System for producing sodium pyrosulfite by using coke oven flue gas and coke oven gas

Abstract

The embodiment of the utility model provides a system for producing sodium pyrosulfite by using coke oven flue gas and coke oven gas, which comprises an absorption tower, a first desorption device, a washing tower, a second desorption device, an oxidation burner and a sulfur dioxide absorption device, the desorption device is used for desorbing saturated activated carbon to form first sulfur dioxide gas; the washing tower is used for absorbing hydrogen sulfide in coke oven flue gas by using turbid liquid prepared from iron oxide powder to form an intermediate liquid; the second desorption device is connected with the washing tower and is used for desorbing the intermediate liquid to form a sulfur-containing substance; the oxidation combustor is used for incinerating the dried sulfur-containing substances to form second sulfur dioxide gas; the sulfur dioxide absorption device is used for producing sodium pyrosulfite. On one hand, sulfur dioxide in the coke oven flue gas can be removed, pollution to the environment is reduced, on the other hand, the coke oven flue gas and coke oven gas can be used for producing sodium pyrosulfite, higher value and wider application are achieved, and the utilization rate of vulcanization resources can be increased.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of coking, particularly to a system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas. BACKGROUND

[0002] Combustible gas such as coal gas generally contains a certain amount of sulfides, in order to prevent the sulfides in the above combustible gas from producing sulfur dioxide after combustion and causing pollution to the atmosphere and the surrounding environment, the combustible gas is usually desulfurized by using oxidation method, absorption method, etc., and the sulfur is stored in sulfur foam. Then, sulfur paste is produced by using the molten sulfur kettle method. The process of producing sulfur paste includes sending the sulfur foam to the molten sulfur kettle, indirectly heating it by using steam, separating the molten sulfur from the clear liquid, when the pressure at the top of the molten sulfur kettle is relatively high, discharging the clear liquid from the top to the clear liquid tank, returning the clear liquid to the desulfurization system after cooling, repeating the feeding 2-3 times, further heating and melting the molten sulfur when there is basically no clear liquid in the molten sulfur kettle, so that the molten sulfur at the bottom enters the collecting device, and transporting the molten sulfur to the outside after it naturally falls to room temperature. However, the process has the problems of waste gas pollution to the environment during the collection, cooling and discharge of the molten sulfur, and low value of the produced product sulfur paste.

[0003] In order to prevent the flue gas containing SO2 and NO X from causing pollution to the atmosphere and the surrounding environment, the active carbon method desulfurization and denitrification process is usually used to treat the coke oven flue gas. In the process of flue gas desulfurization and denitrification treatment, the flue gas is first cooled by recovering heat energy through the waste heat boiler and then introduced into the active coke adsorption purification device. Under the action of the catalyst, SO2, O2 and H2O in the flue gas are captured by the active carbon to generate sulfuric acid, and NO X in the flue gas is reduced by NH3 to generate N2 and H2O. The active coke adsorbing sulfuric acid is desorbed and regenerated in the regeneration tower, and the sulfuric acid and C in the regeneration tower react to generate SO2, H2O and CO2. Then, the SO2-containing acid gas is sent to the ammonium sulfate system to produce ammonium sulfate, and the regenerated active coke is recycled. However, in the existing active carbon method coke oven flue gas desulfurization and denitrification process, SO2 and NH3 can generate ammonium sulfite (NH4)2SO3 instead of ammonium sulfate (NH4)2SO4 without oxidation, which leads to low value of the produced product ammonium sulfate. INVENTION CONTENTS

[0004] The purpose of the embodiment of the utility model is to provide a system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas, and to improve the utilization rate of sulfuration resources. The specific technical scheme is as follows:

[0005] In order to achieve the above object, the utility model discloses an embodiment proposes a kind of system for producing sodium metabisulfite using coke oven flue gas, coke oven gas, it is characterized in that, including: absorption tower, for absorbing the sulfur dioxide in coke oven flue gas, form saturated activated carbon;First desorption device, and the absorption tower are connected, for from the saturated activated carbon desorption form first sulfur dioxide gas;Washing tower, for using iron oxide powder is prepared into suspension liquid absorption hydrogen sulfide in coke oven flue gas, form intermediate liquid;Second desorption device, and the washing tower are connected, for from the intermediate liquid desorption form sulfur-containing substance;Oxidation burner, for to the sulfur-containing substance after drying incineration, form second sulfur dioxide gas;Sulfur dioxide absorption device, for obtaining the first sulfur dioxide gas and the second sulfur dioxide gas as part raw material, production sodium metabisulfite.

