阅读说明：本技术 一种尿素催化水解制氨设备及其制备方法 (Urea catalytic hydrolysis ammonia production equipment and preparation method thereof ) 是由 西孟颖 杨建明 于 2019-11-20 设计创作，主要内容包括：一种尿素催化水解制氨设备及其制备方法,该设备包括原料溶解罐、原料储存罐、原料溶解泵、原料输送泵、反应器、盘管式换热器、产品气罩筒、产品气分离挡板、喷淋器及汽水分离器等。所述产品气罩筒设置在U型盘管式换热器的外周,形成套筒式结构；所述产品气分离挡板设置在产品气罩筒的正上方。该喷淋器设置在产品气分离挡板的上方,且位于产品气罩筒与反应器内壁面之间的空间内。由于本发明设置了产品气罩筒、产品气分离挡板以及汽水分离器,同时采用均相催化剂、原料喷淋以及间接加热相结合的工艺方法,有效增强了反应器内的料液扰动,使传热、传质能力显著增强,具有反应速度快,原料转化率高等优点,从而进一步降低能耗,提高了设备的利用率高。(The equipment comprises a raw material dissolving tank, a raw material storage tank, a raw material dissolving pump, a raw material delivery pump, a reactor, a coil type heat exchanger, a product gas hood cylinder, a product gas separation baffle, a sprayer, a steam-water separator and the like. The product gas hood cylinder is arranged on the periphery of the U-shaped coil type heat exchanger to form a sleeve type structure; the product gas separation baffle is arranged right above the product gas hood cylinder. The sprayer is arranged above the product gas separation baffle and is positioned in a space between the product gas hood cylinder and the inner wall surface of the reactor. Because the invention is provided with the product gas hood cylinder, the product gas separation baffle and the steam-water separator, and simultaneously adopts the process method of combining homogeneous phase catalyst, raw material spraying and indirect heating, the invention effectively enhances the disturbance of the material liquid in the reactor, obviously enhances the heat transfer and mass transfer capability, and has the advantages of high reaction speed, high raw material conversion rate and the like, thereby further reducing the energy consumption and improving the utilization rate of the equipment.)

1. A urea catalytic hydrolysis ammonia production device comprises a raw material dissolving tank (1), a raw material storage tank (3), a raw material dissolving pump (4), a raw material delivery pump (5), a reactor (11), a drain tank (2) and a temperature and pressure reducing device (6); a U-shaped coil heat exchanger (8) is arranged in the reactor, a steam outlet pipeline in the U-shaped coil heat exchanger (8) is divided into two paths, one path enters the coil heat exchanger in the raw material storage tank (3), and the outlet of the heat exchanger is connected with the drain tank (2); the other path is connected with a steam inlet at the bottom of the raw material dissolving tank (1); the method is characterized in that: the apparatus further comprises a product gas hood (9) and a product gas separation baffle (12) mounted inside the reactor; the product gas hood cylinder (9) is arranged on the periphery of the U-shaped coil type heat exchanger (8) to form a sleeve type structure; the product gas separation baffle (12) is arranged right above the product gas hood cylinder (9).

2. The apparatus for producing ammonia by catalytic hydrolysis of urea according to claim 1, wherein: the height of the product gas hood cylinder (9) is the same as that of the U-shaped coil type heat exchanger (8); the sectional area of the product gas separation baffle (12) is the same as that of the product gas hood cylinder.

3. The apparatus for producing ammonia by catalytic hydrolysis of urea according to claim 1, wherein: the apparatus comprises a shower (7); the sprayer (7) is arranged above the product gas separation baffle and is positioned in a space between the product gas hood cylinder and the inner wall surface of the reactor; the outlet of the raw material storage tank (3) is communicated with the inlet of the sprayer (7) through a pipeline and a raw material delivery pump (5).

4. A plant for the production of ammonia by the catalytic hydrolysis of urea according to claim 1, 2 or 3, characterized in that: a steam-water separator (10) is arranged at the top outlet of the reactor.

