CN102900660B - Test method for testing terminal efficiency of integral reciprocating natural gas compressor unit - Google Patents

Abstract

The invention relates to a test method for testing the terminal efficiency of an integral reciprocating natural gas compressor unit, which can effectively test the terminal efficiency of the integral reciprocating natural gas compressor unit. The invention adopts the technical scheme that the method includes the steps of: taking an appropriate amount of compressed natural gas from an output end of a compressor for gas component analysis; reading the parameters of temperature, pressure and displacement on an instrument panel of the compressor unit, working out the polytropic exponents of all stages of natural gas according to the test data, and calculating the indicated power at all stages and the gross indicated power of the compressor unit; calculating the efficiency and the shaft power at jth stage of the reciprocating compressor unit, and working out the gross shaft power of the compressor from the shaft powers at all stages; and finally substituting the gross indicated power NP and the gross shaft power NI into a formula EtaT=Np/NI *100% to calculate the terminal efficiency EtaT of the compressor unit. The test method is simple and convenient, and the calculation is simple. The test method can be applied to working condition evaluation of the reciprocating compressor and for providing reference for the assessment of energy saving and consumption reducing effects of the compressor.

Description

A kind of test method of integrated reciprocating formula gas compressor set compression end efficiency

Technical field

The present invention relates to a kind of for gas engine and compressor are shared to a fuselage, a bent axle, and the test method of the integrated reciprocating formula gas compressor set compression end efficiency being arranged symmetrically.

Background technique

In petroleum chemical enterprise produces, particularly in gas industry production and conveying, Reciprocating Natural Gas Compressor is as a kind of conventional supercharging and gas transmission equipment, the utilization of its compression end energy consumption and the efficiency of compression end, direct relation compressor whether energy-conservation, whether in normal working, do not have a kind of specifically and accurately test method and evaluation criterion.Theoretically, isothermal compression situation lower compression machine power consumption is economized most, final temperature is minimum, and adiabatic compression situation lower compression machine power consumption is maximum, final temperature is the highest.But compressor is a changeable compression process between isothermal compression and adiabatic compression in compression process, its impact of factor such as machine compressed media, working environment is by compression larger.Computational methods and the integrated type compressor of existing compressor bank compression end efficiency are not inconsistent, and can not truly reflect the status of energy consumption of integrated type natural gas compressor.Therefore a kind of test method of integrated reciprocating formula gas compressor set compression end efficiency is provided, significant to the operating mode evaluation of petroleum chemical industry reciprocal compressor and energy-saving and cost-reducing judgement.

Summary of the invention

A kind of method that the object of this invention is to provide energy Validity Test integrated reciprocating formula natural gas compressor compression end efficiency, mainly refers to that gas engine and compressor share a fuselage, a bent axle, is the Reciprocating Natural Gas Compressor group that symmetrical balance distributes.

Integrated reciprocating formula gas compressor set is by gas engine, power to be input to bent axle, to have bent axle to drive compressor piston pressurized gas to do work again.The air horsepower N of input compression end _icomprise compressor compresses gas indicated power N _p, mechanical wear wasted power, heat transfer and leakage loss power, compressor indicated power refers to the power of compressed natural gas in the compressor unit time, therefore the efficiency of unit compression end is the indicated power N of compressor compresses gas _pwith compressor shaft power N _iratio.Compressor bank field test data substitution formula (1) is calculated to unit compression end efficiency;

${\mathrm{\η}}_T=\frac{N_p}{N_I}\×\%---\left(1\right)$

In formula, η _t-unit compression end efficiency, %; N _p-multistage compression indicated power sum, kW; N _i-compressor shaft power, kW; The method can be used for the measuring and calculation of multistage compressor compression end efficiency.

The present invention adopts following technological scheme: a kind of test method of integrated reciprocating formula gas compressor set compression end efficiency, it is characterized in that by compressed natural gas makings component in test compression unit and compressor operating load, obtain unit compression indicated power at different levels and air horsepower, then by formula (1), obtained the efficiency of compressor bank compression end.

