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1、International Standard 7183 0 a! b) cooling with aftercooler; c) overcompression. 2 Units General use of SI units (SystBme International dUnit these are given in table 1. Table 1 - Non-3 units Measure- Unit ment name pressure bar Unit symbol bar Definition 1 bar = 105 Pa volume time litre minute hou
2、r L 1 L = ldm3 min 1 min = 60 s h lh=6Omin=36OOs 3 References IS0 131, Acoustics - Expression of physical and subjective magnitudes of sound or noise in air. IS0 266, Acoustics - Preferred frequencies for measurements- IS0 1000, Sl units and recommendations for the use of their multiples and of cert
3、ain other units. IS0 1217, Displacement compressors - Acceptance tests. IS0 1219, Fluid power systems and components - Graphic symbols. IS0 5167, Measurement of fluid flow by means of orifice plates, nozzles and Venturi tubes inserted in circular cross-section con- duits running full. IS0 5388, Stat
4、ionary air compressors - Safety rules and code of practice. IS0 5389, Turbocompressors - Performance test code. 1) IS0 5941, Compressors, pneumatic tools and machines - Preferred pressures. IEC Publication 51, Recommendations for direct acting in- dicating electrical measuring instruments and their
5、accessories. lEGPublication 651, Sound level meters. 4 Definitions 4.1 moisture content (gram per cubic metre): Ratio of water and water vapour by mass to the total volume. 4.2 vapour concentration (gram per cubic metre) : Ratio of water vapour by mass to the total volume. NOTE - Vapour concentratio
6、n was earlier called “absolute humidity” and has been used to describe what is more correctly termed “water load”, i.e. the water content of the desiccant expressed as a mass ratio. 4.3 vapour ratio: Mass ratio of water vapour (gram) to dry air (gram). NOTE - It is not recommended to express the vap
7、our ratio in parts per million (PPM). When parts per million are used (at very low dew points) it should be clearly stated whether it is on a mass or a volume ratio basis. 4.4 partial pressure (millibar) : Absolute pressure exerted by any component in a mixture. 4.5 saturation pressure (millibar): T
8、otal pressure at which moist air at a certain temperature can coexist in neutral equilibrium with a plane surface of pure condensed phase (water or ice) at the same temperature (see annex B). 1) At present at the stage of draft. -,-,- IS0 7183-1986 (E) 4.6 relative vapour pressure: Ratio of the part
9、ial pressure (millibar) of the water vapour to its saturation pressure (millibar) at the same temperature. NOTE - Relative vapour pressure is often called “relative humidity”. 4.7 relative vapour concentration: Ratio of the actual water vapour concentration (gram per cubic metre) (see 4.2) to its sa
10、turation value (gram per cubic metre) at the same temperature and pressure. 4.6 relative vapour ratio: Ratio of the actual vapour ratio (see 4.3) to the saturation vapour ratio at the same temperature. NOTE - Relative vapour ratio was earlier called “degree of saturation”. 4.9 dew point (degree Cels
11、ius): Temperature, referred to a specific pressure, at which the water vapour begins to condense. 4.9.1 atmospheric dew point: Dew point measured at at- mospheric pressure. NOTE - Atmospheric dew point should not be used in connection with compressed air drying. 4.9.2 pressure dew point: Dew point m
12、easured at the ac- tual pressure, which should be stated. 4.9.2.1 pressure dew point, nominal value: Dew point ob- tained in a dryer, which would not normally be exceeded when operating under the stated conditions. 4.16 flow-rate of a dryer: Volume flow-rate of condensed gas referred to a standard r
13、eference atmosphere condition of an absolute pressure of 1 bar and a temperature of 20 YZ (see IS0 1217). 4.10.1 volume flow at dryer inlet: Maximum volume of flow air accepted by the dryer (under the conditions given in 4.10) including air required for regeneration, pressurizing or cooling purposes
14、. 4.10.2 volume flow at dryer outlet: Maximum volume flow of air delivered by the dryer (under the conditions given in 4.10) available for use, i.e. after purge air, pressurizing air and cool- ing air flows have been deducted. 4.11 desiccant: Substance with the ability to retain water without change
15、 of state; for example, silica gel SiO*, activated alumina AI,O,. The term thus excludes deliquescent substances. 4.12 adsorption: Physical process in which the molecules of a gas or a vapour adhere to the surface of a solid. 4.13 desorption: Driving off of water held by a desiccant. 4.13.1 regenera
16、tion : Desorption and preparation of desic- cant to enable it to enter a new period of operation. 2 4.14 absorption: Process of attracting one substance into the mass of another, so that the absorbed substance disap- pears physically. 4.14.1 liquid absorption: Drying of air or gas by means of a liqu
