JB/T 7658.18-1995 Horizontal condensers for ammonia refrigeration equipment
Some standard content:
Mechanical Industry Standard of the People's Republic of China
Horizontal Condenser for Ammonia Refrigeration Device
1 Subject Content and Scope of Application
JB/T 7658.18-95
Replaces 18 28
This standard specifies the terminology, product classification, technical requirements, test methods, inspection rules, marking, packaging and transportation of horizontal condensers for ammonia refrigeration devices (hereinafter referred to as condensers). This standard applies to horizontal condensers for ammonia refrigeration devices. 2 Reference standards
GB 1226
GB12241
General pressure gauge
Safety valve
, general requirements
GB/T13306 Label
JB/T 6421
JB/T 6917
JB/T 6918
ZB J73 029
ZB J73 042
3 Terminology
Technical conditions for gray iron castings for refrigeration compressorsPressure vessels for refrigeration equipment
Metal and glass sintered liquid level gauges and sight glasses for refrigerationMethods for determining the cleanliness of tubular heat exchangers for ammonia refrigeration equipmentPressure and differential pressure controllers for refrigeration
3.1 Horizontal condenser
The heat exchange tube bundle and shell are placed horizontally, and the cooling water under pressure flows back and forth in the condensation heat exchange tube bundle in multiple passes to condense the high-pressure ammonia gas compressed by the ammonia refrigeration compressor into a liquid heat exchanger. 4 Product classification
4.1 Type
The structure of the condenser is horizontal shell and tube type;
b. The cooling method of the condenser is water cooling. 4.2 Model
4.2.1 Model indication method
The model of the condenser consists of uppercase Chinese phonetic letters and Arabic numerals (hereinafter referred to as numbers). The method of indicating the model is as follows:
Retrofit number: Indicated by numbers, omitted for the first design product Nominal condensing area: Based on the external surface area of the condenser tube, indicated by numbers, m2 Code for condenser
Approved by the Ministry of Machinery Industry of the People's Republic of China on 1995-06-16 1454
Implementation on 1996-07-01
4.2.2 Model example
JB/T7658.18-95
WN25-1: Indicates a condenser with a nominal condensing area of 25m2, the first retrofit. 4.3 Basic parameters
4.3.1 The nominal condensing area of the condenser shall comply with the provisions of Table 1. Table 1
4.3.2 Thermal parameters
4.3.2.1 The heat transfer coefficient of the outer surface of the condenser K≥1045W/(m2C). 4.3.2.2 The working conditions for determining the heat transfer coefficient of the condenser shall comply with the provisions of Table 2. Table 2
Condensation temperature paper
Inlet water temperature w
Cooling water flow rate W
Water pressure loss p
Fouling coefficient
4.4 Design conditions
Water side (steel pipe)
Design pressure: ammonia side
12MPa:
Water side 0.4MPa;
Design temperature: 75℃.
5 Technical requirements
5.1 General requirements
The condenser shall comply with the provisions of this standard and be manufactured according to the drawings and technical documents approved by the prescribed procedures, or it may be manufactured according to the agreement between the user and the manufacturer.
5.2 Materials
5.2.1 The materials of the main pressure-bearing components of the condenser shall have material certificates. 5.2.2 The materials used for the condenser shall comply with the provisions of JB/T6917. 5.3 Gray iron castings
5.3.1 The gray iron castings of the condenser may refer to the provisions of JB/T6421. 5.3.2 Gray iron castings can only be used on the water side of the condenser with a pressure not exceeding 1.05MPa. 5.4 Cold and hot processing
The cold and hot processing of the condenser shall comply with the provisions of JB/T6917. 5.5 Welding and non-destructive testing
The welding and non-destructive testing of the condenser shall comply with the provisions of JB/T6917. 1455
5.6 Test plates and test specimens
JB/T 7658.18—95
The test plates and test specimens of the condenser shall comply with the provisions of JB/T6917. 5.7 Parts and components
The condenser's cylinder, flanges, supports, tube sheets, support plates, tubes and tube bundles and other parts and components shall comply with the provisions of JB/T6917. 5.8 Safety accessories
In addition to complying with the provisions of JB/T6917, the safety accessories of the condenser shall also comply with the following provisions: the overpressure relief device shall comply with the provisions of GB12241 and relevant standards; a.
The high-pressure cut-off device shall comply with the provisions of ZBJ73042; the liquid level gauge and sight glass shall comply with the provisions of JB/T6918; the pressure gauge shall comply with the provisions of GB1226.
