Sludge treatment system for offshore thick oil produced water

Abstract

In order to solve the problems that in an existing sludge treatment system, the synergistic effect of a vacuumizing device and a drying device is poor, and the sludge drying treatment efficiency is affected, the utility model provides a sludge treatment system for offshore thick oil produced water, which comprises a rake dryer and a vacuumizing module communicated with the rake dryer, the rake dryer is provided with a wet material inlet and a dry material outlet; the vacuumizing module comprises a venturi water ejector, the venturi water ejector is of a three-way structure, the two ends of the venturi water ejector in the horizontal direction are used for communicating liquid inlet and mixed liquid ejection respectively, and the end of the venturi water ejector in the vertical direction pumps water-oil mixed steam; sludge enters the rake dryer along the wet material inlet and is dried to generate water-oil mixed steam and dry materials, the water-oil mixed steam is pumped out through the vacuumizing module, and the dry materials are discharged along the dry material outlet. Due to the three-way structure of the Venturi water ejector, the Venturi water ejector is not prone to being blocked during vacuumizing, a vacuum environment can be continuously created in the rake type drying machine, and the sludge drying treatment efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of sludge treatment technology, and in particular to a sludge treatment system for offshore heavy oil produced water. Background Technology

[0002] In offshore heavy oil extraction, large quantities of oily sludge are often generated. Given its high liquid content and large volume, direct resource recovery or harmless treatment would consume significant energy. Therefore, it typically requires drying, which involves using drying equipment to reduce the moisture content and volume of the sludge for subsequent transport to onshore processing. During sludge drying, vacuum equipment is usually used to create a vacuum inside the drying unit, accelerating the drying process and achieving efficient sludge reduction to meet the moisture content requirements of onshore processing facilities, ensuring the smooth operation of the entire process.

[0003] However, the existing combination of vacuuming and drying devices is not very effective, and it is difficult to ensure a stable and highly vacuum environment inside the drying device, which affects the efficiency of sludge drying. Therefore, how to optimize the synergistic application of vacuuming and drying devices to smoothly and efficiently process sludge, while adapting to the characteristics of offshore platforms, has become an urgent problem to be solved. Summary of the Invention

[0004] This invention primarily addresses the problem of poor synergy between vacuuming and drying devices in existing sludge treatment systems, which affects the efficiency of sludge drying.

[0005] To address the aforementioned technical problems, this utility model provides a sludge treatment system for produced water from offshore heavy oil, comprising: a rake dryer and a vacuum module connected thereto; the rake dryer has a wet material inlet and a dry material outlet; the vacuum module includes a Venturi jet, which is a three-way structure, with its horizontal ends used to connect the inlet liquid and the outlet liquid respectively, and its vertical end used to extract water-oil mixed vapor; wherein, the sludge enters the rake dryer through the wet material inlet, is dried to generate water-oil mixed vapor and dry material, the water-oil mixed vapor is extracted by the vacuum module, and the dry material is discharged through the dry material outlet.

[0006] Preferably, the rake dryer includes a jacketed inner cylinder and an outer cylinder, and a stirring rake axially penetrating the dryer. The inner cylinder contains sludge and is connected to the vacuum module. A heat-conducting cavity is formed between the outer cylinder and the inner cylinder to contain a heat-conducting medium and conduct heat to the inner cylinder. The stirring rake is hollow and contains the heat-conducting medium to conduct heat to the inner cylinder. Both the heat-conducting cavity and the hollow stirring rake can heat the sludge contained in the inner cylinder, accelerating its drying rate.

[0007] Preferably, the vacuum module further includes a bag filter connected between the rake dryer and the Venturi jet; wherein, after the solid phase is separated by the bag filter, the water-oil mixed vapor is extracted by the Venturi jet. The bag filter can filter out the solid phase in the water-oil mixed vapor, thereby further preventing the Venturi jet from clogging.

[0008] As a further preferred embodiment, the bag filter has a backflushing air inlet at its upper end for introducing backflushing gas to clean the bag filter; and a dust outlet at its lower end for discharging the dirt and solid phase generated during cleaning. Cleaning the bag filter ensures its proper filtration of the solid phase in the water-oil mixture.

[0009] As a further preferred embodiment, the bag filter is equipped with a heating coil for introducing a heat-conducting medium and heating the bag filter. The heating coil can prevent water vapor from condensing when the hot water-oil mixture passes through the colder bag filter, thus avoiding affecting the filtration efficiency of the bag filter.

