Energy-saving production device for preparing methyl tert-butyl ether by isobutane dehydrogenation method

Abstract

The utility model relates to an energy-saving production device for preparing methyl tert-butyl ether by an isobutane dehydrogenation method. A raw material gasifier is arranged between the catalytic distillation tower feeding and discharging heat exchanger and the catalytic distillation tower, a temperature sensor is arranged on a feeding pipeline from the raw material gasifier to the catalytic distillation tower, a gas phase at the top of the catalytic distillation tower is divided into two pipelines, a compressor is additionally arranged on one pipeline, and an automatic flow regulating valve is additionally arranged on the other pipeline; a cold-side material outlet of the distillation tower feeding and discharging heat exchanger is connected with a cold-side material inlet of the raw material gasifier, a cold-side material outlet of the raw material gasifier is connected with a feeding hole in the middle lower part of the catalytic distillation tower, and a tower top discharging pipeline of the catalytic distillation tower is respectively connected with an inlet of the compressor and a hot-side material inlet of the condenser; an outlet pipeline of the compressor is connected with a hot measuring material inlet of the raw material gasifier, and a hot measuring material outlet of the raw material gasifier is connected with a liquid inlet of the return tank. According to the utility model, a heat pump technology is adopted, so that the heating power of the tower kettle reboiler is reduced, and the steam consumption is reduced; and the method is more economical.

Description

TECHNICAL FIELD

[0001] The utility model belongs to methyl tertiary butyl ether production device and process field, especially, it relates to a kind of energy-saving production device of preparing methyl tertiary butyl ether by isobutane dehydrogenation method. BACKGROUND

[0002] Methyl tertiary butyl ether (abbreviation MTBE) is a kind of transparent, colorless, organic liquid with ether-like odor, is a good gasoline additive, and has wide application in biological analysis technology. The current synthesis MTBE process is mainly etherification process, raw material isobutene and methanol occur etherification reaction under certain temperature, pressure, acidic catalyst catalysis condition, product is obtained after separation and purification Product MTBE. MTBE is prepared by isobutane dehydrogenation method, which is the most widely used production method at present, and the specific production process is as shown in Figure 1 As shown in the figure, the mixed carbon four containing isobutene and isobutane from isobutane dehydrogenation device is mixed with methanol (A), enters pre-reactor (2) after preheater (1), isobutene and methanol occur etherification reaction to generate MTBE in pre-reactor (2), the mixture at the outlet of pre-reactor (2) is heated in catalytic distillation column inlet-outlet heat exchanger (3) after being discharged from catalytic distillation column (5) and then enters catalytic distillation column (5) for continuous reaction, in order to ensure the conversion rate of isobutene, catalytic distillation column will also supplement a certain amount of methanol (B). The gas phase at the top enters condenser (7), and the liquid phase after condensation is ether after carbon four and methanol, which enters reflux tank (8), and the liquid phase in reflux tank (8) is returned to catalytic distillation column (5) by reflux pump (9) as reflux, and the other part is extracted (C); reboiler (10) is arranged at the bottom, and MTBE product (D) is extracted at the bottom.

[0003] Since the reaction of isobutane dehydrogenation to generate isobutene is an equilibrium reaction, the single-pass conversion rate is 40-45% (reference: Song Yanmin et al., isobutane catalytic dehydrogenation to prepare isobutene technology, fine and special chemicals, 2006, 14 (17): 10-19), the mixed carbon four from dehydrogenation reactor contains a large amount of unreacted isobutane in addition to isobutene, which enters pre-reactor and catalytic distillation column with raw material, and is finally extracted from the top of catalytic distillation column. Catalytic distillation column needs to provide a large amount of heat, part of which is used to ensure the conversion rate of isobutene, and the other part is used to evaporate the unreacted mixed carbon four in raw material, which is one of the reasons for high energy consumption per product in MTBE production process.

