CS257451B1

CS257451B1 - Method of hydrogen sulphide and carbon dioxide removal from processing gas during acetylene production

Info

Publication number: CS257451B1
Application number: CS829694A
Authority: CS
Inventors: Pavol Skubla; Vojtech Klausmann; Jozef Bizmar; Imrich Nemeth; Ladislav Kardas; Walter Waradzin
Original assignee: Pavol Skubla; Vojtech Klausmann; Jozef Bizmar; Imrich Nemeth; Ladislav Kardas; Walter Waradzin
Priority date: 1982-12-27
Filing date: 1982-12-27
Publication date: 1988-05-16
Also published as: CS969482A1

Abstract

Na odstraňovanie sírovodíka a oxidu uhličitého z procesného plynu pri výrobě acetylénu sa využívá reakcia s vodným roztokom alkalického uhličitanu (K2CO3, Na2CO3) pri koncentrácii aktívnej zložky v roztoku 16 až 29 %, tlaku 1,4 až 1,7 MPa a teplote 31 až 50 °C. Regeneruje sa len část vypieracieho roztoku, pričom zvyšok sa vracia na hlavu vypieraoej kolony. Regenerácia prebieha v prvom stupni znížením tlaku na 0,1 až 0,7 MPa a po filtrácii roztoku, v druhom stupni stripovaním inertným plynom v kolóne pri tlaku 0,1 až 0,15 MPa a teplote 31 až 59 °C. Uvedeným postupom sa odstráni z procesného plynu 96 % sirovodíka a 90 i oxidu uhličitého.For removal of hydrogen sulfide and carbon dioxide from process gas in the production of acetylene the reaction with an aqueous alkaline solution is used carbonate (K 2 CO 3, Na 2 CO 3) at concentration active ingredient in solution 16 to 29%, pressure 1.4 to 1.7 MPa and a temperature of 31 to 50 ° C. regenerates only a portion of the scrubbing solution the remainder being returned to the head to wash column. Regeneration takes place in the first stage by reducing the pressure to 0.1 to 0.7 MPa and after filtration in the second stage by stripping with inert gas in the column at a pressure of 0.1 to 0.15 MPa a temperature of 31 to 59 ° C. This procedure removes it from process gas 96% hydrogen sulfide and 90 i of carbon dioxide.

Description

Vynález sa týká spůsobu odstránenia sírovodíka a oxidu uhličitého z procesného plynu pri výrobě acetylénu.The present invention relates to a process for removing hydrogen sulfide and carbon dioxide from a process gas in the production of acetylene.

Pri parciálněj oxidácii zemného plynu vzniká asi 6,8 % obj. acetylénu a zbytok tvoří vodík, oxid uholnatý, oxid uhličitý, metán, etán, etylén, Cj a C^-olefíny a acetylény a malé množstvo aromátov. Separácia acetylénu z takejto zmesi je založená na principe odstráftovania jednotlivých zložiek v selektívnych rozpúšťadlách a roztokoch. Acetylén sa nakoniec získává absorpciou do metanolu a desorpciou z tohto roztoku, zatial čo koncový plyn (vodík, oxid uholnatý) z absorpcie sa může využit na výrobu čpavku alebo metanolu. Takýto postup vychádza z předpokladu, že zemný plyn neobsahuje sírne zlúčeniny.The partial oxidation of natural gas produces about 6.8 vol. acetylene and the remainder being hydrogen, carbon monoxide, carbon dioxide, methane, ethane, ethylene, C 1 and C 1 -olefins and acetylenes and a small amount of aromatics. The separation of acetylene from such a mixture is based on the principle of de-filtration of the individual components in selective solvents and solutions. Acetylene is finally obtained by absorption into and desorption from methanol, while the tail gas (hydrogen, carbon monoxide) from the absorption can be used to produce ammonia or methanol. Such a procedure is based on the assumption that the natural gas does not contain sulfur compounds.

