Continuous production equipment for paraformaldehyde

Abstract

The utility model discloses continuous production equipment for paraformaldehyde, and relates to the technical field of chemical production equipment. The continuous production equipment for the paraformaldehyde comprises a flash tower, a heat preservation device, a spray granulation tower and a dryer, an evaporator is arranged on a tower kettle of the flash tower, a feeding port of the evaporator is connected with a fresh formaldehyde feeding pipe and a backflow formaldehyde feeding pipe, the feeding end of the backflow formaldehyde feeding pipe is connected with a discharging port in the tower bottom of the flash tower, and the discharging end of the backflow formaldehyde feeding pipe is connected with a discharging port in the tower bottom of the flash tower. A first formaldehyde extraction pipe is arranged on a branch of the backflow formaldehyde feeding pipe, and a discharging opening of the evaporator is connected with a material returning opening in the lower portion of the flash tower through a first backflow pipe; and the heat preservation device is arranged at the bottom of the flash tower, on the reflux formaldehyde feeding pipe, on the first reflux pipe and on the first formaldehyde extraction pipe. According to the utility model, the evaporator, the flash tower and the heat preservation device are combined, so that a formaldehyde aqueous solution meeting spray granulation conditions can be prepared, and the problem of polymerization caused by overhigh local concentration of formaldehyde can be effectively avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of chemical production equipment, especially relates to a continuous production equipment of oligomeric formaldehyde. BACKGROUND

[0002] Oligomeric formaldehyde shows extensive application prospect in chemical industry, pharmacy and other industrial fields due to its high effective component content and solid particle form.

[0003] The production equipment of oligomeric formaldehyde includes multistage membrane evaporator, spray granulation tower and dryer, the multistage membrane evaporator carries out step-by-step concentration to formaldehyde aqueous solution, the spray granulation tower sprays the concentrated formaldehyde aqueous solution in the form of mist, makes formaldehyde aqueous solution dry rapidly in hot airflow, and forms granular oligomeric formaldehyde.

[0004] The prior art adopts multistage falling film evaporation mode to carry out concentration treatment to formaldehyde aqueous solution, the gasification rate during heat exchange is uncontrollable in the falling film evaporation process, excessive evaporation is prone to be produced, local formaldehyde concentration is high, formaldehyde is easy to polymerize into block, and the equipment is blocked, the existing membrane evaporation equipment basically needs to stop and clean every two weeks, a large amount of energy consumption is caused, and the yield is also affected. UTILITY MODEL CONTENT

[0005] The utility model discloses a kind of oligomeric formaldehyde continuous production equipment, to solve the problem that local formaldehyde concentration is too high when the existing formaldehyde production equipment is concentrated to formaldehyde.

[0006] To achieve the above-mentioned purpose, the utility model provides a kind of oligomeric formaldehyde continuous production equipment, comprising: flash tower, heat preservation device, spray granulation tower, dryer and screening machine;

[0007] The tower kettle of the flash tower is provided with an evaporator, the feed inlet of the evaporator is connected with fresh formaldehyde feed pipe and reflux formaldehyde feed pipe, the feed end of the reflux formaldehyde feed pipe is connected with the discharge port of the bottom of the flash tower, the first formaldehyde production pipe is arranged on the branch of the reflux formaldehyde feed pipe, and the discharge port of the evaporator is connected with the reflux port of the lower part of the flash tower through the first reflux pipe;

[0008] The heat preservation device is installed on the bottom of the flash tower, the reflux formaldehyde feed pipe, the first reflux pipe and the first formaldehyde production pipe;

[0009] The top of the spray granulation tower is provided with a spraying device, the spraying device is connected with the discharge end of the first formaldehyde production pipe, and a pressure pump is arranged on the first formaldehyde production pipe;

[0010] The feed end of the dryer is connected with the discharge port of the spray granulation tower.

[0011] The feed inlet of the screening machine is connected with the discharge outlet of the dryer.

[0012] In an embodiment, the middle part of the flash tower is provided with a condensation section, and the top part is provided with a tail gas discharge pipe.

[0013] In an embodiment, the condensation section comprises a formaldehyde side line pipe, a reflux pump, a condenser and a second reflux pipe connected in sequence, the feed end of the formaldehyde side line pipe is connected with the discharge outlet of the middle part of the flash tower, the liquid outlet end of the second reflux pipe is connected with the material return port of the upper part of the flash tower, and the second formaldehyde extraction pipe is arranged on the branch of the second reflux pipe.

[0014] In an embodiment, one side of the upper part of the spray granulation tower is provided with a heat source input port, and the other side of the upper part is provided with a dust-containing gas flow discharge port.

[0015] The low-poly formaldehyde continuous production equipment further comprises a first cyclone dust collector, the gas inlet end of the first cyclone dust collector is connected with the dust-containing gas flow discharge port through a pipeline, the discharge end is connected with the spray granulation tower through a pipeline, and the gas outlet end is connected with the formaldehyde absorption tower through a recovery pipeline.

[0016] In an embodiment, the dryer is a fluidized bed dryer, the fluidized bed dryer comprises at least two drying chambers connected in series, the exhaust port of each drying chamber is connected with the gas inlet end of a second cyclone dust collector through a pipeline, and the gas outlet end of the second cyclone dust collector is connected with the recovery pipeline through a pipeline.

[0017] In an embodiment, the top of the formaldehyde absorption tower is provided with a nitrogen extraction pipe, the gas outlet end of the nitrogen extraction pipe is connected with the heat source input port of the spray granulation tower and the heat source input port of each drying chamber respectively, and a gas pump and a fresh nitrogen input pipe are arranged on the nitrogen extraction pipe.

[0018] In an embodiment, the heat preservation device comprises a jacket, the jacket is sleeved on the outer wall of the bottom part of the flash tower, the reflux formaldehyde feed pipe, the first reflux pipe and the first formaldehyde extraction pipe.

[0019] The jacket is provided with a medium inlet and a medium outlet connected with the medium inlet.

[0020] In an embodiment, the low-poly formaldehyde continuous production equipment further comprises a circulating pump and a filter arranged on the reflux formaldehyde feed pipe, and the circulating pump, the filter and the feed end of the first formaldehyde extraction pipe are arranged in sequence along the material circulation direction.

[0021] The technical scheme of the utility model discloses, the fresh formaldehyde water solution of concentration 45-57wt% enters the evaporimeter through fresh formaldehyde feed pipe, the formaldehyde water solution of concentration 70-95wt% of reflux enters the evaporimeter through reflux formaldehyde feed pipe, and the formaldehyde water solution of reflux comes from the tower bottom material of flash tower, and the evaporimeter carries out preheating treatment to formaldehyde water solution, and the material after preheating is sent to the flash tower and carries out flash separation.

[0022] At the bottom of the flash tower, the preheated material is subjected to reduced pressure flash evaporation, the tower bottom material is 70-95wt% concentrated formaldehyde water solution, the tower middle material is flash gas, including most of water and a small amount of formaldehyde, and the tower top material is vacuum tail gas. The tower bottom material is extracted and sent to a filter to filter out impurities. After filtration, part of the formaldehyde water solution is refluxed to the feed inlet of the evaporimeter through the reflux formaldehyde feed pipe to serve as the reflux formaldehyde water solution, and the remaining part of the formaldehyde water solution is sent to the spray granulation tower through the first formaldehyde extraction pipe. The concentrated formaldehyde water solution with a concentration of 70-95wt% is kept warm during the material conveying process, and the concentrated formaldehyde water solution is pumped to the spray granulation tower at a relatively fast speed after being pressurized by a pressure pump, thereby reducing the residence time of the concentrated formaldehyde water solution in the first formaldehyde extraction pipe and avoiding the polymerization problem caused by excessively high local concentration of formaldehyde.

[0023] The technical scheme of the utility model discloses discards the common multistage thin film evaporimeter to carry out step-by-step concentration to formaldehyde water solution, and adopts the combination mode of evaporimeter, flash tower and heat preservation device, that is, formaldehyde water solution meeting the spray granulation condition can be prepared, and the polymerization problem caused by excessively high local concentration of formaldehyde can be effectively avoided, and the continuous production mode can be better met. The polymerization degree of the oligomeric formaldehyde product prepared by using the production equipment of the utility model is 9-11, and the purity can reach 92-96wt%. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained according to the structures shown in the drawings without creative labor for those skilled in the art.