Test method of the present invention and step are:

(1) compressed natural gas makings is analyzed, and gets appropriate rock gas carry out component of natural gas analysis at compressor output end with seal container, obtains compressed natural gas makings analysis report.Makings analysis report mainly comprises compressed natural gas component molar percentage, compressibility factor Z, hydrogen sulfide content, carbon dioxide content, relative density S _g, critical temperature T' _c, critical pressure p' _c, air content and total sulfur content.

(2) compressor operating load test, test unit compression cylinder inlet temperature T at different levels _j1, delivery temperature T _j2, suction pressure p _j1, exhaust pressure p _j2and air displacement q _jV.

What during test, on compressor bank instrument panel, have test instrumentation can directly read air inlet/delivery temperature, air inlet/exhaust pressure and compressor air-discharging amount; Unit instrument panel data read incomplete employing infrared radiation thermometer and directly measure air inlet/delivery temperatures at different levels, at preformed hole place, test air inlet/exhaust pressure at different levels, with ultrasonic flowmeter test compression gas discharge.

Test data substitution formula (2) is calculated to rock gas polytropic index kj at different levels;

k _j＝c _p/c _V (2)

In formula, c _pspecific heat at constant pressure kJ/ (kg ℃), the c of-rock gas _vthe specific heat at constant volume kJ/ (kg ℃) of-rock gas.Rock gas specific heat at constant pressure c wherein _p, rock gas specific heat at constant volume c _vby following formula, calculated;

$c_p={\mathrm{\Δc}}_p+c_p^0,c_V=c_p-\mathrm{\Δc}$

In formula, the specific heat at constant pressure of-rock gas under reference pressure, kJ/ (kg ℃); Δ c _p, Δ c-real gas specific heat capacity corrected value, according to equivalent reduced pressure p' _rwith equivalent reduced temperature T' _rvalue is looked into and is got from the real gas specific heat capacity correction chart of SY/T6637-2005 Appendix B, C.

The specific heat at constant pressure under reference pressure wherein by following formula, calculated:

$c_p^0=1.687(1+0.001T_{j2})/\sqrt{S_G}$

In formula, T _j2the-the j stage compressor rock gas delivery temperature, ℃; S _g-rock gas relative density.

Equivalent reduced pressure p' _r, equivalent reduced temperature T' _rby following formula, calculated;

p' _r＝p _j2/p' _c，T' _r＝T _j2/T' _c

In formula, p' _c-rock gas critical pressure, MPa; p _j2the-the j level compression cylinder exhaust pressure, MPa; T _j2the-the j level compression cylinder delivery temperature, K; T' _cthe critical temperature of-rock gas, K.Rock gas critical pressure p' _c, critical temperature T' _cby makings analysis report, measured.

Test data substitution formula (3) is calculated to unit indicated power at different levels,

$N_{\mathrm{pj}}=16.745p_{j1}{q}_{\mathrm{jv}}\frac{k_j}{k_j-1}[{\left(\frac{p_{j2}}{p_{j1}}\right)}^{\frac{k_j-1}{k_j}}-1]\frac{Z_{j1}+Z_{j2}}{{2Z}_{j1}}---\left(3\right)$

In formula, p _j1the-the j stage compressor rock gas suction pressure, MPa; q _jv-inlet air conditions lower compression machine discharge capacity, m ³/ min; Z _j1/ Z _j2-being respectively the Gas Compression Factor under air inlet/exhaust conditions, computational methods can be with reference to GB/T17747; k _jthe rock gas polytropic index of the-the j level.

The total indicated power N of multistage compressor _pindicated power N at different levels _pjalgebraic addition, i.e. N _p=Σ N _pj.

