Method for safe and environmentally friendly construction of soils containing hydrogen sulfide

Abstract

The application discloses a safe and environment-friendly construction method for soil containing hydrogen sulfide, and comprises the following steps: arranging hydrogen sulfide detectors; arranging multiple hydrogen sulfide detectors and two monitoring hosts in a ship for construction, and the height of each hydrogen sulfide detector from the ground is 30-60 cm; optimizing construction equipment; welding keels around and above the mud cabin of the ship, and adopting a closed film to close the mud cabin; the closed area is an area of 15-20 meters close to the bridge side and an area of 10 meters at the rear section of the mud cabin; high-power axial flow fans are arranged in the middle area; the inside of the mud door hole of the mud cabin deck is filled with expanded foam agent, and the outside is additionally provided with a cover plate to block; double-sided plow teeth are installed at the wear-resistant block of the rake head of the ship; and construction: before construction, hydrogen sulfide gas is dispersed to ensure that the concentration value in the cabin is within the normal range; during the construction process, the fan in the cabin of the ship is closed for external circulation, and the internal circulation mode is opened; and the air flow is accelerated by using the explosion-proof axial flow fan ventilation. The application ensures the safety and high efficiency of the construction of the soil containing hydrogen sulfide.

Description

TECHNICAL FIELD

[0001] The present application relates to the dredging engineering technical field, and particularly relates to a safe and environmentally-friendly construction method for soil containing hydrogen sulfide. BACKGROUND

[0002] Hydrogen sulfide is an inorganic compound with the chemical formula H2S, which is a flammable, explosive, toxic and highly corrosive gas. In the channel engineering or dredging engineering, the soil in the dredging area contains hydrogen sulfide gas. If the protection is not proper, the gas will spread with the disturbance of the soil during the dredging process, which will cause serious consequences and even personnel casualty accidents.

[0003] In the existing dredging construction, the trailing suction hopper dredger is mainly used for construction. However, with the increasing complexity of the dredging soil, the existing equipment and construction process cannot ensure the safe production for the soil containing hydrogen sulfide. SUMMARY

[0004] An object of the present application is to solve at least the above problems and / or defects, and to provide at least the advantages to be described later.

[0005] Another object of the present application is to provide a safe and environmentally-friendly construction method for soil containing hydrogen sulfide, which optimizes the equipment and construction process to ensure the safe and efficient construction of the soil containing hydrogen sulfide.

[0006] In order to achieve these objects and other advantages according to the present application, the technical solutions of the present application are as follows:

[0007] A safe and environmentally-friendly construction method for soil containing hydrogen sulfide, comprising the following steps:

[0008] Step one, arranging hydrogen sulfide detectors: arranging multiple hydrogen sulfide detectors and two monitoring hosts in the ship for construction, and the height of each hydrogen sulfide detector from the ground is 30-60 cm;

[0009] Step two, optimization of construction equipment: welding keels around and above the mud tank of the ship, and using a closed film to close the mud tank, wherein the closed area is the area of 15-20 meters close to the bridge and the area of 10 meters at the rear of the mud tank, the middle area is arranged with high-power axial flow fans, the inside of the mud door hole of the mud tank deck is filled with expanding foam agent, and the outside is blocked by adding a cover plate; double-sided plow teeth are installed at the wear-resistant block of the ship rake head;

[0010] Step three, construction: dispersing the hydrogen sulfide gas in the ship cabin before construction to ensure that the hydrogen sulfide concentration in the cabin is within the normal range, and closing the outer circulation and opening the inner circulation mode of the ship cabin during the construction process, and using the explosion-proof axial flow fan to ventilate and accelerate the air flow.

[0011] Preferably, in step one, the hydrogen sulfide detector detection alarm is a secondary alarm mechanism, specifically including:

[0012] When the hydrogen sulfide detector monitors that the hydrogen sulfide concentration is greater than 10 ppm and less than 20 ppm, the detector emits a buzzing sound and is accompanied by a yellow alarm light alarm, the construction personnel wear hydrogen sulfide breathing protector, continue construction, adjust the ship position according to the wind direction, so that the bridge, respirator, engine room monitoring room are in the windward;

[0013] When the hydrogen sulfide detector monitors that the hydrogen sulfide concentration is greater than 20 ppm, the detector emits a buzzing sound and is accompanied by a red alarm light alarm, the construction personnel wear the respirator immediately, stop construction immediately away from the construction area, and carry out high-pressure water flushing and ventilation on the construction area.

