CN210193417U - Dry ice machine with pre-crystallization tank and hydraulic station cooling - Google Patents

Abstract

The utility model discloses a dry ice machine with a pre-crystallizing tank and a hydraulic station for cooling, wherein the dry ice machine comprises a crystallizing cylinder barrel and a liquid carbon dioxide storage tank for providing liquid carbon dioxide for the crystallizing cylinder barrel; the liquid carbon dioxide storage tank is connected with the pre-crystallization tank through a pipeline to provide liquid carbon dioxide; the pre-crystallization tank is connected with the crystallization cylinder barrel through a pipeline to provide liquid carbon dioxide; the pre-crystallization tank is communicated with a gaseous carbon dioxide storage tank; the pre-crystallization tank is also provided with a gaseous carbon dioxide output port provided with a pressure regulating valve; the dry ice production method comprises the following steps: inputting liquid carbon dioxide into a pre-crystallization tank; the pre-crystallization tank continuously provides liquid carbon dioxide for the crystallization cylinder barrel under the condition of keeping the pressure intensity in the tank constant; the crystallization cylinder barrel is used for producing dry ice by extruding after crystallizing liquid carbon dioxide through a piston pushed by hydraulic pressure; adopt the utility model discloses dry ice maker just can export liquid carbon dioxide in crystallization cylinder with stable pressure.

Description

Dry ice machine with pre-crystallization tank and hydraulic station cooling

Technical Field

The invention relates to the field of dry ice manufacturing, in particular to an ice dryer with a pre-crystallization tank and a hydraulic station for cooling.

Background

1. As shown in fig. 1, in the dry ice production process, the liquid carbon dioxide storage tank 11 is usually directly connected to the crystallization cylinder 4 (although not directly connected thereto in the figure), so that the liquid carbon dioxide is crystallized and extruded in the crystallization cylinder 4. However, as the storage amount of the liquid carbon dioxide in the liquid carbon dioxide storage tank 11 gradually decreases, the pressure therein decreases, so that the speed of supplying the liquid carbon dioxide to the crystallization cylinder 4 becomes slow, the movement frequency of the piston 51 in the crystallization cylinder 4 needs to be adjusted accordingly, the operation is troublesome, and the efficiency decreases; and because the pressure in the crystallization cylinder 4 varies with the supply rate of the liquid carbon dioxide, the production becomes unstable, so that the finally produced dry ice is not uniform.

2. As shown in fig. 2, in the prior art, the middle of the crystallization cylinder 4 is connected to a second exhaust gas output pipeline 44, and both ends are respectively provided with a first exhaust port 45 and a second exhaust port 46; a second exhaust gas outlet conduit 44 for outputting gaseous carbon dioxide formed during crystallization; the first exhaust port 45 and the second exhaust port 46 are both communicated with the outside air and are used for balancing the pressure of the cylinder chambers at the two ends of the crystallization cylinder barrel 4;

however, there is a problem that when the piston 51 performs a pulling motion, air enters the crystallization cylinder 4 through the two exhaust ports, moisture in the air freezes on the inner wall of the crystallization cylinder 4, and the frozen ice can greatly obstruct the motion of the piston 51 and even damage the pull rod of the piston 51, thereby causing unnecessary loss.

3. As shown in fig. 1, two types of exhaust gases emerge from the dry ice machine, one type being a continuous exhaust gas 71 which is output from the hydraulic station 6, and the other type being an intermittent exhaust gas 72 which is output from the precrystallisation tank 3 and the crystallisation cylinder 4 and merges into one stream (the exhaust gas from the precrystallisation tank 3 is conducted through a safety valve which is not always open and therefore is intermittent; the piston 51 movement in the crystallisation cylinder 4 is frequent and therefore the output is also intermittent). The continuous waste gas 71 and the intermittent waste gas 72 are different waste gases, and if the waste gases are treated separately, two sets of devices are needed, so that the cost is overlarge; if the processing is performed simultaneously, the effect may be poor because the pressure is unstable.

Disclosure of Invention

The invention aims to solve the technical problem of providing a dry ice machine with a pre-crystallization tank and a hydraulic station for cooling, so as to solve the first problem in the background technology.

