JP3643647B2 - Operation method of fuel supply system for combined cycle power plant - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to oil-fired gas turbine combined cycle power generation.
[0002]
[Prior art]
At present, thermal power generation in Japan mainly uses a system in which a steam turbine is rotated by high-temperature and high-pressure steam generated by a boiler. As the boiler fuel, heavy oil and crude oil are mainly used. Of these, in the case of burning crude oil, low sulfur content crude oil with a high wax content and low SOx generation, such as Minas crude oil and Daqing Produced crude oil is preferred.
[0003]
In addition, recently, a combined cycle power generation facility using LNG, which is a high-quality fuel, has also been adopted. In power generation using the above-described boilers and steam turbines of crude oil or heavy oil, the thermal efficiency is relatively low at around 40% / HHV standard (HHV: high heating value).
[0004]
On the other hand, combined cycle power generation used in LNG burning is a method in which fuel is burned in a gas turbine, the high-temperature exhaust gas is reburned in a boiler, a steam turbine is operated, and power is generated again (so-called exhaust reburning type). The thermal efficiency is dramatically improved to around 48% / HHV standard.
[0005]
For this reason, the development of the combined cycle power generation is strongly desired in recent years when it is urged to switch to a more heat-efficient power generation method from the viewpoint of suppressing the increase in oil consumption. However, in the conventional combined cycle power generation of LNG, LNG is costly to store, and when LNG is supplied to petroleum thermal power, it is expensive to embed the pipeline.
[0006]
On the other hand, there are examples of so-called oil-fired gas turbine combined cycle power generation using crude oil as a fuel in Europe and the United States, but there are problems that many troubles occur due to impurities contained in the crude oil and maintenance costs increase. In this respect, there was a difficulty in practical use. This is because the salinity, vanadium and sulfur contained in the crude oil interact with each other to become a low melting point substance in the gas turbine and adhere to the blade, causing corrosion of the blade.
[0007]
For this reason, as a fuel for a gas turbine, a standard in which the content of salt and vanadium is 0.5 ppm or less is generally adopted, and the sulfur content is also 0.5 wt. However, even low-sulfur-containing crude oils such as Minas crude oil and Daqing crude oil do not satisfy at least these standards for salinity and vanadium, and heat-efficient combined cycle power generation It could not be used as a turbine fuel. Therefore, as a result, it has been difficult to put oil-fired gas turbine combined cycle power generation using crude oil as fuel for the gas turbine.
[0008]
[Problems to be solved by the invention]
In order to solve the above-mentioned impurity problem, the applicant, for example, according to Japanese Patent Application No. 4-287504 (Japanese Patent Application Laid-Open No. 6-207180), distills the desalted crude oil at a predetermined temperature to obtain a low boiling point distillation. An oil-fired gas using crude oil distillation technology, in which a low-boiling fraction is used as gas turbine fuel, while a high-boiling fraction is used as fuel for steam turbine boilers. A turbine combined cycle power generation method is proposed and put into practical use.
[0009]
However, in this power generation method, it was originally considered that each fuel (low-boiling fraction or high-boiling fraction) is generated at a constant distillation temperature. Therefore, the required proportion of fuel consumption accompanying fluctuations in power generation load, etc. It was difficult to respond flexibly to changes. That is, the ratio of the required amount of turbine fuel and boiler fuel is not necessarily constant but changes with fluctuations in the power generation load, etc., but when the distillation temperature is constant, the amount of low-boiling fraction produced as turbine fuel and The ratio of the amount of high-boiling fraction produced as boiler fuel is also almost constant.
[0010]
For this reason, the conventional configuration cannot cope with the change in the ratio of the required amount of fuel, and depending on the case, there is a possibility that some supplementary fuel needs to be replenished or surplus fuel is generated.
