 3 : The efficiencies concerning the TS hot and SS cold for countercurrent flow 8 Table 4 : The efficiencies concerning the TS cold and SS hot for countercurrent flow 8 3
Executive Summary The forehand task appointed to the research group is to improve the production process of dye being produced in the company pilot plant. We approached this problem is a methodical fashion; aiming to understand the equipment we re working with, in great depth. The Helicoil and Shell & Tube Heat Exchanger models the equipment used for production of the dye. This consists of a Helicoil heat exchanger integrated with a Shell & Tube heat exchanger, which allows for two configurations each for the tube side and the shell side. The variables we could vary include configuration of the tubes, direction of flow, flow rate and temperature of stream. This experiment performed collected and tabulated the temperature & pressure at various points of the heat exchanger. Data was recorded for the four possible configurations of the Shell & Tube side with the respective direction of flow (co-current or counter-current). The flow rate and temperature of the exit stream of water was also tabulated and this energy (fusion-vaporization) was calculated and compared with the energy required to raise the temperature of our fluid. The heat transfer efficiency was calculated using this relationship as a fundamental. Following on the primary objective of this experiment, to maintain a steady flow of temperature sensitive dye at 70 F & a flow rate below 8 GPM, we compared our calculated efficiencies at relative configurations & flow rates. The experiment concluded that a flow rate of 8 GPM & counter-current configuration will yield the most efficient conversion rate, amounting to minimal loss of heat, and therefore increased efficiency in production & lower costs. While the results of this experiment identified a quantitative value for the flow rate and a specific configuration as most suited for maximum efficiency in production of our dye, it is recommended that further experiments be performed investigating these parameters with fluids of different constituency. 4
Introduction The environmentally friendly dye being produced in the pilot plant by our company is periodically failing quality inspections, which leads to loss of product and rising operational costs. Insufficient reactor temperature control seems to be a plausible cause for the denaturation of the enzyme being produced, which must be maintained at a temperature below 70 F and a flow rate below 10.0 GPM. Above this temperature, denaturation of the enzymatic additive in the dye produces a toxic white product, which is potentially dangerous and costly to dispose of. This experiment aims to identify the properties of the Shell and Tube Heat Exchanger to keep the temperature of the dye stable and below 70 F. The end goal of this experiment is to maintain a steady supply of industrial grade dye to decrease overall costs per volume of dye, thereby increasing profits. This challenge represents problem related to the field of chemical engineering, different subjects of chemical engineering are applied in this experiment. As chemical engineers, different information gathered from the following courses, transport process of fluid mechanics, transport process heat and mass transfer, and thermodynamics will be used to solve this problem. We believe by working with this challenge will be able to learn the effect of the heat loss from the materials used in the system, and how does changing the mass transfer and flow rates affect the efficiency of the system used and the effect on the final temperature of the dye. Background In order to achieve the end goal of this experiment, to maintain the dye under the temperature required, and to be able to operate the system under 10 GPM, different heat coefficients of varying configurations of the system will be calculated. Using these various configurations of the Shell side and Tube side, and changing the direction of flow and the inlet between cold and hot water, the goal of this experiment will be met. Tube 1 will be calibrated such that the tube-side will have hot water, the shell side will have cold water, and the flow is co-current. The cold water flow rate and hot water flow rate will be set at 8 GPM and as soon as equilibrium is achieved, data including the flow rate, pressures and temperatures will be tabulated into LabView. The hot water flow rate will be tested at 8 GPM, 12 GPM & 15 GPM while the cold water flow rate will be set at almost 6 GPM. The following equation for heat transfer between bodies, which is dependent on the mass, specific heat capacity and the difference between the initial and final operating temperatures. q = m C p (T o - T i ) Equation 1 5
