[Technology] Detailed description of coke oven gas desulfurization situation

Coke oven gas desulfurization enterprises have not been valued before, and many coking plants do not desulfurization device, with the introduction and strengthening of national environmental protection policies, coking plants have begun to add desulfurization systems, in particular, coke oven gas as a city gas or methanol production for civilian use or Dimethyl ether, the desulfurization accuracy is relatively high, H2S index requirements below 20mg / m3, look at the operation of the coking plant wet FGD system is difficult to reach this indicator, the author once in Shanxi, Shandong, Hebei and other coking Plant catalyst application and inspection, that caused the coke oven gas desulfurization compliance difficulties the main reasons are the following:

First, desulfurization tower to be connected in series

Desulfurization tower is the main equipment for desulfurization production, most of the coking plant desulfurization tower are packed tower, and the two towers can be parallel operation of the string can also be found in practice, the two towers in parallel operation process, coke oven air tower speed of 0.4 If m / s is above, exporting H2S is difficult to meet the standard. If the two towers are operated in series, the resistance of tower system will increase slightly, but the increase rate will not increase greatly. Therefore, the coking plant in the case of changes in equipment is best to use two towers in series operation process.

Second, desulfurization should be set before the gas pre-cooling tower

Coke oven gas desulfurization There are two main setting methods, one for the pre-desulfurization, that desulfurization in the blower after the debinder, ammonium sulfate set before, and the other for the desulfurization, desulfurization in the desulfurization, ammonium sulfate rear , There is a rare blower before the set of negative pressure desulfurization, desulfurization gas pre-cooling tower set mainly refers to the front desulfurization, coke oven gas temperature after the gas blower is generally increased to 35-40 ℃, the summer temperature High can be increased above 45 ℃, high temperature can lead to desulfurization solution in the NH3 content decreased, some coking plant desulfurization solution in the NH3 content of only 4-6g / L, the results desulfurization efficiency of less than 80%. The high gas temperature not only affects the NH3 content in the solution, but also increases the side reaction rate in the desulfurization process and increases the side reaction products (NH4) 2S2O3 and NH4CHS in the solution. In addition, Tar removal efficiency is reduced, resulting in gas tar content higher than 30mg / m3 above, affecting the efficiency of desulfurization and desulfurization liquid sulfur foam generation.

In order to meet the temperature requirements in the desulfurization process, it is necessary to set a gas pre-cooling tower before the desulfurization in order to reduce the gas temperature to 30 ° C. Most of the current coking plants are direct precooling towers, so NH3 content in the gas is relatively insufficient, resulting in serious loss of NH3, which is difficult to meet the demand of NH3 concentration in the desulfurization solution. Therefore, it is suggested that the cooling process of the gas precooling tower be Indirect cooling is better.

Third, desulfurization solution should be used Na2CO3 as alkali source

Coke oven gas NH3 content is generally 4-6g / m3, for gas H2S content of less than 5g / m3, with NH3 as an alkali source to meet the needs of the desulfurization reaction in the amount of ammonia, which includes steaming ammonia system to the desulfurization solution In the gas or NH3 added. The NH3 content in the desulfurization solution can generally be maintained at 10-12g / L. If the coke oven gas H2S content is greater than 5g / m3 or more, to NH3 as an alkali source can not meet the desulfurization reaction required NH3 amount. If you want to achieve a higher desulfurization efficiency, the gas should be at least NH3 / H2S 1.3, such as gas H2S content of 6g / m3 or more, the NH3 content should reach 7.8g / m3 or more, even if the coking plant by steam ammonia Device, it is difficult to balance the content of this long-term, so for gas H2S content greater than 5g / m3 above, the best use of Na2CO3 as the alkali source of desulfurization process, and some coking plants use NH3 as the source of alkali in order to achieve higher desulfurization efficiency , Add a certain amount of Na2CO3 or NaOH in the desulfurization solution can achieve good desulfurization effect.

Fourth, control of secondary salt content in the desulfurization solution

The secondary salts generated when desulfurization solution uses NH3 as alkaline source are (NH4) 2S2O3, (NH4) 2SO4 and NH4CNS. The secondary salts generated when Na2CO3 is the alkali source are Na2S2O3, Na2SO4 and NaCNS. The rate of formation of the secondary salt is related to the choice of desulfurization process and the catalyst, and more to the content of HCN in the coke oven gas. Generally, the HCN in the coke oven gas is 1.0-2.5 g / m3. The content of the secondary salt in the desulfurization solution has a relatively big influence on the desulfurization process. One is to increase the consumption of the alkali source and increase the desulfurization cost. Second, increase the viscosity of the desulfurization solution, reducing the sulfur capacity of desulfurization solution, so that desulfurization efficiency is reduced. Third, desulfurization solution secondary salt Na2SO4 additional 40g / L or more will be serious corrosion equipment. Fourth, desulfurization solution is easy to produce secondary desulfurization tower desulfurization tower clogging phenomenon. Fifth, reduce the sulfur recovery rate.

