Method and device for preparing a vanadium-containing combustible

Abstract

A method and a device for preparing a vanadium-containing combustible in a de-asphalting device. In this way, a vanadium-containing combustible is supplied to a de-asphalting unit via a supply line in a de-asphalting device, wherein the vanadium-containing combustible supplied into the de-asphalting unit forms a first mass flow and a substantially de-asphalted combustible is discharged from the de-asphalting unit via a discharge line. A bypass line is connected to the supply line, wherein, via the bypass line, a second mass flow of the vanadium-containing combustible is directed past the de-asphalting unit in parallel to the first mass flow and supplied to the discharge line, such that a combined mass flow is formed in the discharge line.

Claims

1. A method for preparing a vanadium-containing combustible, provided for combustion in a gas turbine, in a deasphalting device, the method comprising: feeding a vanadium-containing combustible by way of an infeed line to a deasphalting unit, wherein the vanadium-containing combustible fed into the deasphalting unit forms a first mass flow; discharging a substantially deasphalted combustible from the deasphalting unit by way of a discharge line; wherein a bypass line is connected to the infeed line; directing a second mass flow of the vanadium-containing combustible by way of the bypass line in a manner parallel with the first mass flow past the deasphalting unit and feeding to the discharge line, wherein a merged mass flow is formed in the discharge line; wherein a control valve is disposed in the infeed line, and the bypass line is connected to the control valve; measuring an exit concentration of vanadium in the merged mass flow by a measuring device disposed in the discharge line; and controlling a ratio between the first mass flow and the second mass flow by the control valve so as to proceed from the exit concentration of vanadium measured in the merged mass flow.

2. The method as claimed in claim 1, wherein an entry concentration of vanadium in the vanadium-containing combustible ahead of the control valve is additionally measured by a further measuring device, and the ratio between the first mass flow and the second mass flow is controlled conjointly with the exit concentration of vanadium in the merged mass flow by the control valve.

3. The method as claimed in claim 1, wherein an entry concentration of vanadium in the vanadium-containing combustible is measured.

4. The method as claimed in claim 1, wherein the first mass flow is set to approximately 2/3 and the second mass flow is set to approximately 1/3 of the vanadium-containing combustible.

5. A deasphalting device for purifying a vanadium-containing combustible, provided for the combustion in a gas turbine, comprising: a deasphalting unit which by way of an infeed line is capable of being fed a vanadium-containing combustible which forms a first mass flow, and from which deasphalting unit a substantially deasphalted combustible is capable of being discharged; a bypass line which connects the infeed line to a discharge line such that the vanadium-containing combustible in a second mass flow is capable of being directed past the deasphalting unit and fed to the substantially deasphalted combustible, and a merged mass flow is formed; and a measuring device and a control valve disposed in the infeed line; wherein the bypass line connects the control valve to a connector in the discharge line, and wherein the measuring device after the connector of the bypass line is disposed in the discharge line such that an exit concentration of vanadium in the merged mass flow is measurable, and a ratio between the first mass flow and the second mass flow is capable of being controlled by the control valve so as to proceed from the exit concentration of vanadium measured in the merged mass flow.

6. The deasphalting device as claimed in claim 5, further comprising: a further measuring device disposed in the infeed line ahead of the control valve, an entry concentration of vanadium in the vanadium-containing combustible being capable of being additionally measured by said further measuring device, and the ratio between the first mass flow and the second mass flow being capable of being controlled by the entry concentration of vanadium in the in the vanadium-containing combustible and the exit concentration of vanadium in the merged mass flow.

7. The deasphalting device as claimed in claim 5, wherein an entry concentration of vanadium in the in the vanadium-containing combustible is measured.

8. The deasphalting device as claimed in claim 5, wherein the first mass flow corresponds to approximately 2/3 and the second mass flow corresponds to approximately 1/3 of the vanadium-containing combustible.

9. The deasphalting device as claimed in claim 5, wherein the first mass flow and the second mass flow correspond in each case to approximately half the vanadium-containing combustible.

10. The method as claimed in claim 1, wherein the first mass flow and the second mass flow are in each case set to approximately half of the vanadium-containing combustible.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the invention will be explained in more detail hereunder by means of figures in which:

(2) FIG. 1 shows a schematic illustration of a deasphalting device having a bypass line;

(3) FIG. 2 shows a schematic illustration of a deasphalting device having a bypass line, a control valve, and a measuring device; and

(4) FIG. 3 shows a schematic illustration of a deasphalting device having a bypass line, a control valve, a measuring device ahead of the control valve, and a further measuring device after the connector in the discharge line.

DETAILED DESCRIPTION OF INVENTION

(5) FIG. 1 shows the deasphalting device 1 according to the invention for purifying vanadium-containing combustible. The deasphalting device 1 comprises a deasphalting unit 4 which by way of an infeed line 3 is capable of being fed a vanadium-containing combustible 2 which forms a first mass flow 5. A substantially deasphalted combustible 6 is capable of being discharged from the deasphalting unit 4 by way of a discharge line 7.

(6) The deasphalting device 1 moreover comprises a bypass line 8 which connects the infeed line 3 to the discharge line 7 such that the vanadium-containing combustible 2 in a second mass flow 9 is capable of being directed past the deasphalting unit 4. The vanadium-containing combustible 2 by way of the bypass line 8 is fed to the substantially deasphalted combustible 6 from the deasphalting unit 4, mixing so as to form a merged mass flow 10.

(7) The following mass balance applies in the discharge line 7:
m.sub.pc.sub.p=m.sub.D,outc.sub.D,out+m.sub.BP.sub.cF(where m.sub.P=m.sub.D,out+m.sub.BP) where m.sub.P=merged mass flow 10 c.sub.P=vanadium concentration in the merged mass flow 10 m.sub.D,out=first mass flow 5 having a substantially deasphalted combustible 6 (minus vanadium flow m.sub.A) c.sub.D,out=vanadium concentration of the substantially deasphalted combustible 6 m.sub.BP second mass flow 9 having a vanadium-containing combustible c.sub.F vanadium concentration in the vanadium-containing combustible 2

(8) By virtue of the mixing of the substantially deasphalted combustible 6 (m.sub.D,out) and the vanadium-containing combustible 2 (m.sub.BP) so as to form the merged mass flow 10(m.sub.P), the following applies: since the vanadium concentration in the vanadium-containing combustible 2 (c.sub.F) is higher than in the merged mass flow 10(c.sub.P), the vanadium concentration (c.sub.D,out) of the substantially deasphalted combustible has to be lower than the vanadium concentration (c.sub.P) in the merged mass flow 10. The nominal value c.sub.P is typically in the range of 8 ppm, such that c.sub.D,out must be lower than 8 ppm, this by virtue of the readily attainable depletion ratio of 2/3 for typical crude oils having fewer than 24 ppm vanadium being technically implementable.

(9) It applies in general that the higher the vanadium concentration (c.sub.F) in the vanadium-containing combustible, the higher the first mass flow 5 (m.sub.D,in) to be deasphalted must be in order to be able to attain the nominal value (c.sub.P,nom).

(10) The invention is based on that only one first mass flow 5 (m.sub.D,in) of the vanadium-containing combustible 2 (crude oil feed flow m.sub.F, feed exit concentration c.sub.F) is directed as an inlet flow to the deasphalting unit 4 and cleaned therein, while a second mass flow 9 (m.sub.BP) in the bypass line 8 is directed past the deasphalting unit 4. The advantage of the bypass line 8 lies in particular in that only part of the feed flow (m.sub.F) has to be deasphalted. Consequently, the deasphalting unit 4 can be constructed so as to be smaller than in the case of the treatment of the entire mass flow (m.sub.F) of the vanadium-containing combustible 2. Accordingly, significantly lower investment and operating costs arise for the cleaning of the oil, on account of which it becomes evident that the implementation of this invention enables an operation in the range of the economical optimum.

(11) For example, if the vanadium concentration in the vanadium-containing combustible 2 (c.sub.F) is 12 ppm, in the case of a typical depletion rate of approx. 2/3 vanadium is depleted to (c.sub.D,out) 4 ppm. When the desired nominal concentration in the merged mass flow 10 (c.sub.P,nom) is 8 ppm, a ratio between the second mass flow 9 (m.sub.BP) and the first mass flow 5 (m.sub.D,in) of 1:1 is predefined in order for the desired mean of 8 ppm to result from 4 ppm and 12 ppm (in reality, m.sub.D,in must be slightly higher since a small part of this flow is diverted as a vanadium byproduct and is no longer available in the product oil).

(12) When only half of the vanadium-containing combustible 2 has to be deasphalted, the size of the deasphalting unit 4 can be halved; halved operating costs for the deasphalting can likewise be expected. The economy of the method is heavily improved.

(13) For highlighting, the method variant without a bypass circuit is to be contrasted. Here, the entire vanadium-containing combustible would be fed to the deasphalting unit 4 (m.sub.D,in=m.sub.F); accordingly, significantly higher investment and operating costs would have to be taken into account for cleaning the oil. The only advantage would lie in a lower vanadium concentration of 4 ppm in the final product stream (c.sub.P=c.sub.D,out). This extra reduction in the vanadium concentration as compared to the 8 ppm set by way of the bypass line 8 would however enable only minor additional savings in the costs for servicing the gas turbines. Said servicing costs would be significantly lower than the additional costs for the larger deasphalting unit 4 to be dimensioned, on account of which it becomes evident that the variant without the bypass line 8 does not correspond to the economical optimum.

(14) The split ratio between the second mass flow 9 (m.sub.BP) and the first mass flow 5 (m.sub.D,in) according to the invention is fixedly set based on a comparison of the vanadium nominal concentration (c.sub.P,nom) and the given actual concentration (c.sub.P).

(15) FIG. 2 shows the deasphalting device 1 illustrated in FIG. 1, but a measuring device 12 and a control valve 11 disposed in the infeed line 3 are furthermore comprised. The bypass line 8 connects the control valve 11 to a connector 16 in the discharge line. The measuring device 12 in the discharge line 7 is disposed after the connector 16 of the bypass line 8 such that the concentration of vanadium in the merged mass flow 10 is capable of being measured. A ratio between the first mass flow 5 and the second mass flow 9 is capable of being controlled by the control valve 11, proceeding from the concentration of vanadium measured in the merged mass flow 10.

(16) To this end, the vanadium concentration is determined in the measuring device with the aid of an analytical method. An in-line method which enables a fast determination of vanadium and thus fast controlling of this split ratio is advantageously used. In the case of an in-line method not being able to be used, it is possible for the vanadium concentration to be determined by an off-line method and for the measured value (c.sub.P) to be subsequently made available to the control valve 11.

(17) The closed control loop for setting the split ratio according to the invention includes a control valve 11 such as a three-way control valve or the combination of two control valves for setting the first and the second mass flow 5, 9 (m.sub.D,in and m.sub.BP).

(18) FIG. 3 shows a deasphalting device 1 having a further measuring device 15 which is disposed in the infeed line 3 ahead of the control valve 11. The further measuring device by measuring determines the entry concentration 13 of vanadium in the vanadium-containing combustible 2. The ratio between the first mass flow 5 and the second mass flow 9 is thus capable of being controlled by means of the entry concentration 13 of vanadium and of the exit concentration 14 of vanadium in the combustible.

(19) The vanadium entry concentration 13 (c.sub.F) in the vanadium-containing combustible 2 (m.sub.F) is thus also measured in addition to the vanadium concentration 14 in the merged mass flow 10 (c.sub.F). Both signals can be combined for advantageously controlling the split ratio. As soon as experience values pertaining to the correlation between the split valve setting of the control valve 11 and the typically attained vanadium concentration (c.sub.P) in the merged mass flow 10 (m.sub.P) are available, the entry concentration 13 (c.sub.F) can thus be used for controlling the split ratio in the control valve 11, as long as the exit concentration 14 of the vanadium (c.sub.P) does not depart from a permitted bandwidth about the nominal value (c.sub.P,nom). The advantage of this control mechanism lies in that a significantly faster reaction to changes in the entry concentration 13 is possible.

(20) Both measuring devices 12 and 15 advantageously measure the concentrations (c.sub.F and c.sub.P) by way of the same analytical apparatus. In order for in-line analytical methods to be carried out, two specimen lines are installed to this measuring apparatus.

(21) It is thus demonstrated by way of the invention how the technical possibility of implementing high depletion rates can be utilized in a profitable manner.