POSM waste alkali liquor concentration process and device

Abstract

The invention relates to a POSM waste alkali liquor concentration process and device. The process is a triple-effect forced circulation evaporation and steam stripping process, and comprises the following steps: firstly, carrying out countercurrent multi-effect evaporation concentration on the waste alkali liquid, and then carrying out steam stripping on the evaporated condensate to further reduce COD (Chemical Oxygen Demand); the device comprises a triple-effect evaporation tower, a double-effect evaporation tower, a single-effect evaporation tower and a stripping tower, a separation filler and a fractional condenser are arranged on an evaporation separation chamber, pressurized rectification is adopted in stripping, a corresponding reflux tank has phase separation capability, and an organic phase and a water phase can be separated; the energy consumption is reduced. The COD value of the evaporation condensate can be effectively reduced, and the concentration ratio of the waste alkali liquid is increased.

Description

Technical Field

[0001] The invention belongs to the field of water treatment, and in particular relates to a concentration process and a device for POSM waste alkali liquor. Background Art

[0002] In industry, co-oxidation is often used to produce propylene oxide (PO) and styrene (SM) at the same time. During operation, the POSM device will produce a large amount of POSM wastewater, which is also called waste alkali liquor due to its high pH. POSM waste alkali liquor also has the characteristics of high COD and difficult biodegradation, and it is difficult to treat it using conventional biochemical processes. At present, the main treatment methods for POSM waste alkali liquor at home and abroad are incineration, wet oxidation pretreatment and biochemical post-treatment, and supercritical water oxidation. The incineration method is widely used due to its mature technology and short process flow. However, the incineration method consumes a lot of fuel, and the waste alkali liquor has a high water content, a lot of organic matter and salts, and the operating cost is too high. Therefore, the concentration of waste alkali liquor has become a hot topic of research.

[0003] Chinese patent CN107512751A uses evaporation to evaporate the cyclohexanone saponification waste alkali liquid into a gas phase and then remove the foam and separate it. The gas phase is compressed by a compressor as an evaporation heat source, and the condensate enters the water treatment system to obtain concentrated waste alkali liquid. This concentration method uses MVR technology, which is more energy-saving, but the equipment investment is high. The enrichment of organic matter in the gas phase will reduce the heat exchange temperature difference, and the waste alkali liquid concentration is low; simple evaporation alone makes the COD value in the condensate higher, and the water treatment is difficult and costly.

[0004] Chinese patent CN111437617B uses steam to continuously strip the waste alkali liquid from cyclohexane oxidation to obtain a gas phase containing effective components and waste alkali liquid after stripping. The advantage is that the effective components such as cyclohexane, cyclohexanone and cyclohexanol in the waste alkali liquid are recovered by stripping, and the process is simple and the flow is short; the disadvantage is that the content of other light and heavy components in the gas phase at the top of the tower is high, the water content of the waste alkali liquid after stripping is high, and it is difficult to incinerate.

[0005] Therefore, simply evaporating and concentrating the waste alkali liquor or stripping it cannot both control the COD in the evaporation condensate and significantly reduce the amount of incineration treatment, and both have limitations. The present invention achieves the concentration of the waste alkali liquor and the reduction of the COD in the condensate by improving the multi-effect evaporation and stripping technology and performing energy-saving coupling. Summary of the invention

[0006] The purpose of the present invention is to solve the problems of high COD value of evaporation condensate of current POSM waste alkali liquid, high wastewater treatment cost and low concentration ratio of waste alkali liquid, and provide a POSM waste alkali liquid concentration process and device. The process is a "three-effect forced circulation evaporation + stripping" process, in which the waste alkali liquid is first concentrated by countercurrent multi-effect evaporation, and the evaporation condensate is further reduced by stripping to reduce COD; in the device, a separation filler and a partial condenser are provided on the evaporation separation chamber, and the stripping adopts pressurized distillation to be beneficial to the enrichment (azeotropic) of organic matter at the top of the tower, and the corresponding reflux tank has a phase separation ability, which can realize the separation of organic phase and aqueous phase, and a heat exchanger for thermal coupling of the top gas phase and the evaporation feed is provided to reduce energy consumption. The present invention can effectively reduce the COD value of evaporation condensate, improve the concentration ratio of waste alkali liquid, and is not easy to block pipelines and incineration nozzles.

[0007] The technical problem solved by the present invention is achieved through the following technical solutions:

[0008] A POSM waste alkali solution concentration process, the process comprises the following steps:

[0009] The waste alkali liquid is sent to the primary raw material preheater E1 and the secondary raw material preheater E2 by the raw material feed pump P1 for preheating, and then enters the three-effect evaporation tower T1 for forced circulation evaporation. The reflux liquid obtained by the distillation section and the partial condenser on the separation chamber is refluxed into the tower; the condensate obtained after the secondary gas is condensed by the primary indirect condenser CX1 enters the stripping liquid inlet tank V1, and the non-condensable gas enters the secondary indirect condenser CX2 for condensation to obtain concentrated organic light components; the remaining non-condensable gas is deep-cooled (-15℃~-10℃) by the tertiary indirect condenser CX3, and the condensate of the secondary indirect condenser CX2 and the tertiary indirect condenser CX3 enters the organic liquid tank V5, the organic liquid wastewater is pumped to the concentrated alkali liquid storage tank V4 by the organic liquid pump, and the non-condensable gas is pumped to the tail gas treatment system by the vacuum pump;

[0010] The operating pressure of the triple-effect evaporation tower T1 is 70-90Kpa, the reflux ratio of the dephlegmator is 0.05-0.3, the gas phase extraction temperature is 89.5°C-96.3°C, the tower bottom temperature is 91.1°C-97.9°C, the preferred operating pressure is 80Kpa, and the reflux ratio is 0.1;

[0011] The outflow temperature range of the waste alkali liquid from the primary raw material preheater E1 is 79.6℃-82.8℃; the outflow temperature range of the secondary raw material preheater E2 is 125.1℃-127.7℃.

