CN102900660A - 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 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 efficient

Technical field

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

Background technique

In petroleum chemical enterprise produces, particularly in gas industry production and the conveying, Reciprocating Natural Gas Compressor is as a kind of supercharging commonly used 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 be 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, and its by compression impact of the factors such as machine compressed media, working environment is larger.Computational methods and the integrated type compressor of existing compressor bank compression end efficient 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 efficient 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

The purpose of this invention is to provide a kind of method of energy Validity Test integrated reciprocating formula natural gas compressor compression end efficient, refer to that mainly gas engine and compressor share a fuselage, a bent axle, be 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 the acting of compressor piston pressurized gas 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, so the efficient of unit compression end is the indicated power N of compressor compresses gas _PWith compressor shaft power N _IThe ratio.Compressor bank field test data substitution formula (1) is calculated unit compression end efficient;

${\mathrm{\η}}_T=\frac{N_p}{N_I}\×100\%---\left(1\right)$

In the formula, η _T-unit compression end efficient, %; 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 efficient.

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

Test method of the present invention and step are:

(1) compressed natural gas makings is analyzed, and gets an amount of rock gas at compressor output end with seal container and carries out the component of natural gas analysis, obtains compressed natural gas makings analysis report.The 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

Critical pressure Air content and total sulfur content.

(3) 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 test instrumentation was arranged on the compressor bank instrument panel during test 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, test air inlet/exhaust pressure at different levels at the preformed hole place, with ultrasonic flowmeter test compression gas discharge.

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

k _j＝c _p/c _V （2）

In the formula, c _pThe specific heat at constant pressure kJ/ of-rock gas (kg ℃), c _VThe specific heat at constant volume kJ/ of-rock gas (kg ℃).Rock gas specific heat at constant pressure c wherein _p, rock gas specific heat at constant volume c _VCalculated by following formula;

$c_p=\mathrm{\Δ}{c}_p+c_p^0,$ c _V＝c _p-Δc

In the 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 the equivalent reduced pressure With the equivalent reduced temperature

Value is looked into from the real gas specific heat capacity correction chart of SY/T6637-2005 appendix B, C and is got.

The specific heat at constant pressure under the reference pressure wherein

Calculated by following formula:

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

In the formula, T _J2-Di j stage compressor rock gas delivery temperature, ℃; S _G-rock gas relative density.

The equivalent reduced pressure

The equivalent reduced temperature

Calculated by following formula;

$p_r^{\′}=p_{j2}/p_c^{\′},$ $T_r^{\′}=\frac{T_{j2}}{T_c^{\′}}$

In the formula,

-rock gas critical pressure, MPa; p _J2-Di j level compression cylinder exhaust pressure, MPa; T _J2-Di j level compression cylinder delivery temperature, K;

The critical temperature of-rock gas, K.The rock gas critical pressure

Critical temperature

Measured by the makings analysis report.

Test data substitution formula (3) is calculated 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 the formula, p _J1-Di 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-Di j level.

The total indicated power N of multistage compressor _PNamely indicated power N at different levels _PjAlgebraic addition, i.e. N _p=∑ N _Pj

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

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

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

In the formula, η _j-reciprocal compressor j stage efficiency, %; T _J1-Di 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=∑ N _Ij

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

The invention has the beneficial effects as follows: easy, the safety of (1) test method of the present invention, calculate simply, when carrying out routine and patrol and examine inspection, compressor bank 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

The below is described further test method of the present invention.

Before selected gas compressor set is tested, need 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.

The tester is carried out 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 the test process carries out synchronism detection, and test parameter repeats to read more than three times, per 10 minutes readings once, the parameters that measures is calculated with arithmetic mean value.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, get an amount of pressurized gas at compressor output end with seal container and carry out the natural gas quality component analysis, according to GB/T13610 " composition analysis-gas chromatography of rock gas " requirement, record the 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, basic 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 the compressor operating load test _J1, delivery temperature T _J2, suction pressure p _J1, exhaust pressure p _J2And compressor displacement q _JVConcrete testing procedure is:

1) the 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 the ultrasonic gas flowmeter test traffic, test position should be selected on the admission line straight length, and flow development length is no less than 30 times of calibers of institute's test tube line.Directly be attached on the pipeline straight length with ultrasonic flowmeter sensor during test, sensed flow meter reading behind the 15min reads a secondary data every 10min, averages as calculated data.

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

Can directly read compression cylinder inlet/delivery temperatures at different levels, air inlet/exhaust pressure for what unit compression cylinder inlet/delivery temperatures at different levels, air inlet/exhaust pressure had a measuring instrument.Can be with infrared radiation thermometer to air inlets at different levels/delivery temperature test 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 the compression cylinder after knock out drum measures.

