WO2016039664A1

WO2016039664A1 - Adsorber for gas purification

Info

Publication number: WO2016039664A1
Application number: PCT/RU2015/000260
Authority: WO
Inventors: Igor Anatol`evich MNUSHKIN
Original assignee: Mnushkin Igor Anatol Evich
Priority date: 2014-09-10
Filing date: 2015-04-23
Publication date: 2016-03-17
Also published as: RU2569349C1

Abstract

The invention relates to the equipment for adsorption purification of gases from admixtures, particularly, hydrocarbon gases from water, carbon dioxide, hydrogen sulfide and other components, and can be used in oil refining, gas processing, chemical and other industries. The adsorber for gas purification comprises cylindrical body with upper and lower bottoms, one or more layers of adsorbent, lower and upper distribution grids, each of which is placed on the support grates, input unions of gas to be purified and output unions of purified gas, input and output unions of regeneration gas, systems of temperature and pressure sensors, hatches for loading and unloading of the adsorbent, access hatches. Lower distribution grid under the first (in flow direction of the refined raw) adsorbent layer is made of horizontally positioned Johnson grid or of solid or perforated sheet with round holes, the edges of which are associated with the vertical cans made of Johnson grid. Upper distribution grid above the last (in flow direction of the refined raw) adsorbent layer is made of horizontally positioned Johnson grid or of solid or perforated sheet with round holes, the edges of which are associated with vertical cans made of Johnson grid.

Description

Adsorber for gas purification

TECHNICAL FIELD

The invention relates to the equipment for adsorption purification of gases from admixtures, particularly, hydrocarbon gases from water, carbon dioxide, hydrogen sulfide and other components, and can be used in oil refining, gas processing, chemical and other industries.

One of the features of gas purification technology is the frequent presence of solid particles (dusty gas) or liquid drops (aerosol).

PREVIOUS TECHNICAL KNOWLEDGE

There is an adsorber comprising cylindrical body with upper and lower bottoms, input unions of gas to be purified and output unions of purified gas, input and output unions of regeneration gas, lower distribution grate, on which the adsorbent layer is placed on the layer of gravel inert substrate or ceramic, porcelain or metal packing, manholes for adsorbent loading and unloading (N. V. Keltsev Fundamentals of adsorption technology. M.: Khimiya, 1984, pp. 222-223 A. G. Kasatkin Basic procedures and apparatuses of chemical technology. M.: Khimiya, 1973. pp. 446-448). The basic disadvantages of the absorber are:

• uneven distribution of gas flow to be purified over normal cross section of the adsorbent layer due to the fact that the output of the purified gas through the upper union having much smaller section than the normal cross section of adsorbent layer results in the formation of dead zones around the outlet of the purified gas having truncated cone shape, which results in the decrease of adsorbent activity and the reduction of adsorption stage length, which impairs the economy performance of the procedure of adsorption gas purification;

• the presence of inert substrate layer increases the size and material consumption of the adsorber, which indirectly results in the increase of fixed assets for the unit of gas adsorption purification;

· inert substrate layer, consisting of gravel particles or packing with dimensions larger than granules have large transport channels with the diameter slightly smaller than adsorbent granule size, it allows the passage of liquid and solid particles in the purified gas stream to the adsorbent layer, at that, the liquid particles treat the adsorbent granules and the solid particles clog small transport pores between the granules, which in both cases results in the decrease of adsorbent activity and the reduction of adsorption stage length, which impairs the economy performance of the procedure of adsorption gas purification.

