Experimental investigation on a flat heat pipe heat exchanger for waste heat recovery in steel industry

Transcription

1 Aville online t ScienceDirect Energy Procedi 123 (217) st Interntionl Conference on Sustinle Energy nd Resource Use in Food Chins, ICSEF 217, 19-2 April 217, Berkshire, UK Experimentl investigtion on flt het pipe het exchnger for wste het recovery in steel industry Hussm Jouhr, *, Sulimn Almhmoud, Amish Chuhn, Bertrnd Delpech, Theodor Nnnou, Svvs A. Tssou, Rocio Ller, Frncisco Lgo, Jun José Arris Brunel University London, Institute of Energy Futures, Center for Sustinle Energy Use in Food Chins, Uxridge, Middlesex UB8 3PH, UK ArcelorMittl Glol R&D Asturis, P.O. Box 9 - Avilés 334, Spin Astrct The mjority of the energy demnd in industril ppliction is primrily used for heting purposes. Recovering wste het could contriute to significnt reduction of production cost nd greenhouse gs emission. In this pper, n innovtive het recovery system ws designed, mnufctured nd tested. The Flt Het Pipe (FHP) is designed to recover the het y rdition from hot steel rods during the mnufcturing cooling process. The FHP system is composed of stinless steel het pipes linked y collector t the ottom nd shell nd tue top heder. The therml performnce of the FHP ws investigted y testing the system t two positions from the rrier of the wires conveyor. The mount of the energy recovered nd the working temperture of the FHP is lso reported. The experimentl results show tht the het trnsfer cpility of the FHP is strongly influenced y the hot source temperture. It ws oserved from the results tht the FHP is n innovtive technology for wste het recovery from industril pplictions with high efficiency. 217 The Authors. Pulished y Elsevier Ltd. Peer-review under responsiility of the scientific committee of the 1st Interntionl Conference on Sustinle Energy nd Resource Use in Food Chins. Keywords: Flt het pipe, het exchnger, Wste het recovery * Corresponding uthor. Tel.: ; fx: E-mil ddress: hussm.jouhr@runel.c.uk The Authors. Pulished y Elsevier Ltd. Peer-review under responsiility of the scientific committee of the 1st Interntionl Conference on Sustinle Energy nd Resource Use in Food Chins /j.egypro

