Supercritical gasification treatment device for causticizing waste liquid of epoxyalkane prepared by chlorohydrin method

Abstract

The invention relates to a supercritical gasification treatment device for causticizing waste liquid of epoxyalkane prepared by a chlorohydrin method, which is characterized in that a NaOH causticizing waste liquid pump is connected with a high-pressure pump through an oxygen dissolver and then is communicated with a heat exchanger to form a NaOH causticizing waste liquid pretreatment system; the electromagnetic heating tubular reactor is communicated with the supercritical delayed gasification reactor, two or more salt elimination lock hoppers are arranged at the bottom of the supercritical delayed gasification reactor, and a gas-liquid mixed-phase outlet in the top of the supercritical delayed gasification reactor is connected with a gas-liquid separation tank through a heat exchanger, so that the supercritical gasification system for the NaOH causticized waste liquid is formed; the supercritical gasification pressure is greater than or equal to 22.1 MPa, the gasification temperature is 400-700 DEG C, and the supercritical delayed gasification reaction time is 1-180 minutes; a preheated waste liquid outlet of the NaOH causticizing waste liquid pretreatment system is connected with an inlet of an electromagnetic heating tubular reactor of the NaOH causticizing waste liquid supercritical gasification system, and a salt discharging lock hopper at the bottom of a supercritical delayed gasification reactor is connected with a high-temperature purified water outlet of the gas-liquid separation tank, so that the causticizing waste liquid supercritical gasification full-recycling treatment device is formed. The concentration of the diluted saline water is 31.5 wt%-36.1 wt%.

Description

1. Technical Field

[0001] The invention provides a supercritical gasification treatment device for caustic waste liquid produced by the chlorohydrin process to produce alkylene oxide, and relates to the field of fine chemicals. 2. Background technology

[0002] The chlorohydrin process for producing alkylene oxide is to prepare hypochlorous acid by mixing chlorine gas and water. 2- C7 olefins react with hypochlorous acid to obtain chlorohydrins, which are then reacted with slaked lime (or caustic soda) to generate alkylene oxide, and then separated by common distillation method to obtain refined alkylene oxide. This process has been industrialized as early as 1931, and has mature production technology, short flow process, large operating load elasticity, good selectivity, low requirements for raw material purity, safe and stable production, low construction investment, and strong cost competitiveness of products. At present, about 40% of the production capacity of world propylene oxide is chlorohydrin process. However, traditional chlorohydrin process device is less environmentally friendly, and water resources and chlorine consumption are large, and the causticized wastewater containing chlorides produced is difficult to handle, pollutes the environment, and the chloric acid produced simultaneously is also more serious to the corrosion of equipment. For example, 1 ton of propylene oxide per production needs to consume about 1.5 tons of chlorine, and at least 40 tons of causticized wastewater containing a small amount of organic chlorides and more than 2 tons of CaCl2 waste residues are produced simultaneously.

[0003] In order to solve the three wastes and corrosion defects of propylene oxide produced by the chlorohydrin method, co-oxidation and direct oxidation methods have been developed at home and abroad. The co-oxidation method overcomes the shortcomings of the chlorohydrin method, such as high corrosiveness and large amount of sewage, but its disadvantages are long process flow, many raw material varieties, high propylene purity requirements, and expensive equipment costs. Propylene oxide produces a large number of co-products in the co-oxidation method. Each ton of propylene oxide must produce 2.5 tons of styrene or 2.4 tons of tert-butyl alcohol. The advantages of this process can only be shown when the market demand for propylene oxide and co-products matches; in addition, the COD of sewage produced by this method is high, and the treatment cost accounts for about 10% of the total investment. The advantages of the direct oxidation method are high conversion rate and selectivity, the amount of wastewater is only 30% of other existing technologies, and the energy consumption is 65% of the existing process; the process flow is simple and economical, the by-product is water, the environmental pollution is small, the land use is small, the factory infrastructure investment is small, and the investment can be reduced by 25%, but the technology is immature, the cost is high, and the safety is poor.

[0004] If the existing chlorohydrin process for producing alkylene oxides adopts NaOH causticization reaction, it can solve the problem of pollution treatment of chloride-containing caustic wastewater and low-cost recycling of concentrated brine, and realize closed-loop utilization of chlorine, and significantly reduce costs and water consumption, then compared with co-oxidation and direct oxidation, the chlorohydrin process for producing alkylene oxides has more development advantages. However, the existing caustic wastewater treatment processes have failed to achieve full resource utilization of caustic wastewater, and it is urgent to develop efficient, clean, low-energy consumption treatment and resource utilization processes and equipment technologies for caustic wastewater from chlorohydrin process for producing alkylene oxides, eliminate the industrial bottlenecks of high pollution and high water consumption of chlorohydrin process for producing alkylene oxides, and improve its market competitiveness. 3. Summary of the invention

[0005] The invention aims to overcome the shortcomings of the existing chlorohydrin process alkylene oxide technology in treating caustic waste liquid and invent a supercritical gasification treatment device for caustic waste liquid of alkylene oxide produced by the chlorohydrin process. After oxygen is shallowly dissolved in the NaOH caustic waste liquid by an oxygen dissolver and pumped at high pressure, it is autothermally gasified under supercritical conditions in an electromagnetic heating pipeline reactor; a supercritical delayed gasification reactor is used to strengthen the gasification reaction, so as to achieve supercritical gas-liquid mixed phase separation and salt phase separation, high-pressure lock bucket salt discharge, and high-temperature purified water waste heat recovery and recycling, thereby breaking the industrial bottleneck of high water consumption and high pollution caustic waste liquid of alkylene oxide produced by the chlorohydrin process at a low cost, eliminating the serious corrosion of chlorine-containing acid generated by the caustic waste liquid treatment to equipment, and laying a foundation for the development of a new chlorohydrin process alkylene oxide technology with low cost, low energy consumption and chlorine closed-loop utilization.

[0006] The technical solution of the present invention is as follows: a feed pump of NaOH caustic waste liquid is connected to a high-pressure pump through an oxygen dissolver and then connected to a heat exchanger to form a NaOH caustic waste liquid pretreatment system, the oxygen amount of the shallow dissolved oxygen in the oxygen dissolver is 0-15wt% or saturated, and the pumping pressure of the high-pressure pump is ≥22.1MPa; an electromagnetic heating tubular reactor is connected to a supercritical delayed gasification reactor, two or more salt discharge lock hoppers are arranged at the bottom of the supercritical delayed gasification reactor, and a gas-liquid mixed phase outlet at the top is connected to a gas-liquid separation tank through a heat exchanger to form a supercritical gasification reactor for NaOH caustic waste liquid. The system has a supercritical gasification pressure of ≥22.1MPa, a gasification temperature of 400-700℃, and a supercritical delayed gasification reaction time of 1-180 minutes; the preheated waste liquid outlet of the NaOH causticizing waste liquid pretreatment system is connected to the inlet of the electromagnetic heating tubular reactor of the NaOH causticizing waste liquid supercritical gasification system, and the salt discharge lock bucket at the bottom of the supercritical delayed gasification reactor is respectively connected to the high-temperature purified water outlet of the gas-liquid separation tank, forming a causticizing waste liquid supercritical gasification full resource disposal device, and the concentration of the diluted brine is 31.5%-36.1%.

[0007] Among them, the oxygen dissolver is a packed tower oxygen-liquid mixer or a mixer with an oxygen microporous distributor arranged in a waste liquid pipeline; the oxygen microporous distributor is a tubular distributor with 1-300μm micropores evenly opened on the tube wall, an opening rate of 1%-10%, and an opening area length of 10-1000mm. The distance between the inner wall of the waste liquid pipeline and the outer wall of the tubular distributor is 1 / 10 to 2 times the inner diameter of the tubular distributor.

[0008] The electromagnetic heating tubular reactor is a reactor in which high-frequency alternating current generates an alternating magnetic field through a coil under the action of an electromagnetic heating controller, and the tubular reactor wall and the internal self-mixing and strengthening internal components generate eddy current self-heating, thereby achieving uniform heating, rapid temperature rise and reaction of high-pressure dissolved oxygen causticized waste liquid; the self-mixing and strengthening internal components are regular packing type, X-cross plate type or spiral plate type.

[0009] A funnel-shaped liquid extraction port is arranged at the center of the supercritical delayed gasification reactor, the funnel is connected to the upper part of the reactor, a gas-liquid mixed phase discharge port is arranged at the top of the reactor, and two or more salt discharge lock hoppers are arranged at the bottom; the salt discharge lock hopper is provided with a high-concentration NaCl slurry level detector.

[0010] The present invention will be described in detail with reference to embodiments. 4. Description of the drawings

[0011] Attached Figure 1 It is a process schematic diagram of the present invention.

[0012] The accompanying drawings are described as follows:

[0013] 1. Feed pump 2. Oxygen dissolver 3. High-pressure pump 4. Heat exchanger 5. Electromagnetic heating tubular reactor 6. Supercritical delayed gasification reactor 7. Gas-liquid separation tank A. NaOH caustic waste liquid inlet B. Oxygen inlet C. Synthesis gas outlet D. Purified water outlet E. Brine outlet

[0014] The process characteristics of the present invention are described in detail below in conjunction with the accompanying drawings and embodiments. 5. Specific implementation methods

[0015] Embodiment, the NaOH caustic waste liquid feed pump (1) is connected to the high-pressure pump (3) through the oxygen dissolver (2) and then connected to the heat exchanger (4), forming a NaOH caustic waste liquid pretreatment system, the oxygen dissolved in the oxygen dissolver (2) is 0-15% or saturated, and the pumping pressure of the high-pressure pump (3) is ≥22.1MPa; the electromagnetic heating tubular reactor (5) is connected to the supercritical delayed gasification reactor (6), the bottom of the supercritical delayed gasification reactor (6) is provided with two or more salt discharge lock hoppers, and the gas-liquid mixed phase outlet at the top is connected to the gas-liquid separation tank (7) through the heat exchanger (4), forming a NaOH caustic waste liquid pretreatment system. The waste liquid supercritical gasification system has a supercritical gasification pressure of ≥22.1MPa, a gasification temperature of 400-700°C, and a supercritical delayed gasification reaction time of 1-180 minutes; the preheated waste liquid outlet of the NaOH causticized waste liquid pretreatment system is connected to the inlet of the electromagnetic heating tubular reactor (5) of the NaOH causticized waste liquid supercritical gasification system, and the salt discharge lock hopper at the bottom of the supercritical delayed gasification reactor (6) is respectively connected to the high-temperature purified water outlet of the gas-liquid separation tank (7), forming a causticized waste liquid supercritical gasification full resource disposal device, and the concentration of the diluted brine is 31.5wt%-36.1wt%.

[0016] The oxygen dissolver (2) is a packed tower type oxygen-liquid mixer or a mixer in which an oxygen microporous distributor is arranged in a waste liquid pipeline; the oxygen microporous distributor is a tubular distributor having micropores of 1-300 μm uniformly opened on the tube wall, an opening rate of 1%-10%, and an opening area length of 10-1000 mm, and the distance between the inner wall of the waste liquid pipeline and the outer wall of the tubular distributor is 1 / 10 to 2 times the inner diameter of the tubular distributor.

[0017] The electromagnetic heating tubular reactor (5) is a tubular reactor in which, under the action of an electromagnetic heating controller (8), high-frequency alternating current passes through a coil to generate an alternating magnetic field, and the tubular reactor wall and the self-mixing and strengthening internal components inside generate eddy current self-heating, thereby achieving uniform heating, rapid temperature rise and reaction of high-pressure dissolved oxygen causticized waste liquid; the self-mixing and strengthening internal components are regular packing type, X-cross plate type or spiral plate type.

[0018] A funnel-shaped liquid extraction port is arranged at the center of the supercritical delayed gasification reactor (6), the funnel is connected to the upper part of the reactor, a gas-liquid mixed phase discharge port is arranged at the top of the reactor, and two or more salt discharge lock hoppers are arranged at the bottom; the salt discharge lock hoppers are provided with a high-concentration NaCl slurry level detector.

[0019] The specific reaction conditions and experimental results are as follows:

[0020] (1) After saturated dissolved oxygen, at 24 MPa and 450°C, the micro-autothermal supercritical gasification reaction was 2 seconds when heated, and the supercritical delayed gasification reaction was 10 minutes. The COD removal rate was 99.1%, and the H2 content in the synthesis gas was 70% and CO was 10%.

[0021] (2) After saturation with dissolved oxygen, the micro-autothermal supercritical gasification reaction was carried out for 2 seconds at 24 MPa and 550°C, and the supercritical delayed gasification reaction was carried out for 5 minutes. The COD removal rate was 99.9%, and the H2 content in the synthesis gas was 65% and the CO content was 8%.

[0022] The device is not only used to treat NaOH causticized wastewater from the chlorohydrin process for producing alkylene oxide, but can also be used for resource disposal of high-concentration biodegradable organic wastewater such as coking wastewater, pharmaceutical wastewater, printing and dyeing wastewater, and papermaking black liquor.

[0023] The supercritical gasification and full resource disposal device for caustic waste liquid of chlorohydrin process for preparing alkylene oxide provided by the present invention realizes micro-autothermal supercritical gasification by shallowly dissolving oxygen in NaOH caustic waste liquid, strengthens mixing and inhibits salt precipitation scaling corrosion while heating by eddy current self-heating by self-mixing strengthening internal components to realize rapid and uniform heating, improves gasification efficiency by supercritical delayed gasification reaction, and realizes separation of water-gas mixed phase and brine by utilizing supercritical water characteristics, recovers waste heat of high-temperature purified water and recycles it, and the effective utilization rate of electric energy is greater than 95%, and organic matter in caustic waste liquid is completely gasified to produce H2 The synthesis gas is more than 60%, the COD removal rate is greater than 99%, the brine concentration can be flexibly adjusted at low cost according to the needs of the electrolyzer, and the cost and investment of resource management of caustic waste liquid are reduced by more than 70% compared with traditional treatment methods, laying the foundation for low-cost and low-energy chlorine closed-loop utilization, breaking the industrial bottleneck of high water consumption in the production of chlorohydrin method of alkylene oxide and high pollution of caustic waste liquid, eliminating the serious corrosion of chlorine-containing acid produced by the disposal of caustic waste liquid to equipment, and providing reliable conditions for the implementation of new chlorohydrin method alkylene oxide technology with low cost, low energy consumption and chlorine closed-loop utilization.

Claims

1. A supercritical gasification treatment device for caustic waste liquid from the production of alkylene oxide by the chlorohydrin process, characterized in that The feed pump of NaOH caustic waste liquid is connected to the high-pressure pump through the oxygen dissolver and then connected to the heat exchanger to form a NaOH caustic waste liquid pretreatment system. The oxygen dissolved in the oxygen dissolver is 0-15wt% or saturated, and the pumping pressure of the high-pressure pump is ≥22.1MPa; the electromagnetic heating tubular reactor is connected to the supercritical delayed gasification reactor, and two or more salt discharge lock hoppers are arranged at the bottom of the supercritical delayed gasification reactor, and the gas-liquid mixed phase outlet at the top is connected to the gas-liquid separation tank through the heat exchanger to form a NaOH caustic waste liquid supercritical gasification system. The supercritical gasification pressure is ≥22.1MPa, the gasification temperature is 400-700℃, and the supercritical delayed gasification reaction time is 1-180 minutes; the preheated waste liquid outlet of the NaOH causticizing waste liquid pretreatment system is connected to the inlet of the electromagnetic heating tubular reactor of the NaOH causticizing waste liquid supercritical gasification system, and the salt discharge lock bucket at the bottom of the supercritical delayed gasification reactor is respectively connected to the high-temperature purified water outlet of the gas-liquid separation tank, forming a causticizing waste liquid supercritical gasification disposal device, and the concentration of the diluted brine is 31.5wt%-36.1wt%.

2. The supercritical gasification treatment device for caustic waste liquid from chlorohydrin process to alkylene oxide according to claim 1, characterized in that The oxygen dissolver is a packed tower oxygen-liquid mixer or a mixer in which an oxygen microporous distributor is arranged in a waste liquid pipeline; the oxygen microporous distributor is a tubular distributor with 1-300 μm micropores uniformly opened on the tube wall, an opening rate of 1%-10%, and an opening area length of 10-1000 mm, and the distance between the inner wall of the waste liquid pipeline and the outer wall of the tubular distributor is 1 / 10 to 2 times the inner diameter of the tubular distributor.

3. The supercritical gasification treatment device for caustic waste liquid from chlorohydrin process for producing alkylene oxide according to claim 1, characterized in that The electromagnetic heating tubular reactor is a tubular reactor in which, under the action of an electromagnetic heating controller, high-frequency alternating current passes through a coil to generate an alternating magnetic field, and eddy current self-heating is generated on the tubular reactor wall and the internal self-mixing strengthening internal components. The self-mixing strengthening internal components are regular packing type, X-cross plate type or spiral plate type.

4. The supercritical gasification treatment device for caustic waste liquid from chlorohydrin process for producing alkylene oxide according to claim 1, characterized in that A funnel-shaped liquid extraction port is arranged at the center of the supercritical delayed gasification reactor, the funnel is connected to the upper part of the reactor, a gas-liquid mixed phase discharge port is arranged at the top of the reactor, and two or more salt discharge lock hoppers are arranged at the bottom; the salt discharge lock hopper is provided with a high-concentration NaCl slurry level detector.

Images