[0014] Preferably, step three specifically includes:

[0015] When there is no wind, increase the speed by 2.5-3 knots, reduce the time of hydrogen sulfide gas gathering in the ship;

[0016] When the wind is on, the normal construction, real-time attention to the alarm of the ship arranged with multiple hydrogen sulfide detectors, the ship's cabin fan is closed to the outside circulation, and the internal circulation mode is opened, and the explosion-proof axial flow fan is always open;

[0017] When the wind is transverse, the construction is carried out in the inner channel area where the hydrogen sulfide gas is high; the explosion-proof axial flow fan is always open;

[0018] When the wind is down, the ship stops construction.

[0019] Preferably, step three and step two quality inspection further include: loading cabin before construction: before construction, the ship cabin is filled with mud, the highest overflow is adopted, the front cabin is closed, the high-pressure water flushing wear block at the rake head and the inside of the rake cavity are opened, the rake lip is adjusted to separate the rake lip from the mud surface.

[0020] Preferably, step one further includes: providing each construction personnel with a portable hydrogen sulfide gas detector, when the hydrogen sulfide concentration in the air is greater than 10 ppm, the detector emits a buzzing sound alarm, when the hydrogen sulfide concentration in the air is greater than 15 ppm, the detector emits a buzzing sound alarm and is accompanied by a red alarm light flashing.

[0021] Preferably, step one further includes: each ship in the construction site is equipped with two four-in-one gas detectors for monitoring the presence of hydrogen sulfide gas and other toxic gases in the air.

[0022] Preferably, wherein, step two further comprises: equipping each room of the ship cabin with a high-power floor standing fan; placing 3000w high-power explosion-proof axial flow fans in the main engine room, pump room and repair room; equipping the cabin, pump room, engine room monitoring room and bridge with hydrogen sulfide breathing protection devices and emergency respirators to meet the needs.

[0023] Preferably, wherein, step three further comprises: during the mud throwing process, the ship keeps throwing mud against the wind or across the wind.

[0024] Preferably, wherein, in step one, the number of hydrogen sulfide detectors is 30, all of which are fixed by steel skeletons, and the monitoring host is 2, the specific installation position is: 21 in the engine room, 9 in the cabin and the bridge, 21 hydrogen sulfide detectors in the engine room are connected with a 32-way monitoring host in parallel, the 32-way monitoring host is placed in the engine room monitoring room, the 9 hydrogen sulfide detectors installed in the cabin and the bridge are connected with a 16-way monitoring host in parallel, and the 16-way monitoring host is placed in the bridge.

[0025] Preferably, wherein, the hydrogen sulfide detector is a YT-95H-H2S-A type fixed hydrogen sulfide alarm.

[0026] The present application at least includes the following beneficial effects:

[0027] 1、The construction method of the present application contains hydrogen sulfide soil safety and environmental protection, optimizes equipment and construction technology, and ensures the safety and efficient development of hydrogen sulfide soil construction

[0028] 2、In the construction method of the present application containing hydrogen sulfide soil safety and environmental protection, the construction method is reasonably set through the distribution and ventilation conditions of hydrogen sulfide soil in the outer channel and the inner channel, the construction safety is taken into account, and the construction efficiency is improved.

[0029] 3、In the construction method of the present application containing hydrogen sulfide soil safety and environmental protection, different alarmers are arranged and equipped in different areas and different construction personnel, and different alarm mechanisms are set, so as to ensure the safety of the construction personnel.

[0030] 4、In the construction method of the present application containing hydrogen sulfide soil safety and environmental protection, the physical property that hydrogen sulfide gas diffuses fast in the wind is fully utilized, the wind direction and wind speed are reasonably utilized, and the appropriate wind direction is selected for construction, so as to facilitate the reasonable arrangement of ship construction production and reduce the influence of hydrogen sulfide gas on construction safety.

