CN207699696U - Heat-exchange system in a kind of the PE electrolytic cells and slot of included exhaust system - Google Patents

Abstract

The utility model is heat-exchange system in the PE electrolytic cells and slot of a kind of included exhaust system, is one kind of metallurgy industry electrolysis installation.It carries out the heating of electrolyte with included exhaust system and heat-exchange system, cool down and the absorption emission problem of toxic gas improves working environment to improve heat exchanger effectiveness, it is horizontal to improve electrolytic refining process.The utility model is made of electrolytic cell ontology, exhaust system and heat-exchange system, electrolytic cell ontology includes groove body, liquid in-out nozzle, into return water nozzle and cover board, the groove body is made of groove body shell, insulating layer, chan frame and groove body inner casing, the exhaust system includes exhaust entrance, exhaust exit pipe, air exhaust passage, drain pipe and valve, and air exhaust passage is placed in upper part of the electrolytic cell both sides.The heat-exchanging tube bundle that the heat-exchange system main body is made of more fluoroplastics thin micro tubes, it is respectively water inlet pipe and return water inlet tube and return water nozzle that heat-exchanging tube bundle, which has vertically and horizontally protect-ing frame structure, upper end protection cap and limiting plate, both ends,.The utility model is purified metals for electrorefining.

Description

Heat-exchange system in a kind of the PE electrolytic cells and slot of included exhaust system

Technical field

The utility model is related to metallurgy industry electrolysis installation, specifically a kind of included row to purify metals for electrorefining Heat-exchange system in the PE electrolytic cells and slot of gas system.

Background technology

The economy of enterprise is imitated in further attention with the development and country of new material to environmental protection, in addition energy-saving and emission-reduction The influence of benefit proposes that increasingly higher demands, including the heat-exchange system of electrolysis installation, electrolysis are set to the electrolysis installation of metallurgy industry The design of standby exhaust emission system, electrolytic cell proposes that more scientific and reasonable requirement, specific requirement are：It is simple in structure, be easy to Processing and operation, corrosion-resistant, durable, sealing good exhaust effect, are easy to heat exchange heat preservation, environmental protection, adaptable spy at light weight Point requires.

Currently, since traditional metal material (such as carbon steel, stainless steel, titanium) heat exchanger is in strong acid alkalinity and strong oxidizing property It is easy to corrosion and scaling in heat exchange system and the influence for the unfavorable factors such as service life is short, teflon heat exchanger is wanted with the epoch It asks and comes into being.Teflon heat exchanger has been developed in recent years for the anti-corrosion heat transmission equipment in strong corrosive medium, at present Research mainly as high effective flue gas heat exchange equipment heat exchange element, for fume afterheat depth recycling and further dedusting, Achieve gratifying effect.Teflon heat exchanger is used as heat exchange material using fluoroplastics, mainly since fluoroplastics are with excellent Performance, such as：(in addition to molten metal sodium and liquid fluorine, it is resistant to all acid, alkali, salt and other one with splendid corrosion resistance Cut chemicals), surface non-stick (surface is not easy to stain fouling, have automatic cleaning action), the good (temperature in use of heat resistance In -200~200 DEG C of ranges), ageing-resistant performance is good and service life is grown (outdoor service life is up to 20 years), light weight, friction The advantages that coefficient is small.

The research of teflon heat exchanger is concentrated mainly on the heat exchange element of high effective flue gas heat exchange equipment, develops novel fluorine Plastic heat exchanger equipment has been the hot spot of domestic and international researcher research.But teflon heat exchanger is used as to be electrolysed for metallurgy industry And the fluoroplastics of the heat exchange process of the constant high temperature or permanent low temperature requirements in plating production in electrolytic cell with deep-etching electrolyte Pipe heat exchanger has not been reported.Chemical inert material teflon heat exchanger is not special to heated solution acid and alkali corrosion system It is required that the heat exchanger for making large capacity constant volume deep-etching liquid of fluoroplastics thin micro tube has broad application prospects.

