WO2011032311A1 - 一种二苯基甲烷二异氰酸酯（mdi）生产过程中产生的废盐水的处理方法 - Google Patents

一种二苯基甲烷二异氰酸酯（mdi）生产过程中产生的废盐水的处理方法 Download PDF

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Publication number
WO2011032311A1
WO2011032311A1 PCT/CN2009/073991 CN2009073991W WO2011032311A1 WO 2011032311 A1 WO2011032311 A1 WO 2011032311A1 CN 2009073991 W CN2009073991 W CN 2009073991W WO 2011032311 A1 WO2011032311 A1 WO 2011032311A1
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Prior art keywords
brine
waste brine
tower
waste
extraction
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PCT/CN2009/073991
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English (en)
French (fr)
Inventor
张宏科
华卫琦
刘小高
赵振华
孙淑常
丁建生
陈建峰
张鹏远
邹海魁
初广文
许利民
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宁波万华聚氨酯有限公司
北京化工大学
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Application filed by 宁波万华聚氨酯有限公司, 北京化工大学 filed Critical 宁波万华聚氨酯有限公司
Priority to EP09744307.1A priority Critical patent/EP2479149B1/en
Priority to KR1020127009895A priority patent/KR101413345B1/ko
Priority to US13/496,872 priority patent/US9802848B2/en
Priority to PCT/CN2009/073991 priority patent/WO2011032311A1/zh
Publication of WO2011032311A1 publication Critical patent/WO2011032311A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/14—Purification
    • C01D3/16—Purification by precipitation or adsorption
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/14—Purification
    • C01D3/18—Purification with selective solvents
    • 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
    • C02F1/26—Treatment of water, waste water, or sewage by extraction
    • 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
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • 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
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • 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
    • C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
    • 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
    • C02F1/26—Treatment of water, waste water, or sewage by extraction
    • C02F1/265—Desalination
    • 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
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
    • 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
    • C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
    • 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
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/74—Treatment of water, waste water, or sewage by oxidation with air
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
    • C02F2103/36—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from the manufacture of organic compounds

Definitions

  • the present invention relates to a method for treating industrial waste brine, and more particularly to a method for treating waste brine produced during the production of diphenylmethane diisocyanate (hereinafter referred to as MDI).
  • MDI diphenylmethane diisocyanate
  • MDI is one of the main raw materials for the polyurethane industry.
  • the aniline and formaldehyde are subjected to a condensation reaction under the action of a hydrochloric acid catalyst to obtain a polymethylene polyphenylpolyamine, and then a polymethylene polyphenyl polyamine phosgenation reaction is used to produce a monomer MDI and a polymeric MDI, which is a polyurethane industry.
  • the aniline and formaldehyde are subjected to a condensation reaction under the action of a hydrochloric acid catalyst to obtain polymethylene polyphenyl polyamine hydrochloride, which is then neutralized with caustic soda, and the brine layer and the polyamine layer are separated, and the polyamine layer is washed with process water.
  • Refining to obtain polyamines is one of the key steps in the preparation of MDI.
  • the above neutralization and washing process will produce a large amount of waste brine.
  • the organic substances such as aniline, diphenylmethane diamine and polyamine in the waste brine are subjected to extraction and stripping treatment, and the pollutant content can be discharged after the detection of the pollutant content.
  • MDI production equipment usually uses toluene, xylene, chlorobenzene, dichlorobenzene or aniline as an extractant to treat waste brine.
  • the extraction equipment generally uses a mixing clarification tank or an extraction tower or a Graes ser extractor.
  • the above extraction process has the disadvantages of large volume of equipment, large investment, low extraction efficiency, long extraction equilibrium time, and easy blockage of the tray or the filler by the salt mud, thereby causing high content of organic amines in the discharged waste brine. Generate fluctuations.
  • the MDI production equipment adopts the conventional extraction and stripping treatment of waste brine, which contains about 14% to 18% sodium chloride, the pH value is generally between 12 and 14, the T0C is about 30 to 50 ppm, and the TN is about 3 ⁇ . 5ppm.
  • waste brine which contains about 14% to 18% sodium chloride
  • the pH value is generally between 12 and 14
  • the T0C is about 30 to 50 ppm
  • the TN is about 3 ⁇ . 5ppm.
  • the above-mentioned waste brine has a high content of organic amines and cannot be directly used as a raw material, and can only be discharged to the standard.
  • the amount of waste brine discharged during the annual MDI production process is large, resulting in a large amount of water and salt waste.
  • a large amount of MDI waste brine can be further treated to make the organic content meet the requirements of the ion-exchange membrane caustic soda production process, and it can be used as a raw material for the production of chlor-alkali ion-exchange membrane caustic soda to generate chlorine gas and caustic soda.
  • MDI production requirements such as hydrochloric acid and hydrogen Chemical raw materials, so that the resources such as sodium chloride and water in the waste water of MDI production are regenerated, and the recycling of materials in the MDI industrial chain is realized.
  • the ZL200710013817. 2 patent discloses a method for continuously extracting polymethylene polyphenyl polyamine from brine, which has a higher content of waste brine organic matter (higher T0C and TN values) due to no subsequent treatment of waste brine.
  • High from a safety point of view, can only be strictly applied to the technical defects of the diaphragm electrolysis process in caustic soda production.
  • the diaphragm electrolysis process belongs to the high energy consumption technology and is subject to policy restrictions, which will be replaced by the ion membrane electrolysis process.
  • the ion membrane electrolysis process requires more stringent organic content in the brine.
  • the ZL200710138065. 2 patent discloses a method for deep treatment of waste brine produced in the production process of MDI, which has a large amount of steam consumed by the stripper due to the use of one-step conventional extraction treatment, and at the same time,
  • the waste brine has higher organic matter content before deep treatment, more oxidant consumed during deep treatment, large amount of adsorbent, and high processing cost.
  • the method for treating MDI waste brine provided by the present invention comprises the following steps:
  • step (3) conveying the waste brine and chemical oxidant discharged from the stripper in step (1) to the oxidation reactor, and introducing air into the aeration;
  • the brine treated by the step (4) can be sent to the chlor-alkali plant as a raw material for production.
  • the waste of the polyamine preparation step in the MDI production process The mass concentration of aniline in the brine is 1-3%, the total mass concentration of diphenylmethanediamine and polyamine (hereinafter referred to as DAM) is 0. 05-0. 3%, and the mass concentration of sodium chloride in the brine is 14 ⁇ 18%.
  • the waste brine and the extractant are first introduced into a supergravity rotating bed for extraction.
