Gansu Rare Company caustic soda plant is now using 15000ta diaphragm production line, annual output of liquid chlorine 0.3 ~ 10,000t, the original liquid chlorine filling and measuring device using the ground scale, manual filling, due to the backwardness of the equipment and maintenance is frequent, does not meet the requirements of the chlor-alkali industry safety production, in November 2007, the process of system optimization, the use of more advanced SCS-2-type computerized automatic fixed-value automatic liquid chlorine filling machine In November 2007, the system optimization of this process was carried out by adopting the more advanced SCS-2 computerized automatic liquid chlorine filling machine with fixed value, which realizes computer monitoring, automatic filling, fault (leakage, overweight) detection and alarm, prevents environmental pollution caused by chlorine leakage, thus guaranteeing the safety of the operation process and meeting the requirements of safe production in chlor-alkali industry.

1 Problems before the transformation and after the transformation of the workflow is briefly described

1.1 Problems before remodeling

(1) The plant's liquid chlorine products are all exported, most users use liquid chlorine cylinders for transportation. And the ground scale filling labor intensity is relatively large, in the filling process at any time to check the filling status, do not allow overfilling, overloading, overpressure out of the station, such as overfilling, overloading, overpressure must be unloaded to deal with before release, otherwise in the process of transportation, use will be the risk of leakage and explosion. (2) liquid chlorine packaging operation, may lead to liquid chlorine cylinder explosion is generally overfilled, when the temperature rises, the liquid expansion, and cause fusible plug leakage, so that the container explosion. For this reason, when tanking liquid chlorine, the weight should be strictly controlled and reweighed to avoid overfilling accidents. (3) The plant has been built since 1988, the plant has been using ground weighing measurement filling, due to the aging of the equipment, maintenance is frequent, the operation is not convenient, resulting in recent years the production cost of maintenance costs remain high. In view of the above problems, the plant of liquid chlorine filling process equipment for the replacement and transformation, using SCS-2 type computer automatic quantitative liquid chlorine automatic filling machine.

1.2 Liquid chlorine filling system after transformation

(1) Chlorine treatment system process flow is briefly described in the plant chlorine treatment system process is the first wet chlorine through the chlorine Le scrubber tower, titanium cooler cooling, three-stage (with 75%, 85%, 95% sulfuric acid) drying tower in addition to impurities; and then dry chlorine through the froth trap, into the fluorine refrigeration unit for liquefaction, after gas-liquid separation, liquid chlorine into the liquid chlorine storage tanks, the end of the chlorine for the synthesis of hydrochloric acid: the final use of liquid chlorine shielded pumps, the Finally, using liquid chlorine shield pump, the storage tank liquid chlorine through the submerged pump transportation, pressurization and packaging (liquid chlorine packaging pressure less than 1.5MPa).

(2) After the transformation of the liquid chlorine packaging process on the ground weighing metering filling and packaging scales transformed into SCS-2 type computer automatic quantitative liquid chlorine automatic filling machine electronic scales, the specific filling process is to start the computer control system, liquid chlorine cylinders lifted to the electronic scales scale platform, connecting liquid chlorine cylinders copper pipe joints, start the control box filling switches; the controller automatically controls the filling chlorine pipeline pneumatic valves and solenoid valves, automatically open the valves to the cylinder high-flow filling The controller automatically controls the pneumatic valve and solenoid valve on the filling chlorine pipeline, automatically opens the valve to fill the cylinder with chlorine gas in high flow; the weighing instrument samples, and the instrument sends out an alarm signal when the filling weight reaches the set preset value; at this time, the solenoid valve installed after the pneumatic valve controls the precise filling in small flow, and the instrument sends out an audible alarm signal again when the filling weight reaches the set rated value; the controller controls the pneumatic valve and the solenoid valve to close, and the cylinder will be moved to the other same electronic scale for re-checking when the filling is completed once. electronic scale for rechecking, while the data is uploaded to the computer.

1.3 Computerized monitoring and statistical data management

(1) The man-machine interface on the computer is a three-dimensional dynamic analog graphic, and the weight of the cylinder is displayed in real time during the filling process, and at the same time, it displays the management number of the cylinder, the start time of the filling, the end time of the filling, the tare weight, the gross weight, the net weight, the filler, and the number of the filling scale.

(2) After the filling is finished, alarm prompts are carried out and a filling record is automatically formed, which contains the above contents and is saved in the computer in the form of a database.

(3) The filling database has the functions of saving, backup, recovery, querying, printing and statistics, and the data records can be queried and printed according to the date, month, using unit, cylinder number and so on.

(4) Through the data exchange with the database of cylinders in and out of the warehouse, so that the inventory, out of the warehouse, the original data, the data re-corrected after the inspection and the filling data can be automatically combined in order to be able to simultaneously in the storage of cylinders, out of the warehouse, the empty bottle stock, the heavy bottle stock and other related information to query and track, to facilitate the sales, and facilitates the relevant personnel to grasp the management of the inventory of cylinders in the storage, out of the storage, and to achieve the full range of the cylinder Tracking.

1.4 Main Functions of the Reformed System

(1) Automatic tare function: overcomes the influence of inconsistent weight of filling containers on the accuracy.

(2) Adjustable fixed value point: adapting to the quantitative filling of various weight ranges.

(3)Over-difference detection: automatically detect the over-difference of full filling.

(4)Automatic diagnosis and fault alarm to improve the reliability of safe operation in system work.

(5) Review: one electronic scale weighing, another electronic scale review to ensure that the data is accurate, while mutual calibration of the two electronic scales whether there is a failure.

2 put into operation after the effect achieved

(1) safe packaging. Filling and weighing, and reweighing, to eliminate the occurrence of liquid chlorine cylinder overloading accidents. The filling process realizes automatic computerized quantitative control, zero leakage packaging, and the system is equipped with over-quantity alarm, leakage alarm and fault alarm device, which fully meets the safe production requirements of the State General Administration of Safety Supervision on the packaging of hazardous chemicals in the chemical industry.

(2) Reduce the labor intensity of packaging positions. After the transformation of the liquid chlorine filling operation is easy to realize the liquid chlorine automatic fixed-value filling control process, greatly reducing the labor intensity of workers.

(3) Improved environment. This device adopts computer monitoring, automatic filling, fault (leakage, overweight) detection and alarm, effectively preventing environmental pollution caused by chlorine leakage, improving the working environment to meet the environmental requirements of the chemical industry production, and the social benefits are significant!

(4) Improved chlorine yield. After the transformation, the leakage problem in the filling process is eliminated, the leakage waste in the filling process is avoided, and the chlorine yield is improved.

3 Conclusion

The plant has installed two sets of (2 sets of weighing, 2 sets of double-checking) SCS-2 computerized fixed-value liquid chlorine metering and filling machine, operation so far, the filling process is simple to operate, accurate filling, safe and reliable, to put an end to the phenomenon of overfilling of liquid chlorine cylinders to ensure the safety of the operation process, to meet the chlor-alkali industry on the liquid chlorine filling, transportation, use of the process of safe production specifications of the relevant requirements, can be promoted in the industry and other liquid hazardous chemicals packaging industry. It can be popularized and applied in the same industry and other liquid hazardous chemicals packaging industry.