Waste heat utilization type urea dissolving device

Abstract

This utility model relates to the field of urea hydrolysis for ammonia production. The aim is to provide a waste heat utilization urea dissolving device, comprising at least two rectangular dissolving tanks arranged side-by-side. The opposite side of two adjacent dissolving tanks serves as a heat exchange side, and heat exchange occurs between the tanks through this side. The dissolving tanks of this utility model can operate simultaneously to achieve large-scale single-batch production of urea solution, or they can operate alternately, thus fully utilizing the waste heat from the cooling phase of the dissolving tanks to preheat adjacent tanks, achieving energy saving and consumption reduction. Furthermore, by combining two or more tanks in a skid-mounted design, installation space and time can be effectively saved.

Description

Technical Field

[0001] This utility model relates to the field of urea hydrolysis for ammonia production technology, specifically to a waste heat utilization type urea dissolution device. Background Technology

[0002] In flue gas denitrification systems, ammonia produced through urea hydrolysis is used for denitrification. The raw material for ammonia hydrolysis is granular urea. Traditional urea dissolution typically employs a single-tank intermittent dissolution method, where urea granules are added in a tanker or external tank at once, followed by heating and stirring with hot water or steam. Because traditional single-tank dissolution requires emptying the solution after each dissolution before the next batch can be added, production continuity is poor and time-consuming, especially impacting system efficiency in large-scale industrial applications (such as power plant denitrification).

[0003] While some existing technologies utilize parallel operation of two or more single tanks for continuous production, a significant drawback is the inability to recover heat from the tanks. Direct discharge or cooling of the high-temperature dissolved solution results in substantial heat waste. Furthermore, operating two or more single tanks simultaneously presents challenges such as large space requirements, high energy consumption, and complex installation. Therefore, a skid-mountable container capable of simultaneous dual-tank dissolution is needed to improve urea dissolution efficiency, achieve heat recovery, and simultaneously save installation space and costs. Summary of the Invention

[0004] The purpose of this invention is to provide a dual-tank urea dissolving device that can achieve heat recovery and reduce energy consumption.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this utility model is: a waste heat utilization urea dissolving device, comprising at least two sets of rectangular dissolving tanks arranged side by side, wherein the opposite side of two adjacent dissolving tanks is a heat exchange side, and heat exchange is formed between the dissolving tanks through the heat exchange side.

[0006] Preferably, the heat exchange sides of adjacent melting tanks share the same sidewall, which is a heat-conducting steel plate.

[0007] Preferably, each of the dissolving tanks is equipped with a circulation system, which includes circulation pipes connected to the dissolving tank at both ends, and a circulation pump, a pressure detection sensor, and a concentration detection sensor arranged sequentially along the circulation direction on the circulation pipes.

[0008] Preferably, the circulation pipe is equipped with an electric heating mechanism or a steam heating mechanism to prevent crystallization of the solution inside the pipe.

[0009] Preferably, the melting tank is provided with an insulation layer on the outside.

[0010] Preferably, the dissolving tank includes an outer tank and an inner tank disposed inside the outer tank. The top of the inner tank is open, and a stirrer is disposed inside the inner tank. The inner tank and the outer tank are connected by a connecting hole disposed on the side wall of the inner tank.

[0011] Preferably, a steam heat exchange coil for heating the inner tank is also provided outside the inner tank. The upper and lower ends of the steam heat exchange coil are respectively connected to a steam interface and a steam condensate interface provided on the side wall of the outer tank through pipelines.

[0012] Preferably, the top of the outer tank is also provided with a demineralized water interface, a drainage interface, a urea interface, a manhole, and a ventilation interface, with the demineralized water interface and the urea interface positioned opposite to the inner tank; the upper part of the outer tank is provided with an overflow interface, and the lower part is provided with a sewage discharge interface.

[0013] Preferably, the top of the outer tank is provided with two urea inlets.

