CN210097635U

CN210097635U - Series connection synthetic tower

Info

Publication number: CN210097635U
Application number: CN201920755029.9U
Authority: CN
Inventors: 王灵清; 石志哲; 李庆华; 郎莹; 张曼; 张燕; 冯世昌; 孔力军; 张恰; 王海平
Original assignee: Hebei Jinniu Xuyang Chemical Co Ltd
Current assignee: Hebei Jinniu Xuyang Chemical Co Ltd
Priority date: 2019-05-23
Filing date: 2019-05-23
Publication date: 2020-02-21
Anticipated expiration: 2029-05-23

Abstract

The utility model relates to a series connection synthetic tower, this synthetic tower includes: 1 st to nth synthesis tower, steam drum and methyl alcohol house steward that connect gradually wherein: the 1 st to nth synthesis towers are independent methanol synthesis towers, the 1 st to nth synthesis towers are connected in sequence, and tube passes of the 1 st to nth tubular reactors respectively contain 1 st to nth catalyst layers; the shell sides of the 1 st to nth tubular reactors of the 1 st to nth synthesis towers are connected with a steam drum; the 1 st to nth methanol separators of the 1 st to nth synthesis towers are all connected with a methanol main pipe, and n is 4, 5 or 6. According to the utility model, the tower outlet gas of the methanol synthesis tower does not need to circulate in the synthesis tower, but continues to enter the next group of methanol synthesis system after being separated by the methanol separator until the components of the tower outlet gas are consistent with the components of the purge gas. Thereby reducing the specific energy consumption of the product.

Description

Series connection synthetic tower

Technical Field

The utility model relates to a series connection synthetic tower, particularly, the utility model relates to a can utilize the series connection synthetic tower of preparation methyl alcohol of many towers series connection technique and not need circulation tower gas under the low pressure.

Background

Methanol is an important organic chemical raw material and also an energy substitute. After being processed and converted, the methanol can be used for preparing various chemical raw materials, such as formaldehyde, acetic acid, dimethyl ether, olefin and the like, and has important influence on the development of the society in China.

The existing technology for preparing methanol from synthesis gas comprises the following steps: methanol synthesis gas (main component is H)₂CO and CO₂) Under the action of a catalyst, methanol is generated by reaction, and the reaction formula is as follows:

CO+2H₂→CH₃OH+90.73kJ/mol

CO₂+3H₂→CH₃OH+H₂O+48.02kJ/mol

the reaction is exothermic and reversible. From a kinetic point of view, increasing the temperature favors the reaction rate; from a thermodynamic perspective, it is desirable to carry out the reaction at a lower temperature. On the other hand, the methanol synthesis reaction is a reaction in which molecules are reduced, and it is advantageous to increase the reaction pressure in order to proceed the reaction in the direction of methanol production. However, as the reaction pressure increases, the power consumption of methanol synthesis increases and the amount of organic impurities produced increases. Therefore, the methanol synthesis catalyst should consider not only how to lower the reaction temperature but also how to make it have a higher conversion at a lower pressure.

At present, the domestic methanol preparation process by using synthesis gas mainly comprises a high-pressure method (19.6-29.4MPa), a medium-pressure method (8.0-12MPa) and a low-pressure method (5.0-8.0MPa), but the problem of high power consumption generally exists.

SUMMERY OF THE UTILITY MODEL

It is an object of the present invention to provide a tandem synthesis column.

According to an embodiment of the present invention, there is provided a tandem synthesis tower, comprising:

1 st to nth synthesis tower, steam drum and methyl alcohol house steward that connect gradually wherein:

the 1 st to the nth synthesis towers are independent methanol synthesis towers and respectively comprise a 1 st to an nth tubular reactor, a 1 st to an nth intermediate heat exchanger, a 1 st to an nth water cooler and a 1 st to an nth methanol separator from top to bottom,

the 1 st to nth synthesis towers are connected in sequence, except for the gas inlet of the 1 st synthesis tower and the gas reactant outlet of the nth synthesis tower, the gas reactant outlet of each synthesis tower is connected with the gas inlet of the next synthesis tower;

the tube passes of the 1 st to the nth tubular reactors respectively contain a 1 st to an nth catalyst layer;

the shell sides of the 1 st to nth tubular reactors of the 1 st to nth synthesis towers are connected with a steam drum;

the 1 st to nth methanol separators of the 1 st to nth synthesis towers are all connected with a methanol header pipe,

and n is 4, 5 or 6.