2 33 Hussm Jouhr et l. / Energy Procedi 123 (217) Introduction The iron nd steel industry is the lrgest energy consuming production process. Energy cost represents out 3 % of the totl production cost. Recovering the het from the steel mnufcturing process is huge chllenge. Recovering the excess het from those processes could reduce the greenhouse emissions nd significntly reduce the production costs. A significnt mount of investigtions within wste het recovery hs een conducted over the pst decde, with significnce on molten slg. The mjority of innovtion hs een focused on molten slgs het recovery s discussed y Zhng et l. [1], Liu et l. [2], nd Gutiérrez-Trshorrs et l. [3]. Four wste het recovery systems hve een investigted: Air lst, Single Drum, Twins Drums, nd the spinning cup methods, typiclly these systems hve n verge efficiency of pproximtely 5%. Kşk [4] proposed n Orgnic Rnkine Cycle for power genertion using the excess het of wlking em sl rehet furnce. The system proposed ws tested with different working fluids in two working conditions. The first cse ws with gross power production of kw. The second cse ws with gross power production of 23 kw. The ORC designed hs n energy nd exergy efficiencies of 1.2%, 48.5% nd 8.8%, 42.2%, respectively. Wste het recovery using het pipe technology hs een investigted on mny different pplictions. Tin et l. [5] investigted new type of het pipe sed het exchnger pplied on wste het recovery of flue gs. The het pipe is composed of condensing shell nd tue chmer nd finned pipe evportor. The clen ir is used to pre het the urner ir supply. This led to reduction of 15% of nturl gs consumption nd therefore reduction of greenhouse gs emissions. Jouhr et l. [6] developed nd vlidted novel flt het pipe sed photovoltic therml (PV/T) system clled het mt. The new design performs s uilding envelope. Three het mts were tested in rel ppliction scle s follows: two PV/T system configurtions, one with cooling cycle nd one without, nd third het mt without PV lyer, which ws using mixture of wter/glycol s cooling fluid. The experiments exmined the effects of cooling cycles on the electricl output nd the temperture of the het pipe PV/T pnels. The electricl efficiency ws incresed y 15% with the use of n ctive cooling cycle in the pnels. Moreover, the temperture rnge ws decresed from the rnge of 4 to 58 C to the rnge of 28 to 33 C. The therml efficiency of the het mt without PV lyer ws round 64%, while the efficiency of the het mt with the PV lyer ws round 5%. The ility of the het mt to sor het from the mient ws studied s function of ir speed nd the temperture difference etween the mient nd cooling wter. Yng et l. [7] proposed design of high temperture flt het pipe receiver in solr power tower plnt. The strt-up nd the therml performnce were experimentlly investigted. The flt het pipe consisted of stinless steel vpour chmer chrged with liquid sodium, wter jcket, nd serrted fins. The FHP ws tested t constnt het input to exmine the strt-up response nd the isotherml chrcteristics. In ddition, the impct of inclintion ngle nd het input on the strt-up time nd temperture distriution ws tested nd the est performnce ws otined ngle of 45. The effective therml conductivity, therml resistnce, nd het trnsfer efficiency of the FHP were clculted t vrious inputs. It ws noted tht the therml resistnce decreses s the het input increse, whilst the efficiency is enhnced s the het input increse. Furthermore, the stility performnce ws studied nd the FHP exhiited the potentil of long term, sfe nd uniform temperture distriution. In this pper flt het pipe is designed to recover the het y rdition nd convection from hot steel in steel industry with tempertures higher thn 5 C. The design of the FHP is presented nd experimentlly investigted. The experimentl results of the performnce of the FHP re reported. 2. Mechnicl design The flt het pipe is designed to recover the het y rdition nd convection from hot sources with tempertures higher thn 5 C. The rditive het is trnsferred through the het pipe evportor wll to inner surfce of the evportor y conduction. When the working fluid reches the sturtion tempertures, it vporizes nd flows upwrd to the condenser. The het is then trnsferred to the cooling fluid vi shell nd tue het exchnger nd condenses the working fluid. Finlly the condenste flows ck to the evportor section with the ssistnce of grvity. The flt het pipe prototype presented in Fig. 1. () is composed of 14 stinless steel pipes linked y ottom collector pipe nd top heder. The top heder is shell nd tue het exchnger consists of 8 stinless steel smooth tues within stinless steel pipe. A stinless steel sheet is fixed t the ck of the evportor section to increse the overll het trnsfer re. The dimensions of the flt het pipe re 1 m height 1 m width. A stnd hs een designed nd mnufctured to hold the system in plce presented in Fig. 1. (). It llows the system to e tested t different inclintions nd heights.

3 Hussm Jouhr et l. / Energy Procedi 123 (217) Fig. 1. () The mechnicl design of the FHP; () The stnd of the FHP 3. Experimentl setup The flt het pipe ws tested on the hot wire cooling process of the production line. The production line length is 7m. The FHP ws plced 575 cm from the eginning of the production line, t the hottest point of the cooling zone. The temperture ws mesured using K type thermocouples, while the flow rte ws mesured using flow meter. These instruments were eventully connected to dt logging system. The thermocouples positions nd the flt het pipe set up re presented on Fig. 2. (). Three thermocouples were instlled on the ottom collector (EV 1-3), n dditionl nine on the verticl het pipes (HP 1-9), three on the top heder to mesure the sturtion temperture of the working fluid (AD 1-3), one on the ck pnel of the FHP, nd two thermocouples on the inlet nd outlet wter tempertures. The speed nd temperture of the ir used to cool the wire ws mesured using Testo 425 portle nemometer. The FHP testing on-site is presented in Fig. 2. (). The flt het pipe ws chrged with wter, with n initil inclintion ngle of High temperture therml insultion ws used to insulte the top heder of the FHP nd the ck pnel to minimize the het loss to the mient surroundings. The wter supply pipe ws lso insulted to void ny rditive het trnsfer with the wter nd 3. AD 1 AD 2 AD 3 HP 1 HP 2 HP 3 HP 4 HP 5 HP 6 HP 7 HP 8 HP 9 EV 1 EV 2 EV 3 Fig. 2. Het pipe experimentl set up () Thermocouple positions; () FHP testing