Electrolyte needed for electrolytic process due to metallurgy industry is nearly all the electrolyte solution of strong acid property, in electricity A large amount of toxic gas can be discharged in solution preocess, as electrolytic chlorination cobalt liquor, nickel chloride solution, nickel sulfate solution, copper nitrate are molten Liquid, copper-bath etc., these electrolyte except itself there is highly acid to discharge volatility toxic gas (such as HCl, HNO₃、H₂SO₄ Deng) outside, while since a large amount of toxic gas caused by anode reduction reaction releases (such as Cl in electrolytic process₂、 SO₂、NO、NO₂Etc. hypertoxicities gas), if be discharged not in time, prodigious influence or even electric can be caused on electrolytic production quality Solution does not go out metal product, if discharge in time cannot be handled effectively in absorption, is partially or completely discharged into the air of production scene In environment, the situation that not only results in the deterioration of production on-site environment or even cannot normally produce, while also seriously threatening The health even life of operating personnel.In addition higher and higher to the requirement of environmental protection at present, in electrolysis production absolutely not Allow toxic gas to be discharged into operation site space and extraneous air, it is therefore necessary to ensure that in electrolytic process Anodic The toxic gas of plate by-product is extracted out by negative pressure in electrolytic cell in time, and in time by outside workshop absorption tower absorb it is up to standard after ability It is discharged in air outside.Therefore, design that must be effective and reasonable in electrolysis production is electrolysed produced toxic gas in time from electrolytic cell Outside interior discharge and electrolytic cell in time and the device for absorbing tail gas that fully absorbs, it is ensured that in electrolytic cell produced poison gas do not accumulate, workshop Benign electrolytic environments situation of the space without poison gas escorts for electrolysis production normalization and has important practical significance.

To prevent toxic gas in electrolytic process from discharging into the atmosphere, the most direct method mostly used is in electrolytic cell On add reduction cell cover plate.Although in a cell poison gas short time inner sealing, there are following drawbacks for cover board：First, electricity The a large amount of of the produced poison gas of solution lodge in electrolytic cell, destroy the electrolytic equilibrium of anode and cathode, are easily formed polarization potential, improve slot Voltage reduces electrolytic efficiency；Second is that the accumulation of a large amount of poison gases causes prodigious influence to electrolytic production quality or is even electrolysed not Go out metal product；Third, in electrolytic cell poison gas a large amount of accumulations, also poison gas can be made to be easy to leak, especially to being operated in slot When (such as tankage peace electrode plate unloads the measurement that slot goes out product, tank voltage), the enrichment poison gas explosion type in slot largely discharges, sternly Ghost image rings the health of environment and operating personnel.To prevent toxic gas in electrolytic process from discharging into the atmosphere, also have using whole A workshop surrounding installs exhaust system, although in the case where adding capping on electrolytic cell, exhaust system makes plant operations environment It makes moderate progress, but without the substantive drawback solved from source present in only dress electrolytic cell capping.

In smelting electrolytic process, single bulky electrolytic cell equipment and by multiple (dozens or even hundreds of) electrolysis In the electrolysis production system of slot composition, since electrolytic cell body is with cement, the cement lining (macromolecules such as anti-rot plastic, resin Material), steel construction groove body lining (high molecular materials such as anti-rot plastic, resin), even currently also have the anti-rot plastic etc. used Material makes, this electrolytic cell is bulky, it is heavy, pick and place inconvenience, an electrolytic cell weight up to several tons even more than ten tons, Some attachmentes are especially added on electrolytic cell to be not easy very much.

Also in research and practice exhaust system is directly arranged, poison gas is discharged into later in the person that has practical work on electrolytic cell Air is handled by absorption tower absorption.Include that the exhaust system of exhaust outlet is set on electro bath-lid and in electrolytic cell lateral layout The exhaust system of exhaust outlet.The exhaust system of exhaust outlet is arranged in the former on electro bath-lid, due to capping be integral and by Steel plate line with rubber or steel plate plastic-spraying make, and are designed with lifting lifting lug, this capping is bulky, it is heavy, picked and placeed by driving, Therefore the exhaust system design occurred in capping is inconvenient, and nozzle is mutually connected in movable, and it is primary to pick and place capping, accordingly arranges The nozzle in air port connects dismounting once；The latter occurs in the exhaust system of electrolytic cell lateral layout exhaust outlet directly in electrolytic cell Lateral opening hole is simultaneously mounted to gas vent, since exhaust hole number and effectively exhaust sectional area are limited, be easy to cause in exhaust pipe and The tiny structure area formed in slot is uneven, into exhaust pipe in entrainment it is serious, into what is carried secretly in the useless poison gas in exhaust pipe Electrolyte increases, and causes the discharge for the electrolyte carried secretly in useless poison gas and slatterns.

Due to developing by leaps and bounds for high pure metal material, the required electrolytic cell proposition that electrorefining purifies high pure metal is higher It is required that be innovated, improved and be transformed on the basis of conventional electrolysis slot, the development need of high pure metal is just adapted to, is had Body is presented as：It is corrosion-resistant, small volume is light, durable, easy processing and manipulation, be easy to heat exchange and heat preservation, environmental protection (including Material environmental protection and in time discharge poison gas environment environmental protection) etc. need and require.

To sum up described in technical background, according to the demand for development of current electrolysis industry, a kind of tool for electrorefining is developed There are the novel environment friendly PE electrolytic cells that heat-exchange system and exhaust system are integrated, has important practical significance.

Invention content

According to the demand for development of current electrolysis industry, the utility model provide it is a kind of for electrorefining, it is simple in structure, It is easy to process, easy to operation use, heat-exchange system in durable and included exhaust system PE electrolytic cells and slot, to adapt to electricity Solve the requirement of refinery practice.

To realize that above-mentioned target, the utility model use following technical proposals, the PE electrolytic cells and slot of exhaust system are carried Interior heat-exchange system includes electrolytic cell ontology, liquid in-out nozzle, into return water nozzle and underflow nozzle, and composition further includes exhaust system System and heat-exchange system, electrolytic cell ontology include groove body and reduction cell cover plate, and the groove body is by groove body shell, insulating layer, channel steel frame Frame and groove body inner casing are constituted, and the liquid inlet and outlet nozzle on groove body is connect with the electrolyte circulating slot (not shown) in the slot ontology external world, Underflow nozzle is connect with lean liquid tank or waste liquid tank (not shown), set on water inlet pipe on groove body and backwater outlet pipe in electrolytic cell One end connect respectively with the water inlet pipe of heat exchanger and backwater outlet pipe, water inlet pipe and backwater outlet pipe are outside electrolytic cell One end is connect with the outlet tube mouth and return water nozzle of heat transferring medium heating tank or cooling bath (not shown) respectively；The exhaust system It is placed in electrolytic cell upper lateral part, including exhaust entrance, exhaust exit pipe, air exhaust passage and air exhaust passage drain pipe and valve, air draft It is equipped with exhaust entrance on the inside of channel, is communicated with groove body inner cavity, one end of air exhaust passage is equipped with exhaust exit pipe and is taken out with outside electrolytic cell Gas system is connected, and the other end is equipped with air exhaust passage drain pipe and valve, its main body of the heat-exchange system is placed in the fluorine in groove body Type plastic tube heat exchanger, the heat-exchanging tube bundle that the main body of heat exchanger is made of more fluoroplastics thin micro tubes, heat-exchanging tube bundle both ends There are vertical protect-ing frame structure, bottom to there is horizontal protect-ing frame structure, tube bank bottom to have upper end protection cap, supported and fixed by limiting plate, into Water pipe and backwater outlet pipe respectively in electrolytic cell water inlet pipe and backwater outlet pipe connect.

Compare with existing equipment, the beneficial effects of the utility model are：1, the utility model with exhaust system and changes Hot systems obtain very high heat exchange effect due to selecting fluoroplastics thin micro tube to make heat-exchanging tube bundle, and with optimum tube diameter value Rate；Due to being equipped with exhaust system, the toxic gas generated in electrolytic process enters air exhaust passage by exhaust inlet pipe, then by being vented Outlet enters extract system, and subsequently into exhaust treatment system, qualified discharge realizes heat exchange heat preservation and exhaust integrated section Energy, environmentally friendly purpose and effect, significantly improve working environment, have ensured the physical and mental health of operator；2, simple in structure, it is easy to Processing and manufacturing；3, material therefor is PE plastics, light-weight, operates light, corrosion-resistant, durable, long lifespan.

Description of the drawings

Heat-exchange system assembling schematic diagram in Fig. 1-PE electrolytic cells and slot

Fig. 2-heat exchanger structure schematic diagram

Fig. 3-the utility model PE electrolytic cell front views

Fig. 4-the utility model PE electrolytic cell left views

A-A sectional views in Fig. 5-Fig. 4

B-B sectional views in Fig. 6-Fig. 5

Fig. 7-electrolytic cell axonometric drawing

Fig. 8-chan frame axonometric drawing

Drawing explanation：

In Fig. 1：1- heat-exchange system 2- electrolytic cell ontology 3- exhaust systems

In Fig. 2：The vertical protect-ing frame structure of 4- water inlet pipe connecting flange 5- return pipe connecting flange 6- heat-exchanging tube bundles 7- The horizontal upper ends the protect-ing frame structure 11- limiting plates 12- limiting plates center poling slot 13- protection caps of 8- circular hole 9- thin micro tubes 10- Plate

In Fig. 3：14- groove body shell 15- insulating layer 16- groove body inner casing 17- chan frame 18- feed liquor nozzle flanges 19- feed liquor nozzle 20- connecting flange 21- connecting flange 22- backwater outlet pipe 23- air exit pipe flanges 24- is vented out Mouth pipe 25- air exhaust passage 26- exhaust entrance 27- reduction cell cover plate 28- busbar import 29- air exhaust passage drain pipes Valve 30- air exhaust passage drain pipe 31- water inlet pipe 32- water inlet pipe connecting flange 33- outlet tube mouth 34- outlet tubes Mouth flange 35- underflow nozzle 36- underflow nozzle flanges

In Fig. 4：19- feed liquor nozzle 18- feed liquor nozzle flange 14- groove body shell 20- connecting flange 22- backwater outlets Pipe 30- air exhaust passage drain pipe 29- air exhaust passage drain tube valve 23- air exit pipe flange 24- exhaust exit pipes

In Fig. 5：25- air exhaust passage 37- cathode conductive bus bar supporting plane 31- water inlet pipe 32- water inlet pipes connect The 23- exhausts of flange 33- outlet tube mouth 34- outlet tube mouth flange 38- anode conducting busbar supporting plane 25- air exhaust passages Export pipe flange 24- exhaust exit pipe 18- feed liquor nozzle flange 19- feed liquor nozzle 20- connecting flange 22- backwater outlets Pipe 26- exhaust entrance 23- air exit pipe flange 24- exhaust exit pipe 21- connecting flange 39- water inlet pipe connection methods It is blue

In Fig. 6：31- water inlet pipe 32- water inlet pipe connecting flange 35- underflow nozzle 36- underflow nozzle flanges 16- Groove body inner casing 15- insulating layer 17- chan frame 14- groove body shell 34- outlet tube mouth flange 33- outlet tube mouths 29- rows Wind channel drain tube valve 30- air exhaust passage drain pipe 25- air exhaust passage 23- air exit pipe flanges

In Fig. 7：23- air exit pipe flange 19- feed liquor nozzle 18- feed liquor nozzle flange 20- connecting flanges 22- is returned Water outlet pipe 23- air exit pipe flange 24- exhaust exit pipe 14- groove body shell 35- underflow nozzle 30- air exhaust passages Drain pipe 29- air exhaust passage drain tube valve 25- air exhaust passage 31- water inlet pipe 33- outlet tube mouth 38- anode conductings Busbar supporting plane 39- water inlet pipe connecting flange 28- busbar import 26- exhaust entrance 24- exhaust exit pipes