[0006] According to an embodiment of the utility model application, still include: first fan, set up between the first desorption device and the sulfur dioxide absorption device, for the first sulfur dioxide gas is blown to the sulfur dioxide absorption device.

[0007] According to an embodiment of the utility model application, still include: centrifugal drying device, set up between the second desorption device and the oxidation burner, for the sulfur-containing substance solid-liquid separation of the second desorption device desorption, and the solid-state separation material is dried, form the sulfur-containing substance after drying.

[0008] According to an embodiment of the utility model application, the second desorption device includes cyclone type regeneration tank and second fan;The inlet of the cyclone type regeneration tank is connected with the outlet of the washing tower, and the outlet of the cyclone type regeneration tank is connected with the centrifugal drying device;The second fan is used for blowing air into the intermediate liquid in the cyclone type regeneration tank, so that the sulfur-containing substance is desorbed in the intermediate liquid.

[0009] According to an embodiment of the utility model application, the first fan includes a blower;And / or, the second fan includes a Roots blower.

[0010] According to an embodiment of the utility model application, still include: dust washing purification device, set up between the oxidation burner and the sulfur dioxide absorption device, for the second sulfur dioxide gas is removed after dust and impurity, is sent into the sulfur dioxide absorption device.

[0011] According to an embodiment of the utility model application, the oxidation burner includes a fluidized bed furnace.

[0012] According to an embodiment of the utility model application, still include: sodium metabisulfite concentration device, and the sulfur dioxide absorption device are connected, for the sodium metabisulfite centrifugal drying of production in the sulfur dioxide absorption device.

[0013] According to one embodiment of the present application, the tail gas washing device is connected with the sulfur dioxide absorption device, and is used for absorbing sulfur dioxide from the tail gas discharged by the sulfur dioxide absorption device.

[0014] According to one embodiment of the present application, the sulfur dioxide absorption device comprises a reaction kettle, an alkali preparation tank and an alkali preparation pump.

[0015] The alkali preparation tank is used for containing a soda solution.

[0016] The reaction kettle is in communication with the first desorption device and the oxidation burner respectively, so as to obtain the first sulfur dioxide gas and the second sulfur dioxide gas.

[0017] The alkali preparation pump is used for conveying the soda solution in the alkali preparation tank to the reaction kettle, and the soda solution reacts with the first sulfur dioxide gas and the second sulfur dioxide gas to produce sodium metabisulfite.

[0018] The system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas provided by the embodiment of the present application comprises an absorption tower, a first desorption device, a washing tower, a second desorption device, an oxidation burner and a sulfur dioxide absorption device. The absorption tower is used for absorbing sulfur dioxide in coke oven flue gas to form saturated activated carbon. The first desorption device is connected with the absorption tower, and is used for desorbing the saturated activated carbon to form the first sulfur dioxide gas. The washing tower is used for absorbing hydrogen sulfide in coke oven flue gas by using iron oxide powder to form an intermediate liquid. The second desorption device is connected with the washing tower, and is used for desorbing the intermediate liquid to form sulfur-containing matter. The oxidation burner is used for burning the sulfur-containing matter after drying to form the second sulfur dioxide gas. The sulfur dioxide absorption device is used for obtaining the first sulfur dioxide gas and the second sulfur dioxide gas as part of raw materials to produce sodium metabisulfite. In the embodiment, on the one hand, sulfur dioxide in coke oven flue gas can be removed, and pollution to the environment is reduced. On the other hand, sodium metabisulfite can be produced by using coke oven flue gas and coke oven gas. Sodium metabisulfite has a wide range of industrial applications, such as medicine, rubber and people's livelihood fields. Compared with sulfur paste in the prior art, sodium metabisulfite has higher industrial value and wider industrial applications, so that the utilization rate of sulfur resources can be improved.

