A cold hydrogeneration heat energy recovery system and method

Abstract

The present invention discloses a cold hydrogeneration heat energy recovery system and method, which includes a raw material gas preheating mechanism, a raw material gas mixing and vaporizing group, a mixed gas heating mechanism, a fluidized bed, a quench tower and a rough separation tower; the raw material gas preheating mechanism is provided with a first shell-side flow channel and a first tube-side flow channel for heat exchange, and the mixed gas heating mechanism is provided with a second shell-side flow channel and a second tube-side flow channel for heat exchange; the inlet of the first tube-side flow channel is connected to a gas supply source, the outlet of the first tube-side flow channel is connected to the inlet of the raw material gas mixing and vaporizing group, the outlet of the raw material gas mixing and vaporizing group is connected to the inlet of the second shell-side flow channel, the outlet of the second shell-side flow channel is connected to the gas inlet of the fluidized bed, the outlet of the fluidized bed is connected to the inlet of the second tube-side flow channel, the inlet of the second tube-side flow channel is connected to the inlet of the quench tower, the outlet of the quench tower is connected to the inlet of the first shell, and the outlet of the first shell is connected to the rough separation tower. The present invention realizes cold hydrogeneration heat energy recovery, reduces heat waste, and lowers energy consumption and production costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of polysilicon production, and particularly relates to a cold hydrogenation heat energy recovery system and method. Background Art

[0002] At present, the process technology for preparing polysilicon in China is basically the Siemens process technology. In this process technology, a very important link is the cold hydrogenation of silicon tetrachloride to produce trichlorosilane, which is one of the raw materials for preparing polysilicon. The cold hydrogenation system is adopted by most domestic manufacturers at present. The cold hydrogenation method uses silicon powder, hydrogen, and silicon tetrachloride as raw materials, and uses copper-based, nickel-based, or iron-based catalysts, etc., to carry out gas-solid phase reactions in a fluidized bed reactor. The chemical equation is: 3SiCl4 + 2H2 + Si = 4SiHCl3. The reaction temperature is 500 - 600 °C, and the pressure is 2 - 3 MPa. The mixed gas coming out of the hydrogenation reactor passes through a quench tower to remove the entrained catalyst and silicon powder, and then passes through a quench unit and a deep cooling unit to recover and utilize hydrogen. Finally, silicon tetrachloride and trichlorosilane are separated by a rough separation tower. The single-pass conversion rate of silicon tetrachloride in this method is 15% - 35%. The reaction temperature is low, and the energy consumption is greatly reduced compared with thermal hydrogenation. It is widely used in polysilicon production.

[0003] However, there is serious heat energy waste in this system, such as: (1) The crude trichlorosilane coming out of the fluidized bed reactor directly enters the quench tower through a water cooler; (2) The gas cooled by the quench tower directly passes through an air cooler, a water cooler, and a Freon cooler in sequence to form a chlorosilane solution; (3) The silicon tetrachloride taken out from the rough separation tower is cooled by a water cooler. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a cold hydrogenation heat energy recovery system and method, which realizes the recovery of cold hydrogenation heat energy, reduces heat waste, and reduces energy consumption and production costs.

[0005] The present invention provides the following technical solutions:

[0006] In the first aspect, a cold hydrogenation heat energy recovery system is provided, including a raw material gas preheating mechanism, a raw material gas mixing and vaporization group, a mixed gas heating mechanism, a fluidized bed, a quench tower, and a rough separation tower;

[0007] The raw material gas preheating mechanism is provided with a first shell-side flow channel and a first tube-side flow channel for heat exchange. The mixed gas heating mechanism is provided with a second shell-side flow channel and a second tube-side flow channel for heat exchange. The fluidized bed is provided with a fluidized bed gas inlet and a fluidized bed outlet;

[0008] The inlet of the first tube-side flow channel is connected to a gas supply source, the outlet of the first tube-side flow channel is connected to the inlet of the raw gas mixing and vaporizing unit, the outlet of the raw gas mixing and vaporizing unit is connected to the inlet of the second shell-side flow channel, the outlet of the second shell-side flow channel is connected to the fluidized bed gas inlet, the fluidized bed outlet is connected to the inlet of the second tube-side flow channel, the outlet of the second tube-side flow channel is connected to the inlet of the quench tower, the outlet of the quench tower is connected to the inlet of the first shell-side, and the outlet of the first shell-side is connected to the rough separation tower.

[0009] Further, the raw gas preheating mechanism includes a silicon tetrachloride preheating group and a hydrogen preheating group. The silicon tetrachloride preheating group includes a silicon tetrachloride primary heat exchanger, and the hydrogen preheating group includes a hydrogen primary heat exchanger.

