CN112418527B - Optimal coal blending ratio calculation and judgment method based on boiler side index and fuel price - Google Patents

Abstract

The invention discloses an optimal coal blending proportion calculation and judgment method based on boiler side indexes and fuel prices, which considers the actual influence of coal blending on the operation of a coal fired unit, simplifies a simple analysis method and a simple formula for a target value of the coal blending proportion by using a calculation formula of power supply coal consumption, relates the target value of the optimal coal blending proportion to the boiler efficiency, the plant power rate of equipment at the boiler side and the fuel prices, provides a specific calculation method for the target value of the coal blending proportion, and obtains a specific implementation method of the coal blending proportion based on the lowest cost target of the coal fired unit.

Description

A method for calculating and judging the optimal coal blending ratio based on boiler-side indicators and fuel prices

Technical Field

The present invention relates to the field of thermal power generation technology in the energy and power industry, and in particular to a method for calculating and judging an optimal coal blending ratio based on boiler-side indicators and fuel prices.

Background Art

Changes in coal types in coal-fired units will inevitably lead to changes in the overall efficiency of the units. At the same time, changes in fuel prices will inevitably lead to changes in power generation costs. According to the actual situation of the boiler, it is necessary to decide the optimal coal blending ratio of different coal types in order to achieve the lowest cost of the coal-fired unit while meeting boundary conditions such as safety and environmental protection.

The traditional method of determining the optimal coal blending ratio is generally determined through experiments. The test method is to measure the relevant parameters and calculate the unit boiler efficiency through different coal blending ratios under certain stable load conditions, and determine the optimal coal blending ratio with the maximum boiler efficiency as the target value. These test methods only consider the impact of boiler efficiency, but do not consider the changes in the power consumption rate of boiler equipment caused by different blending ratios, and cannot objectively evaluate the optimal coal blending ratio.

In addition, when the target value is the minimum coal consumption for power generation, the efficiency of the steam turbine needs to be considered, which makes the determination of the optimal coal blending ratio complicated. Often, factors such as the efficiency of the steam turbine and the heating supply of the unit will affect the analysis results of the optimal coal blending ratio.

At the same time, due to different fuel prices, the blending ratio with the lowest coal consumption is not the optimal coal blending ratio with the lowest cost. At the same time, changes in fuel prices bring about corresponding changes in the optimal coal blending ratio.

Therefore, a simple and accurate calculation method is needed to determine the optimal coal blending ratio.

Summary of the invention

In order to solve the current technical problem of determining the optimal coal blending ratio more objectively or simply, the purpose of the present invention is to provide a method for calculating and judging the optimal coal blending ratio based on boiler-side indicators and fuel prices, which only considers the influence of boiler efficiency and the power consumption rate of boiler-side equipment to determine the performance target values of different coal blending ratios, and at the same time considers the price of the coal blending ratio to determine the cost target value of the coal blending ratio, thereby determining the optimal coal blending ratio when the cost target value of the coal blending ratio is minimized.

In order to achieve the above object, the technical solution adopted by the present invention and the beneficial effects of the present invention are:

A method for calculating and judging the optimal coal blending ratio based on boiler-side indicators and fuel prices comprises the following steps;

Step 1:

According to the relevant standards (GB 10184 Power Plant Boiler Performance Test Procedure), the test is prepared and the coal-fired unit is selected to operate stably at a certain load and two types of coal at a coal blending ratio of x ₁ ;

Step 2:

Measure and record the relevant parameters under the coal blending ratio x ₁ , calculate the boiler efficiency and the power consumption rate of the boiler-side equipment, obtain the performance target value OPT _coal,1 and the cost target value OPT _mix,1 of the coal blending ratio under the coal blending ratio x ₁ , and obtain a set of corresponding relationships between the cost target value of the coal blending ratio and the coal blending ratio (x ₁ , OPT _min,1 );

Step 3:

Keeping other conditions unchanged, only changing the coal blending ratio _x1 to _x2 , repeating steps 1 and 2, we can obtain the cost target values and corresponding data of coal blending ratios for N groups or more ( _x1 , OPT _mix,1 ), ..., ( _xN , OPT _mix,N ), N≥3; _xN is the Nth coal blending ratio;

Step 4:

According to the corresponding data of each coal blending ratio and the cost target value OPT _mix of the coal blending ratio, the functional relationship between OPT _mix and the coal blending ratio x is obtained by using the least squares method and function fitting:

OPT _mix = f(x)

Then the coal blending ratio x corresponding to the minimum value of OPT _mix in the above formula is the optimal coal blending ratio;

Step 5:

For the coal blending ratio under other load conditions, it is only necessary to adjust the load of the coal-fired unit and repeat steps 1-4 to obtain the optimal coal blending ratio under any other coal-fired unit load conditions.

The calculation formula of the performance target value OPT _coal,1 under the condition of coal blending ratio x ₁ in step 2 is as follows:

OPT _coal,1 = η _gl,1 (1-η _cyd,gl,1 )

Where, OPT _coal,1 is the performance target value under the condition of coal blending ratio x ₁ , -;

η _gl,1 —— boiler efficiency under the condition of coal blending ratio x ₁ , -;

η _cyd,gl,1 ——power consumption rate of boiler side equipment under the condition of coal blending ratio x ₁ , -.

