Ammonia recovery system for preparing cyclic carbonate by urea method
By separating and liquefying ammonia in the process of preparing cyclic carbonates using a multi-stage drying system, the problem of blockage caused by ammonia impurities was solved, and the production and low-cost recovery of high-purity liquid ammonia were achieved.
Patent Information
- Application Number
- CN202422899260.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-26
- Publication Date
- 2025-11-11
- Estimated Expiration
- 2034-11-26
AI Technical Summary
In the existing technology, during the preparation of cyclic carbonates using the urea method, the by-product ammonia gas contains impurities such as moisture, which cannot be directly compressed into high-purity liquid ammonia by a compressor, easily leading to blockage formation.
A multi-stage drying system is adopted, including a main dryer and a secondary dryer, combined with a vacuum pump and a compressor. The drying system separates and liquefies ammonia gas to produce liquid ammonia products with a purity of over 99%, avoiding the reaction of ammonia gas with carbon dioxide to form ammonium carbonate.
This technology enables the production of high-purity liquid ammonia, avoids the problem of ammonium carbonate blockage, reduces production costs, and improves the ammonia separation and recovery efficiency.
Smart Images
Figure CN223530191U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of carbonate production technology, and more specifically, to an ammonia recovery system for the preparation of cyclic carbonates using the urea method. Background Technology
[0002] The preparation of cyclic carbonates using the urea method refers to the production process of synthesizing propylene carbonate through a two-step reaction using urea and propylene glycol (or ethylene glycol) as raw materials. This method can not only solve the current problem of severe overcapacity of urea, but also is not limited by region. It can solve the situation in the central and western regions where the traditional method of using propylene oxide (ethylene oxide) is limited by the material transportation distance.
[0003] In actual production, after the raw materials react in the reactor, the gaseous products are usually extracted using a vacuum pump. However, because the products contain substances such as ammonia, carbon dioxide, and water, direct compression cannot produce high-purity liquid ammonia. Therefore, how to effectively avoid the formation of blockages and produce high-purity liquid ammonia has become an urgent problem to be solved. Utility Model Content
[0004] The purpose of this invention is to solve the problem that in the existing industrial urea process for preparing cyclic carbonates, the byproduct ammonia gas contains impurities such as moisture, making it impossible to directly compress it into liquid ammonia using a compressor. This application provides an ammonia recovery system for the urea process of preparing cyclic carbonates. This system has a simple structure, low production or modification costs, and can directly compress ammonia to obtain a liquid ammonia product with a purity of over 99%.
[0005] This utility model is achieved through the following technical solution:
[0006] This invention provides an ammonia recovery system for the preparation of cyclic carbonates using the urea method. Along the material conveying direction, it includes a vacuum pump, a drying system, a compressor, and a liquid ammonia tank connected in sequence. The drying system includes a multi-stage drying mechanism, with the feed end of each stage of the drying mechanism connected to the discharge end of the vacuum pump, and the discharge end of each stage of the drying mechanism connected to the feed end of the compressor.
[0007] Preferably, the multi-stage drying mechanism includes a main dryer and a secondary dryer, and both the main dryer and the secondary dryer are connected to the discharge end of the vacuum pump and the feed end of the compressor respectively via pipes.
[0008] Preferably, the feed end of the main dryer is equipped with a main pipe, which is connected to the discharge end of the vacuum pump, and the main pipe is equipped with a switch valve.
[0009] Preferably, the discharge end of the main dryer is equipped with a main feed pipe, which is connected to the feed end of the compressor, and the main feed pipe is equipped with a main flow meter.
[0010] Preferably, the feed end of the secondary dryer is provided with a secondary pipe, which is connected to the discharge end of the vacuum pump; the discharge end of the secondary dryer is provided with a secondary feed pipe, which is connected to the feed end of the compressor.
[0011] Preferably, the secondary pipeline is equipped with a control valve and a secondary flow meter.
[0012] Preferably, the main dryer is equipped with a drain pipe at its discharge end, and the secondary dryer is equipped with a liquid drain pipe at its discharge end, with the discharge end of the liquid drain pipe connected to the drain pipe.
[0013] The technical solution of this utility model has the following beneficial effects:
[0014] This invention relates to an ammonia recovery system for the preparation of cyclic carbonates using the urea method. The system is simple in structure, has low production or modification costs, and can separate and liquefy recover ammonia from the gaseous products after the reaction. The ammonia can be directly compressed into liquid ammonia with a purity of over 99%, thus avoiding the reaction of the generated ammonia with carbon dioxide to produce ammonium carbonate, thereby preventing the potential blockage of pipes or equipment by ammonium carbonate. Furthermore, each stage of the drying process is equipped with a drainage pipe to recover water and other materials after drying. The process is simple, has low production costs, and provides excellent ammonia separation and recovery. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the ammonia recovery system for the urea method in Example 1 for preparing cyclic carbonates.