In order to achieve the purpose, the invention adopts the following technical scheme:

a dry ice machine with a pre-crystallization tank and a hydraulic station for cooling comprises a crystallization cylinder barrel for producing dry ice by extruding liquid carbon dioxide after crystallizing by a hydraulic pushing piston and a liquid carbon dioxide storage tank for providing liquid carbon dioxide for the crystallization cylinder barrel; the device is characterized in that a liquid carbon dioxide storage tank is connected with a pre-crystallization tank through a pipeline to provide liquid carbon dioxide; the pre-crystallization tank is connected with the crystallization cylinder barrel through a pipeline to provide liquid carbon dioxide;

the pre-crystallization tank is communicated with a gaseous carbon dioxide storage tank; the pre-crystallization tank is also provided with a gaseous carbon dioxide output port provided with a pressure regulating valve. The crystallization cylinder barrel is provided with a necessary regulating valve on a pipeline for the inlet and outlet of liquid carbon dioxide or gaseous carbon dioxide; and exhaust gas output by the gaseous carbon dioxide output port is communicated to the hydraulic station and is used for carrying out heat exchange with hydraulic oil for providing power for the piston.

Preferably, the pre-crystallization tank is also provided with a safety air port provided with a safety valve.

Preferably, the gaseous carbon dioxide output port of the pre-crystallization tank is communicated to the heat exchange device through a pipeline.

The ice drying machine has the advantages that the pre-crystallization tank is arranged between the liquid carbon dioxide storage tank and the crystallization cylinder barrel, so that the liquid carbon dioxide firstly enters the pre-crystallization tank, the constant internal pressure can be ensured by controlling the gas-liquid output and output in the pre-crystallization tank, the constant internal pressure is ensured, and the constant internal pressure is output to the crystallization cylinder barrel, so that the first problem in the background art is solved. The pre-crystallization tank can pre-cool the liquid carbon dioxide, so that the efficiency of converting the liquid carbon dioxide finally conveyed to the crystallization cylinder barrel into dry ice is improved; in addition, the exhaust gas (gaseous carbon dioxide) output from the pre-crystallization tank can cool the hydraulic oil in the hydraulic station, and the cold energy is fully utilized.

A dry ice production method of a dry ice machine with a pre-crystallizing tank comprises the following working states:

s1, inputting liquid carbon dioxide into the pre-crystallization tank;

s2, continuously providing liquid carbon dioxide for the crystallization cylinder barrel by the pre-crystallization tank under the condition that the pressure in the tank is kept constant; the pre-crystallization tank continuously outputs gaseous carbon dioxide and provides power for the piston to exchange heat with hydraulic oil;

and S3, crystallizing the liquid carbon dioxide by the crystallization cylinder barrel through a piston driven by hydraulic pressure, and extruding to produce dry ice.

Preferably, the pre-crystallization tank is communicated with a gaseous carbon dioxide storage tank; the pre-crystallization tank is also provided with a gaseous carbon dioxide output port provided with a pressure regulating valve; the pre-crystallization tank realizes constant pressure in the tank by adjusting input and output of gaseous carbon dioxide.

Preferably, a pressure reducing valve is arranged at a liquid carbon dioxide input port of the pre-crystallization tank, and a back pressure valve is arranged at a gaseous carbon dioxide output port of the pre-crystallization tank; the output end of the pressure reducing valve and the input end of the backpressure valve face the pre-crystallization tank.

Preferably, the pressure in the pre-crystallization tank is controlled to be between 5 and 10 bar.

Preferably, the liquid level of the liquid carbon dioxide in the pre-crystallization tank is controlled to be 20-80%.

The method has the advantages that the first problem in the background technology is solved by arranging the pre-crystallization tank between the liquid carbon dioxide storage tank and the crystallization cylinder barrel and controlling the pressure in the pre-crystallization tank to be stable, and the pressure output to the crystallization cylinder barrel is constant. And the pre-crystallization tank can pre-cool the liquid carbon dioxide, so that the efficiency of converting the liquid carbon dioxide finally conveyed to the crystallization cylinder barrel into dry ice is improved. In addition, the exhaust gas (gaseous carbon dioxide) output from the pre-crystallization tank can cool the hydraulic oil in the hydraulic station, and the cold energy is fully utilized.