In Fig. 8：16- groove body inner casing 17- chan frames

Specific implementation mode

Illustrate specific embodiment of the present utility model below in conjunction with the accompanying drawings, as shown in Figure 1, the utility model includes electrolysis Slot ontology 2, exhaust system 3 and heat-exchange system 1, the electrolytic cell ontology 2 include groove body (as shown in Figure 3), feed liquor nozzle 19, go out Liquid pipe mouth 33, feed liquor nozzle 19 by feed liquor nozzle flange 18, outlet tube mouth 33 by outlet tube mouth flange 34 with outside groove body Electrolyte circulating slot (not shown) be connected, the one end of water inlet pipe 31 and backwater outlet pipe 22 in electrolytic cell passes through connection method Orchid 39 and 21 connect with the water inlet pipe connecting flange 4 of heat-exchange system in electrolytic cell and return pipe connecting flange 5 respectively, water inlet The one end of pipe 31 and backwater outlet pipe 22 outside electrolytic cell is added with heat transferring medium outside electrolytic cell respectively by connecting flange 32 and 20 The outlet tube mouth of heat channel or cooling bath (not shown) is connected with return water nozzle；Underflow nozzle 35 by underflow nozzle flange 36 with it is poor Liquid bath or the connection of waste liquid tank (not shown)；The electrolytic cell ontology 2 is by groove body shell 14, insulating layer 15, groove body inner casing 16, channel steel Frame 17 and reduction cell cover plate 27 constitute (as shown in Figure 3), and groove body inner casing 16 and groove body shell 14 are all made of certain thickness PE Plastic plate makes, welding forming, and the PE tubing that the pipeline being connect with slot ontology 2 is all made of certain diameter makes；The insulating layer 15 are folded between groove body shell 14 and chan frame 17, are made of thermal insulation material；The chan frame 17 is folded in outside groove body Between shell 14 and groove body inner casing 16, to improve the integral strength and rigidity of cell body, the upper end to 25 lower face of air exhaust passage Until, form cathode and anode conducting busbar supporting plane 37 and 38.The exhaust system 3 is placed in the top of electrolytic cell ontology 2 Both sides, including exhaust entrance 26, exhaust exit pipe 24, air exhaust passage 25 and air exhaust passage drain pipe 30 and valve 29, air draft are logical It is equipped with exhaust entrance 26 on the inside of road, is communicated with groove body inner cavity, one end of air exhaust passage is equipped with exhaust exit pipe 24 and air exit Pipe flange 23 is connected with extract system (not shown) outside electrolytic cell, and the other end is equipped with air exhaust passage drain pipe 30 and valve 29, with The connected (not shown) of recovered liquid collecting tank outside electrolytic cell；The air exhaust passage 25 is cuboid, along its length suspension setting In the outside of the cathode and anode conducting busbar supporting plane 37 and 38 of groove body side surface upper part, air exhaust passage 25 and conductive bus bar branch It supports and is equipped with busbar import 28 in the middle part of the groove body side between plane 37,38, the air exhaust passage 25 is in one along its length Determine gradient installation, one end of exhaust exit pipe 24 is high, and one end of air exhaust passage drain pipe 30 is low, in favor of gas-liquid separation.Air draft The certain thickness PE plastic plates welding production in channel.The fluoroplastics tubular type that its main body of the heat-exchange system is placed in groove body is changed Hot device, the U-shaped heat-exchanging tube bundle 6 that the core of heat exchanger is made of more fluoroplastics thin micro tubes 9,6 both ends of heat-exchanging tube bundle There are the vertical protect-ing frame structure 7 of cuboid, 6 bottoms of tube bank to have the horizontal protect-ing frame structure 10 of cuboid, 6 bottom surface level of tube bank, which is laid with part, to be had Upper end cover sheet 13, restraining 6 bottom horizontal portions has the horizontal limiting plate 11 that is laid with to support fixation, vertical protect-ing frame structure 7, level Multiple array circular holes 8 are provided on protect-ing frame structure 10, upper end cover sheet 13 and limiting plate 11, protection, limit in favor of tube bank With efficient heat exchange.Water inlet connecting flange 4 on heat exchanger is connect by water inlet pipe connecting flange 39 with water inlet pipe 31 (shown in Fig. 5), return pipe connecting flange 5 are connected by the connecting flange 21 on backwater outlet pipe 22.The thin micro tube 9 is used Polytetrafluoroethylene material makes, and caliber is within the scope of 4-10mm, and PFA materials also can be used in pipe thickness≤1.0mm, thin micro tube It makes.The limiting plate 11 of 6 bottom of the heat-exchanging tube bundle has 1-8, is equally spaced, and makes heat-exchanging tube bundle right through limiting plate center Poling notch.The tubulation number of every, the heat exchanger is 50 1 500, and 1-3 heat exchanger can be placed side by side in an electrolytic cell. Vertical protect-ing frame structure 7, horizontal protect-ing frame structure 10, upper end cover sheet 13 and the limiting plate 11 of the heat-exchanging tube bundle 6 use fluoroplastics It makes, vertical protect-ing frame structure 7, the heat expansion of horizontal protect-ing frame structure 10 at 6 both ends of heat-exchanging tube bundle fuse welding manner connection, and upper end is protected Protecting cover plate 13 is also welded to connect with heat expansion fusion with 10 upper end of horizontal protect-ing frame structure.

The technique connection of the utility model component part is as follows：Electrolysis in the extraneous electrolyte circulating slot of electrolytic cell ontology 2 Liquid enters electrolytic cell under the action of infusion pump by feed liquor nozzle 19, and the heat transferring medium in heat transferring medium slot (not shown) is being infused The outlet tube of heat transferring medium slot is passed sequentially through under pumping action, water inlet pipe 31, the heat exchanger water that electrolytic cell outside is connected to inside Inlet tube 4 enters in U heat exchange beam 6, and the return water outlet pipe being connected to by heat exchanger return pipe 5, electrolytic cell inner side and outer side 22 flow to the return water nozzle of heat transferring medium slot, finally enter in heat transferring medium slot, and the Bi Shi of heating (or cooling) is circulated throughout again Journey realizes the heat exchange of electrolyte and heat transferring medium.The toxic gas generated in electrolytic process is close reduction cell cover plate 27 Under the conditions of envelope, due to the suction function of extract system (not shown) outside electrolytic cell, pass through exhaust entrance 26, air exhaust passage 25 and row Gas outlet 24 enters extract system, finally enters exhaust treatment system processing, realizes qualified discharge, to make in electrolytic cell To heat exchange heat preservation and exhaust integrated function.

Claims (7)

1. heat-exchange system in the PE electrolytic cells and slot of a kind of included exhaust system, including electrolytic cell ontology, liquid in-out nozzle, into returning Hose nozzle and underflow nozzle, it is characterised in that further include exhaust system and heat-exchange system, the electrolytic cell ontology (2) includes groove body With reduction cell cover plate (27), groove body is by groove body shell (14), insulating layer (15), chan frame (17) and groove body inner casing (16) structure At, the one end of water inlet pipe (31) and backwater outlet pipe (22) in electrolytic cell on groove body respectively with the water inlet pipe of heat exchanger Connecting flange (4) and return pipe connecting flange (5) connection, water inlet pipe (31) and backwater outlet pipe (22) outside electrolytic cell one End is connect with heat transferring medium slot respectively, and the exhaust system (3) is placed in electrolytic cell upper lateral part, including exhaust entrance (26), exhaust Outlet (24), air exhaust passage (25) and air exhaust passage drain pipe (30) and valve (29), air exhaust passage (25) inside are equipped with row Gas entrance (26) is communicated with groove body inner cavity, and one end of air exhaust passage (25) is equipped with exhaust exit pipe (24), is evacuated with outside electrolytic cell System is connected, and the other end is equipped with air exhaust passage drain pipe (30) and valve (29)；Described its main body of heat-exchange system (1) is placed in slot Internal fluoroplastics pipe heat exchanger, the heat-exchanging tube bundle that the main body of heat exchanger is made of more fluoroplastics thin micro tubes (9) (6), heat-exchanging tube bundle (6) both ends have vertical protect-ing frame structure (7), bottom to have horizontal protect-ing frame structure (10), tube bank bottom to have upper end guarantor Protecting cover plate (13) is supported to fix by limiting plate (11), water inlet pipe and backwater outlet pipe respectively with the water inlet in electrolytic cell Pipe is connected with backwater outlet pipe.

2. heat-exchange system in PE electrolytic cells according to claim 1 and slot, it is characterised in that groove body shell (14) and groove body Inner casing (16) uses certain thickness PE plastic plates welding forming.

3. heat-exchange system in PE electrolytic cells according to claim 1 and slot, it is characterised in that insulating layer (15) is folded in slot Between body case (14) and chan frame (17).

4. heat-exchange system in PE electrolytic cells according to claim 1 and slot, it is characterised in that chan frame (17) is folded in Between groove body shell (14) and groove body inner casing (16).

5. heat-exchange system in PE electrolytic cells according to claim 1 and slot, it is characterised in that air exhaust passage (25) is along length It is installed in constant slope in direction.

6. heat-exchange system in PE electrolytic cells according to claim 1 and slot, it is characterised in that thin micro tube (9) uses polytetrafluoro Vinyl material is manufactured, and caliber is pipe thickness≤1.0mm within the scope of 4-10mm.

7. heat-exchange system in PE electrolytic cells according to claim 1 and slot, it is characterised in that the limiting plate of tube bank (6) bottom It is 1-8, is equally spaced.