CN105004201A - Urea solution hydrolysis ammonia producing reactor outlet heat exchanger - Google Patents

Abstract

The invention relates to an outlet heat exchanger of a urea solution hydrolysis ammonia production reactor, which comprises an outer heating sleeve, an inner heating sleeve and a central heating tube which are sequentially sleeved from the outside to the inside; one end of the central heating tube is connected with the outer heating sleeve and the inner The interlayer between the heating sleeves is connected, and the other end extends radially to the outside of the outer heating sleeve to set the heating medium inlet; the inner heating sleeve is used for the flow heating of the heated working fluid; the outer heating sleeve and the inner heating sleeve The interlayer between them, and the central heating tube are used for the flowing heating of the heating medium; the outer heating sleeve is provided with a heating medium outlet. By making the heating working fluid enter the central heating tube first, the heated working fluid enters the interlayer, and the heating working medium that completes the heat exchange leaves the heat exchanger and enters the heating tube bundle of the hydrolysis reactor to provide heat for the hydrolysis reaction. The hydrolysis reaction product gas flows through the middle layer of the triple casing heater, and the temperature is raised within a short distance under the heat exchange effect of the central heating tube and the inner heating casing.

Description

A kind of outlet heat exchanger of urea solution hydrolysis ammonia production reactor

technical field

The invention belongs to the technical field of urea hydrolysis ammonia production technology in a flue gas denitrification system, and in particular relates to an outlet heat exchanger of a urea solution hydrolysis ammonia production reactor.

Background technique

The combustion of coal in coal-fired power plants is accompanied by the emission of a large amount of nitrogen oxides (NO _x ), which pollutes the atmosphere. Usually, a flue gas denitrification device is installed at the tail of the boiler, and the _NOx in the flue gas is removed by selective catalytic reduction (SCR), and converted into non-toxic and harmless nitrogen (N ₂ ) and water (H ₂ O ), so as to meet the emission requirements. The denitration reducing agent ammonia (NH ₃ ) required in the selective catalytic reduction method usually has three supply forms: liquid ammonia, ammonia water and urea. Among them, liquid ammonia and ammonia water are hazardous chemicals. The country has strict laws and regulations concerning the storage, use and transportation of liquid ammonia and ammonia water. Industrial urea is a white crystalline particle, which does not belong to the category of hazardous chemicals. It is convenient for storage and transportation, and will not cause safety hazards due to leakage. Therefore, from the perspective of safety and economy, urea ammonia is gradually favored by people. By using urea solution water Solution to realize the supply of ammonia.

The product gas components of the urea hydrolysis reactor are NH ₃ , CO ₂ and water vapor. The ratio of each component is determined by the concentration of the feed urea. When the feed urea solution concentration is 50%, the product gas volume components: NH ₃ : 37.5%; _CO2 : 18.75%; _H2O : 43.75%. Usually, the operating pressure of the hydrolysis reactor is 0.7MPa and the operating temperature is 145°C. Under this pressure condition, when the product gas temperature is lower than 133°C, water vapor will condense; when the temperature is lower than 85°C, NH ₃ and CO ₂ Reverse reaction occurs to generate ammonium carbamate crystals. The above working conditions all affect safe production. Therefore, during the product gas transportation process, the transportation pipeline needs to be heat-traced and kept insulated, and the transportation temperature should not be lower than 150°C.

The existing commonly used heat exchanger adopts a jacketed heat exchanger, wherein the jacketed pipe is an inner and outer double-layer casing, the inner casing conveys working fluid, and the outer casing is a space filled with heat-tracing working fluid. The purpose of the jacketed pipe is heat tracing, so the heat exchange between the heat tracing steam and the working fluid in the inner casing is less, so the requirement for the heat exchange area is not high. However, the heater at the outlet of the hydrolysis reactor needs to increase the temperature of the product gas in a relatively short delivery space, so there is a high requirement for the heat exchange area of the heater, and the existing heat exchanger cannot meet the requirements. At the same time, in order to obtain a more ideal And fast heat exchange effect, its structure is relatively complex, takes up a lot of space, especially requires a long distance, and the stability of work is poor, and maintenance is complicated.

Contents of the invention

Aiming at the problems existing in the prior art, the invention provides a heat exchanger at the outlet of a urea solution hydrolysis ammonia production reactor with simple structure, easy processing and high heat exchange efficiency.

The present invention is realized through the following technical solutions:

A heat exchanger at the outlet of a urea solution hydrolysis ammonia production reactor, comprising an outer heating sleeve, an inner heating sleeve and a central heating tube which are sequentially sleeved from the outside to the inside; one end of the central heating tube is connected with the outer heating sleeve and the inner heating sleeve The interlayer between the tubes is connected, and the other end extends radially to the outside of the outer heating sleeve to set the heating medium inlet; the inner heating sleeve is used for the flow heating of the heated working fluid; the outer heating sleeve and the inner heating sleeve The interlayer, and the flow heat supply for the heating medium in the central heating tube; the heating medium outlet is arranged on the outer heating sleeve.

Preferably, several flaps are arranged on the outer wall of the casing of the central heating tube in the axial direction.

Preferably, the casing of the central heating pipe is arranged as a spiral coil.

Preferably, the outer heating sleeve, the inner heating sleeve and the central heating tube are coaxially arranged sequentially from outside to inside.

Preferably, the axial directions of the heating medium inlet and the heating medium outlet are located on the same cross section of the outer heating sleeve.

Further, the heating fluid inlet and the heating fluid outlet are arranged close to the heated working fluid inlet.

Preferably, the two ends of the inner heating sleeve are respectively provided with flanges connected to the system pipeline.

Compared with the prior art, the present invention has the following beneficial technical effects:

In the heat exchanger of the present invention, the heating medium first enters the central heating tube, and the heating medium coming out of the central heating tube enters the interlayer, and the heating medium that completes the heat exchange leaves the heat exchanger and enters the heating tube bundle of the hydrolysis reactor for hydrolysis. The reaction provides heat. The hydrolysis reaction product gas flows through the middle layer of the triple casing heater, and under the heat exchange effect of the central heating tube and the inner heating casing, the temperature is raised within a short distance, making full use of the heat of the heating medium ; Not only is the structure simple, easy to use, but also occupies a small space and is easy to process and maintain.

Further, by adopting warp fins or spiral coils, the heat exchange area at high temperature can be increased, and the heat exchange efficiency can be improved.

Further, through the coaxial arrangement, it can ensure the uniform heat exchange, and the balance and unity of the pressure of each working medium at different positions; while improving the heat exchange efficiency, the safety and stability of use are guaranteed.

Further, the heat exchange process of the heating medium can be extended by setting the inlet and outlet of the heating medium on the same side, which improves the space utilization efficiency; at the same time, it is arranged close to the inlet of the heated working medium to enhance the exchange temperature difference, which better meets the requirements of heat exchange. efficiency.

Description of drawings

Fig. 1 is a schematic diagram of the structure described in the examples of the present invention.

Fig. 2 is a schematic diagram of the structure provided with warping pieces described in the examples of the present invention.

Fig. 3 is a cross-sectional view at A_A in Fig. 2 .

In the figure: an outer heating sleeve 1, an inner heating sleeve 2, a central heating tube 3, a heating medium inlet 4, a heating medium outlet 5, a warp 6, and a flange 7.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments, which are explanations of the present invention rather than limitations.

A kind of urea solution hydrolysis ammonia production reactor outlet heat exchanger of the present invention, as shown in Figure 1, comprises outer heating sleeve 1, inner heating sleeve 2 and center heating pipe 3 that are sheathed sequentially from outside to inside; One end of 3 communicates with the interlayer between the outer heating sleeve 1 and the inner heating sleeve 2, and the other end extends radially to the outside of the outer heating sleeve 1 to set a heating medium inlet 4; the inside of the inner heating sleeve 2 is used to be heated Flow heating of the heating medium; the interlayer between the outer heating sleeve 1 and the inner heating sleeve 2, and the central heating tube 3 are used for the flowing heating of the heating medium; the outer heating sleeve 1 is provided with a heating medium exit 5.

In this preferred example, as shown in FIG. 2 , several warping pieces 6 are arranged axially on the outer wall of the central heating tube sleeve 3 to increase the heat exchange area; or the central heating tube sleeve 3 is arranged in a spiral coil. Wherein, the outer heating sleeve 1 , the inner heating sleeve 2 and the central heating tube 3 are coaxially arranged sequentially from outside to inside. And in this preferred example, the axial direction of the heating medium inlet 4 and the heating medium outlet 5 is located on the same cross section of the outer heating sleeve 1; and the heating medium inlet 4 and the heating medium outlet 5 are close to the heated working medium The inlet setting improves the distance and effect of heat exchange. The flanges 7 provided at both ends of the inner heating sleeve 2 are connected to the system pipeline.

The heater described in the present invention is connected with the system pipeline through the flange 7 . This preferred example is described by taking heating steam as the heating working medium as an example. As shown in Figure 1, when working, the heating steam first enters the central heating tube 3 from the heating medium inlet 4, and the steam from the central heating tube 3 enters the jacket between the outer heating sleeve 1 and the inner heating sleeve 2 Inside, the steam that has completed the heat exchange leaves the heat exchanger through the heating steam outlet 5 and enters the heating tube bundle of the hydrolysis reactor to provide heat for the hydrolysis reaction.

The heated working medium is illustrated by taking the hydrolysis reaction product gas as an example in this preferred example, which flows through the inner layer heating sleeve 2, that is, flows through the middle layer between the inner layer heating sleeve 2 and the central heating tube 3, Under the action of heat exchange between the central heating tube 3 and the internal heating tube 2, the temperature is raised within a short distance, and the product gas flows out from the outlet of the heated working medium.

During the whole process, the heating medium fully circulates and releases heat in a limited space, and forms a heat exchange structure with central heating and outer heat preservation, not only uniform and stable heat exchange, but also fast exchange speed, temperature supply and adjustment balance ; It satisfies the requirements of the product gas on the heat exchanger very well.

Claims (7)

1. a urea liquid hydrolysis ammonia reactor outlet processed heat exchanger, is characterized in that, comprise the external heat sleeve pipe (1) that ecto-entad is sheathed successively, interior heating muff (2) and central heating tube (3); One end of central heating tube (3) is communicated with the interlayer between external heat sleeve pipe (1) and interior heating muff (2), and the other end radially extends to external heat sleeve pipe (1) outer setting heating working medium entrance (4); For being heated by the flowing of heating working medium in interior heating muff (2); Interlayer between external heat sleeve pipe (1) and interior heating muff (2), and for the flowing heat supply of heating working medium in central heating tube (3); External heat sleeve pipe (1) is provided with heating working medium outlet (5).

2. a kind of urea liquid hydrolysis according to claim 1 ammonia reactor outlet processed heat exchanger, is characterized in that, the outer wall of described central heating tube sleeve pipe (3) arranges some fins (6) vertically.

3. a kind of urea liquid hydrolysis according to claim 1 ammonia reactor outlet processed heat exchanger, it is characterized in that, described central heating tube sleeve pipe (3) helically coil pipe is arranged.

4. a kind of urea liquid hydrolysis according to claim 1 ammonia reactor outlet processed heat exchanger, it is characterized in that, the external heat sleeve pipe (1) that ecto-entad is sheathed successively, interior heating muff (2) and central heating tube (3) are in coaxially arranged.

5. a kind of urea liquid hydrolysis according to claim 1 ammonia reactor outlet processed heat exchanger, it is characterized in that, the axis of heating working medium entrance (4) and heating working medium outlet (5) is positioned on the same cross section of external heat sleeve pipe (1).

6. a kind of urea liquid hydrolysis according to claim 5 ammonia reactor outlet processed heat exchanger, it is characterized in that, heating working medium entrance (4) and heating working medium outlet (5) are near being arranged by heating working medium entrance.

7. a kind of urea liquid hydrolysis according to claim 1 ammonia reactor outlet processed heat exchanger, it is characterized in that, interior heating muff (2) two ends are respectively arranged with the flange (7) be connected with system pipeline.