[0019] Of course, it is not necessary for any product implementing the present application to achieve all the advantages mentioned above at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0021] Figure 1 A structure schematic diagram of a system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas is provided for the embodiments of the present application.

[0022] Figure 2 A specific structure schematic diagram of a system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas is provided for the embodiments of the present application.

[0023] The absorption tower 11, the first desorption device 12, the first fan 13, the washing tower 21, the cyclone type regeneration tank 221, the second fan 222, the second desorption device 22, the oxidation burner 23, the fluidized bed furnace 231, the centrifugal drying device 24, the dust washing and purifying device 25, the sulfur dioxide absorption device 31, the reaction kettle 311, the alkali preparation tank 312, the alkali preparation pump 313, the sodium metabisulfite concentration device 32, the tail gas washing device 40, and the chimney 50. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0025] The main purpose of the present application is to provide a system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas, and to improve the utilization rate of sulfidation resources.

[0026] Therefore, the present application provides a system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas. The system uses the acid gas generated by coke oven flue gas desulfurization and denitrification and the sulfur foam or sulfur-containing impurities generated by coke oven gas desulfurization device to produce sodium metabisulfite. The system can use the sulfur foam or sulfur-containing impurities generated by desulfurization of combustible gas such as coal gas to produce sodium metabisulfite. Compared with the prior art, the system reduces pollution to the environment and makes the produced product have a wider range of uses.

[0027] Figure 1 A structure schematic diagram of a system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas is provided for the embodiments of the present application, as shown in Figure 1As shown, a system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas, comprising an absorption tower 11, a first desorption device 12, a washing tower 21, a second desorption device 22, an oxidation burner 23 and a sulfur dioxide absorption device 31.

[0028] The absorption tower 11 is used for absorbing sulfur dioxide in the coke oven flue gas to form saturated activated carbon; the first desorption device 12 is connected with the absorption tower 11 and used for desorbing the first sulfur dioxide gas from the saturated activated carbon; the washing tower 21 is used for absorbing hydrogen sulfide in the coke oven flue gas by using the suspension liquid of iron oxide powder to form an intermediate liquid; the second desorption device 22 is connected with the washing tower 21 and used for desorbing the sulfur-containing substance from the intermediate liquid; the oxidation burner 23 is used for burning the dried sulfur-containing substance to form the second sulfur dioxide gas; and the sulfur dioxide absorption device 31 is used for obtaining the first sulfur dioxide gas and the second sulfur dioxide gas as part of raw materials to produce sodium metabisulfite.

[0029] In the application, the absorption tower 11 is filled with activated carbon material, and when the coke oven flue gas enters the absorption tower 11 and passes through the activated carbon, the sulfur dioxide is adsorbed by the activated carbon and gradually reaches a saturated state. The saturated activated carbon is sent to the first desorption device 12, and the saturated activated carbon can be heated by nitrogen gas at a temperature of about 670K to desorb the first sulfur dioxide gas with high concentration.

[0030] The washing tower 21 is provided with a suspension liquid of iron oxide powder (Fe2O3+3H2O=2Fe(OH)3), and when the coke oven gas enters the washing tower 21 and passes through the suspension liquid, the suspension liquid absorbs the hydrogen sulfide (H2S) in the coke oven gas to form an intermediate liquid (2Fe(OH)3+3H2S=Fe2S3+6H2O, Fe2S3=2FeS+S). The second desorption device 22 can use the desulfurization liquid to desulfurize the intermediate liquid to desorb the sulfur-containing substance, and the dried sulfur-containing substance is burned by the oxidation burner 23 to form the second sulfur dioxide gas. The sulfur dioxide absorption device 31 obtains the first sulfur dioxide gas and the second sulfur dioxide gas as part of raw materials to produce sodium metabisulfite. On the one hand, the sulfur dioxide in the coke oven flue gas can be removed to reduce environmental pollution, and on the other hand, the coke oven flue gas and the coke oven gas can be used to produce sodium metabisulfite, which has a wide range of industrial applications, such as medicine, rubber and people's livelihood, and has higher industrial value and wider industrial applications than sulfur paste in the prior art, thereby improving the utilization rate of sulfuration resources.

