CN114054191A - Coal mill pulverized coal optimal fineness evaluation method based on cost change - Google Patents

Abstract

The invention discloses a coal mill coal dust optimal fineness evaluation method based on cost change, which specifically considers evaluation of a coal marking unit price and an online electricity price on coal mill coal dust optimal fineness through the influence of coal dust fineness on the power consumption rate of a coal mill and mechanical incomplete combustion loss. The coal mill coal powder fineness evaluation method based on cost change is more complete, objective and simple in economic aspect, economic evaluation of coal mill coal powder fineness can be quickly and simply given according to changes of standard coal consumption for power generation and plant power consumption, and economic benefit is obvious.

Description

Coal mill pulverized coal optimal fineness evaluation method based on cost change

Technical Field

The invention relates to the technical field of thermal power generation in the energy and power industry, in particular to a coal mill coal powder optimal fineness evaluation method based on cost change.

Background

Energy conservation, consumption reduction, quality improvement and efficiency improvement of a thermal power plant are main targets of operation optimization of the power plant. The fineness of the coal powder at the outlet of the coal mill is a control index for optimizing operation, the fineness of the coal powder is reduced, the combustible substance of fly ash is reduced, the incomplete combustion loss of machinery is reduced, but the plant power consumption rate is increased; on the contrary, the fineness of the pulverized coal is increased, the combustible substance of the fly ash is increased, the incomplete combustion loss of the machine is increased, and the plant power consumption rate is reduced. There is a target value corresponding to the optimal coal powder fineness, and the corresponding incomplete combustion loss of machinery and the plant power rate reach certain values. In the traditional method, the lowest coal consumption of unit degree electricity is often used as an evaluation target to determine the optimal coal powder fineness. However, for the unit which is actually operated, the coal burning quantity can be reduced due to incomplete mechanical combustion, the power plant consumption rate can be increased to reduce the on-grid electricity quantity, the price of the coal burning and the on-grid electricity is different, the optimal coal powder fineness is determined according to the cost change of unit electricity, and the economic benefit of a power plant is maximized.

Disclosure of Invention

In order to overcome the defects of the prior art, the optimal fineness evaluation method of the coal powder of the coal mill based on cost change is provided from the aspect of optimal economy, and the difference between the price of marked coal and the price of on-grid electricity is considered from the aspects of the power consumption rate of the coal mill and the mechanical incomplete combustion loss index of the coal mill, so that guidance is provided for the optimal operation of the coal mill.

In order to achieve the purpose, the invention adopts the technical scheme that:

a coal mill coal powder optimal fineness evaluation method based on cost variation comprises the following steps;

step 1:

the fineness d of the coal dust at the outlet of the separator of the coal mill before the operation adjustment of the coal mill needs to be obtained through statistics or according to related technical standard tests_90,1Coal mill motor power consumption rate eta_cyd,1Fly ash combustible material C_fh,1According to GB/T10184 according to fly ash combustible C_fh,1Can calculate incomplete combustion loss q of machinery_4,1；

Step 2:

obtaining the coal powder fineness d of the power consumption rate of the coal mill after the adjustment of the coal mill_90,2Coal mill motor power consumption rate eta_cyd,2Fly ash combustible C_fh,2Also according to GB/T10184 according to fly ash combustible C_fh,2Can calculate incomplete combustion loss q of machinery_4,2；

And step 3:

marking coal price P_coalAnd the price of power P_swThe cost change Δ C per unit of electricity is calculated by substituting the following equation_cb：

ΔC_cb,2＝P_sw(η_cyd,2-η_cyd,1)+P_coalb_fd(q_4,2-q_4,1)

In the formula,. DELTA.C_cb,2-cost variation after coal mill adjustment, yuan/MWh;

P_sw-the power price of the thermal power generating unit on the internet, yuan/MWh;

η_cyd,2-the power consumption of the coal mill after adjustment of the coal mill, -;

η_cyd,1-coal mill power consumption before coal mill adjustment, -;

P_coalthe price of the standard coal, yuan/kg (standard coal);

b_fdpower generation standard coal consumption, kg (standard coal)/MWh;

q_4,2-loss of incomplete combustion of machinery after adjustment of the coal mill, -;

q_4,1-mechanical incomplete combustion losses before coal mill adjustment, -;

if the unit profit changes C_cb,2Less than or equal to 0, the yield of the thermal power generating unit is positive, the economical efficiency after the coal mill is adjusted is feasible, and the fineness d of the pulverized coal is_90,2Ratio d_90,1The better is;

from the above formula, because the difference exists between the power price of the thermal power generating unit on the internet and the power generation standard coal consumption, the following requirements are met under the general condition:

P_sw>P_coalb_fd

therefore, after the coal mill is adjusted, the same change of the power consumption rate of the coal mill and the change of the mechanical incomplete combustion loss have the same influence on the coal consumption, but have different influence on the cost of unit degree electricity, namely the influence of the change of the power consumption rate of the coal mill is larger than the influence of the change of the mechanical incomplete combustion loss;

and 4, step 4:

repeating the steps 2-3 to obtain the coal powder fineness d under different operation modes of the coal mill_90,3、…、d_90,nAnd Δ C_cbWherein the cost Δ C per unit degree of electricity_cb,optMinimum coal mill operation for optimum coal fines fineness, Δ C_cb,opt＝min[(d_90,2,ΔC_cb,2),(d_90,3,ΔC_cb,3),…,(d_90,n,ΔC_cb,n)]。

The coal powder fineness in the step 1 is obtained through the following modes:

the coal crushing mill motor consumes electric energy to drive the crushing equipment to complete, air entering the coal mill carries crushed coal powder to pass through the coal mill separator, then the crushed coal powder is conveyed into a boiler to be combusted, coarse coal powder returns to the coal mill to be continuously crushed, the fineness of the coal powder leaving the coal mill is adjusted through the coal mill separator, the fineness of the coal powder leaving the coal mill is reduced, the amount of the coarse coal powder returning to the coal mill to be continuously crushed is increased, the power consumption rate of the coal mill motor is increased, and vice versa;

the coal dust leaving the coal mill can be characterized by the coal dust fineness, which is related to the fly ash combustible burned by the boiler, the smaller the coal dust fineness, the lower the fly ash combustible.

The invention has the beneficial effects that:

according to the method, the cost influence of the unit price of standard coal and the price of on-grid electricity on the fineness of the coal powder of the coal mill is considered, the cost change of the unit electricity of the thermal power generating unit is obtained through the influence of the fineness of the coal powder on the power consumption rate of the coal mill and the incomplete combustion loss of machinery, and the fineness of the coal powder with the optimal economical efficiency is determined. Compared with the traditional analysis method, the method has the advantages that the influence of the change amount of the power consumption rate of the coal mill and the cost effect of the change amount of the mechanical incomplete combustion loss on unit-degree electricity are considered to be different from each other from the aspect of economy, the optimization and adjustment of the operation of the coal mill are judged, and the economic benefit of a thermal power plant is maximized.

Description of the drawings:

FIG. 1 is a schematic view of a coal pulverizer.

Detailed Description

The present invention is further described in detail below with reference to the actual calculation scheme.

A coal mill coal powder optimal fineness evaluation method based on cost change has the following specific practical cases:

the power price of the power of a certain thermal power generating unit is 400 yuan/MWh, the price of the standard coal is 0.5 yuan/kg (standard coal), the power consumption rate of an original coal mill is 0.004, the combustible substance of fly ash is 0.06, the incomplete combustion loss of machinery is 0.03, the standard coal consumption for power generation is 300kg (standard coal)/MWh, after the coal mill is adjusted, the fineness of the pulverized coal is reduced, the combustible substance of fly ash is reduced to 0.05, the incomplete combustion loss of machinery is 0.025, the power consumption rate of the coal mill is increased to 0.0042, and the cost change of unit degree electricity is as follows:

400x (0.042-0.004) +0.5x300(0.025-0.03) ═ 0.8-0.75 ═ 0.05M/MWh

From the viewpoint of the power generation cost, although the mechanical incomplete combustion loss is reduced, since the power consumption rate of the coal mill increases and the cost per unit degree of electricity increases, the adjustment of the coal mill is not economical.

The working principle of the coal mill (see fig. 1) is as follows:

the coal crushing mill motor consumes electric energy to drive the crushing equipment to complete, air entering the coal mill carries crushed coal powder to pass through the coal mill separator, then the crushed coal powder is conveyed into a boiler to be combusted, coarse coal powder returns to the coal mill to be continuously crushed, the fineness of the coal powder leaving the coal mill is adjusted through the coal mill separator, the fineness of the coal powder leaving the coal mill is reduced, the amount of the coarse coal powder returning to the coal mill to be continuously crushed is increased, the power consumption rate of the coal mill motor is increased, and vice versa;

the coal powder leaving the coal mill can be represented by coal powder fineness, the coal powder fineness is related to fly ash combustible substances combusted by a boiler, the smaller the coal powder fineness is, the lower the fly ash combustible substances are, the incomplete combustion loss of a machine is correspondingly reduced, but the power consumption rate of a motor of the coal mill can be increased, so that the optimal coal powder fineness exists.

