CN113325713B - Method for determining optimal operation mode of heat supply unit by adopting matched extraction steam external supply technology - Google Patents

Abstract

The invention discloses a method for determining the optimal operation mode of a heat supply unit by adopting a matched steam extraction external supply technology, which adopts field operation data, takes the lowest total standard coal consumption of a coal electric unit under the conditions of fixed steam supply load and power supply load as an optimization objective function, adopts a univariate comparison method, sequentially adjusts the steam pressure and the heat re-steam pressure at the exhaust position of the unit, compares the total standard coal consumption under the conditions of heat supply and power supply of the unit with a reference working condition, and if the total standard coal consumption under the conditions of heat supply and power supply of the unit is larger than the reference working condition, the original reference working condition is still used as the reference working condition; if the parameter is smaller than the preset value, taking the corresponding operation working condition of the parameter as a new comparison reference working condition, continuously adjusting the steam pressure and the hot reheat pressure at the row position in the unit, and performing next iteration optimization. The invention takes the lowest total standard coal consumption as an objective function on the premise of meeting the power grid electric load and the heat load dispatching of the steam utilization unit, and obtains the optimal control values of the steam pressure and the heat-regasification pressure at the middle exhaust position of the matched steam extraction external supply unit under the boundary conditions of different heat supply steam loads, power supply loads and the like on line.

Description

Determination method of optimal operation mode of heating unit with matching extraction steam external supply technology

technical field

The invention belongs to the field of energy saving and consumption reduction, and relates to a method for determining the optimal operation mode of a heating unit adopting a matching extraction steam external supply technology.

Background technique

At present, the main body of electric power energy is gradually changing from thermal power generation to renewable energy such as wind and wind. The function of existing thermal power is gradually transformed from the main body of power supply and electricity at the current stage to the main body of providing valuable services to the whole society: 1) Provide flexibility to the power grid Power supply, participating in power grid peak regulation and frequency regulation services, while achieving a high proportion of new energy power consumption, it also plays an important role in ensuring supply; 2) Provide low-cost, stable power supply and heating services to the society; 3) Urban Coupled consumption of sludge, solid waste and biomass.

Using high-parameter, large-capacity combined heat and power generation + central heating of the heating pipe network to replace the scattered layout, heavy pollution, and high energy consumption of coal-fired and oil-fired heating boiler rooms is a clean, low-carbon, stable and reliable solution for large and medium-sized cities. , an important way of low-cost heat demand, has developed rapidly in recent years. The demand for various forms of energy such as centralized cooling, industrial steam, and high-pressure air has also grown rapidly.

At present, the vast majority of coal-fired generating units are designed and constructed in pure condensing mode. In order to meet the heating needs of urban residents, or the steam supply needs of large enterprises or industrial parks, a small number of cogeneration units have been designed and constructed in a targeted manner. The ever-increasing demand for heat is mainly achieved by the technical transformation of existing coal-fired power units.

Residential heating and industrial steam supply are collectively referred to as central heating. The former uses water as the heat carrier to transfer the low-quality heat of the coal-fired power unit to the user, and the steam-water thermal cycle of the coal-fired power unit has no mass exchange with the heat user; the latter uses steam of a certain pressure and temperature level in the production process of the enterprise. Most of the steam condensate is not recycled. In order to maintain the steam-water quality balance of coal-fired power units, it is necessary to add demineralized water such as the amount of steam supplied to the condenser.

Residential heating and industrial steam supply, the ultimate source of heat is the extraction of steam somewhere in the steam-water thermal cycle of coal-fired power units. However, the coal-fired generating set has extracted steam for external supply through technical transformation. Typical steam sources include boiler superheater outlet, boiler reheater inlet and outlet, medium-pressure cylinder exhaust port, low-pressure cylinder exhaust port, and steam turbine return at all levels. Thermal extraction ports, etc., whose extraction parameters are characterized by discrete distribution in the distribution of pressure and temperature, and the wide-load operation of coal-fired power units under the background of flexible peak regulation of the power grid exacerbates this discrete characteristic to a certain extent. It will inevitably cause the pressure and temperature mismatch between the supply side of the heat source and the user's demand side, resulting in obvious problems of high quality, low use and energy waste.

Matching steam extraction technology can better solve this problem, and has a large number of applications in the field of industrial steam supply. Such equipment is called pressure matcher, hot press, steam jet pump, etc. Its technology is to use the high-speed steam flow generated by high-pressure steam (driving steam) through the nozzle to inhale the low-pressure steam to increase its pressure and temperature, while the pressure and temperature of the high-pressure steam are reduced, thereby improving the parameters of the low-pressure steam, especially suitable for Scenarios where the pressure demand is between main steam-high exhaust, or hot re-intermediate exhaust. Accompanying drawing 1 has given the heat supply system schematic diagram of exhaust steam extraction in heat re-steam injection.

The main performance index of the matching injection device for variable working conditions is the injection ratio, which is defined as the ratio of the flow rate of the steam supplied outside the outlet to the flow rate of the driving steam, a dimensionless number, see formula (1).

Among them, u is the injection ratio, a dimensionless number; m _t , m _h , and m _l are the outlet steam flow rate of the matching ejector device, the driving steam flow rate entering the matching ejector device, and the injected steam flow rate, respectively, in t/h.