[0004] The energy saving measures for the MTBE production process at present mainly have two kinds: one is to adopt heat coupling technology, to set a catalytic distillation column inlet and outlet heat exchanger (3), the high temperature product taken out from the catalytic distillation column is used to preheat the feed of the catalytic distillation column, so that the feed is increased to a certain temperature before entering the column, and the heating steam quantity of the column is reduced; the other is to adopt heat pump rectification technology, the column top steam of the catalytic distillation column is pressurized by a compressor, and the temperature of the pressurized gas is increased, and the gas is heated to a certain temperature and used as the heat source of the column reboiler, so that the steam quantity of the column reboiler is reduced.

[0005] The heat coupling measure of preheating the feed by the column outlet of the catalytic distillation column can increase the temperature of the feed by 10-20 DEG C, and the phase state of the material is not changed, that is, the material is not gasified. Therefore, the steam quantity saved by the energy saving measure is not large; and for the heat pump rectification technology, the carbon four after the methanol and ether is taken out from the top of the catalytic distillation column, and the MTBE and a small amount of heavy components are taken out from the column, due to the large difference between the boiling points of the column top and column materials, the operation temperature difference between the column top and column is large. When the operation pressure is 0.78 MPaG and the total column pressure drop is 50 kPa, the column top gas phase temperature is 59 DEG C, the column temperature is 143 DEG C, and the column top and column temperature difference is 84 DEG C. At this time, if the column top gas phase is compressed to be used as the heat source of the column material heating, the column top gas phase needs to be increased to a high pressure, the compression ratio of the compressor is large (usually more than 5), and the power of the compressor is high, so that the power consumption is increased. Through comprehensive comparison, the energy saving scheme of the high compression ratio heat pump rectification is not dominant in economy.

[0006] Therefore, improving the heat energy utilization rate in the above production process and strengthening the heat coupling in the product separation process are the problems urgently needed to be solved for reducing the energy consumption of the MTBE product. SUMMARY

[0007] The utility model provides a kind of isobutane dehydrogenation method preparation methyl tert-butyl ether's energy-saving production device, and the gas phase of catalytic distillation column is compressed by lower compression ratio to increase pressure and temperature, and the raw material after preheating of pre-reactor outlet is further heated, so that part of raw material is gasified before entering catalytic distillation column, reduce the heat required for material gasification in column, and reduce the energy consumption of product.

[0008] The utility model is realized by the following technical solutions:

[0009] The application relates to an energy-saving production device for preparing methyl tert-butyl ether by dehydrogenation of isobutane, which is based on an existing process flow, wherein a raw material gasifier (4) is arranged between a catalytic distillation column feed and discharge heat exchanger (3) and a catalytic distillation column (5), a temperature sensor (11) is arranged on a feed pipeline of the raw material gasifier (4) to the catalytic distillation column, a catalytic distillation column (5) top gas phase is divided into two pipelines, a compressor (6) is added to one of the pipelines, and an automatic flow regulating valve (12) is added to the other pipeline; a distillation column feed and discharge heat exchanger (3) cold side material outlet is connected with a raw material gasifier (4) cold side material inlet, a raw material gasifier (4) cold side material outlet is connected with a catalytic distillation column (5) middle and lower part inlet, a catalytic distillation column (5) top material pipeline is respectively connected with a compressor (6) inlet and a condenser (7) hot measuring material inlet, a compressor (6) outlet pipeline is connected with a raw material gasifier (4) hot measuring material inlet, and a raw material gasifier (4) hot measuring material outlet is connected with a reflux tank (8) liquid inlet.

