CN112723563A

CN112723563A - Method for retarding scale formation of wall surface by scale removal water-based surface modifier

Info

Publication number: CN112723563A
Application number: CN202110088293.3A
Authority: CN
Inventors: 常云峰; 常旭东; 刘生海
Original assignee: Tianjin Sigma Innova Technology Co ltd
Current assignee: Tianjin Sigma Innova Technology Co ltd
Priority date: 2021-01-21
Filing date: 2021-01-21
Publication date: 2021-04-30

Abstract

The invention relates to a preparation method of a water-based surface modifier and a method for slowing down the scale formation of the wall surface caused by dirt in water by using the water-based surface modifier. Aims to solve the technical problem that trace amount of recombinant components in reaction products are solidified by cooling in the operation of the existing methanol-to-olefin device, which causes serious scaling of a water system heat exchanger. The technical scheme is as follows: a preparation method of a water-based surface modifier and a method for slowing down the fouling of the wall surface of a water-based surface modifier comprise the following steps: 1) stirring and mixing the surface modifier and purified water; 2) homogenizing; 3) injecting into the treated MTO process water system; a preparation method of a water-based surface modifier comprises the following steps: 1) placing the surface modifier contrast agent in a high-pressure reaction kettle, and adding an acid catalyst; 2) heating step by step; 3) and carrying out programmed cooling to room temperature. The present invention can reduce the adhesion and adherence of fouling particles to the wall surfaces of the contactor, thereby extending the operating cycle of such equipment.

Description

Method for retarding scale formation of wall surface by scale removal water-based surface modifier

Technical Field

The invention relates to a method for using a descaling water-based surface modifier to slow down the scale formation of the wall surface caused by dirt in water.

Background

Wilson, Lok and Flanigan of UCC (Union Carbide corporation) of United states company of United states in 1982 discovered that the microporous solid acid silicoaluminophosphate SAPO-34 molecular sieve has unique high selectivity for preparing low-carbon olefin by methanol conversion, and large-scale industrial technology development and industrial demonstration activities for preparing olefin from methanol are globally developed after ethylene and propylene have unique high selectivity. Finally, by combining the technology of the Chinese academy of sciences with the chemical and physical technology core and the technology development of the Luoyang engineering design institute of China petrochemical company as the core with the high efficiency and complementary advantages of engineering, the commercial operation of the first set of methanol to olefin (DMTO) device in the world is realized by the Baotou of inner Mongolia in China, 60 ten thousand tons of olefin are produced annually, and the successful operation of the project is successful in 2010 and opens up a new route of coal-based petrochemical industry for the coal-based methanol to olefin (CTO), which drives the production of 30 sets of MTO devices up to 2020 and 8 months, wherein the DMTO technology occupies the position, and the SMTO of U.S. UOP company MTO and China petrochemical industry and the SHMTO of Shenhua group are the second. Up to now, all MTO devices use SAPO-34 molecular sieve microsphere particles as catalysts, and use circulating fluidized beds as reactors and regenerators to realize catalyst regeneration and recycling, reaction products are purified and separated through cold section devices such as a quench tower, a water washing tower, a sewage stripping tower, a heat exchanger and the like, catalyst scraps and other high-boiling-point byproducts are removed, and process water is recycled, so that unnecessary discharge or post-treatment of process water is reduced, and zero emission of the overall MTO process is realized by combining a sewage treatment plant. Although the MTO process has been operated for a long period of 18-28 months, such long period of operation requires extensive process intervention and the use of repetitive hardware units, including the relatively frequent off-line cleaning of the heat exchanger and the on-line cleaning of the water scrubber with the injection of organic solvents, which results in the overall process being compromised in economic efficiency, increased burden on the environmental protection of the post-treatment, and increased potential safety hazards in operating operations. The purpose of the use of organic solvents, off-line high pressure cleaning, is to remove fouling materials that will adhere to the surfaces of the piping, heat exchangers, and the surfaces of the column and trays. These contaminants include catalyst fines, organic particles. During the operation of the industrial device for preparing olefin from methanol, trace recombinant in reaction products can be solidified in a low-temperature region of washing water, so that a heat exchanger of a water system (washing water) is seriously scaled, and the heat exchange efficiency of a heat exchange device is reduced. In order to ensure the stable operation of the device, the heat exchanger needs to be cleaned off line, so that the production cost is increased, and the hidden danger is formed on the stable operation of the device.

Disclosure of Invention

The invention aims to solve the technical problems that trace recombinant components in reaction products are solidified in a low-temperature region of washing water during operation of the existing industrial device for preparing olefin from methanol, so that a heat exchanger of a water system is seriously scaled and the heat exchange efficiency of a heat exchange device is reduced, and provides a method for retarding scaling of scale on the wall surface of a device by using a scale-removing water-based surface modifier.

