CN1513834A - Recovery method of heavily polluted substance produced in ADC foaming agent production process and its device - Google Patents
Recovery method of heavily polluted substance produced in ADC foaming agent production process and its device Download PDFInfo
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Abstract
A process for recovering the main pollutants during the production of foaming agent ADC includes freezing the neutralized hydrazine solution to 10- -5 deg.C, centrifugal separation to obtain nitrium sulfate and the first filtrate, condensating between the first filtrate and urea, filtering to obtain biurea and the second filtrate, evaporating the second filtrate, centrifugal separating to obtain sodium chloride and the third filtrate, freezing the third filtrate to 10- -5 deg.C, centrifugal separating to obtain ammonium chloride and the fourth filtrate, evaporating the fourth filtrate several times, freezing to obtain crystal of sodium chloride or ammonium chloride, and returning the residual mother liquid back to condenser.
Description
Technical Field
The invention relates to a method and a device for recovering solid substances from liquid through evaporation and freezing crystallization, in particular to a method and a device for recovering serious pollutants in an ADC foaming agent production process.
Background
ADC foaming Agent (ADC) is widely used in plastic rubber industry, and has the widest application and the largest output in the foaming agent. However, the development of ADC production in China is hindered by the source of two main raw materials, namely sodium bichromate as an oxidant and hydrazine hydrate. Therefore, the inventor of the present invention studied ADC production by chlorine oxidation instead of sodium bichromate in the first chemical plant of Fuzhou in 1966, and proposed ADC production by crude hydrazine instead of pure hydrazine in 1970, wherein the production process is as follows:
1. preparation of sodium hypochlorite with sodium hydroxide and chlorine:
2. preparing hydrazine hydrate (also called crude hydrazine) by using sodium hypochlorite, excessive urea and excessive sodium hydroxide:
3. preparation of biurea by condensation of hydrazine hydrate with excess urea:
product of this reaction (NH)4)2SO4Also known as ammoniacal nitrogen NH3-N，
4. Preparing an ADC foaming agent by oxidizing biurea and chlorine gas:
it should be noted that, the pure hydrazine hydrate, one of the two problems mentioned above, is difficult to supply because the production of pure hydrazine hydrate is performed by the reaction of the formula (1) and the formula (2), and then crude hydrazine with hydrazine content of only about 3% is obtained, and the pure hydrazine hydrate contains many soluble impurities, such as by-products of sodium chloride 10-15%, sodium carbonate 4-10%, sodium hydroxide 1-5% and redundant urea and ammonia, and because hydrazine hydrate has a boiling point of 114 ℃, it is difficult to evaporate and concentrate hydrazine from crude hydrazine, and a five-layer evaporation tank is required.
The invention has been studied in detail in 1970 whether various soluble impurities in crude hydrazine influence the reaction of the formula (3) or not, and impurities can be removed after biurea and ADC are filtered and washed twice, the impurities can not influence the reaction of the formula (3), and the purity and quality of products can not be influenced, so the invention provides a new process for producing ADC by using crude hydrazine instead of pure hydrazine at home and abroad, and a large amount of tests and argumentations and large scale production practices prove that the process can meetthe production requirement of ADC in yield, saves a whole set of evaporation, fractionation and concentration equipment and operation procedures for processing and refining pure hydrazine, greatly reduces energy consumption, reduces the loss of one-step evaporation hydrazine, reduces the treatment of hydrazine-containing waste residue, greatly reduces the cost, has international competitive power, and writes a first factory of successful hydrazine hydrate, creates a first factory of Fuzhou to meet the urgent need of ADC market when no patent method is adopted for protection, The new process for producing the ADC foaming agent recovers three byproducts of ammonium sulfate, hydrochloric acid and soda ash, is published in the fourth journal of 1972 of Fuzhou science and technology, is given for gratuitous presentation and popularization and application in the national chemical industry, forms a unique process route in China, changes the yield from dozens of tons produced in the national year to tens of thousands of tons produced in the year, and also changes from a large number of imports of ADC into a large number of exports of China.
However, when crude hydrazine is used for producing ADC foaming agent by condensation, because the condensation reaction of formula (3) can only be carried out under slightly acidic or slightly alkaline conditions, otherwise, urea is subjected to a large amount of hydrolysis loss during condensation at 110 ℃ to cause difficult reaction, sulfuric acid (or hydrochloric acid) must be added to neutralize the crude hydrazine solution and adjust the pH value before and during the condensation reaction, so that the condensation reaction can be rapidly and smoothly carried out under high temperature conditions (a method for recovering by-products generated during neutralization by hydrochloric acid is adopted and is applied to another application), because the introduction of sulfuric acid causes acid mist containing hydrochloric acid and sodium sulfate by-products to be generated during neutralization reaction and acidification in the condensation process, and the following formulas are detailed:
for the treatment of acid mist pollution, the inventor has thoroughly solved the problem in the owned Chinese patent ZL96107542.2 (grant publication No. CN 1095390C). And for the other pollutants ammonium chloride, sodium sulfate and sodium chloride (based on 1 ton of ADC foaming agent, 241 kg of byproduct ammonia nitrogen can be obtained by calculation from a reaction formula, and the side reaction is equivalent to about 1.5 tons of ammonium sulfate, about 1.5-2 tons of byproduct sodium chloride and about 1.5-2.5 tons of sodium sulfate), the residual ammonium chloride, sodium sulfate and sodium chloride are good liquid fertilizers for farmers short of fertilizers in the last seventy-eight years. However, in the mid-eighties of the last century, a large amount of fertilizers are fully supplied and the price is reduced, so that a large amount of condensation mother liquor is directly discharged as waste liquor, and great pollution is caused to the surrounding environment.
