Dredging construction method for harbor channel in soil containing hydrogen sulfide

Abstract

The invention discloses a construction method for dredging a harbor channel containing hydrogen sulfide soil, including: step 1, installing hydrogen sulfide detectors at different positions on a trailing suction hopper ship, partially closing the hatch of the mud tank with a cloth film, and arranging a high-power axial flow fan; step 2, analyzing the main wind direction, the secondary dominant wind direction and its wind speed according to the wind rose diagram of the harbor channel area, and formulating a trailing suction hopper ship construction plan according to the wind direction and wind speed; step 3, adjusting the upward angle of the rake lip to separate the rake lip from the mud surface at the bottom of the channel, using high-pressure water flushing to first break up the mud at the bottom of the channel, so that hydrogen sulfide first volatilizes and dissolves in the water; step 4, adopting a full-tank replacement construction method to suck the mud at the bottom of the channel into the mud tank of the trailing suction hopper ship, and turning on the high-power axial flow fan during the construction process to reduce the concentration of hydrogen sulfide on the ship in the air; step 5, when the mud tank is full, the trailing suction hopper ship is driven to the designated mud dumping area to dump mud. The invention effectively solves the problems of hydrogen sulfide toxic gas protection, collection, and discharge.

Description

Technical Field

[0001] The present invention relates to the technical field of waterway dredging construction, and more specifically, to a method for dredging a harbor waterway in soil containing hydrogen sulfide. Background Art

[0002] Hydrogen sulfide gas is a highly toxic gas that can easily cause death. Its toxicity is 5 to 6 times that of carbon monoxide. 2 When S is inhaled into the human body, it will be transported to various organs of the human body through the respiratory tract, lungs, and blood. First, it will irritate the respiratory tract, dull the sense of smell, cause coughing, and in severe cases, burns; it will sting the eyes and cause blindness in severe cases; it will stimulate the nervous system, causing dizziness, loss of balance, and difficulty breathing; it will accelerate the heartbeat, and in severe cases, the heart will be deprived of oxygen and die.

[0003] At present, the excavation of soil containing hydrogen sulfide gas by a trailing suction hopper has always been a difficult problem in the dredging industry. The trailing suction hopper is equipped with a rake head excavation machine and a mud suction device. During construction, the rake arm is placed underwater to a certain depth so that the rake head contacts the mud surface. Through the propulsion device on the ship, the trailing suction hopper is towed forward with the rake head during navigation to rake and excavate the mud and sand in the underwater soil layer. The excavated mud is then sucked from the suction port of the rake head through the suction action of the mud pump, and the mud is loaded into the mud tank of the trailing suction hopper itself through the discharge end of the mud pump. When the cabin is full of mud and sand, the dredging is stopped, the rake is started to sail to the designated mud dumping area to dump mud, and then return to construction. Since the trailing suction hopper is a dredging ship that directly loads the dredged materials into the cabin and transports them to the designated location for dumping, its open mud tank structure is bound to cause the diffusion of hydrogen sulfide gas, and the hydrogen sulfide concentration on the deck is much higher than the safety limit, so conventional trailing suction hoppers have technical problems such as being unable to operate at all. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0005] Another object of the present invention is to provide a method for dredging a harbor channel in soil containing hydrogen sulfide, which effectively solves the problems of protection, collection, and discharge of toxic hydrogen sulfide gas.

[0006] In order to achieve these purposes and other advantages according to the present invention, a method for dredging a harbor channel in soil containing hydrogen sulfide is provided, comprising:

[0007] Step 1: Install hydrogen sulfide detectors at different positions on the hopper, weld keels around and above the mud tank of the hopper, and partially seal the hatch of the mud tank with a cloth film set on the keel. The sealed area includes the front sealed area in the 12-20m section near the side of the hopper's driving platform and the rear sealed area in the 10m area of ​​the rear section of the mud tank. The middle area is open and equipped with a high-power axial flow fan. A high-power fan is installed in the living cabin of the hopper, and a high-power axial flow fan is installed in the main engine room, pump room, and repair room of the hopper. The mud door hole on the mud tank deck is filled with an expansion foam agent, and a cover plate is installed outside the mud door hole to prevent hydrogen sulfide gas from being released outward through the mud door hole on the mud tank deck;

[0008] Step 2: Analyze the main wind direction, secondary dominant wind direction and wind speed according to the wind rose diagram of the harbor channel area, and formulate a trailing suction hopper construction plan according to the wind direction and speed;

