阅读说明：本技术 一种双冷却系统的等温变换炉 (Isothermal converter with double cooling systems ) 是由 施程亮 许仁春 徐洁 相红霞 左晶文 代小波 于 2019-10-24 设计创作，主要内容包括：本发明涉及一种双冷却系统的等温变换炉,包括炉体、设置在所述炉体内的催化剂框以及设置在所述催化剂框内的多根换热管,所述催化剂框内还设有原料气分配管,所述催化剂框与所述原料气分配管之间的空腔形成反应腔；其特征在于：所述催化剂框与所述炉体之间的间隙形成合成气通道；各所述换热管分为两组,包括连接第一冷媒源的第一组换热管和连接第二冷媒源的第二组换热管,所述第一冷媒源内的冷媒与所述第二冷媒源内的冷媒不同；所述第一组换热管靠近所述原料气分配管布置,所述第二组换热管靠近所述催化剂框布置。(The invention relates to an isothermal converter of a double-cooling system, which comprises a furnace body, a catalyst frame arranged in the furnace body and a plurality of heat exchange tubes arranged in the catalyst frame, wherein a raw material gas distribution tube is also arranged in the catalyst frame, and a cavity between the catalyst frame and the raw material gas distribution tube forms a reaction cavity; the method is characterized in that: a synthetic gas channel is formed in a gap between the catalyst frame and the furnace body; the heat exchange tubes are divided into two groups and comprise a first group of heat exchange tubes connected with a first refrigerant source and a second group of heat exchange tubes connected with a second refrigerant source, and refrigerants in the first refrigerant source are different from refrigerants in the second refrigerant source; the first group of heat exchange tubes are close to the feed gas distribution pipe, and the second group of heat exchange tubes are close to the catalyst frame.)

1. An isothermal converter of a double cooling system comprises a furnace body, a catalyst frame arranged in the furnace body and a plurality of heat exchange tubes arranged in the catalyst frame, wherein a raw material gas distribution tube is also arranged in the catalyst frame, and a cavity between the catalyst frame and the raw material gas distribution tube forms a reaction cavity; the method is characterized in that:

a synthetic gas channel is formed in a gap between the catalyst frame and the furnace body;

the heat exchange tubes are divided into two groups and comprise a first group of heat exchange tubes connected with a first refrigerant source and a second group of heat exchange tubes connected with a second refrigerant source, and refrigerants in the first refrigerant source are different from refrigerants in the second refrigerant source;

the first group of heat exchange tubes are close to the feed gas distribution pipe, and the second group of heat exchange tubes are close to the catalyst frame.

2. The isothermal converter of claim 1, wherein the first coolant source is a first drum and the second coolant source is a second drum;

an inlet of each first heat exchange tube in the first group of heat exchange tubes is connected with a cooling water outlet of a first steam drum, and an outlet of each first heat exchange tube is connected with a steam inlet of the first steam drum;

and the inlet of each second heat exchange tube in the second group of heat exchange tubes is connected with the cooling water outlet of the second steam drum, and the outlet of each second heat exchange tube is connected with the steam inlet of the second steam drum.

3. The isothermal converter of the dual cooling system according to claim 2, wherein the catalyst frame comprises an inner cylinder and an outer cylinder, the inner cylinder is sleeved in the outer cylinder and has a gap with the outer cylinder, and the gap between the outer cylinder and the side wall of the furnace body forms a syngas passage; the feed gas distribution pipe is arranged in the inner cylinder;

the reaction cavity is divided into a second reaction cavity between the outer cylinder and the inner cylinder and a first reaction cavity between the inner cylinder and the feed gas distribution pipe by the inner cylinder;

the first group of heat exchange tubes are arranged in the first reaction cavity, and at least part of the second group of heat exchange tubes are arranged in the second reaction cavity.

4. The isothermal converter furnace of claim 3, wherein said second set of heat exchange tubes is divided into two portions, wherein a first portion is disposed in said second reaction chamber and a second portion is disposed in said first reaction chamber and outside of said first set of heat exchange tubes and adjacent to said inner barrel.

5. The isothermal converter of claim 4, wherein said first reaction chamber is filled with a first catalyst, and said second reaction chamber is filled with a second catalyst.

6. The isothermal converter of dual cooling system of claim 5, wherein said first catalyst and said second catalyst are different catalysts.

7. The isothermal converter of the dual cooling system according to any one of claims 1 to 6, wherein the heat exchange area of the first group of heat exchange tubes is 0.4 to 0.6 of the total heat exchange area;

the heat exchange area of the first group of heat exchange tubes is the sum of the external surface areas of the first heat exchange tubes; the heat exchange area of the second group of heat exchange tubes is the sum of the external surface areas of the second heat exchange tubes;

the total heat exchange area is the sum of the heat exchange area of the first group of heat exchange tubes and the heat exchange area of the second group of heat exchange tubes.