With the publication of the state health care law and the emission standard, if the pollution problem of ammoniacal nitrogen in the ADC production process is not solved, the unique process route in China is rejected, and if the requirement of the environment protection law is executed, 241 kilograms of ammoniacal nitrogen as a byproduct of 1 ton of ADC product is the discharge capacity of 16000 cubic meters which is equivalent to the national allowable emission standard (15mg/l), and manufacturers who do not pay discharge fees or change the process route independently need to close due to the loss.
However, even if some enterprises just want to treat the three pollutants of ammonium chloride, sodium sulfate and sodium chloride in the condensation mother liquor, the method still has great technical problems because a large amount of sodium sulfate is simultaneously separated out when the sodium chloride is recovered from the condensation mother liquor by an evaporation method to form mixed salt which cannot become a product; when the ammonium chloride is recovered by a freezing method, a large amount of sodium sulfate is simultaneously crystallized and separated out, so that the purity of the ammonium chloride is greatly reduced, and the ammonium chloride is difficult to separate and purify.
Disclosure of Invention
The invention aims to solve the problem of serious pollution in the production of an ADC foaming agent by using crude hydrazine in the prior art, and provides a method and a device for recovering the serious pollutants in the production process of the ADC foaming agent, which can comprehensively recycle the byproduct pollutants in the production process of the ADC foaming agent, thoroughly eliminate the pollution and reduce the production cost of the ADC foaming agent.
The purpose of the invention is realized through the following scheme.
The method for recovering the serious pollutants in the production process of the ADC foaming agent is characterized by comprising the following steps of:
1. sodium sulfate is recovered from the neutralized hydrazine solution,
(1) provides a freezingpan, a centrifugal machine,
(2) the crude hydrazine neutralized by sulfuric acid is injected into a freezing pot to freeze and crystallize sodium sulfate,
(3) when the temperature of the solution in the freezing pot is 10 ℃ to-5 ℃, the solution is led into a centrifuge for centrifugation, first filter cake mirabilite and first filtrate are recovered,
2. provides a condensing pan which is composed of a pan body,
(1) adding urea into the first filtrate and carrying out condensation reaction in a condensation kettle,
(2) filtering the condensation reaction liquid, recovering the second filter cake biurea and the second filtrate,
3. recovering sodium chloride and ammonium chloride from the second filtrate,
(1) providing an evaporation pot, a second freezing pot,
(2) introducing the second filtrate into an evaporation tank for evaporating and crystallizing sodium chloride,
(3) introducing the second filtrate into a centrifugal machine for centrifugation when the volume of the second filtrate is reduced by 30-60%, recovering third filter cake sodium chloride and third filtrate,
(4) the third filtrate is pumped into a second freezing pot to freeze and crystallize ammonium chloride,
(5) introducing the third filtrate into a centrifuge for centrifugation when the temperature of the third filtrate in the second freezing pot reaches 10-5 ℃, recovering fourth filter cake ammonium chloride and fourth filtrate,
(6) and repeatedly introducing the fourth filtrate into an evaporation tank for evaporating and crystallizing sodium chloride and freezing crystal ammonium chloride in a second freezing pot until the hydrazine content in the mother liquor is more than 1%, and then sending the mother liquor back to the condensation pot for condensation.
The following reaction in the conventional art:
1. preparation of sodium hypochlorite with sodium hydroxide and chlorine:
2. preparing hydrazine hydrate (also called crude hydrazine) by using sodium hypochlorite, excessive urea and excessive sodium hydroxide:
3. adding sulfuric acid for neutralization:
the obtained reaction solution is called as a neutralized hydrazine solution, and contains by-products of sodium chloride, sodium sulfate, excessive urea and side-reaction ammonium salt in addition to a main product of hydrazine hydrate.
Freezing and crystallizing sodium sulfate in the neutralized hydrazine solution by adopting a freezing method, and centrifuging to obtain a first filter cake, namely sodium sulfate decahydrate (also called mirabilite) and a first filtrate. Theoretically, the solubility of sodium chloride is small along with the change of temperature, the slope of the curve is low, while the solubility of sodium sulfate is large along with the change of temperature, and the slope of the curve is large; practice also proves that no sodium chloride and hydrazonium are separated out when the mirabilite is recovered by freezing at the temperature of 10-5 ℃ in the presence of a large amount of sodium chloride and hydrazonium. The indexes of sodium sulfate recovery by a freezing method are that the yield of mirabilite reaches more than 90 percent, and the chemical index of the mirabilite reaches more than first-grade products; the residual sodium sulfate in the first filtrate is below 20 g/L, and simultaneously, a large amount of sodium chloride, a small amount of urea and ammonium salt are contained.
The best condition for judging the crystallization of the sodium sulfate is selected as follows: introducing into a centrifuge for centrifuging when the temperature of the solution in the freezing pan is 0 deg.C.
Secondly, performing condensation reaction on the first filtrate and urea in a condensation kettle by adopting a conventional method, and filtering the condensation reaction liquid, wherein the second filter cake is biurea, and the second filtrate contains sodium chloride, ammonium chloride, urea, a small amount of unreacted hydrazine and a small amount of sodium sulfate.
Thirdly, sodium chloride is recovered from the second filtrate by adopting an evaporation method in an evaporation tank, and both theory and practice prove that when the evaporation mother liquor contains 200 g/L sodium sulfate, the volume is reduced by 50 percent, the concentration of sodium sulfate reaches 400 g/L, supersaturation is already achieved, and crystallization is carried out, the invention firstly uses a freezing method to crystallize and separate out the sodium sulfate until the concentration of the sodium sulfate is reduced to below 20 g/L, then evaporating and crystallizing sodium chloride by an evaporation method, wherein the crystallization of sodium sulfate can not be separated out even if the volume of the solution is reduced to 60 percent by evaporation, further, because the solubility of sodium chloride is small with the temperature change and the slope of the curve is low, while the solubility of ammonium chloride is large with the temperature change and the slope of the curve is large, therefore, the sodium chloride is easily separated and purified from the ammonium chloride, and the purity of the separated sodium chloride is ensured as long as the ammonium chloride is not separated out when the volume of the second filtrate is controlled to evaporate 30-60%.