[0031] 5、The safe and environment-friendly construction method of soil containing hydrogen sulfide in the application, by loading ballast before construction, the concentration of the slurry in the mud tank is further diluted, the volatilization and dissolution of hydrogen sulfide are accelerated; by modifying into double-sided plow teeth, the crushing effect of the rake head on the soil in the construction area during construction is increased, the characteristics of the plow teeth are fully utilized, the seabed soil is turned and stirred, the turned and stirred soil is fully dispersed by the action of high-pressure water, and the hydrogen sulfide gas in the soil is released. BRIEF DESCRIPTION OF DRAWINGS

[0032] Fig. 1 The flowchart of the safe and environment-friendly construction method of soil containing hydrogen sulfide in the application;

[0033] Fig. 2 The full tank replacement construction schematic diagram of the safe and environment-friendly construction method of soil containing hydrogen sulfide in the application. DETAILED DESCRIPTION

[0034] The application will be further described in detail below with reference to the drawings, so that those skilled in the art can implement the application according to the description.

[0035] It should be noted that the test methods in the following embodiments are conventional methods unless otherwise specified, and the materials can be obtained from commercial channels unless otherwise specified.

[0036] <Embodiment 1>

[0037] For example, Figs. 1-2 The safe and environment-friendly construction method of soil containing hydrogen sulfide is carried out by taking the Tanga harbor channel dredging project in Tanzania as an example.

[0038] I. The situation of the area containing hydrogen sulfide soil:

[0039] 1.1, The dredging project includes the outer channel, the channel entrance, the turning circle and the inner channel area. The dredging engineering quantity is about 1000 million m 3 . The outer channel 1 is 2165m long, the bottom edge design width gradually changes from 240m to 190m; the curved channel arc length is 1527m, the radius is 2040m, and the bottom edge design width is 210m; the outer channel 2 is 1222m long, the bottom edge design width gradually changes from 210m to 170m; the channel entrance is 1309m long, the bottom edge design width is various; the turning circle radius is 260m; the inner channel is 1778m long, and the bottom edge design width is 215m.

[0040] The soil containing hydrogen sulfide is mainly distributed in the outer channel and the inner channel, the entrance channel and the turning circle in the middle area, and the construction soil is mainly sand, and there is no soil containing hydrogen sulfide.

[0041] 1.2, Construction area flow rate: within the entrance, it is a semi-closed harbor, except for the influence of ebb and flow, the flow rate in the harbor is about 0.2 m / s; the main current in the coastal waters outside the harbor area is the South Equatorial Current, with a speed of 0.5-0.6 m / s, and the flow direction is northeast.

[0042] 1.3, Sea waves: from January 2001 to December 2020, the prevailing direction of sea waves was found to be southeast in the offshore area, with the highest waves coming from the southeast; the minimum significant wave height recorded was 0.8 m, with an annual average wave height of 1.6 m; on August 12, 2010, the maximum wave height was 4.6 m, with a direction of 174 ° N (south-southeast); 70% of the wave directions were in the E-S direction, and 30% were in the N-E direction; from April to November, the dominant wave direction was southeast, with the highest waves occurring from June to August. For the nearshore area, the highest waves came from the northeast, with a maximum wave height of 2.4-3.4 m.

[0043] 1.4, Tides: the local area has regular semidiurnal tides, with a high tide of 3.2 m and a low tide of 1.2 m.

[0044] 1.5, The project site is in a tropical savanna climate, with a mild and dry climate, and there is very little fog throughout the year. Occasionally, there is short-term fog, which only has a very small impact on construction. The local area is affected by monsoons, with the construction period being from December to March, mainly affected by north and northeast winds; the construction period is from April to September, mainly affected by southeast and southwest winds. Based on the data analysis results of the above two time periods and the wind resistance of our ships, the wind conditions in this area have little impact on our construction ships.

[0045] 1.6, Hydrogen sulfide soil conditions: the hydrogen sulfide soil is mainly composed of silt, with shell fragments and organic matter, and is very soft to soft, with a moisture content of 100% on the surface, a moisture content of 50% 10 m below the surface, an organic matter content of 8%-16%, an undrained shear strength of 2 kpa 2 m below the surface, and an undrained shear strength of 15 kpa 10 m below the surface.