Preferably, there are no other gas inlets in the 2 nd to nth synthesis columns.

Preferably, in the 1 st to nth synthesis columns, the 1 st to 4 th tubular reactor tube side volume ratio is 1 (0.7 to 0.77): 0.53 to 0.6): 0.25 to 0.32, and when n is 5 or 6, the 5 th tubular reactor tube side volume is 0.13 to 0.32 relative to the 1 st tubular reactor tube side volume, when n is 6, the 6 th tubular reactor tube side volume is 0.13 to 0.32 relative to the 1 st tubular reactor tube side volume, and the tube side volume of the following tubular reactor is equal to or less than that of the preceding tubular reactor tube side volume.

According to the utility model discloses a tower gas that goes out of methyl alcohol synthetic tower need not be at the synthetic tower inner loop, but continues to get into next a set of methyl alcohol synthetic system after the separation of methyl alcohol separator, and the composition that until tower gas that goes out is unanimous with the composition of purge gas. Therefore, the original synthesis gas circulator can be saved, and the unit energy consumption of the product is reduced. In addition, the technology can be popularized and applied to other production devices for preparing methanol, synthetic ammonia and the like by taking the synthetic gas as a raw material, and the unit energy consumption of products can be reduced.

Drawings

Figure 1 is a schematic diagram of the structure of a series synthesis column according to the present invention.

Reference numerals

Catalyst layer of 1 steam drum 2 methanol synthetic tower

Intermediate heat exchanger of 3 methanol synthesis tower and water cooler of 4 methanol synthesis towers

5 methanol separator 6 circulating water inlet of methanol synthesis tower

7 circulating water outlet 8 crude methanol header pipe

Detailed Description

To make the features and effects of the present invention comprehensible to those of ordinary skill in the art, general description and definitions are made below with respect to terms and phrases mentioned in the specification and claims. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

In this document, the terms "comprising," "including," "having," "containing," or any other similar term, are intended to be open-ended franslational phrase (open-ended franslational phrase) and are intended to cover non-exclusive inclusions. For example, a composition or article comprising a plurality of elements is not limited to only those elements recited herein, but may include other elements not expressly listed but generally inherent to such composition or article. In addition, unless expressly stated to the contrary, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". For example, the condition "a or B" is satisfied in any of the following cases: a is true (or present) and B is false (or not present), a is false (or not present) and B is true (or present), both a and B are true (or present). Furthermore, in this document, the terms "comprising," including, "" having, "" containing, "and" containing "are to be construed as specifically disclosed and to cover both closed and semi-closed conjunctions, such as" consisting of … "and" consisting essentially of ….

All features or conditions defined herein as numerical ranges or percentage ranges are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have covered and specifically disclosed all possible subranges and individual numerical values within the ranges, particularly integer numerical values. For example, a description of a range of "1 to 8" should be considered to have specifically disclosed all subranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, and so on, particularly subranges bounded by all integer values, and should be considered to have specifically disclosed individual values such as 1, 2, 3, 4, 5, 6, 7, 8, and so on, within the range. Unless otherwise indicated, the foregoing explanations apply to all matters contained throughout this disclosure, regardless of whether they are extensive or non-extensive.

If an amount or other value or parameter is expressed as a range, preferred range, or a list of upper and lower limits, it is to be understood that all ranges subsumed therein for any pair of that range's upper or preferred value and that range's lower or preferred value, whether or not such ranges are separately disclosed, are specifically disclosed herein. Further, when a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range.

In this context, numerical values should be understood to have the precision to which the numerical value indicates, provided that the objects of the invention are met. For example, the number 40.0 should be understood to cover a range from 39.50 to 40.49.

In this context, for the case where Markush group (Markush group) or tablature is used to describe features or examples of the present invention, those skilled in the art will appreciate that a sub-group of all elements or any individual element within the Markush group or tablature may also be used to describe the present invention. For example, if X is described as "selected from the group consisting of₁、X₂And X₃The group "also indicates that X has been fully described as X₁Is claimed with X₁And/or X₂Claim (5). Furthermore, to the extent that markush group or option-based terminology is used to describe features or examples of the present invention, those skilled in the art will appreciate that any combination of sub-groups of all elements or individual elements within the markush group or option list can also be used to describe the present invention. Accordingly, for example, if X is described as "selected from the group consisting of₁、X₂And X₃Group consisting of "and Y is described as" selected from Y₁、Y₂And Y₃The group "formed indicates that X has been fully described as X₁Or X₂Or X₃And Y is Y₁Or Y₂Or Y₃Claim (5).