[0010] The adjusted process is that a raw material (A) feed pipeline is connected with a preheater (1) cold side material inlet, a preheater (1) cold side material outlet is connected with a pre-reaction device (2) material inlet, a pre-reaction device (2) material outlet is connected with a catalytic distillation column feed and discharge heat exchanger (3) cold side material inlet, a catalytic distillation column feed and discharge heat exchanger (3) cold side material outlet is connected with a raw material gasifier (4) cold side material inlet, a raw material gasifier (4) cold side material outlet is connected with a catalytic distillation column (5) middle and lower part inlet, a catalytic distillation column (5) top material pipeline is respectively connected with a compressor (6) inlet and a condenser (7) hot measuring material inlet, a compressor (6) outlet pipeline is connected with a raw material gasifier (4) hot measuring material inlet, a raw material gasifier (4) hot measuring material outlet is connected with a reflux tank (8) liquid inlet, a condenser (7) hot measuring material outlet is connected with a reflux tank (8) liquid inlet, a reflux tank (8) liquid outlet is connected with a reflux pump (9) liquid inlet, a reflux pump (9) liquid outlet is respectively connected with a catalytic distillation column (5) reflux liquid inlet and a next section device liquid (C) inlet, a catalytic distillation column (5) tower kettle material outlet is connected with a catalytic distillation column feed and discharge heat exchanger (3) hot measuring material inlet, a catalytic distillation column feed and discharge heat exchanger (3) hot measuring material outlet is connected with a next section device liquid (D) inlet, a supplemental methanol (B) material pipeline is connected with a catalytic distillation column (5) upper methanol inlet of a reaction section, and a catalytic distillation column (5) tower kettle material outlet is connected with a reboiler (10) cold side material inlet, and the reboiler (10) cold side material outlet is connected with a catalytic distillation column (5) reboiler return port.

[0011] The raw material of the existing production process, methanol and mixed carbon four, enters a preheater, is preheated to 40 DEG C, and then enters a pre-reactor, and after reaction, the material temperature is 60 DEG C, and then the material enters a catalytic distillation column inlet-outlet heat exchanger, and after heat exchange with the catalytic distillation column outlet material, the material is heated to 80 DEG C, and then the material enters the catalytic distillation column; the catalytic distillation column top gas phase enters a condenser for condensation, and the condensate enters a reflux tank; the liquid phase in the reflux tank enters a reflux pump, and after passing through the reflux pump, part of the liquid phase returns to the catalytic distillation column as reflux, and the other part of the liquid phase is taken out to the next section; the catalytic distillation column bottom material is taken out to the catalytic distillation column inlet-outlet heat exchanger to exchange heat with the raw material, and then is taken out to the next section.

[0012] The catalytic distillation column (5) top gas phase part (or all) enters a compressor (6), the gas phase is heated and pressurized after compression, enters a raw material gasifier (4) to heat the preheated raw material, and the raw material is partially gasified at this point and then enters the catalytic distillation column. The temperature sensor (11) arranged on the raw material gasifier (4) cold side material outlet pipeline controls the flow automatic regulating valve (12) on the catalytic distillation column (5) top gas phase to condenser (7) pipeline, indirectly controls the gas phase flow entering the compressor (6), and further controls the heating capacity of the raw material gasifier (4). The raw material is heated and partially gasified in the raw material gasifier (4), thereby reducing the heat required for the material to be gasified in the catalytic distillation column (5), and achieving the purpose of energy saving.

[0013] The compression ratio of the compressor (6) is 2.0-3.0.

[0014] The compressor (6) inlet gas mass: the total gas phase amount of the catalytic distillation column (5) is 0.1-1.

[0015] The raw material gasifier (4) operating temperature is 85-110 DEG C.

[0016] The raw material gasifier (4) outlet gas phase mass: the total raw material gasifier (4) inlet mass is 0.1-0.75.

[0017] The utility model discloses an energy -conserving type isobutane dehydrogenation method methyl tertiary butyl ether production device adopts heat pump technology, and the catalytic distillation column top gas phase is compressed, and after the gas is heated and pressurized, goes to raw material gasification heating, and makes part raw material to take place gasification before entering the catalytic distillation column, reduced the heat energy that the material needs to be gasified in the catalytic distillation column, reduced the heating power of tower kettle reboiler, reduced the steam consumption, reached the effect of energy saving, and the compression ratio of compressor is lower, compared with the high compression ratio heat pump rectification energy -conserving scheme is more economical.