[0046] II. Hazards of hydrogen sulfide:

[0047] Hydrogen sulfide is an inorganic compound with the chemical formula H2S, which is a flammable, explosive, highly toxic, and extremely corrosive gas. Under normal circumstances, it is a colorless gas with a typical rotten egg odor, with a relative molecular mass of 34.08, a density of 1.539 kg / m 3 , a relative density of 1.19 to air, a melting point of -82.9 °C, a boiling point of -60.3 °C, and is soluble in water. At 0 °C, 1 mole of water can dissolve about 2.6 moles of H2S, and its solubility decreases with increasing water temperature.

[0048] 2.1, Flammability

[0049] The lowest auto-ignition temperature (260°C) occurs at about 15% concentration with air; at higher concentrations or in the absence of oxygen, combustion forms water and sulfur: 2H2S + O2 = 2H2O + 2S↓, at lower concentrations or in the presence of excess oxygen, the combustion product forms water and sulfur dioxide: 2H2S + 3O2 = 2H2O + 2SO2, a pale blue flame is produced during combustion, producing SO2 gas that is harmful to the eyes and lungs. Inadequate oxygen Inadequate oxygen Inhaling small amounts of high concentrations of H2S can be fatal in a short time. Low concentrations of H2S affect the eyes and central nervous system.

[0050] 2.2, Explosiveness

[0051] When the concentration of H2S is between 4.3% and 46%, the mixture of gases formed in the air will produce a strong explosion when exposed to fire.

[0052] 2.3, Toxicity

[0053] H2S gas is a highly toxic gas that can cause death. Its toxicity is 5-6 times that of carbon monoxide. A person's sensitivity to H2S decreases with the number of times they are exposed to it, with the second exposure being more dangerous than the first, and so on. When H2S is inhaled into the body, it travels through the respiratory tract, the lungs, and the blood to all organs of the body. It first irritates the respiratory tract, causing anosmia, coughing, and in severe cases, burns; the eyes are irritated and in severe cases, blindness occurs; the nervous system is irritated, causing dizziness, loss of balance, and difficulty breathing; the heart beats faster, and in severe cases, the heart is starved of oxygen and dies. Alcohol in the blood increases the chances of H2S poisoning.

[0054] The effects of H2S depend on the duration of the exposure and the concentration at which it is exposed, as well as individual physical conditions, so it is difficult to provide a set of fixed rules. H2S concentrations are usually expressed in ppm (per million) but in general, the effects of different concentrations of H2S on humans follow the following rules: in general, repeated exposure to an environment with a concentration of 10 ppm, the average concentration that the body can tolerate. A normal 8-hour workday does not harm health, this concentration is called the threshold limit. If exposure occurs for only a short time during the day, the concentration level can be increased to 15 ppm for a maximum of 15 minutes. A maximum of 4 times a workday with at least 60 minutes of interval in between, this concentration is called the short-term exposure limit.

[0055] III. Construction Process

[0056] 3.1, Equipment:

[0057] Ship: Trailing suction hopper dredger (TUNXI, for dredging), grab dredger group (obstruction salvage and dredging): Jinhangzun 407 (grab), Jinhangzha 48 (mud barge), Jinhangzha 49 (mud barge) and Jinhangzha 51 (mud barge), boat (DARUN 66, emergency rescue).

[0058] Other equipment: gas mask (EHFR-5000, anti-toxic) 40, stand cabinet fan (KS-04X60Dg, ventilation) 13, four-in-one gas detector (detection) 10, portable hydrogen sulfide gas detector (CLIP-H2S, detection) 20, explosion-proof axial flow fan (1000w, 3000w, ventilation) 6, oxygen cylinder and breathing mask (anti-toxic) 5, emergency respirator (THB / 15-I, anti-toxic) 57, fixed hydrogen sulfide monitoring probe (YT-95H-H2S-A, detection) 30, audible and visual alarm (detection) 30, monitoring host (32-way, integrated monitoring) 1 and monitoring host (16-way, integrated monitoring) 1.

[0059] 3.2, Investigation of construction area:

[0060] The area known to contain H2S soil is the outer channel and the inner channel. According to the understanding of the contractor who has once constructed on site, similar conditions also occurred during their construction, but they were grab dredger construction, with small disturbance, no large-scale explosion was found, and the soil sample was also sent to the laboratory, no H2S content was found to be over standard, so no treatment was done. Through on-site investigation, it can be preliminarily judged that the H2S in this area is formed by the decomposition of animal carcasses, and is dispersed in various parts of the construction soil layer.

[0061] The outer channel is thin and open with no shelter, and the ventilation condition is good. Although there are H2S alarm values during construction, the monitoring H2S gas concentration values are within the safe range.

[0062] H2S-containing soil is widely distributed in the inner channel, which is located in a semi-enclosed area in the port, surrounded by urban buildings on all sides, with small wind values, poor gas diffusion conditions, and soil thickness of about 2m, high H2S content, which is the difficulty and key point of H2S soil construction in this project.

[0063] 3.3, Construction process:

[0064] Step one, arrange hydrogen sulfide detector: according to the ship type and ship layout of "TUNXI", the monitoring range of H2S detector is 20-50m 2On the "Tongxu wheel", 30 fixed H2S detectors are installed, and 2 monitoring hosts are installed. Each H2S detector is 30-60 cm away from the ground, and is fixed with a steel framework. The specific layout is as follows: 21 in the cabin, 9 in the cabin and the bridge, and 21 H2S detectors in the cabin are connected in parallel with a 32-channel monitoring host, which is placed in the cabin monitoring room. 9 H2S detectors are installed in the cabin and the bridge, connected in parallel with a 16-channel monitoring host, and the host is placed on the bridge; the specific installation distribution quantity table is as follows Table 1;

[0065] A portable hydrogen sulfide gas detector is provided for each construction worker. When the hydrogen sulfide concentration in the air is greater than 10 ppm, the detector will alarm with a buzzing sound. When the hydrogen sulfide concentration in the air is greater than 15 ppm, the detector will alarm with a buzzing sound and a red alarm light will flash;

[0066] Each ship at the construction site is equipped with two four-in-one gas detectors for monitoring the presence of hydrogen sulfide gas and other toxic gases in the air;

[0067] Among them, the hydrogen sulfide detector is a YT-95H-H2S-A type fixed hydrogen sulfide alarm, and the detection alarm is a two-stage alarm mechanism, which specifically includes:

[0068] When the hydrogen sulfide detector detects that the hydrogen sulfide concentration is greater than 10 ppm and less than 20 ppm, the detector will alarm with a buzzing sound and a yellow alarm light. The construction worker wears a hydrogen sulfide breathing protector and continues to work. According to the wind direction, adjust the position of the ship so that the bridge, the breathing protector, and the cabin monitoring room are all in the upwind position;

[0069] When the hydrogen sulfide detector detects that the hydrogen sulfide concentration is greater than 20 ppm, the detector will alarm with a buzzing sound and a red alarm light. The construction worker immediately puts on a breathing protector and stops working immediately to move away from the construction area. The construction area is subjected to high-pressure water flushing and ventilation;

[0070] Step two, optimization of construction equipment:

[0071] A keel is welded around and above the ship's mud tank, and a closed film is used to close the mud tank. The closed area is 15-20 meters from the bridge side and 10 meters from the rear of the mud tank. High-power axial flow fans are arranged in the middle area. The inside of the mud door hole on the mud tank deck is filled with expanding foam, and the outside is blocked with a cover plate. To maximize the release of H2S gas in the soil, double-sided plow teeth are installed at the rake head wear block to increase the crushing effect of the rake head on the soil during construction. Make full use of the characteristics of the plow teeth to turn over the seabed soil, and combine with the high-pressure water flushing effect to fully disperse the turned-over soil and release the H2S gas in the soil. The closed film is a special film, which is not limited in specific, as long as it can close the mud tank;

[0072] A large power stand fan is equipped in each room of the ship cabin; a 3000w high-power explosion-proof axial flow fan is placed near the main deck mud cabin, the main engine cabin, the pump cabin, the hydraulic room and the engine cabin repair room; hydrogen sulfide breathing protection devices and emergency respirators that meet the needs are equipped in the cabin, pump cabin, engine cabin monitoring room and bridge; the duration of the emergency respirator is 10-15 minutes, which is worn when the general sound alarm system sounds or the H2S gas detector exceeds the standard. The device is only used for "escape" when worn by relevant personnel, not for "work" or rescue, and its distribution is shown in Table 2.

