Two-stage evaporation separator used in urea system

Abstract

The utility model relates to a two-section evaporation separator used in a urea system. Comprising a separator shell, a urea melt inlet is formed in the bottom of the separator shell, a separator gas phase outlet is formed in the top of the separator shell, and a flushing unit used for flushing the inner wall of the top of the separator shell and the inner wall of the separator gas phase outlet is arranged on the lower portion of the separator gas phase outlet. A buffer flow guide unit for preventing urea melt from splashing and preventing biuret from directly falling is arranged between the bottom of the flushing unit and the urea melt inlet; a urea melt outlet is formed in the separator shell corresponding to one side of the lower part of the buffer flow guide unit; the flushing frequency and energy consumption are reduced, and stable operation of follow-up equipment is achieved on the premise that the quality of urea melt liquid is guaranteed.

Description

TECHNICAL FIELD

[0001] The utility model relates to urea production system technical field, specifically a two section evaporation separator used in urea system. BACKGROUND

[0002] In the production process of urea, the liquid urea of the front-end process is separated from the unreacted carbon dioxide and ammonia gas in the flash and true flash, and then is dehydrated by the first evaporation separator and the second evaporation separator, so as to finally concentrate the urea into 99.0% molten urea solution, which is then pumped to the top of the prilling tower by the melting pump, and the qualified urea particles are obtained at the bottom of the tower after prilling. In the above process of producing urea, by-product biuret which affects the quality of urea is produced. According to research, the factors affecting the generation rate of biuret are temperature, liquid urea concentration, ammonia partial pressure, etc. Since the temperature is high and the concentration of urea is high and the ammonia partial pressure is low in the process of the second evaporation separator, biuret will inevitably be produced in this process. Therefore, as the production continues, these biuret will accumulate and agglomerate at the top of the second evaporation separator, and will fall off when it accumulates to a certain extent, falling into the urea below, directly leading to the biuret exceeding the standard in the urea product, and the agglomerates may block the urea outlet, affecting the operation of the melting pump of the subsequent equipment and causing production downtime for maintenance.

[0003] In order to solve the above technical problems, some enterprises set up a flushing pipeline to realize the timed flushing of the position where biuret is easy to accumulate. For example, the utility model patent No. CN201220010806.5, named flushing device for second evaporation separator in urea production system, discloses a circular flushing water pipe, a longitudinal flushing water pipe, a transverse flushing water pipe and an arc flushing water pipe. The timed flushing of the above four flushing water pipes can effectively prevent the accumulation of biuret. The above method can solve the problem of biuret accumulation, but frequent flushing will increase the production energy consumption, and the biuret solids flushed out still have the defect of easy blockage of the pipeline, and will cause fluctuations in the production system. UTILITY MODEL CONTENT

[0004] In order to make up for the above shortcomings, the utility model provides a second evaporation separator used in urea system to solve the technical problems existing in the prior art.

[0005] The utility model solves the technical problems by adopting the following technical scheme:

[0006] A two-stage evaporation separator used in a urea system, comprising a separator shell, a urea melt inlet provided at the bottom of the separator shell, a separator gas phase outlet provided at the top of the separator shell, a flushing unit provided at the lower part of the separator gas phase outlet for flushing the inner wall of the top of the separator shell and the inner wall at the separator gas phase outlet, and a buffer flow guide unit provided between the bottom of the flushing unit and the urea melt inlet for avoiding urea melt splashing and preventing biuret direct falling; a urea melt outlet is provided on the separator shell at the side of the lower part of the buffer flow guide unit.

[0007] The utility model discloses a flushing unit is arranged to the separator shell (namely: the part that is easy to fall into urea melt), and the buffer flow guide unit that prevents biuret direct falling is arranged at the bottom of the flushing unit, so as to realize the flushing frequency of the separator shell is saved, and the biuret that falls off is not easy to fall directly into the vicinity of urea melt outlet, so as to realize the stable operation of subsequent equipment under the premise of guaranteeing urea melt quality.

[0008] Preferably, the buffer flow guide unit comprises a funnel-shaped liquid distributor, and a hole is formed in the center of the liquid distributor.

[0009] Preferably, the outlet end of the liquid guide pipe is on the same side as the urea melt outlet.

[0010] Preferably, a mesh cover is arranged at the urea melt outlet.

[0011] Preferably, an annular baffle is arranged on the outer periphery of the upper part of the liquid distributor.

[0012] Preferably, a blocking strip that is an integral structure with the annular baffle is arranged on the outer side of the annular baffle.

[0013] Preferably, the flushing unit comprises a flushing water pipe, and the flushing water pipe is connected with an annular flushing water pipe arranged in the separator shell; and flushing water nozzles are uniformly arranged on the top of the annular flushing water pipe.

[0014] Preferably, the annular flushing water pipe comprises a flushing water main pipe and a plurality of annular pipe fittings connected with the flushing water main pipe; and the flushing water nozzles are uniformly arranged on the top of the annular pipe fittings.

[0015] The two-stage evaporation separator used in a urea system is manufactured according to the technical scheme, the flushing unit is arranged at the position where biuret can drop into the inside of the separator shell, so that the use of flushing water is reduced and the production energy consumption is reduced, the buffer flow guide unit is arranged at the lower part of the flushing unit, on the one hand, the urea melt entering the separator shell is buffered, so that the urea melt is prevented from splashing to the upper part of the separator shell, and the solid biuret is prevented from directly dropping near the urea melt outlet, so that the content of biuret in the urea melt is prevented from greatly fluctuating, further, the solid biuret is prevented from entering the subsequent equipment (such as a melt pump) with the urea melt, so that the characteristics of the urea product exceeding the biuret standard and long-time stable operation of the equipment are realized; the liquid guide pipe can realize that the urea melt quickly enters the urea melt outlet and is quickly discharged; the annular baffle is arranged, so that the characteristics of improving the receiving capacity of the solid biuret are realized, further, the baffle strip is arranged, so that the solid biuret is prevented from dropping into the lower part of the separator shell in the dissolving process; the annular flushing water pipe is arranged, so that the position where the biuret is easily gathered is uniformly and sufficiently flushed, so that the characteristics of timely removing the solid biuret are realized. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0017] Fig. 1 It is a structural schematic view of the present application.

[0018] Fig. 2 It is a structural schematic view of the annular flushing water pipe of the present application.

[0019] In the figure: 1, separator shell; 2, urea melt inlet; 3, gas phase outlet of the separator; 4, urea melt outlet; 5, liquid distributor; 6, liquid guide pipe; 7, mesh cover; 8, annular baffle; 9, baffle strip; 10, flushing water pipe; 11, annular flushing water pipe; 12, flushing water nozzle; 13, flushing water main pipe; 14, annular pipe. DETAILED DESCRIPTION

[0020] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0021] The following will be described in detail in combination with the drawings of the embodiments of the present application. Figs. 1-2 Further detailed description of the present application, the present application is a kind of two-stage evaporation separator used in urea system, the two-stage evaporation separator includes separator shell 1, the bottom of the separator shell 1 is provided with urea molten liquid inlet 2, the top of the separator shell 1 is provided with separator gas phase outlet 3, the lower part of the separator gas phase outlet 3 is provided with flushing unit for flushing the inner wall of the top of the separator shell 1 and the inner wall at the separator gas phase outlet 3, the bottom of the flushing unit and the urea molten liquid inlet 2 are provided with buffer flow guide unit for avoiding urea molten liquid splashing and preventing biuret directly falling;The lower part of the buffer flow guide unit is provided with urea molten liquid outlet 4 on one side of the corresponding separator shell 1.The present application is suitable for two-stage evaporation separator used in urea production system, the internal of two-stage evaporation separator is in the state of negative pressure and high temperature when running, for removing the moisture in urea molten liquid;Based on the above situation, the present application is provided with buffer flow guide unit, which can realize buffering and blocking after urea molten liquid enters the separator shell 1 from urea molten liquid inlet 2, to avoid urea molten liquid splashing to the inner upper part of the separator shell 1, at the same time, the upper part of the buffer flow guide unit can receive the solid biuret falling from the upper part of the separator shell 1, to avoid the direct entry of the solid biuret into urea molten liquid outlet 4, causing large range fluctuation of biuret content in urea molten liquid, and the problem of solid biuret entering into melting pump and other equipment affecting the normal operation of urea production system;Further, the flushing unit in the present application is arranged at the position where biuret is easy to be produced in the separator shell 1, which can reduce the flushing frequency of the flushing unit, to achieve the characteristics of reducing the use amount of flushing water and reducing the operating load of equipment.

[0022] Further, the buffer flow guide unit includes funnel-shaped liquid distributor 5, a hole is formed in the center position of the liquid distributor 5, and the hole is communicated with liquid guide pipe 6.Through the above setting, the urea molten liquid can be quickly and stably discharged.

[0023] Further, the outlet end of the liquid guide pipe 6 is on the same side as the urea molten liquid outlet 4.

[0024] Further, the urea melt liquid outlet 4 is provided with a mesh cover 7. By providing the mesh cover 7, a small amount of solid biuret can be melted in the urea melt liquid and then enter the urea melt liquid outlet 4, so as to avoid affecting the normal operation of the subsequent equipment.

[0025] Further, the outer circumference of the upper part of the liquid distributor 5 is provided with an annular baffle 8. By providing the annular baffle 8, the receiving range of the solid biuret can be improved, so as to avoid a large amount of biuret entering the inner lower part of the separator shell 1.

[0026] Further, the outer side of the annular baffle 8 is provided with a baffle strip 9 which is an integral structure with the annular baffle 8. By providing the baffle strip 9, the solid biuret can be prevented from falling to the inner lower part of the separator shell 1 during the dissolution of the biuret in the annular baffle 8.

[0027] Further, the flushing unit comprises a flushing water pipeline 10 which is connected with an annular flushing water pipe 11 arranged inside the separator shell 1, and the top of the annular flushing water pipe 11 is uniformly provided with flushing water nozzles 12.

[0028] Further, the annular flushing water pipe 11 comprises a flushing water main pipe 13 and a plurality of annular pipe fittings 14 connected with the flushing water main pipe 13, and the flushing water nozzles 12 are uniformly arranged on the top of the annular pipe fittings 14. By the above arrangement, the parts of the separator shell 1 where the biuret is prone to accumulate can be uniformly and sufficiently flushed, so as to meet the characteristics of timely removing the solid biuret.

[0029] The specific working process of the utility model is as follows: the two-stage evaporation separator continuously operates in the state of negative pressure and high temperature, the urea melt liquid enters the separator shell 1 through the urea melt liquid inlet 2, the gas phase is discharged through the separator gas phase outlet 3, after the equipment operates for a period of time, a large amount of solid biuret is gathered on the upper part of the separator shell 1, the flushing water enters the plurality of annular pipe fittings 14 through the flushing water pipeline 10 and the flushing water main pipe fitting 13, finally the flushing water spray head 12 is used to clean the separator shell 1, so that the solid biuret falls off, a large amount of solid biuret falls on the platform formed by the liquid distributor 5 and the annular baffle 8 surface due to the flushing of the flushing water; since the inside of the separator shell 1 is in the state of negative pressure and high temperature, the flushing water evaporates rapidly after flushing, and does not enter the urea to affect the quality of the urea; the biuret solid falling on the aforementioned platform gradually dissolves in the urea under the flushing of the urea melt liquid, and finally is discharged through the urea melt liquid outlet 4; the blocking strip 9 is arranged to prevent the solid biuret from falling to the inner lower part of the separator shell 1 during the process of dissolving the solid biuret on the aforementioned platform; part of the solid biuret falling in the inner lower part of the separator shell 1 is dissolved in the urea melt liquid (and is blocked by the mesh cover 7), and is discharged through the urea melt liquid outlet 4 after complete dissolution; since the process of dissolving biuret in urea is slow, and the amount of urea melt liquid is relatively large, the quality of urea product is almost not affected, and the problem of biuret accumulation can be well solved under the premise of ensuring the stable operation of the entire urea production system.

[0030] The basic principle, main features and advantages of the utility model are shown and described above. It should be understood by those skilled in the art that the utility model is not limited by the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principle of the utility model, and various changes and improvements can be made to the utility model without departing from the spirit and scope of the utility model, and these changes and improvements all fall within the scope of the utility model claimed.

Claims

1. A two-stage evaporator separator for use in a urea system, the two-stage evaporator separator comprising a separator shell (1), wherein the bottom of the separator shell (1) is provided with a urea molten liquid inlet (2), and the top of the separator shell (1) is provided with a separator gas phase outlet (3), characterized in that: The lower part of the separator gas phase outlet (3) is provided with a flushing unit for flushing the inner wall of the top of the separator housing (1) and the inner wall of the separator gas phase outlet (3). A buffer guide unit is provided between the bottom of the rinsing unit and the urea melt inlet (2) to prevent urea melt from splashing and to prevent biuret from falling directly; The urea melt outlet (4) is provided on the corresponding separator housing (1) on the lower side of the buffer flow guiding unit.

2. The two-stage evaporator separator used in a urea system according to claim 1, characterized in that: The buffer flow guiding unit includes a funnel-shaped liquid diffuser (5), with a hole at the center of the liquid diffuser (5) and the hole is connected to the liquid guiding pipe (6).

3. A two-stage evaporator separator used in a urea system according to claim 2, characterized in that: The outlet end of the liquid guide tube (6) is on the same side as the urea melt outlet (4).

4. A two-stage evaporator separator used in a urea system according to claim 1 or 3, characterized in that: A mesh cover (7) is provided at the outlet (4) of the urea melt.

5. A two-stage evaporator separator used in a urea system according to claim 2 or 3, characterized in that: The upper outer circumference of the liquid dispersant (5) is provided with an annular baffle (8).

6. A two-stage evaporator separator used in a urea system according to claim 5, characterized in that: The outer side of the annular baffle (8) is provided with a baffle strip (9) that is integral with the annular baffle (8).

7. A two-stage evaporator separator used in a urea system according to claim 1, characterized in that: The flushing unit includes a flushing water pipe (10), which is connected to an annular flushing water pipe (11) located inside the separator housing (1). The top of the annular flushing water pipe (11) is evenly distributed with flushing water nozzles (12).

8. A two-stage evaporator separator used in a urea system according to claim 7, characterized in that: The annular flushing water pipe (11) includes a main flushing water pipe (13) and several annular pipes (14) connected to the main flushing water pipe (13), with flushing water nozzles (12) evenly distributed on the top of the annular pipes (14).

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