Test data substitution formula (4), formula (5) are calculated to compressor air horsepower at different levels and efficiency:

$N_{\mathrm{ij}}=\frac{N_{\mathrm{pj}}}{{\mathrm{\η}}_j}---\left(4\right)$

${\mathrm{\η}}_j=\frac{T_{j1}}{T_{j2}-T_{j1}}[{\left(\frac{p_{j2}}{p_{j1}}\right)}^{\frac{k_j-1}{k_j}}-1]\×100\%---\left(5\right)$

In formula, η _j-reciprocal compressor j stage efficiency, %; T _j1the-the j stage compressor rock gas intake temperature, K; The total air horsepower N of compressor _iair horsepower N at different levels _ijalgebraic addition, i.e. N _i=Σ N _ij.

And then calculate Reciprocating Natural Gas Compressor group compression end efficiency by formula (1).

The invention has the beneficial effects as follows: (1) test method of the present invention is easy, safety, calculate simply, when compressor bank is carried out routine and patrolled and examined inspection, all can carry out; (2) test instrument is simple, easy to operate, economic and practical; (3) calculating of compression end energy consumption efficiency can be compressor management person and provides evaluation criterion to compressor operating, economic scene, for units consumption analysis and reducing energy consumption provide reference frame, also for gas industry is efficient, energy-saving run provides a kind of determination methods.

Embodiment

Below test method of the present invention is described further.

Before selected gas compressor set is tested, need to carry out the collection of unit basic data, comprise size, the piston stroke of well station name, equipment model, unit rated power, rated speed, number of compression stages, compression cylinder cylinder diameter, single double-action of compression cylinder etc.

Tester is carried out to safety education, and the personnel that take one's test should, through training, take appointment with certificate; The major parameter such as each stage pressure, temperature, flow that should guarantee compressed natural gas in test process carries out synchronism detection, and test parameter repeats to read more than three times, and every 10 minutes readings once, calculate with arithmetic mean value by the parameters measuring.Reference temperature: 20 ℃; Reference pressure (absolute pressure): 101.3kPa.

The concrete testing procedure of test method of the present invention is as follows:

(1) compressed natural gas makings component analysis, at compressor output end, with seal container, get appropriate pressurized gas and carry out natural gas quality component analysis, composition analysis-gas chromatography > > requirement according to GB/T13610 < < rock gas, records natural gas quality analysis report.Report content comprises presses gas component content: methane (mol%), ethane (mol%), propane (mol%), isobutane (mol%); Normal butane (mol%), isopentane (mol%), pentane (mol%), hexane above (mol%), carbon dioxide (mol%), nitrogen (mol%), helium (mol%), hydrogen (mol%); And heavy hydrocarbon total amount (%), compressibility factor, base low heat value (MJ/m ³), hydrogen sulfide (g/m ³), relative density, critical temperature (K), critical pressure (MPa), air content (%), total sulfur content (mg/m ³) and water dew point (℃).

(2) compressor operating load test, has compression cylinder inlet temperature T at different levels in compressor operating load test _j1, delivery temperature T _j2, suction pressure p _j1, exhaust pressure p _j2and compressor displacement q _jV.Concrete testing procedure is:

1) unit time compressed natural gas measures examination

Unit time compressed natural gas amount should directly be enrolled the compressed natural gas tolerance of compressor measuring instrument indication.If compressor is not equipped with compressed natural gas tolerance measuring instrument, adopt ultrasonic gas flowmeter test traffic, test position should be selected on admission line straight length, and flow development length is no less than 30 times of calibers of institute's test tube line.During test, with ultrasonic flowmeter sensor, be directly attached on pipeline straight length, sensed flow meter reading after 15min, reads a secondary data every 10min, averages as calculated data.

2) compression cylinder rock gas intake temperature/delivery temperatures at different levels, the test of suction pressure/exhaust pressure

What for unit compression cylinder inlet/delivery temperatures at different levels, air inlet/exhaust pressure, have a measuring instrument can directly read compression cylinder inlet/delivery temperatures at different levels, air inlet/exhaust pressure.Can be with infrared radiation thermometer to the test of air inlets at different levels/delivery temperature for the compressor bank that compression cylinder inlet/delivery temperature monitoring is incomplete.The position of temperature test and pressure test require:

1. compression cylinder inlet temperature at different levels position before compression cylinder after knock out drum measures.

