Method for extraction of acrylonitrile, methacrylonitrile or hydrogen cyanide

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for extraction of acrylonitrile, methacrylonitrile or hydrogen cyanide obtained from the reaction flow in the ammoxidation reaction of propane, propylene or isobutylene that involves passing the reactor flow through absorption column, extraction column and head fraction column. Method involves using such regimen of the process to prevent formation of an aqueous phase above feeding plate in the head fraction column. Method provides reducing unfavorable polymerization of hydrogen cyanide that provides significant decreasing or excluding stoppage of the head fraction column.

EFFECT: improved method for extraction.

12 cl, 1 dwg, 7 ex

 

Summary of invention

The present invention is directed to an improved method for the production of Acrylonitrile or Methacrylonitrile. In particular, the present invention is directed to improvement of the processing head of the faction or the separation of HCN in the column head of the faction in the extraction process of Acrylonitrile and Methacrylonitrile. The inventor has discovered a previously unknown relationship between the formation of undesirable polymer HCN in the column head of the faction and the formation of water a second liquid phase in the column head of the faction on a nutrient plate. The present invention is directed to preventing the formation of an aqueous phase in the column head of the faction on a nutrient plate, since the presence of this aqueous phase causes the formation of undesirable and harmful HCN polymer. Previously known technical solutions were aimed at reducing the pressure in the column head of the faction, resulting in lower operating temperatures and a marked reduction in the rate of polymerization of HCN. The present invention is directed to the destruction of the mechanism of HCN polymerization, which proceeds as ionic polymerization in the aqueous phase. Through the use of the present invention can be reduced undesirable polymerization of HCN, and the blockage (clogging) of the column head of the faction can be su is the natural enemy is reduced or eliminated, this can be achieved increased production of desirable products.

The scope of the invention

The present invention relates to the creation of an improved method for the production of Acrylonitrile or Methacrylonitrile. In particular, the present invention is directed to improving the extraction and separation of hydrogen cyanide in the column used in the production of Acrylonitrile or Methacrylonitrile.

Removing Acrylonitrile and/or Methacrylonitrile obtained by ammoxidation of propane, propylene or isobutylene in an industrial scale, produced by quenching flow reactor with water, followed by passing a gas stream containing obtained by blanking Acrylonitrile or Methacrylonitrile and HCN as a by-product in the absorber, where the water and the gases come into contact in countercurrent to remove mainly the whole Acrylonitrile or Methacrylonitrile. Water stream that contains HCN and Acrylonitrile or Methacrylonitrile, then passed through a series of distillation columns and United with them decanter for separation and purification of the product as Acrylonitrile or Methacrylonitrile from the steam flow, which contains mostly whole HCN.

A typical system of extraction and purification, which are used in the process of obtaining Acrylonitrile or metacril is itril, described in U.S. patent 4234510 and 3885928. Summary of invention

The first objective of the present invention is to provide an improved method for extraction and separation of by-product of HCN in the production of Acrylonitrile or Methacrylonitrile.

Another objective of the present invention is to provide an improved method for extraction of Acrylonitrile, Methacrylonitrile or HCN derived from the flow reactor ammoxidation reaction of propane, propylene or isobutylene, which provides for the transmission of a stream of the reactor through an absorption column, the column extraction and column head of the faction, and the improvement is that the column head of the faction works in such a way that suppressed the formation of the aqueous phase above the nutrient plates of the column head of the faction.

An additional object of the present invention is to provide an improved method for extraction of Acrylonitrile, Methacrylonitrile or HCN derived from the flow reactor ammoxidation reaction of propane, propylene or isobutylene by such a mode of operation of the column head of the faction, which inhibits the formation of the aqueous phase above the nutrient plates of the column head of the faction, so that increases the coefficient of irrigation; and use the side of the decanter for rossalini and removal of the aqueous phase from the column; used cooler feed stream to enhance the removal of light fractions in the column, and use the increased number of plates of the distillation of light fractions; use intermediate capacitor on the supply stream in addition to the capacitor upper shoulder strap; subcooled flow irrigation; increased capacity of reboiler and capacitor upper shoulder straps for increased costs of irrigation; control working pressure for shifting the equilibrium between two liquid phases; and other methods known in the art, which allow to improve the performance of reboiler, and the resulting efficiency of the distillation in the column head of the faction. The increase in irrigation hydrogen cyanide or cyanide concentrations of hydrogen higher nutrient plates can also be achieved through higher levels of HCN production to eliminate the second liquid phase. Any increase in the efficiency of the plates can also improve the efficiency of distillation and is useful for eliminating unwanted second liquid phase.