[0018] The main operating parameters of the utility model are the pressure ratio of the compressor, the gas holdup of the vaporizer and the ratio of the compressor intake volume to the total gas volume at the top of the catalytic distillation tower. The main economic indicators are the steam consumption of the catalytic distillation tower and the additional power consumption after adding the compressor. Compared with the existing process flow ( Figure 1 ), the feed rate of raw material mixed C4 is 74600kg / h, the feed rate of methanol to the pre-reactor is 14900kg / h, the feed rate of methanol to the catalytic distillation tower is 800kg / h, and the reflux ratio of the catalytic distillation tower is 1.3. The following table lists the main operating parameters and economic indicators under different working conditions of the existing process flow and the present invention. Through the comparison of different indicators, it can be seen that the solution of the present invention is economical.

[0019] Table 1 Comparison of economic performance indicators of the utility model and the existing technology

[0020]

[0021] Note: Electricity fee is calculated at 0.6 yuan / kwh, and steam fee is calculated at 200 yuan / ton. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Device diagram of prior art

[0023] Figure 2 It is an apparatus diagram of the present utility model.

[0024] Description of reference numerals:

[0025] A-mixed C4 and methanol, B-supplemented methanol, C-etherified C4 and methanol, D-MTBE product

[0026] 1- Preheater, 2- Prereactor, 3- Catalytic distillation tower inlet and outlet heat exchanger, 4- Raw material vaporizer, 5- Catalytic distillation tower, 6- Compressor, 7- Condenser, 8- Reflux tank, 9- Reflux pump, 10- Reboiler, 11- Temperature sensor, 12- Automatic flow control valve DETAILED DESCRIPTION

[0027] Example 1

[0028] The process of embodiment 1 of the utility model is shown in FIG. Figure 2 The feed rate of raw material mixed C4 is 74600 kg / h, the feed rate of methanol to the pre-reactor is 14900 kg / h, and the feed rate of supplementary methanol to the catalytic distillation tower is 800 kg / h. The composition of each main stream is shown in Table 2.

[0029] Table 2 Composition of main streams in Example 1 (wt%)

[0030]

[0031] The raw material C4 and methanol are mixed and then enter the preheater (1), the mixture is preheated to 40°C and then enters the pre-reactor (2), which can be provided with multiple units for online catalyst replacement. The mixture from the pre-reactor enters the catalytic distillation column inlet-outlet heat exchanger (3) and exchanges heat with the column outlet of the catalytic distillation column (5), the mixture is preheated to 80°C and then enters the raw material vaporizer (4), where the raw material exchanges heat with the compressed catalytic distillation column overhead gas, and the material is partially vaporized and then enters the upper part of the stripping section of the catalytic distillation column; the catalytic distillation column also has a feed of supplemental methanol, which enters the column from the upper part of the reaction section. After the mixture completes the reaction and separation in the catalytic distillation column, the ether is collected from the top, and the gas phase of the C4 and methanol enters the compressor (6) with a small compression ratio to be compressed and heated, and then enters the raw material vaporizer (4) to heat the raw material vaporization, and then enters the reflux tank (8) after being condensed by the raw material vaporizer (4). The other part of the gas phase at the top enters the condenser (7) and is condensed into a liquid phase, which also enters the reflux tank (8). The liquid phase in the reflux tank (8) is returned to the top of the catalytic distillation column by the reflux pump (9), and the other part is collected to the next section. The product MTBE is collected from the column bottom of the catalytic distillation column, exchanges heat with the raw material in the inlet-outlet heat exchanger (3), and is then collected to the next section. A temperature sensor (11) is provided at the outlet of the raw material vaporizer, and an adjusting valve (12) is provided on the pipeline of the catalytic distillation column overhead gas to the condenser, so that the gas flow of the catalytic distillation column overhead gas to the condenser is controlled by the temperature of the material at the outlet of the raw material vaporizer. The operating parameters of each device are shown in Table 3.

