Wikisheet Advanced Plate Type Heat Exchanger

Transcription

1 Wikisheet Advanced Plate Type Heat Exchanger Evolution of heat exchanger technology more efficient, lower costs From Alfa Laval website (2016) Objective Contribute to energy efficiency program Background, Wikisheets Process Intensification within the PIN-NL program 2016 project Parties Focal points Phone Author Henk van den Berg, T h.vandenberg@utwente.nl M Second reading and comments Henk Akse, chairman PIN-NL T M henk.akse@traxxys.com Version, date 23 January 2017 Document: WikiAdvancedPlateHeatExchangerv3 Status Version 3 Comments: Wikisheet Advance Plate Type Heat Exchanger 23/1/17 1

2 1. Description Boxma (2007) stated in his Technology report: Plate exchanger consists of a pack of corrugated metal plates with portholes for the passage of two fluids between which heat transfer will take place. And: The plate pack is assembled between a pressure plate and a frame plate and compressed by tightening bolts. The plates are fitted with gaskets, which seals the channels and directs the fluids into alternate channels. Basic advantages of the plate heat exchangers are compactness, large heat transfer areas and high heat transfer coefficients. For applications where gaskets are undesirable (high pressure and temperature or very corrosive fluids), semi-welded or totally welded heat exchangers are available. Spiral heat exchangers and micro heat exchanger with etched channels belong also to the types under consideration. Generally speaking, plate or plate and frame type heat exchangers can realize lower approach temperatures and higher efficiencies than shell and tube heat exchangers. Q max = maximum thermal capacity Actual Q: minimum of flow.c p Q = ε.q max ΔT pinch = (1- ε) ΔT in We consider exchange of heat between fluid flows which do not exchange mass. In the individual flows we allow phase transition or boiling, condensation. Spiral heat exchanger, liquid/liquid and condenser All welded plate heat exchanger Wikisheet Advance Plate Type Heat Exchanger 23/1/17 2

3 Evaporator service plate and frame Fusion bounded, stainless steel P&F Continued development has led to additional types of heat exchangers showing improved performance and moreover coping with additional requirements of specific processes. 2. Process envelope A heat exchanger is always a part of a process, the heat transfer has to serve process objectives. Such as: increase the temperature so that a reaction can take place, exchange of the heat between two streams to reduce energy consumption. See e.g. Hesselgraves chapter 3 The heat exchanger as part of a system: exergetic (second law) analysis. Therefore, a number of variables have to be taken in consideration. Media Process conditions Additional requirements gas/gas, gas/liquid, liquid/liquid, phase transition, number of process streams P and ΔP, Temperatures (IN/OUT, approach, ΔT, limitations) Streams (flows, physical properties, etc.) including fouling Operation (continuous, variations) Design procedures, safety, construction vs. process requirements, material, maintenance, space, costs, cleaning etc. Process heat integration combines the specific tasks of the heats to be exchanged. Hesselgraves, chapter 6 Thermal Design shows that after the decision on the streams te be exchanged, flow profiles (cross, co or countercurrent) have to be set to sketch temperature profiles. This selection is needed to do a first calculation of the required exchange surface. Wikisheet Advance Plate Type Heat Exchanger 23/1/17 3

4 3. Advantages and limitations A key factor of plate and frame heat exchangers is the compactness, exchange area vs. volume of the equipment, see Table below. Channel size area m2/ volume m3 Conventional, e.g. S&T mm ~100 Plate type HE ~5 mm >200 Plate fin 2 mm >700 Micro en special small >3000 According to Ray K. Sinnott and Gavin Towler (2010) and other sources the following advantages and drawbacks of plate and frame heat exchangers are formulated. Advantages: - High heat transfer - turbulence on both sides of the plate, results often in less fouling - High thermal effectiveness possible - Low ΔT - down to 1K - Compactness - compared with a shell and tube unit - Cost - plates are simply pressed from flat sheets using minimum amount of metal - should always be considered for pressures below 30 bar. Costs to 30% of S&T! - Accessibility - can easily be opened up for inspection and cleaning (not for welded version, see disadvantages) - Flexibility - Extra plates can be added (not for welded version) - Short retention time - low liquid inventory and short retention time, making them particularly suitable for processing heat sensitive or expensive liquids Disadvantages, mainly for gasketed P&F: - Pressure - maximum value limited by the sealing of the gaskets and the construction of the frame. - Temperature - limited by the gasket material. - Capacity - limited by the size of the ports - Blockage - not good for solids in suspension unless special wide gap plates are used - Corrosion - The gaskets may not be suitable for organic solvents - Leakage - Gaskets always increase the risk of leakage. - Fire resistance - Cannot withstand prolonged fire For welded P&F and constructions like Compabloc, several of the drawbacks are gone. 4. Commercial status / TRL level The commercial status 2007 was extensively given by Boxma (2007). Meanwhile new developments and applications of plate heat exchangers have been realized. Vendors who e.g. present their products at the Achema exhibition are eager to show in how many processes their efficient plate heat exchangers are applied. Several manufacturers are mentioned in the publications reviewed in the next section. The development of plate heat exchangers will continue in parallel to a continued expansion of the application in industrial processes. We consider the plate heat exchanger technology as mature and having a high TRL, 9. Wikisheet Advance Plate Type Heat Exchanger 23/1/17 4