Based on the parameters of driving steam pressure, injected steam pressure and total outlet flow of commonly used electrical load points, the matching injection device design is carried out. In the actual operation of the matching injection device applied to the industrial steam supply scene of coal-fired power units, the injection ratio u is affected by the pressure of the driving steam and the pressure of the injected steam. Related studies have shown that the injection ratio u increases with the increase of the driving steam pressure _Ph , and increases with the increase of the driven steam pressure P _l .

The matching injection device applied to the industrial steam supply scene of the coal-fired power unit, taking the steam extraction in the heat re-steam ejection described in the present invention as an example, when the coal-fired power unit is running under variable working Throttling adjustment, increasing the extraction pressure P _l of the middle row, can increase the injection ratio u, and reduce the consumption of driving steam (hot resteam) and reduce the consumption of high-quality steam under the condition of a given external steam flow rate m _t , which can reduce the total energy consumption of coal-fired power units in the scenario of dual supply of electricity and heat loads; at the same time, the low-pressure cylinder inlet steam regulating valve throttles and suppresses pressure, and the thermodynamic cycle process produces irreversible throttling losses, and the low-pressure cylinder enters The steam pressure is reduced, and the working capacity is reduced, which increases the total energy consumption of coal-fired power units in the scenario of dual supply of electricity and heat loads.

Similarly, through the throttling adjustment of the steam inlet regulating valve of the medium pressure cylinder, the hot resteam pressure P _h can be increased, the injection ratio u can be increased, and the driving steam (hot resteam) can be reduced under the condition of a given external steam flow rate m _t Consumption, high-quality steam consumption is reduced, which can reduce the total energy consumption of coal-fired power units in the scenario of dual supply of electricity and heat loads; The irreversible throttling loss is eliminated, the inlet steam pressure of the medium-pressure cylinder is reduced, and the working capacity of the medium-pressure cylinder and low-pressure cylinder is reduced, which increases the total energy consumption of the coal-fired power unit in the scenario of dual supply of electricity and heat loads.

In short, the matching injection device applied to the industrial steam supply scene of coal-fired power units, under the condition of given heating and power supply loads, there is an optimal heat resteam pressure and mid-exhaust steam pressure, so that the coal-fired power units The lowest total energy consumption is achieved under the dual variable constraints of heat and power supply.

Existing research focuses on the matching injection device itself, as well as the formulation and design optimization of the coupling between the matching injection device and the thermal system of the coal-fired power unit. Determination of the optimal operation mode under the dual-variable constraints of heat and power supply. At present, operators of coal-fired power units only rely on matching the design parameters provided by the injection device manufacturer, and then perform fuzzy operations based on personal experience. This not only involves a large amount of manual operations, but also lacks scientific guidance and deviates from the optimal operation mode.

To sum up, from the perspective of energy saving, potential reduction of operating costs and improvement of profitability in the operation of heating units that adopt matching extraction steam external supply technology, there is an urgent need for a method for determining the best operation mode with strong operability and practicality .

Contents of the invention

The purpose of the present invention is to solve the technical gap in the determination of the optimal operation mode of the existing matching injection device applied to the industrial steam supply scene of coal-fired power units under the dual variable constraints of heating and power supply, and provide a matching extraction steam extraction A method for determining the optimal operation mode of a heating unit based on technology. The present invention, under the double-variable constraints of external steam supply and power supply, aims at maximizing the profit value of the unit, and adjusts the relevant parameters of the heating unit to match the steam extraction system to realize heat supply. The unit operates in the best mode, which is suitable for heating units that adopt matching extraction steam external supply technology.

In order to achieve the above object, the present invention adopts the following technical solutions to achieve:

The method for determining the optimal operation mode of the heating unit that matches the extraction steam external supply technology includes the following steps:

Step 1, specifying the characterization parameters for matching the optimal operation mode of the extraction steam external supply unit, and establishing a profit value calculation model for matching the extraction steam external supply unit;

Step 2, according to the total steam supply load and power supply load of the boundary parameters, delineate the test working conditions;

Step 3: Guided by matching the lowest value of the total standard coal consumption value of the steam extraction external supply unit, determine the best operation mode for each test condition.

The further improvement of the present invention is:

The step 1 clearly matches the characterization parameters of the optimal operation mode of the external steam extraction unit as follows:

Under the dual-variable constraints of steam supply load m _t and power supply load N _net , the characteristic parameters for matching the optimal operation mode of the extraction external supply unit are hot resteam pressure P _h and mid-discharge steam pressure P _l .

The specific method for establishing a profit value calculation model matching the extraction steam external supply unit in step 1 is as follows:

Match the profit value M of the steam extraction external supply unit:

M=E+Q-B (2)

Among them, Q is heat supply revenue, E is power supply revenue, and B is the total consumption of standard coal;

The power supply income E is as follows:

E＝N _net ×a (3)

Among them, a is the on-grid electricity price;

The heating income Q is as follows:

Q＝ _mt ×b (4)

Among them, b is heat price;

For the steam extraction external supply unit, the main steam pressure of the boiler is adjusted according to the existing fixed-slip-fixed curve, and the main steam temperature and reheat steam temperature are adjusted according to the rated parameters. At this time, the total standard coal consumption of the unit B is the hot resteam Multivariate functions of pressure P _h , power supply load N _net , external steam supply load m _t , and mid-discharge steam pressure P _l :