2. compression cylinder delivery temperatures at different levels position before knock out drum after compression cylinder measures.

3. compression cylinder rock gas suction pressures at different levels are directly enrolled field instrument designation data.

After unit is stable, 15min starts test, and by above-mentioned data every 10min test once, test more than three times, is averaged and got off as data logging to be calculated, completes whole testing process.

Test data substitution formula (2) is calculated to rock gas polytropic index k at different levels _j.

Test data substitution formula (3) is calculated to unit indicated power N at different levels _pj; The total indicated power N of multistage compressor _pfor indicated power N at different levels _pjalgebraic sum.

Test data substitution formula (4), formula (5) are calculated to compressor air horsepower N at different levels _ij; The total air horsepower N of compressor _ifor air horsepower N at different levels _ijalgebraic sum.

By testing and calculate the total air horsepower N of compressor bank _iwith total indicated power N _pafter by formula (1), draw Reciprocating Natural Gas Compressor group compression end efficiency eta _t.

Embodiment: integrated reciprocating formula gas compressor set compression end efficiency test calculated examples

1 certain well station unit compression end efficiency test data

The test data of 1.1 certain well station unit comprises the analysis of compressed natural gas matter: atmospheric pressure 95.6kPa; Gas component: methane 97.46mol%, ethane 1.23mol%, propane 0.16mol%, isobutane 0.031mol%; Normal butane 0.023mol%, isopentane 0.011mol%, pentane 0.007mol%, the above 0.02mol% of hexane, carbon dioxide 0.73mol%, nitrogen 0.27mol%, helium 0.011mol%, hydrogen 0.004mol%.Compressibility factor 0.998; Relative density: 0.571; Critical temperature 193.2K; Critical pressure 4.622Mpa; Air content 0.05%; Rock gas molal weight 18.926kg/kmol.

1.2 compressor operating load test data: this compressor bank is one-level compression, and compressor is processed tolerance 9323m ³/ h (mark), 26 ℃ of Compressor Inlet Temperatures, 92 ℃ of outlet temperatures; Inlet pressure 1.18MPa, outlet pressure 2.59MPa.

2 integrated reciprocating formula gas compressor set compression end efficiency calculation

2.1 test data substitution formulas (2) obtain rock gas polytropic index k _j:

(1) rock gas relative density is S _g=0.571.

(2) specific heat at constant pressure under reference pressure

(3) rock gas critical pressure p' _c, critical temperature T' _c: p' _c=4.622MPa, T' _c=193.2K.

(4) equivalent reduced pressure p' _r, equivalent reduced temperature T' _r:

p' _r＝p ₂/p' _c＝0.56 T' _r＝T ₂/T' _c＝1.89

(5) the specific heat at constant pressure capacitance c of rock gas _p, specific heat at constant volume c _vthrough tabling look-up and calculating:

C _p＝2.54(kJ/kg·K)，C _v＝1.95(kJ/kg·K)

(6) above test data and result of calculation substitution formula (2) are obtained to rock gas polytropic index k:

k＝c _p/c _V＝1.30

2.2 the 1st grade of flows, air inlet/exhaust pressure test parameter substitution formulas (3) obtain the 1st grade of indicated power NP1 of compressor:

$\begin{array}{c}{N}_{p1}=16.745p_1{q}_{1v}\frac{k}{k-1}[{\left(\frac{p_2}{p_1}\right)}^{\frac{k-1}{k}}-1]\frac{Z_1+Z_2}{{2Z}_1}\\ =247.07\left(\mathrm{kW}\right)\end{array}$

The indicated power N that compressor is total _pfor:

N _P＝ΣN _pj　＝247.07(kW)