4 332 Hussm Jouhr et l. / Energy Procedi 123 (217) The experimentl conditions including FHP positioning nd wter prmeters re presented in Tle 1. Tle 1. Experimentl conditions. Experiment Conditions Test 1 Test 2 Air temperture ove the hot wires 136 C Air cooling velocity 6.75 m/s 12 m/s hot wires temperture 45 C 45 C Distnce etween the FHP nd the edge of the rrier 65 cm 6 cm Distnce etween the FHP nd the eginning of the 575 cm production line FHP inclintion ngle from the verticl 12.5 Wter flow rte 23 L/min=.38 kg/s Wter inlet 26.2 C 34.7 C 4. Results nd discussion 2 Test 1 2 Test EV 1 EV 2 EV 3 HP 1 HP 2 HP 3 HP 4 HP 5 HP 6 HP 7 HP 8 HP 9 Bck pnel EV1 EV 2 EV3 HP1 HP2 HP3 HP4 HP5 HP 6 HP7 HP8 HP9 Bck pnel Fig. 3. Het pipe tempertures () Test 1; () Test 2

5 Hussm Jouhr et l. / Energy Procedi 123 (217) Test 1 1 Test AD 1 AD 2 AD AD 1 AD 2 AD 3 EV 1 EV 2 EV 3 EV1 EV 2 EV3 Fig. 4. Bottom collector nd ditic tempertures of the FHP () Test 1; () Test 2 The tests were conducted for two production processes. The first test ws chieved during high density wire production process. Fig. 3. () presents the tempertures of the FHP surfce in test 1. The fluctution of the results in the experiments is due to the steel production process where the steel is produced for out 12 seconds nd pused for 4 seconds. It ws oserved tht the temperture of thermocouple HP7 ws the highest due to the loction, the position reflected the mximum temperture (16 C) during the process. The surfce temperture of the FHP during the hot wires production vried etween 111 C nd 16 C while it decresed to the rnge of 84.9 to C when the steel production ws off. The ck pnel temperture rnged etween 162 C nd C which is expected to e higher thn the temperture of the FHP surfce since the therml conductivity of the stinless steel sheet is low. The second test ws performed during low density wire production process. The het pipe tempertures for test 2 re presented in Fig. 3. (). The surfce tempertures of the flt het pipe vried etween 8 C nd 51 C. It cn e oserved from the results tht the temperture of the thermocouples 7, 8, 9 ws higher thn the temperture of the ottom collector. The film oiling present is reflected s n incrementl increse s shown in thermocouple positions 4, 5, 6, 1, nd 3. Thermocouple 2 hd the lowest temperture vlue, this temperture could e explined y filing thermocouples or d instlltion. The temperture of the ottom collector nd the ditic section of the FHP in test 1 nd test 2 re presented in Fig. 4. (), nd (). In test 1 the verge temperture of the ottom collector ws out 65.7 C t the mximum nd 61.2 C t the minimum when the production is off. While the verge temperture of the thermocouples plced on the top heder which represents the ditic section vried etween 76.4 C nd 66 C. However in test 2, the thermocouples on the ditic section displyed tempertures of 6 C while the three thermocouples plced on the ottom collector showed tempertures of 4 C. It cn e oserved tht the temperture of the ottom collector ws lower thn ditic section ecuse the ottom collector ws not receiving sufficient mount of rditive het. Wter inlet nd outlet tempertures re illustrted in Fig. 5. () for the first nd second experiment. The outlet temperture ws vrying y time s result of vrying the therml performnce of the het pipe. The wter inlet temperture ws nerly constnt t 26.2 C while the verge temperture of the wter outlet ws 33.4 C. In the second test the wter inlet temperture vried etween nd 33.6 C nd 36.2 C, wheres the verge wter outlet temperture ws 41.4 C nd reched mximum vlue of 45.3 C. The het trnsfer rte otined for oth experiments is illustrted in Fig. 5. (). In test 1, the het trnsfer rte reched mximum vlue of 15.6 (kw) nd minimum vlue of 9.1 (kw) nd the verge het trnsfer during the test ws 11 (kw), while the het trnsfer in test 2 the het rte vried etween 14.8 (kw) nd 8.4 (kw). The verge het trnsfer rte during 18 seconds is 1.7 (kw). It cn e oserved tht results in test 1 were higher thn test 2 due to higher density of steel wires. The vrition in results cn e due to the vrition in plcement of the FHP longside the rod conveyor.

