CN112619357A - Method and device for improving efficiency of hydrogen adsorption column and hydrogen recovery system - Google Patents
Method and device for improving efficiency of hydrogen adsorption column and hydrogen recovery system Download PDFInfo
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Abstract
The invention discloses a method for improving the efficiency of a hydrogen adsorption column, which adopts heat conducting oil as a medium, cools the heat conducting oil, and then conveys the heat conducting oil to the hydrogen adsorption column to be used as a cold source of the hydrogen adsorption column, thereby providing lower low-temperature working conditions for the hydrogen adsorption column; and after the heat conduction oil is subjected to heating treatment, the heat conduction oil is conveyed to the hydrogen adsorption column to be used as a heat source for the regeneration of the hydrogen adsorption column, so that higher high-temperature regeneration conditions are provided for the hydrogen adsorption column. The invention also discloses a device for improving the efficiency of the hydrogen adsorption column and a hydrogen recovery system containing the device. The invention can reduce the temperature of the hydrogen adsorption column during use and improve the temperature during regeneration, thereby effectively improving the quality of the recovered hydrogen and further improving the quality of the polysilicon product.
Description
Technical Field
The invention belongs to the technical field of polycrystalline silicon, and particularly relates to a method and a device for improving the efficiency of a hydrogen adsorption column and a hydrogen recovery system.
Background
At present, there are various methods for producing polycrystalline silicon, such as silicon tetrachloride reduction method, silane thermal decomposition method, fluidized bed method, modified siemens method, etc., wherein the modified siemens method is the mainstream technology for producing polycrystalline silicon in the world at present, and about 85% of large-scale polycrystalline silicon production plants adopt the modified siemens method. The existing polysilicon production line in China basically adopts an improved Siemens method process.
In the process of producing polycrystalline silicon by an improved Siemens method, tail gas is generated, the generated tail gas mainly comprises hydrogen, chlorosilane and hydrogen chloride, and the generated tail gas is treated by a dry tail gas recovery process, namely various gases in the tail gas are separated and recovered by unit operations such as low-pressure condensation, compression and pressure rise, absorption and desorption, adsorption and regeneration and the like, and the separated gases are reused in the polycrystalline silicon production process, so that the aims of energy conservation, consumption reduction and closed material circulation are fulfilled.
In a traditional reduction tail gas recovery system, a hydrogen adsorption column is used for adsorbing impurities such as chlorosilane, hydrogen chloride, methane, boron, phosphorus, carbon and the like in hydrogen and releasing heat, the temperature of the adsorption column is increased due to the heat release, and the adsorption effect of the adsorption column is weakened due to the temperature increase, so that the adsorption column needs to be synchronously cooled by using a cold source to provide a using condition and maintain the normal adsorption capacity of the adsorption column. After the hydrogen adsorption column is used for a period of time, the adsorption of the adsorbent reaches a saturated state, the hydrogen adsorption column needs to be regenerated, namely impurities such as chlorosilane and boron adsorbed by the adsorbent are separated out to recover the adsorption capacity of the hydrogen adsorption column, and the regeneration process of the hydrogen adsorption column needs to absorb heat, so that the hydrogen adsorption column needs to be heated by a heat source to provide regeneration conditions.
In the improved Siemens process, the adsorption impurity removal of hydrogen in tail gas is a key technology for hydrogen recovery, the recovered hydrogen is one of raw materials for producing polycrystalline silicon, and the quality of the recovered hydrogen directly determines the product quality of the polycrystalline silicon. Therefore, in order to improve the quality of the recovered hydrogen, it is necessary to provide as low a temperature as possible when the hydrogen adsorption column is used and as high a temperature as possible when the hydrogen adsorption column is regenerated to improve the quality of the recovered hydrogen and further improve the quality of the polycrystalline silicon.
However, in the current technology, circulating water is used as a cold source, and the lowest temperature that can be provided is 30 ℃ (the lowest temperature of the circulating water is 30 ℃); the maximum temperature of 170 c (maximum steam temperature of 180 c) can be provided using steam heated pressurized water as the heat source. Therefore, the use and regeneration effects of the hydrogen adsorption column are influenced by the limitation of the temperatures of the cold source and the heat source, so that the quality of the recovered hydrogen is difficult to further improve.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a method and a device for improving the efficiency of a hydrogen adsorption column and a hydrogen recovery system, aiming at the above disadvantages in the prior art, so as to reduce the temperature of the hydrogen adsorption column during use and improve the temperature during regeneration, thereby effectively improving the quality of the recovered hydrogen, and further improving the quality of polysilicon products
According to one aspect of the invention, a method for improving the efficiency of a hydrogen adsorption column is provided, and the technical scheme is as follows:
a method for improving the efficiency of a hydrogen adsorption column adopts heat conduction oil as a medium, cools the heat conduction oil, and then conveys the heat conduction oil to the hydrogen adsorption column to be used as a cold source of the hydrogen adsorption column, so as to provide a lower low-temperature working condition for the hydrogen adsorption column; and after the heat conduction oil is subjected to heating treatment, the heat conduction oil is conveyed to the hydrogen adsorption column to be used as a heat source for the regeneration of the hydrogen adsorption column, so that higher high-temperature regeneration conditions are provided for the hydrogen adsorption column.