17、id desiccant (for example, triethyleneglycol or sulfuric acid). 4.14.2 deliquescence: Spontaneous process whereby a soluble solid material absorbs water and becomes liquid. 4.16 drying by cooling: Method of liquifying part of the condensable vapours by reducing the temperature. 4.16 drying by overco
18、mpression: Method of drying air by compressing it to a pressure higher than the intended working pressure. 5 Types of compressed air dryers 5.1 Absorption dryers 5.1.1 Compressed air dryers, which extract water vapour from the compressed air, where the absorbent combines chemically with the water va
19、pour and goes into solution. The hydrous solution is drained off; the absorbent is normally not recovered. 5.1.1.1 5.1.1.2 Liquid desiccant Deliquescent substances 5.2 Adsorption dryers 5.2.1 Compressed air dryers, which extract water vapour from the compressed air by attraction and adhesion of mole
20、cules in a gaseous or liquid phase to the surface of a solid. The adsorbent can be regenerated by removing the adsorbed water. 5.2.1.1 heatless: Regeneration is achieved with non-heated, expanded, previously dried air. 5.2.1.2 directly heated : Regeneration is achieved by heating elements applied to
21、 or embedded in the desiccant. 5.2.1.3 regeneration air heated: Regeneration is achieved by passing heated ambient air through the desiccant. 5.2.1.4 regeneration : Achieved by adsorption and absorp- tion. 5.3 Refrigeration dryers 53.1 Compressed air dryers, which extract water vapour by means of co
22、oling with a refrigeration circuit. -,-,- IS0 7183-1986 (E) 5.3.1.1 chilled water: Drying is achieved by cooling the air in a heat exchanger using chilled fluid. 5.3.1.2 heat absorbing mass: Drying is achieved by indirect cooling via thermal storage. 5.3.1.3 direct expansion: Drying is achieved by e
23、vaporating the refrigerant at high velocity inside the heat exchanger tubes. 5.3.1.4 flooded evaporator: Drying is achieved by evaporating the refrigerant from a pool surface within a closed vessel. 5.4 Drying achieved by combination of several systems 6 Reference (standard rating) conditions and pe
24、rformance rating parameters 6.1 Reference (standard rating) conditions and performance rating parameters are both necessary in defining the perfor- mance of an air dryer and in comparing one make of dryer with another. The reference conditions in table 2 shall form an invariable part of any statemen
25、t that performance is to IS0 7183, option A or B also being quoted. The performance rating parameters in table 3 shall form the second and variable part of such a statement. Table 2 - Reference conditions ValuelJ Quantity Unit Tolerance Option A Option I3 Inlet temperature T 35 38 +1 Inlet pressure
26、bar 7 7 + 7 % Inlet pressure dew point OC 35 3% +2 Cooling air inlet temperature OC 25 38 f3 Cooling water inlet temperature OC 25 30 +3 Ambient air temperature “C 25 38 +3 1) The choice between options A and B will be influenced by the in- tended geographical location of the equipment. Table 3 - Pe
27、rformance rating parameters Quantity Unit Outlet pressure dew point OC I Outlet air flow L/s or Value As specified As specified ms/s Pressure drop across dryer bar I As specified Frequency of electrical power SUPPlY Hz As specified 7 Specification The data given in table 4 shall, when applicable, be
28、 stated when specifying and inspecting a compressed air dryer. Other rele- vant details such as explosion proof properties, hazardous area, etc. shall also be included. 3 -,-,- IS0 7183-1986 (El Table 4 - Use and specification data Clause 7.0 Description Compressor type - 7.1 Mode of operation of co
29、mpressor plant - - 7.2 7.3 Volume of air receiver Air volume flow rate related to the intake conditions in compliance with 4.10.1 V 4Vl L, ms L/s or ms/s 7.4 Effective (gauge) pressure of the compressed air Pl bar 7.5 Temperature of compressed air t1 OC 7.6 Pressure dew point of com- pressed air $d
30、1 OC 7.7 Pressure drop across dryer AP bar 7.6 Oil presence in compressed air - g/m3 7.9 Aggressive components in air - 7.10 7.11 Coolant Coolant temperature - OC 7.11.1 Coolant quality - - t Cl - - - - - - - 7.11.2 Coolant pressure 7.12 Position of air dryer bar - 7.13 7.14 7.15 Dryer location Ambi
31、ent conditions (maximum and minimum) Power available Symbol Unit Remarks Explanatory notes Continuous/Intermittent Water/Air Before/After air receiver Indoors/Outdoors State the type of compressor(s) (for example, displacement or turbo- compressor), the type of lubrication (non-lubricated, minimum l
32、ubrication or oil flooded) and the type of coolant (air, water, oil). See IS0 8388. Details should be given of the operating intervals (“on periods”) and the position of the compressed air dryer in the compressed air pipework system. State the volume of the air receiver. The maximum compressed air v
33、olume flow accepted by the dryer under the reference conditions including air required for regeneration, pressurizing or cooling purposes. The inlet air pressure shall be stated. The temperature of compressed air at the inlet of the dryer will affect its performance and shall be stated. If the dryer