5.9 Pressure resistance and airtightness requirements
The condenser shall be subjected to pressure resistance test and airtightness test, and the requirements shall comply with the provisions of JB/T6917. 5.10 Cleanliness
The inside of the condenser should be clean, and the impurity content in the part in contact with the refrigerant should not exceed 800mg/m2.5.11 Appearance quality
The condenser should be beautiful and elegant, and the weld surface should be free of cracks, pores, pits and slag inclusions. The outer surface should be painted, and the paint should be evenly smooth and colorful, and there should be no defects that affect the appearance. Completeness
The condenser supplied as a set should also include:
Ammonia inlet and outlet joints;
Safety valve joints,
Water inlet and outlet pipes;
Air vent and mixed gas vent joints
Pressure gauge joint;
Drain joint:
Balance pipe joint:
Assembly flanges and supports.
5.13 Accessories
The accessories of the condenser are:
Safety valve;
Pressure gauge and pressure gauge valve;
Ammonia valve;
Air vent valve;
Drain cock;
Anchor bolts.
5.13.2 The accessories of the condenser shall comply with the provisions of the relevant standards. 5.14 Warranty period
If the user complies with the provisions of the product manual, the manufacturer shall replace or repair the condenser free of charge within 18 months from the date of shipment from the manufacturer if the condenser is damaged or fails to work properly due to poor manufacturing. 6 Test method
Performance test
The performance test method of the condenser can be in accordance with the provisions of Appendix A (reference part), or industrial operation test can be adopted. 1456
6.2 Nondestructive testing
JB/T 7658. 18—95
The method of nondestructive testing of condensers shall comply with the provisions of JB/T6917. 6.3 Pressure test and airtightness test
The pressure test and airtightness test methods of condensers shall comply with the provisions of JB/T6917. 6.4 Cleanliness determination
The cleanliness determination of condensers may refer to the provisions of ZBJ73029. 7 Inspection rules
General requirements
The condensers shall be inspected by the technical inspection department of the manufacturer in accordance with this standard and technical documents, and shall not be shipped out of the factory until they are qualified. 7.2 Inspection items
7.2.1 Inspection classificationwww.bzxz.net
The inspection of condensers is divided into factory inspection and type inspection. 7.2.2 Inspection items
The inspection items of condensers shall comply with the provisions of Table 3. Table 3
Inspection items
Performance test
Cleanliness
Material report of main pressure-bearing parts
Processing quality
Casting quality
Appearance quality
Non-destructive testing report
Pressure resistance and airtightness test
Check the contents of the label
Check the completeness of the product according to the factory documents
7.3 Factory inspection
Each condenser shall be inspected after manufacture. 7.4 Type inspection
Factory inspection
Type inspection
7.4.1 Type inspection shall be carried out for new products of at least one specification of condenser or old products that have undergone major reforms. 7.4.2 The performance test method of the condenser may be in accordance with the provisions of Appendix A, or industrial operation test may be adopted. 8 Marking, packaging and transportation
8.1 Marking
8.1.1 Label
A label should be fixed on the condenser at a conspicuous and flat position. The label should comply with the provisions of GB/T13306. The contents marked on the label can refer to the provisions of JB/T6917.
8.1.2 Factory documents
The factory documents of the condenser can refer to the provisions of JB/T6917. 8.2 Packaging and transportation
JB/T7658.18—95
8.2.1 All the pipes of the condenser shall be coated with anti-rust agent and properly sealed. The assembled flange shall be tightened with bolts. The flange sealing surface shall be coated with anti-rust grease and sealed with a blind plate.
8.2.2 The painting, packaging and transportation of the condenser may refer to the provisions of JB/T6917. 1458
A1 Scope and purpose
JB/T 7658. 18 --95
Appendix A
Performance test method of water-cooled condenser
(reference)
A1.1 This appendix specifies the test method for water-cooled condenser. A1.2 To achieve the purpose of this month, this appendix:
a: lists and defines the terms proposed for calibrating the capacity of water-cooled condensers; b. establishes the test method as the basis for obtaining the capacity of water-cooled condensers. A2 Terminology
A2.1 Water-cooled condenser
A device assembled from components that allows the refrigerant vapor flowing through to maintain a heat transfer relationship with water, thereby condensing the refrigerant vapor into liquid.
A2.2 Total heat rejection of refrigerant
The total effective heat removed from the refrigerant flowing through the water-cooled condenser, that is, the product of the weight flow rate of the refrigerant and the difference between the melting point of the inlet and outlet refrigerant fluids.
A2.3 Heat rejection in the condensing section
Of the total heat rejection of the refrigerant, the portion of heat that reduces the superheat of the incoming refrigerant vapor and condenses it into a saturated liquid, that is, the product of the weight flow rate of the refrigerant and the difference between the melting point of the saturated refrigerant liquid at the inlet refrigerant vapor pressure and the outlet pressure. A2.4 Heat rejection of refrigerant in subcooling stage
The total heat rejection of refrigerant minus the heat rejection of condensing stage, that is, the product of the weight flow rate of refrigerant and the difference between the saturated refrigerant liquid flame at the refrigerant outlet pressure and the refrigerant liquid melt at the actual outlet temperature. A3 Expression of test results
A3.1 Recommended terms for expressing test results A3.1.1 The following values should be stated in expressing test results: a.
