Inline fouling mitigation during food processing: a sustainable novel solution

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1st International Conference onProcedia Sustainable Energy and Resource Use in Food Chains, Energy 123 (2017) 000–000 375–380 EnergyProcedia 00 (2017) ICSEF 2017, 19-20 April 2017, Berkshire, UK

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Inline Conference fouling mitigation food processing: 1st International on Sustainableduring Energy and Resource Use in Food Chains, ICSEF 2017, 19-20 April 2017, Berkshire, UK a sustainable novel solution Inline fouling mitigation during food processing: The Luanga 15th International Symposium on District Heating and Cooling Nchari*, Charles Edge, Mohammed Shafiq sustainable novel solution Jacobs DouweaEgberts, R&D, Ruscote Avenue, Banbury, OX162QU, United Kingdom Assessing the feasibility of using the heat demand-outdoor Luanga Nchari*, Edge, district Mohammed Shafiq temperature function for aCharles long-term heat demand forecast Abstract Jacobs Douwe Egberts, R&D, Ruscote Avenue, Banbury, OX162QU, United Kingdom

a a c Fouling within the fooda,b,c industry hasPina an impact both capital operation bcosts. is a great cdemand for Corre cost effective and I. Andrić *, A. , P.onFerrão , J.and Fournier ., B.There Lacarrière , O. Le sustainable antifouling solutions. An increase in internal fouling results in poor thermal efficiency during food processing. This is a coupled poor and mass transfer local to theResearch metal surface of designed heat exchangers, pipes other equipment. Internal IN+with Center forheat Innovation, Technology and Policy - Instituto Superior Técnico, Av. Rovisco Pais and 1, 1049-001 Lisbon, Portugal Abstract b increase unwanted fluid flow pressure due to restricted flow. [1, 2] It is demonstrated in this work, fouling could also potentially Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France how fouling iscDépartement mitigated with ultrasound non-invasively during and pilot scale production. When using plateNantes, heatforexchanger set-point Systèmes Énergétiques etonEnvironnement - IMT Atlantique, 4 rueThere Alfred France Fouling within the food industry has an impact both capital operation costs. isKastler, a greata44300 demand cost effective and temperature of 140°C, 128°C and 138°C was achieved without and with an attached ultrasonic transducer respectively. The sustainable antifouling solutions. An increase in internal fouling results in poor thermal efficiency during food processing.duration This is for complete fouling a mass tubular heat exchanger fromof10 to 25 hours with ultrasonic The presence of coupled with poor heatofand transfer local to theincreased metal surface designed heat exchangers, pipes transducers. and other equipment. Internal ultrasound reduces the carbon increase footprintunwanted owing to substantially reduceddue fouling. fouling could also potentially fluid flow pressure to restricted flow. [1, 2] It is demonstrated in this work, Abstract how fouling is mitigated with ultrasound non-invasively during pilot scale production. When using a plate heat exchanger set-point temperature of 140°C, 128°C and 138°C was achieved without and with an attached ultrasonic transducer respectively. The duration District heating networks are commonly addressed in the literature as 25 onehours of the most effectivetransducers. solutions for the for complete fouling of a tubular heat exchanger increased from 10 to with ultrasonic Thedecreasing presence of greenhouse gas emissions from the building These systems require high investments which are returned through the heat ultrasound reduces the carbon footprint owing sector. to substantially reduced fouling. to the changed climate conditions ©sales. 2017 Due The Authors. Published by Elsevier Ltd. and building renovation policies, heat demand in the future could decrease, ©prolonging 2017 The Authors. Published byperiod. Elsevier Ltd. the investment return Peer-review under responsibility of the scientific committee of the 1st International Conference on Sustainable Energy and Peer-review under responsibility of the scientific committee of the 1st International Conference on Sustainable Energy and The mainUse scope of thisChains. paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand Resource in Food Food Resource Use in Chains. forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 that vary Fouling; in bothNon-invasive, construction period andexchangers, typology. High Three weather scenarios (low, medium, high) and three district Keywords: Ultrasonic; Coffee, pressure water, Sustainable ©buildings 2017 The Authors. Published by Elsevier Ltd. Heat renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, heat demand Peer-review under responsibility of the scientific committee of the 1st International Conferenceobtained on Sustainable Energy values and were comparedUse with from a dynamic heat demand model, previously developed and validated by the authors. Resource in results Food Chains. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the errorUltrasonic; in annualFouling; demandNon-invasive, was lower Coffee, than 20% all weather considered). However, after introducing renovation Keywords: Heatfor exchangers, Highscenarios pressure water, Sustainable scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the * Corresponding author. Tel.: +44-129-5223963. coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and E-mail address: [email protected] improve the accuracy of heat demand estimations. 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the scientific committee of the 1st International Conference on Sustainable Energy * Corresponding author. Tel.: +44-129-5223963. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and and E-mail Resource Use [email protected] Food Chains. address:

Cooling.

1876-6102 2017demand; The Authors. Published Elsevier Ltd. Keywords:©Heat Forecast; Climatebychange Peer-review under responsibility of the scientific committee of the scientific committee of the 1st International Conference on Sustainable Energy and Resource Use in Food Chains.

1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 1st International Conference on Sustainable Energy and Resource Use in Food Chains. 10.1016/j.egypro.2017.07.272

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1. Introduction Traditional methods of cleaning in the food industry include high pressure water, rinsing with chemicals and mechanical scrubbing.[1, 2] The described novel method that uses ultrasonic transducers over traditional methods is non-invasive, cost effective, eco-friendly and thermally more efficient. In addition, this solution distinguishes itself by inhibiting fouling continuously during production and is not a post process treatment. Ultrasonic technology in antifouling began with the US Navy in the 1950s. It was found that there was significantly less marine growth around sonar transducers compared to other sections of the hull. Antifouling ultrasonic transducers have been commercially available in the marine industry for over a decade. Conventional methods such as high pressure water washing also used in the food industry are older. [3] 2. Fundamentals 2.1. Fouling Fouling is a five step process. In the first stage (initiation), nucleation of the fouling species occurs followed by the transportation of the fouling species to the surface. At the attachment stage the species deposit on the surface with possible removal of the attached species into the fluid stream. Finally, the fouling deposit may harden or weaken in the aging stage. The most common fouling model is linear where the fouling rate is steady. The fouling rate in this model compromises two rival terms including an anti-deposition or mitigation (Equation 1). The fouling rate = (deposition term) – (anti-deposition term): 𝑑𝑑𝑑𝑑𝑅𝑅𝑅𝑅𝑓𝑓𝑓𝑓 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑

= 𝛼𝛼𝛼𝛼𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝛽𝛽𝛽𝛽 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝛿𝛿𝛿𝛿 𝑅𝑅𝑅𝑅𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒 �

−𝐸𝐸𝐸𝐸

𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓

� - 𝛾𝛾𝛾𝛾Ƭ𝑤𝑤𝑤𝑤

(1)

α, β, γ and δ are parameters, Ƭ𝑤𝑤𝑤𝑤 is the wall shear stress and 𝑅𝑅𝑅𝑅𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 is the fluid temperature. From the equation, it is obvious that there are threshold conditions of temperature and velocity with insignificant fouling rates in heat exchangers. Fouling resistance (FR) characterizes the thermal effect of fouling. It is related to the deposit thickness and thermal conductivity. FR is included in a basic heat transfer equation where U and U 0 are the overall heat coefficients with and without fouling respectively. [1, 4] 1

𝑈𝑈𝑈𝑈

=

1

𝑈𝑈𝑈𝑈0

+ 𝐹𝐹𝐹𝐹𝑅𝑅𝑅𝑅

(2)