[0012] After the three-effect concentration, the alkali liquor is sent to the second-effect feed preheater E4 through the three-effect discharge pump P2, and after heat exchange with the stripping steam (the material outlet temperature range of the second-effect feed preheater E4 is 120.9℃-127.6℃), it enters the second-effect evaporation tower T2; the alkali liquor from the three-effect concentration is forced to circulate and evaporate in the second-effect heater E4, and the condensate containing heavy components obtained by the distillation section on the separation chamber and part of the evaporated condensate is refluxed into the tower, and the secondary gas (104.8℃-111.4℃) enters the shell side of the three-effect heating chamber E3 as a heat source, and the condensate enters the condensate tank V2; the concentrated alkali liquor is sent to the first-effect evaporation tower T3 through the second-effect discharge pump P3;

[0013] The operating pressure of the second-effect evaporation tower T2 is 120-150Kpa, and the reflux ratio is 0.1-0.5; the gas phase extraction temperature is 104.8°C-111.4°C, and the tower bottom temperature is 106.5°C-113.1°C. The preferred operating pressure is 135Kpa, and the reflux ratio is 0.15;

[0014] The alkali liquor from the second effect concentration is sent to the first effect evaporation tower T3 through the second effect discharge pump P3, and is heated by the first effect heater E6 (124.1℃-130℃) for forced circulation evaporation. The condensate containing heavy components obtained by the distillation section on the separation chamber and part of the evaporated condensate is refluxed into the tower. The secondary gas separated by the first effect separation chamber enters the second effect heating chamber E5 (106.5℃-113.1℃) as an evaporation heat source. The concentrated alkali liquor flows to the concentrated alkali liquor storage tank V4 through the liquid level difference, and is sent to the incinerator for incineration through the concentrated alkali liquor discharge pump P10.

[0015] The first-effect evaporation tower T3 has an operating pressure of 200-240 Kpa, a reflux ratio of 0.15-0.5, a gas phase extraction temperature of 120.2°C-126.1°C, a tower bottom temperature of 124.1°C-130°C, and preferably an operating pressure of 200 Kpa and a reflux ratio of 0.2;

[0016] The evaporated condensate from the first-effect evaporation tower and the second-effect evaporation tower flows by gravity to the condensate tank V2 after heat exchange. A small amount of condensate in the condensate tank V2 is sent by the condensate pump P8 to the first-effect evaporation tower T3 and the second-effect evaporation tower T2 distillation section as reflux liquid to control the entrainment and volatilization of organic heavy components. The remaining condensate is sent to the stripping section stripping liquid inlet tank V1 together with the first-stage condensate of the three-effect evaporation tower to further remove the organic components.

[0017] The condensate from the stripping liquid inlet tank V1 is sent to the middle and upper part of the stripping tower T4 by the stripping feed pump P4, and the organic components are removed by stripping under pressure. The gas phase at the top of the tower is condensed by thermal coupling with the evaporation section and then enters the reflux tank V3 (the gas phase at the top of the tower exchanges heat with the second-effect feed preheater E4 of the evaporation section and the secondary raw material preheater E2, and the liquid phase returns to the reflux tank of the stripping section after heat exchange), and is divided into an aqueous phase and an organic phase in the reflux tank V3. The aqueous phase is sent to the top of the stripping tower for reflux by the reflux pump P5, and the organic phase is condensed by the top condensate recooler CX5 and then sent to the concentrated alkali solution storage tank V4, and then sent to the incinerator for incineration through the concentrated alkali solution pump P10; the qualified bottom liquid is sent to the first-level raw material preheater E1 of the evaporation section for preheating the raw material and the recooler CX6 for cooling, and then goes to biochemical treatment.

[0018] Since the stripping tower operates under pressure, the gas phase temperature is high and the calorific value is large. Therefore, a thermal coupling method is used to exchange heat between the stripping tower gas phase and the secondary raw material preheater and the second-effect feed preheater. This not only reduces the use of condensed water, but also reduces the amount of steam required to heat the raw materials, thereby greatly saving energy consumption.

[0019] The stripping tower T4 has an operating pressure of 280-320 Kpa, a reflux ratio of 3-3.6, a gas phase extraction temperature of 112.8°C-117.7°C, a tower bottom temperature of 131.6°C-136.1°C, preferably an operating pressure of 300 Kpa, and a reflux ratio of 3.4; the cooling temperature of the tower top condensate recooler CX5 and the recooler CX6 is below 40°C;

[0020] The three condensers CX1, CX2, and CX3 connected to the triple-effect evaporation tower T1 contain water and some organic matter in the gas phase from the triple-effect evaporation tower T1. The gas phase fraction is adjusted by the primary indirect condenser CX1 to control the COD content in the condensate. After condensation by CX1, the condensate is mainly water, and the remaining non-condensable gas is mainly organic matter with a low boiling point. After condensation by CX2 and CX3, it enters the organic liquid tank V5. The gas phase fraction of the primary indirect condenser CX1 is 0.03-0.05;

[0021] The three evaporation separation chambers are provided with a rectification section, and the triple-effect evaporation tower is provided with a partial condenser to control the entrainment and volatilization of the organic heavy components;

[0022] The process flow is a "triple-effect evaporation + steam stripping" process flow, in which evaporation is performed first and then steam stripping. Since the part of the evaporation tower containing a distillation section can effectively control the entrainment and volatilization of heavy components during the evaporation process, the content of organic components in the final gas condensate is less than 0.1%; while the "stripping + triple-effect evaporation" process flow is first stripping and then evaporation. The entrainment of heavy components cannot be controlled during stripping, resulting in a high content of heavy components in the gas phase at the top of the tower, and the content of organic components in the final gas condensate is only less than 0.5%; in comparison, the process concentration effect of triple-effect evaporation + steam stripping and the distillation section in the evaporation tower is more ideal.

[0023] The POSM waste alkali solution comprises water 87%-92%, organic salt (sodium phenol, sodium benzoate, sodium formate, sodium propionate) 3%-5%, propylene glycol 2%-4%, other organic impurities 2%-3%, and sodium hydroxide 0.9%-1.2% by weight.

