NB/T 47066-2018Thermal performance test method for condensing boiler (English PDF)

Foreword

This document was issued on 6 June 2018 by the National Energy Administration of the PRC and takes effect on 1 October 2018.

It is a NB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

It is classified under ICS 27.060.30, Chinese classification J 98.

This standard has been drafted in accordance with the rules given in GB/T 1.1-2009, Directives for standardization — Part 1: Structure and drafting of standards.

This standard was proposed by and is under the jurisdiction of the National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262).

Drafting organizations of this standard: China Special Equipment Inspection and Research Institute; Harbin Institute of Technology; Shenyang Special Equipment Inspection and Research Institute; Shandong Special Equipment Inspection and Research Institute; Jiangsu Special Equipment Safety Supervision and Inspection Institute; Ningbo Special Equipment Inspection and Research Institute; Shanghai Power Equipment Complete Design and Research Institute Co., Ltd.; Shanghai Industrial Boiler Research Institute Co., Ltd.; Jiangsu Shuangliang Boiler Co., Ltd.; Zhejiang Tefu Boiler Co., Ltd.; Xi'an Jinniu Co., Ltd.; Harbin Hongguang Boiler Group Co., Ltd.; China Energy Conservation Technology Investment Co., Ltd.

Chief drafters of this standard: Qi Guoli, Guan Jian, Gao Jianmin, Wu Shaohua, Zhang Xian, Song Jimin, Li Yishan, Sun Tao, Luo Zhaoqiang, Zhang Rui, Chen Xiubin, Yang Lin, Wu Yan, Deng Longqiang, Wang Huiyun, Sun Yufeng, Xie Zhengwu, Chang Yongqiang, Yu Jiming.

This standard is issued for the first time.

This standard was approved by the National Energy Administration on 6 June 2018 under Announcement No. 8 of 2018, which released 87 industry standards, comprising 47 energy standards (NB) and 40 electric power standards (DL), and it entered into force on 1 October 2018.

1 Scope

NB/T 47066-2018 is the Chinese method for testing the thermal performance of condensing boilers. A condensing boiler is designed to cool the flue gas below the dew point of the water vapour in it, recovering the latent heat that an ordinary boiler sends up the stack - which is why its efficiency can be quoted above one hundred per cent on the lower heating value, and why measuring that efficiency honestly requires a defined method. The standard sets the scope, the normative references and the full set of terms and symbols with their units, then the general requirements: the condition of the boiler before test, the stabilisation period, the permitted variation of the operating parameters during the test, and the duration and number of runs. It specifies the measurements to be taken - fuel flow and its analysis, air and flue gas flow, temperatures at each point, oxygen and carbon dioxide in the flue gas, condensate flow and its temperature, water flow and the inlet and outlet temperatures, and the ambient conditions - with the instruments to be used and the accuracy required of each. The calculation of efficiency by the input-output method and by the heat loss method is given step by step, including the treatment of the latent heat recovered, followed by the uncertainty analysis, the correction to reference conditions, and the content of the test report. Note the printed English carries a typographic error, bolier for boiler, in clause 3.1.1.

1.1 This standard specifies the test requirements, the instruments, meters and test methods, the calculation of results, the corrections, the uncertainty analysis and the requirements for the test report for the thermal performance test of condensing boilers.

1.2 This standard is applicable to condensing boilers fired with natural gas. Other gas-fired boilers, and boilers in which condensation occurs, may be tested by reference to this standard.

The standard therefore covers the complete chain of a thermal performance test: what has to be established before the test, what has to be measured during the test, how the measured quantities are converted into efficiency figures, how those figures are corrected to the guarantee conditions, how the uncertainty of the result is evaluated, and what has to be recorded in the report.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including all amendments) applies.

GB/T 2624.2, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full — Part 2: Orifice plates.

GB/T 2624.3, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full — Part 3: Nozzles and Venturi nozzles.

GB/T 8174, Testing and evaluating method of the thermal insulation effect for equipment and pipes.

GB/T 10184, Performance test code for utility boilers.

GB/T 13610, Analysis of natural gas composition — Gas chromatography.

JJF 1059.1, Evaluation and expression of uncertainty in measurement.

