CN1007984B - Temperature controlling method for polymerization reactors - Google Patents
Temperature controlling method for polymerization reactorsInfo
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- CN1007984B CN1007984B CN 85106346 CN85106346A CN1007984B CN 1007984 B CN1007984 B CN 1007984B CN 85106346 CN85106346 CN 85106346 CN 85106346 A CN85106346 A CN 85106346A CN 1007984 B CN1007984 B CN 1007984B
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- condenser
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Abstract
一种回流冷凝器，由于其冷却效率的增加以及节约能量而改进了生产能力，近来常用于大型聚合反应器。已知的冷却方法存在的问题是总传热系数随着聚合作用的进行而降低，其结果降低了散热能力和聚合反应温度控制的稳定性。本发明以冷凝器所除去的热量作为变量并从冷凝器间歇排放出一部分未反应的单体来进行温度控制，解决了上述问题。
A type of reflux condenser that improves throughput due to its increased cooling efficiency and energy savings, and is recently commonly used in large polymerization reactors. A problem with the known cooling methods is that the overall heat transfer coefficient decreases as the polymerization progresses, with the result that the heat dissipation capability and the stability of the temperature control of the polymerization reaction are reduced. The present invention solves the above-mentioned problems by taking the heat removed by the condenser as a variable and intermittently discharging a part of unreacted monomers from the condenser for temperature control.
Description
The present invention relates to a kind of reflux exchanger, because the raising and the conserve energy of its cooling efficiency, from the viewpoint of boosting productivity, this reflux condensation mode has caused people's attention.Recently, particularly those big polymerization reactors usually adopt this condenser.There is a problem in known method of cooling, and promptly the heat transfer coefficient of reflux exchanger reduces along with the carrying out of polyreaction, and the result has reduced the stability of the ability of reducing phlegm and internal heat and polymerization temperature control.
So far, for address the above problem the method that proposes have force steam circulation enter reflux exchanger with the method (the open No.29196/1976 of Japanese Patent) that improves heat-transfer capability, with the weighted average reading that is located at one or several Temperature Detector in the reflux exchanger with the reduce phlegm and internal heat method (U.S. Patent No. 4 of ability of control, 061,848) and additive method.But last method needs expensive circulation gas blower, and back one method needs large-scale condenser because of its heat transfer coefficient is little.Therefore, these two kinds of methods usually all can not be said so satisfied.
In using reflux exchanger refrigerative method, the overall heat transfer coefficient of condenser generally is to be not less than 500Kcal/m
2Hr ℃.Yet heat transfer coefficient is low to moderate 100-150Kcal/m in actual polyreaction
2Hr ℃, this just needs very uneconomic main equipment.
Heat transfer coefficient reduces can think that (for example the air that exists before the polyreaction, polymerization starter decompose CO, the CO that produces owing to uncondensable gas in the reactor
2And N
2) enter the surface of heat-transfer pipe and accumulate in the there with condensable steam or gas (as monomer etc.).
The objective of the invention is to reduce the size of condenser and controlled polymerization temperature stably.In order to reach this purpose, use the heat from condenser, removed, and discharge a part of unreacted monomer vapor from the reflux exchanger discontinuous of liquid polymerization and come control reaction temperature as controlled variable.
Compare with the method for routine, the heat transfer coefficient of condenser of the present invention can improve more than 2 times or 2 times, thus the size of condenser can reduce to half or littler; Temperature control of the present invention is more stable, thereby can reach productivity that improves polyreaction and the purpose that reduces cost.
Fig. 1 is mounted in the hierarchy of control diagram example of the reflux exchanger on the polymerization reactor.
Temperature (T when Fig. 2 is to use the method for example 3 in the reactor
R) change curve.
Temperature changing curve diagram when Fig. 3 is to use the method for comparison example 3 in the reactor.
The present invention relates to be equipped with the temperature-controlled process of the liquid-phase polymerization device of reflux condenser (lower abbreviation condenser).
The problem that reduces in order to solve heat transfer coefficient, condensable vapours or gas are to emit off and on from reactor at distance reactor condenser position far away in the mode that the steam of new condensation or gas are not shunted. Use the method, owing to replaced by steam or the gas of new condensation at condensable vapours or the gas of the noncondensable gas that contains high concentration of tube surface, so improved the heat transfer coefficient of condenser, also reduced the volume of condenser simultaneously.
