Solvent recovery gas-liquid-solid separation system for brominated polystyrene

Abstract

The utility model relates to a gas-liquid-solid separation system for solvent recovery of brominated polystyrene, which is characterized in that the bottom of a flash distillation kettle is connected with a flash distillation material transfer kettle, a deionized water storage tank is respectively connected with the flash distillation kettle and a gas-phase buffer tank in a feeding manner, and the upper part of the flash distillation kettle is connected with the middle part, the middle lower part or the lower part of the gas-phase buffer tank lower than the internal liquid level through a buffer pipe; the bottom of the gas-phase buffer tank is connected back to the top of the gas-phase buffer tank through a circulating pipe, a material pump and a bag filter are arranged on the circulating pipe, the top of the gas-phase buffer tank is connected with more than one stage of condenser, the more than one stage of condenser is connected with a tail gas discharge pipe, and the bottom of the more than one stage of condenser is connected with an oil-water separator; and the gas-phase buffer tank is provided with a heating jacket. According to the system, the water temperature in the gas-phase buffer tank is slightly higher than the boiling point of the solvent dichloromethane, so that vapor condensation of a gas-phase solvent is prevented, a product entrained by the gas phase is intercepted, and separation of the product and the solvent of an organic phase entrained by the gas phase is realized.

Description

Technical Field

[0001] The utility model relates to the field of chemical equipment, in particular to a solvent recovery gas-liquid-solid separation system for brominated polystyrene. Background Art

[0002] Brominated polystyrene is usually a brominated flame retardant made from polystyrene via bromination with a brominating agent. It has the advantages of high bromine content and thermal stability, good compatibility with flame-retardant substrates, and is not prone to precipitation and migration. It is widely used in engineering plastics such as PA, PBT and PET.

[0003] The reaction solvent of brominated polystyrene is generally a halogenated hydrocarbon. At present, the removal and recovery of solvents in China is generally done by adding the reaction liquid after washing into hot water to flash off the halogenated hydrocarbon solvent, and then recovering it through a condenser and a distillation tower. This is because during the flash evaporation of the organic phase of brominated polystyrene, a small amount of brominated polystyrene particles with a relatively fine particle size do not have time to settle and enter the flash condenser together with the gas phase of the recovered solvent, thereby blocking the tubes of the condenser; at the same time, a small amount of fine droplets of the organic phase that have not yet evaporated are entrained in the mist and enter the flash condenser together with the gas phase of the recovered solvent, so that the recovered solvent contains brominated polystyrene products, which often causes the condenser after the flash kettle to be blocked. Summary of the invention

[0004] The utility model aims to solve the problem of entrained product and organic phase in the recovered solvent gas phase during the flash evaporation of the brominated polystyrene organic phase proposed in the above background technology, and proposes a solvent recovery gas-liquid-solid separation system for brominated polystyrene.

[0005] The technical scheme of the utility model is: a solvent recovery gas-liquid-solid separation system for brominated polystyrene, comprising a flash kettle and a condenser at one level or above, the bottom of the flash kettle is connected to a flash material transfer kettle, and is characterized in that: it also comprises a deionized water storage tank, a gas phase buffer tank, a material pump and a bag filter, the deionized water storage tank is respectively supplied to the flash kettle and the gas phase buffer tank, the upper part of the flash kettle is connected to the middle part or the lower middle part or the lower part of the gas phase buffer tank below the internal liquid level through a buffer pipe, the bottom of the gas phase buffer tank is connected back to the top of the gas phase buffer tank through a circulation pipe, the circulation pipe is provided with a material pump and a bag filter, the top of the gas phase buffer tank is connected to a condenser at one level or above, the condenser at one level or above is connected to an exhaust gas discharge pipe, and the bottom of the condenser at one level or above is connected to an oil-water separator; the gas phase buffer tank is provided with a heating jacket.

[0006] Furthermore, the top of the flash kettle receives the flash liquid transfer kettle feed.

[0007] Furthermore, the bottom of the transfer kettle of the liquid to be flashed is connected to the flash kettle via a liquid outlet valve.

[0008] Furthermore, the liquid to be flashed transfer kettle is connected to the atomizing nozzle in the flash kettle.

[0009] Furthermore, the flash kettle is provided with a stirrer.

[0010] Furthermore, the heating jacket is a steam or hot water jacket.

[0011] Furthermore, the heating jacket is connected behind the flash jacket of the flash kettle.

[0012] Furthermore, the above-level condensers include two condensers connected in series, and the bottoms of the two condensers are connected to an oil-water separator.

[0013] Furthermore, the upper part of the oil-water separator is connected to a wastewater pipe, and the lower part is connected to a solvent recovery tank.

[0014] Furthermore, the heating temperature of the flash kettle is higher than the heating temperature of the gas phase buffer tank.

[0015] The beneficial effects of the utility model are:

[0016] 1. The water temperature in the gas phase buffer tank is slightly higher than the boiling point of the solvent dichloromethane. First, it can prevent the condensation of gas phase solvent vapor; second, it can intercept the products entrained by the gas phase; third, it can realize the separation of the organic phase entrained by the gas phase from the product and the solvent. The solvent rises to solvent vapor when heated and enters the condenser, and the product is intercepted by the water layer. Therefore, the gas phase buffer tank can effectively prevent the gas phase entrainment from causing the subsequent condenser tube blockage.

[0017] 2. The bag filter connected to the gas phase buffer tank can recover the brominated polystyrene product in the water of the gas phase buffer tank in real time. First, it can avoid the loss of the product; second, it can avoid excessive solid content that reduces the efficiency of the gas phase buffer tank; third, too high solid-liquid ratio may also cause the solid product to be carried into the subsequent condenser by steam.

[0018] 3. Since the boiling point of dichloromethane is only 39.8℃ under normal pressure, the two-stage condenser can effectively and completely condense dichloromethane with a lower boiling point. The first-stage condenser uses normal temperature circulating water for preliminary condensation, and the second-stage condenser performs low-temperature condensation, which reduces energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the utility model.

[0020] In the figure: deionized water storage tank 1, flash liquid transfer kettle 2, flash kettle 3, flash material transfer kettle 4, gas phase buffer tank 5, material pump 6, bag filter 7, primary condenser 8, secondary condenser 9, oil-water separator 10, solvent recovery tank 11, buffer pipe 12, flash kettle heating jacket 13, buffer tank heating jacket 14, circulation pipe 15, tail gas discharge pipe 16, waste water pipe 17, liquid outlet valve 18, atomizing nozzle 19. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0022] Figure 1 As shown: a solvent recovery gas-liquid-solid separation system for brominated polystyrene, including a deionized water storage tank 1, a flash liquid transfer kettle 2, a flash kettle 3, a flash material transfer kettle 4, a gas phase buffer tank 5, a material pump 6, a bag filter 7, a primary condenser 8, a secondary condenser 9, an oil-water separator 10, a solvent recovery storage tank 11, a buffer pipe 12, a flash kettle heating jacket 13, a buffer tank heating jacket 14, a circulation pipe 15, an exhaust pipe 16, and a waste water pipe 17. The flash liquid transfer kettle 2 is fed to the upper part of the flash kettle 3, the bottom of the flash kettle 3 is connected to the flash material transfer kettle 4, the deionized water storage tank 1 is respectively fed to the flash kettle 3 and the gas phase buffer tank 5, the upper part of the flash kettle 3 is connected to the middle part or the lower middle part or the lower part of the gas phase buffer tank 5 below the internal liquid level through the buffer pipe 12, the bottom of the gas phase buffer tank 5 is connected back to the top of the gas phase buffer tank 5 through the circulation pipe 15, the circulation pipe 15 is provided with a material pump 6 and a bag filter 7, the top of the gas phase buffer tank 7 is connected to the primary condenser 8 and the secondary condenser 9 in sequence, and then connected to the tail gas discharge pipe 16, the bottom of the primary condenser 8 and the secondary condenser 9 is connected to the oil-water separator 10, the upper part of the oil-water separator 10 is externally connected to the waste water pipe 17, and the lower part is externally connected to the solvent recovery tank 11.

[0023] In this embodiment, a stirrer is provided in the flash kettle.

[0024] In this embodiment, the flash kettle 3 is provided with a flash kettle heating jacket 13, and the gas phase buffer tank 5 is provided with a buffer tank heating jacket 14. The heating temperature of the flash kettle heating jacket 13 is higher than that of the buffer tank heating jacket 14. Based on this embodiment, the two jackets are preferably steam jackets.

[0025] In this embodiment, the flash evaporator 3 receives the flash liquid transfer kettle 2 from the top, and the bottom of the flash liquid transfer kettle 2 is connected to the atomizing nozzle 19 in the flash evaporator 3 through the liquid outlet valve 18 for efficient feeding.

[0026] The working principle of this system is: the deionized water in the deionized water tank 1 flows into from the upper middle part of the flash kettle 3 and the upper side of the gas phase buffer tank 5 by its own weight, wherein the water level in the gas phase buffer tank 5 is much higher than the pipe opening connected to the flash kettle 3 in the lower middle part. The flash kettle 3 is turned on for stirring, and the water temperature of the flash kettle 3 and the water temperature of the gas phase buffer tank 5 are heated to 80°C and 60°C respectively by steam. The liquid outlet valve 18 of the liquid transfer kettle 2 to be flashed is adjusted so that the material is sprayed into the water at a certain rate from the atomizing nozzle 19 on one side of the top of the flash kettle 3. The material contacts the high-temperature water surface, and the solvent dichloromethane is instantly vaporized. The product brominated polystyrene enters the water in the form of fine particles. During the rising process of the dichloromethane vapor, the small particles of the product and the small droplets of the liquid to be flashed are entrained and enter the middle and lower part of the gas phase buffer tank 5 from the other side of the top of the flash kettle 3. After passing through the hot water layer, the brominated polystyrene product remains in the hot water. The dichloromethane vapor enters the primary condenser 8 and the secondary condenser 9 from the top of the gas phase buffer tank 5 in turn for condensation. The condensate is collected from the bottom of the primary condenser 8 and the secondary condenser 9 into the oil-water separator 10 for separation of dichloromethane and water. The dichloromethane flows to the solvent recovery storage tank 11, and the water flows to the wastewater pool through the wastewater pipe 17. After the flash evaporation is completed, the bottom valve of the flash evaporator 3 is opened to allow the solid-liquid mixture of the brominated polystyrene product and water to flow into the flash material transfer kettle 4 by gravity for subsequent solid-liquid separation and drying. The solid-liquid ratio is determined by the liquid level of the gas phase buffer tank 5 or the observation window. When the solid-liquid ratio reaches a certain level, the bottom valve of the gas phase buffer tank 5 is opened to allow the feed liquid to circulate through the material pump 6 and the bag filter 7 for solid-liquid separation.

Claims

1. A solvent recovery gas-liquid-solid separation system for brominated polystyrene, comprising a flash kettle and a condenser at or above the first level, wherein the bottom of the flash kettle is connected to a flash material transfer kettle, characterized in that: It also includes a deionized water storage tank, a gas phase buffer tank, a material pump and a bag filter. The deionized water storage tank is respectively supplied to a flash kettle and a gas phase buffer tank. The upper part of the flash kettle is connected to the middle part, the lower middle part or the lower part of the gas phase buffer tank below the internal liquid level through a buffer pipe. The bottom of the gas phase buffer tank is connected back to the top of the gas phase buffer tank through a circulation pipe. The material pump and the bag filter are arranged on the circulation pipe. The top of the gas phase buffer tank is connected to a condenser above the first level, the condenser above the first level is connected to the exhaust gas discharge pipe, and the bottom of the condenser above the first level is connected to an oil-water separator. The gas phase buffer tank is provided with a heating jacket.

2. The solvent recovery gas-liquid-solid separation system for brominated polystyrene according to claim 1, characterized in that: The top of the flash kettle receives the flash liquid transfer kettle feed.

3. The solvent recovery gas-liquid-solid separation system for brominated polystyrene according to claim 2, characterized in that: The bottom of the liquid transfer kettle to be flashed is connected to the flash kettle via a liquid outlet valve.

4. A solvent recovery gas-liquid-solid separation system for brominated polystyrene according to claim 2 or 3, characterized in that: The liquid transfer kettle to be flashed is connected to the atomizing nozzle in the flashing kettle.

5. The solvent recovery gas-liquid-solid separation system for brominated polystyrene according to claim 1, characterized in that: The flash tank is provided with a stirrer.

6. The solvent recovery gas-liquid-solid separation system for brominated polystyrene according to claim 1, characterized in that: The heating jacket is a steam or hot water jacket.

7. The solvent recovery gas-liquid-solid separation system for brominated polystyrene according to claim 6, characterized in that: The heating jacket is connected behind the flash jacket of the flash kettle.

8. The solvent recovery gas-liquid-solid separation system for brominated polystyrene according to claim 1, characterized in that: The condensers above the first level include two condensers connected in series, and the bottoms of the two condensers are connected to an oil-water separator.

9. The solvent recovery gas-liquid-solid separation system for brominated polystyrene according to claim 1 or 8, characterized in that: The upper part of the oil-water separator is connected to a waste water pipe, and the lower part is connected to a solvent recovery tank.

10. The solvent recovery gas-liquid-solid separation system for brominated polystyrene according to claim 1, characterized in that: The heating temperature of the flash kettle is higher than the heating temperature of the gas phase buffer tank.

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