CN113651727A - System and method for preparing dicyandiamide by mixing ammonia and carbon dioxide - Google Patents
System and method for preparing dicyandiamide by mixing ammonia and carbon dioxide Download PDFInfo
- Publication number
- CN113651727A CN113651727A CN202110912149.7A CN202110912149A CN113651727A CN 113651727 A CN113651727 A CN 113651727A CN 202110912149 A CN202110912149 A CN 202110912149A CN 113651727 A CN113651727 A CN 113651727A
- Authority
- CN
- China
- Prior art keywords
- gas
- dicyandiamide
- reactor
- carbon dioxide
- ammonia
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C277/00—Preparation of guanidine or its derivatives, i.e. compounds containing the group, the singly-bound nitrogen atoms not being part of nitro or nitroso groups
- C07C277/08—Preparation of guanidine or its derivatives, i.e. compounds containing the group, the singly-bound nitrogen atoms not being part of nitro or nitroso groups of substituted guanidines
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention relates to the technical field of dicyandiamide production, in particular to a system and a method for preparing dicyandiamide by mixing ammonia and carbon dioxide. The method comprises the following steps: the method comprises the steps of enabling gas from a trap to pass through a compressor and then react with preheated ammonia in a reactor to obtain cyanamide gas, filtering the cyanamide gas containing solid impurities through a filter-1, polymerizing in a polymerization reactor to obtain dicyandiamide gas, filtering the solid impurities contained in the dicyandiamide gas through a filter-2, cooling and crystallizing in a crystallizer using carbon dioxide as process cold air, collecting dicyandiamide solid in the trap, enabling part of the gas to enter the reactor through the compressor, and enabling part of the gas to be treated and reused as process tail gas. The dicyandiamide solid obtained by the method realizes simple process flow, environmental protection, high raw material utilization rate, byproduct steam, low energy consumption and cost saving on the basis of ensuring high product quality and purity.
Description
Technical Field
The invention relates to the technical field of dicyandiamide production, in particular to a system and a method for preparing dicyandiamide by mixing ammonia and carbon dioxide.
Background
Dicyandiamide, also known as dicyandiamide, dicyandiamide (a dimer of cyanamide, also a cyano derivative of guanidine), of the formula (NH)2CN)2. Dicyandiamide is generally a white crystal in the form of needles, diamonds, scales or powders, having a melting point of 205 ℃.
The existing dicyandiamide preparation method is to hydrolyze calcium cyanamide to obtain calcium cyanamide hydrogen suspension, remove calcium hydroxide filter residue through vacuum filtration, and introduce carbon dioxide into the filtrate to precipitate calcium in the form of calcium carbonate to obtain cyanamide liquid. Polymerizing under alkaline condition, filtering, cooling, crystallizing, separating and drying to obtain dicyandiamide. The equation is as follows:
2CaCN2+2H2O→Ca(HCN2)2+Ca(OH)2
Ca(HCN2)2+CO2+H2O→2NH2CN+CaCO3
2NH2CN→(NH2CN)2
the main factors influencing the quality index of dicyandiamide in the existing lime nitrogen process technology are calcium oxide, calcium hydroxide, calcium carbonate and other impurities contained in the product. The lime nitrogen method has long production process flow and high equipment cost, can generate a large amount of waste residues and waste water, causes serious environmental pollution and large cost, and simultaneously needs a large amount of cooling water to control temperature in the lime nitrogen hydrolysis decalcification process, and can cause great waste of energy consumption and water resources.
Disclosure of Invention
The invention aims to provide a method for preparing dicyandiamide by mixing ammonia and carbon dioxide, which utilizes dicyandiamide products prepared by the processes of mixing reaction, polymerization and the like of the ammonia and the carbon dioxide, so that the products do not contain any calcium and other impurities, and the quality influence factor of the calcium impurities on dicyandiamide in a lime nitrogen method can be solved.
It is a further object of the invention to provide a system for use in the above method.
