Vacuum pre-concentration device for urea recovery

Abstract

The utility model discloses a vacuum pre -concentrator for urea recovery, its characterized in that, including through pipeline connection's two section evaporative condenser, injection circulating tank, injector circulating water pump and vacuum pre -concentrator in proper order, the process condensate outlet of two section evaporative condenser is connected with the import of injection circulating tank through first pipeline, the outlet of injection circulating tank is connected with the import of injector circulating water pump through second pipeline, and the outlet of injector circulating water pump is connected with the feed inlet of vacuum pre -concentrator through third pipeline, and the concentrated liquid outlet of vacuum pre -concentrator is connected to urea evaporation system through fourth pipeline, through the flash evaporation treatment of vacuum pre -concentrator, the urea in process condensate is effectively concentrated, and the concentrated urea urine returns urea evaporation system directly and is finally sent to prilling tower, realizes the direct recovery of urea, avoids the loss of urea in the analysis hydrolysis process in traditional craft.

Description

Technical Field

[0001] This utility model belongs to the field of urea recovery technology, specifically relating to a vacuum pre-concentration device for urea recovery. Background Technology

[0002] In the urea production process, the second-stage evaporator condenser of the evaporation system produces process condensate containing urea. Current technology typically transfers this condensate to an ammonia tank, which then enters a desorption and hydrolysis system for treatment to decompose and recover the urea. However, this process route has significant drawbacks: First, the urea content in the condensate at the outlet of the second-stage evaporator condenser is high (up to 9.37%), requiring a large amount of steam for complete desorption and hydrolysis, leading to a sharp increase in product energy consumption. Second, existing desorption and hydrolysis systems do not achieve complete recovery; some ammonia-nitrogenous substances are not effectively recovered and are emitted with the exhaust gas, resulting not only in the loss of useful substances but also in atmospheric pollution, failing to meet the environmental protection requirements of green production. Therefore, there is an urgent need for a new technology and device that can efficiently and energy-savingly recover urea from process condensate and reduce the load on subsequent processing. Utility Model Content

[0003] Purpose of the utility model: In view of the shortcomings of the prior art, this utility model provides a vacuum pre-concentration device for urea recovery, which aims to directly recover urea from the process condensate by flash evaporation, avoiding its entry into the desorption and hydrolysis system, thereby significantly reducing steam consumption and exhaust gas emissions, and solving energy consumption and environmental protection problems.

[0004] To achieve the above objectives, this utility model provides the following technical solution: a vacuum pre-concentration device for urea recovery, characterized in that it comprises a two-stage evaporator-condenser, a jet circulation tank, an ejector circulation water pump, and a vacuum pre-concentrator connected sequentially by pipelines; the process condensate outlet of the two-stage evaporator-condenser is connected to the inlet of the jet circulation tank via a first pipeline; the outlet of the jet circulation tank is connected to the inlet of the ejector circulation water pump via a second pipeline, and the outlet of the ejector circulation water pump is connected to the feed inlet of the vacuum pre-concentrator via a third pipeline; the concentrate outlet of the vacuum pre-concentrator is connected to the urea evaporation system via a fourth pipeline; and the secondary steam outlet of the vacuum pre-concentrator is connected to the condensation system via a fifth pipeline.

[0005] As a preferred embodiment of this utility model, the ejector circulating water pump is provided with two pumps, one for operation and one for standby, which are connected in parallel on the second pipeline.

[0006] As a preferred technical solution of this utility model, the spray circulation tank is a vertical or horizontal pressurized or atmospheric pressure vessel, and its volume design meets the buffering requirements of the process condensate.

[0007] As a preferred embodiment of this utility model, the vacuum pre-concentrator is a vertical flash tank, which is equipped with a liquid distributor to ensure that the process condensate enters the flash chamber evenly.

[0008] As a preferred embodiment of this invention, the operating vacuum of the vacuum pre-concentrator is maintained by a condensation system and a vacuum pump assembly connected thereto.

[0009] As a preferred embodiment of this utility model, the fourth pipe is connected to the inlet of the first or second stage evaporator of the urea evaporation system.

[0010] As a preferred embodiment of this utility model, the first pipe, the second pipe, the third pipe and the fourth pipe are all made of stainless steel that is resistant to urea corrosion.

[0011] As a preferred embodiment of this utility model, the jet circulation tank is provided with a level gauge interface and an overflow port.

[0012] Compared with the prior art, the beneficial effects of this utility model are:

[0013] (1) This invention utilizes a vacuum pre-concentrator for flash evaporation treatment, effectively concentrating urea in the process condensate. The concentrated urea is then directly returned to the urea evaporation system for purification and finally sent to the granulation tower, achieving direct urea recovery. This avoids the loss of urea during the hydrolysis process in traditional processes, significantly improving the urea recovery rate. Furthermore, the high-urea-content process condensate that originally needed to enter the hydrolysis system is intercepted and recovered, reducing the flow rate of the hydrolyzer by approximately 3 m³ / h. 3 The increased ammonia water processing capacity significantly reduced the operating load on the hydrolysis system and extended the equipment's operating cycle.