Preferably, the method specifically comprises the following steps,
s1, when the hydrogen adsorption column is in use (i.e. when the hydrogen adsorption column is in an operating state for adsorbing impurities): firstly, heat conduction oil is conveyed to a cooling unit for cooling, the cooled heat conduction oil is conveyed to a hydrogen adsorption column to serve as the cold source, and the heat conduction oil output from the hydrogen adsorption column is conveyed back to the cooling unit for recycling;
s2, during regeneration of the hydrogen adsorption column: the heat conduction oil is conveyed to the heating unit for heating, the heated heat conduction oil is conveyed to the hydrogen adsorption column to be used as the heat source required by regeneration, and the heat conduction oil output from the hydrogen adsorption column is conveyed back to the heating unit for recycling.
Preferably, in the step S1, the cooling unit is a two-stage cooling unit, and includes a first cooler and a second cooler, the heat transfer oil is first conveyed to the first cooler for cooling, then conveyed to the second cooler for further cooling, and then conveyed to the hydrogen adsorption column.
Preferably, in step S1, the first cooler uses circulating water as a cooling medium; the second cooler adopts water with the temperature of 7 ℃ as a cooling medium;
the temperature of the heat conducting oil after further temperature reduction is 10-13 ℃.
Preferably, in the step S2, the heating unit is an electric heater; the temperature of the heated heat conduction oil is 200-250 ℃.
Preferably, before the conduction oil is introduced into the first cooler in the step S1 and before the conduction oil is introduced into the heating unit in the step S2, pressurizing the conduction oil to increase the flow rate of the conduction oil, wherein the pressurizing is introducing nitrogen of 0.5 to 0.6 MPaG; the flow rate of the heat transfer oil is 200-250 t/h.
Compared with the prior art, the method for improving the efficiency of the hydrogen adsorption column adopts the heat conduction oil as the medium, and the cooled heat conduction oil can provide a lower temperature condition for the use of the hydrogen adsorption column by cooling or cooling the heat conduction oil medium, so that the adsorption effect is improved, the quality of recovered hydrogen is improved, and the quality of polycrystalline silicon is improved; the heated heat conduction oil can provide higher temperature condition for the regeneration of the hydrogen adsorption column, thereby improving the regeneration effect.
According to another aspect of the invention, a device for improving the efficiency of a hydrogen adsorption column is provided, and the technical scheme is as follows:
a device for improving the efficiency of a hydrogen adsorption column comprises,
the hydrogen adsorption column is used for adsorbing impurities in the hydrogen;
the cooling unit is connected with the hydrogen adsorption column and used for providing a low-temperature medium for the hydrogen adsorption column;
and the heating unit is connected with the hydrogen adsorption column and used for providing a high-temperature medium for the hydrogen adsorption column.
Preferably, the device further comprises a storage tank, wherein the storage tank is connected with the cooling unit and the heating unit and is used for storing the medium, and the medium is heat conduction oil;
the cooling unit comprises a first cooler and a second cooler, wherein the first cooler is used for receiving the heat conduction oil output from the storage tank and primarily cooling the heat conduction oil; one end of the second cooler is connected with the first cooler, and the other end of the second cooler is connected with the hydrogen adsorption column and used for further cooling the heat conduction oil output by the first cooler.
Preferably, the device further comprises an expansion tank, wherein the inlet of the expansion tank is connected with the storage tank, and the outlet of the expansion tank is connected with the first cooler and the heating unit; the expansion tank is provided with a pressurizing device, and nitrogen of 0.5-0.6MPaG is introduced into the expansion tank through the pressurizing device, so that heat conduction oil in the expansion tank has certain pressure, the pressure of an outlet of the expansion tank is improved, larger heat conduction oil flow is obtained, the larger heat conduction oil flow can improve the cooling effect and the heating effect during regeneration of the hydrogen adsorption column during use, and further the efficiency of the hydrogen adsorption column is improved.
Preferably, the device further comprises a pump, the pump comprises a first pump, a second pump and a third pump,
the first pump is arranged between the storage tank and the expansion tank;
the second pump is arranged between the expansion tank and the first cooler;
the third pump is disposed between the expansion tank and the heating unit.
The device of promotion hydrogen adsorption column efficiency of this embodiment adopts the conduction oil as the medium to through setting up cooling unit and heating element, cool off or cool down the conduction oil medium, thereby effectively improve the use and the regeneration condition of hydrogen adsorption column, and then improve and retrieve the hydrogen quality, improve the polycrystalline silicon quality.
According to another aspect of the present invention, there is provided a hydrogen recovery system, which comprises:
the utility model provides a hydrogen recovery system, including the absorption tower, with heat exchanger, hydrogen filter that the absorption tower is connected, with the hydrogen buffer tank that the hydrogen filter is connected still include above the device that promotes hydrogen adsorption column efficiency, the one end of hydrogen adsorption column with the heat exchanger is connected, its other end with the hydrogen filter is connected.