There is an adsorber, comprising casing, branch pipe of gas supply for purification, branch pipe of purified gas output, vessel with the sorbent, screw down device as a grid, support ring with double-action pneumatic cylinders, whose pistons are attached to the grid and are connected via two collectors, two three-way valves and a pipe to gas input, branch pipes for filling the sorbent are equipped with devices to control the sorbent shrinkage (Adsorber: pat. 2305003 Rus. Federation. No. 2005126825/15; appl. 25.08.05; publ. 27.02.07). This method has the following disadvantages:

• excessive complexity of the design of the absorber to seal the adsorbent layer while its shrinkage, resulting in a substantial rise of structure cost in general;

• presence of moving parts in the design of the adsorber (pistons in pneumatic cylinders, screw down device) increases the potential accident risk of the adsorber;

· presence of solid and liquid particles in the stream of gas to be purified results in particles easy penetration to adsorbent layer, at that, the liquid particles treat adsorbent granules, and the solid particles clog the small transport pores between the granules, which in both cases results in the decrease of adsorbent activity and the reduction of adsorption stage length, which impairs the economy performance of the procedure of adsorption gas purification.

There is also an adsorber comprising vertical casing divided by perforated zigzag partitions into sections forming staggered confusors and diffusers, upper and lower grids and outlet and inlet branch pipes. At that, gas inlet branch pipe is a narrowing truncated cone made of resilient elastic material, on the inner surface of which there are longitudinally extended spiral grooves, at that, the design of the grooves is "dovetail". Thus in the direction from the bigger base of gas inlet branch pipe to its smaller base there are outlet windows uniformly arranged at the horizontal level between longitudinally extended spiral grooves and having the same diameter at the same horizontal level and the increasing diameter in the subsequent horizontal levels, while gas to be purified is moving from bigger base of gas inlet branch pipe to its smaller base. Besides, the smaller base of gas inlet branch pipe is plugged with resilient elastic material. On the inner surface of gas outlet branch pipe there are longitudinally extended spiral grooves with a tangent line positioned clockwise. On the inner surface of gas inlet branch pipe, which is a narrowing truncated cone, the tangent line of spiral longitudinally extended grooves is positioned counter-clockwise, wherein the perforated zigzag partitions are made of bimetal, at that, bimetal material of confusor inner surface has 2-2.5 times higher heat conductivity factor than the heat conductivity factor of bimetal material of diffuser inner surface (Adsorber: certificate No. 141495, Rus. Federation. No. 201314343005/05; appl. 25.09.2013, publ. 10.06.2014). This method has the following disadvantages:

• excessive complexity of absorber design caused by the setting of perforated zigzag partitions, since the formation of staggered confusors and diffusers with perforations and low average linear speed of gas to be purified cannot result in the intensification of adsorption purification procedure and only increases the consumption of materials;

• presence of solid and liquid particles in the stream of gas to be purified results in particles easy penetration to adsorbent layer, at that, the liquid particles treat adsorbent granules, and the solid particles clog the small transport pores between the granules, which in both cases results in the decrease of adsorbent activity and the reduction of adsorption stage length, which impairs the economy performance of the procedure of adsorption gas purification.

There is also a vertical adsorber with fixed layer of adsorbent comprising vertical casing, support grid with filling layer of adsorbent, separating metal grids and layers of ceramic balls placed on the support grid and at the top of adsorbent layer, union at the upper bottom of adsorber casing for processed gas input (regeneration gas output), union on the lower bottom of adsorber casing for processed gas output (regeneration gas input), distributors for processed gas regeneration. It is characterized in that over the upper layer of the adsorbent, coated with a layer of ceramic balls, there is a horizontal perforated ring partition overlapping the cross section of adsorber casing, the central part of which has a shape of upward widening conical can, at the bottom of which through holes are provided. At that, in the perforated partition in the area between the conical can and the adsorber casing there are holes of different diameters and distances between them (Vertical adsorber with fixed layer of adsorbent: 2012134380 Rus. Federation appl. 10.08.2012, publ. 20.02.2014). This method has the following disadvantages:

• the presence of two layers of ceramic balls, between which the adsorbent layer is placed, results in the significant increase of hydraulic resistance during the passage of gas to be purified through the adsorber and a corresponding increase of energy costs for the implementation of gas purification procedure;

There is also a vertical adsorber, which contains cylindrical casing with a cover and a bottom. The cover is equipped with the hatch, the union with distribution grid to supply the feed mixture, the union for vapor withdrawal during the desorption and the union for the safety valve.

