# A summary of the hottest factors affecting coal co

2022-10-01
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Summary of factors affecting coal consumption for power supply is worth collecting

coal consumption for power supply, also known as standard coal consumption for power supply, is the average consumption of standard coal (unit: g/kWh, g/kwh) for each 1kwh of electric energy provided by thermal power plants. It is a consumption indicator calculated according to the power supply of the final product of the power plant, and it is one of the important assessment indicators of the state for thermal power plants

the following is a summary of factors affecting coal consumption for power supply for reference

1. The rise of main steam pressure by 1MPa affects the reduction of coal consumption for power supply by 1.65g/kw H

control measures: the increase of main steam pressure will reduce the heat consumption of the steam turbine, but generally, it should not exceed the design value during operation, so as not to cause overpressure due to poor control

calculation formula: the detailed calculation method is to calculate the whole thermal system, first get the change of work and heat absorption, and then get the change of coal consumption. Or the change of heat consumption can be obtained from the correction curve of the manufacturer, and then the change of coal consumption can be obtained. In addition, the influence of other factors on the change of main steam pressure should also be considered. The following formula can be used for rough estimation:

b*[c1/(1+c1)]/η b/（1- η e) , B - coal consumption, C1 - correction coefficient of main steam pressure to heat consumption, η B - boiler efficiency, η E - is the auxiliary power consumption rate

2. The decrease of main steam pressure by 1MPa affects the increase of power supply coal consumption by 1.89g/kw H

control measures: during operation, try to approach the design value for working conditions above 80%, and the target value for working conditions below 80% is not necessarily the design value. The determination of the target value needs to be determined through special sliding parameter optimization tests

calculation formula: the estimation formula is the same as the main steam pressure rise

3. Every 10 ℃ decrease in main steam temperature will affect the increase of coal consumption for power supply by 1.26g/kw H

control measures: low main steam temperature is generally related to factors such as ash deposition in Superheater, low flame center, high feedwater temperature, low combustion excess air coefficient, saturated steam with water, internal leakage of desuperheating water valve, etc. During operation, soot blowing shall be carried out according to the requirements of the regulations, and the air volume and the ratio of primary and secondary air shall be adjusted according to the change of coal type

calculation formula: the detailed calculation method is to calculate the whole thermal system, first get the change of work and heat absorption, and then get the change of coal consumption. Or the change of heat consumption can be obtained from the correction curve of the manufacturer, and then the change of coal consumption can be obtained. In addition, the influence of other factors on the change of main steam temperature should also be considered. The following formula can be used for rough estimation:

b*[c2/(1+c2)]/η b/（1- η e) , B - coal consumption, C2 - correction coefficient of main steam temperature to heat consumption, η B - boiler efficiency, η E - is the auxiliary power consumption rate

4. Every 10 ℃ rise in main steam temperature will affect the reduction of power supply coal consumption by 1.14g/kw H

control measures: the increase of main steam temperature will reduce the heat consumption of the steam turbine, but generally, it should not exceed the design value during operation, so as not to cause overheating due to poor control

calculation formula: the estimation formula is the same as the main steam temperature drop

5. Every 10 ℃ rise in reheater temperature will affect the reduction of power supply coal consumption by 0.91g/kw H

control measures: the increase of reheat steam temperature will reduce the heat consumption of the steam turbine, but generally, it should not exceed the design value during operation, so as not to cause overheating due to poor control

calculation formula: the detailed calculation method is to calculate the whole thermal system, first get the change of work and heat absorption, and then get the change of coal consumption. Or the change of heat consumption can be obtained from the correction curve of the manufacturer, and then the change of coal consumption can be obtained. In addition, the influence of other factors on the change of reheat steam temperature should also be considered. The following formula can be used for rough estimation:

b*[c3/(1+c3)]/η b/（1- η e) , B - coal consumption, C1 - correction coefficient of reheat steam temperature to heat consumption, η B - boiler efficiency, η E - is the auxiliary power consumption rate