With an increase in deposition, the fouling resistance increases also resulting in a change in deposit temperature in the liquid phase. A change in deposit temperature will affect the deposition rate. [5] 2.2. Ultrasonic transducers The principle of how an ultrasonic transducer works is illustrated in Fig. 1. The transducer has a piezoelectric element that generates ultrasonic waves by repeated expansion and contraction. Ultrasonic waves are transmitted through the metal into the liquid. Vibrations in the metal/liquid interphase could potentially prevent foreign particle adhesion on the metal from the liquid. [6]



Luanga et al. / Energy Procedia 123000–000 (2017) 375–380 Luanga NchariNchari et al/ Energy Procedia 00 (2017)

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Wave Propagation

Transducer

Signal Generator Metal/Liquid Interphase

Fig. 1. Principle of Ultrasonic Transducers

2.3. Coffee composition The production of instant coffee includes the extraction of soluble solids from ground-roast coffee. The main coffee bean components are caffeine, carbohydrates, chlorogenic acids, lipids, amino acids and minerals. Coffee composition changes during roasting are the outcome of chemical reactions (pyrolysis, caramelization and Malliard reactions).The composition of coffee beans is also dependent on its species; this difference may influence coffee processing. [7, 8] Table 1. The Chemical Composition of Green and Roasted Coffee Beans [7] Arabica Robusta Arabica Robusta green green roasted roasted Constituent (% DW)

(% DW)

(% DW)

(% DW)

Caffeine

1.3

2.3

1.2

2.4

Trigoneline

0.8

0.7

0.3

0.3

Carbohydrates

53.7

50.7

38

42

Chlorogenic acids

8.1

9.9

2.5

3.8

Lipids

15.2

9.4

17.0

11

Amino acids

11.1

11.8

7.5

7.5

Organic Acids

2.3

1.7

2.4

2.6

Melanoidins

-

-

25.4

25.9

Volatile aroma

Traces

Traces

0.1

0.1

Minerals

3.9

4.4

4.5

4.7

Added to Melanoidins

Added to Melanoidins

Others

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3. Pilot Scale Trial Ultrasonic transducers were attached external to plate heat exchangers during pilot coffee extraction trials [Fig. 2]. The transducers produce ultrasonic wave frequencies preferably between 19 and 59 KHz and require a 3.6 Watts power supply. Extended pilot trials conducted on plate heat exchangers during continuous processing indicate that the fouling resistance can be significantly improved with ultrasonic energy.

Steam IN

Coffee Solution OUT

Coffee Solution IN

Steam OUT

(a)

(b)

Fig. 2. (a) Plate Heat Exchanger with Ultrasonic Transducer (b) P&ID

The heat exchanger set point was 140°C. Over a 5-day trial it only reached 128°C without any ultrasonic effect, compared to 138°C with an ultrasonic transducer, greatly improving the heat transfer [Fig. 3]. It must also be noted here that significantly less cleaning (downtime) of the heat exchanger is required with an ultrasonic transducer compared to without. Typical liquid flowrates (with coffee solids) through the plate heat exchanger are between 50 and 240 kg/hr.

Coffee Solution Temperature, °C

142 Target Temperature

140

With Ultrasound

138 136

Reduced Fouling Resistance (FR) With Ultrasound

134 132 130

Without Ultrasound

128 126

1

2

3

4

5

6 7 8 Time, Hours

9

10

11

12

Fig. 3. Improvement of Plate Heat Exchanger Performance with Ultrasound



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Further trials on a tubular steam heat exchanger showed reduced fouling with an ultrasonic transducer [Fig. 4]. With a trial length of about 20 hours, the run length until complete fouling increased from 10 to 25 hours with an ultrasonic effect [Table 2]. The flowrate of the liquid though the tubular conduit is typically between 200 and 1200 kg/hr. Steam IN

Coffee Solution OUT

Steam OUT Coffee Solution IN (a)

