Denitration, dust removal and waste heat recovery integrated system for cement kiln

Abstract

The invention discloses a denitration, dust removal and waste heat recovery integrated system for a cement kiln. Comprising a preheater (2) and a dust, nitrate and waste heat recovery integrated device (9), an inlet of the preheater (2) is connected with an outlet flue of a rotary kiln (1), and the dust, nitrate and waste heat recovery integrated device (9) sequentially comprises a dust removal unit (901), a denitration unit (902) and a waste heat recovery unit (903) from bottom to top; an inlet flue is arranged on the lower portion of the dust, nitrate and waste heat recovery integrated device (9), an outlet flue is arranged on the upper portion of the dust, nitrate and waste heat recovery integrated device (9), and the inlet flue on the lower portion of the dust, nitrate and waste heat recovery integrated device (9) is connected with an outlet flue of the preheater (2). An outlet of the preheater (2) is connected with the ammonia water spraying device (5); an emergency cooling device (6) and a flue gas heater (8) are further arranged on an outlet flue of the preheater (2); and a humidifying and cooling device (11) is arranged at an outlet flue of the dust nitrate waste heat recovery integrated device (9). According to the invention, the lengths of a connecting flue and an external flue between equipment are effectively reduced, the resistance of the system is reduced, the temperature loss is reduced, and the occupied area and the construction cost are saved.

Description

Technical Field

[0001] The present invention belongs to the technical field of kiln tail flue gas treatment in cement industry, and specifically relates to an integrated system for cement kiln denitrification, dust removal and waste heat recovery. Background Art

[0002] The cement industry is the main source of nitrogen oxide (NOx) emissions in my country. Traditional cement kilns use low-nitrogen combustion and selective non-catalytic reduction denitrification (SNCR) technology, which can reduce NOx emissions to a certain extent. However, with increasingly stringent environmental protection standards, existing technologies cannot meet the requirements of ultra-low emissions.

[0003] Selective catalytic reduction (SCR) denitrification technology is an effective technology that can effectively reduce the NOx content in flue gas, and has been widely used in many industries such as electricity, steel and chemical industry. The application of SCR technology in the cement industry can effectively reduce NOx in the flue gas at the kiln tail.

[0004] However, the flue gas from cement kiln tail has the following characteristics: high temperature, generally up to 320~400℃; high dust content, generally up to 80~120g / Nm 3 ; Some cement kilns also take into account the coordinated treatment of garbage, resulting in complex flue gas composition and high heavy metal content; the harsh operating conditions pose a severe test to the stable operation of SCR.

[0005] The traditional high-temperature and high-dust SCR denitrification technology has a large dust content in the flue, which will cause the catalyst to wear and clog, and the heavy metals contained in the cement kiln dust will accelerate the poisoning and deactivation of the catalyst. In addition, the reactor is arranged independently, resulting in a long reactor inlet and outlet flue, inconvenient layout, and large heat loss, which affects the heat recovery effect of the boiler.

[0006] The traditional high-temperature medium-dust SCR denitrification technology has separate arrangements of the dust collector, denitrification reactor, and waste heat boiler, which occupies a large area, makes it difficult to transform old cement kiln production lines, and has a high investment cost. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides an integrated system for denitration, dust removal and waste heat recovery in a cement kiln.

[0008] The technical solution of the present invention is: a cement kiln denitrification, dust removal and waste heat recovery integrated system, including a preheater and a dust waste heat recovery integrated device, the inlet of the preheater is connected to the outlet flue of the rotary kiln, and the dust waste heat recovery integrated device includes a dust removal unit, a denitrification unit, and a waste heat recovery unit from bottom to top; an inlet flue is arranged at the bottom of the dust waste heat recovery integrated device, and an outlet flue is arranged at the top, and the lower inlet flue of the dust waste heat recovery integrated device is connected to the preheater outlet flue; the preheater outlet is connected to an ammonia injection device; an emergency cooling device and a flue gas heater are also arranged on the preheater outlet flue; a humidification and cooling device is arranged at the outlet flue of the dust waste heat recovery integrated device.

[0009] Furthermore, the dust removal unit includes a corona electrode, a dust collecting electrode, an ash hopper, and a water bath ash conveyor; the dust collecting electrode has an anode plate, and the corona electrode has a cathode wire; the corona electrode and the dust collecting electrode are connected to a high voltage power supply, and impact vibration cleaning is adopted.

[0010] Furthermore, the denitration unit comprises a catalyst layer, and the catalyst layer comprises a denitration catalyst and a supporting steel structure thereof; each catalyst layer is provided with a plurality of rake soot blowers and sonic soot blowers.

[0011] Furthermore, the waste heat recovery unit includes a heat exchange unit composed of a plurality of groups of tubes.

[0012] Furthermore, a plurality of nozzles with an aperture of 2-3 mm are arranged on the rake rod of the rake soot blower; the distance between the nozzle of the rake soot blower and the catalyst surface is not greater than 120 mm; and the rake soot blower is connected to an air compressor station.

[0013] Furthermore, the humidification and cooling device is connected to a process water pump and a process water tank.

[0014] Furthermore, the outlet flue of the integrated dust and saltpeter waste heat recovery device is connected to a high-temperature fan and a bag-type dust collector at the end of the kiln; the bag-type dust collector at the end of the kiln is connected to a circulating fan and a raw material vertical mill; and the outlet of the bag-type dust collector at the end of the kiln is connected to a dust collecting fan and a chimney at the end of the kiln.

[0015] Furthermore, the emergency cooling device is provided with a plurality of humidifying and cooling nozzles distributed in a network; the humidifying and cooling nozzles adopt dual-fluid spray guns, and each group of spray guns is provided with a flow regulating device.

[0016] Furthermore, the ammonia water injection device is connected to an ammonia water delivery pump and an ammonia water tank; the ammonia water injection device is provided with a plurality of ammonia water spray guns, and the spray heads are arranged in a mesh shape; the spray heads adopt a dual-fluid spray gun, and each spray gun is provided with a flow regulating device.

[0017] The beneficial technical effects of the present invention are as follows: the flue gas enters the integrated device for recovering dust and waste heat, first passes through the dust removal unit to effectively reduce the dust content in the flue gas of the denitrification unit, then enters the denitrification unit to effectively reduce the clogging of the denitrification catalyst, and finally enters the waste heat recovery unit to recover heat; in the denitrification unit, the unique dust cleaning method can further reduce the risk of catalyst clogging and extend the life of the catalyst; the integrated device consisting of the dust removal unit, the denitrification unit and the waste heat recovery unit, the three process units are arranged in a vertical combination, which effectively reduces the length of the connecting flue and the external flue between the equipment, reduces the resistance of the system, reduces temperature loss, and saves land and construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of an integrated system for denitrification, dust removal and waste heat recovery in a cement kiln.

[0019] In the figure: 1-rotary kiln, 2-preheater, 3-ammonia tank, 4-ammonia delivery pump, 5-ammonia injection device, 6-emergency cooling device, 7-air compression station, 8-flue gas heater, 9-dust and nitrate waste heat recovery integrated device, 901-dust removal unit, 902-denitrification unit, 90201-catalyst layer, 90202-rake soot blower, 90203-sonic soot blower, 903-waste heat recovery unit, 10-water bath ash conveyor, 11-flue humidification and cooling device, 12-process water pump, 13-process water tank, 14-high temperature fan, 15-raw meal vertical mill, 16-circulating fan, 17-kiln tail bag dust collector, 18-kiln tail dust collection fan, 19-chimney. DETAILED DESCRIPTION

[0020] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0021] A brief overview of one or more aspects of the present invention is given below in conjunction with the accompanying drawings to provide a basic understanding of these aspects. These drawings are simplified schematic diagrams that only show the structures related to the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] A cement kiln denitrification, dust removal and waste heat recovery integrated system comprises a preheater 2 and a dust waste heat recovery integrated device 9, wherein the inlet of the preheater 2 is connected to the outlet flue of the rotary kiln 1, and the interior of the dust waste heat recovery integrated device 9 comprises a dust removal unit 901, a denitrification unit 902 and a waste heat recovery unit 903 from bottom to top; an inlet flue is arranged at the lower part of the dust waste heat recovery integrated device 9, and an outlet flue is arranged at the upper part, and the lower inlet flue of the dust waste heat recovery integrated device 9 is connected to the outlet flue of the preheater 2; the outlet of the preheater 2 is connected to an ammonia water injection device; an emergency cooling device 6 and a flue gas heater 8 are also arranged on the outlet flue of the preheater 2; a humidification and cooling device 11 is arranged on the outlet flue of the dust waste heat recovery integrated device 9.

[0023] The flue gas from rotary kiln 1 and preheater 2 has a temperature of about 320~400℃ and a dust content of about 80~120g / Nm 3； The high-temperature flue gas is connected to the integrated dust and nitrate waste heat recovery device 9 through the C1 outlet flue. The flue gas enters through the inlet flue arranged at the bottom of the integrated dust and nitrate waste heat recovery device 9 and is discharged through the outlet flue arranged at the top. On the high-temperature flue in front of the integrated dust and nitrate waste heat recovery device 9, ammonia water is sprayed into the system as a denitrification reducing agent, and an emergency cooling device 6 is also provided.

[0024] After the flue gas passes through the dust removal unit 901 in the integrated device for recovering waste heat from dust and saltpeter 9, most of the dust settles in the ash hopper of the dust removal unit 901. A water bath ash conveyor is also provided at the bottom of the ash hopper to transport the dust in the ash hopper back to the raw material warehouse; the outlet flue of the integrated device for recovering waste heat from dust and saltpeter 9 is provided with a humidification and cooling device 11 to supplement and quickly adjust the outlet flue gas temperature according to the needs of subsequent processes; the flue gas coming out of the integrated device for recovering waste heat from dust and saltpeter 9 is transported to the back-end process through a high-temperature fan 14.

[0025] The dust removal unit 901 includes a corona electrode, a dust collecting electrode, an ash hopper, and a water bath ash conveyor; the dust collecting electrode has an anode plate, and the corona electrode has a cathode wire; the corona electrode and the dust collecting electrode are connected to a high voltage power supply, and impact vibration cleaning is adopted; the angle of the ash hopper is greater than 60°.

[0026] The water bath type dust conveyor comprises an inner shell, an outer shell, a pipeline and a conveying chain; cooling water flows between the inner and outer shells to cool the conveyed dust.

[0027] The denitration unit 902 includes a catalyst layer 90201, and the catalyst layer 90201 includes a denitration catalyst and its supporting steel structure; each catalyst layer 90201 is provided with a plurality of rake soot blowers 90202 and sonic soot blowers 90203; in the denitration unit 902, the number of layers of the catalyst layer 90201 can be set to one or more layers according to the nitrogen oxide content, and a spare layer is reserved; the catalyst uses a high-temperature catalyst.

[0028] The rake soot blower 90202 is provided with a plurality of nozzles on the rake rod, with an aperture of 2 to 3 mm; the distance from the nozzle of the rake soot blower 90202 to the catalyst surface is not greater than 120 mm; the rake soot blower 90202 is connected to the air compressor station 7.

[0029] The compressed air used by the rake soot blower 90202 comes from the air compression station 7. The air compression station 7 is equipped with an air compressor, a filter, a dryer, etc. to ensure that the air dew point is lower than -40°C.

[0030] The compressed air used by the rake soot blower 90202 needs to be heated to above 200°C to prevent the compressed air used for blowing from forming water droplets at the nozzle of the rake soot blower 90202, which will directly damage the catalyst or cause dust to compact and block the catalyst.

[0031] The rake sootblower 90202 is set up with a coordinated blowing operation mode of multiple sootblower: during the sootblower stroke, blowing is started on the outward stroke and stopped on the return stroke. At the same time, the second sootblower starts blowing, shortening the sootblowing time interval and enhancing the blowing effect.

[0032] The waste heat recovery unit 903 includes a heat exchange unit composed of multiple groups of tubes, which recovers heat from high-temperature flue gas and reduces the flue gas temperature. The flue gas temperature after heat recovery is generally 180-200°C.

[0033] The humidifying and cooling device 11 is connected to a process water pump 12 and a process water tank 13 .

[0034] The outlet flue of the integrated dust and saltpeter waste heat recovery device 9 is connected to the high-temperature fan 14 and the bag dust collector 17 at the kiln tail; the bag dust collector 17 at the kiln tail is connected to the circulating fan 16 and the raw material vertical mill 15; the outlet of the bag dust collector 17 at the kiln tail is connected to the dust collection fan 18 and the chimney 19 at the kiln tail.

[0035] When the flue gas at the C1 outlet of the preheater 2 exceeds 420°C, in order to avoid irreversible damage to the catalyst caused by the high-temperature flue gas, the system automatically turns on the emergency cooling device 6; the emergency cooling device 6 is provided with a plurality of humidification and cooling nozzles distributed in a mesh; the humidification and cooling nozzles adopt dual-fluid spray guns, and each group of spray guns is provided with a flow regulating device.

[0036] The system can automatically adjust each group of spray guns according to the flue gas temperature to achieve precise control of the water spraying amount. After the water spraying in the flue gas cools down to less than 400℃, the system automatically stops spraying water to cool down; at the same time, water spraying can also promote the reaction between calcium oxide and sulfur dioxide in the dust, achieving a certain desulfurization effect.

[0037] The ammonia water injection device 5 is connected to the ammonia water delivery pump 4 and the ammonia water tank 3; the ammonia water injection device 5 is provided with a plurality of ammonia water spray guns, and the spray heads are arranged in a mesh shape; the spray heads adopt a dual-fluid spray gun, and each spray gun is provided with a flow regulating device.

[0038] The C1 outlet flue of the preheater 2 is provided with an ammonia water injection device 5, which is provided with a plurality of ammonia water spray guns, and the nozzles are arranged in a mesh shape; the ammonia water adopts a dual-fluid spray gun, and each spray gun is provided with a flow regulating device. The system can automatically adjust each spray gun according to the set total ammonia water spraying amount to achieve precise ammonia spraying, while ensuring the relative stability of the flow and pressure at a single nozzle to ensure the atomization effect.

[0039] The ammonia water comes from the ammonia station. The ammonia station uses 20% ammonia water as a denitrification agent. After the ammonia water is sprayed into the high-temperature flue, it is quickly atomized, evaporated and diluted. The concentration of NH3 is much lower than the explosion limit.

[0040] An emergency cooling device 6 is provided behind the ammonia spray gun at the C1 outlet flue of the preheater 2; the emergency cooling device 6 is used when the flue gas is over-temperature to ensure that the flue gas temperature entering the dust and nitrate waste heat recovery integrated device 9 is not higher than 420°C, avoiding damage to the denitration catalyst.

[0041] A flue humidification and cooling device 11 is arranged at the outlet of the integrated device 9 for recovering waste heat from dust and nitrate to adjust the humidity of the flue gas and control the smoke plume at the tail of the kiln. At the same time, it can reduce the flue gas temperature to ensure that the inlet flue gas temperature of the high-temperature fan does not exceed 220°C, thus avoiding damage to the filter bag of the tail bag dust collector.

[0042] The flue humidifying and cooling device 11 is provided with a plurality of humidifying and cooling nozzles which are distributed in a mesh shape, and the high-temperature flue is divided into a plurality of fine grids; the emergency cooling device 6 and the flue humidifying and cooling device 11 both adopt dual-fluid spray guns, and each group of spray guns is provided with a flow regulating device. The system can automatically adjust the flow of each group of spray guns according to the flue gas temperature, so as to realize the precise control of the water spraying amount, and at the same time ensure the relative stability of the flow and pressure at a single nozzle, so as to avoid the agglomeration and compaction of high-concentration dust caused by the failure of timely atomization of water droplets in the system.

[0043] The operation of the flue humidification and cooling device 11 can adjust the humidity of the flue gas and control the smoke plume at the kiln tail; at the same time, it can reduce the flue gas temperature, ensure that the flue gas temperature at the high-temperature fan inlet does not exceed 220°C, and avoid damage to the filter bags of the tail bag dust collector 17.

[0044] The outlet flue of the integrated dust and saltpeter waste heat recovery device 9 is connected to the high-temperature fan 14 and the bag dust collector 17 at the kiln tail; the bag dust collector 17 at the kiln tail is connected to the circulating fan 16 and the raw material vertical mill 15; the outlet of the bag dust collector 17 at the kiln tail is connected to the dust collection fan 18 and the chimney 19 at the kiln tail.

[0045] When the raw meal vertical mill 15 is put into normal operation, the high-temperature flue gas passes through the high-temperature fan, the raw meal vertical mill, and then passes through the circulating fan 16, the kiln tail bag dust collector 17, the kiln tail dust collection fan 18 and the chimney 19 in sequence to meet the emission standards.

[0046] When the raw meal vertical mill 15 is shut down, the raw meal vertical mill bypass valve is opened, and the high-temperature flue gas is directly discharged through the kiln tail bag filter 17, the kiln tail dust collecting fan 18 and the chimney 19 to meet the discharge standards.

[0047] The integrated device for recovering waste heat from dust and saltpeter 9 consists of a dust removal unit 901, a denitrification unit 902 and a waste heat recovery unit 903. After the flue gas enters the integrated device for recovering waste heat from dust and saltpeter 9, it first passes through the dust removal unit 901. When the dust in the flue gas passes through the high-voltage electric field between the corona electrode and the dust collecting electrode, the gas is electrified and the particles are charged under the action of the strong electric field force around the corona electrode. The charged particles move toward the dust collecting electrode under the action of the electric field force and deposit on the dust collecting electrode, so that they are separated from the gas and collected. After the dust on the surface of the dust collecting electrode is deposited to a certain thickness, in order to ensure the release effect and prevent the dust from re-entering the flue gas, the enriched dust may be removed regularly, and the cleaning is carried out by hammer vibration or electromagnetic vibration.

[0048] The fallen dust enters the ash hopper at the bottom and is finally sent back to the raw material warehouse through a water bath ash conveyor; the water bath ash conveyor is connected to the circulating cooling water to cool the dust discharged from the ash hopper.

[0049] The flue gas after dust removal enters the denitrification unit 902. The dust removal unit 901 can also play a role in flue gas rectification. Under the action of high-temperature catalysts, nitrogen oxides in the flue gas react with NH3 to remove most of the nitrogen oxides in the flue gas, ensuring that the flue gas meets the emission standards; the corresponding number of catalyst layers are set according to the concentration of the catalyst, and one spare layer is reserved.

[0050] Each layer of catalyst is equipped with multiple rake soot blowers 90202 and sonic soot blowers 90203 for combined soot blowing. The rake soot blowers 90202 use compressed air as the air source for soot blowing. The rake rod of the soot blower is equipped with multiple nozzles with a nozzle aperture of 2-3 mm. High-pressure gas blows the inner and outer surfaces of the catalyst through the nozzles; unlike the traditional arrangement, the actual distance from the rake soot blower nozzle to the catalyst surface in the present invention is no more than 120 mm.

[0051] The compressed air used by the rake soot blower 90202 comes from the air compression station 7. The air compression station 7 is equipped with an air compressor, a filter, a dryer, etc. to ensure that the air dew point is lower than -40°C; in particular, the compressed air used by the rake soot blower 90202 needs to be heated to above 200°C to further avoid the compressed air used for blowing from forming water droplets at the nozzle of the rake soot blower 90202, directly damaging the catalyst or causing dust to compact and block the catalyst.

[0052] The rake sootblower 90202 is set up with a coordinated blowing operation mode of multiple sootblower: during the sootblower stroke, blowing is started on the outward stroke and stopped on the return stroke. At the same time, the second sootblower starts blowing, shortening the sootblowing time interval and enhancing the blowing effect.

[0053] The waste heat recovery unit 903 includes a heat exchange unit composed of multiple groups of tubes, which recovers heat from the high-temperature flue gas and generates electricity through a steam turbine to provide energy for the factory. At the same time, it reduces the outlet flue gas temperature of the integrated dust and saltpeter waste heat recovery device 9 to 180~200℃.

[0054] The advantage of this system is that by integrating different functional units and adding corresponding flue regulation functions, there is no need for flues at the inlet and outlet of the denitrification device, and there is no need to set up separate support frames for dust removal and denitrification devices. At the same time, it has the function of regulating the flue gas state. The system is smoother, has less resistance, less heat loss, and saves investment costs and land.

[0055] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A cement kiln denitrification, dust removal and waste heat recovery integrated system, comprising a preheater (2) and a dust and waste heat recovery integrated device (9), wherein the inlet of the preheater (2) is connected to the outlet flue of the rotary kiln (1), and is characterized in that The dust and saltpeter waste heat recovery integrated device (9) includes, from bottom to top, a dust removal unit (901), a denitrification unit (902), and a waste heat recovery unit (903); an inlet flue is arranged at the bottom of the dust and saltpeter waste heat recovery integrated device (9), and an outlet flue is arranged at the top; the inlet flue at the bottom of the dust and saltpeter waste heat recovery integrated device (9) is connected to the outlet flue of the preheater (2); the outlet of the preheater (2) is connected to an ammonia injection device (5); an emergency cooling device (6) and a flue gas heater (8) are also arranged on the outlet flue of the preheater (2); and a humidification and cooling device (11) is arranged on the outlet flue of the dust and saltpeter waste heat recovery integrated device (9).

2. The integrated system for denitrification, dust removal and waste heat recovery of cement kiln according to claim 1 is characterized in that The dust removal unit (901) comprises a corona electrode, a dust collecting electrode, an ash hopper, and a water bath type ash conveyor; the dust collecting electrode has an anode plate, and the corona electrode has a cathode wire; the corona electrode and the dust collecting electrode are connected to a high voltage power supply, and the dust is cleaned by impact vibration.

3. The integrated system for denitrification, dust removal and waste heat recovery of cement kiln according to claim 2 is characterized in that The water bath type ash conveyor comprises an inner shell, an outer shell, a pipeline and a conveying chain; cooling water flows between the inner and outer shells.

4. The integrated system for denitrification, dust removal and waste heat recovery of cement kiln according to claim 1 is characterized in that The denitration unit (902) includes a catalyst layer (90201), and the catalyst layer (90201) includes a denitration catalyst and a supporting steel structure; each catalyst layer (90201) is provided with a plurality of rake soot blowers (90202) and sonic soot blowers (90203).

5. The integrated system for denitrification, dust removal and waste heat recovery of cement kiln according to claim 1 is characterized in that The waste heat recovery unit (903) comprises a heat exchange unit consisting of a plurality of groups of tubes.

6. The integrated system for denitrification, dust removal and waste heat recovery of cement kiln according to claim 4 is characterized in that The rake soot blower (90202) is provided with a plurality of nozzles on the rake rod, with an aperture of 2 to 3 mm; the distance between the nozzle of the rake soot blower (90202) and the catalyst surface is not greater than 120 mm; the rake soot blower (90202) is connected to the air compression station (7).

7. The integrated system for denitrification, dust removal and waste heat recovery of cement kiln according to claim 1 is characterized in that The humidification and cooling device (11) is connected to a process water pump (12) and a process water tank (13).

8. The integrated system for denitrification, dust removal and waste heat recovery of cement kiln according to claim 1 is characterized in that The outlet flue of the integrated device for recovering waste heat from dust and saltpeter (9) is connected to a high-temperature fan (14) and a bag filter (17) at the kiln tail; the bag filter (17) at the kiln tail is connected to a circulating fan (16) and a raw material vertical mill (15); the outlet of the bag filter (17) at the kiln tail is connected to a dust collecting fan (18) and a chimney (19) at the kiln tail.

9. The integrated system for denitrification, dust removal and waste heat recovery of cement kiln according to claim 1 is characterized in that The emergency cooling device (6) is provided with a plurality of humidifying and cooling nozzles distributed in a network; the humidifying and cooling nozzles adopt dual-fluid spray guns, and each group of spray guns is provided with a flow regulating device.

10. The integrated system for denitrification, dust removal and waste heat recovery of cement kiln according to claim 1, characterized in that The ammonia water injection device (5) is connected to the ammonia water delivery pump (4) and the ammonia water tank (3); the ammonia water injection device (5) is provided with a plurality of ammonia water spray guns, and the spray heads are arranged in a mesh shape; the spray heads adopt dual-fluid spray guns, and each spray gun is provided with a flow regulating device.

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