[0011]
Accordingly, the present invention is a method for operating a fuel supply system of an oil-fired gas turbine combined cycle power generation facility using crude oil distillation technology, and does not require supplementary fuel or the like. It aims at providing the fuel supply system operation method which can respond flexibly to the change of a ratio.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the fuel supply system operating method of the combined cycle power generation facility according to claim 1, wherein the crude oil is distilled at a predetermined distillation temperature to be separated into a low boiling fraction and a high boiling fraction, A method for operating a fuel supply system of a combined cycle power plant using a low-boiling fraction as a fuel for a gas turbine and using the high-boiling fraction as a fuel for a steam turbine boiler, the low-boiling fraction and the According to the required amount of the high boiling fraction, the distillation temperature is adjusted to control the production ratio of the low boiling fraction and the high boiling fraction.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is a diagram showing the configuration of the fuel supply system in the combined cycle power generation facility of this example, and FIG. 2 is a diagram showing the configuration of the power generation system in the combined cycle power generation facility. FIG. 3 is a diagram showing the relationship between the distillation temperature and fraction in the case of Minas crude oil.
[0014]
As shown in FIG. 1, the fuel supply system of this power generation facility includes a crude oil tank 1, a crude oil supply pump 2, a crude oil preheater 3-6, a crude oil heating furnace 7, a distillation tower 8, a condenser 9 as shown in FIG. , Turbine fuel supply pump 10, reflux pump 11, turbine fuel tank 12, boiler fuel supply pump 13, boiler fuel tank 14, feed water preheaters 15 and 16, turbine fuel level sensor 17 (not shown in FIG. 2), boiler fuel level sensor 18 (omitted in FIG. 2), a crude oil supply amount adjustment valve 19 and a distillation amount controller 20 are provided.
[0015]
The crude oil tank 1 stores crude oil, and it is preferable to use a low-sulfur crude oil that has been desalted as the crude oil. As this low-sulfur crude oil, since the desulfurization process of exhaust gas can be simplified, it is needless to say that a low sulfur content is preferable. Usually, the sulfur content is 1% by weight or less, more preferably 0.5%. Less than wt% crude oil is used. Examples of such crude oil include the aforementioned Minas crude oil and Daqing crude oil.
[0016]
In addition, since most sulfur content contained in crude oil is isolate | separated by distillation mentioned later, it is not necessary to necessarily use the above low sulfur crude oil as crude oil of this invention. Further, the salinity contained in the crude oil is likely to remain on the high-boiling fraction side by distillation using the distillation column 8, and depending on the distillation temperature conditions, the salinity content of the low-boiling fraction may be the above-mentioned reference value (0.5 ppm). Therefore, the crude oil of the present invention does not necessarily have to be desalted.
[0017]
In addition, when the desalination treatment is performed in the same facility, a heating means for preheating the crude oil to about 80 to 150 ° C. is provided, and for example, a plurality of stages of diso-routers as well-known desalting means are provided as necessary. Just do it. This disorouter mixes heated crude oil and fresh water and applies a static voltage of, for example, about 20,000 volts to agglomerate and separate the water droplets, lowering the viscosity of the crude oil and separating it by the difference in specific gravity between water and crude oil. In order to facilitate, it is preferable to preheat the crude oil as described above.
[0018]
In addition, the said disorouter is arrange | positioned in the middle of the crude oil supply line 21 which supplies crude oil from the crude oil tank 1 to the crude oil heating furnace 7, and some of the crude oil preheaters 3-6 are heated for the said desalination process. It can also function as a means.
[0019]
The crude oil supply pump 2 sends out the crude oil in the crude oil tank 1 and pumps it to the crude oil heating furnace 7 and further to the distillation tower 8 through the crude oil supply line 21. In this case, the crude heating furnace 7 burns crude oil in the crude oil tank 1, high boiling fraction in the boiler fuel tank 14, or crude oil, heavy oil, light oil, kerosene, naphtha, LPG, etc. prepared separately from the power generation fuel. The crude oil sent to the distillation column 8 is heated to a predetermined distillation temperature.