The best condition for judging the crystallization of the sodium chloride is selected as follows: and when the volume of the second filtrate in the evaporation tank is reduced by 50%, the second filtrate is introduced into a centrifugal machine for centrifugation.
And because the chloride ions of the ammonium chloride with high solubility promote the solubility of the sodium chloride in the solution to be smaller, more sodium chloride can be separated out.
And centrifuging the sodium chloride precipitated by evaporation crystallization by using a centrifugal machine to obtain a third filter cake sodium chloride, wherein the third filtrate also contains a large amount of ammonium chloride, sodium chloride, a small amount of sodium sulfate, a small amount of hydrazine and urea.
And fourthly, freezing and crystallizing the third filtrate in a freezing pot by adopting a freezing method to obtain fourth filter cake ammonium chloride, wherein the solubility of the ammonium chloride is greatly reduced when the temperature is low, so that a large amount of ammonium chloride is separated out, chloride ions in the solution are continuously reduced, the solubility of the sodium chloride is higher, the separation of the sodium chloride cannot occur, and partial sodium sulfate is separated out, so that the third filtrate in the second freezing pot is introduced into a centrifugal machine to centrifugally recover the ammonium chloride at the temperature of between 10 and-5 ℃, and the recovery degree of the sodium sulfateduring the recovery of the sodium sulfate directly influences the purity of the ammonium chloride.
The best condition for judging the crystallization of the ammonium chloride is selected as follows: introducing into a centrifuge for centrifuging when the temperature of the third filtrate in the second freezing pot reaches 0 ℃.
The fourth filtrate also contains solute sodium chloride and ammonium chloride, sodium chloride and ammonium chloride can be recovered through multiple times of evaporation and refrigeration, and when the hydrazine content in the residual solution is more than 1 percent (generally, the solution also contains unreacted hydrazine, and the hydrazine can be used for condensation biurea after the concentration of the hydrazine is improved), the hydrazine returns to the condensation process for recycling, so that the purposes of avoiding the environmental pollution caused by the hydrazine and making the best use of the substances are achieved, the cost is saved, and the waste is avoided. Thus, the whole closed cycle is established, the comprehensive recycling of the byproduct pollutants is realized, and the pollution is thoroughly eliminated.
The present invention relates to equipment such as a freezing pot, a centrifugal machine, an evaporating pot, a condensation pot, etc., which are all provided in the prior art.
The invention is characterized in that the byproducts in the production process of the ADC foaming agent are respectively recovered through different stages, so that the byproducts are not interfered with each other, and the byproducts are easy to separate and purify, in particular to the recovery of ammoniacal nitrogen seriously polluting the environment.
The most technological innovation is that sodium sulfate is skillfully recovered before condensation reaction, namely before ammonia nitrogen is not generated, then sodium chloride and ammonium chloride can be successfully recovered after condensation reaction, and the purity and quality of the recovered sodium chloride and ammonium chloride can be ensured only after the sodium sulfate is recovered.
It must be emphasized that, in the process, when acid is added in the condensation reaction process after the recovery of sodium sulfate to adjust the pH of the reaction system, only hydrochloric acid is used for adjustment, and sulfuric acid is not used for adjustment, so as to avoid introducing new sodium sulfate pollutants to influence the quality of the recovered ammonium chloride.
Therefore, the hydrochloric acid which is the byproduct of the reaction in the formula (4) can be used for pH adjustment of neutralization and condensation reaction, and when the hydrochloric acid is used for neutralization, the hydrochloric acid is directly used as the first filtrate without being recovered through mirabilite.
The whole recovery process of the invention does not need any raw and auxiliary materials, the process is simple and reasonable, and the equipment investment is saved; the whole production process has no discharge of three wastes (ammoniacal nitrogen, sodium sulfate and sodium chloride), fully meets the requirement of environmental protection law on waste discharge, and has optimal environmental protection benefit; the method changes waste into valuable, and the recovered ammonium chloride, sodium sulfate and sodium chloride can create good economic benefit and social benefit, which is an unexpected effect of the invention. On the other hand, the method saves all equipment and operation cost for treating wastes such as ammoniacal nitrogen and the like, and further reduces the cost.
The method also comprises the following steps:
1. the first filter cake is washed with cold water in acentrifuge,
2. stopping the machine and discharging when the hydrazine content of the first filter cake is lower than 0.05 percent.
The process aims to further purify the mirabilite, so that the quality of the mirabilite is further enhanced, and the economic benefit of the mirabilite is improved.
In order to perform another treatment on the recycled mirabilite, thereby more widely realizing the economic benefit of the sodium sulfate and widening the market, the invention can also perform the following treatment on the mirabilite:
the invention can further adopt the following steps:
1. providing a second evaporation tank, a centrifuge E, a drying oven,
2. the redundant mirabilite is sent into an evaporation tank for evaporation and crystallization,
3. sending the solution into a centrifuge for centrifugation when the crystalline solid content of the solution in the evaporation tank reaches 30 percent,
4. and (5) drying the filter cake in a drying furnace to obtain the thenardite.
The filtrate in the process can be fed into the evaporating pot again to be evaporated and crystallized continuously, and the process is repeated continuously until all the mirabilite is converted into sodium sulfate.
The process does not use raw and auxiliary materials, so the profit is 50-100 yuan higher than that of sodium sulfate plants for producing sodium sulfate tons.
The invention further comprises the following steps:
1. the third filter cake is washed with hot water in a centrifuge,
2. and stopping discharging until the content of ammonium chloride in the third filter cake is lower than 0.05%.