6 334 Hussm Jouhr et l. / Energy Procedi 123 (217) Wter inlet nd outlet tempertures Wter inlet test 1 Wter outlet test 1 Wter inlet test 2 Wter outlet test 2 Het trnsfer rte (kw) Het trnsfer rte Test 1 Test 2 5. Conclusion Fig.5. () Wter inlet nd outlet tempertures during Test 1 nd Test 2; () Het trnsfer rte in Test 1 nd Test 2 A flt het pipe (FHP) het exchnger for wste het recovery from high temperture steel production ws presented nd tested. The FHP ws tested t two different distnces from the edge of the steel conveyor t two different production density. The therml performnce of the FHP nd the het trnsfer rte ws investigted. The working temperture of the FHP rnged etween 8 C nd 6 C while the surfce temperture of the FHP reched mximum vlue of 16 C. The FHP ws le recover het up to 15.6 (kw) for wter flow rte of.38 kg/s nd hot source t 45 C. It cn e oserved from the results tht the FHP is promising technology for wste het recovery in steel industry with mny chllenges such s high temperture source nd limited ville spce on sites. More experiments should e crried out to investigte the performnce of the FHP in vrious production process conditions nd for different ngle nd position on the hot wire cooling line. Acknowledgments The reserch presented in this pper hs received funding from the Europen Union s Horizon 22 reserch nd innovtion progrmme under grnt greement No The uthors would like to thnk Sr Diz from Innvel Scientific Services for her technicl support in the development of FHP testing crried out t wire rod mill. References [1] Zhng H, Wng H, Zhu X, Qiu YJ, Li K, Chen R, et l. A review of wste het recovery technologies towrds molten slg in steel industry. Appl Energy 213;112: [2] Liu J, Yu Q, Peng J, Hu X, Dun W. Therml energy recovery from high-temperture lst furnce slg prticles. Int Commun Het Mss Trnsf 215;69:23 8. [3] Gutiérrez Trshorrs AJ, Álvrez EÁ, Río González JL, Surez Cuest JM, Bernt JX. Design nd evlution of het recupertor for steel slgs. Appl Therm Eng 213;56:11 7. [4] Kşk Ö. Energy nd exergy nlysis of n orgnic Rnkine for power genertion from wste het recovery in steel industry. Energy Convers Mng 214;77: [5] Tin E, He Y-L, To W-Q. Reserch on new type wste het recovery grvity het pipe exchnger. Appl Energy 217;188: [6] Jouhr H, Milko J, Dnielewicz J, Syegh M., Szulgowsk-Zgrzyw M, Rmos JB, et l. The performnce of novel flt het pipe sed therml nd PV/T (photovoltic nd therml systems) solr collector tht cn e used s n energy-ctive uilding envelope mteril. Energy 215:1 7. [7] Yng L, Zhou RW, Ling X, Peng H. Experimentl investigte on het trnsfer performnce of Flt Het Pipe Receiver in Solr Power Tower Plnt investigted experimentlly. Compre to other trditionl flt het pipe, this het pipe Serrted fins of solr energy t high temperture. Appl Therm Eng 216;19:662 6.