CN114790061A - Method for reducing formic acid in formaldehyde recovery system - Google Patents
Method for reducing formic acid in formaldehyde recovery system Download PDFInfo
- Publication number
- CN114790061A CN114790061A CN202210440430.XA CN202210440430A CN114790061A CN 114790061 A CN114790061 A CN 114790061A CN 202210440430 A CN202210440430 A CN 202210440430A CN 114790061 A CN114790061 A CN 114790061A
- Authority
- CN
- China
- Prior art keywords
- formaldehyde
- tower
- wastewater
- formic acid
- alkali liquor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/81—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C45/82—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/85—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to a chemical modification
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/34—Organic compounds containing oxygen
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/06—Controlling or monitoring parameters in water treatment pH
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Removal Of Specific Substances (AREA)
Abstract
The invention discloses a method for reducing formic acid in a formaldehyde recovery system, which comprises the following steps: mixing the alkali liquor with the wastewater in the wastewater storage tank to obtain dilute alkali liquor; mixing dilute alkali liquor with the formaldehyde-containing wastewater through an online static mixer, feeding the mixture into a feed tank of a formaldehyde recovery tower, neutralizing formic acid in the formaldehyde-containing wastewater by using the dilute alkali liquor, and controlling the pH value to be 6.5-7; preheating the deacidified wastewater containing formaldehyde by a preheater, and then feeding the preheated wastewater into a formaldehyde recovery tower for rectification; adding alkali liquor into a tower kettle of the formaldehyde recovery tower, and neutralizing formic acid in tower kettle liquid by using the alkali liquor; the top gas of the formaldehyde recovery tower enters a reflux tank after being cooled, and after being sampled and analyzed to be qualified, the top gas enters a reflux tank according to a reflux ratio of 1.4: 1, one part of the formaldehyde enters the top of a formaldehyde recovery tower to be used as reflux, and the other part of the formaldehyde enters a crude aldehyde storage tank; and a part of the tower bottom liquid of the formaldehyde recovery tower is heated and then circularly refluxed, and a part of the tower bottom liquid exchanges heat with the formaldehyde-containing wastewater subjected to deacidification and then enters a wastewater tank. The invention can effectively reduce the content of formic acid in the formaldehyde recovery system, reduce the corrosion of equipment and pipelines, prolong the service life and improve the quality of recovered formaldehyde.
Description
Technical Field
The invention relates to a method for reducing formic acid, in particular to a method for reducing formic acid in a formaldehyde recovery system.
Background
A formaldehyde recovery system in the polyformaldehyde production device is mainly used for recovering formaldehyde in formaldehyde-containing wastewater of each section, and a recovered formaldehyde solution with the concentration of about 35% is stored in a crude formaldehyde storage tank and then enters a trioxymethylene and dioxygen pentacyclic process for reaction. The content of formic acid in the wastewater containing formaldehyde is higher, about 2 percent, due to side reaction, formaldehyde oxidation and the like. The operation temperatures of the bottom and the top of the formaldehyde recovery tower are 162.5 ℃ and 147- & gt 153 ℃, respectively, and the boiling point of formic acid is 100.6 ℃ close to that of water, so that after the formaldehyde-containing wastewater enters the formaldehyde recovery tower, most of the formic acid contained in the wastewater escapes from the top of the tower along with the water and the formaldehyde, and after condensation, a formaldehyde solution with the concentration of about 35% is formed, wherein the content of the formic acid is about 900ppm, and the other part of the formic acid is discharged to a wastewater tank along with the tower bottom liquid after heat exchange with the formaldehyde-containing wastewater through a preheater. The light components escaping from the top of the formaldehyde recovery tower and the overhigh formic acid in the heavy components discharged from the tower bottom not only cause the serious corrosion of equipment and pipelines in the formaldehyde recovery system, shorten the service life, but also reduce the quality of the recovered formaldehyde and cause adverse effects on the subsequent participation in production.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a method for reducing formic acid in a formaldehyde recovery system, which can effectively reduce the formic acid content in the formaldehyde recovery system, ensure that the formic acid content in light components is lower than 500ppm, reduce the corrosion of equipment and pipelines, prolong the service life and improve the quality of recovered formaldehyde.
The purpose of the invention is realized by the following technical scheme.