Moreover, at the joint between the cover and the casing a stiffening ring is provided, and in the middle part of the casing on the support the ring beams with supports are installed, supporting the grate, on which a layer of gravel is laid. At that, the adsorbent layer is located between the gravel layer and the grid, on which there are loads to prevent the adsorbent carry-over during the desorption, and the waste adsorbent is unloaded through the unloading hatch mounted in the casing, and in the bottom there are a bubbler and an inspection hatch with union for condensate withdrawal and water supply. The bubbler has toroidal shape and is fixed on the conical surface of the bottom with the bars (Kochetov's vertical adsorber: pat. 2508932 Rus. Federation. No. 20131 15215/05; appl. 05.04.2013, publ. 10.03.2014). This method has the following disadvantages:

• using of adsorbents with low adsorption activity and selectivity (porous polymeric materials, glass, porous rubber, composite materials, wood, stainless steel, titanium alloys, noble metals), which are not technological and are expensive to treat, since the adsorbent granules are shaped as a cylindrical ring, to the side surface of which two hemispherical surfaces are fastened opposing each other in such a way that the diametric planes of the hemispheres respectively coincide with upper and lower bases of the cylindrical ring, and the top parts of the hemispherical surfaces are on the ring axis and are directed towards each other;

• the ratio of height H of the cylindrical part of the casing to its diameter D is defined by ratio value H/D=0.73...1.1 and the relation of height Hi of the adsorbent layer and height H of the cylindrical part of the casing as follows: H₁/H=0.22...0.55 is not optimum, since providing a high adsorption activity of the adsorbent layer height in the adsorber shall be several times higher than mass transfer zone length, at that, the ratio of values H/D is substantially greater than 2;

DISCLOSURE OF INVENTION

Analysis of patent and technical literature has shown, that besides the presence of individual disadvantages the discussed adsorber designs have as well a common disadvantage: in the presence of solid and liquid particles in the gas stream to be purified (such a situation, for example, is typical in cases, when hydrocarbon gas before adsorption drying is subjected to absorption desulfurization purification using water solution of amine as the absorbent, the purified hydrocarbon gas contains a suspension of microscopic absorbent drops and then comes to the adsorber for gas drying by the selective adsorbents, typically, by silica gel or zeolites depending on the required dew point of the dried gas to be achieved), the particles easily penetrate to the layer of adsorbent. At that, liquid particles treat the adsorbent granules, reducing its adsorptive activity, if these particles are of organic origin, during the regeneration of the adsorbent at a high temperature, the adsorbed organic particles will undergo polymerization and polycondensation reactions, which results in the irreversible deactivation of adsorbents during the multicycle operation. The solid particles fully or partially clog the small transport pores between the adsorbent granules, in both cases resulting in an increase of the diffusion resistance during the adsorption and an increase of hydraulic resistance of the adsorbent layer, which is particularly important when using the adsorbent for the purification of exhaust gases at a minimum overpressure. All the reviewed factors result in the decrease of adsorbent activity and the reduction of adsorption stage duration, which impairs the economic performance of adsorption gas purification procedure.

The task of invention design was to create an adsorber with fixed adsorbent layer, providing the reliable operation of the device under gas purification conditions, containing solid particles and/or dropping liquid, that can be concentrated in the adsorbent layer and cause its deactivation.