The hydrogen recovery system of the embodiment can improve the recovery quality of hydrogen in the polycrystalline silicon production process, and further improve the quality of polycrystalline silicon products.
Drawings
FIG. 1 is a schematic view of the structure of an apparatus for enhancing the performance of a hydrogen adsorption column in example 2;
fig. 2 is a schematic structural view of a hydrogen recovery system in embodiment 3.
In the figure: 1-a storage tank; 2-a first pump; 3-an expansion tank; 4-a second pump; 5-a first cooler; 6-a second cooler; 7-a third pump; 8-a heating unit; 9-hydrogen adsorption column; 10-a first valve; 11-a second valve; 12-a third valve; 13-a fourth valve; 14-a heat exchanger; 15-an absorption column; 16-a hydrogen filter; 17-a hydrogen buffer tank; 18-a device for improving the efficiency of the hydrogen adsorption column.
Detailed Description
In order to make the technical solutions of the present invention better understood, the present invention will be further clearly and completely described below with reference to the accompanying drawings and specific examples of the present invention.
In the prior art, the low temperature condition of the hydrogen adsorption column can only reach 30 ℃ at least when in use, the high temperature condition of the hydrogen adsorption column can only reach 180 ℃ at most when in regeneration, the hydrogen adsorption column is not obvious in use and regeneration effect and is difficult to ensure the quality of the recovered hydrogen due to the limitation of the temperatures of a cold source and a heat source, and the product quality of the polycrystalline silicon is influenced.
Therefore, the invention provides a method for improving the efficiency of a hydrogen adsorption column, which comprises the steps of adopting heat conduction oil as a medium, cooling the heat conduction oil, and then conveying the cooled heat conduction oil to the hydrogen adsorption column to be used as a cold source of the hydrogen adsorption column, so as to provide a lower low-temperature working condition for the hydrogen adsorption column; and after the heat conduction oil is subjected to heating treatment, the heat conduction oil is conveyed to the hydrogen adsorption column to be used as a heat source for the regeneration of the hydrogen adsorption column, so that higher high-temperature regeneration conditions are provided for the hydrogen adsorption column.
Correspondingly, the invention also provides a device of the method for improving the efficiency of the hydrogen adsorption column, which comprises the hydrogen adsorption column, a hydrogen adsorption column and a hydrogen adsorption column, wherein the hydrogen adsorption column is used for adsorbing impurities in hydrogen; the cooling unit is connected with the hydrogen adsorption column and is used for providing a low-temperature medium for the hydrogen adsorption column; and the heating unit is connected with the hydrogen adsorption column and is used for providing a high-temperature medium for the hydrogen adsorption column.
Correspondingly, the invention also provides a hydrogen recovery system, which comprises an absorption tower, a heat exchanger connected with the absorption tower, a hydrogen filter, a hydrogen buffer tank connected with the hydrogen filter, and the device for improving the effect of the hydrogen adsorption column, wherein one end of the hydrogen adsorption column in the device for improving the effect of the hydrogen adsorption column is connected with the heat exchanger, and the other end of the hydrogen adsorption column is connected with the hydrogen filter.
Example 1
The embodiment discloses a method for improving the efficiency of a hydrogen adsorption column, which comprises the steps of adopting heat conduction oil as a medium, cooling the heat conduction oil, and then conveying the heat conduction oil to the hydrogen adsorption column to serve as a cold source when the hydrogen adsorption column is used, so as to provide a lower low-temperature working condition for the hydrogen adsorption column; and after the heat conduction oil is subjected to heating treatment, the heat conduction oil is conveyed to the hydrogen adsorption column to be used as a heat source for the regeneration of the hydrogen adsorption column, so that higher high-temperature regeneration conditions are provided for the hydrogen adsorption column.
The conditions (i.e., working conditions) when the hydrogen adsorption column is used are low temperature and high pressure, and the conditions when it is regenerated are high temperature and low pressure. The method for improving the efficiency of the hydrogen adsorption column of the present embodiment specifically includes step S1 and step S2.
S1, when the hydrogen adsorption column is used:
and S101, conveying the heat conduction oil to a cooling unit for cooling, wherein the cooling unit is used for two-stage cooling and comprises a first cooler and a second cooler.
S101-1, firstly, conveying heat conduction oil to a first cooler for cooling.
The first cooler may be a shell-and-tube cooler, or any other type of cooler. The cooling medium may be circulating water at about 30 ℃ provided by an auxiliary system of a polysilicon production plant, or may be other medium capable of achieving a cooling effect on the heat transfer oil, which is not further limited in this embodiment.
Considering that the flow rate of the heat transfer oil affects the cooling or heating effect of the hydrogen adsorption column, the smaller the flow rate is, the worse the cooling and heating effects are.
Further, in this embodiment, before the heat transfer oil is introduced into the first cooler, pressurizing the heat transfer oil is further included to increase the flow rate of the low-temperature heat transfer oil.