To account for the various variables affecting heat exchange, determining the efficiency of this heat exchanger will also be carried out. This is the percentage ratio of the heat transferred from the hot water to the cold water. Once the energy balance is performed and the values for the overall heat transfer coefficient, efficiency and heat transfer rate are found, then they can be used to calibrate our equipment to produce a uniform flow of quality dye below 70 F. Experimental Method In this experiment different configurations of the helicoil have been tested at different flow rates to study which one is the most efficient and suitable for the objectives. Before starting the experiment, the system must be set up fully, and the temperature thermocouples and gauge pressure measurement tools are ensured to be working the properly. Then the operating procedure has been started. The first configuration (Tube-Hot and Shell-Cold in co-current) at flow rates of 8 and 15 GPM has been operated, initially. As soon as the steam is supplied to the system, the computer will start taking measurements of the system. When the system reached steady state, a condensate of the system was collected. The condensate weight was measured, in order to calculate the flow rate of the condensate. This along with the data collected using LabView enabled us to determine the efficiency and heat loss of our system. The second configuration was exactly the same in a counter-current flow, keeping the Tube-Hot and Shell- Cold. The third and fourth configurations were similar, but with changing the tube side hot to tube side cold. All the data of these runs were tested to look for the best match for the needed system, keeping in mind the efficiency of all of them. 6
Figure 1. Flow sheet diagram of the experiment Results and Analysis Four configurations were tested in this experiment. Two co-current configurations, one where the tube side is hot and the shell side is cold. The other co-current configuration has a cold tube side and a hot shell side. The other two configurations are the same, except that they flow countercurrent to one another. The data for the temperatures was collected via Labview with the aid of several thermocouples attached to the system. For the cocurrent configurations, three flow rates of hot water were used: 8.38 (±0.165) GPM, 11.99 (±0.153) GPM, and 15.61 (±0.083) GPM. These values were obtained via calibration of the pump feed. Starting with TS (Tube Side) hot and SS (Shell Side) cold with a flowrate of 8.38 GPM for the hot water, and with a cold water flow rate of 6.65 GPM, Equation 1 was used to perform an energy balance to find how efficient our heat transfer system was. This efficiency can be obtained by dividing the energy that actually transferred over the energy that should ve transferred, ideally. Temperature difference (obtained from Labview), flow rate (obtained from calibration and LabView), and specific heat of water were taken into consideration while 7
performing this energy balance. Different configurations yielded different efficiencies of heat transfer, the tables below summarize these values obtained for all configurations that were treated similarly for getting an efficiency of heat transfer. Table 1. The efficiencies concerning the TS hot and SS cold for cocurrent flow Hot water Flowrate (GPM) Cold water flowrate (GPM) Efficiency 8.38 (±0.165) 6.43 (±0.033) 90.6% 11.99 (±0.153) 6.61 (±0.031) 81.4% 15.61 (±0.083) 6.65 (±0.0302) 66.5% Table 2. The efficiencies concerning the TS cold and SS hot for cocurrent flow Hot water Flowrate (GPM) Cold water flowrate (GPM) Efficiency 8.38 (±0.165) 6.42 (±0.0298) 94% 11.99 (±0.153) 6.45 (±0.0312) 74.7% 15.61 (±0.083) 7.35 (±0.0392) 59.7% Table 3. The efficiencies concerning the TS hot and SS cold for countercurrent flow Hot water Flowrate (GPM) Cold water flowrate (GPM) Efficiency 8.38 (±0.165) 6.40 (±0.034) 99.4% 11.99 (±0.153) 6.58 (±0.0301) 82.2% 15.61 (±0.083) 7.35 (±0.040) 52.5% Table 4. The efficiencies concerning the TS cold and SS hot for countercurrent flow Hot water Flowrate (GPM) Cold water flowrate (GPM) Efficiency 8.38 (±0.165) 64.3 (±0.033) 96.3% 11.99 (±0.153) 64.9 (±0.035) 89% 15.61 (±0.083) 66.1 (±0.0332) 71.9% 8
After a great deal of calculations, research, and energy balances, the tables above have been conducted in the hopes of properly analyzing and comparing different configurations of heat transfer. One trend that can be seen is that countercurrent flow gave a much higher efficiency than the co-current transfer of heat, meaning more heat was transferred in countercurrent configurations. Another clearer observation concerns the varying hot water flow rates, three flow rates were used to properly examine what would happen to the efficiency of the heat transfer if the flow rate was changed. The results suggest, as the tables above show, that the higher the flow rate, the more the system will lose heat to its surroundings, and the lower the