[0009] Step 3: Fill the cabin with water before construction, take the highest overflow, open the rake head for high-pressure water flushing, adjust the rake lip upward angle to separate the rake lip from the mud surface at the bottom of the channel, use high-pressure water flushing to break up the mud at the bottom of the channel first, so that the hydrogen sulfide will evaporate and dissolve into the water first;

[0010] Step 4: Use the full tank replacement construction method to suck the mud at the bottom of the channel into the mud tank of the trailing suction hopper ship. During the construction process, turn on the high-power axial flow fan to reduce the concentration of hydrogen sulfide in the air on board;

[0011] Step 5: When the mud tank is full, drive the suction hopper to the designated mud dumping area to dump the mud.

[0012] Preferably, the construction plan of the trailing suction hopper vessel is formulated according to the wind direction and wind speed, including:

[0013] When there is no wind, increase the speed by 2.5 to 3 knots to reduce the time that hydrogen sulfide gas accumulates on the ship;

[0014] When there is no wind, head wind or cross wind, carry out normal construction, pay attention to the hydrogen sulfide detector in the stern engine room, and keep the high-power axial flow fan turned on.

[0015] Preferably, when the mud at the bottom of the channel is sucked into the mud tank of the drag suction vessel, if the hydrogen sulfide detector continues to alarm, low-concentration external discharge construction is adopted. During the construction, the drag head is turned on with high-pressure water flushing, and the drag lip is raised to adjust the angle so that the high-pressure water flushing first breaks up and dilutes the mud at the bottom of the channel, and then the diluted mud is sucked in with a mud pump and discharged directly overboard without loading. The high-power axial flow fans in the main engine room and the pump room are turned on for timely exhaust. After the hydrogen sulfide detector detects that the hydrogen sulfide gas concentration returns to normal, the mud loading construction of step four is continued.

[0016] Preferably, the low alarm point of the hydrogen sulfide detector is set at 15 mg / m 3 The high alarm point is set at 30mg / m 3.

[0017] Preferably, during construction, if it is found that the hydrogen sulfide gas has reached the low alarm point of the hydrogen sulfide detector, the ship will immediately issue a ship-wide alarm and require all on-duty personnel to carry emergency respirators. At the same time, the ship will adjust the position of the ship according to the wind direction to keep the bridge, cabins, and main engine room upwind. If the hydrogen sulfide detector continues to alarm and the concentration continues to increase, work will be stopped immediately. If the concentration decreases, construction will continue and real-time monitoring will be maintained. If it is found that the hydrogen sulfide gas has reached the high alarm point of the hydrogen sulfide detector, the ship will immediately issue a ship-wide alarm and require all on-duty personnel to carry emergency respirators. The driver should immediately stop construction and drive the trailing suction hopper away from the construction area for ventilation.

[0018] Preferably, when the hopper vessel is on its way to the mud dumping area, the vessel uses mechanical and natural ventilation to promptly complete the ventilation work inside the cabin. After ventilation, the ship's dedicated detection personnel use handheld detection equipment to go to each cabin for detection. After there is no risk of hydrogen sulfide, normal mud dumping operations can be started;

[0019] During the mud dumping process, the vessel should be kept dumping against the wind or across the wind to reduce the release of hydrogen sulfide generated during mud dumping.

[0020] Preferably, a front baffle and a rear baffle are provided in the mud tank of the trailing suction hopper, and the heights of the front baffle and the rear baffle are both lower than the height of the top of the mud tank; a first plate body is arranged at intervals behind the front baffle, and the height of the first plate body is the same as the height of the top of the mud tank, and the lower end of the first plate body is higher than the bottom of the mud tank, and the edge of the membrane portion of the front closed area is connected to the upper end of the first plate body, and the water in the front closed area overflows from the top of the front baffle and flows along the gap between the front baffle and the first plate body to the middle area; a second plate body is arranged at intervals in front of the rear baffle, and the height of the second plate body is the same as the height of the top of the mud tank, and the lower end of the second plate body is higher than the bottom of the mud tank, and the edge of the membrane portion of the rear closed area is connected to the upper end of the second plate body, and the water in the rear closed area overflows from the top of the rear baffle and flows along the gap between the rear baffle and the second plate body to the middle area;

[0021] The mud pump outlet of the trailing suction hopper is arranged in the front closed area and the rear closed area;

[0022] The overflow well of the mud tank is arranged in the middle area, and the middle area is also provided with an inverted V-shaped cover plate, the lower end of the cover plate is respectively connected to the first plate body and the second plate body, and a plurality of leakage holes are arranged on the edge of the lower end of the cover plate. A slag powder barrel is arranged above the middle area, and a discharge port is arranged at the bottom of the slag powder barrel. An electric valve is arranged at the discharge port to control the slag powder barrel to discharge slag powder into the middle area, so that the slag powder reacts with the hydrogen sulfide-containing water body overflowing into the middle area to form sulfide precipitation.

[0023] The present invention includes at least the following beneficial effects: targeted ship modification scheme and construction process, effectively solves the problems of protection, collection and discharge of hydrogen sulfide toxic gas, is easy to operate, economical and practical, enables the trailing suction hopper ship to operate normally, improves the applicability of the trailing suction hopper ship, and has significant economic benefits.

[0024] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the side structure of the trailing suction hopper according to an embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram of the front structure of the mud tank described in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0028] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0029] The project is located in Dar es Salaam Port, Tanzania (hereinafter referred to as Dar Port). The project includes widening, deepening and dredging of the outer channel, channel entrance, turning circle and inner channel area.

[0030] According to the analysis of drilling exploration data provided by the owner, the soil containing hydrogen sulfide is mainly silt, containing shell fragments and organic matter. The moisture content of the mud surface is 100%, the moisture content 10m below the mud surface is 50%, the organic matter content is 8-16%, the undrained shear strength 2m below the mud surface is 2kpa, and the undrained shear strength 10m below the mud surface is 15kpa.

[0031] At present, the areas where the soil is known to contain hydrogen sulfide are the outer channel and the inner channel. According to the understanding of the contractor who had constructed on site, similar conditions also occurred during their construction, but they were constructed by grab boat groups, with little disturbance and no large-scale outbreak. The soil samples were sent to the laboratory, and no excessive hydrogen sulfide content was found, so no treatment was done. After the on-site investigation, it can be preliminarily judged that the hydrogen sulfide in this area is formed by the decomposition of animal remains and is dispersed in various parts of the construction soil layer. The mud layer of the outer channel is thin and open without shelter, and the ventilation conditions are good. Although there are hydrogen sulfide alarm values ​​during construction, the monitored hydrogen sulfide gas concentration values ​​are all within the safe range. Hydrogen sulfide-containing soil is widely distributed in the inner channel. This area is located in a semi-enclosed area in the port, surrounded by urban buildings, with low wind force and poor gas diffusion conditions. In addition, the soil layer is about 2m thick and the hydrogen sulfide content is high, which is the difficulty and focus of hydrogen sulfide soil construction in this project.

[0032] In order to solve the above problems, the present invention provides a method for dredging a harbor channel in soil containing hydrogen sulfide, comprising:

[0033] Step 1: Install hydrogen sulfide detectors at different positions on the hopper, weld keels around and above the mud tank of the hopper, and partially seal the hatch of the mud tank with a cloth film set on the keel. The sealed area includes the front sealed area in the 12-20m section near the side of the hopper's driving platform and the rear sealed area in the 10m area of ​​the rear section of the mud tank. The middle area is open and equipped with a high-power axial flow fan. A high-power fan is installed in the living cabin of the hopper, and a high-power axial flow fan is installed in the main engine room, pump room, and repair room of the hopper. The mud door hole on the mud tank deck is filled with an expansion foam agent, and a cover plate is installed outside the mud door hole to prevent hydrogen sulfide gas from being released outward through the mud door hole on the mud tank deck;

[0034] Specifically, the project department and the ship communicated and discussed with domestic experts and hydrogen sulfide equipment manufacturers for many times, and finally selected YT-95H-H according to the ship type and ship layout of the construction site. 2 SA type fixed hydrogen sulfide alarm, this detector has the features of remote monitoring, explosion-proof, two-level sound and light alarm, and temperature compensation, which can realize the monitoring of hydrogen sulfide in different temperature environments of ships.

[0035] According to the ship type and ship layout of the trailing suction hopper vessel, the monitoring range of the hydrogen sulfide detector is 20-50m 2 , it is planned to install 30 fixed hydrogen sulfide detectors and 2 monitoring hosts on the hopper. Each hydrogen sulfide detector is 30-60cm above the ground and fixed with a steel frame. The specific layout is: 21 in the engine room, 9 in the cabin and the bridge. The hydrogen sulfide detector is connected in parallel to a 32-channel monitoring host, which is placed in the engine room monitoring room. 9 hydrogen sulfide detectors are installed in the cabin and the bridge, and are connected in parallel to a 16-channel monitoring host, which is placed on the bridge.

[0036] Fixed hydrogen sulfide detector system setting 15mg / m 3 The low alarm value of (10ppm) is set. If it reaches 10ppm, the detector will emit a "beep beep" beep and a yellow alarm light will be on. When the concentration of hydrogen sulfide in the air reaches 30mg / m 3 When the concentration of chlorine in the air is below 20ppm, the detector emits a beeping sound and a red alarm light comes on.

[0037] During the ship construction, the crew's individual protection was emphasized, and the ship was modified. During the loading construction, the hydrogen sulfide mud was smashed from the hatch to the bottom of the cabin, and the potential energy was converted into kinetic energy, releasing a large amount of hydrogen sulfide gas. The hydrogen sulfide gas was recoiled along the mud tank wall to the upper part of the mud tank, and then diffused, with the overall density at high places being greater than that at low places.

[0038] Therefore, keels are welded around and above the mud tank, and cloth membrane is used to seal the mud tank. The closed area is about 15-20 meters from the side of the bridge and 10 meters behind the mud tank. High-power axial flow fans are arranged in the middle area to disperse hydrogen sulfide and prevent hydrogen sulfide gas from entering the cabin from the front and rear air inlets to ensure that the hydrogen sulfide concentration values ​​in the bridge, living cabin and engine room are within the normal range. At the same time, high-power fans are arranged in the living cabin of the trailing suction hopper, and high-power axial flow fans are arranged in places where air is not circulated, such as the main engine room, pump room, and repair room of the trailing suction hopper, to speed up the gas circulation in the cabin and prevent the accumulation of hydrogen sulfide gas.

[0039] The inside of the 24 small mud door holes on the mud tank deck are filled with expanding foam and covered with covers to prevent hydrogen sulfide from being released through them during construction.

[0040] Step 2: Analyze the main wind direction, secondary dominant wind direction and wind speed according to the wind rose diagram of the harbor channel area, and check the direction of the ship construction channel at the same time, make full use of the physical property of hydrogen sulfide gas that diffuses quickly in the wind, and reasonably use the wind direction and wind speed to reduce H 2 The impact of S gas on construction safety. The ship needs to observe the relative wind direction of the ship at any time according to the wind direction and speed instrument, so as to facilitate the ship to arrange construction production reasonably and try to work against the wind and crosswind;

[0041] Specifically, when there is no wind, increase the speed by 2.5 to 3 knots to reduce the time that hydrogen sulfide gas accumulates on the ship;

[0042] When there is no wind, head wind or cross wind, carry out normal construction, pay attention to the hydrogen sulfide detector in the stern engine room, and keep the high-power axial flow fan turned on.

[0043] Vessels must not carry out construction when the wind is favorable.

[0044] Step 3: Fill the cabin with water before construction, take the highest overflow, open the rake head for high-pressure water flushing, adjust the rake lip upward angle to separate the rake lip from the mud surface at the bottom of the channel, use high-pressure water flushing to break up the mud at the bottom of the channel first, so that the hydrogen sulfide will evaporate and dissolve into the water first;

[0045] If the high-pressure flushing pressure is low, two high-pressure flushing pumps are connected in series to one rake head and used in single rake construction. The rake head on one side with high-pressure flushing is used to dredge the mud, while the rake head on the other side uses a combined pump to pump clean water into the cabin, so that the mud concentration in the mud cabin will be further diluted, accelerating the volatilization and dissolution of hydrogen sulfide.

[0046] Step 4: Use the full tank replacement construction method to suck the mud at the bottom of the channel into the mud tank of the trailing suction hopper ship. During the construction process, turn on the high-power axial flow fan to reduce the concentration of hydrogen sulfide in the air on board;

[0047] Specifically, when the mud at the bottom of the channel is sucked into the mud tank of the suction hopper ship, if the hydrogen sulfide detector continues to alarm, low-concentration external discharge construction is adopted. During construction, the suction hopper head is turned on with high-pressure water flushing, and the suction lip is raised to adjust the angle so that the high-pressure water flushing will first break up and dilute the mud at the bottom of the channel. The diluted mud is then sucked in with a mud pump and discharged directly overboard without being loaded into the tank. The high-power axial flow fans in the main engine room and pump room are turned on for timely exhaust. After the hydrogen sulfide detector detects that the hydrogen sulfide gas concentration has returned to normal, the mud loading construction can be continued.

