Fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function

Abstract

The invention provides a fluidized bed iron-carbon micro-electrolysis reactor with an enhanced denitrification function, and relates to the technical field of sewage treatment, the fluidized bed iron-carbon micro-electrolysis reactor comprises a reaction tower body, a water inlet header pipe and an air lifter; a bearing plate is arranged in the reaction tower body, and a crystal discharge header pipe is arranged at the bottom of the iron-carbon composite fluidized filler and penetrates through the reaction tower body. The iron-carbon micro-electrolysis reactor has the beneficial effects that the iron-carbon composite fluidized filler in the reaction tower body of the reactor can be in a fluidized state under the action of lifting water flow of the air lifter, so that the mass transfer and exchange rate is increased, and the time required by an iron-carbon micro-electrolysis reaction is greatly shortened, so that the volume and the construction cost of the reactor are reduced; meanwhile, the filler particles are always in an irregular motion state in a fluidized state, so that the problem of hardening of the filler particles in the reactor is avoided; the iron-carbon composite fluidized filler comprises sodium chloride modified zeolite filler particles, and the sewage treatment efficiency of the reactor can be greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function. Background Art

[0002] Iron-carbon micro-electrolysis is generally used in conjunction with Fenton oxidation and coagulation sedimentation processes. It has a good treatment effect on difficult-to-degrade organic wastewater and heavy metal wastewater, and is widely used in wastewater treatment in the pharmaceutical, printing and dyeing, chemical fiber, leather and other industries. The application of iron-carbon micro-electrolysis in the field of sewage treatment has the following advantages: 1) The process is simple to operate and has low treatment costs; 2) It has a good effect on the treatment of difficult-to-degrade wastewater, which can effectively reduce the toxicity of wastewater and improve the biodegradability of wastewater; 3) It has a good removal effect on organic matter, phosphorus, and heavy metal pollutants. However, the traditional micro-electrolysis technology also shows some obvious shortcomings in treating industrial wastewater, which are mainly manifested as follows: 1) The traditional iron-carbon micro-electrolysis tower is generally a fixed-bed reactor with fillers, which has the problems of insufficient mixing and mass transfer and low reaction efficiency. The hydraulic retention time of the reactor generally requires more than 2 hours; 2) The iron-carbon micro-electrolysis fillers of the traditional iron-carbon micro-electrolysis tower are prone to compaction and passivation. When such problems occur, the treatment efficiency of the reactor decreases or even fails, and regeneration or cleaning is time-consuming and labor-intensive; 3) The iron-carbon fillers of the traditional iron-carbon micro-electrolysis tower are accumulated at the bottom of the reactor. In order to avoid compaction, in addition to the air required for the redox reaction, a large amount of air must be provided to flush the fillers, resulting in high energy consumption. The aeration volume of the traditional iron-carbon micro-electrolysis tower is generally 5m 3 Air / m 3 Sewage; 4) Traditional iron-carbon micro-electrolysis reactors have good removal effects on organic matter, phosphorus, and heavy metal pollutants, but nitrogen pollutants are also one of the main pollutants in wastewater. Traditional iron-carbon micro-electrolysis reactors have poor removal effects on nitrogen pollutants, and the general nitrogen removal rate is less than 10%. Summary of the invention

[0003] In view of this, the present invention provides a fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function, comprising a reaction tower body, a water inlet main pipe and an air lift;

[0004] A support plate is provided in the reaction tower body, the support plate is provided with a plurality of water-permeable holes, a plurality of water distributors are provided at the bottom of the support plate, and all the water distributors are connected to the lower end of the water inlet main pipe;

[0005] An iron-carbon composite fluidized filler is piled on the support plate, a crystal row main pipe is provided at the bottom of the iron-carbon composite fluidized filler, and the crystal row main pipe passes through the reaction tower body;

[0006] A lateral flow ramp is provided above the iron-carbon composite fluidized filler, a water collection main channel is provided above the lateral flow ramp, one end of the water collection main channel extends out of the reaction tower body, and the other end is connected to an air lifter, the air lifter is connected to the upper end of the water inlet main pipe; the air inlet of the air lifter is connected to a blower; the upper end of the water inlet main pipe is also provided with a water inlet;

[0007] The water inlet main pipe is used to input the untreated sewage from the water distributor upward into the reaction tower body, and react with the iron-carbon composite fluidized filler in the reaction tower body to produce crystals. The lateral flow diverter is used to guide the generated crystals downward to make them settle on the support plate. The crystal discharge main pipe is used to discharge the crystals on the support plate. The water collection main channel is used to discharge part of the water treated by the iron-carbon composite fluidized filler. The air lift is used to blow the remaining water in the water collection main channel into the water inlet main pipe under the action of the blower, so as to increase the flow rate and oxygen content of the water in the water inlet main pipe, so that the iron-carbon composite fluidized filler reaches a fluidized state.

[0008] Furthermore, the iron-carbon composite fluidized filler includes iron-carbon particle balls and sodium chloride modified zeolite particle balls.

[0009] Furthermore, the lateral flow incline device comprises a plurality of flow incline tubes arranged obliquely relative to the vertical direction, all the flow incline tubes are arranged in parallel, and the side walls of adjacent flow incline tubes are fixedly connected.

[0010] Furthermore, an air lift trough is provided on the top side wall of the reaction tower body, the air lift trough is connected to the top of the water inlet main pipe, the air lift trough is connected to the water collection main channel, and the air lift is arranged in the water collection main channel.

[0011] Furthermore, a partition plate is provided in the air lift tank, and the partition plate divides the cavity in the air lift tank into a water storage chamber and a reflux chamber. The water collection main channel is connected to the water storage chamber, the air lift is located in the water storage chamber, and a reflux hole is provided on the partition plate.

[0012] Furthermore, an adjustable weir gate is provided on the reflux hole, and the adjustable weir gate is used to adjust the opening of the reflux hole, thereby adjusting the reflux flow rate of the water body in the air lift tank.

[0013] Furthermore, the particle size of the iron-carbon composite fluidized filler is 0.5-0.6 mm.

[0014] Furthermore, the lower end of the water inlet main pipe passes through the reaction tower body and extends into the reaction tower body, a plurality of water distribution branch pipes are connected to the water inlet main pipe, and the water distributor is connected to the end of the water distribution branch pipe.

[0015] Furthermore, a plurality of water collection channels are provided above the lateral flow deflector, and all the water collection channels are connected to the main water collection channel.

[0016] Furthermore, a plurality of crystal discharge branch pipes are vertically connected to the crystal discharge main pipe, and crystal discharge holes are distributed on the crystal discharge branch pipes and the crystal discharge main pipe. A crystal discharge port is provided at one end of the crystal discharge main pipe, and the crystal discharge port passes through the reaction tower body. A crystal discharge valve is also provided on the crystal discharge port, and the crystal discharge valve is opened at a fixed time to discharge the accumulated crystals in the crystal discharge main pipe.

[0017] The beneficial effects of the fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function of the present invention are:

[0018] 1. The reaction tower of the reactor is equipped with an iron-carbon composite fluidized filler, and the air lift can cause the water to flow upward and pass through the iron-carbon composite fluidized filler, making it in a fluidized state. In the fluidized state, the filler particles are always in an irregular motion state, which completely avoids the problems of filler compaction, passivation and even deactivation that may occur in fixed bed fillers in traditional iron-carbon micro-electrolysis reactors.

[0019] 2. The mass transfer exchange rate and reaction rate of the iron-carbon composite fluidized filler in the fluidized state of the reactor's reaction tower are greatly increased, which can greatly reduce the time required for the iron-carbon micro-electrolysis reaction. The hydraulic retention time of the fluidized bed iron-carbon micro-electrolysis tower is only 37.5% of that of the traditional iron-carbon micro-electrolysis reactor. Therefore, the volume of the reactor is also only 37.5% of that of the traditional iron-carbon micro-electrolysis reactor, which greatly reduces the construction cost of the reactor.

[0020] 3. Sodium chloride-modified zeolite filler particles are added to the iron-carbon composite fluidized filler. The adsorption of ammonia nitrogen by sodium chloride-modified zeolite filler particles can reach more than 80%. Therefore, the nitrogen pollutant removal efficiency of the fluidized bed iron-carbon micro-electrolysis tower is increased by 70% compared with the traditional iron-carbon micro-electrolysis reactor.

[0021] 4. The air consumption of the reactor is 3m 3 Air / m 3 For sewage, the air consumption is only 60% of that of the traditional iron-carbon micro-electrolysis tower, and the air pressure is only 30% of that of the traditional iron-carbon micro-electrolysis tower. Therefore, the energy consumption required for aeration is reduced by 82%.

[0022] 5. The iron-carbon composite fluidized filler of the reactor does not have the problems of compaction, blockage, passivation, failure, etc., so there is no need to regenerate or clean the filler, which reduces the consumption of manpower and material resources. The fluidized bed iron-carbon micro-electrolysis tower only needs to regularly replenish the filler and discharge the bottom crystals, which is simple to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic cross-sectional view of the overall structure of a fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to an embodiment of the present invention.

[0024] Figure 2 It is a schematic diagram of the connection structure of the water inlet main pipe and the water distributor of a fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to an embodiment of the present invention.

[0025] Figure 3 It is a schematic diagram of the connection structure of a crystal row branch pipe and a crystal row main pipe of a fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to an embodiment of the present invention.

[0026] Figure 4 It is a schematic diagram of the connection structure of a water collection main channel and an air lift tank of a fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to an embodiment of the present invention.

[0027] Figure 5 yes Figure 4 Schematic diagram of the internal structure of the air lift tank.

[0028] In the above figure: 1-reaction tower body, 2-water inlet main pipe, 3-water distribution branch pipe, 4-water distributor, 5-crystal discharge main pipe, 6-crystal discharge branch pipe, 7-crystal discharge port, 8-support plate, 9-lateral flow deflector, 10-water collection channel, 11-water collection main channel, 12-water collection tank, 13-air lift tank, 14-air inlet, 15-air lift, 16-reflux chamber, 17-adjustable weir gate, 18-water inlet, 19-water outlet, 20-iron-carbon composite fluidized filler, 21-crystal. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0030] Please refer to Figures 1 to 5 The present invention provides a fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function, comprising a reaction tower body 1, a water inlet main pipe 2 and an air lift 15;

[0031] The reaction tower body 1 is provided with a support plate 8, the support plate 8 is provided with a plurality of water-permeable holes, the bottom of the support plate 8 is provided with a plurality of water distributors 4, and all water distributors 4 are connected to the lower end of the water inlet main pipe 2;

[0032] The support plate 8 is stacked with an iron-carbon composite fluidized filler 20. A crystal discharge main pipe 5 is provided in the middle, and the crystal discharge main pipe 5 passes through the reaction tower body 1.

[0033] A lateral flow diverter 9 is provided above the iron-carbon composite fluidized filler 20, and a water collection main channel 11 is provided above the lateral flow diverter 9. One end of the water collection main channel 11 extends out of the reaction tower body 1, and the other end is an air lift. The end of one end of the water collection main channel 11 extending out of the reaction tower body 1 is a water outlet 19, and the air lift 15 is connected to the upper end of the water inlet main pipe 2; the air inlet 14 of the air lift 15 is connected to the blower; and a water inlet 18 is also provided at the upper end of the water inlet main pipe 2.

[0034] The water inlet main pipe 2 is used to input the untreated sewage from the water distributor 4 upward into the reaction tower body 1, and react with the iron-carbon composite fluidized filler 20 in the reaction tower body 1 to produce crystals 21. The lateral flow diverter 9 is used to guide the generated crystals downward to make them settle on the support plate 8. The crystal discharge main pipe 5 is used to discharge the crystals 21 on the support plate 8. The water collection main channel 11 is used to discharge part of the water treated by the iron-carbon composite fluidized filler 20. The air lift 15 is used to blow the remaining water in the water collection main channel 11 into the water inlet main pipe 2 under the action of the blower, so as to increase the flow rate and oxygen content of the water in the water inlet main pipe 2, so that the iron-carbon composite fluidized filler 20 reaches a fluidized state.

[0035] Furthermore, the iron-carbon composite fluidized filler 20 includes iron-carbon particle balls and sodium chloride-modified zeolite particle balls.

[0036] Furthermore, the lateral flow diverter 9 includes a plurality of flow diverter tubes inclined relative to the vertical direction, all the flow diverter tubes are arranged in parallel, and the side walls of adjacent flow diverter tubes are fixedly connected. In this embodiment, the flow diverter tubes are all hexagonal tubes, and the upper and lower ends of the lateral flow diverter 9 are both honeycomb structures.

[0037] Furthermore, the top side wall of the reaction tower body 1 is also provided with an air lift groove 13, the air lift groove 13 is connected to the top of the water inlet main pipe 2, the air lift groove 13 is connected to the water collection main channel 11, and the air lift 15 is arranged in the air lift groove 13.

[0038] Furthermore, a water collecting trough 12 is provided at the edge of the air lift trough 13, and the air lift trough 13 is connected to the water collecting main channel 11 through the water collecting trough 12. A partition plate is provided in the air lift trough 13, and the partition plate divides the cavity in the air lift trough 13 into a water storage chamber and a reflux chamber 16. The water collecting main channel 11 is connected to the water storage chamber, and the air lift 15 is located in the water storage chamber. A reflux hole is provided on the partition plate, and the reflux chamber 16 is connected to the upper end of the water inlet main pipe 2 and the water inlet 18.

[0039] Furthermore, an adjustable weir gate 17 is provided on the reflux hole, and the adjustable weir gate 17 is used to adjust the opening of the reflux hole, thereby adjusting the reflux flow rate of the water body in the air lift tank 13.

[0040] Furthermore, the particle size of the iron-carbon composite fluidized filler 20 is 0.5-0.6 mm.

[0041] Furthermore, the lower end of the water inlet main pipe 2 passes through the reaction tower body 1 and extends into the reaction tower body 1 . A plurality of water distribution branch pipes 3 are connected to the water inlet main pipe 2 . The water distributor 4 is connected to the end of the water distribution branch pipe 3 .

[0042] Furthermore, a plurality of water collecting channels 10 are provided above the lateral flow deflector 9 , and all the water collecting channels 10 are connected to the main water collecting channel 11 .

[0043] Furthermore, a plurality of crystal discharge branch pipes 6 are vertically connected to the crystal discharge main pipe 5, and crystal discharge holes are distributed on the crystal discharge branch pipes 6 and the crystal discharge main pipe 5. A crystal discharge port 7 is provided at one end of the crystal discharge main pipe 5, and the crystal discharge port 7 passes through the reaction tower body 1. A crystal discharge valve is also provided on the crystal discharge port 7, and the crystal discharge valve is opened at a fixed time to discharge the aggregated crystals 21 in the crystal discharge main pipe 5.

[0044] The working process of the present invention is as follows: the wastewater to be treated enters the reflux chamber 16 through the water inlet 18, and after mixing with the reflux water in the reflux chamber 16, it passes through the water inlet main pipe 2, the water distribution branch pipe 3 and the water distributor 4 to form a uniform rising water flow field. The rising flow rate of the water flow is controlled at 30 mm / s. At this time, the iron-carbon composite filler 20 expands under the drive of the water flow and enters a fluidized state to form an iron-carbon filler fluidized bed. At this time, the iron-carbon composite fluidized filler 20 is evenly distributed in the bed and moves irregularly in a small range. At the same time, the filler particles of the iron-carbon composite fluidized filler 20 are mixed with the filler particles, The collision and friction between the filler particles and the reactor, and between the fluid and the reactor increase, and the exchange rate and reaction rate are greatly increased. The components of the iron-carbon composite fluidized filler 20 are iron-carbon particle balls and sodium chloride modified zeolite particle balls, and the particle size is controlled to be 0.5-0.6mm. In addition to the galvanic cell reaction, redox reaction, flocculation and coprecipitation that occur in the traditional iron-carbon micro-electrolysis process, the sodium chloride modified zeolite in the iron-carbon composite fluidized filler 20 can also effectively adsorb and remove ammonia nitrogen in the wastewater, and the adsorption rate of ammonia nitrogen can reach more than 80%. Due to the chemical structure of the zeolite crystal, it has the characteristics of high porosity, large specific surface area, high-efficiency selective adsorption, acid resistance, heat resistance, radiation resistance, etc. The adsorption capacity of sodium chloride modified zeolite for ammonia nitrogen can be as high as 0.8mg / g zeolite. In addition to being an adsorption medium, zeolite will no longer undergo adsorption after adsorption saturation. At this time, it will exist as a crystallization nucleus in the fluidized bed. The iron in the iron-carbon composite fluidized filler 20 produces Fe in the micro-electrolysis anode reaction. 2+ , Fe 2+ In an aerobic environment, an oxidation reaction will occur to generate OH· and Fe 3+ , Fe3+ FeOOH crystals are generated on the surface of zeolite crystal nuclei. Since the environment of iron-carbon micro-electrolysis is an acidic environment, the crystal generation rate is relatively slow and will only occur after the adsorption saturation of the zeolite. As the crystals gradually grow, the rising speed of the water flow at this time is not enough to make them reach a fluidized state, so they sink and accumulate on the supporting plate 8. The crystals are regularly discharged through the crystal discharge main pipe 5, the crystal discharge branch pipe 6 and the crystal discharge port 7, and the iron-carbon composite fluidized filler 20 is regularly replenished from the top of the reaction tower body 1 to make up for the loss of the iron-carbon composite fluidized filler 20. The wastewater purified by the iron-carbon micro-electrolysis reaction rises and enters the top of the reaction tower body 1. A lateral flow ramp 9 is arranged above the fluidized bed of the micro-electrolysis tower. The lateral flow ramp 9 utilizes the principle of "shallow sedimentation" to make the iron-carbon composite fluidized filler 20 and the generated crystals 21 flow along the inclined inner wall surface of the lateral flow ramp 9 and flow back into the fluidized bed, thereby preventing the carbon composite fluidized filler 20 from being carried away by the water flow and preventing the crystals 21 from overflowing. After the wastewater flows through the inclined tube sedimentation area, the clean water is collected by the water collection channel 10, which can ensure a good fluidized state in the fluidized bed reactor. After the clean water is collected by the water collection channel 10, it converges into the water collection main channel 11, and a part of it flows through the outlet 19. The other part enters the air lift tank 13, and air is introduced into the air lift tank through the air lift 15. The main principle of the air lift 15 is to introduce air into the bottom thereof. Due to the small density of air, a pressure difference is generated, and the reflux water at the bottom of the air lift is lifted to a high place under the action of pressure. In the process of lifting the reflux water, the oxygen in the air will also dissolve into the reflux water, thereby realizing the oxygenation of the reflux water. The reflux water of the air lift tank 13 flows into the reflux chamber 16, and an adjustable weir gate 17 is arranged in the reflux chamber 16. The flow rate of the reflux water can be adjusted by adjusting the height of the weir gate 17, thereby controlling the rising flow rate in the reactor.

[0045] In this document, the directional words such as front, back, top, and bottom are defined by the positions of the components in the drawings and the positions of the components relative to each other, and are only for the sake of clarity and convenience in expressing the technical solution. It should be understood that the use of the directional words should not limit the scope of protection claimed in this application.

[0046] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function, characterized in that: It includes a reaction tower body, a water inlet main pipe and an air lift; A support plate is provided in the reaction tower body, the support plate is provided with a plurality of water-permeable holes, a plurality of water distributors are provided at the bottom of the support plate, and all the water distributors are connected to the lower end of the water inlet main pipe; An iron-carbon composite fluidized filler is piled on the support plate, a crystal row main pipe is provided at the bottom of the iron-carbon composite fluidized filler, and the crystal row main pipe passes through the reaction tower body; A lateral flow ramp is provided above the iron-carbon composite fluidized filler, a water collection main channel is provided above the lateral flow ramp, one end of the water collection main channel extends out of the reaction tower body, and the other end is connected to an air lifter, the air lifter is connected to the upper end of the water inlet main pipe; the air inlet of the air lifter is connected to a blower; the upper end of the water inlet main pipe is also provided with a water inlet; The water inlet main pipe is used to input the untreated sewage from the water distributor upward into the reaction tower body, and react with the iron-carbon composite fluidized filler in the reaction tower body to produce crystals. The lateral flow diverter is used to guide the generated crystals downward to make them settle on the support plate. The crystal discharge main pipe is used to discharge the crystals on the support plate. The water collection main channel is used to discharge part of the water treated by the iron-carbon composite fluidized filler. The air lift is used to blow the remaining water in the water collection main channel into the water inlet main pipe under the action of the blower, so as to increase the flow rate and oxygen content of the water in the water inlet main pipe, so that the iron-carbon composite fluidized filler reaches a fluidized state.

2. The fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to claim 1, characterized in that: The iron-carbon composite fluidized filler comprises iron-carbon particle balls and sodium chloride modified zeolite particle balls.

3. The fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to claim 1, characterized in that: The lateral flow incline device comprises a plurality of flow incline tubes arranged obliquely relative to the vertical direction, all the flow incline tubes are arranged in parallel, and the side walls of adjacent flow incline tubes are fixedly connected.

4. The fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to claim 1, characterized in that: The top side wall of the reaction tower body is also provided with an air lift groove, the air lift groove is connected to the top of the water inlet main pipe, the air lift groove is connected to the water collection main channel, and the air lift is arranged in the air lift groove.

5. The fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to claim 4, characterized in that: A partition plate is provided in the air lift tank, and the partition plate divides the cavity in the air lift tank into a water storage cavity and a reflux cavity. The water collection main channel is connected to the water storage cavity. The air lift is located in the water storage cavity, and a reflux hole is provided on the partition plate.

6. The fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to claim 5, characterized in that: The reflux hole is also provided with an adjustable weir gate, and the adjustable weir gate is used to adjust the opening of the reflux hole, thereby adjusting the reflux flow rate of the water body in the air lift tank.

7. The fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to claim 1, characterized in that: The particle size of the iron-carbon composite fluidized filler is 0.5-0.6 mm.

8. The fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to claim 1, characterized in that: The lower end of the water inlet main pipe passes through the reaction tower body and extends into the reaction tower body. The water inlet main pipe is connected to a plurality of water distribution branches, and the water distributor is connected to the end of the water distribution branch pipe.

9. The fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to claim 1, characterized in that: A plurality of water collection channels are also arranged above the lateral flow deflector, and all the water collection channels are connected to the main water collection channel.

10. The fluidized bed iron-carbon micro-electrolysis reactor with enhanced denitrification function according to claim 1, characterized in that: A plurality of crystal discharge branch pipes are vertically connected to the crystal discharge main pipe, and crystal discharge holes are distributed on the crystal discharge branch pipes and the crystal discharge main pipe. A crystal discharge port is provided at one end of the crystal discharge main pipe, and the crystal discharge port passes through the reaction tower body. A crystal discharge valve is also provided on the crystal discharge port, and the crystal discharge valve is opened at a fixed time to discharge the accumulated crystals in the crystal discharge main pipe.

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