The invention discloses a shell and tube type heat exchanger and a control method thereof. The shell and tube heat exchanger comprises a shell, a pipe box, a pipe plate and a heat exchange pipe, wherein the shell is provided with an inner cavity, the shell is provided with a shell pass inlet, a shell pass first outlet and a shell pass second outlet; the shell pass inlet and the shell pass first outlet are located at the two ends of the shell correspondingly, the pipe box is at least arranged at one end of the shell, the pipe box is provided with an inner cavity, a pipe pass inlet and a pipe pass outlet are formed in the pipe box, the pipe plate is located between the shell and the pipe box, the heat exchange pipe is arranged in the inner cavity of the shell, the heat exchange pipe penetrates through the pipe plate to communicate with the inner cavity of the pipe box, and the ratio of the shell pass length between the shell pass second outlet and the shell pass inlet accounts for the shell pass length between the shell pass first outlet and the shell pass inlet is 1/5-1/3. According to the scheme, the problems that when the pipe shell and tube heat exchanger is operated under the variable working condition, a cooling medium adjusting valve cannot be in the interval with excellent adjusting characteristics and accurate control of the outlet temperature of a cooled medium is difficult to be realized according to the working conditions are solved.

Shell and tube type heat exchanger and control method thereof

The utility model discloses a heat transfer device for chlorine dioxide solution heating, it includes tubular heat exchanger, is equipped with the continuous tubulation of multistage in tubular heat exchanger's the casing, forms shell side and tube side in the casing, chlorine dioxide solution's business turn over pipeline body contact journey, the journey is taken over to the business turn over pipeline of filtrating, installs temperature transmitter and pressure relief device on chlorine dioxide solution's the export pipeline, installs temperature control valve on the inlet piping of filtrating. Use the utility model discloses, filtrating can select for use convenient and fast's physics washing mode to clear up after the tubulation inner wall forms scaling, can guarantee the interior chlorine dioxide solution pressure of device and in security range, avoid the incident to take place at technological requirement within range, the pressure relief device of installation through the chlorine dioxide solution temperature after the steerable heating of temperature control device of configuration.

A heat transfer device for chlorine dioxide solution heating

Provided is a method for preparing high-purity chlorine dioxide using a combination of methyl alcohol and hydrogen peroxide as a reducing agent. The method comprises: injecting concentrated sulfuric acid and sodium chlorate solution into a generator to form a reaction mother solution, making the reaction mother solution maintain an acidity of 5.8-6.2N, a sodium chlorate content of 234-266 g/L and a temperature of 69-73℃; then adding a reducing agent from the combination of methyl alcohol and hydrogen peroxide for reaction to generate chlorine dioxide gas and by-product neutral mirabilite; and cooling the chlorine dioxide gas generated by reaction and then absorbing same with chilled water of 4-10℃ to obtain a chlorine dioxide aqueous solution, and at the same time, filtering, washing and recycling the by-product neutral mirabilite. Compared with only using methyl alcohol as a reducing agent, the method can reduce the chlorine gas content in chlorine dioxide by 60-70%, and can reduce the sulfuric acid consumption by 14-20%; besides, the generated by-product is neutral mirabilite, needing no neutralization treatment for acidic mirabilite.

Method for preparing high-purity chlorine dioxide using combination of methyl alcohol and hydrogen peroxide as reducing agent

The invention discloses a method for preparing high-purity chlorine dioxide by using methanol and hydrogen peroxide as reducing agent. The method comprises: concentrated sulfuric acid and sodium chlorate solution are injected into the generator to form the reaction mother liquid. The reaction mother liquid shall be maintained a certain acidity, temperature and sodium chlorate content, and then it is reacted with the reducing agent (methanol and hydrogen peroxide) to produce chlorine dioxide gas and by-product sodium sulfate. The chlorine dioxide gas is cooled and absorbed by low temperature chilled water to obtain an aqueous solution of chlorine dioxide, and by-products are recycled. The chlorine dioxide solution produced by the aforementioned method has a 60-70% reduction in the Cl2 content and 14-20% reduction in sulfuric acid consumption than that of the chlorine dioxide produced by using a single methanol reducing agent, and the by-product produced is sodium sulfate, not sodium hydrogen sulfate, so neutralization reaction treatment is not required.

Method for preparing high-purity chlorine dioxide by using methanol and hydrogen peroxide as reducing agent

The invention discloses an apparatus and a method for comprehensive utilization of thermal energy in chlorine dioxide pulp bleaching. Heat exchange is carried out between normal temperature process water, which is used for producing ice water, and a low-temperature chlorine dioxide water solution, which is about to be added to pulp, so that after the heat exchange, temperature of the chlorine dioxide water solution is increased; then the chlorine dioxide water solution is mixed with the pulp, so that usage amount of steam for heating the pulp is reduced; furthermore, after the temperature of the process water is reduced after the heat exchange, the process water is sent to an ice water machine to produce ice water, so that the refrigerating load is reduced since the water inlet temperatureis reduced, thus saving energy.

Apparatus and method for comprehensive utilization of thermal energy in chlorine dioxide pulp bleaching

The invention discloses a method for preparing high-purity chlorine dioxide through combined reduction of methanol and hydrogen peroxide. The method comprises the following steps: injecting concentrated sulfuric acid and a sodium chlorate solution into a generator to form a reaction mother solution; maintaining certain acidity, temperature and sodium chlorate content of the reaction mother solution, adding a reducing agent composed of methanol and hydrogen peroxide, reacting to generate chlorine dioxide gas and a byproduct neutral mirabilite, cooling the chlorine dioxide gas, absorbing the same with low-temperature chilled water to obtain a chlorine dioxide water solution, and recovering the byproduct. Compared with chlorine dioxide produced by adopting a single methanol reducing agent, the chlorine dioxide solution produced by adopting the method disclosed by the invention has the advantages that the Cl2 content is reduced by 60-70%, the sulfuric acid consumption is reduced by 14-20%,the generated byproduct is neutral mirabilite, and acidic mirabilite neutralization treatment is not needed.

Xu Cuisheng

Papers

A heat transfer device for chlorine dioxide solution heating

Method for preparing high-purity chlorine dioxide using combination of methyl alcohol and hydrogen peroxide as reducing agent

Method for preparing high-purity chlorine dioxide by using methanol and hydrogen peroxide as reducing agent

Apparatus and method for comprehensive utilization of thermal energy in chlorine dioxide pulp bleaching

Method for preparing high-purity chlorine dioxide through combined reduction of methanol and hydrogen peroxide