JPH06178598A - Generation - Google Patents

Abstract

PURPOSE:To pick as much fuel as possible that is suitable for a gas turbine from low-sulfur crude oil at low cost and to generate with good heat efficiency by a method wherein gas, whose main ingredient is methane, is simply topped and the obtained low-boiling point fraction is supplied at high temperature to the gas turbine as fuel. CONSTITUTION:Prior to sending low-sulfur crude oil from a crude oil tank 4 to a demineralization process 5, the crude oil is heated in an exhaust heat recovery boiler 2. The demineralized low-sulfur crude oil is supplied to a first simplified topper 6 and the column top gas, together with column top gas of a second simplified topper 8, is gas-liquid separated in a condensation drum 11. Part of it is supplied by a circulating blower 12 to a column bottom of the simplified topper 8 as gas for stripping and the rest is compressed by a gas compresser 13 and is supplied to a gas turbine 1. A condensed fraction in the condensation drum 11 becomes part of fuel for a gas turbine. Out of an intermediate fraction obtained from the column side of the first simplified topper 6, a low boiling point fraction is flown back to the first simplified topper 6 by a first stripper 7 and the rest is used as fuel for a gas turbine.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a combined cycle power generation method.

[0002]

2. Description of the Related Art At present, as a thermal power generation in Japan, a method using a steam turbine, in which a turbine is rotated by steam of high temperature and high pressure generated by a boiler to generate electric power, is mainly used. Heavy oil and crude oil are mainly used as the oil fuel for the boiler. Among them, in the case of burning crude oil, low-sulfur crude oil containing a large amount of wax and a small amount of SOx, such as crude oil from Minas and crude oil from Daqing, is preferably used from the viewpoint of pollution prevention. In addition, recently, a combined cycle power generation method using LNG, which is a good fuel, has been adopted.

The thermal efficiency in the boiler burning of crude oil or heavy oil and the power generation by the steam turbine is relatively low at about 40% / HHV standard (HHV: high heating value). In contrast,
In combined cycle power generation adopted in LNG-fired combustion, fuel is burned by air compressed by a compressor, or the compressed air is heated by combustion heat, and a turbine is rotated by the high temperature and high pressure gas to generate electricity. This is a method of recovering the heat energy of the exhaust gas with a boiler, operating a steam turbine, and generating electricity again, with a thermal efficiency of about 48% / H.
It is characterized by high HV standard.

[0004]

Since the reserves of petroleum are limited and the increase in petroleum consumption is suppressed, the use of petroleum for power generation has come to be restricted internationally. In other words, the amount of oil used for power generation must be frozen at present. Therefore, when new equipment is installed due to deterioration of power generation equipment, it is necessary to switch to a power generation method with high thermal efficiency so as to cope with future increase in power demand without depending on increase in fuel consumption.

Further, in the combined cycle power generation by LNG, power generation with high thermal efficiency has already been performed, but LNG has a concern about stable supply as compared with crude oil because storage costs high.

In Europe and the United States, crude oil and residual oil have already been used as fuels for gas turbines, but impurities contained in them often cause troubles, and maintenance costs are higher than when diesel oil or LNG is used. Crowding problems have been pointed out. And as the impurity content of the oil fuel used for the gas turbine, the salt content is 0.5 ppm or less and the sulfur content is 0.0
It is desirable to limit the amount of vanadium to 5 wt% or less and vanadium to 0.5 ppm or less. In particular, salinity and vanadium interact with each other to lower the melting point of the blade metal of the gas turbine and cause ash to stick to the blade. The sulfur content is also set from the viewpoint of blade protection. Even low-sulfur crude oil such as the above-mentioned Minas crude oil and Daqing crude oil used as boiler-fired fuel cannot satisfy these standards, and the power generator is combined with a more efficient thermal efficiency from the conventional boiler by scraping and building. -There is a problem that low-sulfur crude oil cannot be used as it is as gas turbine fuel even if it is switched to cycle power generation.