6. Every 10 ℃ drop in reheater temperature will affect the increase of coal consumption for power supply by 0.99g/kw H

control measures: low reheat steam temperature is generally related to factors such as ash deposition in reheater, low flame center, low cold reheat steam temperature, low combustion excess air coefficient, internal leakage of desuperheating water valve, etc. During operation, soot blowing shall be carried out according to the requirements of the regulations, the air volume shall be adjusted according to the change of coal type, the ratio of primary and secondary air, and sliding pressure operation shall be carried out at low load to improve the temperature of cold reheated steam

calculation formula: the estimation formula is the same as that of reheat steam temperature rise

7. The pressure loss of reheater increases by 1%, which affects the reduction of coal consumption for power supply by 0.32g/kw H

control measures: the reheat pressure loss is related to the design, and it is uncontrollable in operation

calculation formula: the detailed calculation method is to calculate the whole thermal system, first get the change of work and heat absorption, and then get the change of coal consumption. Or the change of heat consumption can be obtained from the correction curve of the manufacturer, and then the change of coal consumption can be obtained. In addition, the influence of other factors on the change of reheat pressure loss should also be considered. The following formula can be used for rough estimation:

b*[c4/(1+c4)]/η b/（1- η e) , B -- is the coal consumption, C4 -- is the correction coefficient of reheat pressure loss to heat consumption, η B - boiler efficiency, η E - is the auxiliary power consumption rate

8. The pressure loss of reheater decreases by 1%, which affects the increase of coal consumption for power supply by 0.28g/kw H

control measures: reheating pressure loss is related to design and is uncontrollable during operation

calculation formula: the estimation formula is the same as the increase of reheat pressure loss

9. The decrease of condenser vacuum by 1kPa affects the increase of power supply coal consumption by 2.6g/kw H

control measures: there are many reasons for low condenser vacuum. In general, it is related to the condenser heat transfer coefficient, condenser heat load, cooling water flow and temperature, and the amount of non condensable gas in the condenser. During operation, the following aspects can be adjusted: put the rubber ball cleaning device into operation according to the regulations; The number of circulating water pumps can be determined according to the temperature of circulating water and the vacuum condition of the unit; Regularly check whether the cooling tower drenching filler, nozzle, water separator and other components are intact and whether the drenching density is uniform; Do a good job without leakage, and manually close the manual valve for drainage without water prevention protection; Vacuum tightness test shall be carried out regularly. For the unit using vacuum pump, when the tightness test result is 0.8kpa/min, it will have a great impact on the vacuum of the unit. During operation, check whether the water seal of the shaft is damaged; Appropriately increase the steam supply pressure of low-pressure shaft seal and observe whether the vacuum of condenser has been improved; Conduct vacuum system leak detection if necessary

calculation formula: the detailed calculation method is to calculate the whole thermal system, first get the change of work done, and then get the change of coal consumption. Or the change of heat consumption can be obtained from the correction curve of the manufacturer, and then the change of coal consumption can be obtained. And we should also consider the influence of other factors on the change of vacuum when they change at the same time. The following formula can be used for rough estimation:

b*[c5/(1+c5)]/η b/（1- η e) , B -- coal consumption, C1 -- correction coefficient of vacuum to heat consumption, η B - boiler efficiency, η E - is the auxiliary power consumption rate

note: different vacuum has different influence on coal consumption every 1kPa drop; When the vacuum is low, the impact on coal consumption is much greater for every 1kPa drop. 2.6g/kw. H is the estimated data near the rated vacuum under the load of more than 80%

10. The unit speed drop of 30r/min affects the rise of coal consumption for power supply

control measures: uncontrollable during operation

calculation formula: the change of speed mainly affects the efficiency of the generator and changes the active power generated. The change value of active power after speed change can be found out according to the generator 'speed efficiency' relationship curve, and then the change of coal consumption can be calculated

11. 1t/h leakage change of main steam pipe affects the increase of coal consumption for power supply by 0.35g/kw H

control measures: do a good job of no leakage, and manually close the manual valve for the main steam drainage without water inflow protection

calculation formula: the equivalent heat drop method can be used to carry the heat working medium out of the system, and the calculation formula is not listed in detail

12. 1t/h leakage change in reheat cold section affects the increase of coal consumption for power supply by 0.25g/kw H

control measures: do a good job of no leakage, and manually close the manual valve for the cold re drainage without water inflow prevention protection

calculation formula: it can be calculated by the equivalent heat drop method, carrying the heat working medium out of the system, and the calculation formula is not listed in detail