[0073] Step three, construction:

[0074] Before construction, mud is injected into the cabin, the highest overflow is taken, the front cabin is closed, one of the high-pressure water flushing wear-resistant blocks at the rake head and the inside of the rake cavity is opened, the rake lip is adjusted to an angle, the rake lip is separated from the mud surface, the high-pressure water is used to first scatter the mud on the seabed, so that H2S is first volatilized or dissolved in water. If the high-pressure water pressure is small, two high-pressure water pumps are connected in series to one rake head, and single rake construction is taken (one side of the rake head with high-pressure water flushing is used for dredging, and the other side of the rake head takes the pump to flush water into the cabin, so that the concentration of mud slurry in the mud cabin is further diluted, and the volatilization and dissolution of H2S are accelerated.

[0075] Before construction, the hydrogen sulfide gas in the ship cabin is dispersed to ensure that the concentration of hydrogen sulfide in the cabin is within the normal range,

[0076] During construction, the fan in the cabin of the ship is closed for external circulation and opened for internal circulation, the air flow is accelerated by using the explosion-proof axial flow fan; during construction, the appropriate wind direction is selected for construction, the main wind direction, the secondary dominant wind direction and their wind speed are analyzed, and the ship construction route is observed, the physical property of H2S gas that the diffusion speed is fast in the wind is fully utilized, the wind direction and wind speed are reasonably utilized, and the influence of H2S gas on construction safety is reduced. The ship needs to observe the relative wind direction of the ship at any time according to the anemometer, so as to facilitate the ship to reasonably arrange construction production and try to construct against the wind or cross the wind. Specifically, it includes:

[0077] When there is no wind, increase the speed by 2.5-3 knots to reduce the time of hydrogen sulfide gas gathering on the ship;

[0078] When against the wind, normal construction is carried out, real-time attention is paid to the alarm situation of multiple hydrogen sulfide detectors arranged in the ship, the fan in the cabin of the ship is closed for external circulation and opened for internal circulation, and the explosion-proof axial flow fan is kept open;

[0079] When cross the wind, the inner channel area with high hydrogen sulfide gas is constructed; the explosion-proof axial flow fan is kept open;

[0080] When with the wind, the ship stops construction;

[0081] Wherein, after the completion of construction, on the way to the mud throwing area, the ship uses mechanical and natural ventilation to complete the ventilation of the cabin interior in time. After ventilation, the ship's full-time detection personnel use detection equipment to go to each cabin for detection. After there is no risk of H2S, normal operation begins; During mud throwing, the ship keeps throwing mud against the wind or across the wind to reduce the release of H2S that may occur during mud throwing. After mud throwing is completed, 30 minutes before reaching the construction area, the ship's bridge notifies the engine room to start the construction time. Non-operating personnel in the cabin remain on standby, operating personnel are ready for protection devices for operation, and bridge operators are ready for construction. After reaching the construction area, continue construction according to the above construction process.

[0082] During the ship's construction, on the one hand, the individual protection of the crew is emphasized, and on the other hand, the ship is modified. During the loading of the cabin, the H2S-containing mud is thrown from the cabin outlet to the bottom of the cabin, and the potential energy is converted into kinetic energy, releasing a large amount of H2S gas. The H2S gas rebounds to the upper part of the mud cabin along the mud cabin wall, and then spreads, with the overall feature that the density at high places is greater than that at low places.

[0083] A keel is welded around the mud cabin and above it, and a special membrane is used to close the mud cabin. The closed area is about 15-20 meters from the entrance to the bridge side and 10 meters from the rear section of the mud cabin. High-power axial flow fans are arranged in the middle area to disperse H2S and prevent H2S gas from entering the cabin from the front and rear air inlets, ensuring that the H2S concentration in the cabins of the bridge, cabin and engine room is within the normal range.

[0084] The inside of the 24 small mud door holes on the deck of the mud cabin is filled with expanding foam, and the outside is equipped with specially designed cover plates to prevent H2S from being released outward during construction (no small mud door operation during excavation and throwing operation).

[0085] During construction, if H2S gas is found in the dredged material, deck operations are strictly prohibited. The second officer and chief engineer are responsible for the opening and closing of the cabins on the deck and in the engine room, respectively. During construction, cabin doors must not be opened. After leaving the H2S area during the process of throwing mud with a rake, ventilate in large quantities in time. Throw mud against the wind or across the wind.

[0086] The ship's driver should observe the changes in wind direction and speed in time, maintain navigation observation and lookout, and pay attention to H2S concentration monitoring at any time, and do a good job in H2S protection preparation.

[0087] Table 1, Number of Ship Fixed H2S Detectors

[0088]

[0089]

[0090] Table 2, Number of Emergency Respirators

[0091]

[0092] Where, the construction speed is calculated by the following:

[0093] The length of H2S concentration area is 2000m, in order to prevent H2S concentration during construction, the construction method is to leave the H2S concentration area after 1 hour and go to other construction area. The turning time during construction is 8 minutes, and the pre-ballast time is not counted, so the construction speed of this area is calculated as:

[0094] Length of construction area ÷ 1852 × one round trip ÷ (1 hour - 8 minutes / 60)

[0095] 2000 ÷ 1852 × 2 ÷ (1-8 / 60) = 2.5kn

[0096] Therefore, in order to reduce the time of Tongxu in the H2S concentration area, the construction speed of this area is controlled at 2.5kn.

[0097] Calculation of H2S retention time on ship:

[0098] Tongxu is a bow building ship, the rake is at the stern of the ship, the double rake rakes the seabed, and the H2S gas in the disturbed soil layer escapes. Before the H2S gas rises from the seabed to the water surface, the ship has already left the area, and the harm to the ship is not big. However, after the H2S gas in the soil sucked into the mud tank by the mud pump is released, it will all be retained on the ship.

[0099] According to the analysis of the turbulent flow field characteristics of square bluff body, when the flow impacts the solid block, the velocity of the fluid on the front surface of the bluff body along the movement direction is zero due to the blockage of the bluff body, and then it accelerates along the vertical direction by 90°. Very complex changes occur in the boundary layer on the surface of the square bluff body. Because the velocity of the bluff body wall is zero, when the fluid flows through the 90° corner, the viscous force changes and vortexes are formed. The fluid will produce separation at the front corner of the top of the cube and periodic shedding of Karman vortex street at the tail after passing around the bluff body.

[0100] The distance from the front end of Tongxu mud tank to the ship stern is 105m, and the ship position is the engine room. After H2S is released, the ship continues to move forward, and the H2S above the mud tank will gradually leave the ship. The time for H2S to dissipate on the ship from stopping the pump is calculated as:

[0101] Length of inlet pipe system ÷ flow velocity + diffusion time of H2S-containing mud + retention time of H2S on ship body:

[0102] 60 ÷ 6 ÷ 60 + 1 + 105 ÷ (2.5 ÷ 1.852) ÷ 60 = 2.5min

[0103] That is, after the ship stops pumping, 2.5 minutes later, the H2S diffused above the ship will basically leave the ship body.

[0104] The time required for the ship body to replace fresh air:

[0105] The total volume of the cabin of Tongxu is 30300m 3

[0106] The flow of the fan is 48000m 3 / h

[0107] The time required for the ship body to replace fresh air is 30300 / 48000*60=38min

[0108] That is, after the ship stops pumping, 2.5 minutes later, the H2S diffused above the ship will basically leave the ship body.

[0109] In summary, the construction method of the soil containing hydrogen sulfide is safe and environmentally friendly, which can ensure the safety and efficiency of the construction of the soil containing hydrogen sulfide by reasonably optimizing the equipment and the construction process.