In order to solve the technical problems, the invention adopts the technical scheme that:

a method for reducing fouling of a wall surface by scale removal of an aqueous surface modifier, comprising the steps of:

1) stirring and mixing the water-based surface modifier and purified water by using a stirrer at room temperature to obtain a water-based mixture with the water-based surface modifier content of 5-45%;

2) homogenizing the water-based mixture obtained in the step 1), and heating to obtain a descaling surface modifier;

3) and injecting the descaling surface modifier obtained by treatment into the treated methanol-to-olefin process water system by using a liquid conveying device to treat the wall surface scale, wherein the treatment temperature of the surface modifier on the wall surface scale in the process water system is 20-175 ℃.

Further, the stirrer used in the step 1) is an impeller type stirrer or a stirring and dispersing device with high shearing capacity, the stirring speed v is more than or equal to 30rpm, and the stirring time h is₁Is 3min/m³≤h₁≤20min/m³；

The time h of the homogenization treatment in the step 2)₂Comprises the following steps: 2min/m³≤h₂≤10min/m³(ii) a The heating temperature W is: w is more than or equal to 15 ℃ and less than or equal to 75 ℃, and a coil is selected for heat extraction or heat supply;

the liquid conveying device in the step 3) is a high-pressure diaphragm pump or a liquid conveying device capable of realizing accurate metering and stable conveying;

the injection speed of the liquid is as follows: v is more than or equal to 2.5 kg/h and less than or equal to 110 kg/h;

the injection points of the liquid are: the upper part of the washing tower returns to the tower pipeline and is positioned at the pipeline within 15 meters downstream of the neutralization alkali injection point;

the final addition concentration rho of the descaling surface modifier is as follows: rho is not less than 12.5ppm and not more than 750 ppm.

Further, the water-based surface modifier comprises three of ZAFA-B, ZAFA-D and ZAFA-F.

Further, the preparation method of the ZAFA-B comprises the following steps:

1) placing 20 g of the surface modifier contrast agent A into a high-pressure reaction kettle, and adding 5mg of the acid catalyst A-1;

2) heating from room temperature to 65 deg.C at a speed of 2.0 deg.C/min, maintaining at the temperature for 10min, heating to 120 deg.C at a speed of 1.5 deg.C/min, keeping the temperature for 15 min, heating to 177 deg.C at a speed of 1.0 deg.C/min, and treating at the highest temperature for 3-48 hr;

3) after heating, cooling from 177 ℃ to room temperature at a speed of 1.0 ℃/min per minute, cooling to room temperature, opening the kettle and taking out the modified product, wherein the treatment temperature of the surface modifier for scaling on the wall surface of the process water system is 20-175 ℃.

Further, the chemical composition of the surface modifier contrast agent a in the step 1) is that the carbon-oxygen atom ratio is 3.7, the hydrogen-oxygen atom ratio is 7.1, the ratio of other hetero atoms to oxygen atoms is less than 0.01, and the chemical formula is as follows: c_3.7H_7.1OX_0.01Wherein X is a non-metal element except carbon, hydrogen and oxygen: nitrogen, phosphorus and sulfur;

the acid catalyst A-1 in the step 1) is a mixed aqueous solution containing 9.5% of hydrochloric acid and 0.5% of acetic acid.

Further, the preparation steps of the ZAFA-D are as follows:

1) placing 60 g of surface modifier contrast agent C in a high-pressure reaction kettle, and adding 4.5 mg of acid catalyst A-2;

2) heating from room temperature to 65 deg.C at 2.0 deg.C/min, maintaining at the temperature for 10min, heating to 115 deg.C at 1.5 deg.C/min, maintaining at the constant temperature for 12 min, heating to 160 deg.C at 1.0 deg.C/min, and treating at the highest temperature for 3-48 hr;

3) after heating, cooling from 160 ℃ to room temperature at the speed of 1.0 ℃/min, cooling to room temperature, opening the modified product and taking out.

Further, the acid catalyst A-2 in the step 1) is a mixed aqueous solution containing 4.7% of hydrochloric acid and 0.5% of phosphoric acid;

further, the preparation steps of the ZAFA-F are as follows:

1) 1200 kg of surface modifier contrast agent C is placed in a high-pressure reaction kettle with the size of 2 cubic meters, and 115 g of acid catalyst A-3 is added;

2) heating from room temperature to 65 ℃ at the speed of 2.0 ℃/min, keeping the temperature for 10 minutes, heating to 115 ℃ at the speed of 1.5 ℃/min, keeping the temperature for 12 minutes, finally heating to 130 ℃ at the speed of 1.0 ℃/min, keeping the temperature for 90 minutes, and carrying out the whole process under a closed system;

3) after heating, cooling from 130 ℃ to room temperature at the speed of 1.0 ℃/min, cooling to room temperature, opening the kettle of the modified product and taking out.

