RU2732023C1 - Rectification column for separation of steam-gas mixture of water vapour, ammonia and hydrogen sulphide - Google Patents

Abstract

FIELD: treatment of water, industrial and household waste water.

SUBSTANCE: invention relates to devices for separation of sulphurous-ammonium waste water treatment products and can be used in chemical industry. Rectification column includes housing with branch pipes for supply and removal of vapour and gas and liquid phases, circulating cooled irrigation systems, contact devices, distributors of bottom and top circulating irrigation and blind collector plate equipped with gas duct. Attachment contact devices are located in its lower and upper parts, the dish-shaped contact device is located in its middle part. Blind collector plate equipped with a gas duct separates the upper packing device from the dish-shaped contact device.

EFFECT: technical result consists in improvement of efficiency of separation of steam-gas mixture of water vapour, ammonia and hydrogen sulphide, optimization of vapour-liquid load, elimination of phenomena of spray mud and fluid failure, as well as in ensuring required degree of purity of separation of steam-gas mixture of water vapour, ammonia and hydrogen sulphide.

6 cl, 6 dwg, 1 tbl

Description

SUBSTANCE: invention relates to devices for separation of products of purification of sulphurous-ammonium wastewater, can find application in chemical industry and allows to provide the required degree of purity of separation of steam-gas mixture of water vapor, ammonia and hydrogen sulfide into ammonia.

From patent No. 2162444 (RU IPC C02F 1/04, publ. 01/27/2001 Bull. No. 3) a rectification column (column-type scrubber) is known for cooling a mixture of water and ammonia with a residual hydrogen sulfide content, including a cylindrical body with branch pipes for supplying a mixture of ammonia with residual hydrogen sulfide and water vapor, supply and removal of a circulating liquid flow, removal of an aqueous solution of ammonium hydrosulfide returned to the absorption-stripping column, and ammonia from above the scrubber. The column is equipped with a packed contact device.

The general features of this column and the patented invention are a casing with branch pipes for supplying and removing steam-gas and liquid phases, a circulating cooled irrigation system and a packed contact device.

The known column, designed to cool a mixture of ammonia with residual hydrogen sulfide and water vapor, does not provide for the removal of residual hydrogen sulfide, which is associated with clogging of the ammonia outlet pipelines with ammonium hydrosulfide salts and the need for further additional purification of ammonia-containing gas from hydrogen sulfide before its use or disposal.

From patent No. 2307795 (RU IPC C02F 1/04, B01D 3/14, publ. 10.10.2007 Bull. No. 28) a rectification column (two-section column-type scrubber) is known for separating a gas mixture of ammonia with residual hydrogen sulfide and water. The column includes a cylindrical body with branch pipes for supplying a gas mixture, supplying and removing a circulating liquid flow, removing purified ammonia from above the scrubber and condensate as a bottom product. The upper section of the scrubber is equipped with a contact device (mass transfer section) with circulating irrigation, while its lower section can be equipped with a packing or a tubular heat exchanger.

The general features of this analogue and the column being patented are a casing with branch pipes for supplying and removing steam-gas and liquid phases, a circulating cooled irrigation system in its upper part and two packed contact devices.

The technical result from the implementation of the known column consists in the purification and separation of ammonia from the liquid phase.

The disadvantages of the known column are that the implementation of the ammonia purification process is associated with the need to limit the temperature of the top of the distillation column (at least 100-110 ° C), with a high probability of precipitation of solid deposits of hydrosulfide and ammonium sulfide, and the absence of bottom circulating irrigation does not allow creating conditions for effective absorption of hydrogen sulfide.

From patent No. 2666450 (RU IPC С01С 1/00, B01D 53/14, publ. 09/07/2018 Bull. No. 25) a two-section rectification column (column absorber) is known for purifying gaseous ammonia containing hydrogen sulfide, carbon dioxide, mercaptans, and to obtain ammonia water. The column is made of two contact packing devices, separated by a blind collector plate equipped with a gas duct, equipped with two circulating cooled irrigation systems in its upper and lower parts. The column includes an ammonia water distributor for irrigation of the lower contact device, a water distributor for the upper packed contact device, an ammonia water distributor for irrigation of the upper contact device, a gas duct, an inlet for ammonia-containing gas, an inlet for supplying ammonia water to the lower contact device, an inlet for water supply to upper contact device, inlet for supplying ammonia water to the upper contact device, outlet for ammonia water from a blank collector plate, inlet for inert gas, outlet for polluted flow, outlet for gas discharge.

Common features of this analogue and the column being patented are a body with branch pipes for inlet and outlet of gas and liquid phases, two circulating cooled irrigation systems in its upper and lower parts, two packed contact devices, liquid distributors for irrigation of the upper and lower contact devices and a dead manifold equipped with a gas duct plate separating contact devices.

The technical result, to which the known invention is directed, is to obtain ammonia water of high purity of the required concentration, including according to GOST, from "dirty" gaseous ammonia containing impurities (hydrogen sulfide, carbon dioxide, mercaptans) in one apparatus - column absorber.

The efficiency of separation of ammonia from water and hydrogen sulfide residues has not been determined and the composition of waste gases has not been presented.

The design of the column, equipped with two packed sections, does not provide a high intensity of the mass transfer process and effective purification of gaseous ammonia, as well as a reduction in spray loss and prevention of liquid dip. In addition, the use of an additional water distributor for irrigation of the upper contact device, the use of inert gases and devices for their supply is associated with an increase in material consumption and material costs for the manufacture and operation of the column.

The closest (prototype) in technical essence and the achieved result is a rectification column (three-section absorber of the column type) for separating a vapor-gas mixture containing steam, ammonia and residual sulfur-containing compounds, known from patent No. 2602096 (RU IPC C02F 1/00, publ. 10.11.2016 Bul. No. 31). The column includes a body with branch pipes for inlet and outlet of vapor-gas and liquid phases, circulating cooled irrigation systems located in its upper and lower parts, and three packed contact devices.

The column is designed for cooling and condensation of water vapors, absorption of ammonia and dissolution of hydrogen sulfide and mercaptans in the formed ammonia water. The process is carried out in such a way as to most fully absorb hydrogen sulfide and mercaptans and obtain product ammonia of high purity.

At the same time, the design of this column does not allow for a high intensity of the mass transfer process and a sufficiently effective separation of ammonia from water and hydrogen sulfide residues, to exclude splashing and liquid failure.

The technical problem of the claimed invention is to expand the range of rectification columns to ensure a deep degree of purity in the separation of a vapor-gas mixture of water vapor, ammonia and hydrogen sulfide into ammonia.

Implementation of the claimed invention allows obtaining the following technical result:

- increasing the efficiency of separation of the vapor-gas mixture of water vapor, ammonia and hydrogen sulfide (reducing the amount of residual hydrogen sulfide and water in purified ammonia);

- preventing the formation of ammonium hydrosulfide salts in apparatuses and pipelines;

- optimization of the vapor-liquid load;

- exclusion of the phenomena of splashing and liquid failure.

Elimination of these shortcomings and the technical result from the implementation of a patented rectification column for separating a vapor-gas mixture of water vapor, ammonia and hydrogen sulfide, including a housing with branch pipes for supplying and removing vapor-gas and liquid phases, two circulating cooled irrigation systems located in its upper and lower parts, three contact devices, distributors of lower and upper circulating irrigation and a blind collector plate equipped with a gas duct are achieved by the fact that the column is equipped with two packed contact devices located in the lower and upper parts of the body, and a disc-shaped contact device located in the middle part of the body. A blank collector plate equipped with a gas duct separates the top nozzle contact device from the plate contact device. The lower nozzle contact device is equipped with contact elements - a nozzle of the mellagrid 90x type, the middle poppet contact device is equipped with four contact valve single-pass plates, the upper nozzle contact device is equipped with contact elements - a nozzle in the form of Pall rings with a size of 50 × 50. The column is equipped with inlet devices and distributors for lower and upper circulation irrigation, which contain downpipes, a spreading plate sheet with irrigation holes, baffle discs, and gas ducts. The gaps between the bed of the distribution plates and the downpipes are 55 mm, and between the downpipes and the baffle discs - 30 mm, the diameter of the irrigation holes is 10 mm, and their total area in the bed of the distribution plates is less than 1%. Vortex dampers are made in the lower part of the column and in the pocket of the blind collector plate under the upper packing contact device.

Comparative analysis of the prototype and the claimed rectification column for separating the steam-gas mixture of water vapor, ammonia and hydrogen sulfide shows that both columns include a body with branch pipes for supplying and removing steam-gas and liquid phases, two circulating cooled irrigation systems located in its upper and lower parts, three contact devices, distributors of lower and upper circulating irrigation and a blank collector plate equipped with a gas duct.

A distinctive feature of the claimed rectification column for separating a vapor-gas mixture of water vapor, ammonia and hydrogen sulfide is that the column is equipped with two packed contact devices located in the lower and upper parts of the body, and a disc-shaped contact device located in the middle part of the body. A blank collector plate equipped with a gas duct separates the top nozzle contact device from the plate contact device. The lower nozzle contact device is equipped with contact elements - a nozzle of the mellagrid 90x type, the middle poppet contact device is equipped with four contact valve single-pass plates, the upper nozzle contact device is equipped with contact elements - a nozzle in the form of Pall rings with a size of 50 × 50. The column is equipped with inlet devices and distributors for lower and upper circulation irrigation, which contain downpipes, a spreading plate sheet with irrigation holes, baffle discs, and gas ducts. The gaps between the bed of the distribution plates and the downpipes are 55 mm, and between the downpipes and the baffle discs - 30 mm, the diameter of the irrigation holes is 10 mm, and their total area in the bed of the distribution plates is less than 1%. Vortex dampers are made in the lower part of the column and in the pocket of the blind collector plate under the upper packing contact device.

The patentable invention is illustrated by the following drawings:

in fig. 1 shows a sketch of a column;

in fig. 2 shows the device for entering the upper circulating irrigation;

in fig. 3 shows the distributor of the upper circulating irrigation;

in fig. 4 shows the input device for the bottom circulating irrigation;

in fig. 5 shows the distributor of the bottom circulation irrigation.

The patented rectification column is a welded vertical cylindrical apparatus of variable cross-section (1400/1000), with internal devices mounted on a cylindrical support, and consists of a housing 1, on which a branch pipe 2 is made for supplying a vapor-gas mixture of water vapor, ammonia and hydrogen sulfide (ammonia-containing gas ), branch pipe 3 for the outlet of ammonia-containing gas (purified ammonia), branch pipe 4 for supplying the lower circulating irrigation (NCO), branch pipe 5 for the outlet of the NCO, branch pipe 6 for supplying the upper circulating irrigation (VCO), branch pipe 7 for the outlet of the VCO, branch pipe 8 for return vapors supply, branch pipe 9 for purified water supply. The vortex damper 10, the nozzle contact device 11, which is equipped with contact elements - a nozzle of the mellagrid 90x type, the distributor of the lower circulating irrigation (NCO) 12 (not all downpipes are shown), the input device of the lower circulating irrigation (NCO) 13, are made in the housing 1, a poppet contact device 14, which is equipped with contact valve single-pass plates in the amount of 4 x pieces, a vortex damper 15, a blind collector plate 16, a packed contact device 17, which is equipped with contact elements - an attachment in the form of Pall rings in size 50 × 50, a distributor VTSO 18, input device VTsO 19, downpipes 20 of NCO 12 distributors (not all downpipes are shown) and VTsO 18.

Figures 2, 4 show the input devices VTsO 19 and NCO 13, respectively, which contain downpipes 20, a distribution plate web 21, a baffle disk 22, and gas ducts 23.

Figures 3, 5 show the distributors VCO 18 and NCO 12, respectively, which contain downpipes 20, a distribution plate web 21, gas ducts 23, irrigation (distribution) holes 24.

In the accompanying drawings, like symbols refer to the same or like parts in different views.

The patented rectification column operates as follows. Separated from the products of purification of sulphurous-ammonium wastewater, a steam-gas mixture containing water vapor, ammonia and residual hydrogen sulphide is fed through the pipe 2 to the lower part of the column. The absorbent (bottoms liquid) of the lower circulating irrigation (NCO) through the nozzle 4 and the input device of the lower circulating irrigation (NCO) 13 is fed to the upper part of the 1st along the vapor path (lower) of the packed contact device 11 and is evenly distributed over the cross-section of the column using distribution device 12. The solution withdrawal (withdrawal) of the NCO is carried out from the bottom of the column through the branch pipe 5. In this case, part of the bottom liquid after cooling in air and then water coolers is sent as NCO, and its other part for disposal.

Liquid from the packed contact device 11 flows down the column, and the purified gas, after condensation of water vapor on this element, enters the lower part of the disc contact device 14. Purified water is fed to the upper part of this device through the branch pipe 9 to ensure absorption of residual hydrogen sulfide and ammonia. Gaseous ammonia from the disc contact device 14 enters the lower part of the upper packed contact device 17, and the solution of ammonium hydrosulfide in ammonia water formed as a result of cleaning flows down to the bottom of the column.

Practice has shown that eddies may form at the outlet of the column, which impede the rectification process and promote gas entrainment into the liquid outlet, which degrades the efficiency of the separation process. To prevent the formation of a liquid funnel with entrapment of the gas phase at minimum liquid levels in the cube, vortex dampers 10, 15 are provided in the bottom of the column and in the pocket of the collecting blank plate 16 under the upper packed contact device 17.