Heat rejection of condensing stage, W;
Heat rejection of subcooling stage, W;
Saturated temperature of refrigerant vapor at the site, C, water inlet temperature, C;
Water flow rate, g/s;
Water pressure drop across the condenser, kPa.
A4 Test method
A4.1 Standard test method
A4.1.1 The test must be conducted under specified conditions and consist of a main test and a verification test conducted simultaneously. It can also consist of a main test, but two sets of measurements must be conducted, with an interval of at least 1 hour between the two sets of measurements. A4.1.2 Specified conditions include:
Total heat rejection of refrigerant, W (or saturation temperature at the inlet of refrigerant vapor, C); a.
Inlet water temperature,;
Water flow rate, g/s;
JB/T 7658. 18--95
Minimum superheat of refrigerant vapor at the inlet, C: d.
Minimum ambient temperature, C:
Refrigerant used.
The results of the verification test must be within ± 3% of the results of the main test, but must be determined by the main test A4.1.3
when calibrating the condenser capacity.
The refrigerant must be driven through the condenser by one of the following devices: A4.1.4
Refrigeration compressor and low-pressure side evaporator or calorimeter (preferable method): b.
Refrigerant vapor generator.
A4.2 Main Test Methods
A4.2.1 The main test for closed condensers must include the following methods to determine the heat rejection of the refrigerant: Determine the heat rejection to the water;
Calculate the heat rejection to the surrounding air through the external surface of the condenser. b.
A4.2.2 The heat rejection of the refrigerant to the water is the product of the water flow rate and the difference in the inlet and outlet water melts. A4.2.3 The water flow rate must be determined by a water meter, water flow meter, or weighing water tank. The difference between the inlet and outlet water melts must be determined by the measured temperature. A4.2.4
A4.2.5 The heat emitted through the outer surface to the surrounding air is determined according to formula (A1): q. UA(te - t)
Where: Q1.-The heat emitted through the outer surface, W; U.=x/k+1/h.
If no insulation layer is used, then /k is 0;
r-Thickness of the insulation layer, m
Thermal conductivity of the insulation layer, W/(m2.C); h-Heat release coefficient of the surrounding air. W/(m2-C), for natural convection, h=10W(m2·℃); Exposed surface area with heat loss, m\; A
Condensation temperature,
t-Average temperature of the surrounding air,.
A4.2.6 The amount of heat rejected by the external surface of the condenser must be maintained at or less than 3% of the amount of heat rejected to the feed water. A4.2.7 Test methods and calculations for open shell and tube condensers must comply with the provisions of A4.3.3b and A6.3.1. A4.3 Verification Test Methods
A4.3.1 The verification test must include auxiliary measurements of the amount of heat rejected by the refrigerant by any of the following methods: the product of the melting point difference between the refrigerant fluid entering and leaving the condenser and the refrigerant flow rate; a.
·(A1)
When a refrigerant vapor generator is used in place of the complete refrigeration system, the amount of heat added to the refrigerant fluid by the refrigerant vapor generator b.
The melting point difference between the refrigerant fluid entering and leaving the condenser must be determined by its pressure and temperature. A4.3.2
A4.3.3 The refrigerant flow rate must be determined using one of the following devices: a
Refrigerant calorimeter;
Water or brine cooler;
Refrigerant liquid meter or flow meter.
A4.3.4 A refrigerant calorimeter is a device by which the heat required for evaporation and superheating of the refrigerant fluid flowing through it can be accurately measured. The refrigerant flow rate is given by dividing the heat input, including heat leakage, by the flame difference between the inlet and outlet refrigerant fluids. A4.3.5 If necessary, the water or brine cooler must be insulated to reduce the heat loss due to leakage to a value equal to or less than 1% of the heat taken away by the water or brine.
JB/T 7658.18..95
. The refrigerant flow rate is given by dividing the heat input, including heat leakage, by the flame difference between the inlet and outlet refrigerant fluids. A5 Instruments and Test Apparatus
A5.1 General
A5.1.1 Instruments of the types and accuracies listed below must be calibrated against a standard plunger before and after each test. A5.1.2 Physical property data must be obtained from the most recent publication of "Refrigerant Tables, Diagrams and Characteristics" or the "International Handbook of Scientific and Technical Constants". A5.2 Temperature Measuring Instruments
Temperature measurements must be made using one or more of the following instruments: A5.2.1:
Glass mercury thermometer;
Thermocouple:
Resistance thermometer.
The accuracy of the thermometer must be within the following ranges: brine or water in the calorimeter, ±0.05°C; water temperature of the condenser required to verify the test calculations, ±0.05°C; all others Temperature, ±0.25℃.
