01 summary
Considering the low degree of automation of special resin production process, frequent need for manual operation, the risk of misoperation is large, a resin factory in Hebei Province, through independent R & D and improvement, realized automation of some manual operations, improved the automation level of production system, reduced labor intensity, and ensured the efficient operation of production system. In the automatic control system of special resin production, NHR series instruments mainly realize the functions of signal acquisition, measurement, control, accumulation, recording, networking communication, etc. the product is developed according to the national standard GB / T 34049-2017, and is mainly designed to solve the problems of flow measurement, flow measurement, flow batch control and flow networking. The EMC design of the product conforms to the relevant provisions of GB / t17626.2-11, and the product has obtained CE certification.
02 market background of products
A resin factory in Hebei uses micro suspension polymerization method to produce special resin, which is widely used in wallpaper, medical gloves, toys, sports floor and other fields. In the production process, due to the low level of automation of the production process, the number of manual operations is relatively frequent in the production. Secondly, it is necessary to strictly monitor the process indicators and strictly follow the operation procedures. In order to solve many problems encountered in resin production, the plant introduced a new control concept to the polymerizer coating operation and the addition of defoamer and viscosity reducer After a series of equipment transformation, the automation level has been further improved.
03 main technical principles of products
1. Polymerizer coating operation
Before the revamping, manual spraying is required for the coating operation of polymerizer. The coating pipeline is connected with automatic pistol spray gun with black rubber hose. Before the feeding of polymerizer, manual spraying is carried out around the wall of polymerizer. Due to the use of manual spray gun, some dead corners such as the top, stirring and bottom of polymerizer cannot be sprayed during the coating process, and the thickness of coating on the wall of polymerizer is affected by human factors, uneven and missing. In addition, temporary hose is used for manual operation for washing after coating kettle, and problems such as incomplete washing exist. Before the revamping of the coating kettle, the poor effect of the overall coating kettle has brought many adverse effects on the production. First of all, a large number of scale on the wall of the reactor directly affects the heat exchange capacity of the polymerization reactor, the heat removal rate of the polymerization reaction decreases, and there are many slags generated in the polymerization process, which causes the consumption of raw and auxiliary materials to rise. Second, it is difficult to clean up the polymerizer, which frequently causes the manual lowering of the reactor to clean up the material block, with long time, high labor intensity and impact on the production. Third, it is black The rubber hose is not tightly sealed, which is easy to cause leakage of the coating kettle liquid. The interface is broken, which causes a lot of splashing of the coating kettle liquid on the employees, and the operation environment is poor.
After the transformation, the automatic coating kettle device was introduced, two electric spray valves were added on the top of the polymerizer kettle, one coating kettle liquid pump, one washing water pump and one coating kettle liquid storage tank were added. The coating kettle liquid is stored in the coating kettle liquid tank. The specified amount of coating kettle liquid is sent from the storage tank and injected into the washing water pipe of the polymerization kettle through steam gasification. The mixture of steam and coating kettle liquid is sprayed into the polymerization kettle through the electric spray valve on the top of the polymerization kettle and solidified on the surface of the kettle wall and internal components in the polymerization kettle. See Fig. 1 for the process flow diagram of automatic coating kettle.
2. Addition of defoamer and viscosity reducer
Before the revamping, defoamer and viscosity reducer should be added to the polymerizer after the reaction. As the viscosity tank is above the polymerizer, it is about 3M from the ground, Every time the operator needs to use the mobile ladder to carry the defoamer and viscosity reducing agent to the car and add them into the tank. Because there are many pipelines around the viscosity reducing agent tank that are blocked to some extent, it is easy to cause the agent to spill and pollute the operation environment, and even cause the operation accident due to the valve at the inlet forgetting to close.
The improved defoamer / viscosity reducer automatic adding device adds a defoamer tank, a viscosity reducer tank and a feeding pump around the polymerizer. The defoamer tank and viscosity reducer tank are configured once a week on average. When the auxiliary agent needs to be added to the reactor, only the flowmeter needs to add the accurate amount to the original viscosity reducer tank, and the automatic adding process is shown in Figure 2.
04 application of products
The production process interlock diagram of a special resin factory in Hebei is shown in Figure 3.
The whole special resin production process needs to detect the stop signal of the ion-exchange membrane, the pressure of the hydrogen header, the pressure of the chlorine header, the pressure of the circulating water header, the pressure of the absorption water pump and the hydrogen chloride ratio of the synthetic furnace, etc., during the operation of the synthetic furnace It is necessary to control the pressure of the main circulating water pipe for 90 seconds, the pressure of the absorption water pump for 180 seconds, and the hydrogen chloride ratio of the synthesis furnace for 1 second. Then the synthesis furnace is in emergency shutdown to realize the interlock closing of relevant valves and filling of hydrogen.
Configuration of reaction instrument of synthesis furnace
1. Nhr-5700c multi loop measurement display controller
Realize the signal detection of hydrogen header pressure, chlorine header pressure, circulating water header pressure, absorption water pump pressure, etc
2. Nhr-8300 series 8-way color regulation paperless recorder
In order to control the ratio of hydrogen and chlorine in the synthesis furnace, channel 1 of 8-way adjusting paperless recorder of nhr-8300 series is used as the input channel of the control loop, and the ratio setting of the control loop is used as channel 2, channel 2 carries out the KX migration, thus realizing the ratio adjustment of a = KB
Polymerizer for special resin production
Configuration of automatic coating kettle operation instrument
Nhr-5600a flow totalizing controller
Realize steam gasification measurement, coating liquid flow measurement and flushing water flow measurement and detection of coating kettle of polymerization kettle
In practical application, the meter can accurately calculate the material flow according to the frequency, close the solenoid valve timely according to the value set by the user, and achieve accurate batch control blanking. The introduction of automatic coating kettle operation to realize automatic transformation, combined with the use of imported coating kettle liquid, the effect of anti coating kettle is greatly improved, the slag material ratio is significantly reduced before the transformation, the operation of automatic coating kettle is carried out in a closed polymerization kettle, the process of automatic coating kettle will not affect the site environment, and the expected goal of transforming the working environment of employees and reducing the labor intensity of employees has been successfully achieved.
Defoamer and viscosity reducer produced by special resin
Automatic operation instrument configuration of
Nhr-5600a flow totalizing controller
Realize the measurement and detection of assistant in the automatic operation of defoamer and viscosity reducer
In practical application, the meter can accurately calculate the material flow according to the frequency, close the solenoid valve timely according to the value set by the user, and achieve accurate batch control blanking. The automatic operation of introducing defoamer and viscosity reducer. Each time the auxiliary agent is added to the polymerizer, only the automatic adding procedure needs to be started, and it is added to the viscosity reducer tank by the flowmeter accurately. The adding amount can reach the set value, without intervention, which can significantly reduce the labor intensity of the staff, avoid the auxiliary agent spilling when adding manually, and further improve the working environment.
Product picture
Nhr-5600a flow totalizer
Nhr-5700c multichannel inspection instrument
Nhr-8300 ratio controller
05 conclusion
Combined with the process control of the above two processes, NHR series instruments can be better applied to the occasions of signal detection, flow measurement and ratio control in the automation system. Through the automatic transformation, the utilization rate of the equipment is improved and the artificial fault is greatly reduced. Combined with the control algorithm model of the whole system and intelligent automation tools such as DCS, online detection, monitoring, diagnosis and intelligent control of the whole production process are carried out to achieve various optimal economic indicators, improve economic efficiency and labor productivity, save energy, improve labor conditions and protect the environment. It provides necessary guarantee for stable production, quality, environmental protection and safety production.