Production process of anhydrous spherical calcium chloride

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a production process of anhydrous spherical calcium chloride by using epichlorohydrin production wastewater. The invention provides an economical and reasonable route for effectively utilizing the epichlorohydrin production wastewater, the problem that a feeding pipe is often blocked by an air ring hole edge during feeding granulation of a tower-type bottom air ring hole in the prior art is effectively solved, and the product is good in spheroidization effect, stable in shape and high in yield. Meanwhile, the problem of wastewater treatment of epichlorohydrin production enterprises is solved, the subsequent sewage treatment cost is saved, waste is turned into wealth, the value of circular economy is embodied, and the method has great popularization and application value.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a production process of anhydrous spherical calcium chloride using wastewater produced by epichlorohydrin. Background Art

[0002] Epichlorohydrin is an important organic chemical raw material, mainly used in the preparation of glycerin, epoxy resin, epichlorohydrin rubber, polyether polyols, and an important raw material for the production of glycerin and glycidol derivatives. It is an important organic synthetic raw material and intermediate. The wastewater produced in the production process of epichlorohydrin by the glycerol method contains a large amount of free calcium ions, which will combine with free chloride ions to form calcium chloride. Therefore, it is very necessary to extract calcium chloride from the wastewater produced in the production process of epichlorohydrin as an industrial raw material.

[0003] For example, the Chinese patent document with application number CN01141607.6 discloses a production process of granular calcium chloride and its spheroidizing granulation bed. The process is that the raw material liquid is washed, preheated, evaporated, and then granulated in a special equipment spheroidizing granulation bed, and then dried and cooled to produce granular calcium chloride. Granular calcium chloride is mainly produced by evaporation, but the shape of the granular calcium chloride is not stable. In the past, the tower-type bottom wind ring hole feeding granulation often caused the "long nose" of the wind ring hole edge to cause the feed pipe to be blocked; the product spheroidization was not good; and a large number of seed crystals were easily produced. Unqualified products with crushed particle size are required.

[0004] Therefore, it remains to be further developed to develop a production process that can stably and efficiently utilize epichlorohydrin production wastewater to produce anhydrous spherical calcium chloride. Summary of the invention

[0005] The object of the present invention is to provide a production process of anhydrous spherical calcium chloride, so as to optimize the process of extracting calcium chloride from wastewater generated by producing epichlorohydrin, reduce the cost of wastewater treatment, effectively reduce the cost of extracting calcium chloride, and improve production efficiency.

[0006] To achieve the above-mentioned object of the invention, the present invention provides a production process of anhydrous spherical calcium chloride, which specifically comprises the following steps:

[0007] S1: The wastewater generated during the production of epichlorohydrin is filtered through a filter press to obtain a calcium chloride clear solution;

[0008] S2: preheating and concentrating the calcium chloride solution obtained in step S1 to obtain saponified solution I;

[0009] S3: The saponified liquid I obtained in step S2 is sequentially fed into a demisting washing tower and a spray washing tower through a delivery pump for concentration to obtain saponified liquid II;

[0010] S4: The saponified liquid II obtained in step S3 is pumped to the evaporation system, purified by triple-effect evaporation to obtain saponified liquid III, which is then sent to the boiling granulation tower;

[0011] S5: The saponified liquid III, under the action of the delivery pump, passes through the liquid phase loop pipe of the boiling granulation tower and the gas phase loop pipe of the compressed air, and then enters the atomizing nozzle of the feeding section of the boiling granulation tower to form a calcium chloride atomized liquid. The calcium chloride atomized liquid is dried and granulated by hot air under the action of the spherical calcium crystal seeds in the boiling granulation tower and the blower of the boiling granulation tower to form anhydrous spherical calcium chloride;

[0012] S6: the anhydrous spherical calcium chloride formed in step S5 is discharged from the discharge port at the bottom of the boiling granulation tower;

[0013] S7: The anhydrous spherical calcium chloride is sorted by particle size through a rotary screen, and the anhydrous spherical calcium chloride particles that do not meet the standards are crushed by a crusher to form small particles of calcium chloride as spherical calcium seeds for granulation;

[0014] S8: The spherical calcium seeds prepared in step S7 enter from the top of the boiling granulation tower through gas transport under the action of a Roots blower, and the powdered calcium chloride entrained by the gas in the tower is spirally captured from top to bottom and sprayed out through the nozzle inside the tower, and combined with the calcium chloride atomized liquid entering from the atomizing nozzle, and the gas is discharged from the top of the tower.

[0015] Furthermore, in step S1, the calcium chloride content in the calcium chloride clear solution is 15-16%.