The process aims to further purify the sodium chloride, so that the quality of the sodium chloride is further improved, and the economic benefit of the sodium chloride is improved.
The filtrate and washing liquid in the process can return to an evaporation tank to be evaporated and crystallized for a plurality of times to obtain the sodium chloride.
The invention further resides in
Also comprises the following steps:
1. the fourth filter cake is washed with cold water in a centrifuge,
2. and stopping discharging until the content of the sodium chloride in the fourth filter cake is lower than 1%.
The first filter cake, the third filter cake and the fourth filter cake are washed to obtain purified products, so that the products obtained by the process of the invention reach the standard of like products, and the serious pollutants in the prior art are changed into usable fertilizers of ammonium chloride, sodium chloride and sodium sulfate, thereby turning harm into benefit and changing waste into valuable.
The object of the invention, providing a recovery device of serious pollutants in the ADC foaming agent production process, can be realized by the following scheme.
Recovery unit of serious pollutant in ADC foamer production process, including the condensation pot, its main points lie in, still including neutralizing hydrazine metering tank, the freezing pot, centrifuge A, centrifuge B, the evaporating pot, centrifuge C, second freezing pot and centrifuge D, neutralizing hydrazine metering tank, the freezing pot, centrifuge A, the condensation pot, centrifuge B, the evaporating pot, centrifuge C, second freezing pot and centrifuge D's business turn over material mouth communicates in proper order, and centrifuge A, centrifuge B, centrifuge C and centrifuge D's solid discharge gate respectively with the glauber's salt storage tank, the biurea storage tank, sodium chloride storage tank and ammonium chloride storage tank intercommunication, centrifuge D's filtrating discharge gate and evaporating pot and condensation pot intercommunication.
The various devices are conventional devices, and only because the connection mode of the devices is different from the prior art, the complete device achieves beneficial technical effects when used for recovering pollutants such as ammonium chloride, sodium sulfate and sodium chloride in the production process of the ADC foaming agent.
The invention further resides in
The device for recovering the serious pollutants in the ADC foaming agent production process further comprises a second evaporation tank, a centrifugal machine E and a drying furnace, wherein the mirabilite storage tank, the second evaporation tank, the centrifugal machine E and the feeding and discharging ports of the drying furnace are sequentially connected, and the liquid discharging port of the centrifugal machine E is communicated with the mirabilite storage tank.
The device is mainly used for processing mirabilite to form an anhydrous sodium sulfate product, thereby improving the market prospect and economic value of the mirabilite.
The circulation of materials between the two sets of devices can be realized through a feed pump, and the materials can be stirred by a stirrer which is added to some devices such as a neutralization hydrazine metering tank, a freezing pot, a mirabilite storage tank and the like.
The object of the present invention can also be achieved by the following scheme.
Sodium chloride and ammonium chloride arerecovered from the second filtrate or the following steps may be employed:
(1) provides an evaporating pot, a centrifuge, a dissolving pot,
(2) introducing the second filtrate into an evaporation tank and a centrifuge, evaporating for multiple times, filtering to obtain mixed salt, or solarizing to obtain mixed salt,
(3) heating and dissolving the mixed salt in a solvent in a dissolving pot until ammonium chloride is dissolved to be nearly saturated to obtain sodium chloride crystal mixed solution,
(4) the mixed solution is led into a centrifuge for centrifugation to obtain a third filter cake of sodium chloride, a third filtrate of ammonium chloride and sodium chloride solution,
(5) there is provided a second freezing cylinder for a refrigerator,
(6) pumping the filtrate into a second freezing pot to freeze and crystallize ammonium chloride,
(7) introducing the filtrate into a centrifuge for centrifugation when the temperature of the filtrate in the second freezing pot reaches 10-5 ℃ to obtain a fourth filter cake ammonium chloride and a fourth filtrate,
(8) and (5) repeatedly carrying out the steps (3) to (7) on the fourth filtrate until the hydrazine content in the mother liquor is more than 1%, and then sending the mother liquor back to the condensation kettle for condensation.
The solvent in the process can be fourth filtrate, mother liquor and even water. If the fourth filtrate is still remained after reaching the dissolving pot, the redundant fourth filtrate can be returned to the evaporating pot to recycle the mixed salt.
The process provides a method for recovering sodium chloride and ammonium chloride from a second filtrate obtained aftercondensation reaction, which comprises the steps of firstly removing water to obtain mixed salt, then firstly dissolving ammonium chloride according to different solubilities of the sodium chloride and the ammonium chloride to recover the sodium chloride, and finally freezing to recover the ammonium chloride. The method is also particularly suitable for dry climates in northern winter, because the beach drying method can be used for obtaining mixed salt, and even the second freezing pot can be not used, and the natural freezing method can be directly used for obtaining ammonium chloride. In this way, a lot of costs can be reduced.
Compared with the prior art, the invention has the following advantages: the whole recovery process does not need any raw and auxiliary materials, the process is simple and reasonable, and the equipment investment is saved; the whole production process has no discharge of three wastes, and has good environmental protection benefit; the method has the advantages that waste materials are changed into valuable materials, the recovered ammonium chloride, sodium sulfate and sodium chloride can create good economic benefit and social benefit, all equipment and operation cost for treating wastes such as ammoniacal nitrogen and the like are saved, and the cost is reduced.
Drawings
Fig. 1 is a process flow diagram of examples 1 and 2 of the present invention.
FIG. 2 is a process flow diagram of the preferred embodiment of the present invention.
Detailed Description
The present invention will be described in more detail with reference to examples.
