Product ammonia removal device for preparing cyclic carbonate by urea method

Abstract

The utility model relates to the technical field of preparation of cyclic carbonate by a urea method, and aims to solve the problems that ammonia gas always exists in a reaction system and the purity of the product is finally influenced because the product obtained by the preparation of the cyclic carbonate by the existing urea method directly enters a rectifying tower to be separated and purified. The utility model provides a product ammonia removal device for preparing cyclic carbonate by a urea method. The product ammonia removal device comprises an ammonia removal tank, a gas inlet pipe and a gas suction pipe, the bottom of the ammonia removal tank is communicated with a nitrogen storage tank through the gas inlet pipe; the exhaust pipe is communicated with the top of the ammonia removal tank; the ammonia removal tank is communicated with the rectifying tower through the discharging pipe; the product ammonia removal device for preparing the cyclic carbonate by the urea method, provided by the utility model, is good in ammonia removal effect and high in efficiency, and can effectively avoid the influence of ammonia gas on the purity of the product.

Description

TECHNICAL FIELD

[0001] The utility model relates to urea preparation cyclic carbonate technology field, specifically, relate to a kind of urea preparation cyclic carbonate's product ammonia removal device. BACKGROUND

[0002] Urea preparation cyclic carbonate is an important chemical synthesis method, and its basic principle is that the adjacent two-NH - Group in urea and the hydroxyl of alcohol compound are combined to form intermediate product, and then through ring-closing reaction, cyclic carbonate is generated.

[0003] After urea and propylene glycol reaction end, product needs to be separated and purified, but there is still ammonia gas in reaction product system, and the prior art directly enters separation and purification stage, such as the urea alcoholysis method for producing organic carbonate disclosed in the publication No.CN101121659A, wherein the mixture of fatty alcohol steam, organic carbonate gas, ammonia gas and carbon dioxide gas generated by side reaction, which are collected from the top of fixed bed reactor, is introduced into the middle of deamination rectifying column for separation and purification;However, the product is directly introduced into rectifying column for separation and purification, so that ammonia gas exists in reaction system all the time, which finally affects product purity.

[0004] Based on the above description, there is an urgent need for a product ammonia removal device for urea preparation cyclic carbonate. UTILITY MODEL CONTENT

[0005] The utility model aims at providing a kind of urea preparation cyclic carbonate's product ammonia removal device, to solve the technical problem that the product obtained by the existing urea preparation cyclic carbonate is directly introduced into rectifying column for separation and purification, resulting in ammonia gas existing in reaction system all the time, and finally affecting product purity.

[0006] The embodiment of the utility model realizes by the following technical scheme:

[0007] A kind of urea preparation cyclic carbonate's product ammonia removal device, including ammonia removal tank, gas inlet pipe and suction pipe;The bottom of the ammonia removal tank is communicated with nitrogen gas storage tank by the gas inlet pipe;The suction pipe is communicated at the top of the ammonia removal tank;The ammonia removal tank is communicated with rectifying column by the discharge pipe.

[0008] As preferred, the end of the suction pipe away from the ammonia removal tank is communicated with ammonia dissolving system.

[0009] As preferred, the ammonia dissolving system includes absorption tower, liquid inlet pipe and exhaust pipe;The absorption tower is communicated with the suction pipe;The liquid inlet pipe is communicated with the absorption tower;The exhaust pipe is communicated at the top of the absorption tower.

[0010] As preferred, the ammonia dissolving system further comprises an outlet pipe; the outlet pipe is communicated with the bottom of the absorption tower.

[0011] As preferred, a circulation system is communicated between the outlet pipe and the inlet pipe.

[0012] As preferred, the circulation system comprises a circulation branch pipe and a circulation pump; the outlet pipe is in circulation communication with the inlet pipe through the circulation branch pipe; the circulation pump is arranged at a pipe section of the circulation branch pipe.

[0013] As preferred, a plurality of heat exchange tubes are arranged in the absorption tower; the heat exchange tubes are communicated with the cold gas inlet pipe.

[0014] The technical scheme of the embodiment of the utility model has at least the following advantages and beneficial effects:

[0015] The utility model discloses a product ammonia removing device for urea method preparation of cyclic carbonate, which is suitable for pre-removing ammonia of product distillation before urea method preparation of cyclic carbonate. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a system schematic view of the utility model.

[0017] Figure: 1-ammonia removing tank, 2-inlet pipe, 3-exhaust pipe, 4-nitrogen gas storage tank, 5-distillation tower, 6-ammonia dissolving system, 61-absorption tower, 62-inlet pipe, 63-exhaust pipe, 64-outlet pipe, 7-circulation system, 71-circulation branch pipe, 72-circulation pump, 8-cold gas inlet pipe. DETAILED DESCRIPTION

[0018] The specific embodiment is combined with the drawings.

[0019] Embodiment 1

[0020] Please refer to Figure 1 The utility model provides the following technical scheme: a product ammonia removing device for urea method preparation of cyclic carbonate, which is suitable for pre-removing ammonia of product distillation before urea method preparation of cyclic carbonate.

[0021] Specifically, as Figure 1As shown, a product ammonia removal device for urea method preparation of cyclic carbonate includes an ammonia removal tank 1, a gas inlet pipe 2 and a gas outlet pipe 3; the bottom of the ammonia removal tank 1 is communicated with a nitrogen gas storage tank 4 through the gas inlet pipe 2; the gas outlet pipe 3 is communicated with the top of the ammonia removal tank 1; the ammonia removal tank 1 is communicated with a rectifying tower 5 through a discharge pipe.