[0020]
In this case, the heating amount of the crude oil heating furnace 7 is automatically controlled by the distillation amount controller 20, and the distillation temperature (the crude oil temperature at the inlet of the distillation column 8) is generated so that each fuel is generated in an amount corresponding to the required amount. ) Is adjusted. That is, there is a certain relationship between the amount ratio of the low-boiling fraction produced by distillation and the distillation temperature. For example, in the case of Minas crude oil, it is as shown in FIG. As will be described later, in this case, the distillation amount controller 20 corresponds to the amount ratio of the low-boiling fraction and the high-boiling fraction to be generated based on the level signals from the turbine fuel level sensor 17 and the boiler fuel level sensor 18. It is the structure which controls the heating amount of the crude-oil heating furnace 7 so that it may become distillation temperature.
[0021]
The distillation temperature must be controlled within a predetermined allowable range so that the content of vanadium, salt or sulfur in the low-boiling fraction used as a gas turbine fuel becomes a desired value. May be determined according to the properties of the crude oil and the distillation pressure.
[0022]
In this case, the crude oil preheaters 3 and 4 or the crude oil preheaters 5 and 6 are gas derived from the top of the distillation column 8 (ie, low boiling fraction) or liquid derived from the bottom of the distillation column 8 (ie, This heat exchanger recovers heat in two stages from the high boiling fraction) and sequentially heats the crude oil before it is sent to the crude oil heating furnace 7, which increases the heating efficiency of the crude oil and imposes a burden on the crude oil heating furnace 7. Becomes lighter.
[0023]
In this case, the distillation column 8 is a system in which the low-boiling fraction derived from the top of the column is returned as a liquid by the reflux pump 11 and the reflux line 22 to come into contact with the generated steam of the crude oil and increase the degree of separation. For example, a bubble tower, a perforated plate tower, or a packed tower can be used.
[0024]
The condenser 9 is, for example, a multi-tube heat exchanger that finally cools and condenses the gas (that is, the low-boiling fraction) led out from the top of the distillation column 8 by the liquid line 23. In this case, the condenser 9 is condensed. Unsuccessful gas (off-gas) is discharged from the top. The low-boiling fraction of crude oil condensed in the condenser 9 is withdrawn from the bottom, a part thereof is returned to the distillation column 8 by the reflux pump 11 and the reflux line 22, and the remainder is turbine fuel as turbine fuel. The feed pump 10 sends the fuel to the turbine fuel tank 12. The boiler fuel supply pump 13 pumps the liquid derived from the bottom of the distillation column 8 (ie, the high boiling fraction) to the boiler fuel tank 14 through the liquid line 24.
[0025]
The feed water preheaters 15 and 16 recover heat from the gas derived from the top of the distillation column 8 (ie, the low boiling fraction) or the liquid derived from the bottom of the distillation column 8 (ie, the high boiling fraction). It is a heat exchanger that heats boiler feed water that is sent to the boiler 35 described later.
[0026]
The turbine fuel level sensor 17 is a level sensor that outputs a signal corresponding to the liquid level of the fuel in the turbine fuel tank 12 (turbine fuel composed of low boiling fraction), and the boiler fuel level sensor 18 is a boiler. This is a level sensor that outputs a signal corresponding to the liquid level of the fuel in the fuel tank 14 (boiler fuel comprising a high boiling fraction). The detection signals of these level sensors 17 and 18 are as shown in FIG. It is input to the distillation amount controller 20.
[0027]
The crude oil supply amount adjusting valve 19 is provided on the discharge side of the crude oil supply pump 2 in this case, and adjusts the flow rate of the crude oil sent from the crude oil tank 1 to the distillation tower 8. Be controlled. The distillation amount controller 20 also determines the opening of the crude oil supply amount control adjustment valve 19 and the crude oil heating furnace 7 based on the amount of fuel stored in the tanks 12 and 14 detected by the detection signals of the level sensors 17 and 18. The amount of crude oil distilled is controlled so that the amount of fuel stored in the tanks 12 and 14 is maintained within a certain range. In this case, the distillation temperature and distillation as shown in FIG. It is characterized in that the production ratio of the high-boiling fraction and the low-boiling fraction is changed depending on the distillation temperature so as to correspond to the required amount based on the relationship of the minutes.