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

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

Begin test until the stable rear 15min of unit, with above-mentioned data every the 10min test once, test is averaged and is got off as data logging to be calculated more than three times, finishes whole testing process.

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

Test data substitution formula (3) is calculated unit indicated power N at different levels _PjThe total indicated power N of multistage compressor _PBe indicated power N at different levels _PjAlgebraic sum.

Test data substitution formula (4), formula (5) are calculated compressor air horsepower N at different levels _IjThe total air horsepower N of compressor _IBe air horsepower N at different levels _IjAlgebraic sum.

By test and the total air horsepower N of calculating compressor bank _IWith total indicated power N _PDraw Reciprocating Natural Gas Compressor group compression end efficiency eta by formula (1) afterwards _T

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

1 certain well station unit compression end efficiency test data

1.1 the test data of 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 the 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 formula (2) gets rock gas polytropic index k _j:

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

(2) specific heat at constant pressure under the reference pressure

$c_p^0=1.687(1+0.001t_2)/\sqrt{S_G}$

(3) rock gas critical pressure

Critical temperature

$p_c^{\′}=4.622\mathrm{MPa},$ $T_c^{\′}=193.2K.$

(4) equivalent reduced pressure

The equivalent reduced temperature

$p_r^{\′}=p_2/p_c^{\′}=0.56$ $T_r^{\′}=T_2/T_c^{\′}=1.89$

(5) the specific heat at constant pressure value 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 got rock gas polytropic index k:

k＝c _p/c _V＝1.30

2.2 the 1st grade of flow, air inlet/exhaust pressure test parameter substitution formula (3) are got the 1st grade of indicated power N of compressor _P1:

$N_{p1}=16.745p_1{q}_{1v}\frac{k}{k-1}[{\left(\frac{p_2}{p_1}\right)}^{\frac{k-1}{k}}-1]\frac{Z_1+Z_2}{2Z_1}$

$=247.07\left(\mathrm{kW}\right)$

The indicated power N that compressor is total _PFor:

N _P＝∑N _pj＝247.07(kW)

2.3 the 1st grade of air inlet/delivery temperature, air inlet/exhaust pressure test data substitution formula (5) are got reciprocal compressor the 1st stage efficiency η ₁:

${\mathrm{\η}}_1=\frac{T_1}{T_2-T_1}[{\left(\frac{p_2}{p_1}\right)}^{\frac{k-1}{k}}-1]\×100\%$

$=88.91\%$

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

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

The total air horsepower N of compressor _IFor:

N _I＝∑N _ij＝277.88(kW)

2.5 above test result substitution formula (1) is calculated compressor bank compression end efficiency eta _T:

${\mathrm{\η}}_T=\frac{N_p}{N_I}\×100\%=88.91\%$

Claims (2)

1. the test method of an integrated reciprocating formula gas compressor set compression end efficient, it is characterized in that: get an amount of compressed natural gas at compressor output end with seal container first and carry out the 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

Critical pressure

Air content and total sulfur content; Then read intake temperature T at different levels at the compressor bank instrument panel _J1, delivery temperature T _J2, suction pressure p _J1, exhaust pressure p _J2And compressor displacement q _JvAgain with test data substitution k _j=c _p/ c _VObtain rock gas polytropic index k at different levels _j, c in the formula _pBe the specific heat at constant pressure of rock gas, by

Calculate,

Be the specific heat at constant pressure of rock gas under reference pressure, by

Calculate Δ c _pBe real gas specific heat capacity corrected value, from real gas specific heat capacity correction chart, look into and get c _VFor the 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, looks into from real gas specific heat capacity correction chart and gets; Again according to the k that records above _j, p _J1, p _J2, q _Jv, Z under the air inlet _J1, Z under the exhaust _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=∑ N _PjCalculate the total indicated power N of multistage compression unit _PThen according to the T that records _J1, T _J2, p _J1, p _J2And k _j, substitution

Calculate reciprocal compressor j stage efficiency, again 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=∑ N _IjThe N that will try to achieve above at last _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 the equivalent reduced pressure

With the equivalent reduced temperature

Value is looked into from the real gas specific heat capacity correction chart of SY/T6637-2005 appendix B, C and is got; The equivalent reduced pressure

According to

Calculate the equivalent reduced temperature

According to

Calculate, wherein p _J1, p _J2,

For obtaining data in component of natural gas analysis report and the compressor bank instrument panel.