efficiency will be. Ultimately, if the efficiency is low, the rate of heat transfer will also be low. Conclusions After analyzing the data, the trends and patterns of the system have been studied. From the results it was concluded that as the flow rate increases, the efficiency drops. Furthermore, it was observed that countercurrent flow gives more efficient results. Corresponding to the main objective of achieving the maximum efficiency, while keeping the dye under the given temperature of 70F, and to keep the flow rate below 10 GPM, the system should be operated at 8 GPM. The efficiency of the system will be high at this flow rate, and satisfies the limit of the flow rate given. For the best configuration, it was found that operating the system in a countercurrent flow will help to increase the efficiency of the system. The results implied a conclusion that whether the tube side was cold or hot, made no difference in the efficiency of the heat transfer. Using the information stated, the company will be able to heat the dye to the point required, under 70F with losing minimal energy to the surroundings, and will maintain the texture of the dye and its quality. Recommendations This experiment varied the 4 configurations of the helicoil and Shell & Tube heat exchanger, at flow rates below 10 GPM using water as a substitute for the dye. The bounds of the experiment, the range within which we varied our flow rates, configurations & temperatures are limited by the specific production of the dye. It is recommended that this experiment be performed again, replacing the water with the actual dye as the working fluid. This will allow us to better predict the exact conversions and efficiency rates particular to the nature of the dye. The experiment was performed in small scale, and the amount of product obtained as well as time of processing was limited. Further experiments are recommended, with longer running times. This will result in multiple batches of product dye, which can further be analyzed for consistency, as that is also an important aspect of production and quality control to be considered. In a nutshell, the recommendations for this experiment focus on replicating the experiment with conditions closer to the actual large-scale production of the dye, allowing for more precise measurements and hence greater efficiency in the production process for the pilot plant. 9
References 1. Incropera, Frank P., and David P. DeWitt. "Heat Exchangers." Fundamentals of Heat and Mass Transfer. New York: Wiley, 1990. N. pag. Print. 2. Sajjad, Ahmed, Katherine Aldrich and Cristina Ferrara. Flowsheet 1. Heat Exchangers ; Shell and Tube Laboratory: NU 2014. Print. 10
Operating Procedure Appendix A: Operating Procedure and Safety Analysis 1. Make sure all equipment and valves are shut-off and closed before starting experiment. 2. Approximately 20 minutes before running the experiment, the boiler must be turned on for the high pressure steam used in the experiment. Go on the mezzanine of the U.O. laboratory and find the large blue boiler in the far left corner. In this order, switch on/open the following: i. Main power supply located on the wall to the front, right of the boiler. i iv. Switch located on the wall behind the boiler. Control switch located in the front, top left on the boiler. Yellow handle ball valve located on the front, bottom right of the boiler. 3. Right before beginning the experiment, the valves for the large non-potable water supply tank must be opened. Go on the mezzanine of the U.O. laboratory and find the large, white non-potable water tank. Open the following valves: i. Orange ball valve located at the bottom of the tank. Large, top, yellow handle ball valve located to the right of the tank. 4. For the water supply for the hot stream to the shell and tube heat exchanger, open these valves leaving the valves before and after pump 4 last as well as the valve before the Heliflow heat exchanger. Open valves V122, V136, V137, V131. Turn on the water supply from Sump 2, V89. Have three people ready to turn on pump 4. One person should be at valve V111, one person should be at the pump switch ES 4A for pump 4, and one person should be at V107. When the person at valve V107 starts to crack open V107, he/she should tell the person at the switch ES 4A to turn on pump 4. After pump 4 is turned on, V107 should be fully open as well as V111. 5. For the water supply for the cold stream to the shell and tube heat exchanger, turn on pump #2 by hitting the start button on the pump and open valve V14 simultaneously. 6. Setting up the quick connect hoses for varying configurations on the shell and tube heat exchanger Configuration: Tube side-hot stream; Shell side-cold stream; co-current flow 11