5. A method for producing ammonia by catalytic hydrolysis of urea by using the apparatus as claimed in any one of claims 1 to 4, characterized in that the method comprises the steps of:

1) filling an acidic liquid catalyst taking phosphate as a carrier in a reactor, conveying urea liquid with the mass percentage of 30-70% and the temperature of 40-80 ℃ into a urea storage tank (3) by a raw material dissolving pump (4), and spraying the urea liquid into a space between a product gas hood cylinder (9) and the inner wall of the reactor by a raw material conveying pump (5) through a sprayer (7);

2) reducing the temperature and the pressure of steam with the pressure of 0.6-0.8 MPa and the temperature of 160-180 ℃, then sending the steam into a reactor (11) to heat the urea solution, and carrying out catalytic hydrolysis reaction, wherein the reaction pressure is 0.35-0.55 Mpa, and the reaction temperature is 130-145 ℃;

3) after the reaction, product gas containing mixed ammonia gas and carbon dioxide is generated, the product gas is subjected to first gas-liquid separation through a product gas separation baffle (12), and the separated product gas flows out from an outlet at the top of the reactor through a steam-water separator (10);

4) hot liquid drops separated by the product gas separation baffle (12) are mixed with cold urea liquid sprayed by a sprayer to form an interference type catalytic hydrolysis reaction in the reactor, and the reaction is repeatedly circulated;

5) the heated waste heat steam is divided into two paths from the reactor: one path enters a raw material storage tank (3) to carry out indirect heat exchange on the urea liquid, the temperature of the urea liquid is kept between 40 ℃ and 80 ℃, the other path enters a raw material dissolving tank (1) to dissolve urea, and the temperature in the tank is kept between 40 ℃ and 80 ℃.

6. The method for producing ammonia by catalytic hydrolysis of urea as claimed in claim 5, wherein: the acid catalyst is a mixture of ammonium dihydrogen phosphate and diammonium hydrogen phosphate, and the loading amount of the acid catalyst is 5%/m ³～15％/m ³。

7. The method for producing ammonia by catalytic hydrolysis of urea as claimed in claim 5, wherein: in the step 5), the residual heat steam entering the raw material storage tank (3) accounts for 30-50% of the total heat of the residual heat steam, and the residual heat steam entering the urea dissolving tank (1) accounts for 50-70% of the total heat of the steam.

Technical Field

The invention relates to a process method and equipment for preparing ammonia by utilizing urea, in particular to a method and equipment for preparing ammonia by catalyzing and hydrolyzing urea, belonging to the technical field of chemical material preparation.

Background

The urea hydrolysis reactor is the core equipment of the project of changing liquid ammonia into urea for flue gas denitration in a thermal power plant, and the performance of the urea hydrolysis reactor determines the control quality, energy consumption and operation reliability of a denitration system after modification. The current commercially applied ammonia preparation method by flue gas denitration and hydrolysis mainly comprises the common urea hydrolysis method and the urea catalytic hydrolysis ammonia preparation method, and the common hydrolysis technology has the defects of low reaction speed, long response time, large volume (original belt buffer tank), serious corrosion and the like. The existing urea catalytic hydrolysis is concerned by adding a catalyst on the basis of the common hydrolysis technology, so that the reaction speed can be greatly improved, the corrosion can be reduced, the volume can be reduced, the energy consumption can be reduced, and the urea utilization rate can be improved. Most of domestic manufacturers adopt a urea catalytic hydrolysis technology, but the urea catalytic hydrolysis method adopts a liquid-phase full-mixing reaction, only utilizes a simple coil heat exchanger to exchange heat through a coil, belongs to a static mixing reaction, cannot fully exchange heat and utilize energy to the maximum extent, so that the investment and energy consumption are high, and the urea catalytic hydrolysis technology needs to be further technically improved.

Disclosure of Invention

Aiming at the defects and defects of the prior art, the invention aims to provide novel urea catalytic hydrolysis ammonia production equipment and a preparation method thereof, so that the energy consumption is further reduced, the energy is saved, the reaction speed is accelerated, and the utilization rate of the equipment is improved.

The technical scheme of the invention is as follows:

a urea catalytic hydrolysis ammonia production device comprises a raw material dissolving tank, a raw material storage tank, a raw material dissolving pump, a raw material delivery pump, a reactor, a drain tank and a temperature and pressure reducing device; a U-shaped coil heat exchanger is arranged in the reactor, a steam outlet pipeline in the U-shaped coil heat exchanger is divided into two paths, one path enters the coil heat exchanger in the raw material storage tank, and the outlet of the heat exchanger is connected with a drain tank; the other path is connected with a steam inlet at the bottom of the raw material dissolving tank; the method is characterized in that: the apparatus also includes a product gas hood and a product gas separation baffle mounted inside the reactor; the product gas hood cylinder is arranged on the periphery of the U-shaped coil type heat exchanger to form a sleeve type structure; the product gas separation baffle is arranged right above the product gas hood cylinder.

Among the above-mentioned technical scheme, its characterized in that: the height of the product gas hood cylinder is as high as that of the U-shaped coil type heat exchanger; the sectional area of the product gas separation baffle is the same as that of the product gas hood cylinder.

