Preparation method and system of isooctyl nitrate

Abstract

The invention relates to the technical field of chemical engineering, in particular to a preparation method and system of isooctyl nitrate. The invention provides a preparation method of isooctyl nitrate, which comprises the following steps: A) feeding nitric acid, sulfuric acid and isooctyl alcohol into a microchannel reactor according to a flow ratio of 1.05: 2-2.5: 1, and reacting to obtain an isooctyl nitrate crude product; b) performing waste acid regeneration on the waste acid generated by the reaction; and carrying out alkali washing deacidification and water washing desalination on the isooctyl nitrate crude product to obtain the isooctyl nitrate. The preparation method and system provided by the invention are safer in reaction; the micro-channel reactor has no amplification effect from small test to industrial amplification; the catalyst can be used for synthesis reactions under various extreme conditions; the specific surface area is increased, and heat released by reaction is rapidly transferred; and the heat transfer process and the mass transfer process are enhanced. And the conversion rate and the product yield of the prepared isooctyl nitrate are excellent, and the quality of the prepared isooctyl nitrate is excellent.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a preparation method and system of isooctyl nitrate. Background Art

[0002] Isooctyl nitrate is an important diesel fuel additive that can increase the cetane number (CN value) of diesel, thereby accelerating diesel ignition and improving engine performance. Especially for secondary processed diesel, its cetane number can be increased. The effect of addition varies depending on the base oil. Generally, adding 0.1% to 0.3% of isooctyl nitrate can increase the cetane number by 2 to 9 units. Fuel additives can change certain properties of fuel, making it conducive to improving combustion, so as to reduce the emission of harmful substances in the exhaust of internal combustion engines and achieve energy conservation. There is no need to add equipment or change the structure of vehicles and internal combustion engines. It can improve the fuel energy utilization rate of diesel alcohol at low speed and low load, thereby improving combustion efficiency and reducing pollutant emissions. Therefore, it has gradually been widely used in recent years.

[0003] The existing preparation processes of isooctyl nitrate all use intermittent reactors, which have many disadvantages, such as difficult to control reaction energy, high reaction risk, low product yield, low quality, low operating flexibility, and inability to produce continuously. At the same time, the three wastes in the production process are also a problem to be dealt with. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a method and system for preparing isooctyl nitrate, which has low reaction safety risk, high product yield and high quality.

[0005] The present invention provides a method for preparing isooctyl nitrate, comprising the following steps:

[0006] A) feeding nitric acid, sulfuric acid and isooctyl alcohol into a microchannel reactor at a flow ratio of 1.05:2 to 2.5:1 to react and obtain a crude isooctyl nitrate;

[0007] B) regenerating the spent acid produced by the reaction;

[0008] The crude isooctyl nitrate is subjected to alkali elution to remove acid and water elution to remove salt, thereby obtaining isooctyl nitrate.

[0009] Preferably, in step A), the feed rate of the microchannel reactor is 2.0-3.2 kg / min; the reaction temperature is 20-50° C., and the reaction pressure is 0.3-1.5 MPa.

[0010] Preferably, in step B), the alkaline washing solution used for the alkaline washing and deacidification is an aqueous solution of sodium hydroxide with a mass concentration of 18% to 20%.

[0011] Preferably, in step B), the waste acid produced by the reaction is regenerated and then reused in step A).

[0012] Preferably, in step B), regenerating the spent acid produced by the reaction comprises the following steps:

[0013] a) sending the waste acid produced by the reaction into an incinerator to carry out waste acid cracking;

[0014] b) pressurizing the process gas obtained in step a) and feeding it into a primary reactor to carry out a primary reaction;

[0015] c) condensing the process gas obtained in step b) through a primary condenser, and recycling the obtained sulfuric acid to step A);

[0016] The process gas discharged from the primary condenser is passed through a primary electric demister to remove acid mist, and is pressurized and sent to a secondary reactor to perform a secondary reaction;

[0017] d) the process gas discharged from the secondary reactor enters the secondary condenser for condensation, and the obtained sulfuric acid is recycled to step A);

[0018] e) The process gas discharged from the secondary condenser is sent to the activated carbon reactor under pressure after the acid mist is removed by the secondary electrostatic demister, and the residual sulfur dioxide is absorbed and converted into dilute sulfuric acid.

[0019] Preferably, the temperature of the spent acid cracking is 1000-1050°C;

[0020] The temperature of the primary reaction is 385-460° C.; the primary reaction is carried out under the condition of a primary reaction catalyst, and the primary reaction catalyst includes a vanadium catalyst and / or a platinum catalyst;

[0021] In step c), the condensation temperature is 275-300°C;

[0022] The inlet temperature of the first-stage electric demister is 85-105°C;

[0023] The temperature of the secondary reaction is 400-430°C;

[0024] The secondary reaction is carried out in the presence of a secondary reaction catalyst; the secondary reaction catalyst comprises a vanadium catalyst and / or a platinum catalyst;

[0025] In step d), the condensation temperature is 265-295°C.

[0026] The present invention also provides a system for preparing isooctyl nitrate, comprising:

[0027] Microchannel reactor;

[0028] a crude ester tank connected to the product outlet of the microchannel reactor;

[0029] an alkali washing device connected to the outlet of the crude ester tank;

[0030] A water washing device connected to the outlet of the alkali washing device; the water washing device is provided with an outlet for isooctyl nitrate;

[0031] a waste acid tank connected to the waste acid outlet of the microchannel reactor;

[0032] A waste acid regeneration device connected to the waste acid tank.

[0033] Preferably, a filter is further provided between the crude ester tank and the alkali washing device, specifically a basket filter, for filtering out impurities in the crude isooctyl nitrate.

[0034] Preferably, the alkali washing device comprises a primary alkali washing phase separation tank, and a secondary alkali washing phase separation tank connected to the product outlet of the primary alkali washing phase separation tank;

[0035] A primary alkali-washing fiber membrane contactor is arranged on the top of the primary alkali-washing phase separation tank; a secondary alkali-washing fiber membrane contactor is arranged on the top of the secondary alkali-washing phase separation tank;

[0036] The alkali washing device is also equipped with a primary alkali liquid circulation pump and a secondary alkali liquid circulation pump; the primary alkali liquid circulation pump is used to transport alkali washing liquid to the top of the primary alkali washing fiber membrane contactor; the secondary alkali liquid circulation pump is used to transport alkali washing liquid to the top of the secondary alkali washing fiber membrane contactor;

[0037] An outlet for isooctyl nitrate is arranged on the top of the primary alkali washing phase separation tank; an outlet for isooctyl nitrate is arranged on the top of the secondary alkali washing phase separation tank, which is the outlet of the alkali washing device.

[0038] Preferably, the water washing device comprises a water washing phase separation tank;

[0039] A water-wash fiber membrane contactor is arranged on the top of the water-wash phase separation tank;

[0040] The water washing device is also equipped with a water washing circulation pump; the water washing circulation pump is used to transport deionized water to the top of the water washing fiber membrane contactor;

[0041] An outlet for isooctyl nitrate is arranged at the top of the water-wash phase separation tank.

[0042] Preferably, it also includes:

[0043] A heat exchanger connected to the isooctyl nitrate outlet of the water washing device;

[0044] a coalescer connected to the isooctyl nitrate outlet of the heat exchanger;

[0045] The heat exchanger is used to cool down the isooctyl nitrate;

[0046] The coalescer is used to coalesce free water in isooctyl nitrate.

[0047] Preferably, the waste acid regeneration device further comprises:

[0048] Incinerators;

[0049] a high temperature filter connected to the process gas outlet of the incinerator;

[0050] a process fan connected to the process gas outlet of the high temperature filter;

[0051] a primary reactor connected to the process gas outlet of the process blower;

[0052] A primary condenser connected to the process gas outlet of the primary reactor; the collecting tank outlet of the primary condenser is connected to the sulfuric acid storage tank;

[0053] a primary electric demister connected to the process gas outlet of the primary condenser;

[0054] a process gas fan connected to the process gas outlet of the first-stage electrostatic precipitator;

[0055] a secondary reactor connected to the process gas outlet of the process gas blower;

[0056] A secondary condenser connected to the process gas outlet of the secondary reactor; the collecting tank outlet of the secondary condenser is connected to the sulfuric acid storage tank;

[0057] a secondary electric demister connected to the process gas outlet of the secondary condenser;

[0058] a clean air fan connected to the process air outlet of the secondary electrostatic precipitator;

[0059] An activated carbon reactor connected to the process gas outlet of the clean gas blower.

[0060] Preferably, the primary reactor is equipped with a first fin-tube heat exchanger;

[0061] The first-stage condenser is equipped with a glass tube heat exchanger;

[0062] The secondary reactor is provided with a second fin-tube heat exchanger.

[0063] The preparation method and system provided by the present invention have a small reaction amount, so that the reaction process in the reactor is easier to control, the reaction is safer, and the reaction is intrinsically safe; the microchannel reactor has no amplification effect from small-scale trials to industrial amplification; it can be used for synthesis reactions under various extreme conditions; the specific surface area is increased, and the heat released by the reaction is quickly transferred; the heat transfer process and the mass transfer process are strengthened. In addition, the conversion rate and product yield of isooctyl nitrate prepared by the present invention are both relatively good, and the performance of the prepared isooctyl nitrate is relatively good.

[0064] The present invention uses a microchannel reactor and microchannel reaction technology to achieve precise quantitative control of the reaction process, with low reaction safety risk, high product yield, high quality, and large operational flexibility to produce products of different specifications. In addition, the three wastes can be turned into treasures through the subsequent waste acid regeneration device. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 A system diagram for preparing isooctyl nitrate provided for one embodiment of the present invention. DETAILED DESCRIPTION

[0066] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] The present invention provides a method for preparing isooctyl nitrate, comprising the following steps:

[0068] A) feeding nitric acid, sulfuric acid and isooctyl alcohol into a microchannel reactor at a flow ratio of 1.05:2 to 2.5:1 to react and obtain a crude isooctyl nitrate;

[0069] B) regenerating the spent acid produced by the reaction;

[0070] The crude isooctyl nitrate is subjected to alkali elution to remove acid and water elution to remove salt, thereby obtaining isooctyl nitrate.

[0071] In step A):

[0072] Nitric acid, sulfuric acid and isooctyl alcohol are fed into a microchannel reactor at a flow ratio of 1.05:2 to 2.5:1 to react and obtain a crude isooctyl nitrate.

[0073] In the present invention, nitric acid and isooctyl alcohol react under the catalysis of sulfuric acid to generate isooctyl nitrate and water. The crude product is then washed with alkali and water to obtain the product isooctyl nitrate.

[0074] In certain embodiments of the present invention, the mass concentration of the sulfuric acid is 97%; the mass concentration of the nitric acid is 98%; and the mass concentration of the isooctyl alcohol is 99.5%.

[0075] In certain embodiments of the present invention, before sulfuric acid, nitric acid and isooctyl alcohol are introduced into the microchannel reactor, the process further includes: mixing sulfuric acid and nitric acid to obtain a mixed acid, and mixing the mixed acid with the isooctyl alcohol.

[0076] In certain embodiments of the present invention, the flow ratios of the nitric acid, sulfuric acid, and isooctyl alcohol are 1.05:2.25:1, 1.05:2:1, and 1.05:2.5:1.

[0077] In certain embodiments of the present invention, the feed rate of the microchannel reactor is 2.0-3.2 kg / min, such as 3.2 kg / min, 2 kg / min, 2.5 kg / min. The reaction temperature is 20-50° C., such as 50° C., 20° C., 35° C. The reaction pressure is 0.3-1.5 MPa, such as 1.5 MPa, 0.3 MPa, 0.8 MPa.

[0078] In step B):

[0079] regenerating the waste acid produced by the reaction;

[0080] The crude isooctyl nitrate is subjected to alkali elution to remove acid and water elution to remove salt, thereby obtaining isooctyl nitrate.

[0081] In certain embodiments of the present invention, the alkaline washing solution used in the alkaline washing and deacidification is an aqueous solution of sodium hydroxide with a mass concentration of 18% to 20%. The water washing and desalination uses desalted water. When the temperature is low in winter, the hot water heating system of the alkali solution storage tank is first turned on, and the temperature of the alkali solution storage tank is controlled at 25 to 35°C, such as 35°C, 25°C, and 30°C.

[0082] In certain embodiments of the present invention, before the crude isooctyl nitrate is subjected to alkaline elution to remove the acid, the process further comprises: filtering to remove impurities in the crude isooctyl nitrate.

[0083] In certain embodiments of the present invention, the alkaline elution acid comprises two-stage alkaline elution acid; specifically, a primary alkaline elution acid and a secondary alkaline elution acid.

[0084] In some embodiments of the present invention, after the water washing and desalting, the method further comprises: cooling. The cooling may be natural cooling to room temperature. In some embodiments of the present invention, after the cooling, the method further comprises: removing free water from isooctyl nitrate.

[0085] In certain embodiments of the present invention, the waste acid produced by the reaction is regenerated and then reused in step A).

[0086] In certain embodiments of the present invention, the waste acid produced by the reaction is subjected to waste acid regeneration, comprising the following steps:

[0087] a) sending the waste acid produced by the reaction into an incinerator to carry out waste acid cracking;

[0088] b) pressurizing the process gas obtained in step a) and feeding it into a primary reactor to carry out a primary reaction;

[0089] c) condensing the process gas obtained in step b) through a primary condenser, and recycling the obtained sulfuric acid to step A);

[0090] The process gas discharged from the primary condenser is passed through a primary electric demister to remove acid mist, and is pressurized and sent to a secondary reactor to perform a secondary reaction;

[0091] d) the process gas discharged from the secondary reactor enters the secondary condenser for condensation, and the obtained sulfuric acid is recycled to step A);

[0092] e) The process gas discharged from the secondary condenser is sent to the activated carbon reactor under pressure after the acid mist is removed by the secondary electrostatic demister, and the residual sulfur dioxide is absorbed and converted into dilute sulfuric acid.

[0093] In step a):

[0094] The waste acid produced by the reaction is sent to an incinerator for waste acid cracking.

[0095] The temperature of the waste acid cracking is 1000-1050° C., such as 1050° C., 1000° C., 1030° C. The waste acid cracking is carried out under the conditions of fuel gas and acid gas.

[0096] After the waste acid is cracked, the method further comprises: filtering.

[0097] In step b):

[0098] The process gas obtained in step a) is pressurized and sent to a primary reactor for primary reaction.

[0099] The temperature of the primary reaction is 385-460°C, such as 460°C, 385°C, 420°C.

[0100] The primary reaction is carried out under the condition of a primary reaction catalyst. The primary reaction catalyst includes a vanadium catalyst and / or a platinum catalyst.

[0101] In step c):

[0102] The process gas obtained in step b) is condensed through a primary condenser, and the obtained sulfuric acid is recycled to step A);

[0103] The process gas discharged from the primary condenser passes through a primary electric demister to remove acid mist, and is pressurized and sent to a secondary reactor to perform a secondary reaction.

[0104] The condensation temperature is 275-300°C, such as 300°C, 275°C, 290°C.

[0105] The inlet temperature of the first-stage electric demister is 85-105°C, such as 105°C, 85°C, and 95°C.

[0106] The temperature of the secondary reaction is 400-430°C, such as 430°C, 400°C, 415°C.

[0107] The secondary reaction is carried out in the presence of a secondary reaction catalyst, which includes a vanadium catalyst and / or a platinum catalyst.

[0108] In step d):

[0109] The process gas discharged from the secondary reactor enters the secondary condenser for condensation, and the obtained sulfuric acid is recycled for step A).

[0110] The condensation temperature is 265-295°C, such as 295°C, 265°C, 280°C.

[0111] In step e):

[0112] The process gas discharged from the secondary condenser is sent to the activated carbon reactor under pressure after the acid mist is removed by the secondary electrostatic demister, and the residual sulfur dioxide is absorbed and converted into dilute sulfuric acid.

[0113] The present invention provides a system for preparing isooctyl nitrate, comprising:

[0114] Microchannel reactor;

[0115] a crude ester tank connected to the product outlet of the microchannel reactor;

[0116] an alkali washing device connected to the outlet of the crude ester tank;

[0117] A water washing device connected to the outlet of the alkali washing device; the water washing device is provided with an outlet for isooctyl nitrate;

[0118] a waste acid tank connected to the waste acid outlet of the microchannel reactor;

[0119] A waste acid regeneration device connected to the waste acid tank.

[0120] Figure 1 A system diagram for preparing isooctyl nitrate provided for one embodiment of the present invention.

[0121] In certain embodiments of the present invention, the preparation system further includes: an acid preparation tank, and an acid intermediate tank connected to the outlet of the acid preparation tank. The acid preparation tank is provided with a nitric acid inlet and a sulfuric acid inlet. Specifically, the nitric acid inlet of the acid preparation tank is connected to a nitric acid storage tank; the sulfuric acid inlet of the acid preparation tank is connected to a sulfuric acid storage tank. The acid preparation tank is used to mix nitric acid and sulfuric acid to obtain a mixed acid. The acid intermediate tank is also provided with an isooctyl alcohol inlet. The isooctyl alcohol inlet of the acid intermediate tank is connected to the isooctyl alcohol storage tank. The acid intermediate tank is used to mix the mixed acid with isooctyl alcohol.

[0122] The sulfuric acid storage tank, the nitric acid storage tank and the isooctyl alcohol storage tank are all provided with independent material pumps for controlling the flow individually.

[0123] The inlet of the microchannel reactor is connected to the outlet of the acid intermediate tank. The microchannel reactor is used for the reaction of nitric acid and isooctyl alcohol under the catalysis of sulfuric acid.

[0124] The present invention also includes a crude ester tank connected to the product outlet of the microchannel reactor. The crude ester tank is used to store crude isooctyl nitrate.

[0125] The present invention also comprises an alkali washing device connected to the outlet of the crude ester tank.

[0126] In certain embodiments of the present invention, a filter, specifically a basket filter, is further provided between the crude ester tank and the alkali washing device to filter out impurities in the crude isooctyl nitrate.

[0127] In certain embodiments of the present invention, a delivery pump is provided between the crude ester tank and the filter for delivering the crude isooctyl nitrate.

[0128] In certain embodiments of the present invention, the alkali washing device comprises a primary alkali washing phase separation tank and a secondary alkali washing phase separation tank connected to the product outlet of the primary alkali washing phase separation tank. The primary alkali washing phase separation tank and the secondary alkali washing phase separation tank are both conventional alkali washing phase separation tanks.

[0129] In certain embodiments of the present invention, a primary alkali-washing fiber membrane contactor is arranged on the top of the primary alkali-washing phase separation tank; and a secondary alkali-washing fiber membrane contactor is arranged on the top of the secondary alkali-washing phase separation tank.

[0130] The alkali washing device is also equipped with a primary alkali solution circulation pump and a secondary alkali solution circulation pump; the primary alkali solution circulation pump is used to transport alkali washing liquid to the top of the primary alkali washing fiber membrane contactor; the secondary alkali solution circulation pump is used to transport alkali washing liquid to the top of the secondary alkali washing fiber membrane contactor.

[0131] An isooctyl nitrate outlet is arranged on the top of the primary alkali washing phase separation tank. An isooctyl nitrate outlet (i.e., the outlet of the alkali washing device) is arranged on the top of the secondary alkali washing phase separation tank.

[0132] Specifically, during the primary alkaline washing and deacidification, the crude isooctyl nitrate is transported by a delivery pump, and after being filtered out of impurities by a basket filter, it enters the top of the primary alkaline washing fiber membrane contactor installed on the top of the primary alkaline washing phase separation tank, and contacts the alkaline washing liquid transported by the primary alkaline liquid circulation pump at the top of the primary alkaline washing fiber membrane contactor. The alkaline washing liquid has begun to circulate before the alkaline washing and deacidification, firstly wetting the metal fibers in the primary alkaline washing fiber membrane contactor and flowing downward along the fiber filaments, and the crude isooctyl nitrate flows along the fiber bundle in the same direction as the alkaline washing liquid, so that a flowing film is formed on the fiber bundle between the crude isooctyl nitrate and the alkaline washing liquid, thereby increasing the mass transfer area and improving the mass transfer rate, the acid is extracted into the alkaline washing liquid, the alkaline washing liquid containing salt is detached from the fiber, and settles at the bottom of the primary alkaline washing phase separation tank, and is recycled.

[0133] The isooctyl nitrate after the primary alkali washing and deacidification comes out from the top of the primary alkali washing phase separation tank, enters the top of the secondary alkali washing fiber membrane contactor installed on the secondary alkali washing phase separation tank, and contacts with the alkali washing liquid delivered by the secondary alkali liquid circulation pump at the top of the secondary alkali washing fiber membrane contactor. The alkali washing liquid has begun to circulate before the above step A). ​​The isooctyl nitrate after the primary alkali washing and deacidification and the alkali washing liquid delivered by the secondary alkali liquid circulation pump contact each other on the fiber bundle to remove the acid droplets contained in the isooctyl nitrate; the isooctyl nitrate and the alkali washing liquid are separated by sedimentation in the secondary alkali liquid phase separation tank, and the separated alkali washing liquid is continuously recycled.

[0134] The present invention also comprises a water washing device connected with the outlet of the alkali washing device; the water washing device is provided with an outlet of isooctyl nitrate.

[0135] In certain embodiments of the present invention, the water washing device comprises a water washing phase separation tank. The water washing phase separation tank is a water washing phase separation tank well known to those skilled in the art.

[0136] In certain embodiments of the present invention, a water-wash fiber membrane contactor is disposed on the top of the water-wash phase separation tank.

[0137] The water washing device is also equipped with a water washing circulation pump; the water washing circulation pump is used to transport deionized water to the top of the water washing fiber membrane contactor.

[0138] An outlet for isooctyl nitrate is arranged at the top of the water-wash phase separation tank.

[0139] Specifically, during water washing and desalination, the isooctyl nitrate coming out of the top of the secondary alkali liquid phase separation tank enters the top of the water washing fiber membrane contactor installed on the top of the water washing phase separation tank, and contacts with the desalted water delivered by the water washing circulation pump at the top of the water washing fiber membrane contactor. The desalted water has already started to circulate before water washing and desalination. The isooctyl nitrate and the desalted water after water washing and desalination are separated by sedimentation in the water washing phase separation tank, and the isooctyl nitrate comes out from the top of the tank.

[0140] In certain embodiments of the present invention, the preparation system further comprises a heat exchanger connected to the outlet of the isooctyl nitrate of the water washing device, and the heat exchanger is used to cool the isooctyl nitrate.

[0141] In certain embodiments of the present invention, the preparation system further comprises a coalescer connected to the isooctyl nitrate outlet of the heat exchanger, which is used to coalesce free water in the isooctyl nitrate. Qualified isooctyl nitrate can be pumped to the finished product intermediate tank for testing and analysis, and then sent to the finished product tank outside the boundary area.

[0142] The preparation system provided by the present invention also includes a waste acid tank connected to the waste acid outlet of the microchannel reactor. During the reaction process of the microchannel reactor of the present invention, sulfuric acid and nitric acid are excessive, and the waste acid generated during the reaction process enters the waste acid tank.

[0143] The preparation system provided by the present invention also includes a waste acid regeneration device connected to the waste acid tank.

[0144] In certain embodiments of the present invention, the spent acid regeneration device comprises:

[0145] Incinerators;

[0146] a high temperature filter connected to the process gas outlet of the incinerator;

[0147] a process fan connected to the process gas outlet of the high temperature filter;

[0148] a primary reactor connected to the process gas outlet of the process blower;

[0149] A primary condenser connected to the process gas outlet of the primary reactor; the collecting tank outlet of the primary condenser is connected to the sulfuric acid storage tank;

[0150] a primary electric demister connected to the process gas outlet of the primary condenser;

[0151] a process gas fan connected to the process gas outlet of the first-stage electrostatic precipitator;

[0152] a secondary reactor connected to the process gas outlet of the process gas blower;

[0153] A secondary condenser connected to the process gas outlet of the secondary reactor; the collecting tank outlet of the secondary condenser is connected to the sulfuric acid storage tank;

[0154] a secondary electric demister connected to the process gas outlet of the secondary condenser;

[0155] a clean air fan connected to the process air outlet of the secondary electrostatic precipitator;

[0156] An activated carbon reactor connected to the process gas outlet of the clean gas blower.

[0157] The incinerator is also used for waste acid cracking. The sulfuric acid nozzle inlet of the incinerator is connected to the waste acid outlet of the waste acid tank. The incinerator is also provided with a fuel gas inlet.

[0158] In certain embodiments of the present invention, the fuel gas inlet of the incinerator is connected to the outlet of the air heater; and the inlet of the air heater is connected to the outlet of the combustion-supporting fan.

[0159] A two-stage molten salt heat exchanger is arranged in the incinerator.

[0160] In the incinerator, sulfuric acid in the waste acid is decomposed into SO2, and other impurities in the waste acid are burned at the same time. The combustion-supporting fan extracts high-temperature air from the secondary condenser and sends it to the incinerator after passing through the air heater. Fuel gas (dry gas or methane) and acid gas are directly added to the incinerator as fuel for waste acid cracking. The process gas (temperature is 1000-1050℃) generated by the incinerator is cooled by the two-stage molten salt heat exchanger in the incinerator, and then enters the high-temperature filter for filtration. The dust carried in the process gas is separated; the process gas is pressurized and sent to the primary reactor through the process fan.

[0161] In certain embodiments of the present invention, the primary reactor is equipped with a primary reaction catalyst. X The first reactor is equipped with a first finned tube heat exchanger to remove the reaction heat and control the optimal reaction temperature. Molten salt is passed through the tube of the first finned tube heat exchanger, and the appropriate reaction temperature is obtained by controlling the flow rate of the molten salt.

[0162] In certain embodiments of the present invention, the primary condenser is equipped with a glass tube heat exchanger, and after heat exchange with the air sent in by the primary air blower, the sulfuric acid in the process gas is condensed, accumulated in the collection tank at the bottom of the primary condenser, and then flows to the sulfuric acid storage tank mentioned above. The outlet of the collection tank of the primary condenser is connected to the sulfuric acid storage tank.

[0163] The process gas discharged from the primary condenser is sent to the secondary reactor by the process gas blower after the acid mist is removed by the primary electrostatic precipitator. The secondary reactor is equipped with a secondary reaction catalyst. X It continues to react with ammonia to generate nitrogen, and further oxidizes the remaining sulfur dioxide in the process gas to sulfur trioxide. The secondary reactor is equipped with a second finned tube heat exchanger to preheat the process gas and remove the reaction heat to control the reaction temperature. Molten salt is passed through the tube of the second finned tube heat exchanger, and the appropriate reaction temperature is obtained by controlling the flow of molten salt.

[0164] In certain embodiments of the present invention, the process gas discharged from the secondary reactor enters the secondary condenser for condensation. The secondary condenser is equipped with a glass tube heat exchanger. After heat exchange with the air sent in by the secondary air blower, the sulfuric acid in the process gas is condensed and accumulated in the collection tank at the bottom of the secondary condenser, and then flows to the sulfuric acid storage tank mentioned above. The outlet of the collection tank of the secondary condenser is connected to the sulfuric acid storage tank.

[0165] The process gas discharged from the secondary condenser passes through the secondary electrostatic demister to remove the acid mist, and then is pressurized by the clean gas blower and sent to the activated carbon reactor. The activated carbon reactor is filled with activated carbon, and the residual sulfur dioxide is absorbed and converted into dilute sulfuric acid.

[0166] The activated carbon reactor is provided with a tail gas outlet.

[0167] The sulfuric acid outlet in the activated carbon reactor is connected to the primary condenser, the secondary condenser and the incinerator respectively through a sulfuric acid pump.

[0168] The dilute sulfuric acid is pumped to the primary condenser and the secondary condenser for concentration, and can also be returned to the incinerator for re-decomposition. The clean tail gas is discharged into the atmosphere through the chimney. The sulfuric acid in the collecting tanks of the primary condenser and the secondary condenser flows by gravity to the sulfuric acid storage tank described above. After circulating cooling, the sulfuric acid in the sulfuric acid storage tank can be returned to the collecting tanks of the primary condenser and the secondary condenser, and the collecting tank can be cooled, or it can be directly sent to the sulfuric acid storage tank. Specifically, the sulfuric acid storage tank is also provided with a circulating sulfuric acid outlet, and the circulating sulfuric acid outlet of the sulfuric acid storage tank is respectively connected to the collecting tank of the primary condenser and the collecting tank of the secondary condenser.

[0169] The heat brought out by the molten salt after heat exchange in each heat exchanger eventually causes the steam generator to produce 3.8-4.2MPa (for example, 4.0MPa) steam, and the reaction pressure is 4.2-4.5MPa (for example, 4.5MPa, 4.2MPa, 4.3MPa). The steam is superheated to 450°C by a three-stage steam superheater (three steam superheaters are connected in series in sequence) and then sent to the medium-pressure steam network. The cooled molten salt returns to the molten salt tank, the temperature of which is 260-280°C (for example, 280°C, 260°C, 270°C), and is then pumped to each heat exchanger for recycling. Specifically, the molten salt outlet of the primary reactor is connected to the steam generator, and the molten salt outlet of the secondary reactor is connected to the steam generator. The steam outlet of the steam generator is connected to the three-stage steam superheater. The molten salt outlet of the steam generator is connected to the reused molten salt inlet of the primary reactor and the reused molten salt inlet of the secondary reactor, respectively.

[0170] In certain embodiments of the present invention, the composition of the molten salt (thermal salt) includes: 53wt% potassium nitrate, 40wt% sodium nitrite and 7wt% sodium nitrate. The thermal salt system is used to control the temperature in the reactor to be within a suitable temperature range to achieve a high conversion rate of SO2 to SO3. The thermal salt pipeline system is a jacketed pipe, which is heated by low-pressure steam (1.0MPa) to melt the thermal salt before starting operation. The jacket needs to be turned on for heating before stopping the operation and desalting.

[0171] In the present invention, the waste acid enters the waste acid regeneration device, and is regenerated and reused through the steps of high-temperature cracking in the incinerator, high-temperature dust removal, double denitration conversion condensation, activated carbon conversion and the like.

[0172] The microstructure inside the microchannel reactor of the present invention enables the microreactor device to have a large specific surface area, which can reach hundreds or even thousands of times the specific surface area of ​​the stirred tank. The microreactor has excellent heat and mass transfer capabilities, and can achieve instantaneous uniform mixing of materials and efficient heat transfer. Therefore, many reactions that cannot be achieved in conventional reactors can be achieved in microreactors.

[0173] In certain embodiments of the present invention, the performance parameters of the microchannel reactor are shown in Table 1.

[0174] Table 1 Performance parameters of microchannel reactor

[0175] Specification G4 size 1000×1200×1000 mm weight 350 kg Heat transfer medium flux 0~6m3 / hour Material temperature range -10～200℃ Material pressure range 0~1.8MPa Heat exchange medium pressure range 0-2.7MPa Bracket material 316L Reaction module material Silicon Carbide

[0176] In the present invention, the characteristics of the microchannel reactor are as follows:

[0177] 1. The reaction volume is small, making the reaction process in the reactor easier to control, the reaction safer, and achieving intrinsic safety of the reaction;

[0178] 2. There is no scale-up effect from small-scale trials to industrial scale-up of microchannel reactors;

[0179] 3. It can be used for synthesis reactions under various extreme conditions, such as: rapid, highly exothermic reactions; reactions involving highly corrosive reagents;

[0180] 4. The heat transfer process is enhanced. The internal volume of the reactor is reduced, so that the temperature distribution can be uniformed in a very short time;

[0181] 5. Increased specific surface area; the heat exchange area per unit volume is increased by 1000 times, quickly transferring the heat released by the reaction;

[0182] 6. The mass transfer process is enhanced. In the microchannel, the fluid flow is in the form of laminar flow, and the mass transfer process is mainly intermolecular diffusion. The mass transfer efficiency is 100 times higher than that of the autoclave type, which improves the conversion rate and reduces side reactions;

[0183] 7. The microstructure of the microreactor is not suitable for solid materials and easily crystallized materials.

[0184] In order to further illustrate the present invention, a method and system for preparing isooctyl nitrate provided by the present invention are described in detail below in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0185] Example 1

[0186] Using the present invention Figure 1 Preparation system;

[0187] 1) Synthesis of crude isooctyl nitrate:

[0188] Sulfuric acid with a mass concentration of 97%, nitric acid with a mass concentration of 98% and isooctyl alcohol with a mass concentration of 99.5% are fed into the system from the outside. After the sulfuric acid in the sulfuric acid storage tank and the nitric acid in the nitric acid storage tank are prepared in the acid preparation tank, the obtained mixed acid is sent to the acid intermediate tank, and the isooctyl alcohol and the mixed acid are mixed in the acid intermediate tank, and the feed flow ratio is controlled by the respective material pumps and sent to the microchannel reactor. During the reaction, sulfuric acid and nitric acid are excessive, and the waste acid generated during the reaction enters the waste acid tank, and the crude isooctyl nitrate obtained by the reaction enters the crude ester tank. Among them, the flow ratio of nitric acid, sulfuric acid and isooctyl alcohol is 1.05:2.25:1, the feed amount is: 3.2kg / min, the reaction temperature is 50°C, and the reaction pressure is 1.5MPa.

[0189] 2) Filter the crude isooctyl nitrate in the crude ester tank and perform primary alkali elution to remove acid, secondary alkali elution to remove acid and water elution to remove salt:

[0190] The crude isooctyl nitrate in the crude ester tank is transported by a delivery pump, and after being filtered out of impurities by a basket filter, it enters the top of the primary alkali-washing fiber membrane contactor installed on the top of the primary alkali-washing phase separation tank, and contacts the alkali washing liquid (the alkali washing liquid is a sodium hydroxide aqueous solution with a mass concentration of 20%; when the temperature is low in winter, the hot water heating system of the alkali liquid storage tank is turned on first, and the temperature of the alkali liquid storage tank is controlled to be 35°C) delivered by the primary alkali liquid circulation pump at the top of the primary alkali-washing fiber membrane contactor. The alkali washing liquid has begun to circulate before alkali washing and deacidification, firstly wetting the metal fibers in the primary alkali-washing fiber membrane contactor and flowing downward along the fiber filaments, and the crude isooctyl nitrate flows along the fiber bundle in the same direction as the alkali washing liquid, so that a flowing film is formed on the fiber bundle between the crude isooctyl nitrate and the alkali washing liquid, thereby increasing the mass transfer area and improving the mass transfer rate, the acid is extracted into the alkali washing liquid, the alkali washing liquid containing salt is separated from the fiber, and settles at the bottom of the primary alkali-washing phase separation tank, and is recycled;

[0191] The isooctyl nitrate after the primary alkaline washing and deacidification comes out from the top of the primary alkaline washing phase separation tank, enters the top of the secondary alkaline washing fiber membrane contactor installed on the secondary alkaline washing phase separation tank, and contacts with the alkaline washing liquid delivered by the secondary alkaline liquid circulation pump at the top of the secondary alkaline washing fiber membrane contactor. The alkaline washing liquid has begun to circulate before the above step A). ​​The isooctyl nitrate after the primary alkaline washing and deacidification and the alkaline washing liquid delivered by the secondary alkaline liquid circulation pump contact each other on the fiber bundle to remove the acid droplets contained in the isooctyl nitrate; the isooctyl nitrate and the alkaline washing liquid are separated by sedimentation in the secondary alkaline liquid phase separation tank, and the alkaline washing liquid after separation is continuously recycled;

[0192] The isooctyl nitrate coming out of the top of the secondary alkali phase separation tank enters the top of the water-wash fiber membrane contactor installed on the top of the water-wash phase separation tank, and contacts with the deionized water delivered by the water-wash circulation pump at the top of the water-wash fiber membrane contactor. The deionized water has begun to circulate before the water-wash desalination. The isooctyl nitrate and the deionized water after the water-wash desalination are separated by sedimentation in the water-wash phase separation tank, and the isooctyl nitrate comes out from the top of the tank.

[0193] After cooling in the heat exchanger, it enters the coalescer to coalesce the free water in isooctyl nitrate. Qualified isooctyl nitrate can be pumped to the finished product intermediate tank for testing and analysis, and then sent to the finished product tank outside the boundary area.

[0194] 3) Regenerating the waste acid produced by synthesizing isooctyl nitrate;

[0195] The waste acid produced by the synthesis of isooctyl nitrate is fed into the incinerator through the sulfuric acid nozzle inlet of the incinerator. In the incinerator, sulfuric acid is decomposed into SO2, and other impurities in the waste acid are burned at the same time. The combustion-supporting fan extracts high-temperature air from the secondary condenser and feeds it into the incinerator after passing through the air heater. The fuel gas and acid gas are directly added to the incinerator as fuel for waste acid cracking. The process gas (temperature is 1050°C) generated by the incinerator is cooled by the two-stage molten salt heat exchanger in the incinerator, and then enters the high-temperature filter for filtration. The dust carried in the process gas is separated; the process gas is pressurized and fed into the primary reactor through the process fan for primary reaction. The temperature of the primary reaction is 460°C. The catalyst for the primary reaction is a platinum catalyst.

[0196] The primary reactor is equipped with a primary reaction catalyst. X The first reactor is equipped with a first finned tube heat exchanger to remove the reaction heat and control the optimal reaction temperature. Molten salt is passed through the tube of the first finned tube heat exchanger, and the appropriate reaction temperature is obtained by controlling the flow rate of the molten salt.

[0197] The process gas enters the primary condenser for condensation; the condensation temperature is 300°C. The primary condenser is equipped with a glass tube heat exchanger. After heat exchange with the air sent in by the air blower, the sulfuric acid in the process gas is condensed and accumulated in the collection tank at the bottom of the primary condenser, and then flows to the sulfuric acid storage tank mentioned above. The outlet of the collection tank of the primary condenser is connected to the sulfuric acid storage tank.

[0198] The process gas discharged from the primary condenser is passed through a primary electrostatic precipitator to remove the acid mist (the inlet temperature of the primary electrostatic precipitator is 105°C), and then is pressurized by a process gas blower and sent to a secondary reactor for a secondary reaction. The temperature of the secondary reaction is 430°C. A secondary reaction catalyst (the secondary reaction catalyst is a platinum catalyst) is installed in the secondary reactor. The unreacted NO in the primary reactor is X It continues to react with ammonia to generate nitrogen, and further oxidizes the remaining sulfur dioxide in the process gas to sulfur trioxide. The secondary reactor is equipped with a second finned tube heat exchanger to preheat the process gas and remove the reaction heat to control the reaction temperature. Molten salt is passed through the tube of the second finned tube heat exchanger, and the appropriate reaction temperature is obtained by controlling the flow of molten salt.

[0199] The process gas discharged from the secondary reactor enters the secondary condenser for condensation; the condensation temperature is 295°C. The secondary condenser is equipped with a glass tube heat exchanger. After heat exchange with the air sent in by the secondary air blower, the sulfuric acid in the process gas is condensed and accumulated in the collection tank at the bottom of the secondary condenser, and then flows to the sulfuric acid storage tank mentioned above. The outlet of the collection tank of the secondary condenser is connected to the sulfuric acid storage tank.

[0200] The process gas discharged from the secondary condenser is sent to the activated carbon reactor by the clean gas blower after the acid mist is removed by the secondary electrostatic demister. The activated carbon reactor is filled with activated carbon, and the residual sulfur dioxide is absorbed and converted into dilute sulfuric acid. The dilute sulfuric acid is sent to the primary condenser and the secondary condenser for concentration through the sulfuric acid pump, and can also be returned to the incinerator for re-decomposition. The clean tail gas is discharged into the atmosphere through the chimney. The sulfuric acid in the collection tanks of the primary condenser and the secondary condenser flows by gravity to the sulfuric acid storage tank mentioned above.

[0201] The heat brought out by the molten salt after heat exchange in each heat exchanger eventually makes the steam generator produce 4.0MPa steam, and the reaction pressure is 4.5MPa. The reaction liquid level steam is superheated to 450℃ by the three-stage steam superheater and then sent to the medium-pressure steam network. The cooled molten salt returns to the molten salt tank, and the temperature of the molten salt tank is 280℃. It is then pumped to each heat exchanger for recycling.

[0202] Example 2

[0203] Using the present invention Figure 1 Preparation system;

[0204] 1) Synthesis of crude isooctyl nitrate:

[0205] Sulfuric acid with a mass concentration of 97%, nitric acid with a mass concentration of 98% and isooctyl alcohol with a mass concentration of 99.5% are fed into the system from the outside. After the sulfuric acid in the sulfuric acid storage tank and the nitric acid in the nitric acid storage tank are prepared in the acid preparation tank, the obtained mixed acid is sent to the acid intermediate tank, and the isooctyl alcohol and the mixed acid are mixed in the acid intermediate tank, and the feed flow ratio is controlled by the respective material pumps and sent to the microchannel reactor. During the reaction, sulfuric acid and nitric acid are excessive, and the waste acid generated during the reaction enters the waste acid tank, and the crude isooctyl nitrate obtained by the reaction enters the crude ester tank. Among them, the flow ratio of nitric acid, sulfuric acid and isooctyl alcohol is 1.05:2:1, the feed amount is: 2kg / min, the reaction temperature is 20°C, and the reaction pressure is 0.3MPa.

[0206] 2) Filter the crude isooctyl nitrate in the crude ester tank and perform primary alkali elution to remove acid, secondary alkali elution to remove acid and water elution to remove salt:

[0207] The crude isooctyl nitrate in the crude ester tank is transported by a delivery pump, and after being filtered out of impurities by a basket filter, it enters the top of the primary alkali-washing fiber membrane contactor installed on the top of the primary alkali-washing phase separation tank, and contacts the alkali washing liquid (the alkali washing liquid is a sodium hydroxide aqueous solution with a mass concentration of 18%; when the temperature is low in winter, the hot water heating system of the alkali liquid storage tank is turned on first, and the temperature of the alkali liquid storage tank is controlled to be 25°C) delivered by the primary alkali liquid circulation pump at the top of the primary alkali-washing fiber membrane contactor. The alkali washing liquid has begun to circulate before alkali washing and deacidification, firstly wetting the metal fibers in the primary alkali-washing fiber membrane contactor and flowing downward along the fiber filaments, and the crude isooctyl nitrate flows along the fiber bundle in the same direction as the alkali washing liquid, so that a flowing film is formed on the fiber bundle between the crude isooctyl nitrate and the alkali washing liquid, thereby increasing the mass transfer area and improving the mass transfer rate, the acid is extracted into the alkali washing liquid, the alkali washing liquid containing salt is separated from the fiber, and settles at the bottom of the primary alkali-washing phase separation tank, and is recycled;

[0208] The isooctyl nitrate after the primary alkaline washing and deacidification comes out from the top of the primary alkaline washing phase separation tank, enters the top of the secondary alkaline washing fiber membrane contactor installed on the secondary alkaline washing phase separation tank, and contacts with the alkaline washing liquid delivered by the secondary alkaline liquid circulation pump at the top of the secondary alkaline washing fiber membrane contactor. The alkaline washing liquid has begun to circulate before the above step A). ​​The isooctyl nitrate after the primary alkaline washing and deacidification and the alkaline washing liquid delivered by the secondary alkaline liquid circulation pump contact each other on the fiber bundle to remove the acid droplets contained in the isooctyl nitrate; the isooctyl nitrate and the alkaline washing liquid are separated by sedimentation in the secondary alkaline liquid phase separation tank, and the alkaline washing liquid after separation is continuously recycled;

[0209] The isooctyl nitrate coming out of the top of the secondary alkali phase separation tank enters the top of the water-wash fiber membrane contactor installed on the top of the water-wash phase separation tank, and contacts with the deionized water delivered by the water-wash circulation pump at the top of the water-wash fiber membrane contactor. The deionized water has begun to circulate before the water-wash desalination. The isooctyl nitrate and the deionized water after the water-wash desalination are separated by sedimentation in the water-wash phase separation tank, and the isooctyl nitrate comes out from the top of the tank.

[0210] After cooling in the heat exchanger, it enters the coalescer to coalesce the free water in isooctyl nitrate. Qualified isooctyl nitrate can be pumped to the finished product intermediate tank for testing and analysis, and then sent to the finished product tank outside the boundary area.

[0211] 3) Regenerating the waste acid produced by synthesizing isooctyl nitrate;

[0212] The waste acid produced by the synthesis of isooctyl nitrate is fed into the incinerator through the sulfuric acid nozzle inlet of the incinerator. In the incinerator, sulfuric acid is decomposed into SO2, and other impurities in the waste acid are burned at the same time. The combustion-supporting fan extracts high-temperature air from the secondary condenser and feeds it into the incinerator after passing through the air heater. Fuel gas and acid gas are directly added to the incinerator as fuel for waste acid cracking. The process gas (temperature is 1000°C) generated by the incinerator is cooled by the two-stage molten salt heat exchanger in the incinerator, and then enters the high-temperature filter for filtration. The dust carried in the process gas is separated; the process gas is pressurized and fed into the primary reactor through the process fan for primary reaction. The temperature of the primary reaction is 385°C. The catalyst for the primary reaction is a platinum catalyst.

[0213] The primary reactor is equipped with a primary reaction catalyst. X The first reactor is equipped with a first finned tube heat exchanger to remove the reaction heat and control the optimal reaction temperature. Molten salt is passed through the tube of the first finned tube heat exchanger, and the appropriate reaction temperature is obtained by controlling the flow rate of the molten salt.

[0214] The process gas enters the primary condenser for condensation; the condensation temperature is 275°C. The primary condenser is equipped with a glass tube heat exchanger. After heat exchange with the air sent in by the air blower, the sulfuric acid in the process gas is condensed and accumulated in the collection tank at the bottom of the primary condenser, and then flows to the sulfuric acid storage tank mentioned above. The outlet of the collection tank of the primary condenser is connected to the sulfuric acid storage tank.

[0215] The process gas discharged from the primary condenser is passed through a primary electrostatic precipitator to remove the acid mist (the inlet temperature of the primary electrostatic precipitator is 85°C), and then is pressurized by a process gas blower and sent to a secondary reactor for a secondary reaction. The temperature of the secondary reaction is 400°C. A secondary reaction catalyst (the secondary reaction catalyst is a platinum catalyst) is installed in the secondary reactor. The unreacted NO in the primary reactor is X It continues to react with ammonia to generate nitrogen, and further oxidizes the remaining sulfur dioxide in the process gas to sulfur trioxide. The secondary reactor is equipped with a second finned tube heat exchanger to preheat the process gas and remove the reaction heat to control the reaction temperature. Molten salt is passed through the tube of the second finned tube heat exchanger, and the appropriate reaction temperature is obtained by controlling the flow of molten salt.

[0216] The process gas discharged from the secondary reactor enters the secondary condenser for condensation; the condensation temperature is 265°C. The secondary condenser is equipped with a glass tube heat exchanger. After heat exchange with the air sent in by the secondary air blower, the sulfuric acid in the process gas is condensed and accumulated in the collection tank at the bottom of the secondary condenser, and then flows to the sulfuric acid storage tank mentioned above. The outlet of the collection tank of the secondary condenser is connected to the sulfuric acid storage tank.

[0217] The process gas discharged from the secondary condenser is sent to the activated carbon reactor by the clean gas blower after the acid mist is removed by the secondary electrostatic demister. The activated carbon reactor is filled with activated carbon, and the residual sulfur dioxide is absorbed and converted into dilute sulfuric acid. The dilute sulfuric acid is sent to the primary condenser and the secondary condenser for concentration through the sulfuric acid pump, and can also be returned to the incinerator for re-decomposition. The clean tail gas is discharged into the atmosphere through the chimney. The sulfuric acid in the collection tanks of the primary condenser and the secondary condenser flows by gravity to the sulfuric acid storage tank mentioned above.

[0218] The heat brought out by the molten salt after heat exchange in each heat exchanger eventually makes the steam generator produce 4.0MPa steam, and the reaction pressure is 4.2MPa. The reaction liquid level steam is superheated to 450℃ by the three-stage steam superheater and then sent to the medium-pressure steam network. The cooled molten salt returns to the molten salt tank, and the temperature of the molten salt tank is 260℃. It is then pumped to each heat exchanger for recycling.

[0219] Example 3

[0220] Using the present invention Figure 1 Preparation system;

[0221] 1) Synthesis of crude isooctyl nitrate:

[0222] Sulfuric acid with a mass concentration of 97%, nitric acid with a mass concentration of 98% and isooctyl alcohol with a mass concentration of 99.5% are fed into the system from the outside. After the sulfuric acid in the sulfuric acid storage tank and the nitric acid in the nitric acid storage tank are prepared in the acid preparation tank, the obtained mixed acid is sent to the acid intermediate tank, and the isooctyl alcohol and the mixed acid are mixed in the acid intermediate tank, and the feed flow ratio is controlled by the respective material pumps and sent to the microchannel reactor. During the reaction, sulfuric acid and nitric acid are excessive, and the waste acid generated during the reaction enters the waste acid tank, and the crude isooctyl nitrate obtained by the reaction enters the crude ester tank. Among them, the flow ratio of nitric acid, sulfuric acid and isooctyl alcohol is 1.05:2.5:1, the feed amount is: 2.5kg / min, the reaction temperature is 35°C, and the reaction pressure is 0.8MPa.

[0223] 2) Filter the crude isooctyl nitrate in the crude ester tank and perform primary alkali elution to remove acid, secondary alkali elution to remove acid and water elution to remove salt:

[0224] The crude isooctyl nitrate in the crude ester tank is transported by a delivery pump, and after being filtered out of impurities by a basket filter, it enters the top of the primary alkali-washing fiber membrane contactor installed on the top of the primary alkali-washing phase separation tank, and contacts the alkali washing liquid (the alkali washing liquid is a sodium hydroxide aqueous solution with a mass concentration of 20%; when the temperature is low in winter, the hot water heating system of the alkali liquid storage tank is turned on first, and the temperature of the alkali liquid storage tank is controlled to be 30°C) delivered by the primary alkali liquid circulation pump at the top of the primary alkali-washing fiber membrane contactor. The alkali washing liquid has begun to circulate before alkali washing and deacidification, firstly wetting the metal fibers in the primary alkali-washing fiber membrane contactor and flowing downward along the fiber filaments, and the crude isooctyl nitrate flows along the fiber bundle in the same direction as the alkali washing liquid, so that a flowing film is formed on the fiber bundle between the crude isooctyl nitrate and the alkali washing liquid, thereby increasing the mass transfer area and improving the mass transfer rate, the acid is extracted into the alkali washing liquid, the alkali washing liquid containing salt is separated from the fiber, and settles at the bottom of the primary alkali-washing phase separation tank, and is recycled;

[0225] The isooctyl nitrate after the primary alkaline washing and deacidification comes out from the top of the primary alkaline washing phase separation tank, enters the top of the secondary alkaline washing fiber membrane contactor installed on the secondary alkaline washing phase separation tank, and contacts with the alkaline washing liquid delivered by the secondary alkaline liquid circulation pump at the top of the secondary alkaline washing fiber membrane contactor. The alkaline washing liquid has begun to circulate before the above step A). ​​The isooctyl nitrate after the primary alkaline washing and deacidification and the alkaline washing liquid delivered by the secondary alkaline liquid circulation pump contact each other on the fiber bundle to remove the acid droplets contained in the isooctyl nitrate; the isooctyl nitrate and the alkaline washing liquid are separated by sedimentation in the secondary alkaline liquid phase separation tank, and the alkaline washing liquid after separation is continuously recycled;

[0226] The isooctyl nitrate coming out of the top of the secondary alkali phase separation tank enters the top of the water-wash fiber membrane contactor installed on the top of the water-wash phase separation tank, and contacts with the deionized water delivered by the water-wash circulation pump at the top of the water-wash fiber membrane contactor. The deionized water has begun to circulate before the water-wash desalination. The isooctyl nitrate and the deionized water after the water-wash desalination are separated by sedimentation in the water-wash phase separation tank, and the isooctyl nitrate comes out from the top of the tank.

[0227] After cooling in the heat exchanger, it enters the coalescer to coalesce the free water in isooctyl nitrate. Qualified isooctyl nitrate can be pumped to the finished product intermediate tank for testing and analysis, and then sent to the finished product tank outside the boundary area.

[0228] 3) Regenerating the waste acid produced by synthesizing isooctyl nitrate;

[0229] The waste acid produced by the synthesis of isooctyl nitrate is fed into the incinerator through the sulfuric acid nozzle inlet of the incinerator. In the incinerator, sulfuric acid is decomposed into SO2, and other impurities in the waste acid are burned at the same time. The combustion-supporting fan extracts high-temperature air from the secondary condenser and feeds it into the incinerator after passing through the air heater. The fuel gas and acid gas are directly added to the incinerator as fuel for waste acid cracking. The process gas (temperature is 1030°C) generated by the incinerator is cooled by the two-stage molten salt heat exchanger in the incinerator, and then enters the high-temperature filter for filtration. The dust carried in the process gas is separated; the process gas is pressurized and fed into the primary reactor through the process fan for primary reaction. The temperature of the primary reaction is 420°C. The catalyst for the primary reaction is a platinum catalyst.

[0230] The primary reactor is equipped with a primary reaction catalyst. X The first reactor is equipped with a first finned tube heat exchanger to remove the reaction heat and control the optimal reaction temperature. Molten salt is passed through the tube of the first finned tube heat exchanger, and the appropriate reaction temperature is obtained by controlling the flow rate of the molten salt.

[0231] The process gas enters the primary condenser for condensation; the condensation temperature is 290°C. The primary condenser is equipped with a glass tube heat exchanger. After heat exchange with the air sent in by the air blower, the sulfuric acid in the process gas is condensed and accumulated in the collection tank at the bottom of the primary condenser, and then flows to the sulfuric acid storage tank mentioned above. The outlet of the collection tank of the primary condenser is connected to the sulfuric acid storage tank.

[0232] The process gas discharged from the primary condenser is passed through a primary electrostatic precipitator to remove the acid mist (the inlet temperature of the primary electrostatic precipitator is 95°C), and then is pressurized and sent to the secondary reactor by a process gas blower for secondary reaction. The temperature of the secondary reaction is 415°C. The secondary reactor is equipped with a secondary reaction catalyst (the secondary reaction catalyst is a platinum catalyst). The unreacted NO in the primary reactor is X It continues to react with ammonia to generate nitrogen, and further oxidizes the remaining sulfur dioxide in the process gas to sulfur trioxide. The secondary reactor is equipped with a second finned tube heat exchanger to preheat the process gas and remove the reaction heat to control the reaction temperature. Molten salt is passed through the tube of the second finned tube heat exchanger, and the appropriate reaction temperature is obtained by controlling the flow of molten salt.

[0233] The process gas discharged from the secondary reactor enters the secondary condenser for condensation; the condensation temperature is 280°C. The secondary condenser is equipped with a glass tube heat exchanger. After heat exchange with the air sent in by the secondary air blower, the sulfuric acid in the process gas is condensed and accumulated in the collection tank at the bottom of the secondary condenser, and then flows to the sulfuric acid storage tank mentioned above. The outlet of the collection tank of the secondary condenser is connected to the sulfuric acid storage tank.

[0234] The process gas discharged from the secondary condenser is sent to the activated carbon reactor by the clean gas blower after the acid mist is removed by the secondary electrostatic demister. The activated carbon reactor is filled with activated carbon, and the residual sulfur dioxide is absorbed and converted into dilute sulfuric acid. The dilute sulfuric acid is sent to the primary condenser and the secondary condenser for concentration through the sulfuric acid pump, and can also be returned to the incinerator for re-decomposition. The clean tail gas is discharged into the atmosphere through the chimney. The sulfuric acid in the collection tanks of the primary condenser and the secondary condenser flows by gravity to the sulfuric acid storage tank mentioned above.

[0235] The heat brought out by the molten salt after heat exchange in each heat exchanger eventually makes the steam generator produce 4.0MPa steam, and the reaction pressure is 4.3MPa. The reaction liquid level steam is superheated to 450℃ by the three-stage steam superheater and then sent to the medium-pressure steam network. The cooled molten salt returns to the molten salt tank, and the temperature of the molten salt tank is 270℃. It is then pumped to each heat exchanger for recycling.

[0236] The performance of isooctyl nitrate obtained in Examples 1 to 3 was tested, and the results are shown in Table 2.

[0237] Table 2 Performance test data of isooctyl nitrate obtained in Examples 1 to 3

[0238]

[0239]

[0240] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing isooctyl nitrate, comprising the following steps: A) feeding nitric acid, sulfuric acid and isooctyl alcohol into a microchannel reactor at a flow ratio of 1.05:2 to 2.5:1 to react and obtain a crude isooctyl nitrate; B) regenerating the spent acid produced by the reaction; The crude isooctyl nitrate is subjected to alkali elution to remove acid and water elution to remove salt, thereby obtaining isooctyl nitrate.

2. The preparation method according to claim 1, characterized in that: In step A), the feed rate of the microchannel reactor is 2.0-3.2 kg / min; the reaction temperature is 20-50° C., and the reaction pressure is 0.3-1.5 MPa.

3. The preparation method according to claim 1, characterized in that: In step B), the alkaline washing solution used for the alkaline washing and deacidification is an aqueous solution of sodium hydroxide with a mass concentration of 18% to 20%.

4. The preparation method according to claim 1, characterized in that: In step B), the waste acid produced by the reaction is regenerated and then reused in step A).

5. The preparation method according to claim 1, characterized in that: In step B), the waste acid produced by the reaction is regenerated by the waste acid, comprising the following steps: a) sending the waste acid produced by the reaction into an incinerator to carry out waste acid cracking; b) pressurizing the process gas obtained in step a) and feeding it into a primary reactor to carry out a primary reaction; c) condensing the process gas obtained in step b) through a primary condenser, and recycling the obtained sulfuric acid to step A); The process gas discharged from the primary condenser is passed through a primary electric demister to remove acid mist, and is pressurized and sent to a secondary reactor to perform a secondary reaction; d) the process gas discharged from the secondary reactor enters the secondary condenser for condensation, and the obtained sulfuric acid is recycled to step A); e) The process gas discharged from the secondary condenser is sent to the activated carbon reactor under pressure after the acid mist is removed by the secondary electrostatic demister, and the residual sulfur dioxide is absorbed and converted into dilute sulfuric acid.

6. The preparation method according to claim 5, characterized in that: The temperature of the waste acid cracking is 1000-1050°C; The temperature of the primary reaction is 385-460° C.; the primary reaction is carried out under the condition of a primary reaction catalyst, and the primary reaction catalyst includes a vanadium catalyst and / or a platinum catalyst; In step c), the condensation temperature is 275-300°C; The inlet temperature of the first-stage electric demister is 85-105°C; The temperature of the secondary reaction is 400-430°C; The secondary reaction is carried out in the presence of a secondary reaction catalyst; the secondary reaction catalyst comprises a vanadium catalyst and / or a platinum catalyst; In step d), the condensation temperature is 265-295°C.

7. A system for preparing isooctyl nitrate, comprising: Microchannel reactor; a crude ester tank connected to the product outlet of the microchannel reactor; an alkali washing device connected to the outlet of the crude ester tank; A water washing device connected to the outlet of the alkali washing device; the water washing device is provided with an outlet for isooctyl nitrate; a waste acid tank connected to the waste acid outlet of the microchannel reactor; A waste acid regeneration device connected to the waste acid tank.

8. The preparation system according to claim 7, characterized in that: A filter, specifically a basket filter, is also provided between the crude ester tank and the alkali washing device to filter out impurities in the crude isooctyl nitrate.

9. The preparation system according to claim 7, characterized in that: The alkali washing device comprises a primary alkali washing phase separation tank and a secondary alkali washing phase separation tank connected to the product outlet of the primary alkali washing phase separation tank; A primary alkali-washing fiber membrane contactor is arranged on the top of the primary alkali-washing phase separation tank; a secondary alkali-washing fiber membrane contactor is arranged on the top of the secondary alkali-washing phase separation tank; The alkali washing device is also equipped with a primary alkali liquid circulation pump and a secondary alkali liquid circulation pump; the primary alkali liquid circulation pump is used to transport alkali washing liquid to the top of the primary alkali washing fiber membrane contactor; the secondary alkali liquid circulation pump is used to transport alkali washing liquid to the top of the secondary alkali washing fiber membrane contactor; An outlet for isooctyl nitrate is arranged on the top of the primary alkali washing phase separation tank; an outlet for isooctyl nitrate is arranged on the top of the secondary alkali washing phase separation tank, which is the outlet of the alkali washing device.

10. The preparation system according to claim 7, characterized in that: The water washing device comprises a water washing phase separation tank; A water-wash fiber membrane contactor is arranged on the top of the water-wash phase separation tank; The water washing device is also equipped with a water washing circulation pump; the water washing circulation pump is used to transport deionized water to the top of the water washing fiber membrane contactor; An outlet for isooctyl nitrate is arranged at the top of the water-wash phase separation tank.

11. The preparation system according to claim 7, characterized in that: Also includes: A heat exchanger connected to the isooctyl nitrate outlet of the water washing device; a coalescer connected to the isooctyl nitrate outlet of the heat exchanger; The heat exchanger is used to cool down the isooctyl nitrate; The coalescer is used to coalesce free water in isooctyl nitrate.

12. The preparation system according to claim 7, characterized in that: Also includes: The spent acid regeneration device comprises: Incinerators; a high temperature filter connected to the process gas outlet of the incinerator; a process fan connected to the process gas outlet of the high temperature filter; a primary reactor connected to the process gas outlet of the process blower; A primary condenser connected to the process gas outlet of the primary reactor; the collecting tank outlet of the primary condenser is connected to the sulfuric acid storage tank; a primary electric demister connected to the process gas outlet of the primary condenser; a process gas fan connected to the process gas outlet of the first-stage electrostatic precipitator; a secondary reactor connected to the process gas outlet of the process gas blower; A secondary condenser connected to the process gas outlet of the secondary reactor; the collecting tank outlet of the secondary condenser is connected to the sulfuric acid storage tank; a secondary electric demister connected to the process gas outlet of the secondary condenser; a clean air fan connected to the process air outlet of the secondary electrostatic precipitator; An activated carbon reactor connected to the process gas outlet of the clean gas blower.

13. The preparation system according to claim 12, characterized in that: The first-stage reactor is equipped with a first fin-tube heat exchanger; The first-stage condenser is equipped with a glass tube heat exchanger; The secondary reactor is provided with a second fin-tube heat exchanger.

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