CN107866140B

CN107866140B - Horizontal liquefied gas sweetening tank

Info

Publication number: CN107866140B
Application number: CN201610861501.8A
Authority: CN
Inventors: 张竹梅; 王宁
Original assignee: Sinopec Engineering Inc; Sinopec Engineering Group Co Ltd
Current assignee: Sinopec Engineering Inc; Sinopec Engineering Group Co Ltd
Priority date: 2016-09-28
Filing date: 2016-09-28
Publication date: 2020-03-06
Anticipated expiration: 2036-09-28
Also published as: CN107866140A

Abstract

The invention provides a horizontal liquefied gas sweetening tank which comprises a tank body, an extraction unit and a separation unit, wherein the tank body is provided with a plurality of extraction units; the extraction unit comprises: the device comprises a feeding assembly, an extraction element and a buffer pipe which are connected in sequence, wherein the feeding assembly is provided with a liquefied gas inlet and an alkali liquor inlet with a feeding nozzle; the separation unit includes: overflow plate, coalescence board and the baffle that sets gradually along the commodity circulation direction, the overflow plate is fixed in the bottom of the jar body, and the coalescence board is fixed in the top of the jar body, and the baffle setting is at the middle part of the jar body. Under the condition that the original liquefied gas sweetening process is not greatly changed, the horizontal liquefied gas sweetening tanks are used in parallel or in series, the processing capacity of a liquefied gas sweetening system can be improved, and the equipment has the characteristics of simplicity in installation, convenience in piping and the like.

Description

Horizontal liquefied gas sweetening tank

Technical Field

The invention belongs to the field of deep processing of liquefied petroleum gas, and particularly relates to a horizontal liquefied gas sweetening tank.

Background

In the production and processing flow of petrochemical enterprises, liquefied gas produced from a catalytic or coking device contains a large amount of mercaptan, and the mercaptan is smelly and corrosive; the liquefied gas is required to be subjected to mercaptan removal treatment no matter used as a raw material for production of a downstream device or used as a product liquefied gas, so that the mercaptan sulfur content in the treated liquefied gas meets the index requirement of the downstream device or the product liquefied gas.

At present, petrochemical enterprises mostly use an extraction tower as main equipment for removing mercaptan from liquefied gas. In recent years, with the reasons of crude oil deterioration and the like and the requirement of product structure adjustment, enterprises upgrade and modify catalytic or coking units, so that the yield of liquefied gas is increased, and the mercaptan content in the liquefied gas is increased. These all put forward the requirement of expanding the ability to remove mercaptan from liquefied gas in petrochemical enterprises, and require enterprises to expand the ability to remove mercaptan from liquefied gas. Many enterprises face bottlenecks where the liquefied gas throughput is increased or the mercaptan content is increased, and the liquefied gas cannot be completely treated or the sulfur content of the treated liquefied gas is not qualified. The extraction tower is used as a key device for removing mercaptan from liquefied gas, and the bottleneck limit is more prominent. Considering that the characteristics of the energy expansion modification are that the scale is not enough to newly build an extraction tower, the modification period is short and is limited by occupied area, the investment economy and the like are considered, preferably, the small modification is carried out on the original flow, equipment which is simple to install and small in size is adopted, the arrangement of the equipment is easy, and the requirement of the increase of the processing scale is met under the condition of the minimum modification amount.

Disclosure of Invention

Aiming at the problems and requirements in the prior liquefied gas sweetening energy expansion transformation, the invention aims to provide a horizontal liquefied gas desulfurization tank. Under the condition that the original liquefied gas sweetening process is not greatly changed, the horizontal liquefied gas desulfurizing tanks are used in parallel or in series, the processing capacity of a liquefied gas sweetening system can be increased, and the equipment has the characteristics of simplicity in installation, convenience in piping, capability of shortening the construction period, investment saving and the like.

The solution adopted by the invention is as follows:

a horizontal liquefied gas sweetening tank comprises a tank body, an extraction unit and a separation unit; wherein the content of the first and second substances,

the extraction unit comprises: the device comprises a feeding assembly, an extraction element and a buffer pipe which are connected in sequence, wherein the feeding assembly is provided with a liquefied gas inlet and an alkali liquor inlet with a feeding nozzle; the buffer tube part extends into the tank body from the lower part of the tank body;

the separation unit includes: the overflow plate, the coalescence plate and the baffle are sequentially arranged along the material flow direction; the overflow plate is fixed at the bottom of the tank body, the coalescence plate is fixed at the top of the tank body, and the baffle is arranged in the middle of the tank body;

the part of the buffer tube extending into the tank body is close to a seal head at one side of the tank body and is positioned between the seal head and the overflow plate.

Compared with the prior art, the liquefied gas sweetening tank has the beneficial effects that: (1) the liquefied gas with high mercaptan content can be treated, and the removal rate can reach more than 80 percent; (2) the device can be used in parallel or series with the original extraction tower, so as to achieve the purpose of expanding the processing capacity of the original liquefied gas sweetening system; (3) compared with an extraction tower, the liquefied gas sweetening tank has the advantages of compact structure, simplicity in installation, convenience in piping, capability of shortening the construction period, investment saving and land occupation saving; (4) can ensure the continuous or long-period operation of the device.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings.

Fig. 1 is a schematic diagram of a horizontal liquefied gas sweetening tank according to an exemplary embodiment.

Fig. 2 is a schematic side view of a horizontal liquefied gas sweetening tank according to an exemplary embodiment.

Fig. 3 is a schematic structural view of an overflow plate according to an exemplary embodiment.

FIG. 4 is a schematic diagram of a baffle according to an exemplary embodiment.

Description of the reference numerals

1-liquefied gas inlet, 2-alkali liquor inlet, 3-liquefied gas outlet, 4-alkali liquor outlet, 5-vent, 6-manhole, 7-liquid level meter, 8-coalescence plate, 9-baffle, 10-overflow plate, 11-feeding nozzle, 12-extraction element, 13-buffer tube, 14-flange, 15-diversion hole, 16-trapezoidal hole and 17-hole cover.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

According to an exemplary horizontal liquefied gas sweetening tank, as shown in fig. 1, the horizontal liquefied gas sweetening tank includes a tank body, an extraction unit, and a separation unit.

The extraction unit is used for reacting the liquefied gas with the alkali liquor to generate sodium mercaptan and enabling the sodium mercaptan to enter the alkali liquor. Wherein the extraction unit comprises: the device comprises a feeding assembly, an extraction element 12 and a buffer pipe 13 which are connected in sequence, wherein the feeding assembly is provided with a liquefied gas inlet 1 and an alkali liquor inlet 2 with a feeding nozzle 11; the buffer tube 13 partially extends into the tank body from the lower part of the tank body.

The separation unit is used for ensuring the flow channel and the flow direction of the liquefied gas and the alkali liquor, guiding the reacted liquefied gas to flow upwards and guiding the alkali liquor to flow downwards, and thus realizing the separation of the liquefied gas and the alkali liquor. Wherein the separation unit comprises: the overflow plate 10, the coalescence plate 8 and the baffle 9 are arranged in sequence along the material flow direction; the overflow plate 10 is fixed at the bottom of the tank body, the coalescence plate 8 is fixed at the top of the tank body, and the baffle 9 is arranged in the middle of the tank body.

In the present invention, the "middle" is referred to as "top" or "bottom".

In the invention, the diameter and length of the tank body can be determined according to the treatment capacity of liquefied gas and the specific operation parameter design, and the two ends of the tank body are ellipsoidal or spherical end sockets. Generally, the diameter of the tank body is 1.2-4.8 meters, and the length of the tank body is 4-12 meters.

In addition, the connection mode of the horizontal liquefied gas sweetening tank and the extraction tower can be determined by referring to the existing horizontal separation tank.

In the invention, the part of the buffer tube 13 extending into the tank body is close to a seal head at one side of the tank body and is positioned between the seal head and the overflow plate 10.

According to the invention, the top of the tank body is provided with a vent 5, a manhole 6 and a liquefied gas outlet 3, the bottom of the tank body is connected with a liquid separation bag, and the liquid separation bag is provided with an alkali liquor outlet 4.

In the invention, the alkali liquor is sprayed into small droplets through the feeding nozzle 11 and dispersed into the liquefied gas.

Preferably, the feeding nozzle 11 is composed of a plurality of conical jet openings, and the diameter of each jet opening is 2-8 mm.

Preferably, the extraction element 12 has a multi-layer structure. For example, the multi-layer structure of the extraction element 12 may be composed of a packing (e.g., stainless steel mesh, plate corrugations). Through the multilayer structure of the extraction element 12, the full contact between the liquefied gas and the alkali liquor is realized, mercaptan in the liquefied gas reacts with sodium hydroxide in the alkali liquor to form sodium mercaptan, and the sodium mercaptan is dissolved in the alkali liquor and removed from the liquefied gas.

According to one embodiment, the filling height of the filler is 1 to 5 m.

Preferably, the extraction element 12 is connected to the feed assembly and the buffer pipe 13 by means of a flange 14, respectively, to facilitate the disassembly of the apparatus for service and maintenance.

Preferably, as shown in fig. 2, the length of the portion of the buffer tube 13 extending into the tank body is not less than half of the diameter of the tank body, the end of the buffer tube 13 extends into a side opening, the opening faces to the end socket of the near side, and the area of the opening is 1.2 to 1.5 times of the sectional area of the buffer tube 13.