[0010] Further, the silicon tetrachloride preheating group further includes a silicon tetrachloride secondary heat exchanger. The tube-side inlet of the silicon tetrachloride primary heat exchanger is connected to a silicon tetrachloride gas supply source, the tube-side outlet of the silicon tetrachloride primary heat exchanger is connected to the silicon tetrachloride secondary heat exchanger, and the silicon tetrachloride secondary heat exchanger is heated by steam;

[0011] The hydrogen preheating group further includes a hydrogen secondary heat exchanger. The tube-side inlet of the hydrogen primary heat exchanger is connected to a hydrogen gas supply source, the tube-side outlet of the hydrogen primary heat exchanger is connected to the hydrogen secondary heat exchanger, and the hydrogen secondary heat exchanger is heated by steam.

[0012] Further, the raw gas mixing and vaporizing unit includes a static mixer and a vaporizer connected in series.

[0013] Further, the mixed gas heating mechanism includes a mixed gas primary heat exchanger, a mixed gas secondary heat exchanger, and a mixed gas tertiary heat exchanger;

[0014] The shell-side inlet of the mixed gas primary heat exchanger is connected to the raw gas mixing and vaporizing unit, the shell-side outlet of the mixed gas primary heat exchanger is connected to the shell-side inlet of the mixed gas secondary heat exchanger, the shell-side outlet of the mixed gas secondary heat exchanger is connected to the shell-side inlet of the mixed gas tertiary heat exchanger, and the shell-side outlet of the mixed gas tertiary heat exchanger is connected to the fluidized bed gas inlet;

[0015] The fluidized bed outlet is connected to the tube-side inlet of the mixed gas tertiary heat exchanger, the tube-side outlet of the mixed gas tertiary heat exchanger is connected to the tube-side inlet of the mixed gas secondary heat exchanger, the tube-side outlet of the mixed gas secondary heat exchanger is connected to the tube-side inlet of the mixed gas primary heat exchanger, and the tube-side outlet of the mixed gas primary heat exchanger is connected to the inlet of the quench tower.

[0016] Further, a reactor feed superheater is further included, and the reactor feed superheater is connected between the shell-side outlet of the mixed gas tertiary heat exchanger and the fluidized bed gas inlet.

[0017] Further, it also includes a quench tower reflux drum, a quench unit storage tank, and a quench heat exchanger;

[0018] The outlet of the quench tower is connected to the inlet of the quench tower reflux drum. The quench tower reflux drum is provided with a reflux drum gas outlet and a reflux drum liquid outlet, and the reflux drum liquid outlet is connected to the quench unit storage tank;

[0019] The reflux drum gas outlet is connected to the shell side inlet of the hydrogen first heat exchanger. The shell side outlet of the hydrogen first heat exchanger is respectively connected to the quench unit storage tank and the shell side inlet of the silicon tetrachloride first heat exchanger. The shell side outlet of the silicon tetrachloride first heat exchanger is respectively connected to the quench unit storage tank and the quench heat exchanger, and the quench heat exchanger is connected to the quench unit storage tank;

[0020] The quench unit storage tank is provided with a storage tank gas outlet and a storage tank liquid outlet. The storage tank gas outlet is connected to the hydrogen gas supply source, and the storage tank liquid outlet is connected to the rough separation tower.

[0021] Further, it also includes a rough separation tower bottom heat exchanger. The tube side inlet of the rough separation tower bottom heat exchanger is connected to the outlet of the quench tower. The tube side outlet of the rough separation tower bottom heat exchanger is connected to the inlet of the quench tower reflux drum. The shell side inlet of the rough separation tower bottom heat exchanger is connected to the middle and lower part outlet of the rough separation tower, and the shell side outlet of the rough separation tower bottom heat exchanger is connected to the bottom of the rough separation tower.

[0022] Further, it also includes a rough separation tower feed heat exchanger. The tube side inlet of the rough separation tower feed heat exchanger is connected to the storage tank liquid outlet. The tube side outlet of the rough separation tower feed heat exchanger is connected to the inlet of the rough separation tower. The shell side inlet of the rough separation tower feed heat exchanger is connected to the middle and upper part outlet of the rough separation tower, and the shell side outlet of the rough separation tower feed heat exchanger is connected to the silicon tetrachloride gas supply source.

