CN1051808C - Protective method for explosion-proof plant area by earthing metallic network cathode, and device for detecting - Google Patents

Abstract

The present invention relates to a protective method and a detecting appliance for an explosion-preventing plant area by an underground metal network cathode. The protective method for an explosion-preventing plant area by an underground metal network cathode has the essential that a sacrificial anode step-by-step drainage is buried along an underground pipeline at underground ends of a buried pipe network and a device pipeline; the close packing crossed buried steel pipe network is connected with a high-density equalizer, a deep well impressed current anode ground bed is arranged under the ground of the periphery of the explosion-preventing plant area, a shallowly buried impressed current anode ground bed is arranged under the ground of the explosion-preventing plant area or the position approaching a first stage explosion-preventing area, and sacrificial anode ground beds are arranged continuously or at intervals along the side of the trend of the pipe network under the ground in the explosion-preventing plant area; the cathodic protection of all the direction of the buried steel pipe network, a sheath cable, a metal ground network and a metal fixture is carried out; an explosion-preventing facility is added on the shallowly buried anode ground bed. On-site explosion-preventing detection is carried out by an LSB-1 type explosion-preventing appliance.

Description

Explosion-proof plant area buried metal network cathode protecting process

The present invention relates to the galvanic protection of buried metal network, be particularly useful for explosion-proof plant area buried steel pipe network, bury ground tape armored cable net, the galvanic protection of ground net and underground metal structures thereof.

At present; the cathode protection technology of buried metal network; cathode protection technology as the steel pipe network; often be applied to buried steel pipeline or non-explosion-proof plant area simple buried steel pipe road or other buried metal structures of the foreign minister of plant area distance; and as usual isolated flange or insulation facility are being installed on the buried pipeline or on other buried metal structures; object of protection and non-object of protection are carried out electrically completely cutting off, implement the regional galvanic protection of plant area's buried metal facility.This technology can suppress the corrosion of object of protection effectively, prolongs its work-ing life, guarantees production equipment safety, reliability service.

But, adopt above-mentioned conventional art to carry out galvanic protection with regard to being difficult to for explosion-proof plant area buried metal network.Its reason is: (1) explosion-proof plant area; especially petrochemical complex plant area underground pipe netting index amount is huge; its numerous end is electrical connected with uphole equipment with going out; by cathode protection technology requirement in the past; for electrically isolated, must hold at each pipeline with going out the insulation facility is installed carrying out between underground pipe net and the uphole equipment.Both costed height and be difficult to enforcement, made troubles to maintenance of equipment again.When (2) adopting impressed current cathodic protection, following situation is difficult to avoid: the insulating property of a certain isolated flange or the insulation facility galvanic protection collection that the produced electric current that becomes that lost efficacy flows to equipment through this isolated flange or insulation facility, makes equipment charged; The both sides moment short circuit of perhaps a certain isolated flange or insulation facility produces discharge spark.Unsafe factor by above-mentioned situation produces has limited in the explosion-proof plant area of petrochemical complex and has adopted isolated flange in a large number.When (3) intensive steel pipe network in ground and the coexistence of other buried metal structure are buried by plant area; when adopting impressed current cathodic protection to bury the intensive pipe network in ground; can be to buried steel pipeline or other buried metal structure nearby, (as tape armored cable) causes stray current corrosion, produces unnecessary side effect.(4) when when depth of soil is implemented impressed current cathodic protection less than 10 meters explosion-proof plant area; the earth electric field of its shallow ground bed can produce potential difference being embedded between any 2 metal constructions of this electric field; it is step voltage; in case between structure moment short circuit, this voltage may produce discharge spark and ignite inflammable gas.

The objective of the invention is in order to overcome the drawback of above-mentioned buried metal network cathode protection technology; break the convention of " facility that do not insulate does not just have galvanic protection "; the cathode protection technology of a kind of explosion-proof plant area buried metal network is provided, realizes galvanic protection explosion-proof plant area buried metal network.

Explosion-proof plant area provided by the invention buried metal network cathode protection technology, its main points be the underground pipe net, install pipes lower edge, ground end ground pipeline rout continuously or the compartment of terrain bury sacrificial anode current drainage step by step underground, with the protective current of the equipment that flows to through pipeline that successively decreases, it is 10～30 meters that every pair of sacrificial anode is buried spacing distance underground; For eliminating the side effect of the stray current corrosion that impressed current cathodic protection produces, adopt highly dense equalizer lead technology, promptly the buried steel pipe network that intersects for solid matter is arranged closely-spaced, the high-density equalizer lead of connection along underground pipe, and connects equalizer lead in underground pipe net point of crossing; Divide into deep-well power impressed anode bed in explosion-proof plant area peripherally, in explosion-proof plant area or divide into shallow embedding power impressed anode groundbed with closing on the explosion-proof district of one-level, be about to 3～20 power impressed anode groundbeds, continuously or at interval (10～50 meters) in the shallow embedding soil, be connected in series with cable, the explosion-proof district of explosion-proof plant area or one-level lower edge, ground pipe network trend nearby continuously or the compartment of terrain establish the sacrificial anode groundbed, every group of sacrificial anode groundbed is spaced apart 20～130 meters, with the vertical range of pipeline be 1.5～5 meters, by above-mentioned three kinds of groundbeds, apply the cathodic protection current that impressed current combines with sacrificial anode to the buried steel pipe network; To the position of intensive pipe network of plant area and the coexistence of other buried metal structure, implement omnibearing galvanic protection, promptly buried steel pipe network, tape armored cable, metal ground net, metal structures are electrically connected; To being positioned at explosion-proof plant area or closing on the explosion-proof plant area of one-level, build the safety anti-explosive facility less than 10 meters shallow embedding power impressed anode bed at buried depth.For guaranteeing whole cathodic protection system in the safe operation of explosion-proof plant area, be equipped with the explosion-proof testing apparatus of a kind of LSB-1 type and measure step voltage and short-circuit current, carry out on-the-spot explosion-proof test.

The explosion-proof testing apparatus of LSB-1 type, by a upper and lower ends volumetric flask of cock is housed respectively, the cock upper end connects a sampling courage, the cock lower end is connected with an equilibration flask, two the side mouths in the top of volumetric flask are equipped with rupture disk and two elastic electrodes respectively, external two earthing poles of electrode are connected with a test signal lamp between electrode and earthing pole, voltmeter and two-way switch are formed.

Above-mentioned buried steel pipe network cathodic protection potential controlling valu is-0.85V～-1.05V; Impressed current system feeding point current potential is not defeated by-1.5V; Bury ground carbon steel test piece protection degree＞90%; Bury ground tape armored cable cathodic protection potential controlling valu and be-0.85～-1.20V; The cathodic protection potential of ground net is born the value of moving＞200mV.

Compare with buried metal network cathode protection technology in the past; advantage of the present invention is: break fresh ground (1); do not establish isolated flange or insulation facility at cathodic protection system; both saved manufacturing, the installation costs of a large amount of isolated flanges or insulation facility, also avoided by the unsafe factor that numerous isolated flanges or insulation facility bring is installed.(2) the high-density equalizer lead technology that provides, bury sacrificial anode and Lian Xing formula shallow ground bed technology nearby continuously and at interval underground along pipeline rout; can overcome the shielding effect each other by intensive buried steel pipe network and the generation of other buried metal structure of anticathode protective current; the side effect to the stray current corrosion of buried steel pipe network or other buried metal structure that can overcome that impressed current system itself produces, can successively decrease flows to the cathodic protection current of equipment and the unsafe factor that causes thus on the ground along the underground pipe net.(3) the explosion-proof testing apparatus of LSB-1 type that provides is carried out the test and the safety analysis of step voltage and short-circuit current and is built the safety precaution facility technology, can guarantee that cathodic protection system is in the safe operation of explosion-proof plant area.(4) can implement explosion-proof plant area buried steel pipe network and other buried metal structure and structures are carried out comprehensive galvanic protection; To plant area and explosion-proof plant area do not adopt galvanic protection as yet but the heavier old buried steel pipe network of corrosion, adopt present technique can suppress corrosion, prolong its work-ing life, avoid changing pipeline substantially.

Embodiment:

In the explosion-proof plant area of a super-huge petro-chemical fiber company, floor space is 2 square kilometres, its underground steel water transfer pipe network, tape armored cable network, red copper ground net, metal structures that are embedded with intensive intersection.Wherein the water transfer pipe network length overall is 59 kilometers, and caliber has tens kinds of specifications from Dg25mm to Dg1100mm, buries ground 15 years, does not adopt cathode protection technology as yet, because of the leakage that corrosion causes is risen year by year, and serious threat production.Adopt explosion-proof plant area provided by the invention metalolic network cathode protection technology; establish deep well anode land bed 6 at explosion-proof plant area periphery; its well depth is 20～30 meters; establish 39 of shallow embedding groundbeds in explosion-proof plant area; be about to 3～20 power impressed anode groundbeds continuously and at interval in (10～50 meters) shallow embedding soil; with the cable serial connection, be and connect the distribution of star formula.Simultaneously with 251 groups of sacrificial anode groundbeds, every group of 50～120 meters of spacing (different and different according to pipe network density, the high more spacing of density is more little), along the buried steel pipe trend continuously or the compartment of terrain be distributed in the pipe side, with the vertical range of pipeline be 1.5～5.0 meters.Be connected 300 of high-density equalizer leads on 2～10 parallel and the buried steel pipes that intersect, facing two equalizer lead spacings mutually is 30～100 meters.19 of potentiostats are installed, are used to the power impressed anode groundbed that cathodic protection current is provided.And with the buried steel pipe network, bury ground tape armored cable net, copper ground net, metal structures and electrically connect one; carry out comprehensive galvanic protection; after putting into operation after tested; all do not have the current potential phenomenon of shuffling, i.e. galvanic protection itself produces the side effect of stray current corrosion to buried steel pipe network and other buried metal structure.On shallow ground bed, build safety anti-explosive facility 32 places that form by fine sand, asphalt felt, concrete square brick; use the explosion-proof testing apparatus test of LSB-1 type step voltage; and carry out on-the-spot explosion-proof test, confirm to implement step voltage that impressed current cathodic protection produced inflammable gas that can not ignite in this explosion-proof plant area.When using the explosion-proof testing apparatus of above-mentioned LSB-1 type, earlier equilibration flask is full of red color water, open two-way cock and three-way tap and connect atmosphere, inflate air to volumetric flask, close three-way tap, make it lead to the position of the courage of taking a sample, in proportion inflammable gas is charged into volumetric flask, cut-out tap is inserted the different location with two ground-electrodes then successively, from voltmeter direct-reading step voltage value, and observe and to light bulb.In addition, switch two-way switch, produce spark, ignite inflammable gas, determine that can the step voltage of this place's earth electric field ignite inflammable gas with two silver electrodes moment contact in the bottle.33518.5 square metres of the above-mentioned explosion-proof plant area underground pipe net total areas, after the enforcement galvanic protection, pipe-to-soil potential is defeated by-0.85V, and the area that reaches protection fully is 31021.4 square metres, accounts for 92.6%.Bury ground tape armored cable current potential for-1.11V～-1.12V, copper ground net current potential is-0.72V～-1.47V.It is 92.4% that carbon steel buries ground test piece protection degree, has reached buried metal network galvanic protection control techniques index.

Claims (1)

1, a kind of explosion-proof plant area buried metal network cathode protecting process is characterized in that:

A) bury sacrificial anode current drainage step by step underground continuously or at interval at underground pipe net, lower edge, the ground end ground pipeline rout that installs pipes, it is 10～30 meters that every pair of sacrificial anode is buried spacing distance underground;

B) at solid matter intersection underground pipe net, row connects the high-density equalizer lead closely-spacedly along underground pipe, connect equalizer lead in underground pipe net point of crossing, divide into deep-well power impressed anode groundbed in explosion-proof plant area peripherally, in explosion-proof plant area or divide into shallow embedding power impressed anode groundbed with closing on the explosion-proof plant area of one-level, power impressed anode groundbed spacing distance is 10～50 meters, near explosion-proof plant area or lower edge, one-level explosion-proof plant area ground pipeline rout, continuous or compartment of terrain is buried the sacrificial anode groundbed underground, every group of sacrificial anode groundbed is spaced apart 20～130 meters, with the vertical range of pipeline be 1.5～5 meters, and to the buried steel pipe network, bury the ground tape armored cable, metal ground net, the metal structures electrically connect, implement comprehensive galvanic protection, buried steel pipe network cathodic protection potential controlling valu is-0.85V～-1.05V, impressed current system feeding point current potential is not defeated by-1.5V, bury ground carbon steel test piece protection degree＞90%, bury ground tape armored cable cathodic protection potential controlling valu for-0.85V～-1.20V, the cathodic protection potential of ground net is born the value of moving＞200mV;

C), build the safety anti-explosive facility on the power impressed anode groundbed less than 10 meters latent burying at buried depth in explosion-proof plant area or close on the explosion-proof plant area of one-level.