Drawings

Fig. 1 is a schematic view of the ice dryer of the present invention;

FIG. 2 is a schematic illustration of a prior art crystallization cylinder;

FIG. 3 is a schematic view of a crystallization cylinder of the present invention;

FIG. 4 is a schematic view of an exhaust gas treatment device according to the present invention;

FIG. 5 is a flow diagram of the tail gas treatment of the present invention.

In the figure, 11, a liquid carbon dioxide storage tank, 12, a gaseous carbon dioxide storage tank, 2, a first heat exchanger, 3, a pre-crystallization tank, 31, a first waste gas output pipeline, 4, a crystallization cylinder, 44, a second waste gas output pipeline, 45, a first exhaust port, 46, a second exhaust port, 47, a first external pipeline, 48, a second external pipeline, 5, a hydraulic oil cylinder, 51, a piston, 6, a hydraulic station, 71, continuous waste gas, 72, intermittent waste gas, 81, a first buffer tank, 82, a second buffer tank, 83, a compressor, 84, a second heat exchanger, 85, an adsorption bed, 86, a liquefier, 87, a refrigerator, 88 and a flash evaporator.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings.

As shown in fig. 1, which is a schematic diagram of the ice dryer of the present invention, two liquid carbon dioxide storage tanks 11 are provided, one of which is dedicated to storing liquid carbon dioxide raw material, and the other is dedicated to storing liquid carbon dioxide after tail gas recovery; of course, it is also possible in principle to set both of them to one. In addition to this, a storage tank 12 for gaseous carbon dioxide is provided for storing gaseous carbon dioxide, and the pressure of gaseous carbon dioxide therein is high.

The liquid carbon dioxide storage tank 11 is connected to the top of the pre-crystallization tank 3 through a liquid carbon dioxide input pipeline, the bottom of the pre-crystallization tank 3 is connected with a liquid carbon dioxide output pipeline, and the liquid carbon dioxide output pipeline is connected with a liquid carbon dioxide input end of the crystallization cylinder barrel 4; in this way, the liquid carbon dioxide is transferred from the liquid carbon dioxide storage tank 11 to the pre-crystallization tank 3 and the crystallization cylinder 4 in this order.

The ice dryer of the invention can effectively solve the first problem in the background technology by controlling the pressure stability in the pre-crystallization tank 3. And the pre-crystallizing tank 3 can pre-cool the liquid carbon dioxide, so that the efficiency of converting the liquid carbon dioxide finally conveyed to the crystallizing cylinder 4 into dry ice is improved.

More specifically, in order to control the pressure in the pre-crystallization tank 3 to be stable, such an arrangement may be adopted that:

the top of the pre-crystallization tank 3 is connected with a gaseous carbon dioxide input pipeline and a gaseous carbon dioxide output pipeline, the gaseous carbon dioxide input pipeline is connected with a gaseous carbon dioxide storage tank 12, and when the pressure in the pre-crystallization tank 3 is too low, an electromagnetic valve on the gaseous carbon dioxide input pipeline can be opened to supplement air and pressurize;

a pressure reducing valve is arranged on the liquid carbon dioxide input pipeline, and the output end of the pressure reducing valve faces the pre-crystallization tank 3; a back pressure valve is arranged on the gaseous carbon dioxide output pipeline, and the input end of the back pressure valve faces the pre-crystallization tank 3; because the pressure at the output end is stabilized by the pressure reducing valve, and the pressure at the input end is stabilized by the backpressure valve, the pressure in the pre-crystallization tank 3 can be well stabilized.

In order to further ensure the safety, a first waste gas output pipeline 31 is also arranged at the top of the pre-crystallization tank 3, and a safety valve is arranged on the first waste gas output pipeline 31; when the pressure is too high, the safety valve can be opened to release excessive gas.

The pressure in the pre-crystallization tank 3 can be controlled at a certain constant pressure in the range of 5-10 bar.