[0023] In a second aspect, a method for cold hydrogenation heat energy recovery of the system described in the first aspect is provided, including the following steps:

[0024] Silicon tetrachloride and hydrogen from the gas supply source are introduced into the inlet of the first tube side flow channel of the raw material gas preheating mechanism. After being preheated by the raw material gas preheating mechanism, they enter the raw material gas mixing and vaporization group through the outlet of the first tube side flow channel for mixing and vaporization to obtain a mixed gas;

[0025] The mixed gas is introduced into the inlet of the second shell side flow channel of the mixed gas heating mechanism. After being heated by the mixed gas heating mechanism, it passes through the outlet of the second shell side flow channel and the fluidized bed gas inlet into the fluidized bed. Silicon powder is added to the fluidized bed for reaction, and the reaction generates crude trichlorosilane;

[0026] The crude trichlorosilane enters the mixed gas heating mechanism through the outlet of the fluidized bed and the inlet of the second tube pass flow channel. The mixed gas heating mechanism uses the crude trichlorosilane to heat the mixed gas from the raw gas mixing and vaporizing group. At the same time, the pre-cooled crude trichlorosilane enters the quench tower through the outlet of the second tube pass flow channel and the inlet of the quench tower for secondary cooling;

[0027] The crude trichlorosilane after secondary cooling enters the raw gas preheating mechanism through the inlet of the first shell pass. The raw gas preheating mechanism uses the crude trichlorosilane after secondary cooling to preheat the silicon tetrachloride and hydrogen from the gas supply source. The cooled crude trichlorosilane enters the rough separation tower through the outlet of the first shell pass for separation.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] The present invention includes a raw gas preheating mechanism and a mixed gas heating mechanism; among them, the mixed gas heating mechanism can use the crude product from the outlet of the fluidized bed to heat the mixed gas from the raw gas mixing and vaporizing group, and send the heated mixed gas to the fluidized bed gas inlet for reaction. At the same time, the pre-cooled crude product is sent to the quench tower for secondary cooling; the raw gas preheating mechanism can use the crude product after secondary cooling in the quench tower to preheat the raw gas from the gas supply source, and send the preheated raw gas to the raw gas mixing and vaporizing group for mixing and vaporizing. At the same time, the cooled crude product is sent to the rough separation tower for separation; the cold hydrogenation heat energy recovery system and method provided by the present invention realize cold hydrogenation heat energy recovery, reduce heat waste, and reduce energy consumption and production costs. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of the cold hydrogenation heat energy recovery system in the embodiment of the present invention;

[0031] The labels in the figure are: 1, silicon tetrachloride primary heat exchanger; 2, hydrogen primary heat exchanger; 3, quench heat exchanger; 4, quench unit storage tank; 5, silicon tetrachloride secondary heat exchanger; 6, hydrogen secondary heat exchanger; 7, static mixer; 8, vaporizer; 9, fluidized bed; 10, reactor feed superheater; 11, mixed gas tertiary heat exchanger; 12, mixed gas secondary heat exchanger; 13, mixed gas primary heat exchanger; 14, quench tower; 15, quench tower reflux tank; 16, rough separation tower; 17, rough separation tower feed heat exchanger; 18, rough separation tower bottom heat exchanger. Detailed Embodiments

[0032] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0033] It should be noted that in the description of the present invention, the orientation or positional relationship indicated by terms such as "front", "rear", "left", "right", "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and does not require the present invention to be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0034] Embodiment 1

[0035] As Figure 1 shown, this embodiment provides a cold hydrogeneration heat energy recovery system, including a raw material gas preheating mechanism, a raw material gas mixing and vaporization group, a mixed gas heating mechanism, a fluidized bed 9, a quench tower 14, and a rough separation tower 16; the raw material gas preheating mechanism is provided with a first shell-side flow channel and a first tube-side flow channel for heat exchange, the mixed gas heating mechanism is provided with a second shell-side flow channel and a second tube-side flow channel for heat exchange, and the fluidized bed is provided with a fluidized bed gas inlet and a fluidized bed outlet; the inlet of the first tube-side flow channel is connected to a gas supply source, the outlet of the first tube-side flow channel is connected to the inlet of the raw material gas mixing and vaporization group, the outlet of the raw material gas mixing and vaporization group is connected to the inlet of the second shell-side flow channel, the outlet of the second shell-side flow channel is connected to the fluidized bed gas inlet, the fluidized bed outlet is connected to the inlet of the second tube-side flow channel, the outlet of the second tube-side flow channel is connected to the inlet of the quench tower 14, the outlet of the quench tower 14 is connected to the inlet of the first shell, and the outlet of the first shell is connected to the rough separation tower 16.