[0014] Preferably, the outer tank is further provided with a temperature detection mechanism, which includes an online temperature detection sensor and a local temperature detection sensor for assisting in calibrating the detection accuracy of the online temperature detection sensor; the outer tank is also provided with a liquid level detection sensor with local display function for detecting the liquid level height inside the tank.

[0015] The beneficial effects of this invention are mainly reflected in the following aspects: the dissolving tanks can operate simultaneously to achieve large-scale single production of urea solution, or they can operate alternately, thereby making full use of the residual heat of the dissolving tanks during the cooling stage to preheat adjacent dissolving tanks, achieving the purpose of energy saving and consumption reduction. Moreover, by arranging two or more tanks together, a skid-mounted design for two or more tanks can be achieved, which can effectively save installation space and installation time. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0017] like Figure 1As shown, this utility model is a waste heat utilization urea dissolving device used to dissolve granular urea in urea-to-ammonia production. Unlike traditional single-layer, single-tank designs, it includes at least two sets of rectangular dissolving tanks 0 arranged side-by-side. The opposite side of two adjacent dissolving tanks 0 forms a heat exchange side 30, through which heat exchange occurs between the tanks 0. In other words, this utility model has at least two dissolving tanks 0, as shown in the figure, typically two. The dissolving tanks 0 can operate simultaneously to achieve large-scale single-batch production of urea solution, or they can operate alternately, thus fully utilizing the waste heat from the cooling phase of the dissolving tanks 0 to preheat adjacent tanks 0, achieving energy saving and consumption reduction. Furthermore, by combining two or more tanks in a skid-mounted design, it effectively saves installation space and time.

[0018] It is foreseeable that, as Figure 1 As shown, this utility model has two dissolving tanks 0, but it can actually have multiple dissolving tanks 0, such as 4 or 6. Here, we take 4 as an example. The 4 dissolving tanks 0 can be arranged in a matrix to form two rows side by side. The operation mode can be two groups of two. When running, the two diagonally opposite dissolving tanks 0 and the two diagonally opposite dissolving tanks 0 of another group have a total of 4 heat exchange sides 30. Through the interactive operation of the two groups of dissolving tanks 0, better heat exchange is achieved.

[0019] In this invention, the heat exchange sides 30 of adjacent melting tanks 0 can each adopt a side plate, and the side plates can be combined with heat-conducting plates, heat-conducting silicone, etc. to form good heat exchange. However, a better approach is to share the same side wall, which is a heat-conducting steel plate, and directly utilize the heat-conducting steel plate to form heat exchange.

[0020] The dissolving tank 0 of this invention is equipped with a circulation system. The circulation system includes circulation pipes 31 connected to the dissolving tank 0 at both ends, and a circulation pump 32, a pressure sensor 33, and a concentration sensor 34 sequentially arranged along the circulation direction on the circulation pipes 31. The solution circulates within the tank via the circulation pump 32. The pressure sensor 33 detects whether the pressure after the circulation pump 32 is normal, and the concentration sensor 34 detects whether the solution concentration meets the set requirements. In addition, the circulation pipe 31 is generally equipped with an electric or steam heating mechanism to prevent crystallization of the solution within the pipe. The dissolving tank 0 is externally equipped with an insulation layer. The specific construction of the insulation layer can vary, including insulation boards, insulation jackets, etc. Due to the numerous and relatively conventional structures, they will not be described in detail in this invention.

[0021] The dissolving tank 0 of this utility model includes an outer tank 1 and an inner tank 2 disposed inside the outer tank 1. Generally, the outer tank 1 is a rectangular flat-bottomed container. The top opening of the inner tank 2 facilitates the addition and overflow of materials. An agitator 3 is disposed inside the inner tank 2. The agitator 3 can be any commercially available agitator with good longitudinal and transverse flow dispersing effects. In order to improve the dissolution rate of urea granules in the inner tank 2, a baffle plate for cooperating with the agitator 3 can also be disposed inside the inner tank 2.

[0022] The inner barrel 2 and the outer tank 1 of this utility model are connected by a connecting hole 4 provided on the side wall of the inner barrel 2. The number of connecting holes 4 can be set multiple times and they are arranged around the inner barrel 2. In addition, in order to improve the efficiency of adding dissolved water, when a large amount of dissolved water is required, it would be inefficient to discharge the dissolved water into the outer tank 1 through the connecting hole 4 alone. Therefore, an overflow gap 18 can be provided between the top of the inner barrel 2 and the top of the outer tank 1. That is, there is a gap of a certain width between the top of the inner barrel 2 and the top of the outer tank 1, so that the dissolved water in the inner barrel 2 can quickly overflow into the outer tank 1.

[0023] During the production process, the initial dissolution is carried out in the inner tank 2. Since the inner tank 2 is relatively smaller than the outer tank 1, the stirrer 3 effectively improves the dissolution efficiency of granular urea and dissolved water (excluding saline or hydrophobic solutions) within the inner tank 2. The initially dissolved solution is temporarily stored in the outer tank 1 through the connecting hole 4, and naturally mixes with the dissolved water in the outer tank 1 to form a urea solution of the target concentration. This invention achieves the dissolution of granular urea through a combination of initial dissolution and natural mixing, which greatly improves dissolution efficiency, accelerates the dissolution speed, and can adapt to small-batch urea dissolution, meeting diverse production needs.

[0024] To further improve the dissolution rate of granular urea within the inner tank 2 of this invention, a better approach is to also install a steam heat exchange coil 5 outside the inner tank 2 for heating the inner tank 2. The upper and lower ends of the steam heat exchange coil 5 are connected via pipes 6 to a steam interface 7 and a steam condensate interface 8 located on the side wall of the outer tank 1, respectively. The steam interface 7 is connected to a steam source such as a boiler room, while the steam condensate interface 8 is connected to a condensate collection point (condensate tank). Before adding the granular urea, this invention can first introduce steam to raise the temperature of the dissolving water, thereby increasing the dissolution rate of the granular urea.

[0025] Regarding the interface settings of this utility model, such as Figure 1As shown, the top of the outer tank 1 is also equipped with a demineralized water interface 10A, a drainage interface 10B, a urea interface 11, a manhole 12, and a ventilation interface 13. The positions of the demineralized water interface 10A and the urea interface 11 are opposite to those of the inner tank 2. The demineralized water interface 10A is used for the introduction of demineralized water, the drainage interface 10B is used for the introduction of drainage, and the urea interface 11 is used for the introduction of granular urea. The positions of the demineralized water interface 10A and the urea interface 11 need to correspond to the openings at the top of the inner tank 2. Two urea interfaces 11 are provided on each outer tank 1 to meet various feeding methods, such as screw feeder feeding, bucket elevator feeding, conveyor belt feeding, etc. Taking a system with two dissolving tanks 0 as an example, it has four urea interfaces 11. The upper part of the outer tank 1 is equipped with an overflow interface 35, and the lower part is equipped with a drain interface 36. The overflow interface 35 is connected to the overflow pipe, and the drain interface 36 is directly connected to the drain pipe.

[0026] In addition, this utility model also includes a temperature detection mechanism located in the outer tank 1. The temperature detection mechanism includes an online temperature sensor 14 and a local temperature sensor 15 for assisting in calibrating the detection accuracy of the online temperature sensor 14. The online temperature sensor 14 is used to detect the temperature inside the tank and transmit the data back to the control system, while the local temperature sensor 15 mainly assists in judging whether the temperature detected by the online temperature sensor 14 is accurate. To achieve liquid level detection inside the outer tank 1, a liquid level sensor 17 with local display function is also provided on the outer tank 1 for detecting the liquid level inside the tank.

[0027] During operation, demineralized water is introduced through demineralized water inlet 10A, condensate is introduced through condensate inlet 10B, and steam is introduced through steam inlet 7 to heat the dissolved water. The heated uncondensed steam flows back from the condensate inlet to the condensate collection point and re-enters the steam cycle, or is added to the dissolving tank 0 through condensate inlet 10B. After the dissolved water (demineralized water and condensate) is heated, ventilation is provided through ventilation inlet 13, and stirrer 3 is turned on. Once the temperature sensor detects that the required temperature has been reached, granular urea is introduced through urea inlet 11 into the inner tank 2. The granular urea dissolves rapidly in the inner tank 2, and the dissolved solution enters the outer tank 1 for temporary storage through the connecting hole 4 at the bottom of the inner tank. The temperature sensor detects whether the temperature inside the tank is normal, and the liquid level sensor 17 detects whether the liquid level inside the tank is up to standard.

Claims

1. A waste heat utilization urea dissolving device, characterized in that: It includes at least two rectangular melting tanks (0) arranged side by side, with the opposite side of the two adjacent melting tanks (0) being a heat exchange side (30), and heat exchange is formed between the melting tanks (0) through the heat exchange side (30).

2. The waste heat utilization type urea dissolving apparatus according to claim 1, characterized by: The heat exchange sides (30) of adjacent melting tanks (0) share the same sidewall, which is a heat-conducting steel plate.

3. The waste heat utilization type urea dissolving apparatus according to claim 2, characterized by: Each of the dissolving tanks (0) is equipped with a circulation system, which includes a circulation pipe (31) that is connected to the dissolving tank (0) at both ends, and a circulation water pump (32), a pressure detection sensor (33), and a concentration detection sensor (34) that are sequentially arranged on the circulation pipe (31) along the circulation direction.

4. The waste heat utilization type urea dissolving apparatus according to claim 3, characterized by: The circulation pipe (31) is equipped with an electric heating mechanism or a steam heating mechanism to prevent the solution inside the pipe from crystallizing.

5. The waste heat utilization type urea dissolving apparatus according to claim 4, characterized in that: The melting tank (0) is provided with an insulation layer on the outside.

6. The waste heat utilization type urea dissolving apparatus according to claim 5, characterized by: The dissolving tank (0) includes an outer tank (1) and an inner tank (2) disposed inside the outer tank (1). The top of the inner tank (2) is open and a stirrer (3) is disposed inside. The inner tank (2) and the outer tank (1) are connected by a connecting hole (4) disposed on the side wall of the inner tank (2).

7. The waste heat utilization type urea dissolving apparatus according to claim 6, characterized by: The inner tank (2) is also provided with a steam heat exchange coil (5) for heating the inner tank (2). The upper and lower ends of the steam heat exchange coil (5) are respectively connected to the steam interface (7) and the steam condensate interface (8) provided on the side wall of the outer tank (1) through pipes (6).

8. The waste heat utilization type urea dissolving apparatus according to claim 7, characterized by: The top of the outer tank (1) is also provided with a demineralized water interface (10A), a condensate interface (10B), a urea interface (11), a manhole (12) and a ventilation interface (13). The positions of the demineralized water interface (10A) and the urea interface (11) are opposite to the inner tank (2). The upper part of the outer tank (1) is provided with an overflow interface (35) and the lower part is provided with a sewage discharge interface (36).

9. The waste heat utilization type urea dissolving apparatus according to claim 8, characterized in that: The top of the outer tank (1) is provided with two urea inlets (11).

10. The waste heat utilization type urea dissolving apparatus according to claim 9, characterized by: The outer tank (1) is also equipped with a temperature detection mechanism, which includes an online temperature detection sensor (14) and a local temperature detection sensor (15) for assisting in calibrating the detection accuracy of the online temperature detection sensor (14); the outer tank (1) is also equipped with a liquid level detection sensor (17) with local display function for detecting the liquid level height in the tank.

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