(b) Fig. 4. (a) Tubular Heat Exchanger (Insulated) (b) P&ID

Table 2. Impact of Ultrasound on Fouling in a Tubular Heat Exchanger Processing

Complete Fouling

Cleaning Frequency

Without Ultrasonic

10 hours

Doubled

With Ultrasonic

25 hours

-

The rate of fouling within both heat exchangers without ultrasonic transducers is predicted to be non-linear (2.1). Ultrasonic transducers are probably effective as seen in the trials because they inhibit early stage fouling build up. The impact of ultrasonic transducers on reducing fouling was more effective on the plate compared to the tubular heat exchangers as described above. This may be due to minimized metal surface vibration with the tubular heat exchangers due to increased wall thickness. Alternatively, when ultrasonic waves are propagated the generation of positive as well as negative pressures form microbubbles which inhibit inner surface adhesion. The latter requires strong acoustic waves. [6, 9] No chemical change was detected during the trials probably due to low intensity ultrasound. Ultrasonic waves with a rated output of 200 W (high intensity) promote the formation of hydrogen peroxides. [6] Table 3 below compares the low power rating of ultrasound in preventing antifouling with other applications in the marine and food industry. Table 3. Typical Ultrasonic Treatment Frequencies and Power [3, 6, 9] Type of Fouling (Industry)

Frequency

Power

Biofouling (Marine)

20 KHz

1000 W

Biofouling (Food)

20, 60 & 150KHz

70 & 200 W

Pilot Scale Trial (JDE R&D)

16 - 59 KHz

3.6 W (Low)

The transducer temperature was controlled below 100°C. Piezoelectric materials in ultrasonic transducers are not effective at high temperatures. No impact on the integrity of the equipment was noticed during the trials as a result of ultrasound waves. [9]

380 6

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4. Conclusions Inline fouling mitigation has been successfully tested at pilot scale with ultrasound with a reduced carbon footprint. It is novel because fouling mitigation is continuous during food processing. This technology is applicable to equipment other than heat exchangers including vessels, tanks, pipes etc. Further work is required to commercialize ultrasonic transducers as antifouling systems in the food industry. Development challenges to overcome include operating at higher temperatures and minimizing damping effects without impacting finished product quality. Acknowledgements The authors wish to acknowledge Jacobs Douwe Egberts Associates especially R&D Science and Technology, Instant and Manufacturing for the beneficial discussions. References [1] Melo LF, Bott TR, Bernado CA. Fouling Science and Technology Vol. 145; 1987. [2] Goode RG, Asteriadou K, Robbins PT, Fryer PJ. Fouling and Cleaning Studies in the Food and Beverage Industry Classified by Cleaning Type. Comprehensive Reviews in Food Science and Food Safety. 2013. [3] Legg M, Yucel MK, De Carellan IG, Kappatos V, Selcuk C, Gan TH. Acoustic Methods for Biofouling Control: A Review. 2015. [4] Ebert WA, Panchal CB. Fouling Mitigation of Industrial Heat-Exchange Equipment, Begell House, New York; 1997; 451-460. [5] Gomes de Cruz L, Ishiyama EM, Boxler C. Value pricing of surface coatings for mitigating heat exchanger fouling. Food and Bioproducts processing; 2015; 343-363 [6] Gong C, Hart DP. Ultrasound induced cavitation and sonochemical yields. Journal of the Acoustical Society of America; 1998; 104 [7] Oestreich J. Chemistry of Coffee. Comprehensive Natural Product; 2010; 1085-1117 [8] Cheng B, Furtado A, Smyth HE, Henry RJ. Influence of genotype and environment on coffee quality. Trends in Food Science and Technology 57; 2016; 20-30 [9] Hotrum NE, De Yong P, Fox MB. Pilot scale ultrasound enable plate heat exchanger – its design and potential to prevent biofouling. Journal of Food Engineering; 2015; 81-88