[0031] Figure 2 A specific structure diagram of a system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas provided by the embodiment of the present application is shown in Figure 2As shown, in some embodiments, the system for producing sodium pyrosulfite by using coke oven flue gas and coke oven gas further comprises a first fan 13, which is arranged between the first desorption device 12 and the sulfur dioxide absorption device 31, and is used for blowing the first sulfur dioxide gas to the sulfur dioxide absorption device 31. In some embodiments, the first fan 13 comprises a blower.

[0032] In some embodiments, the first desorption device 12 comprises a desorption tower.

[0033] In some embodiments, the system for producing sodium pyrosulfite by using coke oven flue gas and coke oven gas further comprises a centrifugal drying device 24, which is arranged between the second desorption device 22 and the oxidation burner 23, and is used for separating the sulfur-containing substance from the liquid in the second desorption device 22, and drying the solid separation to form dried sulfur-containing substance.

[0034] In specific implementations, the second desorption device 22 is used to desorb the sulfur-containing substance from the intermediate liquid to form sulfur foam or sulfur-containing impurities. The centrifugal drying device 24 comprises a solid-liquid separation device and a dryer. The solid-liquid separation device separates the solid and liquid in the sulfur foam or sulfur-containing impurities, and the dryer is used to dry the solid separated by the solid-liquid separation device to remove the residual moisture, so as to obtain the dried sulfur-containing substance for incineration by the oxidation burner 23.

[0035] In some embodiments, the second desorption device 22 comprises a cyclone regenerator 221 and a second fan 222; the inlet of the cyclone regenerator 221 is connected with the outlet of the washing tower 21, and the outlet of the cyclone regenerator 221 is connected with the centrifugal drying device 24; and the second fan 222 is used to blow air into the intermediate liquid in the cyclone regenerator 221 to desorb the sulfur-containing substance from the intermediate liquid. In some embodiments, the second fan 222 comprises a Roots blower.

[0036] In applications, the intermediate liquid (Fe2S3 and FeS) is placed in the cyclone regenerator 221, and reacts with oxygen in the air shaft to generate sulfur-containing substance and regenerated desulfurization liquid (2Fe2S3+3O2+6H2O=4Fe(OH)3+6S, 4FeS+3O2+6H2O=4Fe(OH)3+4S). The regenerated desulfurization liquid flows from the cyclone regenerator 221 to the washing tower 21 for recycling.

[0037] In some embodiments, the system for producing sodium pyrosulfite by using coke oven flue gas and coke oven gas further comprises a dust removal and washing purification device 25, which is arranged between the oxidation burner 23 and the sulfur dioxide absorption device 31, and is used for removing dust and impurities from the second sulfur dioxide gas before being sent to the sulfur dioxide absorption device 31.

[0038] In specific implementations, the dust removal and washing purification device 25 includes a heat exchanger, a dust remover, a washer, a foam tower, and a mist eliminator connected in sequence. The heat exchanger is used to heat the second sulfur dioxide gas and reduce the temperature of the second sulfur dioxide gas, and a solid residue discharge port is arranged at the bottom of the heat exchanger. During the heating of the second sulfur dioxide gas by the heat exchanger, part of the dust and impurities in the second sulfur dioxide gas will fall to the bottom of the heat exchanger and be discharged to the outside of the heat exchanger through the solid residue discharge port at the bottom of the heat exchanger.