[0010] As a further preferred embodiment, the number of bag filters is at least two. Having more bag filters allows for more effective and rapid filtration of the solid phase in the water-oil mixture, thereby making the vacuuming operation more stable.

[0011] Preferably, the system also includes a screw conveyor and a ton bag; the screw conveyor includes a conveying channel and a cooling channel connected in sequence; the conveying channel is connected to the dry material outlet of the rake dryer, and a screw conveying device is provided in the conveying channel for conveying dry material; the cooling channel is connected to the ton bag for cooling the dry material.

[0012] Preferably, the system also includes a screw press, a wet silo, and a screw pump connected in sequence; the screw press is used to receive wet sludge to form sludge; the wet silo is used to buffer the sludge; and the screw pump is connected to the wet inlet of the rake dryer and is used to output sludge to the rake dryer.

[0013] As a further preferred embodiment, the wet silo is equipped with a weighing device and / or an arch-breaking device; the weighing device is used to measure the sludge; the arch-breaking device is an auger device and / or a vibration device. The weighing device can measure the amount of sludge fed into the rake dryer in a single batch, and by controlling the quantity and the screw pump, it prevents too much or too little sludge from entering the rake dryer in a single batch, thereby stably completing the sludge drying process.

[0014] As a further preferred embodiment, the screw pump is equipped with a pressure transmitter to adapt to either a low-pressure alarm or a high-pressure alarm based on the transmitter's reading. A high-pressure alarm indicates that sludge has become clogged inside the screw pump and requires cleaning, while a low-pressure alarm indicates that sludge bridging has occurred in the wet silo, preventing it from being delivered to the screw pump. By reading the pressure transmitter's reading, the normal operation of the sludge treatment system is maintained.

[0015] The beneficial effects of this utility model are as follows:

[0016] First, the sludge treatment system of this utility model uses a Venturi jet as the vacuum module of the rake dryer. By drawing in seawater through the inlet of the Venturi jet to generate pressure, it quickly extracts the water-oil mixed vapor generated inside the rake dryer during the drying of oily sludge. While efficiently extracting the gas, it creates a stable vacuum environment inside the rake dryer, significantly improving the sludge drying efficiency. Compared with the existing combination of drying and vacuuming devices, it is more suitable for offshore platforms, reduces dependence on external energy, and effectively improves vacuuming efficiency.

[0017] Secondly, the sludge treatment system of this utility model uses a venturi water jet with a three-way structure and no complex or easily damaged mechanical parts. It is not easily blocked by dirt, thus affecting the vacuuming effect, thereby ensuring the stability of the entire sludge treatment system working together. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the sludge treatment system for offshore heavy oil produced water according to this utility model.

[0019] Attached reference numerals: 1. Screw press, 2. Wet silo, 3. Screw pump, 4. Rake dryer, 5. Bag filter, 6. Venturi jet, 7. Screw conveyor, 8. Ton bag. Detailed Implementation

[0020] The present invention will now be described in more detail with reference to the accompanying drawings. It should be noted that the following description of the present invention with reference to the accompanying drawings is merely illustrative and not restrictive.

[0021] Where possible, the various embodiments described below can be rearranged to form other embodiments not shown in the following description; the various technical features described below can also be rearranged to form other embodiments not shown in the following description.

[0022] Example 1:

[0023] Please refer to the appendix. Figure 1 .

[0024] To address the issue of poor synergy between vacuuming and drying devices in existing sludge treatment systems, which negatively impacts sludge drying efficiency, this embodiment provides a sludge treatment system for offshore heavy oil produced water, including a rake dryer 4 and a vacuum module connected to it. By cooperating with the rake dryer, the vacuum module extracts water-oil mixed vapor from inside the rake dryer, thereby reducing the internal pressure and creating a vacuum negative pressure environment. Under negative pressure, the boiling points of water and oil in the oily sludge are significantly lowered, making it easier to form water-oil mixed vapor, which circulates repeatedly, accelerating sludge drying efficiency and shortening the drying time. For the difficult-to-dry sludge formed during offshore heavy oil produced water processing, the presence of oil vapor helps improve the overall drying capacity and efficiency.

[0025] The rake dryer has a wet material inlet and a dry material outlet, used to receive sludge before drying and output dried material, respectively. The vacuum module includes a Venturi jet injector, a three-way structure. Its horizontal ends connect the inlet and outlet liquid mixtures, while its vertical end extracts the water-oil mixture vapor. The three-way structure effectively prevents solids in the water-oil mixture vapor from clogging the injector, ensuring smooth vacuum operation. The Venturi jet injector creates a pressure difference at the vertical end by varying the liquid flow rate at both horizontal ends, thus extracting the water-oil mixture vapor from inside the rake dryer. Because the inlet liquid is cold and the water-oil mixture vapor is hot, the vapor condenses rapidly inside the three-way structure, forming a mixture that is discharged along with the inlet liquid. In practical applications, an external discharge system can be connected to treat the mixture for recycling or to prevent environmental pollution.

[0026] On offshore platforms, seawater can be used as the intake water for Venturi jets. Compared to other power sources, seawater is low-cost, readily available, and requires no additional electrical or other energy consumption. During the actual operation of the sludge treatment system, a seawater lift pipeline can also be connected to the Venturi jet's intake point for convenient seawater access.

[0027] Sludge enters the rake dryer through the wet material inlet, where it is dried to produce a water-oil mixture of steam and dry material. The rake dryer works in close coordination with a Venturi jet dryer, enabling stable and rapid drying of the sludge under vacuum. During the drying process, the water-oil mixture of steam is extracted by a vacuum module, and the dry material is discharged through the dry material outlet. The various stages are tightly integrated and operate smoothly, making it suitable for continuous operation in relatively complex environments such as offshore, where high equipment stability is required. This significantly improves the efficiency of the entire sludge treatment process, enabling timely and effective treatment of sludge associated with offshore heavy oil produced water.

[0028] In a preferred embodiment, the rake dryer includes a jacketed inner cylinder and an outer cylinder, and an agitator rake axially penetrating the dryer. The inner cylinder contains sludge and is connected to a vacuum module; a heat-conducting cavity is formed between the outer cylinder and the inner cylinder to contain a heat-conducting medium and conduct heat to the inner cylinder; the agitator rake is hollow and contains the heat-conducting medium to conduct heat to the inner cylinder.

[0029] The inner cylinder contains sludge, which is then agitated by the teeth on the stirring rake. After being heated by the heat-conducting chamber and the hollow stirring rake, heat can be transferred to the sludge to the maximum extent. Compared with localized heating, this allows the sludge to be heated evenly and from all directions within the inner cylinder. This avoids inconsistent drying of the sludge and ensures the stability of the dry material quality.

[0030] In a further preferred embodiment, the rake teeth on the mixing rake can also be hollow to increase the contact area with the sludge and improve drying efficiency.

[0031] In a further preferred embodiment, inlets and outlets for the heat-conducting medium are provided on the outer cylinder or the stirring rake to inject the heat-conducting medium and thus regulate its circulation. The temperature, flow rate, and other parameters of the heat-conducting medium can be precisely adjusted according to the actual drying stage and moisture content of the sludge, thereby achieving precise control of the sludge drying temperature within the inner cylinder. For example, in the initial stage of drying, the temperature of the heat-conducting medium can be appropriately increased and its dosage increased to promote rapid moisture evaporation from the sludge. Towards the end of drying, the temperature can be lowered to avoid over-drying, thus achieving controllability and precision in the drying process. Furthermore, a non-continuous method of injecting the heat-conducting medium can be used, i.e., only one injection of the heat-conducting medium and only one temperature adjustment during a single drying process, thereby saving on the amount of heat-conducting medium used.

[0032] In a further preferred embodiment, the heat transfer medium can be heat transfer oil, steam, or water at a temperature higher than that of the sludge. By adjusting the type of heat transfer medium and other parameters, the versatility and practicality of the rake dryer are enhanced. If heat transfer oil is selected as the heat transfer medium, an external heat transfer oil furnace can be used, or a heat transfer oil furnace can be added to the rake dryer to improve the efficiency of heat transfer medium generation and input into the rake dryer.

[0033] In another preferred embodiment, the Venturi jet injector includes a mixing chamber, a contraction chamber, a throat, and a diffuser chamber that are sequentially connected and located in the same horizontal direction. This layout makes the entire structure more compact, reducing clogging problems caused by complex structures or pipe bends. In the mixing chamber, the incoming water and water-oil vapor mix rapidly to form a mixed liquid. As it flows through the contraction chamber, the flow velocity of the mixed liquid increases sharply due to the gradually decreasing cross-sectional area of ​​the contraction chamber, creating a sufficiently strong negative pressure at the throat. This negative pressure provides the power for the Venturi jet injector to draw in the water-oil vapor mixture. When the mixed liquid flows through the diffuser chamber, its gradually increasing diameter causes the flow velocity to gradually decrease and the pressure to gradually increase. This allows the mixed fluid to be smoothly discharged based on a reasonable pressure difference, avoiding impact on external systems and indirectly maintaining the stable operation of the sludge treatment system.

[0034] In another preferred embodiment, the inlet pressure of the Venturi water jet is at least 3 bar. When the inlet pressure is less than 3 bar, the water flow velocity cannot reach a sufficiently high speed when passing through the contraction section, resulting in a weaker negative pressure at the throat. For example, the inlet pressure can be set to 3 bar, 5.5 bar, 7 bar, etc. The inlet pressure is selected according to different negative pressure requirements, thereby creating a stable vacuum environment inside the rake dryer.

[0035] In another preferred embodiment, the vacuum module further includes a bag filter 5, which is connected between the rake dryer and the Venturi jet. After the water-oil mixture is separated into solid phases by the bag filter, it is extracted by the Venturi jet. The gas discharged from the rake dryer often carries some dust particles. If these dust particles directly enter the Venturi jet with the water-oil mixture, it may cause blockage or affect the vacuuming effect. Furthermore, the dust particles, driven by the high-speed flowing mixture, may also cause wear on the inner wall of the Venturi jet, shortening its service life. The bag filter removes dust impurities from the water-oil mixture, making the mixed steam entering the Venturi jet purer and more conducive to subsequent vacuuming operations.

[0036] In addition, the bag filter plays a role in buffering and stabilizing airflow in the entire vacuum module. Its internal bag structure has a certain resistance regulation function for gas passage, which can make the gas flow and pressure entering the Venturi jet from the rake dryer more stable, and avoid interference with the vacuuming effect of the Venturi jet and the operation of the entire vacuum module caused by the instability of airflow at the outlet of the rake dryer.

[0037] In a further preferred embodiment, a back-blowing air inlet is provided at the upper end of the bag filter for introducing back-blowing gas to clean the bag filter; and a dust outlet is provided at the lower end of the bag filter for discharging the dirt and separated solid phase generated during the cleaning of the bag filter.

[0038] During the operation of a baghouse dust collector, as dust-laden gas is filtered, dust particles gradually adhere to the surface of the filter bags. Over time, this accumulation clogs the pores of the bags, significantly increasing air resistance and reducing dust collection efficiency. Introducing backflushing gas through the backflushing inlet allows for periodic or timely reverse blowing of the filter bags, shaking off the dust adhering to the outer surface. This keeps the pores of the bags open, effectively restoring their permeability and stabilizing airflow resistance, ensuring the baghouse dust collector can continuously remove dust and impurities from water-oil vapor mixtures with high efficiency.

[0039] Furthermore, the reverse-flushing gas cleaning method is relatively gentle yet efficient. By setting a reverse-flushing air inlet at the top of the bag filter, the dust shaken off the filter bags falls orderly into the dust outlet at the bottom of the filter for centralized collection and treatment, which helps to achieve clean production. The dust outlet at the bottom of the bag filter is connected to the outside, enabling it to collect and centrally treat the dust separated from the exhaust gas from the rake dryer, preventing direct dust emissions into the surrounding environment and thus avoiding air pollution, meeting environmental protection requirements.

[0040] Because baghouse dust collectors are relatively independent and have a straightforward structure, problems such as poor dust removal or obstructed airflow can be easily identified by checking the condition of the filter bags and the operating status of the cleaning device. This allows for timely repair or replacement. Furthermore, compared to dealing with complex dust-related issues inside a Venturi jet cleaner, maintaining a baghouse dust collector is much simpler. This reduces the maintenance difficulty and cost of the entire vacuum module and even the entire sludge treatment system, ensuring long-term stable operation of the equipment.

[0041] In a further preferred embodiment, nitrogen can be used as the backflushing gas because nitrogen is chemically stable and safe, thus reducing the need for subsequent gas emission treatment steps.

[0042] In a further preferred embodiment, the bag filter is made of PTFE, which has good chemical stability, resists corrosion from acids and alkalis, is suitable for complex industrial environments, and has a smooth surface that prevents dust from adhering, effectively maintaining air permeability during filtration. The bag filter has a temperature range of 50℃ to 200℃, making it widely applicable to various scenarios. However, when the temperature is below 50℃, high humidity can easily lead to condensation, causing dirt to adhere and clog the pores of the filter bags, increasing ventilation resistance, and potentially promoting microbial growth that erodes the bags, affecting their lifespan and efficiency. Furthermore, PTFE softens and deforms at temperatures above 200℃, damaging its pores and reducing dust removal efficiency. Therefore, the temperature range of the bag filter can be selected from 50℃, 125℃, 200℃, etc., to ensure the safety and stable operation of the system.

[0043] In a further preferred embodiment, the bag filter is equipped with a heating coil for introducing a heat-conducting medium and heating the bag filter. The heating coil heats the bag filter, preventing excessive temperature differences between the bag filter and the water-oil mixture, which could lead to condensation. Furthermore, the solid phase of the water-oil mixture may contain viscous components, which can easily clump and adhere to the inner wall, surface of the filter bags, or bottom of the bag filter at lower temperatures. This prevents condensation and blockage of the bag filter due to water vapor and dirt, thus maintaining the normal dust removal function of the bag filter and ensuring its operating efficiency.

[0044] In addition, a suitable temperature environment helps maintain the stable flow characteristics of airflow in the bag filter, avoids airflow turbulence caused by local temperature differences, and allows water-oil mixed vapor containing solid phases to pass through the filter bag more evenly and smoothly for filtration.

[0045] In a further preferred embodiment, the bag filter is equipped with a heat transfer medium inlet and a heat transfer medium outlet, allowing for flexible selection of the type of heat transfer medium and other parameters based on actual production conditions, sludge characteristics, and other environmental factors. Furthermore, the heat transfer medium output from the rake dryer can be fed into the bag filter for reuse, thereby saving costs and reducing the number of times the used heat transfer medium needs to be reheated.

[0046] In a further preferred embodiment, the number of bag filters is at least two. Using multiple bag filters allows for faster filtration of the solid phase in water-oil mixed vapors. Connecting multiple bag filters in parallel significantly accelerates the filtration efficiency. Connecting multiple bag filters in series significantly improves the filtration effect and effectively prevents clogging of the Venturi jet.

[0047] Example 2:

[0048] Please refer to the appendix. Figure 1 .

[0049] This embodiment provides a sludge treatment system for produced water from offshore heavy oil fields. It supplements the existing sludge treatment system architecture described in Embodiment 1, and further includes a screw conveyor 7 and a ton bag 8. The screw conveyor includes a conveying channel and a cooling channel connected in sequence. The conveying channel is connected to the dry material outlet of a rake dryer, and a screw conveying device is installed within the conveying channel for conveying the dry material. The cooling channel is connected to the ton bag for cooling the dry material.

[0050] The structural features of screw conveyors enable them to stably and continuously transport dry material discharged from rake dryers. The rotating helical blades within the conveying channel propel the dry material steadily along the channel towards the cooling channel, preventing interruptions in the transport process and ensuring the orderly transfer of dry material from the dryer to the subsequent collection stage during sludge drying. Screw conveyors are highly adaptable to dry materials with varying particle sizes, moisture content, and viscosity. Whether the material is relatively loose or slightly sticky wet, screw conveyors can effectively transport it by adjusting parameters such as the rotational speed and pitch of the helical blades. This is particularly important for the dry material formed after drying sludge, which has complex composition and diverse properties, ensuring that the dry material can smoothly enter the collection bags and avoids transport difficulties caused by the characteristics of wet materials.

[0051] When the dry material discharged from the rake dryer first enters the conveyor channel, it often still carries some heat. If this heat cannot be dissipated in time, prolonged accumulation in the conveyor channel may lead to excessively high temperatures in the dry material. For some temperature-sensitive wet materials, excessively high temperatures may alter their properties, such as causing oxidation reactions or component decomposition, thereby affecting the quality and subsequent usability of the wet material. Therefore, by setting up a continuous cooling channel after the conveyor channel, cooling media can be injected into the configured cooling structure to absorb the heat from the dry material, ensuring that the collected dry material has normal properties and a suitable temperature, preventing the ton bags from being scalded.

[0052] Furthermore, the high temperature of the dry material itself poses a certain fire hazard, especially when the dry material may contain flammable components or when it is in full contact with air inside the screw conveyor. If it encounters a suitable ignition source, a fire could easily break out. Timely cooling of the dry material through cooling channels, reducing its temperature to within a safe range, can significantly reduce the risk of such fires, ensuring the safety of personnel and equipment on the production site and meeting the requirements of safe production.

[0053] The temperature of the dry material produced by a rake dryer is generally 80℃~120℃. After conveying and cooling, the temperature of the dry material can reach 50℃~80℃, allowing it to be directly collected in ton bags, achieving integrated discharge and collection and accelerating the efficiency of the entire sludge treatment process. For example, a rake dryer producing 120℃ dry material can be conveyed and cooled to 80℃, which can be directly collected in ton bags. Alternatively, 80℃ dry material can be transported and cooled to 50℃. 100℃ dry material can be transported and cooled to 65℃ or even lower. By adjusting the flow rate and type of cooling medium, dry material with a temperature range of 80℃~120℃ can be cooled to any temperature within the range of 50℃~80℃, and the temperature after cooling is lower than the temperature before cooling.

[0054] In a further preferred embodiment, a cooling medium inlet and a cooling medium outlet can be provided on the cooling structure configured in the cooling channel, so as to control the flow rate and temperature of the cooling medium according to the actual situation, thereby accurately controlling the cooling effect in the cooling channel and enabling the equipment to better adapt to the production environment.

[0055] In a further preferred embodiment, seawater is used as the cooling medium, and the cooling medium does not need to come into contact with the dry material, thus saving the cooling medium treatment step after cooling. Therefore, offshore platforms do not need to use cooling circulating water or chilled water as the cooling medium; using seawater can meet the cooling needs while reducing resource waste.

[0056] Example 3:

[0057] Please refer to the appendix. Figure 1 .

[0058] This embodiment provides a sludge treatment system for produced water from offshore heavy oil fields. Based on the existing sludge treatment system of Embodiment 1 or Embodiment 2, the system is further improved. The sludge treatment system also includes a screw press 1, a wet silo 2, and a screw pump 3 connected in sequence. The screw press is used to receive wet sludge to form sludge; the wet silo is used to buffer the sludge; the screw pump is connected to the wet inlet of a rake dryer and is used to output sludge to the rake dryer.

[0059] Screw presses, as a commonly used solid-liquid separation device, can effectively separate solids and liquids in muddy wet materials. For complex wet materials like sludge, the interior often contains both solid impurities and particles, as well as a large amount of water and potentially oily liquid components. Through the rotation of the screw shaft and the squeezing action between the moving and stationary rings, the screw press can gradually aggregate the solid components and separate them from the liquid phase, thus simply processing the wet sludge into sludge.

[0060] The wet silo serves as a buffer and homogenizes the sludge. Although different batches of wet sludge undergo preliminary solid-liquid separation after passing through the screw press, slight differences may still exist in terms of composition and moisture content. In the wet silo, the wet sludge can be thoroughly mixed, resulting in more uniform properties and preventing problems such as significant differences in drying effects or incomplete drying during subsequent drying processes caused by uneven wet sludge distribution.

[0061] Screw pumps possess excellent self-priming capabilities and stable flow characteristics, enabling them to reliably deliver wet materials from the wet silo to the wet material inlet of the rake dryer at a set flow rate. In the entire sludge treatment system, the flow rate matching of wet materials between different stages is crucial. Screw pumps can overcome certain pipeline resistance and the viscosity of wet materials, ensuring a stable and controllable amount of wet material entering the rake dryer. This prevents fluctuations in the wet material delivery volume from affecting the dryer's normal operation, such as preventing insufficient drying due to excessive feed or reduced equipment utilization due to insufficient feed, thus guaranteeing the continuity and stability of the entire system's wet material processing.

[0062] This improves the pretreatment efficiency for complex wet materials such as oily sludge. The screw press quickly separates solids and liquids, the wet silo buffers and evenly distributes the wet material, and the screw pump delivers it stably. The close cooperation of all parts allows sludge that may have been messy and difficult to dry directly to be processed into a state that meets the feeding requirements of the rake dryer in a short time. This shortens the preparation time in the entire sludge treatment process, improves the reliability and collaborative operation of the system, and thus enhances the overall efficiency of the entire system from sludge reception to the final dry material output.