3 Terms and definitions

3.1 Terms and definitions. The following terms and definitions apply to this document.

3.1.1 condensing boiler — a boiler in which the water vapour contained in the flue gas condenses continuously and thereby releases its latent heat of vaporization. (The English entry is printed on the page as condensing bolier, which is a typographical error in the original for condensing boiler.)

3.1.2 input energy — the whole of the chemical energy that can be obtained from the fuel.

3.1.3 output energy — that part of the heat which is absorbed by the working medium and which is not recovered within the boiler system.

3.1.4 reference temperature — the temperature taken as the starting point for calculating the sensible heat, and the losses of heat, of the material streams entering and leaving the boundary of the boiler system. Note: in this standard the reference temperature is taken as 25 degrees Celsius.

3.1.5 input-output method — the method of determining the thermal efficiency of a boiler by measuring the input heat and the output heat directly; it is also called the direct, or positive balance, method of measurement.

3.1.6 energy balance method — the method of determining the thermal efficiency of a boiler by examining in detail all the heat entering and leaving the boiler system; it is also called the indirect method of measurement, or the heat loss method.

3.1.7 measurement precision — the closeness of agreement between the indications, or the measured values, obtained by repeated measurement on the same or on similar objects under specified conditions; abbreviated as precision.

3.1.8 experimental standard deviation — the quantity characterizing the dispersion of the results of a set of n measurements of the same measurand.

3.1.9 measurement uncertainty — the parameter, associated with the result of a measurement, that characterizes the dispersion of the values that could reasonably be attributed to the measurand; abbreviated as uncertainty.

3.1.10 standard uncertainty — the uncertainty of measurement expressed as a standard deviation.

3.1.11 type A evaluation of measurement uncertainty — the evaluation of a component of measurement uncertainty by a statistical analysis of the measured quantity values obtained under specified measurement conditions; abbreviated as type A evaluation.

3.1.12 type B evaluation of measurement uncertainty — the evaluation of a component of measurement uncertainty by means other than a type A evaluation of measurement uncertainty; abbreviated as type B evaluation.

3.1.13 combined standard uncertainty — the standard measurement uncertainty of the output quantity obtained from the standard measurement uncertainties of the input quantities in a measurement model.

3.1.14 relative standard uncertainty — the standard uncertainty divided by the absolute value of the measured value.

3.1.15 expanded uncertainty — the product of the combined standard uncertainty and a numerical factor greater than one.

3.1.16 coverage interval — the interval containing a set of values of the measurand, determined on the basis of the information available, within which the value of the measurand lies with a stated probability.

3.1.17 coverage probability — the probability that the set of values of the measurand is contained within the stated coverage interval.

3.1.18 coverage factor — the number greater than one by which the combined standard uncertainty is multiplied in order to obtain the expanded uncertainty.

3.1.19 degrees of freedom — in the calculation of a variance, the number of terms in the sum minus the number of constraints on that sum.

3.2 Symbols

3.2 Symbols. The following symbols apply to this document.

The symbols used in this standard are expressed by Latin letters and Greek letters, and all subscripts are English abbreviations.

Table 1 is the list of the symbols adopted in this standard, and Table 2 is the explanation of the subscripts.

Table 1, item 1: A(Src) — plane projected area (for a circular surface, the outer surface area is taken); unit: square metres.

Table 1, item 2: a — half-width of the interval of the possible values of the measurand; dimensionless.

Table 1, item 3: a(i) — coefficient; dimensionless.

Table 1, item 4: C — coefficient, taken as 3 600; dimensionless.

Table 1, item 5: C(1), C(2), C(3), C(4) — constants of the equation for the specific heat capacity of a component; dimensionless.

Table 1, item 6: C(a) — range coefficient; dimensionless.

Table 1, item 7: C(BW.H2O.Cl) — chloride ion content of the boiler water; unit: mg/kg.

Table 1, item 8: C(BW.H2O.Na) — sodium ion content of the boiler water; unit: mg/kg.

Table 1, item 9: C(Sat.H2O.Cl) — chloride ion content of the condensate of the saturated steam; unit: mg/kg.

Table 1, item 10: C(Sat.H2O.Na) — sodium ion content of the condensate of the saturated steam; unit: mg/kg.

