SA111320737B1 - Method of Processing Liquid Chlorine Containing Nitrogen Trichloride - Google Patents

Abstract

The present invention relates to a method for treating a stream of liquid chlorine containing nitrogen trichloride from an industrial chloralkali plant. The liquid stream is received into a vaporizer where it is evaporated to chlorine gas and nitrogen trichloride gas. The gas stream is treated by cracking the nitrogen trichloride stream, eg in a superheater or catalytic bed. The treated gas stream is recycled into the chlorine production train of the industrial chlor-alkali unit. The process avoids the use of organic solvents to decompose nitrogen trichloride and create a waste stream that requires additional processing.

Description

1 Method for treating liquid chlorine containing nitrogen trichloride

Method of processing liquid chlorine containing nitrogen trichloride FULL DESCRIPTION BACKGROUND Liquid chlorine containing nitrogen trichloride The invention relates to processing a stream of liquid chlorine from an alkaline process to produce chlorine JU from a chlorine production process. For example, nitrogen trichloride. chlorine production process nitrogen trichloride; A small amount of by-product © is produced; The amount formed in the chlorine production process is in an alkaline process for the production of chlorine. nitrogen contained in the salt fed into the process. Followed by ammonia with the amount of Auli removed from the Bale. chloralkali cell house which leaves chlorine cell house chlorine producer chlorine in chlorine wash unit JU chlorine producer through absorption step; for example in nitrogen trichloride; Before chlorine pressure and liquidity. In the washing step ¢ the scrubber is absorbed 0 New, clean chlorine product pushed into the wash unit and into the holding tank indicated and in carbon tetrachloride containing carbon tetrachloride ¢ nitrogen trichloride in an assay unit In the assay unit the solvent is set at a temperature above point. chloroform sometimes back to unit i it (ALU) boiling chlorine. When liquid chlorine comes into contact with the solvent by solvent. Nitrogen trichloride Lin chlorine scrubber Jue 0 chlorine is slowly absorbed And in a safe way. Nitrogen trichloride Choose the conditions in the analyzer unit so that it decomposes

and with the passage of time»; Tar and other impurities collect in the solvent; The solvent must be replaced periodically; And the generation of the disposed current that must be disposed of. For reasons of both regulatory constraints and product quality (i.e., to reduce the organic content of the final product chlorine), it is preferable to avoid using tetrachloride solvents (fie chloroforms©) in the chlorine production train sil. A method for making nitrogen trichloride without the use of chloroform s carbon tetrachloride solvents is described in US Patent No. 03104549 Ferguson cet al. where gas chlorine gas comes into contact with chlorine gas from a drying tower tower with hydrochloric acid prior to the compression and liquefaction step, however, the process produces an acidic waste stream that must be disposed of or used elsewhere.

It is preferable to provide an improved process for the disposal of nitrogen trichloride that has been removed from the chlorine stream without the use of organic solvents such as carbon tetrachloride or chloroform; And without generating a waste stream «a pale . General description of the invention

VO The invention provides a method for treating a stream comprising liquid chlorine containing a series

Chlorine production for the chlorine production process. The liquid stream is evaporated to produce a stream comprising chlorine gas and nitrogen trichloride gas formed by the analysis of nitrogen trichloride; The gas stream is processed by cracking nitrogen trichloride gas ¢ without the use of solvents or liquid chemicals; producing only one stream; Contains chlorine gas

_ _

chlorine gas with nitrogen gas ¢ This stream is recycled to the chlorine production train sll . The invention also provides a device for treating a stream containing liquid chlorine containing nitrogen trichloride from the chlorine production train.

© . The device includes a chlorine vaporizer with a liquid stream inlet and a boiling area after the inlet. The device includes means for cracking nitrogen trichloride gas after the boiling zone and a means for recycling the resulting stream that includes chlorine gas and nitrogen gas from the nitrogen cracking medium to the chlorine production chain. These and other features will be evident from the following description and figures for specific models.