[0063] Based on the above-described sludge treatment system, the process is as follows: Wet material with a moisture content of 95% first enters the screw press from the inlet of the sludge thickening tank. The sludge produced by the screw press has a moisture content of 85% and settles into the wet material silo by gravity. From the bottom of the wet material silo, the sludge is continuously and evenly conveyed in batches to the rake dryer via a screw pump. Inside the rake dryer, heat is exchanged through a heat transfer medium, and the sludge is continuously agitated by stirring rakes, causing the moisture and oil in the sludge to evaporate. During this drying process, a Venturi jet, based on the filtration of the bag filter, continuously extracts the water-oil mixture vapor from the rake dryer using its own pressure, creating a vacuum environment inside the rake dryer and accelerating the drying rate. The rake dryer ultimately dries the sludge into dry material, which is then conveyed sequentially through the screw conveyor and cooling channels to a collection bin for direct collection.

[0064] In the above process, the moisture content of the wet material is between 90% and 95%, which can be 90%, 92.5%, or 94%, etc. The moisture content of the sludge after treatment by the screw press is between 80% and 85%, which can be adjusted to 80%, 83.5%, 84%, etc., depending on the requirements.

[0065] In a further preferred embodiment, the bottom of the wet material silo is set as a conical structure, so that the wet material gathers to the lowest point by gravity. For example, when sludge is being transported, the outlet valve of the wet material silo is opened, and the sludge can slide down the conical surface and flow out without external force, which can achieve efficient emptying.

[0066] In a further preferred embodiment, the wet silo is provided with at least one of a weighing device or an arch-breaking device; the weighing device is used to measure sludge; and the arch-breaking device is at least one of an agitator or a vibrating device.

[0067] The weighing device can accurately measure the weight of sludge entering the wet silo in real time, which is crucial for the wet material management of the entire sludge treatment system. By recording the amount of sludge fed at different times and in different batches, the energy, time, and other resources required for subsequent drying stages can be rationally allocated to ensure the efficiency and economy of the production process. During the temporary storage of sludge in the wet silo, the weighing device monitors the dynamic changes in the weight of the wet material, ensuring the stable operation of the entire system.

[0068] Due to its inherent viscosity, moisture content, and particle characteristics, sludge tends to arch after being stored in a wet silo for a period of time. This arching can further clog the silo outlet, preventing the screw pump from properly extracting the wet material and thus affecting the continuity of wet material transport throughout the system. This also prevents downstream equipment such as the rake dryer from receiving a stable supply of wet material in a timely manner. Using an arch-breaking device can effectively break up wet material arching and maintain the continuity of wet material transport from the wet silo. Specifically, an auger continuously agitates and tumbles the wet material, disrupting any arched structures that may form, while a vibrating device uses vibration waves to loosen and disperse the wet material. Both effectively break up wet material arching, ensuring that the wet material flows smoothly from the wet silo to the screw pump and maintaining stable system operation. Therefore, in practical applications, only an auger can be selected to agitate the wet material and prevent arching; only a vibrating device can be selected to loosen the wet material and break up arches; or both an auger and a vibrating device can be used simultaneously, relying on vibration and agitation to avoid arching and bridging.

[0069] Furthermore, within the wet material silo, a weighing device alone can be used to control the flow rate of wet material and prevent blockages during transport. Alternatively, a de-bridging device can be used to continuously break up arches in the wet material, thus preventing blockages during transport. Weighing and de-bridging devices can also be used simultaneously, allowing for control of the single-batch transport volume of wet material and timely breaking up of arches, significantly improving the transport rate and safety.

[0070] In a further preferred embodiment, the screw pump is equipped with a pressure transmitter, which adapts to low-pressure or high-pressure alarms based on the transmitter's reading. The pressure transmitter can accurately detect the pressure value in the internal pipeline of the screw pump in real time and display it on a display. By monitoring changes in the reading, the flow of sludge through the pipeline can be understood.

[0071] When the pressure transmitter displays low pressure and triggers a low-pressure alarm, it means that the screw pump may be experiencing insufficient feed. This could be due to factors such as the wet silo being nearly depleted or blockages / leaks in the wet material delivery pipeline, resulting in insufficient wet material entering the screw pump. If the screw pump operates for an extended period under low pressure and near-dry conditions, excessive friction will occur between the screw and pump body due to the lack of lubrication and cooling from the wet material, accelerating component wear and potentially damaging the pump. The low-pressure alarm promptly alerts personnel to investigate the cause, replenish the wet material, or repair pipeline malfunctions, preventing damage from dry running and extending the equipment's lifespan.