The boiler efficiency can be calculated with reference to GB 10184 "Test Procedure for Performance of Power Plant Boilers". The main power-consuming equipment on the boiler side are coal mill, coal feeder, blower, induced draft fan, etc. The ratio of the sum of the power of these equipment to the generating power of the unit is the plant power consumption rate of the boiler side equipment.

At the same time, the coal price P _mix,1 under the condition of coal blending ratio x ₁ is calculated as follows:

Where, P _mix,1 is the price of blended coal under the condition of blending ratio x ₁ , RMB/t standard coal;

P _i ——standard coal price of the i-th blended coal, yuan/t standard coal;

B _cp,i,1 ——the amount of the i-th blended coal under the condition of coal blending ratio x ₁ , tons;

Qi _,ar,dw —— received basic calorific value of the i-th blended coal, kJ/kg;

The cost target value of the coal blending ratio under the condition of coal blending ratio x ₁ can be calculated as:

Beneficial effects of the present invention:

The present invention takes into account the actual impact of coal blending on the operation of coal-fired units, and uses the calculation formula of power supply coal consumption to simplify the simple analysis method and formula of the target value of the coal blending ratio, so that the evaluation of the optimal coal blending ratio is more accurate and objective. Through this method, the traditional optimal coal blending ratio evaluation method can be improved and simple to use, so that the optimal coal blending ratio analysis result truly reflects the impact on the cost of coal-fired units.

DETAILED DESCRIPTION

The present invention is further described in detail below in conjunction with embodiments.

Example:

The specific derivation process of a method for calculating and judging the optimal coal blending ratio based on boiler-side indicators and fuel prices is introduced as follows.

The lowest power supply cost of coal-fired units is the cost target value of the coal blending ratio, and its basic formula is:

OPT _mix = P _mix b _gd ×10 ^-6

Where, OPT _mix is the target cost value of the coal blending ratio, RMB/kWh;

P _mix —— coal blending price, yuan/t (standard coal);

b _gd ——coal consumption of power supply of the unit, g (standard coal)/kWh.

The formula for calculating the price of blended coal is:

Where, _Pmix is the price of blended coal for blending, RMB/t standard coal;

P _i ——standard coal price of the i-th blended coal, yuan/t standard coal;

B _cp,i ——the blending amount of the i-th blending coal, tons;

Qi _,ar,dw —— received basic calorific value of the ith blended coal, kJ/kg.

The calculation formula for coal consumption of coal-fired units is as follows:

Where, b _gd —— coal consumption of power supply of the unit, g (standard coal)/kWh;

HR——heat consumption of steam turbine, kJ/kWh;

η _gl —— boiler efficiency, -;

η _cyd —— power consumption rate of the unit, -;

η _gd —— pipeline efficiency, -;

η _dj -unit generator efficiency, -.

Since only the effect of the coal blending ratio on boiler efficiency and the power consumption rate of boiler-side equipment is considered, the calculation formula for the target coal consumption value of the unit based on the coal blending ratio is simplified to:

OPT _coal = η _gl (1-η _{cyd, gl} - _{η cyd, qt} )

Where, OPT _coal is the performance target value of the coal blending ratio, -;

η _cyd,gl —— auxiliary power consumption rate of boiler side equipment, -;

η _cyd,qt —— power consumption rate of equipment other than boilers, -;

The power consumption rate of the unit is 0.03-0.05, and the power consumption rate of the boiler side equipment is 0.02-0.04. It can be assumed that:

1- _ηcyd,qt ≈1

The performance target value of coal blending ratio OPT _coal can be further simplified as:

OPT _coal = η _gl (1-η _{cyd, g1} )

In this way, the cost target value of the coal blending ratio is simplified to:

That is, the minimum value of OPT _mix is the optimal coal blending ratio.

The specific implementation steps are as follows;

Step 1:

According to the relevant standards (GB 10184 Power Plant Boiler Performance Test Procedure), the test is prepared and the coal-fired unit is selected to operate stably at a certain load and two types of coal at a coal blending ratio of x ₁ ;

Step 2:

Measure and record relevant parameters under the coal blending ratio x ₁ , calculate boiler efficiency and plant power consumption rate of boiler-side equipment, obtain performance target value OPT _{coal, 1} and cost target value OPT _{mix, 1} of the coal blending ratio under the coal blending ratio x ₁ , and obtain a set of corresponding relationships between the cost target value of the coal blending ratio and the coal blending ratio (x ₁ , OPT _{mix, 1} ).

The calculation formula for the performance target value OPT _coal,1 under the condition of coal blending ratio x ₁ is as follows:

OPT _coal,1 =eta _gl,1 (1-eta _cyd,gl,1 )

Where, OPT _{coal, 1} is the performance target value under the condition of coal blending ratio x ₁ , -;

η _gl,1 —— boiler efficiency under the condition of coal blending ratio x ₁ , -;

η _cyd,gl,1 ——power consumption rate of boiler side equipment under the condition of coal blending ratio x ₁ , -.