Another object of the present invention is to provide an improved method for extraction of Acrylonitrile, Methacrylonitrile or HCN derived from the flow reactor ammoxidation reaction of propane, propylene or isobutylene, which provides for transmission on the eye of the reactor through an absorption column, column extraction and column head of the faction, and the improvement lies in the fact that serves an excess of HCN in the column head of the faction, or create such a mode of operation of the ammoxidation reactor, which creates a higher concentration of HCN relative to other products, or produce re-introduction of HCN in the column head of the faction, to ensure that the work of the head of the column fractions, which reduces or eliminates the formation of undesirable aqueous phase.

These and other advantages and features of the invention will be more apparent from the subsequent detailed description, given as an example having no limiting character and in the claims, in which dedicated a special combination of tools to provide such advantages and features of the invention. In accordance with the present invention, advantages and features of the invention can be achieved by a method, which provides for the transportation of the flow reactor, obtained during the ammoxidation of propane, propylene or isobutylene, in the column of damping, in which the hot exhaust gases are cooled by contact with the sprayed water, and then cooled top zipper flow reactor enters the absorption column, in which HCN and raw and elontril or Methacrylonitrile absorbed in water, and then an aqueous solution that contains HCN and Acrylonitrile or Methacrylonitrile, plus other impurities, is passed to the first distillation column (column extraction), in which a substantial portion of the water and impurities are removed in the form of liquid cubic product, while HCN, water, a small proportion of impurities and Acrylonitrile or Methacrylonitrile discharged in the form of steam flow of the upper shoulder strap. This steam thread the top of the shoulder strap is further cooled using a heat exchanger and is sent to the decanter for separating and condensing fluids that return to the extraction process, while the rest of the steam flow is directed into the torch, a furnace for burning waste or other means of waste disposal. The organic stream is sent to the column head of the faction for the Department of HCN from Acrylonitrile.

In accordance with the first preferred embodiment of the present invention, the method is applied to the flow reactor, which is obtained by ammoxidation of propane or propylene, ammonia and oxygen, in order to obtain Acrylonitrile.

In accordance with another predpochtitelnei of the embodiment of the present invention, the flow reactor are due to the reaction of propane, propylene, ammonia and air in the reactor with a fluidized bed, in contact with psevdoozhizhennom is at the forefront of the catalyst. For the implementation of the present invention can be used in a conventional fluidized bed of ammoxidation catalyst. For example, fluidized bed of catalyst, which is described in U.S. patent 3642930 and 5093299 can be used to implement the present invention.

Brief description of drawings

The drawing schematically shows the Acrylonitrile process using the updated column extraction and separation of HCN.

Detailed description of the invention

Next will be described in detail with reference to the drawing, the process of extraction and purification of Acrylonitrile and Methacrylonitrile in accordance with the present invention. The flow reactor 11, obtained by the ammoxidation of propane, propylene or isobutylene, ammonia and oxygen-containing gas in a reactor with psevdoozhizhennom layer (not shown), in contact with a fluidized bed of ammoxidation catalyst, is transported through the transmission line 11 in column blanking 10, in which the hot exhaust gases are cooled by contact with the sprayed water 14. The cooled flue gas, which contains the desired product (Acrylonitrile or Methacrylonitrile, acetonitrile and HCN), then sent through line 12 to the base of the absorption column 20, in which the products are absorbed in water, which is absorbed into the absorption Colo is well top 20 on line 24. Not absorbed gases out of the absorption column 20 through placed above the pipe 22. Water flow, which contains the desired product, then passed through line 23 from the base of the absorption column 20 in the upper part of the first distillation column 30 (column extraction) to further purify the product. The product is extracted from the upper part of the extraction columns 30 and sent to the second distillation column 40 (column head fraction) 40, line 32, while water and other impurities are removed from the extraction columns 30 through line 33. In the column head fraction 40 HCN forms the upper shoulder straps and removed from the column through line 42, and then is cooled in the condenser 80 of the upper shoulder strap, and the resulting material is sent via line 41 to the collection of irrigation fraction 50. The irrigation fluid from the collection of irrigation fraction 50 is returned to the upper part of the head of the column fractions 40 through line 53. The material vapor phase is removed from the collection irrigating fraction 50 by line 52 and is cooled in the condenser 90 product in the form of HCN.