Among them, h _ms , h _rh , h _ch , h _gs , h _zj and h _gj are respectively the main steam enthalpy value at the boiler superheater outlet, the boiler reheater outlet and inlet steam enthalpy value, the boiler inlet feedwater enthalpy value, the boiler reheat Desuperheating water enthalpy value of the device and superheater, kJ/kg; η _b is the thermal efficiency of the boiler:

η _b = f ₂ (D _ms ) (6)

η _p is the pipeline efficiency, take a fixed value of 0.985;

D _ms , D _rh , D _rc , D _gs , D _zj and D _gj are respectively the main steam flow at the boiler superheater outlet, the boiler reheater outlet and inlet steam flow, the boiler inlet feedwater flow, the boiler reheater and superheater deduction Warm water flow, t/h; its correlation is as follows:

Among them, D _ex1 , D _ex2 and D _leak are the 1st stage extraction steam, 2nd stage extraction steam and shaft seal leakage of high pressure cylinder respectively, t/h; where D _ex1 and D _ex2 are based on 1st stage extraction steam and 2nd stage extraction steam The corresponding high pressure heater heat balance calculations give D _leak as a unary function of D _ms :

D _leak ＝f ₃ (D _ms ) (8)

Based on formulas (6), (7) and (8), the main steam flow D _ms at the outlet of the boiler superheater is the benchmark parameter for determining the total consumption of standard coal B;

The relationship between the main steam flow rate D _ms at the outlet of the boiler superheater and the pressure P after the regulation stage of the steam turbine is as follows:

D _ms ＝c×P+d (9)

Among them, c and d are constant coefficients;

The optimization operation under the given total steam supply load m _t and power supply load N _net , matching the lowest value of the total standard coal consumption B value of the external steam extraction unit is the optimal working condition, and the corresponding hot resteam P _h and The middle exhaust steam pressure P _l is the best operation mode.

The step 2 is specifically as follows:

Statistics of unit operation data in the latest complete heating season mainly include:

Total steam supply load m _t : m _{t, min} , m _{t, max}

Power supply load N _net : N _{net, min} , N _{net, max}

According to the distribution of power supply load N _net and total steam supply load m _t , the test conditions are divided according to the following principles:

N _{net, min} , N _{net, min} + (N _{net, max} -N _{net, min} ) × 0.25

N _{net, min} + (N _{net, max} -N _{net, min} )×0.5

N _{net, min} + (N _{net, max} -N _{net, min} )×0.75

N _{net, max}

m _{t, min}

m _{t, min} +(m _{t, max} -m _{t, min} )×0.25

m _{t, min} +(m _{t, max} -m _{t, min} )×0.5

m _{t, min} +(m _{t, max} -m _{t, min} )×0.75

m _{t, max}

The best way to determine the working conditions online is a total of 5×5=25 groups.

The step 3 is specifically as follows:

3-1) Taking the minimum value of the injected steam pressure P _l0 and the minimum value of the driving steam pressure P _h0 matching the operation requirements of the injection device as the reference conditions for optimization, test the pressure P ₀ after the adjustment stage, according to the formula (5)-(9) Calculate and determine the total standard coal consumption B ₀ of the unit;

3-2) The optimization iteration of the steam extraction pressure at the middle row is performed first; the steam pressure at the exhaust of the medium pressure cylinder is adjusted by adjusting the opening of the heating butterfly valve set on the medium and low pressure connecting pipe and before the steam intake of the low pressure cylinder, and synchronously By adjusting the opening of the steam inlet regulating valve of the medium-pressure cylinder to maintain the hot re-steam pressure P _h0 in this optimization iterative process; the steam pressure at the exhaust of the medium-pressure cylinder is raised by 0.05 MPa each time, and the matching ejector is adjusted respectively. The driving steam of the device, the flow rate of the injected steam, and the evaporation of the boiler are used to maintain the steam supply load m _t and the power supply load N _net . After the main operating parameters of the unit are stable, record the operating data for 30 minutes, and take the average value. According to formula (5) -(9) Calculate and determine the total standard coal consumption B ₁ of the unit;

Compare B ₁ with B ₀ , if B ₁ ≥ B ₀ , the original reference working condition is still used as the reference working condition; if B ₁ < B ₀ , the operating condition corresponding to the steam pressure at the exhaust of the intermediate pressure cylinder is used as a new comparison For the baseline working condition, continue to raise the steam pressure at the exhaust of the medium-pressure cylinder by 0.05MPa each time, and carry out the next optimization iteration;

3-3) The extraction pressure at the middle row is raised until the maximum limit value P _l,s of the safe operation of the unit and the highest value P _l of the extraction pressure at the middle row that can be realized by the adjustment means of throttling and holding back the steam inlet regulating valve of the low pressure cylinder _{, max} , the optimization iteration of adjusting the extraction steam pressure at the middle row ends; during this process, the extraction pressure at the middle row corresponding to the lowest value of the total standard coal consumption B of the coal-fired power unit is used as a new benchmark Working condition, at this time, the extraction pressure at the middle row is P _lb , and the standard coal consumption is B _b ;

3-4) The extraction pressure value P _lb at the middle row corresponding to the lowest value of the unit’s total standard coal consumption B value in the optimization iterative process of adjusting the extraction pressure at the middle row is fixed, and the extraction pressure at the middle row is adjusted The extraction pressure at the middle row corresponding to the lowest value of the total standard coal consumption B value in the optimization iterative process is taken as the new reference condition. At this time, the extraction pressure at the middle row is P _lb , and the hot re-extraction pressure is P _h0 , standard coal consumption is B _b ;