Table 1, item 11: c(p) — instantaneous specific heat capacity at constant pressure; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 12: c(p) with an overbar — mean specific heat capacity at constant pressure; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 13: c(p.a.d) — specific heat capacity at constant pressure of dry air; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 14: c(p.CO) — specific heat capacity at constant pressure of carbon monoxide; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 15: c(p.CO2) — specific heat capacity at constant pressure of carbon dioxide; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 16: c(p.f) — specific heat capacity at constant pressure of the fuel gas; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 17: c(p.fg.d) — mean specific heat capacity at constant pressure of the dry flue gas at the outlet of the last condensing heating surface; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 18: c(p.H2) — specific heat capacity at constant pressure of hydrogen; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 19: c(p.H2O) — specific heat capacity at constant pressure of water vapour; units: kilojoules per cubic metre per degree Celsius, and kilojoules per kilogram per degree Celsius.

Table 1, item 20: c(p.N2) — specific heat capacity at constant pressure of nitrogen; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 21: c(p.O2) — specific heat capacity at constant pressure of oxygen; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 22: c(p, sum of CnHn) — specific heat capacity at constant pressure of the hydrocarbons; unit: kilojoules per cubic metre per degree Celsius.

Table 1, item 23: c(xi) — sensitivity coefficient; dimensionless.

Table 1, item 24: D(ev.Sat.cr) — converted evaporation of a saturated steam boiler; unit: t/h.

Table 1, item 25: D(ev.Sat.O.M) — measured output evaporation of a saturated steam boiler; units: t/h or kg/h.

Table 1, item 26: D(ev.Sut.cr) — converted evaporation of a superheated steam boiler; unit: t/h.

Table 1, item 27: D(ev.Sut.O.M) — measured output evaporation of a superheated steam boiler; unit: t/h.

Table 1, item 28: D — inside diameter of the steam outlet pipe; unit: mm.

Table 1, item 29: d(Sat.Sa) — inside diameter of the hole of the steam sampling tube; unit: mm.

Table 1, item 30: EX — total drive efficiency; unit: percent.

Table 1, item 31: E — measurement uncertainty caused by random effects and by systematic effects; dimensionless.

Table 1, item 32: H(a.H2O.g.En) — enthalpy of the water vapour corresponding to the temperature of the air entering the boiler; unit: kilojoules per cubic metre.

Table 1, item 33: H(a.H2O.g.Re) — enthalpy of the water vapour of the air entering the boiler, corresponding to the reference temperature; unit: kilojoules per cubic metre.

Table 1, item 34: H(a.H2O.l.Re) — enthalpy released when the water vapour of the air entering the boiler is converted into water, corresponding to the reference temperature; unit: kilojoules per cubic metre.

Table 1, item 35: H(Cond.En) — enthalpy of the water entering the last condensing heating surface; unit: kJ/kg.

Table 1, item 36: H(Cond.Lv) — enthalpy of the water leaving the last condensing heating surface; unit: kJ/kg.

Table 1, item 37: H(F.En) — enthalpy of the fuel corresponding to the temperature of the fuel entering the system; unit: kilojoules per cubic metre.

Table 1, item 38: H(F.Re) — enthalpy of the fuel entering the system corresponding to the reference temperature; unit: kilojoules per cubic metre.

Table 1, item 39: H(FW) — enthalpy of the feedwater; unit: kJ/kg.

Table 1, item 40: H(FW.D) — design enthalpy of the feedwater; unit: kJ/kg.

Table 1, item 41: H(FW.M) — measured enthalpy of the feedwater; unit: kJ/kg.

Table 1, item 42: H(fg.Cond.H2O.l.Lv) — enthalpy of the condensate corresponding to the temperature of the flue gas leaving the system boundary; unit: kJ/kg.

Table 1, item 43: H(fg.Cond.H2O.l.Re) — enthalpy of the condensate corresponding to the reference temperature; unit: kJ/kg.

Table 1, item 44: H(HW.En) — enthalpy of the inlet water of a hot water boiler; unit: kJ/kg.

Table 1, item 45: H(HW.Lv) — enthalpy of the outlet water of a hot water boiler; unit: kJ/kg.