The problem is solved thanks to the adsorber for gas purification comprising cylindrical body with upper and lower bottoms, one or more layers of adsorbent, each of which is located between lower and upper distribution grids, each of which is placed on the support grates, input unions of gas to be purified and output unions of purified gas, input and output unions of regeneration gas, systems of temperature and pressure sensors, hatches for loading and unloading of the adsorbent, access hatches. Lower distribution grid under the first (in flow direction of the refined raw) adsorbent layer is made of horizontally positioned Johnson grid or of solid or perforated sheet with round holes, the edges of which are associated with the vertical cans made of Johnson grid, and which are buried into the adsorbent layer. Upper distribution grid above the last (in flow direction of the refined raw) adsorbent layer is made of horizontally positioned Johnson grid or of solid or perforated sheet with round holes, the edges of which are associated with vertical cans made of Johnson grid, the bottom of which is made of a solid sheet Johnson grid, and which go out of adsorbent layer limits. Other distribution grates are made of horizontally positioned Johnson grid or of solid or perforated sheet with round holes. Johnson grid is made of metal and is trapezoidal shape wire, attached to the carrier rods with a microscopic gap between the adjacent wires, which makes Johnson grid an universal filtering element for separating solid particles and drops from the gas stream. The presence of the vertical cans made of Johnson grid, buried into the adsorbent layer, on the horizontal Johnson grid, allows increasing of gas filtration surface in several times (the raw gas to be purified entering the adsorbent layer from the bottom of the adsorber, and gas supplied for the adsorbent regeneration flowing to the adsorbent layer from the top of the adsorber). At that, solid and droplet admixtures of the raw gas to be purified will be held on the inner side of the vertical cans made of Johnson grid of lower distribution grid without contacting with the adsorbent, the microparticles of adsorbent granules, usually taken out of the adsorber with the purified gas stream, will be retained on the inner side of the vertical cans made of Johnson grid of upper distribution grid. The presence of the coupling of upper bottom of the adsorber and the casing with flange connections provides the releasable design of the device in its upper part, which simplifies the loading of the adsorbent once per two years during unit overhaul.

Advantageously the adsorber for gas purification has the following feature: if the diameter of the vertical cans made of Johnson grid is d, then their height will be not less than h, and if the distance between the axes of adjacent vertical cans is b, then h= (0.5)*(b-d)*tg(7c-<x), wherein a - opening angle of the flare of gas flow coming from the vertical can, which is defined by gas flow consumption, speed and pressure. For instance, when a = 450, the filtration surface will be increased by 10 %, and when a = 200, the filtration surface will be increased by 63 %, regardless of b and d values.

It is efficient to install the additional collectors, communicating via the crossflow with the drainage tank in the lower bottom, under vertical cans made of Johnson grid located on lower distribution grid. Then, at the beginning of the adsorbent regeneration procedure by regeneration gas stream passing through the adsorbent layer from the top down, solid and drop admixtures extracted from raw material gas to be purified and held on the inner surface of the vertical cans made of Johnson grid of lower distribution grid will be blown away from the surface of Johnson grid and will precipitate in the collectors moving further via crossflows to the drainage tank without contacting with the adsorbent, and the microparticles of adsorbent granules, usually taken out of the adsorber with purified gas stream, will be retained on the inner surface of vertical cans made of Johnson grid of upper distribution grid. Similarly, the microparticles of adsorbent granules held on the inner side of vertical cans made of Johnson grid of upper distribution grid will be returned to the adsorbent layer by regeneration gas stream. It is also preferred that the distribution grids were made dismountable and of perforated sheet with round holes having hole diameter smaller than the diameter of the adsorbent granules.

It is efficient if different adsorbent layers could sorb different admixtures from the raw material to be purified.

The drainage tank shall be advantageously communicating with the additional union of drain product output equipped with the drain valve mounted on the lower bottom, allowing to withdraw the drain product from the adsorber while accumulating of the drain product in the drainage tank.

It is also advisable to install radar type product level sensor for the drainage tank in lower bottom of the absorber for gas purification, providing the automatic control of drain product release.

LIST OF DRAWINGS

Figure 1 shows the design of the absorber for gas purification, consisting of one layer of adsorbent and comprising the following elements:

1 - cylindrical casing;

2 - upper bottom;

3 - lower bottom;

4 - input union of gas to be purified;

5 - output union of purified gas;

6 - input union of regeneration gas;

7 - output union of regeneration gas;

8 - lower distribution grid;

9 - upper distribution grid;

10 - adsorbent layer;

11 - adsorbent unloading hatch;

12 - access hatch;

13 - vertical cans made of Johnson grid;

14 - support grate;

15 - collectors;

16 - crossflow;

17 - drainage tank;

18 - additional union for drainage product withdrawal;

19 - drain valve;

20 - product level sensor; 21 - adsorbent loading hatch;

22 - lower distribution grid of adsorbent upper layer;

23 - upper distribution grid of adsorbent lower layer;

24 - round hole;

25 - bottom of vertical can made of Johnson grid;

26 - distribution grid.

BRIEF DESCRIPTION OF DRAWINGS

The adsorber for gas purification according to Figure 1 is a device consisting of cylindrical casing 1 with upper and lower bottoms 2 and 3, adsorbent unloading hatch 11, product level sensors 20, access hatch 12 intended for repair and checks, drain valve 19 and system of temperature and pressure sensors (is not shown in Figure 1).

When drying gases, the absorber for gas purification operates in two modes: adsorption mode and desorption mode. The adsorption procedure is carried out as follows: raw mixture (gas to be purified) is supplied via input union of gas to be purified 4 located at lower bottom 3 of the adsorber for gas purification, after its passage through support grate 14, on which lower distribution grid 8 is laid, made of horizontally positioned Johnson grid with vertical cans made of Johnson grid 13, buried into adsorbent layer 10, gas to be purified enters adsorbent layer 10, where the absorption of the components of gas to be purified is carried out, at that, the adsorbent is gradually enriched with the extractable admixture. As shown in Figure 1 representing the design of the absorber for gas purification, at its bottom part there are vertical cans made of Johnson grid 13 located on lower distribution grid 8 and buried in adsorbent layer 10, and at the upper part of the device there are vertical cans made of Johnson grid 13 located above upper distribution grid 9, and respectively, above the adsorbent layer.

The trapezoidal shape of the wire, which forms Johnson grid, has a larger base, connected with the carrier rods, and a smaller base, facing the incoming flow of gas to be purified. Therefore, solid particles and aerosol drops of the purified gas, as well as adsorbent particles, taken out by the purified gas from adsorbent layer 10, are retained on the inner surface of cans made of Johnson grid 13 located respectively on lower and upper distribution grids 8 and 9.

Adsorptive gas purification procedure is carried out until adsorbent layer 10 is enriched to a certain level and the contents of extracted admixtures in the purified gas reaches maximum permissible value - from this moment the adsorption stage is considered completed and the supply of gas to be purified stops. After passing through adsorbent layer 10, the purified gas is withdrawn through output union of purified gas 5 located at upper bottom 2 of the adsorber for gas purification. After adsorbent layer 10 is enriched, the desorption stage will start, comprising the restoration of the adsorbent layer using the regeneration gas. The desorption procedure is carried out as follows: through input union of regeneration gas 6 it is supplied through upper distribution grid 9 and vertical cans made of Johnson grid 13 to adsorbent layer 10. In the first moments of regeneration gas supply, a part of it may condense in the lower part of adsorbent layer 10, at that, the condensate with solid and drop admixtures retained on the inner surface of vertical cans made of Johnson grid 13 of lower distribution grid 8 is deposited in collectors 15, then, moving through crossflow 16, enters drainage tank 17, after which the condensate is withdrawn through additional union for drainage product withdrawal 18, and regeneration gas is withdrawn from the unit through output union of regeneration gas 7.

In the absence of the condensation of regeneration gas at the outlet of adsorbent layer 10

(e.g., regeneration gas - inert gas), regeneration gas hits solid and drop admixtures retained on the inner surface of vertical cans made of Johnson grid 13 of lower distribution grid 8, then these admixtures are deposited at collectors 15 and moving through the crossflow 16 fall into drainage tank 17, after which the condensate is withdrawn through additional union for drainage product withdrawal 18, and regeneration gas is withdrawn from the unit through output union of regeneration gas 7.