[0036] Embodiment 2

[0037] This embodiment provides a method for cold hydrogeneration heat energy recovery of the system described in Embodiment 1, including the following steps:

[0038] Silicon tetrachloride and hydrogen from the gas supply source are introduced into the inlet of the first tube-side flow channel of the raw material gas preheating mechanism, preheated by the raw material gas preheating mechanism, and then enter the raw material gas mixing and vaporization group through the outlet of the first tube-side flow channel for mixing and vaporization to obtain a mixed gas; the mixed gas is introduced into the inlet of the second shell-side flow channel of the mixed gas heating mechanism, heated by the mixed gas heating mechanism, and then enters the fluidized bed 9 through the outlet of the second shell-side flow channel and the fluidized bed gas inlet. Silicon powder is added to the fluidized bed 9 for reaction to generate crude trichlorosilane; the crude trichlorosilane enters the mixed gas heating mechanism through the fluidized bed outlet and the inlet of the second tube-side flow channel. The mixed gas heating mechanism uses the crude trichlorosilane to heat the mixed gas from the raw material gas mixing and vaporization group. At the same time, the pre-cooled crude trichlorosilane enters the quench tower 14 through the outlet of the second tube-side flow channel and the inlet of the quench tower 14 for secondary cooling; the secondary-cooled crude trichlorosilane enters the raw material gas preheating mechanism through the inlet of the first shell. The raw material gas preheating mechanism uses the secondary-cooled crude trichlorosilane to preheat silicon tetrachloride and hydrogen from the gas supply source. The cooled crude trichlorosilane enters the rough separation tower 16 through the outlet of the first shell for separation.

[0039] Example 3

[0040] As Figure 1 shown, this embodiment provides a cold hydrothermal energy recovery system, including a raw material gas preheating mechanism, a raw material gas mixing and vaporization group, a mixed gas heating mechanism, a reactor feed superheater 10, a fluidized bed 9, a quench tower 14, a quench tower reflux tank 15, a quench unit storage tank 4, a quench heat exchanger 3, a rough separation tower 16, a rough separation tower bottom heat exchanger 18, and a rough separation tower feed heat exchanger 17.

[0041] The raw material gas preheating mechanism includes a silicon tetrachloride preheating group and a hydrogen preheating group. The silicon tetrachloride preheating group includes a silicon tetrachloride primary heat exchanger 1, and the tube side inlet of the silicon tetrachloride primary heat exchanger 1 is connected to a silicon tetrachloride gas supply source; the hydrogen preheating group includes a hydrogen primary heat exchanger 2, and the tube side inlet of the hydrogen primary heat exchanger 2 is connected to a hydrogen gas supply source.

[0042] The raw material gas mixing and vaporization group includes a static mixer 7 connected to the tube side outlets of both the silicon tetrachloride primary heat exchanger 1 and the hydrogen primary heat exchanger 2, and a vaporizer 8 connected to the static mixer 7. The static mixer 7 is used to uniformly mix silicon tetrachloride and hydrogen. The vaporizer 8 is heated by steam to vaporize the silicon tetrachloride and hydrogen mixture to obtain a mixed gas. Additionally, due to the use of recycled hydrogen and recycled silicon tetrachloride, the vaporizer 8 needs to discharge slag regularly. In this embodiment, the vaporizer 8 is connected to the quench tower 14 to enable the vaporizer 8 to discharge slag to the quench tower 14.

[0043] The mixed gas heating mechanism includes a mixed gas primary heat exchanger 13, a mixed gas secondary heat exchanger 12, and a mixed gas tertiary heat exchanger 11. The outlet of the vaporizer 8 is connected to the shell side inlet of the mixed gas primary heat exchanger 13, the shell side outlet of the mixed gas primary heat exchanger 13 is connected to the shell side inlet of the mixed gas secondary heat exchanger 12, the shell side outlet of the mixed gas secondary heat exchanger 12 is connected to the shell side inlet of the mixed gas tertiary heat exchanger 11, the shell side outlet of the mixed gas tertiary heat exchanger 11 is connected to the reactor feed superheater 10, and the reactor feed superheater 10 is an electric heater for further heating the mixed gas of silicon tetrachloride and hydrogen.

[0044] The fluidized bed 9 is provided with a fluidized bed gas inlet and a fluidized bed outlet; the reactor feed superheater 10 is connected to the fluidized bed gas inlet. The fluidized bed 9 is provided with a silicon powder inlet and can react with the mixed gas of silicon tetrachloride and hydrogen introduced into the fluidized bed 9 to prepare trichlorosilane. The fluidized bed outlet is connected to the tube side inlet of the mixed gas tertiary heat exchanger 11, the tube side outlet of the mixed gas tertiary heat exchanger 11 is connected to the tube side inlet of the mixed gas secondary heat exchanger 12, the tube side outlet of the mixed gas secondary heat exchanger 12 is connected to the tube side inlet of the mixed gas primary heat exchanger 13, and the tube side outlet of the mixed gas primary heat exchanger 13 is connected to the inlet of the quench tower 14.

[0045] The outlet of the quench tower 14 is divided into two branches. One branch is directly connected to the inlet of the quench tower reflux drum 15, and the other branch is connected to the tube-side inlet of the flash column bottom heat exchanger 18. The tube-side outlet of the flash column bottom heat exchanger 18 is connected to the inlet of the quench tower reflux drum 15. The shell-side inlet of the flash column bottom heat exchanger 18 is connected to the outlet at the middle and lower part of the flash column 16, and the shell-side outlet of the flash column bottom heat exchanger 18 is connected to the bottom of the flash column 16.

[0046] The quench tower reflux drum 15 is provided with a reflux drum gas outlet and a reflux drum liquid outlet. The reflux drum liquid outlet is connected to the quench unit storage tank 4; the reflux drum gas outlet is connected to the shell-side inlet of the hydrogen primary heat exchanger 2. The shell-side outlet of the hydrogen primary heat exchanger 2 is respectively connected to the quench unit storage tank 4 and the shell-side inlet of the silicon tetrachloride primary heat exchanger 1. The shell-side outlet of the silicon tetrachloride primary heat exchanger 1 is respectively connected to the quench unit storage tank 4 and the quench heat exchanger 3, and the quench heat exchanger 3 is connected to the quench unit storage tank 4.

[0047] The quench unit storage tank 4 is provided with a storage tank gas outlet and a storage tank liquid outlet. The storage tank gas outlet is connected to the hydrogen gas supply source, and the storage tank liquid outlet is connected to the tube-side inlet of the flash column feed heat exchanger 17. The tube-side outlet of the flash column feed heat exchanger 17 is connected to the inlet of the flash column 16. The shell-side inlet of the flash column feed heat exchanger 17 is connected to the outlet at the middle and upper part of the flash column 16, and the shell-side outlet of the flash column feed heat exchanger 17 is connected to the silicon tetrachloride gas supply source.

[0048] In this embodiment, the tube-side of the silicon tetrachloride primary heat exchanger 1 and the tube-side of the hydrogen primary heat exchanger 2 constitute the first tube-side flow path of the raw material gas preheating mechanism. The connected shell-side of the silicon tetrachloride primary heat exchanger 1, the shell-side of the hydrogen primary heat exchanger, and the shell-side or tube-side (the flow path for temperature reduction) of the quench heat exchanger 3 constitute the first shell-side flow path of the raw material gas preheating mechanism.

[0049] In this embodiment, the connected shell-side of the mixed gas primary heat exchanger 13, the shell-side of the mixed gas secondary heat exchanger 12, and the shell-side of the mixed gas tertiary heat exchanger 11 constitute the second shell-side flow path of the mixed gas heating mechanism. The connected tube-side of the mixed gas tertiary heat exchanger 13, the tube-side of the mixed gas secondary heat exchanger 12, and the tube-side of the mixed gas primary heat exchanger 11 constitute the second tube-side flow path of the mixed gas heating mechanism.

[0050] Example 4

[0051] This embodiment provides a method for cold hydrogenation heat energy recovery of the system described in Example 3, including the following steps:

[0052] Silicon tetrachloride from the silicon tetrachloride gas supply source is preheated through the tube side of the silicon tetrachloride primary heat exchanger 1 and then enters the static mixer 7; hydrogen from the hydrogen gas supply source is preheated through the tube side of the hydrogen primary heat exchanger 2 and also enters the static mixer 7. After the silicon tetrachloride and hydrogen are evenly mixed in the static mixer 7, they enter the vaporizer 8 for heating and vaporization to obtain a mixed gas.

[0053] The mixed gas flows through the shell sides of the mixed gas primary heat exchanger 13, the mixed gas secondary heat exchanger 12, and the mixed gas tertiary heat exchanger 11 in sequence for heating. After heating, the mixed gas enters the reactor feed superheater 10 for further heating, and then flows into the fluidized bed 9 through the fluidized bed gas inlet. At the same time, silicon powder is added to the fluidized bed 9 for reaction to generate crude trichlorosilane.

[0054] The crude trichlorosilane is output from the fluidized bed outlet and flows through the tube sides of the mixed gas tertiary heat exchanger 11, the mixed gas secondary heat exchanger 12, and the mixed gas primary heat exchanger 13 in sequence for pre-cooling. After pre-cooling, the crude trichlorosilane is introduced into the quench tower 14 for secondary cooling.

[0055] The crude trichlorosilane after secondary cooling is divided into two branches at the outlet at the top of the quench tower 14. One branch directly enters the inlet of the quench tower reflux tank 15, and the other branch enters the crude fractionation tower bottom heat exchanger 18, where it exchanges heat with the process liquid flowing from the bottom of the crude fractionation tower 16 into the crude fractionation tower bottom heat exchanger 18 to achieve tertiary cooling, and then enters the quench tower reflux tank 15.

[0056] The process liquid in the quench tower reflux tank 15 enters the quench unit storage tank 4 from the reflux tank liquid outlet. The process gas in the quench tower reflux tank 15 enters the shell side inlet of the hydrogen primary heat exchanger 2 from the reflux tank gas outlet. The cooled process liquid enters the quench unit storage tank 15 from the shell side outlet of the hydrogen primary heat exchanger 2. The uncooled process gas enters the shell side inlet of the silicon tetrachloride primary heat exchanger 1 from the other shell side outlet of the hydrogen primary heat exchanger 2. The cooled process liquid enters the quench unit storage tank 15 from the shell side outlet of the silicon tetrachloride primary heat exchanger 1. The uncooled process gas enters the quench heat exchanger 3 from the other shell side outlet of the silicon tetrachloride primary heat exchanger 1, and the obtained process liquid also enters the quench unit storage tank 4.

[0057] The main component of the process gas coming out of the quench unit storage tank 15 is hydrogen, which is directly incorporated into the hydrogen gas supply source for recycling. The process liquid coming out of the quench unit storage tank 15 enters the crude fractionation tower 16 after passing through the crude fractionation tower feed heat exchanger 17. The silicon tetrachloride gas coming out of the crude fractionation tower 16 enters the crude fractionation tower feed heat exchanger 17 for heat exchange and cooling, and then the obtained silicon tetrachloride liquid is incorporated into the silicon tetrachloride gas supply source to participate in the reaction again.

[0058] Example 5

[0059] AsFigure 1 As shown, this embodiment provides a cold hydrogenation heat energy recovery system, which is different from that of Embodiment 3 in that the silicon tetrachloride preheating group further includes a silicon tetrachloride secondary heat exchanger 5. The tube-side inlet of the silicon tetrachloride primary heat exchanger 1 is connected to a silicon tetrachloride gas supply source, the tube-side outlet of the silicon tetrachloride primary heat exchanger 1 is connected to the silicon tetrachloride secondary heat exchanger 5, and the silicon tetrachloride secondary heat exchanger 5 is heated by steam. The hydrogen preheating group further includes a hydrogen secondary heat exchanger 6. The tube-side inlet of the hydrogen primary heat exchanger 2 is connected to a hydrogen gas supply source, the tube-side outlet of the hydrogen primary heat exchanger 2 is connected to the hydrogen secondary heat exchanger 6, and the hydrogen secondary heat exchanger 6 is heated by steam. The static mixer 7 is connected to both the silicon tetrachloride secondary heat exchanger 5 and the hydrogen secondary heat exchanger 6 at the same time.

[0060] In this embodiment, the tube side of the connected silicon tetrachloride primary heat exchanger 1 and the tube side / shell side (flow channel for temperature rise) of the silicon tetrachloride secondary heat exchanger 5, as well as the tube side of the connected hydrogen primary heat exchanger 2 and the tube side / shell side (flow channel for temperature rise) of the hydrogen secondary heat exchanger 6 constitute the first tube-side flow channel of the raw material gas preheating mechanism. The silicon tetrachloride from the silicon tetrachloride gas supply source is preheated through the tube side of the silicon tetrachloride primary heat exchanger 1 and the silicon tetrachloride secondary heat exchanger 5 and then enters the static mixer 7. The hydrogen from the hydrogen gas supply source is preheated through the tube side of the hydrogen primary heat exchanger 2 and the hydrogen secondary heat exchanger 6 and then also enters the static mixer 7. After the silicon tetrachloride and hydrogen are uniformly mixed in the static mixer 7, they enter the vaporizer 8 for heating and vaporization to obtain a mixed gas.

[0061] Embodiment 6

[0062] Taking the facility for an annual output of 250,000 tons of trichlorosilane as an example, this embodiment uses the cold hydrogenation heat energy recovery system in Embodiment 3 for cold hydrogenation heat energy recovery.

[0063] 125 t / h of silicon tetrachloride from the silicon tetrachloride gas supply source is preheated through the silicon tetrachloride primary heat exchanger 1 and its temperature rises from 55 °C to 95 °C, and then it enters the static mixer 7. 8.6 t / h of hydrogen from the hydrogen gas supply source is preheated through the hydrogen primary heat exchanger 2 and its temperature rises from 40 °C to 105 °C, and then it enters the static mixer 7. The mixed gas of silicon tetrachloride and hydrogen after passing through the static mixer 7 enters the vaporizer 8 for heating and vaporization.

[0064] The vaporized mixed gas of silicon tetrachloride and hydrogen rises in temperature from 145 °C to 265 °C through the mixed gas primary heat exchanger 13, rises from 265 °C to 380 °C through the mixed gas secondary heat exchanger 12, and rises from 380 °C to 500 °C through the mixed gas tertiary heat exchanger 11. The heated mixed gas enters the reactor feed superheater 10 for further heating and then is introduced into the fluidized bed 9. At the same time, silicon powder from the silicon powder source enters the fluidized bed 9 to participate in the reaction to generate crude trichlorosilane.

[0065] The crude trichlorosilane generated by the reaction in the fluidized bed 9 flows through the mixed gas three-stage heat exchanger 11, the mixed gas two-stage heat exchanger 12, and the mixed gas one-stage heat exchanger 13 in sequence, and the temperature drops from 540 °C to 200 °C, and then enters the quench tower 14. The process gas coming out of the quench tower 14 enters the bottom heat exchanger 18 of the rough separation tower from the outlet at the top of the quench tower 14, and then enters the quench tower reflux drum 15. The process liquid in the quench tower reflux drum 15 enters the quench unit storage tank 4. The process gas in the quench tower reflux drum 15 passes through the hydrogen one-stage heat exchanger 2 and the temperature drops from 127 °C to 115 °C, then passes through the silicon tetrachloride one-stage heat exchanger 1 and the temperature drops from 115 °C to 105 °C, and finally passes through the quench heat exchanger 3. The obtained process liquid also enters the quench unit storage tank 4.

[0066] The main component of the process gas coming out of the quench unit storage tank 4 is hydrogen, which is directly incorporated into the hydrogen gas supply source and recycled. The process liquid coming out of the quench unit storage tank 4 enters the rough separation tower 16 after passing through the rough separation tower feed heat exchanger 17. The silicon tetrachloride gas coming out of the rough separation tower 16 enters the rough separation tower feed heat exchanger 17 again for heat exchange and cooling, and then the obtained silicon tetrachloride liquid is incorporated into the silicon tetrachloride gas supply source and participates in the reaction again.

[0067] Compared with the past cold hydrogenation system, the steam unit consumption is reduced from 0.8 t / t.TCS to 0.65 t / t.TCS, that is, each production line saves 18.75 t / h of steam. Calculated at 150 yuan per ton of steam, that is, 2 cold hydrogenation production lines can save more than 50 million yuan per year.

[0068] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A cold hydrothermal energy recovery system, characterized in that It includes a raw material gas preheating mechanism, a raw material gas mixing and vaporizing group, a mixed gas heating mechanism, a fluidized bed, a quench tower, and a rough separation tower, and also includes a quench tower reflux tank, a quench unit storage tank, and a quench heat exchanger; The raw material gas preheating mechanism is provided with a first shell-side flow channel and a first tube-side flow channel for heat exchange. The mixed gas heating mechanism is provided with a second shell-side flow channel and a second tube-side flow channel for heat exchange. The fluidized bed is provided with a fluidized bed gas inlet and a fluidized bed outlet; The inlet of the first tube-side flow channel is connected to a gas supply source. The outlet of the first tube-side flow channel is connected to the inlet of the raw material gas mixing and vaporizing group. The outlet of the raw material gas mixing and vaporizing group is connected to the inlet of the second shell-side flow channel. The outlet of the second shell-side flow channel is connected to the fluidized bed gas inlet. The fluidized bed outlet is connected to the inlet of the second tube-side flow channel. The outlet of the second tube-side flow channel is connected to the inlet of the quench tower. The outlet of the quench tower is connected to the inlet of the first shell-side. The outlet of the first shell-side is connected to the rough separation tower; The raw material gas preheating mechanism includes a silicon tetrachloride preheating group and a hydrogen preheating group. The silicon tetrachloride preheating group includes a silicon tetrachloride primary heat exchanger. The hydrogen preheating group includes a hydrogen primary heat exchanger; The outlet of the quench tower is connected to the inlet of the quench tower reflux tank. The quench tower reflux tank is provided with a reflux tank gas outlet and a reflux tank liquid outlet. The reflux tank liquid outlet is connected to the quench unit storage tank; The reflux tank gas outlet is connected to the shell-side inlet of the hydrogen primary heat exchanger. The shell-side outlet of the hydrogen primary heat exchanger is respectively connected to the quench unit storage tank and the shell-side inlet of the silicon tetrachloride primary heat exchanger. The shell-side outlet of the silicon tetrachloride primary heat exchanger is respectively connected to the quench unit storage tank and the quench heat exchanger. The quench heat exchanger is connected to the quench unit storage tank; The quench unit storage tank is provided with a storage tank gas outlet and a storage tank liquid outlet. The storage tank gas outlet is connected to a hydrogen gas supply source. The storage tank liquid outlet is connected to the rough separation tower.

2. The cold hydrothermal energy recovery system according to claim 1, characterized in that The silicon tetrachloride preheating group further includes a silicon tetrachloride secondary heat exchanger. The tube-side inlet of the silicon tetrachloride primary heat exchanger is connected to a silicon tetrachloride gas supply source. The tube-side outlet of the silicon tetrachloride primary heat exchanger is connected to the silicon tetrachloride secondary heat exchanger. The silicon tetrachloride secondary heat exchanger is heated by steam; The hydrogen preheating group further includes a hydrogen secondary heat exchanger. The tube-side inlet of the hydrogen primary heat exchanger is connected to a hydrogen gas supply source. The tube-side outlet of the hydrogen primary heat exchanger is connected to the hydrogen secondary heat exchanger. The hydrogen secondary heat exchanger is heated by steam.