The boiler efficiency can be calculated with reference to GB 10184 "Test Procedure for Performance of Power Plant Boilers". The main power-consuming equipment on the boiler side are coal mill, coal feeder, blower, induced draft fan, etc. The ratio of the sum of the power of these equipment to the generating power of the unit is the plant power consumption rate of the boiler side equipment.

At the same time, the coal price P _mix,1 under the condition of coal blending ratio x ₁ is calculated as follows:

Where, P _mix,1 is the price of blended coal under the condition of blending ratio x ₁ , RMB/t standard coal;

P _i ——standard coal price of the i-th blended coal, yuan/t standard coal;

B _cp,i,1 ——the amount of the i-th blended coal under the condition of the blending ratio x ₁ , tons;

Qi _,ar,dw —— received basic calorific value of the ith blended coal, kJ/kg.

The cost target value of the coal blending ratio under the condition of coal blending ratio x ₁ can be calculated as:

Step 3:

Keeping other conditions unchanged, only changing the coal blending ratio _x1 to _x2 , repeating steps 1 and 2, we can obtain the cost target values of more than N groups of coal blending ratios and the corresponding data of the coal blending ratios ( _x1 , OPT _{mix, 1} ), ..., ( _xN , OPT _{mix, N} ), N≥3; _xN is the Nth coal blending ratio.

Step 4:

According to the corresponding data of each coal blending ratio and the cost target value OPT _mix of the coal blending ratio, the functional relationship between OPT _mix and the coal blending ratio x is obtained by using the least squares method and function fitting:

OPT _mix = f(x)

The coal blending ratio x corresponding to the minimum value of OPT _mix in the above formula is the optimal coal blending ratio.

Step 5:

For the coal blending ratio under other load conditions, it is only necessary to adjust the load of the coal-fired unit and repeat steps 1-4 to obtain the optimal coal blending ratio under any other coal-fired unit load conditions.

Claims (1)

1. A method for calculating and judging the optimal coal blending ratio based on boiler-side indicators and fuel prices, characterized in that it includes the following steps; Step 1: Prepare the test with reference to the relevant standard "GB 10184 Power Plant Boiler Performance Test Procedure", select the coal-fired unit under a certain load, and operate stably with two kinds of coal blended at a coal blending ratio of x ₁ ; Step 2: Measure and record the relevant parameters under the coal blending ratio x ₁ , calculate the boiler efficiency and the power consumption rate of the boiler-side equipment, obtain the performance target value OPT _{coal, 1} and the cost target value OPT _{mix, 1} of the coal blending ratio under the coal blending ratio x ₁ , and obtain a set of corresponding relationships between the cost target value of the coal blending ratio and the coal blending ratio (x ₁ , OPT _{mix, 1} ); Step 3: Keeping other conditions unchanged, only changing the coal blending ratio _x1 to _x2 , repeating steps 1 and 2, obtaining the cost target values and corresponding data of coal blending ratios for N groups or more ( _x1 , OPT _{Mix, 1} ), ..., ( _xN , OPT _{mix, N} ), N≥3; _xN is the Nth coal blending ratio; Step 4: According to the corresponding data of each coal blending ratio and the cost target value OPT _mix of the coal blending ratio, the functional relationship between OPT _mix and the coal blending ratio x is obtained by using the least squares method and function fitting method: OPT _mix = f(x) Then the coal blending ratio x corresponding to the minimum value of OPT _mix in the above formula is the optimal coal blending ratio; Step 5: For the coal blending ratio under other load conditions, it is only necessary to adjust the load of the coal-fired unit and repeat steps 1-4 to obtain the optimal coal blending ratio under any other coal-fired unit load conditions; The calculation formula of the performance target value OPT _coal,1 under the condition of coal blending ratio x ₁ in step 2 is as follows: OPT _coal,1 =eta _gl,1 (1-eta _cyd,gl,1 ) Where, OPT _coal,1 is the performance target value under the condition of coal blending ratio x ₁ ; η _gl,1 —— boiler efficiency under the condition of coal blending ratio x ₁ ; η _cyd,gl,1 ——power consumption rate of boiler side equipment under the condition of coal blending ratio x ₁ ; The boiler efficiency can be calculated with reference to GB 10184 Power Plant Boiler Performance Test Procedure. The power consumption equipment on the boiler side includes coal mill, coal feeder, blower and induced draft fan. The ratio of the sum of the power of these equipment to the generating power of the unit is the power consumption rate of the boiler side equipment. At the same time, the coal price P _mix,1 under the condition of coal blending ratio x ₁ is calculated as follows:

Where, P _mix,1 is the price of blended coal under the condition of blending ratio x ₁ , RMB/t standard coal; P _i ——standard coal price of the i-th blended coal, yuan/t standard coal; B _cp,i,1 ——the amount of the i-th blended coal under the condition of the blending ratio x ₁ , tons; Qi _,ar,dw —— received basic calorific value of the i-th blended coal, kJ/kg; The cost target value of the coal blending ratio under the condition of coal blending ratio x ₁ can be calculated as: