阅读说明：本技术 一种合成气制乙二醇过程中副产硝酸的处理方法与系统 (Treatment method and system for byproduct nitric acid in process of preparing ethylene glycol from synthesis gas ) 是由 施德 杨卫胜 贺来宾 于 2019-10-21 设计创作，主要内容包括：本发明提供一种合成气制乙二醇过程中副产硝酸的处理方法和系统,其中,所述处理方法包括：将含副产硝酸的液相物料依次通入两个以上彼此串联连接的硝酸转化反应器内,同时,向每个硝酸转化反应器内通入含氮氧化物的气相物料。本发明所述方法采用了液相串联、气相并联的工艺,同时将液相喷淋密度控制在2～5m～3/m～2/h,可在保证催化剂利用的效率的同时,提高硝酸转化率的同时,降低床层压降。同时,硝酸转化的气相原料不通过压缩机增压,且硝酸转化的气相产物要直接进入偶联反应器,且主循环系统不增加阀门,起到了节能作用。(The invention provides a method and a system for treating byproduct nitric acid in a process of preparing ethylene glycol from synthesis gas, wherein the treatment method comprises the following steps: the liquid phase material containing the byproduct nitric acid is sequentially introduced into more than two nitric acid conversion reactors which are connected in series, and simultaneously, the gas phase material containing nitrogen oxide is introduced into each nitric acid conversion reactor. The method adopts the processes of liquid phase series connection and gas phase parallel connection, and simultaneously controls the liquid phase spraying density to be 2-5 m 3 /m 2 The catalyst can be used with high efficiency, the nitric acid conversion rate can be improved, and the bed pressure drop can be reduced. Meanwhile, the gas-phase raw material converted from the nitric acid is not pressurized by a compressor, and the nitric acid is converted into the nitric acidThe gasified gas-phase product directly enters the coupling reactor, and a valve is not added in the main circulating system, thereby playing the role of energy conservation.)

1. A treatment method of byproduct nitric acid in a process of preparing ethylene glycol from synthesis gas comprises the following steps: the liquid phase material containing the byproduct nitric acid is sequentially introduced into more than two nitric acid conversion reactors which are connected in series, and simultaneously, the gas phase material containing nitrogen oxide is introduced into each nitric acid conversion reactor.

2. The processing method according to claim 1, characterized in that it comprises the steps of:

step 1, introducing a liquid phase material containing byproduct nitric acid and a first strand of gas phase material containing nitrogen oxide into a first nitric acid conversion reactor;

and 2, introducing a liquid-phase product obtained from the tower kettle of the first nitric acid conversion reactor and a second strand of gas-phase material containing nitrogen oxide into a second nitric acid conversion reactor.

3. The treatment method according to claim 2, wherein in step 1 and step 2, gas phase products of the first nitric acid conversion reactor and the second nitric acid conversion reactor are respectively taken for cooling and gas-liquid separation treatment, then the obtained final gas phase is recycled to the esterification-coupling recycle gas system, and the liquid phase is introduced into the methanol recovery unit;

preferably, the cooling is performed at 30-60 ℃.

4. The process according to claim 2, wherein in step 1 and step 2, the difference between the internal pressures of the first nitric acid conversion reactor and the second nitric acid conversion reactor is controlled to be less than 50KPa, preferably less than 30KPa, and more preferably 5-30 KPa.

5. The process of claim 2, wherein the first and second nitric acid conversion reactors are packed with catalyst to form first and second catalyst beds, respectively; wherein the content of the first and second substances,

the catalyst loading weight ratio of the first nitric acid conversion reactor to the second nitric acid conversion reactor is 1 (0.5-1), preferably 1 (0.5-0.75); and/or

The height-diameter ratio of the first catalyst bed layer is 0.5-1.5, and the height-diameter ratio of the second catalyst bed layer is 0.8-1.8.

6. The process of claim 2, wherein the first nitric acid conversion reactor and the second nitric acid conversion reactor are both trickle bed reactors, wherein the gas phase feed and the liquid phase feed are co-current from top to bottom;

preferably, the total liquid phase volume space velocity of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 0.1-3 h^-1The liquid phase spraying density is 0.5-10 m³/m²/h。

7. The treatment method according to any one of claims 1 to 6,

the liquid phase material containing the byproduct nitric acid is a liquid phase material containing nitric acid, water and methanol, preferably a tower kettle liquid phase produced material of oxidation esterification reaction in the process of preparing ethylene glycol from synthesis gas, and optionally nitric acid is supplemented in the tower kettle liquid phase produced material; preferably, in the liquid-phase material, the content of nitric acid is 2-10%; and/or

The first stream of gas-phase material containing nitrogen oxide and the second stream of gas-phase material containing nitrogen oxide both contain 1-50 mol% of NO, and preferably are selected from circulating gas containing NO in a coupling system.

8. The processing method according to claim 7,

the flow ratio of the first strand of gas-phase material containing nitrogen oxide to the second strand of gas-phase material containing nitrogen oxide is 1 (0.5-1); and/or

In the first nitric acid conversion reactor and the second nitric acid conversion reactor, the molar ratio of NO to nitric acid is (2-10): 1, and preferably (3-8): 1.

9. The process according to claim 8, wherein the reaction temperature in the first nitric acid conversion reactor and the reaction pressure in the second nitric acid conversion reactor are 40 to 120 ℃ and 0 to 1000 KPaG.

10. A treatment system for by-product nitric acid in a process of preparing ethylene glycol from synthesis gas, which is used for carrying out the treatment method of any one of claims 1 to 9, and comprises a first nitric acid conversion reactor and a second nitric acid conversion reactor which are connected in series, wherein preferably, a tower kettle of the first nitric acid conversion reactor and a tower top of the second nitric acid conversion reactor are connected in series.

Technical Field

The invention relates to treatment of nitric acid-containing byproducts, in particular to a method for treating byproduct nitric acid in a process of preparing ethylene glycol from synthesis gas.

Background

The oxalate is an important organic chemical raw material, can be used for producing various dyes, solvents, extracting agents and various intermediates, and is widely applied to fine chemical engineering. In addition, the oxalic ester can be used for preparing the ethylene glycol through hydrogenation reaction, and the method is a new large-scale industrialized ethylene glycol synthesis process route. Ethylene glycol has long been prepared mainly by petroleum routes, and is relatively high in cost.

The traditional oxalate synthesis process is prepared by heating and esterifying oxalic acid and alcohols in a toluene solvent, and the method has the advantages of high production cost, large energy consumption, large wastewater discharge and serious pollution. The d.f. fenton research of united states oil company in the last sixties of the century found that carbon monoxide, alcohol and oxygen can be directly synthesized into dialkyl oxalate through oxidative hydroxylation. After several generations of scientific research efforts, the most suitable route for preparing oxalate by coupling carbon monoxide with alkyl nitrite is that carbon monoxide is coupled with alkyl nitrite to generate dialkyl oxalate and generate nitrogen monoxide, and the nitrogen monoxide is then reacted with methanol and oxygen to regenerate alkyl nitrite, wherein the reaction equation is as follows:

coupling reaction: 2CO +2RONO → 2NO + (COOR)2 (1)

Esterification reaction (regeneration reaction): 2ROH +0.5O₂+2NO→2RONO+H₂O (2)

Wherein R represents an alkyl group. The nitric oxide and alkyl nitrite in the route are cyclically regenerated in the system. In the esterification reaction, the main reactants are alkyl alcohol, NO and O₂. Due to the presence of NO and O in the reaction system₂The nitrogen oxide in the reaction system is diversified and always in an unstable change process, including NO and NO₂、N₂O₃、N₃O₄Wherein the effective oxide participating in the reaction to form alkyl nitrite is N₂O₃The remaining oxide forming N₂O₃And side reactions such as the formation of nitric acid may also occur. Nitric acid, however, is highly corrosive and must be removed from the regeneration gas product as completely as possible in a timely manner. In addition, water generated in the main reaction can not enter a coupling reaction system, otherwise, the oxalic acid dialkyl ester generated in the coupling reaction is easy to generate hydrolysis reaction in water to generate oxalic acid, and the oxalic acid and the water are both coupling catalyst poisons. Meanwhile, the generation of the byproduct nitric acid causes the loss of the nitric oxide in the oxidative esterification-coupling circulating gas system, the supplementation of the nitric oxide is needed, the instability of the operation of the device is increased, and the operation cost of the device is improved, so that the problem that the byproduct nitric acid of the esterification reaction is efficiently utilized, recycled and processed into one of the key technologies for the long-period stable operation of the oxalate synthesis process is effectively solved.