Table 1, item 46: H(Sat) — enthalpy of the saturated steam; unit: kJ/kg.

Table 1, item 47: H(Sat.D) — design enthalpy of the saturated steam; unit: kJ/kg.

Table 1, item 48: H(Sat.M) — measured enthalpy of the saturated steam; unit: kJ/kg.

Table 1, item 49: H(Sut) — enthalpy of the superheated steam; unit: kJ/kg.

Table 1, item 50: H(Sut.D) — design enthalpy of the superheated steam; unit: kJ/kg.

Table 1, item 51: H(Sut.M) — measured enthalpy of the superheated steam; unit: kJ/kg.

Table 1, item 52: H(Sut.Rh.En) — inlet enthalpy of the reheated steam; unit: kJ/kg.

Table 1, item 53: H(Sut.Rh.Lv) — outlet enthalpy of the reheated steam; unit: kJ/kg.

Table 1, item 54: H(SW.Bd) — enthalpy of the saturated water corresponding to the drum pressure, used for calculating the blowdown heat; unit: kJ/kg.

Table 1, item 55: H(WJ) — enthalpy of the spray water; unit: kJ/kg.

Table 1, item 56: H(WJ.Rh.Lv) — outlet enthalpy of the spray water of the reheated steam; unit: kJ/kg.

Table 1, item 57: H(WJ.Rh.En) — inlet enthalpy of the spray water of the reheated steam; unit: kJ/kg.

Table 1, item 58: h(ab.a) — absolute humidity of the air, that is, the mass of water vapour per kilogram of dry air; unit: kg/kg.

Table 1, item 59: h(ab.F) — absolute humidity of the gaseous fuel, that is, the mass of water vapour per kilogram of dry gaseous fuel; unit: kg/kg.

Table 1, item 60: h(ab.fg) — moisture content of the flue gas after condensation on the last condensing heating surface; unit: kg/kg.

Table 1, item 61: h(ab.fg.Cond.Lv) — moisture content of the flue gas at the outlet of the last condensing heating surface; unit: kg/kg.

Table 1, item 62: h(RH.a) — relative humidity of the air, read from the dry-bulb and wet-bulb temperatures; unit: percent.

Table 1, item 63: h(RH.fg.i) — relative humidity corresponding to measuring point i, obtained by measurement with a heat-traced humidity measuring system; unit: percent.

Table 1, item 64: k — coverage factor, confidence factor; dimensionless.

Table 1, item 65: M — mean relative molecular mass of the fuel gas; dimensionless.

Table 1, item 66: Mr(BW.Sa) — sampling rate of the boiler water; unit: kg/h.

Table 1, item 67: Mr(Cond.FW.Fl) — feedwater flow rate of the last condensing heating surface; unit: kg/h.

Table 1, item 68: Mr(CW.Fl) — circulating water flow rate of a hot water boiler; unit: kg/h.

Table 1, item 69: Mr(FW.Fl) — feedwater flow rate of the boiler; unit: kg/h.

Table 1, item 70: Mr(Sat.Sa) — flow rate of the steam sample; unit: kg/h.

Table 1, item 71: Mr(Sut.Fl) — flow rate of the superheated steam; unit: kg/h.

Table 1, item 72: Mr(Sut.Rh) — mass flow rate of the reheated steam; unit: kg/h.

Table 1, item 73: Mr(Sut.Sa) — sampling rate of the superheated steam; unit: kg/h.

Table 1, item 74: Mr(W.Bd) — mass flow rate of the blowdown water; unit: kg/h.

Table 1, item 75: Mr(WJ) — flow rate of the spray water; unit: kg/h.

Table 1, item 76: Mr(WJ.Rh) — mass flow rate of the spray water of the reheated steam; unit: kg/h.

Table 1, item 77: n — number of sampling holes, and the total number of parameters used to calculate R; unit: pieces.

Table 1, item 78: p — probability; dimensionless.

Table 1, item 79: p(at) — local atmospheric pressure; unit: Pa.

Table 1, item 80: p(FW) — feedwater pressure; unit: MPa.

Table 1, item 81: p(st.Sat.ta) — saturation pressure of water vapour at the temperature t(a); unit: Pa.

Table 1, item 82: p(st.Sat.ti) — saturation pressure of water vapour at the temperature t(i); unit: hPa.

