CN104992265A - Method for evaluating influence of internal leakage of valves of coal-fired power plant thermal system on units - Google Patents

Abstract

The invention discloses a method for evaluating the influence of internal leakage of valves of a coal-fired power plant thermal system on units, comprising the following steps: determining the super-cooling degree of condensate of a condenser, and calculating the difference between the super-cooling degree value and a super-cooling degree value psi0 of condensate during acceptance test in the period of design or early production of the condenser; calculating internally-leaked heat; setting the internally-leaked heat as leaked steam heat, and calculating the amount of internal power converted from the steam heat; calculating the increase of unit power supply coal consumption rate caused by internal leakage according to the ratio of the amount of internal power to the generator power and the heat loss rate value under the amount of the internal power; and counting up the number of days d of internal leakage and the price gamma of each ton of standard coal, and calculating the economic benefit. The beneficial effects are as follows: the increase of unit power supply coal consumption rate caused by internal leakage can be calculated quantitatively, the influence of internal leakage on the economy of units can be evaluated quantitatively, and theoretical basis is provided for determining whether or not to perform valve modification on valves.

Description

The appraisal procedure that firepower plant heating system valves leakage affects unit

Technical field

The present invention relates to the appraisal procedure that a kind of firepower plant heating system valves leakage affects unit.

Background technology

The therrmodynamic system of fuel-burning power plant is often referred to its comprehensive therrmodynamic system, for principle of design Force system hot in nature, compared with the principled thermal system emphasizing economy, comprehensive therrmodynamic system in order to ensure unit starting, stopping, normal run time load change, ensure unit safety under accident conditions, be provided with very many valves, unit safety and operational flexibility are improved greatly.Whether these valves go out therrmodynamic system according to the working medium that it passes through can be divided into two classes, and a class goes out system, is called the valve that leaks outside, another kind ofly can not be system, and mainly Condenser's Hot Well is got back in steam turbine side, is called interior leakage valve.

For first kind valve, the valve namely leaked outside can measure its quality by leak rate test, no longer describes in detail.Valve for interior leakage then cannot be measured, according to previous experiences, the impact of valve on unit net coal consumption rate of interior leakage is larger, but owing to cannot measure it, cause cannot be quantitative measuring and calculating in the valve that leaks on the impact of unit economy, cannot carry out valve transformation for whether to unit provides theory support.

Summary of the invention

Object of the present invention is exactly to solve the problem, the appraisal procedure that a kind of firepower plant heating system valves leakage affects unit is provided, the method can calculate the impact of interior leakage on unit net coal consumption rate quantitatively, for unit economy assessment provides reference frame.

For achieving the above object, the present invention adopts following technical proposals:

The appraisal procedure that firepower plant heating system valves leakage affects unit, comprises the following steps:

Step one: gather unit condensing water temperature and saturation temperature corresponding to exhaust steam pressure, determine the degree of supercooling of condenser condensed water, and the hot-well depression angle value ψ calculating described degree of supercooling value and Condenser Design or first operation reception test in period ₀difference;

Step 2: the condensing water flow measuring Condenser's Hot Well, leaking heat in calculating;

Step 3: interior leaking heat is set as the steam heat leaked, adjusts the amount that it is converted into internal power;

Step 4: according to the amount of internal power and the ratio of generator power, and the heat consumption rate value under this internal power amount, leak the recruitment of the unit net coal consumption rate caused in calculating;

Step 5: leak days running d and mark coal price lattice γ per ton in statistics, computing economy benefit.

In described step one, the defining method of the degree of supercooling ψ of condenser condensed water is specially:

ψ＝t _s-t；

Wherein, t is condensing water temperature, t _sfor the saturation temperature that exhaust steam pressure is corresponding.

In described step 2, the computing method of interior leaking heat are specially:

Q1＝c·D·Δt；

Wherein, c is specific heat of water, and D is condensing water flow, Δ t=ψ-ψ ₀, be the difference of the degree of supercooling of condenser condensed water and Condenser Design or the first hot-well depression angle value of operation reception test in period.

In described step 3, adjusting the concrete grammar being converted into the amount of internal power is:

$W_r=\frac{Q_1}{3600};$

Wherein, Q ₁for interior leaking heat, W _rfor the amount of internal power.

In described step 4, the method for leaking the recruitment of the unit net coal consumption rate caused in calculating is specially:

Wherein, W _rfor the amount of internal power, W is generator power, H _tfor the heat consumption rate under this generator power, η _glfor boiler efficiency, η _gdfor pipeline efficiency, for station service power consumption rate.

