CN104003422A - Mother liquor recovery new process - Google Patents

Abstract

The invention discloses a mother liquor recovery new process. The process adopts the traditional quadruple-effect vacuum salt production and brine mixing cooling mirabilite redissolution technologies. The brine does not need purification and can undergo steam washing. The condensate water of an I effect evaporation tank and an II effect evaporation tank undergoes flash evaporation and then returns to a boiler, and the condensate water of an III effect evaporation tank and an IV effect evaporation tank undergoes heat exchange with original brine through a plate heat exchanger, and the residual heat is recovered. Salt-leached old brine undergoes brine removal and purification. The purified refined bittern is taken as the raw material of a 300 system. The 300 system utilizes the principle that within a certain temperature range, the solubility of NaCl increases with temperature rise and the solubility of Na2SO4 decreases with temperature rise, through certain amount of feed liquid circulation, mirabilite can be precipitated under high temperature, and salt can be precipitated under low temperature, thereby realizing co-production of salt and mirabilite.

Description

Mother liquor absorption method novel process

Technical field

The present invention relates to well mine salt production field, the salt manufacturing that the saltcake type bittern of particularly take is raw material.

Background technology

The raw brine of China's vacuum salt production mainly contains gypsum model (CaSO ₄) and saltcake type (Na ₂sO ₄) two kinds, wherein saltcake type bittern occupies the majority.For gypsum model bittern, because of CaSO ₄solubleness lower, by chemical process, removing is also feasible from seeing economically, even if do not purify, adopting gypsum seed method is also mature and reliable; And for saltcake type bittern, due to its Na ₂sO ₄content is generally all higher, cannot even carry out bittern purifying, conventionally also just remove calcium, the magnesium addition in bittern economically chemically except it, therefore in the production of saltcake type bittern, be substantially all to adopt physical method to realize solventing-out.

Traditional saltcake type bittern vacuum salt production all adopts converts halogen cooling back dissolving saltcake technique, for the high caldo after the desalinization of soil by flooding or leaching (being commonly called as old halogen), or discharging kill-job or carries nitre.Kill-job discharge not only causes the waste of resource and heat energy, and pollution incident also easily occurs, and the mode of carrying nitre mainly contains three kinds, and frozen saltpeter mention, hot method are carried nitre, mother liquor absorption method is carried nitre (coproduction of common name sal prunella).Its ultimate principle is all to utilize Na ₂sO ₄in the time of 17.9 ℃, solubleness is maximum, Yi Cidianwei circle, and temperature raises or declines, Na ₂sO ₄solubleness all correspondingly declines, thereby according to NaCl-Na ₂sO ₄-H ₂o ternary system phasor, changes NaCl-Na ₂sO ₄thereby the temperature of saturated solution changes its system point, realize salt, nitre separation.

Numerous domestic saltcake type bittern manufacturing enterprise adopts the mother liquor absorption method sal prunella coproduction of quadruple effect (also having five effects) vacuum salt production or introduction more at present.Vacuum salt production reduced investment, simple to operate, but salt matter is not high, can not meet modern society's demand more and more higher to salt matter, and wasted the mirabilite resource in bittern and easily polluted.Mother liquor absorption method sal prunella coproduction sal prunella quality is good, resource utilization is high, but investment is large, and bittern purifying cost is high.

Summary of the invention

The object of the invention is in order to provide a kind of hot method by the mother liquor absorption method of introduction and native country to put forward the mother liquor recovery novel process that nitre organically blends.

Mother liquor reclaims a novel process, comprises the following steps:

Step 1, raw brine advection after plate-type heat exchanger and water of condensation heat exchange enters 200 system I, II, III, IV effect evaporating pot is EV201, EV202, EV203, EV204, and raw steam enters heating chamber HE201.

The secondary steam that step 2, bittern evaporation produce enters next effect heating chamber successively, salt slurry adopts salt-draining of parallel flow mode from I effect, to drain into successively that II effect, II effect drain into III effect, III effect drains into IV effect, IV effect salt slurry is extracted out by blowdown pump, and after swirler, 200 systems are flowed back on swirler top.

Step 3, swirler underflow go centrifuge dehydration, dry metering packing again to obtain product salt by the floating device of washing after former halogen washing, floatingly wash device overflow and isolate after glauberite through heavy salt device, settling vessel, and clear liquid goes old halogen purification.

Step 4, purify the V effect evaporating pot EV205 that old halogen enters 200 systems after plate-type heat exchanger and water of condensation heat exchange, proceed to again nitre evaporating pot EV301, after the part secondary steam suction that raw steam produces EV301 by vapor jet pump mixes, enter nitre heating chamber HE301.

The feed liquid of step 5, EV301 enters flash evaporation tank EV302, flash evaporation tank EV303 successively, after shwoot, remove EV205, the part secondary steam that EV301 produces and the steam of EV302 shwoot is successively by interchanger HE306, HE305 and feed liquid heat exchange, and nitre slurry goes centrifuge dehydration, be dried and obtain nitre product through metering packing.

