BRAZED PLATE HEAT EXCHANGERS

Transcription

1 BRAZED PLATE HEAT EXCHANGERS C O M F O R T SOLUTIONS INSTALLATION AND MAINTENANCE MANUAL DIVERSIFIED HEAT TRANSFER, INC. Website:

2 INSTALLATION AND MAINTENANCE FOR BPHEs CBE s Mounting Connections...3 Connections...2 General...3 Threaded General...2 connections...4 Allowable Threaded Connection connections...3 Loads for Pipe Assembly Conditions...4 Soldering Allowable Connections Connection...5 Loads for Pipe Assembly Conditions...3 Soldering Procedure...5 Welding Soldering Connections Connections Strainers...6 Soldering Procedure...4 Insulation...6 Welding Connections...5 Installation of CBEs in Different Applications...7 Strainers...5 Single-Phase Applications, e.g. Water/Water or Water/Oil...7 Insulation...5 Refrigerant Applications in General...8 Refrigerant Applications and Evaporators; V-Type CBEs, e.g. V27 or V Installation of BPHEs in Different Applications...6 Refrigerant Applications and Expansion Valves...8 Refrigerant Single-Phase Applications, and e.g. Freezing Water/Water Protection or Water/Oil To prevent freezing...9 Cleaning Refrigerant of Applications CBEs...9 in General...7 Warranty...11 Disclaimer Refrigerant...11 Applications and Evaporators; V-Type BPHEs, e.g. V27 or V Refrigerant Applications and Expansion Valves...7 Refrigerant Applications and Freezing Protection - To prevent freezing...8 Cleaning of BPHEs...8 Warranty...9 Disclaimer...9

3 Installation and Maintenance Manual For CBEs BPHEs Mounting Never expose unit to pulsations or excessive cyclic pressure or temperature changes. It is also important that no vibrations are transferred to heat exchanger. If re is a risk of this, install vibration absorbers. In In case case of larger of larger connection connection diameters, diameters, we advise we you advise to use you an to expanding use expanding device device pipeline. in Use pipeline. e.g. a Use rubber e.g. mounting a rubber mounting strip as a buffer strip as between a buffer between BPHE and CBE and mounting mounting clamp. clamp. In single-phase applications such as as e.g. e.g. water water to to water water or or water water to oil, to oil, mounting mounting direction direction has little has little or no or effect no effect on on performance performance of of heat heat exchanger, exchanger, but in but two-phase in two-phase applications, applications, orientation orientation of of heat heat exchanger exchanger becomes becomes very very important. important. In In two-phase applications, SWEP s DHT s CBEs BPHEs should should be be mounted vertically, with with arrow arrow on on front front plate plate pointing upwards. Several mounting suggestions suggestions for for DHT SWEP BPHEs CBEs are shown are shown below. below. Mounting Mounting stud bolts, stud in bolts, different in different versions and versions locations, and locations, are available are available on BPHEs on as CBEs an option. as an option. Supported from bottom Sheet metal bracket (rubber insert between bracket and exchanger) Crossbar and bolts (rubber insert between crossbar and exchanger) Equipped with mounting stud bolts on front or back cover plate Support legs are available for some CBEs BPHEs For smaller BPHEs CBEs it is also possible to to mount mount unit unit by simply by simply suspending suspending it from it from pipes/ pipes/connections. 21

4 Connections General All connections are brazed to heat exchanger in general vacuum brazing cycle, a process which gives a very strong seal between connection and and cover cover plate. plate. However, take take care care not not to join to join counterpart with with such such force force that that connection is damaged. is damaged. Depending on application, re re are are a lot a of lot options of options available available for for connections, connections, different different versions versions and locations, and e.g. locations, Compac e.g. flanges, CompacSAE flanges, SAE Rotalock, flanges, Victualic, Rotalock, threaded Victualic, connections threaded and connections welding connections. and welding It is important connections. to have It is important right international to have or local right standard international of connection, or local standard as y not of always connection, are compatible. as y not always are compatible. Rotalock Connections Victualic Connections Welding Connections Flanges of DIN Type, Compac flanges Flanges of SAE Type SAE O-Ring Connections Sealing surface Some connections have an external heel. The purpose of of heel heel is is to simplify to simplify pressure pressure and leakage and leakage testing of testing BPHE of in production. CBE in production. Some connections are equipped with a special plastic cap to protect Some threads connections and sealing are equipped surface of with a connection special plastic and to cap prevent to protect dirt and threads dust from and entering sealing surface BPHE. of This connection plastic cap and should to prevent be removed dirt with and care, dust in from order entering not to damage CBE. thread This plastic or any or cap should part of be connection. removed with Use care, a screwdriver, in order not pliers to damage or knife. thread or any or part of connection. Use a screwdriver, pliers or knife. 32