[0028]
Specifically, for example, the following control is performed. That is, when the amount of fuel stored in each of the tanks 12 and 14 is within the normal range, a reference amount of low-boiling fraction corresponding to the average fuel consumption of the gas turbine 34 described later, and The flow rate and distillation temperature of the crude oil sent to the distillation column 8 are controlled so that a reference amount of high-boiling fraction corresponding to the average fuel consumption of the boiler 35 is generated.
[0029]
Then, for example, when only the fuel consumption of the gas turbine 34 increases from such a normal state, and only the storage amount in the turbine fuel tank 12 falls below the lower limit of the normal range (the required amount of the low-boiling fraction is reduced). When the ratio is increased), only the low-boiling fraction is generated in a larger amount than the reference amount while the amount of the high-boiling fraction is maintained at the reference amount (the generation ratio of the low-boiling fraction). Increase the distillation temperature with the crude oil feed rate.
[0030]
Conversely, when only the amount stored in the turbine fuel tank 12 exceeds the upper limit of the normal range (when the ratio of the required amount of low-boiling fraction is reduced), the production amount of the high-boiling fraction is Distillation with the supply flow rate of the crude oil sent to the distillation column 8 so that only the low-boiling fraction is produced in a smaller amount than the reference amount while maintaining the reference amount (so that the generation ratio of the low-boiling fraction is reduced). Control to lower the temperature.
[0031]
Furthermore, when only the amount stored in the turbine fuel tank 12 falls below the lower limit of the allowable range set outside the normal range (when the ratio of the required amount of the low boiling fraction further increases), the reference The distillation temperature is controlled to the maximum permissible range (for example, 420 ° C.) so that a larger amount of low-boiling fraction is produced than the amount, and the amount of high-boiling fraction produced within the range that does not become excessive. Increase supply flow to maximum.
[0032]
Conversely, when only the amount stored in the turbine fuel tank 12 exceeds the upper limit of the allowable range (when the ratio of the required amount of low-boiling fraction further decreases), only the low-boiling fraction is generated. In order to stop the heating, the heating of the crude oil is stopped, and the supply flow rate of the crude oil is controlled to the required amount of the high boiling fraction (the reference amount to be sent to the boiler fuel tank 14).
[0033]
In addition, for example, when both the fuel consumption of the gas turbine 34 and the boiler 35 increase from the normal state, and the storage amount in each of the tanks 12 and 14 falls below the lower limit of the normal range (high boiling fraction and low In the case where the total required amount is increased while the ratio of the required amount of boiling fraction remains substantially constant), the high boiling fraction and the low boiling fraction are each produced in a larger amount than the reference amount. Only the crude oil supply flow rate is increased while maintaining the distillation temperature at the normal value.
[0034]
Conversely, if the amount stored in each of the tanks 12 and 14 exceeds the upper limit of the normal range (the ratio of the required amount of the high boiling fraction and the low boiling fraction remains substantially constant, In the case of lowering), only the crude oil supply flow rate is reduced while maintaining the distillation temperature at the normal state value so that the high boiling fraction and the low boiling fraction are produced in a smaller amount than the reference amount, respectively. Take control.
[0035]
Furthermore, when the storage amount in each tank 12, 14 falls below the lower limit of the allowable range (the overall required amount further increases while the ratio of the required amount of the high boiling fraction and the low boiling fraction remains substantially constant) In this case, the supply flow rate of the crude oil can be maximized while maintaining the distillation temperature at the normal value so that a higher boiling fraction and a lower boiling fraction than the reference amount are generated. Increase to.
[0036]
Conversely, if the amount stored in each tank 12, 14 exceeds the upper limit of the allowable range (the ratio of the required amount of the high boiling fraction and the low boiling fraction remains substantially constant, In the case of further reduction), the heating of the crude oil and the supply of the crude oil are stopped to stop the production of the high boiling fraction and the low boiling fraction.