[0032] Table 3 Operating conditions of each device in Example 1

[0033]

[0034]

[0035] Figure 1 The process flow without setting the overhead gas compression and related heat coupling is shown in Figure 1, which is under the same feed conditions. The mixed C4 containing isobutylene and butane is mixed with methanol, preheated and then enters the pre-reactor, the outlet material of the pre-reactor is preheated by the catalytic distillation column outlet material and then enters the upper part of the stripping section of the catalytic distillation column for further reaction, the catalytic distillation column overhead gas enters the condenser, and then enters the reflux tank after being condensed, the liquid phase in the reflux tank returns to the catalytic distillation column as reflux by the reflux pump, and the other part is collected to the next section; the catalytic distillation column outlet material exchanges heat with the pre-reactor outlet material and is then collected as product.

[0036] Figure 1 and Figure 2 The energy consumption comparison of the process flow is shown in Table 4, Example 1 Figure 2 The compression ratio of the compressor in the process flow is 2.5, and the energy consumption of the process flow without setting the compressor and related heat coupling is 1.5 times that of the process flow with the compressor and related heat coupling. Figure 1Compared with the process, the steam consumption per hour is reduced by 28%, 539kwh of electricity is newly consumed, the electricity charge is 0.6 yuan / kwh, the steam charge is 200 yuan / ton, the charge saved per unit time is 617 yuan, according to the annual operation time of 8000 hours, 493.6 million yuan of energy consumption charge is saved per year, and the process of the embodiment 1 of the utility model has economy.

[0037] Table 4: Energy consumption and electricity consumption comparison of two process flows of embodiment 1

[0038] Name Steam consumption (ton / hour) New electricity consumption (kwh) Comparison process ( Figure 1 ) 16.7 -- Example 1 Scheme Figure 2 ) 12.0 539

[0039] Embodiment 2

[0040] The process and the feeding condition of the embodiment 2 are same as those of the embodiment 1, the air intake, the compression ratio of the compressor and the gasification rate of the gasifier are adjusted, and the operation parameters of each device are shown in Table 5. Figure 1 The energy consumption and the electricity consumption comparison of the process are shown in Table 6, the steam consumption per hour is reduced by 10%, 132kwh of electricity is newly consumed, the electricity charge is 0.6 yuan / kwh, the steam charge is 200 yuan / ton, the charge saved per unit time is 261 yuan, according to the annual operation time of 8000 hours, 208.6 million yuan of energy consumption charge is saved per year, and the process of the embodiment 2 of the utility model has economy.

[0041] Table 5: Operation condition table of each device of embodiment 2

[0042]

[0043]

[0044] Table 6: Energy consumption and electricity consumption comparison of two process flows of embodiment 2

[0045] Name Steam consumption (ton / hour) New electricity consumption (kwh) Comparison procedure Figure 1 ) 16.7 -- Example 2 Scheme Figure 2 ) 15.0 132

[0046] Embodiment 3

[0047] The process and the feeding condition of the embodiment 3 are same as those of the embodiment 1, the air intake, the compression ratio of the compressor and the gasification rate of the gasifier are adjusted, and the operation parameters of each device are shown in Table 7. Figure 1 The energy consumption and the electricity consumption comparison of the process are shown in Table 8, the steam consumption per hour is reduced by 56%, 1543kwh of electricity is newly consumed, the electricity charge is 0.6 yuan / kwh, the steam charge is 200 yuan / ton, the charge saved per unit time is 954 yuan, according to the annual operation time of 8000 hours, 763.4 million yuan of energy consumption charge is saved per year, and the process of the embodiment 3 of the utility model has economy.

[0048] Table 7: Operation condition table of each device of embodiment 3

[0049]

[0050] Table 8 Energy consumption and power consumption comparison of two process flows of Example 3

[0051] Name Steam consumption (ton / hour) New electricity consumption (kwh) Comparison process ( Figure 1 ) 16.7 -- Example 3 Scheme Figure 2 ) 7.3 1543

[0052] The above examples are only preferred embodiments for fully illustrating the present application, and the protection scope of the present application is not limited thereto. Any equivalent substitutions or transformations made by those skilled in the art based on the present application are within the protection scope of the present application. The protection scope of the present application is subject to the claims.

Claims

1. An energy-saving production device for preparing methyl tert-butyl ether by dehydrogenation of isobutane, characterized in that the catalyst A raw material vaporizer (4) is arranged between the distillation tower inlet and outlet heat exchanger (3) and the catalytic distillation tower (5); a temperature sensor (11) is arranged on the feed pipeline from the raw material vaporizer (4) to the catalytic distillation tower; the gas phase at the top of the catalytic distillation tower (5) is divided into two routes, a compressor (6) is added to one pipeline, and a flow automatic regulating valve (12) is added to the other pipeline; the cold side material outlet of the distillation tower inlet and outlet heat exchanger (3) is connected to the cold side material inlet of the raw material vaporizer (4), the cold side material outlet of the raw material vaporizer (4) is connected to the middle and lower feed port of the catalytic distillation tower (5), the top discharge pipeline of the catalytic distillation tower (5) is respectively connected to the compressor (6) inlet and the condenser (7) heat measurement material inlet, the compressor (6) outlet pipeline is connected to the heat measurement material inlet of the raw material vaporizer (4), and the heat measurement material outlet of the raw material vaporizer (4) is connected to the liquid inlet of the reflux tank (8).

2. The energy-saving production device for preparing methyl tert-butyl ether by dehydrogenation of isobutane according to claim 1, characterized in that: The feed line of raw material (A) is connected to the cold side material inlet of preheater (1), the cold side material outlet of preheater (1) is connected to the material inlet of prereactor (2), the material outlet of prereactor (2) is connected to the cold side material inlet of catalytic distillation tower inlet and outlet heat exchanger (3), the cold side material outlet of distillation tower inlet and outlet heat exchanger (3) is connected to the cold side material inlet of raw material vaporizer (4), the cold side material outlet of raw material vaporizer (4) is connected to the middle and lower feed port of catalytic distillation tower (5), the top discharge line of catalytic distillation tower (5) is respectively connected to the inlet of compressor (6) and the heat measurement material inlet of condenser (7), the outlet line of compressor (6) is connected to the heat measurement material inlet of raw material vaporizer (4), the heat measurement material outlet of raw material vaporizer (4) is connected to the liquid inlet of reflux tank (8), the condenser The thermal measurement material outlet of the device (7) is connected to the liquid inlet of the reflux tank (8), the liquid outlet of the reflux tank (8) is connected to the liquid inlet of the reflux pump (9), the liquid outlet of the reflux pump (9) is respectively connected to the reflux liquid inlet of the catalytic distillation tower (5) and the liquid (C) inlet of the next section equipment, the material outlet of the catalytic distillation tower (5) is connected to the thermal measurement material inlet of the distillation tower inlet and outlet heat exchanger (3), the thermal measurement material outlet of the distillation tower inlet and outlet heat exchanger (3) is connected to the liquid (C) inlet of the next section equipment, the supplementary methanol (B) material pipeline is connected to the methanol inlet of the upper part of the reaction section of the catalytic distillation tower (5), the material outlet of the catalytic distillation tower (5) is connected to the cold side material inlet of the reboiler (10), and the cold side material outlet of the reboiler (10) is connected to the return port of the reboiler of the catalytic distillation tower (5).

Images