A typical case of secondary salt affecting sulfur recovery, the author once encountered in a coking plant in Shanxi. The annual output of 600,000 tons of coke plant, due to limited coal production, only coke oven gas volume 5000m3 / h, there are two major equipment, φ3800, H43000mm regeneration tower and two φ5000, H27000mm desulfurization tower, due to small gas, a Desulfurization tower coke furnace gas, antifreeze two regeneration tower and two desulfurization tower solution normal circulation. H2S content of coke oven gas inlet 2140-8855mg / m3, the average content of 5394mg / m3, the export of H2S content of 6.8-185.6mg / m3, the average content of 38.9mg / m3, (most of the time a number of close to the gas valve, or exports H2S content will be lower) desulfurization efficiency of 99.3%. Desulfurization system December 8, 2007 The original car to the factory February 29, 2008 a total of 83 days operation, but the desulfurization foam has never been, the plant worried about long-term operation will go wrong, I also feel incredible, after repeated Adjustment is not a sulfur foam, found that most of the sulfur in coke oven gas into secondary salt. The 83 days desulfurization system produced sulfur (5394-38.9) × 32/34 × 5000m3 / h × 24h × 83 days = 50198.4 kg, and the desalting liquid secondary salt analysis of Na2S2O3 content of 38.5g / L, Na2SO4 content of 11.9g / L , Na2CNS content is not analyzed, but according to the coking plant solution analysis data speculated that Na2CNS content of at least one times Na2S2O3 should be above 77g / L, the total desulfurization solution is about 1000m3, so as to calculate the secondary salt sulfur content of about 48697kg (including Na2S2O3 sulfur content 15595kg, Na2SO4 sulfur content 2682kg, NaCNS sulfur content 30420kg). Theoretical calculation 83 days should produce about 50198.4kg sulfur, analysis of the secondary salt in the sulfur content of about 48697kg, so that the desulfurization solution can not have much sulfur foam, desulfurization liquid analysis of suspended sulfur is only 0.3g / L, sulfur are converted to vice Salt

The long-term accumulation of the secondary salts in the desulfurization solution, reaching more than 250g / L, will seriously affect the desulfurization process. In the past, some individual plants had to add the salt extraction process in order to solve the problem of the secondary salts in the desulfurization solution. However, To solve the problem of secondary salts high desulfurization solution, it was observed 10000m3 / h coke oven gas drainage liquid 4-5m3 per day to maintain the secondary salt desulfurization solution no longer grow.

Fifth, to maintain a larger solution circulation

According to the requirements of tower spray density and liquid-gas ratio, the density of spray-desulfurization tower solution is 40-50 m3 / m2 and the liquid-gas ratio is 20-30 L / m2. Of course, the device conditions allow the solution circulation should be larger as well, soluble

Excavator cylinder oil seals

â‘ Hardness:

Due to the scientific synthesis of high-molecular polyurethane elastomer materials using iron rubber, the higher the hardness, the higher the modulus, the smaller the elongation, and the better the wear resistance and heat resistance. Well, in the range of minus 35 degrees Celsius to 100 degrees Celsius, and at a pressure of 60 to 70 MPa, the maximum sealing performance can be guaranteed.

â‘¡Pressure resistance:

The use of viscoelastic seals made of nitrile rubber is the most complete protection against damage caused by back pressure. In the range of minus 55 degrees Celsius to 100 degrees Celsius, and under a pressure of 21MPa, due to the rubber The seal is often in a compressed state, so the compression performance of the rubber seal must be considered. It not only achieves enhanced anti-climbing performance and low friction resistance, but also has good performance in dealing with special low-temperature oil, and can also be used in combination with Anti-wear Ring double-purpose retaining ring BRL type.

â‘¢Prevention of oil leakage:

Sealing products made of polytetrafluoroethylene and nitrile rubber/PTFErubber; or seals made of nylon resin and nitrile rubber, which can be used in a wide range of applications with large pressure changes and fast sliding speeds According to the working condition, the input hydraulic pressure cutout is designed on the end face of the polytetrafluoroethylene ring to prevent penetration leakage. The maximum working temperature environment is minus 40 degrees Celsius to 160 degrees Celsius; the maximum working pressure is 50MPa.

SPGW piston seal

Material:PTFE+rubber elastomer+reinforced modified nylon
Temperature:Nitrile rubber -40~100℃
Speed:=1.0m/s
Pressure:≤50mpa

SPGO piston seal

Material:PTFE+rubber elastomer
Temperature:Nitrile rubber -40~110℃
Speed:=1.0m/s
Pressure:≤35mpa

SRUV piston rod seal

Material:NBR+thermoplastic polyurethane
Temperature: -35`90℃
Speed:=0.5m/s
Pressure:≤40mpa

SRS piston rod seal

Material:PTFE+NBR
Temperature:-40~110℃
Speed:=1.0m/s
Pressure:≤40mpa

SRCB piston rod buffer seal

Material:Polyurethane+modified polyoxymethylene
Temperature: -35~110℃
Speed:=1.0m/s
Pressure:≤50mpa

SRU piston rod seal

Material:Polyurethane
Temperature:-35~100℃
Speed:=1.0m/s
Pressure:≤40mpa

SRD iron case dust prevention

Material:Polyurethane+metal skeleton material
Temperature:-40~110℃
Speed:=1.0m/s

SRDI soft dustproof

Material:polyurethane
Temperature:-40~110℃
Speed:=1.0m/

SDS Dumbbell Seal

Material:polyurethane
Temperature: -35~110℃
Speed:=0.5m/s
Pressure:≤50mpa

SPG piston combination seal

Temperature:

NBR+Polyurethane + Modified Polyoxymethylene

Temperature:-35`110℃

Speed:=0.3m/s

Pressure:≤70mpa

SRNL piston rod seal

Material

NBR+Polyurethane + Modified Polyoxymethylene

Temperature:-35`110℃

Speed:=0.3m/s

Pressure:≤70mpa

SRDF Piston Rod Seal

Material

Polyester rubber

Temperature:-40`100℃

Speed:=1.0m/s

SDY Y-seal

Material:Polyurethane

Temperature:-35~110℃

Speed:=0.5m/s

Pressure:≤70mpa

KZT anti fouling ring

SDS Steffel

Piston main oil seal

oil seals,hydraulic oil seal,track link oil seal,TCV oil seal

Safe Seal Technology Co., Ltd. , https://www.sprsealkits.com