  • the spent brine and extractant can be added to the supergravity rotating bed through a liquid distributor at the inlet of the supergravity rotating bed, or premixed and added to the supergravity rotating bed via the liquid distributor.
  • the waste brine and extractant can be added to the supergravity rotating bed in a cocurrent or cross-flow manner.
  • the liquid distributor used can be open or slotted or single or porous or single or multi-tank. , single or multi-group.
  • the phase separator refers to a device in which the polyamine layer and the brine layer are separated by delamination due to density difference, and may be a static device such as a clarification tank or an oil water separator.
  • the separator generally consists of a lateral separation portion and a longitudinal separation portion, wherein the lateral separation portion is provided with a plurality of inclined isolation plates, such a structure is advantageous for separation of the two phases, the longitudinal portion is a stationary portion, and may be a dynamic device such as centrifugation. Splitter.
  • the super-gravity rotating bed can quickly and uniformly mix the waste brine and the extracting agent, the mixing effect of the mixture is close to the molecular state, and the oil phase (extractant) and the water phase (waste brine) are reached.
  • the extraction equilibrium time is extremely short, about 0. Bu 10 seconds, and the conventional extraction reaches a balanced time for a long time, generally the hour level. Before the equilibrium is reached, the treatment effect is unstable, and the organic matter content in the waste brine is very high. Failure to meet standard emissions affects normal production processes.
  • the use of a super-gravity rotating bed for the extraction of waste brine can reduce the amount of extractant and achieve a higher and more stable processing efficiency than conventional extraction.
  • the volumetric flow ratio of fresh extractant to waste brine entering the supergravity rotating bed is 1: 5 ⁇ 1 : 20, preferably 1: 10 ⁇ 1: 15; the residence time of waste brine and extractant in the phase separator is 10 ⁇ 120 minutes, preferably 20 to 40 minutes.
  • the extracting agent in the first step of the method of the present invention may be selected from various extracting agents conventional in the art, and the present invention includes, but is not limited to, the extracting agent is aniline, p-methylaniline, o-methylaniline, p-ethylaniline, o-ethylaniline. 2,4-Dimethylaniline or 2,4,6-trimethylaniline, or any mixture thereof;
  • the extractant of the present invention is preferably aniline.
  • Fresh aniline (referred to as industrial pure aniline) After extracting DAM from waste brine, it can be used as a reaction raw material for preparing polyamines without any subsequent purification treatment.
  • the phase separated waste brine enters the extraction column in a countercurrent flow with the fresh extractant.
  • the extraction tower is used to achieve better treatment results, improve extraction efficiency, and reduce operating costs. Due to the very high mass transfer rate of the supergravity rotating bed extraction process, approximately 50-80% of the organic matter can be extracted. Step extraction towers (slower equilibrium time, low mass transfer rate, often require a higher packing layer or more trays) can operate at higher loads than before, increasing production efficiency. At the same time, since the equilibrium level of the extraction tower is generally several tens of, the extraction effect is better, and the content of organic matter in the waste brine can be made lower. At the same time, due to the pretreatment of the super-gravity rotating bed extraction, the extraction tower can avoid the salt water mudging blockage or the tray which occurred in the past in the long-term operation, and the wastewater index exceeds the standard.
  • the extraction column can be a tray column or a packed column.
  • the internal components of the tower such as liquid distributors, packings or trays, can be selected from common industrial models depending on the engineering design. There are no special requirements for the structure inside the tower.
  • the volumetric flow ratio of fresh extractant to waste brine is 1: 2 ⁇ 1 : 12, preferably 1: 5 ⁇ 1: 10.
  • the supergravity rotating bed (called Higee or RPB) is a novel device capable of greatly enhancing the transfer and micromixing process, and the basic principle is to use the rotation to generate simulated and controllable
  • the super-gravity environment accelerates the mass transfer rate between liquid-liquid molecules.
  • the super-gravity rotating bed is used to strengthen the waste brine extraction process as the first extraction process, and the extraction tower as the second extraction process can improve the extraction efficiency, avoid the disadvantages of easy internal blockage of the equipment and easy fluctuation of the organic content, and at the same time, extraction
  • the height of the packing layer of the tower or the number of plates, the reflux ratio, the volume of the equipment, etc. can be reduced, the P operation cost and the investment cost.
  • the waste brine after two-step extraction enters the stripper, which may be a tray column or a packed column.
  • the type of liquid distributor, packing or tray can be selected according to the engineering design requirements, and there are no special requirements for the structure inside the tower.
  • the amount of steam used in the stripper can be determined by one skilled in the art based on the particular process conditions.
  • the stripping tower described in the method of the present invention is a stripping tower which may be a plate column or a packed column, and the steam-water ratio (ratio of steam mass flow rate to waste brine feed mass flow rate) is controlled to be 1:2 ⁇ 1:10. preferably from 1: 4 to 1: 8; more preferably from 1: 5 to 1: 7; the steam pressure is preferably 1. 9- 2. 0Kg / cm 2.
  • the waste salt after two-step extraction and stripping The total content of aniline, diphenylmethane diamine and polyamine in water does not exceed 3 ppm (liquid chromatography). When their total content exceeds 3 ppm, it is preferred to return the waste brine to the MDI production unit for extraction and stripping until the total content of aniline, diphenylmethanediamine and polyamine is less than 3 ppm, and then to the present invention.
  • the oxidation reactor is treated.
  • the reaction temperature of the waste brine discharged from the stripper in the oxidation reactor is controlled at 20 to 90 ° C, preferably 25 to 55 ° C; and the reaction time is controlled at 20 to 150 minutes. Preferably, it is 40 to 90 minutes; the amount of air to be introduced is controlled according to a ratio of air to waste brine volume flow rate of 10 to 60:1, preferably 1 to 5:30:1.
  • the oxidation reactor provided by the invention has relatively mild reaction conditions, which can greatly reduce the investment cost and the operation cost.
  • the chemical oxidizing agent is selected from the group consisting of hydrogen peroxide, ozone or an oxidizing agent containing free chlorine.
  • the free chlorine-containing oxidizing agent may be liquid chlorine, chlorine gas, sodium hypochlorite, chlorine dioxide or a pale salt water containing free chlorine which flows out from a chlor-alkali factory ion membrane electrolyzer.
  • the oxidizing agent used in the present invention may be either a general industrial product or a recycled product by-product of industrial processes.
  • the amount of the chemical oxidizing agent to be added can be determined by those skilled in the art depending on the chemical oxidizing agent used and the specific process conditions.
  • the oxidizing agent is preferably an oxidizing agent containing free chlorine, further preferably a free brine containing free chlorine flowing from a chloralkali factory ion-exchange membrane electrolyzer; and the amount of fresh brine containing free chlorine is added in an amount of 50 - 5000 gram per liter of waste brine.