Using the branch pipe 6 for supplying the upper circulating irrigation (VTsO), the input device VTsO 19 and the distributor VTsO 18, the upper circulating irrigation is organized. Due to the VCO, a decrease in the temperature of gaseous ammonia is achieved and the carryover of water vapor from the column is prevented on the upper packed contact device 17. In this case, the upper circulating reflux ensures the temperature of the column top within 48-50 ° C. The liquid from the nozzle of the contact device 17 is collected by a blank collector plate 16 and is directed by gravity into the buffer tank. After cooling and mixing with a stream of pure water, part of this liquid is fed to the top of the column as VCO. Purified ammonia is removed from the top of the column through the pipe 3.

FIG. 6 shows the relationship between the values of steam and liquid load. The data presented in FIG. 6, convincingly show that the ratio of the values of steam and liquid load is in the optimal position.

Comparative results of purification of ammonia separated from process condensates from residual hydrogen sulfide are presented in the table. The data presented in the table show that the design features of the patented distillation column ensure the production of product ammonia of high purity (ammonia content is more than 99 wt%, the content of hydrogen sulfide impurity is not more than 0.002 wt%), the prevention of the formation of deposits of ammonium hydrosulfide salts in gas pipelines and phenomena spray and liquid dip.

In this case, the exclusion of the phenomenon of splashing and liquid dip is ensured by placing the disc-shaped contact device 14 in the middle part of the absorber. The most efficient separation of the ammonia-containing gas from the residual hydrogen sulfide-containing gas, as well as the optimal vapor-liquid loading on the trays, is ensured by the high efficiency of the tray devices.

High density of liquid irrigation (more than 30 m ³ / m ² ⋅h) is provided due to the design of the spreading type distributors.

The minimum hydraulic gradient of the liquid level on the distribution plate web and the uniform distribution of the liquid over the column cross section is ensured by supplying the liquid to the distributors through the tubular collector inlet devices. In this case, in the distribution devices, the distance between the web of the distribution plates 21 and the downpipes 20 is 55 mm, and between the downpipes 20 and the baffle discs 22 is 30 mm. The distances indicated are sufficient to ensure an even distribution of the liquid over the distribution tray.

High-quality, uniform distribution of liquid over the section of the column is also ensured by the gas ducts installed between the distribution (irrigation) holes 24 (gas ducts 23) and their number (5 in the VCO input device and 9 in the NCO input device), as well as located in a certain way in the canvas distribution trays distribution holes 24. High liquid flow rates (more than 30 m ³ / m ² ⋅h) and prevention of contamination of irrigation holes are provided due to a sufficiently large (10 mm) diameter of distribution (irrigation) holes. In this case, the total area of the irrigation holes in the web of the distribution plates is less than 1%.

At the same time, the technical result from the implementation of the invention is achieved not by the additive contribution of each component, but due to the total synergistic effect.

Claims (6)

1. A distillation column for separating a vapor-gas mixture of water vapor, ammonia and hydrogen sulfide, including a casing with branch pipes for supplying and removing vapor-gas and liquid phases, two circulating cooled irrigation systems located in its upper and lower parts, two packed contact devices located in its upper and lower parts, distributors of lower and upper circulating irrigation and a deaf collector plate equipped with a gas duct, characterized in that the column is equipped with a third contact device, which is a disc-shaped contact device located in its middle part. 2. The distillation column according to claim 1, characterized in that a blank collecting plate equipped with a gas duct separates the upper packed contact device from the plate contact device. 3. The distillation column according to claim 1, characterized in that the lower packed contact device is equipped with contact elements - packing of the mellagrid 90x type, the middle disc contact device is equipped with four contact valve single-pass trays, the upper packed contact device is equipped with contact elements - packing in the form of rings Pall. 4. The distillation column according to claim 1, characterized in that the column is equipped with input devices and distributors for lower and upper circulating irrigation, which contain downpipes, a distribution plate sheet with irrigation holes, baffle discs, and gas ducts. 5. The rectification column according to claim 4, characterized in that the gaps between the bed of the distribution plates and the downpipes are 55 mm, and between the downpipes and the baffle discs - 30 mm, the diameter of the irrigation holes is 10 mm, and their total area in the bed of distribution trays is less than 1%. 6. The distillation column according to claim 1, characterized in that vortex dampers are made in the lower part of the column and in the pocket of the blind collector tray under the upper packed contact device.

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