[0014] (2) In traditional processes, the hydrolysis treatment of condensate with high urea content requires a large amount of steam. This device achieves urea concentration and recovery through vacuum flash evaporation, which does not require a large amount of steam. At the same time, the reduction in the processing load of the hydrolysis system further reduces steam consumption and significantly reduces the overall energy consumption of the product. Since the urea in the process condensate is directly recovered, the total amount of ammonia nitrogen entering the hydrolysis system is reduced, which reduces the amount of ammonia nitrogen substances that are not fully recovered and are emitted with the tail gas from the source, effectively reducing air pollution and meeting the environmental protection requirements of green production.

[0015] (3) The overall structure of this utility model is simple and mainly consists of conventional equipment. It has the characteristics of low investment and small footprint. It adopts corrosion-resistant pipes and a one-on-one standby pump configuration, which reduces equipment maintenance costs and extends the operating cycle. It can be modified on the basis of existing urea production equipment and has strong practicality. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0017] Figure 1 This is an overall flowchart of the present invention; Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] Example

[0020] Please see Figure 1 This utility model provides the following technical solution: a vacuum pre-concentration device for urea recovery, characterized in that it includes a two-stage evaporator-condenser 1, a jet circulation tank 2, an ejector circulation water pump 3, and a vacuum pre-concentrator 4 connected in sequence by pipelines; the process condensate outlet of the two-stage evaporator-condenser 1 is connected to the inlet of the jet circulation tank 2 through a first pipeline; the outlet of the jet circulation tank 2 is connected to the inlet of the ejector circulation water pump 3 through a second pipeline, and the outlet of the ejector circulation water pump 3 is connected to the feed inlet of the vacuum pre-concentrator 4 through a third pipeline; the concentrate outlet of the vacuum pre-concentrator 4 is connected to the urea evaporation system 5 through a fourth pipeline; and the secondary steam outlet of the vacuum pre-concentrator 4 is connected to the condensation system 6 through a fifth pipeline.

[0021] To ensure continuous and stable system operation and avoid process interruption due to single pump failure, in this embodiment, as a preferred technical solution of the present invention, two ejector circulating water pumps 3 are provided, one as the operating pump and the other as the standby pump, and the two pumps are connected in parallel on the second pipeline.

[0022] In order to provide a stable buffer storage space for the process condensate and ensure the continuity of feeding in subsequent conveying processes, in this embodiment, as a preferred technical solution of the present invention, the spray circulation tank 2 is a vertical or horizontal pressurized or atmospheric pressure vessel, and its volume design meets the buffering requirements of the process condensate.

[0023] To ensure uniform distribution of the process condensate in the flash chamber and improve the stability and uniformity of the flash concentration effect, in this embodiment, as a preferred technical solution of the present invention, the vacuum pre-concentrator 4 is a vertical flash tank, which is equipped with a liquid distributor to ensure that the process condensate enters the flash chamber uniformly.

[0024] In order to maintain the negative pressure environment required for the flash evaporation process and promote the efficient vaporization and separation of water and ammonia in the process condensate, in this embodiment, as a preferred technical solution of the present invention, the operating vacuum of the vacuum pre-concentrator 4 is maintained by the condensation system 6 and the vacuum pump group connected thereto.

[0025] In order to smoothly connect the concentrated urea solution into the original evaporation system and achieve seamless connection with the subsequent purification and concentration process, in this embodiment, as a preferred technical solution of the present invention, the fourth pipe is connected to the inlet of the first-stage evaporator or the second-stage evaporator of the urea evaporation system 5.

[0026] In order to enhance the corrosion resistance of the pipeline to urea solution, extend the service life of the device and ensure operational safety, in this embodiment, as a preferred technical solution of the present invention, the first pipeline, the second pipeline, the third pipeline and the fourth pipeline are all made of stainless steel that is resistant to urea corrosion.

[0027] In order to achieve real-time monitoring of the liquid level of the process condensate in the jet circulation tank 2, and to ensure the safe operation of the system by overflow when the liquid level is abnormally high, in this embodiment, as a preferred technical solution of the present invention, the jet circulation tank 2 is provided with a liquid level gauge interface and an overflow port.

[0028] In this embodiment, the urea evaporation system 5 is a known technology that has been widely used in daily life. Its working principle is mainly based on the principle of steam heating and vacuum flash evaporation to concentrate and purify urine to a molten state. Its specific composition and basic principle are not improvements of this utility model, so they will not be described in detail here.

[0029] In this embodiment, the condensation system 6 is a known technology that is widely used in daily life and is already publicly disclosed. This system typically consists of a surface condenser or a mixing condenser, a hot water well, a vacuum pump, etc. Its basic principle is not an improvement of this utility model, so it will not be described in detail here.

[0030] In summary, the core working principle of this utility model, based on the above-described technical solution, is as follows:

[0031] The device uses a two-stage evaporator-condenser 1, a jet circulation tank 2, an ejector circulation water pump 3, and a vacuum pre-concentrator 4 as its core processing units, supplemented by a condensation system 6 and a urea evaporation system 5 to form a closed-loop recovery system.

[0032] In the urea production process, the process condensate with a urea content of approximately 9.37% produced by the second-stage evaporator condenser 1 no longer enters the traditional ammonia water tank, but is instead introduced into the jet circulation tank 2 for temporary storage through the first pipeline. The jet circulation tank 2, as a buffer device, is a vertical or horizontal pressurized or atmospheric pressure vessel. Its volume design meets the temporary storage requirements of the process condensate. The liquid level is monitored in real time through a liquid level gauge interface, and the overflow port ensures the safe operation of the system in case of abnormal liquid level.

[0033] The ejector circulating water pump 3 (adopting a parallel configuration of one in operation and one on standby, with two pumps installed in parallel on the second pipeline to ensure continuous and stable system operation in case of equipment failure) transports the process condensate in the ejector circulating tank 2 to the top feed port of the vacuum pre-concentrator 4 through the third pipeline at a set pressure. The vacuum pre-concentrator 4 is a vertical flash tank, and the liquid distributor installed inside it ensures that the process condensate enters the flash chamber evenly, ensuring a uniform and stable flash effect. At the same time, the operating vacuum of the vacuum pre-concentrator 4 is maintained by the connected condensation system 6 and the vacuum pump group. Under negative pressure, the water and some ammonia in the process condensate rapidly vaporize to form secondary steam, which is introduced into the condensation system 6 through the fifth pipeline for centralized treatment.

[0034] The urea solution after flash evaporation concentration (with a significant increase in urea concentration) accumulates at the bottom of the vacuum pre-concentrator 4 and is directly transported through the fourth pipeline to the inlet of the first or second stage evaporator of the urea evaporation system 5. After merging with the material in the original evaporation system, it undergoes further purification and concentration. Finally, the qualified molten urea is sent to the granulation tower to be made into the finished product.

[0035] The entire system's pipelines (first to fourth pipelines) are made of urea-resistant stainless steel, effectively resisting the corrosive effects of urea solution and ensuring long-term stable operation of the equipment.

[0036] Finally, it should be noted that, in this utility model, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0037] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A vacuum pre-concentration device for urea recovery, characterized in that, It includes a two-stage evaporator-condenser (1), a jet circulation tank (2), an ejector circulation water pump (3), and a vacuum pre-condenser (4) connected in sequence by pipes; The process condensate outlet of the two-stage evaporator condenser (1) is connected to the inlet of the jet circulation tank (2) through a first pipe; The outlet of the jet circulation tank (2) is connected to the inlet of the jetting water pump (3) through a second pipe, and the outlet of the jetting water pump (3) is connected to the feed port of the vacuum pre-concentrator (4) through a third pipe. The concentrated liquid outlet of the vacuum pre-concentrator (4) is connected to the urea evaporation system (5) through a fourth pipe; the secondary steam outlet of the vacuum pre-concentrator (4) is connected to the condensation system (6) through a fifth pipe.

2. The vacuum pre-concentration device for urea recovery according to claim 1, characterized in that, The ejector circulating water pump (3) is provided in two units, one is the running pump and the other is the standby pump. The two pumps are connected in parallel on the second pipeline.

3. A vacuum pre-concentration device for urea recovery according to claim 1 or 2, characterized in that, The jet circulation tank (2) is a vertical or horizontal pressurized or atmospheric pressure vessel, and its volume design meets the buffering requirements of the process condensate.

4. The vacuum pre-concentration device for urea recovery according to claim 1, characterized in that, The vacuum pre-concentrator (4) is a vertical flash tank, which is equipped with a liquid distributor to ensure that the process condensate enters the flash chamber evenly.

5. A vacuum pre-concentration device for urea recovery according to claim 4, characterized in that, The operating vacuum of the vacuum pre-concentrator (4) is maintained by the condensation system (6) and vacuum pump assembly connected thereto.

6. The vacuum pre-concentration device for urea recovery according to claim 1, characterized in that, The fourth pipe is connected to the inlet of the first or second stage evaporator of the urea evaporation system (5).

7. The vacuum pre-concentration device for urea recovery according to claim 1, characterized in that, The first, second, third, and fourth pipes are all made of stainless steel that is resistant to urea corrosion.

8. The vacuum pre-concentration device for urea recovery according to claim 1, characterized in that, The jet circulation tank (2) is equipped with a level gauge interface and an overflow port.

Images