[0007]

In view of the above problems, the inventors of the present invention have earnestly studied a method of using low-sulfur crude oil as a fuel for combined cycle power generation with high thermal efficiency, and as a result, the sulfur content in low-sulfur crude oil has been found to be high. A lot of relatively high boiling fractions,
In addition, the heavy metal content is concentrated in the distillation bottom oil to a high concentration, and therefore, the low boiling point oil compatible with the gas turbine fuel is obtained by simple topping that simply separates the low-sulfur crude oil into the high boiling point fraction and the low boiling point fraction. Distillate can be easily obtained, and by combining simple topping and combined cycle power generation, low heat energy that is difficult to be effectively used for power generation in an exhaust heat recovery boiler for combined cycle power generation can be used for the simple topping. It can be effectively used for heating low-sulfur crude oil, can further achieve energy saving in combined cycle power generation, and uses a methane-containing gas that is separated from the low-sulfur crude oil topping as a stripping gas for simple topping It has advantages such as smaller wastewater treatment load than ripping, and low sulfur To obtain a knowledge that can often collected gas turbine fuel from crude oil, it was possible to complete the present invention.

That is, the first aspect of the present invention is to heat low-sulfur crude oil with an exhaust heat recovery boiler for combined cycle power generation,
Then, a low boiling fraction and a high boiling fraction are separated by simple topping using a methane-containing gas separated from the low sulfur crude oil as a stripping gas, and the obtained low boiling fraction is used in the combined cycle power generation. A power generation method characterized in that it is used as a fuel for a gas turbine, and the second aspect of the present invention is to perform desalination treatment prior to simple topping,
The present invention also relates to a power generation method characterized in that low heat energy of the exhaust heat recovery boiler is utilized as a heat source for low-sulfur crude oil necessary for desalination treatment.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation of the combined cycle power generation method of the present invention will be described below with reference to a typical embodiment shown in FIG. In FIG. 1, only main equipment is shown and auxiliary equipment is omitted. In the present invention, the desalting step is not always essential, but it is preferable to provide it.
In that case, the heat energy required for the desalination treatment can be obtained from the exhaust heat recovery boiler of the combined cycle power generation, which is particularly preferable from the viewpoint of energy saving. FIG. 1 shows a case where such a desalting treatment step 5 is provided, and further, FIG.
The details of the desalting treatment step 5 are shown in FIG.

It is needless to say that the low-sulfur crude oil used in the present invention is preferably as low in sulfur content as possible, since it can simplify the desulfurization process of combustion exhaust gas, but usually, the sulfur content is 1% by weight or less, More preferably, 0.5% by weight or less of crude oil is used. Examples of such crude oil include the crude oil produced in Minas and the crude oil produced in Daqing, which are rich in wax as described above. The amount of vanadium contained in such crude oil is usually 0.4 to 0.5 ppm.
Minas crude oil is particularly preferable as the low-sulfur crude oil because it has a sulfur content of about 0.1% by weight or less.

Such low sulfur crude oil is heated in the exhaust heat recovery boiler 2 before being sent from the low sulfur crude oil tank 4 to the desalination treatment step 5. The heating temperature in the desalting treatment step 5 is a temperature suitable for electrostatic desalting, for example, a range of 80 to 150 ° C., and a temperature preferable for the viscosity and specific gravity of the crude oil used.
The heated low-sulfur crude oil is desalted using fresh water by the plurality of disorouters 51 in the desalination processing step 5 shown in FIG. The diso router is usually performed in 2-3 stages. FIG. 2 shows the case of three stages. The diso router mixes heated crude oil and fresh water and applies a static voltage of, for example, about 20,000 volts to agglomerate and separate water droplets to reduce the viscosity of crude oil and to separate water and crude oil due to the difference in specific gravity. To facilitate heating as described above. Such a crude oil desalting treatment technique itself is known. The salt content in the desalted crude oil is preferably as low as possible so as not to lower the melting point of the blade of the gas turbine, but is usually adjusted to 0.5 ppm or less, particularly preferably 0.3 ppm or less. Wastewater containing salt is treated in wastewater treatment equipment, and desalted crude oil is treated by the following simple topping.

The desulfurized low-sulfur crude oil has a temperature of 30 required for the operation of the first simple topper 6 in the exhaust heat recovery boiler 2 shown in FIG.
Heat to 0-350 ° C. The first simple topper 6 is basically operated under normal pressure, and a gas fraction is obtained from the top of the tower and a bottom oil is obtained from the bottom of the tower. In addition, an intermediate fraction containing fractions corresponding to heavy naphtha, kerosene, light gas oil, heavy gas oil, etc. can be obtained from the tower side. The overhead gas is cooled in a heat exchanger 10 together with the overhead gas of a second simple topper 8 which will be described later, and is gas-liquid separated in a condensing drum 11. The separated gas component is composed of hydrocarbons containing methane as a main component and having 1 to 3 carbon atoms. A part of this is supplied to the tower bottom of the second simple topper 8 described later as a stripping gas by the circulation blower 12, and the rest is compressed by the gas compressor 13 and supplied to the gas turbine 1. The fraction condensed on the condensation drum 11 corresponds to light naphtha and is added to a part of the gas turbine fuel. The middle distillate obtained from the tower side of the first simple topper 6 is the first stripper 7
Thus, the low boiling point fraction is returned to the first simple topper 6, and the rest is used as gas turbine fuel. The bottom oil of the first simple topper 6 is supplied to the bottom of the second simple topper 8 and topped by the stripping gas which is also supplied to the bottom of the tower. The second simple topper 8 is operated at normal pressure by the stripping gas containing methane as a main component, and a heating source is not usually required. The temperature of the second simple topper 8 is usually 300 to 360 ° C. The bottom oil highly concentrated in the second simple topper 8 has a boiling point of about 900 to 950 ° F, has a relatively high sulfur content, and contains heavy metals such as vanadium in a concentrated manner, and further desalted. When the treatment step 5 has not been carried out, the salt content is also contained in a concentrated form, so from the viewpoint of protecting the blades of the gas turbine, etc., it is not used as a gas turbine fuel, but is used as a boiler fuel or the like.

The distillate obtained from the tower side of the second simple topper 8 is separated into the reflux gas by the second stripper 9, and the heavy oil-equivalent fraction excluding it is added to the fuel for the gas turbine 1.

The ratio of the low boiling point fraction satisfying the above-mentioned criteria as the fuel of the gas turbine 1 from the low sulfur crude oil by the simple two-step topping in FIG. 1 is the kind of the crude oil used.
Although it depends on the operating conditions of the simple topper, the use conditions of stripping gas, etc., in the case of typical Daqing crude oil as an example, it is in the range of about 30 to 40 VOL%, and in the boiling point range about 80.
It is a fraction of 0 to 900 ° F or less. As described above, the high boiling point fraction (iso-bottom oil) that is not used in the gas turbine does not hinder the conventional boiler fuel for power generation, and contributes to the power generation by the steam turbine as usual.

Further, in the present invention, each of the low boiling fractions excluding the bottom oil of the second simple topper 8 obtained as described above is supplied to the gas turbine 1 at a high temperature without being actively cooled. Preferably. As a result, unlike the present invention, the power generation efficiency (thermal efficiency) of the gas turbine 1 is improved by the amount of heat required to heat the fuel to the temperature as compared with the case of using the fuel at room temperature obtained in another step. You can Moreover, the heat energy necessary for heating the fuel is originally obtained from the same exhaust heat recovery boiler of the gas turbine according to the present invention, and a relatively low (low temperature) heat energy that cannot normally contribute to power generation is obtained. This is a great advantage from the viewpoint of energy saving because it can be utilized. When using a gas turbine fuel that is produced in a separate process from low-sulfur crude oil, the fractionated fuel is once cooled and stored in a tank, or is cooled during storage and then transported to a power generation facility for fractionation. The required heat energy cannot be utilized in the gas turbine 1.

