阅读说明：本技术 一种高纯度二氧化碳生产工艺 (Production process of high-purity carbon dioxide ) 是由 黄加斗 刘川 蔡炎南 于 2020-07-16 设计创作，主要内容包括：本发明公开了一种高纯度二氧化碳生产工艺,包括原料气控制、原料气水洗、原料气压缩冷却、原料气净化、制冷液化、提纯、气化、吸附、制冷精馏及储存充装,从而使最终得到的液体二氧化碳中几乎不存在其它杂质,其纯度高达99.999％以上,水洗中循环使用脱盐去除杂质、干燥塔和吸附塔内部填充物加热再生使用节约生产成本,通过液氨转化成的气氨对二氧化碳气体降温,并在液氨转化为气氨的过程中产生大量冷量将气态二氧化碳转化为液体,并且气氨可重新变为液氨实现液氨的循环使用,进一步降低成本。整个生产过程中,只需保证原料气供应充足就可实现连续生产液体二氧化碳,在生产中不需添加或补充物料。(The invention discloses a production process of high-purity carbon dioxide, which comprises raw material gas control, raw material gas washing, raw material gas compression and cooling, raw material gas purification, refrigeration and liquefaction, purification, gasification, adsorption, refrigeration and rectification, and storage and filling, so that other impurities hardly exist in the finally obtained liquid carbon dioxide, the purity of the liquid carbon dioxide reaches over 99.999 percent, the impurities are removed by circularly using desalination in the washing, and the production cost is saved by using fillers in a drying tower and an adsorption tower for heating and regeneration, the carbon dioxide gas is cooled by gas ammonia converted from liquid ammonia, a large amount of cold energy is generated in the process of converting the liquid ammonia into the gas ammonia to convert the gas carbon dioxide into the liquid, and the gas ammonia can be converted into the liquid ammonia again to realize the recycling of the liquid ammonia, so that the cost is further. In the whole production process, the continuous production of the liquid carbon dioxide can be realized only by ensuring sufficient supply of the raw material gas, and materials do not need to be added or supplemented in the production.)

1. A production process of high-purity carbon dioxide is characterized by comprising the following steps:

s1: controlling the raw material gas to finish the conveying of the raw material gas;

s2: washing the raw material gas to remove mechanical impurities and water-soluble gas;

s3: compressing and cooling the raw material gas;

s4: purifying the raw material gas, and removing moisture, impurities and abnormal odor in the raw material gas;

s5: refrigerating and liquefying, namely converting gaseous carbon dioxide into liquid by utilizing a large amount of cold energy generated by converting liquid ammonia from liquid to gas;

s6: purifying, namely removing impurities in the liquid carbon dioxide by using a rectification principle;

s7: gasifying, namely gasifying the liquid carbon dioxide to obtain gaseous carbon dioxide;

s8: adsorption, adopting an adsorption column to adsorb impurities;

s9: refrigerating and rectifying, namely converting gaseous carbon dioxide into liquid carbon dioxide, and then rectifying and purifying;

s10: and (5) storing and filling.

2. The process for producing high purity carbon dioxide according to claim 1, wherein: and S2, washing the raw material gas by desalted water to clean impurities in the raw material gas, wherein the raw material gas washing comprises a raw material gas washing tower, a circulating water pump and a water cooling tower, so that the desalted water is recycled.

3. The process for producing high purity carbon dioxide according to claim 1, wherein: and S3, pressurizing the gas by adopting an oil-free lubrication compressor in the compression of the raw gas, dividing the compression of the raw gas into three sections of compression, gradually increasing the pressure of the gas to 2.0-2.5 MPa in a sectional manner, and cooling the gas compressed in the three sections to normal temperature by adopting an evaporative cooler in the cooling of the raw gas.

4. The process for producing high purity carbon dioxide according to claim 1, wherein: the step S4 is to purify the raw material gas, which includes separating with a separator, adsorbing with an adsorption tower, and drying with a drying tower, wherein the separator separates the moisture in the raw material gas, the separated gas is discharged from the top of the separator, the moisture is discharged from the bottom of the separator, the adsorption tower is filled with activated carbon, the activated carbon is used to adsorb impurities in the gas and purify abnormal odor in the gas, the drying tower is filled with a 3A or 4A molecular sieve to further adsorb moisture and impurities in the gas, so that the moisture content in the gas is less than 20ppm, and the methanol is less than 8 ppm.

