Device for producing urotropine

Abstract

The utility model relates to the technical field of chemical engineering, and provides a device for producing urotropine. Comprising an ammoniation reactor, an MVR evaporator, a crystallization receiving tank, a filtering and decolorizing unit and a drying unit. The bottom of the ammonification reactor is communicated with a raw material inlet of the MVR evaporator through a pipeline; the crystallization receiving tank is connected with the centrifugal machine; the filtering and decolorizing unit comprises a liquid storage tank, filtering equipment and a decolorizing tank; a crystal outlet of the centrifugal machine is connected with cooling conveying equipment through a drying conveying device. According to the production device, the urotropine is produced by adopting a liquid phase method, the raw material cost is lower, the leakage of formaldehyde gas is avoided in the operation, and the safety is higher.

Description

Technical Field

[0001] The utility model relates to a device for producing hexamethylenetetramine. Background Art

[0002] Hexamethylenetetramine, also known as hexamethylenetetramine, has a molecular formula (CH 2 ) 6 N 4 , relative molecular mass 140.18. It is a white hygroscopic powder or colorless and shiny rhombus crystal, odorless, sweet and bitter, and irritating to the skin. Hexamine is soluble in water, ethanol and chloroform, insoluble in ether, flammable, and has a colorless and smokeless flame when burning. Its chemical properties are similar to formaldehyde, and it can undergo many chemical reactions, such as hydrolysis and addition reactions. Hexamine is an important chemical product with a wide range of uses. In the past, hexamine was mainly used to produce RDX and HMX advanced explosives, commonly known as "black gold explosives". Now it is mainly used to produce aminoacetic acid (glycine) intermediates, phenolic resin curing agents and rubber vulcanization accelerators, shrinkage-resistant agents for textiles, and used to make raw materials such as fungicides and diuretics. At present, the production processes of hexamine are mainly gas phase method and liquid phase method. The main difference between these two processes lies in the phase of the raw material formaldehyde used in the actual production process. If liquid formaldehyde solution is used in the production process, the production method is called liquid phase method; if formaldehyde gas is used, the production method is called gas phase method.

[0003] The gas phase hexamethylenetetramine production process is to directly introduce the formaldehyde gas generated by the conversion of methanol into an ammonia reactor to react with ammonia in a saturated hexamethylenetetramine solution to generate hexamethylenetetramine. The biggest feature of this process is that it utilizes the latent heat of formaldehyde and the reaction heat of hexamethylenetetramine to evaporate water under vacuum conditions, thus saving a large amount of steam. Generally, it can achieve steam self-sufficiency when matched with a formaldehyde device. In addition, the gas phase production process has a short route, short reaction time, few side reactions, high product purity, uniform particles, continuous production, high degree of automation, large production capacity, and is equipped with a dilute ammonia water recovery device, which can reduce ammonia consumption and control wastewater discharge.

[0004] The liquid phase method is to feed formaldehyde solution (formaldehyde content ≥ 37.0%) and ammonia into a reactor, and then introduce the urotropine liquid generated by the reaction into a vaporizer to vaporize part of the water. The liquid is concentrated and fed into a crystallizer, and then centrifuged to obtain the finished product. The wet crystals are fed into a dryer for drying. The finished product is obtained after drying. When the liquid phase method generates urotropine, a large amount of steam is required in the concentration process, which has the disadvantage of high energy consumption. Summary of the invention

[0005] The utility model aims to provide a device for producing urotropine, which concentrates urotropine through an MVR evaporator, volatilizes the excess ammonia in the urotropine solution by low pressure, and heats the urotropine concentrate by means of heat release of compressed ammonia gas. The urotropine concentrate provides heat for the MVR evaporator, which reduces the amount of extra steam used when vaporizing the water in the urotropine solution by the original liquid phase method. At the same time, the high-temperature wastewater generated by the analysis tower for analyzing olefin ammonia water can also be used as a drying heat source for the drying and conveying device, further reducing energy consumption. The production device adopts the liquid phase method to produce urotropine, which has lower raw material costs, avoids leakage of formaldehyde gas during operation, and has higher safety.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the utility model is: a device for producing hexamethylenetetramine, including an ammoniation reactor and an MVR evaporator, the bottom of the ammoniation reactor is connected to the raw material inlet of the MVR evaporator through a pipeline, the steam outlet of the MVR evaporator is connected to the inlet of the steam compressor, the concentrated liquid outlet pipeline at the bottom of the MVR evaporator is divided into two paths, one path is connected to the tube side inlet of the heat exchanger through a pipeline, and the other path is connected to the crystallization tank through a pipeline, the tube side outlet of the heat exchanger is connected to the concentrated liquid inlet of the MVR evaporator through a pipeline provided with a pump; the outlet of the steam compressor is connected to the shell side inlet of the heat exchanger through a pipeline; a hot well is provided at the shell side outlet of the heat exchanger; the bottom outlet of the hot well is connected to the inlet of the dilute ammonia water tank through a pipeline, and the outlet of the dilute ammonia water tank is connected to the upper wastewater inlet of the analytical tower through a pipeline provided with a pump.

[0007] The bottom of the crystal receiving tank is connected to the centrifuge through a pipeline, the crystal outlet of the centrifuge is connected to the cooling and conveying equipment through a drying and conveying device, and the lower liquid port of the centrifuge is connected to the liquid storage tank, the filtering equipment, the decolorization tank, and the raw material inlet of the MVR evaporator in sequence through a pipeline equipped with a pump.

[0008] The upper condensate outlet of the analytical tower is connected to the ammonia inlet pipe of the ammonia reactor through a pipeline, and another inlet pipe of the ammonia reactor is connected to the formaldehyde solution tank.

[0009] The filtering equipment is a plate filter press, the inlet pipe of the plate filter press is connected to the liquid storage tank through a pipeline, a delivery pump is provided on the pipeline, the filtrate outlet pipe of the plate filter press is connected to the decolorization tank through a pipeline, and the decolorization tank is filled with activated carbon. The plate filter press is used to remove solid impurities in the filtrate separated by the centrifuge, and the decolorization tank is used to remove pigments in the filtrate of the plate filter press.

[0010] The cooling and conveying equipment uses a jacket cooling cage.

[0011] The drying and conveying device includes a screw conveying dryer, a drum dryer, and a vacuum rake dryer.

[0012] The tail gas outlet of the ammoniation reactor is connected to the absorption tower through a pipeline, and the liquid outlet of the absorption tower is connected to the inlet pipe of the ammoniation reactor through a pipeline.

[0013] Compared with the prior art, the process of the utility model has the following beneficial effects: the urotropine is concentrated by the MVR evaporator, the excess ammonia in the urotropine solution is volatilized by low pressure, and the urotropine concentrate is heated by the heat release of the compressed ammonia gas. The urotropine concentrate provides heat for the MVR evaporator, which reduces the amount of additional steam used when the water in the urotropine solution is vaporized by the original liquid phase method. At the same time, the high-temperature wastewater generated by the analysis tower for analyzing the olefin ammonia water can also be used as a drying heat source for the drying and conveying device, further reducing energy consumption. The production device adopts the liquid phase method to produce urotropine, with lower raw material costs, avoiding the leakage of formaldehyde gas during operation, and higher safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a process flow chart for preparing utolamine according to the utility model;

[0015] Figure 2 It is a simplified structural diagram of the component ammoniation reactor of the utility model. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods:

[0017] Example 1

[0018] A device for producing hexamethylenetetramine mainly comprises an ammoniation reactor 1 and an MVR evaporator 2. The bottom of the ammoniation reactor 1 is connected to the raw material inlet of the MVR evaporator 2 through a pipeline. The steam outlet of the MVR evaporator 2 is connected to the inlet of a steam compressor 2a. The concentrated liquid outlet pipeline at the bottom of the MVR evaporator 2 is divided into two paths, one of which is connected to the tube side inlet of a heat exchanger 2b through a pipeline, and the other is connected to a crystallization tank 3 through a pipeline. The tube side outlet of the heat exchanger 2b is connected to the concentrated liquid inlet of the MVR evaporator 2 through a pipeline provided with a pump; the outlet of the steam compressor 2a is connected to the shell side inlet of the heat exchanger 2b through a pipeline; a hot well 2c is provided at the shell side outlet of the heat exchanger 2b; the bottom outlet of the hot well 2c is connected to the inlet of a dilute ammonia water tank 7 through a pipeline, and the outlet of the dilute ammonia water tank 7 is connected to the upper wastewater inlet of a decomposition tower 8 through a pipeline provided with a pump.

[0019] The bottom of the crystallization tank 3 is connected to the centrifuge 4 through a pipeline, the crystal outlet of the centrifuge 4 is connected to the cooling and conveying device 12 through the drying and conveying device 6, and the lower liquid port of the centrifuge 4 is connected to the liquid storage tank 10, the filtering device 5, the decolorization tank 9, and the raw material inlet of the MVR evaporator 2 in sequence through a pipeline provided with a pump. The storage amount of solid phase hexamine in the crystallization tank 3 should not be too much. In order to protect the equipment from being damaged, it is generally controlled to be 1 / 3 to 2 / 5 of the tank, that is, it is sent to the centrifuge 4 for centrifugal dehydration. Therefore, two crystallization tanks 3 are set up, and the two crystallization tanks 3 are exchanged to receive materials, so that the precipitated hexamine has enough crystal growth time.

[0020] The upper condensate outlet of the analytical tower 8 is connected to the ammonia inlet pipe of the ammoniation reactor 1 through a pipeline, and another inlet pipe of the ammoniation reactor 1 is connected to the formaldehyde solution tank.

[0021] The filtering device 5 is a plate filter press, the inlet pipe of the plate filter press is connected to the liquid storage tank 10 through a pipeline, a delivery pump is provided on the pipeline, and the filtrate outlet pipe of the plate filter press is connected to the decolorization tank 9 through a pipeline, and the decolorization tank 9 is filled with activated carbon. The plate filter press is used to remove solid impurities in the filtrate separated by the centrifuge 4, and the decolorization tank 9 is used to remove pigments in the filtrate of the plate filter press.

[0022] The cooling conveying device 12 uses a jacket cooling cage. The drying conveying device 6 includes a screw conveying dryer, a drum dryer, and a vacuum rake dryer.

[0023] The ammonia reactor 1 includes a body and a cold water jacket. The ammonia reactor 1 is provided with a jacket water inlet and outlet, a jacket water circulation inlet and outlet, an internal coil cooling water inlet and outlet, an internal coil material cooling and heat exchange inlet and outlet, a system recovery ammonia inlet, a raw gas ammonia inlet, a raw formaldehyde liquid inlet, a reaction tail gas ammonia outlet, a circulating mother liquor inlet and a material outlet, and is cyclically connected with other devices through the above-mentioned openings.

[0024] The working process of the device for producing hexamethylenetetramine of the utility model is as follows:

[0025] (1) Ammonia gas and 37 wt% formaldehyde solution enter the ammoniation reactor 1, and the excess gaseous ammonia gas reacts with the liquid phase to produce a urotropine mother liquor containing 24-27 wt% urotropine. The heat of reaction is removed by a circulating cooler to maintain the reaction temperature at 60-65°C.

[0026] 6CH 2 O(liquid)+4NH 3 (gas) → (CH 2 ) 6 N 4 +6H 2 O+81Kcal / mol

[0027] The excess gaseous ammonia reacts exothermically with the liquid phase to make the hexamethylenetetramine mother liquor free of formaldehyde.

[0028] (2) The urotropine mother liquor generated in the ammoniation reactor 1 is pumped to the MVR evaporator 2 and concentrated to 60-65 wt%. The urotropine mother liquor is sprayed onto the plates of the plate heat exchanger in the MVR evaporator 2, and heat is exchanged with the hot mother liquor in the plates, so that the water and ammonia in the mother liquor are volatilized. The gas is pumped to the shell side of the heat exchanger 2b by the steam compressor 2a. The gas is liquefied and releases heat during compression. The condensed water generated by the compression flows into the hot well 2c. A part of the mother liquor concentrated in the MVR evaporator 2 is returned to the tube side in the plate of the MVR evaporator 2 after absorbing the heat of the shell side through the tube side of the heat exchanger 2b. The other part of the mother liquor concentrated in the MVR evaporator 2 is discharged to the crystallization tank 3, and the dilute ammonia water in the hot well 2c is discharged to the dilute ammonia water tank 7. After the urotropine mother liquor is concentrated and centrifuged and dried, the ammonia is volatilized by heat, and the urotropine product does not contain ammonia.

[0029] The liquid phase reaction in the ammoniation reactor 1 and the evaporation in the MVR evaporator 2 are continuous operations.

[0030] (3) The hexamethylenetetramine concentrate is settled and enriched in the crystallization tank 3.

[0031] (4) After the crystal particles are formed, they enter the centrifuge 4 for solid-liquid separation.

[0032] (5) The hexamethylenetetramine solid wet material obtained by centrifugation is dried by a drying and conveying device 6, and then sent to a cooling and conveying device 12. After drying, the hexamethylenetetramine finished product is packaged.

[0033] (6) The filtrate obtained by centrifugation is filtered through a plate filter press to remove solid impurities, then filtered and decolorized through activated carbon, and then recycled to the raw material inlet of MVR evaporator 2, and the mother liquor is recycled.

[0034] (7) The waste liquid from the dilute ammonia water tank 7 enters the analysis tower 8 to recover ammonia; the tail gas after analysis meets the discharge standards, and the waste water is sent to the next process.

[0035] Furthermore, the tail gas of the ammoniation reactor 1 enters the absorption tower 13 to recover ammonia. The absorption tower adopts dilute formaldehyde-clean water two-stage absorption, and the absorption liquid at the bottom of the absorption tower 13 is sent to the ammoniation reactor 1 for use as raw material, and the tail gas after absorption meets the emission standards.

[0036] Since formaldehyde solution and ammonia are used to react in this device, the concentration and dosage of formaldehyde solution are easier to control, and low-concentration formaldehyde solution is easier to obtain than high-purity gas formaldehyde, and the raw material cost is low. However, the process of preparing urotropine by reacting gas formaldehyde with ammonia requires strict control of the ratio of formaldehyde to ammonia, otherwise a reverse reaction is likely to occur, generating trimethylamine, which has a foul odor and affects the quality of the product. The intermittent operation of the concentrated urotropine solution produced by the device of the utility model utilizes the reaction heat of urotropine, evaporates the water under vacuum conditions, has a long crystal growth time, has large product particles, and is popular. A mother liquor filtration device is set in this process for filtration and decolorization to remove impurities introduced and by-products generated during the production process.

[0037] The product quality specifications of hexamethylenetetramine conform to the GB9015-1998 standard in Table 1. Appearance: White or slightly hued crystals, without visible impurities.

[0038] Table 1

[0039]

Claims

1. A device for producing hexamethylenetetramine, characterized in that: The invention comprises an amination reactor and an MVR evaporator. The bottom of the amination reactor is connected to the raw material inlet of the MVR evaporator through a pipeline. The steam outlet of the MVR evaporator is connected to the inlet of the steam compressor. The concentrated liquid outlet pipeline at the bottom of the MVR evaporator is divided into two routes, one route is connected to the tube side inlet of the heat exchanger through a pipeline, and the other route is connected to the crystallization tank through a pipeline. The tube side outlet of the heat exchanger is connected to the concentrated liquid inlet of the MVR evaporator through a pipeline provided with a pump; the outlet of the steam compressor is connected to the shell side inlet of the heat exchanger through a pipeline; a hot well is provided at the shell side outlet of the heat exchanger; the bottom outlet of the hot well is connected to the inlet of the dilute ammonia water tank through a pipeline, and the outlet of the dilute ammonia water tank is connected to the upper wastewater inlet of the analytical tower through a pipeline provided with a pump; the upper condensate outlet of the analytical tower is connected to the ammonia gas inlet pipe of the amination reactor through a pipeline, and the other inlet pipe of the amination reactor is connected to the formaldehyde solution tank.

2. The device for producing hexamethylenetetramine according to claim 1, characterized in that: The bottom of the crystal receiving tank is connected to the centrifuge through a pipeline, the crystal outlet of the centrifuge is connected to the cooling and conveying equipment through a drying and conveying device, and the lower liquid port of the centrifuge is connected to the liquid storage tank, the filtering equipment, the decolorization tank, and the raw material inlet of the MVR evaporator in sequence through a pipeline equipped with a pump.

3. The device for producing hexamethylenetetramine according to claim 2, characterized in that: The filtering equipment is a plate filter press, the inlet pipe of the plate filter press is connected to the liquid storage tank through a pipeline, a delivery pump is provided on the pipeline, the filtrate outlet pipe of the plate filter press is connected to the decolorization tank through a pipeline, and the decolorization tank is filled with activated carbon.

4. The device for producing hexamethylenetetramine according to claim 1, characterized in that: The cooling and conveying equipment uses a jacket cooling cage.

5. The device for producing hexamethylenetetramine according to claim 2, characterized in that: The drying and conveying device includes a screw conveying dryer, a drum dryer, and a vacuum rake dryer.

6. The device for producing hexamethylenetetramine according to claim 1, characterized in that: The tail gas outlet of the ammoniation reactor is connected to the absorption tower through a pipeline, and the liquid outlet of the absorption tower is connected to the inlet pipe of the ammoniation reactor through a pipeline.

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