Specifically, firstly, heat conduction oil is conveyed into an expansion tank, 0.5-0.6MPaG of nitrogen is input into the expansion tank, and the heat conduction oil is pressurized through the nitrogen to provide standby pressure for a second pump, so that the pressure of the outlet of the second pump is improved, the flow of the low-temperature heat conduction oil can be improved by improving the pressure of the outlet of the second pump, the cooling effect on a hydrogen adsorption column is ensured and improved, and the adsorption effect is further improved; and then, the pressurized heat conduction oil is conveyed to the first cooler by a pump, and the temperature can be reduced to about 30 ℃ after the pressurized heat conduction oil exchanges heat with circulating water in the first cooler. In the embodiment, the maximum treatment capacity of the hydrogen adsorption column is 8 ten thousand Nm3/h of tail gas, the flow rate of the heat transfer oil is designed according to the maximum treatment capacity, and the flow rate of the low-temperature heat transfer oil is 200-250t/h, preferably 200 t/h.
And S102-2, and then conveying the mixture to a second cooler for further cooling.
The second cooler may be a shell-and-tube cooler, or any other type of cooler. The cooling medium may be water at 7 ℃ as a refrigerant provided by an auxiliary system of a polysilicon production plant, or may be other media capable of further cooling the heat transfer oil, which is not further limited in this embodiment.
Specifically, the heat transfer oil which is preliminarily cooled to about 30 ℃ is conveyed to a second cooler, and the heat transfer oil at about 30 ℃ is subjected to heat exchange with the water at 7 ℃ serving as a refrigerant in the second cooler, so that the temperature of the heat transfer oil is further reduced to 10-13 ℃.
And S103, conveying the heat conduction oil after further cooling to a hydrogen adsorption column to be used as the cold source.
Specifically, the heat conduction oil with the temperature of 10-13 ℃ is conveyed to a hydrogen adsorption column, so that the hydrogen adsorption column (hereinafter referred to as an adsorption column) is in a lower low-temperature environment than the prior art, and a better adsorption effect is obtained. The heat conduction oil with the temperature of 10-13 ℃ absorbs the heat released when the adsorption column adsorbs impurities, and the temperature of the heat conduction oil after the heat absorption rises to about 17 ℃.
And S104, conveying the heat conduction oil with the temperature of about 17 ℃ output from the hydrogen adsorption column back to a cooling unit (a second cooler) for recycling.
After the hydrogen adsorption column is used for a period of time, the adsorbed impurities are increased and gradually reach saturation, at the moment, the adsorption capacity of the hydrogen adsorption column is obviously reduced, and the hydrogen adsorption column needs to be regenerated (for example, when the adsorption capacity of the hydrogen adsorption column for adsorbing the impurities is reduced to 70% of the initial maximum adsorption capacity, the hydrogen adsorption column needs to be regenerated and can be determined according to actual conditions so as to recover the adsorption efficiency of the hydrogen adsorption column) so as to recover the adsorption capacity of the hydrogen adsorption column. In this example, the hydrogen adsorption column was used for 10 hours and then regenerated. It should be noted that the hydrogen adsorption column is regenerated after 10 hours in this embodiment, which is only an example, and is not limited to the hydrogen adsorption column being regenerated after 10 hours.
S2: when the hydrogen adsorption column is regenerated:
s201, firstly, conveying heat conduction oil to a heating unit for heating.
The heating unit may be a tubular electric heater, or any other type of heater, and this embodiment is not limited further.
Optionally, in order to ensure the stability and the safety of the heating temperature of the heat transfer oil, the electric heater can adopt automatic control, namely the electric heater has the function of setting the temperature and controlling the interlocking to automatically control the heating temperature, such as adopting an 15000KW low-temperature heat transfer oil electric heater. By setting the heating temperature to be 200-250 ℃, preferably 210 ℃ and setting the interlocking, when the temperature of the heat-conducting oil is heated to be above 210 ℃, the electric heater automatically stops heating, and when the temperature is lower than the set temperature, the electric heater automatically starts, so that the manual operation and the potential safety hazard can be greatly reduced.
Further, in this embodiment, before the conduction oil is introduced into the electric heater, the conduction oil is pressurized to increase the flow rate of the high-temperature conduction oil.
Specifically, firstly, heat conduction oil is conveyed into an expansion tank, 0.5-0.6MPaG of nitrogen is input into the expansion tank, and the heat conduction oil is pressurized through the nitrogen to provide a standby pressure for a third pump, so that the pressure at the outlet of the third pump is improved, the flow of high-temperature heat conduction oil can be improved by improving the pressure at the outlet of the third pump, the heating effect on a hydrogen adsorption column is ensured and improved, and the effect of impurity precipitation in the adsorption column is further improved; and then the pressurized heat transfer oil is conveyed to the electric heater by a pump, the pressurized heat transfer oil is heated in the electric heater, and the temperature can be increased to 200-250 ℃. In the embodiment, the flow rate of the high-temperature heat transfer oil is 200-250t/h, and preferably 200 t/h.
And S202, conveying the heated heat conduction oil to a hydrogen adsorption column to serve as the heat source.
Specifically, 200-250 ℃ heat conduction oil is conveyed to the hydrogen adsorption column, so that the hydrogen adsorption column is in a higher high-temperature environment (at most 180 ℃) than that in the prior art, and a better desorption (namely impurity precipitation) effect is obtained. After heat exchange is carried out between the 200-heat conduction oil at 250 ℃ and the hydrogen adsorption column, the temperature of the heat conduction oil is reduced to about 180 ℃.
