CN1122654C - Method for producing formaldehyde by using crude methanol as coproduct of synthetic ammonia - Google Patents
Method for producing formaldehyde by using crude methanol as coproduct of synthetic ammonia Download PDFInfo
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- CN1122654C CN1122654C CN 00115013 CN00115013A CN1122654C CN 1122654 C CN1122654 C CN 1122654C CN 00115013 CN00115013 CN 00115013 CN 00115013 A CN00115013 A CN 00115013A CN 1122654 C CN1122654 C CN 1122654C
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- methyl alcohol
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Abstract
The present invention relates to a method for preparing formaldehyde by using 80 to 95 wt% of coarse methanol together produced with synthetic ammonia under the action of a silver catalyst. A production process comprises the evaporation of methanol, the oxidation of the methanol and the absorption of formaldehyde. Two high efficient adsorption filters are respectively connected with the front and the back of a methanol evaporator. After coarse methanol is adsorbed and filtered twice, the content of harmful impurities of paraffin, etc. in materials is lowered from 1 wt% to 0.1 wt%, and the method ensures that the silver catalyst in an oxidation tower is free from poison. The method uses 80 to 95 wt% of coarse methanol to substitute for 98 to 99 wt% of fine methanol to prepare at least 37 wt% of formaldehyde solutions. The energy consumption is saved, the production cost is lowered, and the economic benefit is enhanced.
Description
The present invention relates to a kind ofly under the silver catalyst effect, methyl alcohol and air generation oxidative dehydrogenation prepare the method for formaldehyde, relate to the method that the thick methyl alcohol of synthetic ammonia coproducing prepares formaldehyde or rather.
In prior art CN1066264, disclose a kind of under silver catalyst, methyl alcohol and air generation oxidative dehydrogenation generate the method for formaldehyde, this technology utilizes the sensible heat of reaction product directly as the superheater thermal source, can reduce the batching steam of 30～double centner/ton (product); Utilize the methyl alcohol of gaseous reaction product condensation latent heat direct evaporation about 80%.Set up methanol rectifying tower, solve base of evaporator water and impurity enriched problem, remove the impurity that makes poisoning of catalyst, prolonged the work-ing life of silver catalyst, reduced the unit consumption of methyl alcohol.But the methanol solution of 15%～25% (weight) that this technology is drawn from the methanol evaporator bottom will become the refined methanol of 98%～99% (weight) through rectifying tower rectifying, then, and again with refined methanol system formaldehyde.Methanol rectification will consume a large amount of heat energy, as if getting rid of this operation of methanol rectification, can make the output height again, and the measured formaldehyde of matter then should just improve with rationally more in invention.
The objective of the invention is to utilize the thick methyl alcohol (methanol content is 80～95% (weight)) of synthetic ammonia coproducing directly to prepare the industrial formol of formaldehyde content 〉=37% (weight).Get rid of methanol rectification operation of the prior art, saved energy consumption, reduced production cost, improved economic benefit.
The present invention is the method for a producing formaldehyde by using crude methanol as coproduct of synthetic ammonia, be included under the katalysis of silver catalyst, methyl alcohol and air generation oxidative dehydrogenation generate formaldehyde, and production technique comprises: the absorption of evaporation, oxidation and the formaldehyde of thick methyl alcohol is characterized in that:
1) methyl alcohol that evaporates for methanol evaporator is that the methanol content of synthetic ammonia coproducing alcohol tower production is the thick methyl alcohol of 80～95% (weight),
2) respectively connecting an adsorption filter at methanol evaporator forward and backward, be filled with commercially available alkaline gac in the strainer, gac is placed on that two layers of stainless steel sift are online, and screen cloth is being supported by sieve plate,
3) a paraffin upflow tube is installed at the middle part of methanol evaporator.
The methanol content that joins pure tower production from synthetic ammonia is to contain 1% normal alkane (paraffin) and iron etc. the thick methyl alcohol of 80%～95% (weight) to the silver catalyst detrimental impurity.Respectively connecting a charcoal absorption strainer at methanol evaporator forward and backward, making liquid crude methanol before entering vaporizer, carry out one time contaminant filter earlier.The liquid crude methanol that enters vaporizer enters a back charcoal absorption strainer again from the outflow of vaporizer lower pipelines and carries out adsorption filtration again after heating, content through detrimental impurity in the thick methyl alcohol material after twice adsorption filtration drops to about 0.1% (weight) from 1% (weight), guaranteed that the silver catalyst in the oxidizing tower of back is not poisoned by impurity, prolong catalyst life, guaranteed normally carrying out of methanol catalytic oxidation process.
It is for the objectionable impuritiess such as paraffin of remaining 0.1% (weight) in the thick methyl alcohol are done further to remove that the vaporizer middle part is provided with the paraffin upflow tube.When the vaporization temperature in the vaporizer reaches 70 ℃, open upflow tube, emit the vasoliniment that contains that has liquefied in the material, contain vasoliniment cooling after, decant impurity such as paraffin, remaining methanol aqueous solution reclaims the Returning evaporimeter utilization.Like this, just can guarantee to enter the purity of the methanol vapor of oxidizing tower, avoid the silver catalyst in the oxidizing tower to be poisoned by impurity.
The particle diameter of the alkaline activated carbon among the present invention in the adsorption filter is Φ 1.5 * 4mm～3.0 * 6mm, and the mesh of stainless steel mesh is 150～200 orders, and the aperture of sieve plate is Φ 5～Φ 15mm.
The loading level of gac can according to how many decisions of charging, and the packed space of gac is 0.2～0.6m on the screen cloth
3
The methyl alcohol that comes out from vaporizer among the present invention, air and steam enter oxidizing tower behind make up water steam material consists of methyl alcohol: air: the mol ratio of water vapor equals 1: 1.96: 1.58.
Used silver catalyst is catalyst for electrolytic silver or float stone silver catalyst in the oxidizing tower of methanol oxidation of the present invention.
The present invention respectively connects a charcoal absorption strainer in the front and back of methanol evaporator, makes thick methyl alcohol through forward and backward twice adsorption filtration, and the content of detrimental impurity such as paraffin, iron is reduced to 0.1% (weight) from 1% (weight) in the thick methyl alcohol material.Use simultaneously the paraffin upflow tube at vaporizer middle part again, constantly remove remaining detrimental impurity in the material, guaranteed normally carrying out of methanol oxidation formaldehyde technology.Replacing concentration with the thick methyl alcohol of 80～95% (weight) is that the refined methanol of 98～99% (weight) prepares the formaldehyde of content greater than 37% (weight).Get rid of methanol rectification operation of the prior art, saved energy consumption, reduced production cost, improved economic benefit.
The quality product of the technical grade formaldehyde that the present invention makes reaches GB9009-88 top grade product index.
Formaldehyde products to thick methyl alcohol system formaldehyde of the present invention and refined methanol system formaldehyde is carried out aggregation test, and test result shows that the quality product of the thick methyl alcohol system formaldehyde of the present invention is better than the quality product of prior art refined methanol system formaldehyde.Test result is as shown in the table: the oxymethylene polymerization test
| Refined methanol system formaldehyde | Thick methyl alcohol system formaldehyde | |
| The turbid phenomenon time opening (h) | 1 | 2 |
| 24 hours postprecipitation amounts | 2 | 1 |
| 48 hours postprecipitation amounts | 2 | 1 |
From table, can find out, the formaldehyde that thick methyl alcohol makes makes late 1 hour of oxymethylene polymerization time than refined methanol, and polymerization amount lacks 1 times, and the storage of this PARA FORMALDEHYDE PRILLS(91,95), transportation have extraordinary effect, illustrates that the aggregation property of the formaldehyde of thick methanol production is better than the formaldehyde that refined methanol is produced.
Compare with refined methanol system formaldehyde, the cost of thick methyl alcohol system formaldehyde reduces more than 10%.Adopt thick methyl alcohol system formaldehyde than descending 66.7 yuan,, can reduce cost every year 1000000 yuan to produce 15000 tons of calculating of formaldehyde per year with refined methanol system formaldehyde formaldehyde cost per ton.
Process flow sheet of the present invention as shown in drawings, number in the figure is represented: the thick methanol feed line of 1-, 2, the 2a-adsorption filter, 3-methanol evaporator, 4-advances vapour line, the 5-oxidizing tower, 6,6a-advances the soft water pipeline, 7, the 7a-absorption tower, 8-exhaust emissions pipeline, 9-formaldehyde discharging pipeline, 10-upflow tube, 11-air feed tube line.
Now in conjunction with the embodiments content of the present invention is described further.
Embodiment 1:
The liquid crude methanol of 80% (weight) of synthetic ammonia coproducing is with 1.2m
3The flow of/h enters adsorption filter 2 from pipeline 1, after most of impurity is fallen in adsorption filtration, liquid crude methanol enters methanol evaporator 3, the vaporization temperature of methyl alcohol is controlled at 50～70 ℃, liquid material after the heating flows out from the lower pipelines of vaporizer 3 and enters a back adsorption filter 2a and carry out adsorption filtration again, reduces to about 0.1% (weight) from 1% (weight) through the material foreign matter content of twice adsorption filtration.The thick methyl alcohol material that comes out from strainer 2a enters methanol evaporator 3 again and evaporates.Air from pipeline 11 with 950m
3The flow of/h enters vaporizer 3 and thick methyl alcohol material evaporates together, and when the methyl alcohol vaporization temperature rises to 62 ℃, during vapor liquid equilibrium, the equilibrium concentration of methyl alcohol is 74% (weight) in the liquid phase.When vaporization temperature rises to 70 ℃, upflow tube 10 is opened, emit the methanol solution that contains impurity such as paraffin, behind the decantation paraffin, remaining methanol solution is sent into evaporation in the vaporizer 3 again.The evaporation material is through pipeline 4 make up water steam, and steam rates is 250kg/h, and make the methyl alcohol that consists of of material: air: the mol ratio of water vapor equals 1: 1.96: 1.58.The material of this proportioning enters oxidizing tower 5, and under 650 ℃ temperature, through the katalysis of catalyst for electrolytic silver, the methanol oxidation dehydrogenation generates formaldehyde gas.Formaldehyde gas enters cooling and absorbing tower 7 from oxidizing tower 5 bottoms.7 tops enter tower internal cooling absorption formaldehyde gas to soft water in the pipeline 6 from the absorption tower.The formaldehyde gas of about 80～90% (weight) is absorbed to generate the industrial formol liquid of 37% (weight), puts into storage tank through pipeline 9.Unabsorbed a small amount of formaldehyde gas enters absorption tower 7a, the structure of 7a and composition and absorption tower 7 are just the same, soft water enters in the tower from 7a top, absorption tower through pipeline 10a, absorb remaining formaldehyde gas, the rare formaldehyde liquid that generates returns absorption tower 7,7 tops enter in the tower and to absorb formaldehyde gas and generate 37% (weight) industrial formol and put into storage tank from pipeline 9 from the absorption tower, and the output that enters 37% (weight) industrial formol of storage tank is 1.3m
3/ h, the unabsorbed tail gas emptying after pipeline 8 enters waste heat boiler burning recovery heat that contains trace formaldehyde, hydrogen, carbon monoxide, carbonic acid gas.
Embodiment 2:
Removing the liquid crude methanol concentration that enters adsorption filter 2 is 87% (weight), and flow is 1.2m
3/ h, pipeline 11 air flow quantitys are 950m
3/ h, the vapor liquid equilibrium temperature is 59 ℃ in the vaporizer 3, and the methyl alcohol equilibrium concentration is 78% (weight) in the liquid phase, and it is 250kg/h that pipeline 4 is added steam rates, and generating industrial formol content is 37.2% (weight), output is 1.4m
3Outside/the h, other processing step, material proportion and reaction parameter are all with embodiment 1.
Embodiment 3:
Removing the liquid crude methanol concentration that enters adsorption filter 2 is 95% (weight), and flow is 1.1m
3/ h, pipeline 11 air flow quantitys are 1000m
3/ h, the vapor liquid equilibrium temperature is 52 ℃ in the vaporizer 3, and the methyl alcohol equilibrium concentration is 86% (weight) in the liquid phase, and it is 330kg/h that pipeline 4 is added steam rates, and generating industrial formol content is 37.4% (weight), output is 1.6m
3Outside/the h, other processing step, material proportion and reaction parameter are all with embodiment 1.
The comparative example 1:
Minus two adsorption filters 2 and 2a than embodiment 1 in the processing step, methanol solution directly enters vaporizer 3 evaporations, and the methanol concentration that enters vaporizer 3 is the refined methanol of 99.8% (weight), and flow is 1.0m
3/ h, pipeline 11 air flow quantitys are 1000m
3/ h, the vapor liquid equilibrium temperature is 46 ℃ in the vaporizer 3, and the methyl alcohol equilibrium concentration is 94% (weight) in the liquid phase, and it is 360kg/h that pipeline 4 is added steam rates, and generating industrial formol content is 37% (weight), output is 1.6m
3Outside/the h, other processing step, material proportion and reaction parameter are all with embodiment 1.
Claims (4)
1, a kind of method of producing formaldehyde by using crude methanol as coproduct of synthetic ammonia is included under the silver catalyst effect, and methyl alcohol and air generation oxidative dehydrogenation generate formaldehyde, and production process comprises: the absorption of the evaporation of methyl alcohol, oxidation and formaldehyde is characterized in that:
1) be that the methanol content that synthetic ammonia joins pure tower production is the thick methyl alcohol of 80～95% (weight) for the methyl alcohol of methanol evaporator evaporation,
2) respectively connecting an adsorption filter at methanol evaporator forward and backward, be filled with commercially available alkaline gac in the strainer, gac is placed on that two layers of stainless steel sift are online, and screen cloth is being supported by sieve plate,
3) at the methanol evaporator middle part paraffin upflow tube is installed.
2, the method for thick methyl alcohol system formaldehyde according to claim 1, it is characterized in that: the particle diameter of the alkaline activated carbon in the adsorption filter is Φ 1.5 * 4mm～3.0 * 6mm, the mesh of stainless steel mesh is 150～200 orders, and the aperture of sieve plate is Φ 5～Φ 15mm.
3, the method for thick methyl alcohol system formaldehyde according to claim 1, it is characterized in that the material that enters oxidizing tower consists of methyl alcohol: air: the mol ratio of water vapor equals 1: 1.96: 1.58.
4, the method for thick methyl alcohol system formaldehyde according to claim 1 is characterized in that silver catalyst used in the oxidizing tower of methanol oxidation is catalyst for electrolytic silver or float stone silver catalyst.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00115013 CN1122654C (en) | 2000-03-21 | 2000-03-21 | Method for producing formaldehyde by using crude methanol as coproduct of synthetic ammonia |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00115013 CN1122654C (en) | 2000-03-21 | 2000-03-21 | Method for producing formaldehyde by using crude methanol as coproduct of synthetic ammonia |
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| Publication Number | Publication Date |
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| CN1314334A CN1314334A (en) | 2001-09-26 |
| CN1122654C true CN1122654C (en) | 2003-10-01 |
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| CN 00115013 Expired - Fee Related CN1122654C (en) | 2000-03-21 | 2000-03-21 | Method for producing formaldehyde by using crude methanol as coproduct of synthetic ammonia |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102295542A (en) * | 2011-07-01 | 2011-12-28 | 福建省永安林业(集团)股份有限公司 | Integrated utilization method of heat in formaldehyde production process |
| CN106800503A (en) * | 2015-11-25 | 2017-06-06 | 衡阳屹顺化工有限公司 | A kind of preparation method of neopentyl glycol raw materials for production |
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