  • the chlorine standard is controlled, preferably adding from 1 000 to 4000 g of free chlorine per liter of waste brine.
  • the adsorption process of the waste brine may be carried out in various adsorption towers suitable for the process, wherein an activated carbon adsorption tower is preferred.
  • the invention has no special requirements for the arrangement of the adsorption tower, as long as the process requirements can be met.
  • the adsorption tower can be set to one or more. When multiple adsorption towers are installed, they can be set in parallel or in series. Among them, it is preferred to use two fixed bed type activated carbon adsorption towers connected in series.
  • the activated carbon in the activated carbon adsorption tower is preferably a coal-like cylindrical activated carbon or granular activated carbon, and the geometrical size thereof can be selected according to the pressure drop requirement of the adsorption tower, and is designed by a person skilled in the art using conventional techniques.
  • 5 ⁇ 5 ⁇ The general cylindrical coal-based activated carbon having a particle size of 1. 5 ⁇ 5 ⁇ .
  • activated carbon can be reused 2 to 3 times.
  • Activated carbon that cannot be regenerated can be used for thermal power generation. For example, it can be used as a fuel for a thermoelectric unit combustion furnace.
  • the furnace temperature is as high as 1300 ⁇ 140 (TC), which can fully burn organic matter and recover energy.
  • the adsorption temperature is controlled at 25 to 50 ° C: preferably 30 to 50 ° C; the average residence time of the waste brine in the adsorption tower is controlled to 3 to 20 minutes, preferably 5 to 10 minutes.
  • the spent brine after adsorption treatment can be used in an ion-exchange membrane caustic soda production process as a raw material for ion-exchange membrane caustic soda production to prepare raw materials for MDI production.
  • the above adsorbed brine is usually collected in a finished brine tank with a T0C (total organic carbon) of less than 8 ppm and a TN (total nitrogen) of less than 2. 5 ppm, which is then sent to an ion-exchange membrane caustic soda production unit.
  • T0C total organic carbon
  • TN total nitrogen
  • this apparatus after the salting and refining steps, it can be used as a raw material for caustic soda production, and electrolyzed to produce raw materials required for MDI devices such as caustic soda, chlorine, and hydrogen.
  • the present invention can remove the amine organic matter in the MDI waste brine more cleanly, and the treated brine has a T0C of less than 8 ppm and a TN of less than 2.5 ppm.
  • the organic matter content low T0C, TN value
  • the service life of the membrane of the ion-exchange membrane electrolytic cell is further improved; the degree of contamination of the ion-exchange membrane is reduced, the cell voltage is lowered, and the power consumption is lowered.
  • the TN value is also lowered, the risk of using the MDI waste brine in the ion-exchange membrane electrolyzer is further reduced.
  • the brine treated by the method of the present invention can be used as an ion-exchange membrane electrolysis raw material of a chlor-alkali plant to generate basic chemical raw materials required for production of MDI plants such as chlorine gas, caustic soda, hydrochloric acid and hydrogen, and to make sodium chloride in MDI waste brine.
  • Resources such as water and water have been regenerated, realizing recycling within the MDI industrial chain and solving the environmental pollution problem of waste brine.
  • the invention adopts two-step extraction treatment, the first step of supergravity rotary bed extraction treatment, and the extraction tower as the second extraction treatment, can improve extraction efficiency and avoid internal components of the device.
  • the clogging and the content of organic matter tend to fluctuate.
  • the height of the packing layer of the extraction tower or the number of plates, the reflux ratio, the volume of the equipment, etc. can be reduced, the P operation cost and the investment cost.
  • the present invention selects the undechlorinated pale salt water flowing out of the ionization membrane ionization tank as an oxidant.
  • the waste chlorine in the pale salt water and the waste alkali in the waste brine can be utilized, and on the other hand, the free brine is free.
  • chlorine when used, it can reduce the dechlorination tower load and subsequent sodium sulfite input, and reduce the operating cost of lye absorption tail chlorine.
  • the process flow provided by the invention is characterized by simple process, convenient operation, reliable operation and low investment cost of industrialization. detailed description
  • the waste brine was transported from the MDI unit condensation process and the waste brine tank, and the flow rate was controlled to 1 000 L/h, wherein the aniline content was 1.5% and the DAM content was 120,000 ppm.
  • the above waste brine and fresh aniline from the aniline raw material tank with a flow rate of 100 L/h were respectively made from the first-stage supergravity rotating bed (manufactured by Beijing University of Chemical Technology, Ministry of Education, Super Gravity Engineering Technology Research Center, the rotor diameter is about 300 ⁇ ).
  • the two liquid phase inlets of the metal packing layer thickness of about 15 mm and the power of about 5 kW are fed, and the speed of the supergravity rotating bed is controlled at 1 000 rpm.
  • the waste brine and extractant flow from the inner edge of the super-gravity rotating bed to the outer edge under the action of centrifugal force, and flow through the liquid phase outlet to the phase separator (manufactured by Yantai Mucun Machinery, volume 3 cubic meters), and the waste brine is controlled by the interface adjuster in the separator.
  • the residence time was 40 minutes, the solution was layered, the upper layer was the extractant (aniline) phase, and the lower layer was the brine phase.
  • the extractant is continuously drawn from the upper layer into the recovery aniline tank, and the brine phase is taken out from the lower layer and sent to the first-stage waste brine buffer tank (about 10 square meters).
  • the DAM content in the waste brine is extracted after the supergravity rotary bed extraction. Reduced to 18ppm.
  • the extraction tower has a diameter of 500 ⁇ and the height of the Pall ring packing is 2,500 ⁇ .
  • the treated waste brine is collected in a second-stage waste brine buffer tank.
  • the waste brine from the second-stage waste brine buffer tank is 3000L/h, and is sent to the top of the stripper.
  • the steam passing through the bottom of the tower is transferred to the bottom of the brine for mass transfer and heat transfer, and the aniline is removed.
  • the steam flow is 5 K ⁇ / ⁇
  • the steam pressure is 1. 9 Kg / cm 2 .
  • the stripper is operated at atmospheric pressure and only has a stripping section.
  • the upper layer is 8 SVG anti-blocking trays (Sulhou Company), the lower packed bed, and the 3 m Sulzer 452Y packing.
  • the residence time in the glass adsorption column is about 12 minutes. After collecting through the adsorption column. The brine was analyzed and analyzed. The treated aniline and diamine have not been detected in the treated brine, the T0C is about 6.9 ppm, the TN is about 1.4 ppm, and the organic content thereof satisfies the process requirements of the ion-exchange membrane caustic soda.