[0022] In this embodiment, before the product is introduced into the rectifying tower for rectification, the product is first introduced into the ammonia removal tank 1 for ammonia removal, effectively avoiding the problem of low purity of the final product caused by the existence of ammonia in the subsequent production system; specifically, the gas outlet pipe 3 is connected to a vacuum pump to vacuumize the ammonia removal tank 1, and then the ammonia gas in the ammonia removal tank 1 is extracted; further, due to the large surface tension of the product, it is more difficult for gas molecules to form bubbles on the surface of the product and escape, thereby reducing the efficiency of ammonia extraction; therefore, by arranging the gas inlet pipe 2 at the bottom of the ammonia removal tank 1, the nitrogen gas is introduced at the bottom of the ammonia removal tank 1 to promote the escape of ammonia gas from the product, so as to be discharged through the gas outlet pipe 3.

[0023] Specifically, as shown in the figure, Figure 1 the end of the gas outlet pipe 3 away from the ammonia removal tank 1 is communicated with an ammonia dissolving system 6. The ammonia dissolving system 6 includes an absorption tower 61, a liquid inlet pipe 62 and a gas outlet pipe 63; the absorption tower 61 is communicated with the gas outlet pipe 3; the liquid inlet pipe 62 is communicated with the absorption tower 61; the gas outlet pipe 63 is communicated with the top of the absorption tower 61. The ammonia dissolving system 6 further includes a liquid outlet pipe 64; the liquid outlet pipe 64 is communicated with the bottom of the absorption tower 61.

[0024] In this embodiment, the liquid inlet pipe 62 is arranged at the top of the absorption tower 61, and the gas outlet pipe 3 is communicated with the bottom of the absorption tower 61, so that the extracted ammonia gas and nitrogen gas can contact for a longer time in the absorption tower 61, thereby improving the dissolution rate of ammonia gas and facilitating the separation of ammonia gas and nitrogen gas; after passing through the absorption tower 61, the nitrogen gas is discharged through the gas outlet pipe 63, and a vacuum pump can be further arranged to improve the discharge efficiency of the nitrogen gas; after dissolution, the ammonia water is discharged through the liquid outlet pipe 61 at the bottom of the absorption tower 61.

[0025] Specifically, as shown in the figure, Figure 1 the liquid outlet pipe 64 and the liquid inlet pipe 62 are communicated with a circulation system 7. The circulation system 7 includes a circulation branch pipe 71 and a circulation pump 72; the liquid outlet pipe 64 is circularly communicated with the liquid inlet pipe 62 through the circulation branch pipe 71; the circulation pump 72 is arranged in the pipe section of the circulation branch pipe 71.

[0026] In this embodiment, the ammonia water discharged from the liquid outlet pipe 64 is introduced again as a solvent into the absorption tower 61 from the top through the liquid inlet pipe 62 for ammonia dissolving again, thereby playing a role of concentrating the ammonia water for subsequent discharge and utilization.

[0027] Specifically, as shown in the figure, Figure 1 a plurality of heat exchange column pipes are arranged in the absorption tower 61; the heat exchange column pipes are communicated with a cold gas inlet pipe 82.

[0028] In this embodiment, the ammonia gas, nitrogen gas and solvent introduced through the liquid inlet pipe 62 all pass through the shell side of the absorption tower 61, and the heat exchange column pipes supply cold gas for heat exchange. The top and bottom of the absorption tower 61 can be internally provided with a buffer sealing cavity for the two ends of the heat exchange column pipes to pass through, and the cold gas inlet pipe 82 supplies cold gas to each heat exchange column pipe.

Claims

1. A product ammonia removal unit for the urea process for the production of cyclic carbonates, characterized by: The ammonia removal tank (1), the gas inlet pipe (2) and the gas outlet pipe (3); the bottom of the ammonia removal tank (1) is communicated with the nitrogen storage tank (4) through the gas inlet pipe (2); the gas outlet pipe (3) is communicated with the top of the ammonia removal tank (1); the ammonia removal tank (1) is communicated with the rectifying tower (5) through the discharge pipe.

2. A product ammonia removal unit for the urea process for the preparation of cyclic carbonates according to claim 1, characterized in that: The far end of the gas outlet pipe (3) from the ammonia removal tank (1) is communicated with the ammonia dissolving system (6).

3. A product ammonia removal unit for the urea process for the preparation of cyclic carbonates according to claim 2, characterized in that: The ammonia dissolving system (6) comprises the absorption tower (61), the liquid inlet pipe (62) and the exhaust pipe (63); the absorption tower (61) is communicated with the gas outlet pipe (3); the liquid inlet pipe (62) is communicated with the absorption tower (61); the exhaust pipe (63) is communicated with the top of the absorption tower (61).

4. A product ammonia removal unit for the urea process for the preparation of cyclic carbonates according to claim 3, characterized in that: The ammonia dissolving system (6) further comprises the liquid outlet pipe (64); the liquid outlet pipe (64) is communicated with the bottom of the absorption tower (61).

5. A product ammonia removal unit for the urea process for the preparation of cyclic carbonates according to claim 4, characterized in that: The circulation system (7) is communicated between the liquid outlet pipe (64) and the liquid inlet pipe (62).

6. A product ammonia removal unit for the urea process for the preparation of cyclic carbonates according to claim 5, characterized in that: The circulation system (7) comprises the circulation branch pipe (71) and the circulation pump (72); the liquid outlet pipe (64) is circulatedly communicated with the liquid inlet pipe (62) through the circulation branch pipe (71); the circulation pump (72) is arranged in the pipe section of the circulation branch pipe (71).

7. A product ammonia removal unit for the urea process for the preparation of cyclic carbonates according to any one of claims 3 to 6, characterized in that: A plurality of heat exchange pipes are arranged in the absorption tower (61); the heat exchange pipes are communicated with the cold gas inlet pipe (8).

Images