The method for reducing the formic acid in the formaldehyde recovery system comprises the following steps:
s1, introducing alkali liquor into a wastewater storage tank through an alkali liquor pipeline to be mixed with wastewater of a trioxymethylene preparation unit to obtain dilute alkali liquor;
s2, conveying the dilute alkali liquor in the wastewater storage tank to an online static mixer through a conveying pump, mixing the dilute alkali liquor with the wastewater containing formaldehyde, conveying the mixed dilute alkali liquor and the wastewater containing formaldehyde into a feed tank of a formaldehyde recovery tower, and neutralizing formic acid in the wastewater containing formaldehyde by using the dilute alkali liquor to control the pH value to be 6.5-7;
s3, conveying the formaldehyde-containing wastewater subjected to acid removal in a feed tank of the formaldehyde recovery tower to a preheater through a feed pump of the formaldehyde recovery tower, and after the wastewater is subjected to heat exchange with tower bottom liquid discharged from the formaldehyde recovery tower, preheating the wastewater, and then feeding the wastewater into the formaldehyde recovery tower for rectification;
s4, adding alkali liquor into the tower kettle of the formaldehyde recovery tower, and neutralizing formic acid in the tower kettle liquid by using the alkali liquor;
s5, cooling the top gas of the formaldehyde recovery tower by a tower top cooler, then feeding the cooled top gas into a reflux tank, sampling from a sampling point, and analyzing to be qualified, and then performing reflux ratio of 1.4: 1, one part of the formaldehyde enters the top of a formaldehyde recovery tower to be used as reflux, and the other part of the formaldehyde enters a crude aldehyde storage tank;
s6, heating one part of the tower bottom liquid of the formaldehyde recovery tower by a reboiler of the formaldehyde recovery tower, performing circulating reflux, and performing heat exchange and cooling on the other part of the tower bottom liquid of the formaldehyde recovery tower and the formaldehyde-containing wastewater subjected to deacidification by a preheater, and then feeding the other part of the tower bottom liquid into a wastewater tank.
The alkali liquor is a sodium hydroxide solution with the mass fraction of 10%.
The formaldehyde-containing wastewater consists of waste liquid discharged from a waste gas washing tower, a waste gas recovery tower and a TOX concentration tower.
A PH value on-line monitoring device is installed in a feeding groove of the formaldehyde recovery tower, the PH value is detected in real time, and the addition amount of dilute alkali liquor is guided.
The sampling analysis qualification standard at the sampling point is that the formaldehyde content is between 35 and 40 percent, the formic acid content is less than 500ppm, and the addition amount of the alkali liquor at the tower bottom is controlled by the formic acid content analyzed at the sampling point.
The alkali liquor and formic acid are subjected to acid-base neutralization reaction to generate sodium formate, the sodium formate is easily dissolved in about 1.3 parts of water, the water content of the formaldehyde-containing wastewater and the water content of the tower bottom liquid are about 86% and 99% respectively, and the sodium formate generated in the acid removal process can be completely dissolved in the formaldehyde-containing wastewater and the tower bottom liquid.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
(1) the invention is successfully applied to the formaldehyde recovery system of the polyformaldehyde device, solves the problem that the formic acid in the formic acid-containing wastewater causes high corrosion to the pipeline and equipment of the formaldehyde recovery system, and prolongs the service life of the pipeline and the equipment.
(2) The invention can effectively reduce the content of formic acid in the recovered formaldehyde, improve the quality of the recovered formaldehyde and ensure the stability of the recovered formaldehyde in subsequent production and utilization.
(3) The sodium formate generated by acid-base neutralization in the operation process of the invention is easy to dissolve in water, can be completely dissolved in the formaldehyde-containing wastewater and heavy components, and can not cause tower plate blockage.
(4) The method has the advantages of low investment cost, short construction period, simple operation and easy popularization.
Drawings
FIG. 1 is a schematic process flow diagram of the method for reducing formic acid in a formaldehyde recovery system according to the present invention.
Reference numerals: 1-alkali liquor pipeline, 2-waste water storage tank, 3-delivery pump, 4-online static mixer, 5-formaldehyde recovery tower feeding tank, 6-formaldehyde recovery tower feeding pump, 7-preheater, 8-formaldehyde recovery tower, 9-tower top cooler, 10-reflux tank, 11-reflux pump, 12-formaldehyde recovery tower reboiler and 13-sampling point.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The invention discloses a device for reducing formic acid in a formaldehyde recovery system, which comprises an alkali liquor pipeline 1, a wastewater storage tank 2, a conveying pump 3, an online static mixer 4, a formaldehyde recovery tower feeding tank 5, a formaldehyde recovery tower feeding pump 6, a preheater 7, a formaldehyde recovery tower 8, a tower top cooler 9, a reflux tank 10, a reflux pump 11, a formaldehyde recovery tower reboiler 12 and a sampling point 13.
The alkali liquor pipeline 1 is divided into two branch pipelines, one branch pipeline is connected to the tower kettle of the formaldehyde recovery tower 8, and the other branch pipeline and the waste water pipeline of the trioxymethylene preparation unit are respectively connected to the feed inlet at the top of the waste water storage tank 2. 2 discharge pipe ways of waste water storage tank are connected to 4 feed inlets of online static mixer respectively through transfer pump 3 and formaldehyde-containing waste water pipeline, 4 discharge gates of online static mixer are connected to 5 feed inlets of formaldehyde recovery tower pan feeding groove through the pipeline, 5 discharge gates of formaldehyde recovery tower pan feeding groove are connected to 7 tube side imports of preheater through formaldehyde recovery tower pan feeding pump 6 through the pipeline. Wherein, a PH value on-line monitoring device is arranged in the feeding tank 5 of the formaldehyde recovery tower, the PH value is detected in real time, and the addition of dilute alkali liquor is guided.
8 upper portion feed inlets of formaldehyde recovery tower pass through pipe connection to export of 7 tube side of pre-heater, 8 top discharge gates of formaldehyde recovery tower have connected gradually top of the tower cooler 9, reflux drum 10, backwash pump 11 through the pipeline, 11 discharge gates of backwash pump are connected to 8 upper portion circulation imports of formaldehyde recovery tower, crude aldehyde storage tank respectively through the pipeline. There is formaldehyde recovery tower reboiler 12 through the pipe connection between 8 lower part discharge gates of formaldehyde recovery tower and the circulation import, 8 lower part discharge gates of formaldehyde recovery tower are connected to 7 shell side entries of preheater through the pipeline, 7 shell side exports of preheater are connected to the wastewater disposal basin through the pipeline. Sampling point 13 sets up on the pipeline between reflux drum 10 export to reflux pump 11 entry, sampling point 13 can adopt the pair to open the valve.
The method for reducing the formic acid in the formaldehyde recovery system comprises the following processes:
s1, introducing alkali liquor into a wastewater storage tank 2 through an alkali liquor pipeline 1, and mixing the alkali liquor with wastewater of a trioxymethylene preparation unit to obtain dilute alkali liquor. Wherein the alkali liquor is a sodium hydroxide solution with the mass fraction of 10%.
S2, conveying the dilute alkali liquor in the wastewater storage tank 2 to an online static mixer 4 through a conveying pump 3, mixing with the wastewater containing formaldehyde, conveying into a feed tank 5 of a formaldehyde recovery tower, neutralizing formic acid in the wastewater containing formaldehyde by using the dilute alkali liquor, and controlling the pH value to be 6.5-7. Wherein the formaldehyde-containing wastewater consists of waste liquid discharged from a waste gas washing tower, a waste gas recovery tower, a TOX concentration tower and the like. And a PH value on-line monitoring device is arranged in the feeding tank 5 of the formaldehyde recovery tower, and is used for detecting the PH value in real time and guiding the addition of dilute alkali liquor.
And S3, conveying the formaldehyde-containing wastewater subjected to deacidification in the formaldehyde recovery tower feeding groove 5 to a preheater 7 through a formaldehyde recovery tower feeding pump 6, performing heat exchange with tower bottom liquid discharged from the formaldehyde recovery tower 8, preheating, and then feeding into the formaldehyde recovery tower 8 for rectification.
And S4, adding alkali liquor into the tower bottom of the formaldehyde recovery tower 8, and neutralizing formic acid in the tower bottom liquor by using the alkali liquor. The alkali liquor and formic acid are subjected to acid-base neutralization reaction to generate sodium formate, the sodium formate is easily dissolved in about 1.3 parts of water, the water content of the formaldehyde-containing wastewater and the water content of the tower bottom liquid are respectively about 86% and 99%, and the sodium formate generated in the acid removing process can be completely dissolved in the formaldehyde-containing wastewater and the tower bottom liquid.