5. The process for producing high purity carbon dioxide according to claim 4, wherein: the drying tower and the adsorption tower are provided with electric heating devices, and the filling materials with internal failures are heated and regenerated for use through the electric heating devices.

6. The process for producing high purity carbon dioxide according to claim 1, wherein: the step S5 includes reducing the temperature of carbon dioxide and liquefying the carbon dioxide, the reducing the temperature of the carbon dioxide is completed in a gas ammonia precooler, the liquefying the carbon dioxide is completed in an ammonia cooling liquefier, the gas ammonia from the ammonia cooling liquefier exchanges heat with the carbon dioxide gas, the cold energy of the gas ammonia is recycled, the temperature of the carbon dioxide gas is reduced, liquid ammonia is added into the ammonia cooling liquefier, the liquid ammonia is converted into a gaseous state from a liquid state to generate a large amount of cold energy, and the gaseous carbon dioxide is converted into the liquid carbon dioxide.

7. The process for producing high purity carbon dioxide according to claim 6, wherein: and the gas ammonia is changed into liquid ammonia again through the ammonia liquid separator, the ice maker and the ammonia evaporative cooler in sequence and stored in the ammonia storage tank, and then enters the ammonia cold liquefier to complete the recycling of the liquid ammonia.

8. The process for producing high purity carbon dioxide according to claim 1, wherein: the step S7 converts the rectified liquid carbon dioxide into gaseous carbon dioxide by using a gasifier.

9. The process for producing high purity carbon dioxide according to claim 1, wherein: the number of the adsorption columns used in the step S8 is 4, each adsorption column is filled with a plurality of adsorbents, and the gaseous carbon dioxide sequentially passes through the 4 adsorption columns to remove impurities in the gaseous carbon dioxide one by one.

10. The process for producing high purity carbon dioxide according to claim 1, wherein: the step S9 is to convert the gaseous carbon dioxide into liquid carbon dioxide by using a refrigerator.

Technical Field

The invention relates to the technical field of carbon dioxide production, in particular to a production process of high-purity carbon dioxide.

Background

During the production of carbon dioxide, gaseous carbon dioxide is often converted to liquid carbon dioxide in order to facilitate storage of the carbon dioxide. The liquid carbon dioxide is a refrigerant, can be used for preserving food and artificial rainfall, and can also be used as an industrial raw material for preparing sodium carbonate, urea and soda water. The food-grade carbon dioxide has the purity of over 99.9 percent, so the production process of the food-grade carbon dioxide has high requirements.

Waste gas is often generated in the chemical production process, the generated carbon dioxide waste gas is utilized to produce liquid carbon dioxide, the waste gas can be recycled, and the pollution to the environment caused by the waste gas discharged into the atmosphere can be prevented. Therefore, carbon dioxide waste gas generated in the chemical production process is usually adopted as raw material gas in the production of the liquid carbon dioxide at present, and then the raw material gas is subjected to a series of treatments to obtain the liquid carbon dioxide. However, the problems of low purification efficiency of carbon dioxide, low cost and the like still exist in the process of producing food-grade high-purity carbon dioxide.

Disclosure of Invention

In view of the above disadvantages, the present invention provides a process for producing high purity carbon dioxide, which can improve the purification efficiency of carbon dioxide, further reduce the production cost, and realize continuous production of carbon dioxide with a purity of 99.999% or more.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

a process for producing high purity carbon dioxide comprising the steps of:

s1: controlling the raw material gas to finish the conveying of the raw material gas;

s2: washing the raw material gas to remove mechanical impurities and water-soluble gas;

s3: compressing and cooling the raw material gas;

s4: purifying the raw material gas, and removing moisture, impurities and abnormal odor in the raw material gas;

s5: refrigerating and liquefying, namely converting gaseous carbon dioxide into liquid by utilizing a large amount of cold energy generated by converting liquid ammonia from liquid to gas;

s6: purifying, namely removing impurities in the liquid carbon dioxide by using a rectification principle;

s7: gasifying, namely gasifying the liquid carbon dioxide to obtain gaseous carbon dioxide;

s8: adsorption, adopting an adsorption column to adsorb impurities;

s9: refrigerating and rectifying, namely converting gaseous carbon dioxide into liquid carbon dioxide, and then rectifying and purifying;

s10: and (5) storing and filling. Preferably, the raw material gas washing of step S2 is to wash impurities in the raw material gas with desalted water, and the raw material gas washing includes a raw material gas washing tower, a circulating water pump and a water cooling tower, so as to recycle the desalted water.