[0037]
Next, as shown in FIG. 2, the power generation system of this power generation facility includes, as shown in FIG. 2, a gas turbine 34, a boiler 35, a steam turbine 36, a condensate comprising a turbine body 31, a compressor 32, and a combustor 33. A container 37 and an economizer 38 are provided. Here, the gas turbine 34 causes the turbine fuel supplied from the turbine fuel tank 12 through the supply line 41 to be brought into contact with the air compressed by the compressor 32 and burned in the combustor 33, and this in the turbine body 31. In this case, the exhaust gas after combustion (residual oxygen concentration of about 11% to 15%, temperature of 580 ° C.) is formed in order to form an exhaust gas recombination type combined cycle. Degree) is supplied to the boiler 35 via the exhaust gas line 42.
[0038]
The boiler 35 is a Stirling boiler, for example, and has a convection heat transfer section 35a. The boiler 35 is supplied with the boiler fuel in the above-described boiler fuel tank 14 through the supply line 43 as fuel, and the exhaust gas from the boiler 35 is removed from the NOx removal through the exhaust gas derivation line 44. In addition to passing through the device and the dust collector, the heat is recovered by the economizer 38, guided to a chimney (not shown), and released to the atmosphere. Depending on the properties of the crude oil, a desulfurization device for removing sulfur (especially sulfurous acid gas) from the flue gas may be provided. Further, the economizer 38 is a heat exchanger that heats boiler feed water by the heat of smoke discharged from the boiler 35 in order to improve the thermal efficiency of the steam cycle.
[0039]
Although not shown in FIG. 2 because it is complicated, the steam turbine 36 includes a multi-stage steam turbine such as high pressure, medium pressure, and low pressure so as to form a so-called reheat cycle. In addition, in order to form a so-called regeneration cycle, it is naturally preferable to provide a plurality of extraction / feed water heaters to ensure a high degree of thermal efficiency. In this case, the feed water preheaters 15 and 16 (not shown in FIG. 2) shown in FIG. 1 also heat the feed water sent from the condenser 37 to the boiler 35 to further increase the thermal efficiency of the steam cycle.
[0040]
According to the power generation facility configured as described above and the operation method thereof, first, the advantages of combined cycle power generation are avoided while avoiding the problems such as the corrosion of the blade metal of the gas turbine 34 caused by impurities as described above. High-efficiency power generation can be made practical. That is, the crude oil sent out from the crude oil tank 1 by the crude oil supply pump 2 is heated to, for example, about 270 ° C. by the crude oil preheaters 3 to 6, and in this case, the crude oil heating furnace 7 provided independently in this case finally To a predetermined distillation temperature.
[0041]
If the distillation temperature is maintained within the above-described allowable range, the vanadium and salt content concentrations of the low-boiling fraction (that is, turbine fuel) derived from the top of the distillation column 8 are set to the reference values. It can be stably maintained at 0.5 ppm (wt.) Or less, and the sulfur content is also 0.5 to 0.05 wt. % Or less. That is, in the case of atmospheric distillation, most of heavy metals remain in high boiling fractions of about 900 ° F. or higher, and salt also remains in high boiling fractions of 420 ° C. (788 ° F.) or higher. Most of these impurities remain on the high-boiling fraction side and are contained in the boiler fuel sent to the boiler fuel tank 14. In the boiler 35, since heavy oil or the like has been burned conventionally, even a fuel containing such impurities can be operated without any problem.
[0042]
Thus, fuel with a sufficiently low impurity concentration is continuously supplied from the turbine fuel tank 12 to the gas turbine 34, and the high-temperature exhaust gas discharged from the gas turbine 34 is introduced into the boiler 35 and re-burned, so that storage is possible. High-efficiency combined cycle power generation using easy crude oil can be operated with high reliability without causing problems caused by impurities in the crude oil.
