CN103697958B - The real time measure method of coal unit drum outlet saturation steam mass rate - Google Patents

Abstract

The present invention provides the real time measure method of a kind of coal unit drum outlet saturation steam mass rate, and step comprises: step 1: according to boiler operatiopn design discipline, sets up over-temperature channel structural parameter database; Step 2: according to the working medium physical parameter storehouse of covering full working scope, in conjunction with on-the-spot plant level supervisory information system server info, real-time calculating current time k over-temperature channel is interior, drum exports and the physical parameter of high pressure cylinder ingress working medium; Step 3: set up over-temperature channel working medium mass budget model, in conjunction with the main steam mass flow calculation drum outlet saturation steam mass rate D of record in plant level supervisory information system server_bh. The present invention can be used for the on-line metering of drum outlet saturation steam mass rate, moreover it can be used to furnace outlet flue gas energy and the real-time combustion power On-line Estimation of boiler.

Description

The real time measure method of coal unit drum outlet saturation steam mass rate

Technical field

The present invention relates to technical field of power generation, specifically, it relates to the real time measure method of a kind of coal unit drum based on working medium mass balance in over-temperature channel outlet saturation steam mass rate.

Background technology

Most of subcritical coal unit drum outlet saturation steam mass rate without direct measuring apparatus, but the pressure-measuring-point by governing stage before and after high pressure cylinder, obtain pressure reduction before and after governing stage, main steam mass rate is obtained after third party's computed in software, then the saturation steam mass rate being directly equivalent to drum outlet, is uploaded to monitoring interface after on-the-spot plant level supervisory information system server record.

But, in coal unit, the saturation steam mass rate of drum outlet and the main steam mass rate of high pressure cylinder entrance have bigger deviation. Major cause connects drum outlet and the over-temperature channel of high pressure cylinder entrance is that a volume is big, the middle-chain of complex structure and operation operating mode frequent variations, the change that the kinetic characteristic of this middle-chain directly results in drum outlet saturation steam mass rate lags behind the change that high pressure cylinder entrance goes out main steam mass rate in time domain, for example, for 300MW unit, this retardation time is about 1-2 minute, and in load alternation process, due to the impact of over-temperature channel interchanger and drum air-capacitor, dynamicdeviation is also bigger. In fact, the real-time calculating lacking drum outlet saturation steam mass rate can directly affect boiler side control (such as drum three blunt quantity control) quality.

The retrieval of prior art is found, Chinese Patent Application No. 201210360382.X, publication date 2012-12-26, describe the flexible measurement method of a kind of high pressure cylinder entrance main steam mass rate, the method is based on Bei Nuli energy conservation equation, utilize first stage pressure measuring point before and after high pressure cylinder, calculate the mass rate of main steam in real time; The calculating of main steam flow when but this technology is only applicable to steady state load, and to be defaulted as known, but actual production process often can only obtain the pressure and temperature of working medium, it does not have density measurement.

Summary of the invention

For defect of the prior art, it is an object of the invention to provide the real time measure method of a kind of coal unit drum based on working medium mass balance in over-temperature channel outlet saturation steam mass rate, the method considers the kinetic characteristic of working medium quality change in over-temperature channel interchanger, based on working medium physical parameter database and boiler side key equipment structural parameter database (specifically referring to over-temperature channel structural database in the present invention), the velocity of variation of working medium quality in real-time calculated passage of heat interchanger; Finally accurately measure drum outlet saturation steam mass rate based on this velocity of variation and high pressure cylinder ingress main steam mass rate measuring point.

For realizing above object, the present invention provides the real time measure method of a kind of coal unit drum outlet saturation steam mass rate, and the method concrete steps comprise:

Step 1: according to boiler operatiopn design discipline, set up over-temperature channel structural parameter database: described over-temperature channel structural parameter database comprises following information: over-temperature channel pipeline is along the total length L in Working fluid flow direction, and total length L is divided into the long short tubes such as n section; Over-temperature channel along Working fluid flow direction heat transfer tube sectional area distribution A (i), i.e. the sectional area of i-th section of short tube; The drum pressure p inscribed when reading this from plant level supervisory information system server real-time data base_qb, superheated vapour pressure p_gr, superheat steam temperature T_gr, superheated vapour mass rate D_gr, the working medium temperature at all measuring point places and pressure in over-temperature channel;

Step 2: according to the working medium physical parameter database that can cover full operation operating mode, the working medium state parameter uploaded in conjunction with on-the-spot plant level supervisory information system server and temperature, pressure, calculate current time k in real time, drum outlet saturated-steam temperature T_qb, over-temperature channel each section of short tube working medium temperature T_gz(i) and pressure p_gz(i), interchanger at different levels working medium density p everywhere_gz(i);

Step 3: set up the working medium mass change in the over-temperature channel calculated passage of heat of working medium mass budget model, and combine the superheated vapour mass rate D obtained by measuring point_gr, calculate drum exit saturation steam mass rate D in real time_bh;

With moment t₀For timing starting point, it may also be useful to the real-time computing technique of drum outlet saturation steam mass rate, take time order and function as sequence, determine t respectively₀��t₀+��t��t₀+2��t��������t₀Corresponding saturation steam mass rate D under+n �� t_bh(t₀)��D_bh(t₀+��t)��D_bh(t₀+2��t)��������D_bh(t₀+ n �� t), and draw D_bhThe trend curve changed in time.

Preferably, in step 2, described over-temperature channel each section of short tube working medium temperature T_gz(i) pressure p_gzI () is by the temperature T at over-temperature channel (taking drum outlet as starting point, high pressure cylinder entrance is terminal) interior working medium measuring point place_gzAnd pressure p_gzLinearly calculate acquisition.

Preferably, in step 2, described interchanger at different levels working medium density p everywhere_gzI () is by current time k each section of working medium temperature T_gz(i) and pressure p_gzI () calculates and obtains.

Preferably, in step 3, described over-temperature channel working medium mass budget model is specially:

$\frac{\mathrm{dM}}{\mathrm{dt}}=D_{\mathrm{bh}}-D_{\mathrm{gr}}$

$\frac{\mathrm{dM}}{\mathrm{dt}}\stackrel{\·}{=}M\left(k\right)-M(k-1)=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ρ}}_{\mathrm{gz}}{\left(i\right)}^{\left(k\right)}A\left(i\right)\·0.1-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ρ}}_{\mathrm{gz}}{\left(i\right)}^{(k-1)}A\left(i\right)\·0.1$

$D_{\mathrm{bh}}=\frac{\mathrm{dM}}{\mathrm{dt}}+D_{\mathrm{gr}}$

In formula:

K is current time;

K-1 is a front sampling instant;

M accumulates working medium total mass in superheater system;

D_bhWorking medium quality and drum saturation steam flow is inputted for superheater system;

D_grWorking medium quality and main steam flow is exported for superheater system;

��_gz(i)^(k)For current time k, the density of working medium in i-th section of interchanger short tube;

��_gz(i)^(k-1)For a upper sampling instant k-1, the density of working medium in i-th section of interchanger short tube;

A (i) is the sectional area of i-th section of interchanger short tube;

Dt is the differential of time.

The present invention can be used for the on-line metering of coal unit drum outlet saturation steam mass rate, if being aided with suitable model to measure other heat-exchange equipments further as crossed the heat absorption amount of the passage of heat, economizer heat absorption amount and air preheater heat exchange models etc. again, then it can also be used for furnace outlet flue gas energy and the real-time combustion power On-line Estimation of boiler.

Compared with prior art, the present invention has following useful effect:

Compared with the conventional direct method going out main steam flow replacement drum outlet saturation steam flow with high pressure cylinder entrance, this method give the hard measurement value in the drum outlet saturation steam mass rate met in over-temperature channel under working medium mass conservation relation, compare original scheme more accurate. In the saturation steam mass flow measurement in each moment, all working medium in over-temperature channel interchanger and high pressure cylinder entrance main steam measuring point information unification are got up, the saturation steam mass rate inscribed when obtaining corresponding. At subsequent time, can measuring saturation steam mass rate based on same mass conservation relation, the difference of it and previous moment saturation steam mass rate can reflect that drum outlet saturation steam mass rate is measured over time truly, accurately. As a kind of flexible measurement method, measuring point data needed for saturation steam mass rate all directly reads from plant level supervisory information system server real-time data base, scene does not need the instrument additionally increasing measuring point, probe or costliness, only need to increasing corresponding software module in existing Controlling System, cost is low. The hard measurement of saturation steam mass rate is that iteration carries out, and only needs to preserve the result of a upper sampling instant (i.e. k-1 moment) in iteration, and EMS memory occupation is few, real-time. Simultaneously, by the working medium physical parameter database that can cover full working scope, the method can accurately follow the tracks of the change of saturation steam mass rate when different operating mode and load, the foundation of device structure parameter database then makes the method can be generalized in the different boiler controller system Controlling System of other device structures very easily, it is used to guide burning adjustment and the optimal control of boiler, improving whole unit performance further, expanded application scope is wide.

Accompanying drawing explanation

By reading with reference to the detailed description that non-limiting example is done by the following drawings, the other features, objects and advantages of the present invention will become more obvious:

Fig. 1 is boiler flue heat-exchange device distribution schematic diagram;

Fig. 2 over-temperature channel working medium actual internal area distributes;

Fig. 3 working medium physical parameter database exports;

Fig. 4 drum outlet saturation steam mass rate hard measurement value change curve in time.

Embodiment

Below in conjunction with specific embodiment, the present invention is described in detail. The technician contributing to this area is understood the present invention by following examples further, but does not limit the present invention in any form. It should be appreciated that to those skilled in the art, without departing from the inventive concept of the premise, it is also possible to make some distortion and improvement. These all belong to protection scope of the present invention.

As shown in Figure 1, for certain 300MW coal unit, this natural circulation boiler model is HG-1025/17.3-WM18 type, and boiler is subcritical, natural circulation, resuperheat, " W " flame mode, two arch list burner hearth, balanced ventilation, afterbody twin flue, gas baffle temperature adjustment, dry ash extraction, outdoor layout, an all steel frame suspending drum boiler.

The present embodiment provides the real time measure method of a kind of coal unit drum based on working medium mass balance in over-temperature channel outlet saturation steam mass rate, and concrete steps comprise:

Step 1: according to boiler operatiopn code, sets up main apparatus structure parameter database, and this database comprises following fixing parameter information:

Superheater pipeline is along Working fluid flow direction as shown in the solid line direction of arrow in Fig. 1, and its overall length is 396.7m, and total length L is divided into 3967 sections waited long short tube, and namely every section of stub length is set as 0.1 meter;

Interchanger along Working fluid flow direction heat transfer tube sectional area distribution A (i), i.e. the sectional area of i-th section of short tube, each major equipment sectional area A (i) distribute as shown in Figure 2;

Relevant real time data is read, as, under the operation condition of current time k, main real time data is as follows from plant level supervisory information system server real-time data base:

Drum pressure 17.6MPa, high pressure cylinder entrance go out main steam flow 233.6kg/s, superheater at different levels each section of short tube working medium temperature (first 387.9 DEG C of superheater one-level desuperheater, after superheater one-level desuperheater 379.1 DEG C, first 472.9 DEG C of superheater two grades of desuperheaters, after superheater two grades of desuperheaters 472.0 DEG C, superheater outlet is 538.7 DEG C) and pressure (superheater entrance is 17.459MPa, and superheater outlet is 16.605MPa).

Step 2: according to the working medium physical parameter database (Output rusults is as shown in Figure 3) that can cover all operation operating modes, in conjunction with the working medium state parameter (temperature, pressure) that on-the-spot plant level supervisory information system server is uploaded, calculate moment k drum outlet saturated-steam temperature T in real time_qb(by current time k drum pressure p_qbCalculate obtain), over-temperature channel each section of short tube working medium temperature T_gz(i) and pressure p_gzI () is (by the temperature T of measuring point in over-temperature channel_gzAnd pressure p_gzLinearly calculate acquisition), interchanger at different levels working medium density p everywhere_gzI () is (by current time k each section of working medium temperature T_gz(i) and pressure p_gzI () calculates and obtains).

Described working medium physical parameter database, refer to according to water and steam thermodynamic properties industry formula (IAPWS-IF97) develop have can parallel calling, region automatically differentiate, the feature such as batch processing computing for the working medium physical parameter database in line computation, can reference: Wang Xuhui, Yu Tong, Hui Zhaoyu, Yuan Jingqi, for the working medium physical parameter database of thermoelectricity gamut emulation, control engineering, 2011; 18:131-133.

Step 3: set up the working medium mass change in the over-temperature channel calculated passage of heat of working medium mass budget model, obtains superheated vapour mass rate D in conjunction with by measuring point_gr, calculate drum exit saturation steam mass rate D in real time_bh;

The present embodiment chooses timed interval �� t=5s, calculates t=t₀For drum outlet saturation steam mass rate in 24 hours of timing starting point, namely at moment t=t₀��t=t₀+5��t=t₀+10��������t=t₀+ 86400, respectively repeat steps 1-3, obtain corresponding drum outlet saturation steam mass rate hard measurement value D_bh(t₀)��D_bh(t₀+5)��D_bh(t₀+10)��������D_bh(t₀+ 86400); Change curve is as shown in Figure 4 in time for drum outlet saturation steam mass rate hard measurement value.

In the present embodiment step 3, described over-temperature channel working medium mass budget model is

$\frac{\mathrm{dM}}{\mathrm{dt}}=D_{\mathrm{bh}}-D_{\mathrm{gr}}$

$\frac{\mathrm{dM}}{\mathrm{dt}}\stackrel{\·}{=}M\left(k\right)-M(k-1)=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ρ}}_{\mathrm{gz}}{\left(i\right)}^{\left(k\right)}A\left(i\right)\·0.1-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ρ}}_{\mathrm{gz}}{\left(i\right)}^{(k-1)}A\left(i\right)\·0.1$

$D_{\mathrm{bh}}=\frac{\mathrm{dM}}{\mathrm{dt}}+D_{\mathrm{gr}}$

In formula,

K is current time;

K-1 is the moment of a front sampling;

M accumulates working medium total mass in superheater system;

D_bhFor superheater system inputs working medium quality (i.e. drum saturation steam mass rate);

D_grFor superheater system exports working medium quality (i.e. main steam mass rate);

��_gz(i)^(k)For current time k, the density of working medium in i-th section of interchanger short tube;

��_gz(i)^(k-1)For a upper sampling instant k-1, the density of working medium in i-th section of interchanger short tube;

A (i) is the sectional area of i-th section of interchanger short tube;

Dt is the differential of time.

The present invention can be used for the on-line metering of coal unit drum outlet saturation steam mass rate, and its measuring result can directly apply in drum feedwater three blunt quantity control the correction exporting saturation steam mass rate. If being aided with suitable model to measure other heat-exchange equipments further as crossed the heat absorption amount of the passage of heat, economizer heat absorption amount and air preheater heat exchange models etc. again, then it can also be used for furnace outlet flue gas energy and the real-time combustion power On-line Estimation of boiler.

Above specific embodiments of the invention are described. It is understood that the present invention is not limited to above-mentioned particular implementation, those skilled in the art can make various distortion or amendment within the scope of the claims, and this does not affect the flesh and blood of the present invention.

Claims (3)

1. the real time measure method of a coal unit drum outlet saturation steam mass rate, it is characterised in that, the method concrete steps comprise:

Step 1: according to boiler operatiopn design discipline, sets up over-temperature channel structural parameter database; Described over-temperature channel structural parameter database comprises following information: over-temperature channel pipeline is along the total length L in Working fluid flow direction, and total length L is divided into the long short tubes such as n section; Over-temperature channel along Working fluid flow direction heat transfer tube sectional area distribution A (i), i.e. the sectional area of i-th section of short tube; The drum pressure p inscribed when reading this from plant level supervisory information system server real-time data base_qb, superheated vapour pressure p_gr, superheat steam temperature T_gr, superheated vapour mass rate D_gr;

Step 2: according to the working medium physical parameter database covering full operation operating mode, the working medium state parameter uploaded in conjunction with on-the-spot plant level supervisory information system server and temperature, pressure, calculate current time k in real time, drum outlet saturated-steam temperature T_qb, over-temperature channel each section of short tube working medium temperature T_gz(i) and pressure p_gz(i), interchanger at different levels working medium density p everywhere_gz(i);

Step 3: set up the working medium mass change in the over-temperature channel calculated passage of heat of working medium mass budget model, and combine the superheated vapour mass rate D obtained by measuring point_gr, calculate drum exit saturation steam mass rate D in real time_bh;

With moment t₀For timing starting point, it may also be useful to the real-time computing technique of drum outlet saturation steam mass rate, take time order and function as sequence, calculate t respectively₀��t₀+��t��t₀+2��t��������t₀Corresponding saturation steam mass rate D under+n �� t_bh(t₀)��D_bh(t₀+��t)��D_bh(t₀+2��t)��������D_bh(t₀+ n �� t), and draw D_bhThe trend curve changed in time;

In step 3, described over-temperature channel working medium mass budget model is specially:

$\frac{\mathrm{dM}}{\mathrm{dt}}=D_{\mathrm{bh}}-D_{\mathrm{gr}}$

$\frac{\mathrm{dM}}{\mathrm{dt}}\stackrel{\·}{=}M\left(k\right)-M(k-1)=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ρ}}_{\mathrm{gz}}{\left(i\right)}^{\left(k\right)}A\left(i\right)\·0.1-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ρ}}_{\mathrm{gz}}{\left(i\right)}^{(k-1)}A\left(i\right)\·0.1$

$D_{\mathrm{bh}}=\frac{\mathrm{dM}}{\mathrm{dt}}+D_{\mathrm{gr}}$

In formula: k is current time;

K-1 is a upper sampling instant;

M accumulates working medium total mass in superheater system;

D_bhWorking medium quality and drum saturation steam mass rate is inputted for superheater system;

D_grWorking medium quality and main steam mass rate is exported for superheater system;

��_gz(i)^(k)For current time k, the density of working medium in i-th section of interchanger short tube;

��_gz(i)^(k-1)For a upper sampling instant k-1, the density of working medium in i-th section of interchanger short tube;

A (i) is the sectional area of i-th section of interchanger short tube;

Dt is the differential of time.

2. the real time measure method of coal unit drum according to claim 1 outlet saturation steam mass rate, it is characterised in that, in step 2, described working medium physical parameter database is set up by IF97 formula.

3. the real time measure method of coal unit drum according to claim 1 and 2 outlet saturation steam mass rate, it is characterised in that, in step 2, described over-temperature channel each section of short tube power pressure p_gzI () is by the temperature T of measuring point in over-temperature channel_gzAnd pressure p_gzLinearly calculate acquisition.