34、 is installed immediately following the compressor aftercooler, the compressed air may be assumed to be saturated. However, the humidity of the air should be measured if the dryer is installed downstream of the air receiver or in the pipework remote from the aftercoolers. - The supplier should state
35、 the type and amount of compressor lubricant that can be expected at the dryer inlet. Any pollution of incursive (aggressive) contaminants should be stated. The coolant temperature shall be measured. Any aggressive component in the coolant should be stated. When designing and specifying the air drye
36、r the position of the air receiver is important and shall be stated. It is necessary to state the location of the dryer (for example indoors, outdoors, hazardous area). Any special ambient conditions shall be stated in the enquiry. To include supply voltage, frequency and number of phases. NOTE - Th
37、e useful lives of desiccants and filter inserts are important; this is however beyond the control of the supplier as their lives are influenced by, for example, pressure drop and the content of water, oil and solid pollutants in the compressed air. 4 -,-,- IS0 7183-1986 (EI 8 Data for performance co
38、mparisons The data to be stated for performance comparisons and for technical acceptance are listed in table 5. Table 5 - Suppliers data for performance comparisons Description Type of compressed air dryer Mode of operation of compressed air dryer Symbol Unit Explanatory notes - - Specific details w
39、ith regard to operation and design/type of the compressed air dryer should be given as well as a specification of the equipment included in the delivery. - - Details should be provided of the mode of operation of the compressed air dryer, for example, continuous operation, on- off operation (for ref
40、rigeration dryers) alternating operation (in the case of adsorption dryers) as well as automatic, semi- automatic or manual. Cycle time Air volume flow rate related to the intake condition Mass flow of compressed air (if required) Qv2 4m2 S L/s or The volume of air delivered by the dryer under the r
41、eference m3/s conditions i.e. after maximum bleed air, pressurizing air and cooling air flows have been deducted. kg/s If required, the manufacturer of the dryer should calculate the mass of flow from the volume flow and state the value in the tender. Temperature of dried compressed air t2 OC The te
42、mperature shall be measured. Pressure drop across dryer AP bar If the dryer is delivered with integral filters, they shall be in- cluded in the pressure drop. Highest pressure dew point under t pd OC The maximum pressure dew point shall be stated for operating condition operating conditions. Nominal
43、 pressure dew point as t pd OC - requested by purchaser Coolant flow QVQ L/s - Energy requirements: Electric power at dryer terminals including P kW all components (this includes cooling air fans), max. and average Bleed air, dump losses, etc., max. and qv loss L/s - average Steam consumption - L/s
44、(or kg/h) - Steam condition pressure - bar - temperature - OC - Water (for cooling according to coolant 4v L/s Pressure, quality inlet temperature and temperature rise temperature which is used at any heat ex- should also be stated. changer of dryer) Noise level of air dryer - dB - NOTE - In additio
45、n to the reference conditions (see table 2, including options A or B) and the performance rating parameters (see table 31, additional data should be available when making performance comparisons. Table 4 sets out those items which may be relevant. 5 -,-,- IS0 7183-1986 (El 9 Performance measuring an
46、d testing 9.1 Test conditions To obtain valid test results, constant operating conditions (inlet air pressure, inlet temperature, inlet pressure dew point, etc.) are required. These conditions shall be listed in the test report. Testing should be carried out under operating conditions specified in t
47、able 2. Performance data should then be compared to selected performance rating parameters, with adequate con- sideration given to measuring instrument tolerances. 9.6.4 Pressure dew point The pressure dew point (see 4.9.2) shall be measured at the dryer outlet. The measuring instrument used shall h
48、ave the ac- curacy indicated in table 6. Table 6 - Accuracy of dew point measurement Dew point range Accuracy OC K - 100 to below - 40 f2 9.2 Conversion of test results I - 40 to below - 10 I fl I Test conditions and results sometimes do not agree exactly with the reference conditions and the select
49、ed performance rating parameters. The precise conversion details shall therefore be agreed between the supplier and user. 9.3 Test report The test report form is given in annex A. 9.4 Test system for air dryers A diagram of a typical testing system for air dryers (see figure 1) and notes on the symbols used are given in annex B. 9.5 Saturation pressure and density of pu