0 BRIEF EXPLANATION OF DRAWINGS Fig. 1 is a schematic form of a prototype of the process contained in the invention; Where the nitrogen trichloride is cracked using a catalytic bed. Figure ¥ is a schematic diagram of a second process model; Where the nitrogen trichloride is cracked using a heating unit (338 watts) superheater. 0 Detailed description

In the following description and in the figures; Corresponding and similar items are indicated by the same reference numbers. As shown in Figure 1-, the chlorine vaporizer unit 01 receives a stream of liquid chlorine containing nitrogen trichloride (YY stream) from the YE chlorine production train of the unit. Industrial chlorine alkali

A chloralkali solution on the VE chlor-alkali cell housing. The chlorine production chain includes . chloralkali plant by hydrolysis of chlorine gas solution in which chlorine gas is produced 01 cell house

Electrolysis of brain . The 11 chlorine scrubbers receive a VY stream from

Chlorine gas, chlorine gas, from the cell housing, and a stream of liquid chlorine, VY liquid chlorine, was not carried into

© Figures illustrating other unit operations that Bale is located between the 01 chloralkali cell house and the Jue chlorine unit 11. The chlorine gas stream VE generated from

Bass is washed in the pressure unit 10 and then it is liquefied. From the bottom of the chlorine wash unit 11 liquid chlorine is fed; rich in nitrogen trichloride (V1 stream) in the holding tank VY from which the YY stream is alternatively routed to the evaporator To;

01 to the evaporator unit 11 directly from the scrubber unit nitrogen trichloride Ye . Part in 50 on YY without using a holding tank. Typically, the current (NTL) contains parts per million. A Yer unit produces one or more million or more nitrogen trichlorides. The current is directed to the . Nitrogen trichloride gas contains chlorine gas with 40 stream 01 vaporization is done. nitrogen trichloride One or more unit processes for cracking nitrogen trichloride

chlorine gas » nitrogen trichloride Recycle the gas that leaves the Vo cracking step of the process chlorine production train; To the production chain of chlorine nitrogen gas and nitrogen gas or waste stream the process avoids generating a waste stream. The chloralkali process is an alkaline step for the production of chlorine. Nitrogen trichloride is added to other chemicals or solvents to deal with in different ways. As shown in the samples of Figure 1; Nitrogen trichloride can be directed cracking

Ye gas formed in evaporation unit 01 to the catalytic bed of catelyti bed in which nitrogen trichloride is cracked. The catalytic layer may include; For example; on idle) Monel

0+ - commercial) as a catalyst for the destroying catalyst of nitrogen trichloride. The catalytic bed can operate at temperatures from -0 to 700°C; pressure values from 1.9 to 100 bar and residence times from 0.1 second to ¾ minutes. The oF gas stream leaving the catalytic bed is recycled; which includes chlorine gas© and nitrogen gas ¢ to the chlorine production train. As an alternative to using a catalytic bed; The gas mixture that has been vaporized in the vaporizing unit can be fed into the superheater; Which can be eda from the evaporation unit or separate from it. In the oF embodiment the evaporator unit 01 has a superheater zone 01 after boiling zone 1©. The operating conditions of the superheater are chosen such that 0 nitrogen trichloride is completely cracked to a large extent. Medium operating temperature can range from Te to 300 ca, operating pressure values from 0.0 to 001 bar and residence time from 1 second to ? minutes. The OY gas stream leaving the superheater is recycled; which includes chlorine gas and nitrogen gas; to the zl series of the Y¢ chlorine production train of the chloralkali process. Optionally, the process can use a superheater and a catalytic bed to crack nitrogen trichloride. The catalytic bed can be within the superheating zone of the Yar evaporator unit than it can be in the form of a separate unit. Optionally, the gas leaving the cracking step of nitrogen trichloride can be directed; eg vo superheater or catalytic bed 4;

The - to the temperature conditioning step 07 before being recycled to the chlorine production train (Te stream) as shown in Figures 1 and 7. This reduces the temperature of the gas stream leaving the cracking step nitrogen trichloride ls can be a temperature of about 80 to 1071 C to a lower temperature for its introduction into the chlorine production train© » which can be a temperature of about minus Yo M. Although the invention has been described in light of the various embodiments, it is not intended to limit the invention to these embodiments. Many modifications will become apparent within the scope of the invention to the owner of skill in the art. The scope of the invention is limited by the following claims.

Claims (1)

M - elements of protection 1-1 A method for treating a stream containing liquid chlorine containing trichloride Nitrogen trichloride » The current is produced in the washing step of the chlorine production process; The method includes the following steps: ; () Receiving the stream that includes liquid chlorine containing nitrogen trichloride from the chlorine production train ysl of the zl process 1 chlorine ¢ chlorine (b) vaporize the liquid stream of step (1) to produce a stream comprising chlorine V ¢ nitrogen trichloride gas and gas A 4 (c) treat the stream obtained by step (b) by cracking the nitrogen trichloride gas contained therein; producing a stream containing 11 chlorine gas and nitrogen gas; and 1(d) recycle the stream obtained by step (c) to the chlorine production train 001 . Chlorine production The chain of chlorine production (Cum) for the protection element lag method 7-1 chlorine and cleaning the chlorine gas stream includes the steps of producing a chlorine gas stream train Y .gas ¥ chlorine production ISH, where the oY production chain includes a method according to the element of protection (=v) chlorine gas also includes the steps of compressing and liquefying the chlorine gas stream train " 1;- the lg method of the protectant? or oF where the recycling sale process of step “(d) involves recycling the stream obtained in step (c) to the chlorine gas stream” fed to the scrubber of the chlorine production chain production train. 1 0—method according to any of claims Y through 4; Whereas, the liquid stream that was received in step Y (0) is received from the holding tank of the stream descending from the washing step. 1 +- method according to any of the protections 1-0; where the liquid stream that Receivable in ¥ step 0 is Lie with nitrogen trichloride 1 7- A method according to any of the preceding claims, where the chlorine production process includes a chlorine production process. 1 +- method according to any of the foregoing claims, wherein step (c) comprises heating the stream of step (b) to a temperature of 0 to 00 m at a pressure of $10 to 100 bar for a residence time of 0.5 seconds to © 1 minutes. Method according to any of the previous claims, where step (c) is performed in unit 1 superheater.-11 1 method according to any of the claims 1 to oF where step (c) includes ) on introducing ¥ the current of step (b) into a catalytic bed containing a catalyst for destroying catalyst Y nitrogen trichloride. 11-1 method according to claim 110, whereby the catalytic bed operates at a temperature Y of 40 to 00 m and a pressure of 100 (Neo bar) for a residence time ranging from .,1 ¥ Seconds to © Minutes. - 10. - VY) a method under any of claims 1 through 101 where it also includes; after step (c); to adapt the temperature of the stream of step (c). Greater than 0 © ppm —Vo 1 method according to any of the claims 1 to OF where the current for step (a) X has a concentration of nitrogen trichloride greater than You ppm. ,. trichloride ?-117 1 A stream treatment apparatus comprising liquid chlorine containing Y nitrogen trichloride ; The current is produced in a chlorine production train ¥ scrubber; Where the device includes: ¢ chlorine vaporizer sl jadi unit (0 ¢ © (b) inlet to receive a stream containing liquid chlorine containing nitrogen trichloride 1 in the evaporation unit of the production chain chlorine dleal production train 1 chlorine production; A (c) boiling zone in the vaporizer unit after the inlet; 4 (d) means for cracking for destroying Massawa “nitrogen trichloride gas nitrogen trichloride 0 occurrence after the boiling zone; and 11 (e) means for recycling a stream comprising VY chlorine gas and nitrogen gas The means of cracking nitrogen trichloride 01 into the chlorine production train. chlorine production, where the chlorine production chain includes VY for the protective element, and the YA device. chlorine gas js) and a washing unit to wash a chlorine gas stream on a train V chlorine gas stream a device according to the protection element VA or ml where the chlorine production chain includes 19 \ chlorine gas also a pressure unit for compressing Chlorine gas stream production Anqet ¥ -71 1 Apparatus of claim 18 or 40; wherein the means of recycling (sale) includes the means of 'recycling the stream comprising chlorine gas and nitrogen gas TF _ from the means The cracking of nitrogen trichloride into the chlorine gas stream ¢ chlorine drop fed to the washing device of the chlorine production train sill. -71 1 device in accordance with any of Clauses 18 to Vo in which a stream receiving inlet ¥ comprising liquid chlorine containing nitrogen trichloride YF is effectively connected to the scrubber. YY) A device of any of Claims 18 to +oY where the recycling medium comprises a Y conduit that effectively connects the cracking medium to the chlorine gas stream. —YY 1 device pursuant to any of claims 117 to YY where the cracking medium includes a “1” superheater unit. YE) A device according to protection YY in which the superheater includes a superheater zone in the evaporator unit. —Yo 1 Apparatus pursuant to any of claims 117 to YY in which the cracking medium comprises a catalytic bed ¥ . -YT 1 device, Ty for any of the claims 117 to YY, where the cracking medium includes each Y of a superheater superheater and a catalytic bed.