The secondary steam of the flash steam of step 6, EV303 and 200 system IV effect evaporating pot EV204 enters heating chamber HE205 jointly, and the secondary steam of EV205 enters mixing condenser, the feed liquid of EV205 enters EV301 after preheater HE305, preheater HE306 heat up, and the salt slurry of EV205 obtains high-quality refined salt through centrifuge dehydration, dry, metering packing.

Beneficial effect of the present invention: 1, investment: because mother liquor absorption method novel process purified brine amount is only the 1/3-1/4 of perhalogeno purge amount, therefore the more former technique of bittern purifying device is much smaller; Again because without the Na preventing in tank ₂sO ₄separate out and turn in a large number material, thus chuck needn't be set, thus tank type is simple, and diameter is less, and although novel process has increased desalinization of soil by flooding or leaching system, investment is little, and equipment manufacturing cost is still much lower; Gross investment can reduce more than 20%.

2, cost: because bittern purifying amount is much smaller, and unit bittern purifying cost is roughly suitable, the more former technique of novel process ton product bittern purifying cost declines many; The more former technology investment volume of novel process is much lower again, and annual interest and year depreciation difference are larger.The more former technique of novel process can reduce running cost more than 10 yuan/ton.

Accompanying drawing explanation

In order to be illustrated more clearly in technical scheme of the present invention, below the accompanying drawing of required use during the present invention is described is briefly described.

Fig. 1 is implementing process schema of the present invention;

Embodiment

As shown in Figure 1, the recovery of the mother liquor described in the present embodiment novel process comprises the following steps:

S1, raw brine advection after plate-type heat exchanger and water of condensation heat exchange enters 200 system I, II, III, IV effect evaporating pot is EV201, EV202, EV203, EV204, and raw steam enters heating chamber HE201.

The secondary steam that S2, bittern evaporation produce enters next effect heating chamber successively, salt slurry adopts salt-draining of parallel flow mode from I effect, to drain into successively that II effect, II effect drain into III effect, III effect drains into IV effect, IV effect salt slurry is extracted out by blowdown pump, and after swirler, 200 systems are flowed back on swirler top.

S3, swirler underflow go centrifuge dehydration, dry metering packing again to obtain product salt by the floating device of washing after former halogen washing, floatingly wash device overflow and isolate after glauberite through heavy salt device, settling vessel, and clear liquid goes old halogen purification.

S4, purify the V effect evaporating pot EV205 that old halogen enters 200 systems after plate-type heat exchanger and water of condensation heat exchange, proceed to again nitre evaporating pot EV301, after the part secondary steam suction that raw steam produces EV301 by vapor jet pump mixes, enter nitre heating chamber HE301.

The feed liquid of S5, EV301 enters flash evaporation tank EV302, flash evaporation tank EV303 successively, after shwoot, remove EV205, the part secondary steam that EV301 produces and the steam of EV302 shwoot is successively by interchanger HE306, HE305 and feed liquid heat exchange, and nitre slurry goes centrifuge dehydration, be dried and obtain nitre product through metering packing.

The secondary steam of the flash steam of S6, EV303 and 200 system IV effect evaporating pot EV204 enters heating chamber HE205 jointly, and the secondary steam of EV205 enters mixing condenser, the feed liquid of EV205 enters EV301 after preheater HE305, preheater HE306 heat up, and the salt slurry of EV205 obtains high-quality refined salt through centrifuge dehydration, dry, metering packing.

Illustrate:

1, according to the mother liquor absorption method constructive accounting of introducing, multiple-effect evaporation salt making system is called to 200 systems, solventing-out system is called 3200 systems.In 200 systems, unsaturated because of the saturated Na2SO4 of NaCl of bittern, in evaporative process, NaCl separates out, and Na2SO4 is constantly concentrated, discharges, therefore only produce salt in 200 systems when Na2SO4 is concentrated into approach when saturated with mother liquor.The mother liquor that 200 systems are discharged enters 300 systems, utilize the positive dissolution characteristics (rising of solubility with temperature and increase) of NaCl and the contrary dissolution characteristics of Na2SO4 (rising of solubility with temperature and reduce), by mother liquor systemic circulation, realizing high temperature analyses nitre and does not analyse salt, low temperature is analysed salt and is not analysed nitre, the coproduction of common name sal prunella, realizes solventing-out in 300 systems by physical method, not only produces salt but also produce nitre.

2, the same, according to English alphabet, write a Chinese character in simplified form, evaporating pot is represented with EV, heating chamber, interchanger represent with HE, and move towards with numeric sorting by technique, as EV201 represents the first evaporator rooms of imitating of 200 systems, HE301 represents the nitre heating chamber of 300 systems.

Positively effect of the present invention: 200 systems of mother liquor absorption method novel process adopt traditional multiple-effect evaporation salt manufacturing, and salt matter guarantees by the desalinization of soil by flooding or leaching.Old halogen after the desalinization of soil by flooding or leaching removes to make smart halogen and as the raw material of 300 systems, 300 systems are identical with former technique.Below the old and new's technique is compared, basic identical because of 300 systems, only 200 systems and bittern purifying are made comparisons.