Significant operating problem encountered when removing and cleaning products in the production of Acrylonitrile and Methacrylonitrile, is the formation of HCN polymer in the column head of the faction, sometimes called the HCN column (40). In particular, HCN polymer is formed on the plates and winterwolf in the column head of the faction above the supply input (where the line 32 is included in the column 40). Solid, polymeric HCN litters plate distillation columns, walls, drains, drain pipes, etc. and also violates the hydraulic balance of the boundary surfaces of the liquid/vapor in the column head of the faction. Polymerization increases the pressure drop in the column, and the corresponding increase of the temperature in the column increases the formation of polymer. The presence of such a polymer may eventually require a long and costly stop section of cleaning product to perform the cleaning operation of the column.

Lack of a clear understanding by professionals of this phenomenon in the past has led to a reduction in operating pressure and hence temperature of the column head of the faction, resulting in reduced polymerization reaction leading to the formation of clogging material. The inventor has found that the mechanism of polymerization depends on the presence of the second liquid, namely water phase in the column head of the faction. This aqueous phase creates conditions leading to ionic polymerization of HCN with the formation of a solid polymer HCN. Polymer HCN is deposited and blocks the active zone and the drain nozzle plates of the column and the adhesion scores intervals of the column. The discovery of this previously unknown and unexpected mechanism made it possible to organize the work of such is istallazione columns with significantly reduced speeds HCN polymerization and, as a result, with reduced clogging. This improvement can be achieved by choosing such a mode of operation of the column head of the faction, which lowers or eliminates the formation of this aqueous phase.

Since the formation of the water layer has not previously been evaluated as a potential source of HCN polymerization, it is currently unknown attempts to reduce the formation of the water layer. Reduction technology education this water layer include (but without limitation) the increase of the coefficient of irrigation; use the side of the decanter for splitting the aqueous phase and removing it from the column; the use of over the cold feed stream to increase the efficiency of the distillation column; the increase in the number organicrich plates; an intermediate capacitor above the supply input in addition to the capacitor upper shoulder strap; subcooled flow irrigation; increase the capacity of the capacitors reboiler and top of shoulder strap to increase the cost of irrigation; control working pressure for shifting the equilibrium between two liquid phases, as well as ways to improve the performance reboiler and related the efficiency of the distillation columns of the parent faction. The increase in irrigation hydrogen cyanide or cyanide concentrations of hydrogen above pitt the school plates can also be achieved by the section of the reactor process with a higher weight percentage of HCN in the product of the reactor, and by increasing the percentage of HCN in the feed stream of the column head of the faction, which leads to the reduction or elimination of the second liquid phase. Any increase in the efficiency of the plates leads to greater efficiency distillation and helps to eliminate unwanted second liquid phase.

The ammoxidation reaction is mainly carried out in a reactor with a fluidized bed, however, can be used reactors and other types, such as reactors with a line of transportation. The fluidized bed reactor for the production of Acrylonitrile is already well known. For example, the design of such a suitable reactor is described in U.S. patent No. 3230246.

The reaction conditions ammoxidation is also well known and described, for example, in U.S. patents 5093299; 4863891; 4767878 and 4503001. Usually the ammoxidation process carried out at the expense of putting in contact propane, propylene or isobutylene in the presence of ammonia and oxygen, in the presence of fluidized bed of catalyst at an elevated temperature to obtain Acrylonitrile or Methacrylonitrile. Can be used any source of oxygen, however, for economic reasons, mainly used air. A typical molar ratio of oxygen to olefin in the feed stream should be within the range of from 0.5:1 to 4:1, and typically is built from 1:1 to 3:1. The molar ratio of ammonia to olefin in the feed stream can vary in the range from 0.5:1 to 5:1. In fact, there is no upper limit for the ammonia-olefin, but for economic reasons there is no reason to increase this ratio over 5:1.