  • Example 1 The test was carried out by using the MDI waste brine treated in Example 1.
  • the temperature of the waste brine is 30 ⁇ 40 °C, and the residence time of the waste brine in the glass adsorption column is about 12 minutes.
  • the aniline and diamine have not been detected in the treated brine, T0C Approximately 6. 8ppm, TN is about 1. 5ppm, and its organic content meets the process requirements of ion-exchange membrane caustic soda.
  • Example 1 The test was carried out by using the MDI waste brine treated in Example 1.
  • the amount of ozone is 10g/h.
  • the ozone is generated by the ozone generator (KT-OZ - 10G type) generated.
  • the waste brine was sent to the jacketed glass adsorption column at a flow rate of 540 liters per hour using a metering pump.
  • the adsorption column used was the same as in Example 1, and the waste brine temperature was 30 to 40 °C.
  • the residence time of the brine in the glass adsorption column was about 12 minutes.
  • the treated aniline and diamine have not been detected in the treated brine, the T0C is about 7.5 ppm, the TN is about 1.6 ppm, and the organic content thereof satisfies the process requirements of the ion-exchange membrane caustic soda.
  • Example 1 The test was carried out by using the MDI waste brine treated in Example 1.
  • the unchlorinated pale salt water was taken from the chlor-alkali ion-exchange membrane caustic soda production unit, and after cooling, the sample was analyzed and analyzed, and the free chlorine (hypochlorous acid # content was about 1500 ppm, T0C was about 5 ppm, and TN was about 2. 5 ppm. Chemical oxidant.
  • the treated aniline and diamine have not been detected in the treated brine, the T0C is about 6.5 ppm, the TN is about 1.4 ppm, and the organic content thereof satisfies the process requirements of the ion-exchange membrane caustic soda.
  • Example 1 Remove 1200 liters of waste brine from the waste brine storage tank, place it in a 2 liter glass kettle with a plug-in aeration tube, add 600 liters of undechlorinated light brine, and chemically oxidize at 40 ⁇ 5 (TC) Reaction, air introduction, aeration volume 60 liters / hour, 1 hour later, using a metering pump to transfer the waste brine in the glass kettle to the jacketed glass adsorption column at a flow rate of 540 liters / hour, using The adsorption column is the same as in Example 1.
  • TC ⁇ 5
  • the adsorption temperature of the waste brine is 30 ⁇ 40 °C, and the residence time of the waste brine in the glass adsorption column is about 12 minutes.
  • the aniline and diamine have not been detected in the treated brine, and the T0C is about 6. 2ppm, TN approx. 1. 2ppm, its organic content meets the process requirements of ionic membrane caustic soda.
  • the MDI waste brine was from the MDI waste brine storage tank in Example 1, which has been sampled and analyzed.