5 5. Examples of application API Schmidt-Bretten on their website lists the following typical tasks for their SIGMA plate heat exchanger in the chemical industries: - Cooling and heating of acids and caustic solutions - Cooling of highly-viscous products (e.g. latex) - Tempering and condensation of solvents (e.g. toluene) - Cooling of water circuits - Condensation of exhaust vapors, steam and multiple-material mixtures - Secondary circuits with high levels of temperature similarity ( t <2 C) - Safety circuits to avoid contamination The vendor states: In the case of an international group with a works in Düsseldorf, almost 300 SIGMA plate heat exchangers have been installed successfully. Specific examples mentioned are: - Condensation of methanol vapor. In case of one application, 12,000 kg/h methanol is condensed at 71 C and cooled down to 50 C. The pressure loss on the methanol side is approximately 65 mbar - Due to the high level of efficiency and the corresponding economic advantages, plate heat exchangers are especially suitable in the manufacture of sulfuric acids with concentrations up to 98%. Special nickel-based alloys are used as a plate material up to operating temperatures of approximately 95 C ( Hastelloy C 276, Alloy C 276 or ). The seals are implemented in Viton GF. 6. Technology and developments The development of the P&F or the CHE systems has been substantial in the last fifty years. From leaking gaskets, plugged heat exchangers to completely welded systems having equally distributed flow pattern and showing high efficiencies in heat transfer not only for liquid streams but also for condensation and evaporation. Straight forward design of a P&F heat exchanger is a challenge. Besides this, specific design procedures are required for types like spiral heat exchangers, Compabloc etc. Picon-Nunez, Polley and Jantes-Jaramillo (2010) presented an alternative design approach based on graphical representation, which facilitates the choice from the options calculated for the range of available plates with different geometries. They have estimated correlations for heat transfer and hydraulic resistance from available literature data. Arsenyeva et al.(2011) present an optimal design of plate-and-frame heat exchangers using mathematical modelling. The optimization variables are: type of plate, the numbers of passes for heat exchanging streams, the relative numbers of plates with different corrugation patterns in one PHE. Qi Li et al.(2011) provided an overview of P&F heat exchangers and other types of compact heat exchangers, its properties and conditions (P, T, flow rate, heat transfer area) for application. The authors see a need for development of additional correlations e.g. for phase transition. Wikisheet Advance Plate Type Heat Exchanger 23/1/17 5

6 7. Potential for industrial branches - Chemical process industries (MJA3 + MEE) - Oil and gas producing industry (MJA3) - Refineries (MEE) - Animal Food industry (MJA3) - Pharmaceutical industries (MJA3) - Soda water and fruit drinks industry (MJA3) - Margarine, Oil and Fat industry (MJA3) - Dairy industries (MJA3) - Fine chemistry, Special Chemistry (MJA3) - Nanoparticle manufacture (MJA3) - Air separation processes, cryogenic processes (MJA3) 8. Self assessment for application - Determine streams to be exchanged mass flows, heat duties - Set flow profiles (cross, co/countercurrent), this is related to a first choice of heat exchanger type in relationship to alternatives - Sketch temperature profiles - Considering the heat exchanger type selected assume a heat transfer coefficient and calculate the required exchange area - Equipment design hand calculations/simulations, mechanical design - This procedure to be repeated for additional heat exchanger types - Evaluate the results and continue with more accurate design procedures to quantify opportunities for compact or advanced plate heat exchangers. 9. Tags Process intensification, efficient heat exchange, small space requirement, liquids and vaporization and condensation. 10. References Bert Boxma, European Roadmap of Process Intensification, Technology report Advanced Plate Type Heat Exchangers (2007) J.E. Hesselgraves, Compact Heat Exchangers Selection, Design and Operation, Pergamon 2001, ISBN Ray K. Sinnott and Gavin Towler, Chemical engineering design, chapter 5 Heat-transfer equipment, 5 th Edition 2010, ISBN Wikisheet Advance Plate Type Heat Exchanger 23/1/17 6

7 Olga P. Arsenyeva, Leonid L. Tovazhnyansky, Petro O. Kapustenko, Gennadiy L. Khavin Optimal design of plate-and-frame heat exchangers for efficient heat recovery in process industries, Energy 36 (2011) Martin Picon-Nunez, Graham Thomas Polley, and Dionicio Jantes-Jaramillo Alternative Design Approach for Plate and Frame Heat Exchangers Using Parameter Plots, Heat Transfer Engineering, 31(9): , 2010 ISSN: print / online DOI: / Qi Li, Gilles Flamant, Xigang Yuan, Pierre Neveu, Lingai Luo, Compact heat exchangers: A review and future applications for a new generation of high temperature solar receivers, Renewable and Sustainable Energy Reviews 15 (2011) Vendor info: visited 20/12/16 visited 20/12/16 visited 21/12/16 visited 20/12/16 Wikisheet Advance Plate Type Heat Exchanger 23/1/17 7