[0043]
In the operation method of this example, the supply of crude oil is performed based on the change in the storage amount of each of the tanks 12 and 14 as described above within the above-mentioned temperature condition in which most of heavy metals and salt are separated to the high boiling point side. By controlling the distillation temperature together with the amount, depending on the required amount of the high-boiling fraction and the low-boiling fraction, the production ratio is changed together with their overall production amount (distillation amount). Even if the ratio of consumption of fuel for gas turbines and boilers fluctuates with the overall consumption of fuel, no auxiliary fuel is required for any fuel, and surplus fuel is produced. Nor. For this reason, it becomes possible to efficiently supply the minimum necessary fuel with simple equipment that does not require an auxiliary fuel tank or the like.
[0044]
Moreover, in the case of the above-described embodiment, as described above, the tanks 12 and 14 for storing the high-boiling fraction and the low-boiling fraction are provided, and the absolute storage amount of each tank is maintained within a certain range. So that it is controlled. Therefore, each of the tanks 12 and 14 functions as a buffer, and even when there is a sudden change in fuel consumption, it is possible to stably supply a necessary amount of fuel, and these tanks 12 and 14 Is advantageous in that it is smaller than in the case of constant distillation amount control.
[0045]
In addition, this invention is not restricted to the said example of a form, There can be various aspects. For example, in the above embodiment, the required amount of each fuel is determined based on the storage amount of the tanks 12 and 14 that store the high-boiling fraction or the low-boiling fraction, and the distillation temperature is changed in accordance with this amount. For example, the supply flow rate of the fuel supplied to the turbine 34 and the boiler 35 is detected, and the generation rate of each fuel changes according to the ratio of the supply flow rate. The distillation temperature may be adjusted.
[0046]
Even when the required amount of each fuel is determined based on the storage amount of the tanks 12 and 14, the required amount is changed stepwise based on whether or not the upper and lower limits of a certain range are exceeded, as in the above example. It is not restricted to the aspect which determines and adjusts distillation temperature, You may adjust distillation temperature so that a production | generation ratio may change continuously according to the ratio of storage amount.
[0047]
Moreover, in the said form example, it was set as the structure which the system which consists of the controller 20 performs automatically operation operation, such as adjustment of the supply_amount | feed_rate of crude oil (operation of the valve 19), and operation of the heating amount of the crude oil heating furnace 7, Needless to say, the operator may determine the amount of tank storage and the like by manual operation of the operator.
[0048]
【The invention's effect】
According to the fuel supply system operation method of the combined cycle power generation facility of the present invention, according to the respective required amounts of the high boiling fraction and the low boiling fraction, the distillation temperature is adjusted to change their production ratio. Therefore, even if the ratio of the required amount of gas turbine fuel and boiler fuel fluctuates along with the overall required amount of fuel, any fuel does not require auxiliary fuel and surplus fuel. Therefore, it is possible to efficiently supply the minimum necessary fuel with a simple facility that does not require an auxiliary fuel tank or the like.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a fuel supply system of a combined cycle power generation facility as an example of an embodiment of the present invention.
FIG. 2 is a diagram showing a power generation system of the combined cycle power generation facility.
FIG. 3 is a diagram showing properties of Minas crude oil (distillation temperature and fraction).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Crude oil tank 2 Crude oil supply pump 3-6 Crude oil preheater 7 Crude oil heating furnace 8 Distillation tower 9 Condenser 10 Turbine fuel supply pump 11 Reflux pump 12 Turbine fuel tank 14 Boiler fuel tank 17 Turbine fuel level sensor 18 Boiler fuel level sensor 19 Crude oil supply amount adjustment valve 20 Distillation amount controller 34 Gas turbine 35 Boiler 36 Steam turbine 37 Condenser

Claims (1)

Crude oil is distilled at a predetermined distillation temperature to be separated into a low boiling fraction and a high boiling fraction, the low boiling fraction is used as a gas turbine fuel, and the high boiling fraction is used as fuel for a steam turbine boiler. The combined cycle power generation facility used as a fuel supply system operation method, wherein the distillation temperature is adjusted according to the required amount of the low boiling fraction and the high boiling fraction, the low boiling fraction and the A method for operating a fuel supply system of a combined cycle power generation facility, characterized by controlling a generation ratio of a high-boiling fraction.

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