  • the undechlorinated pale salt water was taken from the chlor-alkali ionic membrane caustic soda production unit and placed in a 1 Q cubic meter light brine storage tank. After cooling, sampling and analysis, the free chlorine content was about 1500 ppm, the T0C was about 5 ppm, and the TN was about 2. 5 ppm.
  • the finished brine tank is treated brine. After analysis, aniline and diamine have not been detected.
  • the average T0C is 6.2 ppm, and the TN average is 1. lppm.
  • the organic content of the tank meets the process requirements of ionic membrane caustic soda.
  • the above-mentioned MDI waste brine treatment pilot plant is operated continuously for 120 hours, and the treated brine is about 54 tons.
  • the analytical indexes all meet the requirements of the ion-exchange membrane caustic soda production process. After being sent to the ion-exchange membrane production device brine treatment system, the process parameters of the production device All are normal.

Description

一种二苯基甲烷二异氰酸酯 （MDI) 生产过程中产生的废盐
水的処理方法 技术领域
本发明涉及一种工业废盐水的处理方法， 更具体地说， 是二苯基甲 烷二异氰酸酯 （以下简称 MDI )生产过程中产生的废盐水的处理方法。 背景技术
MDI是聚氨酯行业的主要原料之一。将苯胺和甲醛在盐酸催化剂作用 下进行缩合反应， 获得多亚甲基多苯基多胺， 再利用多亚甲基多苯基多 胺光气化反应生产单体 MDI 和聚合 MDI， 是聚氨酯行业内众所周知的方 法。
苯胺和甲醛在盐酸催化剂作用下进行缩合反应， 获得多亚甲基多苯 基多胺盐酸盐， 然后用烧碱进行中和， 盐水层和多胺层分离， 将多胺层 用工艺水洗涤后再精制， 得到多胺， 是 MDI 制备方法的关键环节之一。 上述中和及水洗过程会产生大量废盐水， 废盐水中的苯胺、 二苯基甲烷 二胺和多胺等有机物经过萃取、 汽提处理， 检测污染物含量达标后方可 排放。 MDI生产装置常见以甲苯、 二甲苯、 氯苯、 二氯苯或苯胺等作为萃 取剂处理废盐水， 萃取设备一般采用混合澄清槽或萃取塔或 Graes ser萃 取机等。 上述萃取过程存在设备体积大， 投资大， 萃取效率低下， 萃取 平衡时间长， 塔板或者填料容易被盐泥堵塞等缺点， 从而导致排出的废 盐水中的有机胺类物质的含量较高， 容易产生波动。
一般而言， MDI生产装置采用常规萃取、 汽提处理后的废盐水， 约含 有 14% ~ 18%氯化钠， pH值一般为 12 ~ 14之间， T0C约 30~50ppm， TN约 3~5ppm。 按照离子膜烧碱生产工艺的要求， 上述废盐水中有机胺类物质 含量较高， 不能直接作为原料使用， 只能达标排放。 每年的 MDI 生产过 程中废盐水排放量很大， 造成大量的水资源和盐份的浪费。 从可持续性 发展和循环经济方面考虑， 可以将大量的 MDI废盐水再进行深度处理后， 使得有机物含量满足离子膜烧碱生产工艺的要求， 使其作为氯碱离子膜 烧碱生产原料， 生成氯气、 烧碱、 盐酸以及氢气等 MDI 生产需要的基础 化工原料， 使 MDI 生产废盐水中的氯化钠、 水等资源得到再生， 实现了 MDI产业链内物料的循环利用。
ZL200710013817. 2专利公开了一种连续从盐水中萃取多亚甲基多苯 基多胺的方法， 该方法存在由于没有后续废盐水深度处理措施， 废盐水 有机物（T0C及 TN值较高）含量较高， 从安全角度， 只能严格的应用于 烧碱生产中的隔膜电解工艺的技术缺陷。 从长远看， 隔膜电解工艺属于 高能耗技术受到政策限制， 必将被离子膜电解工艺所替代， 而离子膜电 解工艺对盐水中的有机物含量指标要求比较苛刻。
ZL200710138065. 2专利公开了一种 MDI生产过程中产生的废盐水的 深度处理的方法， 该方法存在由于采用了一步常规萃取处理， 汽提塔消 耗的蒸汽较多， 能耗较高， 同时， 由于废盐水在深度处理之前的有机物 含量较高， 深度处理过程中消耗的氧化剂比较多、 吸附剂用量大， 处理 成本高等技术缺陷。
发明内容
针对以上技术缺陷， 本发明的目的是提供一种对 MDI 废盐水进行处 理的方法。
本发明所提供的 MDI废盐水的处理方法包括以下步骤：
( 1 )将 MDI 生产过程中产生的含有苯胺、 二苯基甲烷二胺和多胺的 废盐水和新鲜萃取剂送至超重力旋转床快速混合后， 对萃取剂和废盐水 在相分离器中进行相分离； 然后再将相分离出的废盐水和新鲜萃取剂送 至萃取塔， 进行逆流萃取；
( 2 )将步骤（1 )萃取塔排出的废盐水送至汽提塔， 进行蒸汽汽提；
( 3 )将步骤（ 1 )汽提塔排出的废盐水和化学氧化剂输送至氧化反应 器中， 并通入空气进行曝气；
( 4 )经步骤（ 3 )处理后的废盐水送至吸附塔进行吸附， 即得合格的 盐水。
其中， 经过步骤（ 4 )处理后的盐水即可送至氯碱工厂作为生产原料。 在本发明所述方法中， 正常情况下， MDI生产过程多胺制备步骤的废 盐水中的苯胺的质量浓度为 1 ~ 3 %， 二苯基甲烷二胺和多胺（以下简称 DAM )的总质量浓度为 0. 05-0. 3% ,盐水中氯化钠的质量浓度为 14 ~ 18 %。
在本发明所述方法中， 废盐水和萃取剂第一步先进入超重力旋转床 进行萃取处理。 废盐水和萃取剂可以分别经过超重力旋转床入口处的液 体分布器加到超重力旋转床中， 或者预先混合后经液体分布器加入到超 重力旋转床中。 废盐水和萃取剂可以并流或错流的方式加入到超重力旋 转床中， 所用的液体分布器可以是开孔式或开槽式或单孔式或多孔式或 单槽式或多槽式， 单组式或多组式。