Further, as shown in FIG. 1, by combining desalination treatment and simple topping with combined cycle power generation, heat energy required for each process is not wasted in the next process as compared with the case where these processes are performed in separate processes. As a result, it will greatly contribute to the improvement of the amount of power generation per constant fuel.

The total heat efficiency of the bottom oil of the second simple topper 8 used in the conventional boiler as the heat generation efficiency according to the present invention depends on the fractional distillation ratio of the simple topping, but when the whole amount is heated by the boiler. The thermal efficiency is about 40% / HHV standard and the thermal efficiency when used for combined cycle power generation of all amount is about 48% / HHV standard. For example, in the case of Daqing crude oil, it can be improved to about 44-46 / HHV standard. . Moreover, since the distillate having a preferable quality as the fuel of the gas turbine 1 is used, maintenance of the gas turbine
It is also extremely advantageous in terms of inspection and blade replacement frequency.

As the stripping gas used for the simple topping, steam is usually used. But,
In steam stripping using steam, the heat energy is lost due to condensation, which is not only disadvantageous from the viewpoint of energy saving, but also the crude oil component is mixed in the condensed water, which makes difficult water treatment necessary for a large amount of wastewater. Become. A method of performing simple topping under reduced pressure is also adopted.
However, steam is usually used for depressurization, and it has the same disadvantages as steam stripping, and the depressurization adds cost to the construction of the device. In comparison with these, by using the stripping gas containing methane according to the present invention, those gas components originally contained in crude oil can be used, and there is almost no heat loss.
It has the advantage that it can be operated with the power required to achieve this, and that the wastewater treatment points are also greatly reduced, greatly simplifying the process. A method of fractionating oil such as crude oil using a methane-containing gas is known (Japanese Patent Laid-Open No. 61-133).
No. 289).

[0019]

As described above in detail, when supplying low-sulfur crude oil to the gas turbine, the present invention heats the low-sulfur crude oil with low heat energy of the exhaust heat recovery boiler, and uses methane as a main component. By simply topping the gas as a stripping gas and supplying the resulting low boiling fraction as a high temperature gas turbine fuel, more fuel suitable for a gas turbine can be collected from low sulfur crude oil at low cost, Power can be generated with good thermal efficiency. This is extremely advantageous from the viewpoint of not only energy saving but also prevention of global warming by CO ₂ generated by power generation and suppression of generation of harmful substances such as SOx. By combining the desalting treatment step in the present invention, the above effect is further improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a process to which the present invention is applied.

FIG. 2 is an explanatory diagram of a desalination process step to which the present invention is applied.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshiaki Ikuta Inventor Yoshiaki Ikuta 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Ltd. (72) Inventor Michio Nakajima 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd. (72) Inventor Masatoshi Shibata 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd.

Claims (2)

[Claims] 1. A low-boiling fraction is obtained by heating low-sulfur crude oil in an exhaust heat recovery boiler for combined cycle power generation, and then by simple topping using a methane-containing gas separated from the low-sulfur crude oil as a stripping gas. A power generation method, characterized in that a low boiling fraction obtained by separating into a high boiling fraction is used as a fuel for a gas turbine of the combined cycle power generation. 2. The low-sulfur crude oil is heated in an exhaust heat recovery boiler for combined cycle power generation to reduce the salt content by electrostatic desalination treatment, and the obtained high-temperature low-sulfur crude oil is further exhaust heat recovered. The power generation method according to claim 1, wherein the boiler is heated in a boiler and separated into a low boiling fraction and a high boiling fraction by simple topping.