In order to achieve the above purpose, the specific technical scheme of the invention is as follows:
a first method for preparing dicyandiamide by mixing ammonia and carbon dioxide comprises the following steps:
firstly, compressing and pressurizing gas from a trap by a compressor, then introducing the gas into a reactor, simultaneously preheating ammonia, then introducing the preheated ammonia into the reactor, and mixing and reacting the gas and the preheated ammonia in the reactor to obtain the cyanamide gas. The cyanamide gas enters a filter-1, solid impurities brought out are filtered, and then the filtered solid impurities are introduced into a polymerization reactor.
Introducing the cyanamide gas into the polymerization reactor, and polymerizing in the polymerization reactor to obtain the dicyandiamide gas. The dicyandiamide gas enters a filter-2, and solid impurities brought out are filtered and then sent into a crystallizer.
And thirdly, after the dicyandiamide gas enters a crystallizer and is mixed with carbon dioxide serving as process cold air for cooling and crystallization, the gas with the dicyandiamide crystals enters a trap for gas-solid separation, dicyandiamide solid is obtained by collection, a part of the gas enters a reactor through a compressor, and a part of the gas is used as process tail gas for treatment and reuse.
As a preferred embodiment herein, the temperature of the ammonia after preheating is in the range of 0 to 140 c, more preferably 25 to 80 c.
As a preferred embodiment of the present application, the temperature of the reactor for the mixed reaction of ammonia and carbon dioxide is controlled at 650-900 deg.C, more preferably at 720-800 deg.C.
As a preferred embodiment herein, the polymerization temperature in the polymerization reactor is 200-400 deg.C, more preferably 260-320 deg.C.
As a preferred embodiment of the present application, the process cold gas carbon dioxide temperature is in the range of 0-100 c, more preferably 25-60 c.
As a preferred embodiment of the present invention, the mass ratio of the introduced ammonia to the carbon dioxide is 1:1 to 1.8.
A second method for preparing dicyandiamide by mixing ammonia and carbon dioxide, which comprises the following steps:
firstly, compressing and pressurizing gas from a trap by a compressor, then introducing the gas into a reactor, simultaneously preheating carbon dioxide, then introducing the preheated carbon dioxide into the reactor, and mixing and reacting the preheated carbon dioxide and the preheated carbon dioxide in the reactor to obtain cyanamide gas. The cyanamide gas enters a filter-1, solid impurities brought out are filtered, and then the filtered solid impurities are introduced into a polymerization reactor.
Introducing the cyanamide gas into the polymerization reactor, and polymerizing in the polymerization reactor to obtain the dicyandiamide gas. The dicyandiamide gas enters a filter-2, and solid impurities brought out are filtered and then sent into a crystallizer.
And thirdly, after the dicyandiamide gas enters a crystallizer and is mixed with ammonia serving as process cold air to be cooled and crystallized, the gas with the dicyandiamide crystals enters a trap to complete gas-solid separation, dicyandiamide solid is obtained by collection, a part of the gas enters a reactor through a compressor, and a part of the gas is used as process tail gas for treatment and reuse.
As a preferred embodiment herein, the temperature of the carbon dioxide after preheating is 0 to 140 c, more preferably 25 to 80 c.
As a preferred embodiment of the present application, the temperature of the reactor for the mixed reaction of carbon dioxide and ammonia is controlled at 650-900 deg.C, more preferably at 720-800 deg.C.
As a preferred embodiment herein, the polymerization temperature in the polymerization reactor is 200-400 deg.C, more preferably 260-320 deg.C.
As a preferred embodiment of the present application, the process cold gas ammonia has a temperature of 0-100 c, more preferably 25-60 c.
As a preferred embodiment of the present invention, the mass ratio of carbon dioxide to ammonia to be introduced is 1:1 to 1.8.
A production system adopted in a method for preparing dicyandiamide by mixing ammonia and carbon dioxide comprises a preheater, a reactor, a first filter, a polymerization reactor, a second filter, a crystallizer and a catcher; the preheater is connected with the reactor, the filter I, the polymerization reactor, the filter II, the crystallizer and the catcher in sequence through pipelines; the trap is connected with the reactor by a compressor.
As a preferred embodiment in the present application, the polymerization reactor is provided with a water inlet and a steam outlet; impurity discharge ports are formed in the first filter and the second filter; the crystallizer is provided with a process cold air inlet.
As a better implementation mode in the application, the reactor is a fluidized bed reactor or a fixed bed reactor, the reactor is connected with a flue gas system through a pipeline, and high-temperature flue gas is used for providing heat.
As a preferred embodiment herein, the heat of polymerization in the polymerization reactor is absorbed by water, which is converted to steam for heat removal.
Compared with the prior art, the invention has the beneficial effects that:
compared with the production flow (figure 2) for producing dicyandiamide by the lime nitrogen method, the production flow (figure 2) of the invention relates to the steps of hydrolysis, decalcification, polymerization, crystallization, separation, drying and the like, and the production flow of the invention relates to the steps of high-temperature reaction, polymerization, crystallization, trapping and the like.
The method utilizes the existing ammonia and carbon dioxide as raw materials to prepare the dicyandiamide, reduces the treatment process of the ammonia and the carbon dioxide in the process, can reduce energy consumption, and simultaneously utilizes the existing ammonia and the existing carbon dioxide to reduce the transportation cost and the raw material cost.
And (III) a large amount of heat is generated in the polymerization process of the cyanamide in the polymerization reactor, and water enters the polymerization reactor to absorb the heat to generate by-product steam, so that the phenomena that the polymerization reactor corrodes equipment and destroys the polymerization process due to overhigh temperature are avoided, the heat loss is reduced, and the energy consumption is saved.
(IV) carbon dioxide is fed from the crystallizer for the purpose of: (1) cooling and crystallizing dicyandiamide gas from a polymerization reactor as process cold gas; (2) the feed stock is fed from a crystallizer and the temperature of the feed stock is raised by cooling the dicyandiamide gas. If the carbon dioxide is directly fed into the reactor, the carbon dioxide needs to be preheated, so that the energy consumption is increased, and in addition, process cold air needs to be fed into the crystallization, so that the cost is increased. The carbon dioxide gas carries dicyandiamide solid to enter a trap, after gas-solid separation, a part of gas enters a reactor after being compressed and pressurized by a compressor, unreacted ammonia and a small amount of dicyandiamide powder can be brought into the reactor for recycling, so that the utilization rate of raw materials reaches 90-99%, and the other part of gas from the trap is treated as process tail gas and then reused, thereby avoiding pollution to the environment.
The method prepares dicyandiamide by mixing ammonia and carbon dioxide, can effectively solve the problem of waste residues generated in the existing lime nitrogen method, achieves the purposes of environmental protection and reduction of the treatment process of the waste residues, and simultaneously avoids the dicyandiamide product containing calcium oxide, calcium hydroxide and other impurities, and the product purity is 98-99.5%.
And (VI) the high-temperature reaction, the polymerization reaction and the crystallization process in the method are all gas-phase processes, so that compared with a liquid-phase process adopted by a lime nitrogen method, the consumption of water resources is reduced, and the process of controlling the temperature by using cooling water in the lime nitrogen hydrolysis decalcification is avoided.
Description of the drawings:
fig. 1 is a schematic process flow diagram of a method for preparing dicyandiamide by mixing ammonia and carbon dioxide in examples 1 and 2 of the invention.
FIG. 2 is a schematic flow chart of a conventional lime nitrogen method for preparing dicyandiamide.
FIG. 3 is a schematic process flow diagram of a method for preparing dicyandiamide by mixing ammonia and carbon dioxide in examples 3 and 4 of the present invention.
Detailed Description
A production system for preparing dicyandiamide by mixing ammonia and carbon dioxide comprises a preheater, a reactor, a first filter, a polymerization reactor, a second filter, a crystallizer and a catcher; the preheater is connected with the reactor, the filter I, the polymerization reactor, the filter II, the crystallizer and the catcher in sequence through pipelines; the trap is connected with the reactor by a compressor.
The polymerization reactor is provided with a water feeding port and a steam outlet; impurity discharge ports are formed in the first filter and the second filter; the crystallizer is provided with a process cold air inlet,
the reactor is a fluidized bed reactor or a fixed bed reactor, the reactor is connected with a flue gas system through a pipeline, and heat is provided by using high-temperature flue gas.
The heat in the polymerization reaction in the polymerization reactor can be absorbed by water, which is turned into steam to perform heat removal.
A method I for preparing dicyandiamide by mixing ammonia and carbon dioxide by using the system comprises the following steps:
firstly, compressing and pressurizing gas from a trap by a compressor, then introducing the gas into a reactor, simultaneously preheating ammonia, then introducing the preheated ammonia into the reactor, and mixing and reacting the gas and the preheated ammonia in the reactor to obtain the cyanamide gas. The cyanamide gas enters a filter-1, solid impurities brought out are filtered, and then the filtered solid impurities are introduced into a polymerization reactor.
Introducing the cyanamide gas into the polymerization reactor, and polymerizing in the polymerization reactor to obtain the dicyandiamide gas.
The dicyandiamide gas enters a filter-2, and solid impurities brought out are filtered and then sent into a crystallizer. And thirdly, after the dicyandiamide gas enters a crystallizer and is mixed with carbon dioxide serving as process cold air for cooling and crystallization, the gas with the dicyandiamide crystals enters a trap for gas-solid separation, dicyandiamide solid is obtained by collection, a part of the gas enters a reactor through a compressor, and a part of the gas is used as process tail gas for treatment and reuse.
The temperature of the preheated ammonia is 0 to 140 ℃, and more preferably 25 to 80 ℃.
The temperature of the reactor for mixing and reacting ammonia and carbon dioxide is controlled at 650-900 ℃.
The polymerization temperature in the polymerization reactor was 200 ℃ and 400 ℃.
The temperature of the process cold air carbon dioxide is 0-100 ℃, and the further optimization is 25-60 ℃.
The mass ratio of the introduced ammonia to the carbon dioxide is 1: 1-1.8.
A second method for preparing dicyandiamide by mixing ammonia and carbon dioxide by using the system comprises the following steps:
firstly, compressing and pressurizing gas from a trap by a compressor, then introducing the gas into a reactor, simultaneously preheating carbon dioxide, then introducing the preheated carbon dioxide into the reactor, and mixing and reacting the preheated carbon dioxide and the preheated carbon dioxide in the reactor to obtain cyanamide gas. The cyanamide gas enters a filter-1, solid impurities brought out are filtered, and then the filtered solid impurities are introduced into a polymerization reactor.
Introducing the cyanamide gas into the polymerization reactor, and polymerizing in the polymerization reactor to obtain the dicyandiamide gas. The dicyandiamide gas enters a filter-2, and solid impurities brought out are filtered and then sent into a crystallizer.
And thirdly, after the dicyandiamide gas enters a crystallizer and is mixed with ammonia serving as process cold air to be cooled and crystallized, the gas with the dicyandiamide crystals enters a trap to complete gas-solid separation, dicyandiamide solid is obtained by collection, a part of the gas enters a reactor through a compressor, and a part of the gas is used as process tail gas for treatment and reuse.
The temperature of the carbon dioxide after preheating is 0 to 140 ℃, and more preferably 25 to 80 ℃.
The temperature of the reactor for the mixed reaction of carbon dioxide and ammonia is controlled at 650-900 deg.C, more preferably at 720-800 deg.C.
The polymerization temperature in the polymerization reactor is 200 ℃ to 400 ℃, more preferably 260 ℃ to 320 ℃.
The temperature of the process cold gas ammonia is 0 to 100 ℃, more preferably 25 to 60 ℃.
The mass ratio of the introduced carbon dioxide to the ammonia is 1: 1-1.8.
In order to facilitate the understanding of the present invention, the process described in the present invention will be further described with reference to the accompanying drawings and the detailed description. It should not be understood that the scope of the above-described subject matter of the present invention is limited to the following examples.
Example 1:
a method for preparing dicyandiamide by mixing ammonia and carbon dioxide by using the system is shown in a schematic flow chart in figure 1.
Compressing and pressurizing gas from the catcher by a compressor, then introducing the gas into a reactor, preheating ammonia at the temperature of 50 ℃, and then introducing the preheated ammonia into the reactor, wherein the mass ratio of the preheated ammonia to the gas from the catcher is 1: 5.2. the reactor is connected with a flue gas system, high-temperature flue gas is used for providing heat for the reactor, the temperature of the reactor is controlled to be 750 ℃, and the reactor and the flue gas are mixed and reacted in a fluidized bed reactor or a fixed bed reactor to obtain cyanamide gas. The cyanamide gas enters a filter-1, solid impurities brought out are filtered, and then the filtered solid impurities are introduced into a polymerization reactor.
And introducing the cyanamide gas into the polymerization reactor, polymerizing in the polymerization reactor to obtain dicyandiamide gas, and controlling the temperature of the polymerization reactor to be 280 ℃, wherein the heat in the polymerization reaction process can be absorbed by water, and the water is changed into steam to transfer heat. The dicyandiamide gas enters a filter-2, and solid impurities brought out are filtered and then sent into a crystallizer.
Introducing dicyandiamide gas into a crystallizer, mixing, cooling and crystallizing carbon dioxide at 40 ℃ and a mass ratio of the dicyandiamide gas to ammonia, introducing the gas carrying dicyandiamide crystals into a trap to complete gas-solid separation, collecting to obtain dicyandiamide solid, introducing part of the gas into a reactor through a compressor, and treating the other part of the gas as process tail gas for reuse.
Example 2:
a method for preparing dicyandiamide by mixing ammonia and carbon dioxide by using the system is shown in a schematic flow chart in figure 1.
Compressing and pressurizing gas from the catcher by a compressor, then introducing the gas into a reactor, preheating ammonia at the temperature of 50 ℃, and then introducing the preheated ammonia into the reactor, wherein the mass ratio of the preheated ammonia to the gas from the catcher is 1: and 5.7, connecting the reactor with a flue gas system, supplying heat to the reactor by using high-temperature flue gas, controlling the temperature of the reactor to be 750 ℃, and mixing and reacting the reactor and the flue gas in a fluidized bed reactor or a fixed bed reactor to obtain the cyanamide gas. The cyanamide gas enters a filter-1, solid impurities brought out are filtered, and then the filtered solid impurities are introduced into a polymerization reactor.
And introducing the cyanamide gas into the polymerization reactor, polymerizing in the polymerization reactor to obtain dicyandiamide gas, and controlling the temperature of the polymerization reactor to be 280 ℃, wherein the heat in the polymerization reaction process can be absorbed by water, and the water is changed into steam to transfer heat. The dicyandiamide gas enters a filter-2, and solid impurities brought out are filtered and then sent into a crystallizer.
Introducing dicyandiamide gas into a crystallizer, mixing, cooling and crystallizing carbon dioxide with the mass ratio of 1.5 to ammonia and the temperature of 40 ℃ as process cold air, introducing the gas carrying dicyandiamide crystals into a trap to complete gas-solid separation, collecting to obtain dicyandiamide solid, introducing part of the gas into a reactor through a compressor, and treating the other part of the gas as process tail gas for reuse.
Example 3: different inlets for carbon dioxide and ammonia
A method for preparing dicyandiamide by mixing ammonia and carbon dioxide by using the system, and the flow schematic diagram is shown in figure 3.
Compressing and pressurizing gas from the catcher by a compressor, then introducing the gas into a reactor, simultaneously preheating carbon dioxide to 40 ℃, and then introducing the preheated carbon dioxide into the reactor, wherein the mass ratio of the preheated carbon dioxide to the gas from the catcher is 1: and 3.9, connecting the reactor with a flue gas system, supplying heat to the reactor by using high-temperature flue gas, controlling the temperature of the reactor to be 750 ℃, and mixing and reacting the reactor and the high-temperature flue gas in a fluidized bed reactor or a fixed bed reactor to obtain cyanamide gas. The cyanamide gas enters a filter-1, solid impurities brought out are filtered, and then the filtered solid impurities are introduced into a polymerization reactor.