2.3 the 1st grade of air inlet/delivery temperatures, air inlet/exhaust pressure test data substitution formulas (5) obtain reciprocal compressor the 1st stage efficiency η ₁:

$\begin{array}{c}{\mathrm{\&eta;}}_1=\frac{T_1}{T_2-T_1}[{\left(\frac{p_2}{p_1}\right)}^{\frac{k-1}{k}}-1]\&times;100\%\\ =88.91\%\end{array}$

2.4 calculate compressor j level air horsepower N by formula (4) _ij:

$N_{\mathrm{ij}}=\frac{N_{\mathrm{pj}}}{{\mathrm{\&eta;}}_j}=277.88\left(\mathrm{kW}\right)$

The total air horsepower N of compressor _ifor:

N _I＝ΣN _ij　＝277.88(kW)

2.5 above test result substitution formulas (1) calculate compressor bank compression end efficiency eta _t:

${\mathrm{\&eta;}}_T=\frac{N_p}{N_I}\&times;100\%=88.91\%$

Claims (2)

1. the test method of an integrated reciprocating formula gas compressor set compression end efficiency, it is characterized in that: first at compressor output end, with seal container, get appropriate compressed natural gas and carry out component of natural gas analysis, its component of natural gas analysis report comprises natural gas quality component molar percentage, compressibility factor Z, hydrogen sulfide content, carbon dioxide content, relative density S _g, critical temperature T' _c, critical pressure p' _c, air content and total sulfur content; Then on compressor bank instrument panel, read intake temperature T at different levels _j1, delivery temperature T _j2, suction pressure p _j1, exhaust pressure p _j2and compressor displacement q _jv; Again by test data substitution k _j=c _p/ c _vobtain rock gas polytropic index k at different levels _j, c in formula _pfor the specific heat at constant pressure of rock gas, by calculate, for the specific heat at constant pressure of rock gas under reference pressure, by calculate Δ c _pfor real gas specific heat capacity corrected value, from real gas specific heat capacity correction chart, look into and get, c _vfor rock gas specific heat at constant volume, by c _v=c _p-Δ c calculates, and Δ c is real gas specific heat capacity corrected value, from real gas specific heat capacity correction chart, looks into and gets; Again according to the k recording above _j, p _j1, p _j2, q _jv, Gas Compression Factor Z under inlet air conditions _j1, Gas Compression Factor Z under exhaust conditions _j2substitution $N_{\mathrm{pj}}=16.745p_{j1}{q}_{\mathrm{jv}}\frac{k_j}{k_j-1}[{\left(\frac{p_{j2}}{p_{j1}}\right)}^{\frac{k_j-1}{k_j}}-1]\frac{Z_{j1}+Z_{j2}}{{2Z}_{j1}}$ Calculate unit indicated power N at different levels _pj, according to N _p=Σ N _pjcalculate the total indicated power N of multistage compression unit _p; Then according to the T recording _j1, T _j2, p _j1, p _j2and k _j, substitution calculate reciprocal compressor j stage efficiency, then basis calculate compressor j level air horsepower N _ij, by air horsepower N at different levels _ijalgebraic sum is tried to achieve the total air horsepower N of compressor _i=Σ N _ij; Finally by the N trying to achieve above _p, N _isubstitution record Reciprocating Natural Gas Compressor group compression end efficiency eta _t.

2. test method according to claim 1, is characterized in that: above-mentioned Δ c _p, Δ c real gas specific heat capacity corrected value is according to equivalent reduced pressure p' _rwith equivalent reduced temperature T' _rvalue is looked into and is got from the real gas specific heat capacity correction chart of SY/T6637-2005 Appendix B, C; Equivalent reduced pressure p' _raccording to p' _r=p _j2/ p' _ccalculate equivalent reduced temperature T' _raccording to T' _r=T _j2/ T' _ccalculate, wherein p _j1, p _j2, p' _c, T' _cfor obtaining data in component of natural gas analysis report and compressor bank instrument panel.