The device for recovering serious pollutants in the ADC foaming agent production process shown in figure 1 comprises the following equipment: the device comprises a neutralization hydrazine metering tank 1, a freezing pot 2, a centrifuge A, a condensation pot 3, a centrifuge B, an evaporation tank 4, a centrifuge C, a second freezing pot 5, a centrifuge D, a mirabilite storage tank 6, a biurea storage tank 7, a sodium chloride storage tank 8, an ammonium chloride storage tank 9, a stirrer 12, a feeding pump 13 and a valve 14.
The connection of these devices is as follows: the neutralization hydrazine metering tank 1 is provided with a stirrer 121 and is communicated with a freezing pot 2 through a feeding pump 131 and a valve 141, the freezing pot 2 is provided with a stirrer 122 and is communicated with a centrifuge A through a pump 132 and a valve 142, a solid discharge port of the centrifuge A is communicated with a mirabilite storage tank 6, a filtrate discharge port of the centrifuge A is communicated with a condensation pot 3 through a feeding pump 133 and a valve 143, the condensation pot 3 is communicated with a centrifuge B through a feeding pump 134 and a valve 144, a solid discharge port of the centrifuge B is communicated with a biurea storage tank 7, a filtrate discharge port of the centrifuge B is communicated with an evaporation tank 4 through a feeding pump 135 and a valve 145, the evaporation tank 4 is communicated with a centrifuge C through a feeding pump 136 and a valve 146, a solid discharge port of the centrifuge C is communicated with a sodium chloride storage tank 8, a filtrate discharge port of the centrifuge C is communicated with a second freezing pot 5 through a feeding pump 137 and a valve 147, the second freezing pot 5 is provided with a stirrer 123, the second freezing pot 5 is communicated, the solid discharge port of the centrifuge D is communicated with the ammonium chloride storage tank 9, the filtrate discharge port of the centrifuge D is communicated with theevaporation tank 4, and the discharge port of the centrifuge D is also communicated with the condensation pot 3.
According to the recovery device for the serious pollutants in the ADC foaming agent production process, the following recovery method for the serious pollutants in the ADC foaming agent production process is adopted, and the recovery method comprises the following steps:
1. sodium sulfate recovery from neutralized crude hydrazine solution by freezing:
opening the stirrer 121 of the neutralization hydrazine metering tank 1, opening the valve 141, then opening the feeding pump 131 to pump the neutralization hydrazine into the freezing pot 2 from the neutralization hydrazine metering tank 1 until the volume of the freezing pot 2 is 80%, closing the valve 141, stopping the feeding pump 131, opening the stirrer 122 of the freezing pot 2, introducing cold liquid to freeze and crystallize sodium sulfate, closing the cold liquid when the temperature of the solution in the freezing pot 2 is 10 ℃, opening the centrifuge A, the valve 142 and the feeding pump 132, pumping the feed liquid into the centrifuge A to carry out centrifugal dehydration, stopping the feeding pump 132, the valve 142 and the centrifuge A when the first cake mirabilite accounts for 70-80% of the volume of the centrifuge A, and taking care to prevent the mirabilite from fully running out to obtain a first cake to a mirabilite storage tank 6.
2. Carrying out a biurea condensation reaction:
opening a valve 143 and a feed pump 133, sending the first filtrate to a condensation pot 3, closing the feed pump 133 and the valve 143, adding urea for condensation reaction, opening a centrifugal machine B, opening a valve 144 and opening a feed pump 134, stopping the feed pump 134, closing the valve 144 and the centrifugal machine B when the second filter cake biurea accounts for70-80% of the capacity of the centrifugal machine B, and discharging the second filter cake to a biurea storage tank 7.
3. Recovering sodium chloride by an evaporation method:
and opening a valve 145 and a feeding pump 135, conveying the second filtrate to the evaporation tank 4, feeding to a certain height, stopping the feeding pump 135, closing the valve 145, starting evaporation operation, when the volume of the second filtrate is reduced by 30%, crystallizing and separating out a large amount of sodium chloride, when ammonium chloride is nearly saturated, opening a centrifuge C, opening the valve 146 and the feeding pump 136 for spin-drying and dewatering, and when the third filter cake sodium chloride accounts for 70-80% of the volume of the centrifuge C, stopping the feeding pump 136, closing the valve 146 and the centrifuge C, and discharging the third filter cake to a sodium chloride storage tank 8.
4. Freezing and recovering ammonium chloride:
opening a valve 147 and a feed pump 137, sending the third filtrate to a second freezing pot 5, feeding to 80%, stopping the feed pump 137 and closing the valve 147, opening a stirrer 123 of the second freezing pot 5, starting the cold liquid for freezing, stopping the cold liquid when the temperature of the third filtrate reaches 10 ℃, opening a centrifugal machine D, opening a valve 148 and opening a feed pump 138, performing spin-drying dehydration, stopping the feed pump 138, closing the valve 148 and the centrifugal machine D when the fourth filter cake ammonium chloride accounts for 70-80% of the capacity of the centrifugal machine D, discharging the fourth filter cake to an ammonium chloride storage tank 9, repeatedly introducing the fourth filtrate into an evaporation tank 4 through a feed pump 1311 and a valve 1411 for evaporating and crystallizing sodium chloride and freezing crystal ammoniumchloride in the second freezing pot 5 until the hydrazine content in the mother liquor is more than 1%, and then sending the mother liquor back to a condensation pot 3 for condensation.
The parts not described in the present embodiment are the same as those in the prior art.
Example 2:
the device for recovering serious pollutants in the ADC foaming agent production process shown in FIG. 2 comprises the following equipment: the device comprises a neutralization hydrazine metering tank 1, a freezing pot 2, a centrifuge A, a condensation pot 3, a centrifuge B, an evaporation tank 4, a centrifuge C, a second freezing pot 5, a centrifuge D, a mirabilite storage tank 6, a biurea storage tank 7, a sodium chloride storage tank 8, an ammonium chloride storage tank 9, a second evaporation tank 10, a centrifuge E, a drying furnace 11, a stirrer 12, a feeding pump 13 and a valve 14.
The connection of these devices is as follows: the neutralization hydrazine metering tank 1 is provided with a stirrer 121 and is communicated with a freezing pot 2 through a feeding pump 131 and a valve 141, the freezing pot 2 is provided with a stirrer 122 and is communicated with a centrifuge A through a pump 132 and a valve 142, a solid discharge port of the centrifuge A is communicated with a mirabilite storage tank 6, a filtrate discharge port of the centrifuge A is communicated with a condensation pot 3 through a feeding pump 133 and a valve 143, the condensation pot 3 is communicated with a centrifuge B through a feeding pump 134 and a valve 144, a solid discharge port of the centrifuge B is communicated with a biurea storage tank 7, a filtrate discharge port of the centrifuge B is communicated with an evaporation tank 4 through a feeding pump 135 and a valve 145, the evaporation tank 4 is communicated with a centrifuge C through a feeding pump 136 and a valve 146, a solid discharge port of the centrifuge C is communicated with a sodium chloride storage tank 8, a filtrate discharge port of the centrifuge C is communicated with a second freezing pot 5 through a feeding pump 137 and a valve 147, the second freezing pot 5 is provided with a stirrer 123, the second freezing pot 5 is communicated, the solid discharge port of the centrifuge D is communicated with an ammonium chloride storage tank 9, the filtrate discharge port of the centrifuge D is communicated with the evaporation tank 4 through a pump 1311 and a valve 1411, and the discharge port of the centrifuge D is also communicated with the condensation pot 3.
The mirabilite storage tank 6 is communicated with the second evaporation tank 10 through a feeding pump 139 and a valve 149, the mirabilite storage tank 6 is provided with a stirrer 124, the second evaporation tank 10 is communicated with a centrifuge E through a feeding pump 1310 and a valve 1410, a solid discharge port of the centrifuge E is communicated with an anhydrous mirabilite storage tank 15, and a filtrate discharge port of the centrifuge E is communicated with the mirabilite storage tank 6.
According to the recovery device for the serious pollutants in the ADC foaming agent production process, the following recovery method for the serious pollutants in the ADC foaming agent production process is adopted, and the recovery method comprises the following steps:
1. sodium sulfate recovery from neutralized crude hydrazine solution by freezing:
opening the stirrer 121 of the neutralization hydrazine metering tank 1, opening the valve 141, then opening the feed pump 131, pumping the neutralization hydrazine into the freezing pot 2 from the neutralization hydrazine metering tank 1 until the volume of the freezing pot 2 is 80%, closing the valve 141, stopping the feed pump 131, opening the stirrer 122 of the freezing pot 2, introducing cold liquid to freeze and crystallize sodium sulfate, closing the cold liquid when the temperature of the solution in the freezing pot 2 is-5 ℃, opening the centrifuge A, the valve 142 and the feed pump 132, pumping the feed liquid into the centrifuge A to carry out centrifugal dehydration, closing the valve 142 and stopping the feed pump 132 when the first cake mirabilite accounts for 70-80% of the volume of the centrifuge A, paying attention to prevent the mirabilite from fully running out, washing the first cake with cold water in the centrifuge A until the hydrazine content of the first cake is lower than 0.05%, stopping the centrifuge A, and discharging the first cake mirabilite to the storage tank 6.
And (3) starting the stirrer 124, the feeding pump 139 and the valve 149 to convey the feed liquid to the second evaporation tank 10, closing the feeding pump 139 and the valve 149 after the feed liquid reaches a certain height, starting evaporation concentration crystallization, separating out a large amount of anhydrous mirabilite crystals, starting the centrifuge E, the valve 1410 and the feeding pump 1310 to spin-dry and dewater when the solid amount reaches 30%, stopping the feeding pump 1310, closing the valve 1410 and stopping the centrifuge E when the filter cake in the centrifuge E reaches 70-80% of capacity, discharging the solid material to the drying furnace to obtain a first-grade product of anhydrous mirabilite, conveying the centrifugal mother liquid to the mirabilite storage tank 6 to be mixed with new mirabilite, and continuing evaporation crystallization.
2. Carrying out a biurea condensation reaction:
and opening a valve 143 and a feed pump 133, feeding the first filtrate to the condensation kettle 3, closing the valve 143, stopping the feed pump 133, adding urea, performing condensation reaction, then opening the centrifuge B, a valve 144 and a feed pump 134, stopping the feedpump 134, closing the valve 144 and the centrifuge B when the second filter cake biurea accounts for 70-80% of the capacity of the centrifuge B, and discharging the second filter cake to the biurea storage tank 7.
3. Recovering sodium chloride by an evaporation method:
and (3) starting a feed pump 135 and a valve 145, conveying the second filtrate to an evaporation tank 4, feeding to a certain height, closing the feed pump 135 and the valve 145, starting evaporation operation, when the volume of the second filtrate is reduced by 60%, crystallizing and separating out a large amount of sodium chloride, and when ammonium chloride is nearly saturated, starting a centrifuge C, opening the valve 146 and stopping the feed pump 136 for spin-drying and dewatering, when the sodium chloride of the third filter cake accounts for 70-80% of the volume of the centrifuge C, closing the valve 146 and stopping the feed pump 136, washing the third filter cake in the centrifuge C by using hot water until the content of the ammonium chloride in the third filter cake is lower than 0.05%, stopping the centrifuge C, and discharging the third filter cake to a sodium chloride storage tank 8.