Yet, generally when monomer vapor when condenser discharges because the heat transfer coefficient flip-flop, the temperature in the reactor can reduce the temperature that cause in chuck and the reactor suddenly and produce very big change.The result causes control to become unstable and makes the uncontrollable danger of reaction.The unexpected increase of the heat of being removed can make the reaction liquid foaming and overflow into condenser.This overflow can cause operational issue, is aggregated that incrustation stops up and as the quality product deterioration of flake and so on as the pipeline between condenser internal surface incrustation, reactor and the condenser.
For example, use vinylchlorid that condenser is arranged be aggregated in operation in the time of about 3 hours after and about 10 minutes monomer vapor discharging, its heat transfer coefficient rises to 700Kcal/m
2Hr ℃, but the flip-flop of this coefficient makes the temperature reduction suddenly in the reactor can cause above-mentioned danger.
So the temperature with the water coolant of condenser in the system of heat transfer coefficient flip-flop can not accurately be controlled as the conventional control method of controlled variable.
Used in the present invention control method is to measure flow rate and its import and export temperature (T of water coolant (F)
2) and (T
3), be calculated as follows the heat that the device that is condensed is removed:
Q
RC＝C
p·ρ·F（T
3-T
2）
(C in the formula
pBe specific heat, ρ is a density), and with the value of gained as controlled variable.
Method provided by the invention is as follows: in the polymerization of using condenser, the method for temperature in the controlling reactor is characterised in that said temperature is also to give off a part of unreacted monomer from reflux exchanger off and on the heat that condenser is removed as controlled variable to control.
Fig. 1 is one embodiment of the invention, in order to the control of the condenser that polyreaction is installed to be described.In Fig. 1, (1) is polymerization reactor; (2) be reflux exchanger; (3) and (4) be the cooling water control valve; (5) be unreacted gas emitting valve; (6) be the unreacting gas retrieving arrangement; (7) be cooling tower; (8) be the chilled(cooling) water supply (CWS) pump; (9) and (10) be cooling water circulating pump.
In the present invention, have from the method for the unreacted monomer vapor of condenser (a 2) intermittently discharged part: with time variable control one of a timed interval discharging of determining the short time simple method and read the method for the reading of water cooler heat extraction amount controller (QRC/5) in definite timed interval, as long as reading does not reach set(ting)value, discharging will be proceeded the time of a weak point.
In the present invention, the control of temperature of reactor (annotation of translation: i.e. temperature in the reactor) is that the output valve that set(ting)value with reactor jacket temperature controller (TRC/6) is set in temperature of reactor controller (TRC/1) is carried out.In other words, the cascade between available TRC/1 and QRC/5 controls controlled temperature.In addition, also the set(ting)value of condenser heat extraction heat controller (TRC/5) can be set in the output valve of TRC/1 or the output valve that the two set(ting)value of TRC/6 and TRC/5 is set in TRC/1 controlled.For the temperature and the flow rate of control condenser cooling water, the set(ting)value of condenser cooling water temperature out controller (TRC/3) or condenser cooling water inlet temperature controller (TRC/2) or condenser cooling water flow rate controller (FRC/4) is set in the output valve of QRC/5.
For example, adopt the set(ting)value of QRC/5 to be set in the output valve of TRC/1, and then, just can reach rapidly and the control of high stable with the cascade connection type control method that the output valve of QRC/5 is regulated cooling water control valve (3).
In addition, adopt the output valve that the set(ting)value of TRC/2, TRC/3 or FRC/4 is set in QRC/5, and then regulate said valve (3), can improve controllability widely with the output valve of TRC/2, TRC/3 or FRC/4.
For unreacted monomer, continuous blow-down has increased the amount of gaseous emission, has consequently reduced the transformation efficiency and the productivity of reaction, has also increased the cost of the monomer compression purifying that reclaims simultaneously, so quantity discharged should be greater than required amount.For fear of too much quantity discharged, discharging answers intermittent type ground to carry out.For example Pai Fang limiting time is preferably 0.5 second to 20 minutes, preferably 30 seconds to the 2 hours timed interval of qualification.So just can guarantee to be not less than 500Kcal/m
2Hr ℃ high heat transfer coefficient.
As for discharging number of times and vapor discharge speed, with regard to unhinderedly obtaining the necessary heat transfer coefficient of heat extraction, preferably the vapor volume with discharging minimizes.Constantly check the reading of set(ting)value and QRC/5 and only when reading reaches set(ting)value, do not discharge with computer, the vapor volume of discharging is reduced in a large number and reach the stable purpose of controlling.Checked the heat that the device that once is condensed is removed in preferably every 1-30 minute.The timed interval is unwanted less than 1 minute frequent inspection, and such inspection also is disadvantageous with regard to the runtime of computer; If but, just relatively large discharging need be arranged interval greater than 30 minutes, could make control be tending towards unstable.Drain time is preferably 0.5 second to 5 minutes, owing to there being the response valve time to make discharging not enough, probably makes control become unstable greater than 5 minutes during less than 0.5 second.The gaseous emission rate is preferably at per unit body (m
3) in the scope of polymerization reactor 10-500Kg/hr, ER for emission rate is lower than 10Kg/m
3Effect is less during hr, greater than 500Kg/m
3May be stopped up by reaction product owing to foaming makes outfall pipeline during hr, the preferential especially ER for emission rate scope of selecting is 100-200Kg/m
3Hr.
The control method of polymerization reactor of the present invention can be used for any liquid-phase reaction system, comprises for example divinyl letex polymerization, vinylchlorid suspension or the equal polymerization of emulsion or copolymerization, vinylidene chloride letex polymerization, vinylbenzene or systems such as propylene class monomer block, suspension or letex polymerization.
If the present invention is used to be lower than the low pressure system of barometric point, just a reliever should be installed in unreacting gas recovery system (6).
" condensable steam or gas " i.e. is the steam or the gas of energy condensation in reflux exchanger, and the setting of this reflux exchanger is in order to remove the heat of polymerization that liquid phase reaction produces.The steam of monomer itself for example, the solvent vapour during solution polymerization adds the steam of the boiling reagent in the reaction system.
Now the present invention will be described with following each embodiment.
Example 1
At 30m
3Polymerization reactor on installation-70m
2Condenser, condenser passes to 80 ℃ hot water, adds 13 then in reactor, the partly-hydrolysed polyvinyl alcohol water solution of the deionized water of 000Kg, the peroxide of 8.7Kg two carbonic acid two (2-ethylhexyl ester) and 230 liter 3%.Polymerization reactor adds 13 through stirring the degassing after 15 minutes, and 000Kg ethene chlorine monomer ℃ makes polymerization reaction take place with mixture heating up to 58.The set(ting)value of reactor jacket temperature controller is set in the output valve of temperature of reactor controller.When polymerization conversion reached 5%, beginning passed to water coolant to condenser.After the set(ting)value with the cooling water outlet temperature controller of condenser is set in the output valve of condenser heat extraction amount controller, carry out time variable control, the heat that condenser is removed increases to 500,000Kcal/hr gradually.
After condenser passes to water coolant, with the ER for emission rate of 3600Kg/hr in condenser overhead every 10 minutes 5 seconds of discharging monomer.The interior temperature of reactor this moment is stable, and controllability is fine, and the heat transfer coefficient of condenser is 500-700Kcal/m
2Hr ℃.Emission gases total amount when polyreaction is finished is about 180kg.
Example 2
Make the beginning polymerization reaction take place by the method identical with example 1.When transformation efficiency reaches 5%, to react that chuck cooling water control device is constant to be controlled at 35 ℃, regulate the water of condensation control valve by cascade connection type control method (set(ting)value of its condenser heat extraction amount controller is set in the output valve of temperature of reactor controller, and the set(ting)value of condenser cooling water flow rate controller is set in the output valve of condenser heat extraction amount controller) with the output valve of condenser cooling water flow rate controller then.After condenser passes to water coolant, every the set(ting)value and the reading of 2 minutes inspection primary condenser heat extraction amount controllers, if reading does not reach set(ting)value, then with 5, the ER for emission rate of 400Kg/hr discharging monomer gas 2 minutes.Temperature in the reactor is very stable at this moment, and controllability is fine, and the condenser heat transfer coefficient is 400-600Kcal/m
2Hr ℃, the about 60Kg of the gross exhaust gas after polymerization is finished.
Example 3
Make the beginning polyreaction by the method identical with example 1.When transformation efficiency reaches 5%, be controlled at 35 ℃ with reactor jacket cooling water control device is constant, press cascade connection type control method (output valve of its condenser heat extraction amount controller) then and regulate the cooling water control valve with the output valve of condenser cooling water inlet temperature controller, after water coolant fed condenser, set(ting)value and reading every 5 minutes inspection primary condenser heat extraction amount controllers, if reading does not reach set(ting)value, then discharged monomer 3 minutes with the ER for emission rate of 4800Kg/hr.As a result, the temperature (T in the reactor
R) very stable (as shown in Figure 2), heat transfer coefficient is 400-500Kcal/m
2Hr ℃, the gas total release is about 100kg.The temperature of the condenser cooling water among Fig. 2, chuck temperature of cooling water and beginning are led to the time of water coolant respectively with T to condenser
RC, Jj and Spc represent it.
Embodiment 4
Carry out polyreaction by the method identical with example 3.When carrying out, reaction compares mutually every 20 minutes set(ting)value and readings with condenser heat extraction amount controller.If reading does not reach set(ting)value, then with discharge value discharging monomer 4 minutes, the result of 450Kg/hr, the temperature in the reactor is stable, and the condenser heat transfer coefficient is 300-400Kcal/m
2Hr ℃, the total gas emissions after polyreaction is finished is about 300Kg.
Comparison example 1
Make the beginning polyreaction by the method identical, but use the amount of peroxidation carbonic acid two (2-ethylhexyl ester) to be 3.9Kg with example 1.When transformation efficiency reaches 5%, water coolant is fed condenser gradually and is controlled at 35 ℃ with the condenser cooling water temperature out is constant.After water coolant passes through condenser, with the ER for emission rate continuous blow-down gas of about 50Kg/hr.As a result, heat transfer coefficient is low to moderate 200-250Kcal/m
2Hr ℃, total emission gases amount is about 300Kg.
Comparison example 2
Make the beginning polyreaction by the method identical, when transformation efficiency reaches 5%, gradually water coolant is fed condenser and the condenser cooling water temperature out is controlled at 35 ℃ with example 1.After water coolant passes through condenser, with the ER for emission rate continuous blow-down gas of about 500Kg/hr.As a result, heat transfer coefficient is 300-400Kcal/m
2Hr ℃, require the gas volume of discharging big to about 3000Kg.
Comparison example 3
Make the beginning polyreaction by the method identical with example 1.When transformation efficiency reaches 5%, the temperature (T of condenser cooling water
RC) constantly being controlled at 35 ℃, beginning was to back 1 hour of the logical water coolant (Spc) of condenser, with ER for emission rate discharging (P) gas of 3600Kg/hr 10 minutes.Heat transfer coefficient before the discharging is 150Kcal/m
2Hr ℃, but reach 700Kcal/m immediately after the discharging
2Hr ℃, reduce to 300Kcal/m then gradually
2Hr ℃.Temperature (T in the reactor
R) descend suddenly along with discharging.Owing to making jacket temperature (Tj), bigger fluctuation becomes unstable.The temperature variation state is shown in Fig. 3.The gaseous emission total amount is about 600Kg.
Claims (8)
1, method of temperature in a kind of liquid-phase polymerization controlling reactor of using condenser is characterized in that said temperature is that the heat removed in order to reflux exchanger is as controlled variable with discharge a part of unreacted monomer off and on from reflux exchanger and control.
2, the process of claim 1 wherein that said temperature is that the output valve that set(ting)value with condenser heat extraction amount controller is set in the temperature of reactor controller is controlled.
3, the process of claim 1 wherein that said temperature is the output valve that the set(ting)value of reactor jacket temperature controller is set in the temperature of reactor controller, the set(ting)value of condenser heat extraction amount controller is programme controlled.
4, the process of claim 1 wherein that the cooling water control valve is to regulate with the output valve of condenser heat extraction amount controller.
5, the process of claim 1 wherein that the heat of being removed by condenser is that set(ting)value with condenser cooling water temperature regulator or condenser cooling water flow director is set in the output valve of condenser heat extraction amount controller and regulates the condenser cooling water control valve with the output valve of condenser cooling water temperature regulator or condenser cooling water flow rate controller and control.
The flow rate of the gas that the unit volume polymerization reactor is discharged when 6, the process of claim 1 wherein discharging is 10-500Kg/m
2Hr.
7, the process of claim 1 wherein that the discharging of unreacted monomer is every discharging in 30 seconds to 2 hours 0.5 second to 20 minutes.
8, the process of claim 1 wherein the setting of condenser heat extraction amount controller and reading be per 30 seconds to 30 minutes mutually more once; If reading does not reach set(ting)value, with unreacted monomer discharging 0.5 second to 5 minutes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85106346 CN1007984B (en) | 1984-07-27 | 1985-08-24 | Temperature controlling method for polymerization reactors |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59158433A JPS6136301A (en) | 1984-07-27 | 1984-07-27 | Method for controlling temperature in polymerization reactor |
| CN 85106346 CN1007984B (en) | 1984-07-27 | 1985-08-24 | Temperature controlling method for polymerization reactors |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN85106346A CN85106346A (en) | 1987-03-18 |
| CN1007984B true CN1007984B (en) | 1990-05-16 |
Family
ID=25741981
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 85106346 Expired CN1007984B (en) | 1984-07-27 | 1985-08-24 | Temperature controlling method for polymerization reactors |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1007984B (en) |
-
1985
- 1985-08-24 CN CN 85106346 patent/CN1007984B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CN85106346A (en) | 1987-03-18 |
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