8. The isothermal converter furnace of claim 7, wherein the heat exchange area of the second part of the second group of heat exchange tubes in the first reaction chamber is 0.06-0.2 of the total heat exchange area.

9. The isothermal converter of claim 8, wherein said inner cylinder and said outer cylinder have cross sections identical to cross sections of corresponding furnace body portions.

Technical Field

The invention relates to chemical equipment, in particular to an isothermal transformation furnace with double cooling systems.

Background

China is a country with abundant coal resources and relatively short petroleum resources, and since the 21 st century, the coal chemical industry of China enters a rapid development stage. Coal gasification is an important method for chemical processing of coal and is a key to realizing clean utilization of coal.

The CO conversion process is an indispensable ring in the modern coal chemical technology and plays a role in starting and stopping. The purpose of CO conversion is to adjust H in the synthesis gas₂And CO concentration to meet the needs of downstream users. When the CO conversion process is matched with an ammonia or hydrogen production device, the high requirement is placed on the dry basis content of CO in the conversion gas, and the dry basis content of CO is generally required to be less than 0.4%. The conventional method is to connect a low-temperature shift converter in series at the downstream of the medium-temperature shift converter to carry out low-temperature deep CO shift. This results in a series of problems of long process flow, more equipment, high investment and large system pressure drop.

(1) In the embodiment 2 of the "adiabatic series isothermal process for high-concentration CO feed gas" disclosed in the chinese invention patent with application number 201410439881.7, the process flow is set to adiabatic conversion + isothermal conversion + adiabatic conversion, in order to reduce the dry basis content of CO in the conversion gas to below 0.4%, the process flow is connected with an adiabatic conversion furnace in series at the downstream of the isothermal conversion, which results in the problems of long process flow, more equipment and large system pressure drop.

(2) For example, the invention discloses a radial flow by-product steam isothermal shift converter in patent number 201410572326.1, which belongs to first-stage shift, namely intermediate temperature shift, and the carbon monoxide content is less than or equal to 3% after single-pass reaction, and when the converter is matched with an ammonia or hydrogen production device, a low-temperature shift converter is connected in series at the downstream for deep shift to reduce the dry CO content to below 0.4%. The problems of long process flow, more equipment, high investment and large system pressure drop are caused.

Disclosure of Invention

The invention aims to solve the technical problem of providing the isothermal shift converter of the double-cooling system capable of simultaneously carrying out medium-temperature shift and low-temperature shift in one shift converter aiming at the current situation of the prior art, and meeting the requirement of a downstream system on the content of CO dry basis being less than or equal to 0.4 percent.

The technical scheme adopted by the invention for solving the technical problems is as follows: an isothermal converter of a double cooling system comprises a furnace body, a catalyst frame arranged in the furnace body and a plurality of heat exchange tubes arranged in the catalyst frame, wherein a raw material gas distribution tube is also arranged in the catalyst frame, and a cavity between the catalyst frame and the raw material gas distribution tube forms a reaction cavity; the method is characterized in that:

a synthetic gas channel is formed in a gap between the catalyst frame and the furnace body;

the heat exchange tubes are divided into two groups and comprise a first group of heat exchange tubes connected with a first refrigerant source and a second group of heat exchange tubes connected with a second refrigerant source, and refrigerants in the first refrigerant source are different from refrigerants in the second refrigerant source;

the first group of heat exchange tubes are close to the feed gas distribution pipe, and the second group of heat exchange tubes are close to the catalyst frame.

Preferably, the first refrigerant source is a first steam drum, and the second refrigerant source is a second steam drum;

an inlet of each first heat exchange tube in the first group of heat exchange tubes is connected with a cooling water outlet of a first steam drum, and an outlet of each first heat exchange tube is connected with a steam inlet of the first steam drum;

and the inlet of each second heat exchange tube in the second group of heat exchange tubes is connected with the cooling water outlet of the second steam drum, and the outlet of each second heat exchange tube is connected with the steam inlet of the second steam drum.

As a further improvement of the above aspects, the catalyst frame may include an inner cylinder and an outer cylinder, the inner cylinder is sleeved in the outer cylinder and has a gap with the outer cylinder, and the gap between the outer cylinder and the side wall of the furnace body forms a syngas channel; the feed gas distribution pipe is arranged in the inner cylinder;

the reaction cavity is divided into a second reaction cavity between the outer cylinder and the inner cylinder and a first reaction cavity between the inner cylinder and the feed gas distribution pipe by the inner cylinder;

the first group of heat exchange tubes are arranged in the first reaction cavity, and at least part of the second group of heat exchange tubes are arranged in the second reaction cavity.