And introducing the cyanamide gas into the polymerization reactor, polymerizing in the polymerization reactor to obtain dicyandiamide gas, and controlling the temperature of the polymerization reactor to be 280 ℃, wherein the heat in the polymerization reaction process can be absorbed by water, and the water is changed into steam to transfer heat. The dicyandiamide gas enters a filter-2, and solid impurities brought out are filtered and then sent into a crystallizer.
Introducing dicyandiamide gas into a crystallizer, mixing, cooling and crystallizing ammonia at 50 ℃ and a mass ratio of the dicyandiamide gas to carbon dioxide, introducing the gas carrying dicyandiamide crystals into a trap to complete gas-solid separation, collecting to obtain dicyandiamide solid, introducing part of the gas into a reactor through a compressor, and treating the other part of the gas as process tail gas for reuse.
Example 4: different inlets for carbon dioxide and ammonia
A method for preparing dicyandiamide by mixing ammonia and carbon dioxide by using the system, and the flow schematic diagram is shown in figure 3.
Compressing and pressurizing gas from the catcher by a compressor, then introducing the gas into a reactor, preheating carbon dioxide at the temperature of 40 ℃, and then introducing the preheated carbon dioxide into the reactor, wherein the mass ratio of the preheated carbon dioxide to the gas from the catcher is 1: and 3.7, connecting the reactor with a flue gas system, supplying heat to the reactor by using high-temperature flue gas, controlling the temperature of the reactor to be 750 ℃, and mixing and reacting the reactor and the high-temperature flue gas in a fluidized bed reactor or a fixed bed reactor to obtain cyanamide gas. The cyanamide gas enters a filter-1, solid impurities brought out are filtered, and then the filtered solid impurities are introduced into a polymerization reactor.
And introducing the cyanamide gas into the polymerization reactor, polymerizing in the polymerization reactor to obtain dicyandiamide gas, and controlling the temperature of the polymerization reactor to be 280 ℃, wherein the heat in the polymerization reaction process can be absorbed by water, and the water is changed into steam to transfer heat. The dicyandiamide gas enters a filter-2, and solid impurities brought out are filtered and then sent into a crystallizer.
Introducing dicyandiamide gas into a crystallizer, mixing, cooling and crystallizing ammonia at 50 ℃ and a mass ratio of the dicyandiamide gas to carbon dioxide, introducing the gas carrying dicyandiamide crystals into a trap to complete gas-solid separation, collecting to obtain dicyandiamide solid, introducing part of the gas into a reactor through a compressor, and treating the other part of the gas as process tail gas for reuse.
Comparing the process parameters and the cost of the method for preparing dicyandiamide in the examples 1 to 4 with the existing lime nitrogen method, the method comprises the following steps:
although the present invention has been described in detail with reference to specific embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
Claims (10)
1. A method for preparing dicyandiamide by mixing ammonia and carbon dioxide is characterized by comprising the following steps: reacting preheated ammonia and gas from a trap in a reactor to obtain cyanamide gas, filtering the cyanamide gas, polymerizing the cyanamide gas in a polymerization reactor to obtain dicyandiamide gas, filtering the dicyandiamide gas, cooling and crystallizing the dicyandiamide gas in a crystallizer using carbon dioxide as process cold air, carrying the dicyandiamide crystal into the trap by the gas to finish gas-solid separation, and collecting to obtain dicyandiamide solid; one part of the gas separated by the catcher returns to the reactor, and the other part is treated and reused as the process tail gas.