The reaction is carried out at a temperature in the range from approximately 260 to 600°C, mostly in the range from 310 to 500°and better still from 350 to 480°C. the Duration of the contact, although it is not critical, typically lies in the range from 0.1 to 50 seconds, and is preferably from 1 to 15 seconds.

In addition to the catalyst, opened in U.S. patent No. 3642930, can be used and other catalysts suitable for implementing the present invention, for example, disclosed in U.S. patent No. 5093299.

In the absorption column, the column extraction and in the column head of the faction supported pressure respectively from 5 to 7 psig (pound per square inch) and from 1 to 4.5 psig and temperatures from 80°F to 110°F and 155°F to 170°F.

EXAMPLES

The simulation process ASPENPLUS ® for the head of the column fractions were used to identify working conditions that allow you to remove the aqueous phase on the plates above the location of the feed entering the column. Was selected temperature of the feed stream of the column and set the efficiency of the plates. Then for each the case made the adjustment coefficient irrigation head of the column fractions until until you form a third water phase on the plates above the location of the power input to the column. Acceptable purity of the product is believed the presence of the upper ring-less than 50 ppm (parts per million) of Acrylonitrile, and the composition of the cubic flow less than 100 ppm HCN.

In all examples, the supply flow of the column head of the faction has a nominal composition containing 83 wt.% Acrylonitrile, 10 wt.% HCN and 7 wt.% water, and this stream is introduced into the column head of the faction with a speed of 40,000 pounds per hour, at a pressure of 30 psia. The column head of the faction has 64 plates, the reboiler and the condenser top of a shoulder strap. The efficiency of the plates in this simulation was 60%. In all examples, the plates are numbered starting from the top plate of the column head of the faction.

Example 1

The main stream was introduced into the column at a plate number 25. When the temperature of the feed stream 100°F third aqueous phase was removed with a coefficient of irrigation 4.95, while the product of the upper shoulder strap and CBM product still have features that are supported within the specified limits. When the coefficients irrigation below 4.95 produces unwanted water layer.

Example 2

The location of the main flow of power shifted on 5 plates, plate number 20. When the temperature of the feed stream 100°F third aqueous phase was eliminated in the ratio Orosei is 4.3, when this product is top of the shoulder strap and CBM product still have features that are supported within the specified limits. Thus, the introduction of five additional plates distillation reduces the coefficient of irrigation needed to eliminate unwanted water phase, with 4.95 in Example 1 to 4.3 in this case.

Example 3

Main stream power at a temperature of 80°F was injected into the column at the plate 25. At such lower temperature stream power, the third aqueous phase was removed with a coefficient of irrigation 4.24 instead 4.95 for Example 1, the product of the upper shoulder strap and CBM product still have features that are supported in the given range.

Example 4

The primary stream was divided into 2 parts: 75% of the feed stream was introduced on the plate 20, and 25% of the feed stream was introduced on the plate number 25. Maintained a temperature of 100°F in both parts of the supply stream. The third aqueous phase was removed with a coefficient of irrigation 4.1, while the product of the upper shoulder strap and CBM product still have features that are supported within the specified limits. This coefficient irrigation is more favorable in comparison with the coefficient of irrigation 4.95 for Example 1 or 4.3 for Example 2.

Example 5

The primary flow of power at a temperature of 100°F was injected into the column at Tarek is 25. Intermediate capacitor plate removes all the material of the liquid phase of the plates 20, cools the material up to 60°F and returns the cooled liquid material on the plate 21. The third aqueous phase was removed with a coefficient of irrigation 4.6, while the product of the upper shoulder strap and CBM product still have features that are supported in the given range.