Ak zemný plyn obsahuje sírne zlúčeniny, potom je potřebné tieto ešte před samotnou parciálnou oxidáciou' z něho odstránit. Najvhodnejší je postup, založený na principe katalytickej hydrogenácil na katalyzátoroch Comox alebo Nimox a zachytávaní sírovodíka na ZnO.If the natural gas contains sulfur compounds, then these must be removed from the gas prior to the partial oxidation. Most preferred is a process based on the principle of catalytic hydrogenation on Comox or Nimox catalysts and hydrogen sulfide capture on ZnO.

Nepriaznivé situácia nastane vtedy, ked důjde k zmene v zložení zemného plynu a ked technológia výroby acetylénu vyvinutá na báze zemného plynu bez sírnych zlúčenln, musí spracovávat zemný plyn s obsahom 5 až 50 mg síry na m . Kedže převážná vSčšina sírnych zlúčenín, nachádzajúcich sa v zemnom plyne, sa rozkládá pri teplotách 250 až 750 °C, vzniká z nich v redukčnom prostředí plameňa (1 400 °C) pri parciálnej oxidácii zemného plynu, hlavně sirovodík a menšie množstvo karbonylsulfidu, ktoré sa pri kvenčovaní s vodou dalej rozkládá za vzniku sírovodíka. Tak sa sirovodík dostane do procesného plynu, z ktorého, pokial sa neodstrá ňuje, prechádza jeho vSčšia část do acetylénu a menšia část do koncového plynu.An unfavorable situation occurs when there is a change in the composition of natural gas and when the acetylene production technology developed on the basis of sulfur-free natural gas has to process natural gas containing 5 to 50 mg of sulfur per m. Since the vast majority of sulfur compounds present in natural gas are decomposed at temperatures of 250 to 750 ° C, they form in a flame-reducing environment (1400 ° C) with the partial oxidation of natural gas, mainly hydrogen sulfide and less carbonyl sulfide, which when fermented with water further decomposes to form hydrogen sulfide. Thus, the hydrogen sulphide enters the process gas, from which, unless removed, most of it passes to acetylene and a minor part to the tail gas.

Obsah sírovodíka v týchto plynoch nepriaznivo ovplyvňuje proces ich dalšieho spracovania: u acetylénu, například na acetaldehyd, vinylacetát a pod., u koncového plynu na čpavok alebo metanol. Prejavuje sa to zníženou životnosťou používaných katalyzátorov, menšími výtažkami, zvýšenými normami spotřeby a teda zhoršenou ekonomikou celej výroby.The hydrogen sulphide content of these gases adversely affects their further treatment process: for acetylene, for example to acetaldehyde, vinyl acetate and the like, for the tail gas to ammonia or methanol. This is reflected in the reduced life span of the catalysts used, lower yields, increased consumption standards and thus a worsened economy of the whole production.

Účinné sa sirovodík a oxid uhličitý dajú vypierať z plynov vodnými roztokmi uhličitanu draselného alebo sodného. Pri tom prebiehajú reakcie:Effectively, hydrogen sulfide and carbon dioxide can be scrubbed from the gases with aqueous potassium or sodium carbonate solutions. There are reactions:

h₂s + K₂co₃s==aKHS + khco₃CO₂ + H₂O + K₂CO_3Í=á2 KHCO₃ h ₂ s ₂ + K ₃ as the Akhs == _KHCO3 + _CO2 + _H2 O + K ₂ CO _{3 R} = a 2 _KHCO3

Pri regenerácii prebiehajú uvedené reakcie v opačnom smere a navýše hydrosulfid draselný sa ešte rozkládá podlá rovnice:During the regeneration, the above reactions proceed in the opposite direction and, in addition, potassium hydrosulfide still decomposes according to the equation:

KHS-*^K2^{S + H}2^S KHS - * ^K 2 ^{S + H} 2 ^S

Z technologických postupov je známy sodový spůsob, pri ktorom sa používá 1 až 3% roztok uhličitanu sodného. Teplota vo vypieracej a regeneračnej časti bývá rovnaká 25 až 30 °C a regeneruje sa stripovaním použitého roztoku vzduchom. Regeneruje sa celé množstvo použitého roztoku. Nevýhodou je přítomnost kyslíka, čím sa spotřebuje mnoho uhličitanu sodného na vedlaj šie reakcie.A soda process is known from technological processes in which a 1 to 3% sodium carbonate solution is used. The temperature in the scrubbing and regenerating compartments is equal to 25-30 ° C and is regenerated by stripping the used solution with air. The whole amount of the solution used is regenerated. The disadvantage is the presence of oxygen, which consumes a lot of sodium carbonate for side reactions.

Iný postup regenerácie použitého roztoku sa snaží obísť túto nevýhodu tým, že namiesto stripovania vzduchom sa využívá znížený tlak (80 kPa) a zvýšená teplota (60 °C).Another process for recovering the solution used attempts to circumvent this disadvantage by using reduced pressure (80 kPa) and elevated temperature (60 ° C) instead of air stripping.

U potašového spůsobu sa sirovodík a oxid uhličitý vypierajú 15% roztokom uhličitanu draselného pri tlaku 0,5 až 1,2 MPa. Celé množstvo roztoku sa regeneruje pri tlaku 80 kPa varom a to bez stripovania inertným plynom.In the potash process, hydrogen sulfide and carbon dioxide are washed with a 15% potassium carbonate solution at a pressure of 0.5 to 1.2 MPa. The entire amount of the solution is recovered by boiling at 80 kPa without stripping with inert gas.

Horúci potašový spůsob používá 30% roztok uhličitanu draselného pri teplote vypierania 80 až 110 °C a pri tlakoch 2,5 až 3,0 MPa. V regenerácii bývá teplota 105 až 110 °C a tlak atmosférický. Nestripuje sa žiadným plynom. Pri vypieraní sírovodíka a oxidu uhličitého vodným roztokom alkalického uhličitanu z procesného plynu pri výrobě acetylénu, nie je možné využit ani jeden z týchto procesov, pretože to neumožňujú technologické podmienky výroby acetylénu.The hot potash process uses a 30% potassium carbonate solution at a scrubbing temperature of 80-110 ° C and at pressures of 2.5 to 3.0 MPa. In regeneration the temperature is 105 to 110 ° C and the pressure is atmospheric. No gas is required. When scrubbing hydrogen sulphide and carbon dioxide with an aqueous solution of alkali carbonate from the process gas in the production of acetylene, neither of these processes can be used, as this is not possible due to the technological conditions of acetylene production.

Na druhej straně, dostupný tlak plynu okolo 1,5- až 1,6 MPa umožňuje pri teplote okolo 40 °C účinné vypieranie zmienených kyslých zložiek i ked kvóli nízkéj koneentrácii sírovodíkav plyne (řádové)desiatky ppm) je potřebné použit vyššie koncentrácie alkalického uhličitanu. Vzhladom k vysokým koncentráciám aktívnej zložky v roztoku je postačujúce, ked sa regeneruje iba jeho část. Špecifickost procesu si vyžaduje zaradenie filtrácie roztoku medzi regeneračně operácie. Je to dané tým, ze procesný plyn z výroby acetylénu obsahuje přibližné 10% až C₄ acetylénov a olefínov, ktoré vytvárajú rózne polymérne a živičnaté látky a tie je potřebné odstraňovat.On the other hand, the available gas pressure of about 1.5 to 1.6 MPa allows efficient scrubbing of said acidic components at a temperature of about 40 ° C, although higher concentrations of alkali carbonate are required in addition to the low hydrogen sulfide gas concentration (tens of ppm). Due to the high concentrations of the active ingredient in the solution, it is sufficient that only a part of it is regenerated. The specificity of the process requires the solution filtration to be included in the regeneration operations. This is because the process gas from the acetylene production contains approximately 10% to C ₄ acetylenes and olefins, which form different polymeric and bituminous substances and need to be removed.