A5.3 Pressure measuring instruments
A5.3.1 One or more of the following instruments must be used for pressure measurement: a.
Mercury column,
Bourdon tube pressure gauge;
Diaphragm pressure gauge.
All pressure measuring instruments must be accurate within ±1% of the absolute pressure reading or differential pressure reading. A5.4
Electrical measuring instruments
One or more of the following instruments must be used for electrical measurements: A5.4.1
Indicator
The accuracy of the electrical instrument must be within the following range: a.
Indicating instrument, full scale reading ±0.5%; integrating instrument, measured value ±1%.
A5.5 Measuring instrument for refrigerant flow
One or more of the following instruments must be used for direct volume measurement: a.
Liquid refrigerant dosing meter:
Liquid refrigerant flow meter;
Gas refrigerant flow meter.
A5.5.2 Refrigerant calorimeter or water or brine cooler The cooler may be used as a direct measure of refrigerant flow (see A4.3.4 and A4.3.5). The flow meter must be accurate to within ±1% of the flow range being measured. A5.5.3
A5.6 Instruments for measuring brine or water flow
A5.6.1 Volumetric measurements must be made using one or more of the following instruments or devices: a.
Liquid dosing meters for measuring weight or volume, liquid flow meters;
Weighing tanks, scales, and timers.
The flow meter must be accurate to within ±1% of the flow range being measured. A5.7 Time measurement
A5.7.1 Time measurement must be performed using a device with an accuracy within ±0.1% of the elapsed time. 1461
A5.8 Weight measurement
JB/T 7658. 18--95
A5.8.1 Weight measurement must be performed using a device with an accuracy within ±0.5% of the total weight measured. A6 Test steps
A6.1 Assembly of the device
A6.1.1 Assemble, connect and test the condenser and the selected instruments and devices, remove moisture, evacuate and charge with the specified amount of refrigerant. If necessary, a liquid subcooler and a vapor superheater must be used to ensure the accuracy of the measurement and to achieve the test conditions. A6.1.2 The water side surface of the condenser should be cleaned before the test, and the test results must be considered as the test results of a clean tube. A6.1.3 The refrigerant side of the condenser should be checked for non-condensable gases. For the purpose of calibrating the capacity of the condenser, the amount of non-condensable gas allowed to be present shall not exceed the amount of gas that will increase the condensing pressure by 0.25°C corresponding to the condensing temperature. A6.2 Operation and Limits
A6.2.1 Start the system in accordance with the following tolerances and requirements to achieve and maintain the specified conditions: a. The arithmetic mean of all pressure readings shall not deviate from the specified value by more than 2% of its absolute value, and each individual reading shall not deviate from the average by more than 2%. The pressure readings must be converted to absolute values in order to determine the saturation temperature of the refrigerant. b. Except for the actual temperature of the inlet refrigerant vapor and the ambient air temperature, the arithmetic mean of all temperature readings shall not deviate from the specified value by more than 0.5°C, and each individual reading shall not deviate from the average by more than 0.5°C. The temperature measurement used to determine the fluid flame must be made when the fluid is under superheated or subcooled conditions so that the correct temperature can be determined. A6.2.2 After reaching stable flow conditions, all required readings must be recorded every 15 minutes, and the test must be continued until four consecutive readings are within the specified limits. A6.2.3 The test record must include the date, the name of the recorder, the main physical parameters of the condenser tested, the refrigerant used, and all test readings.
A6.3 Calculation of Results
A6.3.1 Except for open shell and tube condensers, the total heat rejection of the refrigerant 9t determined by the main test is equal to the heat of the discharge water plus the heat dissipation of the condenser. For open shell and tube condensers, the calculation must be in accordance with A6.3.2. A6.3.2 The total heat rejection of the refrigerant g determined by the verification test is equal to the product of the weight flow rate w and the melting difference Ah of the refrigerant fluid between the inlet and outlet.
A6.3.3 The difference between the main test and the verification test results: g = 4= × 100%
shall not be greater than ±3%.
A6.3.4 The heat rejection of the condensing section 9 is obtained from the weight flow rate w, of the refrigerant determined in the main test: re, - qt/Ah
Then q. = ,Ahl
Where: △h is the difference between the melting point of the refrigerant vapor at the inlet and the flame of the saturated liquid at the outlet pressure. The heat rejection of the refrigerant in the subcooling stage is Q: =qt-q. Additional remarks:
This standard is proposed and managed by the Hefei General Machinery Research Institute of the Ministry of Machinery Industry. This standard is drafted by Wuhan New World Refrigeration Industry Co., Ltd. and Dalian Refrigeration Co., Ltd. The main drafters of this standard are: Hu Zengwu, Sun Zhengguo, Ha Hongbo, and Li Muzhen. This standard was first issued in January 1964 and revised for the first time in December 1986. 1462
..(A2)
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