The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses thereof. Furthermore, there is no intention to be bound by any theory presented in the preceding prior art or the following detailed description or examples.

Examples

Example 1 design of a tandem Synthesis column

As shown in fig. 1, fig. 1 discloses a tandem synthesis tower of the present invention, which comprises:

first to fifth synthesis tower, steam drum and the methanol house steward that connects gradually, wherein:

the first to fifth synthesis towers are independent methanol synthesis towers and respectively comprise a first to fifth tubular reactors, a first to fifth intermediate heat exchangers, a first to fifth water coolers and a first to fifth methanol separators from top to bottom,

the first to fifth synthesis towers are connected in sequence, except for the gas inlet of the first synthesis tower and the gas reactant outlet of the fifth synthesis tower, the gas reactant outlet of each synthesis tower is connected with the gas inlet of the next synthesis tower;

wherein the tube passes of the first to fifth tubular reactors respectively comprise a first to fifth catalyst layer;

wherein the shell sides of the first to fifth tubular reactors of the first to fifth synthesis towers are connected with a steam drum;

wherein the first to fifth methanol separators of the first to fifth synthesis columns are all connected to a methanol header.

Wherein no other gas inlets are provided in the second to fifth synthesis columns.

Wherein the specification sizes of the tubular reactors of the first to fourth synthesis towers are reduced according to the reduction of the catalyst loading, and the specification sizes of the fourth and fifth synthesis towers are the same. Referring to a 20 ten thousand ton/year methanol plant, the catalyst loading amounts of the first to fifth synthesis towers are respectively 21 cubic, 15 cubic, 12 cubic, 6 cubic and 6 cubic, and the inner volumes of the synthesis towers are respectively 60m³、44m³、34m³、17m³、17m³The internal structure is mainly tubular distribution, the pipe diameter includes

Any of which. The specific specification of the required equipment is different with the scale of the methanol device, and the 20 ten thousand ton/year methanol device can be used as the calculation basis.

The series further comprises conventional means for feeding, directing, venting, etc., known to those skilled in the art, such as pumps, lines, pressure gauges, temperature gauges, flow rate gauges, etc., the structure and use of which are known to those skilled in the art and will not be described herein.

Example 2 method for preparing methanol using a tandem Synthesis column

Methanol was prepared using a series of synthesis columns according to example 1, with the following steps being carried out:

a. sending fresh synthesis gas converted from coke oven gas to an air inlet of a first synthesis tower, wherein the components of the fresh synthesis gas are about 20 percent of CO, and the CO is₂About 7%, H₂About 70 percent, and the pressure in the first synthesis tower is about 5.0 MPa.

b. The fresh synthesis gas enters the first synthesis tower at the lower part of the first intermediate heat exchanger of the first synthesis tower, the temperature of the fresh gas is about 40 ℃ when the fresh gas enters the first synthesis tower, the temperature of the gas is raised to 190-230 ℃ after the gas exchanges heat through the reaction of the first intermediate heat exchanger and the first catalyst layer of the first synthesis tower, and then the gas enters the first catalyst layer in the first synthesis tower for reaction.

The temperature of a reacted gas reactant from the first catalyst layer is about 220-260 ℃, heat exchange is carried out with fresh synthesis gas at the temperature of about 40 ℃, the temperature is reduced to 90-110 ℃, the gas reactant is further cooled by a first water cooler, the temperature is reduced to below 40 ℃, most of methanol generated by the reaction is condensed, the obtained gas-liquid mixture enters a methanol separator for separation, the crude methanol enters a crude methanol collecting pipe for a rectification process, the tower outlet gas which is not completely reacted enters the next synthesis tower unit for repeating the process, and the whole synthesis reaction process is repeated five times, so that the inert gas content of the system meets the index requirement. Then, the gas reactant of the fifth synthesis column is discharged as purge gas and used as fuel gas.

The temperature and pressure working conditions of the catalyst layer, the intermediate heat exchanger, the water cooler and the methanol separator of each tower are the same, and are respectively the catalyst layer temperature of 220-260 ℃, the pressure of 4.5-5.5MPa, the intermediate heat exchanger shell pass low-temperature medium of 40 ℃, the tube pass high-temperature medium of 220-260 ℃, after countercurrent heat exchange, the low-temperature medium is heated to 190-230 ℃, the high-temperature medium is cooled to 90-110 ℃, the water cooler inlet is 90-110 ℃, the outlet is below 40 ℃, the methanol separator temperature is below 40 ℃, and the working pressure is 4.5-5.5 MPa.