[0039] The dust remover is used to remove the dust and impurities in the second sulfur dioxide gas, and a solid residue discharge port is arranged at the bottom of the dust remover. When the second sulfur dioxide gas passes through the dust remover, part of the dust and impurities in the gas are removed and discharged through the solid residue discharge port at the bottom of the dust remover.

[0040] The washer is provided with a dilute sulfuric acid tank for further removing the dust and impurities in the second sulfur dioxide gas. After the second sulfur dioxide gas enters the washer, the second sulfur dioxide gas contacts with the dilute sulfuric acid in the dilute sulfuric acid tank, and the dust and impurities therein are absorbed by the dilute sulfuric acid, thereby reducing the content of the dust and impurities contained in the second sulfur dioxide gas.

[0041] The foam tower is used to further remove the dust and impurities in the second sulfur dioxide gas, and is connected with a dilute sulfuric acid pump. After the second sulfur dioxide gas enters the foam tower, it is further fully contacted with the dilute sulfuric acid, so that the content of the dust and impurities is further reduced to meet the requirements of the process. In actual application, a packed tower can be used to replace the foam tower. The mist eliminator is used to remove the acid mist contained in the second sulfur dioxide gas. After being washed by the dilute sulfuric acid, the second sulfur dioxide gas contains part of the acid mist (dilute sulfuric acid). When the second sulfur dioxide gas passes through the mist eliminator, the mist eliminator can remove the acid mist contained in the second sulfur dioxide gas.

[0042] In some embodiments, the oxidation burner 23 includes a bubbling furnace 231.

[0043] In some embodiments, the sulfur dioxide absorption device 31 comprises a reaction kettle 311, an alkali preparation tank 312 and an alkali preparation pump 313; the alkali preparation tank 312 is used for containing a soda solution; the reaction kettle 311 is communicated with the first desorption device 12 and the oxidizing burner 23 respectively, so as to obtain the first sulfur dioxide gas and the second sulfur dioxide gas; and the alkali preparation pump 313 is used for conveying the soda solution in the alkali preparation tank 312 to the reaction kettle 311, and the soda solution reacts with the first sulfur dioxide gas and the second sulfur dioxide gas to produce sodium metabisulfite. By using the alkali preparation pump 313, the soda solution in the alkali preparation tank 312 can be conveyed to the reaction kettle 311, wherein the reaction kettle 311 can be single-stage or multi-stage in series. The soda solution can be formed by mixing soda and water in a certain proportion.

[0044] In some embodiments, the system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas further comprises a sodium metabisulfite concentration device 32, which is connected with the sulfur dioxide absorption device 31 and used for centrifuging and drying the sodium metabisulfite produced by the sulfur dioxide absorption device 31.

[0045] In specific implementation, the sodium metabisulfite concentration device 32 comprises a centrifuge and a dryer, the inlet of the centrifuge is connected with the outlet of the reaction kettle 311, and the centrifuge is used for separating the sodium metabisulfite and the soda solution produced by the reaction kettle 311, and the sodium metabisulfite separated is conveyed to the dryer for drying, so as to obtain relatively pure sodium metabisulfite.

[0046] In some embodiments, the system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas further comprises a tail gas washing device 40, which is connected with the sulfur dioxide absorption device 31 and used for absorbing the sulfur dioxide in the tail gas discharged by the sulfur dioxide absorption device 31.

[0047] In specific implementation, the tail gas washing device 40 comprises a tail gas absorption tower and a tail gas circulation pump, the tail gas absorption tower is communicated with the outlet of the reaction kettle 311, and the tail gas circulation pump is used for spraying the absorption liquid to the tail gas absorption tower, so as to absorb a small amount of unreacted sulfur dioxide gas, so as to meet the gas emission standard.

[0048] In some embodiments, the system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas further comprises a chimney 50, which is arranged on the absorption tower 11, so that the absorption tower 11 can discharge waste externally.