[0048] During construction, if it is found that the hydrogen sulfide gas has reached the low alarm point of the hydrogen sulfide detector, the ship will immediately issue a ship-wide alarm and require all on-duty personnel to carry emergency respirators. At the same time, the ship will adjust the position of the ship according to the wind direction to keep the bridge, cabins, and main engine room upwind. If the hydrogen sulfide detector continues to alarm and the concentration continues to increase, work will be stopped immediately. If the concentration drops, construction will continue and real-time monitoring will be maintained. If it is found that the hydrogen sulfide gas has reached the high alarm point of the hydrogen sulfide detector, the ship will immediately issue a ship-wide alarm and require all on-duty personnel to carry emergency respirators. The driver should immediately stop construction and drive the trailing suction hopper away from the construction area for ventilation.

[0049] Step 5: When the mud tank is full, drive the suction hopper to the designated mud dumping area to dump the mud.

[0050] Specifically, when the dredger is on its way to the mud dumping area, the ship uses mechanical and natural ventilation to complete the ventilation work inside the cabin in time. After ventilation, the ship's dedicated detection personnel use handheld detection equipment to go to each cabin for detection. After there is no risk of hydrogen sulfide, normal mud dumping operations begin;

[0051] During the mud dumping process, the vessel should be kept dumping against the wind or across the wind to reduce the release of hydrogen sulfide generated during mud dumping.

[0052] The targeted ship modification scheme and construction process of the above embodiment effectively solve the problems of protection, collection and discharge of hydrogen sulfide toxic gas, are easy to operate, economical and practical, enable the trailing suction hopper ship to operate normally, improve the applicability of the trailing suction hopper ship, and have significant economic benefits.

[0053] like Figures 1-2 As shown, in another embodiment, a front baffle 2 and a rear baffle 3 are provided in the mud tank 1 of the trailing suction hopper, and the heights of the front baffle 2 and the rear baffle 3 are both lower than the top height of the mud tank 1; a first plate body 4 is arranged at intervals behind the front baffle 2, and the height of the first plate body 4 is the same as the top height of the mud tank 1, and the lower end of the first plate body 4 is higher than the bottom surface of the mud tank 1, and the edge of a portion of the cloth membrane 5 of the front closed area is connected to the upper end of the first plate body 4, and the water in the front closed area overflows from the top of the front baffle 2 and flows to the middle area along the gap between the front baffle 2 and the first plate body 4; a second plate body 6 is arranged at intervals in front of the rear baffle 3, and the height of the second plate body 6 is the same as the top height of the mud tank 1, and the lower end of the second plate body 6 is higher than the bottom surface of the mud tank 1, and the edge of a portion of the cloth membrane 5 of the rear closed area is connected to the upper end of the second plate body 6, and the water in the rear closed area overflows from the top of the rear baffle 3 and flows to the middle area along the gap between the rear baffle 3 and the second plate body 6;

[0054] Here, the front baffle 2, the rear baffle 3, the first plate body 4 and the second plate body 6 are connected to the inner walls of the mud tank 1 at both sides respectively;

[0055] The mud pump outlet of the trailing suction hopper is arranged in the front closed area and the rear closed area;

[0056] The overflow well 7 of the mud chamber 1 is arranged in the middle area, and the middle area is also provided with an inverted V-shaped cover plate 8, the lower ends of the cover plate 8 are respectively connected to the first plate body 4 and the second plate body 6, and the lower end edge of the cover plate 8 is provided with multiple leakage holes, and a slag powder barrel 9 is arranged above the middle area, where the slag powder barrel 9 can be connected to the keel 10 around and above the middle area of ​​the mud chamber 1 through a connecting rod, and a discharge port is arranged at the bottom of the slag powder barrel 9, and an electric valve is arranged at the discharge port to control the slag powder barrel 9 to discharge slag powder to the middle area, so that the slag powder reacts with the hydrogen sulfide-containing water body overflowing into the middle area to form sulfide precipitation.

[0057] When the above-mentioned trailing suction hopper ship is used for mud loading construction, the front closed area and the rear closed area of ​​the front mud tank 1 are first filled with seawater, and the mud pump of the trailing suction hopper ship sucks mud from the drag head and sends it to the mud pump discharge port along the mud transportation pipeline. Since the mud pump discharge port is arranged in the front closed area and the rear closed area, the mud can be directly discharged into the seawater in the front closed area and the rear closed area. This full tank replacement overflow loading construction method can reduce the disturbance of mud loading, and at the same time reduce the overflow speed of hydrogen sulfide gas and the deposition concentration of hydrogen sulfide on the deck. At the same time, since the top of the front closed area and the rear closed area has been covered with a cloth film 5, the hydrogen sulfide gas is confined in the closed area of ​​the mud tank 1 and is difficult to overflow onto the deck;

[0058] After hydrogen sulfide gas evaporates from the mud, it will also dissolve in the seawater. At this time, the seawater containing hydrogen sulfide gas overflows from the top of the front bulkhead 2 and flows to the middle area along the gap between the front bulkhead 2 and the first plate body 4, and also overflows from the top of the rear bulkhead 3 and flows to the middle area along the gap between the rear bulkhead 3 and the second plate body 6. The cover plate 8 can limit the surging of the seawater containing hydrogen sulfide in the middle area, thereby preventing hydrogen sulfide from escaping from the seawater and depositing on the deck. At the same time, the electromagnetic valve at the discharge port of the slag powder barrel 9 can be opened to allow the slag powder in the slag powder barrel 9 to slide into the seawater in the middle area through the leakage hole along the top inclined surface of the cover plate 8. Here, the slag powder is preferably iron slag or copper slag. Since the slag powder contains iron ions and copper ions, it can form iron trisulfide and copper sulfide precipitation with hydrogen sulfide, so the hydrogen sulfide component in the seawater can be eliminated, and the other components in the slag powder are dispersed in the seawater and separated and discharged through the overflow well 7 in the middle area. In this way, low-grade iron and low-grade copper in the iron slag and copper slag can be enriched, which is convenient for re-refining, thereby improving resource utilization;

[0059] When dumping mud, the mud door holes at the bottom of the mud tanks in the front and rear closed areas are opened to dump mud, while the sediment in the middle area can be sucked to the shore for retention.

[0060] In the above embodiment, two overflows are adopted. The first overflow separates the sludge from the seawater containing hydrogen sulfide, and the second overflow separates the precipitate generated by the reaction of the seawater containing hydrogen sulfide and the slag powder. This not only eliminates hydrogen sulfide and reduces its concentration, but also enriches and separates low-grade copper-iron compounds, killing two birds with one stone.

[0061] 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, and 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 the specific details and the illustrations shown and described herein.

Claims

1. A method for dredging a harbor channel in soil containing hydrogen sulfide, characterized in that: include: Step 1: Install hydrogen sulfide detectors at different positions on the hopper, weld keels around and above the mud tank of the hopper, and partially seal the hatch of the mud tank with a cloth film set on the keel. The closed area includes the front closed area of ​​12~20m section near the side of the hopper bridge and the rear closed area of ​​10m area in the rear section of the mud tank. The middle area is open and equipped with high-power axial flow fans. High-power fans are installed in the living cabin of the hopper, and high-power axial flow fans are installed in the main engine room, pump room and repair room of the hopper. The mud door holes on the mud tank deck are filled with expansion foam, and cover plates are installed outside the mud door holes to prevent hydrogen sulfide gas from being released outward through the mud door holes on the mud tank deck; Step 2: Analyze the main wind direction, secondary dominant wind direction and wind speed according to the wind rose diagram of the harbor channel area, and formulate a trailing suction hopper construction plan according to the wind direction and speed; Step 3: Fill the cabin with water before construction, take the highest overflow, open the rake head for high-pressure water flushing, adjust the rake lip upward angle to separate the rake lip from the mud surface at the bottom of the channel, use high-pressure water flushing to break up the mud at the bottom of the channel first, so that the hydrogen sulfide will evaporate and dissolve into the water first; Step 4: Use the full tank replacement construction method to suck the mud at the bottom of the channel into the mud tank of the trailing suction hopper ship. During the construction process, turn on the high-power axial flow fan to reduce the concentration of hydrogen sulfide in the air on board; Step 5: When the mud tank is full, drive the hopper to the designated mud dumping area to dump the mud; Wherein, a front baffle and a rear baffle are arranged in the mud tank of the trailing suction hopper, and the heights of the front baffle and the rear baffle are both lower than the height of the top of the mud tank; a first plate body is arranged at intervals behind the front baffle, and the height of the first plate body is the same as the height of the top of the mud tank, and the lower end of the first plate body is higher than the bottom of the mud tank, and the edge of the membrane portion of the front closed area is connected to the upper end of the first plate body, and the water in the front closed area overflows from the top of the front baffle and flows to the middle area along the gap between the front baffle and the first plate body; a second plate body is arranged at intervals in front of the rear baffle, and the height of the second plate body is the same as the height of the top of the mud tank, and the lower end of the second plate body is higher than the bottom of the mud tank, and the edge of the membrane portion of the rear closed area is connected to the upper end of the second plate body, and the water in the rear closed area overflows from the top of the rear baffle and flows to the middle area along the gap between the rear baffle and the second plate body; The mud pump outlet of the trailing suction hopper is arranged in the front closed area and the rear closed area; The overflow well of the mud tank is arranged in the middle area, and the middle area is also provided with an inverted V-shaped cover plate, the lower end of the cover plate is respectively connected to the first plate body and the second plate body, and a plurality of leakage holes are arranged on the edge of the lower end of the cover plate. A slag powder barrel is arranged above the middle area, and a discharge port is arranged at the bottom of the slag powder barrel. An electric valve is arranged at the discharge port to control the slag powder barrel to discharge slag powder into the middle area, so that the slag powder reacts with the hydrogen sulfide-containing water body overflowing into the middle area to form sulfide precipitation.

2. The method for dredging a harbor channel in soil containing hydrogen sulfide according to claim 1, characterized in that: The construction plan of the trailing suction hopper vessel is formulated according to the wind direction and speed, including: When there is no wind, increase the speed by 2.5 to 3 knots to reduce the time that hydrogen sulfide gas accumulates on the ship; When there is no wind, head wind or cross wind, carry out normal construction, pay attention to the hydrogen sulfide detector in the stern engine room, and keep the high-power axial flow fan turned on.

3. The method for dredging a harbor channel in soil containing hydrogen sulfide according to claim 1, characterized in that: When the mud at the bottom of the channel is sucked into the mud tank of the suction hopper ship, if the hydrogen sulfide detector continues to alarm, low-concentration external discharge construction is adopted. During construction, the suction hopper head is turned on with high-pressure water flushing, and the suction hopper lip is raised to adjust the angle so that the high-pressure water flushing can first break up and dilute the mud at the bottom of the channel. The diluted mud is then sucked in with a mud pump and discharged directly overboard without loading. The high-power axial flow fans in the main engine room and pump room are turned on for timely exhaust. After the hydrogen sulfide detector detects that the hydrogen sulfide gas concentration has returned to normal, the mud loading construction in step four can be continued.

4. The method for dredging a harbor channel in soil containing hydrogen sulfide according to claim 1, characterized in that: The low alarm point of the hydrogen sulfide detector is set at 15 mg / m 3 The high alarm point is set at 30 mg / m 3 .

5. The method for dredging a harbor channel in soil containing hydrogen sulfide according to claim 4, characterized in that: During construction, if it is found that the hydrogen sulfide gas has reached the low alarm point of the hydrogen sulfide detector, the ship will immediately issue a ship-wide alarm and require all on-duty personnel to carry emergency respirators. At the same time, the ship will adjust the position of the ship according to the wind direction to keep the bridge, cabins, and main engine room upwind. If the hydrogen sulfide detector continues to alarm and the concentration continues to increase, work will be stopped immediately. If the concentration drops, construction will continue and real-time monitoring will be maintained. If it is found that the hydrogen sulfide gas has reached the high alarm point of the hydrogen sulfide detector, the ship will immediately issue a ship-wide alarm and require all on-duty personnel to carry emergency respirators. The driver should immediately stop construction and drive the trailing suction hopper away from the construction area for ventilation.

6. The method for dredging a harbor channel in soil containing hydrogen sulfide according to claim 1, characterized in that: When the hopper vessel is on its way to the mud dumping area, the ship uses mechanical and natural ventilation to complete the ventilation work inside the cabin in time. After ventilation, the ship's dedicated detection personnel use handheld detection equipment to go to each cabin for detection. After there is no risk of hydrogen sulfide, normal mud dumping operations begin; During the mud dumping process, the vessel should be kept dumping against the wind or across the wind to reduce the release of hydrogen sulfide generated during mud dumping.

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