And S203, the heat conduction oil with the temperature of about 180 ℃ output from the hydrogen adsorption column is conveyed back to the heating unit for recycling.
According to the method for improving the efficiency of the hydrogen adsorption column, the heat conduction oil is adopted as the medium, the heat conduction oil medium is cooled or cooled firstly, and the cooled heat conduction oil can provide a lower temperature condition for the use of the hydrogen adsorption column, so that the adsorption effect is improved, the quality of recovered hydrogen is improved, and the quality of polycrystalline silicon is improved; the heated heat conduction oil can provide higher temperature condition for the regeneration of the hydrogen adsorption column, thereby improving the regeneration effect.
Example 2
As shown in fig. 1, this embodiment discloses an apparatus that can be used in the method for improving the performance of the hydrogen adsorption column of embodiment 1, comprising,
the hydrogen adsorption column 9 is used for adsorbing impurities in the hydrogen;
a cooling unit connected to the hydrogen adsorption column 9 for supplying a low-temperature medium to the hydrogen adsorption column 9;
and the heating unit 8 is connected with the hydrogen adsorption column 9 and is used for providing a high-temperature medium for the hydrogen adsorption column 9.
Specifically, this embodiment device still includes storage tank 1, and storage tank 1 is connected with cooling unit, heating unit 8 for store above-mentioned medium, the medium adopts the conduction oil. The cooling unit comprises a first cooler 5 and a second cooler 6, wherein the first cooler 5 is used for receiving the heat conduction oil output from the storage tank 1 and primarily cooling the heat conduction oil; one end (i.e. an inlet) of the second cooler 6 is connected with an outlet of the first cooler 5, the other end (i.e. an outlet) of the second cooler 6 is connected with an inlet of the hydrogen adsorption column 9, and the second cooler 6 is used for further reducing the temperature of the heat conduction oil output by the first cooler 5.
In this embodiment, the first cooler 5 and the second cooler 6 may be both shell-and-tube coolers, or any other types of coolers. The first cooler 5 can adopt circulating water with the temperature of about 30 ℃ provided by an auxiliary system of a polycrystalline silicon production plant as a cooling medium, and the second cooler 6 can adopt water with the temperature of 7 ℃ provided by the auxiliary system of the polycrystalline silicon production plant as the cooling medium. Firstly, conducting heat oil and circulating water at about 30 ℃ in a first cooler 5 to carry out first heat exchange and temperature reduction, wherein the temperature of the conducting heat oil (when a hydrogen adsorption column is switched from a regeneration process to an adsorption working process, the temperature of the conducting heat oil coming out of the hydrogen adsorption column is 200-250 ℃) is reduced to about 30 ℃ through heat exchange; then, the heat exchange and temperature reduction are carried out for the second time in the second cooler 6 with water at 7 ℃, and the temperature of the heat conducting oil is reduced to 10-13 ℃, namely the low-temperature medium.
Of course, the first cooler 5 and the second cooler 6 in the present embodiment may be any other type of cooler capable of achieving a similar effect, and are not limited to the shell-and-tube cooler.
A first valve 10 is further provided between the second cooler 6 and the hydrogen adsorption column 9 for controlling the time for transferring the low-temperature heat transfer oil (10-13 ℃) output from the second cooler 6 to the hydrogen adsorption column 9: when the hydrogen adsorption column 9 is used, the hydrogen adsorption column 9 adsorbs impurities such as chlorosilane, boron, carbon and the like in hydrogen and releases heat, at the moment, the first valve 10 is opened, the heat conducting oil cooled by the first cooler 5 and the second cooler 6 enters the hydrogen adsorption column 9 to absorb the heat released by adsorption, so that the hydrogen adsorption column 9 is in a low-temperature condition with a lower temperature than that in the prior art when in use, the adsorption column can adsorb the impurities more easily, and the use effect of the hydrogen adsorption column is improved; when the hydrogen adsorption column 9 is regenerated, the first valve 10 is closed.
In this embodiment, the outlet of the hydrogen adsorption column 9 is connected to the inlet of the first cooler 5, a second valve 11 is provided therebetween, and the second valve 11 and the first valve 10 are synchronized, i.e., the second valve 11 and the first valve 10 are simultaneously opened or closed. The heat conducting oil with the low temperature of 10-13 ℃ is heated to about 17 ℃ after absorbing heat, flows out from an outlet of the hydrogen adsorption column 9 and then is conveyed back to the first cooler 5 again (when the hydrogen adsorption column carries out the adsorption working process, the circulating water with the temperature of 30 ℃ is stopped to be led into the first cooler to avoid the loss of cold energy, the heat conducting oil with the temperature of about 17 ℃ is directly cooled to 10-13 ℃ in the second cooler and then enters the hydrogen adsorption column to absorb heat to complete the circulation process, when the hydrogen adsorption column is switched from the regeneration process to the use process, the temperature of the heat conducting oil coming out of the hydrogen adsorption column can reach 200 ℃ and 250 ℃, at the moment, the high-temperature heat conducting oil exchanges heat with the circulating water to be cooled in the first cooler and then enters the second cooler to be cooled to avoid the high-temperature heat conducting oil directly entering the second cooler to be cooled, and the water with the temperature of 7 ℃ is heated too high to cause thermal shock, then enters a second cooler for cooling, thereby realizing the recycling of the heat conducting oil. The maximum treatment capacity of the hydrogen adsorption column of the present embodiment can reach 8 ten thousand Nm 3/h.