Table 1, item 83: Q(gr.ar) — gross calorific value of the fuel; units: kilojoules per cubic metre, megajoules per cubic metre.

Table 1, item 84: Q(i) — ideal-gas volumetric calorific value of component i, gross or net; unit: megajoules per cubic metre.

Table 1, item 85: Q(net.ar) — net calorific value of the fuel; units: kilojoules per cubic metre, megajoules per cubic metre.

Table 1, item 86: Q(Rh) — output heat of the reheated steam; unit: kJ/h.

Table 1, item 87: Qr(B) — external heat credits; unit: kJ/h.

Table 1, item 88: Qr(Bd) — heat carried away by the blowdown water; unit: kJ/h.

Table 1, item 89: Qr(F) — input heat of the fuel; unit: kJ/h.

Table 1, item 90: Qr(HW.Cond) — output heat of the last heating surface of a hot water boiler; unit: kJ/kg.

Table 1, item 91: Qr(I) — input heat; unit: kJ/h.

Table 1, item 92: Qr(L) — heat losses; unit: kJ/h.

Table 1, item 93: Qr(O) — output heat; unit: kJ/h.

Table 1, item 94: Qr(O.HW) — output heat of a hot water boiler; unit: kJ/h.

Table 1, item 95: Qr(O.Sat) — output heat of a saturated steam boiler; unit: kJ/h.

Table 1, item 96: Qr(O.Sut) — output heat of a superheated steam boiler; unit: kJ/h.

Table 1, item 97: Qr(Sat.Cond) — output heat of the last condensing heating surface of a saturated steam boiler; unit: kJ/h.

Table 1, item 98: Qr(Sut.Cond) — output heat of the last condensing heating surface of a superheated steam boiler; unit: kJ/kg.

Table 1, item 99: Q(X) — drive energy input; unit: kW.

Table 1, item 100: q(p.B.a.d.gr) — external heat credit carried by the dry air entering the system, based on the gross calorific value; unit: percent.

Table 1, item 101: q(p.B.a.d.net) — external heat credit carried by the dry air entering the system, based on the net calorific value; unit: percent.

Table 1, item 102: q(p.B.F.gr) — external heat credit brought by the sensible heat of the fuel, based on the gross calorific value; unit: percent.

Table 1, item 103: q(p.B.F.net) — external heat credit brought by the sensible heat of the fuel, based on the net calorific value; unit: percent.

Table 1, item 104: q(p.B.H2O.gr) — external heat credit brought by the moisture in the air, based on the gross calorific value; unit: percent.

Table 1, item 105: q(p.B.H2O.net) — external heat credit brought by the moisture in the air, based on the net calorific value; unit: percent.

Table 1, item 106: q(p.B.X.gr) — external heat credit from the power of the auxiliary equipment, based on the gross calorific value; unit: percent.

Table 1, item 107: q(p.B.X.net) — external heat credit from the power of the auxiliary equipment, based on the net calorific value; unit: percent.

Table 1, item 108: q(p.L.fg.CO.HC.gr) — loss caused by the carbon monoxide and the unburned hydrocarbons in the flue gas, based on the gross calorific value; unit: percent.

Table 1, item 109: q(p.L.fg.CO.HC.net) — loss caused by the carbon monoxide and the unburned hydrocarbons in the flue gas, based on the net calorific value; unit: percent.

Table 1, item 110: q(p.L.fg.Cond.gr) — loss due to the water vapour carried away by the flue gas, based on the gross calorific value; unit: percent.

Table 1, item 111: q(p.L.fg.Cond.gr.l) — loss brought about by the absorption of the latent heat of vaporization of the water vapour that has condensed, based on the gross calorific value; unit: percent.

Table 1, item 112: q(p.L.fg.Cond.net) — loss due to the water vapour carried away by the flue gas, based on the net calorific value; unit: percent.

Table 1, item 113: q(p.L.fg.Cond.net.l) — loss brought about by the absorption of the latent heat of vaporization of the water vapour that has condensed, based on the net calorific value; unit: percent.

Table 1 continues beyond item 113 in the full standard, and Table 2 gives the explanation of every subscript used in the symbols above.