The traditional treatment method for preparing the ethylene glycol from the synthesis gas comprises a non-catalytic method and a catalytic method, wherein the non-catalytic method has the defects of low nitric acid conversion rate, and the reaction product needs nitric acid concentration and is recycled; the catalytic method is disclosed in patents CN106565496A and CN1445208A, and has the problems of large reactor resistance and high pressure drop, and too high resistance may result in insufficient gas phase raw material for reaction, NO: HNO₃The proportion is insufficient, the nitric acid conversion rate is reduced, a gas-phase compressor is generally required to be added, or the pressure is suppressed by adding a valve to the main material of the oxidative esterification-coupling gas-phase circulation, so that the energy consumption of the system is increased.

Disclosure of Invention

In order to overcome the problems of large system pressure drop, high energy consumption, low nitric acid conversion rate and the like in the prior art, the invention effectively reduces the resistance of a gas phase system and the energy consumption of the system while ensuring the high nitric acid conversion rate through a gas phase parallel connection and liquid phase series connection mode.

One of the purposes of the invention is to provide a method for treating byproduct nitric acid in a process of preparing ethylene glycol from synthesis gas, which comprises the following steps: the liquid phase material containing the byproduct nitric acid is sequentially introduced into more than two nitric acid conversion reactors which are connected in series, and simultaneously, the gas phase material containing nitrogen oxide is introduced into each nitric acid conversion reactor.

Aiming at the process of high concentration of nitric acid as a byproduct of oxidation esterification, wherein the nitric acid/water (weight) of a discharged liquid phase at the bottom of an esterification tower is more than 10% (the water content at the bottom of the oxidation esterification tower is 20-30% (by weight), for example, 30%, if the nitric acid concentration is more than 3% (by weight), the nitric acid/water (weight) is more than 10%), and for the nitric acid byproduct liquid with high concentration, the nitric acid conversion rate of a single nitric acid conversion reactor can not meet the requirement generally. Specifically, the problems of large reactor resistance and pressure drop due to the adoption of a single nitric acid conversion reactor exist, too high resistance can cause insufficient reaction gas phase raw materials, and the ratio of NO: HNO₃The ratio is insufficient, the nitric acid conversion rate is reduced, and therefore, a gas phase compressor is usually required to be added, or a valve is added to the main material of the oxidative esterification-coupling gas phase circulation to suppress the pressure, but the energy consumption of the system is increased.

In the invention, the catalyst bed layer in a single reactor is used in more than two (preferably two) nitric acid conversion reactors connected in series, so that the height-diameter ratio of each reactor is obviously reduced, the pressure drop is reduced, and a gas-phase compressor or a valve pressure holding mode is avoided. In addition, although one reactor is added, the cost of the method is obviously lower than that of the method adopting a compressor, so that the method effectively reduces the resistance of a gas phase system and reduces the energy consumption of the system while ensuring the high conversion rate of the nitric acid.

In a preferred embodiment, the treatment method comprises the following steps:

step 1, introducing a liquid phase material containing byproduct nitric acid (namely a liquid phase material containing nitric acid, water and methanol) and a first strand of gas phase material containing nitrogen oxide into a first nitric acid conversion reactor;

and 2, introducing a liquid-phase product obtained from the tower kettle of the first nitric acid conversion reactor and a second strand of gas-phase material containing nitrogen oxide into a second nitric acid conversion reactor.