According to one embodiment, the cross-sectional area of the extraction element 12, buffer tube 13 is between 0.005 and 0.126m²。

In addition, the distance between the buffer tube 13 and the tangent of the end socket at one side of the sweetening tank is the shortest as possible according to the requirements of equipment manufacture, so that the floor area of the horizontal liquefied gas sweetening tank can be further reduced.

Preferably, as shown in fig. 3, the overflow plate 10 is an arched plate, the overflow plate 10 is provided with a diversion hole 15 and a trapezoidal hole 16, the trapezoidal hole 16 is wide at the top and narrow at the bottom and is provided with a hole cover 17, and the hole cover 17 forms an included angle of 15-30 degrees with the overflow plate 10 obliquely downward. The number of the flow guide holes 15 is preferably one, and the number of the trapezoidal holes 16 is preferably plural.

Preferably, the height of the overflow plate 10 is 150-300 mm or less than one tenth of the diameter of the tank body.

Preferably, the upper part and the lower part of the baffle 9 are both provided with horizontal notches, wherein the distance between the upper horizontal notch and the top of the tank body is not less than one third of the diameter of the tank body, and the distance between the lower horizontal notch and the bottom of the tank body is not more than one third of the diameter of the tank body.

Preferably, as shown in fig. 4, a plurality of trapezoidal holes 16 are formed in the lower portion of the baffle 9, each trapezoidal hole 16 is wide at the top and narrow at the bottom and is provided with a hole cover 17, and the hole cover 17 forms an included angle of 15-30 degrees with the baffle 9 in an inclined downward direction.

Preferably, the coalescence plates 8 are of wire mesh construction.

According to the invention, the tank body and the liquid separating bag are respectively provided with a liquid level meter 7.

The invention is characterized in that the types of the elements of the horizontal liquefied gas sweetening tank and the arrangement thereof are designed, and unless otherwise stated, the specific size and structure of each element can be selected according to the conventional calculation mode of the horizontal separation tank design in the liquefied gas sweetening system, and the details are not repeated.

According to the invention, the horizontal liquefied gas mercaptan removal tank shown in FIG. 1 is used for removing mercaptan in liquefied gas by the following processes:

liquefied gas containing mercaptan and alkali liquor respectively enter a liquefied gas sweetening tank from a liquefied gas inlet 1 and an alkali liquor inlet 2, the alkali liquor enters an extraction unit through a feeding nozzle 11, the alkali liquor is dispersed into small drops by the feeding nozzle 11 and passes through an extraction element 12 together with liquefied gas feeding, the liquefied gas and the alkali liquor fully contact in the extraction element 12, mercaptan in the liquefied gas reacts with sodium hydroxide in the alkali liquor to form sodium mercaptide, the sodium mercaptide is dissolved in the alkali liquor and is removed from the liquefied gas, the obtained mixed liquid of the liquefied gas and the alkali liquor enters a buffer tube 13 for buffer layering, the mixed liquid of the liquefied gas and the alkali liquor is settled and separated under the action of gravity after coming out of the buffer tube, the mixed liquid close to the bottom layer reduces the flow rate and disturbance through an overflow plate 10, the coalescence plate 8 promotes the small drops to be agglomerated into large drops for settlement, and the liquefied, the alkali liquor flows downwards, and the alkali liquor and the liquefied gas leave the tank body through the liquefied gas outlet 3 and the alkali liquor outlet 4 respectively to realize separation.

In the invention, the liquefied gas containing the mercaptan can be discharged liquefied gas of a refinery liquefied gas extraction tower. After the horizontal liquefied gas mercaptan removal tank is connected in series with the extraction tower, the mercaptan sulfur removal rate of the liquefied gas can reach more than 80%.

The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Examples

When the flow rate of the liquefied gas discharged from a liquefied gas extraction tower of a certain plant is 19995 kg/h, the mass content of mercaptan sulfur is 45ppm, namely when the mass of mercaptan sulfur is 0.9 kg/h, the product index requirement that the mass content of mercaptan sulfur is not more than 10ppm is not met.

In this example, mercaptan in the discharged liquefied gas was removed by a horizontal liquefied gas mercaptan removal tank (see fig. 2 to 4) shown in fig. 1. Wherein the tank body specification is phi 2800 multiplied by 6000, and the sectional areas of the extraction element 12 and the buffer tube 13 are 0.018m²The height of the filler was 2.2 m. The horizontal liquefied gas sweetening tank is connected in series behind the liquefied gas extraction tower.