S5, cooling the top gas of the formaldehyde recovery tower 8 by a tower top cooler 9, then feeding the cooled top gas into a reflux tank 10, sampling from a sampling point 13, and analyzing to be qualified, and then performing reflux ratio of 1.4: 1, one part of the formaldehyde enters the top of a formaldehyde recovery tower 8 to be used as reflux liquid, and the other part of the formaldehyde enters a crude aldehyde storage tank. Wherein the qualified standard of sampling analysis at the sampling point 13 is that the formaldehyde content is between 35 and 40 percent, the formic acid content is less than 500ppm, and the addition amount of the alkali liquor at the tower bottom is controlled by the formic acid content separated out at the sampling point 13.
S6, heating one part of the tower bottom liquid of the formaldehyde recovery tower 8 by a formaldehyde recovery tower reboiler 12 and then circularly refluxing, and exchanging heat and cooling the other part of the acid-removed formaldehyde-containing wastewater discharged from the preheater 7 and the feeding groove 5 of the formaldehyde recovery tower, and then feeding the other part of the acid-removed formaldehyde-containing wastewater into a wastewater groove.
While the present invention has been described in terms of its functions and operations with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise functions and operations described above, and that the above-described embodiments are illustrative rather than restrictive, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined by the appended claims.
Claims (6)
1. A method for reducing formic acid in a formaldehyde recovery system is characterized by comprising the following processes:
s1, introducing alkali liquor into a wastewater storage tank (2) through an alkali liquor pipeline (1), and mixing the alkali liquor with wastewater of a trioxymethylene preparation unit to obtain dilute alkali liquor;
s2, conveying the dilute alkali liquor in the wastewater storage tank (2) to an online static mixer (4) through a conveying pump (3), mixing the dilute alkali liquor with the wastewater containing formaldehyde, conveying the mixed liquor into a feed tank (5) of a formaldehyde recovery tower, neutralizing formic acid in the wastewater containing formaldehyde by using the dilute alkali liquor, and controlling the pH value to be 6.5-7;
s3, conveying the formaldehyde-containing wastewater subjected to deacidification in a feeding groove (5) of the formaldehyde recovery tower to a preheater (7) through a feeding pump (6) of the formaldehyde recovery tower, performing heat exchange with the tower bottom liquid discharged out of the formaldehyde recovery tower (8), preheating, and then rectifying in the formaldehyde recovery tower (8);
s4, adding alkali liquor into the tower kettle of the formaldehyde recovery tower (8), and neutralizing formic acid in the tower kettle liquor by using the alkali liquor;
s5, cooling the top gas of the formaldehyde recovery tower (8) by a tower top cooler (9), then feeding the cooled top gas into a reflux tank (10), sampling from a sampling point (13), analyzing and qualifying, and then performing reflux ratio of 1.4: 1, one part of the formaldehyde enters the top of a formaldehyde recovery tower (8) to be used as reflux, and the other part of the formaldehyde enters a crude aldehyde storage tank;
s6, heating one part of the tower bottom liquid of the formaldehyde recovery tower (8) by a formaldehyde recovery tower reboiler (12) and then circularly refluxing, and exchanging heat with the formaldehyde-containing wastewater subjected to deacidification by the preheater (7) and cooling the other part of the tower bottom liquid to enter a wastewater tank.
2. The method for reducing formic acid in a formaldehyde recovery system as recited in claim 1, wherein said caustic is a 10% by weight sodium hydroxide solution.
3. The method for reducing the formic acid in the formaldehyde recovery system according to claim 1, wherein the formaldehyde-containing wastewater comprises waste liquid discharged from a waste gas washing tower, a waste gas recovery tower and a TOX concentrating tower.
4. The method for reducing the formic acid in the formaldehyde recovery system as defined in claim 1, wherein the feeding tank (5) of the formaldehyde recovery tower is provided with an online pH monitoring device for detecting the pH value in real time and guiding the addition of the dilute alkali solution.