5 Threaded connections Threaded connections can be female or male of well-known standards such as, ISO-G, NPT and ISO 7/1. The exterior can also be hexagonal which is shown below. Externally Threaded Connections (Male) Internally Threaded Connections (Female) of Standard Type Internally Threaded Connections (Female) with a Hexagonal Exterior Allowable Connection Loads for Pipe Assembly Conditions Mb Mt The maximum allowable connection loads given below are valid for low-cycle fatigue. The maximum allowable connection loads given below are valid for low cycle fatigue. If high cycle fatigue is involved special analysis should be made Pipe Shear Force, Tension Force, Ft Bending Moment, Torque, Mt Size Fs Mb Pipe Size(kN) Shear (kp) Force(kN) Tension (kp) Force (Nm) Bending (kpm) Moment (Nm) (kpm Torque ) inches FS (lbs) FT (lbs) MB (ft.lb) MT (ft.lb) ½ ¾ ¼ ½ ½

6 Soldering Connections Soldering Connections The soldering connections (sweat connections) are in principle designed The soldering for pipes connections with (sweat dimensions (sweat connections) connections) in mm are are or in principle inches. principle designed The for measurements designed pipes with for dimensions correspond pipes with to in mm dimensions internal or inches. diameter in The mm measurements of or inches. connections. correspond The to Some measurements of internal SWEP s correspond diameter soldering of to connections internal connections. are diameter universal, Some of of i.e. DHT s connections. fit both soldering connections mm Some and of SWEP s inch are pipes. universal, soldering These i.e. connections are fit denominated both are mm universal, xxu, and such inch i.e. pipes. as fit both These 28U are denominated which mm and fits inch both xxu, pipes. such 1 1/8 These as and are U denominated which mm. fits both xxu, such 1 1/8 as and U mm. which fits both 1 1/8 and mm. All BPHEs CBEs are are vacuum-brazed with with eir eir a pure a pure copper copper filler filler or a nickel-based or a nickel-based filler. Under filler. normal Under normal All soldering CBEs soldering conditions are vacuum-brazed conditions (no vacuum), (no with vacuum), eir temperature a pure temperature should copper not filler should exceed or not a 1470 F nickel-based exceed (800 C) F filler. Too (800 C). Under much Too normal heat much could soldering heat change could conditions change material (no structure material vacuum), resulting structure temperature in resulting internal or should in external internal not leakage or exceed external at 1470 F leakage connection. (800 C). at connection. Too much heat Because of this Because could change we recommend of this we material that recommend structure all soldering that resulting is made all soldering internal with silver is solder made or external containing with leakage silver min. solder at 45% containing connection. silver. This min. Because type 45% of solder silver. of this has This we a relatively type recommend of solder that low soldering has all a relatively soldering temperature low is soldering made with and high temperature silver solder moistening and and high containing fluidity moistening min. properties. and 45% fluidity silver. properties. This type of solder has a relatively low soldering temperature and high moistening and fluidity properties. When soldering flux is used in order to remove oxides from metal surface. This property When soldering flux is used in order to remove oxides from metal surface. This property makes When soldering flux potentially flux is used very in aggressive. order to remove Consequently, oxides from it is very metal important surface. to use This property correct makes flux potentially very aggressive. Consequently, it is very important to use correct amount makes of flux. potentially Too much, very might aggressive. lead to severe Consequently, corrosion, it so is no very flux important should be to allowed use to correct enter amount of flux. Too much, might lead to severe corrosion, so no flux should be allowed to enter amount CBE. of flux. Too much, might lead to severe corrosion, so no flux should be allowed to enter CBE. BPHE. Soldering Procedure Soldering Procedure The The hard hard silver silver soldering soldering procedure procedure for for all all BPHE CBE connections connections can can be be carried carried out out without without any any use use of The cooling hard silver water, soldering neir by procedure dimpling for under all CBE water connections nor e.g. water can be flow carried through out without waterside any use of of cooling water, neir by dimpling under water nor e.g. water flow through waterside of of cooling exchanger. water, neir by dimpling under water nor e.g. water flow through waterside of exchanger. exchanger. 1. Clean joints to be soldered. Clean inside of connection on CBE and outside Clean Clean of joints joints pipe. to to be be Degrease soldered. soldered. Clean Clean connection inside inside of properly of connection with connection on some kind on of BPHE solvent, CBE e.g. and and Tri. 2. Apply outside outside flux of of to pipe. pipe. inside Degrease Degrease of connection connection and properly properly outside with with of some some pipe. kind kind of of solvent, solvent, e.g. e.g. Tri. Tri Center Apply Apply flux pipe to to into inside connection. of of connection and and outside of of pipe Avoid Center oxidation pipe into on connection. inside of pipe by sending a flow of nitrogen through pipe 4. and Avoid oxidation CBE during on on inside soldering inside of of process. pipe pipe by by sending sending a flow a flow of nitrogen of nitrogen through through pipe pipe and 5. It and is BPHE important CBE during during that soldering connection soldering process. process. and pipe are evenly heated At It is important correct soldering that connection temperature and (1112 pipe F) are connection evenly heated. has a slightly red color The At first correct part soldering of collings temperature is done (1112 by F) keeping connection nitrogen has a slightly flowing red through color. 7. exchanger. The first part part The of of final collings cooling collings is done could is done by be keeping done by with keeping water nitrogen which nitrogen flowing removes through flowing last through exchanger. hardened flux exchanger. The on final cooling inside The final and could outside cooling be done around could with be water done solder. which with water removes which removes last hardened last flux hardened on flux inside on and outside inside and around outside around solder. solder. The minimal compound of silver must be at least 45%. Below you find an example of such a The solder. minimal compound of of silver silver must must be at be least at least 45%. 45%. Below Below you find you an find example an example of such of a such a solder. solder. Tab. 2 Solder and flux Compound (%) Melting range Tab. 2 Solder and flux Ag Cu Compound Cd (%) Zn Melting ºC Frange Hard silver solder: 454 Ag 45 Cu 15 Cd Zn ºC Flux: 800 F Welding Connections 5 54 Welding is only recommended on specially designed welding