The second group of heat exchange tubes are divided into two parts, wherein the first part is arranged in the second reaction cavity, and the second part is arranged in the first reaction cavity, positioned at the outer side of the first group of heat exchange tubes and close to the inner cylinder. The scheme can ensure that the primary synthesis gas in the first reaction cavity enters the second reaction cavity after the primary synthesis gas is reduced to the requirement of low-temperature reaction feeding in the flowing process.

The first reaction cavity is filled with a first catalyst, and the second reaction cavity is filled with a second catalyst.

The reaction chambers in the above embodiments may be filled with the same wide-temperature catalyst, and preferably, the first catalyst and the second catalyst are different catalysts.

Preferably, the heat exchange area of the first group of heat exchange tubes accounts for 0.4-0.6 of the total heat exchange area;

the heat exchange area is the external surface area of the heat exchange tube embedded in the catalyst bed layer. The heat exchange area of the first group of heat exchange tubes is the sum of the external surface areas of the first heat exchange tubes; the heat exchange area of the second group of heat exchange tubes is the sum of the external surface areas of the second heat exchange tubes.

The total heat exchange area is the sum of the heat exchange area of the first group of heat exchange tubes and the heat exchange area of the second group of heat exchange tubes.

The heat exchange area of the second part of the second group of heat exchange tubes in the first reaction cavity accounts for 0.06-0.2 of the total heat exchange area, so that the temperature of reaction gas entering the second reaction cavity is ensured to be about 230 ℃.

The cross sections of the inner cylinder and the outer cylinder are the same as the cross section structures of the corresponding furnace body parts.

Compared with the prior art, the low-temperature CO conversion and the medium-temperature CO conversion reaction can be integrated in a reaction furnace, raw material gas firstly passes through the catalyst inner frame to carry out the medium-temperature conversion reaction, the conversion reaction heat passes through the medium-pressure boiler water heat transfer to generate the medium-pressure saturated steam with the pressure of 4.0Mpa (G), the reaction gas after the medium-temperature conversion passes through the low-pressure boiler water to be cooled and then enters the catalyst outer frame to carry out the low-temperature conversion reaction, the dry basis content of CO is reduced to be below 0.4%, and the low-temperature conversion reaction heat passes through the low-pressure boiler water heat transfer to generate the low-pressure saturated steam with the pressure of. The system has short flow, less equipment, low investment and small system pressure drop.

Drawings

FIG. 1 is a longitudinal sectional view of a reactor section in an embodiment of the invention;

FIG. 2 is a schematic diagram of an embodiment of the present invention;

FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2;

FIG. 4 is an enlarged view of a portion C of FIG. 3;

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

As shown in fig. 1 to 4, the isothermal converter of the dual cooling system includes:

the furnace body 1 is of a conventional structure and comprises an upper seal head 11, a lower seal head 12 and a cylinder body 13 connected between the upper seal head 11 and the lower seal head 12. The upper end enclosure 11 is provided with a manhole 14, the manhole 14 is covered by a manhole cover, and the feed gas inlet 35 is arranged on the manhole cover.

And the catalyst frame is used for filling a catalyst and is arranged in the cylinder body 13, and a reaction cavity is formed by a cavity between the catalyst frame and the feed gas distribution pipe 3. The catalyst frame in this embodiment includes an inner cylinder 21 and an outer cylinder 22.

The mounting structure of the catalyst frame may be any one of those in the prior art as required. In the embodiment, the upper end and the lower end of the catalyst frame are not closed, the upper end and the lower end of a catalyst bed layer in the catalyst frame are filled with refractory balls, the outer cylinder is fixed through the cylinder, and the inner cylinder is supported through the heat exchange tubes on two sides and the first tube box 61 and the second tube box 51 on the lower sides.

The inner cylinder 21 is sleeved in the outer cylinder 22, a gap is formed between the inner cylinder and the outer cylinder 22, and a synthetic gas channel 2a is formed by the gap between the outer cylinder and the side wall of the furnace body; the raw material gas distribution pipe 3 is sleeved in the inner cylinder 21.

The reaction chamber is divided by the inner cylinder into a second reaction chamber 2b between the outer cylinder and the inner cylinder and a first reaction chamber 2c between the inner cylinder and the synthesis gas collection pipe.