A coal mill coal powder optimal fineness evaluation method based on cost change has a specific practical case II:

the thermal power generating unit has the power price of 400 yuan/MWh on the internet, the price of standard coal of 0.5 yuan/kg (standard coal), the power consumption rate of an original coal mill of 0.004, the combustible substance of fly ash of 0.06, the incomplete combustion loss of machinery of 0.030, the standard coal consumption for power generation of 300kg (standard coal)/MWh, after the coal mill is adjusted, the fineness of pulverized coal is increased, the combustible substance of fly ash is increased to 0.07, the incomplete combustion loss of machinery of 0.035, the power consumption rate of the coal mill is reduced to 0.0038, and the cost change of unit electricity is as follows:

400x (0.0038-0.004) +0.5x300(0.035-0.03) — 0.8+0.75 — -0.05 yuan/MWh

From the power generation cost, although the incomplete combustion loss of the machine is increased, the power consumption rate of the coal mill is reduced, the adjustment of the coal mill reduces the cost of unit-degree electricity, the income is increased, and the fineness of the pulverized coal is better than that before the adjustment. Taking a 1000MW unit as an example, if the annual equivalent utilization hours is 4500, the yield is increased by 1000 × 5000 × 0.05/10000, which is 25 ten thousand yuan.

Claims (2)

1. A coal mill coal powder optimal fineness evaluation method based on cost variation is characterized by comprising the following steps;

step 1:

the fineness d of the coal dust at the outlet of the separator of the coal mill before the operation adjustment of the coal mill needs to be obtained through statistics or according to related technical standard tests_90，1Coal mill motor power consumption rate eta_cyd，1Fly ash combustible material C_fh，1According to GB/T10184 according to fly ash combustible C_fh，1Can calculate incomplete combustion loss q of machinery_4，1；

Step 2:

obtaining the coal powder fineness d of the power consumption rate of the coal mill after the adjustment of the coal mill_90，2Coal mill motor power consumption rate eta_cyd，2Fly ash combustible C_fh，2Also according to GB/T10184 according to fly ash combustible C_fh，2Can calculate incomplete combustion loss q of machinery_4，2；

And step 3:

marking coal price P_coalAnd the price of power P_swThe cost change Δ C per unit of electricity is calculated by substituting the following equation_cb：

ΔC_cb，2＝P_sw(η_cyd，2-η_cyd，1)+P_coalb_fd(q_4，2-q_4，1)

In the formula,. DELTA.C_cb，2-cost variation after coal mill adjustment, yuan/MWh;

P_sw-the power price of the thermal power generating unit on the internet, yuan/MWh;

η_cyd，2-the power consumption of the coal mill after adjustment of the coal mill, -;

η_cyd，1-coal mill power consumption before coal mill adjustment, -;

P_coalthe price of the standard coal, yuan/kg (standard coal);

b_fdpower generation standard coal consumption, kg (standard coal)/MWh;

q_4，2-loss of incomplete combustion of machinery after adjustment of the coal mill, -;

q_4，1-mechanical incomplete combustion losses before coal mill adjustment, -;

if the unit profit changes C_cb，2Less than or equal to 0, the yield of the thermal power generating unit is positive, the economical efficiency after the coal mill is adjusted is feasible, and the fineness d of the pulverized coal is_90，2Ratio d_90，1The better is;

from the above formula, because the difference exists between the power price of the thermal power generating unit on the internet and the power generation standard coal consumption, the following requirements are met under the general condition:

P_sw＞P_coalb_fd

therefore, after the coal mill is adjusted, the same change of the power consumption rate of the coal mill and the change of the mechanical incomplete combustion loss have the same influence on the coal consumption, but have different influence on the cost of unit degree electricity, namely the influence of the change of the power consumption rate of the coal mill is larger than the influence of the change of the mechanical incomplete combustion loss;

and 4, step 4:

repeating the steps 2-3 to obtain the coal powder fineness d under different operation modes of the coal mill_90，3、...、d_90，nAnd Δ C_cbWherein the cost Δ C per unit degree of electricity_cb，optMinimum coal mill operation for optimum coal fines fineness, Δ C_cb，opt＝min[(d_90，2，ΔC_cb，2)，(d_90，3，ΔC_cb，3)，...，(d_90，n，ΔC_cb，n)]。

2. The method for evaluating the optimal fineness of the pulverized coal of the coal mill based on the cost change as claimed in claim 1, wherein the fineness of the pulverized coal in the step 1 is obtained by:

the coal crushing mill motor consumes electric energy to drive the crushing equipment to complete, air entering the coal mill carries crushed coal powder to pass through the coal mill separator, then the crushed coal powder is conveyed into a boiler to be combusted, coarse coal powder returns to the coal mill to be continuously crushed, the fineness of the coal powder leaving the coal mill is adjusted through the coal mill separator, the fineness of the coal powder leaving the coal mill is reduced, the amount of the coarse coal powder returning to the coal mill to be continuously crushed is increased, the power consumption rate of the coal mill motor is increased, and vice versa;

the coal dust leaving the coal mill can be characterized by the coal dust fineness, which is related to the fly ash combustible burned by the boiler, the smaller the coal dust fineness, the lower the fly ash combustible.

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