Then perform the optimization iteration of the hot re-extraction pressure; adjust the hot re-extraction pressure by adjusting the opening of the medium-pressure cylinder inlet regulating valve, and simultaneously adjust the opening of the low-pressure cylinder inlet regulating valve to maintain the optimal iteration process The steam extraction pressure value P _lb at the middle row; raise the heat re-extraction pressure by 0.1MPa each time, and adjust the driving steam entering the matching injection device, the injected steam flow rate and the boiler evaporation respectively to maintain the steam supply Load m _t and power supply load N _net , record the operating data for 30 minutes after the main operating parameters of the unit are stable, take the average value, and calculate and determine the total standard coal consumption B ₂ of the unit according to formulas (5)-(9);

Comparing B ₂ with B _b , if B ₂ ≥ B _b , the original reference working condition is still used as the reference working condition; if B ₂ < B _b , the operating condition corresponding to the heat resteam pressure is taken as the new comparative reference working condition, Continue to increase the inlet steam pressure from the middle exhaust to the heat pump by 0.1MPa each time, and carry out the next optimization iteration;

3-5) The hot resteam pressure is raised until the lowest value between the highest limit value P _h,s of the safe operation of the unit and the highest value P _h,,max of the hot resteam pressure that can be realized by the adjustment means, through the hot resteam The optimization iteration of pressure adjustment is over; the final optimal operating condition corresponding to the lowest value of the total standard coal consumption B of the unit in this process, at this time, the hot resteam pressure is _Phb , and the steam pressure at the middle row is _Plb , Standard coal consumption is B _best ;

3-6) Complete the determination of the optimal operation mode for the remaining 24 working conditions, and obtain the optimal hot resteam and mid-exhaust steam pressures of the matching extraction external supply unit under different power supply loads N _net and total steam supply load m _t value.

It also includes step 4, the optimization result is applied to the guidance of production energy-saving potential tapping;

According to the difference of the total steam supply load m _t , the optimal operation mode under 25 working conditions is taken as the variable of the power supply load N _net , and the variation of the optimal heat resteam pressure and middle exhaust steam pressure with the power supply load N _net are respectively plotted curve;

During production and operation, according to the total steam supply load m _t and power supply load N _net , and according to the linear interpolation or extrapolation method, the maximum value of the matching external steam supply unit under different steam supply loads m _t and different power supply loads N _net is obtained. Optimum heat re-steam pressure and medium-discharge steam pressure to achieve the lowest operating cost and maximize profitability.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention adopts the on-site operation data, takes the lowest total standard coal consumption value of the unit under the condition of fixed heating load and power supply load as the optimization objective function, adopts the single variable comparison method, and obtains the matching steam extraction heating unit by adjusting the operating parameters The optimal control value of hot resteam pressure and mid-exhaust steam pressure under different boundary conditions such as steam supply load and power supply load. Compare the total standard coal consumption under the heating and power supply conditions of the unit with the reference working condition. If it is greater, the original reference working condition will still be used as the reference working condition; In this case, continue to adjust the steam pressure and heat resteam pressure at the middle row of the unit, and carry out the next iteration optimization. The present invention takes the lowest total standard coal consumption as the objective function under the premise of satisfying the double scheduling of the electrical load of the power grid and the heat load of the unit of steam consumption, and obtains on-line matching external supply units of steam extraction under different boundary conditions such as heating steam load and power supply load. Optimum control values of steam pressure and hot re-steam pressure at the mid-row to achieve lowest operating costs and maximize profitability.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is a schematic diagram of the heat supply system of the heat re-steam ejection exhaust extraction steam of the present invention.

Fig. 2 is a flow chart of the method for determining the optimal operation mode of the heating unit using the matching external steam extraction technology in the present invention.

Among them: 1-boiler, 2-high pressure cylinder, 3-medium pressure cylinder, 4-low pressure cylinder, 5-generator, 6-matching injection device, 7-medium pressure cylinder inlet steam regulating valve, 8-low pressure cylinder inlet steam regulator valve.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "horizontal", "inside" etc. is based on the orientation or positional relationship shown in the drawings , or the orientation or positional relationship that the product of the invention is usually placed in use is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation or be constructed in a specific orientation and operation, and therefore should not be construed as limiting the invention. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions, and should not be construed as indicating or implying relative importance.

In addition, when the term "horizontal" appears, it does not mean that the part is required to be absolutely horizontal, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal than "vertical", and it does not mean that the structure must be completely horizontal, but can be slightly inclined.

In the description of the embodiments of the present invention, it should also be noted that, unless otherwise specified and limited, the terms "setting", "installation", "connection" and "connection" should be interpreted in a broad sense, for example, It can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

The present invention is described in further detail below in conjunction with accompanying drawing:

Referring to the figure, the method of determining the optimal operation mode of the heating unit matching the extraction steam external supply technology includes the following steps:

Step 1: Specify the characterization parameters for matching the optimal operation mode of the extraction steam external supply unit, and establish a profit value calculation model for the matching extraction steam external supply unit.

Under the dual-variable constraints of steam supply load m _t and power supply load N _net , the characteristic parameters for matching the optimal operation mode of the extraction external supply unit are hot resteam pressure P _h and mid-discharge steam pressure P _l .

The profit value M of the matching extraction steam external supply unit is equal to the heat supply income Q + power supply income E minus the total standard coal consumption B, see formula (2).

M=E+Q-B (2)

Power supply income E is calculated according to formula (3).

E＝N _net ×a (3)

Among them, a is the on-grid electricity price.

Heat supply income is calculated according to formula (4).

Q＝ _mt ×b (4)

Among them, b is heat price.

Coal-fired power units provide external power supply and heat supply services. The power supply load N _net is dispatched in real time by the local power grid according to regional supply and demand relationships, and the steam supply load and heat users are dispatched in real time according to demand. Coal-fired power units themselves do not have independent power and heat regulation authority.

The variable of the profit value M in the optimization operation process is only the total consumption of standard coal B, so it can be considered that the working condition corresponding to the lowest value of the total consumption of standard coal B is the best working condition. is the optimal control value.

For the steam extraction external supply unit, the main steam pressure of the boiler is adjusted according to the existing fixed-slip-fixed curve, and the main steam temperature and reheat steam temperature are adjusted according to the rated parameters. At this time, the total standard coal consumption of the unit B is the hot resteam See formula (5) for the multivariate functions of pressure P _h , power supply load N _net , external steam supply load m _t , and middle exhaust steam pressure P _l .

Among them, h _ms , h _rh , h _ch , h _gs , h _zj and h _gj are respectively the main steam enthalpy value at the boiler superheater outlet, the boiler reheater outlet and inlet steam enthalpy value, the boiler inlet feedwater enthalpy value, the boiler reheat Desuperheating water enthalpy value of the device and superheater, kJ/kg. Can be calculated from on-site pressure and temperature measurements.

η _b is the thermal efficiency of the boiler, see formula (6), which is different for different units and needs to be obtained according to the special field test.

η _b = f ₂ (D _ms ) (6)

η _p is the pipeline efficiency, which can be set at 0.985.

D _ms , D _rh , D _rc , D _gs , D _zj and D _gj are respectively the main steam flow at the boiler superheater outlet, the boiler reheater outlet and inlet steam flow, the boiler inlet feedwater flow, the boiler reheater and superheater deduction Warm water flow, t/h. The above parameters are not independent, but follow a certain correlation, see formula (7).

Among them, D _ex1 , D _ex2 and D _leak are the 1st stage extraction steam, 2nd stage extraction steam and shaft seal leakage of high pressure cylinder respectively, t/h. Among them, D _ex1 and D _ex2 can be calculated according to the heat balance of the high-pressure heater corresponding to the first-stage steam extraction and the second-stage steam extraction, and D _leak is a one-variable function of D _ms , as shown in formula (8), which is given by the steam turbine manufacturer.

D _leak ＝f ₃ (D _ms ) (8)

Combining formulas (6), (7) and (8), it can be seen that the main steam flow rate D _ms at the outlet of the boiler superheater is the benchmark parameter for determining the total standard coal consumption B. However, there is currently no steam flow measurement technology that meets the accuracy requirements of engineering applications, so the main steam flow of the DCS system cannot be used as an indicator parameter of the present invention.

The relationship between the main steam flow D _ms at the outlet of the boiler superheater and the pressure P after the regulating stage of the steam turbine is shown in formula (9).

D _ms ＝c×P+d (9)

Among them, c and d are constant coefficients, which are different for different units and can be obtained through special field tests.

The measurement technology of the pressure P after the regulating stage of the steam turbine is mature, the precision is extremely high, and it fully meets the engineering requirements.

In summary, for the optimization operation under the given total steam supply load m _t and power supply load N _net , the optimal working condition is the lowest value of the total standard coal consumption B value matching the extraction external supply unit, and the corresponding heat resteam Ph _h and middle row steam pressure P _l are the best operation mode.

Step 2, according to the boundary parameters total steam supply load m _t and power supply load N _net , the test working conditions are delineated.

Statistics of unit operation data in the latest complete heating season mainly include:

Total steam supply load m _t : m _{t, min} , m _{t, max}

Power supply load N _net : N _{net, min} , N _{net, max}

According to the distribution of power supply load N _net and total steam supply load m _t , the test conditions are divided according to the following principles:

N _{net, min} , N _{net, min} + (N _{net, max} -N _{net, min} ) × 0.25

N _{net, min} + (N _{net, max} -N _{net, min} )×0.5

N _{net, min} + (N _{net, max} -N _{net, min} )×0.75

N _{net, max}

m _{t, min}

m _{t, min} +(m _{t, max} -m _{t, min} )×0.25

m _{t, min} +(m _{t, max} -m _{t, min} )×0.5

m _{t, min} +(m _{t, max} -m _{t, min} )×0.75

m _{t, max}

To sum up, according to the method for delineating optimal working conditions of the present invention, the optimal mode of online determination of working conditions totals 5×5=25 groups.

Step 3: Guided by matching the minimum value of the total standard coal consumption B value of the extraction steam external supply unit, determine the best operation mode for each test condition.

1) Match the total steam supply load m _t and power supply load N _net of the extraction steam external supply unit to match the minimum value P of the pressure of the injected steam (steam source is the steam extraction at the middle row) required for the operation of the injection device _l0 , and the lowest pressure value P _h0 of driving steam (steam source is heat re-extraction place), as the reference condition for optimization, test the pressure P ₀ after the adjustment stage, and calculate and determine the unit standard according to formulas (5)-(9) Total coal consumption B ₀ .