[0072] When a pressure transmitter displays low pressure and triggers a high-pressure alarm, it typically indicates a problem with the screw pump's internal piping: wet material blockage, outlet obstruction, or internal component malfunction. This prevents the smooth discharge of wet material, causing pressure to accumulate and rise within the pipes. Failure to promptly identify and address this high-pressure situation can lead to several issues. First, it can subject the screw pump to excessive pressure load, potentially causing motor overload, pump body rupture, and other serious malfunctions. Second, excessive pressure may breach the seals at pipe connections, leading to wet material leakage, which not only affects production but also poses safety hazards such as environmental pollution. A high-pressure alarm allows personnel to respond quickly, identify and resolve the root cause of the pressure increase, effectively preventing these potential risks and ensuring the safety of equipment and personnel.

[0073] Excessive output pressure from the screw pump can also adversely affect downstream equipment such as rake dryers. For example, it may impact the dryer's feed inlet structure, affecting its sealing performance or the normal distribution of wet material inside. Timely detection and resolution of problems via high-pressure alarms helps maintain good connectivity and stable operation between all equipment in the system, preventing a single fault from affecting other equipment and reducing overall maintenance costs and complexity.

[0074] It should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A sludge treatment system for offshore heavy oil produced water, characterized in that, Includes a rake dryer and a vacuum module connected to it; The rake dryer has a wet material inlet and a dry material outlet; The vacuum module includes a Venturi water jet, which is a three-way structure. Its two horizontal ends are used to connect the liquid inlet and the liquid outlet, respectively, and its vertical end is used to extract water-oil mixed vapor. The sludge enters the rake dryer through the wet material inlet and is dried to generate water-oil mixed steam and dry material. The water-oil mixed steam is extracted by the vacuum module and the dry material is discharged through the dry material outlet.

2. The sludge treatment system according to claim 1, characterized in that, The rake dryer includes a jacketed inner cylinder and an outer cylinder, and also includes a stirring rake that axially penetrates the rake dryer. The inner cylinder contains sludge and is connected to the vacuum module; A heat-conducting cavity is formed between the outer cylinder and the inner cylinder to contain the heat-conducting medium and conduct heat to the inner cylinder. The stirring rake is hollow and is used to contain the heat-conducting medium and conduct heat to the inner cylinder.

3. The sludge treatment system according to claim 1, characterized in that, The vacuum module also includes a bag filter, which is connected between the rake dryer and the Venturi water jet. The water-oil mixed vapor is separated into solid phases by the bag filter and then extracted by the Venturi jet.

4. The sludge treatment system according to claim 3, characterized in that, The bag filter has a back-blowing air inlet at the top for introducing back-blowing gas to clean the bag filter. The bag filter has a dust outlet at its lower end for discharging the dirt and solid phase generated during the cleaning of the bag filter.

5. The sludge treatment system according to claim 3, characterized in that, The bag filter is equipped with a heating coil for introducing a heat transfer medium and heating the bag filter.

6. The sludge treatment system according to claim 3, characterized in that, The number of bag filters is at least 2.

7. The sludge treatment system according to claim 1, characterized in that, It also includes screw conveyors and ton bags; The screw conveyor includes a conveying channel and a cooling channel connected in sequence; The conveying channel is connected to the dry material outlet of the rake dryer, and a screw conveyor is installed in the conveying channel for conveying dry material; The cooling channel is connected to the ton bag and is used to cool the dry material.

8. The sludge treatment system according to any one of claims 1 to 7, characterized in that, It also includes a screw press, a wet silo, and a screw pump connected in sequence; The screw press is used to receive wet sludge to form sludge; the wet silo is used to buffer the sludge; the screw pump is connected to the wet inlet of the rake dryer and is used to output sludge to the rake dryer.

9. The sludge treatment system according to claim 8, characterized in that, The wet silo is equipped with a weighing device and / or an arch-breaking device; The weighing device is used to measure sludge; The arch-breaking device is an auger device and / or a vibration device.

10. The sludge treatment system according to claim 8, characterized in that, The screw pump is equipped with a pressure transmitter to adapt to low-pressure or high-pressure alarms based on the reading of the pressure transmitter.

Images