i. Attach quick connect hose from QC on Heliflow heat exchanger (Top, left side) to QC38 on shell and tube heat exchanger (Hot supply) Attach quick connect hose from QC42 to drain (Hot return) i Attach quick connect hose from QC next to V17 to QC40 on shell and tube heat exchanger (Cold supply) iv. Attach quick connect hose from QC36 to drain (Cold return) Configuration: Tube side-hot stream; Shell side-cold stream; counter-current flow i. Attach quick connect hose from QC on Heliflow heat exchanger (Top, left side) to QC38 on shell and tube heat exchanger (Hot supply) Attach quick connect hose from QC42 to drain (Hot return) i Attach quick connect hose from QC next to V17 to QC36 on shell and tube heat exchanger (Cold supply) iv. Attach quick connect hose from QC40 to drain (Cold return) Configuration: Tube side-cold stream; Shell side-hot stream; co-current flow i. Attach quick connect hose from QC on Heliflow heat exchanger (Top, left side) to QC40 on shell and tube heat exchanger (Hot supply) Attach quick connect hose from QC36 to drain (Hot return) i Attach quick connect hose from QC next to V17 to QC38 on shell and tube heat exchanger (Cold supply) iv. Attach quick connect hose from QC42 to drain (Cold return) Configuration: Tube side-cold stream; Shell side-hot stream; counter-current flow i. Attach quick connect hose from QC on Heliflow heat exchanger (Top, left side) to QC40 on shell and tube heat exchanger (Hot supply) Attach quick connect hose from QC36 to drain (Hot return) i Attach quick connect hose from QC next to V17 to QC42 on shell and tube heat exchanger (Cold supply) iv. Attach quick connect hose from QC38 to drain (Cold return) 7. Actual experiment : A. After quick connect hoses have been set-up on heat exchanger with proper configuration, open V145 for water for the hot stream. 12
B. Slowly open large yellow handle ball valve to the left of the heat exchanger, next to the E715 label which supplies steam to heat up the water for the hot stream. C. Open valves V16, yellow handle ball valve by QC40, and yellow handle ball valve between QC38 and QC41. D. Record flow rate readings from Hoffer Flow Controller (Cold stream) and FI6 Rotameter (Hot stream) E. Turn on Omega Thermocouple Thermometer E535 and record temperature readings (Dials 1-4). F. In this experiments, run varying flow rates. Try holding one stream at a constant flow rate while varying the flow rate of the other stream and vice versa. Try different configurations to find the best heat transfer. 8. Shut down the system Shut off the steam to the Heliflow heat exchanger by closing the large yellow handle ball valve to the left of the heat exchanger, next to the E715 label. b. Three people are needed to shut down pump 4. i. Have one person at V-111, one person at the ES-4A, and one person at V-107. Follow the same procedure as turning on pump 4. c. When the person at valve V107 starts to close V107, he/she should tell the person at the switch ES 4A to turn off pump 4. After pump 4 is turned off, V107 should be fully closed as well as V111. d. Shut off the water supply V-89. Close valves V122, V136, V137, V131, and V145. Shut off the cold supply pump (pump 2) by pressing the stop button on pump 2 and closing valve V14 simultaneously. Close valves V16, yellow handle ball valve by QC40, and the yellow handle ball valve between QC38 and QC41. Go up to the mezzanine, close the valves for the large non-potable water supply tank i. Orange ball valve located at the bottom of the tank. Large, top, yellow handle ball valve located to the right of the tank. Still up on the mezzanine, switch off/close the switches/valves for the boiler in the following order: i. Yellow handle ball valve located on the front, bottom right of the boiler. Control switch located in the front, top left on the boiler. 13
i iv. Switch located on the wall behind the boiler. Main power supply located on the wall to the front, right of the boiler. Safety Analysis The Safety Analysis is a crucial component of our experiment, as this experiment consists of potentially harmful fluids, gases and parts at very hot temperatures. Rubber gloves, safety hat and protective eye wear should be worn at all times to protect against burns on the hand and eyes, and possible injury to the head. Additionally, precaution should be taken to avoid contact with the boiler, steam and any other hot parts including containers for the hot water. As another precaution, the users should wear close top shoes and the minimal bare skin should be exposed. As part of data measurement and calculation in our experiment, we use electrical equipment such as the thermometer, computer, stopwatch etc. Care should be taken not to expose these items and their electrical circuit to steam/fluids to avoid electrical damage, shock and loss of data. At the time of system startup and shutdown, it is crucial to check Appendix 1 and make sure the appropriate valves are closed and the system is depressurized before any connections are broken/ hoses are removed. 14