A green residue-reducing propylene oxide production apparatus and method

Abstract

The present application relates to a kind of green residue reduction propylene oxide production device and method, belong to energy-saving and environment-friendly chemical equipment field.The production device of the present application not only reduces the hydrogen chloride concentration in chlorohydrin entering saponification system, and the amount of lime milk in saponification reaction, but also significantly reduces the amount of filter residue that needs additional treatment, so as to improve production efficiency, promote green residue reduction while also achieving more effective cost control, so that the propylene oxide production cost of the present application is also greatly reduced, and the economic advantage is significant.

Description

TECHNICAL FIELD

[0001] The present application relates to a green residue-reducing propylene oxide production device and method, belonging to the field of energy-saving and environment-friendly chemical processes. BACKGROUND

[0002] Among numerous chemical products, propylene derivatives occupy an important position. Among these derivatives, the production of propylene oxide (PO) is particularly prominent, ranking second only to polypropylene and acrylonitrile, and becoming one of the important varieties of propylene derivatives. As an important organic chemical raw material, propylene oxide is widely used in the production of polyurethane, surfactants, propylene glycol and other chemical products. Its market demand is large, and its application field is wide, so that propylene oxide occupies a pivotal position in the global chemical industry. With the continuous progress of chemical technology and the continuous growth of market demand, the production and application prospect of propylene oxide will continue to maintain strong development momentum.

[0003] At present, the main methods for industrial synthesis of propylene oxide include chlorohydrination method, ethylbenzene co-oxidation method, isobutane co-oxidation method, hydrogen peroxide direct oxidation method (HPPO) and the like. Among them, the chlorohydrination method is a relatively mature process, which generates chlorohydrin by chlorinating propylene, and then obtains propylene oxide by dehydrochlorination, but this method produces a large amount of waste residue, polluting the environment. The ethylbenzene co-oxidation method generates propylene oxide by co-oxidizing ethylbenzene and oxygen, which reduces the generation of waste residue, but has high energy consumption, and the toxicity of ethylbenzene also poses a threat to the environment and the health of operating personnel. The isobutane co-oxidation method uses isobutane and oxygen to generate propylene oxide under the action of a catalyst, which has more by-products and requires high purity of isobutane. The hydrogen peroxide direct oxidation method generates propylene oxide by direct reaction of hydrogen peroxide and propylene, which has only water as by-product and is an environmentally friendly production method, but the technology is not mature enough and the cost is high.

[0004] The present application aims to provide a green residue-reducing propylene oxide production device and method to improve the environmental pollution and high energy consumption problems in the prior art. SUMMARY

[0005] To improve the above technical problems, the present application provides a propylene oxide production device, wherein the production device comprises:

[0006] a lime milk preparation device;

[0007] a saponification reaction device located downstream of the lime milk preparation device;

[0008] a sedimentation and concentration recycling device and a saponification residual liquid acid addition device located downstream of the saponification reaction device;

[0009] a further reaction device of the concentrated liquid and the chlorohydrination reaction product, which is located upstream of the saponification reaction device and downstream of the sedimentation and concentration recycling device;

[0010] The first discharge end of the sedimentation and concentration recycling device is connected with the feed end of the saponification reaction device, the feed end of the lime milk preparation device, and the chlorohydrination discharge end of the further reaction device of the concentrated liquid and the chlorohydrination reaction product, respectively.

[0011] According to an embodiment of the present application, the chlorohydrination reaction product refers to the product after the reaction of propylene with chlorine and water. For example, the chlorohydrination reaction product comprises chloropropanol, hydrogen chloride, hypochlorous acid and water.

[0012] According to an embodiment of the present application, the chloropropanol is monochloropropanol, which can be selected from one or both of 1-chloro-2-propanol and 2-chloro-1-propanol. Preferably, the chloropropanol comprises a mixture of 1-chloro-2-propanol and 2-chloro-1-propanol. Preferably, in the chloropropanol, the molar ratio of 1-chloro-2-propanol to 2-chloro-1-propanol is greater than 1:1, for example, 5:1 to 9.9:1, such as 5:1, 6:1, 7:1, 8:1, 9:1, 9.5:1 or 9.9:1.

[0013] According to an embodiment of the present application, the saponification reaction device comprises a feed end and a discharge end, wherein:

[0014] The feed end comprises a chlorohydrination liquid feed port, a chlorohydrination liquid inlet after reaction with the concentrated liquid, a lime milk feed port, and a concentrated liquid feed port connected with the sedimentation and concentration recycling device;

[0015] The discharge end is connected with the feed end of the sedimentation and concentration recycling device.

[0016] The further reaction device of the concentrated liquid and the chlorohydrination reaction product is a mixture of the concentrated liquid from the sedimentation and concentration recycling device and the chlorohydrination reaction product. The hydrochloric acid in the chlorohydrination reaction product reacts with calcium hydroxide and calcium carbonate in the concentrated liquid, and the generated gas phase is sent to an environmental protection device after water washing to further reduce the generation of solid particles in the liquid. The reacted chlorohydrination liquid is pumped to the saponification reaction device.

[0017] According to an embodiment of the present application, the discharge end of the saponification reaction device produces a mixture comprising propylene oxide (such as crude propylene oxide), solid waste and waste liquid.

[0018] According to an embodiment of the present application, the lime milk preparation device comprises a feed end and a discharge end, wherein:

[0019] The feed end comprises a concentrated liquid feed port connected with the sedimentation and concentration recycling device and a calcium hydroxide feed port.

[0020] The discharge end is connected with a lime milk feed inlet of the saponification reaction device, so that the reaction is carried out in the saponification reaction device.

[0021] According to an embodiment of the present application, the lime milk preparation device further comprises a calcium hydroxide particle size screening device.

[0022] According to an embodiment of the present application, the sedimentation and concentration recycling device is used for recycling the saponification residual liquid (i.e. mixture of solid waste and waste liquid) generated by the saponification reaction device through sedimentation and concentration, and is connected with the feed end of the lime milk preparation device, the feed end of the saponification reaction device, and the chloroalcohol discharge end of the further reaction device of the concentrated liquid and the chloroalcohol reaction product.

[0023] According to an embodiment of the present application, the sedimentation and concentration recycling device comprises a sedimentation device, a concentration device and a recycling device. The sedimentation device can be a sedimentation tank known in the art for sedimentation; the concentration device can be an evaporation device or a cyclone known in the art; and the recycling device can comprise pipelines and pumping devices connected with the feed end of the lime milk preparation device, the feed end of the saponification reaction device, and the chloroalcohol discharge end of the further reaction device of the concentrated liquid and the chloroalcohol reaction product.

[0024] According to an embodiment of the present application, the saponification residual liquid and acid adding device comprises a feed end and a discharge end, wherein the feed end comprises a saponification residual liquid feed inlet and an acid feed inlet. For example, the saponification residual liquid and acid adding device is used for mixing part of the saponification residual liquid with hydrochloric acid, so that the hydrochloric acid reacts with the alkali (such as calcium hydroxide) in the residual liquid, and the dry basis filter cake content is reduced. For example, the discharge end of the saponification residual liquid and acid adding device can deliver the product to a solid-liquid separation device (such as a filter device, such as another concentration tank), and the product is separated by the solid-liquid separation device to obtain a clear liquid and a solid waste residue. For example, the filter device is a filter press.

[0025] According to an embodiment of the present application, the production device further comprises an industrial water treatment device, and the water inlet of the industrial water treatment device is connected with the liquid outlet of the solid-liquid separation device and the second discharge end of the sedimentation and concentration recycling device.

[0026] The concentrated liquid from the first discharge end of the sedimentation and concentration recycling device is recycled into the saponification reaction device, the lime milk preparation device and the further reaction device of the concentrated liquid and the chlorohydrination reaction product, and the concentrated liquid from the second discharge end of the sedimentation and concentration recycling device is introduced into the industrial water treatment device. In the present application, the first discharge end refers to the discharge end of the concentrated liquid for recycling. In a specific embodiment, three branches are provided at the first discharge end, the first branch is connected to the feed end of the saponification reaction device, the second branch is connected to the feed end of the lime milk preparation device, and the third branch is connected to the chlorohydrination discharge end of the further reaction device of the concentrated liquid and the chlorohydrination reaction product.

[0027] According to an embodiment of the present application, the production device further comprises a filter residue treatment device, and the feed end of the filter residue treatment device is connected to the solid material outlet of the solid-liquid separation device.

[0028] The present application also provides a production method of propylene oxide, comprising:

[0029] The chloropropanol is subjected to a saponification reaction in a system to obtain propylene oxide;

[0030] The system comprises lime milk, chlorohydrination liquid, concentrated liquid and further reaction material of the concentrated liquid and the chlorohydrination reaction product.

[0031] The concentrated liquid is obtained by sedimentation and concentration of the saponification residual liquid generated from the saponification reaction.

[0032] According to an embodiment of the present application, the concentration ratio of the saponification residual liquid subjected to sedimentation and concentration is 1:1.05-1:8, for example, 1:1.08, 1:1.1, 1:1.2, 1:1.3, 1:1.5, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7.

[0033] According to an embodiment of the present application, the concentration comprises primary concentration, secondary concentration or more levels of concentration. For example, the concentration ratio of the primary concentration is 1:1.5-1:5, for example, 1:1.5, 1:2, 1:3, 1:4, 1:5; the concentration ratio of the secondary concentration is greater than 1:1.2 and not more than 1:5, for example, 1:1.3, 1:1.6, 1:2, 1:3, 1:4, 1:5.

[0034] According to an embodiment of the present application, the lime milk is a suspension obtained by mixing and reacting calcium hydroxide powder with water or concentrated liquid.

[0035] According to an embodiment of the present application, the chlorohydrination liquid is the reaction liquid after the chlorohydrination reaction of propylene with chlorine and water.

[0036] According to an embodiment of the present application, the sedimented concentrated saponification residual liquid accounts for 70% to 99%, for example 75%, 80%, 85%, 90%, 92%, 95% of the total volume of the saponification residual liquid.

[0037] According to an embodiment of the present application, the ratio of the sum of the volumes of the concentrated liquid for preparing milk of lime, the concentrated liquid for further reacting with the chlorohydrination reaction product, and the concentrated liquid returned to the system to the volume of the sedimented concentrated saponification residual liquid is 1:2 to 1:7, for example 1:3, 1:4, 1:5, 1:6.

[0038] According to an embodiment of the present application, part of the saponification residual liquid produced by the saponification reaction is treated with acid to neutralize the calcium hydroxide therein. For example, hydrochloric acid is added in an amount that only reacts with calcium hydroxide and does not react with calcium carbonate. Preferably, the pH value of the saponification residual liquid after mixing reaction with hydrochloric acid is 8.6 to 9.6 to avoid the emission of greenhouse gas CO2.

[0039] According to an embodiment of the present application, the flow rate ratio of the saponification residual liquid treated with acid to the saponification residual liquid separated by sedimentation is 1:3 to 1:8, for example 1:4, 1:5, 1:6, 1:7.

[0040] According to an embodiment of the present application, the content of calcium hydroxide in the saponification residual liquid is 0.1wt% to 0.2wt%, and the content of calcium carbonate is 0.2wt% to 0.5wt% by weight.

[0041] According to an embodiment of the present application, the content of calcium hydroxide in the concentrated liquid is 0.105wt% to 1.5wt%, and the content of calcium carbonate is 0.21wt% to 5wt% by weight.

[0042] According to an embodiment of the present application, the concentrations of the concentrated liquid for preparing milk of lime, the concentrated liquid for further reacting with the chlorohydrination reaction product, and the concentrated liquid returned to the system are the same or different.

[0043] In one embodiment, the concentrated liquid for preparing milk of lime is a primary concentrated liquid, and the concentrated liquid for further reacting with the chlorohydrination reaction product and the concentrated liquid returned to the system are secondary concentrated liquids.

[0044] For example, in the primary concentrated liquid, the content of calcium hydroxide is 0.105wt% to 0.24wt%, and the content of calcium carbonate is 0.21wt% to 0.8wt%;

[0045] In the secondary concentrated liquid, the content of calcium hydroxide is 0.5wt% to 1.5wt% (for example 0.5wt% to 1.0wt%), and the content of calcium carbonate is 1.2wt% to 5.0wt% (for example 1.3wt% to 2.0wt%).

[0046] According to an embodiment of the present application, the solid particles in the saponification residual liquid can comprise one, two or more of oxides, hydroxides, carbonates or hydrochloric acid insoluble substances of metal or non-metal elements.

[0047] According to an embodiment of the present application, the metal or non-metal elements can be selected from one, two or more of Ca, Mg, Fe, Al, Si.

[0048] According to an embodiment of the present application, the solid particles in the saponification residual liquid can comprise one, two or more of Ca(OH)2, CaCO3, MgCO3, Fe2O3, Al2O3, SiO2. For example, the filter residue can comprise Ca(OH)2, CaCO3, Mg(OH)2, MgCO3, Fe2O3, Al2O3and SiO2.

[0049] According to an embodiment of the present application, the solid particles in the saponification residual liquid can also comprise CaSO4.

[0050] According to an embodiment of the present application, in the settling and concentration process, the ratio of the amount of concentrated liquid recycled to the overflow amount of supernatant can be 1:3 to 1:10, such as 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0051] According to an embodiment of the present application, the molar ratio of Ca(OH)2to chloropropanol in the concentrated liquid can be higher than 1:1 and lower than 1.5:1, such as (1.05-1.3):1, for example 1.05:1, 1.10:1, 1.15:1, 1.20:1, 1.25:1 or 1.30:1.

[0052] According to an embodiment of the present application, the flow ratio of the concentrated liquid to the chlorohydrin liquid can be 1:5 to 1:20, such as 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20.

[0053] According to an embodiment of the present application, the method for producing propylene oxide further comprises subjecting the saponification residual liquid after acid treatment to solid-liquid separation, subjecting the obtained liquid phase to industrial water treatment, and subjecting the obtained solid phase to waste residue treatment.

[0054] According to an embodiment of the present application, the method for producing propylene oxide further comprises subjecting other concentrated liquids, other than the concentrated liquid used for preparing lime milk, the concentrated liquid used for further reaction with the chlorohydrination reaction product, and the concentrated liquid used for returning to the system, to industrial water treatment.

[0055] According to an embodiment of the present application, the propylene oxide production method is carried out in the production device.

[0056] According to an embodiment of the present application, the propylene oxide production method comprises the following steps:

[0057] (1) mixing calcium hydroxide powder with water or concentrated solution to obtain lime milk;

[0058] (2) subjecting chlorohydrin to saponification reaction in the system to obtain propylene oxide;

[0059] The system comprises the lime milk, chlorohydrin solution, concentrated solution, and reaction materials of concentrated solution and chlorohydrin;

[0060] The concentrated solution is obtained by settling and concentrating part of saponification residual solution generated by the saponification reaction;

[0061] (3) subjecting another part of saponification residual solution generated by the saponification reaction to acidification, solid-liquid separation, subjecting the obtained liquid phase to industrial water treatment, and subjecting the obtained solid phase to waste residue treatment.

[0062] According to an embodiment of the present application, optionally, the propylene oxide production method further comprises the following step:

[0063] (4) subjecting other concentrated solutions except the concentrated solution for preparing lime milk, the concentrated solution for further reaction of reaction products of chlorohydrin, and the concentrated solution for returning to the system to industrial water treatment.

[0064] According to an embodiment of the present application, the propylene oxide production method comprises the following steps:

[0065] (A1) mixing calcium hydroxide powder with water or concentrated solution in the lime milk preparation device to obtain lime milk;

[0066] (A2) part of saponification residual solution generated by the saponification reaction device enters the settling and concentrating recycling device to obtain concentrated solution; part of the concentrated solution enters the lime milk preparation device, the further reaction device of concentrated solution and chlorohydrin reaction products, and the saponification reaction device;

[0067] (A3) another part of saponification residual solution generated by the saponification reaction device enters the saponification residual solution acidification device and the solid-liquid separation device, the obtained liquid is sent to the industrial water treatment device, and the solid is sent to the waste residue treatment device.

[0068] According to an embodiment of the present application, optionally, the propylene oxide production method further comprises the following step:

[0069] (A4) another part of the concentrated solution of the settling and concentrating recycling device is treated in the industrial water treatment device.

[0070] Advantages

[0071] The propylene oxide production device and method of the present application not only reduces the amount of lime milk used in the saponification reaction, but also significantly reduces the amount of filter residue that needs to be treated additionally, thereby improving production efficiency, promoting green residue reduction, and achieving more effective cost control, so that the production cost of propylene oxide of the present application is also reduced to a certain extent, and the economic advantage is significant. BRIEF DESCRIPTION OF DRAWINGS

[0072] Figure 1 The figure is a schematic diagram of the production device of the present application, wherein each reference sign has the following meaning: 1-saponification reaction device; 2-settling and concentration recycling device; 3-lime milk preparation device; 4-saponification residual liquid acid addition device; 5-filtration device; 6-waste residue treatment device; 7-industrial water treatment device; 8-further reaction device of concentrated liquid and chlorohydration reaction product. DETAILED DESCRIPTION

[0073] The technical solutions of the present application will be further described in detail below in combination with specific examples. It should be understood that the following examples are only illustrative and explanatory of the present application, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above description of the present application is covered within the scope of protection intended by the present application.

[0074] Example 1: Propylene oxide production device

[0075] The present example provides a propylene oxide production device as shown in Figure 1 The production device comprises:

[0076] a lime milk preparation device 3;

[0077] a saponification reaction device 1 located downstream of the lime milk preparation device 3;

[0078] a settling and concentration recycling device 2 and a saponification residual liquid acid addition device 4 located downstream of the saponification reaction device 1;

[0079] a further reaction device 8 of concentrated liquid and chlorohydration reaction product, which is located both upstream of the saponification reaction device 1 and downstream of the settling and concentration recycling device 2;

[0080] a filtration device 5 and a waste residue treatment device 6 located downstream of the saponification residual liquid acid addition device 4;

[0081] an industrial water treatment device 7 located both downstream of the settling and concentration recycling device 2 and the filtration device 5.

[0082] The saponification reaction device 1 comprises an inlet end and an outlet end, wherein: the inlet end comprises a chlorohydrin liquid inlet, a chlorohydrin inlet after reaction with the concentrated liquid, a lime milk inlet, and a concentrated liquid inlet connected with the sedimentation and concentration recycling device 2; the outlet end is connected with the inlet end of the sedimentation and concentration recycling device 2 and the saponification residual liquid and acid device 4, that is, the output of the outlet end comprises propylene oxide (such as crude propylene oxide) and saponification residual liquid (i.e. a mixture of solid waste and waste liquid), part of the saponification residual liquid enters the sedimentation and concentration recycling device 2, and the other part enters the saponification residual liquid and acid device 4.

[0083] The first outlet end of the sedimentation and concentration recycling device 2 is respectively connected with the inlet end of the saponification reaction device 1, the inlet end of the lime milk preparation device 3, and the chlorohydrin outlet end of the further reaction device 8 of the concentrated liquid and chlorohydrin reaction product, and the second outlet end of the sedimentation and concentration recycling device 2 is connected with the water inlet of the industrial water treatment device 7. The sedimentation and concentration recycling device 2 is used for sedimentation and separation of the saponification residual liquid generated by the saponification reaction device for recycling to be delivered to the inlet end of the lime milk preparation device 3, the inlet end of the saponification reaction device 1, and the chlorohydrin outlet end of the further reaction device 8 of the concentrated liquid and chlorohydrin reaction product. Further, the sedimentation and concentration recycling device comprises a sedimentation device, a concentration device, and a recycling device. The sedimentation device can be a sedimentation tank known in the art for sedimentation; the concentration device can be an evaporation device or a cyclone known in the art; and the recycling device can comprise pipelines and pumping devices connected with the inlet end of the lime milk preparation device 3, the inlet end of the saponification reaction device 1, and the chlorohydrin outlet end of the further reaction device 8 of the concentrated liquid and chlorohydrin reaction product. In a specific embodiment, the first outlet end is provided with three branches, the first branch is connected with the inlet end of the saponification reaction device, the second branch is connected with the inlet end of the lime milk preparation device, and the third branch is connected with the chlorohydrin outlet end of the further reaction device of the concentrated liquid and chlorohydrin reaction product.

[0084] The lime milk preparation device 3 comprises an inlet end and an outlet end, the inlet end comprises a concentrated liquid inlet connected with the sedimentation and concentration recycling device 2 and a calcium hydroxide inlet, and the outlet end is connected with the lime milk inlet of the saponification reaction device 1, so as to carry out reaction in the saponification reaction device. The calcium hydroxide inlet is optionally connected with a calcium hydroxide particle size screening device.

[0085] The concentrated liquid from the thickening and recycling device 2 is mixed with chlorohydrination reaction products in the further reaction device 8. The chlorohydrination reaction products refer to the products after the reaction of propylene with chlorine and water. For example, the chlorohydrination reaction products include chloropropanol, hydrogen chloride, hypochlorous acid and water. The chloropropanol is monochloropropanol, which includes a mixture of 1-chloro-2-propanol and 2-chloro-1-propanol. The hydrogen chloride in the chlorohydrination reaction products reacts with calcium hydroxide and calcium carbonate in the concentrated liquid to produce gas phase, which is washed with water and then sent to the environmental protection device to further reduce the generation of solid particles in the liquid. The reacted chlorohydrination liquid is pumped to the saponification reaction device 1.

[0086] The saponification residual liquid and acid adding device 4 includes an inlet end and an outlet end, wherein the inlet end includes a saponification residual liquid inlet and an acid inlet. The saponification residual liquid and acid adding device 4 is used to mix part of the saponification residual liquid with hydrochloric acid to react the hydrochloric acid with the alkali (such as calcium hydroxide) in the residual liquid to reduce the dry basis filter cake content. The outlet end of the saponification residual liquid and acid adding device delivers the product to the filtration device 5 for solid-liquid separation to obtain clear liquid and solid waste residue.

[0087] The water inlet of the industrial water treatment device 7 is connected to the liquid outlet of the filtration device 5 and the second outlet end of the thickening and recycling device 2.

[0088] Propylene oxide production process embodiment

[0089] The propylene oxide production device of Example 1 is used to prepare propylene oxide (PO) according to the following process steps based on a 40,000 t / a PO device:

[0090] S1: The saponification reaction device generates saponification residual liquid, and the flow rate of the saponification residual liquid (calcium hydroxide content 0.12 wt%, calcium carbonate content 0.25 wt%) is about 280 m 3 / h, wherein:

[0091] (1) The saponification residual liquid is fed into the thickening and recycling device at a flow rate of Va1 to thicken and concentrate the saponification residual liquid (hereinafter referred to as "concentrated liquid"), and the concentrated saponification residual liquid contains:

[0092] The concentrated liquid P1 is recycled to the lime milk preparation device at a flow rate of Vb1;

[0093] The concentrated liquid P2 is recycled to the saponification reaction device and the further reaction device of the concentrated liquid and chlorohydrination reaction products at a flow rate of Vb2;

[0094] The remaining supernatant is fed into the industrial water treatment device;

[0095] (2) The saponification residual liquid without thickening and concentration is fed into the saponification residual liquid and acid reaction device at a flow rate of Va2, and hydrochloric acid is added to the saponification residual liquid and acid reaction device to react with the saponification residual liquid until the pH value is 8.6-9.6.

[0096] The reaction residue is transported to a filtering device to separate liquid and solid, wherein the liquid enters an industrial water treatment device and the solid enters a waste residue treatment device.

[0097] S2: To a lime milk preparation device, calcium hydroxide is added in an amount of 1.48 t / t PO and mixed with the concentrated solution P1 in step S1 to obtain lime milk;

[0098] S3: The lime milk obtained in step S2 is transported into a saponification reaction device at a flow rate Vc1; and the product (total flow rate Vs = Vb2 + Vd1) generated by further reacting the concentrated solution P2 in step S1 with the chlorohydrination reaction product at a flow rate Vd1 in the chlorohydrination reaction device is transported into the saponification reaction device to prepare propylene oxide.

[0099] The chlorohydrination reaction product at a flow rate Vd1 is obtained from a chlorohydrination reaction, and its composition is as follows: chlorohydrin: 4.05 wt%, HCl: 1.68 wt%.

[0100] The process conditions of the saponification reaction device are as follows: saponification kettle temperature Tf; top temperature Td; saponification top pressure Pd (absolute pressure), and saponification kettle pressure Pf (absolute pressure).

[0101] According to the above process, the process conditions are adjusted in the following examples 2, example 3, comparative example 1, and comparative example 2, as follows:

[0102]

[0103]

[0104] Note:

[0105] i. The flow rate units in the above table are all m 3 / h;

[0106] ii. In the above example 2, example 3, and comparative example 1, except for the conditions indicated, the other process steps and conditions are the same.

[0107] iii. In the above comparative example 2, except for the conditions indicated, there are the following differences:

[0108] (1) The content of calcium hydroxide in the saponification residue is 0.12 wt%, and the content of calcium carbonate is 0.80 wt%;

[0109] (2) Only concentrated solution P1 is prepared, and concentrated solution P2 is not prepared, so Vb2 is 0;

[0110] (3) The saponification residue without thickening by concentration does not enter the saponification residue acid addition reaction device, but is transported into the saponification residue acid addition reaction device at a flow rate Va2 (80 m 3h) into a filtration device, separating a liquid and a solid, the liquid being directed to an industrial water treatment device and the solid being directed to a waste residue treatment device.

[0111] The results of the above experiments are summarized in the following table:

[0112]

[0113] The above experimental results show that the device and method of the present application can increase the production of propylene oxide and reduce the production of solid waste to below 100 kg / tPO. Moreover, the thickened concentrated liquid will reduce the load of the saponification system, reducing the amount of saponification steam, lime milk, and raw materials.

[0114] The thickened concentrated liquid reacts with hydrochloric acid in chlorohydrin in advance, reducing the concentration of hydrochloric acid in chlorohydrin liquid and increasing the reaction probability of lime milk and chlorohydrin in chlorohydrin liquid. This not only improves the efficiency of the saponification system and helps the good operation of the saponification system, but also avoids the emission of greenhouse gases.

[0115] In summary, the production device of the present application not only reduces the concentration of hydrogen chloride in chlorohydrin liquid and the amount of lime milk in saponification reaction, but also significantly reduces the amount of filter residue that needs to be treated additionally. Therefore, while improving production efficiency and promoting green residue reduction, the present application also achieves more effective cost control, so that the production cost of propylene oxide is also greatly reduced, and the economic advantage is significant.

[0116] The above has exemplarily described the embodiments of the technical solutions of the present application. It should be understood that the protection scope of the present application is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art within the spirit and principles of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A process for the production of propylene oxide, characterized in that, The production method is carried out in a production device, which comprises: a lime milk preparation device; a saponification reaction device downstream of the lime milk preparation device; a sedimentation concentration recycling device and a saponification residual liquid acidification device downstream of the saponification reaction device; a further reaction device of concentrated liquid and chlorohydration reaction product upstream of the saponification reaction device and downstream of the sedimentation concentration recycling device; wherein the first discharge end of the sedimentation concentration recycling device is connected with the feed end of the saponification reaction device, the feed end of the lime milk preparation device, and the feed end of the further reaction device of concentrated liquid and chlorohydration reaction product, respectively; a solid-liquid separation device, the discharge end of the saponification residual liquid acidification device delivers products to the solid-liquid separation device, and the clear liquid and solid waste residue are obtained after separation; the production method comprises the following steps: (A1) mixing calcium hydroxide powder and water or concentrated liquid in the lime milk preparation device to obtain lime milk; (A2) part of the saponification residual liquid generated by the saponification reaction device enters the sedimentation concentration recycling device to obtain concentrated liquid; part of the concentrated liquid enters the lime milk preparation device, the further reaction device of concentrated liquid and chlorohydration reaction product, and the saponification reaction device; the sedimentation concentrated saponification residual liquid accounts for 70% to 99% of the total volume of the saponification residual liquid; the ratio of the sum of the volumes of the concentrated liquid for preparing lime milk, the concentrated liquid for further reaction with chlorohydration reaction product, and the concentrated liquid returned to the saponification reaction device to the volume of the sedimentation concentrated saponification residual liquid is 1:2 to 1:7; the concentrated liquid for preparing lime milk is primary concentrated liquid, and the concentrated liquid for further reaction with chlorohydration reaction product and the concentrated liquid returned to the saponification reaction device is secondary concentrated liquid; in the primary concentrated liquid, the content of calcium hydroxide is 0.105wt% to 0.24wt%, and the content of calcium carbonate is 0.21wt% to 0.8wt%; in the secondary concentrated liquid, the content of calcium hydroxide is 0.5wt% to 1.5wt%, and the content of calcium carbonate is 1.2wt% to 5.0wt%; (A3) another part of the saponification residual liquid generated by the saponification reaction device enters the saponification residual liquid acidification device and the solid-liquid separation device, and the separated liquid is sent to an industrial water treatment device, and the solid is sent to a waste residue treatment device; the flow rate ratio of the saponification residual liquid treated by acidification to the saponification residual liquid separated by sedimentation is 1:3 to 1:8; part of the saponification residual liquid generated by the saponification reaction is treated by acidification, and the pH value after acidification treatment is 8.6 to 9.

6.

2. The production method according to claim 1, characterized by, The saponification reaction device comprises a feed end and a discharge end, wherein: the feed end comprises a chlorohydration liquid inlet, a chlorohydration liquid inlet after reaction with concentrated liquid, a lime milk inlet, and a concentrated liquid inlet connected with the sedimentation concentration recycling device; the discharge end is connected with the feed end of the sedimentation concentration recycling device; and / or, the discharge end of the saponification reaction device outputs a mixture comprising propylene oxide, solid waste, and waste liquid.

3. The production method according to claim 1, characterized by, The lime milk preparation device comprises a feed end and a discharge end, wherein: the feed end comprises a concentrated liquid inlet connected with the sedimentation concentration recycling device and a calcium hydroxide inlet; The discharge end is connected with a lime milk feed inlet of the saponification reaction device, so that the reaction is carried out in the saponification reaction device. And / or, the lime milk preparation device further comprises a calcium hydroxide particle size screening device.

4. The production method according to claim 1, characterized by, The sedimentation and concentration recycling device comprises a sedimentation device, a concentration device and a recycling device. And / or, the feed end of the saponification residual liquid acidification device comprises a saponification residual liquid feed inlet and an acid feed inlet.

5. The production method according to claim 1, characterized by, The production device further comprises an industrial water treatment device, and a water inlet of the industrial water treatment device is connected with a liquid outlet of the solid-liquid separation device and a second discharge end of the sedimentation and concentration recycling device. And / or, the production device further comprises a filter residue treatment device, and a feed end of the filter residue treatment device is connected with a solid material outlet of the solid-liquid separation device.

6. The production method according to claim 2, characterized by, The lime milk is a suspension obtained by mixing and reacting calcium hydroxide powder with water or concentrated liquid; And / or, the chlorohydrination liquid is a reaction liquid obtained by chlorohydrination reaction of propylene with chlorine and water; And / or, the sedimentation and concentration saponification residual liquid accounts for 75%, 80%, 85%, 90%, 92% or 95% of the total volume of the saponification residual liquid.

7. The production method according to claim 2, characterized by, The flow ratio of the concentrated liquid to the chlorohydrination liquid is 1:5 to 1:

20.

8. The production method according to claim 2, characterized by, The content of calcium hydroxide in the saponification residual liquid is 0.1wt% to 0.2wt%, and the content of calcium carbonate is 0.2wt% to 0.5wt% by weight; And / or, in the sedimentation and concentration process, the flow ratio of the concentrated liquid recycling amount to the supernatant overflow amount is 1:3 to 1:10; And / or, the molar ratio of Ca(OH)2 to chloropropyl alcohol in the concentrated liquid is higher than 1:1 and lower than 1.5:1; And / or, the flow ratio of the concentrated liquid to the chlorohydrination liquid is 1:5 to 1:

20.

9. The production method according to claim 1, characterized by, In the secondary concentrated liquid, the content of calcium hydroxide is 0.5wt% to 1.0wt%, and the content of calcium carbonate is 1.3wt% to 2.0wt%.

10. The production method according to claim 1, characterized by, The concentration ratio of the primary concentrated liquid is 1:1.5 to 1:5, and the concentration ratio of the secondary concentrated liquid is greater than 1:1.2 and not more than 1:

5.

11. The production method according to claim 1, characterized by, The production method further comprises a step (A4) of feeding another part of the concentrated liquid of the sedimentation and concentration recycling device into the industrial water treatment device.

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