The side walls of the inner cylinder 21 and the outer cylinder 22 are provided with through holes (not shown in the figure), and the through holes not only serve as flow channels for the first reaction gas and the second reaction gas, but also play a role of a gas distributor, so that the first reaction gas uniformly enters the second reaction chamber.

In this embodiment, the cross-sectional structures of the cylinder, the inner cylinder, the outer cylinder and the raw material gas distribution pipe are the same and are concentrically arranged.

This example is filled with different narrow temperature type catalysts in the first reaction chamber and the second reaction chamber. The first reaction chamber is filled with a medium-temperature shift catalyst, and the second reaction chamber is filled with a low-temperature shift catalyst. Different types of catalysts are filled according to respective reaction characteristics, so that the conversion catalyst reaction activity in a specific temperature range is fully utilized, the reaction rate is high, and the CO conversion rate is high. This mode is the preferred mode.

The first reaction cavity and the second reaction cavity can be filled with the same wide-temperature catalyst, and the wide-temperature catalyst needs to simultaneously take the medium-temperature conversion activity and the low-temperature conversion activity into consideration, so that the conversion reaction rate and the CO conversion rate are lower than those of the narrow-temperature catalyst. Meanwhile, the wide-temperature catalyst gives consideration to medium-temperature and low-temperature catalytic activity at the expense of the service life of the catalyst. The use of the wide temperature type catalyst may eliminate the need for an inner cylinder.

The raw material gas distribution pipe 3 is used for distributing raw material gas, is arranged in the middle of the inner cavity of the catalyst frame, and is formed by sequentially and detachably connecting a plurality of sections of cylinder bodies 31, wherein adjacent cylinder bodies 31 are connected through flanges 34 in the embodiment; a plurality of air inlets (not shown in the figure) for the raw material gas to enter the catalyst bed layer from the raw material gas distribution pipe 3 are arranged on the side wall of each cylinder 31; a plurality of footsteps 32 are sequentially arranged on the inner side wall of the cylinder 31 at intervals along the axial direction. The end cover is detachable, the end cover is communicated with the inner cavity of the lower end enclosure after being detached, the upper port of the raw material gas distribution pipe 3 is connected with the raw material gas inlet 35, and raw material gas enters from the raw material gas inlet.

The heat exchange tubes are provided with a plurality of heat exchange tubes, are parallel to the axis of the furnace body 1 and vertically penetrate through the catalyst bed layer, and comprise a first group of heat exchange tubes consisting of a plurality of first heat exchange tubes 41 and a second group of heat exchange tubes consisting of a plurality of second heat exchange tubes 42. The first heat exchange tubes 41 and the second heat exchange tubes 42 are arranged at regular intervals on concentric circumferential lines in the reaction chamber.

For the sake of distinction, each of the first heat exchange tubes 41 is shown as a solid circle and each of the second heat exchange tubes 42 is shown as a hollow circle in fig. 3.

Wherein each first heat exchange tube 41 is arranged in the first reaction chamber close to the feed gas distribution tube 3. The inlet of each first heat exchange pipe is connected with a first cooling water pipeline 62 through a first pipe box 61, and the first cooling water pipeline 62 is connected with the cooling water outlet of the first steam drum 6; the outlet of each first heat exchange pipe 41 is connected with a first steam pipeline 64 through a first steam collecting device 63, and the first steam pipeline 64 is connected with the steam inlet of the first steam drum 6. The first reaction cavity removes heat through medium-pressure boiler water to obtain a byproduct of medium-pressure saturated steam with the pressure of 4.0Mpa (G), and the saturation temperature is about 252 ℃.

Each second heat exchange tube 42 is divided into two portions, a first portion being disposed in the second reaction chamber and a second portion being disposed in the first reaction chamber and disposed adjacent to the inner tube 21. In the embodiment, 3 layers of second heat exchange tubes 42 are arranged in the first reaction cavity, and 1-5 layers are preferred. The inlet of each second heat exchange pipe 42 is connected with a second cooling water pipe 52 through a second pipe box 51, and the second cooling water pipe 52 is connected with the cooling water outlet of the second steam drum 5; the outlet of each second heat exchange tube 42 is connected to a second steam conduit 54 via a second steam collection device 53, the second steam conduit 54 being connected to the steam inlet of the second drum. The second reaction cavity removes heat by a low-pressure boiler through water to obtain a byproduct of 0.45Mpa (G) of low-pressure saturated steam, and the temperature of the saturated steam is about 155 ℃.

In this embodiment, the heat exchange area of the first group of heat exchange tubes accounts for 0.41 of the total heat exchange area; the heat exchange area of the second part of the second group of heat exchange tubes accounts for 0.11 of the total heat exchange area, and the heat exchange area of the first part of the second group of heat exchange tubes arranged in the second reaction cavity accounts for 0.48 of the total heat exchange area.

