Process for lime slurry production

Abstract

A process for controlling scaling on and within lime slaking and handling equipment such as SDA atomizers and reducing lime usage by forming a mixture with at least one polymeric dispersant and a quantity of water and introducing the mixture to a vessel for preparation of a lime slurry.

Description

I. BACKGROUND OF THE INVENTION[0001]A. Field of Invention[0002]The present invention is directed generally to a method of preparing an alkaline-neutralizing agent. The present method described herein may provide a reduction in the alkaline chemical usage as well as a reduction in equipment scaling.[0003]B. Description of the Related Art[0004]Suspensions of alkaline-neutralizing agents may be used in a variety of diverse applications. Alkaline-neutralizing agents may be, for example, caustic solutions or lime slurries. Lime slurries can commonly be used in a water-softening process called “lime softening” where lime causes ‘hardness’ ions to precipitate from and settle out of solution, thus softening the water. In wastewater and process water applications, it can be desirable to use lime slurries instead of conventional caustic (often prepared from sodium hydroxide, or “NaOH”) solutions to adjust the pH of, or to neutralize acidic solutions on a commercial, municipal, and / or industri...

AI Technical Summary

Benefits of technology

The invention relates to a process for making an alkaline-neutralizing agent that can reduce scaling, reduce alkaline chemical usage, reduce waste ash, and reduce mercury gas emissions. The process involves adding a mixture of at least one polymeric dispersant and a quantity of water to a vessel for preparation of a slurry. This process is easy to implement and use. The technical effects of the invention include improved performance and efficiency during the production of alkaline-neutralizing agents.

Problems solved by technology

However, caustic solutions can be highly dangerous and must be carefully controlled to ensure that humans do not come into contact with these solutions, which can cause severe burns.

In addition, the solid NaOH particles that often can be used to make caustic solutions by dissolution in water also present serious health concerns, and their use, shipment, and storage must be carefully controlled; they are subject to numerous safety regulations.

Lime can be considerably less expensive than NaOH and also may be preferable from a health-safety standpoint, but handling problems associated with lime typically overshadow its use.

But using such high-content lime solids can be problematic because the resulting viscosity can render the slurries impractical or un-useful from a materials-handling standpoint.

However, creating lime slurries, especially a high solid version, can lead to scale.

One issue with using lime slurries can be scaling with the equipment.

For example, the increase in solids can result in very high viscosities and can also lead to increased scaling in the slurry-producing and conveying equipment as well as in other areas within the process.

The scaling can lead to maintenance issues, feed rate decrease, density changes, and reduction of stability in the sulfur oxide (SOx) levels in the SDA.

In addition, scaling may also increase lime usage.

Images