Form 2
The Patent Act 70
(Act 39 of 70)
COMPLETE SPECIFICATION
(Section 10)
AN IMPROVED PROCESS FOR THE MANUFACTURE OF CHLOROPRENE BY EMPLOYING AC DRIVE FOR PROCESS CONTROL
PIDILITE INDUSTRIES LIMITED, A COMPANY REGISTERED UNDER THE INDIAN
COMPANIES ACT 1956 HAVING ITS REGISTERED OFFICE LOCATED AT REGENT
CHAMBERS, NARIMAN POINT, MUMBAI-400021, MAHARASHTRA, INDIA
The following description particularly describes the nature the invention and the manner which it is to be performed

Field of Invention:
The invention relates to an improved process for the manufacture of chloroprene. The present invention particularly relates to an improved process for the manufacture of chloroprene wherein the flow of HC1 solution generated during the process is controlled by employing AC drives avoiding the use of the control valves. The improved process of the present invention can be used to control parameters like flow & level in chloroprene manufacturing process plant. The present invention eliminates the use of control valves and thereby reduces electrical energy consumption.
• Background of Invention
Conventionally, process flow in the chloroprene manufacturing process is controlled by throttling the pump discharge by using control valve. Such a process is shown in Fig 1 of the drawing accompanying this specification. In chloroprene manufacturing process as shown in Fig.l. Butadiene (1) is reacted with chlorine (2) in the chiorination reactor (3) to form dichlorobutenes and hydrogen chloride (HCL) gas. The dichlorobutens are condensed in the condenser (4) and the HC1 gas is separated in the vapor liquid separator (5). This HC1 gas is to the scrubber (6) for scrubbing with water to form HC1 solution. Dichlorobutenes are further isomerized (7) and dehydrochlorinated (8) to give chloroprene (9). This HC1 solution is passed on to the tank (11) and then pumped by the pump (12) to the effluent treatment plant (17). Based on the level of HC1 solution in the tank (11) which is indicated by a known level transmitter (15), the flow rate of HC1 solution which is pumped to the effluent treatment plant (17) is controlled using the control valve (13) provided in the discharge line of the pump (12). Level transmitter (LIC (15)) will sense the level of HC1 solution in tank (11) and corresponding signal will be sent to a known DCS (Distributed control system). In the DCS this signal will be processed further and suitable signal will be sent to control valve to control the opening of the valve.
When the level of the HC1 solution in the tank (11) reaches a particular high level (85% of total tank level), the control valve (13) is opened fully (100%) automatically due to level indicator control(LIC (15)) and as the level reduces (25% of total tank level) in the tank (11) the opening of the control valve (13) also reduces automatically due to level indicator control(LIC (15)) as described earlier . In such a process substantial amount of electrical energy is wasted due to throttling (Throttling is act of restriction) i.e. flow is restricted at control valve.
The pump (12) operates at a fixed speed & the flow of HC1 solution is controlled by adjusting the opening (0-100%) of the control valve (13) automatically due to level indicator control (LIC (15)) as described earlier. Electrical power is proportional to cube of flow rate and square of speed. In

conventional process as the pump (12) operates at a fixed speed, the consumption of power remains same even when the flow rate is reduced using the control valve (13) automatically due to the known level indicator control (LIC (15)) resulting in the loss of electrical energy.
• Prior Art
To the best of our knowledge it is not hitherto known to control the flow of HC1 solution generated during the chloroprene manufacturing process by employing an AC motor
• Objectives of the invention
Therefore, the main objective of the present invention is to provide an improved process for the manufacture of chloroprene wherein the flow of HC1 solution generated during the process is controlled by employing an AC motor instead of valves, which eliminates the loss of energy
Still another objective of the present invention is to provide an improved process for the manufacture of chloroprene wherein the flow of HC1 solution generated during the process is controlled by employing an AC motor instead of valves and thereby reducing the chances of leakage of the HC1 solution.
• Principle by which the invention has been developed
Speed of a pump which is driven by a motor, is proportional to frequency of power supply to the motor.
N=120f/P Where N= Speed f = Frequency
P = No. of poles (Constant for a given motor)
Therefore If the frequency of the power supply is changed , the speed of the motor and that of the connected pump can be changed and the required flow of the pump can be controlled without using a control valve. Electrical power is proportional to cube of the flow rate and square of speed. If required the flow rate is less, it can be achieved by reducing the power supply frequency using AC drive which further reduces speed of motor and pump thereby reducing power consumption.
The details of the process is described with reference to the drawings .In the drawing fig 2 represents the flow sheet of the process of the present invention showing the novel aspects of the process The improved process of the present invention is shown in Fig 2

• Summary of Invention
Accordingly the present invention provides an improved process for the manufacture of chloroprene
which comprises
i) Reacting butadiene (1) with chlorine gas (2) in a chlorination reactor ( 3 ) to form
dichlorobutenes and HC1 gas ii) Passing Dichlorobutenes formed to the condenser(4) to condense dichlorobutenes iii) Passing the dichlorobutenes and HC1 gas to the vapor liquid separator (5) for separating the
HC1 gas iv) Passing the separated HC1 gas to the scrubber ( 6) for scrubbing the HC1 gas with water
introduced to the scrubber to form HC1 solution,
v) Passing the HC1 solution to the tank (11)
vi) Passing the HC1 solution in the tank (11) to the effluent treatment plant (17) through the
pump (12)) based on the level which is indicated by the known level transmitter ( LIC 15)
and controlled by a known DCS system , the flow rate of the HC1 solution from the tank
(11) being controlled by an AC drive ( 13 ) vii) Passing the dichlorobutenes coming out of the vapor liquid separator ( 5) as mentioned in
step (iii) , to an Isomerisation unit ( 7) for the isomerisation of Dichlorobutenes to 3,4-
dichlorobutene and viii) Passing the isomerised dichlorobutenes from the Unit (7) to the dehydrochlorinating unit
(8) to which unit sodium hydroxide is passed to produce chloroprene (9)
• Description of the Invention
In the present invention which is shown in figure-2, the control valve (13) shown in the prior art
process shown in the fig l is eliminated., Based on the level of HC1 solution in the tank (11) indicated by level transmitter ( LIC 15) and controlled using DCS automatically , Level transmitter (LIC(15)) will sense the level of HCI solution in tank (11) and corresponding signal will be sent to the AC drive. Based on this signal the AC drive will vary the speed of the electric motor( M) . The flow rate of the HCI solution is pumped to the effluent treatment plant (17) and is controlled by the AC drive (13). When the level of the HCI solution in the tank (11) reaches a particular high level (85% of total tank level), the AC drive (13) operates the motor (M 14 ) and the pump (12) at full speed thereby giving maximum flow rate to the pump (12) and as the level in the tank (11) reduces (25% of total tank level), the AC drive (13) operates the motor (M 14) and the pump (12) at proportionally reduce speed thereby giving the reduction in flow rate of HCI solution also reduces This operation saves electrical energy by eliminating throttling action of control valve

Distributed control system( DCS ) used in the process is basically a computerized system which operate as per predefined instruction of microprocessor based control system . DCSs are dedicated systems used to control manufacturing processes that are continuous or batch-oriented, such as oil refining, petrochemicals, central station power generation, pharmaceuticals, food & beverage manufacturing, cement production, steelmaking, and papermaking. DCSs are connected to sensors and actuators and use set point control to control the flow of material through the plant. Such systems are well know in the art and are also commonly used to control and monitor various process parameters like flow of liquids , temperature , level etc . DCS system refers to a control system usually of a manufacturing system, process or any kind of dynamic system, in which the controller elements are not central in location (like the brain) but are distributed throughout the system with each component sub¬system controlled by one or more controllers. The entire system of controllers is connected by networks for communication and monitoring.. We have used in the process of the present invention a know DCS system
Level transmitters are used to measure the level of a liquid or bulk solid material (as well as slurries) within a specified space, and to provide electrical output about these measurements that are proportional to the input level. Level transmitters are designed to measure level based on either a point level or continuous level readings. Point level transmitters provide output when a specific level measurement is reached. This output is generally in the form of an audible alarm or an electrical charge to actuate a switch. Continuous level transmitters measure level within a specified range and provide output as a continuous reading of the level. Level transmitters can operate through a wide range of temperatures, pressures, vapor gas mixtures, and process conditions.
In the process of the present invention we have used a known continuous level transmitter (LIC) for measurement of level of HC1 solution in tank. The LIC will sense the level of HCL solution in tank (11) and corresponding signal will be sent to AC drive. Based on this signal AC drive will vary the speed of the electric motor.
• Advantages of invention
The process
(a) Saves Electrical energy by eliminating throttling action of control valve
(b) Reduces carbon emission
c) Facilitates smooth operation of the process

We claim
1. An improved process for the manufacture of chloroprene which comprises
(i) Reacting butadiene (1) with chlorine gas (2) in a chlorination reactor ( 3 ) to form dichlorobutenes and HC1 gas
(ii) Passing Dichlorobutenes formed to the condenser(4) to condense dichlorobutenes
(iii) Passing the dichlorobutenes and HC1 gas to the vapor liquid separator (5) for separating the HC1 gas
(iv) Passing the separated HC1 gas to the scrubber ( 6) for scrubbing the HC1 gas with water introduced to the scrubber to form HCI solution.
(v) Passing the HCI solution to the tank (11)
(vi) Passing the HCI solution in the tank (11) to the effluent treatment plant (17) through the pump (12) ) based on the level which is indicated by level transmitter ( LIC 15) and controlled by DCS system , the flow rate of the HCI solution from the tank (11) being controlled by an AC drive ( 13)
(vii) Passing the dichlorobutenes coming out of the vapor liquid separator ( 5) as mentioned in step (iii), to an Isomerisation unit ( 7) for the isomerisation of Dichlorobutenes to 3.4-dichlorobutene and
(viii) Passing the isomerised dichlorobutenes from the Unit (7) to the dehydrochlorinating unit (8) to which unit sodium hydroxide is passed to produce chloroprene (9)
2. An improved process for the manufacture of chloroprene substantially as herein described with
reference to fig 2 of the drawing accompanying this specification