Process and system for comprehensively treating ammonia-containing silane waste gas

Abstract

The invention discloses a process and a system for comprehensively treating ammonia-containing silane waste gas. The system comprises a first condenser, a silane combustion tower, a dust remover, an ammonia still, a second condenser and an ammonia water storage tank. According to the invention, silane and ammonia gas can be treated at the same time, the tedious process of respectively treating two kinds of waste gas in the traditional technology is avoided, and the treatment efficiency is improved; the first condenser is arranged for efficient condensation, it is ensured that volatile substances such as ammonia gas are effectively recycled, and resource waste is reduced; by arranging the silane combustion tower, combustible components in silane waste gas can be fully combusted and converted into harmless silicon dioxide dust, and efficient treatment of the silane waste gas is ensured; the ammonia still can enable liquid and gas to be in full contact, so that the heat transfer and mass transfer effects are improved, and the evaporation efficiency is improved; by means of treatment of the ammonia still, byproducts such as high-concentration ammonia water can be recycled.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and in particular to a process and system for comprehensively treating waste gas containing ammonia silane. Background Art

[0002] Silane (SiH4) and ammonia (NH3) are commonly used gases in the production process of solar photovoltaic cells, especially in the PECVD (plasma enhanced chemical vapor deposition) process, where they are used as plasma gas sources to deposit silicon nitride anti-reflection films. This film can reduce the reflection of light on the surface of the cell, thereby improving the photoelectric conversion efficiency of solar cells. However, these gases will produce waste gas during the reaction process, which needs to be properly handled.

[0003] Silane combustion tower is a commonly used equipment in the photovoltaic solar energy industry. The function of the stainless steel silane combustion tower is to treat silane and ammonia in the PECVD tail gas. Its working principle is that silane spontaneously ignites or undergoes oxidation reaction when it comes into contact with the input compressed air and nitrogen, and a large amount of silicon dioxide dust is generated after the reaction; ammonia is absorbed by water to form high ammonia nitrogen wastewater, and the dust is carried to the spray system by the airflow and dissolved in the water.

[0004] Silane treatment methods: ① Catalytic combustion method to treat silane so that silane reacts rapidly with oxygen in the air to generate harmless silicon dioxide and water vapor, with high treatment efficiency. This method can completely convert silane into harmless substances and reduce environmental pollution. Compared with other methods, the catalytic combustion device occupies a relatively small area and is suitable for places with limited space. However, silane is flammable and explosive, and the temperature and oxygen concentration need to be strictly controlled during the treatment process to prevent safety accidents. ② The adsorption method to treat silane is easy to operate and does not require complex equipment and processes. Compared with the catalytic combustion method, the adsorption method has less equipment investment and is suitable for small enterprises. For low-concentration silane waste gas, the adsorption method has a higher treatment efficiency. However, the adsorbent will be saturated after adsorbing a certain amount of silane and needs to be regenerated. The regeneration process may be complicated and energy-intensive. For high-concentration silane waste gas, the treatment effect of the adsorption method may be limited and needs to be used in combination with other methods.

[0005] Treatment methods for ammonia: ① The spray absorption method can use the spray liquid to react with ammonia to generate harmless ammonium salts and water, with high treatment efficiency. The spray tower has a simple structure and is easy to operate and maintain. However, the spray liquid will gradually become saturated after absorbing ammonia, and needs to be replaced or treated regularly, which increases the operating cost. The wastewater generated after the spray liquid absorbs ammonia needs to be treated to avoid secondary pollution. ② The adsorption method uses the high specific surface area and good adsorption performance of adsorbents (such as activated carbon, silica gel, molecular sieves, etc.) to effectively adsorb ammonia and reduce the ammonia concentration to a very low level. However, the adsorbent needs to be replaced regularly: the adsorbent will gradually become saturated during use and needs to be replaced regularly, increasing the operating cost. ③ The membrane separation method uses special membrane materials to separate and treat ammonia, which can achieve efficient removal of ammonia. However, the equipment cost of the membrane separation method is high, which increases the investment cost. The membrane material will gradually age or become blocked during use and needs to be replaced regularly to maintain the treatment effect. The biological treatment method uses microorganisms to decompose or convert ammonia into harmless substances, which is environmentally friendly. However, biological treatment has high requirements on environmental conditions (such as temperature, pH value, etc.), and the treatment efficiency may be affected to a certain extent. The biological treatment process is relatively long and requires sufficient reaction time.