2. A method for preparing dicyandiamide by mixing ammonia and carbon dioxide is characterized by comprising the following steps: reacting preheated carbon dioxide gas with gas from a trap to obtain cyanamide gas, filtering the cyanamide gas, polymerizing the cyanamide gas in a polymerization reactor to obtain dicyandiamide gas, filtering the dicyandiamide gas, cooling and crystallizing the dicyandiamide gas in a crystallizer with ammonia as process cold air, carrying the dicyandiamide crystal into the trap by the gas to finish gas-solid separation, and collecting to obtain dicyandiamide solid; one part of the gas separated by the catcher returns to the reactor, and the other part is treated and reused as the process tail gas.
3. The process according to claim 1 or 2 for the preparation of dicyandiamide by mixing ammonia with carbon dioxide, characterized in that: the temperature after preheating the ammonia and the temperature after preheating the carbon dioxide are both 0-140 ℃, and the preferred temperature is 25-80 ℃; the polymerization temperature in the polymerization reactor was 200 ℃ and 400 ℃.
4. The process according to claim 1 for preparing dicyandiamide by mixing ammonia and carbon dioxide, wherein: the temperature of the reactor is controlled at 650-900 ℃; the mass ratio of the introduced ammonia to the carbon dioxide is 1: 1-1.8.
5. The process according to claim 2 for preparing dicyandiamide by mixing ammonia and carbon dioxide, wherein: the temperature of the reactor is controlled at 650-900 ℃; the mass ratio of the introduced carbon dioxide to the ammonia is 1: 1-1.8.
6. The process according to claim 1 for preparing dicyandiamide by mixing ammonia and carbon dioxide, wherein: the temperature of the process cold air carbon dioxide is 0-100 ℃, and the preferred temperature is 25-60 ℃.
7. The process according to claim 2 for preparing dicyandiamide by mixing ammonia and carbon dioxide, wherein: the temperature of the process cold gas ammonia is 0-100 ℃, and the preferable temperature is 25-60 ℃.
8. The production system for dicyandiamide by mixing ammonia and carbon dioxide according to claim 1 or 2, wherein the system comprises a preheater, a reactor, a first filter, a polymerization reactor, a second filter, a crystallizer and a trap; wherein the preheater is connected with the reactor, the first filter, the polymerization reactor, the second filter, the crystallizer and the catcher in sequence through pipelines; the catcher is connected with the reactor through a first pipeline and a compressor, and the catcher is connected with the tail gas absorption device through a second pipeline.
9. The system for producing dicyandiamide according to claim 8, wherein: a water feeding port and a steam outlet are respectively arranged on the polymerization reactor; impurity discharge ports are formed in the first filter and the second filter; and a process cold air inlet is arranged on the crystallizer.
10. The method of claim 8, wherein the method comprises the following steps: the reactor is a fluidized bed reactor or a fixed bed reactor, is connected with a flue gas system through a pipeline, and provides heat by using high-temperature flue gas; the heat in the polymerization reaction in the polymerization reactor can be absorbed by water, which is turned into steam to perform heat removal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110912149.7A CN113651727A (en) | 2021-08-10 | 2021-08-10 | System and method for preparing dicyandiamide by mixing ammonia and carbon dioxide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110912149.7A CN113651727A (en) | 2021-08-10 | 2021-08-10 | System and method for preparing dicyandiamide by mixing ammonia and carbon dioxide |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113651727A true CN113651727A (en) | 2021-11-16 |
Family
ID=78490995
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110912149.7A Pending CN113651727A (en) | 2021-08-10 | 2021-08-10 | System and method for preparing dicyandiamide by mixing ammonia and carbon dioxide |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113651727A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115944942A (en) * | 2022-12-06 | 2023-04-11 | 四川金象赛瑞化工股份有限公司 | Preparation method of cyanamide substance |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2721786A (en) * | 1952-04-19 | 1955-10-25 | American Cyanamid Co | Preparation of cyanamide |