Further, the chemical composition of the surface modifier contrast agent C in the step 1) is 2.92 of carbon-oxygen atom ratio, 6.23 of hydrogen-oxygen atom ratio, 0.02 of other heteroatom-to-oxygen atom ratio, and the chemical formula is as follows: c_2.92H_6.23OX_0.02Wherein X is a non-metal element except carbon, hydrogen and oxygen: nitrogen, phosphorus and sulfur;

the acid catalyst A-3 in the step 1) is a mixed aqueous solution containing 4.7% of hydrochloric acid and 0.5% of nitric acid.

Furthermore, the water-based surface modifier is a water-based weak ion substance, has negative charges in a water-based system with the pH value of more than or equal to 4.5, and has an isoelectric point IEP of less than or equal to 3.5;

the isoelectric point reduction value of the water-based surface modifier to dirt in process water is as follows: delta IEP is more than or equal to 0.1 and less than or equal to 0.8.

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

1. the water-based surface modifier ZAFA adopted by the invention can reduce the adhesion and adhesion of dirt particles on the wall surface of a contact device, thereby prolonging the operation period of the equipment. At ZAFA usage levels between 12.5ppm and 750ppm, the heat exchanger life cycle can be extended by at least 20%, and even 100%, and up to 500%, i.e., from 14 days to 17 days, and even 28 days, and up to 70 days.

2. The invention can greatly prolong the operation period of unit devices such as a heat exchange device, a washing tower, a sewage stripping tower and the like through which process water passes, reduce the risk of MTO overall protective shutdown caused by out-of-control system temperature control or overhigh system pressure drop, and reduce the direct cost and the operation risk of the off-line manual cleaning and maintenance of equipment.

Drawings

FIG. 1 is a graph comparing the thermal stability results of comparative example A and the surface modifiers B-180-3, B-180-18, B-180-24 obtained by subjecting it to catalytic modification treatment;

FIG. 2 is a graph comparing the thermal stability results of comparative example C with those of the surface modifiers D-160-3, D-160-18, D-160-24 obtained by subjecting it to catalytic modification treatment;

FIG. 3 is the result OF infrared spectroscopic analysis OF contaminant OF-1 on the surface OF a MTO heat exchanger E1205C/D tube bundle;

FIG. 4 is a scanning electron micrograph OF OF-1 fouling on the surface OF a tube bundle OF the E1205C/D heat exchanger;

FIG. 5 shows MTO organic soil dispersion results for comparative example surface modifier BACH-010;

FIG. 6 shows the results of surface potential analysis of ZAFA-B surface modifier with isoelectric point of 2.1;

FIG. 7 shows the results of surface potential analysis of the surface modifier ZAFA-D, which has an isoelectric point of 2.8;

FIG. 8 is the surface modification ability results of the surface modifier ZAFA-B;

FIG. 9 is the results of surface potential analysis of MTO process water scale particles prior to surface modification without ZAFA-B; the isoelectric point is 6.4;

FIG. 10 is the results of surface potential analysis of MTO process water modified with ZAFA-B surface modifier;

FIG. 11 is the results of ZAFA-B surface modifier dispersion on MTO organic foulants;

FIG. 12 is a graph comparing the stability of Levima MTO soil particles before and after ZAFA-B modification;

FIG. 13 is a Raman spectrum of fouling materials from Levima MTO process water without ZAFA surface modification;

FIG. 14 is a Raman spectrum of a Levima MTO process water fouling system modified with ZAFA-D;

FIG. 15 shows the results of ZAFA-F in an industrial setting;

FIG. 16 is a photomicrograph of Levima MTO process soil particles before ZAFA-B modification;

FIG. 17 is a photomicrograph of a Levima MTO process soil particles after ZAFA-B modification;

FIG. 18 shows the OF-1 modified dispersion results OF surface modifier ZAFA-F-130-1.5 on MTO organic fouling.

Detailed Description

The invention is further illustrated by the following figures and examples.

Example 1:

in this embodiment, a method for reducing fouling of a wall surface by fouling in water with a water-based surface modifier includes the following steps:

1) stirring and mixing the water-based surface modifier and purified water by using a stirrer at room temperature to obtain a water-based mixture with the water-based surface modifier content of 5%; the stirrer used is an impeller stirrer, the stirring speed is 50rpm, and the stirring time h₁Is 10min/m³；

2) Homogenizing the water-based mixture obtained in the step 1), and heating to obtain a descaling surface modifier; time h of the homogenization treatment₂Comprises the following steps: 5min/m³(ii) a The heating temperature W is: heating at 25 deg.C with coiled pipe;

3) and injecting the descaling surface modifier obtained by treatment into the treated methanol-to-olefin process water system by using a liquid conveying device to treat the wall surface scale, wherein the treatment temperature of the surface modifier on the wall surface scale in the process water system is 20 ℃.

The liquid conveying device is a high-pressure diaphragm pump; the injection speed of the liquid is as follows: 10-60 kg/h;

the injection points of the liquid are: the upper part of the washing tower returns to the tower pipeline and is positioned at the pipeline within 15 meters downstream of the neutralization alkali injection point; the final addition concentration rho of the descaling surface modifier is as follows: 268 ppm.

