Thermal Flowmeters for Wastewater Applications

Wastewater treatment plants ( WWTPs) or publicly owned treatment plants (POTWs) must operate 24/7 to satisfy domestic, industrial, and storm drain sources. Sewage treatment includes eliminating pollutants from wastewater and sewage (human waste, animal waste, soaps, and detergents) to create a safe fluid waste stream that can be reintroduced safely into the ecosystem and a solid waste appropriate for reuse (usually as fertilizer). The primary applications for flow meters in wastewater treatment settings measure blower air to each pool in the aeration basin and measure digester gas flow.

The aeration basin is an array of treatment pools containing aerobic bacteria that break down the pools' sewage. A blower adds the necessary dissolved oxygen (DO) to the aerobic bacteria in the aeration basin. Too little oxygen destroys the bacteria, and too much oxygen is expensive; running the aeration blower accounts for up to 60% of all wastewater power consumed.

Digester sewage is called "sludge." When bacteria is added to the digester, the sludge breaks down and releases gas. This digester gas is collected, compressed, it's excess moisture gets removed, and is then cleaned in a scrubber. The cleaned gas is sent to engines or fuel cells for power generation, boiler water heating (for steam or hot water), and excess gas burns off at the flare. Many extensive sewage treatment facilities use digester biogas to operate the plant, minimizing their grid power consumption.

Developing accurate flow rate data allows wastewater treatment facilities to more precisely manage digester production levels, enabling tighter controls on methane levels and flaring. Kurz Instruments provides a handy overview of where thermal flowmeters are applied and provide optimal performance. 

DOWNLOAD THE TECHNICAL PAPER HERE

For more information about applying flowmeters to wastewater applications in New England contact Piping Specialties. Call them at 800-223-1468 or visit their site at http://psi-team.com.

Thermal Flow Meters for Pulp & Paper Applications

Trees used in paper-making go through processing in a de-barker and a chipper, where they reduce to approximately one-inch wood chips. The wood chips are pressure cooked in a digester and become pulp, refined, turned into slush, and screened. Screening drains away liquid, and the resulting pulp is then pressed and dried into the paper. Several steps within the pulp and paper-making process create emissions that must be monitored and reported.

Creating paper pulp relies on a careful balance of low-velocity air flows among the various processes. For example, the recovery boiler following the digester modulates to follow the digester load changes. Additionally, a recovery boiler uses the black liquor's chemical reaction to generate heat for the boiler. It has three airflow systems requiring tight control to create stable air flows.

Kurz Instruments provides a good application note explaining the areas where thermal flow meter uses appear in the pulp and paper production process. You can download the application note below.

DOWNLOAD THE THERMAL FLOW METERS FOR PULP & PAPER APPLICATION NOTE HERE

For more information on instrumentation for pulp and paper mills in New England, contact PSI Controls (Piping Specialties, Inc.). Call them at 800-223-1468 or visit their website at https://psi-team.com.

An Innovative and Unique Solution for Measuring Dry Gas Flow in Wet Gas Environments

The Problem - Reading Dry Gas Flow in a Wet Gas Environment

Irrespective of any single manufacturer's claim, daily and seasonal temperature changes in wet gas environments cause erratic high flow readings in standard thermal flow meters. With standard thermal flow meters, as the flow flow temperature decreases, more water condenses out of the gas causing the standard thermal flow meter to misread the water contacting the sensor as dense air. Within an active condensing gas flow, the low overheat (less than 50°C) of standard flow meter products make them incapable of accurately reading the dry gas flow within a wet gas environment.

Kurz Instruments Develops a Practical Implementation of the Leidenfrost Effect to Overcome the Problem

The Leidenfrost Effect, named after 18th Century scientist Johann Gottlob Leidenfrost, is a phenomena that happens when liquid contacts a surface significantly hotter than the liquid’s boiling point.  A vapor layer is created between the liquid and the surface that keeps the liquid suspended, delaying the rate of evaporation. 

Kurz Instrument developed an innovative solution. By maintaining a high signal-to-noise ratio and a high sensor overheat, mist particles vaporize on impact with the heated sensor. Thus, by employing the Leidenfrost Effect, the leading edge of larger droplets vaporize to steam, which diverts the remaining water around and away from the heated sensor. The unique design of the WGF allows it to accurately monitor the dry gas component in a wet gas flow regardless of changing condensation levels.

The Kurz WGF flow meter for condensing gas environments includes features that allow them to outperform all other currently available thermal mass flow meters. Kurz was the first thermal mass flow meter manufacturer offering accurate and reliable condensing gas flow measurements. Their unique design centers around a high 300°C sensor overheat capability. The design also provides sensor overheat protection at zero flow through the incorporation of a unique temperature control and power limiting design. As a result, the Kurz WGF is not affected by water droplets in the flow stream. This unique technology establishes Kurz flow meters with WGF technology as the only thermal flow devices suitable for biogas and condensing gas environments found in digesters, landfills, animal feeding operations, mining, and wet stacks.

To learn more about The Leidenfrost Effect and how it applies to Kurz flow meters, visit this page.

To learn more abount Kurz Instrument products, call PSI Controls (Piping Specialties, Inc.) at 800-223-1468, or visit their web site here - https://psi-team.com.