[0006] Therefore, it is necessary to improve the existing technology to provide a more reliable solution. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a process and system for comprehensively treating ammonia-containing silane waste gas in view of the deficiencies in the above-mentioned prior art.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: In a first aspect of the present invention, a process for comprehensively treating ammonia-containing silane waste gas is provided, comprising the following steps:

[0009] S1, the mixed waste gas containing silane and ammonia is input into the first condenser for condensation, and silane and ammonia are separated. Ammonia and water vapor in the waste gas are condensed to form ammonia water which enters the ammonia evaporation tower, and the silane waste gas enters the silane combustion tower;

[0010] S2, nitrogen and compressed air are introduced into the combustion chamber of the silane combustion tower, silane is burned, and the waste gas generated is discharged after passing through the dust collector;

[0011] S3. The condensed water discharged from the first condenser enters the heat exchange chamber, and is vaporized to form water vapor after heat exchange with the combustion chamber of the silane combustion tower. The water vapor enters the ammonia distillation tower from the lower end, and the ammonia water discharged from the condenser enters the ammonia distillation tower from the upper end, and countercurrently contacts with the water vapor rising in the ammonia distillation tower. The mixture of ammonia vapor and water vapor is discharged from the top of the ammonia distillation tower, and enters the ammonia water storage tank after condensation in the second condenser. The wastewater containing ammonia nitrogen is discharged from the bottom of the ammonia distillation tower.

[0012] Preferably, the volume ratio of the gas introduced into the silane combustion tower is controlled to be silane waste gas: air: nitrogen = 1:5-20:11-44.

[0013] The second aspect of the present invention provides a system for comprehensively treating ammonia-containing silane waste gas, which uses the process as described above to treat the mixed waste gas containing silane and ammonia. The system includes: a first condenser, a silane combustion tower, a dust collector, an ammonia evaporation tower, a second condenser and an ammonia water storage tank.

[0014] Preferably, the first condenser is a single-pass shell-and-tube condenser, the mixed exhaust gas containing silane and ammonia enters the tube side of the single-pass shell-and-tube condenser, the condensed water enters the shell of the single-pass shell-and-tube condenser, the ammonia gas and the water vapor in the exhaust gas are condensed to form ammonia water, the ammonia water flows out from the lower end of the tube side and enters the ammonia distillation tower through the ammonia water delivery pipe, the silane exhaust gas is discharged from the upper part of the tube side, and enters the silane combustion tower from the bottom through the silane exhaust gas delivery pipe.

[0015] Preferably, the silane combustion tower comprises a tower body, a combustion chamber arranged at the bottom of the tower body, a heat exchange chamber located above the combustion chamber, a water distribution pipe arranged in the tower body and connected to the top of the heat exchange chamber, and a steam delivery pipe connected to the bottom of the heat exchange chamber, wherein the steam delivery pipe is connected to the ammonia distillation tower; the combustion chamber and the heat exchange chamber are separated by a heat-conducting partition;

[0016] The silane waste gas delivery pipe is connected to the bottom of the combustion chamber, the lower side of the combustion chamber is provided with an air intake pipe for delivering nitrogen and compressed air, the upper side of the combustion chamber is connected with an exhaust pipe, and the end of the exhaust pipe is connected to the dust collector.

[0017] Preferably, the upper part and the lower part of the ammonia distillation tower are respectively connected with a concentrated ammonia discharge pipe and a diluted ammonia discharge pipe, and the concentrated ammonia discharge pipe is sequentially connected to the second condenser and the ammonia water storage tank;

[0018] The silane waste gas discharged from the first condenser enters the combustion chamber of the silane combustion tower through the silane waste gas delivery pipe, is mixed with the nitrogen and compressed air entering through the air inlet pipe and burns in the combustion chamber, and the waste gas in the combustion chamber is transported to the dust collector through the exhaust pipe and discharged after dust removal;

[0019] The condensed water discharged from the first condenser enters the heat exchange chamber through the water distribution pipe, and is vaporized to form water vapor after heat exchange with the silane combustion tower. The water vapor enters the ammonia distillation tower from the lower end through the steam conveying pipe. The ammonia water discharged from the condenser enters the ammonia distillation tower from the upper end through the ammonia water conveying pipe, and countercurrently contacts with the rising water vapor in the ammonia distillation tower. The mixture of ammonia vapor and water vapor is discharged from the top of the ammonia distillation tower, and is conveyed to the second condenser by the concentrated ammonia discharge pipe for condensation, and then enters the ammonia water storage tank. The wastewater containing ammonia nitrogen is discharged from the bottom of the ammonia distillation tower through the dilute ammonia discharge pipe.

[0020] Preferably, a uniform gas distribution device is provided at the lower part of the ammonia still, and the uniform gas distribution device comprises a conical gas inlet box, a disc-shaped gas distribution box connected to the conical gas inlet, a vertical gas distribution pipe connected to the vertical gas inlet at the bottom of the conical gas inlet box, and a horizontal gas distribution pipe connected to the horizontal gas inlet at the side of the disc-shaped gas distribution box;

[0021] The vertical air distribution pipe and the horizontal air distribution pipe are connected in parallel with the ends of the steam delivery pipe.

[0022] Preferably, a conical air inlet cavity communicating with the vertical air distribution pipe is formed inside the conical air inlet box;

[0023] The inner periphery of the disc-shaped air distribution box is provided with an annular air distribution cavity connected with the horizontal air distribution pipe, and the upper part of the annular air distribution cavity is connected with a plurality of external air distribution holes;

[0024] The outer cloth air holes are conical holes, and the diameters of the outer cloth air holes gradually increase from bottom to top;

[0025] Observed from a horizontal cross section, the horizontal air distribution pipe is tangent to the outer periphery of the annular air distribution cavity.

[0026] Preferably, a plurality of inner air distribution holes are arranged in an inner circumferential array of the annular air distribution cavity on the disc-shaped air distribution box, the inner air distribution holes vertically penetrate the disc-shaped air distribution box, and the bottoms of the inner air distribution holes are connected to the conical air inlet cavity.

[0027] Preferably, the upper surface of the disc-shaped air distribution box is provided with a plurality of liquid guiding grooves extending from the center to the periphery, the plurality of liquid guiding grooves are radially arranged and staggered with the outer air distribution holes and the inner air distribution holes;

[0028] From the center to the periphery of the disc-shaped air distribution box, the width and depth of the liquid guide groove gradually increase.

[0029] The beneficial effects of the present invention are:

[0030] The present invention provides a comprehensive process and system for treating ammonia-containing silane waste gas. The present invention can treat both silane and ammonia waste gases at the same time, avoiding the cumbersome process of treating the two waste gases separately in the traditional technology, and improving the treatment efficiency.

[0031] The present invention provides a first condenser for efficient condensation, thereby ensuring effective recovery of volatile substances such as ammonia and reducing resource waste;

[0032] The present invention provides a silane combustion tower, so that the combustible components in the silane waste gas can be fully burned and converted into harmless silicon dioxide dust, thereby ensuring efficient treatment of the silane waste gas; the ammonia evaporation tower can enable the liquid and the gas to fully contact, thereby increasing the heat transfer and mass transfer effects and improving the evaporation efficiency;

[0033] The present invention can recover byproducts such as high-concentration ammonia water by setting up a treatment through an ammonia evaporation tower, and the dust and waste liquid generated during the treatment process are effectively treated, thereby avoiding the generation of secondary pollution;

[0034] The present invention provides a uniform gas distribution device to form water vapor with a rotating upward flow, thereby promoting uniform contact between water vapor and ammonia nitrogen-containing wastewater in the ammonia still tower, reducing the ammonia content in the wastewater at the bottom of the tower, and increasing the ammonia content in the concentrated ammonia byproduct at the top of the tower, thereby improving the treatment effect of the ammonia still tower;

[0035] The system of the present invention has a compact structure and is easy to operate, and can reduce energy consumption and labor costs; at the same time, the heat recovery design enables part of the heat to be recycled, further reducing the operating cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the structure of the system for comprehensive treatment of ammonia-containing silane waste gas in Example 2;

[0037] Figure 2 This is a schematic diagram of the structure of the system for comprehensive treatment of ammonia-containing silane waste gas in Example 3;

[0038] Figure 3 Schematic diagram of the internal structure of the uniform air distribution device in Example 3;

[0039] Figure 4 This is a schematic diagram of the structure of the uniform air distribution device in Example 3 from a top view;

[0040] Figure 5 for Figure 4 Cross-sectional view at AA in the middle.

[0041] Description of reference numerals:

[0042] 1—first condenser; 11—tube pass; 12—shell layer; 13—ammonia water delivery pipe; 14—silane waste gas delivery pipe;

[0043] 2—silane combustion tower; 21—tower body; 22—combustion chamber; 23—heat exchange chamber; 24—water distribution pipe; 25—steam delivery pipe; 26—air inlet pipe; 27—exhaust pipe; 28—heat-conducting baffle;

[0044] 3—ammonia evaporation tower; 31—concentrated ammonia discharge pipe; 32—diluted ammonia discharge pipe;

[0045] 4—second condenser;

[0046] 5—Ammonia storage tank;

[0047] 6—Dust collector;

[0048] 7—uniform air distribution device; 71—conical air inlet box; 72—disc-shaped air distribution box; 73—vertical air distribution pipe; 74—horizontal air distribution pipe;

[0049] 711—conical air inlet cavity; 712—vertical air inlet;

[0050] 721—horizontal air inlet; 722—annular air distribution cavity; 723—external air distribution hole; 724—internal air distribution hole; 725—liquid guide groove. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0052] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0053] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0054] Example 1

[0055] A process for comprehensively treating ammonia-containing silane waste gas comprises the following steps:

[0056] S1, the mixed waste gas containing silane and ammonia is input into the first condenser 1 for condensation, and silane and ammonia are separated. Ammonia and water vapor in the waste gas are condensed to form ammonia water and enter the ammonia distillation tower 3, and the silane waste gas enters the silane combustion tower 2;

[0057] S2, nitrogen and compressed air are introduced into the combustion chamber 22 of the silane combustion tower 2, silane is burned, and the waste gas generated is discharged after passing through the dust collector 6;

[0058] S3, the condensed water discharged from the first condenser 1 enters the heat exchange chamber 23, and is vaporized to form water vapor after heat exchange with the combustion chamber 22 of the silane combustion tower 2. The water vapor enters the ammonia evaporation tower 3 from the lower end, and the ammonia water discharged from the condenser enters the ammonia evaporation tower 3 from the upper end, and is countercurrently contacted with the water vapor rising in the ammonia evaporation tower 3. The mixture of ammonia vapor and water vapor is discharged from the top of the ammonia evaporation tower 3, and enters the ammonia water storage tank 5 after condensation by the second condenser 4. The wastewater containing ammonia nitrogen is discharged from the bottom of the ammonia evaporation tower 3.

[0059] The volume ratio of the gases introduced into the silane combustion tower 2 is controlled to be silane waste gas: air: nitrogen=1:10:22.

[0060] Example 2

[0061] A system for comprehensively treating ammonia-containing silane waste gas, which uses the process of Example 1 to treat mixed waste gas containing silane and ammonia, and the system includes: a first condenser 1, a silane combustion tower 2, a dust collector 6, an ammonia distillation tower 3, a second condenser 4 and an ammonia water storage tank 5.

[0062] In this embodiment, the first condenser 1 is a single-pass 11-tube condenser. The mixed exhaust gas containing silane and ammonia enters the tube side 11 of the single-pass 11-tube condenser, and the condensed water enters the shell 12 of the single-pass 11-tube condenser. The ammonia gas and the water vapor in the exhaust gas are condensed to form ammonia water. The ammonia water flows out from the lower end of the tube side 11 and enters the ammonia distillation tower 3 through the ammonia water delivery pipe 13. The silane exhaust gas is discharged from the upper part of the tube side 11 and enters the silane combustion tower 2 from the bottom through the silane exhaust gas delivery pipe 14.

[0063] In this embodiment, the silane combustion tower 2 includes a tower body 21, a combustion chamber 22 arranged at the bottom of the tower body 21, a heat exchange chamber 23 located above the combustion chamber 22, a water distribution pipe 24 arranged in the tower body 21 and connected to the top of the heat exchange chamber 23, and a steam delivery pipe 25 connected to the bottom of the heat exchange chamber 23, and the steam delivery pipe 25 is connected to the ammonia distillation tower 3; the combustion chamber 22 and the heat exchange chamber 23 are separated by a heat conductive partition 28;

[0064] The silane waste gas delivery pipe 14 is connected to the bottom of the combustion chamber 22. The lower side of the combustion chamber 22 is provided with an air intake pipe 26 for conveying nitrogen and compressed air. The upper side of the combustion chamber 22 is connected to an exhaust pipe 27, and the end of the exhaust pipe 27 is connected to the dust collector 6.

[0065] In this embodiment, the upper and lower parts of the ammonia evaporation tower 3 are respectively connected with a concentrated ammonia discharge pipe 31 and a diluted ammonia discharge pipe 32, and the concentrated ammonia discharge pipe 31 is connected in sequence to the second condenser 4 and the ammonia water storage tank 5;

[0066] The silane waste gas discharged from the first condenser 1 enters the combustion chamber 22 of the silane combustion tower 2 through the silane waste gas delivery pipe 14, and is mixed with the nitrogen and compressed air entering through the air inlet pipe 26 and burned in the combustion chamber 22. The waste gas in the combustion chamber 22 is delivered to the dust collector 6 (bag dust collector 6 in this example) through the exhaust pipe 27, and is discharged after dust removal.

[0067] The condensed water discharged from the first condenser 1 enters the heat exchange chamber 23 through the water distribution pipe 24, and is vaporized to form water vapor after heat exchange with the combustion chamber 22 of the silane combustion tower 2. The water vapor enters the ammonia evaporation tower 3 from the lower end through the steam conveying pipe 25. The ammonia water discharged from the condenser enters the ammonia evaporation tower 3 from the upper end through the ammonia water conveying pipe 13, and countercurrently contacts with the water vapor rising in the ammonia evaporation tower 3. The mixture of ammonia vapor and water vapor is discharged from the top of the ammonia evaporation tower 3, and is conveyed to the second condenser 4 by the concentrated ammonia discharge pipe 31 for condensation, and then enters the ammonia water storage tank 5. The waste water containing ammonia nitrogen is discharged from the bottom of the ammonia evaporation tower 3 through the dilute ammonia discharge pipe 32.

[0068] Example 3

[0069] As a further improvement on the basis of Example 2, in this embodiment, a uniform gas distribution device 7 is provided at the lower part of the ammonia still 3, and the uniform gas distribution device 7 includes a conical air inlet box 71, a disc-shaped air distribution box 72 connected to the conical air inlet, a vertical air distribution pipe 73 connected to the vertical air inlet 712 at the bottom of the conical air inlet box 71, and a horizontal air distribution pipe 74 connected to the horizontal air inlet 721 on the side of the disc-shaped air distribution box 72;

[0070] The vertical gas distribution duct 73 and the horizontal gas distribution duct 74 are connected in parallel to the ends of the steam delivery pipe 25 .

[0071] The conical air inlet box 71 has a conical air inlet cavity 711 in communication with the vertical air distribution pipe 73;

[0072] The inner periphery of the disc-shaped air distribution box 72 is provided with an annular air distribution cavity 722 connected to the horizontal air distribution pipe 74, and the upper part of the annular air distribution cavity 722 is connected to a plurality of external air distribution holes 723;

[0073] The outer cloth air hole 723 is a tapered hole, and the diameter of the outer cloth air hole 723 gradually increases from bottom to top.

[0074] Observed from a horizontal cross section, the horizontal air distribution pipe 74 is tangent to the outer periphery of the annular air distribution cavity 722 .

[0075] In this embodiment, a plurality of inner air distribution holes 724 are arranged in an inner circumferential array of the annular air distribution cavity 722 on the disc-shaped air distribution box 72. The inner air distribution holes 724 vertically penetrate the disc-shaped air distribution box 72, and the bottom of the inner air distribution holes 724 is connected to the conical air inlet cavity 711.

[0076] In this embodiment, a plurality of liquid guiding grooves 725 are provided on the upper surface of the disc-shaped air distribution box 72 from the center to the periphery. The plurality of liquid guiding grooves 725 are arranged radially and staggered with the outer air distribution holes 723 and the inner air distribution holes 724.

[0077] From the center to the outer periphery of the disc-shaped air distribution box 72, the width and depth of the liquid guide groove 725 gradually increase.

[0078] In the liquid film or droplet solution of the ammonia nitrogen-containing wastewater sprayed down from the ammonia evaporation tower 3, the part near the inner wall of the ammonia evaporation tower 3 is easy to adhere to the inner wall of the ammonia evaporation tower 3 and fall, and the contact surface between this part of the ammonia nitrogen-containing wastewater and the water vapor flowing upstream is reduced, and the contact collision intensity is significantly weakened (the ammonia nitrogen-containing wastewater forms a liquid film on the inner wall of the ammonia evaporation tower 3, and the water vapor passes through the liquid film in a relatively sliding manner). Compared with other areas, the ammonia in this part of the ammonia nitrogen-containing wastewater is not easy to rise with the water vapor into the concentrated ammonia discharge pipe 31, which will cause the ammonia content in the wastewater at the bottom of the tower to increase. In this embodiment, by setting a uniform gas distribution device 7, while improving the uniform contact between the water vapor and the ammonia nitrogen-containing wastewater, the above-mentioned problem can also be effectively solved.

[0079] The water vapor entering the vertical air distribution pipe 73 can evenly enter each inner air distribution hole 724 after passing through the conical air inlet chamber 711, so that the rising water vapor is more evenly distributed in the ammonia still 3, and promotes the contact of the remaining downstream ammonia nitrogen-containing wastewater; in the annular air distribution chamber 722, the horizontal steam flow entering the horizontal air distribution pipe 74 along the tangent forms a rotating airflow inside, and combines with the rising flow entering the conical air inlet chamber 711 to form water vapor with a rotating rising flow. After passing through the conical outer air distribution holes 723, the water vapor of the rotating rising flow diffuses outward while the vortex rises. This part of the water vapor moves relative to the ammonia nitrogen-containing wastewater on the inner wall of the ammonia still 3 in the horizontal and vertical directions, and strongly collides and contacts with the ammonia nitrogen-containing wastewater on the inner wall of the ammonia still 3. The ammonia in the ammonia nitrogen wastewater is efficiently vaporized to form ammonia vapor, which rises together with the water vapor into the concentrated ammonia discharge pipe 31, thereby reducing the ammonia content in the wastewater at the bottom of the tower and increasing the ammonia content in the concentrated ammonia by-product at the top of the tower, which can improve the treatment effect of the ammonia still 3.

[0080] In addition, a plurality of liquid guiding grooves 725 on the upper surface of the disc-shaped air distribution box 72 can form a diversion effect for the falling ammonia nitrogen-containing wastewater. The structural design of the liquid guiding grooves 725 being high in the middle and low at the outer ends facilitates the ammonia nitrogen-containing wastewater to flow toward the periphery and flow out of the disc-shaped air distribution box 72; the structural design of the liquid guiding grooves 725 being narrow in the middle and wide at the outer ends facilitates the collection of the ammonia nitrogen-containing wastewater on the upper surface of the disc-shaped air distribution box 72.

[0081] Application effect test

[0082] The systems of Example 2 and Example 3 were used to treat the silane and ammonia mixed waste gas generated in the PECVD process of the photovoltaic industry. The waste gas flow rate was 15000Nm 3 / h, of which silane waste gas is about 35% and ammonia is about 42%.

[0083] After the system treatment of Example 2, the concentration of the concentrated ammonia water obtained after condensation in the second condenser 4 was 18 wt %, and the ammonia nitrogen content in the ammonia nitrogen-containing wastewater was 160 mg / L.

[0084] After the system treatment of Example 3, the concentration of the concentrated ammonia water obtained after condensation in the second condenser 4 was 22 wt %, and the ammonia nitrogen content in the ammonia nitrogen-containing wastewater was 127 mg / L.

[0085] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A process for comprehensive treatment of ammonia-containing silane waste gas, characterized in that: The following steps are involved: S1, the mixed waste gas containing silane and ammonia is input into the first condenser for condensation, and silane and ammonia are separated. Ammonia and water vapor in the waste gas are condensed to form ammonia water which enters the ammonia evaporation tower, and the silane waste gas enters the silane combustion tower; S2, nitrogen and compressed air are introduced into the combustion chamber of the silane combustion tower, silane is burned, and the waste gas generated is discharged after passing through the dust collector; S3. The condensed water discharged from the first condenser enters the heat exchange chamber, and is vaporized to form water vapor after heat exchange with the combustion chamber of the silane combustion tower. The water vapor enters the ammonia distillation tower from the lower end, and the ammonia water discharged from the condenser enters the ammonia distillation tower from the upper end, and countercurrently contacts with the water vapor rising in the ammonia distillation tower. The mixture of ammonia vapor and water vapor is discharged from the top of the ammonia distillation tower, and enters the ammonia water storage tank after condensation in the second condenser. The wastewater containing ammonia nitrogen is discharged from the bottom of the ammonia distillation tower.

2. The process for comprehensive treatment of ammonia-containing silane waste gas according to claim 1, characterized in that: The volume ratio of the gas introduced into the silane combustion tower is controlled to be silane waste gas: air: nitrogen = 1:5-20:11-44.

3. A system for comprehensive treatment of ammonia-containing silane waste gas, characterized in that: The mixed waste gas containing silane and ammonia is treated by the process as claimed in claim 1 or 2. The system comprises: a first condenser, a silane combustion tower, a dust collector, an ammonia distillation tower, a second condenser and an ammonia water storage tank.

4. The system for comprehensive treatment of ammonia-containing silane waste gas according to claim 3, characterized in that: The first condenser is a single-pass shell-and-tube condenser. Mixed waste gas containing silane and ammonia enters the tube side of the single-pass shell-and-tube condenser, and condensed water enters the shell layer of the single-pass shell-and-tube condenser. Ammonia and water vapor in the waste gas condense to form ammonia water, which flows out from the lower end of the tube side and enters the ammonia distillation tower through the ammonia water delivery pipe. Silane waste gas is discharged from the upper part of the tube side and enters the silane combustion tower from the bottom through the silane waste gas delivery pipe.

5. The system for comprehensive treatment of ammonia-containing silane waste gas according to claim 4, characterized in that: The silane combustion tower comprises a tower body, a combustion chamber arranged at the bottom of the tower body, a heat exchange chamber located above the combustion chamber, a water distribution pipe arranged in the tower body and connected to the top of the heat exchange chamber, and a steam delivery pipe connected to the bottom of the heat exchange chamber, wherein the steam delivery pipe is connected to the ammonia distillation tower; The combustion chamber and the heat exchange chamber are separated by a heat-conducting partition; The silane waste gas delivery pipe is connected to the bottom of the combustion chamber, the lower side of the combustion chamber is provided with an air intake pipe for delivering nitrogen and compressed air, the upper side of the combustion chamber is connected with an exhaust pipe, and the end of the exhaust pipe is connected to the dust collector.

6. The system for comprehensive treatment of ammonia-containing silane waste gas according to claim 5, characterized in that: The upper part and the lower part of the ammonia evaporation tower are respectively connected with a concentrated ammonia discharge pipe and a diluted ammonia discharge pipe, and the concentrated ammonia discharge pipe is connected to the second condenser and the ammonia water storage tank in sequence; The silane waste gas discharged from the first condenser enters the combustion chamber of the silane combustion tower through the silane waste gas delivery pipe, is mixed with the nitrogen and compressed air entering through the air inlet pipe and burns in the combustion chamber, and the waste gas in the combustion chamber is transported to the dust collector through the exhaust pipe and discharged after dust removal; The condensed water discharged from the first condenser enters the heat exchange chamber through the water distribution pipe, and is vaporized to form water vapor after heat exchange with the silane combustion tower. The water vapor enters the ammonia distillation tower from the lower end through the steam conveying pipe. The ammonia water discharged from the condenser enters the ammonia distillation tower from the upper end through the ammonia water conveying pipe, and countercurrently contacts with the rising water vapor in the ammonia distillation tower. The mixture of ammonia vapor and water vapor is discharged from the top of the ammonia distillation tower, and is conveyed to the second condenser by the concentrated ammonia discharge pipe for condensation, and then enters the ammonia water storage tank. The wastewater containing ammonia nitrogen is discharged from the bottom of the ammonia distillation tower through the dilute ammonia discharge pipe.

7. The system for comprehensive treatment of ammonia-containing silane waste gas according to claim 6, characterized in that: A uniform gas distribution device is provided at the lower part of the ammonia still, and the uniform gas distribution device includes a conical gas inlet box, a disc-shaped gas distribution box connected to the conical gas inlet, a vertical gas distribution pipe connected to the vertical gas inlet at the bottom of the conical gas inlet box, and a horizontal gas distribution pipe connected to the horizontal gas inlet on the side of the disc-shaped gas distribution box; The vertical air distribution pipe and the horizontal air distribution pipe are connected in parallel with the ends of the steam delivery pipe.

8. The system for comprehensive treatment of ammonia-containing silane waste gas according to claim 7, characterized in that: The conical air inlet box has a conical air inlet cavity formed inside thereof and connected to the vertical air distribution pipe; The inner periphery of the disc-shaped air distribution box is provided with an annular air distribution cavity connected with the horizontal air distribution pipe, and the upper part of the annular air distribution cavity is connected with a plurality of external air distribution holes; The outer cloth air holes are conical holes, and the diameters of the outer cloth air holes gradually increase from bottom to top; Observed from a horizontal cross section, the horizontal air distribution pipe is tangent to the outer periphery of the annular air distribution cavity.

9. The system for comprehensive treatment of ammonia-containing silane waste gas according to claim 8, characterized in that: The disc-shaped air distribution box is provided with a plurality of inner air distribution holes in an inner circumferential array of the annular air distribution cavity. The inner air distribution holes penetrate the disc-shaped air distribution box in a vertical direction, and the bottoms of the inner air distribution holes are connected to the conical air inlet cavity.

10. The system for comprehensive treatment of ammonia-containing silane waste gas according to claim 9, characterized in that: The upper surface of the disc-shaped air distribution box is provided with a plurality of liquid guiding grooves extending from the center to the periphery, the plurality of liquid guiding grooves are arranged radially and staggered with the outer air distribution holes and the inner air distribution holes; From the center to the outer periphery of the disc-shaped air distribution box, the width and depth of the liquid guide groove gradually increase.

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