[0024] Another technical solution of the present invention to solve the technical problem is as follows:

[0025] A POSM waste alkali solution concentration treatment device, the device comprises a three-effect evaporation tower T1, a second-effect evaporation tower T2, a first-effect evaporation tower T3 and a stripping tower T4;

[0026] The raw material feed pump P1 is connected to the primary raw material preheater E1 and the secondary raw material preheater E2, and then connected to the separation chamber of the triple-effect evaporation tower T1 through pipeline 1; the top outlet of the triple-effect evaporation tower T1 is connected to the primary indirect condenser CX1, the secondary indirect condenser CX2 and the tertiary indirect condenser CX3 in sequence; the lower part of the triple-effect evaporation tower T1 is connected to the inlet of the forced circulation pump P11 through a pipeline, and the outlet of P11 is connected to the triple-effect heater E3 through a pipeline and then connected to the triple-effect separation chamber, and the tower kettle discharge port is connected to the triple-effect discharge pump P2 and the secondary feed preheater E4 in sequence and enters the separation chamber of the secondary evaporation tower T2 through pipeline 2; the primary indirect condenser CX1 enters the stripping liquid inlet tank V1 through pipeline 3; the secondary indirect condenser CX2 and the tertiary indirect condenser CX3 are respectively connected to the organic liquid tank V5, and the tertiary indirect condenser CX3 is connected to the tail gas treatment system; the organic liquid tank V5 is connected to the organic liquid pump P9 and then enters the concentrated alkali liquid tank V4;

[0027] The top gas outlet of the second-effect evaporation tower T2 is connected to the shell side of the three-effect heater E3 and then to the condensate tank V2 via pipeline 4; the lower part of the second-effect evaporation tower T2 is connected to the inlet of the forced circulation pump P12 via a pipeline, and the outlet of P12 is connected to the second-effect heater E5 via a pipeline and then to the second-effect separation chamber; the discharge port of the tower kettle is connected to the second-effect discharge pump P3 and connected to the separation chamber of the first-effect evaporation tower T3 via pipeline 5;

[0028] The top gas outlet of the first-effect evaporation tower T3 is connected to the shell side of the second-effect heater E5 and then to the condensate tank V2 through pipeline 4; the lower part is connected to the inlet of the forced circulation pump P13 through a pipeline, and the outlet of P13 is connected to the first-effect heater E6 through a pipeline and then to the first-effect separation chamber; the tower kettle outlet is connected to the concentrated alkali liquid tank V4 through pipeline 6; the outlet of the condensate tank V2 is connected to the top reflux ports of the second-effect evaporation tower T2 and the first-effect evaporation tower T3 respectively through the secondary condensate reflux pump P8, and the other way is connected to the stripping feed tank V1 through pipeline 3; the stripping feed tank V1 is connected to the stripping tower T4 through the stripping feed pump P4.

[0029] One gas outlet at the top of the stripping tower T4 is connected to the start-up condenser CX4, and the other gas outlet is connected to the shell side of the second-effect feed preheater E4 and the shell side of the secondary raw material preheater once, and then connected to the reflux tank V3 through pipeline 7, and the start-up condenser CX4 is connected to the reflux tank V3; one gas outlet of the reflux tank V3 is connected to the top reflux pump P5 and connected to the top of the stripping tower T4, and one gas outlet is connected to the concentrated alkali liquid tank V4 through the top condensate recooler CX5 and the condensate discharge pump P6; one gas outlet at the bottom of the tower is connected to the stripping tower reboiler E7 and then to the stripping tower bottom, and one gas outlet at the bottom of the tower is connected to the stripping tower liquid discharge pump P7 through the shell side of the primary raw material preheater E1 to the condensate recooler CX6 to be sent to the biochemical treatment system.

[0030] The three-effect evaporation tower T1 includes a gas-liquid separation chamber, a rectification section and a condenser from bottom to top. filler The theoretical number of plates is 8-12. The condenser is connected to the distillation section through a flange, and the condensate is directly refluxed to the packing layer of the distillation section. The feed port is set in the middle of the separation chamber.

[0031] The second-effect evaporation tower T2 includes a gas-liquid separation chamber and a distillation section. A structured packing is installed in the distillation section, and the number of theoretical plates is 10-14. A liquid distributor is arranged on the upper part of the packing layer, and the reflux port is arranged above the distributor. The feed port is arranged in the middle of the separation chamber.

[0032] The first-effect evaporation tower T3 includes a gas-liquid separation chamber and a distillation section. A structured packing is installed in the distillation section, and the number of theoretical plates is 10-16. A liquid distributor is arranged on the upper part of the packing layer, and the reflux port is arranged above the distributor. The feed port is arranged in the middle of the separation chamber.

[0033] Stripping tower T4 is a packed tower with structured packing inside. The theoretical number of plates is 35-45, the feed is at 7-12 plates, and the reflux port is at the top of the reflux distributor.

[0034] The three-effect evaporation tower T1, the two-effect evaporation tower T2, and the one-effect evaporation tower T3 contain a rectification section and a partial condenser reflux;

[0035] The outlet of the raw material feed pump P1 is provided with a flow meter;

[0036] The outlet of the organic liquid tank V5 is provided with a liquid level regulating valve;

[0037] The three-effect discharge pump P2, the two-effect discharge pump P3 and the one-effect discharge pipeline are provided with a liquid level regulating valve;

[0038] The beneficial effects of the present invention are as follows:

[0039] In the current industrial incineration treatment of waste alkali liquid, the cost of incineration treatment is too high due to the large amount of waste alkali liquid and high water content. The impurity composition and content of the waste alkali liquid produced under different processes are different. In the process of simple evaporation or stripping, the top gas phase contains not only light components, but also components that azeotropize with water. At the same time, some heavy components are entrained with the top gas phase, resulting in the COD of the top gas phase being too high, reaching 160,000-200,000 mg / L, resulting in excessively high water treatment costs. In addition, the high content of heavy components will solidify and aggregate in the pipeline after cooling, which is easy to block the pipeline and cause corrosion to the pipeline.

[0040] The invention is scientifically and reasonably designed, adopts the technical process of "three-effect forced circulation evaporation + stripping", evaporates first and then strips, and each effect evaporator contains a distillation section inside, which can effectively control the volatilization and entrainment of heavy components; the three-effect evaporator adopts three-stage indirect condensation to adjust the gas phase fraction, effectively separates the condensate and the organic non-condensable gas, and reduces the COD value of the water phase; the three-effect evaporator adopts three-effect forced circulation evaporation, and each effect evaporator distills the concentrated liquid of the previous effect evaporation again, and uses the distillation section added on the separation chamber and the reflux liquid of the condenser to control the entrainment of heavy components; because the POSM waste alkali liquid contains more benzene impurities, most of which produce azeotropy with water and are extracted with water, so a pressurized operation is adopted in the stripping section to increase the content of these impurities in the azeotropic composition, reduce the water content, and thus reduce the energy consumption of incineration treatment; the concentrated liquid is extracted from the first effect, the temperature is high and the material viscosity is low, and it is not easy to block the pipeline and the incineration nozzle.

[0041] When simply evaporated and concentrated, the COD value of the evaporation condensate is as high as 20000-50000 mg / L. The process of the present invention can effectively reduce the COD value of the waste liquid to 1000-5000 mg / L, reduce the amount of waste alkali liquid after concentration by 30%, and reduce the consumption of incineration fuel by 30%. The present invention also adopts thermal coupling technology, and the gas phase at the top of the stripping tower exchanges heat with the raw materials to reduce the steam consumption in the evaporation process. According to the calculation of processing 30 tons of waste alkali liquid per hour, 3-3.8t / h of steam is saved, and 180t / h of circulating water consumption of the stripping tower is saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A diagram of a POSM waste alkali liquid concentration device;

[0043] In the figure, T1: three-effect evaporation tower; T2: two-effect evaporation tower; T3: one-effect evaporation tower; T4: stripping tower

[0044] E1: primary raw material preheater; E2: secondary raw material preheater; E3: three-effect heater; E4: secondary feed preheater; E5: secondary heater; E6: primary heater; E7: stripping tower reboiler; CX1: primary indirect condenser; CX2: secondary indirect condenser; CX3: tertiary indirect condenser; CX4: start-up condenser; CX5: tower top condensate recooler; CX6: recooler; P1: raw material feed pump; P2: three-effect outlet Feed pump; P3: Second effect discharge pump; P4: Stripping feed pump; P5: Tower top reflux pump; P6: Condensate discharge pump; P7: Stripping kettle liquid discharge pump; P8: Secondary condensate reflux pump; P9: Organic liquid pump; P10: Concentrated alkali liquid discharge pump; P11: Three effect circulation pump; P12: Second effect circulation pump; P13: First effect circulation pump; V1: Stripping feed tank; V2: Condensate tank; V3: Reflux tank; V4: Concentrated alkali liquid tank; V5: Organic liquid tank; DETAILED DESCRIPTION

[0045] The following is combined with Figure 1 The present invention is further described by examples. However, the following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited by them.

[0046] like Figure 1 As shown, the POSM waste alkali solution concentration treatment device of the present invention comprises a three-effect evaporation tower T1, a second-effect evaporation tower T2, a first-effect evaporation tower T3 and a stripping tower T4;

[0047] The raw material feed pump P1 is connected to the primary raw material preheater E1 and the secondary raw material preheater E2, and then connected to the separation chamber of the triple-effect evaporation tower T1 through pipeline 1; the top outlet of the triple-effect evaporation tower T1 is connected to the primary indirect condenser CX1, the secondary indirect condenser CX2 and the tertiary indirect condenser CX3 in sequence; the lower part of the triple-effect evaporation tower T1 is connected to the inlet of the forced circulation pump P11 through a pipeline, and the outlet of P11 is connected to the triple-effect heater E3 through a pipeline and then connected to the triple-effect separation chamber (material forced circulation heating evaporation), and the tower kettle discharge port is connected to the triple-effect discharge pump P2 and the secondary feed preheater E4 in sequence and enters the separation chamber of the secondary evaporation tower T2 through pipeline 2; the primary indirect condenser CX1 enters the stripping liquid inlet tank V1 through pipeline 3; the secondary indirect condenser CX2 and the tertiary indirect condenser CX3 are respectively connected to the organic liquid tank V5, and the tertiary indirect condenser CX3 is connected to the tail gas treatment system; the organic liquid tank V5 is connected to the organic liquid pump P9 and then enters the concentrated alkali liquid tank V4;

[0048] The top gas outlet of the second-effect evaporation tower T2 is connected to the shell side of the three-effect heater E3 and then to the condensate tank V2 via pipeline 4; the lower part of the second-effect evaporation tower T2 is connected to the inlet of the forced circulation pump P12 via a pipeline, and the outlet of P12 is connected to the second-effect heater E5 via a pipeline and then to the second-effect separation chamber; the discharge port of the tower kettle is connected to the second-effect discharge pump P3 and connected to the separation chamber of the first-effect evaporation tower T3 via pipeline 5;

[0049] The top gas outlet of the first-effect evaporation tower T3 is connected to the shell side of the second-effect heater E5 and then to the condensate tank V2 through pipeline 4; the lower part is connected to the inlet of the forced circulation pump P13 through a pipeline, and the outlet of P13 is connected to the first-effect heater E6 through a pipeline and then to the first-effect separation chamber; the tower kettle outlet is connected to the concentrated alkali liquid tank V4 through pipeline 6; the outlet of the condensate tank V2 is connected to the top reflux ports of the second-effect evaporation tower T2 and the first-effect evaporation tower T3 respectively through the secondary condensate reflux pump P8, and the other way is connected to the stripping feed tank V1 through pipeline 3; the stripping feed tank V1 is connected to the stripping tower T4 through the stripping feed pump P4.

[0050] One gas outlet of the top of the stripping tower T4 is connected to the start-up condenser CX4, and the other gas outlet is connected to the shell side of the second-effect feed preheater E4 and the shell side of the secondary raw material preheater once, and then connected to the reflux tank V3 through pipeline 7, and the start-up condenser CX4 is connected to the reflux tank V3; one gas outlet of the reflux tank V3 is connected to the top reflux pump P5 and connected to the top of the stripping tower T4, and one gas outlet is connected to the concentrated alkali liquid tank V4 through the top condensate recooler CX5 and the condensate discharge pump P6; one gas outlet of the tower kettle is connected to the stripping tower reboiler E7 and then connected back to the stripping tower kettle, and one gas outlet of the tower kettle is connected to the stripping kettle liquid discharge pump P7 through the shell side of the primary raw material preheater E1 to the condensate recooler CX6 to be sent to the biochemical treatment system.

[0051] The triple-effect evaporation tower T1 includes a gas-liquid separation chamber, a distillation section and a condenser from bottom to top. A structured packing is installed in the distillation section, and the number of theoretical plates is 8-12. The condenser is connected to the distillation section through a flange, and the condensate is directly refluxed to the packing layer of the distillation section. The feed port is set in the middle of the separation chamber.

[0052] The second-effect evaporation tower T2 includes a gas-liquid separation chamber and a distillation section. A structured packing is installed in the distillation section, and the number of theoretical plates is 10-14. A liquid distributor is arranged on the upper part of the packing layer, and the reflux port is arranged above the distributor. The feed port is arranged in the middle of the separation chamber.

[0053] The first-effect evaporation tower T3 includes a gas-liquid separation chamber and a distillation section. A structured packing is installed in the distillation section, and the number of theoretical plates is 10-16. A liquid distributor is arranged on the upper part of the packing layer, and the reflux port is arranged above the distributor. The feed port is arranged in the middle of the separation chamber.

[0054] Stripping tower T4 is a packed tower with structured packing inside. The theoretical number of plates is 35-45, the feed is at 7-12 plates, and the reflux port is at the top of the reflux distributor.

[0055] The three-effect evaporation tower T1, the two-effect evaporation tower T2, and the one-effect evaporation tower T3 contain a rectification section and a partial condenser reflux;

[0056] The outlet of the raw material feed pump P1 is provided with a flow meter;

[0057] The outlet of the organic liquid tank V5 is provided with a liquid level regulating valve;

[0058] The three-effect discharge pump P2, the two-effect discharge pump P3 and the one-effect discharge pipeline are provided with a liquid level regulating valve;

[0059] In the triple-effect evaporation tower T1, the separation chamber is Φ2800×5000mm / distillation section is DN1000×6000mm, filled with 5m250Y structured packing, and the dephlegmator is 40m 2 DN800×1500mm;

[0060] In the second-effect evaporation tower T2, the separation chamber is Φ2400×4500mm / distillation section is DN900×6000mm, and is filled with 5m250Y structured packing;

[0061] In the first-effect evaporation tower T3, the separation chamber is Φ2200×4500mm / distillation section is DN900×6000mm, and is filled with 5m250Y structured packing;

[0062] In the stripping tower T4, Φ1000×26000mm, 3m500Y structured packing and 15m250Y structured packing are installed;

[0063] In the described process:

[0064] The waste alkali liquid is sent by the raw material feed pump P1 to the primary raw material preheater E1 and the secondary raw material preheater E2 for preheating, and then enters the three-effect evaporation tower T1 for forced circulation evaporation. The entrainment and volatilization of organic heavy components are controlled by the distillation section and the reflux of the condenser on the separation chamber in the tower; the secondary gas is condensed by the primary indirect condenser CX1 and enters the condensate tank V2, the non-condensable gas is concentrated organic light components and enters the secondary indirect condenser CX2 for condensation, the remaining non-condensable gas is deep-cooled by the tertiary indirect condenser CX3, the condensate of the secondary indirect condenser CX2 and the tertiary indirect condenser CX3 enters the organic liquid tank V5, the organic liquid wastewater is pumped to the concentrated alkali liquid storage tank V4 by the organic liquid pump, and the non-condensable gas is sent to the tail gas treatment system by the vacuum pump.

[0065] After the three-effect concentration, the alkali liquor is sent to the second-effect feed preheater E4 through the three-effect discharge pump P2, and then enters the second-effect evaporation tower T2 after heat exchange with the stripping steam; the alkali liquor from the three-effect concentration is forced to circulate and evaporate in the second-effect heating chamber, and the entrainment and volatilization of the organic heavy components are controlled by the distillation section on the separation chamber and the reflux of part of the evaporated condensate. The secondary gas enters the shell side of the three-effect heating chamber E3 as a heat source, and the concentrated alkali liquor is sent to the first-effect evaporation tower T3 through the second-effect discharge pump P3.

[0066] The alkali liquor from the second effect concentration is sent to the first effect evaporation tower T3 through the second effect discharge pump P3, and is forced to circulate and evaporate after being heated in the first effect heating chamber E6. The entrainment and volatilization of organic heavy components are controlled by the distillation section on the separation chamber and the reflux of part of the evaporated condensate. The secondary gas separated by the first effect separation chamber enters the second effect heating chamber E5 as the evaporation heat source. The concentrated alkali liquor flows to the concentrated alkali liquor storage tank V4 by the liquid level difference, and is sent to the incinerator for incineration through the concentrated alkali liquor discharge pump P10.

[0067] The evaporation condensate of the first and second effects enters the stripping liquid inlet tank V1, and part of it is refluxed by the condensate pump to the first-effect evaporation tower T3 and the second-effect evaporation tower T2 distillation section to control the entrainment and volatilization of organic heavy components, and the rest is sent to the stripping liquid inlet tank V1 of the stripping section to remove organic components and further remove organic matter.

[0068] The secondary gas condensate of the evaporation section and the condensate of the primary indirect condenser are used as raw materials. The condensate of the stripping liquid inlet tank V1 is sent to the middle and upper part of the stripping tower T4 by the stripping feed pump P4, and the organic components are removed by stripping under high pressure. The top gas phase is condensed by thermal coupling with the evaporation section and then enters the reflux tank V3 (the top gas phase exchanges heat with the secondary feed preheater E2 of the evaporation section, and the liquid phase returns to the reflux tank of the stripping section after heat exchange). In the reflux tank V3, it is divided into water phase and organic phase. The water phase is sent to the top of the distillation tower by the reflux pump P5 for reflux, and the organic phase is condensed by the top condensate recooler CX5 and sent to the concentrated alkali liquid storage tank V4, and then sent to the incinerator for incineration through the concentrated alkali liquid pump P10. The qualified bottom liquid of the tower is sent to the primary raw material preheater E1 of the evaporation section to preheat the raw material and the recooler CX6 to cool it before going to biochemical treatment.

[0069] Example 1

[0070] The following description is made by taking the treatment of 30.08 tons of POSM waste alkali liquor per hour as an example.

[0071] The POSM waste alkali solution comprises 90% water, 3.5% organic salt (sodium phenol, sodium benzoate, sodium formate, sodium propionate), 3% propylene glycol, 2.5% other organic impurities and 1% sodium hydroxide in percentage by weight;

[0072] A POSM waste alkali liquid concentration process, the POSM waste liquid from the reaction zone has a temperature of 25°C, is preheated (126.5°C) by a primary raw material preheater E1 and a secondary raw material preheater E2, and then enters a three-effect evaporation tower T1 for forced circulation evaporation, the feed rate is 30.08 t / h, the three-effect evaporation tower T1 has 10 theoretical plates, 9 feed positions, an operating pressure of 80 Kpa, a gas phase extraction temperature of 93.1°C, a tower bottom temperature of 94.7°C, a reflux ratio of 0.1, and the gas phase is condensed by a primary indirect condenser CX1 and then enters a condensate tank V2, the flow rate is 7.16 t / h, and the non-condensable gas The concentrated organic light components are condensed in the secondary indirect condenser CX2, and the remaining (2.6%) non-condensable gas is deep-cooled (-12°C) by the tertiary indirect condenser CX3. The condensate (organic liquid wastewater) of the secondary indirect condenser CX2 and the tertiary indirect condenser CX3 enters the organic liquid tank V5 (the components are: water, propylene oxide, benzaldehyde, propylene glycol), with a flow rate of 0.429t / h. The organic liquid wastewater (water, propylene oxide, benzaldehyde, propylene glycol) is sent to the concentrated alkali solution storage tank V4 through the organic liquid pump P9, and the non-condensable gas (propylene oxide) is sent to the tail gas treatment system by the vacuum pump, with a flow rate of 0.001t / h;

[0073] The alkali liquor after three-effect concentration is sent to the second-effect feed preheater E4 through the three-effect discharge pump P2, and then enters the second-effect evaporation tower T2 after heat exchange with the stripping steam. The feed rate is 22.49t / h, the feed temperature is 124.5℃, the theoretical plate number of the second-effect evaporation tower T2 is 10, the feed position is 9, the operating pressure is 135Kpa, the gas phase extraction temperature is 108.2℃, the tower kettle temperature is 110℃, the reflux ratio is 0.15, and the alkali liquor from the three-effect concentration is intensively heated in the second-effect heating chamber. Circulation evaporation is carried out to control the entrainment and volatilization of organic heavy components through the rectification section on the separation chamber and the reflux of part of the evaporated condensate. At this time, the water content in the gas phase is 99.6%, and the gas phase flow rate is 6.65t / h. The concentrated alkali solution (85.9% water, 5.8% propylene glycol, 0.4% phenylethyl alcohol, and the rest are organic salts (sodium phenol, sodium benzoate, sodium formate, sodium propionate) and organic impurities) is sent to the first-effect evaporation tower T3 through the second-effect discharge pump P3, and the flow rate is 15.84t / h;

[0074] The alkali liquor from the second effect concentration is sent to the first effect evaporation tower T3 through the second effect discharge pump P3. The feed temperature is 110.3℃, the feed amount is 15.84t / h, the theoretical plate number of the first effect evaporation tower T3 is 10, the feed position is 9, the operating pressure is 220Kpa, the gas phase extraction temperature is 123.3℃, ​​the gas phase flow rate is 7.26t / h, the tower kettle temperature is 127.2℃, the reflux ratio is 0.2, and the alkali liquor from the second effect concentration is sent to the first effect heating chamber E6 After heating, forced circulation evaporation is carried out, and the entrainment and volatilization of organic heavy components are controlled by the rectification section on the separation chamber and the reflux of part of the evaporated condensate. The concentrated alkali solution (composed of: 74% water, 10.6% propylene glycol, 0.8% phenylethyl alcohol, and the remaining organic salts (sodium phenol, sodium benzoate, sodium formate, sodium propionate) and organic impurities) flows to the concentrated alkali solution storage tank V4 by gravity through the liquid level difference, with a flow rate of 8.58t / h, and is sent to the incinerator for incineration through the concentrated alkali solution discharge pump P10;

[0075] The secondary gas condensate of the evaporation section and the condensate of the primary indirect condenser are used as raw materials (composition: 98.9% water, 0.2% propylene oxide, 0.5% benzaldehyde, 0.1% acetophenone, and the rest are organic salts and organic impurities). The condensate of the stripping liquid inlet tank V1 is sent to the middle and upper part of the stripping tower T4 by the stripping feed pump P4. The feed temperature is 106.1°C, the feed rate is 21.08t / h, the theoretical plate number of the stripping tower T4 is 40, the feed position is 10, and the operating pressure is 3 00Kpa, gas phase extraction temperature is 115.3℃, tower bottom temperature is 133.9℃, reflux ratio is 3.4, raw materials are stripped under high pressure to remove organic components, the top gas phase is condensed by thermal coupling with the evaporation section and then enters the reflux tank V3, and is sent to the top of the distillation tower by the reflux pump P5 for partial reflux, and the rest is sent to the concentrated alkali liquid storage tank V4 as organic liquid wastewater after condensation by the tower top condensate recooler CX5, with a flow rate of 1t / h, and then sent to the incinerator for incineration through the concentrated alkali liquid pump P10. The qualified tower bottom liquid (water content 99.9%) is sent to the evaporation section primary raw material preheater E1 to preheat the raw material and the recooler CX6 to cool it and then go to biochemical treatment, with a flow rate of 20.08t / h.

[0076] In the above example, the POSM waste alkali liquor is concentrated through the process of three-effect forced circulation evaporation + stripping. The water content in the second-effect evaporation condensate and the first-effect evaporation condensate reaches more than 99.6%, and the water content of the condensate after stripping also reaches more than 99.9%. The water content of the waste liquid sent to incineration treatment is reduced to less than 75%, and the flow rate is reduced to 10t / h per hour. The flow rate of water in the incineration waste liquid is reduced by 5-7.5t / h, and the water gasification cost is reduced by 1,000 yuan / h, which greatly reduces the cost of incineration treatment.

[0077] Example 2

[0078] The other steps are the same as those in Example 1, except that the feed rate is changed from 30 t / h to 33 t / h, the reflux ratio of the three-effect evaporation tower T1 is changed from 0.1 to 0.3, the operating pressure is changed from 80 Kpa to 90 Kpa, the gas phase temperature is changed from 93.1°C to 96.3°C, and the kettle temperature is changed from 94.7°C to 97.9°C; the reflux ratio of the second-effect evaporation tower T2 is changed from 0.15 to 0.5, the operating pressure is changed from 135 Kpa to 150 Kpa, the gas phase temperature is changed from 108.2°C to 111.4°C, and the kettle temperature is changed from 110°C to 113.1°C; the reflux ratio of the first-effect evaporation tower T3 is changed from 0.2 to 0.5 , the operating pressure changed from 220Kpa to 240Kpa, the gas phase temperature changed from 123.3℃ to 126.1℃, and the bottom temperature changed from 127.2℃ to 130℃; the reflux ratio of the stripping tower T4 changed from 3.4 to 3.6, the operating pressure changed from 300Kpa to 320Kpa, the gas phase temperature changed from 115.3℃ to 117.7℃, and the bottom temperature changed from 133.9℃ to 136.1℃; the water content in the second-effect evaporation condensate and the first-effect evaporation condensate reached more than 99.6%, and the water content of the bottom liquid after stripping also reached more than 99.9%, and the water content of the waste liquid to be treated by biochemical treatment was reduced to below 75%.

[0079] Comparative Example 1

[0080] Similarly, 30 tons of POSM waste alkali liquid is treated per hour by using a stripping + three-effect circulating evaporation device (excluding the distillation section. The upper part of the feed inlet of the distillation tower is called the distillation section, and the lower part of the feed inlet is called the stripping section. That is, the upper part of the feed inlet of the three separation chambers is not equipped with separation fillers, which only has the function of simple gas-liquid separation and has no function of controlling organic heavy components). The pressure in the tower is adjusted and the concentrated product is obtained through normal operation.

[0081] The water content in the evaporation condensate in Comparative Example 1 is 99.4%, which is less than the 99.9% water content of the condensate after stripping in Example 1. The heavy component is higher than that in Example 1, and the water content of the concentrated liquid in Comparative Example 1 is 87%, and the flow rate is 17.5 t / h, while that in Example 1 is less than 75%, and the flow rate is 10 t / h. The water content in Example 1 is significantly reduced and the processing volume is low. Example 1 can significantly reduce the cost of incineration treatment.

[0082] Matters not covered by the present invention are known technologies.

Claims

1. A POSM waste alkali liquor concentration process, characterized in that The process includes the following steps: The waste alkali liquid is pumped by the raw material feed pump to the primary raw material preheater, and then preheated in the secondary raw material preheater and enters the three-effect evaporation tower for forced circulation evaporation. The reflux liquid obtained by the distillation section and the partial condenser on the separation chamber is refluxed into the tower; The condensate obtained after the secondary gas is condensed by the first-stage indirect condenser enters the stripping liquid inlet tank, and the non-condensable gas enters the second-stage indirect condenser for condensation to obtain concentrated organic light components; the remaining non-condensable gas is deep-cooled (-15℃~-10℃) by the third-stage indirect condenser, and the condensate of the second-stage indirect condenser and the third-stage indirect condenser enters the organic liquid tank, the organic liquid wastewater is pumped to the concentrated alkali liquid storage tank by the organic liquid pump, and the non-condensable gas is pumped to the tail gas treatment system by the vacuum pump; The operating pressure of the triple-effect evaporation tower is 70-90Kpa, the reflux ratio of the partial condenser is 0.05-0.3, the gas phase extraction temperature is 89.5°C-96.3°C, and the tower bottom temperature is 91.1°C-97.9°C; After the three-effect concentration, the alkali liquor is pumped to the second-effect feed preheater through the three-effect discharge pump, and then enters the second-effect evaporation tower after heat exchange with the stripping steam (the outlet temperature of the material of the second-effect feed preheater is in the range of 120.9°C-127.6°C); the alkali liquor from the three-effect concentration is forced to circulate and evaporate in the second-effect heater, and the condensate containing heavy components obtained by the distillation section on the separation chamber and part of the evaporated condensate is refluxed into the tower, and the secondary gas (104.8°C-111.4°C) enters the shell side of the three-effect heating chamber as a heat source, and the condensate enters the condensate tank; the concentrated alkali liquor is pumped to the first-effect evaporation tower through the second-effect discharge pump; The operating pressure of the second-effect evaporation tower is 120-150Kpa, the reflux ratio is 0.1-0.5; the gas phase extraction temperature is 104.8°C-111.4°C, and the tower bottom temperature is 106.5°C-113.1°C; The alkali liquor from the second effect concentration is pumped to the first effect evaporation tower through the second effect discharge pump, and is heated by the first effect heater (124.1℃-130℃) and forced to circulate and evaporate. The condensate containing heavy components obtained by the distillation section on the separation chamber and part of the evaporated condensate is refluxed into the tower. The secondary gas separated by the first effect separation chamber enters the second effect heating chamber (106.5℃-113.1℃) as an evaporation heat source. The concentrated alkali liquor flows to the concentrated alkali liquor storage tank by the liquid level difference, and is pumped to the incinerator for incineration through the concentrated alkali liquor discharge pump; The operating pressure of the first-effect evaporation tower is 200-240Kpa, the reflux ratio is 0.15-0.5, the gas phase extraction temperature is 120.2°C-126.1°C, and the tower bottom temperature is 124.1°C-130°C; The condensate from the stripping liquid inlet tank is pumped to the middle and upper part of the stripping tower by the stripping feed pump, and the organic components are removed by stripping under pressure. The gas phase at the top of the tower is condensed by thermal coupling with the evaporation section and then enters the reflux tank, where it is divided into water phase and organic phase. The water phase is pumped to the top of the stripping tower by the reflux pump for reflux, and the organic phase is condensed by the top condensate recooler and then sent to the concentrated alkali liquid storage tank, and then sent to the incinerator for incineration by the concentrated alkali liquid pump; the qualified tower bottom liquid is pumped to the primary raw material preheater of the evaporation section by the discharge pump to preheat the raw material and the recooler to cool it before going to biochemical treatment; The operating pressure of the stripping tower is 280-320 Kpa, the reflux ratio is 3-3.6, the gas phase extraction temperature is 112.8°C-117.7°C, and the tower bottom temperature is 131.6°C-136.1°C.

2. POSM waste alkali liquor concentration process as claimed in claim 1, is characterized in that described POSM waste alkali liquor composition mass percent comprises water 87%-92%, organic salt (sodium phenolate, sodium benzoate, sodium formate, sodium propionate) 3%-5%, propylene glycol 2%-4%, other organic impurities 2%-3%, sodium hydroxide 0.9%-1.2%.

3. POSM waste alkali liquor concentration process as claimed in claim 1, is characterized in that In the triple-effect evaporation tower, the operating pressure is 80Kpa and the reflux ratio is 0.1; In the second-effect evaporation tower, the operating pressure is 135Kpa and the reflux ratio is 0.15; In the first-effect evaporation tower, the operating pressure is 200 Kpa and the reflux ratio is 0.2; In the stripping tower, the operating pressure is 300 Kpa and the reflux ratio is 3.

4.

4. The POSM waste alkali liquor concentration process as claimed in claim 1, wherein the waste alkali liquor has a material outflow temperature range of 79.6°C-82.8°C from the primary raw material preheater and a material outflow temperature range of 125.1°C-127.7°C from the secondary raw material preheater.

5. A POSM waste alkali solution concentration treatment device, characterized in that the device comprises a triple-effect evaporation tower, a second-effect evaporation tower, a first-effect evaporation tower and a stripping tower; The raw material feed pump is connected to the primary raw material preheater and the secondary raw material preheater and then connected to the separation chamber of the triple-effect evaporation tower through a pipeline; the top outlet of the triple-effect evaporation tower is connected to the primary indirect condenser, the secondary indirect condenser and the tertiary indirect condenser in sequence; the lower part of the triple-effect evaporation tower is connected to the inlet of the forced circulation pump through a pipeline, the outlet of the forced circulation pump is connected to the triple-effect heater through a pipeline and then connected to the triple-effect separation chamber, the tower kettle outlet is connected to the triple-effect discharge pump and the secondary feed preheater in sequence and enters the separation chamber of the secondary evaporation tower through a pipeline; the primary indirect condenser CX1 enters the stripping liquid inlet tank through a pipeline; the secondary indirect condenser and the tertiary indirect condenser are respectively connected to the organic liquid tank, and the tertiary indirect condenser is connected to the tail gas treatment system; the organic liquid tank is connected to the organic liquid pump and then enters the concentrated alkali liquid tank; The top outlet of the second-effect evaporation tower is connected to the shell side of the three-effect heater and then to the condensate tank through a pipeline; the lower part of the second-effect evaporation tower is connected to the inlet of the forced circulation pump through a pipeline, and the outlet of the forced circulation pump is connected to the second-effect heater through a pipeline and then to the second-effect separation chamber; the discharge port of the tower kettle is connected to the second-effect discharge pump and connected to the separation chamber of the first-effect evaporation tower through a pipeline; The top gas outlet of the first-effect evaporation tower is connected to the shell side of the second-effect heater and then to the condensate tank through a pipeline; the lower part is connected to the inlet of the forced circulation pump through a pipeline, and the outlet of the forced circulation pump is connected to the first-effect heater through a pipeline and then to the first-effect separation chamber; the tower kettle outlet is connected to the concentrated alkali liquid tank through a pipeline; one way of the condensate tank outlet is connected to the top reflux ports of the second-effect evaporation tower and the first-effect evaporation tower respectively through the secondary condensate reflux pump, and the other way is connected to the stripping feed tank through a pipeline; the stripping feed tank is connected to the stripping tower through the stripping feed pump; One gas outlet at the top of the stripping tower is connected to the start-up condenser, and the other gas is connected to the shell side of the second-effect feed preheater and the shell side of the secondary raw material preheater, and then connected to the reflux tank through a pipeline, and the start-up condenser is connected to the reflux tank; one gas outlet of the reflux tank is connected to the top reflux pump to the top of the stripping tower, and one gas outlet is connected to the concentrated alkali liquid tank through the top condensate recooler and the condensate discharge pump; one gas outlet of the tower kettle is connected to the stripping tower reboiler and then back to the stripping tower kettle, and one gas outlet of the tower kettle is connected to the stripping kettle liquid outlet pump, and then connected to the condensate recooler through the shell side of the first raw material preheater to the biochemical treatment system.

6. The POSM waste alkali liquid concentration treatment device as claimed in claim 5 is characterized in that the triple-effect evaporation tower comprises a gas-liquid separation chamber, a rectifying section and a partial condenser from bottom to top, a packing is installed in the rectifying section, the number of theoretical plates is 8-12, the partial condenser is connected to the rectifying section by a flange, and the condensate is directly refluxed to the rectifying section packing layer. The feed port is arranged in the middle of the separation chamber; The two-effect evaporation tower includes a gas-liquid separation chamber and a distillation section. The distillation section is equipped with structured packing, with a theoretical plate number of 10-14. A liquid distributor is arranged on the upper part of the packing layer, and the reflux port is arranged above the distributor. The feed port is arranged in the middle of the separation chamber; The first-effect evaporation tower includes a gas-liquid separation chamber and a distillation section. A structured packing is installed in the distillation section, and the number of theoretical plates is 10-16. A liquid distributor is arranged on the upper part of the packing layer, and the reflux port is arranged above the distributor; the feed port is arranged in the middle of the separation chamber; The stripping tower is a packed tower with structured packing inside. The theoretical number of plates is 35-45, the feed plate is 7-12, and the reflux port is at the top of the reflux distributor.

7. POSM waste alkali solution concentration treatment device as claimed in claim 5, characterized in that The three-effect evaporation tower, the two-effect evaporation tower and the one-effect evaporation tower contain a rectification section and a partial condenser reflux; The outlet of the raw material feed pump is provided with a flow meter; The outlet of the organic liquid tank is provided with a liquid level regulating valve; The three-effect discharge pump, the two-effect discharge pump and the one-effect discharge pipeline are provided with liquid level regulating valves.

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