CN1026975C - Water reusing technology and equipment by lime processing of dregs - Google Patents

Abstract

The present invention relates to a technological system and a special device thereof for reusing slag of softening water by lime. The technological system comprises a water processing system, a calcination system and a digesting and emulsion preparing system of calcined lime. Compared with the prior art, the technological system has the advantages of simplicity, small occupation area, low cost of operation and construction, easy realization of automatization, safe and reliable operation and high utilization rate of slag. The special rapid reactor of the water processing system can complete softening and separation in one step; the technological system has the advantages of simplified technology, high slag purity and good quality of discharged water.

Description

Water reusing technology and equipment by lime processing of dregs

The present invention relates to the softening treatment process of lime and the equipment of water.

The lime treatment of water is a kind of method of more employing in the water softening processing technology field both at home and abroad, its advantage is: the wide material sources of lime, waste is solid and is convenient to dispose, the problem that does not have the polluted underground water source, but, owing to use block lime, utilization ratio has only about 40%, bed drain purge is big, make newborn system complex, disadvantage such as staff's operational condition difference and make this technology be difficult to promote the use of is if use high purity powdery slaked lime, domestic source of goods deficiency, be restricted again in the application, in No. 4017391 patents of U.S. Tan Dun Running-water Company application on July 6th, 1976, proposed a kind of unboiled water that combines with chemical processing system and given treatment system, this system carries out water treatment with lime, the mud of discharging is separated and recovery, contain lime carbonate in the mud, magnesium hydroxide and other foreign material, this mud through carbonization, flotation, some steps such as dehydration, then the lime carbonate clod of separating is sent into the calcination system, calcination becomes lime to recycle.Magnesium hydroxide in the mud forms the Magnesium hydrogen carbonate of dissolved form after carbonization, again through steps such as decarburization, dehydration, oven dry, make Magnesium Carbonate Light 41-45 and sell.The advantage of this process system is big to the subject range of unboiled water water quality, but recovery system complexity, floor space is big, working cost and construction cost height, restive, performance difficulty, the unslaked lime purity that reclaims the deslagging calcination low (general CaO content is about 93%), the conveying of mud material and calcination difficulty, flue gas band dust is serious, contaminate environment.

In view of there is aforesaid disadvantage in the lime treatment system of water in the prior art, difficulty is applied, and the lime treatment deslagging that the present invention proposes a kind of new water utilizes process system and dedicated water treatment facility again, and emphasis solves following problem:

1. the lime treatment of water exists a large amount of deslagginves to handle problems, and present method can make the deslagging recycling more than 90% turn waste into wealth, and can solve the source problem that comes of high purity lime, also has part to remain high purity unslaked lime simultaneously and can supply export trade.

2. the process system of prior art is (as U.S. Tan Dun Running-water Company, see also annex) the deslagging recovery method, reclaim problem though can solve deslagging, but complex process working cost and construction investment are too big, performance difficulty, present method can make water softening processing and sediment be separated in the water treating equipment and finish simultaneously, not needing ad hoc separation system and deslagging is particulate matter, the purity height, be convenient to carry and calcination, do not contain dust in the smoke evacuation substantially, method is simple, reliable, floor space is little, and operation, construction cost is low.

3. employing present method also can be improved operator's working conditions, operator is in operation does not contact lime, realizes automatization easily, and operating safety, reliable.

4. present, reactor both domestic and external to go out water suspension higher, generally at 70-100ppm, thereby increased the burden of filter plant, cause difficulty to the invention provides a kind of novel flashing reactor to operation, can use water suspension and be lower than 10ppm, and deslagging density height (CaO content can reach 99%), uniform particles (d=2mm).

Now design of the present invention and technical solution are described below:

Content of the present invention relates to the lime treatment unboiled water and the method for recycling use again of the deslagging after handling, and the dedicated water treatment facility for realizing that present method designs.

The principle of present method foundation is: precipitation reaction of carbonate hardness such as reaction formula 1., 2. with the secondary reaction formula 3.:

The CaCO that discharges ₃Precipitation is through calcination, as reaction formula 4.

Again CaO is digested, make milk of lime, 5. as reaction formula

Present method comprises the following steps:

1. (hereinafter to be referred as reactor) mixed with milk of lime after water entered flashing reactor 1, and the control concentration of reactants produces lime carbonate, and the granular particle of separating out is dammed softening water from the outflow of reactor top, and realization lime carbonate separates with water.

2. from the effusive soft water in reactor 1 top, filter, remove the suspended substance in anhydrating, adjust about pH value to 7.5 supply and demand water department again through neutralizer 4 through filter 3.

3. the lime carbonate sediment of discharging from reactor bottom enters the deslagging pond, sends into raw material case 10 behind the draining, sends into roasting system by feeding machine 11 again and carries out calcination.

4. sediment produces relative mobilely with flue gas in the calcination tube of rotary kiln 12, and is burnt by section and to resolve into unslaked lime, and the unslaked lime of heat cools off through cooling cylinder, enters unslaked lime case 14 and utilizes and bury scraper plate and send into unslaked lime retention tank 16.