In described step 5, the method for computing economy benefit is specially:

x＝Δg×d×24×W×γ/10^ ⁸；

Wherein, Δ g is the recruitment of the unit net coal consumption rate that interior leakage causes, and d is interior leakage days running, and W is generator power, and γ is the price of mark coal per ton.

The invention has the beneficial effects as follows:

The recruitment of the unit net coal consumption rate caused is leaked in the calculating that the present invention can be quantitative, and then internally leakage has made quantitative assessment to the impact of unit economy, enable the advance fund funding of power plant's initial estimate valve transformation and the economic effect of transformation, for determining whether that carrying out valve transformation to unit provides theoretical foundation.

Accompanying drawing explanation

Fig. 1 is the inventive method process flow diagram.

Embodiment

Below in conjunction with accompanying drawing, the present invention is further described.

The hydrophobic cooled water cooling in condenser of the steam discharge of turbine low pressure cylinder, low-pressure heater, condensing into water is pooled in hot well, due to valve imprecision, leak steam in steam turbine pusher side to be directly pooled in Condenser's Hot Well, condensate water is heated, after being boosted by condensate pump with the form of hot well outlet condensate water, enters low-pressure heater.

The condensate undercooling of Condenser Design does not generally consider the impact of interior leaking heat on temperature rise of condensate.Therefore, the temperature rise of condensate water, needs to calculate according to the condensate undercooling of actual measurement and the degree of supercooling of design.Owing to cannot measure quality and the enthalpy of interior leakage steam, the heat that the present invention is internally leaked is estimated by condensing water flow and temperature rise.

Interior leaking heat is from the flow passage component of steam turbine, steam turbine internal power is reduced, generator active power reduces, and generated energy reduces, in the constant situation of circulation heat, the corresponding rising of unit heat consumption rate, because station-service electricity, boiler efficiency, pipeline efficiency are constant, corresponding net coal consumption rate raises, because delivery is decided by user, when delivery is constant, coal consumption increases.

If investment undergoes technological transformation, eliminate valves leakage, make the heat of interior leakage get back to Turbine Flow Path, steam turbine internal power increases, and generator active power increases, and station-service electricity, boiler efficiency, pipeline efficiency are constant, corresponding net coal consumption rate reduces, and when delivery is constant, coal consumption reduces.Coal in power plant cost reduces, and the cost conversion of reduction is enterprise profit.

Therefore, interior leaking heat leaks for the impact of unit operation economy in really calculating quantitatively surely, and then provides theoretical foundation for whether carrying out valve transformation.

The present invention proposes the appraisal procedure that a kind of firepower plant heating system valves leakage affects unit, as shown in Figure 1, comprises the following steps:

Step one: gather unit condensing water temperature and saturation temperature corresponding to exhaust steam pressure, determine the degree of supercooling of condenser condensed water, and the hot-well depression angle value ψ calculating described degree of supercooling value and Condenser Design or first operation reception test in period ₀difference;

The defining method of the degree of supercooling ψ of condenser condensed water is specially:

ψ＝t _s-t；

Wherein, t is condensing water temperature, t _sfor the saturation temperature that exhaust steam pressure is corresponding.

Step 2: the condensing water flow measuring Condenser's Hot Well, leaking heat in calculating;

The computing method of interior leaking heat are specially:

Q1＝c·D·Δt；

Wherein, c is specific heat of water, and D is condensing water flow, Δ t=ψ-ψ ₀, be the difference of the degree of supercooling of condenser condensed water and Condenser Design or the first hot-well depression angle value of operation reception test in period.

Step 3: interior leaking heat is set as the steam heat leaked, adjusts the amount that it is converted into internal power;

Adjusting the concrete grammar being converted into the amount of internal power is:

$W_r=\frac{Q_1}{3600};$

Wherein, Q ₁for interior leaking heat, W _rfor the amount of internal power.

Step 4: according to the amount of internal power and the ratio of generator power, and the heat consumption rate value under this internal power amount, leak the recruitment of the unit net coal consumption rate caused in calculating;

The method of leaking the recruitment of the unit net coal consumption rate caused in calculating is specially:

Wherein, W _rfor the amount of internal power, W is generator power, H _tfor the heat consumption rate under this generator power, η _glfor boiler efficiency, η _gdfor pipeline efficiency, for station service power consumption rate.

Step 5: leak days running d and mark coal price lattice γ per ton in statistics, computing economy benefit.

The method of computing economy benefit is specially:

x＝Δg×d×24×W×γ/10 ^{^8}；

Wherein, Δ g is the recruitment of the unit net coal consumption rate that interior leakage causes, and d is interior leakage days running, and W is generator power, and γ is the price of mark coal per ton.