| CN101016151A (en) * | 2006-08-08 | 2007-08-15 | 芮海平 | Method of preparing cyanamide aqueous solution and dicyandiamide and coproducing carbon and calcium carbonate by calcium cyanamide |
| CN205328904U (en) * | 2015-12-07 | 2016-06-22 | 上海弗鲁克科技发展有限公司 | System for synthetic dicyandiamide of one -step method |
| CN112521313A (en) * | 2020-12-16 | 2021-03-19 | 四川金象赛瑞化工股份有限公司 | System and process for producing dicyandiamide by melamine |
-
2021
- 2021-08-10 CN CN202110912149.7A patent/CN113651727A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2721786A (en) * | 1952-04-19 | 1955-10-25 | American Cyanamid Co | Preparation of cyanamide |
| CN101016151A (en) * | 2006-08-08 | 2007-08-15 | 芮海平 | Method of preparing cyanamide aqueous solution and dicyandiamide and coproducing carbon and calcium carbonate by calcium cyanamide |
| CN205328904U (en) * | 2015-12-07 | 2016-06-22 | 上海弗鲁克科技发展有限公司 | System for synthetic dicyandiamide of one -step method |
| CN112521313A (en) * | 2020-12-16 | 2021-03-19 | 四川金象赛瑞化工股份有限公司 | System and process for producing dicyandiamide by melamine |
Non-Patent Citations (1)
| Title |
|---|
| 汪多仁: "《绿色农药与化肥中间体》", 30 April 2009 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115944942A (en) * | 2022-12-06 | 2023-04-11 | 四川金象赛瑞化工股份有限公司 | Preparation method of cyanamide substance |
| CN115944942B (en) * | 2022-12-06 | 2024-04-12 | 四川金象赛瑞化工股份有限公司 | Preparation method of cyanamide substance |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102267713B (en) | Method for producing high-quality light calcium carbonate by ammonium salt circulation process | |
| CN102198953A (en) | Methods for coproducing sodium carbonate and ammonium sulfate from melamine tail gas and mirabilite | |
| CN1884077B (en) | Method for aminolysis of fluorosilicone compounds and separation of fluorine and silicon | |
| CN113651727A (en) | System and method for preparing dicyandiamide by mixing ammonia and carbon dioxide | |
| CN113511988A (en) | System and method for preparing dicyandiamide by using urea | |
| CN1208328C (en) | Trimeric cyanamide joint production method using one step method | |
| CN101519383B (en) | Process for jointly producing cyanuramide, sodium carbonate and ammonium chloride by using carbamide | |
| CN111943897A (en) | Melamine production system and process by high-pressure synthesis low-pressure gas-phase quenching method | |
| CN108796612B (en) | Method for preparing calcium sulfate whisker and co-producing ammonium sulfate by phosphogypsum cyclic decomposition | |
| CN102438947B (en) | Sodium cyanide process | |
| CN114195408A (en) | Method for preparing active lime by deep treatment of carbide slag | |
| CN105294509A (en) | System and method for synthesizing dicyandiamide by one-step process | |
| CN113651728A (en) | Method for transferring heat of polymerization reactor during dicyandiamide preparation | |
| CN114455612B (en) | Process for preparing sodium carbonate byproduct gypsum by using sodium sulfate and carbon dioxide as raw materials | |
| CN103601630A (en) | Method utilizing calcium carbide slag and carbon monoxide to synthesize calcium formate | |
| CN113651725A (en) | System and method for preparing dicyandiamide by reusing melamine tail gas | |
| CN113044857B (en) | Production process for preparing high-purity sodium cyanide or potassium cyanide with high yield | |
| CN114620697A (en) | Production process and production equipment for preparing iron phosphate by taking phosphorus iron slag as byproduct of yellow phosphorus as raw material | |
| CN213708198U (en) | Melamine production system for high-pressure synthesis low-pressure gas-phase quenching method | |
| CN102351345B (en) | Method for recovering melamine from melamine waste water and co-producing desulfurizer | |
| US4096235A (en) | Process of producing magnesia with sulfuric acid recycle | |
| CN115944942B (en) | Preparation method of cyanamide substance | |
| CN1025555C (en) | Process for manufacture of crystal calcium carbonate | |
| CN100595148C (en) | Method for preparing potassium carbonate | |
| CN1180699A (en) | Technology for producing ammonium carbonate with combined production of melamine |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |