JPS6159358B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cleaning and desalination of fuel oil for gas turbines, and particularly to a cleaning and desalination method and apparatus that utilize centrifugal force.

Gas turbines are widely used for power generation and other purposes because they can generate large amounts of power with small devices.
Since gas turbines have a structure in which power is obtained by blowing high-temperature gas produced by twisting and burning fuel oil onto blades, impurities in the fuel oil cause corrosion and wear problems. There are various impurities that cause these problems, but Na and K salts are the main causes of corrosion, and it is necessary to remove these salts from fuel oil, that is, desalinate. must be kept below several ppm, preferably below 1 ppm. Also, the main cause of wear is solid matter such as sand grains, which must be removed.

Solids in fuel oil can be removed with a filter.
Na and K salts mainly combine with Cl and are dissolved in the form of NaCl and KCl in water, which is present in a small amount in fuel oil, or in the form of minute solids in fuel oil. Since these salts dissolve in water, a simple method for removing Na and K salts is to wash the fuel oil with water, move the Na and K salts toward the water, and then separate this water from the fuel oil. However, as is well known, when fuel oil and water are mixed and stirred, an emulsion is formed, making it impossible to separate water and fuel oil. For this reason, in general, a chemical to prevent emulsion (hereinafter referred to as an emulsion breaker) is added to the fuel oil, and further, by using centrifugal force,
Separation is achieved using static electricity.

The structure of a commonly used centrifugal separator consists of a rotor that rotates at high speed and an outer circumferential wall surrounding it, a pipe for introducing a mixture of fuel oil and water into the rotor, and a pipe for introducing a mixture of fuel oil and water into the rotor. There are pipes for discharging each oil and a sludge discharge port provided on the outer peripheral wall. When the mixed liquid is introduced into the rotating rotor, the mixed liquid is separated into fuel oil, water, and sludge by strong centrifugal force.The fuel oil and water pass through their respective discharge ports, and the sludge with poor fluidity is removed from the outer peripheral wall. It can be discharged by ejecting it from the small hole.

Desalination using this centrifugal separator involves mixing and washing of fuel oil with water, separation of a fuel oil and water mixture, that is,
A combined wash-separation combination is used. A conventional example will be explained below with reference to FIG. In the figure, 1 is the first
stage centrifugal separator, 1' is a second stage centrifuge, 2 is a fuel oil tank, 3 is an emulsion breaker, 4 is a mixer, 5 is a pump, 7 is a filter, 10 is raw fuel oil, 11 is cleaning oil, 12 is clean water, 13 is waste water, 14 is sludge, 15 is an emulsion breaker, and 16 is washing water.

In the fuel oil tank 2, large solid substances are removed by sedimentation or the like. An emulsion breaker 15 and washing water 16 are added to raw fuel oil 10 drawn out from a fuel oil tank 2 by a pump 5, and these liquids are mixed in a mixer 4 to thoroughly wash the fuel oil. The fuel oil that has been mixed and washed in the mixer 4 is transferred to the first stage centrifugal separator 1.
to go into. Here, fuel oil, water, and sludge are separated by the action of centrifugal force, and the water becomes wastewater 13 and is led together with sludge 14 to the next treatment step. water,
The fuel oil from which the sludge has been removed is further thoroughly mixed with wash water 12, an emulsion breaker 15, and a mixer 4, and is then washed. Then the second stage centrifuge 1'
The oil is separated into oil, water, and sludge, and the oil becomes cleaning oil 11. It passes through a filter 7 to remove solids from the cleaning oil, and is stored in a predetermined tank as gas turbine fuel.

As described above, the raw material fuel oil 10 is mixed with water, washed, and then separated using a centrifugal separator, which is desalted and refined by repeating so-called mixed washing and separation.
The water used for cleaning (clean water 12) is water that is low in Na and K salts, and the water after cleaning contains a large amount of Na and K salts, as well as other impurities in the fuel oil. If treated to remove these substances, it can be reused as washing water, but for economic reasons, it is generally treated as wastewater. The amount of water for cleaning is sufficient to sufficiently wash the fuel oil by mixing and stirring, and is usually used in an amount of about 5 to 10% of the amount of fuel oil.

As described above, in the past, the main focus was on desalination, and the cleaning water and fuel oil were separated by introducing an emulsion breaker to refine the fuel oil. In the above method, the filter 7 was clogged with minute solids, and the filter 7 had to be cleaned frequently.

Since desalination of fuel oil involves removing Na and K salts that are easily dissolved in water, it is sufficient to wash the fuel oil with water and separate the introduced water from the fuel oil. However, mixing water and fuel oil creates an emulsion that cannot be separated, so a method is usually adopted in which an emulsion breaker is introduced to separate the oil and water.

In order to eliminate the above-mentioned drawbacks, the present inventors have investigated the properties of sludge and emulsion. When fuel oil is placed in a container and left to stand still, a layer of sludge forms at the bottom of the container, and the sludge layer contains sand, sand, etc. In addition to solid materials such as iron pieces, solid wax and water droplets are mixed in, creating a highly viscous layer. Also, Na and K salts are dissolved in the water droplets in the sludge. These water droplets are hardly destroyed by strong centrifugal force to form a water layer. Removal of the sludge involves removal of solid matter and water droplets, that is, removal of Na, K salts.

When a small amount of water is mixed into fuel oil, the water breaks down into water droplets and dissolves into oil. When a strong centrifugal force is applied to this water-dispersed oil, an oil layer and a layer of water droplets are formed, with almost no water layer forming. The layer of water droplets is called sludge. Therefore, by putting water in oil and mixing it, water droplets containing solid salts such as Na, Na salts, etc. in the oil are collected in the input water, and a layer of water droplets, or sludge, is created by centrifugal force. Na, K can also be removed by removing sludge.
Can remove salt and solids. The viscosity of the sludge is high as mentioned above. Therefore, the solids in the sludge will not separate from the sludge even in a strong centrifugal force field.

From the above, it is clear that Na, K salts, and solids can be removed from fuel oil by removing sludge from fuel oil and by adding water to fuel oil to create sludge and removing it.

FIG. 2 shows an embodiment of the invention. The raw material fuel oil 10 flows through the first-stage centrifugal separator 1 and the second-stage centrifugal separator 1' in this order, and is led to the next step through the filter 7. In the first stage centrifugal separator 1, raw fuel oil 1
Excluding sludge in 0. Thus solids and most of the Na, K salts are removed. In the fuel oil from which the sludge has been removed, there are some water droplets accompanying the flow of the main oil, so Na and K salts are not sufficiently removed.
Clean water 12 is added to the main oil, and this is dispersed into water droplets by stirring and mixing using a mixer, and the dispersed oil is introduced into the second stage centrifugal separator 1'. A layer of water droplets, or sludge, is formed in the introduced oil due to centrifugal force.
By removing this sludge, cleaning oil 11 with a low content of Na and K salts can be obtained. The clean water 12 used here is contained in the sludge and can be removed from the oil, but some of it accompanies the oil flow. For this reason,
If the concentration of NNa and K salts is high, the concentration of these salts in the cleaning oil 11 will increase, which is not suitable. Since about 1000 ppm of water often remains in oil, it is desirable to use water with a Na and K salt concentration of 1000 ppm.

By the above method, solids in fuel oil,
Na and K salts can be removed without using an expensive emulsion breaker.

According to an experiment in which the amount of clean water 12 was 1.5% of the oil, crude oil with a Na concentration of 20 ppm was the first.
The concentration was reduced to 3 ppm at the exit of stage centrifuge 1, and to 0.5 ppm at the exit of second stage centrifuge 1', and no particles with a diameter of 5 microns or more were found in this oil. Further, the water content in cleaning oil 11 was 1000 ppm. The greater the ratio of clean water 12 to oil, the better the cleaning effect. However, when the proportion is less than 2%, the water concentration in the cleaning oil 11 is small and there is little change in the proportion, but when the proportion is 2% or more, the concentration increases. For this reason,
The input ratio of clean water 12 is desirably about 2% or less.

The amount of Na and K salts contained in sludge water such as crude oil is large. In the first stage centrifugal separator 1, entrainment of water droplets in the sludge in the outlet oil is physically unavoidable. For this reason, the concentration of Na and K salts in the oil from the first stage centrifugal separator 1 is not sufficiently reduced. Therefore, two or more stages of centrifugal separators are required, and the installation of two or more stages of centrifuges according to the present invention is inevitable.

There may be cases where it is necessary to further reduce the amount of water in the cleaning oil depending on the requirements of the next process.

FIG. 3 shows another embodiment of the present invention. In the figure, 1" is a third stage centrifugal separator, and the oil entering the third stage centrifugal separator 1" is fed into the emulsion breaker 15 and then mixed. Stir and mix at step 4. Due to this structure, a small amount of water droplets contained in the oil that has undergone cleaning treatment is broken by the emulsion breaker 15 or coalesced, and the water droplets are mixed into water in the third stage centrifugal separator 1''. The oil becomes a layer, allowing separation of water and oil, and reducing the moisture in the cleaning oil 11.Since the amount of moisture in the oil entering the machine 1'' is small, the amount of emulsion breaker 15 to be introduced can be small.
The present invention has the effect of reducing the amount of water in the cleaning oil 11 and reducing the amount of emulsion breaker consumed.

In some cases, like heavy oil B, there is almost no sludge in the feedstock fuel oil 10. In this case, cleaning oil 11
can be added to create a sludge to remove solids and Na and K salts.

Next, FIG. 4 shows still another embodiment of the present invention, in which a mixer 4 is installed in front of the first stage centrifugal separator 1, and clean water 12 and raw fuel oil 10 are fed into the main machine 1. Arrange so that they can be mixed before entering. With this structure, the clean water 12 is dispersed in the raw fuel oil 10 to form a group of water droplets, and the group of water droplets forms a layer in the first stage centrifugal separator 1 to form a sludge, and by removing this sludge. Solids, Na and K salts can be removed.
In the method of the present invention, solid matter and Na and K salts can be removed even when there is no sludge in the raw fuel oil 10.

As explained above, according to the present invention, since solid matter can be removed, clogging of the filter 7 can be eliminated, and furthermore, without using an emulsion breaker,
Another advantage is that Na and K salts can be removed by using a small amount.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a conventional fuel oil desalination method, and FIGS. 2 to 4 are explanatory diagrams showing respective examples of the fuel oil desalination method according to the present invention. DESCRIPTION OF SYMBOLS 1...1st stage centrifugal separator, 1'...2nd stage centrifugal separator, 1''...3rd stage centrifugal separator, 4...Mixer, 7...Filter, 10...Material fuel oil, 11...
...Cleaning oil, 12...Clean water, 14...Sludge,
15... Emulsion breaker.

Claims (1)

[Claims] 1. A fuel oil desalination method in which centrifugal separators are installed in multiple stages in series with the flow of fuel oil to desalinate the fuel oil,
A fuel oil characterized in that sludge contained in the fuel oil is removed in a first-stage centrifugal separator, and only water is added to the fuel oil after the sludge has been removed, and the mixture is charged into a second-stage centrifugal separator. Desalination method. 2. A fuel oil desalination method according to claim 1, characterized in that three or more stages of centrifugal separators are installed and only an emulsion breaker is added to the fuel oil fed into the final stage centrifugal separator. .