1. investment: for novel process, one is because the raw brine of 200 systems is without purification, according to Na in bittern ₂sO ₄the difference of content, old halogen purge amount is about the 1/3-1/4 of perhalogeno purge amount, and bittern purifying investment is saved over half; It is two because without the Na preventing in tank ₂sO ₄separate out and turn in a large number material, thus chuck needn't be set, thus tank type is simple, and diameter is less, and although novel process has increased desalinization of soil by flooding or leaching system, investment is little, and equipment manufacturing cost is still much lower; It can not implement a minute effect preheating (if adopt three-phase flow technology or other preventing fouling, this technique is also feasible) three because not adopting bittern purifying, only in low-temperature zone, uses efficient plate-type heat exchanger, therefore reduced the investment of minute effect preheating.Generally speaking, the more former technique of novel process reduces investment more than 20%.

2. quality: the quality product of 300 systems is roughly suitable, and the salt matter of novel process 200 systems is lower, but in the face of the high-quality reality of favorable rates not necessarily, the quality-advantage of former technique can not embody completely.

3. energy consumption: to turn material amount less due to novel process 200 systems, after heat, move just few, the utilization of condensation water residual heat in addition, although do not adopt a minute effect preheating, total energy consumption level and former technique roughly quite or slightly high (3%), for Na ₂sO ₄the raw brine that content is higher, because needn't turn in a large number material from 200 higher systems of heat utilization efficiency, novel process comprehensive energy consumption even may be lower than former technique.

4. working cost: take that to build the mother liquor absorption method production equipment of a set of 600,000 tons/year be example:

A, bittern purifying expense: because the CaSO4 major part in former halogen is separated out with the form of glauberite in 200 systems, compare with former halogen, CaSO4 content in old halogen declines, MgSO4 content rises, unit bittern purifying cost is roughly suitable, by halogen consumption 3.5m3/ ton product, 3 yuan of unit bittern purifying costs, old halogen purge amount is that 1/3 of perhalogeno purification is got, 7 yuan/ton of products of the more former technique decline of novel process bittern purifying cost.

B, the interest on investment and depreciation: the more former technology investment volume of novel process is at least low 3,000 ten thousand yuan, annual interest is saved 196.5 ten thousand yuan (annual rate is got by 6.55%), year depreciation difference=3000**95%/10 year=2,850,000 yuan.

Ten thousand yuan of Interest spread+depreciation difference=481.5

Unit interest and depreciation decline 481.5/60=8 yuan/ton

C, energy consumption: former technique ton product comprehensive energy consumption is got by 120kg mark coal, and novel process ton product increases the about 3.6kg of mark consumption of coal, and cost increases approximately 3.6 yuan/ton.

D, working cost add up to: the more former technique of novel process can reduce by 11.4 yuan/ton of running costs, approximately 6,800,000 yuan of year saving working costs.

Realization in order to demonstrate the invention, has described above-mentioned embodiment.But other variations of the present invention and modification, be apparent for those skilled in the art, any modification/variation within the scope of essence disclosed in this invention and fundamental principle or imitation conversion all belong to claim protection domain of the present invention.

Claims (1)

1. mother liquor reclaims a novel process, it is characterized in that, comprises the following steps:

Step 1, raw brine advection after plate-type heat exchanger and water of condensation heat exchange enters 200 system I, II, III, IV effect evaporating pot is EV201, EV202, EV203, EV204, and raw steam enters heating chamber HE201.

The secondary steam that step 2, bittern evaporation produce enters next effect heating chamber successively, salt slurry adopts salt-draining of parallel flow mode from I effect, to drain into successively that II effect, II effect drain into III effect, III effect drains into IV effect, IV effect salt slurry is extracted out by blowdown pump, and after swirler, 200 systems are flowed back on swirler top.

Step 3, swirler underflow go centrifuge dehydration, dry metering packing again to obtain product salt by the floating device of washing after former halogen washing, floatingly wash device overflow and isolate after glauberite through heavy salt device, settling vessel, and clear liquid goes old halogen purification.

Step 4, purify the V effect evaporating pot EV205 that old halogen enters 200 systems after plate-type heat exchanger and water of condensation heat exchange, proceed to again nitre evaporating pot EV301, after the part secondary steam suction that raw steam produces EV301 by vapor jet pump mixes, enter nitre heating chamber HE301.

The feed liquid of step 5, EV301 enters flash evaporation tank EV302, flash evaporation tank EV303 successively, after shwoot, remove EV205, the part secondary steam that EV301 produces and the steam of EV302 shwoot is successively by interchanger HE306, HE305 and feed liquid heat exchange, and nitre slurry goes centrifuge dehydration, be dried and obtain nitre product through metering packing.

The secondary steam of the flash steam of step 6, EV303 and 200 system IV effect evaporating pot EV204 enters heating chamber HE205 jointly, and the secondary steam of EV205 enters mixing condenser, the feed liquid of EV205 enters EV301 after preheater HE305, preheater HE306 heat up, and the salt slurry of EV205 obtains high-quality refined salt through centrifuge dehydration, dry, metering packing.