Specifically, the heating unit 8 can adopt a tubular electric heater, and in order to ensure the stability and safety of the heating temperature of the heat transfer oil, the electric heater also has an automatic temperature control function, namely the electric heater can realize the interlocking control of the heating temperature by setting a temperature threshold, and if the electric heater can be a 15000KW low-temperature heat transfer oil electric heater. When the hydrogen adsorption column 9 is regenerated, the heating temperature threshold of the electric heater is set to 200-250 ℃, the electric heater heats the heat-conducting oil to 200-250 ℃, and the high-temperature medium is obtained.
Of course, the heating unit 8 of the present embodiment may be any other type of heater having a similar function, and is not limited to an electric heater.
In this embodiment, the temperature threshold is preferably 210 ℃, when the temperature of the heat transfer oil is heated to the temperature threshold (in this embodiment, the temperature is above 210 ℃), the electric heater automatically stops heating, and when the temperature is lower than the temperature threshold, the electric heater automatically starts, so that a stable temperature of the high-temperature medium heat transfer oil is provided, and manual operation and potential safety hazards can be greatly reduced.
A third valve 12 is arranged between the electric heater and the hydrogen adsorption column 9 and used for controlling the time for transmitting the high-temperature heat conduction oil (200-: when the hydrogen adsorption column 9 is in use (i.e., performing the adsorption process), the third valve 12 is closed; when the hydrogen adsorption column 9 is regenerated, the third valve 12 is opened (and the first valve 10 is closed), the heat conducting oil heated by the electric heater enters the hydrogen adsorption column 9 to heat the hydrogen adsorption column 9, so that the hydrogen adsorption column 9 is in a high-temperature condition with higher temperature than that in the prior art during regeneration, and adsorbed impurities such as chlorosilane, boron and carbon are more easily desorbed and separated out, thereby improving the regeneration effect of the hydrogen adsorption column.
In this embodiment, the outlet of the hydrogen adsorption column 9 is connected to the inlet of the electric heater, a fourth valve 13 is provided therebetween, and the fourth valve 13 and the third valve 12 are synchronized, that is, the fourth valve 13 and the third valve 12 are simultaneously opened or closed. The high-temperature heat conduction oil is subjected to heat exchange with the hydrogen adsorption column 9, the temperature is reduced to about 180 ℃, the heat conduction oil flows out from the outlet of the hydrogen adsorption column 9, and then the heat conduction oil is conveyed back to the electric heater for heating so as to be recycled.
Further, the device also comprises an expansion tank 3, wherein the inlet of the expansion tank 3 is connected with the storage tank 1, the outlet of the expansion tank 3 is connected with the first cooler 5 and the heating unit 8, and a pressurizing device is arranged on the expansion tank. The expansion tank is used for increasing the pressure of the heat conduction oil, namely nitrogen is introduced into the expansion tank by a pressurizing device, the pressure of the nitrogen is preferably controlled to be 0.5-0.6MPaG, and the expansion tank can also be used for temporarily storing the heat conduction oil so as to supplement the heat conduction oil in the working process of the device.
Further, the device still includes the pump, the pump includes first pump 2, second pump 4, third pump 7, first pump 2 locates between storage tank 1 and the expansion tank 3 for carry the conduction oil in the storage tank 1 to the expansion tank 3, second pump 4 locates between expansion tank 3 and the first cooler 5, be used for carrying the conduction oil in the expansion tank 3 to carry out the cooling processing in the first cooler 5 when hydrogen adsorption column 9 uses, third pump 7 locates between expansion tank 3 and the heating element 8, be used for carrying the conduction oil in the expansion tank 3 to the heating element 8 (being electric heater) when hydrogen adsorption column 9 is regenerated and carry out the intensification processing.
In this embodiment, through setting up pressure device, can provide for second pump 4 and third pump 7 and prepare for the pressure to improve the pressure of the export of second pump 4 and third pump 7, the improvement of the export pressure of second pump 4 and third pump 7 can improve the flow and the circulating speed of conduction oil, thereby guarantee and improve the cooling and the heating effect to the hydrogen adsorption column, and then improve the absorption of adsorption column and the effect of desorption.
The device for improving the efficiency of the hydrogen adsorption column adopts heat conduction oil as a medium, and cools or reduces the temperature of the heat conduction oil medium by arranging the cooling unit and the heating unit, so that the use and regeneration conditions of the hydrogen adsorption column are effectively improved, the temperature of the hydrogen adsorption column in use reaches 10-13 ℃, the temperature of the hydrogen adsorption column in regeneration reaches 200-250 ℃, the adsorption and desorption effects of the hydrogen adsorption column are improved, the quality of recovered hydrogen is improved, and the quality and the capacity of polycrystalline silicon are improved.
Example 3
As shown in fig. 2, the present embodiment discloses a hydrogen recovery system, which includes an absorption tower 15, a heat exchanger 14 connected to the absorption tower 15, a hydrogen filter 16, and a hydrogen buffer tank 17 connected to the hydrogen filter 16, and further includes a device 18 for improving the performance of the hydrogen adsorption column in embodiment 2, wherein one end of a hydrogen adsorption column 9 in the device 18 for improving the performance of the hydrogen adsorption column is connected to the heat exchanger 14, and the other end thereof is connected to the hydrogen filter 16. The outlet end of the hydrogen filter 16 is connected to a buffer tank 17.
Specifically, the heat exchanger 14 is a shell-and-tube heat exchanger, an inlet of a tube side of the heat exchanger is used for receiving the tail gas (with the temperature of about 30 ℃) generated in the polysilicon production process, an outlet of the tube side of the heat exchanger is connected with an inlet of the absorption tower (preferably arranged at the bottom of the absorption tower), and an outlet of the absorption tower 15 (preferably arranged at the top of the absorption tower) is connected with an inlet of a shell side of the heat exchanger 14. After treatment in the absorption tower 15, the remaining gas is mainly hydrogen, and also contains trace amounts of impurities such as hydrogen chloride, chlorosilane, carbon, boron, phosphorus and the like, and the temperature of the remaining gas is reduced to about-40 ℃ (the absorption tower is provided with a cooling device). The tail gas (about 30 ℃) generated in the production process of the polycrystalline silicon and the hydrogen (namely residual gas) containing impurities and discharged from the absorption tower 15 exchange heat in the heat exchanger 14, so that the temperature of the tail gas is reduced to about (-20 ℃). The outlet of the shell pass of the heat exchanger 14 is connected with the gas inlet of a hydrogen adsorption column 9 in a device 18 for improving the efficiency of the hydrogen adsorption column, hydrogen containing impurities is introduced into the hydrogen adsorption column 9, and the impurities such as trace hydrogen chloride, chlorosilane and carbon are removed by utilizing the adsorption effect of activated carbon in the hydrogen adsorption column 9. The adsorption and regeneration cycle of the hydrogen adsorption column 9 was performed according to the cycle of the apparatus for improving the performance of the hydrogen adsorption column described in example 2. The gas inlet of the hydrogen adsorption column 9 is preferably arranged at the bottom of the hydrogen adsorption column 9, and the gas outlet thereof is preferably arranged at the top of the hydrogen adsorption column 9. The inlet of the hydrogen filter 16 is connected with the outlet of each set of hydrogen adsorption columns 9, and the outlet thereof is connected with the hydrogen buffer tank 17. The hydrogen after adsorption and impurity removal is filtered in a hydrogen filter 16 to remove carbon powder so as to improve the purity of the hydrogen. And then passed to a buffer tank 17 for use, for example, in polysilicon production.
Practice proves that in the polycrystalline silicon production process, the system can ensure that the carbon content in the polycrystalline silicon product is less than or equal to 2ppm (less than 3-5ppm in the prior art).
Optionally, one hydrogen recovery system may include 1 or more, preferably more, of the devices 18 for enhancing the performance of the hydrogen adsorption column described in example 2. The plurality of means for enhancing the effectiveness of the hydrogen sorption column 18 may be connected in all parallel or all in series or a combination of both.
The hydrogen recovery system in this embodiment further preferably employs four devices 18 for increasing the efficiency of the hydrogen adsorption column, wherein two devices 18 for increasing the efficiency of the hydrogen adsorption column are connected in series to form one set, more precisely, two hydrogen adsorption columns 9 in the two devices described in embodiment 2 are connected in series to form one set, and two sets are provided, and then the two sets of devices are connected in parallel to form one set.
Specifically, establish ties the hydrogen adsorption column 9 in two embodiments 2 promotion hydrogen adsorption column performance's device 18 in as a set of, the impurity-containing hydrogen that comes out of heat exchanger 15 gets into a hydrogen activated carbon adsorption column earlier, adsorbs the edulcoration after, and hydrogen activated carbon adsorption column carries out the secondary and adsorbs the edulcoration through two-step adsorption edulcoration, can make more thoroughly that impurity got rid of to improve the purity of hydrogen. Then, every two groups are arranged in parallel to form one group, so that the processing efficiency is improved.
The device 18 for improving the efficiency of the hydrogen adsorption column can be one set, or can be a plurality of sets, preferably three sets, namely 12 devices 18 for improving the efficiency of the hydrogen adsorption column in the embodiment 2, the three sets of devices 18 for improving the efficiency of the hydrogen adsorption column are arranged in parallel and are electrically connected with a DCS (distributed control system) in a polysilicon production plant, and each series is controlled through a time program on the DCS, so that the three sets of devices 18 for improving the efficiency of the hydrogen adsorption column are subjected to low-temperature adsorption (namely, when the hydrogen adsorption column is used), heating regeneration, temperature reduction and pressurization processes respectively, and the process of the three sets of devices is alternated to reduce the time length of the hydrogen adsorption column when the hydrogen adsorption column is not used, thereby improving the treatment efficiency.