Wherein, the methanol synthesis catalyst is filled in the tubes, the shell side of the catalyst layer of the tower is hot water and steam, and is connected to a common steam drum. The methanol synthesis process is carried out in a catalyst layer in a tube array, the generated heat is transferred to a shell pass, hot water and steam are used for absorbing and generating medium-pressure steam, and the medium-pressure steam is separated from a public steam drum and is merged into a steam pipe network. Wherein, the cooling medium of the water cooler is circulating water. The gas discharged from the intermediate heat exchanger is cooled to 40 ℃ in a water cooler, most of high boiling point substances such as methanol and generated water are cooled into a liquid phase, the liquid phase enters a methanol separator, unreacted synthesis gas is discharged from the upper part of the methanol separator, and enters the next methanol synthesis tower unit until the unreacted synthesis gas is discharged from the upper part outlet of the methanol separator of the last synthesis tower in the form of purge gas, the purge gas is used as fuel gas, and the main components of the purge gas are less than 5 percent of CO and less than 2 percent of CO₂Unreacted H₂And a small amount of N₂And the like.

Wherein, the methanol separator is mainly used for separating gas-liquid mixture, the liquid is crude methanol, and the gas is unreacted synthesis gas. Liquid enters a crude methanol collecting pipe from an outlet at the lower part of the methanol separator to be subjected to a rectification process; the gas is synthesis gas, and the synthesis gas is discharged out of the tower through an upper outlet of the methanol separator and goes to the next methanol synthesis tower unit. The single pass conversion of carbon monoxide was adjusted by the tube diameter of the catalyst layer and the different catalyst loading of each column.

The purity of the obtained crude methanol is 85 percent and can be purified to be more than 99.9 percent through the next methanol rectification process, the CO conversion rate is more than 95 percent, the unit energy consumption of 20 ten thousand tons/year device is 500 yuan/ton, and the energy is saved by 150 yuan/ton compared with the prior device with the same scale.

Example 3

Except that 4 synthesis towers were connected in series, and the volume of the tubular reactor of each synthesis tower was set to 66m³，46m³，36m³And 19m³And catalyst loadings were set to 24 cubic, 16 cubic, 13 cubic, and 7 cubic, respectively, the tandem synthesis column was designed in the same manner as in example 1.

Example 4

The series of synthesis columns of example 3 were used and the reactions were carried out using the same starting materials and procedures as in example 2, and the series of columns was calculated to have a CO conversion of 93% or more.

Example 5

Except that 6 synthesis towers were connected in series, and the volume of the tubular reactor of each synthesis tower was set to 44m³，44m³，27m³，27m³，14m³And 14m³And the catalyst loadings were set to 15 cubes, 10 cubes, 5 cubes, and 5 cubes, respectively, the tandem synthesis column was designed in the same manner as in example 1.

Example 6

The series of synthesis columns of example 5 were used and the reactions were carried out using the same starting materials and procedures as in example 2, and the series of columns was calculated to have a CO conversion of 95% or more.

Comparative example 1

Except that 3 synthesis towers were connected in series, and the volume of the tubular reactor of each synthesis tower was set to 60m³，60m³And 60m³And the catalyst loadings were set to 20 cubes, and 20 cubes, respectively, the tandem synthesis column was designed in the same manner as in example 1.

Comparative example 2

The series of synthesis columns of comparative example 1 was used and the reactions were carried out using the same starting materials and procedures as in example 2, and the series of columns was calculated to have a CO conversion of about 85%.

Comparative example 3

Except that 7 synthesis towers were connected in series, and the volume of the tubular reactor of each synthesis tower was set to 44m³，27m³，27m³，27m³，14m³，14m³And 14m³And the catalyst loadings were set to 15 cubes, 10 cubes, 5 cubes, and 5 cubes, respectively, the tandem synthesis column was designed in the same manner as in example 1.

Comparative example 4

The series of synthesis columns of comparative example 3 were used and the reactions were carried out using the same starting materials and procedures as in example 2, and the series of synthesis columns was calculated to have a CO conversion of 85% or more.

The unconverted gas needs a compressor to do work when entering and leaving the tower every time, and at the moment, the compressor does work due to the increase of the number of the towers, so that the energy consumption is larger.

