CN104096512B - A kind of hydrolysis of urea reactor outlet demister - Google Patents

Abstract

A urea hydrolysis reactor outlet defogging device of the present invention comprises a cylinder body, and a cyclone defogging section and a wire mesh demisting section arranged in series in the cylinder body and separated by an annular partition; the lower end of the cylinder body extends into the urea hydrolysis reactor The outlet is set, the upper end forms a gas phase outlet and is fixed with the outlet of the urea hydrolysis reactor; the outlet end of the wire mesh demisting section is connected to the gas phase outlet, and the inlet end is connected to the exhaust end of the cyclone demisting section; the air inlet of the cyclone demisting section is set On the side wall of the cylinder body, the liquid outlet at the lower end of the cyclone defogging section extends below the liquid level in the urea hydrolysis reactor. Demisting is carried out by using two-stage series devices. The first stage is cyclone demisting to separate large droplets, and the second stage is wire mesh demisting to separate small droplets; the airflow through the outlet of the cyclone demisting section enters the wire in the form of rotating flow. The mesh defogging section increases the length of the trajectory of the airflow in the wire mesh defogging section, improves the defogging effect of the wire mesh defogging section, obtains a better comprehensive defogging effect, and has a stronger defogging ability.

Description

A urea hydrolysis reactor outlet demisting device

technical field

The invention belongs to the technical field of flue gas denitrification, and relates to a demisting device at the outlet of a urea hydrolysis reactor.

Background technique

The preparation of ammonia by urea hydrolysis is a reducing agent preparation process in the SCR denitrification process of flue gas in thermal power plants. The principle is that the urea solution is hydrolyzed to generate ammonia and carbon dioxide under certain temperature and pressure in the hydrolysis reactor. The generated ammonia, carbon dioxide and part of the water vapor leave the hydrolysis reactor and are sent to the boiler flue for denitrification reaction. The internal space of the hydrolysis reactor is divided into the lower liquid phase space and the upper gas phase space. Due to the violent boiling of the liquid phase space, the vapor phase space is not only filled with reaction product ammonia, carbon dioxide and partially evaporated water vapor, but also contains a large amount of small liquid. drop. The composition of the small droplets is the same as that of the hydrolysis reaction liquid, and part of urea is dissolved. If the small droplets leave the hydrolysis reactor together with the hydrolyzate and enter the subsequent process flow, due to changes in the operating pressure and other factors of the subsequent process flow, the small droplets will vaporize, and the urea dissolved in the small droplets will crystallize out and block the pipeline. and equipment. It is therefore necessary to minimize the number of small droplets leaving the hydrolysis reactor.

At present, the commonly used technology in the industry is to install a wire mesh demister at the outlet of the hydrolysis reactor product, as shown in Figure 1. On the one hand, due to the large content of small droplets in the gas phase, it is limited by the demisting ability of the wire mesh eliminator itself. The defogging effect is not ideal, and the defogging effect cannot be improved. On the other hand, the current wire mesh demister adopts a built-in fixed structure, which is not easy to repair and replace after blockage occurs.

Contents of the invention

Aiming at the problems existing in the prior art, the present invention provides a demisting device at the outlet of a urea hydrolysis reactor with high working efficiency and convenient maintenance and replacement.

The present invention is realized through the following technical solutions:

A urea hydrolysis reactor outlet demisting device includes a cylinder body, and a cyclone defogging section and a wire mesh demisting section arranged in series in the cylinder body and separated by an annular partition; , the upper end forms a gas phase outlet and is fixed with the outlet of the urea hydrolysis reactor; the gas outlet of the wire mesh demisting section is connected to the gas phase outlet, and the air inlet is connected to the exhaust end of the cyclone demisting section; the air inlet of the cyclone demisting section is set in the cylinder On the side wall of the body, the liquid outlet at the lower end of the cyclone defogging section extends below the liquid level in the urea hydrolysis reactor.

Preferably, the lower end surface of the wire mesh defogging section is set as an inverted cone.

Further, a vortex stabilizing rod extending to the liquid discharge port is provided at the center of the lower part of the wire mesh defogging section.

Preferably, the air inlet is arranged symmetrically on the side wall of the cylinder corresponding to the cyclone defogging section, and the air inlet direction of the air inlet is tangent to the inner circle of the cylinder where it is located.

Further, guide vanes arranged in a spiral are arranged in the liquid discharge port, and the helical direction of the guide vanes is the same as that of the airflow in the cyclone defogging section.

Preferably, the upper end of the cylinder is hooked and fixed to the outlet of the urea hydrolysis reactor through the provided outlet flange.

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

The present invention adopts two-stage serial device for defogging, the first stage is cyclone demisting capable of separating large droplets in the airflow, and the second stage is wire mesh demisting for separating small droplets in the airflow; through the cyclone demisting section The outlet air flow enters the demister section of the wire mesh in the form of rotating flow, thereby increasing the length of the trajectory of the airflow in the demist section of the wire mesh, improving the demisting effect of the demist section of the wire mesh, and obtaining better comprehensive demisting Compared with the existing design, the overall demisting effect of the equipment is greatly improved, and the amount of liquid carried by the gas after passing through the demister is reduced by more than 50%; at the same time, the original built-in fixed wire mesh demister The structure is changed to a two-stage series-connected one-piece plug-in structure, which facilitates inspection and maintenance.

Further, the initial contact area between the wire mesh demister and the mist-containing air flow is increased by setting the inverted cone surface at the lower end of the wire mesh demisting section, and the decontamination ability of the wire mesh demisting section is improved. On the other hand, the liquid collected by the wire mesh demister is easy to accumulate in the lower part of the cone section and be discharged in time, which can better improve the decontamination ability of the wire mesh demister section.

Further, the vortex stabilization rod arranged at the lower end of the wire mesh demisting section can stabilize the vortex core of the rotating airflow, reduce the precession effect at the end of the vortex core, and improve the separation efficiency of the cyclone demisting section; on the other hand, the vortex stabilization rod can The collected liquid enriched in the lower part of the cone section of the wire mesh demister is diverted to the bottom of the demister and discharged, which also improves the separation efficiency of the wire mesh demister section.

Furthermore, the symmetrical arrangement of the air inlet allows the airflow to pass through the restriction of the air inlet when it enters, and can form a vortex in the cyclone defogging section by itself to improve the separation effect.

Further, the urea solution flowing into the hydrolysis reactor after being guided by the set guide vanes can reduce the disturbance of the collected liquid to the solution in the hydrolysis reactor, reduce splashing, and reduce the liquid content in the airflow.

Furthermore, the quick fit with the outlet of the reactor is realized through the flange provided at the upper end of the cylinder body, which improves the efficiency of inspection and replacement.

Description of drawings

Fig. 1 is a structural schematic diagram of a wire mesh demister at the outlet of a urea hydrolysis reactor in the prior art.

Fig. 2 is a diagram of the use state of the mist eliminator described in the example of this patent.

Fig. 3 is a structural schematic diagram of the mist eliminator described in the example of this patent.

Fig. 4 is a sectional view taken along line A-A of Fig. 3 .

In the figure: cyclone defogging section 1, wire mesh defogging section 2, air inlet 3, gas phase outlet 4, outlet flange 5, liquid outlet 6, guide vane 7, cylinder 10.

detailed description

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 hydrolysis reactor outlet demister device of the present invention, as shown in Figure 3, it comprises cylinder body 10, and the cyclone defogging section 1 that is arranged in series in cylinder body 10 and it is separated by annular partition 9 and silk screen Demisting section 2; the lower end of cylinder body 10 extends into the outlet of the urea hydrolysis reactor, and the upper end forms a gas phase outlet 4 and is fixed with the outlet of the urea hydrolysis reactor; the gas outlet of the wire mesh demisting section 2 communicates with the gas phase outlet 4, and The gas end is connected to the exhaust end of the cyclone defogging section 1; the air inlet 3 of the cyclone defogging section 1 is set on the side wall of the cylinder 10, and the liquid outlet 6 at the lower end of the cyclone defogging section 1 extends into the urea hydrolysis reactor Set below the inner liquid level. Wherein, as shown in FIG. 3 , the lower end surface of the wire mesh defogging section 2 is arranged as an inverted cone surface, and a vortex stabilizing rod 8 extending to the liquid discharge port 6 is arranged in the center of the lower part. As shown in Figure 3, the air inlet 3 is symmetrically arranged on the side wall of the cylinder 10 corresponding to the cyclone defogging section 1, as shown in Figure 4, the air intake direction of the air inlet 3 and the inner circle of the cylinder 10 Tangent. As shown in FIG. 3 and FIG. 4 , guide vanes 7 arranged in a spiral arrangement are arranged in the liquid discharge port 6 , and the helical direction of the guide vanes 7 is the same as that of the airflow in the cyclone defogging section 1 . As shown in FIG. 3 , the upper end of the cylinder body 10 is hooked and fixed to the outlet of the urea hydrolysis reactor through the outlet flange 5 provided.

When the present invention is used, as shown in Figure 2, the present invention is hooked and fixed with the outlet of the urea hydrolysis reactor through the outlet flange 5, and fixed by bolts; The mixed gas composed of vaporized water vapor carries small droplets from the air inlet 3 into the cyclone defogging section 1, and rotates in the cyclone defogging section 1. Throw it onto the wall of the cyclone demisting section 1, discharge it from the discharge port 6 under the action of gravity and downward airflow, and return to the urea hydrolysis reactor without splash under the action of the guide vane 7. The mixed gas and small particle droplets enter the wire mesh demisting section 2 through the cyclone demisting section 1, and the small droplets are separated in a spiral motion in the wire mesh demisting section 2, and the demisted mixed gas passes through the gas phase outlet 4 Leaving the hydrolysis reactor and entering the next process; the separated liquid droplets in the screen demisting section 2 are collected on the lower conical surface and guided and discharged by the vortex stabilization rod 8, which also stabilizes the vortex in the cylinder 10 The role of the center improves the overall separation effect; the overall demisting effect of the equipment is greatly improved compared with the original design, and the amount of liquid carried by the gas after passing through the demister is reduced by more than 50%.

The mode of implementation of the present invention is not limited thereto.

Claims (5)

1. a urea hydrolysis reactor outlet demisting device, is characterized in that, comprises cylinder (10), and is arranged in series successively in cylinder (10) its cyclone defogging section ( 1) and wire mesh defogging section (2); the lower end of the cylinder (10) extends into the outlet of the urea hydrolysis reactor, and the upper end forms the gas phase outlet (4) and is fixed with the outlet of the urea hydrolysis reactor; the wire The air outlet of the net defogging section (2) is connected to the gas phase outlet (4), and the air inlet is connected to the exhaust end of the cyclone demisting section (1); the air inlet (3) of the cyclone demisting section (1) It is arranged on the side wall of the cylinder (10), and the liquid outlet (6) at the lower end of the cyclone defogging section (1) is set below the liquid level in the urea hydrolysis reactor; the lower end surface of the wire mesh defogging section (2) Set in an inverted cone. 2. a kind of urea hydrolysis reactor outlet demisting device according to claim 1, is characterized in that, the bottom center of wire mesh demisting section (2) is provided with the stabilizing vortex rod ( 8). 3. The demisting device at the outlet of a urea hydrolysis reactor according to claim 1, characterized in that, the air inlet (3) is symmetrically arranged on the cylinder (10) corresponding to the cyclone demisting section (1) On the side wall of the air inlet (3), the air intake direction of the air inlet (3) is tangent to the inner circle of the cylinder (10) where it is located. 4. The demisting device at the outlet of a urea hydrolysis reactor according to claim 1 or 3, characterized in that, said drain port (6) is provided with guide vanes (7) in a spiral arrangement, The helical direction of the guide vanes (7) is the same as that of the airflow in the cyclone defogging section (1). 5. A kind of urea hydrolysis reactor outlet demister device according to claim 1, is characterized in that, described cylinder (10) upper end is articulated with urea hydrolysis reactor outlet through the outlet flange (5) that is provided with fixed.