7 Hard silver solder: 454 Flux: 800 F Welding Connections Welding is only recommended on specially designed welding connections. All SWEP s DHT s welding connections are executed with a 30 chamfer on top of connection. Do not weld on pipes on or types of connections. The measurement in mm corresponds to external diameter of connection. Welding Procedure Protect unit from excessive heating by: a) using a wet cloth around connection. b) making a chamfer on joining tube and connection edges as shown. + Use TIG or MIG/MAG welding. When using electrical welding circuits, connect ground terminal to joining tube, not to back of plate package. Internal oxidation can be reduced by a small nitrogen flow. Strainers If any of media contains particles larger than 1 mm, we recommend that a strainer be installed before exchanger with a size of mesh (number of openings per inch). The particles could orwise block channels, causing bad performance, increased pressure drop and risk of freezing. Some strainers can be ordered as CBE BPHE accessories. Insulation 6 5

8 Insulation Insulation for Refrigerant Applications CBE BPHE insulation is is recommended for evaporators, condensers or district heating applications, etc. For refrigeration, use use extruded insulation sheets, e.g. e.g. Armaflex or or equivalent which also also can can be be supplied supplied by by SWEP. DHT. Insulation for for Heating Applications For heating applications, various types of of insulation boxes can be used. The working temperature range defines which insulation is recommended. SWEP DHT can can supply some of of se insulation insulation types as types optional as accessories. optional accessories. Installation of BPHEs CBEs in in Different Applications Single-Phase Applications, e.g. Water/Water or Water/Oil Normally, circuit with highest temperature and/or pressure should be connected on left side of heat exchanger when arrow is pointing upwards. For example, in a typical water-to-water application, two fluids are connected in a counter-current flow, i.e. hot water inlet in connection F1, outlet F3, cold water inlet F4, outlet F2. This is because right-hand side of heat exchanger contains one channel more than lefthand side, and hot medium is thus surrounded by cold medium to prevent heat loss. F1 F3 F2 F4 6 7

9 Refrigerant Applications in General In all refrigerant applications it is very important that every refrigerant channel is surrounded by a water/brine channel on both-hand sides. Normally refrigerant side must be connected to left-hand side and and water/brine circuit circuit to to right right side side of of BPHE. CBE. If If refrigerant refrigerant is incor- is incorrectly rectly connected, connected, to to first and first last and channel, last instead channel, of instead water/brine, of water/brine, evaporation evaporation temperature temperature will drop, with will drop, risk with of freezing risk and of freezing very bad and performance. very bad performance. DHT BPHEs SWEP used CBEs as condensers used as condensers or evaporators evaporators should always should be fitted always with be adequate fitted with connections adequate connections refrigerant on side. refrigerant side. Condenser: The refrigerant (gas) is connected to upper left connection and condensate to lower left connection. The water/brine circuit inlet is connected to lower right connection and outlet to upper right connection. DHT SWEP BPHEs CBE used as condensers should always be be fitted fitted with with soldering connections on refrigerant refrigerant side. side. Evaporator: The refrigerant (liquid) is connected to lower left connection and gas gas to to upper upper left left connection. connection. The water/ The water/ brine brine circuit circuit inlet is inlet connected is connected to to upper upper right connection right connection and and outlet outlet to lower to right lower connection. right connection. DHT BPHEs SWEP used CBE as used condensers as condensers should should always be always fitted with be soldering fitted with connections soldering on connections refrigerant on side. refrigerant side. Refrig Gas IN Refrig Liq OUT F1 F3 F2 F4 Water OUT Water IN Fig. 4 Connection location: Condenser Refrig OUT Refrig Liq IN F1 F2 F3 F4 Water IN Water OUT Fig. 5 Connection location: Evaporator Refrigerant Applications and Evaporators; V-Type BPHEs, e.g. V27 or V45 Refrigerant Applications and Evaporators; V-Type CBEs, e.g. V27 or V45 The V-type BPHEs CBEs are equipped with a special distribution device at refrigerant inlet, i.e. normally port F3. The purpose of distribution device is to to evenly distribute refrigerant in in channel channel The refrigerant liquid should be connected to lower left left connection (F3) (F3) and and refrigerant refrigerant gas outlet gas outlet to to upper upper left left connection (F1). The water/brine circuit inlet should be connected to to upper right connection (F2) and outlet to to lower lower right right connection connection (F4). (F4). F3 F2 Water Ref. inlet Gas outlet F4 Water outlet Ref. Liquid inlet Refrigerant Applications and Expansion Valves The expansion valve should be placed close to inlet connection, whereas bulb should be mounted about inches mm from from vaporized refrigerant outlet connection. The pipe diameter between expansion valve and BPHE CBE should be be same as as diameter of of refrigerant liquid line. 87 8

10 For V-type BPHEs, CBEs, pressure drop drop in in internal internal distribution distribution system system must be must added be to added pressure to drop pressure in drop expansion in expansion valve to arrive valve at to arrive total at pressure total drop. pressure Normally, drop. Normally, selecting selecting next larger size next valve larger will size give valve satisfactory will give satisfactory performance. performance. Refrigerant Applications and Freezing Protection - To prevent freezing a) Use a filter < 1 mm, 16 mesh (see previous chapter on Strainers). b) Use an antifreeze when evaporation temperature is close to liquid-side freezing. c) Use a freeze protection rmostat and flow switch to guarantee a constant water flow before, during and after compressor operation. d) Avoid pump-down function. e) When starting up a system, wait a moment before starting condenser (or have reduced flow through it). Refrigerant Applications and F2 Condensers The refrigerant (gas) should be connected to upper left connection, F1, and condensate to lower left connection, F3. The water/brine circuit inlet should be connected to lower right connection, F4, and outlet to upper right connection, F2. F3 Gas inlet F4 Liquid outlet Water outlet Water inlet Cleaning of CBEs BPHEs Thanks to normally very high degree of of turbulence in in CBEs BPHEs re re is a is a self-cleaning effect effect in in channels. However, in in some some applications fouling tendency can can be be very high, e.g. when using extremely hard water at high temperatures. In such cases it is always possible to clean exchanger by circulating a cleaning liquid (CIP (CIP- Cleaning - Cleaning In In Place). Place). Use Use a tank a tank with with weak weak acid, acid, 5% phosphoric 5% phosphoric acid acid or, if or, if exchanger exchanger is frequently is frequently cleaned, cleaned, 5% oxalic 5% oxalic acid. Pump acid. Pump cleaning cleaning liquid through liquid through exchanger. exchanger. 98

11 For tough installations we recommend factory-installed CIP connections/valves for easy maintenance. F2 F1 For optimum cleaning, cleaning solution flow rate should be a minimum of 1.5 times normal flow rate, preferably in a backflush mode. After use, do not forget to rinse heat exchanger carefully with clean water. A solution A solution of 1-2% of sodium 1-2% hydroxide sodium (NaOH) hydroxide or (NaOH) sodium bicarbonate or sodium bicarbonate (NaHCO3) before (NaHCO 3 ) last before rinse ensures last rinse that ensures all acid that is neutralized. all acid is Clean neutralized. at regular Clean intervals at regular intervals CIP solution out CIP solution in F4 F3 For furr information about cleaning of For furr information about cleaning of BPHEs, please consult DHT. CBEs, please consult SWEP s CIP information or your local SWEP company. Warranty DHT offers a 12-month warranty from date of installation, but in no case longer than 15 months from date of delivery. The warranty covers only manufacturing and material defects. Disclaimer DHT s BPHE performance is based on installation, maintenance and operating conditions done in conformance with this manual. DHT cannot assume any liability for BPHEs that do not meet se criteria. For furr information, please consult DHT s technical information, local DHT distributor or factory directly. 10 9

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