The hydrogen recovery system of the embodiment can improve the recovery quality of hydrogen in the polycrystalline silicon production process, and further improve the quality of polycrystalline silicon products.
It will be understood that the foregoing is only a preferred embodiment of the invention, and that the invention is not limited thereto. It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention, and these changes and modifications are to be considered as within the scope of the invention.
Claims (11)
1. A method for improving the efficiency of a hydrogen adsorption column is characterized in that heat conducting oil is adopted as a medium,
after cooling the heat conducting oil, conveying the heat conducting oil to a hydrogen adsorption column to be used as a cold source for the hydrogen adsorption column, and providing a lower low-temperature working condition for the hydrogen adsorption column;
and after the heat conduction oil is subjected to heating treatment, the heat conduction oil is conveyed to the hydrogen adsorption column to be used as a heat source for the regeneration of the hydrogen adsorption column, so that higher high-temperature regeneration conditions are provided for the hydrogen adsorption column.
2. The method for improving the performance of a hydrogen adsorption column according to claim 1, comprising the steps of,
s1, when the hydrogen adsorption column is used: firstly, heat conduction oil is conveyed to a cooling unit for cooling, the cooled heat conduction oil is conveyed to a hydrogen adsorption column to serve as the cold source, and the heat conduction oil output from the hydrogen adsorption column is conveyed back to the cooling unit for recycling;
s2, during regeneration of the hydrogen adsorption column: the heat conduction oil is conveyed to the heating unit for heating, the heated heat conduction oil is conveyed to the hydrogen adsorption column to be used as the heat source required by regeneration, and the heat conduction oil output from the hydrogen adsorption column is conveyed back to the heating unit for recycling.
3. The method according to claim 2, wherein in step S1, the cooling unit is a two-stage cooling unit having a first cooler and a second cooler, the heat conducting oil is first transferred to the first cooler for cooling, then transferred to the second cooler for further cooling, and then transferred to the hydrogen adsorption column.
4. The method for improving the performance of a hydrogen adsorption column according to claim 3, wherein in step S1, the first cooler uses circulating water as a cooling medium; the second cooler adopts water with the temperature of 7 ℃ as a cooling medium;
the temperature of the heat conducting oil after further temperature reduction is 10-13 ℃.
5. The method for improving the performance of a hydrogen adsorption column according to claim 2, wherein, in the step S2,
the heating unit is an electric heater; the temperature of the heated heat conduction oil is 200-250 ℃.
6. The method for improving the performance of a hydrogen adsorption column according to claim 3, wherein the method further comprises pressurizing the thermal oil to increase the flow rate of the thermal oil before passing the thermal oil to the first cooler in the step S1 and before passing the thermal oil to the heating unit in the step S2,
the pressurization is to introduce nitrogen of 0.5-0.6 MPaG; the flow rate of the heat conducting oil is 200-250 t/h.
7. A device for improving the efficiency of a hydrogen adsorption column is characterized by comprising,
the hydrogen adsorption column (9) is used for adsorbing impurities in the hydrogen;
the cooling unit is connected with the hydrogen adsorption column and used for providing a low-temperature medium for the hydrogen adsorption column;
and the heating unit (8) is connected with the hydrogen adsorption column and is used for providing a high-temperature medium for the hydrogen adsorption column.
8. The device for improving the efficiency of the hydrogen adsorption column according to claim 7, further comprising a storage tank (1), wherein the storage tank is connected with the cooling unit and the heating unit and is used for storing the medium, and the medium is heat conduction oil;
the cooling unit comprises a first cooler (5) and a second cooler (6),
the first cooler is used for receiving the heat conduction oil output from the storage tank and carrying out primary cooling on the heat conduction oil;
one end of the second cooler is connected with the first cooler, and the other end of the second cooler is connected with the hydrogen adsorption column and used for further cooling the heat conduction oil output by the first cooler.
9. The apparatus for improving the performance of a hydrogen adsorption column according to claim 8, further comprising an expansion tank (3),
the inlet of the expansion tank is connected with the storage tank, and the outlet of the expansion tank is connected with the first cooler and the heating unit;
and a pressurizing device is arranged on the expansion tank.
10. The device for improving the efficiency of a hydrogen adsorption column according to any one of claims 7 to 9, further comprising pumps including a first pump (2), a second pump (4), and a third pump (7),
the first pump is arranged between the storage tank and the expansion tank;
the second pump is arranged between the expansion tank and the first cooler;
the third pump is disposed between the expansion tank and the heating unit.
11. A hydrogen recovery system, comprising an absorption tower, a heat exchanger connected with the absorption tower, a hydrogen filter, and a hydrogen buffer tank connected with the hydrogen filter, characterized in that the system further comprises the device for improving the efficiency of the hydrogen adsorption column according to any one of claims 7 to 10, wherein one end of the hydrogen adsorption column (9) in the device for improving the efficiency of the hydrogen adsorption column is connected with the heat exchanger (14), and the other end is connected with the hydrogen filter (16).
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