The device of the invention is also characterized in that: the equipment comprises a sprayer which is arranged above the product gas separation baffle and is positioned in a space between the product gas hood cylinder and the inner wall surface of the reactor; the outlet of the raw material storage tank is communicated with the inlet of the sprayer through a pipeline and a raw material delivery pump.

The device of the invention is also characterized in that: a steam-water separator is arranged at the top outlet of the reactor.

The invention provides a method for preparing ammonia by catalytic hydrolysis of urea, which is characterized by comprising the following steps:

1) filling an acidic liquid catalyst taking phosphate as a carrier in a reactor, conveying urea liquid with the mass percentage of 30-70% and the temperature of 40-80 ℃ into a urea storage tank by a raw material dissolving pump, and spraying the urea liquid into a space between a product gas hood cylinder and the inner wall of the reactor by a raw material conveying pump through a sprayer;

2) reducing the temperature and the pressure of steam with the pressure of 0.6-0.8 MPa and the temperature of 160-180 ℃, then sending the steam into a reactor to heat urea liquid, and carrying out catalytic hydrolysis reaction, wherein the reaction pressure is 0.35-0.55 MPa and the reaction temperature is 130-145 ℃;

3) generating a product gas containing ammonia gas and carbon dioxide mixture after the reaction, carrying out first gas-liquid separation on the product gas through a product gas separation baffle, and enabling the separated product gas to flow out of an outlet at the top of the reactor through a steam-water separator;

4) hot liquid drops separated by the product gas separation baffle are mixed with cold urea liquid sprayed by a sprayer, and an interference type catalytic hydrolysis reaction is formed in the reactor, so that the repeated circulation is realized;

5) the heated waste heat steam is divided into two paths from the reactor: one path enters a raw material storage tank to carry out indirect heat exchange on the urea liquid, the temperature of the urea liquid is kept between 40 ℃ and 80 ℃, the other path enters a raw material dissolving tank to dissolve urea, and the temperature in the tank is kept between 40 ℃ and 80 ℃.

In the method of the present invention, the characteristics thereofThe method comprises the following steps: the acid catalyst is a mixture of ammonium dihydrogen phosphate and diammonium hydrogen phosphate, and the loading amount of the acid catalyst is 5%/m ³～15％/m ³。

The method of the invention is characterized by comprising the following steps: in the step 5), the residual heat steam entering the raw material storage tank accounts for 30-50% of the total heat of the residual heat steam, and the residual heat steam entering the urea dissolving tank accounts for 50-70% of the total heat of the steam.

① the invention adopts the U-shaped coil heat exchanger and arranges the product gas hood cylinder around, the height of the product gas hood cylinder is the same as the height of the U-shaped coil heat exchanger, the temperature around the U-shaped coil heat exchanger is high, the catalyst gathers around the heat exchanger, there reacts with urea rapidly to produce ammonia gas and carbon dioxide of product gas, the product gas diffuses outwards, the temperature outside the product gas hood cylinder is low, the hot fluid flows upwards, the cold fluid flows downwards, increase the disturbance of solution, help the reaction go on faster, ② set up the product gas separation baffle on the said U-shaped coil heat exchanger and upper portion of the product gas hood cylinder, this filter baffle is right above the heat exchanger, its sectional area is the same as the sectional area of the product gas hood cylinder, the product gas produced is mixed with the liquid substance and risen through the baffle and can filter some liquid substance, carry on gas-liquid separation, ③ set up the shower above the middle of product gas and reactor, this shower position is higher than the product gas separation baffle, the urea solution passes the shower to the product gas after dropping, in this part of gas separator, receive the heat in this urea solution, the course of reaction.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of a novel ammonia production plant by catalytic hydrolysis of urea provided by the invention.

In the figure: 1-raw material dissolving tank; 2-a drain tank; 3-a raw material storage tank; 4-raw material dissolving pump; 5-a raw material delivery pump; 6-temperature and pressure reduction device; 7-a sprayer; 8-U-shaped coil type heat exchanger; 9-product gas hood cylinder; 10-steam-water separator; 11-a reactor; 12-product gas separation baffle.

Detailed Description

The structure, principle and operation of the invention will be further described with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of the structural principle of an embodiment of a novel urea catalytic hydrolysis ammonia production device provided by the invention, and the device comprises a raw material dissolving tank 1, a drain tank 2, a raw material storage tank 3, a raw material dissolving pump 4, a raw material delivery pump 5, a reactor 11, a temperature and pressure reducing device 6, a sprayer 7, a U-shaped coil heat exchanger 8, a product gas hood cylinder 9, a product gas separation baffle 12, a steam-water separator 10, and corresponding pipelines and valves; the product gas hood cylinder 9 is connected with the reactor 11 in a welding mode; the product gas separation baffle 12 is fixed on the inner wall surface of the reactor; the product gas hood cylinder 9 is arranged on the periphery of the U-shaped coil type heat exchanger 8 to form a sleeve type structure; the product gas separation baffle 12 is arranged directly above the product gas hood canister 9. Preferably, the height of the product gas hood cylinder 9 is the same as that of the U-shaped coil type heat exchanger 8; the sectional area of the product gas separation baffle 12 is the same as the sectional area of the product gas hood canister.

A product gas hood cylinder 9 is arranged at the periphery of the U-shaped coil type heat exchanger 8, and a product gas separation baffle plate 12 is arranged at the upper parts of the U-shaped coil type heat exchanger 8 and the product gas hood cylinder 9; because the temperature around the U-shaped coil heat exchanger 8 is high, the catalyst is gathered around the heat exchanger, and the catalyst and urea react rapidly at the heat exchanger to generate ammonia gas and carbon dioxide; the product gas diffuses outwards, the external temperature of the product gas hood cylinder is low, and cold and hot fluids are mixed, so that the disturbance of feed liquid can be increased, and the reaction can be carried out more quickly. The product gas generated at the moment is mixed with liquid substances, and the liquid substances can be partially filtered out by the separation baffle plate when rising, so that the gas and the liquid are separated at one time.

The sprayer 7 is arranged above the product gas separation baffle 12 and is positioned in a space between the product gas hood cylinder and the inner wall surface of the reactor; the outlet of the raw material storage tank 3 is communicated with the inlet of the sprayer 7 through a pipeline and a raw material delivery pump 5. The position of the sprayer 7 is higher than the product gas separation baffle 12, the urea solution drops to the bottom of the reactor through the product gas after being sprayed out from the sprayer, and the urea solution receives a part of heat in the process, so that the heating time is shortened, and the reaction is accelerated.

The steam-water separator 10 is fixed at the outlet of the reactor, and aims to perform secondary gas-liquid separation on product gas. The steam-water separator 10 may be a corrugated steam-water separator.

A steam outlet pipeline in the U-shaped coil type heat exchanger 8 is divided into two paths, one path enters the coil type heat exchanger in the raw material storage tank 3, and the outlet of the heat exchanger is connected with the drain tank 2; the other path is connected with a steam inlet at the bottom of the raw material dissolving tank 1.

The process of the invention comprises the following steps:

1) the reactor is filled with an acidic liquid catalyst taking phosphate as a carrier, and the filling amount is 5%/m ³～15％/m ³(ii) a Urea is filled into a dissolving tank 1, dissolved by desalted water and heated and dissolved by steam; the urea solution is delivered into a urea storage tank 3 by a raw material dissolving pump 4 and then sprayed into a reactor 11 by a delivery pump 5 through a sprayer 7, wherein the feeding mass percentage of the urea solution is 30-70%, and the temperature is 40-80 ℃;

2) reducing the temperature and the pressure of steam with the pressure of 0.6-0.8 MPa and the temperature of 160-180 ℃ through a temperature and pressure reducer (6), then entering a U-shaped coil type heat exchanger 8, and indirectly heating urea liquid in a reactor, wherein the pressure in the reactor is 0.35-0.55 MPa, and the reaction temperature is 130-145 ℃;

3) the heated waste heat steam is divided into two paths from the reactor: one path enters a raw material storage tank 3 for indirect heat exchange, the temperature of the heat-preservation urea solution is between 40 and 80 ℃, the other path is connected with a steam inlet at the bottom of a raw material dissolving tank 1 for dissolving urea, and the temperature is between 40 and 80 ℃; an outlet of the coil type heat exchanger in the raw material storage tank 3 is connected with the drain tank 2, and the drain is recovered;

4) the catalytic hydrolysis reaction is carried out in the reactor 11, the catalyst reacts with the urea solution near the pipe wall of the U-shaped coil heat exchanger 8, the product gas ammonia and carbon dioxide generated after the reaction diffuse outwards, the cold fluid sprayed by the sprayer 7 enters the product gas hood cylinder 9, the hot fluid flows upwards, the cold fluid flows downwards, the solution disturbance is increased, and the reaction can be carried out more quickly.

5) Liquid drops carried by the product gas pass through the product gas separation baffle 12 to carry out primary gas-liquid separation under the action of gravity, and when the liquid drops pass through the steam-water separator 10 at the outlet of the reactor, secondary gas-liquid separation is carried out, and the product gas flows out from the outlet of the reactor after the secondary separation.

The following examples are given to further illustrate the invention;

table 1: structural parameters

Table 2: reaction process parameters

Continue to watch