The heat exchange area of the first group of heat exchange tubes is the sum of the external surface areas of the first heat exchange tubes in the catalyst bed layer; the heat exchange area of the second group of heat exchange tubes is the sum of the external surface areas of the second heat exchange tubes in the catalyst bed layer; the total heat exchange area is the sum of the heat exchange area of the first group of heat exchange tubes and the heat exchange area of the second group of heat exchange tubes.

The medium-temperature shift reaction is carried out in the first reaction cavity, medium-pressure saturated steam of 4.0Mpa (G) is obtained as a byproduct by water heat removal of a medium-pressure boiler at the temperature of about 252 ℃, and the operation temperature of the reaction is maintained between 240 ℃ and 280 ℃. The second reaction chamber is used for carrying out low-temperature shift reaction, and low-pressure saturated steam of 0.45Mpa (G) is obtained as a byproduct by water heat removal of a low-pressure boiler at the temperature of about 155 ℃, and the operation temperature of the reaction is maintained between 200 and 240 ℃. In order to better link the temperature of the converted gas in the first reaction cavity and the temperature of the converted gas in the second reaction cavity, the second part of the second group of heat exchange tubes is arranged in the first reaction cavity, and the converted gas is reduced by 10-40 ℃ through strong heat exchange between boiler water with lower temperature (low-pressure boiler water at about 155 ℃) and high-temperature converted gas, so that the temperature of the converted gas entering the second reaction cavity is about 230 ℃.

The first and second headers 61 and 51 may have a ring pipe structure, as shown in fig. 1 of the present embodiment; the two tube boxes can also be box structures which are arranged in an up-and-down overlapping mode, and the two tube boxes can also be in a tube plate mode.

The first steam collecting means 63 and the second steam collecting means 53 may be a loop pipe or a header pipe.

The first steam line 64 and the second steam line 54 are each provided with a first expansion joint 65 and a second expansion joint 55, respectively, for absorbing thermal stresses.

The working principle of the isothermal conversion furnace of the double cooling system is described as follows:

the raw material gas enters an upper end socket of the reactor through a raw material gas inlet 35, descends along a channel of a raw material gas distribution pipe, uniformly enters a catalyst bed layer of the first reaction cavity through each through hole on the raw material gas distribution pipe, and is subjected to medium-temperature CO conversion reaction to form first reaction gas, wherein the reaction temperature is 240-280 ℃. The medium-pressure cooling water in the first steam pocket enters each first heat exchange pipe 41 from the first cooling water pipeline in a natural circulation mode, the reaction heat of the catalyst bed layer in the first reaction cavity is taken away, the generated steam-water mixture returns to the first steam pocket through the first steam collecting device and the first steam pipeline for steam-liquid separation, and medium-pressure saturated steam of 4.0Mpa (G) is a byproduct. The medium pressure saturated steam is sent downstream through medium pressure saturated steam line 56; medium pressure boiler water is fed into the first drum through a medium pressure boiler feed water line 67.

The first reaction gas flows in the radial direction and enters the second reaction chamber from the first reaction chamber through the through holes on the inner barrel. Before entering the second reaction cavity, when the first reaction gas flows through the second heat exchange tube in the first reaction cavity, the first reaction gas exchanges heat with the low-pressure cooling water in the part of the second heat exchange tube, after the temperature of the first reaction gas is gradually reduced to meet the requirement of low-temperature CO conversion feeding temperature, the first reaction gas enters the catalyst bed layer in the second reaction cavity through the through holes on the inner cylinder to carry out low-temperature CO conversion reaction, and second reaction gas is formed.

And low-pressure cooling water in the second steam pocket enters each second heat exchange pipe from the second cooling water pipeline and the second pipe box in a natural circulation mode, reaction heat of a catalyst bed layer in the second reaction cavity is taken away, a generated steam-water mixture returns to the second steam pocket through the second steam collecting device and the second steam pipeline for steam-liquid separation, low-pressure saturated steam of 0.45Mpa (G) is obtained as a byproduct, the low-pressure saturated steam is sent to the downstream through the low-pressure saturated steam pipeline 56, and low-pressure boiler water is supplemented into the second steam pocket through the low-pressure boiler water supply pipeline 57.

The raw material gas is subjected to medium-temperature shift reaction and low-temperature shift reaction in the same shift furnace in sequence, and the CO content is reduced to be below 0.4 percent (V percent, dry basis).

The second reactant gas is delivered to the downstream system through the syngas channel 2a via the bottom head cavity and the syngas delivery conduit 33.