[0110] Although the embodiments of the present application have been disclosed as above, it is not limited to the application listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present application. Additional modifications can be easily realized by those skilled in the art. Therefore, the present application is not limited to specific details and the figures shown and described herein without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A safe and environmentally friendly method for construction of a soil containing hydrogen sulfide, characterized by, The method comprises the following steps: Step one, arranging hydrogen sulfide detector: arranging multiple hydrogen sulfide detectors and two monitoring hosts in the ship under construction, the height of each hydrogen sulfide detector from the ground is 30-60 cm; wherein, the number of hydrogen sulfide detectors is 30, which are all fixed by steel framework, the number of monitoring hosts is 2, the specific installation position is: 21 in engine room, 9 in cabin and bridge, 21 hydrogen sulfide detectors in engine room are connected with one 32-way monitoring host in parallel mode, the 32-way monitoring host is placed in the engine room monitoring room, 9 hydrogen sulfide detectors installed in cabin and bridge are connected with one 16-way monitoring host in parallel mode, the 16-way monitoring host is placed in the bridge; Wherein, the detection alarm of hydrogen sulfide detector is a two-level alarm mechanism, which specifically comprises: When the hydrogen sulfide detector monitors that the concentration of hydrogen sulfide is greater than 10 ppm and less than 20 ppm, the detector emits a buzzing sound and is accompanied by a yellow warning light alarm, the construction personnel wear hydrogen sulfide breathing protector, continue construction, adjust the position of the ship according to the wind direction, so that the bridge, the breathing protector and the engine room monitoring room are all in the upwind position; When the hydrogen sulfide detector monitors that the concentration of hydrogen sulfide is greater than 20 ppm, the detector emits a buzzing sound and is accompanied by a red warning light alarm, the construction personnel immediately wear the breathing protector and stop construction away from the construction area, and high-pressure water flushing and ventilation are carried out on the construction area; Each construction personnel is equipped with a portable hydrogen sulfide gas detector, which emits a buzzing sound alarm when the concentration of hydrogen sulfide in the air is greater than 10 ppm, and emits a buzzing sound alarm and is accompanied by a red alarm light flashing when the concentration of hydrogen sulfide in the air is greater than 15 ppm; Each ship in the construction site is equipped with two four-in-one gas detectors for monitoring the presence of hydrogen sulfide gas and other toxic gases in the air; Step two, optimization of construction equipment: welding keel around and above the mud tank of the ship, and closing the mud tank with a closed film, wherein, the closed area is the area of 15-20 meters close to the bridge side and 10 meters of the rear section of the mud tank, high-power axial flow fans are arranged in the middle area, the inside of the mud door hole of the mud tank deck is filled with expanded foam agent, and the outside is blocked by adding a cover plate; double-sided plow teeth are installed at the wear-resistant block of the rake head of the ship; Step three, construction: before construction, the hydrogen sulfide gas in the ship cabin is dispersed to ensure that the concentration of hydrogen sulfide in the cabin is within the normal range, and during the construction process, the fan in the cabin of the ship is closed for external circulation and opened for internal circulation mode, ventilation is used to speed up air flow by using explosion-proof axial flow fan; Wherein, between step three and step two, it further comprises: pre-cabin ballast before construction: before construction, mud is injected into the cabin of the ship, the highest overflow is used, the pre-cabin is closed, one of the high-pressure water flushing wear-resistant block at the rake head and the inside of the rake cavity is opened, the rake lip is adjusted to be separated from the mud surface by raising the rake lip, and the high-pressure water flushing is used to first scatter the mud on the seabed, so that H2S is first volatilized or dissolved in water.

2. The method of claim 1, wherein the soil is treated with hydrogen sulfide. Step three specifically comprises: When there is no wind, increase the speed by 2.5-3 knots to reduce the time of hydrogen sulfide gas gathering on the ship; When the wind, normal construction, real-time attention to the ship layout multiple hydrogen sulfide detector alarm, the ship's cabin fan closed outside the cycle, open the internal cycle mode, keep the anti-explosion axial fan always open; When the wind, normal construction, real-time attention to the ship layout multiple hydrogen sulfide detector alarm, the ship's cabin fan closed outside the cycle, open the internal cycle mode, keep the anti-explosion axial fan always open; When the wind, normal construction, real-time attention to the ship layout multiple hydrogen sulfide detector alarm, the ship's cabin fan closed outside the cycle, open the internal cycle mode, keep the anti-explosion axial fan always open; 3. The construction method for safe and environmentally friendly construction of hydrogen sulfide-containing soil as described in claim 1, characterized in that, Step two also includes: in each room of the ship cabin equipped with a high-power stand cabinet fan; in the main engine room, pump room and repair room placed 3000w high-power anti-explosion axial fan; in the cabin, pump room, engine room monitoring room, the bridge equipped with hydrogen sulfide breathing protector and meet the needs of the emergency respirator.

4. The construction method for safe and environmentally friendly construction of hydrogen sulfide-containing soil as described in claim 1, characterized in that, Step three also includes: during the process of throwing mud, the ship keeps the wind or cross-wind throwing mud.

5. The construction method for safe and environmentally friendly construction of hydrogen sulfide-containing soil as described in claim 1, characterized in that, Hydrogen sulfide detector is YT-95H-H2S-A type fixed hydrogen sulfide alarm.

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