Furthermore, it was surprisingly found that the CO conversion is rather reduced when more synthesis columns are connected in series. It is believed that this is probably due to the fact that the catalyst loading per column decreases with increasing number of columns, the space velocity increases with the same amount of gas, and the per pass conversion per column decreases, resulting in a decrease in production/conversion.

Comparative example 5

Using a single volume of 172m³The same raw materials and processes as in example 2 were used to perform the reaction in a tubular reactor column with a catalyst loading of 60 cubic, which was calculated to have a CO conversion of about 85%.

Thus, it can be seen that the CO conversion is reduced when compared to example 1-2, using a single reactor with the same total volume of reactors in series and catalyst loading.

Comparative example 6

Using a single volume of 172m³The tubular reactor and the synthesis column with a catalyst loading of 60 cubic meters used the same raw materials as in example 2, and the reaction temperature was set to 220 ℃ and 260 ℃, the reaction pressure was set to 6.2-6.9MPa, and the CO conversion rate of the synthesis column was 95% or more.

Thus, it can be seen from comparison with examples 1-2 that, when a single reactor having the same total volume and catalyst loading as the reactors connected in series is also used, the reaction temperature and reaction pressure must be greatly increased to achieve the same CO conversion.

Comparative example 7

Using a single volume of 60m³And a synthesis column with a catalyst loading of 21 cubic meters and a gaseous reactant outlet of the synthesis column connected to a gas inlet of the synthesis column via a pressure pump, the same raw materials and processes as in example 2 were used for the reaction, and the conversion of CO of the synthesis column was calculated to be 80% or less.

Thus, as compared with example 1-2, it can be seen that when a reflux reactor is used, the recycle gas is generated by returning the reactor outlet gas to the gas inlet of the synthesis column by a booster pump, and a certain amount of recycle gas is required for maintaining the pressure while the amount of process gas is reduced, so that the yield is lowered and the energy consumption is increased.

In conclusion, according to the above embodiments, the utility model discloses a methanol synthesis method syngas CO conversion rate is high, and because reaction pressure is low, the unit energy consumption is low, has better energy-concerving and environment-protective effect.

Further, as can be seen from the results of comparative examples 1-2, if the number of reactors in series is less than 4, there may be a problem of insufficient CO conversion.

As can be seen from the results of comparative examples 3 to 4, if the number of reactors in series exceeds 6, the CO conversion may not be further increased and there may be a problem in that the compressor power consumption is increased and the methanol production is decreased.

From the results of comparative examples 5 and 6, it can be seen that if a single reactor is used, which is comparable to the total volume of the reactors in series and the catalyst loading, the CO conversion is very low; if higher conversions are to be achieved, the reaction temperature/pressure needs to be increased considerably, which leads to a high specific energy consumption.

As can be seen from the results of comparative example 7, compared with the preparation method using the reflux reactor in the prior art, the method according to the present invention has an advantage in that the methanol synthesis can be performed at a lower pressure, and the reduction of the synthesis pressure reduces the power consumption of the compressor.

The above embodiments are merely exemplary in nature and are not intended to limit the claimed embodiments or the application or uses of such embodiments. In this document, the term "exemplary" represents "as an example, instance, or illustration. Any exemplary embodiment herein is not necessarily to be construed as preferred or advantageous over other embodiments.

In addition, while at least one exemplary embodiment or comparative example has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations of the invention are possible. It should also be appreciated that the embodiments described herein are not intended to limit the scope, applicability, or configuration of the claimed subject matter in any way. Rather, the foregoing implementations will provide those of ordinary skill in the art with a convenient road map for implementing the described embodiment or embodiments. Further, various changes may be made in the function and arrangement of elements without departing from the scope defined in the claims, which includes known equivalents and all foreseeable equivalents at the time of filing this patent application.

Claims

1. A series-connected synthesis column, comprising:

and n is 4, 5 or 6.

2. The tandem synthesis column of claim 1,

there are no other gas inlets in the 2 nd to nth synthesis columns.

3. The tandem synthesis column of claim 1,

in the 1 st to nth synthesis towers, the 1 st to 4 th tubular reactor tube side volume ratio is 1 (0.7 to 0.77): (0.53 to 0.6): 0.25 to 0.32), and when n is 5 or 6, the 5 th tubular reactor tube side volume is 0.13 to 0.32 relative to the 1 st tubular reactor tube side volume, when n is 6, the 6 th tubular reactor tube side volume is 0.13 to 0.32 relative to the 1 st tubular reactor tube side volume, and the tube side volume of the following tubular reactor is less than or equal to that of the preceding tubular reactor tube side volume.