5. The method for reducing the formic acid in the formaldehyde recovery system as recited in claim 1, wherein the qualified standard of sampling analysis at the sampling point (13) is that the formaldehyde content is between 35% and 40%, the formic acid content is less than 500ppm, and the addition amount of the tower bottom alkali liquor is controlled by the formic acid content separated out at the sampling point (13).
6. The method of claim 1, wherein the alkali solution and formic acid undergo an acid-base neutralization reaction to form sodium formate, the sodium formate is readily soluble in about 1.3 parts of water, the water content in the formaldehyde-containing wastewater and the water content in the tower bottoms are about 86% and about 99%, respectively, and the sodium formate generated during the acid removal process is completely soluble in the formaldehyde-containing wastewater and the tower bottoms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210440430.XA CN114790061A (en) | 2022-04-25 | 2022-04-25 | Method for reducing formic acid in formaldehyde recovery system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210440430.XA CN114790061A (en) | 2022-04-25 | 2022-04-25 | Method for reducing formic acid in formaldehyde recovery system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114790061A true CN114790061A (en) | 2022-07-26 |
Family
ID=82461808
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210440430.XA Pending CN114790061A (en) | 2022-04-25 | 2022-04-25 | Method for reducing formic acid in formaldehyde recovery system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114790061A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109133232A (en) * | 2018-09-27 | 2019-01-04 | 南通天泽化工有限公司 | A kind of recovery system and its recovery method of highly concentrated formaldehyde solution |
-
2022
- 2022-04-25 CN CN202210440430.XA patent/CN114790061A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109133232A (en) * | 2018-09-27 | 2019-01-04 | 南通天泽化工有限公司 | A kind of recovery system and its recovery method of highly concentrated formaldehyde solution |
Non-Patent Citations (2)
| Title |
|---|
| 陈鹏: "甲醛回收塔加碱降酸防腐蚀工艺技术改造", 《化肥设计》, vol. 55, no. 6, pages 46 - 49 * |
| 黄苍锋等: "甲醛回收塔防腐蚀技术探讨", 《广州化工》, vol. 42, no. 11, pages 169 - 170 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110054164B (en) | Concentrated recovery system of dilute sulfuric acid | |
| CN105754724A (en) | Method for direct conversion of plant soapstock into fatty acid | |
| CN102850519A (en) | Synthetic method of epoxy resin, and associated device thereof | |
| CN110092711A (en) | A kind of formaldehyde separation method of butanol purifying technique | |
| CN207046880U (en) | Hydrochloric acid pickling waste liquor recovery and processing system | |
| CN114790061A (en) | Method for reducing formic acid in formaldehyde recovery system | |
| CN218403826U (en) | Device for reducing formic acid in formaldehyde recovery system | |
| CN217163255U (en) | A rectification equipment that is arranged in N-methylaniline production methyl alcohol to retrieve | |
| CN107163007A (en) | A kind of method that continuous stream micro passage reaction hemicellulose two-step method prepares furfural | |
| CN210103609U (en) | Prevent wet-type oxidation reaction system of jam | |
| CN101255350B (en) | Technique for comprehensive treatment of diesel oil alkaline residue by using circulating technology | |
| CN206109122U (en) | Hydrochloric acid pickling waste water processing system | |
| CN114684953B (en) | Method and device for treating ethylene waste alkali liquor | |
| CN109052522B (en) | Glycol production wastewater pretreatment system and method | |
| CN211595332U (en) | System for treating coke oven gas desulfurization and decyanation waste liquid by using waste pickling solution | |
| CN108854456B (en) | System and method for recycling heat energy of desorption tower | |
| CN220257200U (en) | Steam condensate recovery processing equipment | |
| CN221588183U (en) | Ammonia-nitrogen wastewater stripping deamination process system | |
| CN109852413A (en) | A kind of method of coal tar production modified coal tar pitch | |
| CN219433229U (en) | Device for recovering polluted steam condensate and waste heat thereof | |
| CN215962208U (en) | Ethylene glycol rectification anticorrosion system | |
| CN102517216B (en) | Process for extracting thallus protein from concentrated glutamic acid mother liquor | |
| CN218130022U (en) | Multifunctional online detection rectification system | |
| CN216573011U (en) | Nylon copolymerization reactor | |
| CN219603382U (en) | Process system for recycling ammonia nitrogen in sewage treatment |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |