CN107300291B - Glycol solution refrigerating system and glycol circulating liquid - Google Patents

Abstract

The invention discloses an ethylene glycol solution refrigerating system and an ethylene glycol circulating liquid, wherein the system comprises an auxiliary agent storage tank, an ethylene glycol solution storage tank and a refrigerating unit, wherein the auxiliary agent storage tank and the ethylene glycol solution storage tank are communicated with the refrigerating unit through an ethylene glycol solution circulating pipeline provided with a circulating pump to form a circulating loop, and the ethylene glycol solution in the ethylene glycol solution storage tank is cooled and circulated in an interlayer of the auxiliary agent storage tank through the refrigerating unit. The glycol circulation liquid comprises 25-35% of glycol, 0.25-0.35% of disodium hydrogen phosphate, 2.5-3.0% of borax, 0.35-0.50% of sodium benzoate, 0.12-0.15% of methylbenzotriazole TTA, 0.12-0.15% of antisludging agent and the balance of deionized water. The system utilizes the characteristics of high boiling point, difficult evaporation loss and low freezing point of ethylene glycol, and introduces ethylene glycol circulating liquid into the interlayer of the initiator storage tank, thereby meeting the requirement of storage temperature and further ensuring the stable operation of polyvinyl chloride production. The glycol circulating liquid does not corrode a circulating pipeline and does not scale, so that the auxiliary agent in the auxiliary agent storage tank can be kept stable at a required temperature for a long time.

Description

Glycol solution refrigerating system and glycol circulating liquid

Technical Field

The invention relates to a polymerization initiator refrigerating device, in particular to an ethylene glycol solution refrigerating system and an ethylene glycol circulating liquid.

Background

In the polyvinyl chloride production process, in the polymerization process, an initiator, a terminator or an emergency terminator and other auxiliary agents are added into a polymerization kettle to promote polymerization or terminate reaction, a certain storage temperature requirement is provided for the auxiliary agents before the auxiliary agents are added, and the use effect of the auxiliary agents is influenced to a certain extent due to the fact that the temperature is too high or too low, so that production is influenced.

The auxiliary agent in the production of polyvinyl chloride is usually stored in an auxiliary agent storage tank, and a certain requirement is placed on the refrigerating fluid of an interlayer of the storage tank. During long-term operation, the refrigerating fluid is oxidized into polymer organic acid (commonly called sludge) to corrode a water tank and a water jacket so as to leak the water tank and the water jacket; and moreover, very sticky substances are easy to form, scaling is easy to occur after deposition, so that the system is blocked in operation, and shutdown and maintenance can be performed after a period of operation, so that the economic benefit of the whole polyvinyl chloride production line is directly affected.

Disclosure of Invention

In order to solve the defects in the prior art, the invention aims to provide an ethylene glycol solution refrigerating system and an ethylene glycol circulating liquid, wherein the system utilizes the characteristics of high boiling point of ethylene glycol, difficult evaporation loss in use and low freezing point, and the ethylene glycol circulating liquid is introduced into an interlayer of an initiator storage tank, so that the requirement of storage temperature is met, and the stable operation of polyvinyl chloride production is further ensured.

The invention is realized by the following technical scheme.

The invention relates to an ethylene glycol solution refrigerating system which comprises an auxiliary agent storage tank, an ethylene glycol solution storage tank and a refrigerating unit, wherein the auxiliary agent storage tank and the ethylene glycol solution storage tank are communicated with the refrigerating unit through an ethylene glycol solution circulating pipeline provided with a circulating pump to form a circulating loop, and the ethylene glycol solution in the ethylene glycol solution storage tank is cooled and circulated in an interlayer of the auxiliary agent storage tank through the refrigerating unit.

Further, one top pipeline of the glycol solution storage tank is communicated with an upper interlayer of the auxiliary agent storage tank, the other top pipeline of the glycol solution storage tank is communicated with a refrigerating unit, and a circulating pump is communicated with a circulating pipeline of the refrigerating unit; and a bottom pipeline of the ethylene glycol solution storage tank is communicated with a circulating pump.

Further, the circulating pump comprises an ethylene glycol solution A/B circulating pump and an ethylene glycol solution circulating pump, wherein the ethylene glycol solution A/B circulating pump is respectively communicated with a liquid outlet of the ethylene glycol solution storage tank, and the ethylene glycol solution circulating pump is communicated with a liquid inlet of the ethylene glycol solution storage tank.

Further, the top pipeline of the glycol solution storage tank is communicated with the liquid inlet of the refrigerating unit, and the liquid outlet of the refrigerating unit is communicated with the circulating pump to the bottom interlayer of the auxiliary agent storage tank through the circulating pipeline.

Further, control valves are respectively arranged on the inlets and outlets of the auxiliary agent storage tank, the glycol solution storage tank and the refrigerating unit.

The invention further provides an ethylene glycol circulating liquid for an ethylene glycol solution refrigerating system, which comprises the following raw materials in percentage by mass:

25-35% of ethylene glycol; disodium hydrogen phosphate 0.25-0.35%; borax 2.5-3.0%; sodium benzoate 0.35-0.50%; 0.12 to 0.15 percent of tolyltriazole TTA; 0.12 to 0.15 percent of scale inhibitor; the balance of deionized water.

Further, the scale inhibitor is YX-94 scale inhibitor of Jiangsu Han light industry Co., ltd.

Further, when the ethylene glycol circulation liquid is at-20 ℃, the ethylene glycol is 35%; when the ethylene glycol circulation liquid is at-10 ℃, the ethylene glycol is 25%.

The invention has the beneficial effects that:

1) By adopting the system, the auxiliary agent used for the polyvinyl chloride can be kept at a required temperature, and the stable operation of production is ensured.

2) Ethylene glycol has a high boiling point (boiling point: 107 ℃) and low freezing point (freezing point: -40 ℃); and preservative, antirust agent, corrosion inhibitor, scale inhibitor and the like are added; the ethylene glycol circulating liquid is proportioned to achieve the purposes that the ethylene glycol circulating liquid does not corrode a circulating pipeline and does not scale, so that the auxiliary agent in the auxiliary agent storage tank can be kept stable at the required temperature for a long time.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention.

In the figure: 1. a glycol solution storage tank; 2. a glycol solution circulation line; 3. an auxiliary agent storage tank; 4. a refrigerating unit; 5. a glycol solution circulation pump; 6. glycol solution A/B circulating pump.

Detailed Description

The present invention will be described in further detail with reference to examples, but is not intended to be construed as limiting the invention in any way.

As shown in fig. 1, the glycol solution refrigerating system comprises an auxiliaryagent storage tank 3, a glycol solution storage tank 1 and a refrigeratingunit 4, wherein the auxiliaryagent storage tank 3 and the glycol solution storage tank 1 are communicated with the refrigeratingunit 4 through a glycolsolution circulating pipeline 2 provided with a circulating pump to form a circulating loop, and glycol solution in the glycol solution storage tank 1 is cooled and circulated in an interlayer of the auxiliaryagent storage tank 3 through the refrigeratingunit 4.

Wherein, the top pipeline of the glycol solution storage tank 1 is communicated with the upper interlayer of the auxiliaryagent storage tank 3, the other is communicated with the refrigeratingunit 4, the circulating pipeline of the refrigeratingunit 4 is communicated with a circulating pump, and the bottom pipeline of the glycol solution storage tank 1 is communicated with the circulating pump. The circulating pump comprises an ethylene glycol solution A/B circulating pump 6 and an ethylene glycol solution circulating pump 5, wherein the ethylene glycol solution A/B circulating pump 6 is respectively communicated with a liquid outlet of the ethylene glycol solution storage tank 1, and the ethylene glycol solution circulating pump 5 is communicated with a liquid inlet of the ethylene glycol solution storage tank 1. The top pipeline of the glycol solution storage tank 1 is communicated with the liquid inlet of the refrigeratingunit 4, and the liquid outlet of the refrigeratingunit 4 is communicated with the circulating pump to the bottom interlayer of the auxiliaryagent storage tank 3 through the circulating pipeline. Control valves are respectively arranged on the inlet and the outlet of the upper part and the bottom interlayer of the auxiliaryagent storage tank 3, and the inlet and the outlet of the glycol solution storage tank 1 communicated with the refrigeratingunit 4 are respectively provided with control valves; control valves are respectively arranged on the liquid inlets and the liquid outlets of the glycol solution circulating pump 5 and the glycol solution A/B circulating pump 6.

In the production process, the auxiliary agent is stored in an auxiliaryagent storage tank 3, the auxiliaryagent storage tank 3 is in a jacket form, an ethylene glycol aqueous solution is arranged in the jacket, and the heat exchange effect of the ethylene glycol aqueous solution is forcedly utilized through an ethylene glycol solution A/B circulating pump 6, so that the temperature of the auxiliary agent is maintained at-10 to-20 ℃ (different temperatures are provided for different auxiliary agents). The glycol solution is stored in a glycol solution storage tank, and the glycol solution circulating pump 5 allows the glycol aqueous solution to pass through the refrigerator to maintain its temperature. When the addition agent is needed to be added into the polymerization kettle, the initiator is metered into the kettle through a weighing tank.

The system utilizes the characteristics that the glycol has high boiling point (boiling point: 107 ℃), is not easy to evaporate and lose in use, has low freezing point (freezing point: minus 40 ℃), can reach minus 50 ℃ when the water content is 95%, has high flash point, is not easy to catch fire, has good safety, is suitable for severe cold areas and is also suitable for heat exchange requirements, and the system adopts the following concentration ratio by mass: 55% of ethylene glycol and 45% of water are prepared into an ethylene glycol circulating liquid, and the circulating liquid is easy to obtain raw materials and is an antifreezing solution widely applied at present.

Ethylene glycol itself is a relatively active substance, and ethylene glycol contains hydroxyl groups, is easily polymerized into a high molecular polymer, is further oxidized into a polymer organic acid (commonly called sludge), and corrodes a water tank and a water jacket to leak the polymer organic acid, so that a preservative is also necessary in the prepared antifreeze to prevent corrosion and scale formation of steel and aluminum. And very sticky substances are easy to form, and scaling is easy to occur after deposition; and the ethylene glycol reacts with oxygen to generate trace formic acid and acetic acid. Acidity is necessary as an antifreeze because the presence of alkaline scale on the radiator reduces the heat dissipation.

Therefore, the ethylene glycol antifreeze solution is added with weak acid disodium hydrogen phosphate as an anticorrosive agent, and 2.5-3.5 g of disodium hydrogen phosphate is generally added per liter of antifreeze solution, so that the concentration of disodium hydrogen phosphate in ethylene glycol volatilized for a long time becomes high, and the acidity is slightly enhanced; on the other hand, ethylene glycol reacts with oxygen to generate trace formic acid, acetic acid and ethylene glycol aqueous solution, which are similar to common aqueous solution and other concentration ethylene glycol aqueous solutions, have corrosiveness to carbon steel, copper, aluminum, zinc and other materials, but have no common calcium chloride and sodium chloride brine with high corrosion speed.

Therefore, the system adopts the following mixture ratio of glycol refrigerating fluid:

25-35% of ethylene glycol; disodium hydrogen phosphate 0.25-0.35%; borax 2.5-3.0%; sodium benzoate 0.35-0.50%; 0.12 to 0.15 percent of tolyltriazole TTA; 0.12 to 0.15 percent of scale inhibitor; the balance of deionized water.

Further, a 10 degree glycol solution was formulated to 25% freezing point of-12 degrees. If the refrigerating temperature of the refrigerating medium solution is about-10 ℃, the freezing point of the solution must be about 10 ℃ lower than the refrigerating temperature, otherwise, the refrigerating temperature is not the refrigerating temperature, namely the solution at-20 ℃ (freezing point) and the concentration is 35%.

The addition of the methylbenzotriazole (TTA) in the glycol refrigerating fluid can prevent and inhibit rust and corrosion of zinc metal and the like; the addition of borax and sodium benzoate can realize corrosion prevention; the scale inhibitor of YX-94 series of Jiangsu Han light industry Co., ltd is mainly used for scale inhibition and scale prevention of glycol solution circulation pipelines and devices.

The following examples are given to further illustrate the effects of the present invention.

After the glycol circulating liquid is adopted, the refrigerating fluid in the interlayer of the storage tank does not have the phenomena of leakage and deposition scaling caused by corrosion of the water tank and the water jacket after the system circulates for half a year, and the system is stable in operation. Therefore, the glycol solution refrigeration system and the glycol circulation liquid designed by the invention solve the problems existing in the existing polyvinyl chloride production, and are glycol refrigeration circulation liquid with excellent performance.

The invention is not limited to the above embodiments, and based on the technical solution disclosed in the invention, a person skilled in the art may make some substitutions and modifications to some technical features thereof without creative effort according to the technical content disclosed, and all the substitutions and modifications are within the protection scope of the invention.

Claims (5)

1. The glycol solution refrigerating system is characterized by comprising an auxiliary agent storage tank (3), a glycol solution storage tank (1) and a refrigerating unit (4), wherein the auxiliary agent storage tank (3) and the glycol solution storage tank (1) are communicated with the refrigerating unit (4) through a glycol solution circulating pipeline (2) provided with a circulating pump to form a circulating loop, and glycol circulating liquid in the glycol solution storage tank (1) is cooled and circulated in an interlayer of the auxiliary agent storage tank (3) through the refrigerating unit (4);

the ethylene glycol circulating liquid comprises the following raw materials in percentage by mass:

25-35% of ethylene glycol; disodium hydrogen phosphate 0.25-0.35%; borax 2.5-3.0%; 0.35-0.50% of sodium benzoate; 0.12 to 0.15 percent of tolyltriazole TTA; 0.12-0.15% of an antisludging agent; the balance of deionized water;

the antisludging agent is YX-94 antisludging agent;

when the temperature of the ethylene glycol circulating liquid is-20 ℃, the ethylene glycol is 35%; when the ethylene glycol circulation liquid is at-10 ℃, the ethylene glycol is 25%.

2. The glycol solution refrigerating system according to claim 1, wherein a top pipeline of the glycol solution storage tank (1) is communicated with an upper interlayer of the auxiliary agent storage tank (3), and another pipeline of the glycol solution storage tank is communicated with the refrigerating unit (4), and a circulating pump is communicated with a circulating pipeline of the refrigerating unit (4); the bottom pipeline of the glycol solution storage tank (1) is communicated with a circulating pump.

3. The glycol solution refrigeration system according to claim 2, wherein the circulating pump comprises a glycol solution a/B circulating pump (6) and a glycol solution circulating pump (5), the glycol solution a/B circulating pump (6) is respectively communicated with a liquid outlet of the glycol solution storage tank (1), and the glycol solution circulating pump (5) is communicated with a liquid inlet of the glycol solution storage tank (1).

4. The glycol solution refrigeration system according to claim 2, wherein the top pipeline of the glycol solution storage tank (1) is communicated with the liquid inlet of the refrigerating unit (4), and the liquid outlet of the refrigerating unit (4) is communicated with the circulating pump to the bottom interlayer of the auxiliary agent storage tank (3) through the circulating pipeline.

5. The glycol solution refrigeration system according to claim 1, wherein control valves are respectively arranged on the inlets and outlets of the auxiliary agent storage tank (3), the glycol solution storage tank (1) and the refrigerating unit (4).

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