[0049] The above merely describes the preferred embodiments of the present application, but is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A system for producing sodium metabisulfite using coke oven flue gas, coke oven gas, characterized by, Comprising: an absorption tower (11) for absorbing sulfur dioxide in coke oven flue gas to form saturated activated carbon; a first desorption device (12) connected with the absorption tower (11) for desorbing the saturated activated carbon to form a first sulfur dioxide gas; a washing tower (21) for absorbing hydrogen sulfide in coke oven gas with a suspension of iron oxide powder to form an intermediate liquid; a second desorption device (22) connected with the washing tower (21) for desorbing the intermediate liquid to form sulfur-containing substances; an oxidation burner (23) for incinerating the dried sulfur-containing substances to form a second sulfur dioxide gas; a sulfur dioxide absorption device (31) for taking the first sulfur dioxide gas and the second sulfur dioxide gas as part of raw materials to produce sodium metabisulfite.

2. A system for producing sodium metabisulfite using coke oven flue gas and coke oven gas according to claim 1, characterized in that, Further comprising: a first fan (13) arranged between the first desorption device (12) and the sulfur dioxide absorption device (31) for blowing the first sulfur dioxide gas to the sulfur dioxide absorption device (31).

3. The system for producing sodium metabisulfite using coke oven flue gas and coke oven gas according to claim 2, characterized in that, Further comprising: a centrifugal drying device (24) arranged between the second desorption device (22) and the oxidation burner (23) for separating the sulfur-containing substances desorbed by the second desorption device (22) into solid and liquid, and drying the solid separation to form dried sulfur-containing substances.

4. The system for producing sodium metabisulfite from coke oven flue gas and coke oven gas according to claim 3, wherein the second desorption device (22) comprises a cyclone regenerator (221) and a second fan (222); an inlet of the cyclone regenerator (221) is connected with an outlet of the washing tower (21), and an outlet of the cyclone regenerator (221) is connected with the centrifugal drying device (24); the second fan (222) is used for blowing air into the intermediate liquid in the cyclone regenerator (221) to desorb the sulfur-containing substances from the intermediate liquid.

5. The system for producing sodium metabisulfite from coke oven flue gas and coke oven gas according to claim 4, wherein the first fan (13) comprises a blower; and / or the second fan (222) comprises a Roots blower.

6. The system for producing sodium metabisulfite using coke oven flue gas and coke oven gas according to claim 1, characterized in that, Further comprising: a dust removal, washing and purification device (25) arranged between the oxidation burner (23) and the sulfur dioxide absorption device (31) for sending the second sulfur dioxide gas into the sulfur dioxide absorption device (31) after removing dust and impurities.

7. The system for producing sodium metabisulfite from coke oven flue gas and coke oven gas according to claim 1, wherein the oxidation burner (23) comprises a fluidized bed furnace.

8. The system for producing sodium metabisulfite using coke oven flue gas and coke oven gas according to claim 1, characterized in that, Further comprising: a sodium metabisulfite concentration device (32) connected with the sulfur dioxide absorption device (31) for centrifugally drying the sodium metabisulfite produced by the sulfur dioxide absorption device (31).

9. The system for producing sodium metabisulfite using coke oven flue gas and coke oven gas according to claim 1, characterized in that, Further comprising: a tail gas washing device (40) connected with the sulfur dioxide absorption device (31) for absorbing sulfur dioxide from the tail gas discharged by the sulfur dioxide absorption device (31).

10. The system for producing sodium metabisulfite by using coke oven flue gas and coke oven gas according to any one of claims 1 to 9, characterized in that, the sulfur dioxide absorption device (31) comprises a reaction kettle (311), an alkali preparation tank (312) and an alkali preparation pump (313); the alkali preparation tank (312) is used for containing a soda solution; the reaction kettle (311) is in communication with the first desorption device (12) and the oxidizing burner (23) respectively, so as to obtain the first sulfur dioxide gas and the second sulfur dioxide gas; the alkali preparation pump (313) is used for conveying the soda solution in the alkali preparation tank (312) to the reaction kettle (311) and reacting with the first sulfur dioxide gas and the second sulfur dioxide gas to produce sodium metabisulfite.

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