13. 1t/h leakage change in reheat hot section affects the increase of coal consumption for power supply by 0.32g/kw H

control measures: do a good job without leakage. For the thermal rehydration without water inflow protection, the manual door can be manually closed

calculation formula: the equivalent heat drop method can be used to carry the heat working medium out of the system, and the calculation formula is not listed in detail

14. The change of auxiliary steam consumption of 10t/h affects the coal consumption of power supply of 1.68g/kw H low auxiliary steam source

affects the coal consumption of power supply by 2.1g/kw H high auxiliary steam source

affects the coal consumption of power supply by 2,5g/kw H cold section steam source

control measures: do a good job in the management of non production steam

calculation formula: according to the equivalent heat drop method, carry the heat working medium out of the system to calculate the biaxial impact machine. Presumably, some customers do not know what it is, and the calculation formula is not listed in detail

15. The change of condensate supercooling degree increases by 1 ℃, which affects the increase of power supply coal consumption by 0.04g/kw H

control measures: control the water level of the hot well, and the tightness of the vacuum system meets the standard

calculation formula: the pure heat can be calculated out of the system according to the equivalent heat drop method, and the calculation formula is not listed in detail

16. The decrease of feed water temperature by 10 ℃ affects the increase of coal consumption for power supply by 0.71g/kw H

control measures: check whether the bypass valve of the high-pressure heater leaks, whether the steam inlet valve of the heater throttles, whether the extraction air is normal, and maintain the water level of the high-pressure heater normal

calculation formula: the calculation is the same as that of the end difference rise of the last high-pressure heater

17. Every 1 ℃ increase in condenser end difference will affect the increase of coal consumption for power supply by 0.48g/kw H (near the rated vacuum)

control measures: put the rubber ball cleaning device into operation regularly as required. When the end difference is very large, acid pickling can be considered

calculation formula: an increase of 1 ℃ in the end difference is equivalent to an increase of 1 ℃ in the exhaust temperature. The vacuum around the rated vacuum decreases by about 0.3kpa, which can be calculated according to the vacuum drop

18. The end difference of high-pressure heater changes by 10 ℃ 1. The end difference of high-pressure heater rises, affecting the increase of power supply coal consumption by 0.19g/kw H

2 the terminal difference of high-pressure heater rises, affecting the increase of power supply coal consumption by 0.55g/kw H

3 the terminal difference of high-pressure heater rises, affecting the increase of power supply coal consumption by 0.71g/kw H

control measures: control the water level to avoid insufficient temperature rise of upstream heater; If the heater is seriously blocked and the heat exchange area is insufficient, replacement can be considered

calculation formula: the calculation process is relatively complex and cannot be summarized by a formula. It is no longer listed that

19. The change of extraction pressure loss of high-pressure heater is 0.1mp #1. The end difference of high-pressure heater increases by 2.5 ℃, which affects the increase of coal consumption for power supply by 0.047g/kw H (near the rated working condition)

2 the end difference of high-pressure heater increases by 1.5 ℃, which affects the increase of power supply coal consumption by 0.08g/kw H (near the rated working condition)

3 the end difference of high-pressure heater increases by 1 ℃, which affects the increase of coal consumption for power supply by 0.07g/kw H (near the rated working condition)

control measures: check the opening of steam inlet valve and check valve to ensure no throttling

calculation formula: the increase of pressure loss is equivalent to the increase of end difference, which can be calculated according to the increase of end difference; Under rated working condition, the pressure loss of 3 pump changes by 0.1MPa, and the end difference increases by about 2.5 ℃; The increase of pressure loss is equivalent to the increase of end difference, which can be calculated according to the increase of end difference; Under rated working condition, the pressure loss of 2 pump changes by 0.1MPa, and the end difference increases by about 1.5 ℃; The increase of pressure loss is equivalent to the increase of end difference, which can be calculated according to the increase of end difference; Under rated working condition, 1 pumping pressure loss changes by 0.1MPa, and the end difference increases by about 1 ℃

20. The heat loss of heater and pipeline changes by 1%1. The high-pressure heater affects the coal consumption of power supply by 0.13g/kw H (near the rated working condition)

2 high pressure heater affects the coal consumption of power supply 0.18g/kw H (amount

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