The water-based surface modifier is ZAFA-B, and the preparation method comprises the following steps: placing 20 g of the surface modifier contrast agent A into a high-pressure reaction kettle, and adding 5mg of the acid catalyst A-1; heating from room temperature to 65 deg.C at a speed of 2.0 deg.C/min, maintaining at the temperature for 10min, heating to 120 deg.C at a speed of 1.5 deg.C/min, keeping the temperature for 15 min, heating to 177 deg.C at a speed of 1.0 deg.C/min, keeping the temperature for 180 min, and sealing; after the reaction is finished, carrying out programmed cooling, cooling at the speed of 1.0 ℃/min per minute from 177 ℃ to room temperature, cooling to room temperature, opening the modified product, taking out the modified product, marking as B-180-3, wherein the B-180-18 is a product which is heated to 177 ℃ and then is subjected to constant temperature treatment for 18 hours; b-180-24 is a product which is heated to 177 ℃ and then subjected to constant temperature treatment for 24 hours, and the product used in the example is B-180-3.

The water-based surface modifier can also be a water-based mixture with any value between 5 and 45 percent;

the acid catalyst A-1 is a mixed aqueous solution containing 9.5% of hydrochloric acid and 0.5% of acetic acid;

the treatment temperature of the surface modifier for the wall surface scale in the process water system can be any temperature between 20 and 175 ℃;

the stirring speed can be any value more than or equal to 30rpm, and the stirring time can be more than or equal to 3 h₁≤20min/m³At any value in between, the time of the homogenization treatment is more than or equal to 2 and less than or equal to h₂≤10min/m³The heating temperature can be any value between 15 and 75 ℃, and the injection speed of the liquid can be any value between 2.5 and 110 kg/h; the final addition concentration of the descaling surface modifier can be any value between rho and 750ppm, wherein the rho is more than or equal to 12.5;

the constant temperature treatment time at the maximum temperature in step 2) in the preparation method of ZAFA-B can be any value between 3 and 48 hours.

The impeller type stirrer can also be replaced by a stirring and dispersing device with high shearing capacity; the coil pipe can be used for heat taking instead of heat supply; the high-pressure diaphragm pump can also be replaced by a liquid conveying device which can realize accurate metering and stable conveying.

The chemical composition of the surface modifier contrast agent A is that the carbon-oxygen atom ratio is 3.7, the hydrogen-oxygen atom ratio is 7.1, the ratio of other heteroatoms to oxygen atoms is less than 0.01, and the chemical formula is as follows: c_3.7H_7.1OX_0.01Wherein X is a non-metal element except carbon, hydrogen and oxygen, and is usually nitrogen, phosphorus and sulfur. The TSI characteristics of surface modified contrast agent A are shown in FIG. 1, which is most typically characterized by a characteristic peak at 258 ℃ with the higher temperature peak being weaker, especially for materials above 400 ℃ being only about 0.2.

As shown in figure 1, the temperature of the characteristic peak of the product is increased from 258 ℃ of the raw material to nearly 400 ℃, even to be ultrahigh by 400 ℃, so that the high-temperature environment with harsh dirt treatment process can be met.

To verify the effectiveness of the water-based surface modifier ZAFA-B prepared in this example on MTO scale treatment, the following tests were performed.

1. Surface potential measurement

The surface potential measurement of the water-based surface modifier ZAFA-B is shown in FIG. 6, which indicates that the water-based surface modifier is a weakly anionic surface modifier. At a pH above 3, the water-based surface modifier is negatively charged.

It is fully proved that ZAFA-B has obvious effect on the surface modification of MTO process water containing organic dirt, and the surface tension of the system is reduced by at least 1.5 percent and even more than 23 percent.

The results of the surface potential measurements of MTO foulants subjected to ZAFA-B surface modification before the ZAFA-B modification are shown in FIG. 9.

ZAFA-B surface modifier was added to 200 ml of process water (containing scale).

FIG. 10 is a surface potential result of MTO scale modified with 100ppm ZAFA-B, showing that the scale surface is negatively charged when the system is acid-base neutral and positively charged in the acidic case, and the acid-base of the wash water is controlled to be neutral or slightly basic according to DMTO process design and process control requirements, thus the scale surface is negatively charged under the operating conditions;

the comparison of the results in FIG. 9 and FIG. 10 shows that the surface potential modification of the MTO scale by ZAFA-B is not obvious, and the change of the characteristic isoelectric point before and after the addition of ZAFA-B is small. Therefore, ZAFA-B is not a charge-modifying surface modifier.

2. Turbidity measurement

Organic fouling OF-1 was dispersed using ZAFA-B. 200 ml OF MTO process water is taken, 1 g OF OF-1 dirt is added into the MTO process water, a certain amount OF surface modifier ZAFA-B is added into the MTO process water, the system is stirred strongly so as to realize the dispersion OF-1, and the dispersion effect is measured by turbidity measurement, and the result is shown in figure 11.

The results in fig. 11 show that even at very low ZAFA-B addition doses, a greater degree of soil dispersion has been obtained. Compared with the inorganic surface modifier BACH-010 (figure 5), the MTO dirt dispersion is obviously improved, and the turbidity is improved by 7-8 times. MTO foulant OF-1 was effectively dispersed by the ZAFA-B surface modifier.

The use of ZAFA-B not only dispersed MTO scale but also improved the scale stability after dispersion, i.e., improved the rate of scale settling, and fig. 12 shows that the scale particle size settled before surface modifier treatment, resulting in poor system stability, and the system stability index (RSI) decreased from 100% initially to less than 79% in 90 minutes. Stability measurements were made on the stability of the system by adding 100ppm ZAFA-B to the MTO process water and the results are shown in FIG. 12. The result shows that the system stability is obviously improved after ZAFA-B modification, the system stability index RSI usually exceeds 80%, the stability is generally considered to be good, the RSI exceeds 90%, and the system stability is superior. 100ppm ZAFA-B modified MTO foulant RSI was close to 92%.

3. Testing of surface modification Properties

The results of the surface modification performance of the water-based surface modifier ZAFA-B on MTO process water are shown in FIG. 8, and show that the surface tension of the MTO process water can be obviously reduced from 71.6mN/m to 24.8 mN/m. The higher the ZAFA-B content, the greater the reduction in surface tension.

The fouling of the surface of the wall of the process water of the DMTO apparatus with an annual methanol throughput of 138 ten thousand tons is treated by the prepared descaling surface modifier: the total pressure of the water washing tower fluctuates between 36.5kPa and 37.5kPa before ZAFA-B injection, the pressure is that the tower return amount is between 145 tons/h and 155 tons/h, and the tower return amount is much lower than the tower return amount of 360 tons/h in the initial period of starting the system. The amount of tower return is still further reduced with the risk of causing a loss of control of the system and even a protective on-line shutdown of the system. In this case, the system is faced with opening the water wash tower for dirt cleaning. Injecting the ZAFA-B surface modifier into a tower return pipeline on the water washing tower by a high-pressure diaphragm metering pump. The injection dosage of ZAFA-B is adjusted according to the content of suspended matters (dirt) in the process water and the amount of external drainage. The suspended matter content of the process water is 167 mg/L, the discharged water amount is 168 tons/h, the pressure change result of the system is shown in figure 15, the large-amplitude sudden pressure drop of the system is caused by the large-amplitude reduction of the system load, the dotted line is marked as the pressure change condition of the system load at the same level, after the ZAFA-B injection for nearly 170 hours, the total pressure of the system is reduced from 36.5kPa to 32.5kPa under the operation condition that the ZAFA-B dose is kept at 45 kg/h or the concentration is 268ppm, so that the system pressure is obviously relieved, and the dirt of the surface system is stripped and discharged to a large extent. During the period, the instantaneous concentration of the fouling of the discharged water is as high as 720NTU, and the fouling control effectiveness of ZAFA-B is fully reflected.

The Chemical Oxygen Demand (COD) of the process effluent of a DMTO plant with an annual methanol throughput of 138 million tons was 657mg/L prior to ZAFA modification treatment.

The COD of the system after 70 hours treatment with 45 kg/hr ZAFA-B added to the system showed a negligible contribution to COD at a dose of 268ppm ZAFA-B.

Example 2:

the chemical composition of the surface modifier contrast agent C in this example is 2.92 carbon to oxygen atomic ratio, 6.23 hydrogen to oxygen atomic ratio, and 0.02 other heteroatom to oxygen atomic ratio, and its chemical formula is: c_2.92H_6.23OX_0.02Wherein X is a non-metal element except carbon, hydrogen and oxygen, and is usually nitrogen, phosphorus and sulfur. The TSI characteristics of comparative surface modifier C are shown in FIG. 2, which is most typically characterized by a characteristic peak at 254 deg.C, with the high temperature peak being weaker, especially below 0.1 for materials above 400 deg.C.

The preparation method of ZAFA-D comprises the following steps of putting 60 g of surface modifier contrast agent C into a high-pressure reaction kettle, and adding 4.5 mg of acid catalyst A-2; carrying out temperature programming heating treatment at 160 ℃, heating from room temperature to 65 ℃ at the speed of 2.0 ℃/min, keeping the temperature for 10 minutes, heating to 115 ℃ at the speed of 1.5 ℃/min, keeping the temperature for 12 minutes, finally heating to 160 ℃ at the speed of 1.0 ℃/min, keeping the temperature for 180 minutes, and carrying out the whole process under a closed system; after the reaction is finished, carrying out programmed cooling, cooling at the speed of 1.0 ℃/min from 160 ℃ to room temperature, cooling to room temperature, opening the modified product, taking out, and marking as D-180-3; in addition, D-180-18 and D-180-24 are products treated at the final temperature for 18 hours and 24 hours, respectively, and the three products used in the example are compared.

The acid catalyst A-2 is a mixed aqueous solution containing 4.7% of hydrochloric acid and 0.5% of phosphoric acid;

the corresponding thermal stability measurements are shown in FIG. 2. As can be seen from fig. 2, the thermal stability of the surface modifier contrast agent C was significantly improved after the catalytic heat treatment. The characteristic peak corresponds to a temperature increase from the original 254 ℃ C (comparative example C) to 366 ℃ C (D-180-3) or even up to 425 ℃ C (D-180-18). However, the catalytic treatment was continued for 24 hours, and the peak of the highest temperature disappeared, indicating that the catalytic treatment was not favorable for a long time.

The surface potential measurement of the water-based surface modifier ZAFA-D is shown in FIG. 7, which indicates that the surface modifier is also a weakly anionic surface modifier. At a pH above 3, the surface modifying agent is negatively charged.

ZAFA-D surface modification treatment was carried out on OF-2, which is fouling OF process water from a DMTO plant (plant-C) having an annual methanol throughput OF 138 ten thousand tons. The microscopic results of the fouling particles without ZAFA-D modification are shown in FIG. 16 where the fouling particles are large (20-25 microns) and have sharp organic morphology, with the catalyst fines being less distinctive.

ZAFA-D was added to MTO process water containing 167ppm OF-2 in an amount OF 105ppm, and injected in the same manner as in example 1. Observation with an optical microscope showed in FIG. 17, which shows that no large agglomerated particles were observed, and only uniform small particles OF 1-3 μm were observed, indicating that 105ppm ZAFA-D was sufficient to achieve effective dispersion OF OF-2, which further demonstrates the effective surface modification and dispersion OF MTO organic fouling by ZAFA-D.

The results of the raman spectroscopy analysis of the process water containing MTO foulant are shown in fig. 13. 150ppm ZAFA-D surface modifier is added into the process water, and the modified system is subjected to Raman spectrum analysis. The Raman spectrum analysis result of the system after the ZAFA-D surface modification is shown in FIG. 14, and the result of FIG. 14 shows that the addition of the ZAFA-D generates stronger 2420-^-1And 1120 + 1240cm^-1Raman absorption peaks generated by the interaction of ZAFA-D and dirt, and Raman spectrum analysis results show that the addition of the ZAFA-D surface modifier generates characteristic Raman absorption peaks, which proves that MTO dirt is obviously modified and dispersed.

The water-based surface modifiers ZAFA-B and ZAFA-D of the invention are prepared by using a surface modifier with multi-MTO organic dirt, and reducing the surface tension of the system to enable the dirt to be stripped and dispersed from the surfaces of a tower tray of a washing tower, the tower wall, the outer pipe wall of a heat exchanger and the pipeline surface to be carried out in process water to be carried out of the system, thereby reducing the further adhesion of the dirt in the process water from a reverse recycling system, effectively relieving the pressure of the system and playing a positive role in the long-time and high-load operation of an MTO device.

Example 3:

The ZAFA-F is prepared by placing 1200 kg of surface modifier contrast agent C in a high-pressure reaction kettle with the size of 2 cubic meters, and adding 115 g of acid catalyst A-3; carrying out temperature programming heating treatment at 130 ℃, heating from room temperature to 65 ℃ at the speed of 2.0 ℃/min, keeping the temperature for 10 minutes, heating to 115 ℃ at the speed of 1.5 ℃/min, keeping the temperature for 12 minutes, finally heating to 130 ℃ at the speed of 1.0 ℃/min, keeping the temperature for 90 minutes, and carrying out the whole process under a closed system; and (3) carrying out programmed cooling after the reaction is finished, cooling at the speed of 1.0 ℃/min from 130 ℃ to room temperature, cooling to room temperature, opening the kettle of the modified product, and taking out the modified product, wherein the label is F-130-1.5.

Using a surface modifier F-130-1.5 for dispersing organic fouling OF-1, and taking 9850 kilograms OF MTO process water; putting the mixture into a stirring kettle of 2 cubic meters, wherein the system temperature is 27.8 ℃, and the stirring paddle speed is 75 RPM; 5.18 kg OF-1 was dispersed in the above MTO process water, the amount OF OF-1 dispersion was determined by the turbidity OF the mixed system, and the amount OF dispersion was measured after stirring and dispersing for 30 minutes, as shown in FIG. 18. The amount of dispersion without surface modifier was negligible and was close to 0 ppm.

10ppm ZAFA-F-130-1.5 was added to the system, the ZAFA-F was injected in the same manner as in example 1, stirred for 15 minutes, and the product was collected for turbidity measurement, and the results are shown in FIG. 18. The dispersion result is the second point from the left in the figure. The addition OF surface modifier was continued in this system to obtain dispersion test results OF 300ppm and 50000ppm ZAFA-F-130-1.5 addition OF OF-1, as shown in the third and fourth points OF FIG. 18 (upper right corner OF FIG. 18).

The results in FIG. 18 show that as the amount of the modifier ZAFA-F-130-1.5 is increased, the amount of organic scale decomposition increases, thus it can be seen that ZAFA-F-130-1.5 is an effective MTO organic scale dispersion modifier. The material analysis and test method comprises the following steps:

1. the thermal stability of a surface modifier material is measured as the Thermal Stability Index (TSI), which is measured using a surface modifier specific thermal stability test apparatus (TSEA). The surface modifier is mixed with a dispersion medium such as: water or modifying objects such as: mixing process water, heating the process water to simulate the operating conditions of the using process: temperature, pressure and gas-liquid flow rate, the measured values being the consumption of the surface modifier under certain modification conditions, the lower the consumption, the higher the TSI thermal stability of the surface modifier. If the surface modifier is not stable under such conditions and is decomposed or denatured, its effectiveness is reduced, which is also reflected by low surface modification activity, poor thermal stability, and shift of TSI to low temperatures. The heating can be performed by adopting a constant-temperature oil bath, a fluidized bed sand bath or a heating furnace, or infrared heating, the temperature is usually 40 ℃ to 750 ℃, and the TSI spectrogram of the thermal stability index of the surface modifier is a graph of the variation of the surface modifier to the temperature.

2. The potential measurement is carried out by adopting a Zetasizer Nano-NS of the British Marvin instrument company or a Zetapals particle size and surface potential analyzer of the American Bruk Highen instrument company, dispersed water sample products are put into a product pool for relevant measurement, the concentration of the products is controlled below 5 percent according to the size and the refraction factor of the product particles, and the particle size of the analyzable products is from 1 nanometer to 700 micrometers.

3. Specific surface area and pore size analysis of solid products was performed on a specific surface area analyzer of ASAP-2020, Micromerics, USA, by degassing 20-60 mg of the product using a Micromerics V60 degassing station purge type degassing, the degassing process being divided into two stages: namely, 30ml/min of nitrogen is used for purging for 30 minutes at room temperature; then, after the temperature was raised to 350 ℃, nitrogen gas of 30ml/min was purged for 2 hours. The degassed product was subjected to nitrogen adsorption at liquid nitrogen temperature to obtain BET specific surface area results.

4. The turbidity measurement of the aquatic product is carried out at room temperature by adopting a 2100AN turbidimeter of Hach company in America and calibrating the instrument by using a plurality of standards of 5-1000NTU of Hach company.

5. Scanning electron microscope imaging and element analysis are carried out on a TM-1000 scanning electron microscope of Hitachi instruments, Japan, the product is sprayed with gold by adopting an SC-5 automatic atomic high-resolution sputtering coating instrument of Pelco in America so as to improve the imaging effect of the product, and the TM-1000 is provided with an EDS element detector which can detect and semi-quantify most inorganic elements.

6. Optical microscopic observation was performed using an Olympus CH optical microscope, Japan.

7. Infrared spectroscopic analysis of the product was carried out on a Tensor 27 red infrared spectrometer from Bruker instruments, Germany, and the infrared analysis of solid products was usually carried out on a GladiATR on-line heated total reflectance product bench from PIKE instruments, USA.

8. Product Raman spectrum analysis adopts a DXR Raman microscope spectrometer of U.S. Thermo to carry out product imaging and Raman analysis, and the analysis range is 400-4000cm^-1The product is usually applied directly or the liquid product is dropped onto a special optical microscope slide, if no powder is scattered directly onto the product slide.

9. The pH of the water samples was measured using a 420A + pH meter from Thermo Orion instruments, USA, equipped with an automatic temperature compensated pH probe, and the test was performed at room temperature.

10. The surface tension was measured using a Proline t15 dynamic surface tensiometer from SITA instruments, Germany.

Comparative example 1

The number of the washing tower water-washing heat exchange devices E1204 and E1205 of the methanol-to-olefin (MTO) device for producing 63 million tons of olefins every year are 12. Wherein, the E1205 heat exchangers have four groups, and each group has two; e1204 four groups, one for each group. When the heat exchanger is started, no dirt is on the surface of the heat exchanger, and the heat exchange efficiency is highest. When the process water enters the heat exchanger E1205, the temperature (inlet temperature) is 58 ℃, the temperature (outlet temperature) is reduced to 35 ℃ after heat is taken by the heat exchanger, and the maximum temperature difference reaches 23 ℃. After 35 days, the outlet temperature was only 16 ℃ after heat removal through the heat exchanger at the same inlet temperature (58 ℃) as the heat exchanger was used for a longer period of time. This temperature difference is already close to the critical temperature difference of 15 c for cleaning. The scale of the system is urgently needed to be removed, the heat exchange efficiency is improved, and the temperature of the system is at least reduced to below 40 ℃.

The method comprises the steps OF firstly taking the heat exchanger OF the E1205C/D group off line, manually cleaning the heat exchanger, and sampling fouling substances attached to a heat exchanger tube bundle with serious fouling during cleaning, wherein the product is marked as OF-1. The heat exchange core OF E1205C/D is drawn out, and the observation shows that the thickness OF the OF-1 layer on the surface OF the heat exchanger tube bundle is as high as 3-4 mm, so that the heat exchange efficiency OF the heat exchanger is seriously reduced by the thick organic dirt, and the effective heat exchange efficiency OF the heat exchanger is reduced by 87.5 percent.

FIG. 3 shows the results OF infrared spectroscopic analysis OF MTO organic fouling OF-1. The infrared spectrum data acquisition is carried out by adopting an ATR spectrogram acquisition accessory of a Tensor 27 infrared spectrometer of Bruker instruments Germany. The results indicate that the organics are predominantly saturated and unsaturated hydrocarbons rather than polycyclic aromatic hydrocarbons, consistent with what is commonly known as "wax".

FIG. 4 is a scanning electron micrograph OF MTO organic foulant OF-1 showing few dark inorganic particles further evidencing organic fouling;

as can be seen from the scanning electron micrograph OF the fouling material OF-1 in fig. 4, the morphology OF the fouling material OF-1 does not have any sign OF catalyst particles, but is a typical amorphous organic solid, and in view OF the high melting point OF the material, the organic matter is solidified on the surface OF the heat exchanger tube bundle at a temperature below 65 ℃ to form a "coating" with an extremely low thermal conductivity coefficient, which leads to the reduction OF the heat exchange efficiency OF the cold exchange equipment.

The OF-1 is dispersed by using an inorganic surface modifier BACH-010 (environmental protection science and technology, Inc. OF Fukediwa (Tianjin)). 200 ml OF MTO process water is taken, 1 g OF OF-1 dirt is added into the MTO process water, a certain amount OF surface modifier BACH-010 is added into the MTO process water, and the system is stirred strongly so as to realize the dispersion OF OF-1. The addition of the surface modifier BACH-010 is from 500ppm to 50%, and the dispersion effect is measured by visual inspection and turbidity; the dispersion OF OF-1 can cause the turbidity OF the water system to increase, and in view OF the darker color OF the OF-1 fouling, under the condition OF obvious effect, the change OF the turbidity can be measured by visual inspection, the dispersion OF the fouling can be quantitatively measured, and the turbidity OF the process water product can be measured after 120 minutes OF continuous stirring and dispersion. The results are shown in FIG. 5, and the results in FIG. 5 show that the dispersion effect OF inorganic surface-modified BACH-010 on OF-1 is insignificant, and the change in turbidity OF the modified system is small.

Claims

1. A method for reducing scale formation on the wall surface of a vessel by scale removal of a water-based surface modifier, comprising the steps of:

2. The method of claim 1 for mitigating fouling of a wall surface by a water-based surface modifier, wherein: the stirrer used in the step 1) is an impeller type stirrer or a stirring and dispersing device with high shearing capacity, the stirring speed v is more than or equal to 30rpm, and the stirring time h₁Is 3min/m³≤h₁≤20min/m³；

3. The method of any of claims 1-2, wherein the water-based surface modifier comprises three of ZAFA-B, ZAFA-D and ZAFA-F.

4. The method of claim 3, wherein the ZAFA-B is prepared by the method steps of:

3) and after heating, cooling from 177 ℃ to room temperature at the speed of 1.0 ℃/min per minute, cooling to room temperature, opening the kettle of the modified product, and taking out.

5. The method according to claim 4, wherein the chemical composition of the surface modifier contrast agent A in the step 1) is 3.7 carbon to oxygen atomic ratio, 7.1 hydrogen to oxygen atomic ratio, and the ratio of other hetero atoms to oxygen atomic ratio is less than 0.01, and the chemical formula is as follows: c_3.7H_7.1OX_0.01Wherein X is a non-metal element except carbon, hydrogen and oxygen: nitrogen, phosphorus and sulfur;

6. The method of claim 3, wherein the ZAFA-D is prepared by:

7. The method according to claim 3, characterized in that the preparation steps of ZAFA-F are:

8. The method of claim 6, wherein the chemical composition of the surface modifier contrast agent C in step 1) is 2.92 carbon to oxygen atoms, 6.23 hydrogen to oxygen atoms, and 0.02 other heteroatom to oxygen atoms, and has the chemical formula: c_2.92H_6.23OX_0.02Wherein X is a non-metal element except carbon, hydrogen and oxygen: nitrogen, phosphorus and sulfur;

the acid catalyst A-2 in the step 1) is a mixed aqueous solution containing 4.7% of hydrochloric acid and 0.5% of phosphoric acid.

9. The method according to claim 7, wherein the acid catalyst A-3 in the step 1) is a mixed aqueous solution containing 4.7% of hydrochloric acid and 0.5% of nitric acid.

10. The method of claim 3, wherein the water-based surface modifier is a water-based weakly ionic substance having a negative charge in a water-based system at a pH of 4.5 or more and an isoelectric point IEP of 3.5 or less;