Drainage tanks 17 are released through drain valve 19 of additional union for drainage product withdrawal 18 as per the signal of product level sensor 20.

Figure 2 shows the structure of the absorber for gas purification, consisting of several layers of adsorbent. The adsorber for gases purification, given in Figure 2, operates similarly as the adsorber given in Figure 1.

The use of several adsorbent layers allows sorbing various admixtures from the purified material. A distinctive feature of the absorber for gas purification with one layer given in Figure 1, is the presence of additional adsorbent unloading hatch 11 and the additional distribution grids: lower distribution grid of adsorbent upper layer 22 and upper distribution grid of adsorbent lower layer 23.

Figure 3 shows the arrangement of support grate 14, distribution grid 26 and vertical can made of Johnson grid 13, at that, distribution grid 26 is mounted on support grate 14 and is made of the perforated sheet with round hole for can made of Johnson grid 13, the bottom of which is made of solid sheet.

Thus, the invention applied provides the solution of how to create the adsorber design with fixed adsorbent layer, providing the reliable operation of the unit under the conditions of gas purification, containing solid particles and/or dropping liquid, that can be concentrated in the adsorbent layer and result in its deactivation.

Claims

Formula of the invention

1 The adsorber for gas purification includes cylindrical body with upper and lower bottoms, in which one or more adsorbent layers are placed, each of which is located between lower and upper distribution grids, each placed on the support grates, input unions of gas to be purified and output unions of purified gas, input and output unions of regeneration gas, systems of temperature and pressure sensors, hatches for loading and unloading of the adsorbent, access hatches. T h e f e a t u r e is that the lower distribution grid under the first (in flow direction of the refined raw) adsorbent layer is made of horizontally positioned Johnson grid or of solid or perforated sheet with round holes, the edges of which are associated with the vertical cans made of Johnson grid, the bottom of which is made of solid sheet or Johnson grid and which are buried into the adsorbent layer. Upper distribution grid above the last (in flow direction of the refined raw) adsorbent layer is made of horizontally positioned Johnson grid or of solid or perforated sheet with round holes, the edges of which are associated with the vertical cans made of Johnson grid, the bottom of which is made of solid sheet or Johnson grid and which are out of adsorbent layer limits. Other distribution grids are made of horizontally positioned Johnson grid or of solid or perforated sheet with round holes.

2 The adsorber for gas purifying as per p. 1, has the following feature: if the diameter of the vertical cans made of Johnson grid is d, then their height will be not less than h, and if the distance between the axes of adjacent vertical cans is b, then h= (0.5)*(b-d)*tg(7c-a), wherein a - opening angle of the flare of gas flow coming from the vertical can.

3 The adsorber for gas purification as per p. 1 is characterized in that under the vertical cans made of Johnson grid, located at the lower distribution grid, there are additionally installed collectors, which are communicating via crossflow with the drainage tank located in the lower bottom of the adsorber for gas purification.

4 The adsorber for gas purification as per p. 1 , is characterized in that the distribution grids are dismountable.

5 The adsorber for gas purification as per. p. 1 is characterized in that the distribution grids are made of perforated sheet with round holes, at that, the diameter of the holes is smaller than the diameter of the adsorbent grains. 6 The adsorber for gas purification as per p. 1, is characterized in that different layers of adsorbent sorb different admixtures from the raw material to be purified.

7 The adsorber for gas purification as per p. 3 is characterized in that the drainage tank communicates with an additional union for drainage product withdrawal equipped with a drain valve attached at the lower bottom.

8 The adsorber for gas purification as per p. 3 is characterized in the level sensor of drainage tank product installed in the lower bottom of the adsorber for gas purification.

9 The adsorber for gas purification as per p. 8 is characterized in that the level sensor of drainage tank product is radar type.