4. Freezing and recovering ammonium chloride:
starting a feed pump 137 and a valve 147, sending the third filtrate to a second freezing pot 5, feeding to 80%, closing the valve 147, stopping the feed pump 137, starting a stirrer 123 of the second freezing pot 5, starting the cold liquid for freezing until the temperature of the third filtrate in the second freezing pot 5 is-5 ℃, stopping cooling, starting the centrifuge D, the valve 148 and the feeding pump 138, performing spin-drying and dehydration, when the fourth filter cake ammonium chloride accounts for 70-80% of the capacity of the centrifuge D, the feed pump 138 and the valve 148 are stopped, and (3) washing the fourth filter cakewith cold water in a centrifuge D until the content of sodium chloride in the fourth filter cake is lower than 1%, stopping the centrifuge D, discharging the fourth filter cake to an ammonium chloride storage tank 9, repeatedly introducing the fourth filtrate and sodium chloride washing liquor into an evaporation tank 4 through a feed pump 1311 and a valve 1411 to evaporate and crystallize sodium chloride and freeze crystal ammonium chloride in a second freezing pot 5 until the content of hydrazine in the mother liquor is higher than 1%, and returning the mother liquor to a condensation pot 3 for condensation.
The recovery apparatus and the remaining steps in this example were the same as in example 1.
The best embodiment is as follows:
the recovery method of serious pollutants in the ADC foaming agent production process shown in figure 2,
1. when sodium sulfate is recovered from the neutralized hydrazine solution by freezing, the solution is introduced into a centrifuge for centrifugation when the temperature of the solution in the freezing pot 2 is 0 ℃;
2. when sodium chloride is recovered by an evaporation method, introducing the sodium chloride into a centrifugal machine for centrifugation when the volume of the second filtrate in the evaporation tank 4 is reduced by 50%;
3. when ammonium chloride is recovered by freezing, the third filtrate is introduced into a centrifuge for centrifugation when the temperature of the third filtrate in the second freezing pot 5 reaches 0 ℃.
The present example is the same as example 2 except for the above-mentioned portions.
Claims (10)
1. The method for recovering serious pollutants in the production process of the ADC foaming agent is characterized by comprising the following steps of:
(1) sodium sulfate is recovered from the neutralized hydrazine solution,
① to provide a freezer, a centrifuge,
② the crude hydrazine which has been neutralized by sulfuric acid is pumped into a freezing pot to freeze and crystallize sodium sulfate,
③ introducing into a centrifuge for centrifugation when the temperature of the solution in the freezing pot is 10-5 deg.C, recovering first cake mirabilite and first filtrate,
(2) provides a condensing pan which is composed of a pan body,
① adding urea into the first filtrate and carrying out condensation reaction in a condensation kettle,
② filtering the condensation reaction liquid, recovering the second filter cake biurea and the second filtrate,
(3) recovering sodium chloride and ammonium chloride from the second filtrate,
① provides a vaporization tank, a second freezer,
② introducing the second filtrate into an evaporator to evaporate and crystallize sodium chloride,
③ when the volume of the second filtrate in the evaporating pot is reduced by 30-60%, the filtrate is introduced into a centrifuge for centrifugation and returned
Collecting the third filter cake sodium chloride and the third filtrate,
④ the third filtrate is pumped into a second freezing pot to freeze and crystallize ammonium chloride,
⑤ to the second freezing pot, introducing the third filtrate into a centrifuge for centrifugation at the temperature of 10 ℃ to-5 ℃, recovering the fourth filter cake ammonium chloride,
⑥ introducing the fourth filtrate into an evaporator for several times to evaporate and crystallize sodium chloride and freezing crystal ammonium chloride in a second freezing pot until the hydrazine content in the mother liquor is more than 1%, and returning the mother liquor to the condensation pot for condensation.
2. The method for recovering serious pollutants in the ADC foaming agent production process of claim 1, wherein the serious pollutants are introduced into a centrifuge for centrifugation when the temperature of the solution in a freezing pot is 0 ℃; introducing into a centrifuge for centrifuging when the temperature of the third filtrate in the second freezing pot reaches 0 ℃.
3. The method of claim 1, wherein the second filtrate is centrifuged until the volume of the second filtrate in the evaporator is reduced by 50%.
4. The method for recovering serious pollutants in the ADC foaming agent production process of claim 1, further comprising the following steps of:
(1) the first filter cake is washed with cold water in a centrifuge,
(2) stopping the machine and discharging when the hydrazine content of the first filter cake is lower than 0.05 percent.
5. The method for recovering serious pollutants in the ADC foaming agent production process of claim 1, is characterized by further comprising the following steps of:
(1) providing a second evaporation tank, a centrifuge E, a drying oven,
(2) sending the mirabilite into an evaporation tank for evaporation and crystallization,
(3) when the crystalline solid content in the solution reaches 30 percent, the solution is sent into a centrifuge for centrifugation,
(4) and (5) drying the filter cake in a drying furnace to obtain the thenardite.
6. The method for recovering serious pollutants in the ADC foaming agent production process of claim 1, further comprising the following steps of:
(1) the third filter cake is washed with hot water in a centrifuge,
(2) and stopping discharging until the content of ammonium chloride in the third filter cake is lower than 0.05%.
7. The method for recovering serious pollutants in the ADC foaming agent production process of claim 1, further comprising the following steps of:
(1) the fourth filter cake is washed with cold water in a centrifuge,
(2) and stopping discharging until the content of the sodium chloride in the fourth filter cake is lower than 1%.