Example 6

The primary flow of power at a temperature of 100°F was injected into the column at the plate 25. A total of 400 pounds per hour 99.8 wt.% HCN at a temperature of 80°F filed on the plate 20. The third aqueous phase was removed with a coefficient of irrigation 4.3, while the product of the upper shoulder strap and CBM product still have features that are supported within the specified limits. It should be borne in mind that the addition of pure HCN can be produced anywhere in the column section head of the faction between the top plate and nutritious dish. The industrial installation configuration of the reactor to obtain a higher percentage of HCN in the product flow reactor, resulting in a higher percentage of HCN in the feed streams of the column head of the faction, is analogous to this example.

Example 7

The primary flow of power at a temperature of 100°F was injected into the column at the plate 25. Two-phase side of the decanter, which m who can work at temperatures below the ambient temperature, removes all the material of the liquid phase of the plates 24, decontinued the aqueous phase from the organic phase and returns the material of the organic phase on the plate 25. The third aqueous phase was removed with a coefficient of irrigation 4.8, while the product of the upper shoulder strap and CBM product still have features that are supported in the given range.

It should also be borne in mind that a combination of different means to reduce or avoid undesirable aqueous phase can lead to the optimal solution for specific restrictions. However, experts can easily understand that various modifications of the present invention, which can be offered in the understanding of the above description, is not beyond the scope of the claims.

1. Method for the recovery of Acrylonitrile, Methacrylonitrile or hydrogen cyanide obtained from flow reactor ammoxidation reaction of propane, propylene or isobutylene, which provides for the transmission of a stream of the reactor through an absorption column, the column extraction and column head fraction, characterized in that it envisages the setting mode of the column head of the faction, which prevents the formation of the aqueous phase above the nutrient plates of the column head of the faction.

2. The method according to claim 1, wherein said mode of operation of the column goal the main faction provides for an increase of the coefficient of irrigation head of the column fractions to the values in which the aqueous phase is not formed above a nutritious dish.

3. The method according to claim 2, wherein said mode of operation of the column head of a faction involves increasing the supply of hydrogen cyanide to the column to achieve the conditions equivalent to the higher coefficient of irrigation.

4. The method according to claim 3, wherein said supply carried out by recycling the purified HCN in the column head of the faction.

5. The method according to claim 3, wherein said supply carry out due to the work of the ammoxidation reactor in a mode that allows you to receive a flow reactor with higher concentrations of HCN.

6. The method according to claim 1, wherein said mode of operation of the column head of a faction involves the use of the side of the decanter to remove water material from this column.

7. The method according to claim 1, wherein said mode of operation of the column head of the faction provides for an increase in the number of distillation plates of the column.

8. The method according to claim 1, wherein said mode of operation of the column head of the faction provides for increased performance reboiler this column.

9. The method according to claim 1, wherein said mode of operation of the column head of the faction makes use of the intermediate capacitor higher nutrient plates and below the capacitor irrigation of the column.

10. The method according to claim 1, in which the specified operation mode of the column head of the faction provides for the cooling of the feed stream of this column to a temperature to the aqueous phase is formed above a nutritious dish.

11. The method according to claim 1, wherein said mode of operation of the column head of the faction provides subcooling flow irrigation of the column.

12. The method according to claim 1, wherein said mode of operation of the column head of the faction provides for the reduction of the operating pressure of the column so that when the pressure was decreased area of the second liquid phase.



 

Same patents:

FIELD: chemical technology.

SUBSTANCE: invention relates to a method for extraction of organic material comprising hydrogen cyanide prepared in reactor flow in carrying out the ammoxidation reaction of propylene or isobutylene for preparing acrylonitrile or methacrylonitrile followed by feeding vapor flows from technological devices to the torch head part. At least one part of organic material from torch head part comprising hydrogen cyanide is fed to the extraction stage. Method provides reducing amount of acrylonitile and HCN feeding to combustion.

EFFECT: improved method for extraction.

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FIELD: industrial organic synthesis.

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EFFECT: enhanced process efficiency.