This liquefied gas containing mercaptan, alkali lye enter the liquefied gas and take off the mercaptan jar respectively from liquefied gas entry 1, alkali lye entry 2 (the flow ratio of liquefied gas, alkali lye is 1.5, the alkali lye concentration is 15 wt%), liquefied gas and alkali lye fully contact in extraction element 12, produce sodium mercaptan, sodium mercaptan dissolves in the alkali lye and gets rid of from the liquefied gas, the mixed liquid of liquefied gas and alkali lye gets into buffer tube 13 and carries out the buffering layering, the mixed liquid of liquefied gas and alkali lye comes out from buffer tube 13, the mixed liquid near the bottom reduces the velocity of flow through overflow plate 10, reduce the disturbance, and promote the droplet coalescence to become the heavy liquid drop settlement by coalescence board 8, guide liquefied gas upward flow through baffle 9, alkali lye downward flow, both leave the jar body through liquefied gas export 3 and alkali lye export 4 respectively, realize the separation.

After the liquefied gas sweetening tank is used for processing, the mass content of mercaptan sulfur in the discharged liquefied gas can be reduced to 7ppm, namely when the mass content of the mercaptan sulfur is 0.14 kg/hour, the content of the mercaptan sulfur in the discharged liquefied gas meets the requirement of product indexes, and the mercaptan sulfur removal rate of the liquefied gas sweetening tank reaches 84.4 percent.

The above-described embodiments are merely exemplary embodiments of the present invention, and it will be apparent to those skilled in the art that various modifications and variations can be made based on the principles disclosed herein, without departing from the scope of the invention as defined in the appended claims.

Claims

1. A horizontal liquefied gas sweetening tank is characterized by comprising a tank body, an extraction unit and a separation unit; wherein the content of the first and second substances,

the extraction unit comprises: the device comprises a feeding component, an extraction element (12) and a buffer pipe (13) which are connected in sequence, wherein the feeding component is provided with a liquefied gas inlet (1) and an alkali liquor inlet (2) with a feeding nozzle (11); the buffer tube (13) partially extends into the tank body from the lower part of the tank body;

the separation unit includes: an overflow plate (10), a coalescence plate (8) and a baffle (9) are arranged in sequence along the material flow direction; the overflow plate (10) is fixed at the bottom of the tank body, the coalescence plate (8) is fixed at the top of the tank body, and the baffle (9) is arranged in the middle of the tank body;

the part of the buffer tube (13) extending into the tank body is close to a seal head at one side of the tank body and is positioned between the seal head and the overflow plate (10).

2. The horizontal liquefied gas sweetening tank according to claim 1, wherein a vent (5), a manhole (6) and a liquefied gas outlet (3) are arranged at the top of the tank body, a liquid separation bag is connected to the bottom of the tank body, and an alkali liquor outlet (4) is arranged on the liquid separation bag.

3. The horizontal liquefied gas sweetening tank according to claim 1, wherein the feeding nozzle (11) is composed of a plurality of conical jet ports, and each jet port has a diameter of 2-8 mm.

4. The horizontal liquefied gas sweetening tank according to claim 1, wherein the extraction element (12) is a multi-layer structure.

5. The horizontal liquefied gas sweetening tank according to claim 1, wherein the extraction element (12) is connected to the feed assembly and the buffer pipe (13) by a flange (14).

6. The horizontal liquefied gas sweetening tank of claim 1, wherein the length of the part of the buffer tube (13) extending into the tank body is not less than half of the diameter of the tank body, the extending end is laterally opened, the opening faces to the end socket of the near side, and the area of the opening is 1.2-1.5 times of the sectional area of the buffer tube (13).

7. The horizontal liquefied gas sweetening tank according to claim 1, wherein the overflow plate (10) is an arched plate, a diversion hole (15) and a trapezoidal hole (16) are formed in the overflow plate (10), the trapezoidal hole (16) is wide at the top and narrow at the bottom and is provided with a hole cover (17), and the hole cover (17) forms an included angle of 15-30 degrees with the overflow plate (10) in an inclined downward direction; the height of the overflow plate (10) is 150-300 mm.

8. The horizontal liquefied gas sweetening tank according to claim 1, wherein the height of the overflow plate (10) is no more than one tenth of the diameter of the tank body.

9. The horizontal liquefied gas sweetening tank of claim 1, wherein the baffle (9) is provided with horizontal notches at the upper part and the lower part, wherein the distance between the upper horizontal notch and the top of the tank body is not less than one third of the diameter of the tank body, and the distance between the lower horizontal notch and the bottom of the tank body is not more than one third of the diameter of the tank body.

10. The horizontal liquefied gas sweetening tank according to claim 1 or 9, wherein a plurality of trapezoidal holes (16) are formed in the lower portion of the baffle (9), the trapezoidal holes (16) are wide in the upper portion and narrow in the lower portion and are provided with hole covers (17), and the hole covers (17) are inclined downward to form an included angle of 15-30 degrees with the baffle (9).

11. The horizontal liquefied gas sweetening tank according to claim 1, wherein the coalescence plate (8) is of wire mesh structure.