The pre-crystallization tank 3 also ensures the liquid level stability of the liquid carbon dioxide while ensuring the pressure stability. The liquid level is typically set at 20% to 80%, which can be controlled by a pressure relief valve on the liquid carbon dioxide inlet line and a solenoid valve on the liquid carbon dioxide outlet line. In order to monitor the liquid level, a level sensor may be provided in the pre-crystallization tank 3.

Before the liquid carbon dioxide enters the crystallization cylinder 4, the liquid carbon dioxide enters the pre-crystallization tank 3 through a liquid carbon dioxide input pipeline, is partially converted into gaseous carbon dioxide in the pre-crystallization tank 3 and is discharged through a gaseous carbon dioxide output pipeline. Because the generation of the gaseous carbon dioxide absorbs heat, the temperature of the remaining part of the liquid carbon dioxide is lower, and the conversion efficiency of the part of the liquid carbon dioxide which is transferred to the crystallization cylinder 4 and then converted into dry ice is greatly improved. This is another great advantage of the provision of the pre-crystallization tank 3. Tests prove that the conversion efficiency of the dry ice machine is 48% at most and 40% above at least.

The gaseous carbon dioxide outlet line connected to the pre-crystallization tank 3 will output gases with a large amount of cold, which, as known from thermodynamic knowledge, are at a lower temperature than the liquid carbon dioxide fed into the liquid carbon dioxide inlet line, so that the cold of the former can be completely recovered to the latter. In particular the first heat exchanger 2 is used.

The gases in the liquid carbon dioxide inlet line and the gaseous carbon dioxide outlet line are passed into two mutually heat-transferrable passages of the first heat exchanger 2, so that the latter gas can be used to further cool the liquid of the former. This gas can also be used to cool the hydraulic station 6 described below.

A piston 51 is provided in the crystallization cylinder 4, and the piston 51 is used for pressing dry ice powder to mold it. The piston 51 is driven by a hydraulic ram 5, the hydraulic ram 5 being driven by a hydraulic station 6. The hydraulic station 6 usually generates a large amount of heat during operation, and a cooling coil is generally arranged in the hydraulic station 6, so that gaseous carbon dioxide output from the first heat exchanger 2 is communicated with the cooling coil, hydraulic oil in the hydraulic station 6 can be cooled by utilizing gaseous carbon dioxide with partial cold, and finally, the gaseous carbon dioxide output from the hydraulic station 6 is continuous waste gas 71.

Of course, the first heat exchanger 2 may not be provided, and the gas output from the gaseous carbon dioxide output pipeline of the pre-crystallization tank 3 may be directly passed to the hydraulic station 6 to cool the hydraulic oil.

The second problem in the background art is next solved.

As shown in fig. 3, in the present invention, the first exhaust port 45 is connected to the first external connection pipe 47, the second exhaust port 46 is connected to the second external connection pipe 48, and the first external connection pipe 47 and the second external connection pipe 48 are simultaneously connected to a pipe four-way connection piece, which is disposed at the exhaust gas outlet on the cylinder wall in the middle of the piston stroke and is in sealed communication with the exhaust gas outlet; the conduit four-way connection communicates with a second exhaust gas outlet conduit 44. Therefore, the crystallization cylinder 4 is isolated from the outside air, and the pressure of the two cylinder chambers in the crystallization cylinder 4 can be stabilized.

Of course, there are other ways to make the exhaust gas outlet, the second exhaust gas outlet pipe 44, the first exhaust port 45 and the second exhaust port 46 in a sealed manner, such as providing a sealed chamber: the first exhaust port 45, the second exhaust port 46 and the exhaust gas outlet are all arranged inside the closed chamber, and the closed chamber is communicated with the second exhaust gas output pipeline 44.

The third problem in the background art is solved next.

Fig. 4 shows an exhaust gas treatment device. The two exhaust gases are first combined and compressed for subsequent operation. For this purpose, the continuous waste gas 71 is passed into a first buffer tank 81, and the intermittent waste gas 72 is passed into a second buffer tank 82; the first buffer tank 81 communicates with the second buffer tank 82. One of the buffer tanks, such as the second buffer tank 82, is placed in communication with the input of the compressor 83.

The two waste gases are compressed by the compressor 83, the temperature of the two waste gases rises, and the two waste gases can be cooled by the original waste gases, wherein the method is that the waste gases in the first buffer tank 81 and the waste gases in the second buffer tank 82 exchange heat with the output waste gases of the compressor 83 by the second heat exchanger 84; the concrete figure is as follows: the first buffer tank 81 and the second buffer tank 82 are connected to both ends of one passage of the second heat exchanger 84, respectively, and the output end of the compressor 83 is connected to one end of the other passage of the second heat exchanger 84, so that the other end of the passage can output cooled exhaust gas.

In order to control the pressure in the two buffer tanks well, the following arrangement is also made:

the two buffer tanks are divided into a high-pressure layer and a low-pressure layer which are connected through valves, wherein the low-pressure layer is used as a main body and is used for introducing waste gas and connecting devices, and the high-pressure layer is used for adjusting the air pressure of the low-pressure layer; the high pressure layer gas is derived from the exhaust gas from the compressor 83 or from the gaseous carbon dioxide storage tank 12. The method comprises the following specific steps:

the inside of the first buffer tank 81 is divided into a first high-pressure layer and a first low-pressure layer connected by a valve; the first high-pressure layer is communicated with the output end of the compressor 83 through a valve; the first low-pressure layer is used for connecting the second buffer tank 82 and the second heat exchanger 84; the first low pressure layer is also used for passing a continuous off-gas 71.

In this way, the continuous exhaust gas 71 is passed into the first low pressure layer, and the pressure of the first low pressure layer can be adjusted by opening the valve. The pressure in the first high-pressure layer can be set to be 1.2-2.5 MPa; the pressure intensity in the first low-pressure layer is set to be 0.1-0.8 MPa; the pressure of the exhaust gas discharged from the compressor 83 is set to 2.0 to 3.0 MPa.

The inside of the second buffer tank 82 is also divided into a second high-pressure layer and a second low-pressure layer connected by a valve; the second high-pressure layer is communicated with the output end of the compressor 83 through a valve; the second low-pressure layer is used for being connected with the first buffer tank 81, the input end of the compressor 83 and the second heat exchanger 84; the second low pressure layer is also used for the introduction of intermittent exhaust gases 72.

In this manner, the intermittent exhaust gas 72 is passed into the second low pressure layer, and the pressure of the second low pressure layer can be regulated by the second high pressure layer. The pressure in the second high-pressure layer can be set to be 1.2-2.5 MPa; the pressure in the second low-pressure layer can be set to be 0.1-0.8 MPa; the pressure of the exhaust gas output from the compressor 83 may be set to 2.0-3.0 MPa.

The valves can adopt electromagnetic valves or other valves.

The cooled exhaust gas output from the second passage of the second heat exchanger 84 is input to the adsorption bed 85, and the adsorption bed 85 is used for adsorbing impurities, moisture, and the like in the exhaust gas; the output end of the adsorption bed 85 is communicated with the input end of the liquefier 86, and a refrigerator 87 is arranged in the liquefier 86; the liquefier 86 is used to liquefy the exhaust gas; the output end of the liquefier 86 is communicated with the input end of the flash evaporator 88, and the flash evaporator 88 is used for further rectifying impurities in the liquid carbon dioxide according to the principle that different substances have different boiling points. The flash vessel 88 outputs purified liquid carbon dioxide to the liquid carbon dioxide storage tank 11. An off-gas output line is connected to each of the adsorption bed 85 and the flash evaporator 88, and outputs the impurity off-gas.

FIG. 5 shows a flow chart of the exhaust gas recovery. Wherein drying corresponds to the adsorbent bed 85, liquefaction corresponds to the liquefier 86, and rectification corresponds to the flasher 88. It will be apparent that other means may be employed to carry out the steps of the flow chart.

Finally, the working process of the whole system is explained.

Liquid carbon dioxide is conveyed into the pre-crystallization tank 3 from the liquid carbon dioxide storage tank 11, and then the pressure in the pre-crystallization tank 3 and the liquid level height of the liquid carbon dioxide are controlled to stabilize the pressure at a certain constant pressure of 5-10bar, so that the liquid level height of the liquid carbon dioxide is 20% -80%;

then, the liquid carbon dioxide in the pre-crystallization tank 3 is transmitted to the crystallization cylinder barrel 4, so that the liquid carbon dioxide is crystallized into dry ice particles in the crystallization cylinder barrel 4, and the dry ice particles are extruded and molded by a piston 51; in the process, the input and output of liquid carbon dioxide and the input and output of gaseous carbon dioxide in the pre-crystallization tank 3 are also dynamically controlled to keep the pressure and the liquid level in the pre-crystallization tank 3 stable;

because the two cylinder chambers separated by the piston 51 in the crystallization cylinder 4 are simultaneously communicated with the second exhaust gas output pipeline 44, when the piston 51 moves towards one cylinder chamber, the gas in the cylinder chamber is transferred to the second exhaust gas output pipeline 44 or the other cylinder chamber through the communication channel, so that the pressures of the two cylinder chambers are dynamically balanced in the process of the movement of the piston 51, and the process does not need to be contacted with the outside air, thereby reducing the obstruction to the movement of the piston 51 caused by the icing of water vapor and the damage to the crystallization cylinder 4, a piston pull rod and the like.

The gaseous carbon dioxide output from the pre-crystallisation tank 3 contains a significant amount of cold which can be used to cool the liquid carbon dioxide feed and the hydraulic station 6 powering the piston 51, and is ultimately output as a continuous exhaust gas 71. An intermittent exhaust gas 72 is also output from the first exhaust gas outlet line 31 connected to the pre-crystallization tank 3 and the second exhaust gas outlet line 44 connected to the crystallization cylinder 4.

The continuous waste gas 71 and the intermittent waste gas 72 are respectively introduced into a first buffer tank 81 and a second buffer tank 82, and the first buffer tank 81 is communicated with the second buffer tank 82, so that the continuous waste gas 71 and the intermittent waste gas 72 can be mixed; the mixed waste gas is input into a compressor 83, the compressor 83 compresses and outputs two waste gases, the output waste gas is cooled by the original continuous waste gas 71 and the original intermittent waste gas 72 and then is conveyed to an adsorption bed 85, the adsorption bed 85 adsorbs impurities, moisture and the like in the waste gas and conveys the dried waste gas to a liquefier 86, a refrigerator 87 is arranged in the liquefier 86 and can refrigerate and liquefy the waste gas to form liquid carbon dioxide; the liquefier 86 feeds the liquid carbon dioxide to the flash evaporator 88, the flash evaporator 88 evaporates and discharges impurities still existing in the liquid carbon dioxide, and finally the produced high-purity liquid carbon dioxide is fed back to the original liquid carbon dioxide storage tank 11 to complete the circulation.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.

Claims (2)

1. A dry ice machine with a pre-crystallization tank and a hydraulic station for cooling comprises a crystallization cylinder (4) for producing dry ice by extruding liquid carbon dioxide after crystallizing the liquid carbon dioxide by a hydraulic pushing piston (51), and a liquid carbon dioxide storage tank (11) for supplying the crystallization cylinder (4) with the liquid carbon dioxide; the device is characterized in that the liquid carbon dioxide storage tank (11) is connected with the pre-crystallization tank (3) through a pipeline to provide liquid carbon dioxide; the pre-crystallization tank (3) is connected with the crystallization cylinder barrel (4) through a pipeline to provide liquid carbon dioxide;

the pre-crystallization tank (3) is communicated with a gaseous carbon dioxide storage tank (12); the pre-crystallization tank (3) is also provided with a gaseous carbon dioxide output port provided with a pressure regulating valve; and exhaust gas output by the gaseous carbon dioxide output port is communicated to the hydraulic station (6) and is used for carrying out heat exchange with hydraulic oil for providing power for the piston (51).

2. The dry ice machine with pre-crystallization tank and hydraulic station cooling according to claim 1, characterized in that the pre-crystallization tank (3) is also opened with a safety vent equipped with a safety valve.

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