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The invention relates to an improved method for the recovery and regeneration of unreacted ammonia from the resulting stream containing Acrylonitrile or Methacrylonitrile derived from the reaction zone, where oxygen, ammonia and a hydrocarbon selected from the group consisting of propane and isobutane, interact in a reactor in the presence of a fluidized bed of ammoxidation catalyst at elevated temperature to obtain the corresponding unsaturated nitrile cooling discharge flow from the fluidized bed reactor containing the corresponding nitrile and unreacted ammonia from the first aqueous solution of ammonium phosphate, in which the ratio of ammonium ions (NH+4) to phosphate ions (PO-34) is from about 0.7 to about 1.3, to absorb essentially all of the unreacted ammonia present in stemming the flow reactor for the formation of the second aqueous solution of ammonium phosphate, richer ammonium ions than the first solution, heating the second aqueous solution of ammonium phosphate to elevated temperature sufficient to reduce the amount of ammonium ions in the second solution to essentially the same level present in n the th ammonia, in a fluidized bed reactor

The invention relates to a method for producing olefin-unsaturated NITRILES by the reaction of lower alkanes or alkenes with oxygen and ammonia in the gas phase in the presence of water vapor and a suitable catalyst at elevated temperature in the ammoxidation reactor with the formation at the exit of the hot gaseous stream comprising nitrile, unreacted reagents and by-products, followed by passing hot gaseous flow through the reverse jet scrubber, in which the hot gaseous stream is rapidly cooled, as a result of its contact with the cooling liquid injected countercurrent to the direction of movement of the specified gas flow, with the removal of ammonia, when this gaseous stream is passed through a reverse jet scrubber provided with such a speed that allows you to change to reverse the direction of flow of the injected coolant by evaporation of a part of the injected coolant

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The invention relates to a method for isolation and purification refinancing nitrile, such as Acrylonitrile
The invention relates to an improved method of extraction of Acrylonitrile or Methacrylonitrile, which is used in the production of Acrylonitrile or Methacrylonitrile

FIELD: chemical technology.

SUBSTANCE: invention relates to a method for extraction of organic material comprising hydrogen cyanide prepared in reactor flow in carrying out the ammoxidation reaction of propylene or isobutylene for preparing acrylonitrile or methacrylonitrile followed by feeding vapor flows from technological devices to the torch head part. At least one part of organic material from torch head part comprising hydrogen cyanide is fed to the extraction stage. Method provides reducing amount of acrylonitile and HCN feeding to combustion.

EFFECT: improved method for extraction.

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The invention relates to a method for isolation and purification refinancing nitrile, such as Acrylonitrile
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EFFECT: improved method for extraction.

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FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for extraction of acrylonitrile, methacrylonitrile or hydrogen cyanide obtained from the reaction flow in the ammoxidation reaction of propane, propylene or isobutylene that involves passing the reactor flow through absorption column, extraction column and head fraction column. Method involves using such regimen of the process to prevent formation of an aqueous phase above feeding plate in the head fraction column. Method provides reducing unfavorable polymerization of hydrogen cyanide that provides significant decreasing or excluding stoppage of the head fraction column.

EFFECT: improved method for extraction.

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FIELD: chemical technology.

SUBSTANCE: invention relates to a method for the hydrocyaniding reaction of unsaturated compounds. Method involves at least one step of the hydrocyaniding reaction in the presence of catalytic system comprising metalloorganic complex. Complex comprises one or some organophosphorus ligands of monodentate organophosphite type, one or some bidentate organophosphorus ligands, and, optionally, a promoter of Lewis acid type. Also, method involves the separating step by distillation of reagent used in the method, or compound synthesized during the hydrocyaniding reaction from medium containing the above indicated catalytic system. Medium subjected for the separating step by distillation shows the ratio of mole of organophosphorus ligands expressed as number of phosphorus atoms to number of metal atoms less or equal 15, and/or the mass ratio of the metal content forming the metalloorganic complex less or equal 1.3%. The vat temperature in the distillation step is lower or equal 180°C. Method provides separating and extracting catalyst and final substances with minimal loss of compounds forming the catalytic system.

EFFECT: improved hydrocyaniding method.

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FIELD: organic chemistry, chemical technology.

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EFFECT: improved method of synthesis.

7 cl, 2 tbl, 2 dwg, 2 ex

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