Test example:

Certain factory 300MW unit, before overhaul, in thermal test, 75%THA operating mode Computer group Condenser's Hot Well degree of supercooling is ψ=-2.08 DEG C, the condensing water flow going out hot well is D=604.707t/h, and going out hot well condensing water temperature is t=27.38 DEG C, and the degree of supercooling according to design condensate water is ψ ₀=1.2 DEG C, generator power W=250MW, unit heat consumption rate is H _t=8192kJ/kW.h.Station service power consumption rate boiler efficiency is η _gl=92.89%, pipeline efficiency is η _gd=99%, according to inspection, the valve of interior leakage is all steam, and unit runs d=1200 days altogether, and unit average load rate is 75%, mark coal price lattice γ=550 yuan per ton.

Interior leakage steam makes condensate water raise Δ t=ψ-ψ ₀=1.2-2.08=3.28 DEG C;

Interior leaking heat is Q ₁=cD Δ t=604.707 × 3.28 × 4.1868=8304.26MJ/h;

Interior leaking heat is from Turbine Flow Path, and being few work is:

Net coal consumption rate is raised:

Unit runs d=1200 days altogether, and unit average load rate is 75%, mark coal price lattice γ=550 yuan/ton per ton.

The many consumption mark coal costs estimated in units of currency:

＝Δg×d×24×W×γ/10 ^{^8}

=2.99 × 1200 × 24 × 250 × 550/10^ ⁸wan Yuan

=118.404 ten thousand yuan

In conjunction with the cost of investment that consumption mark coal cost and the valve of estimation are transformed, determine whether to transform valve.

By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.

Claims (6)

1. the appraisal procedure that affects unit of firepower plant heating system valves leakage, is characterized in that, comprise the following steps:

Step one: gather unit condensing water temperature and saturation temperature corresponding to exhaust steam pressure, determine the degree of supercooling of condenser condensed water, and the hot-well depression angle value ψ calculating described degree of supercooling value and Condenser Design or first operation reception test in period ₀difference;

Step 2: the condensing water flow measuring Condenser's Hot Well, leaking heat in calculating;

Step 3: interior leaking heat is set as the steam heat leaked, adjusts the amount that it is converted into internal power;

Step 4: according to the amount of internal power and the ratio of generator power, and the heat consumption rate value under this internal power amount, leak the recruitment of the unit net coal consumption rate caused in calculating;

Step 5: leak days running d and mark coal price lattice γ per ton in statistics, computing economy benefit.

2. a kind of firepower plant heating system valves leakage as claimed in claim 1 appraisal procedure that unit is affected, it is characterized in that, in described step one, the defining method of the degree of supercooling ψ of condenser condensed water is specially:

ψ＝t _s-t；

Wherein, t is condensing water temperature, t _sfor the saturation temperature that exhaust steam pressure is corresponding.

3. a kind of firepower plant heating system valves leakage as claimed in claim 1 appraisal procedure that unit is affected, it is characterized in that, in described step 2, the computing method of interior leaking heat are specially:

Q1＝c·D·Δt；

Wherein, c is specific heat of water, and D is condensing water flow, Δ t=ψ-ψ ₀, be the difference of the degree of supercooling of condenser condensed water and Condenser Design or the first hot-well depression angle value of operation reception test in period.

4. the appraisal procedure that affects unit of a kind of firepower plant heating system valves leakage as claimed in claim 1, is characterized in that, in described step 3, adjusting the concrete grammar being converted into the amount of internal power is:

$W_r=\frac{Q_1}{3600};$

Wherein, Q ₁for interior leaking heat, W _rfor the amount of internal power.

5. the appraisal procedure that affects unit of a kind of firepower plant heating system valves leakage as claimed in claim 1, is characterized in that, in described step 4, the method for leaking the recruitment of the unit net coal consumption rate caused in calculating is specially:

Wherein, W _rfor the amount of internal power, W is generator power, H _tfor the heat consumption rate under this generator power, η _glfor boiler efficiency, η _gdfor pipeline efficiency, for station service power consumption rate.

6. a kind of firepower plant heating system valves leakage as claimed in claim 1 appraisal procedure that unit is affected, it is characterized in that, in described step 5, the method for computing economy benefit is specially:

x＝Δg×d×24×W×γ/10^ ⁸；

Wherein, Δ g is the recruitment of the unit net coal consumption rate that interior leakage causes, and d is interior leakage days running, and W is generator power, and γ is the price of mark coal per ton.