阅读说明：本技术 一种粗甲醇制甲醛预处理工艺 (Pretreatment process for preparing formaldehyde from crude methanol ) 是由 王雪岭 孙文文 于 2021-07-27 设计创作，主要内容包括：本发明公开的属于化学工艺技术领域,具体为一种粗甲醇制甲醛预处理工艺,包括以下步骤：(1)来自粗甲醇罐区的粗甲醇进入粗甲醇预热器,通过蒸汽间接加热,控制粗甲醇预热器出口温度30～50℃；(2)经过加热后的粗甲醇,通过甲醇增压泵加压送入一级过滤器,增压泵出口压力0.6～0.8MPa；(3)经过一级过滤器后进入二级过滤器,过滤粗甲醇中油蜡等有机杂质,控制过滤器上下压差不超过0.05MPa；(4)经过前两级过滤器后,进入三级过滤器,过滤粗甲醇中酸性杂质,控制过滤器上下压差不超过0.05MPa；(5)经过三级过滤器后,进入甲醇精密过滤器,去除甲醇中的机械杂质后,进入下一工段。该种粗甲醇制甲醛预处理工艺工艺简单高效,企业效益得到提高。(The invention discloses a pretreatment process for preparing formaldehyde from crude methanol, belonging to the technical field of chemical processes, comprising the following steps: (1) the method comprises the following steps that crude methanol from a crude methanol tank area enters a crude methanol preheater, steam is used for indirect heating, and the outlet temperature of the crude methanol preheater is controlled to be 30-50 ℃; (2) pressurizing the heated crude methanol by a methanol booster pump, and conveying the heated crude methanol into a primary filter, wherein the outlet pressure of the booster pump is 0.6-0.8 MPa; (3) the crude methanol enters a secondary filter after passing through a primary filter, organic impurities such as oil wax and the like in the crude methanol are filtered, and the pressure difference between the upper part and the lower part of the filter is controlled not to exceed 0.05 MPa; (4) after passing through the first two-stage filter, the crude methanol enters a third-stage filter, acid impurities in the crude methanol are filtered, and the pressure difference between the upper part and the lower part of the filter is controlled not to exceed 0.05 MPa; (5) and after passing through the three-stage filter, the methanol solution enters a methanol precision filter, mechanical impurities in the methanol are removed, and then the methanol solution enters the next working section. The pretreatment process for preparing formaldehyde from crude methanol is simple and efficient, and the enterprise benefit is improved.)

1. A pretreatment process for preparing formaldehyde from crude methanol is characterized by comprising the following steps: the method comprises the following steps:

(1) the method comprises the following steps that crude methanol from a crude methanol tank area enters a crude methanol preheater, steam is used for indirect heating, and the outlet temperature of the crude methanol preheater is controlled to be 30-50 ℃;

(2) pressurizing the heated crude methanol by a methanol booster pump, and conveying the heated crude methanol into a primary filter, wherein the outlet pressure of the booster pump is 0.6-0.8 MPa;

(3) the crude methanol enters a secondary filter after passing through a primary filter, organic impurities such as oil wax and the like in the crude methanol are filtered, and the pressure difference between the upper part and the lower part of the filter is controlled not to exceed 0.05 MPa;

(4) after passing through the first two-stage filter, the crude methanol enters a third-stage filter, acid impurities in the crude methanol are filtered, and the pressure difference between the upper part and the lower part of the filter is controlled not to exceed 0.05 MPa;

(5) and after passing through the three-stage filter, the methanol solution enters a methanol precision filter, mechanical impurities in the methanol are removed, and then the methanol solution enters the next working section.

2. The pretreatment process for preparing formaldehyde from crude methanol according to claim 1, which is characterized in that: the crude methanol preheater is a coil heating device, the outlet temperature of the crude methanol preheater is controlled to be 30-50 ℃, and the optimal state of subsequent filtering activity is achieved.

3. The pretreatment process for preparing formaldehyde from crude methanol according to claim 1, which is characterized in that: the three-stage filter passes through the filter bed layer from top to bottom.

4. The pretreatment process for preparing formaldehyde from crude methanol according to claim 1, which is characterized in that: the pressure difference between the inlet and the outlet of each filter of the primary filter and the secondary filter is not more than 0.05 MPa.

5. The pretreatment process for preparing formaldehyde from crude methanol according to claim 4, wherein the pretreatment process comprises the following steps: the number of the primary filter and the secondary filter is 2 in 1 in actual production, and 3 in total.

