For the cause of centrifuge accident, in order to ensure the safety of centrifuge use, we should strengthen the following aspects of management.

Correct installation of centrifuges

(1) Power supply voltage. The voltage fluctuation should meet the industry standard within 10%, otherwise the centrifuge can not run normally. If the voltage fluctuation exceeds the industry standard, the voltage regulator should be used to meet the normal working needs of the instrument.

(2) Protection of grounding. The indoor should have independent ground wire, the ground wire should be reliably connected with the centrifuge shell, the ground resistance <4Ω, the ground wire can not be connected to the heating pipe, the water pipe, so as to avoid the occurrence of electric shock accident.

(3) Centrifuge placement. A suitable location should be selected according to the performance of the centrifuge, and the general low speed centrifuge (table) can be placed on a smooth, solid table (its base is equipped with rubber suction feet, with the help of atmospheric pressure and the weight of the instrument itself, close to the table); large capacity low speed centrifuge and high speed centrifuge should be placed on the corresponding solid ground, horizontal placement. Centrifuge weighing hundreds of kilograms, should be placed on a very solid ground, and equipped with dustproof, moisture-proof equipment. There is no strong vibration source near the centrifuge, avoid heat source and direct sunlight around, leave some space around, keep good ventilation.

(4) Host installation. Adjust the screw to support the machine foot to the ground, observe and adjust the screw through the level to make the main engine stable. Install the rotor, position the fastening, place the leveler in multiple parts of the rotor, adjust the screw until the leveler bubbles are all located in the center. Ensure that the 4 feet are balanced and the suspension is not allowed.

In the process of using the centrifuge, it is necessary to strictly follow the operating manual of the centrifuge model. This is certainly to be followed, but the machine, like people, occasionally appears “sick “, that is, machine failure. In the face of failure is their own roll up sleeves to start repair? Or call the repairman? Today, according to the practice experience of centrifuge maintenance, we have sorted out some common problems and methods of centrifuge maintenance.

1. Oil pressure fault problem. This kind of fault mainly shows that there is no oil pressure, too low oil pressure or too high oil pressure. Its treatment is:

(1) No oil pressure. Check whether the oil filter is blocked, whether the pressure gauge is damaged, whether the tubing and joints are connected and loose, broken, and whether the tubing is unblocked.

(2) Oil pressure is too low. The normal outlet oil pressure of the centrifuge in this coal preparation plant is 3.0~3.5 bar, If the oil pressure is too low, check whether the suction pipe from the oil pump passing through the filter to the oil tank is unblocked; check whether the oil line is leaking; check whether the coupling between the motor and the oil pump shaft is damaged, otherwise replace the coupling; whether the oil pump is damaged, otherwise replace the oil pump.

(3) Excessive oil pressure. When the oil pressure of the centrifuge is too high, check whether to add appropriate mechanical oil to the tank according to the requirements of the equipment usage instructions; check whether each pipeline is blocked, if there is a blockage problem, use compressed air to clean the sundries in the pipeline.

B. Excessive vibration fault. The problems of excessive vibration during the operation of the centrifuge are mostly caused by incorrect installation, blocking deformation of the sieve basket, blocking of the coal channel between the sieve basket and the scraper, and loosening of the bolts. The solutions are as follows: check whether the sieve basket is blocked, worn out or deformed; check whether the spring of the vibrator is aged; check whether there is a fine coal accumulation on one side of the sieve basket; check whether the wedge sieve basket is damaged, deformed or unbalanced; check whether the anchor bolt is corroded and firm; check whether the bearing is damaged and replace the bearing if it is damaged; if the new vibrating motor is replaced, check whether it is consistent with the load of the replaced motor.  And to match the other side of the motor, the two motors should be assembled the same.

With the accelerated development of society, the sewage wastewater discharged through food, chemical and other industries can be seen everywhere, the national government has also issued corresponding targets for sewage treatment, and for the way of sewage treatment, it needs physical, biological and chemical treatment to remove impurities. Now, the common solution to this problem is to separate sewage and waste residue through decanter centrifuge, in the process of biological and chemical auxiliary treatment, and then through the continuous circulation of centrifuge equipment after the sewage can be turned into available water resources.

The use of decanter centrifuges to treat sewage problems mainly goes through the following stages:

Stage 1: Screening and preprocessing

Because many waste water because of external reasons, there will be too many solid waste inside, such as some common garbage items, cosmetics, sanitary products, rags, plastic products, stone particles and so on. And in order to avoid damage to separation equipment, we have to filter out the waste in the wastewater, do this step is very important.

Phase II: Physical/Chemical treatment

This stage can remove a lot of solid impurities, it is necessary to use decanter centrifuge equipment, but in this process to the treatment of waste water to add a certain amount of coagulant or polymer and other chemical agents, to the sewage of small particle impurities to polymer, so as to facilitate decanter centrifuge equipment for solid-liquid separation treatment, if the sewage contains oil, oil and water separation can be carried out after re-separation treatment.

Phase III: Biological treatment

This stage is the final stage, starting with the adjustment of sewage through physical filters, such as sand filters, to remove residual organic and inorganic pollutant particles in the water. The second is sterilization, which can be used to sterilize water quality by ultraviolet light or chlorination.

It can be seen from the above steps that the cost of treating wastewater into available water resources is high, and it is very tedious at the same time. Liaoning Fuyi production of decanter centrifuge can do continuous operation processing, and can be different material separation requirements to develop appropriate centrifuge equipment, if there are other details need to know, can be at any time at any time.

In recent years, with the increasing environmental pollution, the state pays more and more attention to environmental protection. Especially this year, the special action of environmental protection swept across the country, in order to let enterprises attach importance to environmental protection, so that enterprises in the process of production to achieve the purpose of energy conservation and environmental protection. For the construction engineering industry, the drilling cast-in-place pile mud treatment is an urgent need to solve the environmental protection point, mud discharge absorption point on the surrounding environment is also huge, so not to solve this problem, the construction industry will also face the risk of closure and regulation.

In the past, the mud discharged by bored piles was transported to the designated absorption site through mud tankers. The mud sedimentation tank is set up in the absorption yard. After three stages of sedimentation, the digger digs out the sediment and transports it to the evaporation tank. After natural dehydration and solidification, it is transported to the site as subgrade filler, earth backfill or local backfill waste soil.

Mud curing treatment

In the process of precipitation and evaporation, occupying a large area of the site will cause certain damage to the surrounding ecology. The sewage discharge after sedimentation and the landfill of waste soil caused some damage to the surrounding environment. If the harmful substances in the mud are buried on the spot, it is easy to cause pollution and damage to the surrounding groundwater sources.

Because of the damage of mud and environmental protection special activities, our project has introduced the mud curing dehydration treatment equipment. The mud curing equipment we introduced is “potion” curing, the moisture content of the mud block after dewatering is controlled at about 20%, which can reach the condition of earth-moving out; the water used for the construction of bored cast-in-place piles can be recycled through dehydration equipment, and the water use rate is up to 95%; the mud curing field is digested to reduce the pollution of the surrounding environment.

Slurry curing process

The main parts of the treatment process of mud curing treatment equipment are: liquid mixer, mud curing reaction tank, mud curing filter press, mud pressure filtration water collection system. First, the liquid is mixed into the liquid mixer to stir, and then the curing agent is prepared, and then a branch pipe is set up on the input pipe of the mud curing reaction tank, and the curing liquid mixer is connected, and the proportion of the mud mixing liquid is controlled by the liquid flow rate and the mud flow rate. After mixing the appropriate proportion of liquid slurry into the curing reaction tank, it is pressurized and transported to the mud curing filter press, and the water in the mud is removed by physical and mechanical extrusion.

4. Cooling and lubrication
When drilling, the drill bit has been rotating and breaking rock strata at high temperature, producing a lot of heat; the drilling tool also continuously friction with the shaft wall to produce heat. Through the circulation of drilling fluid, the heat is taken away in time, which can play the role of cooling bit, drilling tool and prolonging its service life. Because of the existence of drilling fluid, the drill bit and drilling tool are rotated in the liquid, so the friction resistance is greatly reduced, which plays a good lubricating role.
5. Transfer of hydrodynamics
The drilling fluid is ejected at a very high flow rate at the drill nozzle, and the high speed jet produced a strong impact on the bottom of the well, thus improving the drilling speed and rock breaking efficiency. High pressure jet drilling is to use this principle, significantly improve the mechanical drilling speed. When drilling with turbine drilling tools, the drilling fluid flows through the turbine blade at a higher flow rate from the drill pipe, making the turbine rotate and driving the bit to break the rock.
6. Access to underground information
Through the change of rock debris and drilling fluid performance to obtain all kinds of underground information for drilling construction to provide the basis for the formulation of technical measures.
In addition, in order to prevent and minimize damage to oil and gas reservoirs, modern drilling technology also requires that drilling fluid must be compatible with the oil and gas reservoirs encountered by drilling to meet the requirements of protecting Shantou gas reservoirs; in order to meet geological requirements, the drilling fluid used must be conducive to formation testing without affecting formation evaluation; drilling fluid should also be free from injury and pollution to drilling personnel and the environment, small corrosion to downhole tools and surface equipment or minimize corrosion.
Generally, the drilling fluid cost only accounts for 7%~10% of the total drilling cost. However, the advanced drilling fluid technology can often save drilling time twice, thus greatly reducing the drilling cost and bringing considerable economic benefits.

1. Circulation of drilling fluid
   The circulation of drilling fluid is maintained by drilling pumps (commonly known as mud pumps). High-pressure drilling fluid discharged from the drilling pump passes through the surface high-pressure manifold, riser, hose, faucet, square drill rod, drill pipe, drill collar to the drill bit, ejected from the drill nozzle, then flowing upward along the annular space formed by the drill rod and the shaft wall (or casing), returning to the ground through the discharge line, vibrating screen flow into the mud pool, and then through the treatment of various solid control equipment back to the upper pool, into the recirculation, this is the drilling fluid circulation process and  Circulating system.
   

II. Function of drilling fluid
1. Carrying and suspended cuttings

The most basic function of drilling fluid is to carry the cuttings of the bottom hole broken by the bit to the ground through circulation, to keep the hole clean, to ensure that the bit always contacts and breaks the new formation at the bottom of the well, not to cause repeated cutting, and to keep safe and fast drilling. The drilling fluid can suspend the drilling debris retained in the well in the annulus, so that the drilling debris will not sink quickly and prevent the sand-sinking drilling.
 2. Solidify wellbore
Well-wall stability and well-hole rules are the basic conditions for safe, high-quality and fast drilling. The drilling fluid with good performance should be able to form a thin and tough mud cake on the shaft wall by means of liquid phase filtration, stabilize the drilled formation, prevent the liquid phase from invading the formation, and reduce the degree of hydration expansion and dispersion of shale.
3. Equilibrium formation pressure and rock lateral pressure
In the process of drilling engineering design and drilling, it is necessary to adjust the drilling fluid density continuously, so that the liquid column pressure can balance the formation pressure and the formation side pressure, so as to prevent the occurrence of downhole complex situations such as blowout and well collapse.

Other processing technologies

3.1 Demulsification: demulsification methods are mainly chemical demulsification, membrane demulsification, electric field demulsification, shear demulsification, heating demulsification, centrifugal demulsification, etc. Now more chemical demulsification is used, that is, adding demulsifier to emulsified oily drilling wastewater, through chemical action, supplemented by other separation methods, to achieve the purpose of emulsion de-stability, demulsification and oil-water separation. The chemical demulsification methods adopted at home and abroad mainly include salting-out method, acid-base method, condensation method and mixing method, but although these methods make the treatment effect remarkable, but because of the addition of chemical additives, the cost is increased, and the new impact on the environment is also brought.  　　

According to the characteristics of waste drilling fluid as water-based and oil-based mixture, an efficient and economical treatment process was adopted. The results show that the treatment technology can effectively separate the three phases of oil, mud and water in the waste drilling fluid, reduce the amount of sludge, improve the content of pollutants in the effluent, and basically meet the national solid waste discharge standard after treatment, which basically solves the problem of disposal and discharge of waste drilling fluid in oil fields.

 3.2 Mechanical Dehydration: This method is to separate the solid-liquid two phases from the waste drilling fluid by means of enhanced measures such as chemical flocculant deposition and mechanical separation. However, because of the different characteristics of drilling fluid produced by each oil field, a single flocculant can not make the drilling fluid of various properties carry out effective solid-liquid separation, and different flocculants should be used for different waste drilling fluids.　　

3.3 MTC (Mud To Cement) technology: the conversion of waste drilling fluid into cement slurry technology, referred to as MTC technology, which mixes waste drilling fluid with slag and uses activator to activate the solidified components in slag. With other additives to obtain various uses of cementing fluid. This technique has been studied extensively at home and abroad, and has been widely used. There are many advantages to cementing with it: low turbulent displacement, good compatibility with mud, short thickening transition time and static gel strength transition time. 　　

With the continuous development of oil fields, drilling waste treatment has higher requirements, China’s drilling waste treatment work can not be compared with developed countries, because of its late start, research and application is still in a relatively basic stage, the control and prevention of drilling waste liquid is still not in place, and there is still a big gap with the world’s advanced level, so we should increase the research on drilling waste liquid treatment and application, and strive to prevent drilling waste liquid as the focus of drilling pollution control.

2. Curing Method

Curing method is to add curing agent to waste water-based drilling mud or drilling mud sediment, so that it can be converted into soil-like solid (pseudo soil) landfill in place or used as building material, etc. This method can greatly reduce the erosion of soil by metal ions and organic matter in waste drilling mud, thus reducing the environmental impact and harm of waste drilling mud, and at the same time can ensure that waste drilling mud pool can be ploughed back at the end of drilling process.

 2.1 Cement curing technology: Cement curing is a treatment of cement as curing agent to solidify the waste slurry. Cement is an artificial inorganic cement material, the main components are SiO2、CaO、Al2O3 and Fe2O3.. There are many kinds of cement which can be used as curing treatment, the most common application is ordinary Portland cement. The curing principle is to form calcium silicate hydrate glue through silicate and water, and to form an object containing silicate fiber and hydroxide after solidification, to contain harmful substances, and gradually harden to form cement solidified body.

2.2 Lime curing technology: Lime curing is a method of curing waste slurry containing sulfate or sulfite with lime as main curing agent and active silicate as additive. The principle of lime curing is that in the presence of moisture, lime and silica-aluminate roots in additives react with the above type of waste mud, gradually coagulate, harden, and finally achieve curing.

2.3 Curing technology of fly ash: fly ash is a mixture of pozzolanic materials, mainly composed of potentially active impurities such as SiO2、Al2O3. The curing principle of fly ash is that, in the presence of water, silica and alumina are excited by alkaline substances in the mud to produce hydration hardening, stable hydration products (CSH and CAH,CAH) are generated by excitation, which will accelerate the reaction to form ettringite, further improve the gel composition and hardening quality of drilling waste mud system, and finally reach the curing target.

2.4 Water glass curing technology: Water glass is a soluble alkali metal silicate material made of alkali metal oxide and silica, which is a colorless and transparent viscous liquid. Water glass has hardening, binding, containment and other properties, can be used as cementitious materials. Water glass curing method is to use water glass as the main curing substrate, supplemented by inorganic acid substances (such as sulfuric acid, nitric acid and phosphoric acid), and then mixed with waste mud according to a certain proportion of ingredients, neutralization and condensation dehydration reaction, so that the harmful substances automatically dehydration, after condensation hardening, finally achieve curing.

With the continuous exploration of oil field reserves in China, the development strength of oil field has been obviously enhanced, and the number of oil wells is also increasing more and more rapidly. Because of the damage to the environment, the treatment technology of the waste produced during drilling has attracted more and more attention. Drilling fluid, as the main waste liquid to be treated in drilling process, has been widely used in pollution-free treatment technology of oil field waste drilling fluid because of the pollution and damage effect of some chemical components contained in it on the environment.

1 Recycling method

The waste drilling fluid can be reused after recovery, storage and treatment by transit station. This method not only avoids the damage of drilling fluid to the environment, but also effectively reduces the cost of drilling fluid in the process of reuse.

1.1 Mechanized recovery units are used to convert drilling fluid into dry-cured dry powder formulations and to reuse the cured dry powder formulations after hydration. Although the hydrated drilling fluids can not reach their original properties, their use as an aggravating agent is still very effective. This method uses more fuel and costs more in the process of curing the drilling fluid into dry powder formulations, which is also a disadvantage of this method.

1.2 Old well drilling fluid reuse technology: this technology is relatively simple, one well after the completion of the drilling fluid can be moved to another similar well to continue to use, then the drilling fluid only need to add some treatment agent to achieve the original performance for re-use. This method does not require mechanical equipment and fuel, the demand for personnel and equipment is low, the cost is low, and the pollution of drilling fluid to the environment is effectively reduced, so this technology has remarkable effect in terms of economic, environmental and engineering benefits. This method is most suitable for the area with high wellhead density. After the completion of the old well, the drilling fluid is transferred by transfer tank truck Using another field utilization, this method urgently needs to solve an urgent problem, that is, how to ensure the multiple reuse of drilling fluid with the minimum investment, which is the most promising and low cost method at present, effectively realizes the reduction of production cost and the improvement of economic benefit of oil wells.

To be continued

According to the mud properties of different mine sand washing plants, the use of different mud rapid precipitator products can effectively ensure the recycling of cleaning, rapid precipitation speed, flocculation tight. Compared with the present treatment process of mud wastewater from sand washing yard, the separation of mud water and flocculation sedimentation purification by using mud rapid precipitator has great advantages, which is manifested in the following aspects:

1. sewage treatment capacity is large: reduce the precipitation time of suspended matter, reduce the content of suspended matter in sewage and reduce the cost of sewage purification treatment, small area, low management costs. At present, the sedimentation tank sewage purification treatment system, which is widely used by mine sand washing field production enterprises, only depends on the gravity of fine particles for precipitation, its precipitation speed is slow and the precipitation time required is longer.
2. addition amount is less: using this product with a very small amount can play a good flocculation sedimentation effect, rapid precipitation.
   3. removal rate is high: the mud sand branch removal rate is more than 95%, the water in the clear liquid tank can be returned directly to the sand washing system, and the real zero discharge can be achieved. This product can be used for piling, mining, sand washing yard and other mud precipitation treatment.
   
3. Usage:
   1. the slurry rapid precipitator solid particles and tap water were stirred and dissolved into liquid state, which was directly added to the instantaneous precipitation in the mud wastewater of the sand washing field by the way of valve or metering pump. the dissolved concentration of the slurry rapid precipitator was generally 0.1%-0.2%.

2.for the uncertain sediment concentration in mud wastewater, the amount of addition should be determined by experiments.

3.for the treatment of different concentrations of sand washing wastewater, the amount of mud precipitator can be adjusted by field debugging.

Note: the amount of mud precipitator is determined with the concentration of sand washing sewage, if the amount of excessive, it will cause waste and will have a reaction, if the amount of mud precipitator is not enough, it will be difficult to produce precipitation, so the correct and reasonable control of the dosage, should first do a small test to determine the dosage in use.E