DD235660A1 - PROCESS FOR STABILIZING COLD PRODUCTS IN DELAYED DECOMPOSITION - Google Patents

Abstract

The invention relates to a process for the preparation of the cleavage products which are formed in the delayed coking of coal-containing products, preferably tar pitch. The cleavage products are passed through a column in countercurrent to a quench oil at a system pressure of 0.25 to 1.15 MPa, preferably 0.5 to 1.0 MPa and cooled to 380 to 410C. The ratio quenchoel / cleavage product and the quench oil temperature are adjusted so that the amount of the vapor phase is reduced by 1 to 8%. The vaporous cleavage products or the condensed Fluessigprodukte be relaxed or promoted for tar fractionation.

Description

For this 1 page drawing

Field of application of the invention

The invention relates to a process for working up the cleavage products which are formed in the delayed coking of coal-based products, preferably of tar pitch. It can preferably be used in the production of high-quality electrode cokes according to the delayed coking principle.

Characteristic of the known technical solutions

The coking of high-boiling liquid fractions derived from petroleum or coal is a widely used process which produces, in addition to coke, a range of useful liquid and gaseous products.

In recent years, the coking of coal-based liquid products has become increasingly important. Either a pre-fractionated tar or pitch is used in the actual coking plant. This process is carried out predominantly according to the principle of stepwise heating (DRP 705576, DRP 746186) or the principle of delayed coking (BRD 1 935 467), the latter method because of its serious technical and

economic benefits are preferred as far as possible. .

Under certain circumstances, existing coking plants are reconstructed so that they work on the principle of delayed coking.

Both in the use of pre-fractionated tar and pitch, such processes include two technological systems for fractionation. Dassind the tar fractionation and fractionation of Koker fission products. The coking of pitch has the advantage over the use of pre-fractionated tar, on the one hand, that there is a minimum for the mass throughput and the energy expenditure. On the other hand, however, both fractionators must meet the ever-increasing conditions for fractionation sharpness, as required by the methods for the economic processing of tar oils. Due to the thermal instability of the products, the individual technological systems have to be realized with the smallest possible spatial distances.

Delayed coking is an alternating process. In the phases of steaming and cooling of the reactors, quanitatively and qualitatively strongly fluctuating products accumulate over time, which also have to be fractionated in a suitable manner. The complete separation of water and oil due to the small differences in density causes these products considerable difficulties.

Object of the invention

The object of the invention is to stabilize the Koker fission products so that they are processed without adverse effects and without increased energy use in the Fraktionierteil in which the Koker raw material is obtained, and if necessary be transported over larger territorial distances can.

Explanation of the essence of the invention

The invention has for its object to provide a method by which reduces the scope of the total consuming fractionators in the delayed coking of coal-based feed products and also the workup of such products as obtained in the vapors and cooling phase, can be performed in the case of the reconstruction of existing facilities, larger territorial distances between individual technological stages should be possible.

Surprisingly, it has been found that it is possible to dispense with a fractionation system in the coking plant and to recycle all the resulting Kokerspaltprodukte the operating phases coking, steaming and cooling in the tar distillation and to fractionate there, if the said products are stabilized in a suitable manner. Stabilization takes place in a quench system. This consists of two columns in which a high-boiling fraction is preferably circulated from the tar distillation at different temperatures and pressures. In dereinen column incurred during coking at a pressure of 0.3 to 1,2MPa and having a temperature of 400 to 500 ⁰ C cleavage products are stabilized by higher boiling fraction in an amount of 4 to 13%, based on the quenching by Total amount of fission products to be condensed. In this material and heat exchange at the same time evaporate low boiling components of the quench oil in a small amount, so that generally results in a reduction of the vapor phase of 1 to 8% / This summary condensation rate is in addition to the process parameters pressure and temperature and the composition of the products of the ratio depending on the products. The quench oil / coker cleavage product ratio is 0.1 to 2.0.

The operating pressure is within the limits of 0.25 to 1.15 MPa, depending on the length of the return line and the heat losses occurring here chosen so that on the one hand, the critical for the thermal instability temperature of 410 ⁰ C in the stabilization below and on the other hand in the pipeline does not reach or fall below the dew point temperature of the fission products. In this first stage of the quench system also subsequently formed or entrained coke particles are deposited.

When steaming and cooling of the coke falls on the head of the coke tower to a water vapor-oil vapor mixture. The ratio of water / oil changes from 1: 1 to 10: 1 during these processes. The temperature can be 130 to 500 ° C. The said vapors are passed through the other column at a pressure of 0.1 to 0.2 MPa in countercurrent to the quench oil, whose temperature is 70 to 100 ° C. The steam oils are almost completely condensed and passed together with the quench oil in the tar distillation. The remaining in the water vapor small amounts of oil from 2 to 15%, generally from 2 to 5%, can be separated by gravity after condensation of the steam without problems. The two columns are combined with each other and with the tar distillation technologically in such a way that resulting by quantity distributions and quality changes no disturbances of the stable operating regime in the tea distillation plant and that there the energy costs do not rise. The Koker cleavage products are predominantly vaporous, i. H. passed with the correspondingly high heat content in the Teerfraktioi.erung. The quench oil is recycled at a higher temperature than it was taken over. I η certain situations ζ. As in malfunctions or when decommissioning the tar distillation, it may be appropriate to coke over a limited period pitch without the cleavage products can be returned to the tar distillation. During this time, the Koker cleavage products are passed in succession through the two columns of the quench system and completely condensed. The liquid product is passed, for example, to the Einsatzteer tank. On the head of the first or second Quench column additionally anhydrous and hydrous oils of other process stages of the coking plant can be abandoned and thus returned to the process.

The technology according to the invention makes it possible to realize a total recirculation of the time-varying attack of intermediates and by-products without disturbing the continuity in the regime of the peer-producing fractionation column. A portion of the quench oil can also be added to the fission product line to quench the fission products. In addition, a small amount of hot or quench oil can be used for rinsing spaces which are constantly or temporarily not flowed through in the region of the reactor in order to prevent coking there.

embodiments

Reference to a drawing and the following examples, the inventive method will be explained in more detail:

Figure 1 illustrates the preferred technology without the invention being limited to this variant. The tar is added via the line 1 in the preheater 2. In the pitch separator 3 falls as a liquid product pitch. The vaporous products pass via the line 4 into the fractionating section 5, where gas, light oil, middle oil and tartar oil are separated. The product boiling higher than tar oil in the bottom of the column, the so-called hot oil, is recycled via line 6 to the feedstock. The pitch passes via the line 7 to the pitch preheater 8 and from there via the line 9 in the Koksturm 10th

A portion of the hot oil is moved via the line 11 to the container 12. It is cooled in the heat exchanger 13. From the container 12, the hot oil passes through the heat exchanger 13 and the conduit 14 into the container 15th

From tank 15 excess quench oil is added via line 16 to the hot oil recirculation. Of the containers 12 and 15 is added via the lines 17 and 18 quench oil to the top of the column 19 and 20 respectively.

The Koker cleavage products leave the coke tower at the top and pass via the line 21 into the column 20, where they are conducted in countercurrent to the quench oil. In this case, a partial condensation takes place depending on the selected process parameters. The vaporous products leave the column at the top and are expanded via the line 22 for tar distillation.

The illustrated technology represents only one of the possible variants. Thus, for example, the coker-cleavage products can not be passed via the line 21 directly to the column 20, but previously by another coker tower to its heating.

-3- 745 58

During steaming and cooling, steam or cooling water is added via line 25 into the coking tower. The resulting steam-oil vapor mixture is expanded via line 23 into the column 19. Here the oil components are condensed. The water vapor leaves the column at the top via the line 24. The fed into the column 19 vapors and, accordingly, the condensed therefrom liquid products only occasionally. The container 12 is dimensioned so that it can absorb these quantities. The contents of the container are discharged evenly over a constant amount. As a result, largely constant operating conditions in the entire quench system and a quantitatively and qualitatively approximately constant recovery for tea distillation are achieved.

In the event of complete condensation of the Koker cleavage products required in certain situations, the vapors are passed from the top of the column 20 via the line 26 into the column 19. The condensed cleavage products fall together with the quench oil in the container 12. The uncondensed gases are discharged via the line 24.

In other process stages of the coking plant resulting anhydrous and water-containing oils can be given to the head of the quench column 19 and 20 and processed in the respective system with. The supply of such products via the line 27th

Example 1:

In the reactor 10 brown coal smolder Weichpech is coked under a pressure of 0.9 MPa at a temperature of 46O ⁰ C. The resulting at the top of the reactor fission products are relaxed via line 21 into the quench column 20. As quench oil, part of the circulating bottoms product is fed to the tar distillation via the line 11.

The stabilization process is operated under the following conditions: Line Quantity Pressure

kg / h MPa

11 14 16 18 1200 0.85

21 4900 0.9

22 4670 '0.15

The _f ratio Quenchöl / Kokerspaltprodukt is 0.24 and the total condensation rate is 4.7%. The qualitative change in the Koker fission products can be seen above all at the end of the boiling point, as the following compilation of the indices of the boiling behavior shows:

temperature dew point temperature ⁰ C ⁰ C 345 317 348 200 456 456 403 321

management

5%

- True boiling curve -

50%

98%

11 352 ⁰ C. 14 284 ⁰ C 16 = 18 287 ⁰ C 21 22

456 ⁰ C 447 ⁰ C 447 ⁰ C 264 ° C 256 ⁰ C

567 ⁰ C 569 ⁰ C 580 ⁰ C 438 ⁰ C 425 ⁰ C

652 ⁰ C 66O ⁰ C 67O ⁰ C 506 ° C 458 ⁰ C

The temperature of the stabilized coker cleavage products returned to tar fractionation is 82K above the dew point temperature.

Example 2:

The same Koker cleavage product as described in Example 1 is stabilized under unchanged conditions under the following conditions:

management

Quantity kg / h

Pressure MPa

temperature

dew point temperature

3500 4900 4670

0.6 0.9 0.15

345 317 365 320 456 388

456 325

The boiling indexes for the products are:

- True boiling curve -

management

5%

50%

95%

98%

11 352 ⁰ C. 14 284 ⁰ C 16 = 18 296 ⁰ C 21 22

456 ⁰ C 447 ° C 445 ⁰ C 264 ⁰ C 256 ⁰ C

567 ⁰ C 569 ⁰ C 580 ⁰ C 438 ⁰ C 432 ⁰ C

652 ° C 66O ⁰ C 670 ⁰ C 506 ⁰ C 464 ⁰ C

There is a clear change at the end of the boiling trend. The temperature of the stabilized products is 63 K above the dew point temperature.

Example 3:

When steaming the coke with steam, a steam-oil vapor mixture is formed having the following composition:

water

C ₄ -minus hydrocarbons C ₅ -plus-hydrocarbons

47.6%

49.1%

The boiling indices of the C ₅ plus share are:

5%: 162 ⁰ C-True boiling curve 95%: 569 ° C-True boiling curve

The vapor mixture is passed from the top of the reactor into the column 19

 Here are the following process conditions:

Pressure MPa

management amount container kg / h 11 12 17 22155 23 5 249 24 2888

Temperature ° C

0.13 0.13 0.13 0.12

345 180 90 430 107

91.6% of the oil content is condensed. The oil content in the water vapor is 7.5% and the liquid density of the oil is <850 kg / m ³ . '_ , _.,.: _. ~ _r ~ _.... _: ".

Example 4:

When cooling the coke with cooling water, a steam-oil vapor mixture is formed having the following composition:

Water: 90.1%

C ₄ -minus hydrocarbons: 0.7%

Cs-plus hydrocarbons: 9.2%

The boiling indexes of the Caa share are:

5%: 162 ° C - True boiling curve 95%: 621 ° C - True boiling curve

The vapor mixture is passed from the top of the reactor into the column 19. The quenching process is carried out under the following conditions:

management amount container kg / h 11 12 17 13000 23 5,500 24 5120

Print ' temperature MPa ⁰ C 345 0.16 175 0.16 90 0.16 296 0.15 115 ^:

75.2% of the oil content is condensed. The oil content in the water vapor is 2.5% and the liquid density of the oil is <850 kg / m ³ .

Example 5:

In certain situations, such as after the decommissioning of the tar distillation, it may be necessary to coke still residual amounts of pitch without the recycling of the Koker fission products being possible for the soil destilation. During this time, the cleavage products are stabilized in the usual way in the column 20 and then passed into the column 19 for condensation. The release of excess quench oil for tar distillation is also not possible for the reasons mentioned. The resulting in the first column small amount is collected in the appropriately sized container 15. The condensed in the second column products are passed from the container 12 via the line 28, for example, to the Einsatzteertank and processed in the following phase of operation. The line 14 is shut off. The process described is carried out under the following conditions:

management amount container kg / h 18 1200 21 4900 26 4670 17 31220 24 1130 28 3540

Pressure MPa

Temperature ⁰ C

200

456

403

90

96

150

The boiling indexes for the products are:

management

5%

- True boiling curve -

50%

95%

98%

18 21 26 17 24

287 ⁰ C

175 ⁰ C

447 ⁰ C 264 ° C 256 ° C 373 ⁰ C

580X 438 ° C 425 ° C 520 ⁰ C 137 ° C

67O ⁰ C 506 X 458 X 550X 175 X

The cumulative condensation rate in the column 20 is 4.7%. In the column 19, a further 72.2% of the discharged from the reactor 10 Koker fission products are condensed. The uncondensed products in a size of 23.1% are discharged via the line 24. This mass flow consists of non-condensable gases and vapors of low-boiling products.

Examples:

The same cleavage product as described in Example 1 is passed into the quench column 20 for stabilization. At the same time a process oil, which is obtained in the gravity separation of a water-oil mixture in another technological stage of the coking plant, abandoned via the line 27 to the head of the column 20. The process is operated under the following conditions:

management

Quantity kg / h

Pressure MPa

temperature dew point temperature ⁰ C X 345 317 339 200 456 456 30 401 319

11 14 16 18 21 27 22

700 4900

300 4988

The boiling indexes for the products are:

management

5%

- True boiling curve -

0.85 0.9 1.0 0.15

50%

98%

11 352x 14 284x 16 = 18 283 X 21 27 9OX 22

456 X 447 ⁰ C 447 ⁰ C 264 X 211 X 251 X

567 X 569 X 438 58o C ^{0 0} C 322 X 417 X

652 X 660X 670X 506 ⁰ C 360X 452 X

As a result of the partial condensation of high-boiling fractions in the Koker cleavage product during stabilization, there is above all a change in the boiling point. The difference between the process temperature and the dew point temperature is 82 K-. The additionally supplied process oil is due to its Siedelage almost completely with the vaporous coker

Claims (5)

Invention entitled; 1. A process for the stabilization of fission products, which arise in the delayed coking of kohlestämmigen products, preferably from Teerpech, under a pressure of 0.3 to 1.2 MPa and a temperature of 400 to 500 ⁰ C, characterized in that the cleavage products in Countercurrent to a quench oil at a system pressure of 0.25 to 1.15 MPa ₁ Prev ₁ to 1.0 MPa, passed through a column and cooled to 380 to 410 ° C, the quench oil / cleavage ratio and the quenching oil temperature are adjusted so in that the amount of the vapor phase is reduced by 1 to 8%, preferably 1 to 5%, and these vaporous cleavage products or the condensed liquid products for tar fractionation are expanded or conveyed. 2. The method according to item 1, characterized in that as quench oil, a subset of higher than the tar oils, that is used in the range of 240 to 600 ° C sump return from the tar fractionation and in a ratio Quenchöl / Koker-SpaltproduktvonOJ to 2.0 with a temperature of 200 to 38O ⁰ C is added to the quench column. 3. The method according to item 1 and 2, characterized in that the obtained during steaming and cooling of the coke water vapor-oil vapor mixtures are passed through a second column of quench, in which at a pressure of 0.1 to 0.2 MPa to 70 to 100 ⁰ C cooled Quenchöl ini countercurrent to the vapor phase flows and the discontinuously occurring condensed steam oils are fed continuously with a constant amount together with the quench oil to the first quench column. 4. The method according to item 1 to 3, characterized in that the stabilized Koker cleavage products are passed into the second quench column and the condensed hydrocarbons are discharged together with the quenching oil to Einsatzteerbehälter or in a storage container. 5. The method according to item 1 to 3, characterized in that in other process stages of the coking plant resulting anhydrous and also water-containing are abandoned on the head of the first or second quench column.