[0025] Figure 1 The structure schematic view of one embodiment of the oligomeric formaldehyde continuous production equipment provided by the utility model.

[0026] EXPLANATION OF DRAWINGS:

[0027] 1. flash column; 11. filter; 12. evaporator; 13. jacket; 14. reflux formaldehyde feed pipe; 15. first reflux pipe; 16. first formaldehyde take-off pipe; 17. fresh formaldehyde feed pipe; 18. formaldehyde side-draw take-off pipe; 19. second formaldehyde take-off pipe; 110. tail gas vent pipe; 2. spray granulator column; 21. spray device; 22. heat source input port; 23. pressurization pump; 3. dryer; 31. drying chamber; 4. sifter; 5. first cyclone; 6. formaldehyde absorption column; 61. recovery pipe; 62. nitrogen take-off pipe; 63. fresh nitrogen input pipe; 64. branch pipe; 641. heating device; 7. second cyclone.

[0028] The realization, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0030] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, movement condition, etc. between the components in a certain specific posture, and if the specific posture changes, the directional indications also change accordingly.

[0031] In addition, if the embodiments of the present application involve descriptions of "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include at least one of the features. In addition, "and / or" or "and / or" appearing throughout the text means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B simultaneously satisfy the scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection required by the present application.

[0032] The prior art adopts a multi-stage falling film evaporation mode to concentrate formaldehyde aqueous solution, and in the falling film evaporation process, the vaporization rate during heat exchange is uncontrollable, excessive evaporation is prone to occur, the local formaldehyde concentration is high, formaldehyde is easy to polymerize into blocks, and the equipment is blocked, the existing thin film evaporation equipment basically needs to be stopped and cleaned every two weeks, causing a large amount of energy consumption, and also affecting the yield.

[0033] In view of this, the utility model provides a continuous production equipment of oligomeric formaldehyde to solve the problem of the existing formaldehyde production equipment that is prone to have too high local formaldehyde concentration when concentrating formaldehyde.

[0034] Please refer to Figure 1 In an embodiment of the utility model, the continuous production equipment of oligomeric formaldehyde includes: a flash tower 1, a heat preservation device, a spray granulation tower 2 and a dryer 3, the tower kettle of the flash tower 1 is provided with an evaporator 12, the feed inlet of the evaporator 12 is connected with a fresh formaldehyde feed pipe 17 and a reflux formaldehyde feed pipe 14, the feed end of the reflux formaldehyde feed pipe 14 is connected with the discharge port of the bottom of the flash tower 1, the reflux formaldehyde feed pipe 14 is provided with a first formaldehyde production pipe 16 on the branch, the discharge port of the evaporator 12 is connected with the back feed port of the lower part of the flash tower 1 through a first reflux pipe 15, the heat preservation device is installed on the bottom of the bottom of the flash tower 1, the reflux formaldehyde feed pipe 14, the first reflux pipe 15 and the first formaldehyde production pipe 16, the top of the spray granulation tower 2 is provided with a spraying device 21, the spraying device 21 is connected with the discharge end of the first formaldehyde production pipe 16, and the bottom of the spray granulation tower 2 is provided with a discharge port, the feed end of the dryer 3 is connected with the discharge port, and the dryer 3 is provided with a discharge port.

[0035] In the technical scheme of the utility model, the fresh formaldehyde aqueous solution with the concentration of 45-57wt% enters the evaporator 12 through the fresh formaldehyde feed pipe, the reflux formaldehyde aqueous solution with the concentration of 70-95wt% enters the evaporator 12 through the reflux formaldehyde feed pipe 14, the reflux formaldehyde aqueous solution comes from the tower bottom material of the flash tower 1, the working temperature of the evaporator 12 is controlled to be 85 DEG C, the evaporator 12 carries out preheating treatment to the formaldehyde aqueous solution, and the preheated material is sent to the flash tower 1 through the first reflux pipe 15, and the heat preservation device insulates the tower bottom material of the flash tower 1, the material in the reflux formaldehyde feed pipe 14, the material in the first reflux pipe 15 and the material in the first formaldehyde production pipe 16.

[0036] The preheated material is subjected to flash evaporation in the flash tower 1 under negative pressure, with a vacuum degree of 50-95 kPa and a temperature of 85 DEG C. The material at the bottom of the tower is a 70-95 wt% formaldehyde aqueous solution, the material in the middle of the tower is flash gas, and the material at the top of the tower is vacuum tail gas. The material at the bottom is collected and sent to the filter 11 to remove impurities. After filtration, part of the formaldehyde aqueous solution is returned to the feed inlet of the evaporator 12 through the reflux formaldehyde feed pipe 14 as reflux formaldehyde aqueous solution, and the rest of the formaldehyde aqueous solution is sent to the spray granulation tower 2 through the first formaldehyde collection pipe 16. The formaldehyde aqueous solution with a concentration of 70-95 wt% is kept warm during the material conveying process, and a pressurizing pump 23 is arranged on the first formaldehyde collection pipe 16. The high-concentration formaldehyde aqueous solution is pumped to the spray granulation tower at a faster speed, thereby avoiding the problem of polymerization caused by too high local concentration of formaldehyde.

[0037] In the spray granulation tower 2, the pressure in the spray device is controlled to be 2.5 MPa, and the temperature is 16 DEG C. The formaldehyde aqueous solution with a concentration of 70-95 wt% is sprayed out through the spray device 21. The misty formaldehyde droplets are rapidly dried in the hot gas stream to form granular oligomeric formaldehyde. The oligomeric formaldehyde is discharged through the discharge port and sent to the dryer 3. The drying temperature is controlled to be 85 DEG C. After drying, it is sent to the screening machine 4 to screen the oligomeric formaldehyde with a particle size meeting the requirements.

[0038] The technical scheme of the utility model discloses discards the common multistage thin film evaporator to formaldehyde aqueous solution and carries out step-by-step concentration, and adopts the combination mode of evaporator 12, flash tower 1 and heat preservation device, that is, formaldehyde aqueous solution meeting the spray granulation condition can be prepared, and the problem of polymerization caused by too high local concentration of formaldehyde can be effectively avoided, and the continuous production mode can be preferably met. The polymerization degree of the oligomeric formaldehyde product prepared by the production equipment of the utility model is 9-11, and the purity can reach 92-96 wt%.

[0039] Specifically, the heat preservation device comprises a jacket 13, the jacket 13 is sleeved on the outer wall of the bottom of the flash tower 1, the reflux formaldehyde feed pipe 14, the first reflux pipe 15 and the first formaldehyde collection pipe 16, the jacket 13 is provided with a medium inlet and a medium outlet communicated with the medium inlet.

[0040] By adopting the above technical scheme, the jacket 13 is sleeved on the outer wall of the bottom of the flash tower 1, the reflux formaldehyde feed pipe 14, the first reflux pipe 15 and the first formaldehyde collection pipe 16, the hot water at 100 DEG C or above enters the jacket 13 from the medium inlet of the jacket 13, and is discharged from the medium outlet of the jacket 13 after heat exchange, so as to circulate, thereby keeping the formaldehyde aqueous solution warm.

[0041] In the embodiment of the utility model, the oligomeric formaldehyde continuous production equipment further includes a circulating pump arranged on the reflux formaldehyde feed pipe 14, and along the circulating direction of the material, the circulating pump, the filter 11 and the feed end of the first formaldehyde extraction pipe 16 are sequentially arranged. The circulating pump pumps out the tower bottom material of the flash tower 1, after filtration, part of which is refluxed to the evaporator 12, and the rest is extracted to the spray granulation tower 2.

[0042] Specifically, the middle part of the flash tower 1 is provided with a condensation section, and the top of the flash tower 1 is provided with a tail gas discharge pipe 110. The condensation section includes a formaldehyde side line extraction pipe 18, a reflux pump, a condenser and a second reflux pipe which are sequentially connected, the feed end of the formaldehyde side line extraction pipe 18 is connected with the discharge port of the middle part of the flash tower 1, the liquid outlet end of the second reflux pipe is connected with the material return port of the upper part of the flash tower 1, and the second formaldehyde extraction pipe 19 is arranged on the branch of the second reflux pipe. The flash gas in the middle part of the tower is extracted through the formaldehyde side line extraction pipe 18, after condensation, part of the condensed liquid is refluxed, and the rest of the condensed liquid is extracted through the second formaldehyde extraction pipe 19.

[0043] In the embodiment of the utility model, one side of the upper part of the spray granulation tower 2 is provided with a heat source input port 22, and the other side of the upper part of the spray granulation tower 2 is provided with a dust-containing gas flow discharge port; the oligomeric formaldehyde continuous production equipment further includes a first cyclone dust collector 5, the air inlet end of the first cyclone dust collector 5 is connected with the dust-containing gas flow discharge port through a pipeline, the discharge end is connected with the spray granulation tower 2 through a pipeline, and the air outlet end is connected with a formaldehyde absorption tower 6 through a recovery pipe 61. The dryer 3 is a fluidized bed dryer, the fluidized bed dryer includes at least one drying chamber 31, a plurality of drying chambers 31 are connected in series, the exhaust ports of the drying chambers 31 are connected with the air inlet end of a second cyclone dust collector 7 through corresponding pipelines, and the air outlet end of the second cyclone dust collector 7 is connected with the recovery pipe 61 through a pipeline.

[0044] By adopting the above technical scheme, the heat sources of the spray granulation tower 2 and the fluidized bed dryer are both heated nitrogen flow. The dust-containing gas flow generated in the spray granulation process and the dust-containing gas flow generated in the drying process are sent into the corresponding cyclone dust collectors, the cyclone dust collectors perform gas-solid separation on the dust-containing gas flow, the separated gas contains formaldehyde and nitrogen, the separated gas is sent into the formaldehyde absorption tower 6 through the recovery pipe 61, so that the formaldehyde and the nitrogen are separated, the nitrogen extracted from the top of the tower can be used as the nitrogen source for the spray granulation and the fluidized drying after being heated, or fresh nitrogen can be appropriately supplemented according to the production requirement, and the fresh nitrogen and the recovered nitrogen are used as the heat sources for the spray granulation and the drying after being heated. It can be understood that each drying chamber 31 is provided with a corresponding heat source input port and an exhaust port. The solid particulate matter separated by the first cyclone dust collector 5 is refluxed into the spray granulation tower 2 to participate in the next spray granulation.

[0045] Specifically, the fluidized bed dryer has 5 drying chambers 31 connected in series, so that the product can be dried in the drying chambers 31 in turn to better meet the production requirements. It can be understood that the heat source input and exhaust of each drying chamber 31 are independent.

[0046] In order to better supply the heat source for the spray granulation tower 2 and the drying chambers 31, the top of the formaldehyde absorption tower 6 is provided with a nitrogen extraction pipe 62, the exhaust end of the nitrogen extraction pipe 62 is connected with the heat source input port 22 of the spray granulation tower 2 and the heat source input port of the dryer respectively, and the nitrogen extraction pipe 62 is provided with a gas pump and a fresh nitrogen input pipe 63.

[0047] By adopting the above technical scheme, the nitrogen extraction pipe 62 is provided with a plurality of branch pipes 64, the plurality of branch pipes 64 are arranged one by one with the heat source input port 22 of the spray granulation tower 2 and the heat source input port of the plurality of drying chambers 31, and each branch pipe 64 is provided with a heating device 641. The nitrogen extracted from the top of the formaldehyde absorption tower 6 is divided into each branch pipe 64 through the nitrogen extraction pipe 62, and then enters the corresponding spray granulation tower 2 and each drying chamber 31. It can be understood that the top of each drying chamber 31 is provided with a corresponding exhaust port, and each exhaust port is connected with the gas inlet end of the second cyclone dust collector 7 through a corresponding pipeline.

[0048] The above is only an exemplary embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made by using the content of the present application specification and drawings, or directly / indirectly applied in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A continuous production apparatus for oligomeric formaldehyde, characterized by, The application relates to a continuous production equipment for oligomeric formaldehyde. The equipment comprises a flash tower, a heat preservation device, a spray granulation tower, a dryer and a screening machine. The tower kettle of the flash tower is provided with an evaporator, the feeding port of the evaporator is connected with a fresh formaldehyde feeding pipe and a reflux formaldehyde feeding pipe, the feeding end of the reflux formaldehyde feeding pipe is connected with the discharging port of the bottom of the flash tower, a first formaldehyde extraction pipe is arranged on the reflux formaldehyde feeding pipe in a branch mode, the discharging port of the evaporator is connected with the reflux port of the lower part of the flash tower through a first reflux pipe. The heat preservation device is arranged on the bottom of the flash tower, the reflux formaldehyde feeding pipe, the first reflux pipe and the first formaldehyde extraction pipe. A spraying device is arranged on the top of the spray granulation tower, the spraying device is connected with the discharging end of the first formaldehyde extraction pipe, and a pressurizing pump is arranged on the first formaldehyde extraction pipe. The feeding end of the dryer is connected with the discharging port of the spray granulation tower. The feeding port of the screening machine is connected with the discharging port of the dryer.

2. The continuous production apparatus for oligomeric formaldehyde according to claim 1, characterized by The middle part of the flash tower is provided with a condensing section, and the top is provided with a tail gas discharging pipe.

3. The continuous production apparatus for oligomeric formaldehyde according to claim 2, wherein The condensing section comprises a formaldehyde side line extraction pipe, a reflux pump, a condenser and a second reflux pipe which are sequentially connected, the feeding end of the formaldehyde side line extraction pipe is connected with the discharging port of the middle part of the flash tower, the liquid outlet end of the second reflux pipe is connected with the reflux port of the upper part of the flash tower, and a second formaldehyde extraction pipe is arranged on the second reflux pipe in a branch mode.

4. The continuous production apparatus for oligomeric formaldehyde according to claim 1, wherein One side of the upper part of the spray granulation tower is provided with a heat source input port, and the other side of the upper part is provided with a dust-containing gas flow discharging port. The continuous production equipment for oligomeric formaldehyde further comprises a first cyclone dust collector, the air inlet end of the first cyclone dust collector is connected with the dust-containing gas flow discharging port through a pipeline, the discharging end is connected with the spray granulation tower through a pipeline, and the air outlet end is connected with a formaldehyde absorption tower through a recovery pipe.

5. The continuous production apparatus for oligomeric formaldehyde according to claim 4, wherein The dryer is a fluidized bed dryer, the fluidized bed dryer comprises at least two drying chambers which are connected in series, the exhaust ports of the drying chambers are connected with the air inlet end of a second cyclone dust collector through pipelines, and the air outlet end of the second cyclone dust collector is connected with the recovery pipe through a pipeline.

6. The continuous production apparatus for oligomeric formaldehyde according to claim 5, wherein The top of the formaldehyde absorption tower is provided with a nitrogen extraction pipe, the air outlet end of the nitrogen extraction pipe is connected with the heat source input port of the spray granulation tower and the heat source input ports of the drying chambers respectively, and a gas pump and a fresh nitrogen input pipe are arranged on the nitrogen extraction pipe.

7. The continuous production apparatus for oligomeric formaldehyde according to claim 1, wherein The heat preservation device comprises a jacket, the jacket is arranged on the outer wall of the bottom of the flash tower, the reflux formaldehyde feeding pipe, the first reflux pipe and the first formaldehyde extraction pipe. A medium inlet and a medium outlet which are in communication with the medium inlet are arranged on the jacket.

8. The continuous production apparatus for oligomeric formaldehyde according to claim 1, wherein The continuous production equipment for oligomeric formaldehyde further comprises a circulating pump and a filter which are arranged on the reflux formaldehyde feeding pipe, and the circulating pump, the filter and the feeding end of the first formaldehyde extraction pipe are sequentially arranged along the circulating direction of the material.

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