In a further preferred embodiment, in step 1 and step 2, the gas phase products (i.e., alkyl nitrite) of the first nitric acid conversion reactor and the second nitric acid conversion reactor are taken respectively, cooled and subjected to gas-liquid separation treatment, and then the resulting final gas phase is recycled to the esterification-coupling recycle gas system, and the liquid phase is introduced into the methanol recovery unit.

Wherein, the esterification-coupling recycle gas system refers to a system for synthesizing oxalate through CO catalytic oxidation coupling reaction, namely a system for generating reactions shown in formulas (1) to (2) in the background technology.

In a further preferred embodiment, the cooling is carried out at 30 to 60 ℃.

By utilizing the treatment method, the liquid-phase product of the first nitric acid conversion reactor enters the second nitric acid conversion reactor, and is pumped to a subsequent methanol recovery unit together with the liquid-phase product of the second nitric acid conversion reactor, and the gas-phase product is directly removed from the inlet of the coupling reactor after being absorbed by methanol.

In a preferred embodiment, in the step 1 and the step 2, the difference between the internal pressures of the first nitric acid conversion reactor and the second nitric acid conversion reactor is controlled to be less than 50KPa, preferably less than 30KPa, and more preferably 5-30 KPa.

Wherein, the pressure difference refers to the pressure difference between the inlet gas-phase material and the extracted gas-phase product.

In a preferred embodiment, the first and second nitric acid conversion reactors are packed with catalyst to form first and second catalyst beds, respectively.

In a further preferred embodiment, the catalyst loading weight ratio of the first nitric acid conversion reactor to the second nitric acid conversion reactor is 1 (0.5-1), preferably 1 (0.5-0.75).

Wherein, because the liquid phase is gasified after the gas and liquid phase materials are mixed and heated, the liquid phase flow at the inlet of the second nitric acid conversion reactor is obviously reduced, and the catalyst loading of the second nitric acid conversion reactor can be lower than that of the first nitric acid conversion reactor.

In the invention, gas-liquid distributors are respectively arranged in the first nitric acid conversion reactor and the second nitric acid conversion reactor and above the catalyst bed layer.

In a preferred embodiment, the ratio of height to diameter of the first catalyst bed is 0.5 to 1.5, and the ratio of height to diameter of the second catalyst bed is 0.8 to 1.8.

In a further preferred embodiment, the aspect ratio of the first catalyst bed is 0.8 to 1.2, and the aspect ratio of the second catalyst bed is 1.0 to 1.5.

The gas phase entering the two catalyst beds is controlled by reasonably optimizing the height-diameter ratio of the first catalyst bed and the second catalyst bed, so that the gas quantity is prevented from being controlled by using an adjusting valve, and the pressure drop loss is increased.

In a preferred embodiment, the first nitric acid conversion reactor and the second nitric acid conversion reactor are both trickle bed reactors, wherein the vapor phase feed and the liquid phase feed are co-current from top to bottom.

In a preferred embodiment, the total liquid phase volume space velocity of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 0.1-3 h^-1The liquid phase spraying density is 0.5-10 m³/m²/h。

In a further preferred embodiment, the total liquid phase volume space velocity of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 0.5-2 h^-1The liquid phase spraying density is 2-5 m³/m²/h。

In the prior art, in order to reduce the pressure drop of the nitric acid conversion reactor, the reactor needs to be improved, the diameter of the reactor needs to be enlarged, and the height-diameter ratio of the reactor needs to be reduced. In the present invention, no modification of the reactor is required, or a conventional reactor is used, and thus, the spray density is not affected. Thus, the invention adopts the processes of liquid-phase material series connection and gas-phase product parallel connection, and simultaneously controls the liquid-phase spraying density to be 2-5 m³/m²The catalyst utilization efficiency can be ensured, the nitric acid conversion rate is improved, and the bed pressure drop is reduced.

In a preferred embodiment, the liquid-phase material containing by-product nitric acid in step 1 is a liquid-phase material containing nitric acid, water and methanol, and is preferably a tower kettle liquid-phase extracted material of an oxidation esterification reaction in a process of preparing ethylene glycol from synthesis gas.

In a further preferred embodiment, the liquid phase feed is optionally supplemented with nitric acid.

The supplemented nitric acid can be purchased concentrated nitric acid or nitric acid obtained by concentrating unreacted nitric acid in a liquid-phase product, the preferred supplemented nitric acid comprises 20-68% of nitric acid, and the balance of water, and the supplemented nitric acid has the function of making up for the loss of nitrogen oxides in the system.

In a further preferred embodiment, the content of nitric acid in the liquid phase material is 2-10%.

Wherein, the content of the nitric acid refers to the total amount of the nitric acid after supplementing the nitric acid.

In a preferred embodiment, the first stream of gaseous feed containing nitrogen oxides and the second stream of gaseous feed containing nitrogen oxides both contain 1 to 50 mol% NO, preferably 10 to 30 mol% NO.

In a further preferred embodiment, the first stream of gas phase feed comprising nitrogen oxides and the second stream of gas phase feed comprising nitrogen oxides are both selected from the group consisting of NO-containing recycle gas in the coupling system.

The coupling system is a system which generates coupling reaction in the synthesis of oxalate through CO catalytic oxidation coupling reaction, namely a system which generates reaction shown in formula (1) in the background technology.

In a further preferred embodiment, the flow ratio of the first stream of gaseous feed comprising nitrogen oxides to the second stream of gaseous feed comprising nitrogen oxides is 1 (0.5-1).

The flow ratio of the first stream of gas containing nitrogen oxide to the second stream of gas containing nitrogen oxide is controlled to be 1 (0.5-1) by adjusting the height-diameter ratio of the catalyst bed layer, so that energy can be saved, and the relatively high nitric acid conversion rate can be achieved.

In a preferred embodiment, the molar ratio of NO to nitric acid in the first nitric acid conversion reactor and the second nitric acid conversion reactor is (2-10): 1, preferably (3-8): 1.

In the present invention, NO reacts with nitric acid as follows:

(2NO+3CH₃OH+HNO₃→2CH₃ONO+H₂O)。

in a preferred embodiment, the reaction temperature in the first nitric acid conversion reactor and the reaction pressure in the second nitric acid conversion reactor are 40-120 ℃ and 0-1000 KPaG.

In a further preferred embodiment, the reaction temperature in the first nitric acid conversion reactor and the reaction pressure in the second nitric acid conversion reactor are 60 to 100 ℃ and 200 to 500 KPaG.

By using the treatment method, the total conversion rate of the nitric acid is 80.0-99.9%, preferably more than 90%, for example more than 98%.

The second purpose of the present invention is to provide a treatment system for by-product nitric acid in a process of preparing ethylene glycol from synthesis gas, which is used for performing the treatment method of the first purpose of the present invention, wherein, as shown in fig. 1, the treatment system comprises a first nitric acid conversion reactor 1 and a second nitric acid conversion reactor 2 which are connected in series, and preferably, a tower bottom of the first nitric acid conversion reactor 1 and a tower top of the second nitric acid conversion reactor 2 are connected in series.

In the invention, as shown in fig. 1, a liquid phase material 3 containing nitric acid, water and methanol and a first strand of gas phase material 4 containing nitrogen oxides are mixed and heated and then enter a first nitric acid conversion reactor 1, a first nitric acid conversion reactor liquid phase product 5 and a first nitric acid conversion reactor gas phase product 6 are directly obtained by separation at the tower bottom of the first nitric acid conversion reactor 1, the first nitric acid conversion reactor liquid phase product 5 and a second strand of gas phase material 7 containing nitrogen oxides are mixed and heated and then enter a second nitric acid conversion reactor 2, and a second nitric acid conversion reactor liquid phase product 8 and a second nitric acid conversion reactor gas phase product 9 are directly obtained by separation at the tower bottom of the second nitric acid conversion reactor 2.

The endpoints of the ranges and any values disclosed in the present application are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual values, and between the individual values may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein. In the above, the various technical solutions can in principle be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in the present invention.

Compared with the prior art, the invention has the following beneficial effects:

(1) in the invention, the gas-phase raw material converted by nitric acid is not pressurized by a compressor, and the gas-phase product converted by nitric acid directly enters the coupling reactor, and a valve is not added in the main circulating system, thereby playing a role in energy conservation;

(2) the method adopts the processes of liquid phase series connection and gas phase parallel connection, and simultaneously controls the liquid phase spraying density to be 2-5 m³/m²The catalyst utilization efficiency can be ensured, the nitric acid conversion rate is improved, and the bed pressure drop is reduced;

(3) the invention ensures high conversion rate of nitric acid by gas phase parallel connection and liquid phase series connection, effectively reduces the resistance of a gas phase system and reduces the energy consumption of the system.

Drawings

FIG. 1 is a schematic structural diagram of a treatment system for by-product nitric acid in a process of preparing ethylene glycol from synthesis gas according to the invention;

in fig. 1, 1 is a first nitric acid conversion reactor, 2 is a second nitric acid conversion reactor, 3 is a liquid phase material containing nitric acid, water and methanol, 4 is a first stream of gas phase material containing nitrogen oxides, 5 is a first nitric acid conversion reactor liquid phase product, 6 is a first nitric acid conversion reactor gas phase product, 7 is a second stream of gas phase material containing nitrogen oxides, 8 is a second nitric acid conversion reactor liquid phase product, and 9 is a second nitric acid conversion reactor gas phase product.

Detailed Description

While the present invention will be described in detail with reference to the following examples, it should be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the present invention.

It is to be further understood that the various features described in the following detailed description may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

The nitric acid concentrations in the examples and comparative examples were analyzed by titration, the water content by Karl Fischer method, and other components by gas chromatography. The method for calculating the conversion rate of the nitric acid comprises the following steps: the nitric acid conversion rate is 1-inlet liquid phase flow rate × nitric acid concentration/(outlet liquid phase flow rate × nitric acid concentration).

Example 1

Material 35m containing nitric acid, water and methanol³The composition by weight is as follows: 72% of methanol, 25% of water and 3% of nitric acid.

The first stream of gas containing nitrogen oxide has standard volume flow rate of 8000Nm³A standard volume flow rate of 6000Nm for a second gas stream containing nitrogen oxides³H, molar composition: NO 15%, CO₂ 10％，N₂55 percent of methyl nitrite, 5 percent of CO 12 percent and 3 percent of methanol.

The filling volume of the first nitric acid conversion reaction catalyst is 20m³The diameter of the reactor is 3m, the filling height is 2.8m, and the height-diameter ratio is 0.93; the catalyst filling volume of the second nitric acid conversion reactor is 15m³The diameter of the reactor is 2.6m, the filling height is 2.8m, and the height-diameter ratio is 1.08. The inlet temperature of the first nitric acid conversion reactor and the inlet temperature of the second nitric acid conversion reactor are both controlled to be 90 ℃, and the reaction pressure is 500 KPaG. The reaction gas phase product is cooled and absorbed by methanol and then directly goes to the inlet of the coupling reactor, and the liquid phase is introduced into a methanol recovery unit.

The nitric acid treatment is carried out by adopting the scheme, and the total liquid phase volume space velocity of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 1h^-1First, dinitrate conversion reactorThe spraying density of the inlet liquid phase is 4.1m³/m²The distribution of liquid phase is relatively easy, the pressure drop of the reactor is only 10KPa, the gas phase raw material does not need extra pressurization, the energy consumption is low, and the conversion rate of nitric acid reaches 98 percent.

Example 2

Material 35m containing nitric acid, water and methanol³The composition by weight is as follows: 60% of methanol, 30% of water and 10% of nitric acid (the nitric acid is supplemented to 10%).

The first stream of gas containing nitrogen oxide has standard volume flow rate of 7200Nm³H, standard volume flow of a second gas containing nitrogen oxides 6800Nm³H, molar composition: NO 30%, CO₂ 5％，N₂45 percent of methyl nitrite, 5 percent of CO 12 percent and 3 percent of methanol.

The filling volume of the first nitric acid conversion reaction catalyst is 23m³The diameter of the reactor is 3m, the filling height is 3.2m, and the height-diameter ratio is 1.07; catalyst filling volume of the second nitric acid conversion reactor is 12m³The diameter of the reactor is 2.6m, the filling height is 2.3m, and the height-diameter ratio is 0.88. The inlet temperature of the first nitric acid conversion reactor and the inlet temperature of the second nitric acid conversion reactor are both controlled to be 100 ℃, and the reaction pressure is 450 KPaG. The reaction gas phase product is cooled and absorbed by methanol and then directly goes to the inlet of the coupling reactor, and the liquid phase is introduced into a methanol recovery unit.

The nitric acid treatment is carried out by adopting the scheme, and the total liquid phase volume space velocity of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 1h^-1The spraying density of the liquid phase at the inlets of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 3.5m³/m²The distribution of liquid phase is relatively easy, the pressure drop of the reactor is only 15KPa, the gas phase raw material does not need extra pressurization, the energy consumption is low, and the conversion rate of nitric acid reaches 85 percent.

Example 3

Material 35m containing nitric acid, water and methanol³The composition by weight is as follows: 65% of methanol, 30% of water and 5% of nitric acid.

Standard volume flow rate of first stream of gas containing nitrogen oxide of 7500Nm³Standard volume flow rate 7500Nm of a second gas containing nitrogen oxide³H, molar composition: NO 20%, CO₂ 5％，N₂56% in nitrous acidAcid methyl ester 8%, CO 10%, methanol 1%.

The loading volume of the first nitric acid conversion reaction catalyst is 17.5m³The reaction diameter is 3m, the filling height is 2.5m, and the height-diameter ratio is 0.83; the catalyst filling volume of the second nitric acid conversion reactor is 17.5m³The diameter of the reactor is 3m, the filling height is 2.5m, and the height-diameter ratio is 0.83. The inlet temperature of the first nitric acid conversion reactor and the inlet temperature of the second nitric acid conversion reactor are both controlled to be 80 ℃, and the reaction pressure is 1000 KPaG. The reaction gas phase product is cooled and absorbed by methanol and then directly goes to the inlet of the coupling reactor, and the liquid phase is introduced into a methanol recovery unit.

The nitric acid treatment is carried out by adopting the scheme, and the total liquid phase volume space velocity of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 1h^-1The spraying density of the liquid phase at the inlet of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 4.7m respectively³/m²H and 4.4m³/m²The distribution of liquid phase is relatively easy, the pressure drop of the reactor is only 5KPa, the gas phase raw material does not need extra pressurization, the energy consumption is low, and the conversion rate of nitric acid reaches 80 percent.

Example 4

Material 35m containing nitric acid, water and methanol³The composition by weight is as follows: 70% of methanol, 26% of water and 4% of nitric acid.

The first stream of gas containing nitrogen oxide has a standard volume flow rate of 9300Nm³Standard volume flow rate of 4700Nm for the second gas containing nitrogen oxide³H, molar composition: NO 15%, CO₂ 5％，N₂% of methyl nitrite, 8% of CO 15% and 3% of methanol.

The filling volume of the first nitric acid conversion reaction catalyst is 20m³The reaction diameter is 2.8m, the filling height is 3.3m, and the height-diameter ratio is 1.18; the catalyst filling volume of the second nitric acid conversion reactor is 15m³The diameter of the reactor is 2.2m, the filling height is 4m, and the height-diameter ratio is 1.8. The total liquid phase volume space velocity of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 1h^-1The inlet temperature of the first nitric acid conversion reactor and the inlet temperature of the second nitric acid conversion reactor are both controlled to be 90 ℃, and the reaction pressure is 500 KPaG. The reaction gas phase product is cooled and absorbed by methanol and then directly goes to the inlet of the coupling reactor, and the liquid phase is introduced into a methanol recovery unit.

The nitric acid treatment is carried out by adopting the scheme, and the inlet liquid phase spraying densities of the first nitric acid conversion reactor and the second nitric acid conversion reactor are respectively 4.5m³/m²H and 6.0m³/m²The liquid phase distribution is relatively easy, the pressure drop of the reactor is 18KPa, the gas phase raw material does not need extra pressurization, the energy consumption is low, and the conversion rate of the nitric acid reaches 98.5 percent.

Example 5

Material 35m containing nitric acid, water and methanol³The composition by weight is as follows: 60% of methanol, 30% of water and 10% of nitric acid.

The first stream of gas containing nitrogen oxide has standard volume flow rate of 7200Nm³H, standard volume flow of a second gas containing nitrogen oxides 6800Nm³H, molar composition: NO 30%, CO₂ 5％，N₂45 percent of methyl nitrite, 5 percent of CO 12 percent and 3 percent of methanol.

First nitric acid conversion reaction catalyst loading volume is 46m³The diameter of the reactor is 3.8m, the filling height is 4.1m, and the height-diameter ratio is 1.08; catalyst filling volume of the second nitric acid conversion reactor is 24m³The diameter of the reactor is 2.8m, the filling height is 3.9m, and the height-diameter ratio is 1.39. The total liquid phase volume space velocity of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 0.5h^-1The inlet temperature of the first nitric acid conversion reactor and the inlet temperature of the second nitric acid conversion reactor are both controlled to be 100 ℃, and the reaction pressure is 450 KPaG. The reaction gas phase product is cooled and absorbed by methanol and then directly goes to the inlet of the coupling reactor, and the liquid phase is introduced into a methanol recovery unit.

The nitric acid treatment is carried out by adopting the scheme, and the total liquid phase volume space velocity of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 0.5h^-1The spraying density of the liquid phase at the inlet of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 2.3m³/m²/h、3.1m³/m²The distribution of liquid phase is relatively easy, the pressure drop of the reactor is only 13KPa, the gas phase raw material does not need extra pressurization, the energy consumption is low, and the conversion rate of nitric acid reaches 95 percent.

Example 6

Material 35m containing nitric acid, water and methanol³The composition by weight is as follows: 70% of methanol, 26% of water and 4% of nitric acid.

The first stream of gas containing nitrogen oxide has a standard volume flow rate of 8700Nm³A second stream of nitrous oxide containing gas having a nominal volumetric flow rate of 5300Nm³H, molar composition: NO 15%, CO₂ 5％，N₂% of methyl nitrite, 8% of CO 15% and 3% of methanol.

The filling volume of the first nitric acid conversion reaction catalyst is 10m³The reaction diameter is 2.2m, the filling height is 3.3m, and the height-diameter ratio is 1.2; the catalyst filling volume of the second nitric acid conversion reactor is 7.5m³The diameter of the reactor is 1.8m, the filling height is 2.9m, and the height-diameter ratio is 1.6. The total liquid phase volume space velocity of the first nitric acid conversion reactor and the second nitric acid conversion reactor is 2h^-1The inlet temperature of the first nitric acid conversion reactor and the inlet temperature of the second nitric acid conversion reactor are both controlled to be 90 ℃, and the reaction pressure is 500 KPaG. The reaction gas phase product is cooled and absorbed by methanol and then directly goes to the inlet of the coupling reactor, and the liquid phase is introduced into a methanol recovery unit.

The nitric acid treatment is carried out by adopting the scheme, and the inlet liquid phase spraying densities of the first nitric acid conversion reactor and the second nitric acid conversion reactor are respectively 7.4m³/m²H and 9.0m³/m²The liquid phase distribution is relatively easy, the pressure drop of the reactor is 17KPa, the gas phase raw material does not need extra pressurization, the energy consumption is low, and the conversion rate of the nitric acid reaches 92 percent.

Comparative example 1

The by-product nitric acid from the apparatus for producing ethylene glycol by treating synthesis gas was obtained in the same manner as in example 1, except that one reactor was used and the total catalyst loading was 35m³Diameter of reactor 3m, height of catalyst 5m, total reaction gas amount 14000Nm³The liquid phase volume space velocity of the reactor is 1h^-1The inlet liquid phase spraying density is 3.4m³/m²The nitric acid conversion rate can reach 98%, but the pressure drop of the reactor reaches 55KPa, and a raw material gas supercharger needs to be additionally arranged, so that the equipment investment, the device maintenance cost and the device energy consumption are greatly increased.