6. The pretreatment process for preparing formaldehyde from crude methanol according to claim 5, wherein the pretreatment process comprises the following steps: the first-stage filter and the second-stage filter, 3 filters can be switched and regenerated on line, and the normal operation of production is not influenced. Can be regenerated on line, and greatly reduces the time for disassembling and assembling the filter medium and the labor intensity of workers.

7. The pretreatment process for preparing formaldehyde from crude methanol according to claim 1, which is characterized in that: the pressure difference of the inlet and the outlet of each filter of the three-stage filter is not more than 0.05 MPa.

8. The pretreatment process for preparing formaldehyde from crude methanol according to claim 6, which is characterized in that: the three-stage filter is prepared from 1 st filter and 1 st filter in actual production, and 2 filters in total.

Technical Field

The invention relates to the technical field of chemical processes, in particular to a pretreatment process for preparing formaldehyde from crude methanol.

Background

The crude methanol is not further rectified from a methanol synthesis tower, although the crude methanol is simply treated, the crude methanol does not reach the national standard, the crude methanol can be used for preparing refined methanol and can also be used for directly producing formaldehyde, and if the crude methanol is directly used as a raw material for producing the formaldehyde, the operation can be simplified, and the cost is greatly saved.

At present, two main industrial formaldehyde production processes are silver method and iron-molybdenum method, wherein the silver method is mainly adopted by domestic formaldehyde manufacturers, and the iron-molybdenum method is adopted by some manufacturers. The catalyst used in the production of formaldehyde by the silver method is electrolytic silver, and in the gas-solid phase catalytic reaction, the improvement and protection of the activity of the catalyst are important conditions for determining the production process, and in order to protect the catalyst, it is necessary to know the poison which makes the catalyst lose activity. Formaldehyde production is a typical methanol dehydrogenation, oxidation reaction, and has been studied in detail. Reported that CS₂、CHCl₃、H₂S、Cl₂、Br₂Compounds such As P, As, Fe, Hg, Pb are poisons for silver catalysts. In addition, ketone and aldehyde impurities are resinified on a silver catalyst; in addition, it has been shown experimentally that certain poisons promote the reaction at very low concentrations, e.g. CS₂、CHCl₃The dehydrogenation reaction can be accelerated, except for sedimentary poisons; however, iron is well known as a poison for very catalysts.

Based on the sensitive characteristics of the electrolytic silver catalyst and the component analysis of the crude methanol, if the crude methanol is used as a raw material to produce formaldehyde, no matter what method is used, the influence of impurities in the crude methanol on the catalyst must be eliminated, and at least the influence of the impurities in the crude methanol should be reduced as much as possible, otherwise, the ideal effect is difficult to achieve.

Disclosure of Invention

The invention aims to provide a pretreatment process for preparing formaldehyde from crude methanol, which aims to solve the problems of removal of high-carbon alcohol, free acid, ketone, ether, ester, alkane and a small amount of organic amine contained in the crude methanol and influence on a catalyst in the background technology. The method solves the problems of poor activity, easy poisoning, short production period, simple and efficient process of the silver catalyst in the process of preparing formaldehyde from crude methanol, and greatly saves the cost for production enterprises.

In order to achieve the purpose, the invention provides the following technical scheme: comprises a crude methanol preheater, a methanol booster pump, a primary filter, a secondary filter, a tertiary filter and a methanol precision filter. The method comprises the following steps:

(1) the method comprises the following steps that crude methanol from a crude methanol tank area enters a crude methanol preheater, steam is used for indirect heating, and the outlet temperature of the crude methanol preheater is controlled to be 30-50 ℃;

(2) pressurizing the heated crude methanol by a methanol booster pump, and conveying the heated crude methanol into a primary filter, wherein the outlet pressure of the booster pump is 0.6-0.8 MPa;

(3) the crude methanol enters a secondary filter after passing through a primary filter, organic impurities such as oil wax and the like in the crude methanol are filtered, and the pressure difference between the upper part and the lower part of the filter is controlled not to exceed 0.05 MPa;

(4) after passing through the first two-stage filter, the crude methanol enters a third-stage filter, acid impurities in the crude methanol are filtered, and the pressure difference between the upper part and the lower part of the filter is controlled not to exceed 0.05 MPa;

(5) and after passing through the three-stage filter, the methanol solution enters a methanol precision filter, mechanical impurities in the methanol are removed, and then the methanol solution enters the next working section.

Preferably, the crude methanol preheater is a coil heating device, the outlet temperature of the crude methanol preheater is controlled to be 30-50 ℃, and the optimal state of subsequent filtering activity is achieved.

Preferably, the first-stage filter and the second-stage filter adopt a fixed bed, and the built-in filter medium is activated carbon.

Preferably, the primary filter and the secondary filter are carried out in a series connection mode, and 3 filters are 2 filters for one filter.

Preferably, the primary filter and the secondary filter can realize the function of on-line activated carbon regeneration.

Preferably, the three-stage filter adopts a fixed bed, and the built-in filter medium is alkaline resin.

Preferably, the three-stage filter is operated in a one-on-one-standby mode during normal operation.

Preferably, the pressure difference between the upper part and the lower part of the filter is controlled to be not more than 0.05 MPa.

Compared with the prior art, the invention has the beneficial effects that: this kind of crude methyl alcohol system formaldehyde preliminary treatment process adopts level four filter equipment, and after the preliminary treatment, impurity content is showing to descend, and the side reaction product is little to product quality influence, has realized crude methyl alcohol system formaldehyde, and the product reaches the index of premium grade product. The process flow is simplified, the investment cost is greatly reduced, and the utilization rate of raw materials is higher.

Drawings

FIG. 1 is a schematic diagram of the composition of a pretreatment process for preparing formaldehyde from crude methanol.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a technical scheme that: a pretreatment process for preparing formaldehyde from crude methanol comprises the following steps:

(1) the method comprises the following steps that crude methanol from a crude methanol tank area enters a crude methanol preheater, steam is used for indirect heating, and the outlet temperature of the crude methanol preheater is controlled to be 30-50 ℃;

(2) pressurizing the heated crude methanol by a methanol booster pump, and conveying the heated crude methanol into a primary filter, wherein the outlet pressure of the booster pump is 0.6-0.8 MPa;

(3) the crude methanol enters a secondary filter after passing through a primary filter, organic impurities such as oil wax and the like in the crude methanol are filtered, and the pressure difference between the upper part and the lower part of the filter is controlled not to exceed 0.05 MPa;

(4) after passing through the first two-stage filter, the crude methanol enters a third-stage filter, acid impurities in the crude methanol are filtered, and the pressure difference between the upper part and the lower part of the filter is controlled not to exceed 0.05 MPa;

(5) and after passing through the three-stage filter, the methanol solution enters a methanol precision filter, mechanical impurities in the methanol are removed, and then the methanol solution enters the next working section.

Example (b):

(1) crude methanol from a crude methanol tank area enters a crude methanol preheater, and is indirectly heated through steam, and the outlet temperature of the crude methanol preheater is controlled to be 50 ℃;

(2) pressurizing the heated crude methanol by a methanol booster pump, and sending the heated crude methanol into a first-stage filter, wherein the outlet pressure of the booster pump is 0.6 MPa;

(3) the crude methanol enters a secondary filter after passing through a primary filter, organic impurities such as oil wax and the like in the crude methanol are filtered, and the pressure difference between the upper part and the lower part of the filter is controlled not to exceed 0.03 MPa;

(4) after passing through the first two-stage filter, the crude methanol enters a third-stage filter, acidic impurities in the crude methanol are filtered, and the pressure difference between the upper part and the lower part of the filter is controlled not to exceed 0.03 MPa;

(5) and after passing through the three-stage filter, the methanol solution enters a methanol precision filter, mechanical impurities in the methanol are removed, and then the methanol solution enters the next working section.

Wherein the crude methanol preheater is a coil heating device, and the outlet temperature of the crude methanol preheater is controlled to be 50 ℃ so as to achieve the optimal state of subsequent filtering activity; the first-stage filter and the second-stage filter adopt a fixed bed, and the built-in filter medium is activated carbon; the primary filter and the secondary filter are connected in series, and 3 filters are provided for 2; the primary filter and the secondary filter can realize the on-line activated carbon regeneration function; a third-stage filter which adopts a fixed bed and is internally provided with a filter medium which is alkaline resin; the three-stage filter adopts a one-on-one-standby mode in normal operation.

While the invention has been described above with reference to an embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the various features of the embodiments disclosed herein may be used in any combination, provided that there is no structural conflict, and the combinations are not exhaustively described in this specification merely for the sake of brevity and conservation of resources. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.