5. with feeding machine 17 unslaked limes in the unslaked lime retention tank 16 are sent into and digested in the high-temperature digester 18 and be diluted into 5% milk of lime, enter milk of lime agitator tank 19 again, utilize injector 20 that milk of lime is delivered in the reactor then.

6. unnecessary unslaked lime is stored and is treated pin.

In order to guarantee to have in the reactor preferably grain through distributing and helping the carrying out of crystallisation process, present method has taked alternate mode to add crystal seed and discharging sediment, degree of supersaturation for conditioned reaction device bottom lime carbonate, thereby reach the crystallization velocity of control lime carbonate, the crystallization that guarantees lime carbonate is carried out on crystal seed basically, present method is by reactor reflux pump 2, a part of Returning reactor with the reactor water outlet, improved the reactor effluent quality, in order to obtain the milk of lime of good dispersity, present method has adopted wet method thermophilic digestion system breast, the milk of lime of this good dispersity can be accelerated the carrying out of the softening reaction in the reactor 1, has also improved the effective rate of utilization of lime.Simultaneously, by taking after the above three measures, can guarantee to go out the uniform particles of water suspension in the reactor 1 less than the 10ppm deslagging.

In grain burning system, send into the lime carbonate sediment of rotary kiln baking.Its optimum calcination temperature is 1050 ℃, and the compactedness of material is 10～15%.

The preparation of lime slurry, present method has adopted wet method thermophilic digestion mode, in the thermophilic digestion process, the control water cement ratio is about 3: 1, earlier quicklime slaking is become the lime white of 30% left and right sides concentration, and then towards rare one-tenth desired concn, like this lime slurry good dispersity of Huo Deing, active high, and residual volume is few.In addition, in digestion and storage process, carry out suitable stirring, can obtain fine and smooth lime hydrate emulsion.In high-temperature digester, material temperature is controlled at 90～100 ℃ and gets final product.

Now that description of drawings is as follows:

Fig. 1: the lime treatment deslagging of water utilizes the method system diagram again.

Wherein:

1. flashing reactor

2. reflux pump

3. strainer

4. neutralizer

5. sour volume pump

6. sour storagetank

7. softening water tank

8. softening water pump

9. deslagging pond

10. raw material case

11. feeding machine

12. rotary kiln

13. crystal seed injects and preparation system

14. unslaked lime case

15. transfer roller

16. unslaked lime case

17. feeding machine

18. high-temperature digester

19. milk of lime agitator tank

20. milk of lime injector

21. water

22. outer water supply

23. from water

24. fuel

Cooperate method of the present invention, the present invention has also designed special-purpose water treating equipment-flashing reactor, it is characterized in that:

The bottom of reactor is a cone, be provided with lime milk intlet pipeline 25, slag-drip opening 26 crystal seeds add inlet 27 and recirculation water import 28, the reactor middle part is a right cylinder, top is loudspeaker, the top is a bending dome 29, top and top weldering are one, become full closeding state, home position from reactor head, the inlet channel 30 of a straight-through reactor bottom is housed, inlet channel 30 is separated by a distance with the reactor cone base, a ring pipe is housed in the totally-enclosed body on reactor top, circulating line 31 is provided with four and enters oral pore 32, on ring pipe, establish two outlet water pipes 33, stretch out outside the reactor from reactor top horn body, as the softening water water outlet, between the top and bottom of reactor, reactor reflux pump 34 in parallel, a part of Returning reactor with the reactor water outlet, thereby reached control, the crystallization velocity of conditioned reaction device bottom lime carbonate guarantees that the crystallization of lime carbonate is carried out basically on crystal seed, improved the purpose of the effluent quality of reactor, the lime milk intlet pipeline penetrates from reactor bottom cone inclined-plane, enters in the center inlet channel 30, and stretches to the reactor cone base with inlet channel 30.

Now that description of drawings is as follows:

Fig. 2: flashing reactor structure iron.

Wherein:

25. lime milk intlet pipeline

26. slag-drip opening

27. crystal seed adds inlet

28. recirculation water import

29. bending dome

30. inlet channel

31. circulating line

32. water-in

33. softening water rising pipe

34. reflux pump

Now technical economic benefit of the present invention is described below:

1. conserve water resource:

At present, the water loss of China thermal power plant and other industrial sectors all is higher than international most advanced level, this China that comparatively lacks for water source of fresh water is urgent problem, power station and other industrial sector water loss the best parts are industrial colling, want to reduce the water yield loss of industrial colling, just must improve the repeat usage of this part water, the concentration rate of cooling water system is improved.After the water coolant concentration rate improves, just must take measures areput, otherwise the production economic benefit of power plant or other industrial sectors is descended.

With 1,200,000 kilowatts fuel-burning power plant is example, adopts the lime treatment ratio to add acid treatment, the stability series method is handled, but every day about 20,000 tons of conserve water, present method will have been created condition for industrial sector extensively adopts lime treatment.

2. working cost is low:

This processing method is close with employing outsourcing high purity slaked lime powder processing method initial cost, and its working cost and waste water and dregs quantity discharged see the following form.

The lime treatment method comparison sheet of two kinds of water of table 1

The use high purity disappears

This process system of project

The lime powder system

Outsourcing purity is 80%

619 tons of/month 0(self-sufficiencies)

Slaked lime

10000 tons 200 tons of annual bed drain purges

2,150,000 yuan 1,050,000 yuan of annual operating costs

10290 tons/month 720 tons/month of wastewater discharges

0 160 tons/month of the unslaked limes of confession export trade

Annotate:

1. the slaked lime powder of purity 80% is by 160 yuan/ton (comprising freight charges);

2. press 250 yuan/ton for the unslaked lime of export trade;

3. handle 3500 tons/hour of the water yields, year operation 7000 hours;

4. meter because the transportation of deslagging and deposit the increase expense;

5. unboiled water water quality: basicity 4.45 equivalent parts per millions, calcium 3.6 equivalent parts per million magnesium 1.2 equivalent parts per millions.

3. reliability height

Present method is compared with the technology that adopts the high purity slaked lime powder, and the variation (9.5～11.5) of present method pH value in the operational process does not have influence substantially to going out water suspension, and the latter then influences seriously.Simultaneously, the unslaked lime of this process system calcination in pelletized form, and is mobile fine, metering is convenient, and the latter is because restive to excess water, usually excessive because of moisture content in the production process, make its mobile decline, cause the lime metering system to stop up, bring difficulty to operation.

Now the embodiment with present method exemplifies as follows:

Four 300,000 kilowatts of generating set of Zou County, Shandong power plant, the recirculated cooling water and the process water of power plant adopt this process system, and handling the water yield is 4000 tons/hour.

One. present method can reach index:

1. water treatment system:

1. water outlet water is held:

Suspended substance is less than 1ppm

About basicity 0.5epm

The lime carbonate rate of recovery is greater than 90%

2. this water quality can make the concentration rate of power plant's circulating cooling system water bring up to 5.0 times, compare with methods (2.5 times of concentration rates) such as adding sour stability series, every day, but conserve water was about 20000 tons, adopted additive method also can produce phreatic pollution problem.

2. calcination system

The unslaked lime purity of deslagging calcination is greater than 95%;

The quicklime slaking speed of deslagging calcination was less than 1 minute;

The thermo-efficiency 45% of rotary kiln;

It is for sale to remain 171 tons of unslaked limes in every month.

Two. working cost

Present method is compared with adopting outsourcing high purity slaked lime powder process system, and initial cost is close, running cost such as following table:

Two kinds of processing method comparison sheets of table 2 Shandong Zou County power plant

The use high purity disappears

Project present method

Lime powder technology

707 tons/month 0 of 80% slaked lime powder consumptions

11400 tons 800 tons of annual bed drain purges

2,460,000 yuan 1,200,000 yuan of annual operating costs

11760 tons/month 823 tons/month of wastewater discharges

0 171 tons/month of many surplus amount of lime

Claims (2)

1, the softening treatment process of a kind of lime of water comprises:

1), water joins flashing reactor and mixes with milk of lime, controls reactant concn by the following step, the calcium carbonate granule of separating out is discharged from reactor lower part, the water that is softened flows out from reactor top.

2), from the effusive soft water in reactor top, filter, adjust pH is to being essentially 7.5, send calcination system from the lime carbonate sediment of reactor lower part discharge.

3), the hot unslaked lime that generates of calcining back sends into high-temperature digester and is diluted into 5% milk of lime after cooling, enters agitator tank again, with injector milk of lime is delivered in the reactor.

It is characterized in that:

1), the part of reactor water outlet is returned above-mentioned reactor by reflux pump,

2), take discontinuous manner to add crystal and discharging sediment,

3), wet method thermophilic digestion time control water cement ratio is essentially 3: 1, and quicklime slaking become to be essentially the lime white of 30% concentration, again towards rare to desired concn, and in digestion and storage process, offset milk of lime and stir, and the temperature of charge in the control digestive organ conversion zone is at 90-100 ℃

2, the water treating equipment of special use in a kind of method according to claim 1 have reactor cavity, and its bottom is a cone, and the middle part is a right cylinder, and top is hydraucone, and the top is the bending dome,

It is characterized in that:

1), the inlet channel of a straight-through reactor bottom is housed at the reactor head home position, and separated by a distance with the reactor bottom cone,

2), reactor bottom is provided with lime milk intlet pipeline, slag-drip opening, crystal seed and adds inlet and recirculation water import,

3), a ring pipe is housed in the totally-enclosed body on reactor top, four water-ins are established in the ring pipe top, also have two water outlets to draw outside the reactor on the ring pipe,

4), between the top of reactor and bottom a reactor reflux pump in parallel,

5), the lime milk intlet pipeline passes from reactor bottom cone side, enter in the inlet channel at center, and stretch to the reactor cone base together with pipeline.

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