8. The device for recovering serious pollutants in the production process of the ADC foaming agent comprises a condensation pot (3), it is characterized by also comprising a neutralization hydrazine metering tank (1), a freezing pot (2), a centrifugal machine (A), a centrifugal machine (B), an evaporating pot (4), a centrifugal machine (C), a second freezing pot (5) and a centrifugal machine (D), wherein the neutralization hydrazine metering tank (1), the freezing pot (2), the centrifugal machine (A), a condensation pot (3), the centrifugal machine (B), the evaporating pot (4), the centrifugal machine (C), the second freezing pot (5) and the inlet and outlet of the centrifugal machine (D) are communicated in sequence, and solid discharge portsof the centrifuge (A), the centrifuge (B), the centrifuge (C) and the centrifuge (D) are respectively communicated with a mirabilite storage tank (6), a biurea storage tank (7), a sodium chloride storage tank (8) and an ammonium chloride storage tank (9), and a filtrate discharge port of the centrifuge (D) is communicated with the evaporation tank (4) and the condensation kettle (3).
9. The device for recovering the serious pollutants in the ADC foaming agent production process according to claim 8, further comprising a second evaporation tank (10), a centrifuge (E) and a drying furnace (11), wherein the mirabilite storage tank (6), the second evaporation tank (10), the centrifuge (E) and the feeding and discharging ports of the drying furnace (11) are sequentially connected, and the liquid discharging port of the centrifuge E is communicated with the mirabilite storage tank (6).
10. The method for recovering serious pollutants in the ADC foaming agent production process of claim 1, wherein the sodium chloride and the ammonium chloride are recovered from the second filtrate or the following steps are adopted:
(1) provides an evaporating pot, a centrifuge, a dissolving pot,
(2) introducing the second filtrate into an evaporation tank and a centrifuge, evaporating for multiple times, filtering to obtain mixed salt, or solarizing to obtain mixed salt,
(3) heating and dissolving the mixed salt in a solvent in a dissolving pot until ammonium chloride is dissolved to be nearly saturated to obtain sodium chloride crystal mixed solution,
(4) the mixed solution is led into a centrifuge for centrifugation to obtain a third filter cake sodium chloride, a third filtrate ammonium chloride solution,
(5) there is provided a second freezing cylinder for a refrigerator,
(6) pumping the filtrate into a second freezing pot to freeze and crystallize ammonium chloride,
(7) introducing the filtrate into a centrifuge for centrifugation when the temperature of the filtrate in the second freezing pot reaches 10 to-5 ℃ to obtain a fourth filter cake ammonium chloride and a fourth filtrate,
(8) and (5) repeatedly carrying out the steps (3) to (7) on the fourth filtrate until the hydrazine content in the mother liquor is more than 1%, and then sending the mother liquor back to the condensation kettle for condensation.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1328176C (en) * | 2005-01-28 | 2007-07-25 | 江苏江大环境工程有限责任公司 | New comprehensive utilization method of ADC foaming agent condensed mother liquor |
| CN101289415B (en) * | 2008-05-30 | 2010-09-29 | 南京大学 | Method for treating feed liquid in process for producing blowing agent by carbamide method |
| CN102826520A (en) * | 2012-09-17 | 2012-12-19 | 宁夏日盛实业有限公司 | Method for implementing co-production of ammonium sulfate from ADC foaming agent wastewater by extracting hydrazine hydrate |
| CN103043841A (en) * | 2012-12-10 | 2013-04-17 | 枣庄中科化学有限公司 | ADCA (Azodicarbonamide) foaming agent liquid waste disposal process |
| CN103058892A (en) * | 2013-01-06 | 2013-04-24 | 杭州海虹精细化工有限公司 | Method for preparing biruea through utilizing hydrazino ester, acid and salt compound |
| CN104692575A (en) * | 2014-12-22 | 2015-06-10 | 内蒙古久科康瑞环保科技有限公司 | Crystallization treatment method and device of high salt wastewater |
| CN106748895A (en) * | 2015-11-25 | 2017-05-31 | 衡阳市锦轩化工有限公司 | A kind of processing method of ADC foaming agent condensed mother liquors |
| CN109607910A (en) * | 2018-11-27 | 2019-04-12 | 江西世龙实业股份有限公司 | A kind of System and method for of processing AC foaming agent production waste water |
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- 2003-07-15 CN CN03132081.3A patent/CN1226279C/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1328176C (en) * | 2005-01-28 | 2007-07-25 | 江苏江大环境工程有限责任公司 | New comprehensive utilization method of ADC foaming agent condensed mother liquor |
| CN101289415B (en) * | 2008-05-30 | 2010-09-29 | 南京大学 | Method for treating feed liquid in process for producing blowing agent by carbamide method |
| CN102826520A (en) * | 2012-09-17 | 2012-12-19 | 宁夏日盛实业有限公司 | Method for implementing co-production of ammonium sulfate from ADC foaming agent wastewater by extracting hydrazine hydrate |
| CN103043841A (en) * | 2012-12-10 | 2013-04-17 | 枣庄中科化学有限公司 | ADCA (Azodicarbonamide) foaming agent liquid waste disposal process |
| CN103058892A (en) * | 2013-01-06 | 2013-04-24 | 杭州海虹精细化工有限公司 | Method for preparing biruea through utilizing hydrazino ester, acid and salt compound |
| CN104692575A (en) * | 2014-12-22 | 2015-06-10 | 内蒙古久科康瑞环保科技有限公司 | Crystallization treatment method and device of high salt wastewater |
| CN104692575B (en) * | 2014-12-22 | 2017-02-22 | 内蒙古久科康瑞环保科技有限公司 | Crystallization treatment method and device of high salt wastewater |
| CN106748895A (en) * | 2015-11-25 | 2017-05-31 | 衡阳市锦轩化工有限公司 | A kind of processing method of ADC foaming agent condensed mother liquors |
| CN109607910A (en) * | 2018-11-27 | 2019-04-12 | 江西世龙实业股份有限公司 | A kind of System and method for of processing AC foaming agent production waste water |
| CN109607910B (en) * | 2018-11-27 | 2020-02-07 | 江西世龙实业股份有限公司 | System and method for treating AC foaming agent production wastewater |
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|---|---|
| CN1226279C (en) | 2005-11-09 |
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