在本发明所述方法中， 所述相分离器是指多胺层和盐水层因为密度 差发生分层进行分离的设备， 可以是静态设备， 例如澄清槽或者油水分 离器。 分离器一般由横向分离部和纵向分离部组成， 其中横向分离部安 装数块倾斜的隔离板， 这样的结构有利于两相的分离， 纵向部分是静置 部； 也可以是动态设备， 例如离心分离器。
根据本发明所述的方法， 由于超重力旋转床能够将废盐水和萃取剂 快速而均勾的混合， 其敖观混合效果接近分子状态， 油相 （萃取剂）和 水相（废盐水）达到萃取平衡的时间极短， 大约 0.卜10秒， 而常规萃取 达到平衡的时间很长， 一般都是小时级， 在未达到平衡前， 处理效果不 稳定， 废盐水中的有机物含量非常高， 不能达标排放， 影响正常生产过 程。
采用超重力旋转床进行废盐水萃取处理， 可以降低萃取剂的用量而 达到比常规萃取更高更稳定的处理效率。 进入超重力旋转床的新鲜萃取 剂和废盐水的体积流量比为 1: 5 ~ 1 : 20， 优选为 1: 10 ~ 1: 15 ; 废盐水和 萃取剂在相分离器的停留时间为 10 ~ 120分钟， 优选为 20 ~ 40分钟。
本发明方法步骤 1 中的萃取剂可以选用本领域常规的各种萃取剂， 本发明包括但不限于萃取剂为苯胺、 对甲基苯胺、 邻甲基苯胺、 对乙基 苯胺、 邻乙基苯胺、 2， 4 -二甲基苯胺或 2， 4， 6 -三甲基苯胺、 或它们 的任意混合物； 本发明萃取剂优选为苯胺。 新鲜苯胺（指工业纯苯胺） 萃取掉废盐水中的 DAM后， 可以作为制备多胺的反应原料， 不需要进行 任何后续的精制处理。 在本发明所述方法中， 经过超重力旋转床萃取后的废盐水进入相分 离器发生分层后， 经相分离的废盐水再与新鲜萃取剂以逆流流动形式进 入萃取塔。 采用萃取塔处理是为了达到更好的处理效果， 提高萃取效率， 同时降低操作费用。 由于超重力旋转床萃取过程的传质速率非常高， 大 约能萃取掉 50~80%的有机物。 而步萃取塔（达到平衡时间慢、 传质速率 低， 往往需要更高的填料层或者更多的塔板数） 可以比以往更高的负荷 的操作， 提高生产效率。 同时， 由于萃取塔的平衡级一般都达到几十个， 萃取效果更佳， 可以使得废盐水中的有机物含量更低。 同时， 由于超重 力旋转床萃取的预处理， 萃取塔可以避免以往在长期运转情况下发生的 盐泥堵塞填料或者塔板而导致废水指标超标。
萃取塔可以是板式塔或者填料塔。 塔内部构件如液体分布器、 填料 或者塔板的型式可根据工程设计需要选用常见工业型号。 塔内结构没有 任何特殊要求。新鲜萃取剂和废盐水的体积流量比为 1: 2 ~ 1 : 12，优选为 1: 5 ~ 1: 10。
本发明方法中，所述的超重力旋转床（称为 H i gee或 RPB)是一种能够 极大强化传递和微观混合过程的新型设备， 其基本原理就是利用旋转产 生模拟的、 可调控的超重力环境， 使得液 -液分子间传质速度加快。 采 用超重力旋转床强化废盐水萃取过程， 作为第一步萃取处理， 而萃取塔 作为第二步萃取处理， 可以提高萃取效率， 避免设备内部构件容易堵塞 和有机物含量容易波动的缺点， 同时， 萃取塔的填料层高度或塔板数、 回流比、 设备体积等可以减小、 P条低操作费用及投资费用。
经过两步萃取后的废盐水进入汽提塔， 汽提塔可以是板式塔或者填 料塔。 液体分布器、 填料或者塔板的型式可根据工程设计需要选用常见 工业型号， 塔内结构没有任何特殊要求。 汽提塔的蒸汽用量可由本领域 的技术人员根据具体的工艺条件来确定。
本发明方法中所述的汽提塔为汽提塔可以是板式塔或者填料塔， 汽 水比（蒸汽质量流率与废盐水进料质量流率之比）控制为 1 : 2 ~ 1: 10 , 优 选为 1 : 4 ~ 1: 8; 进一步优选为 1: 5 ~ 1: 7 ; 蒸汽压力优选 1. 9- 2. 0Kg/cm2。
在本发明所述方法中， 一般情况下， 经过两步萃取和汽提后的废盐 水中的苯胺、 二苯基甲烷二胺和多胺的总含量不超过 3ppm (液相色谱分 析）。 当它们的总含量超过 3ppm时， 最好将废盐水返回到 MDI生产装置 进行萃取、 汽提， 直到苯胺、 二苯基甲烷二胺和多胺的总含量小于 3ppm 时， 再输送至本发明所述氧化反应器进行处理。
一般来说， 提高氧化反应温度、 增大曝气量， 可以提高废盐水中有 机物的氧化效果， 促使其发生分解。 氧化程度愈深， 分解愈彻底。 由于 废盐水的腐蚀性， 在较高的反应温度下对设备的材质要求更高， 往往需 要更昂贵的耐腐蚀的材质， 需要有换热设备， 材质同样很贵； 同时， 由 于曝气量较大， 需要风量更大的风机及氧化反应器体积； 因此， 氧化反 应器的投资成本非常高。
而在本发明所述方法中， 从汽提塔排出的废盐水在氧化反应器中的 反应温度控制在 20 ~ 90 °C， 优选为 25 ~ 55 °C ; 反应时间控制在 20 ~ 15 0 分钟， 优选为 40 ~ 90分钟； 所通入的空气量按照空气与废盐水体积流量 之比为 1 0 ~ 60: 1，优选 1 5 - 30: 1进行控制。本发明提供的氧化反应器的 反应条件比较温和， 可以极大的降低投资成本及操作费用。
在本发明所述方法中， 化学氧化剂选自双氧水、 臭氧或含游离氯的 氧化剂。 所述含游离氯的氧化剂可以是液氯、 氯气、 次氯酸钠、 二氧化 氯或从氯碱工厂离子膜电解槽流出的含游离氯的淡盐水等。 本发明所采 用的氧化剂既可以是通用的工业产品， 也可以是工业过程副产的回收品。 所述化学氧化剂的加入量可由本领域的技术人员根据所使用的化学氧化 剂以及具体的工艺条件来确定。 所述氧化剂优选含游离氯的氧化剂， 进 一步优选从氯碱工厂离子膜电解槽流出的含游离氯的淡盐水； 且含游离 氯的淡盐水的加入量按照每升废盐水加入 50 - 5000亳克游离氯的标准进 行控制， 优选每升废盐水加入 1 00 ~ 4000亳克游离氯。
在本发明所述方法中， 所述废盐水的吸附过程可以在适合该工艺要 求的各种吸附塔中进行， 其中， 优选活性炭吸附塔。 本发明对于吸附塔 的布置方式没有特殊要求， 只要能够满足工艺要求即可。 吸附塔可以设 置一个， 也可以设置多个； 当设置多个吸附塔时， 可以使其并联设置， 也可以串联设置。 其中， 优选采用两个串联的固定床式活性炭吸附塔。 所述活性炭吸附塔内的活性炭优选煤质圆柱形活性炭或者颗粒活性炭， 其几何尺寸的选择可以根据吸附塔的压降要求， 由本领域技术人员采用 常规技术进行设计。 一般的圆柱型煤质活性炭的粒径为 1. 5 ~ 5匪。 当活 性炭吸附饱和后， 为了避免二次污染， 最好将活性炭送到生产厂家进行 活化再生处理。 一般情况下活性炭可以重复使用 2 ~ 3次。 不能再生的活 性炭可用于热力发电， 例如， 可用作热电单元燃烧炉的燃料， 其炉温高 达 1300 ~ 140(TC左右， 可以使有机物充分燃烧， 并回收能量。