[0016] Attached reference numerals: 1-vacuum pump, 21-main dryer, 211-main pipeline, 212-switch valve, 213-main feed pipe, 214-main flow meter, 215-drain pipe, 22-secondary dryer, 221-secondary pipeline, 222-secondary feed pipe, 223-control valve, 224-secondary flow meter, 225-drain pipe, 3-compressor, 4-liquid ammonia tank. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below. Where specific conditions are not specified in the embodiments, they are performed according to conventional conditions or conditions recommended by the manufacturer; where the manufacturers of instruments, equipment, reagents, or raw materials are not specified, they are all conventional products that can be purchased commercially. The following are specific embodiments in conjunction with the accompanying drawings.
[0018] like Figure 1As shown, this embodiment provides an ammonia recovery system for the preparation of cyclic carbonates using the urea method. Along the material conveying direction, it includes a vacuum pump 1, a drying system, a compressor 3, and a liquid ammonia tank 4 connected in sequence. The drying system includes a two-stage drying mechanism, and the feed ends of both stages are connected to the discharge ends of the vacuum pump 1, and the discharge ends of both stages are connected to the feed ends of the compressor 3.
[0019] Specifically, the two-stage drying mechanism includes a main dryer 21 and a secondary dryer 22, both of which are connected to the discharge end of the vacuum pump 1 and the feed end of the compressor 3 via pipelines. The main dryer 21 is used for routine operation, while the secondary dryer 22 can be used as a backup drying mechanism, and the operation of the main dryer 21 and the secondary dryer 22 can be controlled by valves and other components.
[0020] In this embodiment, the main dryer 21 has a main pipe 211 at its feed end, which is connected to the discharge end of the vacuum pump 1, and is equipped with a switching valve 212; the main dryer 21 has a main feed pipe 213 at its discharge end, which is connected to the feed end of the compressor 3, and is equipped with a main flow meter 214. The secondary dryer 22 has a secondary pipe 221 at its feed end, which is connected to the discharge end of the vacuum pump 1; the secondary dryer 22 has a secondary feed pipe 222 at its discharge end, which is connected to the feed end of the compressor 3; the secondary pipe 221 is equipped with a regulating valve 223 and a secondary flow meter 224.
[0021] In this embodiment, the discharge end of the main dryer 21 is equipped with a drain pipe 215, and the discharge end of the secondary dryer 22 is equipped with a liquid drain pipe 225. The discharge end of the liquid drain pipe 225 is connected to the drain pipe 215 to recover water and other materials after drying.
[0022] The ammonia recovery system for preparing cyclic carbonates using the urea method in this embodiment has a simple structure and low production or modification costs. It can separate and liquefy recover ammonia from the gaseous products after the reaction, and directly produce liquid ammonia products with a purity of over 99% through compression, thus avoiding the reaction of the generated ammonia with carbon dioxide to produce ammonium carbonate, thereby fundamentally avoiding the problem of ammonium carbonate potentially clogging pipes or equipment. In addition, each stage of the drying mechanism is equipped with a drainage pipe, which can recover water and other materials after drying. The process is simple, the production cost is low, and the ammonia separation and recovery effect is good.
[0023] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. An ammonia recovery system for the preparation of cyclic carbonates using the urea process, characterized in that, Along the material conveying direction, it includes a vacuum pump (1), a drying system, a compressor (3) and a liquid ammonia tank (4) connected in sequence; The drying system includes a multi-stage drying mechanism. The feed end of each stage of the drying mechanism is connected to the discharge end of the vacuum pump (1), and the discharge end of each stage of the drying mechanism is connected to the feed end of the compressor (3).
2. The ammonia recovery system for the urea process of preparing cyclic carbonates according to claim 1, characterized in that, The multi-stage drying mechanism includes a main dryer (21) and a secondary dryer (22), and the main dryer (21) and the secondary dryer (22) are respectively connected to the discharge end of the vacuum pump (1) and the feed end of the compressor (3) through pipes.
3. The ammonia recovery system for the urea process of preparing cyclic carbonates according to claim 2, characterized in that, The feed end of the main dryer (21) is equipped with a main pipe (211), which is connected to the discharge end of the vacuum pump (1), and the main pipe (211) is equipped with a switch valve (212).
4. The ammonia recovery system for the urea process of preparing cyclic carbonates according to claim 3, characterized in that, The main dryer (21) is equipped with a main feed pipe (213) at the discharge end, which is connected to the feed end of the compressor (3), and the main feed pipe (213) is equipped with a main flow meter (214).
5. The ammonia recovery system for the preparation of cyclic carbonates using the urea method according to claim 2, characterized in that, The feed end of the secondary dryer (22) is equipped with a secondary pipe (221), which is connected to the discharge end of the vacuum pump (1); the discharge end of the secondary dryer (22) is equipped with a secondary feed pipe (222), which is connected to the feed end of the compressor (3).
6. The ammonia recovery system for the urea process of preparing cyclic carbonates according to claim 5, characterized in that, The secondary pipeline (221) is equipped with a control valve (223) and a secondary flow meter (224).
7. The ammonia recovery system for the preparation of cyclic carbonates using the urea process according to any one of claims 2 to 6, characterized in that, The main dryer (21) is equipped with a drain pipe (215) at the discharge end, and the secondary dryer (22) is equipped with a liquid drain pipe (225) at the discharge end, and the discharge end of the liquid drain pipe (225) is connected to the drain pipe (215).