[0016] Furthermore, in step S2, the calcium chloride content in the saponification solution I is 27-28%.

[0017] Furthermore, in step S3, the calcium chloride content in the saponification solution II is 33-35%.

[0018] Furthermore, in step S4, the calcium chloride content in the saponification solution III is 50-55%.

[0019] Furthermore, in step S5, the liquid phase loop pressure of the boiling granulation tower is 0.05-0.25 MPa, and the gas phase loop pressure is 0.35-0.45 MPa.

[0020] Furthermore, the air inlet pressure of the blower in the boiling granulation tower is 7.0-8.0 KPa, and the hot air temperature is 350-450°C.

[0021] Furthermore, the hot air entering the boiling granulation tower is in a rotating state during the granulation process.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The invention provides an economical and reasonable route for effectively utilizing wastewater from epichlorohydrin production, effectively solving the problem that the edge of the wind ring hole often causes the feed pipe to be blocked during the feeding granulation of the wind ring hole at the bottom of the tower, and the product has good spheroidization effect, stable shape and high yield. At the same time, it solves the wastewater treatment problem of epichlorohydrin production enterprises, saves subsequent sewage treatment costs, realizes the transformation of waste into treasure, embodies the value of circular economy, and has great promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 : is the production process flow chart of anhydrous spherical calcium chloride of the present invention. DETAILED DESCRIPTION

[0025] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0026] like Figure 1 As shown, a production process of anhydrous spherical calcium chloride specifically comprises the following steps:

[0027] S1: The wastewater generated in the production process of epichlorohydrin is filtered through a filter press to obtain a calcium chloride clear liquid which is stored in an intermediate tank. The calcium chloride content in the calcium chloride clear liquid is 15-16%.

[0028] S2: In step S1, the obtained calcium chloride clear liquid enters the evaporator from the intermediate tank for preheating and concentration, and then the secondary steam produced by heating is recovered and used as a heating heat source for the existing epichlorohydrin saponification tower; and the saponification liquid I (calcium chloride aqueous solution) obtained after preheating enters the calcium chloride evaporator, and the calcium chloride content therein is 27-28%.

[0029] S3: In step S2, the obtained saponified liquid I is sequentially fed into a demisting washing tower and a spray washing tower through a delivery pump for concentration. The demisting washing tower absorbs secondary hot air from the spray washing tower through circulation, and the spray washing tower absorbs secondary hot air from the boiling granulation tower through circulation to obtain saponified liquid II, which effectively saves energy. The calcium chloride content in the saponified liquid II is 33-35%.

[0030] S4: In step S3, the saponified liquid II is pumped to the evaporation system, purified by triple-effect evaporation in the positive generation system to obtain saponified liquid III, and the calcium chloride content in the saponified liquid III is increased to 50-55%, and then sent to the boiling granulation tower.

[0031] S5: The saponified liquid III, under the action of the delivery pump, passes through the liquid phase loop (0.05-0.25MPa) of the boiling granulation tower and the gas phase loop (0.35-0.45MPa) of the compressed air, and then enters the atomizing nozzle of the feeding section of the boiling granulation tower. Under the action of compressed air, the saponified liquid III enters the boiling granulation tower in the state of calcium chloride atomized liquid after passing through the atomizing nozzle. The calcium chloride atomized liquid and the spherical calcium crystal seeds in the boiling granulation tower and the blowing machine of the boiling granulation tower are dried and granulated by hot air to form anhydrous spherical calcium chloride; and according to the control principle of the pressure regulation of the blower inlet in the boiling granulation tower, the air inlet pressure is controlled to be 7.0-8.0KPa and the hot air temperature is 350-450°C. The hot air entering the tower is in a rotating state during the granulation process, so that the powdered calcium chloride and the spherical calcium crystal seeds formed in the tower can better form qualified anhydrous spherical calcium. At the same time, the hot air rotation in the boiling tower effectively solves the problem that the feed pipe is often blocked by the edge of the wind ring hole in the bottom wind ring hole of the tower during feeding granulation, and the product spheroidization effect is good.

[0032] The hot air temperature in the boiling granulation tower and the concentration of the saponified liquid III directly affect the size of the product spherical particles, and the qualified standard particle size of the product is preferably 3-6mm. Preferably, when the hot air temperature in the boiling granulation tower is 350°C, at the same concentration, the hot air temperature decreases by 5°C, and the spherical particle size of the product increases; on the contrary, when the temperature in the tower increases by 5°C, the spherical particle size of the product decreases. When the inlet air temperature of the granulation tower is reduced by 20°C, the content of ball calcium will decrease, resulting in an increase in the unqualified rate of the same batch of products.