3. The cold hydrogenation heat energy recovery system according to claim 1, wherein The raw material gas mixing and vaporizing group includes a static mixer and a vaporizer connected to each other.

4. The cold hydrogenation heat energy recovery system according to claim 1, wherein The mixed gas heating mechanism includes a mixed gas primary heat exchanger, a mixed gas secondary heat exchanger, and a mixed gas tertiary heat exchanger; The shell-side inlet of the mixed gas primary heat exchanger is connected to the raw material gas mixing and vaporizing group. The shell-side outlet of the mixed gas primary heat exchanger is connected to the shell-side inlet of the mixed gas secondary heat exchanger. The shell-side outlet of the mixed gas secondary heat exchanger is connected to the shell-side inlet of the mixed gas tertiary heat exchanger. The shell-side outlet of the mixed gas tertiary heat exchanger is connected to the fluidized bed gas inlet; The outlet of the fluidized bed is connected to the inlet of the tube side of the three-stage mixed gas heat exchanger. The outlet of the tube side of the three-stage mixed gas heat exchanger is connected to the inlet of the tube side of the two-stage mixed gas heat exchanger. The outlet of the tube side of the two-stage mixed gas heat exchanger is connected to the inlet of the tube side of the one-stage mixed gas heat exchanger. The outlet of the tube side of the one-stage mixed gas heat exchanger is connected to the inlet of the quench tower.

5. The cold hydrogenation heat energy recovery system according to claim 4, wherein, It further includes a reactor feed superheater, which is connected between the outlet of the shell side of the three-stage mixed gas heat exchanger and the inlet of the fluidized bed gas.

6. The cold hydrothermal energy recovery system according to claim 1, wherein It further includes a bottoms heat exchanger of the rough separation tower. The inlet of the tube side of the bottoms heat exchanger of the rough separation tower is connected to the outlet of the quench tower. The outlet of the tube side of the bottoms heat exchanger of the rough separation tower is connected to the inlet of the quench tower reflux drum. The inlet of the shell side of the bottoms heat exchanger of the rough separation tower is connected to the outlet at the middle and lower part of the rough separation tower. The outlet of the shell side of the bottoms heat exchanger of the rough separation tower is connected to the bottom of the rough separation tower.

7. The cold hydrothermal energy recovery system according to claim 1, characterized in that It further includes a feed heat exchanger of the rough separation tower. The inlet of the tube side of the feed heat exchanger of the rough separation tower is connected to the outlet of the storage tank liquid. The outlet of the tube side of the feed heat exchanger of the rough separation tower is connected to the inlet of the rough separation tower. The inlet of the shell side of the feed heat exchanger of the rough separation tower is connected to the outlet at the middle and upper part of the rough separation tower. The outlet of the shell side of the feed heat exchanger of the rough separation tower is connected to the silicon tetrachloride gas supply source.

8. A method for cold hydrothermal energy recovery using the system according to any one of claims 1 to 7, characterized in that, It includes the following steps: Silicon tetrachloride and hydrogen from the gas supply source are introduced into the inlet of the first tube side flow channel of the raw material gas preheating mechanism. After being preheated by the raw material gas preheating mechanism, they enter the raw material gas mixing and vaporizing group through the outlet of the first tube side flow channel for mixing and vaporization to obtain a mixed gas. The mixed gas is introduced into the inlet of the second shell side flow channel of the mixed gas heating mechanism. After being heated by the mixed gas heating mechanism, it passes through the outlet of the second shell side flow channel and the fluidized bed gas inlet and is introduced into the fluidized bed. Silicon powder is added to the fluidized bed for reaction, and crude trichlorosilane is generated by the reaction. The crude trichlorosilane enters the mixed gas heating mechanism through the outlet of the fluidized bed and the inlet of the second tube side flow channel. The mixed gas heating mechanism uses the crude trichlorosilane to heat the mixed gas from the raw material gas mixing and vaporizing group. At the same time, the pre-cooled crude trichlorosilane enters the quench tower through the outlet of the second tube side flow channel and the inlet of the quench tower for secondary cooling. The crude trichlorosilane after secondary cooling enters the raw material gas preheating mechanism through the inlet of the first shell side. The raw material gas preheating mechanism uses the crude trichlorosilane after secondary cooling to preheat the silicon tetrachloride and hydrogen from the gas supply source. The cooled crude trichlorosilane enters the rough separation tower through the outlet of the first shell side for separation.

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