Preferably, in the step S3, the raw material gas compression is performed by using an oil-free lubrication compressor to pressurize the gas, the raw material gas compression is divided into three-stage compression, and the gas pressure is gradually increased to 2.0-2.5 MPa in stages. And the raw material gas is cooled to normal temperature by adopting an evaporative cooler to cool the gas compressed by the three sections.

Preferably, the purification of the raw material gas in step S4 includes separation by a separator, adsorption by an adsorption tower, and drying by a drying tower, the separator separates moisture in the raw material gas, the gas after separation exits from the top of the separator, moisture exits from the bottom of the separator, the adsorption tower is filled with activated carbon, the activated carbon is used for adsorbing impurities in the gas and purifying abnormal odor in the gas, the drying tower is filled with a 3A or 4A molecular sieve for further adsorbing moisture and impurities in the gas, so that the moisture content in the gas is less than 20ppm, and the methanol is less than 8 ppm.

Preferably, the drying tower and the adsorption tower are provided with electric heating devices, and the filling materials which are failed in the drying tower and the adsorption tower are heated and regenerated by the electric heating devices.

Preferably, the step S5 includes reducing the temperature of carbon dioxide and liquefying the carbon dioxide, where the reducing the temperature of the carbon dioxide is performed in a gas ammonia precooler, the liquefying the carbon dioxide is performed in an ammonia-cooling liquefier, the gas ammonia from the ammonia-cooling liquefier exchanges heat with the carbon dioxide gas, the cooling capacity of the gas ammonia is recovered, and the temperature of the carbon dioxide gas is reduced, and the ammonia-cooling liquefier is added with liquid ammonia, and the liquid ammonia is converted from a liquid state to a gaseous state to generate a large amount of cooling capacity, so as to convert the gaseous carbon dioxide into the liquid carbon dioxide.

Preferably, the gas ammonia is changed into liquid ammonia again through the ammonia liquid separator, the ice maker and the ammonia evaporative cooler in sequence and stored in the ammonia storage tank, and then enters the ammonia cold liquefier to complete the recycling of the liquid ammonia. Preferably, the step S7 uses a gasifier to convert the liquid carbon dioxide after rectification into gaseous carbon dioxide.

Preferably, the number of the adsorption columns used in step S8 is 4, each adsorption column is filled with a plurality of adsorbents, and the gaseous carbon dioxide sequentially passes through the 4 adsorption columns to remove impurities in the gaseous carbon dioxide one by one.

Preferably, the step S9 uses a refrigerator to convert the gaseous carbon dioxide into liquid carbon dioxide.

The invention has the beneficial effects that: 1. the method comprises the steps of raw material gas washing, raw material gas purification, one-by-one adsorption by an adsorption column and rectification again, so that the finally obtained liquid carbon dioxide reaches the food grade, the purity of the liquid carbon dioxide is up to more than 99.999 percent, and other impurities hardly exist;

2. the desalted water is recycled in the raw material gas washing process, and the drying tower and the adsorption tower used in the raw material gas purification process are heated by adopting the electric heating devices, so that fillers in the drying tower and the adsorption tower are heated and regenerated for use after long-term purification failure, and the production cost is saved;

3. the invention utilizes gas ammonia heat exchange to reduce the temperature of carbon dioxide gas in a gas ammonia precooler, utilizes cold energy generated by converting liquid ammonia into gas to liquefy the carbon dioxide in an ammonia cold liquefier, the gas ammonia after heat exchange is converted into liquid ammonia again after sequentially passing through a liquid ammonia separator, an ice maker and ammonia evaporative cooling, the liquid ammonia enters the ammonia cold liquefier again, the converted gas ammonia enters the gas ammonia precooler to form a cycle, thereby realizing the continuous refrigeration and liquefaction of the carbon dioxide gas, and the liquid ammonia can be reused, thereby further reducing the cost;

4. the invention can realize continuous production of liquid carbon dioxide under the condition of sufficient supply of raw material gas, and does not need to add or supplement materials in the production process.

The invention is further described with reference to the following figures and examples.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

In order to explain technical contents, structural features, and objects and effects of the present invention in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.