2) The optimization iteration of the extraction pressure at the middle row is carried out first. Adjust the steam pressure at the exhaust of the medium pressure cylinder by adjusting the opening of the heating butterfly valve set on the medium and low pressure connecting pipe before the steam intake of the low pressure cylinder. It is necessary to simultaneously adjust the opening of the steam inlet regulating valve of the medium pressure cylinder to keep the hot resteam pressure P _h0 constant during this optimization iteration process. Raise the steam pressure at the exhaust of the medium-pressure cylinder by 0.05MPa each time. At this time, the injection ratio of the matching injection device changes. It is necessary to adjust the driving steam entering the matching injection device, the flow rate of the injected steam, and the boiler evaporation. and other parameters, so as to keep the steam supply load m _t and power supply load N _net constant, record the operating data for 30 minutes after the main operating parameters of the unit are stable, take the average value, and calculate and determine the standard coal of the unit according to formulas (5)-(9) Total consumption B ₁ .

Compare B ₁ with B ₀ , if B ₁ ≥ B ₀ , the original reference working condition is still used as the reference working condition; if B ₁ < B ₀ , the operating condition corresponding to the steam pressure at the exhaust of the intermediate pressure cylinder is used as a new comparison For the baseline working condition, continue to increase the steam pressure at the exhaust of the medium-pressure cylinder by 0.05 MPa each time, and carry out the next optimization iteration.

3) The extraction pressure at the middle row is raised until the maximum limit value P _l,s of the safe operation of the unit (at this time, the exhaust temperature of the medium pressure cylinder reaches the maximum limit, which is provided by the steam turbine manufacturer) and the low pressure cylinder inlet steam regulating valve is throttled. The optimal iteration through the adjustment of the extraction pressure at the middle row ends until the lowest value between the highest value of the extraction pressure at the middle row P _l,max that can be realized by means of holding pressure adjustment. In this process, the extraction steam pressure at the middle row corresponding to the lowest value of the total standard coal consumption B of the coal-fired power unit is taken as the new reference condition. At this time, the extraction steam pressure at the middle row is P _lb , and the standard coal consumption is B _b .

4) Matching the total steam supply load m _t and power supply load N _net of the steam extraction external supply unit is given, and the lowest value of the unit’s total standard coal consumption B value corresponding to the optimal iterative process of the extraction steam pressure adjustment at the middle row The extraction pressure value P _lb at the middle row is fixed, and the extraction pressure at the middle row corresponding to the lowest value of the total standard coal consumption B value in the optimization iteration process of the adjustment of the extraction pressure at the middle row is taken as the new reference condition. At this time, the extraction pressure at the middle row is P _lb , the hot re-extraction pressure is P _h0 , and the standard coal consumption is B _b .

Then iteratively optimize the hot re-extraction pressure. The hot re-extraction pressure is adjusted by adjusting the opening of the steam inlet regulating valve of the medium pressure cylinder. During this process, the exhaust pressure of the medium pressure cylinder is affected by the change of the heat resteam pressure. In order to maintain the hot resteam pressure in this optimization iterative process to keep P _lb constant. Raise the heat re-extraction pressure by 0.1MPa each time. At this time, the injection ratio of the matching injection device changes, and the parameters such as the driving steam entering the matching injection device, the flow rate of the injected steam, and the boiler evaporation volume need to be adjusted separately. In order to keep the steam supply load m _t and power supply load N _net constant, record the operating data for 30 minutes after the main operating parameters of the unit are stable, take the average value, and calculate and determine the total standard coal consumption of the unit according to formulas (5)-(9) _B2 .

Comparing B ₂ with B _b , if B ₂ ≥ B _b , the original reference working condition is still used as the reference working condition; if B ₂ < B _b , the operating condition corresponding to the heat resteam pressure is taken as the new comparative reference working condition, Continue to increase the inlet steam pressure from the middle exhaust to the heat pump by 0.1 MPa each time, and carry out the next optimization iteration.

5) The heat resteam pressure is raised until the maximum limit value P _h,s of safe operation of the unit (at this time, the exhaust steam temperature of the high pressure cylinder reaches the maximum limit value, which is provided by the steam turbine manufacturer) and the maximum value of the heat resteam pressure that can be realized by the adjustment means The optimization iteration by thermal re-steam pressure adjustment ends at a low value between Ph _,,max . The final best operating condition corresponding to the lowest value of the total standard coal consumption B of the unit in this process, at this time, the hot resteam pressure is _{Ph hb} , the steam pressure at the middle row is P _lb , and the standard coal consumption is B _best .

6) Complete the determination of the optimal operation mode of the remaining 24 working conditions, and obtain the optimal hot resteam and mid-exhaust steam pressure values of the matching extraction steam external supply unit under different power supply loads N _net and total steam supply load m _t .

Step 4, the optimization result is applied to the production energy saving potential tap guidance.

According to the difference of the total steam supply load m _t , the optimal operation modes under the above 25 working conditions are plotted with the power supply load N _net as the variable, and the optimal heat resteam pressure and mid-discharge steam pressure are respectively plotted against the power supply load N _net Curve.

During production and operation, according to the total steam supply load m _t , power supply load N _net and other parameters, and according to the linear interpolation or extrapolation method, the technicians can obtain the matching extraction steam external supply unit at different steam supply load m _t and different power supply load N net The best hot resteam pressure and mid-discharge steam pressure value under _net , in order to achieve the lowest operating cost and maximize profitability.

If the performance of steam turbines, boilers, matching injection devices and other related equipment changes due to technical transformation or maintenance, the above operations need to be performed again to determine that the matching extraction steam external supply unit can operate under different power supply loads N _net and different steam supply loads m The optimum hot re-steam pressure and mid-discharge steam pressure value under _t .

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (4)

1. The method for determining the optimal operation mode of the heating unit matching the extraction steam external supply technology is characterized in that it includes the following steps: Step 1, specifying the characterization parameters for matching the optimal operation mode of the extraction steam external supply unit, and establishing a profit value calculation model for matching the extraction steam external supply unit; The step 1 clearly matches the characterization parameters of the optimal operation mode of the external steam extraction unit as follows: Under the dual-variable constraints of steam supply load m _t and power supply load N _net , the characterization parameters matching the optimal operation mode of the extraction external supply unit are hot resteam pressure P _h and mid-discharge steam pressure P _l ; The specific method for establishing a profit value calculation model matching the extraction steam external supply unit in step 1 is as follows: Match the profit value M of the steam extraction external supply unit: M=E+Q-B (2) Among them, Q is heat supply revenue, E is power supply revenue, and B is the total consumption of standard coal; The power supply income E is as follows: E＝N _net ×a (3) Among them, a is the on-grid electricity price; The heating income Q is as follows: Q＝ _mt ×b (4) Among them, b is heat price; For the steam extraction external supply unit, the main steam pressure of the boiler is adjusted according to the existing fixed-slip-fixed curve, and the main steam temperature and reheat steam temperature are adjusted according to the rated parameters. At this time, the total standard coal consumption of the unit B is the hot resteam Multivariate functions of pressure P _h , power supply load N _net , external steam supply load m _t , and mid-discharge steam pressure P _l :

Among them, h _ms , h _rh , h _ch , h _gs , h _zj and h _gj are respectively the main steam enthalpy value at the boiler superheater outlet, the boiler reheater outlet and inlet steam enthalpy value, the boiler inlet feedwater enthalpy value, the boiler reheat Desuperheating water enthalpy value of the device and superheater, kJ/kg; η _b is the thermal efficiency of the boiler: η _b = f ₂ (D _ms ) (6) η _p is the pipeline efficiency, take a fixed value of 0.985; D _ms , D _rh , D _rc , D _gs , D _zj and D _gj are respectively the main steam flow at the boiler superheater outlet, the boiler reheater outlet and inlet steam flow, the boiler inlet feedwater flow, the boiler reheater and superheater deduction Warm water flow, t/h; its correlation is as follows:

Among them, D _ex1 , D _ex2 and D _leak are the 1st stage extraction steam, 2nd stage extraction steam and shaft seal leakage of high pressure cylinder respectively, t/h; where D _ex1 and D _ex2 are based on 1st stage extraction steam and 2nd stage extraction steam The corresponding high pressure heater heat balance calculations give D _leak as a unary function of D _ms : D _leak ＝f ₃ (D _ms ) (8) Based on formulas (6), (7) and (8), the main steam flow D _ms at the outlet of the boiler superheater is the benchmark parameter for determining the total consumption of standard coal B; The relationship between the main steam flow rate D _ms at the outlet of the boiler superheater and the pressure P after the regulation stage of the steam turbine is as follows: D _ms ＝c×P+d (9) Among them, c and d are constant coefficients; The optimization operation under the given total steam supply load m _t and power supply load N _net , matching the lowest value of the total standard coal consumption B value of the external steam extraction unit is the optimal working condition, and the corresponding hot resteam P _h and The middle exhaust steam pressure P _l is the best operation mode; Step 2, according to the total steam supply load and power supply load of the boundary parameters, delineate the test working conditions; Step 3: Guided by matching the lowest value of the total standard coal consumption value of the steam extraction external supply unit, determine the best operation mode for each test condition. 2. The method for determining the optimal operation mode of the heating unit using the matching extraction steam external supply technology according to claim 1, characterized in that, the step 2 is specifically as follows: Statistics of unit operation data in the latest complete heating season mainly include: Total steam supply load m _t : m _{t, min} , m _{t, max} Power supply load N _net : N _{net, min} , N _{net, max} According to the distribution of power supply load N _net and total steam supply load m _t , the test conditions are divided according to the following principles: N _{net, min} , N _{net, min} + (N _{net, max} -N _{net, min} ) × 0.25 N _{net, min} + (N _{net, max} -N _{net, min} )×0.5 N _{net, min} + (N _{net, max} -N _{net, min} )×0.75 N _{net, max} m _{t, min} m _{t, min} +(m _{t, max} -m _{t, min} )×0.25 m _{t, min} +(m _{t, max} -m _{t, min} )×0.5 m _{t, min} +(m _{t, max} -m _{t, min} )×0.75 m _{t, max} The best way to determine the working conditions online is a total of 5×5=25 groups. 3. The method for determining the optimal operation mode of a heating unit using matching extraction steam external supply technology according to claim 1, characterized in that, the step 3 is specifically as follows: 3-1) Taking the minimum value of the injected steam pressure P _l0 and the minimum value of the driving steam pressure P _h0 matching the operation requirements of the injection device as the reference conditions for optimization, test the pressure P ₀ after the adjustment stage, according to the formula (5)-(9) Calculate and determine the total standard coal consumption of the unit B ₀ ; 3-2) The optimization iteration of the steam extraction pressure at the middle row is performed first; the steam pressure at the exhaust of the medium pressure cylinder is adjusted by adjusting the opening of the heating butterfly valve set on the medium and low pressure connecting pipe and before the steam intake of the low pressure cylinder, and synchronously By adjusting the opening of the steam inlet regulating valve of the medium-pressure cylinder to maintain the hot re-steam pressure P _h0 in this optimization iterative process; the steam pressure at the exhaust of the medium-pressure cylinder is raised by 0.05 MPa each time, and the matching ejector is adjusted respectively. The driving steam of the device, the flow rate of the injected steam, and the evaporation of the boiler are used to maintain the steam supply load m _t and the power supply load N _net . After the main operating parameters of the unit are stable, record the operating data for 30 minutes, and take the average value. According to formula (5) -(9) Calculate and determine the total standard coal consumption B ₁ of the unit; Compare B ₁ with B ₀ , if B ₁ ≥ B ₀ , the original reference working condition is still used as the reference working condition; if B ₁ < B ₀ , the operating condition corresponding to the steam pressure at the exhaust of the intermediate pressure cylinder is used as a new comparison For the baseline working condition, continue to raise the steam pressure at the exhaust of the medium-pressure cylinder by 0.05MPa each time, and carry out the next optimization iteration; 3-3) The extraction pressure at the middle row is raised until the maximum limit value P _l,s of the safe operation of the unit and the highest value P _l of the extraction pressure at the middle row that can be realized by the adjustment means of throttling and holding back the steam inlet regulating valve of the low pressure cylinder _{, max} , the optimization iteration of adjusting the extraction steam pressure at the middle row ends; during this process, the extraction pressure at the middle row corresponding to the lowest value of the total standard coal consumption B of the coal-fired power unit is used as a new benchmark Working condition, at this time, the extraction pressure at the middle row is P _lb , and the standard coal consumption is B _b ; 3-4) The extraction pressure value P _lb at the middle row corresponding to the lowest value of the unit’s total standard coal consumption B value in the optimization iterative process of adjusting the extraction pressure at the middle row is fixed, and the extraction pressure at the middle row is adjusted The extraction pressure at the middle row corresponding to the lowest value of the total standard coal consumption B value in the optimization iterative process is taken as the new reference condition. At this time, the extraction pressure at the middle row is P _lb , and the hot re-extraction pressure is P _h0 , standard coal consumption is B _b ; Then perform the optimization iteration of the hot re-extraction pressure; adjust the hot re-extraction pressure by adjusting the opening of the medium-pressure cylinder inlet regulating valve, and simultaneously adjust the opening of the low-pressure cylinder inlet regulating valve to maintain the optimal iteration process The steam extraction pressure value P _lb at the middle row; raise the heat re-extraction pressure by 0.1MPa each time, and adjust the driving steam entering the matching injection device, the injected steam flow rate and the boiler evaporation respectively to maintain the steam supply Load m _t and power supply load N _net , record the operating data for 30 minutes after the main operating parameters of the unit are stable, take the average value, and calculate and determine the total standard coal consumption B ₂ of the unit according to formulas (5)-(9); Comparing B ₂ with B _b , if B ₂ ≥ B _b , the original reference working condition is still used as the reference working condition; if B ₂ < B _b , the operating condition corresponding to the heat resteam pressure is taken as the new comparative reference working condition, Continue to increase the inlet steam pressure from the middle exhaust to the heat pump by 0.1MPa each time, and carry out the next optimization iteration; 3-5) The hot resteam pressure is raised until the lowest value between the highest limit value _Ph,s of safe operation of the unit and the highest value P _h,max of the hot resteam pressure achievable by the adjustment means, through the hot resteam pressure The optimization iteration of the adjustment is over; the final optimal operating condition corresponding to the lowest value of the total standard coal consumption B of the unit in this process, at this time, the hot resteam pressure is P _hb , the steam pressure at the middle row is P _lb , and the standard Coal consumption is B _best ; 3-6) Complete the determination of the optimal operation mode for the remaining 24 working conditions, and obtain the optimal hot resteam and mid-exhaust steam pressures of the matching extraction external supply unit under different power supply loads N _net and total steam supply load m _t value. 4. The method for determining the optimal operation mode of the heating unit using the matching extraction steam external supply technology according to claim 3, further comprising step 4, the optimization result is applied to the production energy-saving potential tapping guidance; According to the difference of the total steam supply load m _t , the optimal operation mode under 25 working conditions is taken as the variable of the power supply load N _net , and the changes of the optimal hot resteam pressure and middle exhaust steam pressure with the power supply load N _net are plotted respectively curve; During production and operation, according to the total steam supply load m _t and power supply load N _net , and according to the linear interpolation or extrapolation method, the maximum value of the matching external steam supply unit under different steam supply loads m _t and different power supply loads N _net is obtained. Optimum heat re-steam pressure and medium-discharge steam pressure to achieve the lowest operating cost and maximize profitability.

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