Týmto požiadavkám vyhovuje spósob odstránenia sírovodíka a oxidu uhličitého z procesného plynu pri výrobě acetylénu, podlá ktorého sa procesný plyn vypiera v kolóne s vodným roztokom uhličitanu alkalického kovu (uhličitan draselný, uhličitan sodný) a koneentrácii vypieracieho roztoku 16 až 29 % hm. K vypieraniu dochádza pri teplote 31 až 50 °C a tlaku 1,4 až 1,7 MPa. Na regeneráciu sa odvádza iba část použitého roztoku zo spodu vypieracej kolony, zatial čo zvyšné množstvo sa vracia na hlavu vypieracej kolony. Regenerácia použitého roztoku prebieha v prvom stupni znížením tlaku nad roztokom na hodnotu 0,1 až 0,7 MPa a v druhom stupni, po predchádzajúcej filtrácii roztoku, sa tento stripuje v kolóne pri tlaku 0,1 až 0,15 MPa a pri teplote 31 až 59 °C prúdom inertného plynu, pričom zregenerovaný roztok sa odtahuje zo spodnej časti kolony a vracia sa na hlavu vypieracej kolony.These requirements are met by a process for the removal of hydrogen sulfide and carbon dioxide from the process gas in the production of acetylene by which the process gas is scrubbed in an aqueous alkali metal carbonate solution (potassium carbonate, sodium carbonate) and a scrubbing solution of 16 to 29 wt. The scrubbing takes place at a temperature of 31 to 50 ° C and a pressure of 1.4 to 1.7 MPa. Only a portion of the solution used is recovered from the bottom of the scrubbing column for recovery, while the remainder is returned to the scrubbing column head. The regeneration of the solution used is carried out in the first stage by reducing the pressure above the solution to 0.1 to 0.7 MPa and in the second stage, after the previous filtration of the solution, it is stripped in the column at a pressure of 0.1 to 0.15 MPa and 59 ° C with an inert gas stream, the recovered solution being withdrawn from the bottom of the column and returned to the scrubbing column head.

K výhodám navrhovaného postupu patří dobrá selektivita a vysoká účinnost zachytávania sírovodíka a nízké náklady celého procesu.The advantages of the proposed process include good selectivity and high efficiency of hydrogen sulfide scavenging and low process costs.

Příklad 1Example 1

000 m\h (0 °C, 0,1 MPa) procesného plynu _1 pri výrobě acetylénu, ktorý obsahuje 0,15 % obj. oxidu uhličitého a 50 ppm sírovodíka o tlaku 1,5 MPa a teplote 35 °C vstupuje do spodnej Časti vypieracej klobúčikovej kolony 2 o priemere 1 600 mm so 16 etážami (obrázok 1). Na vrch kolony sa privádza oběhovým Čerpadlom 10 m^.h’*^' -Ί9 až 20 % hm. roztoku uhličitanu000 m / h (0 ° C, 0.1 MPa) of process gas 1 in the production of acetylene containing 0.15 vol. of carbon dioxide and 50 ppm of hydrogen sulphide at a pressure of 1.5 MPa and a temperature of 35 ° C enters the lower part of a 1600 mm diameter 16 cm scrubbing column 2 (Figure 1). The top of the column is fed by a circulating pump of 10 to 20 wt%. carbonate solution

3—1 draselného. Zo spodnej časti kolony odchádzajú na regeneráciu 4 m .*h asi 18% roztoku uhličitanu draselného.3 - 1 potassium. Approximately 18% potassium carbonate solution is passed from the bottom of the column to recover 4 m / h.

Po expanzi v odplyňovacej nádobě 2 sa čiastočne zregenerovaný roztok privádza cez filter _4 čerpadlom na.hlavu stripovacej klobúčikovej kolony 5, ktorá má priemer 900 mm a 26 etáží.After expansion in the degassing vessel 2, the partially recovered solution is fed through the filter 4 through the pump to the top of the stripper cap column 5, which has a diameter of 900 mm and 26 trays.

V odplyňovacej nádobě na hlavě kolony sa udržuje atmosférický tlak a teplota 35 °C, na dne kolony je teplota 40 °C. Do spodnej časti kolony sa privádza dusík 6 v maximálnom množstve 2 000 m\h 1 a z hlavy kolony odchádza uvolněný sirovodík a oxid uhličitý. Regenerovaný roztok sa vrac-ia na hlavu vypieracej kolony. Procesný plyn, odchádzajúci na dalšie spracovanie obsahuje 150 ppm oxidu uhličitého a 2 ppm sírovodíka.In the degassing vessel at the top of the column atmospheric pressure and temperature of 35 ° C are maintained, at the bottom of the column the temperature is 40 ° C. Nitrogen 6 is fed to the bottom of the column at a maximum of 2,000 m < 3 > h < 1 > The recovered solution is returned to the scrubbing column head. The process gas leaving for further processing contains 150 ppm of carbon dioxide and 2 ppm of hydrogen sulfide.

Claims

No. 3,257,451 did not utilize any of these processes, since this does not allow the technological conditions of the ethylene production. On the other hand, the available gas pressure of about 1.5 to 1.6 MPa allows for efficient washing of the above-mentioned acidic components even at a temperature of about 40 ° C, although a higher concentration of alkali carbonate is required to use a low hydrogen sulfide-in-gas (order of magnitude) ppm. In view of the high concentration of the active ingredient in the solution, it is sufficient to regenerate a portion thereof. The specificity of the process requires the inclusion of solution filtration between regeneration operations. This is because the process gas from the acetylene production contains about 10% to about 4 acetylenes and olefins, which form various polymeric and bituminous materials and these need to be eliminated. These requirements are met by the removal of hydrogen sulfide and carbon dioxide from the process gas in the production of acetylene, according to which the process gas is washed in a column of an aqueous alkali carbonate solution (potassium carbonate, sodium carbonate) and a washing solution concentration of 16 to 29 % wt. Washing occurs at a temperature of 31 to 50 ° C and a pressure of 1.4 to 1.7 MPa. Only a portion of the solution used is removed from the bottom of the scrubbing column for recovery, while the remaining amount is returned to the scrubber head. The regeneration of the used solution occurs in the first stage by lowering the pressure over the solution to a value of 0.1 to 0.7 MPa, and in the second stage, after previous filtration of the solution, it is stripped in the column at a pressure of 0.1 to 0.15 MPa and at a temperature of 31 to 59 ° C through a stream of inert gas, the recovered solution being drawn off from the bottom of the column and returned to the head of the scrubbing column. Advantages of the proposed process include good selectivity and high hydrogen sulphide capture efficiency and low process costs. Example 1 25,000 m (0 ° C, 0.1 MPa) of process gas 1 for the production of acetylene containing 0.15% by volume carbon dioxide and 50 ppm hydrogen sulfide at 1.5 MPa and 35 ° C at the bottom Part of a washing cap column 2 with a diameter of 1600 mm with 16 plates (Figure 1). Up to 10 to 20% by weight of the circulating pump is fed to the top of the column. potassium carbonate solution. About 4% potassium carbonate solution is withdrawn from the bottom of the column for regeneration of 4 m. After expansion in the degassing vessel 2, the partially recovered solution is fed through the filter 4 through a pump head of a stripping cap column 5 having a diameter of 900 mm and 26 trays. The degassing vessel at the top of the column maintains atmospheric pressure and a temperature of 35 ° C, to dnecolones the temperature is 40 ° C. Nitrogen 6 is fed to the bottom of the column at a maximum of 2000 m 1 and released hydrogen sulfide and carbon dioxide are removed from the top of the column. The recovered solution is returned to the head of the scrubbing column. The process gas leaving for further processing contains 150 ppm carbon dioxide and 2 ppm hydrogen sulfide. BEFORE THE INVENTION A method of removing hydrogen sulfide and carbon dioxide from a process gas in the production of acetylene is to process the process gas in a column of an aqueous solution of potassium carbonate or sodium carbonate characterized in that the conditioning of the scrubbing solution is 16 to 29%, scrubbing takes place at a temperature of 31 to 50 ° C and a pressure of 1.4 to 1.7 MPa, whereby only a portion of the solution used from the bottom of the scrubbing column is removed for recovery, while the abundant amount is returned to the scrubbing column head and the recovery of the used solution takes place first. step by reducing the pressure above the solution to a value of 0.1 to 0.7 MPa and then in a second stage, after prior filtration, the solution is stripped in a column at a pressure of 0.1 to 0.15 MPaa at a temperature of 31 to 59 ° C with a stream of inert gas, the recovered solution is drawn off the bottom of the column and returned to the head of the scrubbing column. 1 drawing