在本发明所述的吸附过程中，吸附温度控制在 25 ~ 50°C：，优选为 30 - 50°C ; 废盐水在吸附塔中的平均停留时间控制在 3 ~ 20分钟，优选为 5 ~ 10分钟。
在本发明所述方法中， 经吸附处理后的废盐水可用于离子膜烧碱生 产方法中， 用作离子膜烧碱生产原料， 以制备 MDI生产所需的原料。
上述经过吸附处理后的盐水通常先收集于成品盐水罐中， 其 T0C (总 有机碳） 小于 8ppm和 TN (总氮） 小于 2. 5ppm， 然后送往离子膜烧碱生 产装置。 在该装置中， 经过化盐、 精制工序后， 即可作为烧碱生产的原 料， 可电解生成烧碱、 氯气和氢气等 MDI装置需要的生产原料。
与现有技术相比， 本发明的有益效果主要体现在以下方面：
1、 本发明能够将 MDI废盐水中的胺类有机物脱除的更干净， 处理后 的盐水的 T0C小于 8ppm， TN小于 2. 5ppm。在进行本发明所得盐水的循环 利用时由于有机物含量（T0C、 TN值低）减少， 进一步提高了离子膜电解 槽的膜的使用寿命； 离子膜污染程度减轻， 槽电压降低， 电耗降低。 同 时， 由于 TN值也降低， 进一步降低了离子膜电解槽使用 MDI废盐水的风 险性。
2、 经本发明所述方法处理后的盐水可用作氯碱工厂离子膜电解原 料， 生成氯气、 烧碱、 盐酸和氢气等 MDI工厂生产需要的基础化工原料， 并使 MDI废盐水中的氯化钠、 水等资源得到再生， 实现了 MDI产业链内 循环利用， 解决废盐水的环境污染问题。
3、 本发明通过两步萃取处理， 第一步超重力旋转床萃取处理， 而萃 取塔作为第二步萃取处理， 可以提高萃取效率， 避免设备内部构件容易 堵塞和有机物含量容易波动的缺点， 同时， 萃取塔的填料层高度或塔板 数、 回流比、 设备体积等可以减小、 P条低操作费用及投资费用。
4、 本发明选择离子膜电离槽流出的未脱氯淡盐水作为氧化剂， 一方 面， 可以将淡盐水中的废氯与废盐水中的废碱利用起来， 另一方面， 将 淡盐水中的游离氯利用起来， 可以减少脱氯塔负荷以及后续的亚硫酸钠 投入量、 减少碱液吸收尾氯等操作成本。
5、 本发明提供的工艺流程在设计上突出体现工艺简洁、 操作方便、 运行可靠、 工业化投资费用低等特点。 具体实施方式
下面的实施例将进一步详细说明本发明所提供的方法， 但本发明并 不因此而受到任何限制。
实施例 1
从 MDI 装置缩合工序中和废盐水罐中输送出废盐水， 流量控制为 1 000L/h , 其中， 苯胺含量为 1. 5 % ， DAM含量为 12 00ppm。 将上述废盐水 与来自苯胺原料罐的一股流量为 1 00L/h的新鲜苯胺分别从第一级超重力 旋转床（由北京化工大学教育部超重力工程技术研究中心制造， 转子直 径约 300匪， 金属填料层厚度约 15mm， 功率约 5千瓦） 的两个液相进口 送入， 超重力旋转床的转速控制在 1 000转 /分钟。 废盐水和萃取剂在离 心力作用下由超重力旋转床内缘流向外缘， 经过液相出口流至相分离器 (烟台木村机械制造， 体积 3立方）， 通过界面调整器控制废盐水在分离 器的停留时间为 40分钟， 溶液分层， 上层为萃取剂 （苯胺）相， 下层为 盐水相。 萃取剂由上层连续引出进入回收苯胺罐， 盐水相从下层引出， 送入第一级废盐水緩冲罐（体积约 1 0方）， 经过分析， 超重力旋转床萃 取后， 废盐水中 DAM含量降为 18ppm。
从第一级废盐水緩冲罐将 1 000L/h 的废盐水与来自苯胺原料罐的新 鲜苯胺 180L/h， 分别从萃取塔的上部进料口和下部进料口送入， 两相由 于比重不同， 使得废盐水和苯胺进行逆流萃取。 萃取塔塔径 500匪， 内装 鲍尔环填料高度为 2500匪。经过分析， 第二步塔式萃取后，废盐水中 DAM 含量降为 0. 8ppm， 苯胺浓度约 2. 6%。 处理后的废盐水收集在第二级废盐 水緩冲罐。
将来自第二级废盐水緩冲罐的废盐水 3000L/h,送入汽提塔顶部， 塔 底部通入的蒸汽与塔顶下来的盐水进行传质、 传热， 脱除苯胺， 蒸汽流 量为 500Kg/h，蒸汽压力为 1. 9 Kg/cm2。汽提塔为常压操作且只有提馏段， 上层为 8块 SVG防堵塔板（苏尔寿公司），下面填料床层， 3米苏尔寿 452Y 填料。 汽提后的废盐水进入 MDI废盐水罐（约 20方）， 经过分析， 废盐 水中的苯胺含量约 1. 7ppm、 DAM的含量约 0. 7ppm， TOC值约 16ppm， TN 约 3. 2ppm， 废盐水中的氯化钠含量约 18 % ， PH值约 13。
实施例 1
将实例 1中 MDI废盐水罐的废盐水移取 1200亳升， 放入带有插入式 曝气管的 2升玻璃釜中， 加入浓度 30 %过氧化氢（分析纯， 烟台化工研 究所） 12亳升， 在常温下进行化学氧化反应， 通入空气， 曝气量 40升空 气 /小时， 1小时后， 将废盐水按照 540亳升 /小时流量送入带有夹套的玻 璃吸附柱中 （直径 30 匪， 高度 800mm )， 内装直径为 4匪的圆柱型煤质 活性炭 100克， 废盐水温度 30 ~ 40 °C， 其在玻璃吸附柱中的停留时间约 12分钟， 收集流经吸附柱后的盐水， 并进行分析。 处理后的盐水中已经 检测不到苯胺和二胺， T0C约 6. 9ppm， TN约 1. 4ppm， 其有机物含量满足 离子膜烧碱的工艺要求。
实施例 3
采用实施例 1处理后的 MDI废盐水进行试猃。
从废盐水储罐中移取废盐水 1200亳升， 放入带有插入式曝气管的 1 升玻璃釜中， 加入浓度 10 %次氯酸钠（试剂纯， 烟台三和化学试剂厂） 6 亳升， 在 4 (TC下进行化学氧化反应， 通入空气， 曝气量 40升 /小时， 1 小时后， 用计量泵将废盐水按照 540亳升 /小时流量送入带有夹套的玻璃 吸附柱中， 所采用的吸附柱与实施例 1相同， 废盐水温度 30 ~ 40 °C， 废 盐水在玻璃吸附柱中的停留时间约 12分钟。 处理后的盐水中已经检测不 到苯胺和二胺， T0C约 6. 8ppm， TN约 1. 5ppm， 其有机物含量满足离子膜 烧碱的工艺要求。 实施例 4
采用实施例 1处理后的 MDI废盐水进行试猃。
从废盐水储罐中移取废盐水 1200亳升， 放入带有插入式曝气管的 1 升玻璃釜中， 通入臭氧量为 10g/h， 臭氧是由臭氧发生器 （KT-OZ - 10G 型） 生成。 1小时后， 用计量泵将废盐水按照 540亳升 /小时流量送入带 有夹套的玻璃吸附柱中， 所采用的吸附柱与实施例 1 相同， 废盐水温度 30 ~ 40 °C , 废盐水在玻璃吸附柱中的停留时间约 12分钟。 处理后的盐水 中已经检测不到苯胺和二胺， T0C约 7. 5ppm， TN约 1. 6ppm， 其有机物含 量满足离子膜烧碱的工艺要求。
实施例 5
采用实施例 1处理后的 MDI废盐水进行试猃。
从氯碱离子膜烧碱生产装置取回未脱氯淡盐水， 冷却后， 取样分析， 游离氯（次氯酸 # 含量约 1500ppm， T0C约 5ppm， TN约 2. 5ppm。 采用 该未脱氯淡盐水作为化学氧化剂。
从废盐水储罐中移取废盐水 1200亳升， 放入带有插入式曝气管的 1 升玻璃釜中， 加入上述未脱氯淡盐水 600 亳升， 在室温下进行化学氧化 反应， 通入空气， 曝气量 60升 /小时， 1小时后， 用计量泵将废盐水按照 540亳升 /小时流量送入带有夹套的玻璃吸附柱中， 所采用的吸附柱与实 施例 1相同。 废盐水的吸附温度 30 ~ 40 °C， 在玻璃吸附柱中的停留时间 约 12分钟。 处理后的盐水中已经检测不到苯胺和二胺， T0C约 6. 5ppm， TN约 1. 4ppm， 其有机物含量满足离子膜烧碱的工艺要求。
实施例 6
采用实施例 1处理后的 MDI废盐水进行试猃。 从废盐水储罐中移取 废盐水 1200亳升， 放入带有插入式曝气管的 2升玻璃釜中， 加入未脱氯 淡盐水 600亳升， 在 40 ~ 5 (TC下进行化学氧化反应， 通入空气， 曝气量 60升 /小时， 1小时后， 用计量泵将玻璃釜中的废盐水按照 540亳升 /小 时流量送入带有夹套的玻璃吸附柱中， 所采用的吸附柱与实施例 1相同。 废盐水的吸附温度为 30 ~ 40 °C， 废盐水在玻璃吸附柱中的停留时间约 12 分钟。 处理后的盐水中已经检测不到苯胺和二胺， T0C约 6. 2ppm， TN约 1. 2ppm, 其有机物含量满足离子膜烧碱的工艺要求。
实施例 7
MDI废盐水来自实例 1中 MDI废盐水储罐， 已经取样分析。从氯碱离 子膜烧碱生产装置取回未脱氯淡盐水放入 1 Q立方米淡盐水储罐，冷却后， 取样分析， 游离氯含量约 1500ppm， T0C约 5ppm， TN约 2. 5ppm。
从废盐水储罐中以 300公斤 /小时的流量输送 MDI废盐水到鼓泡塔底 ( 500 X 3300匪）液相进料管中， 同时， 以 150公斤 /小时流量加入未脱氯 淡盐水至进料管中， 从塔底气相进料管连续通入空气， 曝气量 13立方米 /小时，废盐水从鼓泡塔顶出料管流出后，从活性炭吸附塔（ 600 X 3550匪， 共装填 400公斤直径为 4匪的煤质圆柱型活性炭）塔底的液相进料管线 进入， 流经活性炭床层后， 从吸附塔顶部流出， 进入 20立方米成品盐水 罐。 成品盐水罐是处理后的盐水， 经过分析， 已经检测不到苯胺和二胺， T0C平均 6. 2ppm, TN平均 1. lppm, 其有机物含量满足离子膜烧碱的工艺 要求。
上述 MDI废盐水处理中试装置连续运行 120小时， 处理后的盐水大 约 54吨， 其分析指标均满足离子膜烧碱生产工艺要求， 送入离子膜生产 装置盐水处理系统后， 生产装置各项工艺参数均正常。

Claims

权 利 要 求
1、 一种 MDI生产过程中产生的废盐水处理方法， 其特征在于， 所述 方法包括以下步骤：
(1)将 MDI 生产过程中产生的含有苯胺、 二苯基甲烷二胺和多胺的 废盐水和新鲜萃取剂送至超重力旋转床快速混合后， 对萃取剂和废盐水 在相分离器中进行相分离； 然后再将相分离出的废盐水和新鲜萃取剂送 至萃取塔， 进行逆流萃取；
(2)将步骤（1)萃取塔排出的废盐水送至汽提塔， 进行蒸汽汽提；
( 3 )将步骤（ 1 )汽提塔排出的废盐水和化学氧化剂输送至氧化反应 器中， 并通入空气进行曝气；
( 4 )经步骤（ 3 )处理后的废盐水送至吸附塔进行吸附， 即得合格的 盐水。
1、根据权利要求 1所述的方法，其特征在于，所述废盐水是来自 MDI 生产过程制备多胺步骤的盐水， 盐水中苯胺的质量浓度为 1~3%， 二苯 基甲烷二胺和多胺的质量浓度为 0.05 - 0.3 %，盐水中氯化钠的质量浓度 为 14~18%。
3、 根据权利要求 1所述的方法， 其特征在于， 步骤（ 1 )中所述进入 超重力旋转床的新鲜萃取剂和废盐水的体积流量比为 1: 5 ~ 1: 20,优选为 1: 10~1： 15; 废盐水和萃取剂在相分离器的停留时间为 10~120分钟， 优选为 20 ~ 40分钟。
4、 根据权利要求 3所述的方法， 其特征在于， 步骤（1) 中所述进 入萃取塔的新鲜萃取剂和相分离出的废盐水的体积流量比为 1: 2 ~ 1: 12, 优选为 1: 5 ~ 1: 10; 所述萃取塔是板式塔或者填料塔。
5、 根据权利要求 4 所述的方法， 其特征在于， 步骤（1) 中所述萃 取剂为苯胺、 对甲基苯胺、 邻甲基苯胺、 对乙基苯胺、 邻乙基苯胺、 2， 4-二甲基苯胺或 2， 4， 6-三甲基苯胺、 或它们的任意混合物。
6、 根据权利要求 5 所述的方法， 其特征在于， 步骤（2) 中所述汽 提塔是板式塔或者填料塔， 蒸汽质量流率与废盐水进料质量流率之比为 1:2-1: 10, 优选为 1:4 ~ 1:8; 蒸汽压力优选 1.9- 2. OKg/cm2; 其中， 从 汽提塔排出的废盐水中苯胺、 二苯基甲烷二胺和多胺的含量小于 3ppm; 废盐水的 T0C值小于 20ppm。
7、 根据权利要求 6 所述的方法， 其特征在于， 步骤（3) 中进一步 包括所述氧化反应器中的反应温度控制在 20~90°C， 优选为 25~55°C; 反应时间控制在 20 ~ 150分钟， 优选为 40~90分钟； 所通入的空气量按 照空气与废盐水体积流量之比为 10 ~ 60: 1，优选 15 - 30: 1进行控制； 所 述氧化反应器为鼓泡塔反应器或带有曝气装置的釜罐或槽式反应器。
8、 根据权利要求 7 所述的方法， 其特征在于， 所述步骤（3) 中化 学氧化剂选自双氧水、 臭氧、 氯气或液氯、 次氯酸钠、 二氧化氯或从氯 碱工厂离子膜电解槽流出的含游离氯的淡盐水。
9、 根据权利要求 8 所述的方法， 其特征在于， 所述步骤（4)进一步 包括： 吸附塔的吸附温度控制在 25 - 50°C， 优选为 30 - 50°C; 废盐水在 吸附塔中的平均停留时间控制在 3 - 20分钟， 优选为 5 ~ 10分钟。
10、 根据权利要求 9所述的方法， 其特征在于， 所述步骤（4)中的吸 附塔为一个或者多个串联的固定床式活性炭吸附塔， 所述活性炭为煤质 圆柱形活性炭或者颗粒活性炭。
11、 根据权利要求 10所述的方法， 其特征在于， 所述步骤（4)所制 得盐水的 T0C小于 8ppm， TN小于 2.5ppm。
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EP2479149B1 (en) 2014-07-16
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