[0033] S6: In step S5, the finished product of anhydrous spherical calcium chloride is discharged from the discharge port at the bottom of the boiling granulation tower, and the discharge speed of the anhydrous spherical calcium chloride is controlled by frequency conversion of a star-shaped feeder arranged at the discharge port;

[0034] S7: The anhydrous spherical calcium chloride is sorted by particle size at the rotary screen; the discharged anhydrous spherical calcium chloride with qualified particle size is packaged in the packaging silo, and the anhydrous spherical calcium chloride with particle size that does not meet the standard will be crushed by the crusher to form small particles of calcium chloride, which will be used as spherical calcium crystal seeds for granulation.

[0035] S8: The spherical calcium crystal seeds enter from the top of the boiling granulation tower through gas transportation under the action of the Roots blower, and form a spiral from top to bottom inside the boiling granulation tower to capture the powdered calcium chloride entrained by the gas in the tower, and then spray it out through the nozzle inside the tower. The spherical calcium crystal seeds are combined with the calcium chloride atomized liquid entering from the atomizing nozzle, and are dried and granulated by hot air to form anhydrous spherical calcium chloride; the gas is preferably air. Finally, the gas is discharged from the top of the tower, with a discharge pressure of 1.5-1.8KPa and a temperature of 165-172°C, and enters the subsequent washing tower. That is, the anhydrous spherical calcium chloride finally produced has no unqualified products, and the production wastewater of epichlorohydrin can be fully utilized.

[0036] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0037] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A production process for anhydrous spherical calcium chloride, characterized in that, The specific steps include: S1: The wastewater generated during the production of epichlorohydrin is filtered through a filter press to obtain a calcium chloride clear solution; S2: preheating and concentrating the calcium chloride solution obtained in step S1 to obtain saponified solution I; S3: The saponified liquid I obtained in step S2 is sequentially fed into a demisting washing tower and a spray washing tower through a delivery pump for concentration to obtain saponified liquid II; S4: The saponified liquid II obtained in step S3 is pumped to the evaporation system, purified by triple-effect evaporation to obtain saponified liquid III, which is then sent to the boiling granulation tower; S5: The saponified liquid III, under the action of the delivery pump, passes through the liquid phase loop pipe of the boiling granulation tower and the gas phase loop pipe of the compressed air, and then enters the atomizing nozzle of the feeding section of the boiling granulation tower to form a calcium chloride atomized liquid. The calcium chloride atomized liquid is dried and granulated by hot air under the action of the spherical calcium crystal seeds in the boiling granulation tower and the blower of the boiling granulation tower to form anhydrous spherical calcium chloride; S6: the anhydrous spherical calcium chloride formed in step S5 is discharged from the discharge port at the bottom of the boiling granulation tower; S7: The anhydrous spherical calcium chloride is sorted by particle size through a rotary screen, and the anhydrous spherical calcium chloride particles that do not meet the standards are crushed by a crusher to form small particles of calcium chloride as spherical calcium seeds for granulation; S8: The spherical calcium seeds prepared in step S7 enter from the top of the boiling granulation tower through gas transport under the action of a Roots blower, and the powdered calcium chloride entrained by the gas in the tower is spirally captured from top to bottom and sprayed out through the nozzle inside the tower, and combined with the calcium chloride atomized liquid entering from the atomizing nozzle, and the gas is discharged from the top of the tower.

2. The production process of anhydrous spherical calcium chloride according to claim 1, wherein In step S1, the calcium chloride content in the calcium chloride clear solution is 15-16%.

3. The production technology of anhydrous spherical calcium chloride according to claim 1, characterized in that, In step S2, the calcium chloride content in the saponification solution I is 27-28%.

4. The production technology of anhydrous spherical calcium chloride according to claim 1, characterized in that, In step S3, the calcium chloride content in the saponification solution II is 33-35%.

5. The production technology of anhydrous spherical calcium chloride according to claim 1, characterized in that, In step S4, the calcium chloride content in the saponification solution III is 50-55%.

6. The production process of anhydrous spherical calcium chloride according to claim 1, characterized in that: In step S5, the liquid phase loop pressure of the boiling granulation tower is 0.05-0.25 MPa, and the gas phase loop pressure is 0.35-0.45 MPa.

7. A production process for anhydrous spherical calcium chloride according to claim 6, characterized in that, The blower inlet air pressure in the boiling granulation tower is 7.0-8.0 KPa, and the hot air temperature is 350-450°C.

8. The production process of anhydrous spherical calcium chloride according to claim 7, wherein: The hot air entering the boiling granulation tower is in a rotating state during the granulation process.

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